p 0-2 0 -7 c:;

r

A

HISTOEY OF INFUSORIA,

rNrCLTJDING

THE DESMIDIACE^ AND DIATOMACE^,

BRITISH AND FOREIGN.

ANDREW PRITCHARD, Esq., M.R.I.,

AUTHOR OP THE 'MICROSCOPIC CABINET,' ETC.

FOURTH EDITION.

ENLAHGED AND EEVISED BY
.T. T. AELID&E, M.B., B.A. Lond. ; W. AECHEE, Esq. ;
-T. RALES, M.E.C.S.L. ; W. C. WILLIAMSON, Esq., F.E.S. ;
AND THE A.UTHOE.

ILLUSTRATED BY FORTY PLATES.

LONDON:
WHITTAKEE AND CO., AVE MAEIA LANE.

1861.

[ The right of fraiidafion is reserved.']

PBINTED BY TAYLOR AND FRANCIS,
RED LION COURT, FLEET STREET.

ALERE 8 FLAtUIAM.

PREFACE.

Special interest has always been taken by man in the structure and
development of the minute forms of life^ whether animal or vegetable :
in this volume I propose to lay before the reader a resume of the
present state of our knowledge of the multitude of living beings called
Infusoria. This term, as employed by Professor Ehrenberg of
Berliuj includes a wide range both of animal and vegetable life;
while it is now restricted by other naturalists to the Protozoa, and,
in the works recently commenced by Dr. Stein and MM. Claparede
and Lachmann, to the ciliated members of that group.

The former editions of this work having included a History of the
BaciUaria, Phytozoa, Protozoa (under the name Polygastrica), and of
the Kotatoria, it is incumbent on me to retain these groups, though
the researches of late years have so extended our acquaintance with
them that much diflSculty has been felt in the attempt to comprise
the whole in a single volume, so necessary for a practical manual.

The successful investigation of this department of Natural History
arose mainly from the improvement of the microscope consequent
upon the discoveries of "Test Objects" and "penetrating power,"
the latter depending upon "angular aperture," — discoveries whicli
'my colleague the late Dr. Goring and myself had the pleasure of
presenting to the public. The microscope, having become tlicreby a
reliable instrument, has revealed to us the true forms and structure of
these beings.

Part I. is devoted to a General History of the several more or less
natural groups of Infusoria : it contains also the observations and
opinions of British and Continental naturalists on their nature
structure, functions, and classification. The foreign writings on
these sulijects are so voluminous that even an abstract of them has
increased tliis part of the work much beyond what it occupied in

V

iv

niKFACE.

former editions, while the introduction of the Tables from Part II.
has further extended it ; but, as I have been anxious to give an
impartial account of the researches on tliis subject, a briefer summary
might have impaired its usefulness and value. To Dr. Arlidge is
due the rearrangement and preparation of this part.

Part II. contains descriptions of the Families, Genera, and Species
of the groups whose general history forms the subject of the preceding
part of this volume. The systematic arrangement of Ehrenberg has
been retained for the Phytozoa, Protozoa, and Rotatoria, the new
genera and species of other naturalists being collated and engi'afted
thereon. The descriptions of those curious and highly-organized
creatures the Rotatoria have been extended and revised by Professor
Williamson of Manchester, whose original researches and observa-
tions on this group are greatly appreciated, both in this country and
abroad.

In consequence of the long illness of Mr. Ralfs, who had under-
taken the revision of the Bacillaria, the publication of this edition has
been delayed, and that group has been printed last — a deviation from
the original design which it is hoped will not inconvenience the
reader, while it has allowed opportunity for the insertion of the latest
researches. Owing to the circumstance stated above, the revision of
the Systematic History of the Family or Subgroup Desmidiaceae has
been kindly carried out by Mr. William Archer of Dublin, who has
added some original views, expressing by symbols the characters of
certain genera ; moreover, M. de Brebisson of Falaise has given this
edition the benefit of his valuable co-operation, by furnishing descrip-
tions of the newly-discovered foreign species.

The elegance and variety of the forms, the beauty and elaborate
sculpturing of the silicious shells of the Diatomaceae, and the general
interest now taken in their study, rendered it desirable to bring together
in this volume all the known genera and species, British and foreign.
This I have been able to effect by the research of Mr. Ralfs, whose
name is so intimately identified with the knowledge of these organisms,
and whose present arrangement of their families and genera wiU no
doubt tend to facilitate our better acquaintance ■o'ith them. Owing to
tlie great dimensions Avhich this treatise has acquired, and the limited
space consequently at command, I was under tlic necessity of con-
densing the manuscript of Mr. Ralfs, and of introducing abbrcvi-

PREITACE,

V

ations. Still I have, iu accordance with my original design, given
every known specific name, whether synonym or variety, whereby
observers may avoid confusion in the nomenclature by not employing
the same names for newly-discovered forms. The references now
introduced are to works published subsequently to the early editions
of this book : for their verification I am indebted to Mr. Kitton
of Norwich.

Twenty-one new Plates have been added to this edition, of which
six are engraved by Mr. Tuffen West. In the case of the Diatoms,
all the new figures are drawn to one scale, representing a magnifying
power of 300 diameters; many of them likewise are drawn from
specimens, whilst others are engraved from original drawings kindly
lent by Mr. George Norman of Hull, Mr. Roper of Clapton, and
Mr. Brightwell of Norwich.

It now becomes my pleasing duty to acknowledge the kind assist-
ance received from the late Professors Gregory of Edinbm'gh and
Bailey of New York ; also to tender to Di-s. Donkin, Gkeville,
Francis, Wallich, Strethill Wright, and Mr. Gosse, along with
the gentlemen before named, my best thanks for their aid and advice
during the progi'ess of this laborious undertaking.

In conclusion, should the object proposed in the reissue of this
work be attained, viz. to produce in a single volume a compendium
of the present state of knowledge, calculated to promote and facilitate
the study of the very interesting branch of Natm^al History Avhicli
forms its subject, and which has occupied much of my leisure time
for more than forty years, I shall be fully content.

ANDREW PRITCHARD.

Oanonbui'y, London, N.
November 15, 18G0.

i

■I-

I

I

I

CONTENTS.

Preface Page iii

List of works quoted and abbreviations used herein . « ix

PAET I. — Geneiul History of Infusoria, etc.

BacillAria : Besmidiea, their figure, page 1 ; colour, consistence, envelopes, openings in
lorica, 4 ; movements and external cUia, 5 ; contents of fronds, 6 ; circulation of con-
tents, 7; reproduction, 11; habitats, distribution, appearance in masses and vital
endowments, vegetable nature and affinities, mode of collection, 20. — Fediastrcm, their
figm-e, composition, and contents of cells, 24 ; number and disposition of the ceUs in
the fronds, 25 ; development and grovrth, 29 ; systematic position, 30. — Diatomacece,
their general and external charactei's, 31 ; figure, 32 ; the silicious shell or lorica, its
divisions and structural composition, marldngs, stria?, canaUcidi, puncta, &c., 37;
contents of frustules, supposed digestive sacs, reproductive vesicles, &c., 47 ; move-
ments, then* character and causes, cilia, circulation of contents, respiration, 60;
nutritive functions, supposed stomachs, 56 ; multiplication, reproduction, and develop-
ment, 58; conjugation, 61; habitats, appearance in masses, abundance, 75; geogra-
phical distribution, 79 ; geological importance and fossil accumulations, 82 ; aerolitic
Diatomeoc, 85 ; uses of Diatomaceous deposits, 86 ; of the nature of DiatomejE, whether
animals or plants, various hypotheses, 87; determination of species and genera,
varieties, classification of Kiitzing, Smith, and others, 96 ; on the mode of obtaining,
preparing, and preserving specimens, 102.

Phytozoa: the beings included under this name, their general character, division into
groups or tribes, their figure, coverings. 111; cell-contents, 113; movements, 117;
process of nutrition, 119; multiplication and rejDroduction, fission, macrogonidia,
microgonidia, 120; encysting process, condition of rest, 123; phases of being and
alternation of generation, 124 ; on their nature, animal and vegetable charactei-s, 128 ;
habitats, occiu-rence in masses, colour caused by then- accumulation, 129. — Families :
Monadina, 130; Cryptomonadina, \4Q ; Folvocina, 144 ; Vibrionia, 1S4; Astasiwa at
Euglmma, 188 ; nature of Astasisea, 196.

Protozoa, Wd.—BUzofoda, 201; movements of contained particles, 210; nucleus, 211;
reproduction, 213 ; of the testaceous shells of Monothalamia, 218 ; shells of Po'lytha-
lamia or Foraminifera, 222; dimensions and conditions of life, 227; habitats and
distribution, 229 ; of their cell-nature and characters as individuals or as colonies of
animals, 232 ; on their affinities, 234 ; classification, 237. Actincrphryina, 243 ;
movements, 246; prehension and entrance of food, 247; contractile vesicle, 250 •
nucleus, 252 ; encysting, fission, gemmation, embryos, 253 ; conjugation, 256 ; loca^
lities, affinities, 257. Acinetina, 258 ; origin and development, 261. Greqarinida
262. Psorospermia, 265. Ciliata, 266. Subgroup A. Asfoma: OpalincBa, their
general characters and functions, 267 ; nucleus, self-division, supposed embryos, 269 •
habitats, vital endowments, natiu-e, affinities, classification, 270. PeridinicBa ' 271 •
contents, 274 ; reproduction, 275. Subgi-oup B. Stomatoda : dimensions, 277 ; figure'
278 ; consistence, 279 ; integument, markings on siu-face, spines, lorica, 280 ; exteruai
sheaths or cases, 282; cilia and ciliary action, 285; locomotive and fixed forms
varieties of locomotion, transitory power of locomotion among tiie attached goner-i'
288 ; structure of pedicles, 292 ; compound special organs of locomotion and pre-
hension, the peristom and rotary or ciliated disc, the spirally-coiled head of Sniro
chona, 2^4.— Ciliated Prnfnzoa, internal organization : subtegumentary layer chloro'
phyll, thread-cells, 297; muscles, 300; organs of digestion, nutrition, and secretion
301; the polygastnc hypothesis, 303; dental apparatus or teeth, 311- contractile
vesicle 312; nucleus, nucleolus, 326; ovules, 334; spermatozoids, 337; accessory
^n^n l'l^q" r^l' ""^^^T.^"*' 8pl»erical colls, Bupposcd glands, 338; circulation of
contents, 339. The encysting process, 341 ; reproduction, fission, gemmation, internal

Vlll

CONTENTS.

ova producing germs or embryos, impregnation, production of new beings with and
without metamorphosis, transtbriniition into Aeineta;, .34r); nature of Ciliated Pro-
tozoa, their existence as inde])endent organisms, ecll-tlieory apjjliod lo tlicni, .'3(58;
conditions of life, ^70; succession of species, 371; dm-alion of life, influence of
external agents, heat and cold, 373 ; necessity of air, chemical agents, electricity and
galvanism, 374; aflinities with other animals, geographical distribution, 375 ; classi-
fication, 376. Subgroups of Ciliated Protozoa: Ichthydina, 380; Noctilucida, 382;
Bysteria, 387.

Rotatoria or Rotipeea : general characters, 392 ; appendages, 397 ; the muscular system,
406 ; movements, 409 ; the digestive system, 410 ; reception of food, its deglutition,
420 ; the secreting system, 422 ; the vascular and respiratory systems, 426 ; the
nervous system, organs of sense, psychical endowments, 434; reproductive organs,
441 ; formation of ova, 442 ; development of embryo, 445 ; the embryo-metamor-
phosis, 447 ; vrintfir ova, 450; male Rotatoria, 463; duration and conditions of life,
habitats and distribution, 463 ; affinities and classification, 468 ; Ehrenberg's classifi-
cation, 478 ; Dujardin and Leydig's classifications, 480.

Tabdigrada : their structiire, habitats, and aflinities, 482.

PART II. — A Systematic History of Infusoria, with Descriptions of the
Families, G-enera, ahd Species.

Group Phytozoa. Families : Monadina, 485 ; Hydromorina, 503 ; Cryptomonadina, 505 ;
Volvocina, 514; Vibrionia, 529; Astasiaea or Euglensjea, 538; Dinobryina, 547.

Group Protozoa — Subgroup Ehizopoda, 547 : Amoebfca, .548 ; ArceUina, 551 ; Actino-
phryina, 558 ; Acinetina, 564. — Subgroup Ciliata, 568. Astoma : OpaUnaea, 569 ;
Cyclidina, 571 ; Peridinicea, 574. Stoviatoda : VorticeUina, 579 ; Ophi-ydina, Vaginifcra,
598; Enchelia, 605; Colepina, 616: Trachelina, 616; Ophryocercina,.630; Aspidis-
cina, 631 ; Kolpodea or Colpodea, 631 ; Oxylrichina, 639 ; Euplotina, 645.

Group Rotatoria. Families : Ichthydina, 660 ; OEcistina, 663 ; Megalotrocha\i, G64 ;
Floscularia, 665 ; Hydatinasa, 677 ; Albertina, 693 ; Euchlanidota, 693 ; Plulodincea,
700 ; BrachionsEa, 706.

Group Tardigrada, 713.

Group Bacillaeia : Desmidiaceaj, 715 ; Diatomaceis, 756.
Index to the Illustrations of the Diatomaceae, 941.
Description of the Plates, 949.
Index to the Families and Genera, 965.

LIST OF ABBEEVIATIONS

OF

WOEKS AND AUTHORS' NAMES EEFEEEED TO IN THE
PEESENT EDITION.

Abliandliingen der Berliner Academie der Wissenschaften.
Abhandlimgen der Senckenbergischen Gesellschaft in FrankfiU't am Main.
Ag CD. or AD. Agardh's Conspectus Diatomorum.
ANH. Annals and Magazine of Natural History.

Anat. d. wbeUos. Thiere. Siebold, C. Th. von. Lehrbuch der vergleichendeu

Anatomie der wirbellosen Thiere. Berlin, 1848.
Ar. or Ai"n. Professor G. Wallrer-Amott, LL.D.
ASA. or AA. Agardh's Systema Algarum.
ASN. or Ann. d. SN. Annales des Sciences Naturelles, Paris.
B. or Bai. Professor Bailey of New York.
BAJ. Professor Bailey, in American Joiu'nal of Science.

BO. or BSC. Professor Bailey's Contributions to Knowledge, Smithsonian Insti-
tution.

BMO. Professor Bailey's Microscopic Organisms
Boston Jom-nal of Natm-al History. 1853.

Braun, A., Prof. Algarum Unicellularum Genera nova aut minus cognita. 1855.

Br(5b. M. de Brebisson of Falaise.

BD. M. de Br^bisson's Diatomacese of Cherbourg.

Bn. T. Brightwell, Esq., Norwich.

Brit. Assoc. Transactions of the British Association for the Advancement of
Science.

British Desmidiese. By John Ealfs. 1848.

Brit, and Foreign Med. Rev. British and Foreign Medico-Chinirgical Review.
Bulletin de L'Academie de St. P^tersbourg, xiii. 1855.
Cai-penter, Dr. W. B. The Microscope.
Carus. Icones Zootomicse. 1858.

Cohn, E. S. Professor Cohn on the Structure of Protococcus ^j^mj-w/w. Ray

Society, 185.3. London.
Comptes Eendus de rj\.cad(5mie Imperiale des Sciences.
D'Orbigny, Alcido, Foraminiferes Fossilcs, 1840.

Duj. or Du. Duiardin, F., Ilistoire Naturelle des Zoophytes. — Infusoires. Paris,
1841.

E., Eh., or Ehr. Professor Ehrenberg, Berlin.

EA. Professor Ehrenberg\s Mikroscopischen Lebens in Auierika.

Edin. New Phil. Joum. Edinburgh New Pliilosophical .lournal.

Einzell. Alg. Niigeli, Prof., Gattuugen einzelliger Algeu. Zurich, 1849.

EI. or Inf. Professor Ehreuberg's Die Infusiouathiercuen.

EK. Professor Ehrenberg's ICreidethierchen.

EM. I'rofessor Ehrenberg's Milcrogeologie.

EEBA. or EB. or EE. Professor Ehrenljerg in Eeports of Berlin Academy.
Ehrenberg, Prof. Passatstaub und Blutregen.

X

LIST OF ABBREVIATIONS, ETC.

Entx^ Colin,_^Pi'of. F. Entwickelimgs-geschichte der miki-oskopisclien Algen uiid

Fauna Infusoria, Noifolk. T. Briglitwell, Norwich.

Gr. Dr. E. K. GreviUe.

GBF. Dr. R. K. Gre^ille's British Flora.

GCF. Dr. R. K. Greville's British Cryptogamic Flora.

Greg. Dr. Grejjory of Edinburgh.

GDC or GC. Dr. Gregory's Diatomaceas of the Clyde.

HBA. Ilassall's British Al^te.

Jones, T. Rymer, Prof. A General Outline of the Animal Kingdom. London,
1841.

K. or Klitz. Professor Kiitzin*.

KA. or KSA. Professor Kiitzing's Species Alganun.

KB. Professor Kiitzing's Bacillarien.

Kiitzing. Phjcologia Germaiiica. 1845.

KTi. Die klemsten Lebensfomien.

KSD. Professor Kiitzing's Synopsis Diatomeorum.

Linntea, xiv. 1840.

Lyngb. Professor LjTigbye's Tentamen Hydi-ophytologife Danicse.
Medical Times. London, 1856. Professor Huxley's Lectures.
Me. or Men. Professor Meneghini.

Meneghini, R. S. Professor Meneghini on the Animal Natiu'e of Diatomese. Ray-
Society. London, 1853.
Mem. de I'Acad. Roy. Belgique. M(5moires de I'AcadiSmie Royale de Belgique.
Micrographic Dictionary, The. By Dr. Griffith and Prof. Henfi-ey.
Microscopic Illusti-ations. By C. R. Goring, M.D., and Andrew Pritchard.
Mittheilungen der Natiu-forschenden Gesellschaften in Bern. 1849.
MJ. or JMS. Jom-nal of Microscopical Science.
Monatsb. Berlin. Acad. Monatsbericht der Berliner Academie.
MT. or TM. or TMS. Transactions of Microscopical Society.
Miiller's Archiv. Ai-chiv fiir Anatomie imd Physiologic. Von Dr. J. Miiller.
Miiller, 0. F. Prof Animalcida Infusoria.
Na. or Niig. Professor Nfigeli.

Nat. Hist. Review. Natm-al History Review, Dublin.

Nov. Act. Acad. Cuiios. Nova Acta Academise Natm'se Curiosorum.

Owen, Richard. Lectures on the Invertebrate Animals. London, 1843.

Owen, Richard. On Parthenogenesis. London, 1849.

Ph. Professor John Phillips, F.R.S.

Phil. Trans. Philosophical Transactions of the Royal Society of London.

Perty, Max., Dr. Ziu- Kenntniss kleiuster Lebensfonnen. 1852.

Proceedings of the American Association for the Advancement of Science.

Proceedings of the Boston Society of Natural Historj^

Proc. Roy. Soc. Proceedings of the Royal Society of London.

Proc. Roy. Soc. Edin. Proceedings of the Royal Society of Edinburgh.

Proceedings of the Academy of Natiual Sciences of Philadelphia. 1853.

Rab D. or RD. Dr. Rabenliorst, Die Siisswasser Diatomaceen.

Ra. or R. Mr. Ralfs.

R.S. Ray Society's publications.

R.S. Reports. Ray Society Reports.

Rejuv. R.S. Braun, A., 'Professor, On the Phenomena of Eejuveuescence in

Nature. Ray Society. London, 1853.
Ro. F. C. S. Roper, Esq.

Schleidon, J. M., Prof. Principles of Scientific Botany : translated by Dr. Lau-
kester. 1859.

Schultze, Dr. Max S. Ueber den Organismus der Polj'thalamien. Leipzig, 1854.
Schneider, Ant. S^Tiibolas ad Infusoriorum Ilistoriam Naturalem Dissertatio In-

auguralis. Berlin, 1854.
Sh. or Shadb. G. Shadbolt, Esq.

Sill. JoiuTi. Sillimau's American Jom-nal of Science and Arts.
S. or Sra. Professor Smith.

SBD. or SD. Professor Smith's S^niopsis of British DiatomaceaJ.
Stein, F., Prof. Die Infusionsthiere, auf ihre Eutwickelungsgescliichte.

EIULVTA, ETC.

xi

Ti-ansactions of the Pliilosophical Societ)- of Manchester.
Transactions of the Medical and Physical Society of Bombay.
Untersuchungen iiber die Familien der Conjugaten. By Professor de Bory.
Van der Hoeven. Lehrbuch der Zootomie. 1850 & 1856.
Wag'ner. Zootomie.

Wieomann's Archiv. Archiv fiii' Naturgeschichte. Von A. F. A. Wiegmann.
Williamson, Prof On the Recent Foraminifera of Great Britain. Ray Society.
London, 1857.

Zeitschr., or Siebold's Zeitschr. Zeitschrift fiir wissenschaftliche Zoologie. Von
Cai-1 T. von Siebold imd Albert KoUiker. 1848-59.

Note. — The names of Ehreuberg, Dujardin, Perty, and Siebold are frequently
mentioned without particular notice of the work quoted ; but the treatises intended
are those in which each of those several authors has given a general historj' of
Infusoria, and which are named in the above list. So, in the accoimt of the
Rhizopoda, Schultze is often quoted, his special work on their -organization being
refen-ed to ; and lastly, in the History of the Rotatoria, the opinions of Leydig are
all derived from his essays in Siebold's 'Zeitschrift.'

For abbreviations employed in Systematic History of Desmidiacese, see p. 721.

Note. — The references to the engi-avings in this work are printed thus :
(xn. 20.) for Plate XH. fig. 20.

EEEATA, ETC.

Page 10, line 8 from bottom, dele See Appendix at end.

— 218, line 7 from top, for Poraminifiera read Foraminifera.

— 243, line 7 from bottom, for peuliarity read peculiarity.

— 253, line 3 from top, for Actinophrga read Actinophrys.

— 259, line 4 from bottom, for XVIII. read XXIII.

— , 316, line 6 from bottom, for Leuekhart read Leuckart.

— 324, line 14 from bottom, for Wagener read Wagner.

— 470, line 7 from top, for 1855 read 1858.

— 535, line 6 from bottom, after figured, insert subsequently.

— 726, col. 2, line 20 from bottom, itisert segment 3-lobed, before lateral lobes.

— 726, col. 2, Hne 1 1 from bottom, for side read sides.

— 729, col. 2, line 25 from bottom, dele comma after surface, and insert after middle

— 732, col. 2, line 22 from bottom, for finely read finally.

— 735, insert " C. aciculare (West).— Elongated, very slender, straight, except at extre-

mities." or

— 741, col. 2, transpose reference to figure from S. glohulatum to <S. bacillare.

— 744, col. 2, line 34, ior imradoxuni read tetracenm.

— 753, line 18 from top.yb;- Pcdiastrium read Podiastrum.

— 758, lino 5 from bottom, dele Synedrcas. {See p. 910.)

— 760, col. 1, Uno 28, after capitate, insert striaj.

— 761 , col. 1, liiio 4 from bottom, for 159 read 150, and insert xi. 1-8

— 7G4, for E. Terra read E. Serra.

— 765, col. 2, line 2 from bottom, for Argus read Arcus.

— 768, after Q-enus Oncosphenia, insert Genus Podosphenia from p. 769.

— 771, col. 1, Une 14, for broadly read loosely.

— 772, col. 2, Uno 5 from bottom, for pear-like read pearl-like.

— 77-3, col. 1, line 10 from bottom, yo?* III. rcac^ xm.

— 774, col. 1, line 5, insert (iv. 32.) ■ "

— 775, transpose Odontidium mosodou to end 0. hyemalc as si/n

— 775, ior "O.pinnatt^n" vQadpinnulatum.

xu

EUEATA, ETC.

Page 777, end of F. viresce^is, insert (ix. 176.)

— 778, line 6, after Ealfs, insert . —

— 779, liefore Genus Nitzschia, insert Fam. characters of Sui-ii-ellete from p. 783 • and seo

Note, p. 940.

— 781, col. 1, line 2 from bottom, for 20 read 21.

— 783, col. 1, line 12, for 22 read 23.

— 784, col. 1, line 5 from bottom, for 2, 3 ; read 24.

— 784, col. 2, line 22 from bottom, for 19 read 20.

— 7SG, S. pulcbella, insert (iv. 28.)

— 789, S. fulgens, insert (xiii. 20.)

— 791, col. 1, line 2, for xviii. read viir.

— 796, S. striatula, insert (ix. 137, 138.)

— ■ 798, col. 1. Uue 24, for diTiduate read dimidiate.

— 799, col. 1, line 21 from bottom, for magnificent 7-ead marginal.

— 802, col. 2, line 14, for xv. read xu. ; Ime 29, for xv. read xii. ; last figm-e, for 56

read 50.

— 806, Gompbogramma rupestre, insert (rv. 46.)

— 800, Tetracyclus lacustris, insert (viii. 10.)

— 809, Gepbyria incm-vata, i7isert (v. 50.)

— 809, Gepbyria media, insert (v. 49.)

— 809, Euplemia pulcbella, insert (vin. 2.)
— ■ 812, for C. undulata read C. undata.

— 821, col. 2, line 6, after ochracea, insert (Ealfs) from next line; and after ferruginea

insert (Ebr.).

— 836, col. 2, line 8 from bottom, for x. read xi.

— 844, A. Kittoni, insert (viii. 24.)

— 851, col. 1, Une 17 from bottom, for nervosa read enervis.

— 8G3, Dicladia Capreolus, insert (vi. 28.)

— 875, Cymbella Arcus, insert (vii. 78.)

— 891, col. 1, Une 2 from bottom, for xii. read xi.

— 893, for "N. dissimilis (Eab.)" read "N. clepsydra (Ealfs)."

— 903, for " N. producta " read " N. extensa."

— 911, S. Fulmen (Breb.), read " S. Fulmen (Bri.)," and insert that species after S. con-

stricta.

— 923, col. 1, last line, for (viii. 43.) read (viii. 48.)

— 929, col. 1, top line, for octocarpoides read ectocarpoides.

— 938, col. 1, line 9, for " C. radiata " read " C. stylorum." ^

— 941, Actinoptychus Jupiter, now Actinocyclus Ebrenbergii.

— 952, in description of Plate VII., insert " 78. CymbeUa Arcus, to right of fig. 42.

79. Amphora monUifera, to right of fig. 49." [Note. The engraver has omitted
the numbers to these two figures in that Plate.]

WORKS BY THE SAME AUTHOK.

MICROSCOPIC ILLUSTRATIONS, with Descriptions of the New Microscopes,
Rules for constmcting them, and Directions for their management.

MICROSCOPIC CABINET, -svith Descriptions of the Jewel and Doublet Micro-
scopes, Test Objects, &c.

MICROGRAPIIIA, with practical Essays on Eye-pieces, Solar and Gas Micro-
scopes, &c.

NOTES ON NATURAL HISTORY, selected from the 'Microscopic Cabinet,"
with 10 colom-ed Plates from original Dra^^^ngs by C. R. Goring, M.D.

MICROSCOPIC OBJECTS : Animal, Vegetable, and Mineral.

A LIST OF ENGLISH PATENTS for the first Forty-five Years of the present
Century.

PAET 1.

A GENERAL HISTORY OF INFUSORIA.

Sect. I.— OF THE BACILLARIA.

Under this designation, contrived by Ehrenberg, two families of microscopic
unicellular Alg£e are comprehended, viz. the Desmidie^ and the Diatome^.

The Diatomeae differ from the Desmidieae chiefly by their dense siUcious
envelope, composed of two opposite portions or valves and of an interposed
segment, and by the general absence of the usual green colouring matter of
plants — chlorophyll or chromule. The Desmidieae, on the contraiy, have a
non-sihcious envelope, sepai'able into two segments, and filled with bright
grass-green chromule. In various vital phenomena the two tribes accord ;
but-whilst the Desmidieae are all but universally admitted to be plants, the
Diatomeae are still regarded by many to be of an animal natiire. With respect
to this question, the arg-uments pro and con. will be best understood when
the organization and vital endowments of these beings have been discussed.

I.— OF THE FAMILY DESMIDIEiE OE DESMIDIACE^.
(Plates I. II. III. and XVI.)

The Desmidieae are (pseudo-)imicellular Algae of a' herbaceous gi-een colom-,
of fi-eshwater habit, and have a membranous lorica composed of two symme-
trical segments or valves. In Kiitzing's arrangement (S_p.Alg.), the Desmidiete
constitute a family of the Chamaephyceae, a suborder of the class Isocai-pece.
Ehrenberg treated the genus Closterium as a distinct family, which he placed
between the Vibrionia and Astasiaea, with the name Closterina.

That the Desmidieaj are actually unicellular (in the sense of fonuin"- a
single enclosed cavity), Mr. Ralfs has, in his most valuable monograph on the
fimuly (1848), taken much pains to demonstrate. Owing to the veiy deep
constriction of the fronds of many genera, e. g. of Euastrum and Micrastcrias,
the appearance of the littlo organism is that of two cells united by a narrow
band (I. 1, 2, 24, 26, 27; II. 18, 28), forming, in Ehrcuberg's opinion, a
binary cell or frustule. However, between such deeply partite foms, and
others in which no constriction is perceptible, for instance in Closterium
eveiy intermediate gradation is met with. Other evidence of the unicellular
stnictm-c is afforded by the phenomena of conjugation and of the fonnation
of sporangia, by the newly-formed segments resulting from sclf-fission bcino-
intei-posed between the old valves, and by the fact that the entire contents
will escape through an opening made in either valve. Moreover, in several
genera the ciixulation of portions of the contents throughout the frond, from
one segment to the other, clearly demonsti'atra the continuity of their interior

Figure.— There is great variety in the figm-e of De8micHe{t), and much

2

GENEHAL HISTORY OF THE INFUSOEIA.

beauty. This will be best illustrated by reference to the Plates I. and II, ; for
description alone would fail to convey even a tolerably accm-ate conception.
In Micrasterias (I. 18, 20, 21) the fmstule has a general circular outUne, but
is bipartite and variously cut. In Euastrum (I. 23, 24, 26 ; II. 10) it is
bipartite, and each valve deeply sinuated. In many species of Cosmartum
(I. 1, 2 ; II. 33) the constriction is much shallower, the valves hemispherical,
and their margin entire. In Staurastrum (I. 31-34 ; II. 3, 7) each segment
is more or less irregularly produced at the extremities into hom-Hke pro-
cesses. In Penium, Docidivm, and Closterium (II. 1, 2, 9, 14) the frond is
elongated and wand-Kke, without constriction, or with only a very faint one,
and in many species is, moreover, curved or crescentic. Not a few genera
present numerous fronds united together ; the outline of the compound being
will consequently vary, both according to the figure of each individual frond,
and especially to the mode in which the several fronds are united. Thus in
Hycdotheca, Desmidium, and other genera (II. 35, 37, 39), the quadrate
fronds are united side by side in single series, so as to form a chain or
filament, in other words are concatenated.

The lateral view or cross-section of the fronds fui-nishes valuable characters,
and is largely made use of by Mr. Ealfs with that object, especially to distin-
guish between the several filamentary species. His figures show that the
fronds may be more or less compressed, and consequently offer on a transverse
section (end view) an oval and more or, less acuminate form (I. 25 ; 11. 23,
29), further modified by the elevations and depressions which the sui-faces
possess (I. 25 ; II. 23). In other cases the section is cii'cular, e. g. in Hya-
loiheca and Didymoprium (II. 32, 38), whilst in others, again, thi-ee or four
sides exist which are commonly concave, as in Desmidium (II. 40).

The end view exhibits the arrangement of the mass of chlorophyll, which
in some instances would appear to be peculiar and determinate of species.

The appearance of the Desmidiese is much modified by the sinuosities,
eminences, depressions, and processes, as well of the siu'face as of the margin
of the fi'onds, and also by the depth and width of the central constriction.
The surface may be dotted over irregularly, or more often regularly : the dots
themselves are in most cases elevated points, and in fewer instances depressions.
An irregular distribution of minute dots produces a granular-looking surface
(I. 24 ; II. 23, 30). Where the spots are larger their elevated character
becomes evident on the margin, to which they give a finely-toothed or dentate
appearance, e. g. in Cosmarium (I. 1, 2, 3). In some elongated forms, such
as Tetmemorus and Penium (II. 15), the puncta are disposed in lines parallel
to the length : in Docidium, however, the disposition, so far as regular, is
transverse. In several examples the surface is marked by elevated hues or
by ftuTOWs (II. 6). Such markings seem peculiar to the elongated genera,
particularly to Clostenum.

Many apparent lines are resolvable by higher magnifying powers into rows
of puncta. Where the lines arc fine, they are said to produce a striation of
the surface, as in Closterium attenuatum and C. acerosum. ; where they ai-e
more distinct they are temied costfc, and the surface they cover is costate or
ribbed, as in Closteriimi costatum and C. angusfatum. In general, in order
to discover the striation of the surface, tlie fronds must be ^•icwed when
empty ; sometimes indeed the lines can be made out at the extremities wliich
are unoccupied by chlorophyll.

The striae and costse of Closterium and Penium referred to are disposed
longitudinally, but frequently they are intersected at one or more points by a
transverse lino. In these spindle-shaped genera, where no constriction is
found, one such transverse line, usually central, is constant, and indicates

OF THE DESMIDrEiE,

3

the point of sepai-ation into two valves (II. 1, 2, 9). Each valve again is
occasionally subcli\ided by another line (II. 6, 15). These lines may be
single or double, and in the case of the middle suture their number may be
more multiplied, as in Clostenum Uneatum and G. Balfsii. The median
sutiu-al line is evident in other genera, e. g. in Hyalotheca, Cosmarium, and
Euastrum (II. 35). In several it takes on a fm-ther development, and
becomes an elevated lidge or band, appearing, in a front view, as a double
Une, terminating on each mai-gin in a dentation. Instances occur in Docidium
and in Didymopriimi (II. 9, 39). Such double lines are also sometimes met
with on each side the median suture, and at others, among the concatenate
forms, at the junction-surfaces of connected fronds.

That the dots or puncta on the smf ace of the fnistules are commonly small
elevations has already been stated; a further development of such into
papillae or minute spines crowned by a globular apex is seen in Micrasterias
papillifera ; whilst in many Cosmaria and Staurastra, the edge or the entire
surface is bedecked by fine hair-like spines or by obtuse ones, looking on the
margin like crenations (I. 1, 2, 3). When short and stout, many elevated
processes of the surface are called tubercles (II. 16, 17) ; when long and
tapeiing, they constitute spines, and in this form may be either straight or
curved : such are especially produced from the angles of the fronds, as in
Artlirodesmus (II. 18, 28). Among the Staurastra, illustrations of forked
spines (II. 3, 7) are found ; whilst among sporangia of many species, spinous
processes, besides tubercles and other appendages, are highly developed (II.
22, 25, 34) and attain theu- most complex conditions.

The modification of surface in several genera seems due, not to mere simple
appendages, but to positive expansions of the limiting membrane itself into
thick processes, which in their turn usually end in spines ; instances occur
in Xanthidium and Staurastrum (I. 27, 28 ; II. 3, 7, 20, 25). Generally
these large productions from the surface occupy constant and defiiiite positions,
such as the extremities, the rounded angles of the fronds, or a margin, and
are rarely indifferently placed. A general distribution over the surface is
rather characteristic of Xanthidium (I. 27, 28). In Eiuxstrum the sui-face is
throvra into very broad round swellings, hence called inflations ; such may be
presumed to be constant in number and position (I. 24, II. 30, the empty
divided fronds).

The margin of the more flattened, and the extremities of the elongated, spe-
cies furnish important specific and generic characters. Micrasterias has its
margin deeply incised into lobes (1.18, 20, 21, 22), which, with reference to the
centre of the frond, have a radiating arrangement, and are themselves incised
or inciso-dentate. The fronds of Euastrum are more or less deeply sinuated
(I. 23, 24, 26 ; II. 10), and the intermediate lobes produced vaiy both in
dimensions and outline. Where the lobes on the margin of fronds are small
and little prominent, they constitute crenations and dentations which may
occur singly or in pairs ; in the latter case, the margin so modified is said to
be bidentate or bicrenate (I. 1, 2, 3; II. 31, 26, 37). For example, some
fronds of Euastrum hinatum are bicrenate on the sides, and those of Didy-
moprium at the angles of the filaments (II. 39), whilst bidentate frastuies
are seen in Desmidium (II. 37), and in Hyalotheca mucosa. It has been
before remarked that when the surface is covered by tubercular eminences
or conical granules, a dentate outline is produced ; instances of this occur in
Eiuistrum verrucosum and in several Cosmaria. Another variety of margin
exists, known by the tenn midulated or wavy, where its elevations and de-
pressions are comparatively shallow. Lastly, the general concavity or the
convexity of the margin furnishes other specific characteristics.

4

GENEEAL HISXOBT OP THE INFTTSORIA.

Among the variations in the ends of the fusiform or elongated genera may-
be noticed the notched or emarginate apices of Tetmemorus (II. 12) ; the
truncate extremities of Bociclium (II. 9, 10), sometimes also, as in Z>.
Ehrenhergii, tiiberculate ; and the more or less acutely conicsd apices of
Closterium, prolonged in some species, as in 0. attenuatum, by an abrupt
contraction of the fi'ond into a conical process — in others, as in O. setaceum
and C. rostratum, by the gradual tapering of the whole frond — into long
rostrate or setaceous beaks.

CoLotna. — This is due to the endochrome or internal substance, which is
usually of a herbaceous green colour, and often diffused pretty uniformly
throughout the fronds, sometimes however leaving intervals at which the
enclosing membrane (lorica, Ehr.) becomes visible. This lorica is itself
mostly colourless ; yet in several species of Closterium and Penium it has a
reddish-brown tint (II. 5, 6, 15). The green colouring matter of the interior
is identical with that of plants, i, e. it is chlorophyll or chromule, and con-
sequently undergoes a change of coloui* in autumn, becoming, Kke the leaves
of plants at that season, a reddish-brown. When this change occurs, it is
equally indicative of the termination of Hfe.

Consistence. — Envelopes. — The hmiting membrane of Desmidiacese is
fli'm, though flexible ; it exhibits some elasticity and considerable resistance
to pressure, is not brittle, and not readily decomposable. Traces of silica are
found in a few species, but not, says Mr. Ralfs, " in sufficient quantity to
interfere with their flexibility." It is Hned by a softer flexible membrane ;
and besides this, the DesmidiesB generally have an external mucous or gela-
tinous covering, mostly so transparent and homogeneous as to be overlooked.
To bring it into view, it is a common plan to add some coloiuing matter to
the water in which the organism is viewed ; but good manipulation with a
high power will frequently succeed without recourse to this expedient to
demonstrate it. The particles of colour diflPused about the frond, and indeed
any external bodies, such as small vegetable cells, are seen, not in contact
with the fronds, as they would often be if these were naked, but kept at a
distance corresponding with the width of the hyaline envelope (I. 15 ; II. 35).
In Didymoprium Grevillii and Sfaurastrum tumidum the mucous sheath is
distinct and well defined ; " in others (to quote Mr. Balfs) it is more atte-
nuated . . . . , and, in general, its quantity is merely sufficient to hold the
fronds together in a kind of filmy cloud which is dispersed by the slightest
touch. When they are left exposed by the evaporation of the water, this
mucus becomes denser, and is apparently secreted in larger quantities to
protect them from the effects of drought."

The lining or the primordial membrane of the finn lorica is thin, colourless,
and highly elastic, and altera its contour with the varying movements of the
endochrome which it immediately invests. It is in contact with the out«r
case only at some points, mostly about the centre, and being elsewhere free,
an interval exists between the two envelopes. This elastic lining is acted on
by various chemical reagents ; for instance, it is contracted or coiTugat<?d by
iodine and by acids.

Openings in Lokica. — Openings have been represented by several writers
in the firm envelopes of Dcsmidictc, and more particularly in those of Clos-
terium. Ehrcnborg, for instance, stated that apertures existed at the extre-
mities, through which soft, very short, and conical transparent papiUas
slightly protruded to serve as locomotive organs. Both Mr. Varley and Mr.
Dalrj-mple also desci-ibed tenninal orifices, closed within, liowevcr, by a mem-
branous envelope ; but neither they nor any other obscrvcra have detected
the papilla-like locomotive organs Ehrenbcrg represented. " In no instance

OF THE DESMIDIEiE.

5

(Mr. Ralfs says) can any portion of the contents of the cell be forced out from
the exti-emitios." More recently !lie belief in terminal apertures has been
revived by. the published researches of the Eev. Mr. Osborne and others
(J. M. S.), who affirm, that not only the outer hard case, but also the mem-
bi-anous lining is penetrated by foramina, through which water enters from
without into the cavity of the frond. Another writer in the Mic. Journ., Dr.
"VYxight, describes, in a specimen of Clostei-ium didymoticum, certain circular
markings, consisting of two concentric rings, as apertures penetrating " both
layei-s of the investing membrane at irregular intervals :" yet neither the
character of these circular bodies, as represented by their observer, nor their
irregular distribution, coimtenances such a notion, and the appeal he makes
to Mr. Ealfs's figures, instead of aidiag his argument, is totally subversive of
it ; for although, ia the fronds of Closterium didymoticum and of C. Ralfsii,
some large globules are distinguishable, these are in single linear series in a
definite and constant position, except when disturbed from it by the death of
the plant, or by its exhaustion by parasitic growths upon it, and clearly are
not apertures. Besides, any such globules are sought in vain when the frond
is empty, as Mr. Ealfs distijictly shows by his figui'es ; whereas if they were
openings, they would then be more evident than when the frustule is filled
■with its endochrome. Mr. Wenham {J. M. S. 1856, p. 159) has been un-
able to confinn the presence of apertures, and writes — " It may be assumed
that if such an opening existed it would have something like a structural
margin of such a size as to allow its position at least to be visible under the
microscope, but not the slightest break can be observed in the laminated
structure that the thickened ends display."

Movements aitd Exteen ax Chia. — By continued observation the DesmidiesE
are seen to move very slowly onwards, or with an oscillating movement
backwards and forwards. This phenomenon is most notable in the long
spindle-shaped fronds of the genus Closterium ; in others it is scarcely, in
many not at all, cognizable. Ehrenberg having persuaded himself of the
existence of pedal organs or papUlae at the extremities of the fronds of Clos-
terium, foimd no difficulty in explaining their locomotion; but other observers,
who deny the presence of such organs, have been compelled to seek somo
other explanation of the subject. Some have referred the locomotion to the
influence of the vital acts taking place within the organism, to the extri-
cation of gas, &c. ; others again, particularly of late, have attributed it to
the presence of cOia coveiing the suiface. This latter hypothesis is sup-
ported chiefly by the Rev. Mr. Osborne and Mr. Jabez Hogg, who represent
these organs as covering the fronds of Closterium, of Staurastrum, and of
other Desmidieoe (see page 7, on the Circulation). Mr. Wenham has
sought cilia in vain, and attributes the supposition of their existence to an
optical illusion. Powerful oblique sunlight, which is found necessary to
(hsplay the apparent ciliaiy movement, this observer remarks, " causes a
refractive atom to appear elongated as a ray or line . . . . , and this line also
to appear to extend over the boundary of a cell-wall or other adjoining body:
another cause of deception arises from a large angle of aperture." The pos-
sibility of such en-ors he illustrates by reference to the circulation as seen
in Anacharis. In those fronds invested with a mucous sheath, cilia on the
surface of the lorica could perform no locomotive function, and therefore can
scarcely be supposed present. Like^vise in the concatenated species they
cannot be looked for, since any movements they possess are of that general
-sort seen in other filiform Algse, springing from ^^tal action under the
influence of hght.

Apart from tliis inconsiderable movement', seen under the microscope, the

6

GENERAL HISTOKY OF THE INFUSOEIA.

Desmidieee are known to move through considerable spaces. They travel
towards the light ; appear on the side of the vessel on which the light falls,
or rise to the surface and form a pellicle upon it. These, and the analogous
fact of their penetrating to the surface of mud in which they have been
imbedded, when exposed to light, are phenomena common to the Dcsmidieaj
with other Algae. " Another proof (writes Mr. Ealfs) of their power of
locomotion is afforded by their retiring in some instances beneath the surface
when the pools dry up," a phenomenon witnessed also in the case of other
plants. Braun S. p. 203) casually refers to this kind of motion, dependent
on the resumption of vital action. The Penium curium (Cosmarium curium,
Ralfs), which grows " in rain-pools which are alternately quickly filled and
dried up in the changes of the weather, ascends from the muddy bottom,
when the pools fiU, in the form of beautiful bright green clouds, produced
by the social growth and the very fluid, widely-extended gelatinous invest-
ment of the cells." The movement of this plant, it is added, is more active
and more regiilar than that of other Desmidieae, and " it is a remarkable
sight to behold all the individuals ia a dish of water in a short time turn
their long axes towards the hght, and thus aiTange themselves in beautiful
streaks in the gelatinous mass. Obsei'vation likewise shows that it is the
younger half of the cell, disting-uishable as such for a long time after division,
which here timis towards the Hght."

Contents of Feonds. — The contents of the fronds or fiiistules of Desmidieae
are designated generally by the name of Endochrome. This endochrome, we
have already remarked, is of a grass-green coloiu', and contained in a proper
sac lining the denser lorica. It is not homogeneous, but presents numerous
globules, small vesicles, and many refracting corpuscles ; it is commonly
not uniformly diffused, but collected in a definite manner, and it either com-
pletely fills its sac or leaves it unoccupied at parts, which not seldom are
constant in position and aspect. The appearance of the endochrome is
modified by age, by external physical circumstances, and by the process of
development. Niigeli and Braun describe it as constituting two layci-s
within the primordial utricle, viz. an outer and an inner mucilaginous layer,
the latter the thicker of the two.

Ehrenberg, influenced by his belief of the animal natm-e of the Desmidiaccie,
and by his peculiar hypothesis of their polygastric organization, rciirescnted
the larger vesicles or globules to be digestive sacs or stomachs, and the
smaller green coi-puscles, ova. He even exerted his imagination still fiu-ther,
by announcing that in Micrasterias, Arthroclesmus, and one or two other
genera, male reproductive stiiictures are visible. These suppositions it is
not necessaiy to discuss, seeing that they are unsupported by any facts in
the structure and ceconomy of this family.

The globules and corpuscles of the endochrome of Desmidieas seem to
differ in no respect from those in other Algse, consisting of chlorophyll,
starch, and of oily materials floating in a watciy mcdiiun. In most sjiecies
of Closterium and of Tetmemorus, some large diaplianous vesicles arc con-
spicuous, either disposed irregularly, or more frequently in a single longi-
tudinal series (II. 1, 12, 13). Those have the appearance of being distinct
cells; and Mrs. Thomas has indeed described two such, of large size, in
Cosmarium mrmiaritiferum, as " vesicles fiUed with moving granules." No
doubt many of the apparent vesicles are nothing more than vacuoles wlrich,
as in other protoplasmic substances, tend to arise in the ceU-contents. and
may assume a fixity in size and in position.

The several species of Closterium, and of Docidhtnu and some of Pniivm,
present also, at each extremity of the endochrome (II. 2. 9. ]4). "a large

OF THE DESMIDIE^.

hyaline or straw- coloured globule which contains minute granules in con-
stant motion." It is seen even in the earliest stage of the frustules, but
disappears in dried specimens.

In addition to these structures, distinguishable in certain genera only,
Niigeli and others state that a central nucleus exists in all the Desmidiea3,
mostly containing within itself a nucleolus. " In Closterium (Braun writes)
the nucleus with its colom-less mucilaginous envelope is maintained in the
centre of the spindle-shaped cell by the green lameUae of contents, arranged
radiantly ai-ound the long axis of the cell, which lamellae are interrupted by
it in the middle of the cell. In many cases it seemed to be surrounded as
by a band, or by a cavity containing water."

Nageli affirms that " Arthrodesmus possesses a small coloiu'less corpuscle on
the wall of the cell, which looks like a nucleolus. Euastmm also exhibits
frequently among the green contents two obscure bodies resembling nuclei,
always one in each half, when the division through the middle takes place.
These are not attached to the cell-membrane, but lie free in the midst of the
cavity : they appear to possess a dark centre (nucleolus) and a clear peri-
phery (enveloping layer?).. ..In Closterium a nucleus lies in the centre
which possesses a thick whitish nucleolus within a clear enveloping layer.
It is coloured brown by iodine, and whoUy resembles the nucleus in Spi-
rogyra." Probably the vesicles mentioned and figured by Mrs. Thomas are
really nuclei (I. 2, 5).

There is something special in the disposition of the endochi'ome in very
many of the Desmidieae. On a front view of Desmiclium, the endochrome is
divided into linear portions by a pale transverse line between the angles ;
and on a transverse view it is seen to send out as many thick rays as the
cell has angles. Again, in Cosmarium Ralfsii the endochrome is somewhat
radiate ; but it is in the elongated genera, in Penium and Closterium, that
its disposition is most characteristic. In both these genera the green matter
of the endochrome seems condensed, so as to produce broad longitudinal bands
(II. 2, 14), technically called jillets, which have their continuity always
interrupted at the median transverse suture, and in several examples of the
genus Penium by three cross bands. These fiUets are more or less strongly
marked in different cases, and, it may be, are constant in number in the same
species. Mr. Ralfs (p. 159) teUs us that Meneghini considers them of too
much importance to be omitted in the specific definition. They may occa-
sionally be useful in discriminating nearly allied forms ; but as they are fre-
quently indistiact, or from various causes not readily counted with certainty,
he is imwiUing to introduce them into the specific characters, except in the
absence of more permanent marks of distinction.

CiECTTLATioN OF CONTENTS. — A circuktiou or rotation of much of the liquid
contents may frequently be seen in the Desmidiea3. The Olosteria aflPord the
best subjects for witnessing this phenomenon, but careful focusiag and other
microscopical adjustments are always needed to display it. Even Mr. Ralfs
had failed to observe it untD. he watched it in conjunction with Mr. Bower-
bank, in Closterium Lunula and in Penium Digitus,

Since Mr. Ealfs's account was written, much more attention has been
bestowed on this phenomenon ; and it has been observed by eveiy micro-
scopist who has sought for it. The Rev. Mr. Osborne has pai-ticularly studied
it, and has come to the conclusion that it is due to ciliary action. " If
(he writes, J. M.S. ii. 235) I put a specimen on the stage, cover the stage
so as to exclude the light, use the parabolic illuminator with the direct light
of the sun, in certain focal positions I see what appear to bo cilia worlcing
evenly and continuously along the whole external margin of the plant. I

8

GENEEAl HISTORY OF THE HTFUSOBIA.

am inclined to believe that this is not so, that this is some ocular deception,
and that these cilia, so seen, arc -ndthin the outer case. It may be that these
ciHa are on the external surface of the membranous sac, as well as over the
endochrome ; more practised observers with higher powers may yet determine
that. Of the existence of the cilia throughout the plant there can be no
doubt, and no object I have ever seen wiU bear comparison with this when

behold under sunhght It is seldom that I can trace a current up one

margin, and round the point down the other ; these currents seem to me as
the rule to pass from the point, when they reach it, down to the centre of
the spot where the cilia are seen terminating the endochrome."

In a second part of this communication the writer adds : "I have scarcely
failed in one attempt to see the circulation and ciliary motion in the Clos-
terium Lunula. I tried today heating a little water, by putting a small bottle
in a cup of warm water ; the effect seemed to retard the circulation, but to
make the globules larger. I have traced it over the whole extent of the en-
dochrome, but it is best seen at the convex side a short way from the edge. I
am more than ever convinced the cyclosis is the waving of attached tongues
of cilia. The specimens are capricious in the results they afford ; they show
best when the sun has been on the jar for a time. I have watched the move-
ments of the globules in Vallisneria, Nitella, &c., and they are to me altogether
of a different nature to that in the Closterium, &c. To my eye there is no
real analogy between this circulation and that in the above plants ; but there
is much more with the branchial action in the mussel." Mr. Jabez Hogg's
supplementary notes to Mr. Osborne's paper represent the whole frond as
" brilliantly gUttering with the moving and active cilia ; whilst in the
cyclosis numerous zoospores were most actively moving about by the same
agency. When the sunlight falling on these little bodies warmed them into
life and motion, the rapid undulations produced by the action of the cOia
illuminated the whole frond with a series of most charming and dehcately-
coloured prismatic fringes or Newton's rings. The motion and distiibution
of the cilia must be seen by the aid of the direct sun-rays and parabola ; for
although I tried eveiy other mode of illumination, and with Mi-. Brooke nsed
Gniett's condenser, yet neither of us noted satisfactoinly theu- situation and
distribution until we resorted to the parabola. At the same time the cir-
culation may be most accurately observed to take place over the entire
surface of the frond. The stream is best seen to be ranning up the external
margin, jiLst internal to a row of cilia, with another taking a contrary direc-
tion next to the serrated cUiary edge of the endochrome ; the whole being
restricted to the space between the mass of endochrome and hyaline integument
passing above and around the cyclosis, but not entering into it."

Another writer (J. M. S. 1855, p. 84), Mr. Western, adduces an observa-
tion which he believes to confii-m the presence of ciHa in Closterium, and
even goes so far as to advance the notion that the circulation in tlie cells of
Chara, and, by analogical reasoning, in those also of other water-plants,
originates in cihary movements. In Ohara, as in Closterium, he tells us, he
observed " precisely tlic same appearances, the same rapid undulations, to-
gether with the same brilliant coruscations." Dr. Wright, whose contribu-
tion in the same Journal (1855, p. 171) Ave have previously quoted, admits
the presence of cilia, and starts the extraordinaiy supposition that the circu-
lation of the contents of Closterium is carried on through canals or vessels,
which he describes as marginal, and that it is independent " of a fi-oquent
irregular movement of granules of endochrome more resembling imperfect
cyclosis."

If oiu' doctrines concerning the physiology of animal and vegetable cells be

OF THE DESMIDIEiB.

9

at all correct, the' statements above quoted respecting the ciliary origin of
cyclosis, and more particularly the hyiiothesis of a vascular system, are
scarcely or not in any way admissible. We are disposed to attribute the
appearances so interpreted to misconception. Dr. Wright's notion of canals
or vessels is equally extravagant with that once advanced by Schultze, of the
network of sap-vessels in and about the cells of plants, and requii-es no dis-
cussion. The opinion of Mr. Osborne that the ciu-rents in Closteria and other
Desmidieae ai-e due to cilia, and are not analogous with the in all respects
similar currents in the cells of various aquatic plants, is simply an assump-
tion, and one indeed in opposition both to what an unbiassed observation of
the phenomenon in the two sets of plants would suggest, and to what com-
parative physiology would teach. Again, the analogy he suggests between
his supposed ciliary cyclosis and the ciliary action of the branchiae of the
mussel will be inconceivable to any one who understands the structiu-e of the
brancliial apparatus of Mollusca, the distribution of the cilia on the external
siu-face of a mucous membrane, and their office there in providing for the
active performance of the respiratory function. Analogy would, indeed, in-
duce us to believe, that if cilia are the motory organs of the cyclosis of
Desmidieae, they are equally so of that in other unicellular Algae, as well as
of that in the cells composing the tissue of compoimd forms. If so, we might
adopt Mr. Western's belief in the existence of cilia wherever a circulation of
the contents of cells is visible, did not om' opinion of the natuji'e of cells and
of the histological relations of their parts deter us from accepting the doc-
trine at all of the presence of internal cilia within unicellular organisms.

Then, again, we cannot see the necessity of a ciliary apparatus to secui-e the
flirctuating, oscillating or irregular and mostly incomplete movements of the
coi-puscles within the cells of Desmidieas. To us such movements are expli-
cable by reference to the changes ensuing in the nutritive processes of the
living oi'ganisra, and to the cm-rents caused by the ever-acting endosmose and
exosmose. Moreover, it should be borne in mind how exceedingly minute
these molecular movements are ; how veiy inconsiderable the space passed
through is ; how sluggish, compared with those due to undoubted ciliaiy ac-
tivity, the movements themselves are. But in addition to arguments deduciblo
froni analogy and general morphology, those put forwai'd by Mr. Wenham,
resting on du-ect observation and experiment, seem to us strongly adverse to
Mr. Osborne's hypothesis, and indicate it to be a consequence of optical de-
ception. At a preceding page (p. 5) we have quoted Mr. Wenham's remarks
on the deceptive effects produced in viewing objects by oblique sunlight, or
by any powerful soiu-ce of illumination, and by the use of a large angle of
aperture ; we will here add his comparative obsei-vation of the circulation of
Anacharis. In viewing this, he tells us (op. cit. p. 159), " with a large aper-
ture, the chlorophj'll-granules traversing along a straight and thin septum (if
the position is favourable) appear to project into the neighbouring cell, seem-
ing to pass directly under the line of the cell-wall. Smaller particles mil
apparently travel within the substance of the cell-wall ; and in case of a
boundary or single cell, or in unicellular plants, if the surrounding water has
nearly di-ied up, the rim or prism remaining round the exterior (by the way,
just the conditions under which Mr. Western made his observation) causes
irregular refracted images of the particles of protoplasm to appear outside the
cell, bearing such a remarkable similarity to external cilia, that the passin"-
shadows may even be mistaken for currents in the water." "

Besides the incomplete rotation or circulation of the contents iust con-
sidered, there is an active l)ustling sort of movement of minute" granides
witlim an apparent globidar vesicle situated at each end of the elongated

10

GENERAL HISTOUY OF THE INFUSOEIA.

fronds of some Deamidiese, e.g. of Docidmm and of Closterium. The vesicles
in question are known as the " teiToinal globules," or chambers, and would
appear to be actually invested with a membrane, and therefore distinct en-
closed sacs. In Closterium rostratum and C. setaceum, the collection of moving
granules is at a distance from the extremities, and apparently not contained
mthin a vesicle. In all species exhibiting terminal globules these structures
appear in their earliest stage, but disappear when they are dried,

Ehrenberg imagined the supposed retractile locomotive organs to be fixed
to these globules, and that the granular movement within them was no other
than that of the bases of these organs. Mr. Varley described the chambers
as having contractile walls, and the molecules as transparent spheroids mea-
suring from l-20,000th to l-40,000th of an inch, sometimes escaping from
their- chamber and cu'culating vaguely and irregularly between the periphery
of the gelatinous body and the shell. Mr. Kalfs regarded the terminal glo-
bules to be peculiar to the Closterina ; yet their contained granules seemed to
him " to differ in no respect, except in position and uninterrupted motion,
from other granules in the same frond." He once saw the motion continue
after their escape from the ceU. Mr. Osborne {op. cit. p. 235) behoves the
granules to be ciliaiy bodies. He writes : " At the extremities of the green
matter there are certain bodies acting with a ciliaiy movement within what
has been called a chamber, lying towards the poiat of the membranous sac ;
certain bodies, apparently of the same kind, separate from the endochrome in
a small mass, appearing at the extreme end of this so-called chamber, or at
the side close to the end ; these also impart a ciliary movement to the water
within the sac around them." He adds (p. 239) : " When the endochrome
is of a rich dark green, I find the chamber at the extremity veiy plain and
defined, with its cilia very active .... As the endochrome gets of a lighter
colour. . . .the chamber becomes smaller and the cilia are barely seen." At
p. 236, Mr. Osborne further states, " The loose bodies seen in the chamber of
Closterium Lunula have very generally cilia, and are, I believe, zoospores ;
loose pieces of endochrome are sometimes brought round in the current, but
these are easily distinguished. I have never seen anything like true cyclosis,
i. e. molecules in circulai' movement, within the so-called chamber."

Of the purpose of the moving gramiles within the teiTiiinal globules, the
prevailing notion is that they are zoospores. Meyen likened them to the
" spermatic animalcules of plants ;" and, as above noted, Mr. Ralfe saw them
move about as do the zoospores of other Algae when freed from the enclosing
capsule and frond. So far as we can gather from his remai-ks, Mr. Osborne
also inclines to this opinion, which is likewise supported by Mrs. Thomas
(T. M. 8. 1853, p. 37).

We are sorry that we can present no more definite views concerning the
nature, characters, and pui-pose of the terminal globules than those compiised
in the foregoing extracts. We find no similar globules in other Alga;, and
therefore obtain no guide from analogy ; indeed sucli stnictiires seem to be
peculiar to the elongated Desmidicae — to tiie genera Closterium, Pcnium, and
Docidium ; we must consequently look to subsequent research to elucidate the
question. (See Appendix at end.)

Another sort of internal movement, more prevalent among the DesmidieaB
than that last considered, is " the swarming motion," so called, seen cither at
one or two parts of the frond when matiu-e, or othenAase tiiroughout its con-
tents. Having once commenced, it never ceases, but extends itself, and
induces changes in the nature, appearance, and coloiu' of the endochrome ;
for this loses its grass-green colom*, acquires the autumnal yellowish or
reddish-brown tint, and a finely granular aspect. Wlien the granules biu-st

or THE DESMlDIEiE.

11

through the openings of the suture between the valves, they escape to a
distance and still keep up their active movement.

In the genus Cosmarium this phenomenon is frequently and readily ob-
served. Mrs. Thomas, in her interesting obsei-vations on Cosmarium mar-
garitiferum {T. M. S. 1855, p. 33), has detaHed the foUowing appearances :—
" In each half (she wiites) the centre was occupied by a vesicle (as it appeared)
filled with moving granules, while smaller vesicles were at the four sides
(I. 2). The granules did not appear to cii-culate through the plant, but kept
to their own place, which was either a bag or cavity— I could not decide
which." In another example " the granules were swarming over the whole
plant." . . .

These peculiar movements of the granules are not restricted to this tnbe,
but are known to occui- in many genera of Algae. Their purpose seems con-
nected with the reproductive process. Mrs. Thomas (loc. cit.) refers to it as
in some way related with the formation of sporangia ; wliilst Mr. KaUs, who
speaks of the swarming particles as " zoospores," confesses himself perfectly
unacquainted with their subsequent histoiy, although he coincides with Pro-
fessor Harvey in regarding the phenomenon of swarming as a " strictly vege-
table peculiarity."

Eepeoduction of DESMlDIEiE. — This function presents itself under two
phases, the end of one of which is to multiply or perpetuate the individual
plant, whilst that of the other is to reproduce the species. The former pur-
pose is attained by the process of fission, the latter by that of the development
of sporangia, and, it may be, by the swarming of zoospores.

The act of seK- division is frequently obseiwed, and is in all respects the
same process as in the cells of other Algae, or indeed of any plant. Analogy,
and not, indeed, direct obsei'vation, suggests as necessary the initiative action
of a nucleus to precede the constriction of the soft lining sac of the lorica,
i. e. of the primordial membrane, which is next followed by that of the harder
external coat. The proceeding is varied, in some non-essential particulars, by
the figare of the fronds, and also by the circumstance of its own completeness
or incompleteness. Mr. Ralfs has well described the fission of Euastrum (op.
cit. p. 4). The narrow connecting band between the two segments of the
frond lengthens and is " converted into two roundish hyaline lobules ; " these,
though at first very minute, increase rapidly in size, and exhibit from their
origin the deep constriction characteristic of the mature fronds. The advancing
growth of the interposed new foiiuations necessaiily pushes further asunder the
original segments, which finally become disconnected, " each taking with it a
new segment to supply the place of that from which it has separated .... At
first the new portions are devoid of colour, and Irave much the appearance of
condensed gelatine ; but as they increase in size the internal fluid acquires a
green tint, which is at first very faint, but soon becomes darker ; at length
it assumes a granular state. At the same time the new segments increase
in size and obtain their normal figure ; the covering in some species shows
the presence of puncta or granules, and, as in Xanthidmm and Staurastrum,
the spines and processes lastly make their appearance, beginning as mere
tubercles, and then lengthening until they attain their poifect form and size.
Complete separation, however, often occurs before aU these details of develop-
ment are complete (II. 11, 24, 26). This singular process is repeated again
and again, so that the older segments are united successively, as it were, with
many generations." Illustrations of this act are fiuTiished, in the case of two
species of Cosmarium, in the appended plates (I. 4 ; II. 26), to which the
above account will be foxmd equally well to apply.

" In Sphcerozosma the same changes take place (1. 11), and arc just as

12

GENERAL HISTOHT OF THE INFUSOUIA.

evident; but the colls continue linked together, and a filament is formed, which
elongates more and more rai)idly as the joints increase in number. This
continued multiplication by division has its limits ; the segments gi-adually
enlarge whilst they divide, and at length the plant ceases to grow; the division
of the cells is no longer repeated ; the internal matter changes its appearance,
increases in density and acquires starch-granules, which soon become nume-
rous ; the reproductive granules are perfected, and the individual perishes.
In a filament the two oldest segments are found at its opposite extremities ;
for so long as the joints divide, they are necessarily separated further and
fiu-ther from each other. Whilst tlus process is in progress, the filament in
Sjphoerozosma consists of segments of aU sizes (1. 11) ; but after it has reached
maturity there is httle inequahty between them, except in some of the last-
formed segments, which are pennanently smaller. The case is the same with
those genera in which the separation of the cells is complete .... It is obvious
that the new portions must arise from the whole of the junction-margin of
the original valves ; consequently when the junction occupies only a part of
the breadth, the new portion will be narrower than the old ; but when the
junction of the valves is as broad as the cell, the new portion will from the
beginning be of the same breadth," and will i-emain undistinguishable by its
size when fission is complete.

Mr. Ralfs goes on to say that, " when the cell is oblong, or only rounded
at the extremities, the process, though similar, is less evident ; the cell at
fii'st seems merely to elongate (II. 11), until it attains nearly twice its ori-
ginal length, when the division commences, and the rounding of the new ends
becomes apparent. The tapering cells present but little difference, for the
separation takes place before the extremities are fully developed ; sometimes
these cells separate obhquely, as in S_pirotcema."

The mode of self-division in Glostenum has been illiistrated by the Eev.
Mr. Osborne {J. M. S. 1854, p. 57), from whose account we abstract the fol-
lowing particulars : — " I have (he says) watched for houi-s the process of
complete seK-division ; one-half of the frond has remained passive, the other
has had a motion from side to side, as if moving on an axis at the point of
juncture ; the separation has become more and more ai'dent, the motion more
active, until at last, with a jerk, one segment leaves the other," each having
one extremity — the one newly formed along the line of junction of the two
segments — much more obtuse than the other. " The circidation of the con-
tained globules for some hours previous to subdivision, and for some few hours
afterwards, inins quite round the obtuse end of the endochrome."

Previously to complete separation esich segment begins to show a central
constriction of its endochrobie, which iu due time extends across the new
frond, and constitiites the median clear space or band.

A true reproductive act is presented by the act of conjtyation, or coiqiling
of two fronds, and by the resultant development of a sporangium (II. 6, 8 ;
XVI. 11, 12, 13, 14). This process consists in the apposition and subsequent
intercommunication of the cavities and contents of two cells, which may be
free, or othei-wise, members of a chain or filament. It is an act not jicculiar
to the Desmidiea;, but common to them along with the Diatomeaj and Con-
jngataj. " In the family Conjugata3 (says Mr. llalfs) the cells conjugate
whilst still foi-ming parts of a filament ; but in the Desmidicaj the filamentous
species almost invariably separate into single joints before their conj\igation,
and in most of the species the valves of the cells become detnchcd after they
are emptied of their contents." To bring about tlic neccssaiy apposition, it
is usual for the conjugating cells to expand or bulge out on those sides which
arc to come into union ; and whilst this is proceeding, the vesicles or globules

OP THE DESMIBIEJE.

13

increase much in number, and, together with the granular contents, become
aggregated about the conjugating part. When contact is complete, an absorp-
tion of the opposed walls of the two cells takes place, or the sutiu'c of each
opens, the endochrome from both is discharged and intermingled, and an
orbicular green granular mass, enveloped in a mucous sheath thi-own out
around it by the conjiigating cells, is produced. When the process has pro-
ceeded thus far, the original valves are more or less completely emptied of
their contents, lose their vitality, and are sooner or later detached, and float
away from the sporangium developed.

The foi-mation of a sporangium by conjugation occupies no great time.
Indeed, in the case of Closterium Ehrenbergii, the Eev. W. Smith tells us
that " the discharge of the endochrome and the formation of the sporangia
are accomplished with much rapidity, and may often be seen taking place in
the field of the microscope ; the whole operation not occupying more than
a few minutes .... During the formation of the sporangia there appears to
be a second development of mucus in the foi-m of rings aroimd the reproduc-
tive bodies ; this is probably only the effect of the pressure prodiiced by the
growth of the sporangia on the mass of investing mucus."

This act of conjugation admits of sKght variations in character, determined
by the form of the conjugating cells, and by other cii'ciunstances peculiar to
the tribe, family, or genus in which in it occurs. In the filamentous species
of Desmidie£e, the joints, as before noted, usually become separated before
their conjugation ; and in most instances the old valves left empty after the
act of conjugation are almost immediately detached from the sporangium ;
but in a few species they persist some time afterwards, e. g, in several of
Penium. In Didymoprium the separated joints, on conjugating, unite by
means of a narrow process pushed out from each, and often of considerable
length ; through this the endochrome of one cell is trarisfen-ed into the other,
and thus the sporangium is produced within one of the two cells, just as in
the Conjugatse. In Staurastrum and Micrasterias the contents of both
fronds are discharged into a delicate intermediate sac or bag, which gradually
thickens, produces emiaences, and at last forked spines (II. 25). Again, in
Tetmemdrus, " the process of forming the sporangium (says Mr. Ralfs) is
interesting, as it exhibits a striking similarity to the change diuing the
formation of similar bodies in Stawocarpus among the Conjugates. In
Staurocarjous, after conjugation, a subquadrate cell is formed, within which
the endochrome is collected. The latter is at fii'st of the same figure as the
cell, but iu at least one species is at length condensed into a compact
globular body, and iu every species the eeU with the contained sporangium
finally separates from the filaments with which it is connected. In this
separate state I can discover no character by which to distinguish the
sporangium of Tetmemorm from one belonging to a species of Staurocarpus."
To quote the same authority, — "In Penium Jenneri the conjugating fronds do
not open and gape at the suture, as is usual in the Desmidiea3, but couple by

small and distinct cylindrical tubes like many of the ConjugatSB In

Closterium two fronds unite by means of projections arising at the junction of
the two segments, and then the newly-fomicd portion continues to enlarge
until the original segments are separated by a cell of an irregiilar figure (11,
6, 6). The contents of the fronds being collected in this cell become a dense
seed-like mass, which is sometimes globular, resembhng the sporangium of
Mougeotia, and sometimes square, Uke that of Staurospermum. The newly-
formed cell is thinner and generally paler than the segments of the fronds ;
in some species it looks. Uke a prolongation of the segments, and in othora
these are so loosely attached that their connexion is scarcely perceptible.

14

GENKUAL iriSTOBT OF THE INFUSOKIA.

The coupling of the fronds generally takes place from the convex margin,
but may occur on the concave, or even the convex margin of one frond may
couple -with the concave of the other."

The Eev. W. Smith {A. N. H. 1850) represents the conjugation of
Closterhcm Elirenbergii to be peculiar (XVI. 11, 12, 13, 14). The first
phenomenon (he tells us) is an alteration in the granular condition of the
endochrome. This, from a light yellowish green, passes to a much darker
shade, and the larger granules, or " diaphanous vesicles " of Ealfs, which
were originally few in number, and arranged in a somewhat irregular longi-
tudinal series (XVI. 10), become exceedingly numerous and pervade the
entire frond. While this change is about taking place, the fronds approach
in pairs, approximating by their concave surfaces, and finally coming into
such close neighbourhood that their inflated centres are in contact and their
extremities slightly overlapped (XVI. 11). In a short time, probably in the
course of twenty-foiu- hours, a remarkable change takes place, both in the
appearance and condition of the fronds ; a mass of delicate mucus is secreted
around the approximated fronds ; these remove to a little distance from' each
other, undergo " self-division," and present altogether an irregular oval figure,
the outhue of which is formed by the peripheiy of the mucus, the fom* divi-
sions of the fronds being placed ia the middle in a somewhat quadrilateral
maimer (XVI. 12). During the progress of cell-division, the internal mem-
brane of the ceU-wall becomes enlarged at the suture or line of separation,
and projects in the form of an irregular cone, with a blunt or rounded apex
forming a beak, whose side view presents a triangular outline. This beak
becomes filled with endochrome, either by the dilatation or increase of the
contents of the half-frond, and the divided frond assumes the appearance of
one with two unequal segments (12), being what M. Morren calls *' a Chs-
terium of two unequal cones." On these membranous expansions, at the con-
cave surfaces of the fronds, and close to the original sutures, there appear,
almost simultaneously with the formation of the beaks, two cii-cular projec-
tions, which, rupturing at their apices, give egress to the delicate sacs which
enclose the endochrome, and which, drawing with them their contents, and
meeting with the endochrome sacs emitted through similar projections from
the other half-fronds, form, by their connexion, in-egular masses, which
quickly consolidate and assume the appearance of perfectly crrculai-, smooth,
dark-coloui-ed balls, the sporangia of Ealfs and seminulcs of Morren.

Lastly, we may add, that Siebold (J. M. S. 1853, pp. 118, 119) remarks that
the conjugation in C'lostenum Diance, C. Uneatum, C. striolatum, G.setaceum,
&c., differs from that in G. Lunula, G. rostratum, and other members of the
family, by dehiscence at the central transverse suture, and the consequent
coalescence of the contents of the two cells into a rounded or angular mass, —
an observation which taUies with the account presented us by Mr. Ealfs.

Braun (On Eejuvenescence, R. S. p. 286 et seq.), speaking of conjugation
generally in simple cells, gives an elaborate view of the variations tlie phe-
nomenon exhibits, and arranges them under several heads. Thus among the
Desmidiefe " the conjugating cells unite with participation of the external
membrane, [and] the reproductive cell is formed [either] through contraction
of the contents clothed by the internal cell-membrane, [or] out of the mere
contents as a new cell inside the mother-cell." But in the majority of the
Desmidieae, " the conjugating cells, after dehiscence of the out^r membrane,
unite through the inner ; the reproductive cell is formed out of the mere
contents as a new cell inside the conjugation-cell." By the first-named
mode, "the formation of the reproductive cell is ... . not a direct result of
the conjugation, but it is fomed subsequently in the interior of the con-

OF THE DESMIDIE^.

15

jiigation-cell, in the strongly expanded isthmus of this. The delicate internal
membrane, with the contents enclosed by it, drawing itself ont of the extre-
mities of the double ceU, forms a secd-ceU, at first cniciatc, foiu'-lobed, then
bluntly quadrangxilar, and finally globular, clothed by a many-layered
thickened membrane within the persistent four-homed conjugation-cell.
From Ralfs's representation, this is most probably the way in which the pro-
cess is to be iinderstood in CyUndrocystis (Penium) Brebissonii."

The second mode, when the union of the isolated ceUs is also lateral and
parallel, is exemplified in Closterium Lunula, in which, according to Morren's
express statement, three different membranes take part in the formation of
the canal of union, — an inner and an outer ceU-membrane, and a membrane
(the primordial utricle) immediately enclosing the green mass. The glo-
bular reproductive cell foimed in the connecting canal is an active gonidium,
which begins to revolve even while in the canal, and soon breaks through the
gelatinously-swollen membrane of the latter. Very often two approximated
individuals divide again and conjugate before they have completely separated,
whence result conjugated double pairs.

The third scheme of conjugation, the most widely extended, is itself
reduced by Braun to two principal secondary varieties, and to several sub-
sidiary ones. Thus conjugation takes place either in a parallel position or in
a crossed (decussate) manner. The former is peculiar to the Closterina ; the
latter is met with in Euastrum and allied forms, and also in many genera
formerly united with Desmidivm. The modifications, in various species, of
these plans are well explained in Braun's work, to which we would refer
for particulars, as well as for an elucidation of the production of a " really
double spore (not two-lobed, as Ealfs terms it) " in Olosterium lineatum.

The next question which presents itself is, whether the product of con-
jugation is to be esteemed a spore or a spore-case, i. e. a sporangium. That
the latter is its nature appears pretty clear, and is assumed as a fact by Mr.
Ealfs. This authority observes : " The sporangia I consider capsiiles, and
this view seems to be confirmed by the experience of Mr. Jenner, who states
that the covering of the sporangium swells, and a mucus is secreted, in
which minute fronds appear, and by their increase at length ruptiu'e the
attenuated covering." In this opinion Siebold coincides ; and the Eev. W.
Smith {A. N. H. 1850, p. 4) represents, on the authority of Mr. Jenner, the
bursting of a sporangium of Closterium acerosum, and the development of
young fronds from its contents.

Braun, in his philosophical treatise (op. cit. B. S. p. 133), remarks of the
products of conjugation in the Desmidieae, that " they do not pass. Eke the
swarming- cells of the PalmeUaceoe and the reproductive cells of the Dia-
tomaceae, directly and by uninternipted growth into the primary generation
of the new vegetative series, but persist for a long time in a condition of rest,
during which, excepting as regards imperceptible internal processes, they
remain wholly unchanged. To distinguish these from the direct germ-cells
(gonidia), I shall caU them seed-cells (spores). The development of these
spores has not yet been observed ; but it may be assumed as certain, that
they do not pass as such into the primaiy generation, but produce this at the
period of germination, by an internal transformation of thcii* contents and
bring these to light as a new generation with a dehiscence of the old' en-
velope. Certain early conditions obsen'ed in Closterium and Euastnim, namely
families of unusually small individuals, enclosed in transparent colourless
vesicles, render it even probalile that in certain genera of Dcsmidiea?, a
number of individuals are produced from one spore, by a formation of transi-
tory generations occumng already mthin the spore. The enclosing vesicle

16

GENEEAL niSTOKY OF THE INFUSOUIA.

is probably the dissolved and swollcn-up internal cell-coat of the spore,
which holds the young individuals combined for some time after the outer
coat of the spore has been thrown off."

Although Braun has, in the preceding account, made use of the tcnn "spore"
to express the conjugation-product, yet, in the verj^ admission that, in those
Desmidie£E in which only we have any clue to the subsequent history, it
produces, not a siiigie individual, as does a spore commonly so called, but a
multitude, he essentially agrees with Mr. Ralfs, who prefers to call the body
a capsule. We may quote Mrs. Thomas in support of the same view ; for she
considers the sporangium a capsule, or {T. M. 8. 1855, pp. 36, 37) "the
winter casing of a large number of young plants which escape from it by
rapidly knocking against its walls, when these have been loosened by spring
warmth, or which grow up as the walls gradually decay in the midst of slimy
gelatinoiis masses." In proof of this opinion this lady appeals to the immense
increase in the number of plants seen in the spring beyond what can be ex-
plained as the result of self-fission.

In her opinion the sporangium is a capsule (I. 8, 9) filled with zoospores
similar to those moving granules, supposed to be such, seen within the fuU-
grown plant, capable, when their fitting time comes, of filling the waters
with their countless progeny.

In these accounts there is a pervading harmony ; and the truth seems to
be that, by the formation of a sporangium, provision is made for the per-
petuation of the species through the winter, when the large majority, at
least of adult plants, have ceased to exist. The phenomenon is clearly
analogous to that of the formation of seeds by herbaceous plants, or of ova
by insects and other animals, when the cycle of existence of the parent being
is complete, or is put an end to by unfavourable external circumstances.

Braun has expressed the sequence in the phases of existence in the follow-
ing technical language {11.8. p. 133): " In the Desmidiacefe, the Zygnemacefe,
and in Palmoglcea, the transitional generation is divided into a double one,
since the last generation does not pass directly into the first, but the fii-st
generation of the succeeding cycle is produced as a new structiu'e in the ger-
mination ; so that we have here to distinguish three kinds of generation of
cells, — the commencing generation, the concluding generation, and the
intermediate vegetative generations." The last-named is represented by the
process of self-fission, which takes place in the perfect plant, and is con-
tinued through a long series of individuals.

Between its fii'st appearance and its ultimate development, the sporangium
of DesmidiesE undergoes a progressive series of changes ; at fii'st it is pale
and homogeneous, but soon gets granular, acquires a gradually deepening
green colour, and presents vesicles and globules in large nimiber. The enve-
lope, at fii-st very delicate, augments in thickness, and becomes lined by
others, whilst its suiface either remains smooth or becomes granular, tubcr-
culatcd, or spinoris, and the spines themselves in many instances forked or
branched (II. 15, 22, 25, 30, 34). Simultaneously with these changes the
integument increases in density, and together Avith its processes acquires
considerable firmness and toughness. Moreover, as it advances in age it
usually assumes a reddish -bro-woi colour; when this has happened, the
sporangium and contents may be presumed to have reached matiuitj-.

Mrs. Thomas {op. cit. p. 35) thinks she cncoimtered a mature sporangium
of Cosmarium margaritiferum in the shape of a many- coated ball filled with
gi-anules in the same rapid motion as obseiTcd in the full-grown Cosmarium
(I. 10, 11). " The similiirity of the movement (she says) attracted ray
attention ; and I also saw that in one part the enclosing mombranc appeared

OF THE DESMIDIE.T,.

17

thinner, as if giving way at that spot. On the thii-d morning the membrane
had broken and the grannies escaped, leaving the neai-ly emptied case
(I. 12).

Inasmuch as a sporangium may pass successively from a smooth to a spinous
condition, it follows that the transitional stages of one species may be mistaken
for the final stage of another ; hence a difficulty in determining to what plant
detached scattered sporangia may belong. It is only, indeed, when these seed-
capsides occui- in company with the fronds producing them that we axe enabled
to pronounce decisively by what species they are generated.

As the foregoing account of conjugation and sporangia passed through the
press, we met with the valuable paper of Dr. Hofmeister on the propagation
of the DesmidieiE and Diatomese, translated by Prof. Henfi-ey from the
Report of the Natural Histortj Society of Sa^vony for 1857. This commu-
nication tends to clear up the questions of the nature of the sporangia and of
the relation of theii- contents to the propagative process. The conciseness of
the description renders abridgment undesirable ; and we accordingly present
it (so far as it relates to the points in question) as it stands in the Annals of
Natural History (1858, i. p. 2) : —

" The conjugated individuals of Cosmarium tetraopMialmum displayed
exactly the behaviour which EaLfs has represented and Braim described of
those of Cosmarium margaritiferum. The Cosmaria which had commenced
the conjugation process appeared cracked apart at the constricted place in the
middle. Into each of the halves of the tuberculated ceU-coat of the two
mother-individuals extended a continuation of the membrane of the conju-
gation-ceU. This smooth membrane completely lined the interior of the
tuberculated half-sheUs. The contents of the conjugation-cell revealed no
definite aiTangement ; they were mostly accumulated in the middle into an
irregularly-shaped ball ; in other cases separated into several such balls, part
of which extended even into the split half-sheUs of the mother-cell. With
these conjugated individuals, in the same fluid, occuiTed (veiy spaiingly) par-
ticular specimens which bore, in the middle space between the two separated
half-shells, a broad, delicate-waUed utricle, the circumference of which about
equalled that of the two half-ceUs taken together. The arrangement of the
ceU- contents in the primary portions of the cell did not appear essentially
altered ; the contents of the intermediate expansion consisted of a thick coat
upon the wall of granular protoplasm Avith sparingly-scattered chlorophyll.
This condition is probably that which immediately precedes conjugation,
originating by excretion of new cellulose at the deepest part of the constric-
tion, after the cracking of the membrane and separation of the primaiy halves
of the cell, exactly as in normal cell- division, from which this process can
only be distinguished by the omission of the formation of a septum at the
narrowest part of the isthmus. Similar phenomena have been observed by
Nageli in Cosmarium crenulatum, and by Mrs. Herbert Thomas in Cosmarium
margaritiferum (scarcely specifically distinct from C. tetraoplithalmwn^, only
that here the intermediate piece of the Alga did not conjugate Anth the
similar piece of another individual, but, producing tubercles on its outer
surface, continued the vegetative life.

" In other conjugation-cells there lay, in the middle part of the eonjugation-
ceU, a globular cell enveloped in a rather thick membrane, of gelatinous
aspect, and smooth on the outside (the spore). No intermediate stages could
be found between this and the previously-described condition. Experiments,
in which an attempt was made to obtain a completion of the less-advanced
conjugation under the microscope, all failed. Apparently the conjugation-
cell is exceedingly sensitive to any external injury, especially to contact vAt\\

0

18

OENEltAL niSTOllY OF THE INFUSOllIA.

foreign bodies. Very probably the contents, in the above-described cases,
were already abnormally altered, and incapable of further development.

" In other conjugation-ccUs the young spore displayed a still tliicker mem-
brane, covered on the outside with trancate-conical elevations, in which
membrane could be detected a composition of tAvo coloiuless layers. The
outer of these layers remained clear and transparent even in the advance to
maturity. Its elevations became developed into rather long spines, which
forked at the apices into two or four branches. The deeper-seated layer of
the spore-membrane meanwhile assumed a dark-brown colour'. By rolling
under . the covering-glass, the tough, colourless, outer layer may be readily
stripped from the inner, more brittle, brown layer ; then the latter appears
covered on its outer surface with slight elevations, similar to those which
first appeared upon the young spore. The brown layer of the spore-coat
encloses a third, delicate, colourless layer (perhaps the primary membrane
of the spore) which immediately envelopes the cell-contents.

" At the beginning of July, the green contents of aU the spores appeared
conglobated into a spherical mass with sharp outlines, which, lying free ia
the middle part of the ceU, nowhere touched its internal waU. Three weeks
later, in many of the spores these contents appeared separated into two
flattened ellipsoidal masses; when I cracked the ceU by careful pressure,
I was sometimes successful in di-iving out one or both of the masses of
contents in an uninjured condition. They could then be recognized beyond
all doubt as primordial cells; bodies destitute of a soM cell- membrane,
having a thin coat of protoplasm which ' bubbled ' out in water, to which
adhered a thick investment, coloured bright green by numerous imbedded
chlorophyll-granules, surrounding a centa-al cavity filled with transparent
fluid. The fluid contained in the spore in which the two piimordial cells
were immersed, was not colom-less, but rendered turbid by numerous im-
measurably small granules exhibiting molecular motion. In August each of
the ellipsoidal primordial cells had divided into two globular cells, of similar
character to the mother-cell. Towards the end of September, some of the
spores exhibited another such division, so that they then contained eight, not
globular, but strongly flattened primordial cells. Most, however, passed
through the winter-rest imchanged, during which the majority died. At
the beginning of April of the next year, the spinous, transparent, outermost
layer of the coat was more or less completely decayed on all the spores, even
on those which were still to be recognized as living by the vivid green colour
of the contents. All the spores still alive contained at least eight, many six-
teen daughter-cells, all very strongly flattened, almost discoid. In several
spores the outline of the daughter-cells was no longer circular, but displayed
two shallow lateral notches. The still- existing, broAVTiish, inner layer of the
spore-coat was now seen to be softened ; it no longer exhibited its former
brittleness, and it was difficult to crack it by pressure. Daughtcr-ceUs whose
lateral constrictions were most strongly marked, were about half as lai^e
again as the circular, whose diameter about equalled that of the isthmus of
the former, and they almost entirely filled up the caA-ity of the spore. ^Yhen
these were pressed out from the crushed spore, then- form and size agreed
almost exactly Avith that of Cosinarhim Meneghinii.

" I saw similar phenomena in the spores of Cosmantim widuhtum (Corda),
in which the investigation is rendered veiy difficult by the minute size, and
which, cultivated for some months in my room, entered abundantly into con-
jugation. In this, again, I observed the contraction of the green contents of
the cell into a globule occupj-ing the central part ; the division of this ball
into two, four, eight, and sixteen splicrical masses ; finally, the transition of

OF THE DESMIDIEJE.

those daughtor-eells of the last generation from the form of circular lenticular
bodies into two-lobcd ones like the mother-plant. Hero the young Cosmaria,
whose diameter amounted to scai-coly ^th or |th of that of the mother-plant,
were set free by the very gradual solution of the membrane of the spore. A
similai* process very probably occurred in Cosmarium tetraophthalmum, but
could not be observed there, fi'om the cii'cumstance that all the materials had
been used up in the investigation.

" These facts place it beyond doubt that the contents of the spores produced
by the conjugation of two individuals of Cosmarium, are transformed by
repeated binaiy division into eight or sixteen daughter- cells, which assume the
form of the mother- cell, and finally become free by the solution of the waU
of the spore. Such behaviour of the spores had indeed been rendered pro-
bable before, by the discovery of the vesicular stnicture observed by Foeke
and Ealfs, which enclosed a number of small Chsteria, for the most part
beginning to divide. But the certainty wliich can only be given by direct
observation of the development was altogether wanting.

" The development of four daughter-cells in the interior of spores produced
by the conjugation of two individuals (with participation of the whole of the
cell-membrane), has been demonstrated by Alex. Braun for the Palmellacean
Palmoglcea macrococca, Kiitz. (?)."

Sporangia are the only portions of Desmidiese of past eras which have been
preserved to us in a truly fossil condition. Ehrenberg discovered certain
orbicular and spinous bodies in flint, some of which he referred to the genus
Xanthiclium among the Desmidieae, and others to Pyxiclicula among the Dia-
tomeae. However, as Mr. Ealfs remarks (p. 13), this association is, no doubt,
erroneous, since in tme Xanthidia the cell is compressed, bipartite and bi-
valved, whilst in these fossils it is globose and entire, and there can be no
doubt that they are fossU sporangia (XVII. 506 to 515).

To quote Mr. Kalfs's accoimt (p. 13) — " The fossil forms vary Kke recent
sporangia, in being smooth, bristly, or furnished with spines, which in some
are simple, and in others branched at the extremity. Sometimes, too, a
membrane may be traced even more distinctly than in recent specimens, either
covering the spines or entangled with them. Some writers describe the fossil
forms as having been sUicious in their living state ; but Mr. "Williamson in-
forms me that he possesses specimens wliich exhibit bent spines and torn
margins, and thus wholly contradict the idea that they were silicious before
they were imbedded in the flint."

Another mode of propagation is presumed to take place by means of the
active molecides seen within the fronds of DesmidicEe — in other words, by
zoospores, as happens in many families of Algae. M. Morren advanced this
notion, and imagined the minute particles which he denominated " propa-
gules,'' to be at once transformed into small fronds. Mr. Ralfs coimtenances
the opinion so ftu- as to say that the escape of the granular contents of the
mature frond is probably one mode of reproduction. He, however, likewise
regards (as Prof. W, Smith observes) the swarming of the granules as
identical with the movement of the zoospores, and confesses to his ignorance
of the history of the motile granules after theii- escape. But we perfectly
coincide mth Prof. Smith that the swarming of the granules Avithin a matm-c
frond is in most cases "a cHstm-bance attendant iipon the decay of the
granular mass," and not a plienomenon connected with reproduction. StUl
ouj- acquaintance -with the swarming granules, particularly after their escape
from the frond, is so imperfect that it is useless to speculate on tlieir func-
tional purpose.

Ehrenberg, to carry out his hypothesis of the animal nature of Desmidiete,

c 2

20

genehal history of the rNFtrsoBiA.

and to assimilate thoir organization Avith that ho attributed to other Polj'-
gastrica, represented the larger oil-vesicles and starch-grains to be either
stomach-sacs or ova, — at one time the one, at another the otlier, in a purely
arbitrary fashion. Some again of the more transparent or rcfi-acting vesicles
were, Avith no shadow of reason, called fecundating or spei-matic glands. An
attempt to show the error of such an hypothesis of internal organization
would be futile and imcalled for at the present day.

Habitats, Disteibution, Appeahance in Masses, and Vital Endowments

OF DESMIDIEiE. VEGETABLE NaTUKE AND AFFINITIES. MoDE OF COLLECTION.

Tlie Desmidieaj live in fresh water, in ditches and ponds, and rarely in
streams, except when these are very sluggish. They will often rapidly appear
in a recent collection of water, and are not destroyed when the pool is chied
up, as their reappearance immediately after a shower proves ; nevertheless,
ponds which do not dry up during the summer, and pools in boggy gi-oimd,
are richer in these organisms, provided the water remains sweet. To quote
Mr. Ealfs's experience — " The Desmidiese prefer an open coimtry. They
abound on moors and in exposed places, but are rarely found in shady woods
or in deep ditches. To search for them in turbid water is useless ; such
situations ai'e the haunts of animals, not the habitats of the Desmidiefe, and
the waters in wliich the latter are present are always clear to the veiy bottom."
They no doubt inhabit the fresh waters in all parts of the globe, for they
have been found wherever sought in each hemisphere. StiU the sevei-al
genera and species are not universal, for, as in the case of higher plants,
some species are ijeculiar to one country, others to another ; and in the same
countiy the presence and prevalence of any one species "will be determined
by the physical featiu'es of localities, by the nature of the soU, and the Hke.
The distribution, however, of the Desmidieae has not been inquired into so
fully as to justify any attempt to lay down special laws.

Oftentimes in small collections of water, Desmidieae of the same or of
vaiious species and genera multiply to such an extent as to colour the water,
and in the case of the filamentous species, to appear in filmy masses on the
surface or at the bottom of the pool ; stUl this enormous multipKcation, and
the coloration of the water they inhabit, are far less frequent in tlie case of
the family in question than with others — for instance, the Euglcneae, or even
the Diatomeae.

Mrs. Thomas (op. cit. p. 36) has described the gi-een masses formed by
Cosmanum, which during summer and autumn " would float to the siu-faee,
rapidly disengaging oxygen as the sun shone on them, and sinking again to
the bottom -with the coolness of the evening. Later in the year, masses would
adhere to the inner surface of the bottle in the form of a thin pellicle, or
coUect in slimy masses, which appeared to dissolve with the wannth of the
coming spring. The green colour changed to that of a reddish yeUow; and it
might have been thought that all was dead, did not the microscope show the
same beautiful green, both in young and full-grown plants, together with much

bright red and brown, apparently the casings of the sporangia Large

Cosmaria stiU in active motion (the remains of the mature growtli of the pre-
ceding summer) lay imbedded in the mass, when a small portion was separated
for microscopic observation, as well as clusters of young ones (I. 13, 14).
When the bottle had remained more than a year untouched, except for change
of water, these masses increased in Icatheiy hardness ; green life was not
extinct, but became feeble in colour, and too much changed to warrant further
observations, whUe a small portion placed in another bottle, and more freely
exposed to the light, multi])Iied Avith great rapidity."

Many of the vital endoM-ments of the Desmidien! liave already been do-

OF THE DESMIDIEiE, ^

scribed: we have noted their process of reproduction and of growth, the
moleciilai- and cii-culatory movements wthin them, tlieir slight locomotive
power ; but besides these, there ai-e others requiring to be mentioned : for
instance, theii- powers of secretion are highly pronounced ; — the production
of firm envelopes to fronds and sporangia ; the formation of starch-grains, of
colom-ing matter, and of oil-globules within; the exhalation of oxygen fi'om
the surface, — a respii-atory act ; and lastly, their ability to resist decomposition.

The Desmidieae serve as food to many sorts of small aquatic animals, to
the Rotifera, to vaiious Annelida and small Crustacea, and to the freshwater
MoUusca. They are supposed also to preserve the freshness of the water,
and by the oxygen they exhale, to furnish the vital aii- necessary to the
respii-ation of the aquatic animals found mth them. They are subject to
desti-uction not only in the way of supplying food to animals, but also by
disease. Por instance, Cohn has shown (Entiv. d. mikr. Alg.) that the
Closteria are attacked by a microscopic unicellular fungus, called Qhytridium,
the spores of which afiix themselves on the integument, and on germinating,
penetrate the cavity of the frond by their delicate fibres, and induce a pro-
gi-essive brealdng-up and absorption of the contents, until nothing but the
empty hull of the plant remains.

Mr. RaLfs has the following remarks (p. 13) : — " In aU the Desmidiese, but
especially in Glostenum and Micrastenas, small, compact, seed-like bodies of
a blackish colour are at times met with. Their situation is imcertain ; and
their nimiber varies fr-om one to foiu'. In their immediate neighboui-hood the
endochrome is wanting, as if it had been required to form them, but in the
rest of the frond it retains its usual character and appearance. I cannot
satisfy myself respecting the nature of these bodies ; but I believe them to
arise from an unhealthy condition of the plant, or else to be parasitic." With
respect to the views expressed in this extract, we are disposed to think Mr.
Ealfs right in his conclusion that the black bodies he met Avith were parasitic ;
and on comparing his accoimt Avith the figures and description of the parasitic
Chytridium in Cohn's memoir (Entiv.), it seems to us highly probable that the
globules referred to were no other than the spores of that microscopic fungus.

Por a long time disciission was life respecting the animal or the vegetable
nature of the Desmidieae. That it was the former was the prevailing
notion until within the last few years, when the improvements in the
microscope, and the more extended and accurate knowledge of the featiu-es
of vegetable life in its simplest manifestations, rendered this opinion no longer
tenable, and at the present day it may be considered exploded. It is un-
necessary, therefore, to go minutely into this question ; for it -will suffice to
indicate the most strildng distinctive characters, especially those which rest
upon the affinities of the family under consideration. Those readers who
would see the point fully discussed wiU do well to refer to Mr. Ralfs's admi-
rable monograph, to which we, and others also, resort as to a mine, for the
materials to build up a history of the Desmidieae.

An old argument advanced by Ehrenberg for the animality of the Des-
midiea;, was, that they had a power of volimtary movement Hke animals.
"Without staying to consider the loose and unphilosophic use of this term
volimtary, as applied to the motion, whether in the DcsmicHea; or in the
simplest animal existences, its occurrence can be no proof of animal life
seeing that it is exhibited by acknowledged plants, and in a still more marked
manner by theii- spores. Moreover, such movements are doubtless effected
by cilia, both in the animal and vegetable world alike, and are likewise
determined by the vital processes going on within and also without tliose
simple organisms, in relation with external media and with surrounding

22

GENEUAL HISXOHY OF THE INFU80IIIA,

physical conditions. Siebold, quoting Niigeli's opinions, says {J. M. S. i.
p. 120) — " The slow turning, and at the same time rare movements of the
Closteria (the gemis in which motion is more evident), present no character
of spontaneity; these motions are merely the consequence of an active
endosmosis and exosmosis, by which the water immediately sm-rounding the
Closteria, and consequently themselves, are put into motion." Again, as Mr.
Kalfs remarks, the motive power is less in degree than in the Diatomeaj.

Cell-multiplication by fission or transverse division, enumerated by Ehren-
borg as an animal peculiarity, is now so completely established as a vegetable
phenomenon, that it can claim no consideration when the question of the
actual afimities of a disputed organism is to be solved. And equally unde-
serving of critical examination at the present day is the complex animal
organization attributed by the Berlin microscopist to the fronds of Desmidiea;.
Concerning the apparent sac containing the moving particles in the Closteria
and in other genera, regarded by Mr. Dalrymple as a vegetable pecuharity,
Mr, Ralfs obsei"ves, " I confess I am unable to refer to any example in other
Algae of terminal globules like those present in the Closteria, but neither can
one be found amongst animals ; and £f in some respects they have an analogy
with organs belonging to the latter, in others they agree better with vegetable
life." On another argument raised, the same author remarks, " The con-
traction of the internal membrane of the Closteria, or the expiilsion of their
contents on the application of iodine or other reagents, cannot be rehed upon
as a satisfactory test for determining their nature ; for the blandest fluids vrill
in some cases (both among recognized Algse and the Closteria themselves)
occasion violent action." On the other side of the question, the act of swarm-
ing, the emission of actively motile germs (presumed in this family), the
presence of starch and of chlorophyll, the chemical relations between these
substances, and also with the oily matters formed in the fi'onds, the exhala-
tion of oxygen in sunlight, and the absence of azotized material in their
chemical constitution furnish reasons for an'anging the Desmidiea3 with
plants. Besides these reasons, others are foimd in the general form and in
the modes of propagation being precisely analogous with those in admitted
uniceUulai' Algae. Their intimate afimities with Algae are shown by the fact
that Meneghini and Klitzing placed Merismo-pcedia among the Desmidieae,
and that Braun refers the two genera Scenedesmtis and Pediastrum, rucluded
by Ehrenberg himself in the famUy in question, to the PalmeUaceae. The
process of conjugation, wHch has been often apiiealed to as a characteristic
of plant-Hfe, would appear, however, to be, in exceptional cases and imder
peculiar modifications, also an animal phenomenon, and therefore inapplicable
as a test.

Meneghini, who contends for the animality of the Diatomeae, has pro-
nounced {B. S. p. 497, 1853) the opinion that — " The Closteria and Des-
midieae in general are plants, and not animals. In the actual state of science
we ai-e compelled to admit this proposition. The organic structure, the phy-
siological phenomena, the history of their development, the chemical materials
they contain, manifest in these beings a perfect correspondence with others,
which in eveiy point of view coiTOspond with the abstract idea of a plant.
But what they present in common with other beings cndcntly animal, is
merely an appearance, or at the most, a resemblance in external form.
Ehrenberg was misled by this appearance, and, guided by this fallacious
similitude, tliought that he discovered in the Dcsmidiea) the same oi-ganic
pecuharities wliich proved the animality of other beings."

Respecting the affinities of tlio Desmidicaj, Mr. Ralfs states that, " on one
side, they arc allied to the Conjugatac (Zygnemea)) by similarity of reproduc-

OF THE DESMTDIEiE.

23

tion, and on tho other to the Palmolleae, by tliG usually complete transverse
di\ision, and by the presence of a gelatinous investment. Indeed the relation
to the latter is so intimate, that it is difficult to say to which family some
genera belong. . . . Some species of Scenedesmus may be allowed to have an
almost equal claim to ranli with either." Again, they are related to the
Diatomeoe by similai-ity in the reproductive process.

In Elu-enberg's system of Polygastria, the Olosteria were placed together
as a distinct family, imder the name of Closterina, whilst aU the other genera
of Desmidieae were ranged as a section of the Bacillaria. This separation,
based as it was upon presumed stnictiu-al peculiarities, is no longer accepted
by microscopists, who cojoin Closterium with the several genera included in
Ehrenberg's section Desmidiacea in one group — the Desmidieas.

The division of this family proposed by Mr. Kalfs is made according as —
1. The plant forms an elongated jointed filament (by incomplete division of
its cells) ; or — 2. The frond is simple, fr'om complete transverse division, and
distinctly constricted at the junction of the segments, which are seldom longer
than broad ; sporangia spinous or tuberculated — rarely, if ever, smooth ; or —
3. The frond is simple, as above, generally much elongated, never spinous,
frequently not constricted at the centre ; sporangia smooth ; or — 4. Cells
elongated, entii-e, fasciculated ; or — 5. The fr-ond composed of few cells, de-
finite in number, and not forming a filament.

This last section is so exceptional in g'eneral characters, and especially in
the mode of reproduction, that Braun detaches it from the Desmidieae and
associates it with the PalmeUese. In this plan we coincide, and have there-
fore treated separately this last section of Mr. Ralfs, comprehending Pedias-
trum and Scenedesmus.

Kiitzing {Species Algamm) includes the Desmidieae in his subclass Mala-
copHYCEJE, suborder Chamajphyceae.

Mr. Ealfs enumerated 20 genera ; viz. — In Sect. 1, Hyaloiheca, Didymo-
prium, Desmidium, Aptogonium, SphcBrozosma. Sect. 2, Micrasterias, Euas-
trwm, Cosmarium, Xanthidium, Arthrodesmus, Staurastrum, Didymocladon.
Sect. 3, Tetmemorus, Penium, Docidium, Closterium, Spirotcenia. Sect. 4,
AnJcistrodesmus (lihapMdium). Sect. 5, Pediastrum, Scenedesmm.

When compihng his systematic work, Kiitzing appears not to have seen
Mr. Ralfs's monograph, but only his detached papers in the Magazines, and
consequently was unable to compare the genera estabHshed by the English
author with those described by himself. The consequence is that Kiitzing
describes several genera, not admitted by Mr. Ealfs, who has otherwise dis-
posed their representative species, disallowing the supposed distinctive generic
character. Nevertheless it seems desirable to enumerate the additional
genera of Kiitzing, since several are new (unnoticed by our English authority),
and derived from the papers of Ehrenberg or of other obsei-vers, or from his
own researches. Those instituted by Ehrenberg were introduced in oiu- last
edition.

The additional genera are: — TrocMscia (K.), Tetraedron (K.), PitMscus
(K.), Staiiroceros (K.), Polysolenia (E.), Mia-otlieca (E.), Pohjedmm (Niigeh),
Zygoxanthium (E.), Phycastrum (K.), Asteroxanthium (K.), Stephanoxan-
ihium (K.), Grammatonema (Agardh), Bamhusirm (K.), Isthmosira (K.)
Spondylosum (Brcbisson), EMampia (E.), OemimUa (Turpin), Monactinus
(Corda), Staurogonia (K.), Sphoirastrum (Meyen), Sorastrum (K.), Ccelas-
trum (Niigcli), lUmphidium (K.), Oocardium (Niigcli). '

The value of the several genera instituted and their characteristics form
the subject of the systematic history of the Desmidiete by Mr. llalfs in the
subsequent portion of this treatise.

24

GENEEAL UISTOHY OF THE INFU80UIA.

SUBFAMILY PEDIASTRE^.
(Plato I. 37 to 69. Plate II. 19, 36, 37.)

This includes the genera Micrasterias and Arthrodesmus of Ehrenberg, the
Pediastrum and Scenedesmus of Ealfs, Kiitzing, and others ; and, in addition
to these two, to foUow Nageli's classification, Sorastrum, delastrum, and
probably also Sphcerodesmm.

At the time Mr. Ralfs wrote, much uncertainty prevailed respecting what
should be considered characteristics of species, and what were the modes of
propagation ; and it is much to be regretted that, although some of the diffi-
culties and doubts are removed, ovu' knowledge of these microscopic Algaj is
far from complete.

Ehrenberg, in harmony with the general views of organization he had
adopted, placed Micrasterias and Arthrodesmus among the Desmidiese, in the
class of Polygastric Infusoria, and described the existence in them of ova,
stomach-vesicles, and seminal glands. Yet he was unable to point out one
single feature reaUy indicative of their animal natiu-e, even locomotion being
unrecognized. Indeed, among those who might be inclined to foUow the
distinguished Berlin naturalist in attributing an animal nature to most of his
Polygastria, the generality would hesitate, in face of the many intimate ho-
mologies, structui'al and physiological, between the Pediastrese and admitted
Algee, to predicate it of that group of organisms.

EiGUEE, CoMPosiTioif, AND CONTENTS OF Cells. — The individual cells among
the Pediastreae do not exist, isolated and independent, but are united together
in a fi'ond, in determinate number and in a definite arrangement for each
genus. In all the species they agree in having a membranous wall like the
DesmidieaB and PalmeUese. We confine ourselves, it should be imderstood,
in noting the figure of the cells, to the matiu'e phase or stage, which, although
but one of several known phases, is that most marked, best understood, and
most perfect.

The cells of Scenedesmus (Arthrodesmus, Ehr.) (I. 37 to 43) are entire, oval,
oblong, or fusiform, with their ends either rounded or pointed. Their length
is from two to four times their width or thickness, and they ai'e spherical on
a transverse section. They exhibit no constriction or sutm-e at the middle,
neither in their waU nor in their endochrome, and in these pai'ticulars con-
sequently dififer fi'om the cells of true Desmidiete. The membrane is fi-e-
quently drawn out in the form of straight or ciu-ved spines ; this happens
usually only with the cell at each end of the chain (I. 40, 41) ; but in a foAv
cases, other cells nearest to the outer ones become also armed -with spines
(I. 42). When this extension to the other cells occui-s, Niigeli remarks that
the spines do not appear on both the superior and inferior extremities of each
cell, but only on the upper of the one, two, or three next within the one
terminal cell, and on the lower extremity of the same number within the
other terminal cell (I. 42). It is rare that the central cells of the chain are
armed, and even when this occurs it is only with short spines. In addition
to a spine, or, as may happen, a pair of spines fi*om the upper and lower ex-
tremity, the end cells at times have a third sjiine standing at right angles
from their sides (I. 41).

The cells of Pediastrum are considerably compressed, so that M-hen aggre-
gated they form a flattened tabular stnictiu-e (I. 44 to 48, 59 to 69). In
figure, as seen from above, they vaiy according as they occupy the margin of
the collection, i. e. are peripheral, or are central. The latter arc polj-gonal,
frequently hexagonal, and no doubt oAve this shape to mutual lateral pressure
duiing growth ; the maigiual cells Iiave fcAVcr sides, and arc frequently irre-

OF THE PEDIASTHEiE.

25

gulaily quadiilateral, but thek free margin is more or less deeply notched,
and therefore bilobed (I. 44, 45, 53, 62). The lobes are usually tapering,
and form a tubular process either mmcate or acute at the extremity (I, 62).
In a few cases the notch is not angulai-, but cui-ved and erescentic (I. 62) ;
in others again it is deep, angular, and gaping (I. 52, II. 27), and gives the
cell an irregidar figure ; this latter condition is more seen where only a few
cells are imited together, and where the lobes are not prolonged as pro-
cesses. In some species, moreover, the lobes are terminated by short hair-
like spines.

The notch on one side is not confined to the peripheral cells, but extends,
in several species, also to the contained cells of the frond (I. 52, 66) ; their-
lobes, however, are not tapering, but sharply truncate. Nageli instituted a
subgenus of Pediastrurn under the name of Anomojjedium, the chief charac-
teristic of which is the absence of bilobed peripheral cells (I. 46, 47, 48).

The cells of Ccelastrimi are hexangTilar (I. 49, 50, 51), the central ones
veiy regularly so, whilst the peripheral are rounded off on theii" free aspect
in one sjDecies, and in another notched and bilobed (I. 54, 55). Those, lastly,
of Sorastrum (I. 56, 57) are wedge-shaped or triangular, with rounded
angles ; they cohere by their apices, whilst the base is peripheral, often
rather concave or emai'ginate, and, as a rule, armed at each angle by a pair of
short spiaes. On a lateral view the cells are oblong (I. 58).

There is a pei-vadiag uniformity in the contents of the cells of the different
genera of PediastrcEB, which consist of the usual vegetable protoplasm, and
are spoken of collectively as the endochrome. At first the colour is veiy pale
green, but it becomes deeper with advancing age, and in fully mature or
decayiag cells is seen to change to red or brownish red, just as the leaves of
trees change colour on the approach of autumn. At first, the protoplasm is
clear and homogeneous, but ia course of time granules appeal', enlarge in
bulk, and multiply ia number. Moreover, each cell presents a single chlo-
rophyll-vesicle, which is least discernible iu very young and ia very old cells
(I. 53 to 58). It is ordinarily seen ia or about the centre of the cell, but
may occur on one side, as ia Pediastrurn JRotula. Aroimd this vesicle are
seen in several species clear circular spaces or globules, recalling those of
Glosterium, vaiying ia number in different cases from two to sis (I. 44, 45,
53). In Pediastnim JRotula, NageH observed tAVO such ; ia P. Boryanum and
P. Selencea (I. 44, 45), from two to six ; ia the species of Scenedesmics and
of Sorastrum (I. 57), one hyaliae space. This author likewise represents the
relative position of the chlorophyll-vesicle and of the translucent space to be
constant in similar fronds. In those made up of two cells only, the chloro-
phyll-vesicle is placed outside, whilst the clear- cavity lies agaiast the parti-
tion-wall. Iu chains of foxu- to eight cells the chlorophyll-vesicle is external

relatively to the central cell, and the clear space iaternal (I. 40, 41), the

position being regulated, not by the partition-wall, as in the PalmeUeiB in
general, but by the centre of the entii-e frond. OU-globules are also con-
tained in the cells ; their presence is readily demonstrated by the addition of
tincture of iodine, for they continue colourless when tiio surrounding mass is
coloiu-ed bro\ra ; their position often exhibits much regularity. Unless the
chlorophyll-vesicle be esteemed nuclear, no nucleus has been discenicd in the
cells of Pediastrea^. On one occasion Niigeli saw, in Pediastrurn Boryanum, the
endochrome disposed in a radiating manner around the chlorophyll-vesicle
an arrangement which often obtams in Algaj, and in many vegetable cells
where there is a central nucleus.

Number and DisrosrrroN of titk Cells in the Fhondr.— The cells of Pe-
(hastrese are always united together in compound fronds. The number so

26

GENERAL niSTORY OF THE INFUSOEIA.

united, and tlioii- mode of combination, differ in the different genera arid
species.

In Scenedesmm the cells are arranged (I. 37 to 43) in single linear series,
side by side,_ united by a mucous hyaline matiix, which is less abundant
than ia Pediastrvm. Two, mostly four, and less fi-equently eight cells are
concatenated ; and, as a rale, the line of union extends the entire length. Ex-
ceptions occui", owing to the junction-surfaces being less extensive, in the form
of chains of cells having a zigzag border, every alternate cell being depressed
below the normal plane, or in that of an obhque chain, having each member
m succession depressed beneath the preceding. Sometimes two rows of eight
cells eaeh lie side by side (I. 38), so that the one dovetails into the other by
the alternate elevation and depression of their component ceUs : this may
happen in the whole extent of the two coherent chains, or ia a portion
only of their length at one or other extremity ; or one chain may be broken
into two segments, each dovetailed to the other chain at ofjposite ends so as
to leave an unoccupied central space. The alternation of the cells in fi-onds
composed of two rows, is the result, according to Mr. Ealfs, of the oblique
manner of division. In the genus Pediastrum the fronds are generally com-
posed of a larger number of cells than in Sccnedesmus, disposed in the same
plane according to a defkiite and usually concentric arrangement, and forming
compound stellate fronds (I. 52, 63, 62, 66, 67), whence the term Micras-
terias (little star-like beings) invented by Ehrenberg, and also the second half
of the generally adopted term (Pedi)-astrum.

To distinguish species, Ehrenberg chiefly employed the number of the
cells in a frond — both the entii'e number and that of each concentric circle,
together with the number of cu'cles. Succeeding naturalists, however, have
pointed out that the number of cells in the same species is subject to con-
siderable variation. Turpin detected the trae law determining their number,
and Niigeli further illustrated and enforced it. The latter writes that
(Einzell. Alg. p. 92) "the cells are united 2, 4, 8, 16, 32, or 64 together
in a frond. These nimibers are always constant in young fronds without
exception. In older specimens one or more cells may be lost, and the frond
become therefore apparently UTeg-ular. These cells do not spontaneously
detach themselves from the rest, but die, and are partially or entirely
dissipated, as a consequence of injury from some external cause, probably in
most cases by small aquatic animals. They ocem' in all stages of destrac-
tion, and when entii'ely vanished, the vacant space indicates their foi-mer
position. The cells are aggregated together in a single plane, which possesses
mostly a circular or somewhat rounded outline ; but in the disposition of the
cells there is considerable variety. In the case of 4 cells they are either all
in opposition (II. 27), or only 2 in the centre ; with 8 ceH^, one usually
lies in the middle, and the other 7 suiTOund it in a circular manner
(I. 52); less commonly, 2 are central and 6 peripheral (I. 62); rarely,
one occupies the centre with 6 around it in a circle, whilst the remaining
or eighth cell is placed on the pcrij^liery ; and still rarer, the disposition is
quite irregular. Where 16 ceUs arc combined, the rule is that there is one
in the centre surrounded by an inner circle of 5 and an outer cii-cle of 10.
At times, 4, 5, or 6 internal cells are cncii-cled by 12, 11, or 10 outer
ones (I. 53, 66, 67), whereby a double ling is produced: more nu'cly
the arrangement is completely irregular. Agam, 32 cells are mostly
80 placed that one central cell has ai'ound it 3 cii-clcs, the innermost of
5, the middle of 10, and the outer of 16 cells; less frequently, tlic 3
circles are respectively composed of 5, 11, and 15, or of 6, 10, and 16;
occasionally 5 internal coUs have 2 outer series, one of 11, the other of 16

OF THE PEDIASTKEiE.

27

cells; or 6 cells arc enclosed by 11 and 15, or by 10 and 16 ; or, lastly, tlie
distribution is partly or completely ii-regular. In the caSe of 64 cells, no
regular aggregation frequently is observable : sometimes 2 or 3 external con-
centric series are perceptible, where the position of the inner cells follows
no rule ; less frequently, the concentric arrangement can be followed to the
centre; when this is the case, one central cell may be enclosed by foui-
series respectively of 6, 13, 19, 25, or of 7, 13, 19, 24 ceUs; or again, 2
middle ceUs have aroimd them 8, 13, 18, 23, or 7, 12, 19, 24, or 7, 13, 19,
23 cells in foui- rows ; or fiu'ther, 3 central cells have 8, 13," 18, 22 cells
around, and so forth.

" The form of the genus Pediastrum has in general a decided tendency to
a concentric disposition of the cells. Thus 4 cells combine in 1, 8 in 2,
16 in 3, 32 in 4, and 64 in 5 circles. When this concentric ai-rangement is
disturbed, it occiu's more frequently in larger than in small fronds, and more
frequently among the central than the peripheral cells."

Braun (Gen. Nov. p. 71) has entered much in detail respecting the number
and disposition of the cells, and arrived at the same general results as Wag'eli.
He observes that " the same numerical law is common to all the species [of
Pediastrum], but the number may vary more or less within the legitimate
series, even indeed in one and the same species : the disposition also is liable
to variation where there is the Kke number of cells in the same multifarious
species ; and this so much the more the greater the number of cells. . . .The
legitimate (normal) series, viz. 1, 2, 4, 8, 16, 32, 64, 128, is explained by the
binary division which takes place in the formation of gonidia, and which is
quieUy arrested or continued for a longer period.

" I have no direct observations to show whether specimens consisting of a
single cell are generated singly from the pai'ent ceU, or, after being developed
in company with others, they have become dispersed by some accident, wMch
is very probable. Such specimens, belonging pretty clearly to Pediastrum
Ehrenhergii, occur everywhere in company with the multicellular fronds of
this species. Unicellular examples of other species are, it would seem, very
rare. I have seen one such of P. Bo tula ; of some which I think should be
assigned to P. Boryanum. Bi-cellular specimens I have only observed in the
case of P. Ehrenbergii : instances of 128 cells have frequently occurred to me
with P. valgum, and twice with P. Boryanum. The other numbers are common,
and occur in very many or in all species, or in the majority ; certain of them
indeed much more frequently than others.

" Numbers divergent from the normal series, whether incomplete or more
than complete (supra-complete), are rare, whilst veiy divergent ones are
very rai-e. The former have their origin in the process of fission and the
formation of gonidia, when one or other segment in the penultimate division
remains undivided, or divides once too often. Thus in P. Boryanum, specimens
are occasionally found having 15 instead of 16, 31 for 32, 63 for 64 cells, or
on the contrary, 17 for 16. Examples of 65 in lieu of 64 cells have oceurred
to me in P. asperum. The latter, i. e. those numbers widely divergent, may
originate, if in the earlier division of the cytioplasm [protoplasm] some' seg-
ment is, as it were, passed by, and subsequently enters agsiin in the scries of
segmentation. In this way the mmibers entering into the series 3, 6 12
24, 48, examples of whicli arc at hand, may be explained. Thi-eo cells liavo
been met mth by me in P. Ehrenhergii, and more frequently 6, both in this
species and in P. Potida ; 24 cells, once, in P. asperum."

Braun adds that, if any person should doubt tliat the number of cells chffers
in the same species, he has only to insjiect collections mado in the same place
and hvmg under like conditions, and to note the une(iual forms produced

28

GENEIUI mSTOUY OF TUE INFUSOllIA.

from the same parent indi'STidual, and lastly, to remark the analogy presented
in other allied genera, e. (j. Scenedesmus, Sorastrum, and Ocehstrum, to con-
vince himself of the fact.

Moreover, as shown by NiigeU, when the number of cells is the same in a
frond (coenobium, Braun), their an-angemcnt varies considerably, tending
more and more to irregularity as the cells are more multiplied. " The noi-mal
and most frequent disposition is orbicular, the cells being arranged, according
to their number, in one or several concentric circles, around either a single
central cell or none at aU. Where two cells axe placed in the centre, the
circles around incline to an elliptic figure ; from this a transition to an
elongated form still more aberrant from the orbicular type is indicated, in
Avhich the elongate- elliptic circles surround several intermediate cells placed
in single or double longitudinal series. By the less regular concentric or the
entirely confused disposition of the cells, the elliptic foi-m passes at length
into others stUl more abnormal, such as reniform, panduriform, cuneiform,
&c., aU which agree in having 64 or 128 ceUs. The regular concentric
arrangement is moreover deranged by the occasional intercalation of cells
referable to no one of the circles ; and lastly, OAving to an incompleteness
of the circles of ceUs, they become so connected one Avith another, that a
spiral disposition is the result, which, although abnoi-mal in eveiy species, is
in some specimens constructed with wondei-ful regulaaity. All these various
ari'angements arise from the manner in which the motile gonidia are disposed
and marshalled in their first stage ; for these are distributed within the
parent depressed orbicular cell, according to the laws of juxtaposition, in a
plane."

Another peculiarity in the disposition of the cells in the fronds of Pedias-
trum is, that sometimes, instead of being all in juxtaposition, so as to form
an unbroken congeries of cells, or, in the language of Nageli (op. dt. p. 94),
instead of being parenchymatic, apertui-es or interspaces are left between
them (I. 53). This is most seen where the inner cells are more or less bi-
lobed, so that an opening subsists between the lobes of each cell ; but similar
apertures may likewise occur at the angles where the cells come into contact.
When the position of the cells in the table is regular, that of the foramina is
so also. Pediastrum Selencea with 16 cells has, as a lode, 6 large and 8 small
openings ; the large are bounded by 3 cells, the smaU by 2 ; the small spaces
are sometimes absent, when the large become very evident. Fronds of the
same si)ecies, having 32 cells, display usually 11 lai'ger interspaces lying
betwixt 3 cells, and 18 smaller enclosed between 2 cells.

Anomopedium, a subgenus of Pediastrum, differs not only in its peripheral
cells not being bUobed, but also in having its cells partially disposed in a double
plane (I. 46, 47, 48). The cells which are in the numerical series of 4, 8,
16, 32, and 64, are subject to manifold arrangements, and frequently aggre-
gated quite irregularly. They are mostly so placed, that in one, two, or even
three (hrections, they can be clearly discerned to be in parallel straight rows.
A concentric disposition is quite exceptional ; not imfrequently, instead of all
the cells occupying the same plane, some form a pai-tial second layer upon
the other about the middle. '

In Coelastrum (I. 50, 51, 52) the hexangular cells are so arranged that
they form a hollow, globular, areolar frond. Coel. sphcericum consists of 25
to 40 cells, wliich compose a lamina perforated by 3, 4, 5, 6, 8 angular meshes
(areola)) somewhat larger than the cells themselves, and from 13 to 22 in
number. Ccel. cubicum consists of 8 cells united in a cubical form, hollow
inside : on each side arc 4 cells enclosing a quadrangular aperture.

Lastly, in Sorastrum the wedge-shaped or cordate cells (I. 56, 57) are all

OF THE PEDIASTREJ?.

in close apposition and form a globular frond. The cells in the typical species,
S. echinatum, arc 8 or 16 in number, and so arranged that all their apices
converge towards and meet in the centre of the frond.

S^hcerodesmii,% which probably is rightly accounted one of the Pediastrea^,
is named, but not described, by Nageli ; we are, however, informed by Braun
(Gen. Nova, p. 70, in foot-note) that its fronds are composed of 4 spherical
cells closely aggregated in a rhomboidal form.

Development and GR0-\\TrH. — Sceneclesmus multiplies by fission, as Ealfs
believed, in an obli(iue du-eetion, but according to Nageli, parallel to the long
diameter of the cells. The former adopted his opinion from the features of
biserial chains ; but the latter interprets those appearances by the simulta-
neous occui-rence of longitudinal and of transverse fission (I. 37, 39).

The process of self-division commences generally at the same period in
each cell of the frond (family, Nag-eh), and proceeds with so great rapidity
that its intermediate stages are unobserved. One of the two terminal cells
(I. 39), or, in an eight-celled, probably the two, sometimes remain for awhile
undivided. The ceU separates into two, then each of these again into two
others, and at times this act of subdivision is repeated a third time. By a
more prolonged act of segmentation of the cell-contents, the result is a number
of minute cells which arrange themselves in rows of two, four, or eight, and
thus form miniature fronds which ultimately escape the parent-ceU. by rup-
ture. Occasionally, adds Nageli, the young fronds are connected together
by mucus, formed by dissolution of the parent cell-wall. Development takes
place in parallel planes, although by their increase they become mutually
compressed and irregular, and the chains curved prior to their discharge.

This production of macrogonidia and their cohesion into fronds has not
been seen by Braim., and is, in his experience, an exceptional phenomenon
{Qen. Nova, p. 67).

When Ml-. Ealfs wrote his work on the Desmidiese (in 1848), he had to
confess himself altogether ignorant of the modes of reproduction both of
Pecliastrum. and Scenedesmits. He, however, described self-division of the
cells in both genera, but rightly regarded this process as one not of develop-
ment, but of vegetative increase and repetition. On this subject he remarked
(ojo. cif. p. 182), — " I have not seen the cells during the process of division,
but I am informed by M. de Brebisson that it takes place at the notch, in
the same manner as in other Desmidieae : hence the cells in each cu-cle ai-e
connected at theii- ends, like those of the filamentous genera. I do not,
however, understand in what manner the additional cii-cles are formed, nor
why the numbers in each circle are so constant."

Nageli, likcAvise, was equally ignorant of the propagation of Pediastnmi,
but thought it highly probable it resembled that of Scenedesmits. Tlie num-
ber of cells in a table or frond, indicated to his mind its production by a series
of fissions in the power of two ; and ho presumed that a new frond was gene-
rated within a parent cell by division of its protoplasm, just as in Scenedesmus,
— a supposition supported by the fact that the entire young fronds are not
larger than the single cells of mature specimens, that like these they arc
composed of the same number of individual cells similarly disposed, and
undergo no subsequent segmentation into a larger number.

The more recent researches of Braun are confirmatory of the views of Na-
geli (Gen. Nova, p. 68), Amid a large number of specimens of Pediastritni
Boryanum he detected the escape of, in most instances 32, more seldom
of 16, and rarely of 8 gonidia, from a parent cell,— the number gene-
rally, but not invanably, corresponding mth that of the cells composing the
mature frond or coenobium. The collection of gonidia was enclosed by a

80

QEITEIIAL niSTOny OF THE INFUSOKIA.

common envelope, within which they moved actively about for a quarter of
an hoiu' before coming to a state of rest, and aiTanging themselves regularly
in a frond (I. 64). This sac is described in the author's work on Itejuvenes-
cencG {Ray Soc. p. 184) as the vesicular inner layer of the mother-ceU.
He -witnessed this production of gonidia from many, but not from aU the
cells of the fi'onds, for it sfeems to take place in them in succession, and pro-
bably in some definite manner, according to their position in the frond. He
further describes the development of microgonidia to follow the same plan as
that of macrogonidia, but to differ from the latter in number, size and form,
and in duration and cessation of motion. Macrogonidia have a subglobose
figure, a diameter of jxiT^^ ^ millimetre ; one side hyaline, and scarcely
elongated, the other turned towards the periphery of the frond, green, and
by-and-by extended and emargiaate : no vibratile cUia discoverable on them.
They never leave the sac in which they are produced ; and the young fi-ond is
seen, until the close of the second day, loosely enveloped by a gelatinous
layer, which ultimately disappears by deliquescence (I. 64).

On the other hand, microgonidia are at first densely aggregated and
closely invested by the sac in which they ai'e generated ; like macrogonidia
they are subglobose (I. 60, 61, 68, 69). After a while the sac is gradually
dilated, and, growing more and more in length, forms an acute hyaline beak
(rostrum) as long as the green portion, which constitutes the rest, or the
body, of the gonidium. This rostrum, moreover, is furnished either with a
pair of cilia, longer than the body, or with a single cUium. The length of
these developed microgonidia is nearly y^th millimetre ; the thickness YTirt^
(I. 61, 68, 69). The movement withia the sac is at first slow ; but when
this is fuUy expanded, it is very active, and continued for an houi' and
upwards, until the sac is ruptured, and the whole heap of microgonidia escape.
The number of microgonidia cannot, by reason of their aggregation and their
swarming movement, be easily determined ; at least 64 occur in a sac, and
most commonly many more, for instance, 128. Of theu- subsequent history,
Braun can give no satisfactory account.

A reference to the same able writer's book on Rejuvenescence (R. S.)
informs us, at p. 200, that before the formation of the gonidia of Pediastrum,
the single starch-grain, the nuclear character of which has been above re-
marked, disappears. From the same source we also obtain a series of illus-
trations of the development of macrogonidia, of their arrangement in the
characteristic stellate frondose form, and of the vaiieties in the number and
arrangement of the component cells, which may be seen in examples of the
same species of Pediastrum.

The development both of Ocelastrum and Sorastrum is unknown.

The Pediastrese are of freshwater habit, living in ponds, on which they
frequently form, in conjunction with other small plants, a coloured film or
scum. They are also common in turfy pools on moors, and invest the surface
of various aquatic plants.

Systematic Position op PEDiASTREiE. — Mr. Ralfs followed Ehrenberg,
Mcneghini, and others xa placing the Pediastreaj among Desmidieie; but
Corda, Niigeli, and Braim have separated the two as distinct tribes. Indeed,
Mr. EaLfs has modified his views since the publication of his monograph, and
would treat the Pediastrea; as a subfamily of Dcsmidicse. Niigcli {Einzell. AJg)
arranges them with the PalmeUea? as a distinct group, and in this lia.s the
support of Braim (Oen. Nova, p. 69). These natiu-alists point out that the
distinctive featiu-es between the Pcdiastrea? and the Desmidiete, are that the
former neither conjugate nor multiply by continued transverse division of tlieir
cells in the same direction, each newly-formed segment acquiring all the

OF THE DIATOMEiE.

31

characters of a complete cell ; that, unlike the Desmidiese, they propagate by
gonidia; have but one instead of two or more equaUy-sized starch-grains
and a central nucleus ; and that their fronds are not distinguishable into two
symmetrical halves. " The Desmidiese ai-e evidently multicellulai', or pseudo-
uniceUular, from separation of their cells, whilst (says Braun) Pediastrum
is a true unicellular iUga rendered pseudo-multiceUular by the cohesion of the
cells. The aggregation of ceUs in Desmidieae is always uniserial, filiform or
concatenate ; the fronds of Pediastrum are grouped on a plane of a disc-form
or frondose character."

Braun next traces the affinities of Pediastrum, and remarks that, althoiigh
it resembles Hydrodietyon in the construction of its fronds (coenobia) by the
connexion of motile gonidia, yet since in Hydrodietyon the gonidia are
simultaneous, and in Pediastrum successional, it is rather an analogy than
an affinity which exists between these two genera. However, he admits the
con-ectness of the association of Pediastrum with the genera NageU iudicated,
vi2. with Sorastmm, Ccelastrum, Scenedesmus, and probably Sphcsrodesmus,
and would add to their number the genus Staurogonia (Kiitz.), the Orucigenia
of Morren {Ann. des Sciences Nat. 1830, p. 404). AU these genera agree
with Pediastrum in the successional formation of gonidia, yet differ from it
m other particulars except m the construction of the frond from motionless
gonidia. Among other genera, Polyedrum may be likened to Pediastrum ia
the form of its cells, but its propagation is unknown ; lastly, Characium and
Cystococcus agree with Pediastrum in the successional genesis and activity of
their gonidia.

To this elucidation of the afflmities of Pediastrum we have to add the
observation of Cohn {Entwick. d. miJcr. Alg.), of the analogy or affinity in
general structure between this genus and Gonium.

The division of Pediastrum into tribes or subgenera, as proposed by Braun,
and the distinction of species of the Pediastreae in general, will receive due
consideration in our systematic account of the family.

II.— OF THE FAMILY DIATOME^ OR DIATOMACE^.
(Plates IV. to XVII.)

General and External Chaeaotees of DiATOMEiE. — Testides or Frus-
tules. — Figure : free, concatenated, and fixed Forms. — Varieties of Filaments
and of Pedicels. — Aggregated Frusttdes. — The Diatomeae, Diatomacece, or
CymbeUeae, are unicellular organisms composed of two opposite plates or valves,
generally convex, and of an intei-posed connecting third segment, forming
together a miniature box of a sUicious nature, enclosing a soft organic matter,
rarely green, but usually yellowish or orange-brown in colour. They inliabit
either fresh, salt, or bi'ackish water.

They were reckoned by Ehi-enborg among the Bacillai'ia, and liave in con-
sequence been sometimes described as sUicious BaciUaria.

Each individual Diatom enclosed in its silieious envelope is spoken of as a
frastule, testule, frond, or baciUimi, and in general phraseology as a cell.
The first term is that now most in use, wlulst " testule " and " bacillum "
are words^ rarely employed, except in the works of Ehrenberg and of his im-
mediate disciples.

A rectangular or prismatic figure most widely obtains in this family • and
the angles of jimction of the valves are as a rule acute. Deeply notclied
fronds, Uke those in Desmidiete, e. g. Micrasterias and Euastrum, do not occur •
and the production of spmes and tubercles on the valves, so common in that
iamily, is rare among the Diatomete.

32

GENEllAI, HISTOTIY OF THE INFUSOaiA.

PiGmiE. — There is an immense diversity of figui-o among the fmstules,
determined chiefly by that of the o^jposed valves, but in some degree also by
the amount of development of the interposed third segment or cingulum
(XVI. 23, 24.) This last Mr. Ealfs considers an essential part of every
frustule ; but Prof. Smith states it to be a secondary, non-essential element
consequent on the growth of the organism, and specially developed in rela-
tion to the process of self- division. When this cingulum or " connecting
membrane " is much enlarged prior to fission, the figui-e as viewed on this
side is considerably changed, and the appearance of a double fiaistido often
occasioned.

Not a few of the Diatomeaa are much elongated and narrow, and from pre-
senting a wand-like figm-e (IX. 148, 166, 174 ; X. 184, 185), suggested to
Ehrenberg the term Eacillaria to designate the family. However, some
species are trapezoid, or square, or nearly so (X. 47, 21, 22), others round
like piU-boxes (IX. 131, 181; X. 200, 204), whilst others again are
almost globular or spheroid, owing to the great convexity of the valves.
Several genera are boat-shaped, scaphoid, or navicular in figui-e (IX. 139,
135 ; XII. 5, 6, 8, 48, 43) ; some are rather oval, egg-shaped, or ovoid ;
many resemble thin flattened discs — are discoid (XT. 33, 35, 36, 39) ;
many are wedge-shaped — cuneiform, or cuneate ; a few are triangular (XI.
43, 45) ; lastly, some are curved or twisted on themselves, and others assume
in certain directions a sigmoid pr an undidated figure (IX. 144, 145.; XY. 11,
22, 59, 60). Evenly-curved valves are said to be arcuate, such as those of
Eunotia (IX. 165 ; XVI. 10, 18), and of some species of Cymbella and
Nitzschia, whilst the peculiarly-twisted valves of Gampylodiscus (XVII.
517) are saddle- shaped. In Ci/matopleura, again, the surface of the valves is
undulated, and when bent rather sharply at an angle on themselves, the
valves become geniculate, as in Achnanihidiv/m.

As a rule the frustules of Diatomeae are symmetrical, and consist of two
equal and similar halves ; but exceptions to this are found in the Achnanthea9,
Cocconeidae, and one or two other families (IX. 159).

Another variety of frustules is described as winged or alate, — the ala being
a smooth expansion in the form of a margin (XIII. 5, 6, 7). The alas may
arise from the margin, and are then said to be marginal, as in Surirella, or
othei-wise from the disc, as in Tryhlionella, in which they are called submar-
ginal. A further modification of the valves affecting the figm-e is exemplified in
Nitzschia and AmpJiiprora, which have a longitudinal elevated ridge extending
from one extremity to the other ; such ridges are called keels, and the valves
keeled or caiinated. In the discoid forms two portions are commonly distin-
guishable, viz. the disc and margin or rim (XI. 31, 35, 38), the one at times
separated by a distinct line, and often presenting different sculpturing from
the other. The disc moreover exhibits occasionally at its centre a promi-
nence or elevated thicloiess called an umbo or boss. In Eujjodisnis (XI. 41,
42) tubular horns come off from the surface of the valves, and in Tnceratium
from the angles.

The extremities of some species, e. g. in Nitzschia and PUurosigma, are
extremely elongated, forming long, filiform, tubular processes ; and in Den-
ticella, Biddidphia (II. 40, 48, 50), and lihizoselenia (Ehr.), short tubidar
processes and spines are produced from the surfaces and margins. These
processes are commonly simple, but according to Ehrenberg arc branched
(ramose) in the genus last cited, and in Dicladia and Syjuiendrium. More-
over, very singular hispid and sometimes bifid processes or styles have been
noted on the valves of some species of Goniothedim (Ehr.), recalling by
their figure that of the spines on the sporangia of many Desmidiea?. Other

QF THE DIATOMEiE.

33

Diatoms, referred by Mr. BrightweU {J. M. S. 1856, p. 106) to the genus CJice-
toceros, have highly developed spines on the valves, besides the two pairs of
veiy long filiform smooth or spinous horns springing from the fnistules
themselves, or from the interposed cingulum. Gerataulus is another genus
provided with a pair of long horn-like processes.

Great variety of outline may prevail in a genus, so considerable indeed
that an accurate definition is -with difficulty laid down, the characteristics
shading o& thi'ough several species, until at length the similarity to an as-
sumed typical form is much diminished, whilst on the other hand an ap-
proach is made towards the features of another genus. The like latitude of
form prevails also vdth species, and gives rise to very numerous and fre-
quently perplexing varieties. On this topic Prof. Smith remarks — " While
a typical outline of "its frustule is the general characteristic of a species, this
ontlme may be modified by the accidental circumstances which surround the
embryo during its growth and the development of its silicious epiderm ; then,
any such aben-ation of form becomes stereotyped by the process of self-divi-
sion of the fnistule, generating multitudes of others slightly deviating from
the normal form." It must not be forgotten that the figure is greatly modified
or entirely changed by the position of the valves, whether seen in face or on
one side ; for each frustule generally presents four planes or sides, and, unless
regard be paid to this circumstance, one genus may be mistaken for another,
or even each view be presumed a distinct genus. Thus in the genera Navicula,
Pinnularia (XII. 5, 6, 15, 18), and in many others, the frustules are on one
aspect boat-shaped, but on the other oblong with truncated ends, or prismatic.
In the genus Triceratiwm (XI. 43, 44), the difference of figure is very re-
markable according to the side viewed (as presently illustrated). It is there-
fore necessary to examine a specimen on every aspect it presents : this can
generally be effected by the accidental rolling over of fnistules under inspec-
tion, or can otherwise be brought about by a very slight sliding movement
of the thin glass cover upon the slide under the microscope.

Mr. BrightweU thus describes and explains the transitions of form produced
by a change in position of the frustules of the genus Triceratium {J. M. S.
i. 248) : — " The normal view of the frustule may be represented by a vertical
section of a triangular prism. If the frustule be placed upon one of its flat sides,
we look down upon its ridge and obtain a front view of its two other sloping
sides. If it be placed upon one of its ridges, we have a front view of one of
its fiat sides, generally broader than long, and of its smooth or transparent
suture or connecting membrane. If the frustule be progressing towards
self-division, it is then often considerably longer than broad, and when nearly
matured for separation presents the appearance of a double fr-ustule."

It would be in vain to attempt to describe all the numerous forms assumed
by the members of this extensive family ; the representations in the plates
of this volume wiU convey the clearest notions of their diverse outline and
markings (see Plates 4 to 17). Great diff"erence unfortunately has existed re-
specting the sides which should be esteemed primary and afibrd specific cha-
racteristics, and those which should bo held as oiily secondary; and the
nomenclature of the surfaces has been equally a matter of dispute and uncer-
tainty. Ehrenberg employed the terms dorsum, venter, and lateral surfaces
or sides, but so loosely that they do not always indicate homologous portions
Thus he has often called a convex smfaco the dorsum, simply from its convexity'
and a concave one the venter, on account of its concavity. Kiitzing attemnted
a more certam and scientific phi-aseology by calling those sides which have
no central opening (umhiUcus), but through whicli self-division occurs the
pnmary sides, and the other two the secondary sides, further distinguishing

34

GENEHAL HISTORY pF THE INFUSOKIA.

the latter into a right and a left with reference to the frustulo when lying on
a primary side. The left side is often concave, and the right convex ; mostly,
however, the two are alike. As a general rule the primary sides correspond
with the lateral surfaces, and the secondary Avith the dorsum and venter in
the terminology of Ehrenherg. Mr. Ralfs, in his papers in the Ann. Nat.
Hist., used the simple terms '//-on* view' and 'side view,' corresponding £
respectively with Kiitzing's names primary and secondary sides. The llev. "
W. Smith adopts this nomenclature as the most convenient for the English
student, and uses the term ' front view ' to denote the aspect of the frustule
when the valvular suture (connecting membrane), or the Une along which
self- division takes place, is tui-ned towards the observer, and the tenn ' side
vieiv ' when the centre of one valve is directed to the eye. He adds —
" Even these terms will require modification when applied to some of the
more complex and irregular forms ; but in general their meaning will be
sufficiently obvious."

It must happen, therefore, from this terminology, that at times a front
view cannot be said to exist, viz. when the connecting membrane is obsolete
and the opposed valves are closely applied to each other, a suture alone in-
dicating the line of junction.

In size the Diatomeaj vary very greatly ; some individual frustules are
cognizable by the naked eye, whilst others require the highest powers of
the microscope to display them. Even among specimens of the same species
great diversity of size prevails, — a peciiliarity much determined by the cir-
cumstances surrounding a frustule at the period of its development, and
afterwards perpetuated through a long series of individuals multiplied by
self-fission.

The Diatomeae exist under three chief forms, as — 1. Single isolated free
fr-uskdes. 2. Erustules attached by a stalk, stipes, or pedicle. 3. Fi-ustules
coherent in chains, or aggregated together in ramose tufts by an intei-posed
gelatinous substance. The third form is the consequence of incomplete fission,
or of imperfect separation after fission. Incomplete fission and consequent
concatenation are observed in Bacillaria, Meridian, Himantidium, Melosira,
Odontidivm, Striatella, Fragilaria, &c. (IX. 131, 167, 171, 175, 176, 177) ;
and the form of the chain or filament produced will be deteiToined by the
figure of the individual fnistiiles composing it. For instance, if these be
rectangular, then the resulting chain (IX. 171, 172, 176 ; XIV. 2, 4, 6, 13)
is straight, but if wedge-shaped, it is curved or spiral (IX. 177, 179 ; XII.
21). The extent and degree of attachment of the adjoining finstules differ
in different genera ; thus, in Bacillana it is very slight, and readily yields,
allowing one segment to gUde on another, or to sepai-ate from it, except at
one point, yet at the same time possessing the power of recoveiing itself. In
Odontidium, Himantidium, Denticida, and Meridian (IX. 177), the mutual
adhesion of the several segments is stronger ; and after the opposed sm-faces
have been separated, futui-e adhesion is not effected. In Fragilaria, the ad-
herence is more tenacious. In Diatoma, Tahellaria, Qrammatopliora , Am-
phitetras, &c. (II. 46 ; XI. 22, 52 ; XTV. 23), the frustules hang together by
a sort of hinge inserted between adjoining angles in a zigzag fashion. In
Isthmia, this hinge or connecting link attains a greater magnitude, and, in
fact, is double. In Podosira (II. 45) and in some species of Melosira a
junction-process is developed from the centre of each frustule in the chain.
In other Melosirce and in Orthosira, the junction-surfaces are toothed (den-
tate), and thus hold the adjoining frustiiles in firm union. In the instance
of Biddidphia (II. 46, 48), the surfaces in union are curiously elongated at
the angles into roimdcd or horn-Ukc processes, whilst their convexitj- is

OF THE DIATOMEiE.

35

crowned by several bristles or seta). Lastly, in Eucampia (II. 43) the
junction-surfaces arc so excavated, that when the frustules are concatenated a
filament is foi-med, perforated by oval foramina.

In not a few genera, as above mentioned, the attachment is at opposed
angles, and a zigzag chain produced ; but in Isthmia (X. 183) it is peculiar
in being indiscriminately made at any part of the adjacent frustule, and
thereby produces an irregularly branched filament.

The above examples will suffice to illustrate the characters and varieties
of concatenation in the form of filaments, whether straight or spiral ; but it
is necessary to add that the width of a filament " equals the length of the
fnistule or valve measured along the suture or junction-line, and that the
breadth of the valve denotes the thickness of the filament " {Smith, Synops.
ii. 6). In those instances in which frustules are connected together by a
process or smaU isthmus acting as a sort of hinge, the concatenation cannot
be ascribed to incomplete division only, for the existence of such a process is
the result of a special formation which essentially corresponds with the
pedicle or stipes of fixed species.

Numerous Diatomese grow attached to foreign bodies by a stalk of variable
length, and which, although generally simple, is sometimes compound by
dividing and subdividing in a ramose manner. Even among the recognized
free Diatomese, such as Navicula, Pinnularia, NitzscMa, &e., specimens are
not unfrequently seen adherent by one extremity, about which they turn
or bend themselves as on a hinge ; however, in these instances such union
is but temporary, and no connecting medium exists. In Synedra (X. 184),
on the other hand, a bond of union occurs in the form of a Little gelatinous
conical nodule, resembling very nearly the hinge-Kke isthmus which binds to-
gether the frustules of many genera in a sort of zigzag chain. By the process
of self-division it also comes to pass that groups of Synedrce occur attached
together by the same point, in a fan-like or a stellate form, as in S. radians,
S. affinis, &c. In other species detachment after fission is too speedy to
allow of this sort of combination, except of some two or four individuals.
The fan-like collection of frustules is said to be flabellate, fan-Hke, or
radiating ; and when the component members are curved, they and the bun-
dles they form are described as arcuate. The nodule of attachment oceui'S
in various degrees of development, and attains in this same genus Synedra to
the dimensions of a pedicle — ex. in Synedra swperba, and even to branch,
as in Synedra fulgens and Synedra pulchella.

When a stipe branches, it does so normally in a dichotomous manner by
the very circumstance of the process of self-division, each new individual
produced by that act developing its own secondary pedicle, or pedicel.

This regular dichotomy is instanced in the genera Dorypliora (XIV. 21),
Cocconema (XIII. 10), and Qomphonenvx (XIII. 11). In Licmophora (XIII.
20), and in one species of Bhipidophora, viz. Rh. Dalmatica, an irregular
branching — essentially dichotomous, however — is met with, and is thus ex-
plained by Prof. Smith : — " In Bhipidophora paradoxa and Bh. elongata,
self-division is immediately followed by the separation of the half-new frus-
tidcs and a dichotomy in the filamentous stipes, while in the present genus
the fnistules remain for a time coherent, and continue dividing and mul-
tiplying on the summit of the pedicel, which becomes elongated and incras-
sated at each successive repetition of the process .... A branching, or rather
longitudinal rupture, of the pedicle takes place at irregular intervals ; and the
entire organism presents us with more or loss complete flabella (fon-liko
clusters) on the summit of the branches, and imperfect flabella or single
frustules irregularly scattered throughout the entire length of the pedicel "

D 2

36

GENEIiAL niSTOEY OF THE INFUSOEIA.

The same authority has the following remark on the process of ramification :
he says (i. 75), " When self-division (i. e. of the frustules) is completed, the
extension of the filament below the fiustules is suspended, a joint or arti-
culation is foi-med at the base of the dividing frustule, and each of the half-
new fnistules begins anew, in its progress towards special self- division, the
secretion of a new joint or intemode ; and a dichotomy is the result."

The occurrence of the double condition of union of frustules in a con-
catenate manner and of attachment by a pedicle is illustrated in the genera
Achnanthes (X. 201, 202), Striatella (X. 203, 204), BTiahdonema (XIII. 27),
and Podosira (II. 45). In Melosira also, attached species occur ; and Prof.
Smith inclines to the opinion that all filamentous Diatomea3 are stipitate on
their first production. In the second stalked genus cited, viz. Striatella, the
stalk attains the highest development, but remains slender and unbranched.
Between this most developed form and the mere nodules of attachment in the
genera Achnanthes and Melosira, every intermediate phase is encountered.
In any one species, however, there is no positive determinate length of the
stipes, for this varies according to the idiosyncrasy, vigour, and external con-
ditions affecting the organism ; consequently characters derived from the
dimensions of the stems can have no specific value.

There is a large section of Diatomeae in which the frustules are diiftised
throughout a mucous or muco-gelatinoujs mass, rarely confusedly, but mostly
in a definite manner, usually in thread- or tube-like branches, which nor-
mally ramify in a dichotomous fashion, and resemble on a minute scale the
tufts formed by many large sea-weeds. This peculiar aggregation is the
consequence of the large production and subsequent persistence of the mucus
which is throwTi out when the system of reproduction, whether by sporangia
or by fission, takes place. Histologically, therefore, it is homologous with
the pedicles and connecting nodules or isthmi thrown out during the act of
self- division, as also with the mucous stratum, which still very often persists
when that act is complete, around specimens of Cocconeis, Chcetoceros, Melo-
sira, Fragilaria, Striatella, &c.

The tissue thus composed of mucus and enclosed fnistules constitutes what
is called (from analogy with the large Algae and other Cryptogamic plants)
the frond, and afiects various shapes, in some measure characteristic of the
genera. Thus, in one of those so-called frondose Diatomeae, viz. Dichieia
(XV. 30, 31), it is membranous and leaf-like, and resembles a species of
TJlva; in Mastogloia, filiform with nipple-like expansions; in Encyoiuma
(XIV. 22), Homceocladia (XIV. 37, 38, 47, 49), and Schizonema, filaraentous
and more or less branched ; in Colletonema subcohcerens, globose. Again, when
filamentous, the ramifications diff'er much in tliickness and in expansion, and
in the extent of adhesion between the branches ; where these are long and
slender they are called ' capillary,' and where contiguous branches coalesce,
they give rise to a submembranous condition. The degree and mode of
division, the collection of the branches into bundles {i. e. fasciculi), or, on the
contrary, their loose or diffuse arrangement, supply useful characters in the
distinction of species. Again, the fronds differ in consistence, being in some
genera or species more ligid, setaceoiis, or robust, in others softer, flaccid,
and more delicate : these opposite conditions furnish Prof. Smith with grounds
for the division of the genus Schizonema into two tribes.

The disposition of the frustules Avithin the mucous investment supplies
other important distinctions. Thus in DicJcieia it is irregular ; in Mastofjhia
each little fnistulc occupies " the summit of a little nipple-Uke cushion of
gelatine ; " in Berheleya (XIV. 34, 35) the fnistules are densely packed in
the filaments; in Encyonema they occur mostly "in single file, except

OF THE DIATOMEiE.

37

towards the extremities, where they are somewhat crowded withm the
distinctly tubiilai- filaments, and enjoy a certain latitiide of movement; and,
lastly, in Colletonema and Schizonema (X. 207, 208) they arc arranged
in one or more files according to the stage of growth, within less per-
fect tubes than in the genus last mentioned, and retained m situ by the
mucus axoimd. .

Ehrenberg recognized this tribe of compound Diatomeae, and mtroduced it as
one of the sections of his great family Badllaria, under the name of Lacernata,
or Naviculce with a double lorica. His acquaintance with the gi-oup was, how-
ever, very imperfect, and he appears to have comprehended m it organisms
quite foreign to it, and to have failed to give that precision to_ his classifi-
cation of the included beings which could alone confer a high scientific value
and permanence upon it. , , ,

Of the Envelopes of the Ekustules of Diatome^. — The Silidous Shell or
Lorica ; its Divisions and Structural Composition, MarTcings, Strice, Ganali-
culi, Puncta, Sfc. — Sufficient has been said of the mucous coat which at
certain times, and always in certain genera, surrounds the frustules of
Diatome®. The fnistules themselves remain to be described: they are
hollow variously-shaped cells having but one cavity — ^unicellular, and a
sihcious outer wall, unaffected by a red heat and by strong acids, which
would corrode and dissolve every other substance belonging to a living beiag
except silex. This silex is stated not to polarize light, as does the mriieral
silex not in combiaation with organic beings ; and the erroneous statement
made by some authors, of the polarizing effect of some Diatomaceous shells
is due to the circumstance, that they did not take care to thoroughly remove
the organic carbonaceous matter with which the silex is in union in the
frustules ia question.

The sUex, besides being united with organic matter, deposited it may be
within a cellular tissue, is contaminated by iron, which Professor Erankland
of Manchester states {Smith, Synops. p. xxi) "exists in the state of a
silicate or protoxide .... "and he attributes to its presence " the brown coloiu'
which is assumed upon exposiag the Diatoms to the influence of a moderate
heat; the protoxide of iron, by the gradual absorption of oxygen, being
converted into brown peroxide of iron, which assumes a redder tinge upon
being more strongly heated."

The relative proportion of siHoa varies within considerable limits in different
genera of Diatomeae. In several genera, perhaps in marine ones exclusively,
it is very deficient, and the wall of the frustule is little more than horny, or it
may be even flaccid, as for example in DicJdeia and Schizonema. The fnistules
of Fragilaria, Striatella, and Podosira are less firmly silicious than those of
many others of the filamentous Diatomeae. In some genera (those, viz.,
which produce tubular processes) silex is deficient or absent from the pro-
duced wall ; in Podosira this deficiency occurs at the apex of the valves, and
in Prof. Smith's opinion is probably intended " to allow a free secretion of
the mucus which unites the frustules and provides a pedicle for their attach-
ment to the plant on which they grow, as it does not occur on the non-
attached valve of the first-formed frustule. In the living state the absence
of silex is not perceived ; but when the frustules have been macerated in
acid, these portions of the valves appear as perforations, owing to the dis-
appearance of the cell-membrane."

The fnistules of the Diatomeaj are composed, as before stated, of two
usually more or less convex valves, enclosing a single cavity, which becomes
augmented by the growth of a thii-d segment interposed between them, pro-
duced preparatoiy to the process of self-division. Meneghini asserts that

38

GENEHAl niSXOEY OP THE INFUSOEIA.

the silicious sliicld or lorica ia four-sided, and composed of four pieces or
valves. Although this appears to bo the true structure of some species, owing
to the ready separation of the connecting membrane into two portions, yet the
majority offer no countenance to the notion, the connecting membrane
forming a continuous oval or circular ring. In Triceratium, however, is an
example of an even more pseudo-multiple composition ; for its prismatic tri-
angular frustule breaks up into " two triangular plates or walls of silex
forming the ends, and into three oblong rectangular pieces or bands forming
the thi'ee sides, the latter usually dividing themselves into several elongated
paraUeliform pieces" {Brightwell, J. M. S. i. 248).

Again, in several genera, doubtfully arranged by Ehrenberg among the
sihcious Bacillaria, e.g. Dictyocha (XII. 62, 63) and Mesocena (XII. 71), the
individuals are represented as composed of several segments united together.
Each valve consists of a sihcious lamina superposed on an organic soft
lining (or primordial) membrane which immediately encloses the contents of
the cell. NageU speaks of a mucilaginous pellicle on the inside of the
organic layer as a sort of third tunic ; and Kiitzing likewise discovera a thin
stratum brought into view when recent frustules are dried, and particularly
after heating them to redness, in the shape of an opake bro^wnish stain, or
of brown lines or points, extending not unfrequently over a considerable
portion. To this supposed iudependent material its observer applied the
name ' cement,' imagining it to be the connecting matter of the valves and
of frustules when in union, and attributed its brown colour to the presence
of iron. This presumed layer of cement we can regard as nothing more than
the stain produced by the oxidation of the salts of iron in chemical imion
with the silica, as Prof. Erahkland has shown (p. 37). However, Meneghini
adopts the notion of this thii-d envelope or cement, inasmuch as he observes
it to be constant, without employing the means used by Kiitzing to display
it, not merely in the species enumerated by its discoverer, but in many
others, and possibly in all {R. S. 1853, p. 361) : — " For to me (continues the
same author) it appears to correspond with that fine membrane of the Ach-
nanthidia, which, according to Kiitzing's own observation, is always visible
whenever the two new individuals (into which every Diatom is resolved in
its multiplication by deduplication) begin to separate. The lines and points
supposed to belong to the subjacent shield belong very frequently to this kind
of covering." The analogy expressed in the quotation just given, between
the delicate stratimi — the ' cement ' of Kiitzing, and the secretion poured
out when self-division is proceeding, we cannot regard as correct ; for this
latter is a special and usually not persistent coating, in all probability exuded
through the fissures or pores uncovered by the silicious lamina, by the sub-
jacent organic membrane, and is Avithal dcsti'oyed by the heat generally
required to bring the ' cement ' into \'iow, whereas the presumed coat is
represented to be constant and also permanent both under the operation of
fire and of acids. However, the belief, in the existence of a vegetable mem-
brane outside the silicious epiderm gains ground ; for Mr. Shadbolt, in his
presidential address before the Microscopical Society, 1858 (T. M. S. 1858,
p. 72), states it as the result of hia researches, that the frustidc of Arach-
noicliscus and of other forms consists of a sillcioKS framework, over wliich is
stretched a species of membrane, whether silicious or not ho does not presume
to decide, but certainly pliant to a considerable extent, capable of being pai--
tiaUy roUcd up by mechanical agency -without brealdng, and elastic enough
to rotiu-n to its original position when the extraneous force is removed.
" Tlie stractui-e noticed by Mr. lloper iu Coscinodiscm lahjrinilms, and by
myself in the more common species C. radiaius and Triceratium favus, I

OF THE DIATOMEiE.

39

believe to bo of precisely the same natm-e, and I am much mistaken if we do
not find it in many other species of the Diatomacea."

In the accompanying part of the Jom-nal {J. M. S. 1858, p. 162), Prof.
Walker-Amott refers with approval to this opinion of Mr. Shadbolt, and
appends some most important remarks bearing on the presence or absence of
this membrane in the determination of species. He observes that " There
can be no doubt that these discs (i. e. of Arachnoidiscus) have a homy
vegetable outer covering, in addition to the silicious one, and that by too
long boUing in acid, as is necessary for guano, the marks are much obli-
terated or entirely removed. This, however, is not peculiar to the present
genus, but may be obsei-ved, more or less, in all Diatoms, although sometimes
the vegetable pellicle is very thin and may be removed by a few seconds'
immersion in boiling nitric acid. It is this circumstance which gives a quite
different appearance to the same species, according as the preparation is
made. Thus, in Actinocyclus the vegetable epidermis is eeUular, while the
sDicious part is striated like a Pleurosigma ; and when the vegetable part is
removed, we often find nodules or knobs along the margin (forming, then,
the genus Omphalopelta), not previously visible. Those who describe Diatoms
from slides are thus liable to commit great errors, and indeed no certainty can be
obtained, except by getting the recent or growing Diatom and examining it,
Ist, after being immersed for a short time in cold acid, or simply washed in
boiling water ; 2ndly, after being boiled in acid for about half a minute, or a
whole minute at most ; and 3rdly, after being boiled for a considerable time :
we shall then see that many of the supposed distinct species of authors are
the same, prepared in a different way. Of course, deposits or guanos can yield
little or no information, although, when once a species has been determined
by the way I have indicated, we may be able to refer forms occurring in
guano or deposits to it with tolerable certainty."

Mr. Brightwell, speaking of the lorica or silicious epiderm of Triceratiwm,
states that the valves are resolvable into " several distinct layers of silex,
dividing like the thin divisions of talc, and frequently found of such exquisite
delicacy as to be difficult of detection" M. S. i. 248). The silicious lamina
is generally looked upon as a production or secretion from the subjacent
organic membrane, the true ceU-waU. NageH {B. S. Reports, 1846, p. 220)
says, " it lies outside the membrane, and must be regarded, fr'om analogy
with aU other similar structures, as an extra- cellular substance excreted from
the ceU;" and, as MenegMni {op. cit. p. 360) adds, "in fact, anorganic mem-
brane ought to exist, for the silica could not become solid except by crystal-
lizing or depositing itself on some pre-existing substance." Prof. Smith
moreover states (A. K H. 1851) that, apart from analogy, he has direct evi-
dence of the independence of the silicious coat, having in his possession
numerous specimens of a Stauroneis (probably S. aspera, Kiitz.), in which the
valves, after slight maceration of the fnistules in acid, have, in part or whoUy,
become detached from the cell-membrane, leaving a scar on its walls bearing
the distinct impression of the nimierous and prominent valvular markings of
this beautiful species. The same observer adds that he has in some cases
noticed this organic membrane to contract around the coU-contents, upon the
death of the cell. Again, the application of hydi'ofluorie acid, proposed by
Prof. Bailey, to recent, and sometimes even to fossil shells, proves the same
fact, by leaving a distinct internal flexible cell-membrane retaining the
general form, after the dissolution of the silica by the acid. Fiu-ther su])port
if needed, is famished by the phenomena of cell- division, in which tlie Uning
membrane takes the initiative, and is followed by the doubling-in of the
external coat upon it.

40

GENEBAL HISTOEY OP THE UTFUSOBIA.

Nevertheless, although a silicious layer be artificially separable from the
underlying organic coat, the relation and union of the two are indeed
very intimate : and in the case of the apparently inorganic external lamina,
the silex must be presumed to be deposited in some form of connective tissue,
or, in other words, to permeate it. This opinion is advocated by Menegliini,
who adduces ia its support the circumstance of the silicious shield of Ach-
nanthidia being covered with "a very delicate dilatable membrane, itself
containing silica, as is proved by its sustaining unchanged the action of fire
and acids." This author goes on to suggest that "this permeation may
occur either in the wall of a simple cell, as is seen in the epidermal cells of
many plants, or within minute cells, as in various plants and animals."

The sxirface of Diatomaceous frustules is generally very beautifully sculp-
tured, and the markings assume the appearance of dots (puncta), stripes
(striae), ribs (costae), pinnules (pinnse) ; of furrows and fine lines ; of longi-
tudinal, transverse and radiating bands ; of canals (canaliculi), and of cells
or areolae, whilst each and aU these varieties present striking modifications
in number, relative distribution, and in degree of development. Again, two
or more sorts of markings may occur together ia the same individual ; and
lastly, the entire frustule may be covered, or certain spots may be left
unoccupied by them, in the form of bands, circular spaces, and the like.

The preceding account of the coverings of a Diatomaceous frustule make it
clear that the apparent superficial markings, although chiefly due to the
sculpturing of the silicious epiderm and to its internal involutions, are still
in some instances and in a certain degree dependent on the overlying firm
vegetable membrane which Mr. Shadbolt and others have shown to exist.

But, apart fr'om this, modem research shows that puncta, lines, costae and
other markings are not the same in nature in aU examples presenting them ;
that in one case a circular point is a depression, in another an elevation, and
in a third a mere thickening or condensation of silicious material. So
of lines or costae: some are markings of the surface, and either furrows,
ridges or thickenings, or actual canals, whilst others ai'e the result of invo-
lutions or foldings of the internal coat or incomplete septa.

Again, the fine lines or striae of many frustules are resolvable into rows of
minute dots, as in Navicula and Pleurosigma. When the striae are more
distinctly composed of rows of dots or puncta, they are described as monili-
form ; examples occur in Oomphonema and Poclosphenia.

Speaking of striae, Unes, and puncta generally, Prof. Smith {op. cit. i.
p. xvii) confesses his belief that they are all " modifications in the arrangement
of the silex of the valve, arising fi-om the mode of development peciiliar in each
case to the membrane with which the silex is combined and, referiing to
the areolar or ceUular-looking valves of Triceratium and of Isthmia especially,
and to the recognized growth of organized beings by cells, he arrives at the
conviction that " the valvular markings in every case aiise from modifications
of cellular tissue," which forms, so to speak, the matrix of the silicious
epiderm. " No difficulty (he adds) presents itself to the supposition that the
moniliform striae of Epithemia, Navicula, and others, the circular markings of
Coscimdiseiis eccentricus, and the iiTegular star-Uke structure of Enpodiscus
An/us, are all modifications of cellular tissue ; and even in the costae of P»i-
nuiaria, and the unresolvable stiiaj of Eupodisciis scidpUis and others, it is
not difficult to conceive wo have confluent cells whose union gives rise to the
appearance of lines or bands."

Great diff"erence has existed, and even yet exists, in the interpretation of
the exact natiu'o of many superficial markings. Some circular dots or pimcta
ai'e held by certain observers to be pits, by others holes, and by others to be

OP THE DIATOMEiE.

41

elevations. So of stripes, costee, and pinnules: to some, such markings in
special instances are ridges ; to others, furrows or fissures ; to others, ele-
vations ; and to others again, canals. The ai'dent microscopical research ot
this period is daily diminishing the number of these enigmas, and intro-
ducing cei-tainty in place of doubt and vague conjecture. To Ehrenberg s
apprehension, many puncta were real pores, and many striae or costse real
fissures ; the former of these were supposed to give exit to a few or to multi-
tudmous imaginary 'pedal organs' for locomotion, the latter to serve for the
passage of ova, and generally to bring the presumed internal animal organiza-
tion into immediate relation with the external medium around it.

Perhaps the discussion respecting the nature of apparent pores has been
most animated in the case of the genera Navicula and Pinnularia, which
present a large rounded spot at each extremity of the frustule and a central
space known as the umbilicus, with a tubular or canal-like band connecting
them together (XII. 15, 21, 46 ; XVI. 1). From the unabilicus, Ehi-enberg
believed a single locomotive organ to proceed — an undivided sole-like foot,
similar to the locomotive organ of snails, whilst he represented the terminal
points to be orifices for the purposes of nutrition (IX. 134). Although
denying the oflS.ces assigned them by the Berlin micrographer, Kiitzing coin-
cided with him in the belief of their being actual pores, and supposed that
they give exit to a gelatinous substance, such as is actually found sur-
rounding some Naviculce, and becomes a prominent character m the tribe of
Diatomeae represented by ScMzonema. Schleiden {Principles of Botany, by
Lankester, p. 594) speaks of the longitudinal band as a cleft, and of the
median and terminal spots as circular enlargements or thickened spots of
silicious matter. He moreover appends an enlarged lateral view of a Pin-
nularia (XVI. 2, 3, 4, 5), to prove that the seeming central orifice is simply
a depression. This explanation of their nature coincides in the main with
that given by Prof. Smith, who asserts that these markings are due to a lon-
gitudinal band of condensed and more solid silex, widened into small expan-
sions at the centre and extremities, or at the extremities only, and probably
designed to give firmness to the valve. " That these expansions (he adds)
are not perforations in the valve, as alleged by Ehrenberg, and acquiesced in
by Kiitzing, might be shown in various ways. The internal contents of the
frustule never escape at such points when the frustule is subjected to pressure,
but invariably at the suture or the extremities .... nor does the valve when
fractured show any disposition to break at the expansions of the central line,
as would necessarily be the case were such points perforations, and not
nodules. Moreover, the central band of silex is itself frequently traversed by
a narrow line which arises from the confluence of a series of cells, which
thus form a minute tube ; but this tube invariably ends in a rounded extre-
mity at the central and terminal nodules, and does not pass into an opening

or_ aperture in the valve The bending down of this tube and the

thickening downwards of the silex at the nodules give the semblance of
depressions to the surface of the valve at such places. But I am disposed to
think that this is merely an optical appeai-ance, and at all events assured
that no perforation exists at such points, and that the terms applied to these
nodules by different authors, implying that they are openings or ostiola, are
altogether inadmissible."

Examples of nodules at the centre and extremities are found in the
genera Amphiprora, Pinnularia, Navicula (XII. 5, 6), and Oomphonema (XII.
15, 21, 46). In Stauroneis the central nodule is developed transversely, so
as to form a smooth transverse band or "stauros" fi-eo from marldngs
(XII. 7, 8, 18). A median longitudinal ridge or band exists in Navicula,

42

GENERAL HI8T0HY OF THE INFCSOHIA,

Stauroneis, &c., whilst in AmxMphura (XIII. 1, 2) two ridges are noticeable,
but whether these are of the same nature structurally is uncertain. In
Borypliora, again, there is a median band, but no nodules distinguishable ; and
in Eunotia and Himantidivm the terminal nodules would seem exceptional in
character, being due, as Prof. Smith supposes, " to an inflection of the valves
at the point of junction." The rounded space in the centre of the discoid
valves of Actinocyclus (XI. 132) and Arachnoicliscus (XV, 18-21;, which is
devoid of areola, is designated by him a pseudo-nodule, in order, we presume,
to contrast a mere bare space with the like smooth but condensed and thick-
ened spots described as nodules.

In this record of opinions, those of Siebold and Nageli (J. M.S. i. 196)
should not be omitted : — " Precisely at the spots (says the former vmter) at
which Ehrenberg and others suppose they have seen six openings {i. e. three
on each valve) in Navicula, the silicious cell-membrane is thickened, and con-
sequently forms so many rounded eminences which project internally." These
views thus far tally with those of Prof. Smith and others ; however, a few
lines further on in his essay, Siebold expresses the belief that the lines
limning along the middle of the surfaces fi'om one thickening to another
" are to be referred to a suture, fissure, or rather gap, in which no silicious
matter is deposited, so that in these places the delicate primordial membrane
which lines the silicious shield can be brought into close relation with the
external world, I come to this conclusion from the cii'cumstance that it is
exactly at these four sutures or fissures that the water surrounding the
Navicula is set in motion." (See p. 50.)

Upon the whole question of the actual nature of the mai-kings on the
surface of the silicious frustules, we are happy to add a paper published by
Prof. Bailey {8ill. Jowrn. ii. 349), which appears to afford a satisfactory
elucidation. We present it entire, with the practical notes on manipulation,
so that our readers may imdertake a critical examination for themselves : —

" I now offer proof which removes all doubt, and shows that these markings
are neither apertures nor depressions, but are in reality the thickest parts of
the shell. If the shells are placed in dilute hydrofluoric acid and watched
by the aid of the microscope as they gradually dissolve, the thinnest parts of
course dissolve first, and apertures, if any exist, should become enlarged.
Now the very parts which have been called orifices by some, and depressions
by others, are the last of aU to disappear as the shell is dissolved. This mode
of observation, besides establishing the fact that these are the thickest parts
of the shell, reveal many interesting particulars of structure. Thus, in
the large Pinnularia, it may be seen, with even a low power, that the two
parallel bands (separated by a canal) which reach fi-om the central knob to
the terminal ones, and which appear smooth before the application of acid,
become distinctly striated after their surface is dissolved oft', as does also the
central spot itself, showing that striaa which existed in the yoimg shell are
covered up and nearly obliterated4by subsequent deposits. In Siaiirosira the
cross-band and the two longitudinal bands ai-e tho last to dissolve, and these
last bands, as in most Diatomacea, appeal- separated by what is cither a canal
or thin portions of the shell. In GrammatojpJwra the undulating lines are
internal plates, which are the last to dissolve. In Heliopelta, Actlnoptychus,
&c., the polygonal central spot is the last to disappear. In Isihmia, the spots
on the surface, Avhich at first appear like granular projections, arc in reality
thin portions of the shell, and imdor the action of the acid they soon become
holes, Tho acid also proves that tlie larger spots at the transverse bands are
a scries of large arcuate holes in the silicious shell, and the piers of this
series of arches remain some time after tho rest of tho sheU has vanished.

OF THE DIATOMEJE.

43

A few dii-ections on the mode of manipulation may be useful. As tho fumes
of the hydi-olluoric acid, if they reach the lenses, would greatly injiu-e them,
it is advisable to protect the front face of the objectives by temporarily con-
necting to them a thin plate of mica by Canada balsam, as mica resists the
action of hydrofluoric acid much better than glass. I prepare the cell in
which the solution is to take place by cementing a plate of mica to a glass
slide, and then cover all its smface, except a central small disc, with wax.
On this disc, which forms a cell, the shells are put with a dish of water, and
after adding a di-op or two of acid by means of a dropping-rod of silver or
platinum, the cell is covered with another plate of mica, and the slide is then
placed under the microscope."

Some markings of the surface, apparent only as striae under inferior magni-
fying powers, are in several genera resolvable, as before noticed (p. 40), into
rows of rounded dots, e. g. in Pleurosigma ; and ia consequence such specimens
have been employed to try the relative powers of microscopes, and are spoken
of as ' test objects.' But the powers of microscopes have been more severely
tested of late years, by the endeavour to ascertain whether such dots are eleva-
tions or depressions of the surface, and, as might be expected, the dissension
on this matter has equalled that respecting the central band and umbilicus.

Dr. J. W. Griffith is in favoiir of their being depressions {Proc. Roy. Soc.
1855). He argues that, as the markings " are evidently depressions in the
genera and species with coarsely marked valves (Isthmia, &c.), we should
expect from analogy that the same would apply to those with finer markings
(those viz. in dispute, Gyrosigma, Pleurosigma, and others). And this view
receives farther support from the fact that under varied methods of lUirmina-
tion corresponding appearances are presented by the markings when viewed
by the microscope — from those which are very large, as ia Isthmia, through
those of moderate and small size, as ia the species of Coscinodiscus, down to
those ia which they are extremely minute, for instance in Oyrosigma,
&c. The angular (triangular or quadrangular) appearance assumed by the
marldngs arises fi'om the light transmitted thi'ough the valves beiag un-
equally oblique; this may be readily shown in the more coarsely marked
valves {Isthmia, Goscinoclisciis), which present the true structural appearance
when the light is reflected by the mirror ia its ordinaiy position, and the
spurious angular appearance when the light is rendered oblique by moving
the mirror to one side." Another statement is put forward by the same
author ia the Micrographic Dictionary (Introduction, p. xxxiii) ia support
of his opioion, viz. " that the liae of fracture of the broken valves passes
through the rows of dots on the dark lines corresponding to them, showing
that thoy are thinner and weaker than the rest of the substance. Had these dots
represented elevations, the valves would have been stronger at these poiuts."

The more prevalent opinion, however, is, that these delicate dots ia rows
are elevations of the suiface. Mr. G. Himt {J. M. S. 1855, pp. 174-175)
adduces an observation to demonstrate this fact. He found that on a speci-
men of Pleurosigma being moistened, the markings Avere ahnost entirely
obscured, but that on the apphcation of a gentle heat " the moistui-o slowly
retreated, leaviag patches of the shell diy, and Avith tho markings as dis-
tinct as before." On observing these diy parts of tho shell, they were seen to
be uniformly bounded by straight Mncs, parallel to the two directions of least
distance of the dots. " Now (contiaues Mr. Hunt), on tho supposition of
these httle dots being elevations, the phenomenon appears to me easily ex
plicable on the principle of capiUary attraction. We can readily conceive
the moisture clinging from one dot to another ; and it would always have a
tendency to arrange itself m lines parallel to the directions of least distance

44

GENEBAL HISTORY OF TIIE IlfFUSOlUA.

I am, however, quite at a loss to imagine how the same principle would apply
on the hypothesis that the dots are depressions, nor do I see upon what
piinciple the phenomenon is expUcable."

A dii-ect demonstration that the markings in general of the Diatomeaj are
elevations is attempted by Mr. Wenham, whose knowledge of optics and prac-
tical skill in mechanical manipulation are not exceeded by any microscopist
of the present day {J. M. S. 1855, pp. 244-245). To quote his words— "A
careful study of the coarser varieties will distinctly prove that the markings
are raised ribs or prominences on the surfaces, in some instances on one side
of the shell only, as seen in the Campylodiscus spiralis and others. Though
the microscope proves this fact satisfactorily in the large species, it fails to do so
in the most difficult specimens, chiefly on account of the above-named deceptive
appearances, arising from the irregular refraction and reflection of hght. It
occurred to me that it might be possible to obtain a perfect cast or impression
of the structure ; and by vicAving this as an opake object, the error, if arising
from refraction, would be avoided, and a discovery might be the reward of the
expeiiment. I have succeeded in effecting this by means of the electrotype
process, which for many reasons is to be preferred, as it does not distort the
object, and is so minutely faithful that even the mere trace of organic matter,
left by a slight finger-mark, is perfectly copied. The method I have adopted
is this : — Procure a small plate of metal highly polished (a piece of daguerreo-
type plate answers extremely well), and, after gently heating it, rub a piece
of bees-wax over the surface ; while this is stiU melted wipe it neai-ly ail off
again with a piece of rag, so as to allow a very thin film to remain ; when
the plate is cold, arrange the Diatomacea or other objects, previously moist-
ened, upon the waxed surface, heat the plate again to at least 212°, in order
to cement the objects on it. The wax serves a twofold purpose : first, its
interposition prevents the possibility of a chemical union of the metallic
deposit with the plate ; and secondly, the object is securely held thereto by
its agency. The objects are now ready to receive a coating of copper. If
the battery is in good working order, three or four hours will give a film
sufficiently strong to bear removal ; when this is stripped off, if the process
has been properly managed, the objects will be seen imbedded in its surface ;
whether they are silicious or organic, they may be entirely dissolved out by
boiling the cast in a test tube with a strong solution of caustic potash, and
afterwards washing with distilled water ; the copper film may then be mounted
in Canada balsam. By these means I have obtained distinct impressions of
the markings of some of the more difficult Diatomacea, such as N. {Pleuro-
sigma) Balticum, P. Hippocampus, &e., leaving no doubt of their prominent
nature." (See Microscopic Cabinet, ed. 1832, chap. xvi. and xviii.)

Besides the superficial markings explicable on the supposition of an invest-
ing areolar membrane, and the sculptuiing of the silicious epiderm, there
are others, dependent on structural modifications of the sQicious laminEe of
the valves, and on inflections of these internally. Among the former are
many of the stronger-marked costae and pinnules of Ehi-enberg ; and among
the latter are to be reckoned the imperfect partitions ('septa') seen in
several genera, and those peculiar processes of the internal siirface which
Kiitzing called ' vittce.' Schleiden described ' pinnules ' to be clefts or fissures.
" In these spots (says he), the shield consists of two leaves lyiug one over the
other ; these leaves ai-e penetrated by the small clefts, which, whcii both
the lameUse touch each other, are somewhat broader, which explains the
varying breadth of the clefts according to the alteration of the foci. Frag-
ments in which this structure is clearly represented may be frequently obtained
by crushing the shield," (XVI. 5, G.)

OP THE DIATOlfEJE,

45

Prof. Smith likewise describes inter-lamellar channels, under the name of
' canalicuU; "hoUowed out between the silicious epiderm and internal cell-
membrane, and apparently formed by waved flexures of the epidermal enve-
lope They are very conspicuous in Epithemia longicornis, and foi-m

distinctive characters in the genera Surirella and Oampylodiscus." This
observer also regards them " as minute canals which convey the nutri-
mental fluid to the surface of the internal membrane," this fluid entering
them from without through pores or fissures existing along the line of suture
of the valves (p. 50). That these canals are not modifications of the cellular
structure of the silicious epiderm is shoTVTi by the circumstance of the strias
passing uninterraptedly over the entire surface of the valves in some Epithemice.

The costiB of Campylodisms equally appear to be canaHculi, and are dis-
posed in a radiate manner. In Surirella and Tryhlionella these canals are
usually parallel, whUst in Mastogloia they take the form of loculi.

Kiitztng assigned a special structxu-e and purpose to the markings he
called ' vittce,' and used them in forming a subsection of Diatomese he called
Vittatce. The Kev. Prof. Smith remarks that to him these markings do not
seem special organs, but modifications in the outline of the valve, which is
inflected. In Grammatophora (XI. 48, 49, 52, 53) these inflections con-
stitute a leading feature of the genus, and, from their resemblance to written
characters, have suggested its name. In this instance they foim incomplete
septa.

The terms striee and costse or pinnules are not synonymous. Striae are
the finer lines of shght breadth, which may look like narrow grooves or
ridges, whilst costae or pinnules are the wider markings, having an evident
double contoui', and the appearance of fissures or canals. The fineness of
some striae is such that, as before noted, they may be readily overlooked ;
however, their presence, when not positively demonstrable, may be assumed
by the colours displayed on focusing diied specimens. An analogous fact
presents itself in the case of mother-of-pearl, which owes its vaiying and
beautiful colours to the existence of fine lines covering its surface. The
colour varies in different species, and is due to the refraction of the rays of
light passing through the silicious epiderm ; its shades depend on the dii'ection
of the striae and on their distance from each other ; its aid may therefore be
advantageously evoked in the determination of species.

Striae generally seem to be produced by the confluence of minute rounded
points or beads — in other words, are commonly momliform, and often extend,
as products of an investing areolar tissue, over the entire surface of the valves,
imhke those costae which originate in structural pecxiliarities of the silicious
plates. Eows of pvmcta occur in Nitzschia, and monUiform strias in Navicida,
Pleurosigma, Gomphonema, and Podosplienia. To the confluence of the
superflcial cells, Mr. Smith attributes the production of the costffi of Pinnu-
laria, whilst those of Achnanthes he looks upon as thickenings on the under
surface of the silicious valves, and generally similar to those of Isthmia, wliich
line the valves and anastomose on their under surface ; lastly, the striaj of
Bhabdonema are constituted of series of oblong cells,

_ The value of the external markings of Diatomeac, in a systematic point of
view, has been much discussed. Ehrenberg assumed the number of striaj
or of costa3 or pinnules to be constant in the same space in each species, and
accordingly gives the number of stria:; counted within a given fraction' of a
line. A great multitude of species was the consequence of this plan • never-
theless the mere fact of number of striae within a given space cannot be esteemed
a valid specific character by itself; for it seems quite clear that the relative
closeness of stnse, their number Mathin the -001 of on inch, varies according

4G

GENEBAL niSTOBT OP TUE INFUSOHIA.

to tlio ago and to the size of tho valves, and both size and figure are consi-
derably affected by cii-cumstances of growth, of locaUty, and the like. A
writer in the Microscopical Journal (1855, p. 307) suggests that the number '<
of stria) on tho entire valve may supply a more stable character ; yet even
on this point we axe wanting in direct observation to show that this number
may not be affected by accidental circumstances.

Although " the relative distance of the strias and their greater or less dis-
tinctness " be accounted by Prof. Smith of specific importance, yet he is
obliged to admit {J. M. 8. 1853, p. 133) that it is by no means certain that
these features may not to a sHght extent be modified by locaUties and age,
and is disposed to beheve that they are certain gnaides only when we have
made allowance for these conditions, and that while they are constant in
fnistules originally from the same embryo, they may slightly vary in those
which owe their birth to different embryonic cells. It is also worthy of
note that, in certain instances, e. g. in Odontidium hyemalis, Epithemia Arcus,
&c., the costse are frequently more numerous on one valve than on the other.

Other illustrations of the variation in the number and in the distinctness
of strife in the same species are to be found in the late lamented Dr. Gregory's
valuable papers {T. M. S. 1855, p. 10). The relative position of striae — ^if
parallel or radiate, their moniliform or confluent character, their equal and
general diffusion over the entii'e surface, or their absence at parts, are other
circumstances available for the purposes of classification.

Besides striation, the other descriptions of superficial markings are resorted
to for specific and generic characters. Such are the presence or absence of
a median band, Avith central and terminal nodules, the existence of a trans-
verse band, the figure, relative position and aggregation of the areolae or ceUs
of the surface. The median and transverse bands have been employed by
all systematists, and would seem well suited to furnish characteristics by their
constancy. The same may be said of the pore-hke spots or nodules. Kiitzing
went so far as to make the presence or absence of a central nodule or um-
bilicus the turning-point in his grand division of the Diatomeae into um-
bilicated and non-umbilicated.

Lastly, speaking generally, the precaution intimated by Prof. "Walker- Amott
(p. 39), of having specimens, intended to be compai'ed together for the determi-
nation of specific forms, similarly prepared, must ever be bome in mind where
the superficial markings are referred to for characters; othei-wise an excessive
and erroneous multiphcation of species, and a deplorable confusion wiU result.

"We have already seen that the connecting membrane is not an essential
segment of a Diatomaceous frustule, but an after- development in connexion
with the process of self- division; yet, not-ndthstanding, it is so frequently
present, and in many examples its dimensions and cliaracters are so marked,
that it supplies an important element in specific and generic descriptions.

In the circulai' and discoid Diatomeae, it assumes the form of a continuous
ring (XI. 40, 42), but in many oblong and navicular fi-ustules it is itself
oblong or navicular, having a figure the reverse of the valves it is placed
between (XII. 17, 24, 31 ; XIII. 5, 6, 7). In these latter and in other
instances it is frequently separable into two portions, at the opposite extre-
mities of the frustules where the silex is absent ; and hence it is that the
shells of the Diatomea3 have been described by Meneghini and other writers
as composed of four segments.

In general, the proportion of silex in its constitution is loss than that in
the valves; and the existence of markings— of areolae, striae, and the Hkc—
is also much rarer. Where they do occur, they furnish useful particulars
in defining species and genera. The small dovelopmeut of the connectipg

OP THE DIATOMEiE.

47

membrane in Pleuwsigma is a remarkable featm-o of that genus, whilst in
Gomphonmna (XII. 28, 53), and other genera with cuneate (wedge-shaped)
frustiiles, the figaire is due to the greater development of this segment at one
end than af the other. In Amphiprora (XIII, 5, 6), Aclmanthes, Himanti-
dium (XII. 50, 52), and Melosira, the connecting membrane is striated, and
in. BiclcMphia (II. 48), Isthmia (X. 183), and Amphitetras (XI. 21, 22) is
cellulate or areolate.

In certain genera the connecting membrane takes on an extraordinary-
development, which greatly modifies the figure of the fi-ustules. Instead of
being hmited to the interspace between the opposed valves, it extends on
either side beyond the sutures (XII. 9), presents itself as a band of greater
or less width, and acquires an unusual persistence. Under this form it con-
stitutes the ' dngulum ' of descriptive writers, and is seen in Amphitetras,
BidcMpUa, Podosira, and Melosira. In the last, two genera, Prof.^ Smith
tells us, the persistence of this circular band is " eminently conspicuous,
retaioing the fi-ustides after self- division in a geminate union until the self-
dividing process is renewed."

Contents of FRtrsTTTLES. — Nuclem, supposed Digestive Sacs, JReproductive
Vesicles, Sfc. — The organic membrane of the frustules of Diatomese, strength-
ened externally by the sOicious plates, encloses within its cell-like cavity a
soft mucilaginous substance filled with numerous granules and globules, and
usually of a yeUow-brown or orange-brown colour, but at times of a
green hue, and technically known as the ' endoclirome,^ or in Eiitzing's
phraseology, the ' gonimic substance.' The granular matter is particu-
larly aggregated about the organic wall, leaving the central portion more
clear. In this clear central space is a transparent vesicle, representing the
nucleus of the cell, having the granules frequently collected around it in an
annular form. NageU states that the nucleus, enclosing a nucleolus, lies
sometimes free in the centre of the fhistular cavity, but at other times is
affixed at one spot to the waU., and therefore ' parietal.' He also describes
two sorts of nuclei, viz. primary and secondary, attributing to the former the
active part. Schleiden represents the nucleus to be primarily concerned in
the original formation of the cell, as weU as in its subsequent multi]jlication.
by self-division.

Among other elements of the endochrome are more or fewer rather
translucent globules, which Prof. Smith believes, like Kiitzing, to be secre-
tions of the cell, of a fatty or oily composition, and to be the source of the
peculiar odour emitted on burning the Diatomese. In support of this
view Kiitzing states that he has occasionally seen two coalesce, proving the
absence of proper waUs, and expresses his conviction that these corpuscles
are akin to the amylaceous secretions of the Desmidie83 and Confervte and the
starch-granules of the higher vegetables.

These globules are smaller than the nuclear space, and occupy a pretty
constant and definite position. " The number of these globules is frequently
four, often placed near the extremities, or more rarely clustered round the
central vesicle." Meneghini (op. cit. R. S. p. 364), alluding to these vesicles,
states them to vary in number, size, and disposition at diff'ercnt stages and
according to various conditions, oven under tho eye of the observer. '

These apparent oU-globules were caUod by Ehrenbcrg male sexual glands
or testes, whilst those other vesicles distributed within the mucilaginous
matter, often about the nucleus, were named stomachs. The latter idea he
based espcciaUy on a series of experiments to introduce colouiing matter
into the interior of tho frustules, in which he believed ho succeeded The
species mentioned ave Nnvieula gracilis, N. AmjMsbcenn, N. viridula. N fulva

48

GENERAL DISTOET OF THE INFUSOttlA.

N. Nitzschii, N. lanceolata, and N. capitata ; also Oomphonema truncatum,
Cocconema cistula, Arthrodesmus quadricavdatm, and Closterium acerosum.
The two last, however, are Desmidieaj. In the seven species of Navicula
enumerated, from 4 to 20 little stomach-sacs are said to have become fiUed
with the indigo employed as the colouring matter.

" This effect (as Meneghini remarks) could only be produced by keeping the
Diatomeae a long time in water laden with particles of indigo, and often re-
newed." Kiitzing deduced an opposite conclusion from these experiments,
viz. that they Avere solid corpuscles which, being seated near an opening,
exerted an especial attraction upon the colouring matter, Meyen argued,
so long since as 1839 (Jahresbericht d. Alcad. Berlin), against the supposed
stomach-sacs and the entrance of colouring matter within them. His
objections are thus expressed : — " On the one hand, I can see no stomach-sacs
in the Naviculce, and never observed in the living and moving Bacillaria the
colouring matter received at one extremity and carried towards the centre,
where these stomach-sacs should lie, whilst among the cUiated Infusoria
such observations are easy ; on the other hand, it is not uncommon, especially
in the larger species, to see the molecides of the colouring matter employed,
lie upon the middle of the broad ventral surface, looking as if actually within
the organism ; but if a glass plate be placed upon the specimen and then
carefully removed, the particles of colouring matter are taken away with it."
Even Ehrenberg admitted that the presumed stomach-sacs varied in number,
were quite irregular in their disposition in the interior, and not unfrequently
wanting altogether. This last circumstance, Kiitzing remarks, is opposed to
the belief in their digestive functions, since such important organs as stomachs
can never be supposed absent.

Although the existence of this fanciful polygastric apparatus in the
Diatomeae is scarcely worth controverting, yet we may add to the above
objections to it the fact that, in the hands of other experimenters, the
attempt to introduce colouring matter by any definite apertures into the
fmstules of this family has been unsuccessful.

The arrangement of the mucUaginous endochrome, or rather of its pro-
minent globules, vesicles, and granules, is sufficiently definite and constant
in the same species to afford useful characteristics. At one time these
molecules are diffused rather irregularly ; at another they are collected in a
rounded heap towards the centre, whilst at another they are disposed in
lines radiating from the nucleus, or formed in a layer upon the cell- wall, —
" at aU times " (adds Prof. Smith) " having one or several oily globules,
which occupy in different species different positions, but are constant in
number and position in the same species. The minute granules " (he con-
tinues, i. p. 20) " are generally accumulated in thin layers towards the internal
ceU-waUs : when the frustule is so turned that this layer of endochrome is
presented edgeways to the eye, the granules appear to be chiefly aggregated
into two plates applied to the opposite sides of the frustule ; and when self-
division is in progress and the cell-contents are divided into two portions,
such a separation or temporary aggregation must necessarily ensue ; but in
the simplest condition of the frustule the contents are diffused over the entire
surface of the ceU-waUs, precisely as may be seen in the coUs of many of the
larger Algse, or of some water-plants of a higher order, as in the leaves of
Hydrocharis Morsus-rance and others."

Schultze has recently represented {MUll. Archiv, 1858) a definite peculiar
disposition of the endochrome — of its mucilaginous and granular portions and
its- coloured corpuscles. In the more or less quadrate fnistulcs of DcniiceUa,
and in tlic circidar ones of Coscinodiscus, he describes the existence of a central

OF THTE DIAT0MEJ5.

49

dear vesicle, from which tliin, finely granular lines or threads extend and
intersect and branch in a reticulate manner, with a more or less distinct
radiation, the more fluid contents flowing between them. In the long cylin-
drical fnistules of Bhizosolenia, on the contrary, these granular mucilaginous
threads nm longitudinally. Within these threads the colouring, yellowish-
brown corpuscles, not circular, but, as Schultze says, iiTegularly multangular,
are disposed and retained in theu- position. Although these researches extend
to so few fonns, yet we are disposed to beheve that this disposition of the
elements of the endochrome will be found to be the rule. A reg-ular arrange-
ment is figui-ed in many drawings of the Diatomese by various observers ;
and where it does not appear it is most probably due to the want of attention
to its presence, — or to the excessive multiplication of the coloiiring corpuscles,
causiag them to appear spread beneath the envelopes as a pretty uniform
layer. A definite disposition of the chlorophyll-granules is common in plants,
particularly among the lower Algae, and owes its constancy to the presence
of the mucous and less fluid contents, which are condensed from the sur-
rounding fluid in. the form of filmy threads, and serve as a nidus to the colour-
ing particles. In this disposition, therefore, of the endochrome and its cor-
puscles we perceive a vegetable character, as contrasted with what is seen in
animal cells, and find in it an additional argument for the vegetable nature
of the Diatomese.

Notwithstanding that the endochrome is, by pretty general consent, ho-
mologous with that of recognized vegetable Algae, still it would seem to be
of a different chemical composition as well as of another colour. Kutzing,
indeed, rnsisted on the fact of the similarity of the endochrome to the
gonimic substance of Algae, from the circumstance that, by means of alcohol,
he was able to extract a colouiing matter similar to chlorophyll ; yet E,aben-
horst and others have remarked a difference in chemical nature. Prof. Smith
again, whilst admitting the imperfection of our knowledge on this point,
goes on to say that " the tincture of iodine causes the internal membrane to
contract upon the cell-contents, and converts these from the golden yellow
which they exhibit iu some species, into bright green, and that a weak
solution of sulphuric acid, while it effects the same contraction in the cell-
waU, gives to the contents, which have been previously treated vnth iodiae,
a dark-brown hue :• alcohol, on the other hand, as in the case of vegetable
cells ia general, dissolves the utricle and its contaiued endochrome, or at aU
events entirely removes their colour, and leaves their silicious epiderm in a
state of perfect transparency. It does not, however, dissolve the envelope in
which the frustules of the frondose forms are imbedded, nor the filamentous
stipes or gelatuious cushions to which other species are attached."

Meneghini (op. dt. B. S. p. 365) contends that the identity in nature of
the endochrome of Diatomeae and of Algae is not proved. " Its colour is dif-
ferent ; and it is differently coloured by chemical reagents. The resemblance
to it ia some instances, as in Melosira, in regard to conformation and suc-
cessive alterations, is only in appearance. In the endochrome of Alga) the
monogonimic substance begins by presenting a granular appearance ; then it
becomes distinctly granulated and changes into the polygonimic substance,
so minutely described by Kiitzing. But these changes do not occur in
the coloured substance of Diatomeae. If we insist on a parallel, wo can
OTdy compare it to the cryptogonimic substance of Biissoidia, Callitlmmnm,
Gnffithsra, and PolysipJmnia. It divides into two pkrts which successively
midergo ultenor division ; and in regard to these changes we may observe
that there is an essential distinction between those that occui- duiing life and
those that take place after death, the greater number happening in the latter

E

50

GENEEAL HISTOEY OF THE INFU80EIA.

condition The identity of this substance with endochrome is contradicted

by Kiitzing's own experiments, which prove it to be very rich in

nitrogen : it emits ammonia copiously when decomposed by heat ; and this
can only proceed from a substance abounding with it, which such a decom-
position compels it to yield up. Nor, on the contrary, do I beheve that there
is any weight in the argument from the solubility of its colouring principle
in alcohol ; for tliis is not apropei-ty peculiar to chlorophyll, or to any sub-
stance of vegetable origin."

The contents of the frustules are brought into relation with the surround-
ing mediiun through certain pores or fissures, which have been referred to as
existing here and there along the sutures between the opposed valves, or
otherwise between the valves and the interposed connecting membrane. The
existence of such openings in the sihcious envelope, and the consequent
exposure of the organic internal or primordial membrane in the situations
mentioned, have been demonstrated chiefly by the researches of Prof. Smith,
who applies to them the name of 'foramina.' They are thus described {op.
cit. i. p. 15) : — " Along the line of suture in disciform or circular frustules,
but more generally at the extremities of the valves only, when the Diatom is
of an oblong, linear, or elongated form, there exist perforations in the sUex
which permit the surrounding water to have access to the sui-face of the
internal cell-membrane. The fonnation of silex seems occasionally to be
ajTested in the neighboui-hood of these spots ; and the connecting membrane
is in consequence either wholly or partially interrupted at such places. Thus,
after the internal cell-membrane has been removed by acid, when it often
happens that the valves fall away from the connecting membrane, the latter
separates into two parts ; and the frustule has in consequence been described
as consisting of four plates. The interruptions in the silicious epiderm are
usually apparent as slight depressions at the extremities of the frustule ; and
the appearances they present have been denominated ' puncta' by Mr. Ralfs.
In some species these interruptions are more numerous, being found along
the entire line of suture, and are often connected with minute canals hollowed
out between the sOicious epiderm and the internal cell-membrane, and ap-
parently formed by waved flexures of the epidermal envelope." The latter
constitute the canaliculi heretofore spoken of (p. 45).

Siebold regarded the longitudinal bands having a double outline, and ex-
tending from the apparent dots or pores at either end of Naviculce to near the
centre, to be fissures ; but the account previously given proves this able man
to have been mistaken on this point. Like Prof. Smith, however, he con-
cluded that the internal membrane was imperforate, and that it served as
the medium for the exosmosis and endosmosis attending the function of
nutrition.

Movements of the Diatome-s; ; — their chaeacter and causes ; — Cilia ; —
Circulation of Contents ; — Respiration. — The peculiar movements noticed
in many Diatomeae have attracted the observation of all microscopists, and
have induced many, especially among the older observei-s, to receive it as
evidence of their animal natui-e ; but even those who agree on tliis point
are in no better accord among themselves respecting its cause than are those
who refer these beings to the vegetable Idngdom.

The power of movement is not confined to those only which are free, biit
also to concatenate and to some fixed forms, e. g. Sijnedra, wliich move on their
fixed extremity. There is considerable diversity both in the manner and ext€nt
of movement of diff'erent species ; but in none is it exliibitcd in an equal
degree to that seen in the spores of Algte. " The motion," says Prof. Smith,
" is of a peculiar kind, being generally a scries of jerks producing a rectilinear

OP THE DIATOMEiE.

51

movement in one direction, and a return upon nearly the same path, after a
few moments' pause, by another series of isochronal impulsions. The move-
ment is evidently of a mechanical nature, produced by the operation of a force
not depending upon the volition of the living organisms : an obstacle in the
path is not avoided, but pushed aside ; or, if it be sufficient to avert the
onwai-d course of the frustule, the latter is detained for a time equal to that
which it vrould have occupied in its forward progression, and then retires
from the impediment as if it had accomplished its fuU course. There is cer-
tainly no character of animahty in the movement ; and the observer, familiar
with the phenomena of life in the earlier stages of vegetable existence, is
constrained to see a counterpart in the involxmtary motions of the filaments
of the Oscillatoriete, or of the gemmiparous spores of the Puci and Con-
fervae."

This same view was taken by Morren in 1839 (op. cit.), who says — " The
movement of the Bacillaiia, however free it may be, is by no means so free
and active as that of the spores of Algse, which are plants, or, at least, parts
of plants ; and the motion is no positive ground for the belief in their ani-
mality."

The cause of the motion of the Diatomese has hitherto not been satisfacto-
rily determined. To the hypothesis of a snail-Hke expanding foot projecting
from the central pore or umbilicus, advanced by Ehrenberg, we have already
alluded (p. 41); and since no one original observer, in spite of the best-directed
efforts, has been able to detect the remotest evidence of such an organ, and
as all evidence goes to show that no actual perforations exist at the point
indicated for its extrusion, it would be useless to raise any argument upon it.
This distinguished naturalist subsequently satisfied himself of the presence
of other locomotive organs in a Navicula {Surirella gemma, XII. 3, 4), which
he has thus described : — " Instead of a snail-like expanding foot, long delicate
threads projected, where the ribs or transverse markings of the shell joined
the ribless lateral portions, and which the creature volimtarily drew in or
extended. An animalcule ^th of a line long had 24 for every two plates,
or ninety-six in all ; and anteriorly, at its broad frontal poi-tion, four were
visible. "Whether these organs were supernumerary, and existed along with
cirrhi, &c., and with the flat snail-Hke foot which the rest of the Naviculce
possess, could not be determined. Longitudinal clefts at the broad side of the
shell were not present ; but as many as 96 lateral openings for the exit of the
cirrhi were perfectly distinct." These ciliary processes were further stated
to be actively vibratile, and to be retracted or extended at short periods.

Prof. Smith has remarked on this appearance, that the presence of haii-s
apparently on aU parts of the frustule may often be detected, and that he has
noticed them on nearly every occasion on which he has gathered this species,
but in no case has he been able to perceive any motion in such hairs ; and he
therefore concludes that they are merely a parasitic gi-owth, such as the
mycelium of some Algae. He has also seen similar appendages to other Dia-
tomese, but in every case devoid of motion.

The notion of exsertile and retractile feet has been renewed by M, Focke
{Comptes Bendits, 1855, p. 167), who attributes the movements of Navicula to
such organs of a temporary kind, which he says pass through openino-s he
has detected on the sides of the lorica. "
_ NageU offered the following, and, to Siebold's mind, satisfactoiy, explana-
tion of the forward and backward movement, as well of many Desmidiece
as of Diatomeae {J. M. S. 1853, p. 195). " The ceUs," he wiites, " have no
special organs for these movements. But as in consequence of their nutri-
tive processes they both take in and give out fluid matters, the ceUs neces-

E 2

62

QENEKAL HISTORY OP THE INFUSOHTA.

sarily move when the attraction and the emission of the fluids is mieqnally
distributed on parts of the surface, and is so active as to overcome the
resistance of the water. This motion, consequently, is observed more particu-
larly in those cells which, in consequence of their taper form, easily pass
through the water ; these cells, moreover, move only in the direction of their
long axis. If one half of a spindle-shaped or ellipsoidal cell chiefly or en-
tirely admits material, the other haK, on the contrary, giving it out, the cell
moves towards the side where the admission takes place. But as in these
cells both halves are physiologically and morphologically exactly aKke, so it
is that it is first the one and then the other half which admits or emits, and
consequently the cell moves sometimes in one, at other times in the opposite
direction."

In our apprehension, this mechanical interpretation of the phenomenon is
not sufiicient ; the alternate reception and discharge of fluid matters by each
opposite half requires an effort of imagination, to conceive, unwarranted by
analogy. We shall, however, presently see that Prof. Smith gives the pre-
ference to this supposition, amid the many conflicting fancies of authors and
the obscurity of the question.

Encouraged by apparent success in discovering cUia on the fi'onds of Des-
midieae, Mr. Jabez Hogg searched for them on Diatomese, and teUs us {J. M. S.

1855, p. 235) that he has repeatedly satisfied himself that their motive power
is derived from cilia arranged aroimd openings at either end, — ^in some also
around the central openings, which, with, those cilia at the ends, act as
paddles or propellers. He, moreover, states his impression that the frustules
have a degree of volition sufficient " to move along and to steer their course ;
for intervals of rest and motion are most clearly to be distinguished." To
this belief in cUia on the fiiistules of Diatoms, Mr. Wenham is as determined
an opponent as he is to the like hypothesis respecting the Desmidiese (J". M. S.

1856, p. 159), and he offers the following speculations on the cause of the
movements : — " If caused by the action of cilia, such, extremely rapid impidses
would be required to propel the comparatively large body tlu'ough the water,
that suiTOimding particles would be jerked away far and wide ; a similar
effect would be observed if the propiilsion were caused by the reaction of a jet
of water, which, according to known laws of hydi-odynamics, miist neces-
sarily be ejected with a rapidity sufficient to indicate the existence of the
cun-ent a long distance astem. I consider that there is no ground for
assuming the motions of the Diatomacese to be due to either of these causes.
They are urged forward through a mass of sediment without displacing any
other particles than those they immediately come in contact with, and quietiy
thrust aside heavy obstacles directly in their- way, with a slow but decided
mechanical power, apparently only to be obtained from an abutment against
a sohd body. In studying the motions of the Diatomea9, I have frequentiy
seen one get into a position such as to become either supported or jammed
endways between two obstacles. In this case, particles in contact -\vith the
sides are carried up and down from the extreme ends with a jerking move-
ment and a strange tendency to adherence, the Diatom seeming imwiUing
to part with the captured particle. Under these circumstances I have dis-
tinctly perceived the undulating movement of an exterior membrane ; whether
this envelopes the whole surface of the silicious valves I am not able to
determine, nor do I know if the existence of such a membrane has yet been
recognized. The movement that I refer to occupied the place at the junction
of the two valves, and is caused by the imdulation of what is known as the
'connecting membrane.' This will account for the progressive motion of
the Diatome£e, which is performed in a manner analogous to that of the

OF THE BIATOMEiE.

53

Gasteropoda. The primaiy cause, however, is different, and not due to any
property of animal vitality, but arises, in my opinion, merely from the effects
of vegetable circulation. I have observed several corpuscles of uniform size
travel to and fro apparently withia the membrane, which is thus raised in
waves by their passage." Mr. Wenham follows up this explanation by a
conjecture with respect to the rarer movements of the Desmidiese. "As
there ai-e in these," he writes, " no indications of either external orifices or
cUia, may not their locomotion be effected by the ciirrents of protoplasm
forcing their way between the primordial utiicle and outer tunic, which wiU
thus be raised in progressive waves if the investment happens to be in a
suitably elastic condition." (See p. 5.)

The undulating movement of an exterior membrane thus indicated by Mr.
Wenham, over the sm-face of Diatomaceous fi-ustules, is doubtless identical
with the ciirrent demonstrated by Siebold by means of indigo {J. M. S.
i. pp. 196, 197). The latter states that the particles of this colouring matter
which come in contact with the living Naviculce are set iato a quivering
motion, although previously quite motionless ; but this happens only along
the lines of the four sutm-es, the particles adherent to other parts of the shield
remaining motionless. " The indigo particles, which are propelled from the
terminal towards the two central eminences, are never observed to pass
beyond the latter : at this point there is always a quiet space, from which
the particles of indigo are again repelled in an inverse direction towards the
extremities. This proves that the linear sutures, as may in fact be seen,
do not extend over the central eminences of the shield. The current at these
clefts is occasionally so strong, that proportionally large bodies are set in
motion by it." The sutures and clefts alluded to by Siebold, it should be
imderstood, are not the sutiures between the valves and connecting membrane,
but the evident lines extending between the apparent pores on the valves,
and which, to his apprehension, are actual fissures in the silicious envelope,
by which " the delicate primordial membrane which lines the silicious shield
can be brought into close relation with the external world." This belief in
the presence of such fissures on the valves we have previously examined and
shown to be unfounded. (See p. 41.)

Prof. Smith has the following remarks on this debateable point of the
cause of the motions of Diatomeae {op. cit. vol. i. p. xxLii) : — " Of the cause
of these movements, I fear I can give but a very imperfect account. It
appears certain that they do not arise fr-om any external organs of motion.
The more accurate instruments now in the hands of the observer have enabled
him confidently to affirm that all statements resting upon the revelations of
more imperfect object-glasses, which have assigned motile cUia, or feet, to
the Diatomaceous frustiile, have been founded upon illusion and mistake.
Among the hundreds of species which I have examined in every stage of
growth and phase of movement, aided by glasses wMch have never been
surpassed for clearness and definition, I have never been able to detect any
semblance of a motile organ; nor have I, by colouring the fluid with
carmine or indigo, been able to detect, in the coloured particles surrounding
the Diatom, those rotatory movements which indicate, ui the various species
of true infusorial animalcules, the presence of cilia. I am constrained to
believe that the movements of the Diatomaceee arc owing to forces operating
within the frustule, and are probably connected with the endosmotic and
exosmotic action of the ceU. The fluids which are coucomed in these
actions_ must enter and be emitted through the minute foramina at the
extremities of the silicious valves ; and it may easily be conceived that an
exceedingly small quantity of water expelled through these minute apcr-

54

GENERAL HI8T0EY OF TEE rNFUSOBIA.

tiires would be sufficient to produce movements in bodies of so little specific
gravity.

" If the motion be produced by the exosmose taking place alternately at one
and the other extremity, while endosmose is proceeding at the other, an
alternating movement would be the result in frustules of a linear form, —
while in others of an elliptical or orbicular outline, in wliich foramina exist
along the entire line of suture, the movements, if any, must be irregular, or
slowly lateral.

" Such is precisely the case. The backward and forward movements of
the Naviculece have been already described ; in Surirella and Campylodiscm
the motion never proceeds farther than a languid roU from one side to the
other ; and in Gomphonema, in which a foramen, fulfilling the nutritive office,
is found at the larger extremity only, the movement is a hardly perceptible
advance in intermitted jerks in the direction of the narrow end. The subject
is, however, one involved in much obscurity, and is probably destined to
remain, for some time to come, among the mysteries of Nature, which baffle
while they excite inquiry."

The last clause of this quotation expresses the unsatisfactory state of the
question; yet the foregoing examination will, we think, leave only three
hypotheses deserving further inquiry : viz., 1. the existence of cilia, or, 2. of
an undiUating membrane ; and 3. the operation of endosmose and exosmose,
as a mechanical cause. To our apprehension, the presence of cilia, perhaps
ranged only along the sutural lines, has not been completely disproved ; and,
on the other hand, considered as locomotive organs, cilia have the great
advantage of analogy over the presumed undulatory membrane. Do not,
indeed, the experiments vpith indigo, recounted by Siebold, suggest cilia to
be the active agents of the movements recorded ?

The rate of motion of the Diatomeae is exceedingly languid and slow ;
sometimes it amounts to no more than an oscillating movement, with httle
or no change of place ; and at anothei-, the back-g^ard and forward movements
are so nearly equal, that the frustule makes no appreciable advance. Prof.
Smith has measured the rate of motion of some species, and remarks that,
however vivacious and rapid they may at first sight seem, yet, when con-
sidered with reference to the high magnifying powers employed, and the
consequent amplification of their movements, they are very slow. " I have
noted the movements of several species with the aid of an eye-piece micro-
meter and a seconds watch, and found that one of the most rapid, viz. Bacil-
laria paradoxa, moved over -g^th of an inch in a second ; Pinnularia radiosa,
one of the slowest, over -pJ^th of an inch in the same time ; and that the
same period was occupied by Pinnularia ohlonga in traversing ■jTjVo'tli of an
inch, Nitzschia linearis ^ ^th of an inch, and Pleurosigma strigosum -gxiro*^
of an inch. Or, expressing the spaces and times by other units, we find that
the most active requii-ed somewhat more than thi-ee minutes to accomplish
movements whose sum would make one inch, and the slowest nearly an horn-
to perform the same feat."

■ Before quitting the subject of the movements of the Diatomeae, we would
briefly advert to the pecuiiar motion of some species, especially of Bacillaria
paradoxa. The movements of this organism, as the specific name impHes,
are paradoxical, or veiy strange in character. Mr. Thwaites essayed to
describe what indeed can be rightly apprehended only by personal ob-
servation, in the following words (Proc. of Linn. Soc. i. p. 311): — "When
the filaments have been detached from the plants to wliich they adhere, a
remarkable motion is seen to commence in them. The first indication of this
consists in a slight movement of a terminal fnistide, which begins to shdc

OF XUE DIATOME-E.

55

length^vise over its contiguous frastule ; tho second acts simultaneously in a
similar manner with regai-d to the third, and so on throughout the whole
filament, — the same action having been going on at the same time at both
ends of the filament, but in opposite directions. The central frustule thus
appeai-s to remain stationaiy, or nearly so, — while each of the others has
moved with a rapidity iacreasing with its distance fi'om the centre, its own
rate of movement having been increased by the addition of that of the inde-
pendent movement of each fnistide between it and the central one. This
lateral elongation of the filament continues until the point of contact between
the contiguous fmstules is reduced to a very small portion of their length,
when the filament is again contracted by the frustules sUdiug back again as
it were over each other ; and this changed direction of movement proceeding,
the filament is agaiu draAvn out until the frustules are agaia only slightly in
contact. The direction of the movement is then again reversed, and con-
tinues to alternate in opposite dii'ections, the time occupied in passing from
the elongation in one direction to the opposite being generally about 45
seconds. If a filament while in motion be forcibly divided, the uninjured
frustules of each portion continue to move as before, proving that the filament
is a compound structui'e, notwithstanding that its frastules move in imison.
When the filament is elongated to its utmost extent, it is extremely rigid, and
requires some comparatively considerable force to bend it, the whole filament
moving out of the way of any obstacle rather than bending or separating at the
joints. A higher temperature increases the rapidity of the movement."

To this account Prof. Smith appends these observations : — " The motion
here so accurately described is not essentially different from that noticeable
in many of the free species of Diatomese, the pecuharity being that it is
here exhibited in numerous united frustules ; when observed in a band of
one hundred or more frustules, the singular appearances assumed by the
filament under the action of so many individuals moving at one time in
apparent concert, and another in opposition, never fail to excite astonish-
ment."

Mr. Thwaites's account conveys the impression that the movements are
always regular : but this is not the case ; for Mr. Ealfs teUs us, by letter,
that both Dr. Bailey and himself have convinced themselves that they are
at many times irregular.

Dr. Don kin, in his description of a new species of Badllaria he names B.
cursoria (J. M. S. 1858, p. 27), has the following account of its singular move-
ments : — " When the filament is in a quiescent state, the frustules are all drawn
up side by side, their extremities being all in a Hne, thus forming a group.
When a filament previously at rest resumes its activity, the movement] is
commenced by the second or inner fnistule at one end of the filament gliding
forward along the contiguous sui-face of the first or outer frustule until their
opposite extremities overlap each other. This is soon followed by a similar
movement of the third, foui-th, and fifth, &c., aU moving fonvard in the same
direction, and each frustule gliding along the surface of the one preceding it,
until they have extended themselves into a lengthened filament or chain. In
the course of two or thi-ee seconds after this has been accomplished, a retrograde
movement, exactly of the same character, begins to take place, and continues
until the filament has retraced its course, and stretched itself out in a direction
exactly opposite to the position it had previously occupied. This phenomenon
is repeated again and again ; and in this manner the whole group is kept in
a state of activity for an indefinite period of time ; and aU the while, if no
impediment produces irregularity, tho outer or terminal frustule, next to
which tho movement commenced, vudntains a stationary and fived position.

56

GENERAL HISXOfiY OF THE DfrUSOItlA.

" The rapidity with which each individual frmtule moves is in direct ratio
to its distance from the terminal stationary frustule, being most rapid at the
opposite or moving extremity of the filament. On this account, most of the
fnistules, while the filament is moving to and fro, cross a Kne drawn at light
angles to the middle of the long axis of the stationary fnistule, at the same
instant of time, afterwards shooting past each other like horses on a race-
course.

" The force with which the filament moves is very great, so much so that
I have observed it upset and shove aside a large frmtule of A. arenaria, n.
sp., at least six times its own bulk, obstructing its path. This force is, in a
great measui'e, due to the rapidity with which the frustules move, — the time
which a filament, even of considerable length, occupies in crossing the field
of the microscope being only a few seconds.

" Light appears to be a necessary stimiilus for the maintenance of this
motion. When a filament in active motion is placed in the dark for a short
period, and then examined, the movement is seen to have ceased, but again
commences when the filament- is exposed to the light for a short time. Is
not this singular movement, with which the present species is endowed, a
vital phenomenon, and independent of physical causes for its existence ?

"When the moving extremity becomes entangled in any kind of substance
intercepting its course, the opposite or stationary extremity commences to
move, and continues to do so until the entangled extremity is set free ;
sometimes, in such instances, a fnistule in the centre remains fixed, a move-
ment of each half of the filament in opposite directions, on either side of it,
taking place. But all these iiTegularities cease as soon as the impediment
has been got rid of.

" These facts lead to the conclusion that the present species is a true Bacil-
laria, although apparently somewhat anomalous in the structure of its fr'ustule.
The gliding movement of one fnistule over the contiguous one is the same as
is observed in B. paradoxa ; but it differs from this latter species in this
essential particular, that the whole of its filament moves on one side of a
terminal frustule which is stationary, — while, in B. paradoxa, each half of the
filament moves in opposite directions on either side of a central stationary
frustule."

The movement of one segment upon another is witnessed in other con-
catenate species, but in a less degree, where the medium of attachment is
limited to a small space, as in those several genera having the alternate or
opposite angles of their frustules connected by a link-like isthmus, e. g.
Diatoma, Fragilaria, Grammatophora, &c.

NuTBiTivE FimcTioNs; — Supposed Stomachs; — Cieculation of Contents; —
Respibation. — The nutrition of Diatomese is provided for primaiily by the
endosmotic and exosmotic action going on thi-ough the ' foramina ' in the
sUicious epiderm, whereby fluid material laden with the matters necessary
to build up the various elements of the endochi'ome is introduced into the
organisms.

On the first appearance of a frustule, the cndochromc is homogeneous and
granular ; but as time advances, granules are seen to congi-egate in certain
parts, and globules or vesicles of various size speedily develope themselves,
and either take up definite positions or are irregularly difiiised. During
these changes in the contents — during, indeed, the entii-e life of the cell,
under the influence of Hght, oxygen is given off, and the gases with which
it was united in various chemical compounds are appropriated to the i)urposes
of the economy.

The very fact of the existence of the sUicious epiderm, thro^vn off, it would

OF THE DIATOMEiE.

67

soem, as an excretion from the organic membrane of the fnistules, indicates
the activity and energy of the nutritive functions,— a fact fui-ther demonstrated
by the production of the ' connecting membrane,' and, in short, by the whole
process of reproduction, whether by self-division or by sporangia. The silica
present in the lorica must be taken up by the organism in a state of solu-
tion ; and although the quantity of silica dissolved in water is inconceivably
small, it is nevertheless sufacient to supply the material for the construction
of millions of Diatomaceous shells, even in a short time, as the phenomena
of reproduction and the rapid appearance of these structures as an appre-
ciable powder, or as a colouring matter in water, prove. " It is probable," says
Dr. Gregory {J. M. S. 1855, p. 2), " that as fast as the silex is extracted from
the water by them, it is dissolved from the rocks or earths in contact with
the water, so that the supply never fails;" and we may add, so that the
quantity never accumulates beyond the veiy minute fractional portion chemists
can detect.

Ehrenberg's untenable hypothesis of the presence of stomach-sacs and of an
alimentary canal opening externally has received suf&cient attention in the
history already given (pp. 47, 48), of the nature of the contents of the Diatomeae
and of their investing lorica. Were other considerations needed, the absence
at times of any such vesicles as Ehrenberg conceived to be gastric cells, their
occasional coalescence, and the phenomenon of cyclosis or the circulation of
the contents, each and all subjects of direct observation, might be appealed
to as proofs of the errors that great naturalist fell into respecting the internal
organization of the Diatomese.

The phenomenon of cyclosis has been observed by NageH in a species of
Navicula, and in one of Gallionella (Melosira) (XY. 27), and by Prof. Smith
in other Diatoms. This writer says (op. cit. i. p. xxi) — " In Swirella biseriata
this motion has been more especially apparent ; but I have also observed it
take place in Nitzschia scalaris and Campylodiscus scalaris. This circulation
has not, however, the regularity of movement so conspicuous in the Des-
midiese, and is of too ambiguous a character to fuiTiish data for any very certain
conclusions, save one, viz. that the Diatom must be a single cell, and cannot
contain a number of separate organs, such as have been alleged to occupy its
interior, — since the endochrome moves freely from one portion of the fnistule
to the other, approaching and receding from the central nucleus unimpeded
by any intervening obstacle."

Schultze, in his contribution on the movements within the frustules of
Diatomeae (Mull. Archiv, 1868), represents them to occur in and along the
finely granular threads into which the less fluid mucilaginous portion of the
endochi-ome is drawn out. He compares the movements in character to
those of the 'variable processes' or pseudopoda of Ehizopodes, and thereby
assimilates the mucilaginous films of Diatomaceous frustules -with the soft
sarcode of those simplest animalcules, — a similarity coimtenanced by the now
well-known fact of an Amcebiform phase in the cycle of development of some
of the lower Algas (vide section on Phytozoa). The cyclosis in plant-ceUs is
no doubt rightly attributed to the operation of the vital processes of nutrition
and of the so-called respiration, and primarily to the chemico-vital action
proceeding by the medium of the chlorophyU-globulcs ; and it seems most con-
sonant with the teachings of science to assign the less active and less complete
and regular internal movements of the Diatomeae also to the similar vital
forces,— the coloured cori^uscles, it may be, acting here Hkewise as the prime
mover. We are aware that the nucleus has been represented to be the first
8oui-ce of the movements in plant-cells, since the current seems to flow from
and to retui-n to it in many cases ; but this phenomenon is cxpUcable in

58

GENERAL. HISTOKY OF THE INFUSOKIA.

another way, by admitting the disposition of the raucous threads as displayed
by Schultze, extending as they do from the nucleus on all sides, and serving
at the same time to limit and to direct the movements taking place vv'ithin
and by them. We have not adverted to ciliary action as the cause, for ; so
far as we can gather, Mr. Osborne and Mr. Jabez Hogg have failed to impress
many naturalists vrith the fact of its existence and operation in Diatoms.

Lastly, Schultze remarks that, to see the mucilaginous threads and the
internal movements, living and fi-esh specimens are needed ; for they are soon
arrested when the fi'ustiiles ai-e removed from theii* natural habitats, and ai-e
quite lost to vision when they become diy. Hence it is, no doubt, that no
previous observer has detected and rightly apprehended the facts enunciated
by Schultze.

The so-caUed function of respiration is evinced in the fixing of the carbon
of the carbonic acid and in the disengagement of oxygen gas ; but this is
rather an act of nutrition, and resembles that silent and invisible disengage-
ment of certain particles, and the rearrangement of others, which proceed in
the formation and in the removal of worn-out tissues in higher animals.

Multiplication', Reproduction, and Development of Diatome^. — Among
the modes of reproduction of the Diatomeae, self- division has usually been
accounted one, but erroneously so, since this process is no more than a mul-
tiplication of an individual cell, and completely homologous with the process
of cell-fission exhibited in the constmction of animal and vegetable tissues
in general. The pecuharity in the self-division of the Diatomeae, i. e. among
the free simple beings, is, that the division is followed by separation ; for
each cell, instead of uniting with its neighbours in the formation of a tissue,
commences an independent existence. Self-division in one direction, not
followed by separation, produces the filamentary or concatenated Diatomeae,
whilst the abundant excretion of a mucus around the dividing frustules, and
its persistence, give rise to the frondose genera, which make an approach
towards the character of vegetable cellular tissue, — each cell, however, retain-
ing an independent vitality greatly more pronounced than in the latter.

The process of self-fission or dedupHcation in this family resembles in all
essential particulars that in other vegetable cells (XV. 28, a, b, c). Preparatory
to its visible occurrence, or rather simultaneously with certain changes in the
interior, the valves separate by the progressive growth of the connecting
membrane. The nucleus -within is observed to divide into two portions, each
of which eventually becomes detached fi-om the other, and, in Prof. Owen's
language, seiTes as a centre of spermatic force, and induces an aggregation
of the granules of the endochrome about it. Whilst this separation of the
nucleus and of the general contents is going fonvard, the lining or primordial
membrane of the cell becomes doubled inwards in the cntii-e cii-cimiference
along the line of division, and advances gradually until it at length forms a
complete septum, cutting the onginal single cell into two. This septum is
actually double ; and in each lamina a deposit of silicious material speedily
proceeds, so as to produce two new valves, each opposed to, and immediately
continuous around its circumference vdth, one of the two original valves.
Thus, on the completion of this process of dcduplication, two frustules resiilt,
awaiting only the final act of separation to enter on an independent exist-
ence and to repeat the like series of phenomena, and so on through a
seemingly almost endless chain, to perpetuate the existence of the particular
species or individual. (See Meneghini's account of the process and peculiari-
ties of self-division in this class, in the examination of the arguments for the
animality of the DiatomacciB, in a subsequent page.) The true nature, there-
fore, of this process of self- division being an extension, not a renewal, of

OF THE DIATOMEiE.

59

individual life, has been justly represented by Mr. Thwaites as an act of
gemmation, not of reproduction.

In the course of self- division, in some instances at least, a mucous or
muco-gelatinous matter is thrown out around the frustules engaged. This
cii-cumstance did not escape the notice of Niigeli ; and Prof Smith (Synopsis,
i. p. 62) has, after noting it in previous pages as"a common phenomenon in the
family, thus referred to it in the genus Pleuro'sigma : — " While self-division
is actively going forward, the mucus generated by the dividing fnistiiles is
often so considerable as to produce the appearance and effect of a_ distinct
frond, which assumes the form of a thin pellicle of some little tenacity. At
other times, when the mucous secretion does not assume the continuity of a
pellicle, it invests the individual frustule with a transparent envelope, which
has the appearance of an exterior membrane, and has been sometimes mis-
taken for such. On one occasion I also met with the frustules of P. Hippo-
campus enclosed in mucous or gelatinous tubes, precisely like those of a
Colletonema ; but these conditions must be regarded, for the present at least,
as temporary or accidental, and cannot be admitted into the specific or generic
descriptions."

The process of self-division is affected in some unimportant particulars by
the figure and habits of certain genera. Thus in one section of the Melosirece,
the frustules of which have convex ends, Mr. EaLfs points out {A. N. H.
xii. p. 347) that the central line is more strongly marked, and seems to
divide the frustule into two equal portions. It becomes broader, and at length
double, and ultimately an intermediate growth separates the two halves of
the frustule, which, during this process, do not increase in size ; but when
the intermediate space is equal to the diameter of the original frustule, two
new frustules are formed, by the addition of two hemispheres on the inner
sides of the separated portions. The outer siUcious covering still remaining,
the frustules are connected in pairs, and appear like two globules within a
joint, as they are characterized by Harvey in Melosira numinuloides, and by
Carmichael in M. globifera. The above description belongs more particularly
to M. nummuloicles ; but the process in the other species of this section is the
same : a series of changes, nearly similar, occurs in Isthmia.

" In this genus," the author quoted says, " the mode of growth is very
curious. As in most of the Diatomeae, the plant increases by a division of
the frustules ; but in this genus, as also in Biddulphia and Amphitetras
(and in the Achnanthece), two new frustules are formed within the old one
and as they enlarge, rupture it, when it falls off. In these the front portion
is at first very narrow, and merely a broad line, but it increases greatly in
breadth until the new frustules are fuUy formed." In this description and
explanation the widening band or front portion mentioned is in fact the
' connecting membrane ' of Prof. Smith, which, in the genera named, has
an extra development, " an extension beyond the sutures of the valves," and
also an unusual persistence, retaining the two frastules together after self-
division, in such a manner that they seem to be enclosed within an original
single frusttdc, just as Mr. RaLfs describes.

This longer persistence of the connecting membrane has been noted by
Prof Smith (A. N. H. 1851, p. 4), who writes—" In some cases, by the
new, or rather semi-new frustules proceeding immediately to repeat the
process [of self-division], the connecting membrane is thi-oAvn off and disap-
pears ; in others it remains for some time, linking the fi-ustulcs in pairs as
in Melosira and Odontella." ^ '

Another peculiarity, again, not unfroquently obtains in this process of self
fission, VIZ. a departure from the prevailing law of similarity which exists

60

GEKEJIAL HISTORY OF THE INFTJSOEIA.

between the new valve and the parent one with which it is united in the
newly- created frustule. The newly-developed segment occasionally acquires
slightly greater dimensions, — a fact best exliibited in the filamentous genera,
since in them it gives rise to an evident irregidarity in the chain, affecting its
width. Yet, as Prof. Smith remarks (i. p. xxvi), " This increase is so small,
that in a filament of many hundred fmstules, the enlargement is scarcely
appreciable. The rapid attenuation represented by some authors ia the
filaments of the Fragilarice must therefore be attributed to the deceptive
appearance presented by a compressed band when slightly twisted, the sem-
blance of attenuation being thus given to the portions which are presented
in an oblique direction to the eye of the observer .... Starting from a single
frustule, it will be at once apparent, that if its valves remain unaltered in
size, while the ceU-membrane experiences repeated self-division, we shall
have two frustules constantly retaining their original dimensions, four slightly
increased, eight somewhat larger, and so on in a geometrical ratio, which
wiU soon present us with an innumerable midtitude containing individuals in
every stage, but in which the larger sizes preponderate over the smaller ; and
such are the circumstances ordinarily found to attend the presence of large
numbers of these organisms."

Mr. Ralfs has favoured us with the following remarks on this subject in
letters. He writes (March 1856) — " In a recent number of the Ann. Nat.
Hist., Mr. Carter expresses his belief that the frustules of Diatomaceae gra-
dually become smaller by division, and that it requires the sporangial frustule
from time to time to keep them the proper size. This I cannot admit ; for
any person who wiU take the trouble to watch a species of GompTwnema
from its first appearance in spring, as a scarcely visible fringe to aquatic
plants, win observe not only increase of mass, but also enlargement of the
frustules. If Mr. Carter is right, the filament in Fragilaria would be very
unequal : for instance, as the first-formed frustule could not decrease, and as
its segments after division would always form the two ends of the filament,
they should be the largest, then the adjacent valves of the two central frustules
of the filament the next largest, and so on." In a subsequent letter the
same distinguished authority wiites : — " I see that Prof. Smith, in his
Synopsis, p. xxvi, takes the contrary view to Mi-. Carter, and considers that
the frustules do not grow after they are fully formed, but that, in dividing,
the new frustules may slightly increase in size. It is thus that he accounts
" for the varying breadth of the bands in the filamentous species, and the
diversity of size in the fmstules of the free forms." If he is correct, his
opinion is stiU more adverse to Mr. Carter's views respecting the frustules
formed after self- division. But I doubt also the correctness of Mr. Smith's
views. He himself states that " the enlargement is scarcely appreciable ;"
and yet we fljid a vast difference of size in the fiiistules of the same gather-
ing. The filaments are so fragile in Fracjilaria, and even in Himantidium,
that it is very difficult to determine whether tlic fmstules in the same fila-
ment do differ much in size, and whether, if they do, the variations are alter-
nating or irregular, as would be the case if either Prof. Smith or Mr. Carter
be correct.

The rate of production of specimens of Diatomese, even by this one pro-
cess of simple self-division, is something really extraordinary. So soon as
a fmstule is divided into two, each of the latter at once proceeds with
the act of self- division ; so that, to use Prof. Smith's approximative cal-
culation of the possible rapidity of multiplication, supposing the process
to occupy, in any single instance, twenty-four hom-s, " we should have, as
the progeny of a single frustule, the amazing number of one thousand

OF THE DIATOMTEiE.

61

millions in a single month —a cii-cumstanco wliich will in some degree explain
the sudden, or at least rapid appearance of vast mimbers of these organisms
in localities where they were, but a short time previously, either unrecognized
or only sparingly diflused."

This multiplication by self- division now described, is generally supposed,
after a time, so to speak, to exhaust itself, and thereby to render necessary
other plans of propagating species. That some other modes do really exist
is suggested by the fact of the considerable variations of size of frustules of
the same species obtained at one time from the same locality, and moreover
by diversities in the relative distance and in the delicacy of the striae of the
surface. One such mode of propagation Mr. Thwaites has demonstrated to
consist in the production of sporangial frustules by a process of conjugation
analogous to that in the Desmidieae and many other Algae.

Conjugation. — The method of conjugation, although essentially alike in^ all
cases, exhibits several important modifications ia the genera of this family.
These were more or less clearly perceived by Mr. Thwaites, who spoke of them
as exceptional varieties ; but to Mr. Smith belongs the credit of reducing all
of them under four principal forms: viz., 1. That in wliich two parent frustules
produce two sporangia by conjugation, as m.Epithemia,Cocconema,Oomjphonema,
Encyonema, and Colhtonema. 2. Two parent frustules generate a single spo-
rangium, e. g. in Himanticlimn. 3. " The valves (vol. ii. p. xii) of a single
fnistule separate, the contents set free rapidly increase in bulk, and finally
become condensed into a single sporangium. This may be seen in Cocconeis,
C'yclotella, Melosira, Orthosira, and Schizonema.

" In Melosira nummicloides, M. Borrerii, and M. svhjlexilis, the second valve
of the conjugating frustule is rarely found united to the mucus surrounding
the sporangium, the conjugation taking place only in the last frustule of the
filament ; but in Melosira varians and Orthosira 07'ichalcea, conjugation taking
place throughout the entire filament, both valves are usually found adherent
to the sporangium or its suri'ounding mucus.

" From a single frustule, as in the last method, two sporangia are produced
in the process of conjugation : this takes place in Achnanth.es and Shabdonema."

In describing the process as generally as possible, we cannot do better than
follow Mr. Thwaites's account, although it is illustrated by an example taken
from the fij'st category of variations. " For the most part," he tells us,
" conjugation in the Diatomeae, as in the Desmidieae, consists in the union
of the endochrome of two approximated fronds, — this mixed endochrome
developing around itself a proper membrane, and thus becoming converted
into the sporangium. In a veiy early stage of the process, the conjugated
frustules, as in Eunotia turgida, have their concave surfaces in nearly close
apposition (XI. 1), and from each of these surfaces two protuberances arise,
which meet two similar ones in the opposite frastule (XI. 3) ; these protu-
berances indicate the future channels of communication by which the endo-
chrome of the two frustules becomes united, as wcU as the spot where is
subsequently developed the double sporangium, or rather the two sporangia.
A front view of two frastules at the same period shows each of them to have
divided longitudinally into two halves (XI. 4), which, though some distance
apart, are still held together by a very delicate membrane : this, however
soon disappears. '

" The mixed endochrome occurs, at first, as two irregular masses between
the connected frustules ; but these masses shortly become covered, each with
a smooth cyUndrical membrane,— the yoimg sporangia, which graduaUv
increase m length (XI. 5, 6), retaining neariy a cylindrical form (XI 7)
untU they far exceed m dimension the parent fnistules, and at length when

62

GENERAL HISTORY OF THE INFUSORIA.

mature, become, like them, transversely striated upon the surface (XI, 8).
Around the whole structure a considerable quantity of mucus has, during
this time, been developed, by which the empty fi-ustiiles are held attached to
the sporangia (XI. 5-8)."

The variations in the process are aUuded to in the following extracts from
the same eminent observer's papers : — " In different genera, slight variations
are met with in the method of conjugation : thus, in some species of Gom-
jphonema the sporangia lie in a direction parallel to the empty fi-ustules,
instead of across them, as described in Eunotia turgida. Again, there are
examples (in Oomphonema minutissimum and Fragilaria pectinalis) where,
instead of the conjugated frustules separating into two halves, only a slit
appears at one end, to sei-ve for the escape of the endochrome. Instead also
of the pau- of conjugated fnistules producing between them two sporangia,
they may develope but a single one, as happens in Fragilaria pectinalis. In
this species, too, the sporangium, at fii'st cylindrical, soon assumes a flattened,
somewhat quadrangular form, and in many cases undergoes fissiparous divi-
sion before it has put on the exact appearance of the frustule of a Fragilaria.

"The Melosirece (Gallionellce, Ehr.) and the Biddulphice," Mr. Thwaites
remarks, " would seem, in their development of sporangia, to offer an excep-
tion to most Diatomeae ; for in those genera no evident conjugation has been
seen. However, something analogous to it must take place ; for, excepting
the mixture of endochi'omes of two cells, the phenomena are of precisely
similar character. Thus, instead of the conjugation of two frustules (XV.
29, a, h, c, d, 32, 33), a change takes place in the endochrome of a single
fiTistule, — that is, a disturbance of its previous arrangement, a moving
towards the centre of the frustule, and a rapid increase in its quantity:
subsequently to this it becomes a sporangium ; and out of this are developed
sporangial frustules, as in the other Diatomeae. In a single cell, therefore,
a process physiologically precisely similar to that occurring between two
conjugating cells takes place ; and it is not difficult to believe, taking into
view the secondary character of ceU-membrane, that the two kinds of endo-
chrome may be developed at the opposite ends of one frustiile, as easily as in
two contigixous frustules, and give rise to the same phenomena as ordinary
conjugation."

Further, in his notes on Schizonema subcohcerens, Mr. Thwaites writes, —
" The sporangia of this species are produced by the conjugation of a pair of
frustules outside the filaments ; but sporangial fnistules are frequently found
in a filament intermixed with ordinary frustules, from which they differ only
in size."

Dr. Griffith and Mr. Carter, moreover, have portrayed pecvdiarities in
the conjugating process, which Prof. Smith can neither explain nor confirm,
and is equally unable to reduce under either of the leading variations he has
defined. The first-named natm-alist stated that in the conjugation of a
species of Navicula (ampliirhynchus ?) a silicious sheath enveloped the spo-
rangial frustule, indestructible by heat and nitric acid. " It is," he writes,
" colourless, elongate, rounded at the ends, and furnished with coarse trans-
verse strise or depressions, tkrough which the line of fracture nms when the
object is crushed." This account seems to Prof. Smith erroneous; and he
suggests that this sheath " may probably have been an appearan^x resulting
from the condeiisation and coiTugation of the mucus developed around the
reproductive body." This conclusion Dr. Griffiths declares untenable, since
no kind of mucus wiU resist the action of a red heat and nitric acid. The
specimen examined was, besides, not an isolated one, but hundi-eds such were
present " {A. N. H. xvi. 92).

OF THE DIATOMEiE.

63

Prof. Smith thus alludes to Mr. Carter's views The cii-eumstance
dwelt upon by Mr. Carter as having an important bearing upon the rationale
of the process, viz. that one of the conjugating frastules is invariably smaller
than the other, is altogether at variance with my experience, and is totally
iiTeconcilablo with the process as it occurs in the genera- mentioned under
the thii-d and foiu-th classes. 1 am therefore disposed to believe that the
difference in size noticed by Mr. Carter was a mere accidental diversity, and
of no essential signification."

The fom- typical modes of conjugation established by Prof. Smith have
their occurrence thus explained (Synoj>s. ii. p. xiii) :— " The functions of
life and growth are not suspended during the act of conjugation; and
in consequence self-division may take place at any stage of the process
which accompanies the formation of the reproductive body, or the latter
process may intrude upon, or arrest any step in the progress of self-divi-
sion.

" In the first mode of conjugation, as occurring in Epitliemia, &c., self-
division may be r^arded as xa. the earliest stage of its progress, which merely
involves the separation of the endochrome of the parent frustules into two
portions, but does not include such a differentiation of these portions as
renders them capable of the conjugative act : the endochrome capable of
conjugating with these segregated portions must be sought for in other
frustules ; hence the process in these genera involves the presence of two
parent frustiiles, and results in the production of two sporangia.

" In the second mode, met with in Himantidium, the progress of separa-
tion is arrested at a still earlier stage ; no differentiation has taken place,
and conjugation intervening, necessitates the union of the entire contents of
two parent frustiiles to form a single sporangium.

" In the third mode, the progress of the separation of the endochrome in
the parent frustule must be considered as so far advanced that complete
differentiation has taken place. In every respect but the formation of new
valves, self-division has been completed ; the incomplete frustules are there-
fore prepared for conjugation, which, intervening at this stage, leads the
observer to believe that but one frustule has been concerned in the produc-
tion of the siagle sporangium. This we see in Melosira and the other genera
mentioned under this class.

"And lastly, self-division occurring during the progress of conjugation,
the endochrome becomes segregated in the very act of intermingling, and a
single frustule, whose contents have been abeady differentiated, gives rise to
two sporangia, as in AcJmanthes and Rhahdonema.

" Nor is the self-dividing disposition in all cases permanently arrested by
the complete formation of the sporangium. Having assumed the form of the
parent frustules, with a great increase in size (the enlargement in dimen-
sions being in some cases due to the accumulation of the contents of the two
conjugating frustules, and in others to a rapid assimilation of nutritive
material fi-om the surrounding mediimi), the sporangial fnistule immediately
submits to self- division, and by the repetition of this act dcvelopes a series
of frustules equal in size to the original product of the conjugating process.
This is notably the case in the filamentous species, as may be easily seen
in Melosira, in Ortliosira, and in Himantidium. How far this self- division
may be carried in the sporangial frastules is at present unknown ; it is pro-
bably of short duration, as we rarely meet with any considerable 'number of
frustules characterized by the enlarged size of the sporangial form In most
cases an arrest of growth, and conscquentiy of self- division, seems imme-
diately to foUow the complete formation of the sporangia, and the reproduc-

64

GENERAL HISTORY OF THE INFtTSORIA.

tive body assumes the quiescent character which belongs to the seed of the
higher plant, its vital function remaining dormant until circumstances favour
its further development and the production of the young frustules of which
it is the destined parent.

" In the gathering of Oocconema Vistula made ia April 1852, which con-
tained numerous instances of the conjugating process, I observed the frequent
occim-ence of cysts enclosing minute bodies, variable in their number and
size, and many of which had the outline and markings of the surrounding
forms, and were obviously young frustules of the Cocconema. It would appear
from the figures [appended to this account], that the production of the young
frustules is preceded by the separation and throwing off of the silicious valves
of the sporangium, and the constriction or enlargement of its primordial
utricle, according to the number of yoimg frustules originating in its pro-
toplasmic contents. In this gathering, forms of every size intermediate
between the minutest frustule in the cyst and the ordinary frustules engaged
in the conjugating process were easily to be detected ; and the conclusion
was inevitable, that the cysts and their contents were spoi'angia of the species
with which they were associated, and indicated the several stages of the re-
productive process."

Since the preceding account of conjugation was wiitten, a valuable, although
not a very lucid, contribution on the subject has appeared by Dr. Hofmeister,
in the Eeports of the Saxony Natural History Society for 1857, and has been
translated by Prof. Henfrey in the A. N. H. for January 1858. Prom this
we extract the following as supplementary to the previously- written history
of the conjugation-process and of self -fission, as well of the Desmidieae (p.ll)
as of the Diatomeae : —

" Conjugation is far more rarely met with in the Diatome^ than in the
Desmidieag. It appears that this process occurs here only at particular
epochs, differing according to the seasons, happening simultaneously in all
individuals, and quickly completed. Trequently as indications of conjugation
having taken place have been met with (the occurrence of individuals of the
same species, of remarkable diversity of size, side by side, in free Diatomeae,
e. g. Pinnularia viridis, Surirella bifrons, Staurosigina lacustre, all the year
round, besides the occurrence of shorter or longer rows of cells of about
double the diameter, in the bands, of the forms remaining connected by the
lateral surfaces, e. g. Melosira, Podosira), yet it has seldom happened that
they have been met with in the moment of conjugation.

" Since the classic researches of Thwaites upon this subject, the knowledge
of it has on the whole been but little advanced by the obsei-vations of Focke
(conjugation of Surirella), Giiffith (conjugation of Navicida), "W. Smith and
Carter (conjugation of Cocconeis, Cymbella, Amphora^. The following cases
have been observed ; — " Formation of a single conjugation-cell, dividing very
soon after its origin : in Himantidium pectorale, Cymbella Kutzingiana, Cocco-
neis Pediculus, Cocconeis Placentula, Qomphonema lanceolatunu Schizoriema
Orevillii, Orthosira orichalcea, 0. Bickiei, remarkable from the repeated throw-
ing-off' of the coats of the conjugation-cell, the cracked halves of which clothed
the conical ends of the conjugation-cell in shape of funnels ; Orthosira va-
rians, Surirella bifrons, and a Navicula not specifically determined. Here
belongs also the only conjugation of a Diatomacean that I have seen, that of
Cyclotella operculata, conjugation-cells of which, mth adherent empty coats
of the mother-cells, I found abundantly in ditches of a marshy meadow not
far from Leipsic, in October 1852. They were not distinguishable in any
essential respect from the Cyclotella Kutzingiana figured by Thwaites.

" Next to these cases of the fonnation in the firet place of only one conju-

\

OF THE DIATOME.'E.

65

gation-cell, come a series of obsei-vations in which two new cells were seen
betAveen the empty conjugated mother-cells, without any convincing evidence
being offered of a division of the mother-cells having occurred just before
conjugation, as in the cases hereafter to be mentioned, — where, rather, the
position of the empty cells in relation to the conjugation-cells, and the affinity
of the forms in question to some in which the entii-e development has been
observed, render it probable that the unicellular condition of the conjugation-
cell has hitherto escaped observation. In this group are to be counted Goc-
conema lanceolatum, C. Cistula, Goniphonema dicliotomum, G. lanceolatum, G.
marinum,Achnanthes Jongipes,Bhahdonema arcuatum,Oolletonema subcoh(xrens.

" In a smaller number of Diatomeae, species of the genera so nearly allied
together, Epithemia, Cymhella, and Amphora, the conjugation is immediately
preceded by a division of the mother-cells into two, analogous to the division
of the cells of Chsterium rostratum when about to conjugate. This division
is longitudinal, taking place exactly as in the vegetative division in Cymhella
Pediculus, AmjjJwra ovalis, and Epithemia Sorex, but transverse and in a
direction crossing that of the vegetative division in Epithemia turgida, E. gihba,
and E. verrucosa.

" Recent observations show distinctly that the conjugation of the Diatomeas
agrees in all essential points with that of the Desmidiefe. "When a cell is
about to conjiigate, there is produced in it a coat round the entii'e contents,
accurately liiing the old membrane, but not adhering to it. The growth of
this coat cracks the old cell-membrane exactly in the same way as occurs in
vegetative division. From the fissure the young, smooth coat emerges, in the
form of a vesicle, and unites with the similar structtu'e produced by a neigh-
bouring cell. Al. Brann thought it must be assumed, from Thwaites's obser-
vations, that the primordial utricles of the two conjugating Diatomean cells
united ; but that this is not the case, and that a soft and flexible cell-mem-
brane, protruded from the cracked, rigid, old shell, encloses the contents
destined to be blended with those of the neighboming cell, is distinctly shown
by Smith's figiu'e of Rhabdonema arcuatum, and Carter's of Cocconeis Pedi-
culus and Amphora ovalis. The introductoiy part of the conjugation is dis-
tinguished in no respect from the vegetative cell-division in Epithemia Sorex,
Amphora ovalis and Cymhella Pediculus, and, further, in Chsterium rostrat\(,m ;
in Epithemia turgida, gihba, and verrucosa, only by a different position of the
wall dividing the mother-ceU ; in the rest of the Diatomeae and Desmidiete, by
omission of the formation of septa, — frequently, also, by one-sided dehiscence
of the cracked mother-cell, whose shells remain stUl connected at one side.

" Thwaites's observations established that the cell produced from the conju-
gation of two cells of a Diatomacean, very soon after its origin, assiimcd tlio
form of the mother-ceU, becoming distinguishable from it almost solely by
being twice as large. Smith has endeavom-cd to render it probable that the
colonies of young individuals, enclosed in a cyst, of Cocconeis Cistula, Gom-
phonema dichotomum, and Synedra radians, some of which he found associated
with conjugated, full-grown individuals, must have originated from the divi-
sion of the spores (sporanges of Enghsh authors). This hj-pothesis has much
in its favour, but, in the present condition of our knowledge, it is inexplicable
where the sihcious shells of the spore-ceUs remain. HoAvever this may be,
there is no doubt of the occiuTcnce of cysts of this land. In the same pools
of a marshy meadow which repeatedly fiu-nished me with conjugated indivi-
duals of Cyclotella late in autumn, I found, in early spring of two successive
years, globidar cells, each of which enclosed a great number (32 to 40) of
small individuals of the same species. The walls of these cells appeared
shai-ply defined internally and extemaUy ; the contents of a thin, fluid natm-e

66

GENERAL HISTOKY OF THE IKFTJSOEIA,

Structures similar to those represented by Smith, of Synedra radians, occurred
in extreme abundance in the end of the autumn of 1854, in company with
Synedra Ulna. Here the cells, which, like those observed by Smith in the
allied species, had a diseased aspect and an abnonnal arrangement of the
coloured contents, were imbedded in a granular jelly, of a reddish colour by
transmitted light. I very much doubt whether these last were in a condition
capable of further development ; while in reference to the cysts of Cydotella
ojpereidata, I share Smith's opinion.

" The establishment of the assertion that the commencement of conjugation,
in the Desmidieae and Diatomeaj is but little distinguished from the com-
mencement of vegetative cell-division, renders some discussion of the latter
requisite. Pringsheim has already directed attention to the resemblance of
this process in the Desmidieae to the vegetative cell-multiplication of the
joints of (Edogonium. In fact, it is an absolutely general phenomenon in the
true Desmidieae, so far as observation reaches, that the older parts of the
membrane of a cell about to divide, do not, as in other cases (for example,
in Zygnemeae), regularly increase in size with the parent-ceU by growth in
all (hrections ; but the older, outer layers of the integument spHt open Avith
an annular crack at the equator of the cell, shortly after (or during ?) the
division. They still remain sticking on, covering the ends of the cell with a
thick envelope, but become removed gradually further apart by the interpo-
sition of new cellulose between their fractured edges. The interposed new
coat is the direct continuation of that which lines the internal surface of the
cracked halves of the old shell. It is the margins of the half-shells which
constitute the rings, parallel to the end-surfaces, upon the cylindrical lateral
surfaces of the cells of Hyalotheca dissiliens and H. mucosa, the wrinkled pro-
jections of the membrane in the middle of the deep constriction of the ceU of
Micrasterias and the large Euastra, of the flat constriction of the cell of
Docidium, as also the ring at the equator of the external surface of Closte-
rium : in Closterium and in Docidium, frequently as many as six may be
counted, — a phenomenon which, in Docidium tmncatum and the large Clos-
teria, may be recognized at fii'st sight as dependent upon a number of halves
of cracked cells regularly encasing their successors.

*' The dehiscence of the coat of the dividing cell is, in all observed cases,
preceded by the formation of the septum dividing the cell into two halves
\Cosmarium margaritiferum). The gradual development of tliis from the
margin of the ceU-wall inwards, as a gradually- widening annular fold of the
innermost layer of the integument, has not yet been observed, and, from
analogy vsdth the processes in (Edogonium, is scarcely probable. But, as in
(Edogonium, the contents of the cell may be contracted, before the formation
of the septum, into two masses, in contact, but separated by a sharp hne
of demarcation (two contracted daughter- cells imperfectly cut off from one
another, still adhei-ing together at the place of constriction).

" From the half-shells of cells of the same Docidium which dehisced under
the eye of the obsei-ver, emerged, within half-an-hour, to the extent of -^th or
|th of the length of the half-shells, the daughter- cells, still intimately con
nected at the point of contact. They could henceforth be perceived to
enclosed by a ccUulose coat, firm although delicate. Treated with rcagen
strongly extracting water, such as glycerine, one or both of the extruded
pieces frequently drew back into the halves of the shells of the mother-cell,
the projecting pieces of membrane becoming doubled inwards. The just-
emerged coats of the daiighter- cells of Docidium did not take a blue colour
when treated with iodized chloride of zinc, while the old halves of the mem-
brane of the divided cell assumed the blue colour immediately.

OP THE DIATOME^.

67

" In Cosmarium margaritife^nm, and Staurastrum dejectum, it may be easily-
observed that a slight elongation of the isthmus, and the fonnation of a septum
passing across the middle of this, precede the appearance of new half-cells
in the deep constriction. It is after the appearance of the septum that the
old wall of the mother- cell breaks by an annular fissure exactly at the place
where that septiun is formed. The two halves of the old cell-coat ai-e then
separated by the bulging-out of the younger, inner layers of membrane, not
fii-mly adherent to the old portions. The new halves are at first lined only
by protraded portions of the peUicle of their contents (outermost layer of
the parietal coats of protoplasm) belonging to the older half-ceUs ; from the
moment only of the dehiscence of the old ceU-coat, does a portion of the
granular' contents of the older cell-halves make its way into the new emerging
halves.

" In like manner, doubtless, occurs the cell- division of Micrasterias, of the
large fonns of Euastrum, Cosmarium, Staurastrum, and other Desmidieae,
only that they have not been observed completely, because these larger Des-
midieas very seldom multiply by division out of their natural stations. The
cell-division of the Diatomeae that have hitherto been observed in vegetative
multiplication, differs in essential points from that just described.

" When a cell of Navicula {Pinnularia) viridis is about to divide, there
appears upon one of the secondary sides (front view of English authors),
parallel to the primary sides (the furrowed faces of the cell having an elon-
gated eUiptical outline), an annular rim, which, growing gradually inwards,
constricts the contents of the cell by an annular furrow, in a manner exactly
similar to that of the commencement of cross- division in a cell of Cladophora.
When a ceU in this state is treated with substances producing slight endos-
mosis (for instance, a weak solution of carbonate of ammonia), the contents
retract on both sides from the annular rim, and constitute two completely
separate cell-like structures (halves of a primordial utricle), each of a very
long eUipsoidal form, and each lying close against one of the primary sides
{faces of halves) of the cell. When the annular lim has grown inwards to
about the sixth part of the shortest diameter of the cell, its development is
arrested. In natural conditions, this stage is succeeded by the retraction of
the primordial utricle from it. Each of these halves of the ceU-contents
becomes clothed, on the side turned away from the primary side of the cell,
with a new membrane, which soon exhibits the first indications of the pecu-
liar thickening ribs and nodules of one of the primary sides of our Pinnularia
The ceH has now completed its division. Seen from one of the secondary
sides, it contains two new individuals, equal to the mother-ceU in length and
breadth, but only possessing one-thii'd of its thickness. The externally-
situated primary side of each of them is the old primary side of the mother-
cell, to which we must imagine the newly-formed membrane of the daughter-
cell closely adherent at all points. Perhaps the narrow secondary sides of
the new cells may be in the same condition. But the contiguous primary
sides of the daughter- cells are totally new stmctures, which, developed rapidly,
in a short time become similar to the old primary sides in eveiy part. The
two daughter- cells are at fii'st held together by the broad middle piece of the
secondary sides of the mother-cell, bearing the above-mentioned annular rim
inside. The contents of the intermediate space consist of a transparent fluid
destitute of any solid structiu-es, doubtless pure water. The two daughter-
cells are finally set free by the gradual ' weathering ' of the zone-membrane
which holds them together. The division of Surirella bifrons takes place
exactly in the same way. An essentially similar kind of vegetative multipli-
cation is widely diflfused, if not general, in the Diatometo. The well-known

F 2

68 GENERAL HISTORY OF THE INFUSOHTA.

phenomenon of the formation of a tubular membrane, often impregnated vath
silex, and elegantly dotted or areolated, connecting the tn-o segments of
Isthmia, Mclosira, &e., depends upon the same process.

^' An analogous case is met with in the fonnation of the spores of Pellia
epiphylla. The mother-cell here produces six ridges of cellulose projecting
inward from the internal wall, intersecting at an angle of fiO° ; these ridges
grow in toward the middle point of tho cell, Hke the annular ridge of Cla-
doj)hora at the commencement of cell-division. When these projecting ridges
have attained the breadth of a fourth part of the transveree diameter of the
mother-cell, the cell-contents divide into four parts, which, retracting from
one another and from those ridges, occupy tho four chambers of the cell, each
of which is vaulted externally and bounded laterally by thi-ee of the ridges, —
here becoming coated with a membrane and developed into a spore, while the
tetrahedral space in the middle of the cell, bounded by the six ridges, remains
filled only with waterj' fluid. The spores become free by the solution of the
enveloping part of the membrane of the mother- ceU. The resemblance of
this process to the vegetative multiplication of Navicula consists in the inter-
niption of the division of the cell by the formation of septa, and the subse-
quent completion of the daughter-cells by secretion of membrane on the
external surface of contracted portions of the contents of the mother-cell.
A deviation occurs in the circumstance that in Pellia the segment of the coat
of the mother-cell which is in contact with the external surface of the daughter-
cell becomes dissolved, while in Navicula it persists and remains most inti-
mately connected with the daughter-ceU.

" The newly-formed parts of the cell- coat facing together in the division
are, in the Diatomese, and still more clearly in the Desmidiese, perfectly smooth
and even for some time after their production ; it is subsequently that they
obtain the often very considerable tubercles and spines, consisting principally
of cellulose. The same applies to the processes upon the outer integimient of the
spores of Euastra, Cosniaria and Staurastra produced in the conjugation. These
phenomena, as also the autumnal secretion of jeUy by many of the Desmidiese,
desei've more notice than they have hitherto attracted in connexion with the
theory of the life of the vegetable cell. Still more remarkable behaviour is
displayed by the cell-coat of an organism which I refer only doubtfully to
the Desmidieae. In many pools about Leipsic, in which Desmidiete aboimdcd,
occuiTed large, accurately spherical, thick-walled cells, some as much as -05
millim. in diameter, rich in chlorophyll, which not only Hned the internal wall
as a connected granular layer, but — as in many Desmidiese — fonned groups,
distributed, in the interior of the cell, in a system of radially-aiTanged plates,
which presented a stellate appearance when seen from the side. It would
be no great stretch of imagination to regard these cells as the conjugation-
spores of a large Desmidiean. But these spores are all spiny, with, the single
exception of those of XanthicUum armatum. This veiy sti-iking form occiu-s
but rarely with us, having hitherto been found only in a single locality, while
these globules are as common as they are abundant, and are often found in
great numbers in forest pools, which harbour, in addition to them, only very
small Desmidieee. But such a supposition is still more decidedly negatived
by the circumstance that the cells in question are sometimes found chvidinc:
into two. This renders it in the highest degree probable that they are inde-
pendent organisms — Desmidiese -ndthout a central constriction, which mny
form the commencement of a series of fonns terminating in Micrasterias.

" These cells frequently appear suiTounded by a wider coat, inside wliich the
coll then floats freely, enclosed by its own closely-investing coat. Several
such empty coats arc often met with, even as many as six sticking one inside

OF THE DI.VTOMEiE.

G9

another. Close investigation shows that the broader empty coats have an
orifice, towards the border of which the membrane grows gradually thinner.
These holes have not the aspect of perforations of the outer walls thi-ough
external injury ; they rather resemble the orifices of the walls of Cladophora,
through which the swai-ming-spores escape. It might be conjectured that
the plant multiplied by swarming-spores, and that solitaiy ones becoming
developed inside the empty coat of the mother-cell gave rise to that appear-
ance; but this is contradicted by the great frequency of their occiu-rence,
as also by the circumstance that we never find a number of green cells inside
one cell-coat. It is more probable that the contents of the cell contract, and
become coated with a new membrane, when the old one is perforated, — by
unknown causes, which perhaps lie in the course of development of the
species.

" If we seek to bring the phenomena introductory to vegetative cell-mul-
tiplication under one point of view with the preparations for conjugation, we
find that, in the Desmidieas, iu both cases a new membrane is formed around
the total contents of the ceU, wliich indeed lies close upon the old coat at all
points, but by no means adhei'es to it, as we are accustomed to conceive of
the so-called layers of thickening of the ceU-waU. The growth of the young
membrane cracks the stronger old one — ^in vegetative cell-multiplication
always in an annular form, in conjugation, mostly in a one-sided manner,
with a valve-hke slit (ffi/alotheca dissiliens ; Glosterium). At this stage
first occurs a distinction between the two processes of develoj^ment, — the
formation of a septum taking place in ceU-division, while in conjugation the
protruding part of the young membrane continues to enlarge outwards,
without, in many cases, any separation of the contents into two halves taking
place. The younger, innennost layer of membrane remains with that portion
lining the old ceU-coat, sticking whoUy in this in Hyalotheca, Bambusina,
Cosmarium. ■ But even in individuals of species of the last genus it sometimes
occurs, in Tetmemorus and Olosteriiim (e. g. C. acutum) as a rule (although by
; no means without exception), that the ends of the connected inner coats of
I the conjugating cells draw themselves out of the cast-off" shells of the mother-
i cells, in extreme cases entirely ; so that the cell originating by the blending
of the internal coats of two individuals (inside which the spore is formed)
i becomes capable of being rounded off into a sphere.

" Both the ceU-division and the preparation for conjugation of Zygnomeaj
'. are distinguished from the processes in Desmidiese by the circimistance that
I in the former the wall of the oldest cells grows in its entire mass, and does

■ not allow the youmger layers of membrane to protrude tkrough fissures or
'■■ slits.

" In the Diatomese, lastly, the division into two, like the conjugation, takes
! place, seemingly, in aU cases, through and after a preparatory contraction of
I the contents or separate portions of the contents of the cells ; and in not a
I few cases the conjugation takes place during, and is accompanied by, division
of the contracted contents into two portions. What import for the life of the
•species has the conjugation of the Zygnemca;, Desmidieae, Palmcllete (Pal-
imor/loea), and Dcsmidieaj? Our knowledge of the race of Alga3, so iraport-

■ antly advanced by the labours of Pringsheim and Cohn, should allow a more
I positive answer to this question than that inquirer, to whom the study owes
I most briUiant acquisitions, is inclined to give. The idea of sexuality of tlie
1 lower Alga3 depends principally upon the perfectly justifiable, but still only
. analogical conclusions which, starting from tlic obsei-vations made during a

■ century on the Phanerogamia, have advanced, through the intermediation of
I those, lees numerous, on the Vascular Cry|)togamia and Muscincfe, and the

70 GENEEAL niSTOBY OF THE INFTJSOEIA.

I

facts established in Facits by experiment of aitificial separation or irnion of
the sexes, to the (Edogonia, Vaucheria, Splmroplea and Volvox. Pringsheim's
declaration, that physiological questions of such a kind as the necessity of the
action of the fecundating matter in generation can only be certainly decided
by the observation of mor^ihological processes, -will not be adopted. Expe-
liment has long ago proved the existence of sexes in the Phanerogamia,
before the penetration of the pollen-tube into the ovule, and its relation to
the germinal vesicle, had been made out,— observations which that theory
really no longer required for the establishment of its main question. And
if, among so many confirmatory experiments, a few negative results present
themselves, in what branch of human knowledge do we not meet with similar
phenomena ? The general rules of evidence hold good in such cases.

" The same analogies, then, which lead us to recognize a fecundation in
the penetration of the spermatic body of CEclogonium into the mother-cell of
the spore, in the mixture of that body with the contracted contents of the
mother-cell of the spore (with Pringsheim's ' fecundation-globule '), must
necessai-ily lead us to regard conjugation as a fecundation. It is distinguished
from the process in CEdogonium only by the fact that the portions of cell-
contents which become blended into one cell are of equal size, and that there
is not one of them provided with apparatus by means of which, like the
spermatic body of CEdogonium by its cilia, it is moved onward until it reaches
the cell to be fecundated, — both points, evidently, of no essential importance.

" The sporangial frustiiles differ in general fi'om the parent forms not merely
in size, but also in the number of striae or of other markings, and to some
slight degree in outline. Such variation, M. Thuret contends, proves the phe-
nomenon of conjugation to be, not a true mode of reproduction, but only ' a
second mode of multiplication of fmstules, very curious and very abnormal.'

" In the immatiu-e condition, we are informed by Mr. Thwaites, it happens
that the sporangia in many species resemble in general characters the mature
frustules of another species or even of an allied genus. Thus the sporangia
of Gomphonema minutissimum (XI. 17) and of G. dichotomum have a close
resemblance to the frustules of Cocconema. On the other hand, in some genera,
as in Cocconema, the sjjorangia take on at once the exact characters of the
ordinary frustules, from which they differ only in their exceeding that of the
majority of the latter in dimensions.

" When a sporangiiim in a transitional condition is like the fnistule of another
genus, we are assisted in distinguishing its true nat\ire and affinity, oftentimes,
by the persistence of the mucus diffased around it ; or by continued observa-
tion we may witness its assimiption iiltimately of its true specific characters,
including the development of its pedicle or stalk, where the possession of
such an organ is a characteristic (as in Gomphonevia)."

The above fact suggests it as very probable that transitional forms have
been described as particular species, or located in wrong genera. Thus Mr.
Thwaites thinks that Kiitzing's Epithemia vertagus is no other than the
sporangium of Eunotia turgida, and also that the enlarged frustules of the
Melosirece, which that same writer had conjectiu-ally regarded as reproductive
bodies, are in fact the sporangial product of conjugation, and give rise to
a chain of frustiiles larger than those from which they had themselves
originated.

The subsequent histoiy of the sporangial fmstules on being matiired is
not satisfactorily made out. Prof Smith has the following on the question
(J. M. S. 1855, p. 131) : — " The ordinary Diatomaceous fnistule seems to owe
its production to the protoplasmic contents of the sporangial fnistule formed
by the process of conjugation. These sporangia, like the seeds of higher

OP THE BlATOMEiE.

71

plants, often remain for a long period dormant, and are borne about by cur-
rents or become imbedded in the mud of the waters in which they have been
produced, until the circumstances necessary to their development concur to
call them iuto activity. At such times their sHicious epiderms open to per-
mit the escape of the contained endochrome, which is resolved into a myriad
of embryonic frustules ; these either remain free or suiTound themselves with
mucus, foi-ming a pellicle or stratimi, and in a definite but unascertained
period reach the mature fonn of the ordinary frustule," when their fui'ther
growth appears almost entirely aiTCsted by the production of the silicious
coat, and when multiplication by self-division provides for the continuation of
individual life. To continue the quotation, " The size of the mature fi-ustule
before self-division commences is, however, dependent upon the idiosyncrasy
of the embryo, or upon the circumstances in which its embryonic growth takes
place ; consequently a very conspicuous diversity in their relative magnitudes
may be usually noticed in any large aggregation of individuals, or in the same
species collected in different locahties."

The behef that the contents of the sporangia! frustules resolve themselves
into a ' brood' of Diatoms, having the same form and specific characters as
the original parent-cells. Prof. Smith establishes by the following observations
made by himself {Synopsis, vol. ii. p. xv) : — " In the gathering of Cocconema
Cistula made in April 1852, which contained numerous instances of the con-
jugating process, I observed the frequent occurrence of cysts enclosing minute
bodies variable in their number and size, and many of which had the outline
and markings of the surrounding forms and were obviously young frastules of
the Cocconema. It would appear that the production of the yoimg frastules
is preceded by the separation and throwing off of the sihcious valves of the
sporangium and the constriction or enlargement of its piimordial utricle,
according to the number of young frustules originating in its protoplasmic
contents. In this gathering, forms of every size, intermediate between the
minutest frustule in the cyst and the ordinary frustules engaged in the
conjugating process, were easily to be detected ; and the conclusion was
inevitable, that the cysts and their contents were sporangia of the species
with which they were associated, and indicated the several stages of the
reproductive process."

Again, in a gathering of Synedra radians, although not found at the
time in a congregating state, yet the appearance of the cysts and of their
contents was equally characteristic of the reproductive process. That such
a " cystoid condition is one stage in the normal development of its reproduc-
tion," a subsequent examination in a distant locahty satisfied him.

The prosecution of this inquiry into the final changes of the sporangial
frustules is seriously impeded by the dissolution of the investing mucus and
the consequent dispersion of the reproductive bodies.

Thirty-two species of the Diatomca3 have been observed in the act of con-
jugation, belonging to the genera Epithemia, Cocconeis, Cocconema, Cymbetta,
Cyclotella, Gomphonema, Himantidium, Achnanthes, Bhahdonema, Melosira,
Navicula, Siirirella, Ampliora, Orthosira, Encyonema, CoUetonema, and ScJiizo-
nema. On this paucity compared -with the number of known genera, Prof.
Smith has the following explanatory remarks {Synops. n. p. xi) : — "One reason
for the paucity of observations on this process in the Diatomere is no doubt to
be found in the changes which usually take place in the condition of these
organisms at this period of their existence. During conjugation the proo-ress
of self-division is aiTcsted, the general mucous envelope or stratum produced
dunng self-division is dissolved, and the conjugating paira of fnistules become
detached from the onginal mass ; they are thus more readily borne away and

72

GENEfiAL HISTOllY OF TUE INFTJSOBIA,

dispersed by tlio surrounding currents or the movements of worms and in-
sects, and their detection becomes in consequence more casual and difficult.
By far the greater number of the species I have mentioned belong to those
genera whose fi-ustules are adherent, or attached by stipes to foreign bodies,
or which form continuous filaments or aggregated frondose expansions. Not
more than four, viz. Oydotella Kutzingiana, Navicula firma, Amphora ovalis,
and Cymhella Pediculus, are to be regarded as free fonns : the reason I have
just given will account for this circumstance ; and the larger propoilion of
adherent or frondose species detected in conjugation may doubtless be ascribed
to the firmer position conferred upon such forms by the presence of these
accessory methods of attachment and adhesion, while the filaraentous species,
being usually aggregated in considerable masses or entangled amidst the
branches of the larger Algce, are also less liable to dispersion."

Another mode of development, first pointed out by Mr. Ralfs in his early
contributions to the histoiy of the Diatomeae {A. N. H. 1843), by an internal
gemmation or j^roduction of cells approaching in physiological features to
self-division, appears to prevail in at least some instances. It is alluded to by
Prof. Smith, when speaking of the Meridion circulare {op. cit. 7). He met with
a variety of fiiistules, which upon a close examination, especially in a Hving
state, led him to the conviction " that the appearance of a double wall of silex
is owing to the formation within the original fi-ustule of a second perfect cell,
instead of the usual mode of division by which the origiual fnistule is divided
into two half -new cells .... In the present case, the central veseicle or cyto-
blast becomes enlarged without division, and secretes on its extension two
new valves, which are pushed outwards until they He in close approximation
with the original valves. This process is not always repeated ; the usual mode
of self-division again reciu's, and two valves are formed in the interior of
this new cell according to the normal method. . . .This unusual method of
development is not, however, sufficiently constant to warrant the separation
of such frustules from the species in which it occurs, perhaps hardly sufficient
to constitute a variety, as frustules in both the ordinary and abnoiTnal states
may be met with in the same gathering and even in the same filament."

Himantidium Soleirolii is another species producing internal cells, which
Prof. Smith quoted, remarking that he had no doubt it is merely an accidental
modification of cell-growth, since, in the same filament, cells thus formed may
be frequently found along mth others foUowing the nonnal mode of self-divi-
sion. In Odontidium anomalum, this variety is in fact the usual condition
of the frustules, and the ordinary mode of self-division is but rarely to be
met -with. A remarkable instance of this abnormal development presented
itself to Prof. Smith in Achnanthes snbsessilis, in wliich " the formation of a
cell interior to the original one had proceeded thi-ough sevend successive
stages, and the result is a compound frustule, consisting of the mother-cell
and a number of included cells, each successive development being embraced
by the others previously formed."

Mr. Ralfs has recently (J. M. S. 1857, p. 14) recun-cd to the subject of tliis
plan of reproduction, and has found himself obliged to differ fi-om Prof. Smith
in some particulars. He writes : " Although it is true that ' we frequently
find in the same filament cells thus formed, and othera foUowing the nonnal
mode of growth,' as I formerly showed, yet I cannot agree to Prof. Smith's
statement under liimantklium Soleirolii, that ' there is no doubt of its being
merely an accidental modlfieation of ceU-growth.' On the contrarj-, I beheve
it to be a reproductive state of the species, and consequently to have a definite
and important part in their economy.

" For several years I have attentively watched the circumstances connected

\

OF THE DIATOMEiE.

73

■ndth the formation of these inner cells in Himantidium undulatum, by
gathering specimens at shoi-t intei-vals. Dnriag great part of the -winter, the
filaments increase in bulk, by repeated division of the frustules, untU they
form large masses, filling the ditches ; at length the inner cells make their
appearance, at fii'st spaiingly ; but as spiing advances, it is difficult, in many
situations, to obtain a filament Tvithoiit them. I have found that when these
become abimdant, the filaments cease to grow, and the entii-e mass soon breaks
up and disappears. The same thing happens in the other species of Himan-
tidium, and in Meridion.

" I do not find that the inner cell commences in the centre and pushes its
valves outn^ai-ds, as stated by Prof. Smith. Were this the case, the internal
matter also would necessarily be pushed outwards by the advancing valves,
and thus condensed between them and the walls of the frastule. On the
contrary, in the Himantidium the internal matter, before nearly fluid, collects
within the new cell, becomes dense and more granular, and the new walls are
formed round it in the sitiTation they are to occupy, leaving an empty space
between them and the walls of the frustule.

" The alteration and condensation of the colouring matter, and the ap-
pearance, or at least great increase of vesicles, have a strong resemblance to
what takes place previous to the formation of sporangia, the completion of
which, as in this case, usually preludes the death and disappearance of the
mass.

" As in most acknowledged sporangia, the cell thus formed always tends
to assume an oval or orbicular form. It, however, is very frequently, and
perhaps generally, divided in halves, as in the fission of the frustules, so that
the oval seems made up of two neighboimng frustules ; but this is not the
case, as may readily be ascertained by noticing the marginal puncta of the
original frustule.

" Do these newly- constituted cells ever continue to divide, as Prof. Smith
supposes ? I beheve not ; at least I have never seen a specimen in which
the semi-elliptic portions were separated by the interposition of other valves
resembhng either themselves or those of the ordinary fiiistule. For my o^vn
part, I have been unable to trace the species after the formation of these cells,
owing to the qiiickly succeeding disappearance of the mass. If, indeed, this
renewed division does occui', the resemblance to what takes place in the
sporangia of some species of Melosira would be increased.

" Prof. Smith, in his most interesting and valuable account of the * Repro-
duction in the Diatomacese,' enumerates foiu" modes in which sporangia are
fonned. The third is thus defined : —

" ' The valves of a single frustule separate ; the contents, set free, rapidly
increase in buUi, and finally become condensed into a single sporangium.'

" As far as regards the Melosira varians, the only one in this group which
I have had an opportunity of noticing, I believe the process is essentially the
same as in the examples already described. The only diff'crcnce is, that the
new-formed cell being inflated, and much larger than the original frustule,
the valves of the fnistule must necessarily be cither mptured or pushed apart
by the increasing growth of the sporangium, and the latter alternative happens.

" I have seen no specimen of Mr. Brightwcll's Clicetoceros Wighamii, but
from his figures I bcHcve the goniothecia-like bodies constitute another
example of tlic formation of internal cells.

" I have said that I consider these internal cells sporangia, and cssentiaUy
of the same nature as the inflated ones of Melosira variam. At the same
time we .should not forget that Mr. Thwaitcs discovered the Himantidium
pectmah in a truly conjugated state, and that it is contrary to our experience

74

GENERAL HISTOHT OJ? THE INFtJSOEIA.

of the economy of nature that the same result should be obtained in the same
species in two different ways."

M. Focko has satisfied himself of the rej^roduction of some species of Navi-
culce (A. N. H. 1855, 237) by a strange complication of the phenomena of
" alternation of generation" and conjugation. Navicula hifrons, for example,
forms, he says, by the spontaneoiLS fission of its internal substance, spherical
bodies which, like gemmules, give rise to Surirella microcora. These by
conjugation produce N. splendida, which gives rise to N. hifrons by the same
process. This last act of gemmation has been obsei-ved by the author in aU
its phases. He saw two specimens of N. splendida, enveloped in a soi't of
mucosity, open and evacuate the whole of their contents, which sei-ved to form
a N. bifroiis. The production of the reproductive bodies by the latter wa.s
also obsei-ved ; but their development into Surirella microcora, and the pro-
duction of sjplendida by conjugation, rest solely on the inductions of the
author.

These facts require revision and confirmation, but they are, nevertheless,
worthy of the attention of observers, and appear to point to phenomena quite
as singular as those which have been revealed to us within the last few years
by the study of the reproduction of so many of the lower animals. They, in
fact, present in a manner the converse of the phenomena exhibited in the
ordinary alternation of generation, as several germs or eggs are necessary for
the production of the last individual of the cycle.

Kiitzing has surmised the existence of another mode of development, viz.
by germs or spores prepared from the gonimic contents of the fnistules. This
method of propagation was indeed comprehended in Ehrenberg's doctrine that
much of the granular contents were ova ; an hypothesis started rather to biing
the structure of the Diatomese in accordance with the generally assumed poly-
gastric organization, than to explain any observed phenomena, comphcated as
it also was with other suppositions of fecundating male glands or seminal
vesicles and a sexual discharging orifice.

Eabenhorst (SUssivasser-Diatom. p. 3) has followed up Kiitzing's suggestion,
and afiii-ms that the fnistules of Diatomeae swell up in a vesicular manner
and become filled with a greater or less number of cells, which at first have
an irregular figure, but subsequently assume a regular oval shape. This
having happened, the cells move in a current from right to left within the
cavity of the parent- ceU, which by-and-by sphts open and emits its progeny,
each of which has, at an anterior clear space, two long projecting cilia. For a
very short time these germs enjoy a swarming movement, and afterwards, on
becoming stationary, attain with extreme rapidity, or even sm-jjass, the size of
the parent-cell, which is itself destroyed in the act. This plan of reproduc-
tion by the development of a brood of young organisms within a parent-ceU,
or, in more technical terms, this fonnation of active gonidia (microgonidia),
prevails ia many of the lower Alga3, and consequently has no d-priori argu-
ment against it. However, as Prof. Smith remarks, " Its occurrence in the
Diatomeae cannot be received as estabhshcd without fm-thcr obscrs-ation and
a more careful record of the phenomena attending its progress" (op. cit.
vol. ii. p. xvii).

Eabenhorst has illustrated this mode of development in only one species of
Melosira, although he puts it forward in a general manner as if tnie of all
the Diatomeaj. Indeed it occiu's to us that it is not a special and othcndse
unobsei-ved process of reproduction, but merely that variety of the act of con-
jugation dcsciibed by Mr. Thwaitcs in the genus Melosira, in which a change
in the endochromc of ii .single fnistule, attended by an increase of contents
and a consequent enlargement — such as is intimated in llabenhoi-st's account —

OF THE DIATOMEiE.

75

converts it into a sporangium. Beyond tHs stage, Mr. Tliwaitcs docs not
appear to have foUowed the sporangial frustule so generated ; but, assuming
the correctness of Prof. Smith's hypothesis of the generation and subsequent
evolution of numerous minute frustulcs within it, do we not find a precisely
analogous phenomenon with that which Eabenhorst represents as an addi-
tional mode of propagation, or with what Focke (see preceding page) describes
as the foi-mation of gemmules out of the internal substance, and theii- sub-
sequent discharge? The supplementaiy phenomenon of alternation with
change of specific foim, included in the statement of the latter observer, even
if confii-med, will not affect the general analogy presumed. _

Habitats. — Appearance in masses, abundance, geographical distribution.
— Fossil Diatomece. — Existence in the atmosphere. — Practical lises and appli-
cations of the Diatomece.— The habitats and the distribution of the DiatomeiS,
both in time and space, are the most extensive, various, and wide, 'of all
organic beings. In fresh, in salt, and in brackish waters they are alike found ;
they exist abundantly in a Hving state about the roots of plants and diffused
in moist earth ; they are also to be met with in the dust of the atmosphere
and in meteoric products. They are, in fine, inhabitants of earth, a,ir, and
water. When no longer ahve, their silicious skeletons preserve their form
and constant characters, uninjured by most of the causes which obliterate
the remains of other Hving beings. They are so preserved in most of the
rocks above the oldest primary — in aU, indeed, in which intense heat has not
operated to fuse sUica into a molten mass. At the present day they are
ejected from the bowels of the earth in the lava, ciuders, and ashes of vol-
canos, and are borne about by the winds from one continent to another in
showers of dust.

In respect of habitat, the Diatomeas are divisible iato marine and fresh-
water species ; some indeed are common to both fresh and salt water, or
exist in brackish water. The following account of the habitats of Diatomeee,
illustrated by reference to particular examples, is from the experienced pen
of Mr. Ralfs, who has supphed us with it : —

" The Diatomeffi may be obtained at all seasons of the year, but are most
plentiful in spring and summer, many of them indeed beiug limited to that
period ; thus the species of Micromega and Schizonema are, with few excep-
tions, in perfection only in May and June, when they are met with in shel-
tered situations, forming wide patches on the ground and on the flat surfaces
of rocks exposed at ebb-tide. About the end of May the Enteromorpha
compressa, so common on our shores, often seems as if faded at the end ; this
appearance is frequently accompanied by the presence of Gh-ammonema Jur-
gensii, which is easily recognized by its slippery feel, when from its pale
colour it would otherwise escape detection.

" At aU seasons of the year, the smaller and more slender Algae, marine
and freshwater, as soon as they attain maturity, become almost invariably
covered with parasitic Diatomea3, which impart to them a brownish colom*.
In this way we obtain species of Oocconeis, Achnanthes, Striatella, Tabellaria,
Orammatophora, Isthmia, Gomphonema, Podosphenia, Rhipidophora, and
Synedra. On the contrary, Amphitetras and Biddidphia prefer the muddy
crevices iu the sheltered sides of perpendicular rocks.

" In salt marshes we may expect to find the Achnanthes sidmssilis on the
slender filaments of Enteromorpha, but so sparingly as hardly to discolour
them. The species of Epiihemia are parasitic on Gladophora, both in brackish
and in freshwater pools. The Melosirm are common in marshes, especially at
the mouths of large rivers, where they form Conferva-Iiko brownish masses.

" Many of the unattached Diatomcaj are produced in dark brown patches

^6

OENEHAL HISTORY OF THE INFUSOHIA,

at the bottom of pools, or on the surface of mud ; the freshwater species
often by the road-side ; the marine forms usually near high-water mark. Am-
phipleura injlexa and A. scalaris congregate, in large brown stains or spots,
on the muddy sides of rocks, whilst other species, for instance Campylodiscus,
and Coscinodiscus concinnus, form similar collections, but prefer more shady
situations.

" The sides of ditches in brackish marshes are very proMc, especially after
spring-tides, and in situations not again covered until the next high-tides.
"We may expect to gather in such places species of Surirella, Navicula, Pleu-
rosigma, Ceratoneis, Amphiprora, Ampliora, &c. The soil about the roots of
rushes and of other plants inhabiting salt marshes often afford interesting
forms, but seldom in abundance. We find there species of Coscmodisais and
of Zygoceros ; but such are obtained more abundantly fi'om the mud or from
the washings of bivalve shells brought up from deep water or collected at the
mouths of rivers. Oyster-beds are in general productive. The Bacillaria
paradoxa inhabits ditches in which the water is nearly fresh, and is frequently
obtainable from the scum driven from the surface to the banks.

" Pew Diatomese are peculiarly autumnal ; we have, however, gathered
Homoeodadia Martiana, Berlceleya fragilis, DicJcieia pinnata, and StriaUUa
unipunctata, chiefly at that season.

" On warm summer days, Diatomeas, with various microscopic Algse and
Pungi, rise to the surface of water by the disengaged oxygen gas still ad-
hering to them and buoying them up, and there form a deHcate film or a
scum, and at times even a layer of considerable thickness. Such collections
are rich in species of Navicula, Gymbella, Surirella, and Synedm. When an
entangled larger mass is formed, there is usually one prevailing species.
Specimens of Fragilaria are generally found on decaying wood or leaves,
or amongst Conferva3 difiused in the water. From the drainings of Spliagnum
may often be obtained Synedra biceps and various species of Himantidium,
Boggy soil, especially when situated on a slope, afibrds various species of Epi-
themia and Navicula ; so likcAvise does the soft matter on rocks on which water
constantly trickles. Washings from oysters and the refuse raised by trawlers
are usually rich in spheres of Coscinodiscus, Actinoptychus, Pleurosigma, Di-
ploneis, Navicula, Dictyoclia, &c. The same kind of washings from sheltered
harbours give Surirella fastuosa, Aidiscus sculptus, together with species of
Gampylodiscus, Triceratimn, &c. Washings of corallines are likewise some-
times productive."

Mr. Norman supplies us mth the following hints : — " The most interesting
forms occur in salt water, especially in shallow lagoons, saltwater marshes,
estuaries of rivers, pools left by the tide, &c. Their presence in any abun-
dance is shown by the colour they impart to the aquatic plants they are
attached to ; or when found on mud, by the yeUo-n-ish-brown film they form
on the surface, and which, if removed with a spoon without distui-bing the
mud, wiU be found a vciy pure deposit.

Such collections are best put at once in bottles, or even partially dried
and wrapped in pieces of paper or tin-foil. Wlien placed in bottles, a few
drops of spirit are advantageously added. In all cases it is essential that the
locality Avhence obtained should be plainly written on each package. Capital
gatherings arc obtainable by cai-efully scraping the broAvnish-colourcd layer
from mooring-posts, or the piles of wharfs or jetties.

" In clear running ditches, the plants and stones have often long streamers
of yeUowish-brown slimy matters adliering to them, generally composed almost
whoUy of filamentary species. The layers of Diatomaccous fi'onds on the
surface of mud arc often covered with bcad-hkc bubbles of oxygen, which

OF THE DIATOMTIJn.

77

from time to time rises to the smface of the water and carries up with it
some of the deposit in the form of a scum, which gets blown to lecAvard, and
may be readily collected from the edge of the pond quite free from particles
of mud and other impvuities.

" Good and rare specimens have been obtained from the stomachs of Ho-
lothmidfe and other Mollusca which inhabit deep water, and are often thrown
on shore after severe gales of wind. These animals may be merely dried and
presei-ved just as found, and the contents of the stomach obtained afterwards
by (hssection. Shells and stones, covered with seaweed, &c., from deep water,
also afford most interesting and little-known forms. The rougher these are,
the better (they ought by no means to be cleaned). Deep-sea soundings
(especially those from great depths) should be preserved ; for they are often
exclusively Diatomaceous,

" Very rare species have often been formed in immense quantities in the
arctic and antarctic regions by melting the ' pancake ice,' rendered brownish
by these microscopic shells. The sea is also often observed discoloured with
brownish patches, which should be collected, and the water filtered through
blotting-paper or cotton wool : the residuum will frequently tiun out to be
composed of Diatomefe. It is also highly interesting to collect and examine
the impalpable dust which occasionally falls into the folds of the sails of ships
at sea."

Scallops and other Mollusca often contain rich and rare collections in their
stomachs. In Ascidia (e. g. Phallusia sulcata, Ascidia mentula) Mr. Norman
and the Eev. R. CressweU found an abundant source. Mr. Norman adds, in
a further note kindly sent us — " The Ascidians, whose stomachs are almost
always so loaded with Diatotaiaceous frustules, are to be found abundantly
on the shells of oysters dredged 'in deep water, and readily procurable from
the trawlers.

" The Saljpce (found so abundantly floating on the surface of the sea in warm
latitudes) afford very pure gatherings. The roots of the various species of
mangrove, growing in the dense swamps of rivers and estiiaries in the tropical
regions of Afiica, AustraUa, and the Eastern Ai'chipelago, are said to be fi'e-
quently covered with a brownish mucous shme very rich in Diatomeee. I
have also obtained very pure gatherings from the roots of the Dutch rushes,
as imported, and from the Zostera marina from the Baltic, used for stuffing
beds, &c., by upholsterers. Stones, moreover, brought as ballast fi-om abroad,
wiU amply pay the diligent collector by yielding foreign and perhaps rare
species. The roots of aquatic plants from tropical countries, stored in her-
baria, would, if properly examined, yield many interesting forms of Diatoms."

Indeed we may add, generally, that the roots of land plants, particularly
of mosses, lichens, &c., growing around trees on the ground, or upon them,
are fniitful in Diatomcaj, and, in fact, of some of the rarer fomis. In the
Number of the Microscopical Transactiom just published (July 1858, p. 79),
Col. Baddeley notes the occurrence of Diatoms in considerable numbei-s iri
the Noctiluca miliaris. They are the chief constituents of a mass of dark
matter near the nucleus, and lie in the so-called vacuoles, into which they
enter from the mouth. This occurrence suggests an easy method of obtaining
different marine species of Diatometc in their natural state, often alive, and
with their endochrome perfect. The Colonel cUscovered in this way several
rarer species, and gives a Hst of nearly 50 which he identified, besides not a
few forms of whose trae name he was uncertain. To extract the Diatoma
ceous mass from the interior of the Noctilmce, Col. Baddeley recommends
that the seawater and its hving freight bo poured, on arriving homo in a
white hand-basin, and be let stand for an hour or two. '< Tliis rough treat-

78

GENERAL HISTOET OF THE INFUSOUIA.

ment causes these creatures to disgorge their food ; and if, after an interval,
tlio water be carefully f)om'ed off, a sediment will be found at the bottom'
which will consist of Diatoms mixed with some refuse."

Dr. Donkin lately {T. M. S. 1858, p. 11) caUed attention to the occurrence
of that rare form, Syndendrium diadema, in the stomach of the lobster, and
in a subsequent paper {op. cit. p. 14) alludes to the abundant deposit of living
Diatoms upon the sands at the sea-side, in the following paragraph : —
" Professor Smith states that ' the shallow pools left by the retiring tide at
the mouths of oiu: larger rivers ' are the favourite habitat of marine species.
But such localities I have found not to be half so prolific in species a.s the
sands of still hays, on the shore, ivhere they are exposed by the reflux of the
tide, at a distance correspondinc/ with the half-tide margin. In these places,
where the sands are sloping towards the sea, and grooved out into smaU
fim-ows, filled with salt water oozing out from behind, the abundance of
Diatoms aggregated into a living mass imparts to the surface of the sand
different hues of chestnut and oHve, the difference of coloui- being due to
the nature of the species present. These coloured patches, it is interesting
to observe, are, during the sunshine, studded with numei-ous minute air-
bubbles, undoubtedly given off by the Diatoms themselves.

" To separate the Diatoms thus detected, from the surface of the sand, I
found to be impossible. I therefore seized hold of the nearest bivalve shell
which happened to lie in the way, and with this I carefully scooped up the
surface of the coloui-ed sand. This I emptied into a wide-mouthed, stoppered
bottle, capable of holding eight ounces, until half full ; the other half of the
bottle I filled up with salt water. I then shook the whole briskly and allowed
the bottle to stand for a short period. The sand, being composed entirely of
fine round grains of quartz and the minute fragments of shells, settled at the
bottom in a few seconds, leaving the Diatoms all suspended in the water
above, and forming by their abundance a chestnut-coloured cloud, but not
more than 1 part in 1000 of the whole sand collected. The coloured water
was then poured into another bottle, and formed the gathering, while the
sand was thrown away. The Diatoms, in their turn, were separated from the
superfluous water by subsidence, and brought home in l|-oz. bottles. In this
manner I soon found that any quantity could be collected in a pure and \m-
mixed condition, affording an excellent opportiinity of examining their living
forms, and one of which I availed myself on every occasion.

" After carefully examining materials collected in this way from various
parts of the beach, I detected not less than about 100 species, all these
strictly marine, and, with a few exceptions, each species in considerable
abundance."

The fact of Diatomea3 rendeiing themselves perceptible to common vision
by their excessive accumulation and the coloiu- they impart to water, is illus-
trated by the phenomenon of coloration of the sea recorded by Dr. Hooker,
also by the Melosira ochracea, which occurs in many, perhaps in all, cha-
lybeate waters, and also in peat water containing a small proportion of iron.
It is of the colour of iron rust, and in mineral springs, in which it abounds,
is often taken for precipitated oxide of iron. It covers eveiything under
water, but foi-ms so delicate and floccose a mass that the least motion dissi-
pates it. In the spring of the year this mass is composed of very delicate,
pale-yellow globules, which can bo easily separated from each other. They
unite together in rows like short chains, and produce an irregular gelatinous
felt or floccose substance. About summer, or in autumn, they become de-
veloped into more evidently articulated and stiff threads of a somewhat larger
diameter, but still form a complicated mass or web, and, either from adhering

OF THE DIATOMEJE.

79

to each other or to delicate Conferva;, appear branched. In the young con-
dition, when examined under shallow magnifiers, they resemble gelatine ; but
with a power of 300 diameters the flexible granules are discoverable, and,
with dextrous management, the little chains forming the felt or floccose
web can be made out. In summer, on the other hand, its structui'c can be
observed much more easily and distinctly. Early in spring the colom- is that
of a pale yellow ochre, but in summer that of an intense rusty red. Other
examples occur where a single species becomes tangible to the unaided senses ;
such are met with in the brown specks mentioned in the preceding account of
habitats formed by particular species upon the larger Algae and Confervas. So
the Goniphonema geminatum forms on rocks tirfts of a spongy texture and
brownish colom- when yoimg, but white afterwards. The Synedra Ulna often
produces a white incrustation on stones in rivers in summer ; and Fragilaria
and Odontidium are seen outstretched as dehcate brown filaments, several
feet in length, like many filiform Algae, from which, however, they differ by
breaking up so very readily, on the least distiirbing force, into their separate
joints. " Large numbers of Ehizoselenia " (writes Mr. BrightweU, J. M. S.
1858, p. 95) "have been detected in the stomachs of Salpce, and they have also
been observed floating free in the ocean in warm latitudes, their appearance
being that of httle confervoid flakes of exquisite dehcacy, but of a sufiicient
aggregation of filaments to be seen by the naked eye. The mass appeared
(probably from the endochrome) of a faint, evanescent, ochraceous colour."
Moreover, the frondose species generally attain an appreciable magnitude.
Thus Encyonenia prostratimi forms a tuft-hke stratum, — when recent, dark
brown, but when dried, of a dull green coloiu". Schizonema suhcolicerens grows
into tufts fi-om a quarter to half an inch or more high ; and 8. vulgare con-
stitutes a dark brown gelatinous stratum on stones in shallow water, fila-
ments simple "or nearly so in deep still water, and much branched filaments
in deep rapid streams.

Mr. Norman, of Hull, has most kindly famished us with the following
original observation on the growth of one species, the Campylodiscus cos-
tatus : — " In the early part of the spriag of 1856," he writes, " I made a
gathering of freshwater Diatomeae from the ' Spring IDitch,' Hull. Although
I met with a few odd fnistules of the species named, I did not consider it of
sufficient interest to boO. in acid for mountiag, and the phial containing them
was left in the window of my laboratory during the ensuing summer. Some
time in the autumn I had occasion to make use of this bottle, and was on the
point of throwing away the contents, when I noticed the sui-face of the de-
posit and the sides of the bottle to be covered with a dense brown growth of
Diatoms. On firrther examination I found an immense colony of Campylo-
discus, which gave by preparation some beautifully piu-e slides of tliis species.
In removing the upper layer I purposely left a few of the fiiistules in the
bottle, which was again placed in the window. These have again increased
to a great extent, and now (December 1857) they appear to thrive in perfect
health. Does not this occiuTence suggest an easy plan of procm-ing in a
pure state such forms as are rarely foimd together in any abundance ? "

Geographical Distribution.— Species of Diatomea3 are for the most part
distributed over a very wide geographical area. Some, indeed, would seem
cosmopolitan, whilst others are Umitcd to certain regions. Por instance the
Terpsinoe has not been discovered in Euro])e ; and Synedra Entomon is
reckoned by Ehi-enbcrg as peculiariy a South American production. This
author has given fuU force to this seeming fact, and employed it in the en-
deavom- to discover the origin and coui'se of meteoric dust, and also to arrive
at certain geological deductions. For example, he says {Monatsh Berlin

80

GENETIAL UISTOEY OF THE INFUSORIA.

AJcad. 1849), " Tho chain of rocky mountains traversing the continent of
North America, forms, with reference to the distiibution of Infusoria, a
stronger bai-rier between California and Oregon, and the rest of the continent,
than does the Pacific Ocean, with Chma, between the western plains of
North America and the region of Siberia. Thus, the United States, with
Mexico, never present any of the forms characteristic of Oregon and Cali-
fornia, whilst, on the other hand, the peculiar forms of these latter countries
are met with in Siberia. All this is remarkably confii-med in this, that the
gold region of the Sacramento, in the extent and abundance of its Infusorial
products, finds its parallel only in Siberia."

This presumed fact of limited geographical distribution is thus applied
by Ehrenberg in another paper {Monatsh. 1846) : — " The atmospheric dust
which, since 1830, has fallen in the Atlantic Ocean as far as 800 miles west
from Africa, on the Cape de Yerde Islands, and even in Malta and Genoa,
has been all of an ochre-yeUow colour, never grey like the dust seen in the
north of Africa, and consists of from -1-th to 1-rd of organic particles referable
to 90 species, the greater number of which ai'e of freshwater habit, and foimd
equally in the most widely separated regions named. This dust, even in
Genoa, whence it is carried by the Sii-occo wind, contains no characteristic
African forms, but, on the contrary, presents the Synedra Entomon, a deci-
dedly characteristic species of South America." From his observations on
this meteoric dust, Ehrenberg concludes that there is a cuiTcnt of air xiniting
Africa and America in the region of the trade winds, and occasionally directed
towards Europe. On the other hand, their wide diffusion is exemplified iu Dr.
Hooker's Report on the Diatomaceous vegetation of the Antarctic sea {Brit.
Assoc. 1847) : — " The genera and species of Diatomacete collected within the
Antarctic sea are not at all peculiar to those latitudes ; on the contrary, some
occur in every country between Spitzbergen and Victoria Land. Others, and
even some of these, have been recognized by Ehrenberg as occui'ring fossil
in both Americas, in the south of Europe and north of Africa, in Tripoli
stone and in volcanic ashes ejected both fi-om active and extinct volcanos,
whilst others again exist in the atmosphere overhanging the tropical At-
lantic."

Prof. Smith has the following remarks on cosmopolitan or very widely-
diflPused species {Synojps. ii. p. xxvii) : —

" Of fi-eshwatcr species frequent in the British Islands, the following seem
almost cosmopolitan, viz. Synedra radians, Pinmdaria viridis, PinnuJaria
horealis, and Gocconema lanceolatum. Gatherings from many localities in
Europe, from Smyrna and Ceylon, from the Sandwich Islands, New Zealand,
and New York, fi'om the loftiest accessible points of the Himalaya in Asia,
and the Andes in America, have supplied specimens of these forms.

" Navicula serians abound in all our moimtain bogs, and is equally common
in the marshes of Lapland and America.

" Epithemia gibba is an inhabitant of the Geysers of Iceland and the lakes
of Switzerland.

" The South Sea Islands supply Stauroneis acuta, and Ceylon Synedra
Ulna, whUe Stauroneis PJuenicenteron is equally abundant in Britain, Sicily,
and Nova Scotia.

" These notes of localities will give some idea of the wide distribution of
our fluviatile Diatomacete : more numerous gatherings woiild, no doubt,
greatly extend tho hst ; and the following circumstance vnW show how gene-
rally our commoner British forms are diffused throughout European localities
that have been carefully examined. During a torn- in Langucdoc and the
Auvergne in the spring of 1854, I made iipwards of forty gatherings from

OF XnK D1AT0.ME.E.

81

the rivers, streams, and lakes of the district I traversed. In tliesc I detected
130 species, and but one form not yet determined as indigenous to T3ritain.
If this be the case Avith a district much of whose Phanerogamous flora is so
different from our own, it bears out the view I have taken, that these or-
ganisms enjoy a range of distribution far more general than the higher orders
of plant-life.

" Nor is the distribution of marine species less notable for its extent and
uniformity. Coscinodlscus eccentricus and C. radiatus range from the shores of
Britain to those of South Africa. Grammatophora marina and O. macUenta are
found in almost every maiine gathering from the Arctic Ocean to the Maui-i-
tius. Stauroneis pulcheUa, Cocconeis Scutellum, and BiddidpMa pulchella are
equally abundant on the Em-opean, the ximerican, and the African coasts,
while lihabdonema Adrlaticum belies its name by its occim-ence in the Indian,
Atlantic, and Pacific Oceans. During the researches already mentioned, in the
South of France, I made several prolific gatherings on the shores of the Gulf
of Lyons; but, of 33 forms occurring in these, Hyalosira delicatida, Kiitz,,
was the only one not famihar to me as a British species."

The supposition that many species of Diatomeaa occupy a very limited geo-
graphical area, and that considerable numbers have, in course of ages, disap-
peared or become extinct, as many animal and vegetable organisms have done,
was thus ably examined by the lamented Dr. Gregory in a communication to
the Royal Society of Edinbui-gh, made in 185G (P/'oc. Boy. Soc. Edin. 185G-
T)?, p. 442). The subject of discussion is introduced in his notice of Na-
I'icida prcetexta, a form previously considered only fossil. " I have," he says,
selected this form because the bed in which it occurs fossil is the oldest in
which Ehrenberg has found any Diatoms. He has indeed found microscopic
organisms in the chalk, and even in older rocks, among A\'hich he mentions
the moimtain limestone and the SUruian greensand. But the forms in the
two latter rocks are not numerous, and, as well as those which abound in the
chalk, belong to the Foraminifera or to the Polycystina, not to the Diato-
macea .... In shor-t, I have no hesitation in saying, that I beUeve aU the forms
in the iEgiua clay-marl, which is the oldest Diatomaccous deposit yet de-
scribed, will be found Hving on our coast." The stratum at -<Egina belongs
either to the challv formation, or to the oldest tertiary or Eocene beds.

Dr. Gregory continues, " It may also be observed that, of aU the forms
figured by Ehrenberg from more recent strata, whether miocene, like the bed
on which the town of Eichmond (Virginia) is built, and several kinds of Bcrg-
mehl — or phocene, Hke other Berg-mehls or pohshing-slatcs, &e. — or still
more recent, the great majority are perfectly identical vnt\\ existing Diatoms.
Indeed, although many forms are stated in Ehrenberg's earliest writings to
be fossil only, and have been supposed to be extinct, the progress of obser-
vation is continually adding to the number of species which are found also in
the recent state. Thus, for example, the whole group of dentate Eunofia;,
which abound in the Lapland and Finland Bcrg-mohls, were long thought to
be only fossil ; but they have been nearly aU found in America, and I have
myseK seen several of them recent in this country. Eunotia triodon, lono'
supposed to be extinct, occurred scattered in many of tlie Scottish freshwater
: gathniings.

Talcing these facts into consideration, I am led to believe that Ave have no
evidence that any species of Diatom has become extinct, as so many species
and even genera and tril)es, of more highly organized beings have done. I
obscn-c that Mr. Brightwell expr(>s»cs a similar opinion in his valuable nnner
on ClupAoceros {J. M. S. iv. p. 105)." " ^ ^

Wherefore Dr. Gregoiy comes to the conclusion, that " the whole of the

0

82

OENEIUL niSTOllY OF THE INI^tTSOllIA.

species wliich occiu' fossil mil, ore long, l)e detected in the recent state. It
is at all events certain that a very large proportion of the Diatoms found in
the fossil state also occur in the living state, and that every day adds to their
number. There is at present no good evidence of the existence of Diatoms
earlier than the chalk, if so early. But we must not forget that the shells
of Diatoms appear to be altered by long contact with carbonate of lime, so
that they may have existed at one time in the chalk. We find them, how-
ever, in spite of the action of calcareous matter, in the recent chalk-marls of
Meudon and of Caltanisetta, which are rather more recent than the chalk,
and probably of about the age of the clay-marl of vEgina. If , as I believe,
no Diatoms have become extiuct, this may perhaps depend on their minute
size and extreme simphcity of stractxirc, which probably render them more
indifferent to climatic changes than moi-e highly organized and larger beings.
We have evidence, to a certain extent, that this is the case ; for by Ehren-
berg's figures it appears that, in gatherings of recent Diatoms from all parts
of the world, in every possible variety of climate, the majority of species are
identical with our own.

" Diatoms, therefore, are not materially affected by existing differences of
climate, and have probably been as little affected by the geological changes
which have occurred, at all events, since the period of the Eocene deposits."

Geological iMPOsTiiNCE of DiATOMEiE. — Fossil Accumulations. — Although
so exceedingly minute and apparently insignificant in comparison with the
animals and plants usually claiming our notice, yet, by their excessive multi-
plication and accumulation, they assume even a greater importance, in the
physical history of the earth, than the largest trees or animals with which
we are acquainted. This lesson is taught us by living examples of these
microscopic beings constituting appreciable masses, and by innumerable in-
stances where only the sUicious skeletons remain, in a fossil or semi-fossil
condition.

Ehrenberg thus illustrates their rapidity of production and accumulation.
" SUicious Infusoria," he says, "form, in stagnant waters duiing hot weather,
a porous layer of the thickness of the hand. Although more than 100,000,000
weigh har(Uy a grain, one may in the course of half-an-hour collect a pound
weight of them ; hence it will no longer seem impossible that they may bmld
up rocks. However, one of the most striking examples of the operation of
Diatomese as a physical agency on a large scale, is afforded by Dr. Hooker's
observations addressed to the British Association (Beport, 1847). He says —
" The waters, and especially the newly-foiTned ice of the whole Antarctic
Ocean, between the parallels of 60° and 80° south, abound in Diatomace«, — so
numerous as to stain the sea eveiywhere of a pale ochi'cous brown, the surface
having that colour as far as the eye can reach from the sliip. Though pecu-
liarly abundant in the Icy Sea, these plants are probably uniformly dispersed
over the whole ocean, but, being invisible from their minuteness, can only be
recognized when washed together in masses, and contrasted with some opake
substance. They were invariably found in the stomachs of Salpaj and of other
sea animals, in all latitudes between that of the tropic and the highest parallel
attained in the Antarctic expedition. Their death and decomposition produce
a submarine deposit or bank of vast dimensions, consisting mainly of their
silicious shields, intermixed with Infusoria and inorganic matter. Its position
is from the 76th to the 78th degree of south latitude, and occupies an area
400 miles long by 120 wide. The lead sometimes sank two feet in this pasty
deposit, and on examination showed the bottom made up in great measure of
the species now living on the surface. This deposit may be considered as
resting upon the shores of Victoria Land and of tlie Barriers, and hence on Iho

OV TUK DIATOJIEJ';.

83

submarine flanks of Mount Erebus, an active volcano 12,000 feet high. From
the fact that Diatomeoe and other organisms enter into the formation of
pumice and ashes of other volcanos, it is perhaps not unreasonable to con-
jecture that the subterranean and subaqueous forces, which keep Mount
Erebus in activity, may open a direct communication between tliis Diato-
maceous deposit and its volcanic fires. Moreover, this bank flanks the whole
length of Victoria Barrier, a glacier of ice 400 miles long, whose seaward
I edge floats in the ocean, whilst its landward extends in one continuous sweep
1 from the crater of Mount Erebus and other mountains of "Victoria Land to the
! sea. The progressive motion of such a glacier, and accumulation of snow on
its surface, must result in its interference with the deposit in question, which,
if ever raised above the surface of the ocean, would present a stratified bed
of rock which had been subjected to the most violent disturbances."

But instances of the abundance of sHicious organisms ia sea- or river-
bottoms are to be met wdth nearer home. Mr. Roper has explored the mud
of the Thames (J. M. S. 1854, p. 68) ; and he teUs us that, excluding the
coarse sand, nearly one-fourth of the finer part of the residuum is entirely
1 composed of the silicious valves of different species of DiatomcEE, — " marine
I forms prevailing." This writer also quotes the experience of Ehrenberg,
who, with respect to the mud of the Elbe, has established the remarkable
fact that at Gluckstadt, a distance of 40 miles, and even above Hamburg,
upwards of 80 miles above the mouth of the river, marine silicious- shelled
Infusoria were found alive, and their skeletons deposited in it in such abun-
dance, that at the former locality they form from one-quarter to one-thii'd of
the entii'e mass, and that the proportion is stiU about one-half that amoimt
at Hamburg, as far as the flood- tide extends. All his observations gave- a
i great predominance of marine over freshwater species, even when the salt
i taste of the water was no longer perceptible. His examination of the mud
of the Scheldt and Ems fiu-nished similar results, as did that of the marine
deposit in various Uttoral regions of the North Sea and Baltic.

Reverting to the Thames deposit, Mr. Roper expresses his belief that the
silicious sheUs " have a perceptible influence in the formation of shoals and
mud-banks in the bed of the river. . . .And the great abimdance and general
distribution of species serve to Ulustrate the occurrence of similar deposits
in a fossil state at localities now far removed, by alterations in the eartli's
surface, from the streams or harbours in which they were originally de-
posited.

" Another point worthy of attention is the influence of these organisms
in the fonnation of deltas at the mouths of large and slowly-flowin"-
rivers — such, for instance, as the Mississippi, in wliich the mean velocity of
the current at Ne'w Orleans is only about one mUc and a half per hour for
the whole body of water. Sir Charles Lyell, from experiments on the pro-
portion of sediment carried down by the river, has calculated that, taking tlie
area of the delta at 13,000 square miles, and the quantity of solid matter
brought down annually at 3,702,758,400 cubic feet, it must have taken G7,000
years for the wliole delta. Now, as the silicious frustules of the Diatomeje
are secreted from tlie water alone, and would most probably be extremoly
abundant in so sluggish a stream (especially as Prof. Bailey has found botli
marine and fresliwatcr species abundant in the rice-grounds), there can be
little doubt that, without taking tlie larger proportion noticed by Elirenbor"-
in the Elbe, even if it were considerably less, it would reduce the above
period by several thousand years ; and tlio same cause would probably applv
with equal force to tlie Ganges and Nile. Ehrenberg considered t.h'/l "I'f
Pillau. there are annually deposited from the water fi-om 7200 to \ \ oo(»

G 2

84

GKNURAL HISTORY OF THE INFUSOKIA.

cubic metres of fine microscopic organisms, which, in tlac course of a century,
■would give a cloi^sit of fi-ora 720,000 to 1,400,000 cubic metres of infusoi-y
rock or Tripoli stone."

Another fact exemplifying the Avidely pervading presence of silicious In-
fusoria was revealed by the experiments of Ehrenberg, viz. their existence
in a living state in moist earth beneath the surface, the only vital condition
necessary being a small quantity of raoistiu'e. The presence of their remains
at considerable depths in mud also is well exemplified by the experimental
borings made by Mr. Okeden {J. M. S. 1854, p. 26) at Neyland, a creek of
MiLford Haven, where deposits rich in Diatomaceous remains of maiine or
brackish and fresliwater character occurred at the depth of 20, 30, and
40 feet.

The preceding illustrations wiU suffice to show the active share taken by
the Diatomeas at the present day in the ever-occiu'ring changes of the earth's
siu'face ; others must now be adduced to exemplify their influence in the past
physical changes of the globe. These examples are so numerous, and, relative
to other phenomena, so important, that it is embarrassing to make a selection.
Ehrenberg is the most assiduous cultivator of this department of knowledge.
He has peraonally examined deposits collected fi-om almost every countiy of
the world, and described, with illustrative plates, the genera and species he
has encountered in them, in his recent large work the MiJa-ogeologie, 1855.
One of the most stiiking and, to his mind, unique instances of a Diatoma-
ceous deposit, formed at a remote or geological period, he has shown to exist
in North America, on the banks of the Colimibia River.

The river of Columbia, in its course at Place-du-Camp, runs between two
precipices 700 to 800 feet high, composed of porcelain-clay 500 feet thick,
covered over by a layer of compact basalt 100 feet thick, on wliich, again, some
volcanic deposits exist. The clay strata are of very fine grain, and vaiy in
colour ; some are as white as chalk. Dr. Bailey has shown, fi-om some por-
tions submitted to him by Col. Fremont, that tliis apparently argillaceous layer
is entirely composed of freshwater Infusoria. Its perfect purity from sand
shows that it is not a drift, but has been formed on the spot. By its immense
thickness of 500 feet, this layer of biolithic Tripoli far sm-passes any similar
layers elsoAvhere, which attain ordinaiily only one or two feet thickness,
although those of Lunebui'g and BiHn have a depth of 40 feet. Some beds
we also Icnow elsewhere having 70 feet ; yet such are not pure, but inter-
sected by strata of tufa or of other material.

A very pure Diatomaceous deposit has been met with by Dr. Gregory- in
the island of Mull, which when diy is almost wliitc, and much resembles
chalk, being light, pliable, and adherent to the fingers {T. M. S. 1853, p. 93),
and in composition hardly contains anything besides silicious organic remains
" for the most part entire, but Avith some fragments ; other portions which
are denser contain also many fragments of quartz of various sizes, aud vjust
numbers of comminuted fragments of loricfc." Prof. Smith (Si/uoj)s. vol. i.
p. xii) says — "Districts recovered from the sea, in the present or other
periods of the earth's histoiy, frequently contain myriads of such cxuriic
forming strata of considerable tbiclcness." Examples of this nature in our
own coimtrj' arc met with in " the ancient site of a mountain lake in the
neighbouriiood of Dolgelly, localities of a similar kind near Lough Islaiid-
Reavey in Down, and Lough Moiu-ne in Antrim." Mr. Okeden concludes,
from facts collected by borings in the mud of sonu> creeks and rivere of
South Wales, " that not the surfiice merely, but the whole mass of those
tidal deposits is penetrated by these minute and wondi-ous organisms, while,
from the fact of their being found at Neyland at a depth of 40 foot lielow tlio

OF THE DIATOME^.

85

present siu-fticc, and close upon the rock which forms tlie oiiginal bed of this
estuary, the mind is iiTCsistibly led to the conclusion that they have existed
there from the time when the waters fii'st rolled over the spot."

Berg-mehl, Tripoli, and other polishing-powders, the stratified deposits at
Bilin in Bohemia and iniEgina, and numerous others examined and reported
on by various microscopists might lihemse be adduced to demonstrate the
important pai-t played by these individually invisible beings, when accumu-
lated in countless myriads, in the construction of the earth's crust.

The Oolitic, and even some earUer metamorphic rocks, poi-phpitic rocks,
&c., are not wanting, according to Ehi-enberg, in species of Diatomeae ; but
in the Pliocene, Miocene, Eocene, and in chalk and flint, and still more in
the tertiaiy deposits, the abimdance and variety of forms are greater. Diato-
maceous shells are cuiiously preserved to us in large abundance and perfec-
tion in guano, in which they have doiibtless entered as a component in the
way of mixture with food taken by the birds which have deposited that
manure.

The foregoing facts teach us that probably, in the present condition of our
planet, no portion of its siu'face is destitute of Infusorial life ; and now, fi'om
the prosecution of microscopic research in connexion with geological facts,
it would appear that, imdcr this simplest and primary form, organic life made
its fii-st appearance on the globe, and has, dimng the many epochs of this
world's history, and notwithstanding the mightiest changes its surface has
undergone, been sustained imtil the present moment ; and, what is more, so
extraordinary is the capability of the silicious Diatomeas to preserve life, and
so astonishing their powers of multiplication, that species which are now
found living have theii- generic and even their specific types at the veiy
da'svn of creation. Prof. Ehi-enberg has advanced tliis same statement in his
recent work (MiJcrogeologie), saying that the oldest sihcioiLS Infusoria, whe-
ther Carboniferous or Silurian, belong to the same genera, and often to the
same species.

AiiiioLiTic DiATOMEiE. — Elircuberg was the fii'st to demonstrate the fre-
quent existence of Diatomea3 along with other microscopic beings and or-
i ganic pai-ticles in the atmosphere, principally in those showers of dust which
! fall from time to time in various parts of the world, and in those other mete-
j oric products known by the name of ' meteoric paper ' and ' blood-rain.' In
I such atmospheric productions, the Berhn naturalist has detected above a him-
I dred species ; these, accompanied by descriptions and figiu-es, and prefaced
; by an account of aU such atmospheric phenomena on record, were jjublished
I by Ehrenbci-g in a large brochure entitled " Passafstaub unci Blaircgen,''
consisting of 192 folio pages. An extract from this book will convey the
best attainable notion of the physical importance of these aciial dust-showers.

The quantity of actual solid matter that has fallen from the atmosphero
by showers is far more considerable than supposed ; for, though it falla iu a
diffiiscd dust-like form, the extent of surface covered at any one time is
veiy considerable. Comparing it with meteorolites, Ehrenberg obsciTCs that
! the total quantity of these stones which fell between 1790 and 1819 weiglicd
600 cwt., while in a single dust-shower at Lyons, in 1846, the solid matter
weighed fully 7200 cwt. Other dust-storms in Italy, at Cape de Verd, and in
other localities have exceeded even that at Lyons, in the quantity of matter
precipitated to tlie eartli ; and Elirenberg suggests to the imagination' the
millions of tons that must have fallen since the time of Homer. Lastly ho
entertains the curious opinion, that this meteoric dust does not necessarilv
derive its existence from the oartli's surface, and from the force of atmospheric
ciuTcnts, but from some general law of the atmosphere, according to wMeh

I

86

UKNEKAL lU.STOllY Ol- TJIE INl'USOKIA.

the living organisms mainly composing it may have the power of self-
cloveloi:)ment in the air.

Uses of Diatomaceotjs Deposits.— The utility and possible and probable
purposes of these minute organisms to mankind have not yet met with due
consideration. Their relation to the soil, in which they are so abundant,
and their influence on its fniitfulness are matters only incidentally reflected
on by authors. " Sufficient attention," remarks Prof. Gregory {J. M. S.
1855, p. 2), " has not yet been paid to the fact of the invariable presence of
Diatomeae in all earths in which plants are foiind. Ehrenberg, in his Mi-
h-ogeologie, has established the fact as a universal one, and pointed out the
important bearing it h.as on the growth of the soil. Indeed, it is difficult to
imagine a more effectual agent in the transference of silica from the waters
to the solid earth than the growth of Diatomeae, the shells of which are as
indestructible as their multiplication is rapid. Ehrenberg is of opinion that
they live in the soil as well as in water ; and the constant presence of
moistm-o in the soil renders this conceivable. Although the proportion of
silicious matter dissolved in ordinaiy water is but small, it is evidently
sufficient to supply the shells of millions of Diatoms in a veiy short time ;
and it is therefore probable that, as fast as it is extracted from the water bj-
them, it is dissolved from the rocks or earths in contact with the water, so
that the supply never fails."

Mr. Eoper has also suggested, from the consideration that the best samples
of guano contain the greatest number of these silicious skeletons, which
doubtless serve to replace the large amount of silica abstracted from the soil
by the cereal crops, that it is probable that the deposits of many of our
rivers would have a beneficial eff'ect if applied to the land ; and it rests with
the microscopist to point out the most favourable localities for obtaining
them. Ehrenberg notices an instance where this has been done in Jutland,
where a blue sand abounding in calcareous and silicious shells is collected,
and greatly increases the fertility of the arable soil to which it is applied ;
and Prof. Bailey also states that the mud of Newhaven hai'bour is used as a
fertilizer, and is found to contain 58-63 per cent, of silica. The author
last-named has moreover adduced instances to prove that the great fertility
of the rice-fields of South Carolina is mainly due to tlieii* richness in Diato-
maceous remains. This notion is strengthened by the examinations of
Ehrenberg, and by the commonly observed fact of the occiu-rence of Diatomeaj
about the roots of plants, especially of the cereals, which demand a large
supply of silicious material to construct their stems.

Dr. Hooker (op. cit.) contends that the abundant Diatomaceous deposits of
the South Pole supply ultimately the means of existence to many of the
smaller denizens of the ocean, and that they keep up that balance between
the animal and the vegetable Idngdom which prevails tlu-ough all other lati-
tudes. He adds that they probably piuify the Adtiated atmosphere, just as
plants do in a more temperate region.

In the arts, the remains of Diatomaceous shells, as the chief ingredients in
certain deposits, are brought into use as polishing- powder under the name of
Tripoli, and also, as an extremely fine and pure silicious sand, in the manu-
facture of porcelain. The powder called Tripoli has various origins, and
diffcra in the microscopic orgtinisms it contains. Species of Melosira especially
abound — for instance, of Melosira varians. Elirenberg infonns us that the
Tripoli of Jastraba in Himgary and that from Cassel resemble each other in
their component species.

A veiy remarkable application of a deposit of Diatoraea3 is its use as
an article of food, under the pressui-o of want, by the wi-etclied inhabitants of

OF THK BIATOMEiE.

87

some inhospitaMo and barren districts of Em-ope— for instance, in some
localities of Lapland and of Hungaiy, and in other parts of the world.
Ehi-enberg mentions a sort of earth under the name of " Tanah," eaten in
Samarang and Java, which overlays some moimtains of Java at several places
at a height of 4000 feet. It is generally solid, plastic, and sticky ; it is
roUed and dried in the shape of small sticks over a charcoal fii-e, and is eaten
as a delicacy. An examination of this earth disclosed 3 or 4 species of
Polygastrica and 13 of Phytolitharia,

It has been attempted to make the specific characters of Diatomaceous de-
posits of critical value in deciding on the date and superposition of rocks.
However, the geographical distribution of these beings is as yet insufficiently
known ; and every day reveals the fact that species deemed peculiar to some
one locality are to be foimd in others, and to have at least a very wide range.
"We have already quoted some examples of apparent limited diffusion in oiu'
remarks on geographical distribution ; it is therefore not necessary to illustrate
the subject further in this place.

The circumstance that some one or two species seem at times peculiar to a
neighbom-hood, has encouraged antiquarians to seize on it with, the hope of
determining the locality whence the clay was procured from which ancient
specimens of pottery or porcelain were manufactured.

Another practical purpose to which the shells of Diatomese have been put
is as test-objects for microscopes, the penetrating and defining powers of which
are measiu-ed by their ability to detect and demonstrate the existence and
natiu'e of certain markings on the siuface of the siLicious epiderm — such,
for example, as the striae of Pleurosigma.

Oir THE NATURE OF DiATOMEiE, WHETHEIi AnIMALS OB PlANTS VARIOUS

HYPOTHESES. — The nature of the Diatomeae is still a much-vexed question,
although the opinion of those naturalists who hold them to be plants — mem-
bers of the great family of Algee — preponderates. Ehrenberg assumed their
animal nature, and persuaded himself of the existence of a complicated organi-
zation, such as neither the researches of others can confirm nor analogy sup-
port. In his latest papers on Organization, he has insisted most strongly on
the apparent successful feeding of these organisms with particles of colom*
which entered within their interior. These experiments are not satisfactoiy,
and have failed in the hands of others ; it is besides quite clear, that the
umbilicus, at which he represented the colour-granules to enter, is no real
opening in the lorica, but a thickening of its epiderm.

Prof. Meneghini, now many years ago, penned a learned treatise to prove
the animality of the Diatom ea3 ; but although he offered many ingenious argu-
ments to support his opinion, he did not succeed in establishing it. Many de-
tails of stiiicture and organization and micro-chemical characters, lu-ged by him
in favour of their animal nature, have been considerably modified or entirely
set aside by subsequent researches ; and the general argument, that the varia-
tion fi'om recognized plants is in many particulars very marked, has only a
comparative or relative force, according to the extent of differential striictui'e
of animals which may, on the other hyjiothesis, bo set forth and proved.

The distinguished Italian naturalist indeed limits his design in the treatise
before us (On the Animal nature of the Diatomea), R. S. 1853) to disputino'
Kiitzing's arguments for their vegetable nature, saying (p. 3G6), " Whilst
unable to confirm or refute the opinions of Ehrenberg, wo seem to have
observed facts sufficient to disprove those of Kiitzing,"

On this same side are ranged Pocke, Eckhardt (a pupil of Ehrenberg), and
Prof. Bailey, who express their inability to reconcile some of tlio stmctural
details and physiological phenomena with vegetable organization. Schlcidcn

88

GENERAL niSTOHY Or THE INFUSOKIA.

perhaps slioiild ulso bo reckoned of the number, since he remarks, in his de-
scription of the shield of a Navicula, that "such an artificial and complicated
structure amongst plants has no explanation, and is entirely without signifi-
cation. In all actual plants we find the silica present in quite a different
form, as little separate scales or drops, and distributed through the substance of
the ceU-waU."

In favour of the vegetable natui-e of the Diatomeaj, on the other hand, the
majority of the original observers in this coimtry unite Avith many of the most
distingnislied naturalists of the Continent, such as Kiitzing, Siebold, Nageli,
Rabenhorst, Braun, Cohn, Meyen, &c. The last inquirer, so long ago as 1839,
urged vaiious objections against the presumed animality of the Desmidieae
and Diatomeae, and more particularly against Ehrenberg's views. Respecting
the animality of the Diatomea3 (Naviculacea), he remarks generally — " The
reasons adduced for such belief arc so weak, that the conclusions deduced fi-om
them are yet for the most part very doubtful."

A small number of natui'alists have expressed the notion that the Diatomca;
belong eqiially to the animal and to the vegetable kingdom. M. Thm-et may
be named as one of these, since he has stated that there is no more reason in
favour of the one affinity than of the other. Such an idea is certainly unphilo-
sophical; for it would cut the Imot instead of loosening it, by the assumption
of an order of organic beings intermediate between the animal and the vege-
table Idngdom, and undeterminable to which they belong.

We will now proceed to state the leading arguments for the animality of
the Diatomeae, indicating the name of the MTiter suggesting each, so far as
practicable : —

1. The Diatomeae — many species at least — exhibit a peculiar' sjjontaneoiis
movement, which is produced by certain locomotive organs. — Ehrenberg.

2. The greater part have in the middle of the lateral surface an opening,
about which certain round corpuscles are situate, which become coloured blue
when placed in water containing indigo, like the ' stomach-cells' of many In-
fusoria,, and consequently may equally be regarded as stomachs. — Ehrenberg.

3. The shells of many Diatomaceae resemble in structiu'e and conformation
the calcareous shells of Gasteropoda and similar Mollusca. — Ehrenberg.

4. The method of multiplication by self-division. — BUircnbergandMcneghini.

5. The complicated structure of the wall of the fnistiiles, and the characters
of the silicious deposit. — Schleiden, Bailey, and Meneghini.

6. The greater affinity in chemical composition of the contents (the cndo-
chrome) with animal than "with vegetable products. — Meneghini.

Each of these arguments reqiures examination in detail, and its value tested.
To begin therefore with the first — the occurrence of locomotion and the organs
by which it is eff'ccted, as evidences of animal constitution. Morren, in the
paper quoted (Jahresbericht Ahad. Berlin, 1839), pointed out that motion is not
confined to animals, but exhibited also by the spores of Algae and by sperm-
atic particles. To these examples may be added the OsciUatoria?, Proto-
coccus in its various phases, Vauclieria clavata, Uloihri.v zonata, and otlier
Algae, among which are the now admitted genera of Volvoeinea). In many
of these, the movements are mucli more active and lively, and present more
seeming spontaneity than those of any of the Diatoms, The emplojnncnt of
the word spontaneous to signify the sort of movement of these organisms is
certainly unjustifiable, if understood at all in its usual signification, of an act
originating in the moving body directed to a special puqiosc ; for no more
spontaneity is manifested in the motions of these silicious organisms than in
those of the leaves of the Dioniva miiscijniln wlieu any particle impinges on
their sensitive hairs. Meneghini, in examining this point, is compelled to

OF THE DIATOMEiE.

89

admit that no absolute proof is deducible from the movements of the frustules,
in support of their animal nature ; and the only difficulty to liim agamst
admitting that tliey may be vegetable in character, is, that they are so dif-
ferent from those of OsciUatorite, Desmidieee, and Protococcoidese, — a worth-
less objection, to be sufficiently answered by asking whether that motion does
not diifer as widely from that of any animals, and whether the movements of
the Desmidieffi are not equally unlike those of the Oscillatorise as those of the
Protococeus.

The locomotive organs insisted on — consisting, according to Ehrenberg, of a
retractile foot and of retractile ciliary processes — have not been sufficiently
■demonstrated to use as an argument. Ehi-enberg, Corda, and more lately
Focke, are the only observers who pretend to have seen such organs, although
the organisms said to possess them are subjects of daily minute research by
hundreds of wonder-finding microscopists. The mucous film which invests
many Diatomaceous frastules may, indeed, have been seen and misinterpreted.
Meneghini calls attention to a kind of sparkling or agitation — actually a rapid
and indeteriniaate change in the refz'action of light at their extremities, Avhich
he seems disposed to believe shadows forth the presence there of some sort
of eihaiy locomotive organs. Grranting, however, that cilia were ascertained to
be the cause of the movements perceived, the doctrine of animality would in
no way be advantaged, since cOia are not peculiarly animal structures.

According to ISTageli, one sort of vegetable movements originates in the act
of growth. Of such a kind are probably the vibrations of the Oscillatoriffi ; and
possibly the motions of the Diatoms are in some degree reducible to the same
category. And it is to be remarked that these motions are not equally apparent
and active imder all circumstances, even among specimens of the same species,
but are most so when the vital phenomena of the organisms are most aroused —
when the most rapid interchange of material is going on between the external
medium and the internal cavity.

2. The second argument rests entirely upon hypothetical groimds, derived
^rom Ehi-enberg's observations, and is valueless so long as those observations
are imconfirmed. It seems quite clear that the central opening or umbilicus
spoken of has no real existence ; and if this be so, then the apparent entrance
of colouring matter within a set of corpuscles situated around it must be an
error of obsei-vation, imless the unproved and improbable assumption be made
that the colom'-particles enter at foramina placed elsewhere (as at the extre-
mities), and become transmitted to these centrally placed sacs or so-called
stomachs. Kiitzing declares that the seeming entrance of colour-granules is
the result of mechanical causes, and adds the more important statement that
the central collection of vesicles is often wanting.

3. The third argument, that a resemblance obtains between the shells of
Bacillaria and those of some Molluscous animals, is, to say the least, fanciful,
and in a scientific inquiry can be admitted to prove nothing. If external
similarity proved anything, it might as well be adduced to demonstrate tlic
affinity of a lead-tree with the higher plants, whilst, again, the error to which
this sort of proof wiU lead is well exemplified in the case of the Foraminifora,
which from mere outward resemblance were for years accounted members of
the Cephalopodous family. In the latter instance, indeed, the similarity in
external form was very stiilcing— far exceeding that of any Diatom with any
testaceous animal.

Kiitzing, in his review of this assigned reason for their animality meets it
in another way by obser%ang that, among the.coUs of higher plants, examples
are to be found which in configuration find other pai'ticidars aoroe witli Dia
toms— for instance, the numerous forms of poUen witli theirlingios spines

90

GENERAL IIISTOUY OF THE INFUSOlilA,

&c. But, as Meneghini remarks, " he might have added the more appropriate
instance of the Desmidieaj, wliich would be very closely allied to the Diatomea;,
if the latter, like the former, could bo referred to the vegetable kingdom. If
not equal ia constancy and regularity, the Desmidieaj display a greater degree
of complication: and we must remember the different nature of their substance ;
for in the vegetable cell, when Ume or silica predominates, the wall becomes
imiform and regular."

4, Multiplication by self-division was at one time cited by Ehrenberg as
peculiarly an animal phenomenon, — a notion at variance with the observations
of eveiy naturalist, and now requiring no refutation. However, Meneghini
has more recently advanced the statement that an essential difference iu the
process of fission prevails between the Diatomeae on the one hand and the
Desmidiete and Alga) in general on the other, applying to the former modifi-
cation (in accordance with Brcbisson's views) the term cleduplication, to the
latter reduplication. To extract his remarks (ojj. cit. 368) — " Division is
always longitudiual, and takes place underneath a fine external sihcious
membrane, by the formation of contiguous diaphragm walls which divide the
internal cavity. Thus the contents are longitudiaaUy divided ; and this divi-
sion is complete if the two new individuals detach themselves and so acquire
individual liberty. It is imperfect if the fine sUicious persistent membrane
and the secreted gelatinous substance retain them connected together. This
mode of reproduction (which Brebisson distinguished by the name of dupli-
cation and deduplication, from the reduplication of Desmidiete) deserves the
most attentive obsei-vation. The foregoing exposition presents the fact in its
most rude and superficial general appearance, and makes us feel acutely the
want of a more circumstantial description peculiar to various forms. It is
only after having established facts relative at least to the principal generic
types, that we can establish, on a scientific basis, the general idea of multi-
plication by duplication. A few observations sufiice, however, to prove that
this does not occur in so simple a manner as we are taught to believe, by
comparing it with that in vegetable cells. In the Achnanthidia, for example,
it is described and figured that the principal surfaces, which occupy the inter-
mediate space between the two superior and the inferior valves, commence by
presenting fine transverse lines, and next a strong longitudinal line along the
middle ; then there appear two new intermediate valves contiguous to each
other — the superior valve (?) of the new inferior individual, and the inferior
one of the superior. My observations convince me that the aft'air does not
proceed with so much simplicity. I have often seen the two lateral valves
separated, and the intermediate space thus largely amplified. In otlier cases
there appeared only a new inferior valve complcmcntaiy to the superior, the
inferior individual thus remaining incomplete. Finally, in others, between
the complete superior individual and the incomplete inferior valve, there
appeared a new individual with both its valves, but nearer together, smaller,
finer, with lines much less distinct." In short, " in tliis phenomenon there
is more complication than that of a simple cellular dcduplication."

5. In a previous page (p. 88) we have quoted Schleiden's notice of a dif-
ficulty in the way of recognizing Diatoms to be plants. It is one likewise
Avhich has presented itself to others, for instance, to Prof. Bailey and Mene-
ghini. " If we suppose them to be plaaits," says the latter writer, " we must
admit cveiy fnistule, every Navicula, to be a cell. Wo must suppose tliis cell
with walls penetrated by silica developed vvitlxin another cell of a different
nature, at least in every case where there is a distinct pedicle or investing
tube. In this silicious wall we must recognize a complication certainly un-
equalled in the vegetable kingdom.'" {op. cit. p. 372.)

OF THE DIAT0ME-2E.

91

This critique of Moneghini loses much of its force when it is noticed that
" the existence of a pedicle, or isthmus, or of a muco-gelatinous sheath envelop-
I ing the fiiistules, is assumed by him, quite hypothetically, to mdicatc theu'
I formation Avithin a cell-wall represented by the soft investment,— an idea
originated by him because he could not admit of an extra- cellular formation.
The present state of knowledge, however, clearly recognizes the not infi-equent
I formation of extra-ceUular matters about ceHs, and consequently this portion
of the difficidty in question will cease to have importance.

On the other hand, no animals can be pointed out having a similar complex
silicious stmcture, whilst an analogy may be, to a certain extent, found with
the Desmidiete, some of which have a small deposit of silica in their envelopes,
which again in some Diatoniaceous frastules is very deficient (see p. 37).
Indeed, the affinity between the Desmidiete and the Diatomeae is mamfested
\ by the differential characters which naturalists feel themselves called upon to
; indicate (see p. 95).

The composite stiaicture of the fnistules is principally the result of the per-
meation of the external tunic with silex. The little box or capsule, when
fii-st produced, represents a simple enclosed cell, imbued Avith more silica than
a Desmidiaceous frond, but othermse not histologically unlike. Wlien the
i little being prepares for self-division, the opposite valves separate, much as
I the opposed halves of a frond of one of the DesmidieEe, and the intermediate
I production, according to the habit of the class, becomes penetrated by silica
(to a less extent, however, than the original valves), and assumes so much of
a permanent character that it is very frequently considered an independent
tlm'd segment.

So again, the ceUuIar, or areolate, or otherwise figured and involuted surface
of the frustules, cited by Meneghini as dissimilar to any plant-structure, woidd
also appear to be a consequence of this permeation of the organic membrane
with silica, and of various modifications consequent thereon. To show that
I analogies are not wanting in the vegetable kingdom of curiously modified and
, figured cell-walls, we may mention as examples, besides poUen-grains, in-
stanced by Kiitzing, the sporangia of DesmidieEe and of various Algae. More-
over, the capability of the simplest enclosing membrane to develope a very
complex superficial structiu-e is illustrated in the case of the Eliizopodes,
I among which are many examples of striated, areolated, and othermse modified
I shells, which, m the eyes of many, range with imiceUular organisms. Wo
' must not forget to state that Meneghini himself seems to have appreciated
the effect of the pei-meation of sUica upon the characters of the cell- wall ; for
: he says, in his supplementary annotations (op. cit. p. 511), " the part which
i silex takes in the formation of the cell- wall is undeniable," as in the epi-
dermis of GramineaB, Palms, and Equiseta. " The stomatic ccUs of Equiscta
merit particular attention, both from the sUex they contain, and the transverse
stria; they present on the intemal siu'face. This resemblance to the shield of
Diatomeae might lead us to believe that we ought to regard it as an argument
I for maintaining the vegetability of the latter: but I do not think that I ought
j to dwell upon such an objection ; I only notice it because I would not appear
to be, or pretend to be, unacquainted with it. Yet it seems to me important in
another point of view — the apparent complication that the simple cell may
assume when penetrated by silica."

We cannot do better than close this part of the argument by Prof. Smith's
review of the subject {Sjnojis. ii. p. xix) :— " In every case tliis membrane
[of the frustide] is more or less penetrated or imbued with sUex ; and the
presence of this substance appears to have modified the intimate structure of
the membrane, and induced great variety in (lie mode and character of its

92

OKJIIJIUX HISTOBY OP THE INFUSOKIA,

formation in different genera, accompauied by great regularity in the indi-
vidual species.

" These variations exhibit themselves in the different modifications of
structure which constitute the markings of the valves, appearing imder the
form of ribs and nodules, costse, striae, or cellules of an elliptical, cii-cular,
or hexagonal outline. A wide comparison of specimens seems to me to prove
that these various markings originate in the tendency impressed upon all
organized structure to develope itself upon the type of the cell, and that the
presence of the silicious constituent in the cell-membrane of the Diatom gives
a fixedness to this tendency, which, in ordinary cases, is cither not discern-
ible in the structiu'e of the membrane, or whose eifect is obliterated by the
coalescence of the softer material wliich constitutes its substance. However
this may be, it appears to me certain that the structure of the silicious valve
in the Diatomaceae is invariably cellulate, the cellules being more or less
modified according to the peculiar requirements of each species, and that no
other explanation of their characteristic markings seems consistent with the
facts which arc established by a careful examination and comprehensive know-
ledge of Diatomaceous structure. That this explanation does not' involve con-
siderations at variance with the conditions of unicellular vegetable life, wiU
be obvious to any one familiar with the structure of the sihcious epidenn in
the Equisetaceae and Graminaceaj, and the distinctly cellulate stmcture of
many pollen-grains, while this very presence of silex as a constituent of the
cell-wall in the Diatomaceae appears to be wholly unaccoimtable except on the
supposition of the vegetable nature of these organisms. In no instance do we
find a parallel condition in the animal kingdom (for the secretion of silicious
spicula, as an internal skeleton, in some of the Spongideae, cannot be regarded
as an analogous phenomenon), whereas the vegetable kingdom fiunishes us
with cases, not merely of the secretion of sUex as a vegetable product ia the
Bamboo, but with frequent instances of its intimate union with cellulose in
the membrane which forms the epiderm of the cell, as in the Natural Orders
ali'cady mentioned, in the Palmaceae and others."

On the nature and mode of deposition of the sUex, Dr. Bailey has ad-
vanced the statement that the silica in Phytolitharia, as well as in Diatomea;,
Polycystinca3, and SpongUithes, is not doubly refractive and polarizing, as
Ehrenberg described, and that even the admitted exception of Araclinoi-
cliscus is not such. The error in supposing it so has originated from the im-
perfect removal of the dense carbonaceous tissiies which ai-e deposited beneath
the silica.

6. The final argument we have to consider for the animality of the
Diatomea) is, that the greater affinity in the chemical composition of the
contents, i. e. of the endoclirome or gonimic substance, is with plants, and not
with animals. This argument is certainly based on a nice and very difficult-
to-bc-determincd fact. Meneghini insists on it as important. His remai-ks
have already been given in oiu- notice of the contents of the frustulcs, to
which we must refer (p. 47), addiiig here only some supplcmentaiy obser-
vations to fully convey his opinions. " Finally," he writes (op. cit. p. 3GG),
for this is not a property peculiar to cliloropliyll, " I may add that, if a portion
of chlorophyll could be demonstrated in the interior of Diatomea?, this would
by no means invalidate thcu' animal natm-e ; we might stUl suppose they had
swallowed it for food. As to the oU-globulcs " which Kiitzing represents,
Meneghini considers they may be no more than particles of sarcode, Avliich
have an oily appearance ; and he woidd observe " that the number and volume
of these globules mcrcase considerably after death, and that during life they
arc situated upon a longitudinal line extending from one extremity to the

OF raiJ DIATOMEJJ.

93

other. And," ho continues, " I rely upon the observation that there is some
motion and successive alteration in them, as if these minute globules mixed
vrith lai-ger ones, and separated again from them." For, to the mind of
the Italian naturalist, the hypothesis of stomachs is admissible, although
the fact that a polygastric structiu-e (affirmed by Ehrenberg) has not been
shown in the ciliated Protozoa is in itself an d priori argument that such an
organization is not to be found in the Diatomeos, among which animal cha-
racteristics are so much more deficient and indeterminate.

Although, to oru- apprehension, this argument, based on the differential
chemical composition, to the extent it is developed by Meneghini, is incom-
plete and inconclusive, yet it was a duty to present it, in order that some of
the many ardent English microscopists may be induced to attempt the solution
of this micro-chemical question.

Eabenhorst, we should not omit to state, describes the colouring matter of
Diatomete as quite different from the chlorophyll of plants. For instance, he
states that the chlorophyll of plants is taken up by alcohol, dissolves with a
yellowish-green colour in alkalies, and with muriatic acid acquii'es an emerald-
green colour, whereas the colouring material of Diatomeffi is insoluble iu
alcohol (although after a time its coloirr fades), remains unchanged by alkalies,
and acquires a pale-green colour with muriatic acid.

It stUl remains to point out the facts which speak in favour of the vegetable
nature of the Diatomaceae. The following summary was offered by Kiitzing : —

" 1. The great resemblance of compoimd forms to Algae, and their develop-
ment by iission. There are, indeed, compound Infusoria, as Monad-masses
and Polypes : but the former are veiy questionable animals ; and the latter
have this essential distinction, that the individual animal lives "without
(external to) its habitation, and moves freely, whereas such Navicidcv as
Encyonema, ScJiizonema, and Micromega, and similar genera, grow within the
enclosing substance, biulding themselves up lilvo the cells in the stem of a
plant — so vegetating here only as cells. In Hlce manner, the individuals of
Fragilaria, Melosira, Himantidium, &c., are steadily fixed, and unable to
exhibit animal motion.

" 2. The inner soft organic parts, which I have designated gonimic sub-
stance, possess, as well in their chemical nature as in their development,
peculiarities akin to those met with in the ceU-conteuts of confervoid Alga;.

" This relation is most clearly seen in the genus Melosira and its allied forms,
which, not only in form, but also in the chemical components of their con-
tained matter (since the presence of chlorophyll is common to all Diatomeas),
arc closely allied to the confei'void Algte.

" 3. The development of seeds, or young [as Kiitzing represents it], occurs
here as in undoubted Algtc, but never as in true animals.

" 4. The Diatomerc, and especially the free moving Nnvimlcc, dcvelope, in
the Sim's rays, an appreciable quantity of oxygen, like all admitted plants'

" The evolution of oxygen, indeed, occurs in green Monnds and EugleiKv ;
but this affords no argument for the animality of the Diatomea), but renders
the animal nature of those Infusoria themselves very doubtful, and the more
so as recent obsei-vations confii-m the idea of the origin of the lower plants
themselves from Monads and Euglenn;. AVherefore all these comparisons
sei-vo to favour the belief in the vegetable nature of Diatomea)."

To these nrguments has been added another, resting on the assumption of
conjugation being peculiar to plants ; and Mr. Blackwell discovers further

It is ncoessaiy to inquire, mi«lm, into tlic real value of the arguments

94

GENERA 1- niSTOEY OE THE INFUSOniA.

on this, as 1ms been done with tlioso on the other side of the question.
Menoghini enters the lists with Kiitzing, and disputes the conclusions arrived
at by him, rather than the facts on which they rest.

The fii'st argument, founded on external resemblance, has little value, and
offers no certain indications of affinities. However, taking Kiitzing's state-
ments in his own words, modem research has added to its weight ; for it
has proved, what was before only a probability, that the so-called Monad-
masses are only of a vegetable natui-e.

The second reason advanced has been already discussed, Avhilst the third
rests as yet on incomplete observations, and in Meneghini's opinion has an
equally strong analogy in animals, for example, " in the ovaries of Polypes
and other inferior animals, as in many Ovipara of superior classes. And, in
fact, the bag of a spider, with the thousands of small eggs that it contains,
seems to me quite as like, as the spore of an Alga, to the organ of propaga-
tion of a Schizonema or a Micromega.'" These analogies cannot be allowed
much weight, whilst it is, on the contrary, pretty clearly ascertained that the
sporangia of Diatomese produce a brood of young forms within them, — a
phenomenon according in aU particulars with the mode of reproduction in
numerous Algae and Fungi.

The fourth argument for their vegetable nature must be admitted to possess
great importance. Since Kiitzing enunciated it, the apparent objections
against the vital phenomena in question being restricted to plants, haA^e been
removed by subsequent inquiry. The green Monads and Eugleno}, cited by
Kiitzing, are now recognized to be vegetable, and can no longer cast doubt, by
reason of an assumed animal nature, on the fact of the evolution of oxygen
being a characteristic of vegetable life. The evolution of oxygen, as Prof.
Smith, like every other careful observer, tells us, " may be noticed in any
mass of Diatomacese during the warmer months of the year, or in gatherings
freely exposed to the sun, in the elevated temperatiu-e of a confined apartment,
dui'ing the winter or spring. Under these conditions the water in the vessel
becomes covered with minute bubbles of oxygen, and portions of the Diato-
maceous stratum are floated up by the buoyancy of the globules of this gas
adhering to their frustules. Such phenomena can only be accoimted for by
supposing that the Diatomacete are plants, and that they exhide, like all
plants in a state of active vegetation, oxygen from theii- tissues ; but this pro-
cess is irreconcilable with the hypothesis of their animal nature." {Siinopn.
vol, ii. p. XX.)

Prof. Carpenter insists {Microscope, p. 469), that the most positi-^-e and
easily defined distinction between Protophyta and Protozoa "lies in the
nature of the aliment, and iti the method of its introduction," in each case.
" For whilst the Protophyte obtains the materials of its mitrition from the
air and moisture that surrovmd it, and possesses the power of dctaclmig
oxygen, hydrogen, carbon, and nitrogen from their proA-ious binaiy combina-
tions, and of imiting them into ternary and quaternary organic compounds
(chlorophyll, starch, albumen, &c.), the simplest Protozoon. in common witli
the highest members of the animal kingdom, seems utterly destitute of any
such power, and is dependent for its support upon organic substances pre-
viously elaborated by other beings. But fiu-thcr, the Protophyte obtains its
nutriment by mere absoi-ption of liquid and gaseous molecules, which pene-
trate by simple imbibition, whilst the Protozoon, though destitute of any
proper stomach, makes (so to speak) a stomach for itself in the substance of
its body, into which it ingests the solid particles that constitute its food, and
within Avhich it subjects them to a regular process of digestion. Hence the
simplest members of the two kingdoms, which can scarcely be distinguisliod

OF THE DIATOME^Ti.

95

from eacli other by any strmtural characters, seem to be pJiysiohc/icalh/ sepa-
rable by the mode in which they perform those actions wherein their life most
essentially consists."

The process of conjugation has been used as an argument for the vegetable
natiu-e of Diatomete by Mr. Thwaites and others. This subsequently seemed
to be set aside by the observation of apparent conjugation in Actinophrys and
Gregarina observed by Kolliker and Cohn. However, this phenomenon
appears again in the ascendant as a vegetable characteristic ; for the observa-
tions of Ml-. Weston {J. M. S. 1856, 122), of Leuckart, Lieberkuhn, and
others, go to show that the act believed to be one of conjugation in the
Actimphrys, is not really a process of reproduction, but merely a temporary
cohesion : moreover Lieberkuhn {Mem. de VAcad. Boy. Belyique, vol. xvi.)
proves that the production of the Navicellce is not necessaiily a consequence
of the act of conjugation in the Qregarince.

K future research substantiate the fact that conjugation is essentially a
vegetable process, then the nature of the Diatomete will no longer be doubtful.

On a review of the arguments ui'ged on each side, and on consideration of
the whole stractural and vital peculiarities of the Diatomesa, we are disposed
to consider them of a vegetable natui'e — members of the great family of
Algae, and, together with many other unicellular plants, to constitute a group
known by the name of Protophyta. Fageli, in 1849, took this view, and
reckoned the Diatomere as one of his eight orders of unicellular Algoe, of
which the Desmidiaceae and Palmellacefe were other two. How close must
be the afBnity of the Diatomeae with the Desmidieae is shown by the fact of
the two families having so long been treated of together under the common
head and name of Bacillaria. And although sufficiently decisive characters
separate the one set of beings from the other, yet, in the grand phenomena
of life and organization, a true homology exists. The difference between some
Desmidieae and Palmelleae is as much pronoimced as it is between the former
and some Diatomeae ; and between these several orders, together with the
Zygnematae, various intermediate forms are to be found, which serve as con-
necting links. Although Mr. Ealfs would not now insist upon the distinc-
tions between the Desmidieae and Diatomeae, formerly laid down by him as
decisive, yet they may be here reproduced with advantage. 1. In Diatomea?
(op. dt. p. 19) " each frustule consists of three pieces, one central, ring-like
and continuous all roimd, and the others lateral." In opposition, Prof. Smith
asserts that the central third segment is no essential part of the frustules,
but a portion produced, just Hlce that between the opposed valves of
Desmidiea), preparatoiy to the process of self-fission. 2. " The di\dsion is
completed by the formation of new portions ■within the enlarged central
piece, which then falls off, or else by a new septum arising at the centre ; "
but Mr. Ealfs believes that in eveiy case the separation commences internally
before it extends to the coveiing. So fai' as we can miderstand the matter,
no essential variation in this process prevails in the two families. 3. " Their
coverings, with vciy few exceptions, are silicious, withstand the action of
fire and acids, and may bo broken, but not bent ; the frustules are often
rectangular in form, are never warted, and scarcely ever spinous." To these
statements it may be replied, that in a few Diatoms the silex is in small
quantities in the valves, and that, on the contraiy, examples of partially
silicious Desmidieae arc known. The action of fii-e and acids, the capabiUty
of being bent or not, are qualities dependent on the relative proiiortion of
silex m the fnistulcs, and are but secondary distinctions. The same may be
said of the remaining points mentioned— the rectangular form and tlio
presence of warts and spines. The form indeed is, at best, of little value in

96

GENERAL HISTOUY OF THE INFCSOl'.IA.

the argument. The rectangular form of the Diatoracae is doubtless a conse-
quence mainly of the silicious composition : yet it is far from univei-sal among
them ; for some species are rather orbicular, others sections of cylinders, others
capsular, and others again not unlike square sacs with bulging sides and rounded
corners. Even where a rectangular outline exists, it is most frequently only in
one view ; and the most that can be said is, that the lines of jimction are in
many instances acute. On the other hand, examples of a rectangular outhne
are to be found among the DesmidietE and their allies : the junction-surfaces
of Hyalotheca and Didymoprium are at right angles to the sides of the frond ;
the end view of Staurastrv/in tumidum is as angular as the front view of a
Triceratium ; and the fi-ont view of Euastrum mneatum presents decidedlj-
rectangular truncate extremities. So too in the genus Pediustrum, formerly
enumerated among the Desmidiese, although now detached as a subfamily
and placed between them and the Palmelleae, examples of an angular outline
occm", as in the Pediastrum Tetras and other species. As to the production
of spines, sufiiciently numeroxis examples exist among the Diatomese to prove
it no distinctive peculiarity of the Desmidieae ; and although warty expan-
sions or elevations of the siu'face precisely like those of some Desmidiese, may
not be noticed in Diatomeas, yet certain exag'geratcd inflations of the surface
are seen in some Diatomese, e. g. in Bidduli^Ma imlcheUa and B. regiiui.
The two next distinctions indicated by Mr. Ealfs are of more consequence,
but nevertheless cannot be admitted as demonstrative of an entire difference
in nature. They are thus stated : — " Their internal matter is usually brown
w^hen recent ; and although some species are greenish, or become green after
they have been gathered, none are of a truly herbaceous character. Theii'
vesicles bear some resemblance to those in the Desmidiese ; but they ai'e
of a yellower colour, and no starch has been detected in them." The last
section of this statement must be held as still suh judice ; the chemistry of
the endochrome is too imperfect to afford a safe argument, and the chemical
relations of starch and isomeric compoimds too little understood. The con-
cluding distinction, " that the Diatomeae do not conjugate," the researches of
Mr. Thwaites have negatived.

To employ the summary of the affinities of the Diatomeae presented by
Prof. Smith {Synops. vol. ii. p. xxi) : — " The Diatomaceac, with specialities of
their own, have also intimate alliances \nt\\ the other ordei-s of the Proto-
phyta, resembling the Zygnemaceae and Dcsmidiaceac in the reproductive pro-
cess,— the Nostochaceae in the tendency shown by several genera to surround
their fi-ustules mth frondose masses of mucus, within which linear scries of
cells are subsequently developed,— the OscUlatoriea^ in their movements, — the
Palraellacese and all the orders I have named, in the self-dividing act by
which the individuals of the species arc miiltiphed, or the aggregate of spe-
cific life maiatained and increased."

Determination of Species and Genera ; Yakieties ; Classification. —
The question has been very much discussed of late, what chai-acters of the
frustules and of their .contents arc to be employed in the construction of
species ? Ehrenbcrg generally proceeded on the principle of notifying eveiy
departure from any one form, assiuned to be specific, as representing another
species ; but this loose plan has been foimd productive of error and of ex-
cessive multiplication of species, inasmuch as shape, or outline, or markings of
the sui-face are not nearly so permanent and distinctive a.s formerly imagined.

Although in some species the size and figure seem pretty constant, yet in
many they are subject to endless variations. Prof. Gregory cites as examples
of changeablenoss" of form the three species, Ennotia (/ibba, Pimiuhria
clivergens, and Ilimanlldimn bidem ; and he woidd comprehend several pro-

OF THE DIATOMEiE.

97

Slimed species of Naviciilce under the name of N. variam. So again Dr.
Ciieville, speaking {A. N. H. 1855, p. 258) of the Grammato^hora C?) Bal-
fouriana (Smith), which he erects into a new genus Diatomella, observes,
" There is greater variation in the relative length and breadth of the fmstules
than would be likely to occur in other Diatomaeeous groups. In some the
length is more than equal to tmce tlie breadth, while others are exactly-
square ; and between these two extremes every gradation may be obseiwed ;
resembling in this inequality Fragilaria, Oclontidium, Grammatojjhory., and
other filamentous genera having piano-compressed frustules." ^ But in this
veiy case a ditference ai-ises between Dr. Greville and Mr. Smith respecting
the value of intemal markings as a characteristic distinction ; for the latter
author remarks, " The absence of a curve in its septa, relied upon by Dr.
Greville, I cannot regai'd as of sufficient importance to constitute a generic
distinction, as this featui-e is scarcely noticeable in some states of Gramma-
tophora macilenta, and is uniformly absent in G. stricta." (Synoj>s{s, vol. ii.
p. 44.)

" The si^e of the mature frustule " (says Prof. Smith, J. M. S. 1855, p. 1 32)
f before self-di^dsion commences, is, however, dependent upon the idiosyncrasy
of the embiyo, or upon the circumstances in which its embryonic growth
takes place; consequently a very conspicuous diversity in their relative
magnitudes may be usually noticed in any large aggregation of individuals,
or in the same species collected in different localities.

It may also be easily conceived that, while a typical outline of its cell
must be the characteristic of a certain species, such outline may to some
extent be modified by the accidental circumstances which surround the em-
bryo during its earlier growth and development. A lanceolate form may
become linear, elliptical, or even somewhat oval, by the pressure of surround-
ing cells ; and acute ends may be transformed into obtuse or rounded ex-
tremities.

. " Those who understand the process of self-division wall see here a suffi-
cient reason for the occurrence of multitudes of fmstules deviating from the
normal form, or even for the existence of myriads at one spot, all having a
form different fi'om the type, — the single embryo from which they have all
sprung by self-division (which process stereotypes the shape with which it
commences) having from some accidental circumstances become modified in
its outline.

" It foUows, then, from these considerations, that neither size nor outline
is sufficient to enable the observer to determine the species of a Diatoma-
eeous frustule. If he has the means of compaiing specimens in sufficient
numbers and from various localities, he may fix with tolerable certainty
upon the magnitude and form which may be regarded as the average and
type of the species ; but, without such opportunities, a reliance upon such
characters wiU inevitably lead to the undue multiplication of species and to
a confused and erroneous nomenclature."

In the construction of genera, similar difficulties present themselves. Thus,
Mr. Brightwell complains (./. M. S. i. 252)—" It appears as if we could carry
our real knowledge little beyond that of species ; and when we attempt to
define kinds and groups, we are met on every side by forms which set at
nought our definitions. With reference to the species of the present genus
(Tnceratium), loolring upon T. favus or T. mer/asfomum as what wo con-
ceive to be the most perfect plan (if any) on which this group is constructed
we find aU the species diverging from it, and canying us to analogous forms
in other groups, or lost m them. Placing the perfect triangular form of

98

GENEEAL HISTOHY OF THE INTUSOHIA.

T. favus in the centre, we may diverge in lines to a circumference ending in
one line, in the long-armed T. Solennoceros, itself nearly resembling Desmi-
dium tridens or D. hexaceros ; in another line ending in a form resembUng
Desmidiwm apiculosum ; in another like Zygoceros rhombus, especially in the
front view; in another analogous to Amphitetras antediluviana ; and in
another to Campylodiscus cribrosus."

Next after size and form, markings existing on the surface or within the
frustules have been employed as specific and generic characteristics ; but with
these, as with the former conditions, great imcertainty prevails in their ap-
plication, as we have already seen in the difference of opinion, regarding some
internal markings of O^-ammatophora, between Dr. Greville and Prof. Smith.
In like manner the character, the breadth, the relative position and distribu-
tion, the distinctness and the number of strijB on the valves, although
tolerably constant in some species, are, in the majority, subject to great
variation. Then again some naturalists coimt the number of striae in a
given space, as, for example, in the -nnjo-th of an inch, whilst others advo-
cate counting the entire number in the length of the valve. The latter plan,
to all appearance, must afford more certainty, although the trouble of it is
much greater ; for in the growth of frustules there would seem an expansion
of their walls, inducing consequently a displacement of the striae further
apart ; and observation does not confirm the opinion, that in the imperfectly
developed frustiiles a smaller number exists, which are added to in course of
growth.

However, just as in the case of the form and size, so, in this matter of the
superficial markings, there will be variations according as the frustules result
from self-division and are stereotyped impressions of an already existing'
form, or according as they originate from sporangial frustules and may have
an individual idiosyncrasy, or be modified in their development by the loeahty,
aid by surrounding circumstances, season and the like.

A writer in the Mic. Journ. (1855, p. 309) invites notice to another cir-
cumstance : — " Sufficient attention has not yet been paid to the sporangial
state of the Diatoms. From the observations recorded by Thwaites, Smith,
and others, different genera seem to foUow different laws on the subject. In
Navicula tliis state appears to be always accompanied by a great dilatation of
the frustule, and the formation of a strong line or band between the median
line and the margin ; sometimes the new line is neai-ly straight and parallel
to the median line, except near the nodule, with which it seems connected ;
sometimes it is curved ; but whether both sti-uctures occm- in the same
species, or are indicative of different species, no evidence has hitherto been
adduced Tlie strias appear, however, to preserve nearly the same in-
clination, to the new or intermediate lines which they did in the non-
sporangial state to the median Une ; and hence the direction of the striae is
not sufficient of itself to distinguish species, however good a character it may
afford, unless regard be had to the peculiar state of the fi-ustule."

Prof. Smith has endeavoured to frame some general lodes for the guidance
of naturalists in instituting generic and specific chai-actors, which we cannot
do better than subjoin in an abridged form {J. M. S. 1855, pp. 132-134 ; and
Synops. vol ii. p. xxii). In determming specific character, three circumstances
are of essential importance: 1. the stnictiu-e of the valve; 2. the habitat;
3. the arrangement of endochome in the living fr-ustule.

The first can be applied to both liAdng and dead or fossil specimens, and
affords the most constant and obvious characters. " These varieties of stnic-
turc arise from the modes in which the silex combines with the cellulose of

OF THE DIATOMEiE.

99

the epiderm ; and this combination seems to follow eertahi and invariable
laws, which ai-e subject to no derangement from the external circumstances
in which the growth of the embryo may take place. The structure of the
valve reveals itself in the chai-acter of the striation, which may therefore be
found a good specific distinction." Thus the strife may be costate or monili-
form, pai-allel or radiate, reach the median liue or be absent from a greater
or lesser portion of the siu-face, &c. The relative distances and the distinct-
ness of the strisB are also other features to be recorded, allowance being made
for the influence of localities and of age, and for the fact of their having
originated from the same or from different sporangia.

Next to striation in importance is locality, which will often aid to discri-
minate between closely allied forms, siace fresh- and salt-water species
cannot exchange habitats. Locality also seems even more restricted by other
external conditions of a more limited natiu-e.

Lastly, the arrangement of the endochi'ome confers a specific character
more certain than habitat. Examples of various arrangement of gonimic
substance, and of the large, constant, oil-like globules, have been already
given.

It follows, therefore, that the diflBlculty of defining species is much en-
hanced where examples occur only in a fossU state. Even in the living
state, shape and size cannot be implicitly relied on, but gatherings are re-
quired fr-om different localities, and every condition of growth observed, before
an average size or a typical outline can be. decided on. And although stria-
tion is an important guide, it often happens that this feature is so nearly
alike in allied species of the simple forms, such as Cocconema, Cymbella, and
Naviaida, that our determination must be influenced by less important con-
siderations, and the habitat, outline, and aiTangement of cell-contents all
require to be brought under review before we should feel justifled in consti-
tuting a species.

In the construction of genera, the several conditions (viz. form, size, stria-
tion, habitat, and disposition of endochi'ome) employed iu the determination
of species are also resorted to. Other peculiarities, however, are noted,
such as the transverse or longitudinal lines or bands, indicating thickenings
of the valves, the presence of a central spot (umbilicus) or of terminal ones,
and (as Prof. Smith mentions) " the obvious varieties of form or combination
to which the cellules submit in the progress of their formation, exhibiting
themselves as hexagonal, circular, or irregular in outline, as distinct from
each other, or as more or less confluent." {Synops. vol. ii. p. xxiv.)

Kiitzing has extensively used the cu'cumstance of the presence or absence,
the number and the position of apparent pores, not only in constitutiag
genera, but also the higher divisions, families and orders. The figui-e of
frustules on a transverse section, or an end view, is another point he has
resorted to in framing his classification. He would, indeed, appeal- to assign a
yet higher importance to the central spot or umbilicus than Ehrenberg him-
self, since he has distinguished his tribes Striatal and Vittatxe, respectively,
into two orders, Stomaticai and Astomaticce, according as this structural pecu-
liarity is present or absent. So, again, in the case of the Navicular frastules,
he has constituted Swrirella with some other genera into a family Surirellece
separated from Navicula, Pinnularia, and other genera, and placed in a dis-
tinct order of Striata;, because the former group is destitute of an umbilicus
(hence Astomaticm), which the latter possesses (the Stomaiicm) Moreover
as the family Na%aculeae, along with others, presented an umbilicus on each
valve of their fnistule, the term Distomatim was appUed to cUstiuguish them

H 2

100

GENEBAL HISTOET OV THE IWEUSOEIA,

from otlier families having an umbilicus only on one valve — Monostomaticce.
In this plan, therefore, Kiitzing assigned to the cii-cumstance of striation an
altogether secondary place to that of the existence of a central lunbilicus,
asserting that the presence or absence of transverse striffi Avas inconstant,
and therefore not to be xxsed in generic distinctions.

Meneghini critically reviews Kiitzing's system of classification, and points
out many anomalies and errors in it. " In the three proposed tribes," re-
marks this author, " we have unnatm'al dismemberments and associations.
The same conclusion prevails also in respect to the six orders, as weU as to
the ulterior divisions in the first two, taken from the continuity or inter-
ruption of the strise and the presence of one or two stomatic apertures " (op.
cit. p. 492). For instance, he asserts that the character of the median
apertiu'e, given as distiuctive of Tabellariece from Striatellece, is absolutely
false; and he doubts generally of the presence, constancy, and value of a
median aperture in fi-aming such distinctions as Kutzing has done. The
Actiniscece he would separate from the Diatome£E.

Again, proceeding on the principle that no one character can be allowed
an absolute value, he divides the Diatomese into two sections, the Actiniscece
and Loricatce. Of the latter he would create 8 families: — 1. Eunotiece;

2. Fragilariece (uniting with them the Mericliece, Striatellece, and Tahellariece) ;

3. MelosirecE, comprising the Coscinodiscece, Tnpodiscece, Angidiferce, Bid-
dulphiece, and Angidatce ; 4. Oocconeidece ; 5. AcJinanthece ; 6. Oymhellece ;
7. Naviculece (with all the SurirellecB) ; 8. OomphonemecB (with all the
Licmophorece, except the genus Licmophora)."

To the presence or absence of an external muco-gelatinous investment
around the silicious fnistules, this naturalist gave little weight in framing a
classification, reckoning it, together with the existence or not of a pedicle
or of concatenation, as scarcely admissible in the identification of species.

On. the other hand. Prof. Smith has employed these circumstances, con-
sidered in relation to the process of self- division, as the basis of his system
of classification. He would look to the phenomena of reproduction as the
most sure basis ; but in the absence of precise information, except in a few
instances, these are at present inapplicable, and self-division seems to liim
" to come next in order, as a most important function connected with in-
crease and growth, and to supply the necessary variety of phenomena on
which to ground our sectional divisions." And he thus proceeds to explain
his plan (Synops. i. p. xxviii) : —

" I have therefore separated those forms where self-division is accom-
panied by the secretion of a pennanent gelatinous or membranaceous envelope,
in which the fnistules are subsequently imbedded, from those in which such
secretion is altogether absent, or is represented merely by a cusliion or
stipes, to which the frustules ai-e attached by a small portion of their sur-
face ; and I have placed the latter, as of simpler organization, in my first
tribe, arranging the genera belonging to it into subtribes, depending upon
the permanency or otherwise of the connecting-membrane, another product
of the self-dividing process. This enables me to place apart those genera
whose species present us Avith frustules in which the union of the cells is
dissolved almost immediately upon the completion of self-division, as well as
those where a cushion or stipes stiU maintains a kind of indirect individuality
in the divided frustules, from the genera in which the cells cohere after
gemniiparous increase, and by such coherence form filaments of various
lengths and forms, allotting the latter to subtribes wliich respectively pre-
sent a compressed filament, a zigzag chain, or a cylindrical thread. In the

or THE DIATOMEiK.

101

second tribe, including those genera which have frondose forms, I find cha-
racters for my subti'ibes in the natiu'e of the frond and the arrangement of
the frustules.

" I do not propose this arrangement as fi'ee from exceptions or even serious
defects ; but I have adopted it in preference to those hitherto given, as bring-
ing more frequently together forms allied in structui'e and mode of growth,
and as being at the same time more strictly in accordance veith the external
physiognomies of these organisms, and therefore more likely to be appre-
hended by the inquirer entering upon the study of this department of nature.
A wider study of Diatomaceous forms will doubtless lead to more accurate
and more natiu-al generalizations."

We subjoin the systems of classification proposed by Kiitzing and by
Smith. The fonner is presented in a tabular form—

DIATOME^.

Tribe I.
Striata).

Tribe II.
Vittatoe.

Tribe III.
Areolatie.

Order I.

ASTOMATIC^.

Without a central -
opening on the
secondary side.

* Transverse strioe unbroken.
Family 1. Eimotieae.

2. Meridiess.

3. FragUarieae.

Striae broken (interrupted) in the median Une.
Family 4. Melosirese.

Order II.

StOMATIC;!!.

With the central
opening.

Order I.

ASTOMATIC/E.

Without median
apertm'e on se-
condary side. /

Order II.
Stomatic/E.
With a large dis-
tinct one.

Order I.

DlSCIFORM^E.

Order II.

' ApPENDICULAT/E.

Appended doubt-
ful forms.

5. Surirellese.

a. MoNOSTOMATICiE.

Family 6. Cocconeidese.
7. Aohnantheae.

b. DlSTOMATICai.

f Having a median aperture on only
\ one of the two secondary surfaces.

Family 8. Cymbelleae,

9. Gromphonemeae,

10. Naviculeae.

11. Licmophoreas.

12. Striatelleae.

/With a median aperture on each
\ secondary surface.

13. TabeUarieas.

14. CoscinodiscesB.

15. Anguliferffi.

16. Tripodisceije.

17. Biddulpliieas.

18. Angulatae.

19. Actinisceae.

The Synoptical Table of Prof. Smith contains only those genera then
known m Britain ; but since the date of its pubUcation not a few othcra
have been added to the Hst.

Class CRYPTOGAMIA.

Subclass ALG^. Natujbal Order DIATOMACE^.

Plant a Fkustule; consisting of a unilocular or irapcrfectlv sontntA or^^
invested with a bivalve silicious epidermis. ^..^J^^fl^ZZ, by

102 GENEEAL niSTOET OF THE HTFTTSOEIA.

Self-Divisiok ; during whicli process the cell secretes a more or less sili-
cious CoNKECTrNG Membeane. Eepbobtjction, by Conjugation and the
formation of Sporangia.

Teibe I. Fmstules naked ; not imbedded in gelatine nor enclosed in mem-
hranaceous tubes.

Stjbtkibe 1. Connecting membrane deciduous ; fmstules solitary or du-
ring self-division in pairs, rarely in greater numbers,
adherent or free, dispersed, or aggregated into a mucous
stratum.

22 Geneea. Epithemia, Eunotia, Cymbella, Amphora, Cocconeis,
Coscinodiscus, Eupodiscus, Actinocyclus, Arachnoi-
discus, Triceratium, Cyclotella, Campylodiscus,
Simrella, Trybhonella, Cymatopleura, Nitzschia,
Amphiprora, Amphipleura, Navicula, Pinnularia,
Stauroneis, Pleurosigma.

SxTBTEiBE 2. Connecting membrane subpersistent j frustules after self-
division attached by a gelatinous cushion, or dicJwto-
mous stipes.

7 Geneea, Synedra, Doryphora, Cocconema, Gomphonema, Po-
dosphenia, Rhipidophora, Licmophora.
SuBTEiBE 3. Connecting membrane evanescent, or obsolete ; frustules after
self-division united into a compressed filament.

12 Geneea. Meridion, Bacillaria, Himantidium, Odontidium, Den-
ticiila, EragUaria, Eucampia, Achnanthes, Achnan-
thidium, Ehabdonema, Striatella, Tetracyclus.

SuBTEiBE 4. Connecting membrane subpersistent ; frustules after self-
division united into a zigzag chain.

6 Geneea. Diatoma, Grammatophora, Tabellaria, Amphitetras,
Biddulphia, Isthmia.

SuBTEiBE 5. Connecting membrane subpersistent as a silicious amiulus ;

frustules after self-division united into a cylindrical
filament.

3 Geneea. Podosira, Melosira, Orthosu-a.

Teibe II. Frustules invested with a gelatinous or membranaceous envelope.
SuBTEiBE 6. Frond indefinite, mammillate ; frustules scattered.

1 Genus. Mastogloia.

SuBTEiBE 7. Frond definite, compressed or globular ; frustules scattered.

2 Geneea. Dickieia, Berkcleyia.

iStTBTEiBE 8. Frond definite, filamentous ; frustules in rows.

3 Geneea. Encyonoma, Colletoncma, Scliizonema.
SxJBTEiBE 9. Frond definite, filamentous ; fi-ustules fasciculated.

1 Genus. Homoeocladia.

On the Mode of obtaining Diatomej;. Peepaeatton of Diatomaceous
Deposits mixed with Mud oe in inE Fossil State. Peeseevation of Spe-
cimens.— Many hints on the obtaining of specimens of Diatomese are seal-

OF THE DIATOMEiE.

103

tercd in previous sections of this history of the Order, particularly in that
on their habitats (p. 75) ; yet, to make the dii-ections complete, additional
details ai'e necessary.

^Miere Diatome* in the living state exist in any considerable number,
they usually form a brilliant cinnamon, or sometimes an oUve-brown film or
patch, and thereby become visible to the naked eye or to an ordinaiy lens,
adherent to vaaious water-weeds, to decayed portions of wood, leaves, or
other floating substances, or as a patch on the mud at the bottom, or other-
wise floating on the surface of the pond as a scum or film. Besides such
positions and such collections, Diatomese exist diffused more or less abun-
dantly thi'ough the water or in the mud itself (see p. 75 et seq.).

When seen adherent to an aquatic plant, the process of collection is very
simple — by carefuUy gathering or removing the plant from the water and
washing it to detach the Diatomaceous frustules, if these cannot be more
advantageously viewed whilst stiU adherent to its stem or leaves. So, too,
where, mostly in conjunction with other organisms, the Diatomete float in
mass, Hke a scum on the surface, nothing is easier than to lightly skim the
collection from the surface. But when the layer of frustules reposes on the
surface, or is more or less intermixed with the mud, some additional pre-
cautions are required in their collection, unless indeed the film has sufficient
tenacity, by cohesion of its component frustules, as in the case of Schizonemese,
to allow of its being raised en masse upon some thin flat instrument, a spoon
or spatula, insinuated beneath it.

The general methods of collection applicable to the Desmidieae and other
minute Algse are equally so to the Diatomese, whilst various modifications
will suggest themselves to the mind of every practical naturalist to meet the
vaiying circumstances under which he makes the collection. Mr. Ealfs has
kindly famished us with notes on this point. He ^v^ites — " It is often
difficult to procure clear specimens of those species which form strata on
mud ; most of them, however, can be obtained, tolerably free from the mud
on which they congregate, by the following method, which is applicable both
to those found in maiine situations and to those gathered fi-om the wayside.
When the water is somewhat diied up, if the finger be pressed upon the
stratum with a gentle force, the Diatomaceae will adhere to the finger, and
may then be removed by scraping them off upon a piece of Linen folded over
the edge of a tin box or of a knife ; by repeating this process, a sufficient
quantity can easily be collected. At first, probably, a portion of mud, espe-
cially if very wet, will also be taken up ; but a little practice wUl soon show
the force requisite for places where the water is plentiful, and for those
where it is nearly dried up. Specimens thus collected can be prepared for
mounting with much less trouble than if gathered mixed witli a large quan-
tity of dirt."

When it is wished to captiiro frustid.es diffused in water, a piece of muslin
may bo used as a filter, just as for Desmidicaj, and the residue left upon
it examined as it is, or, if required, washed, to detach foreign matters mixed
with it. Where some adraixtiu-e of mud is imavoidable, frequent washing of
the collected substance wiU often suffice to separate sufficiently the silicious
frustTilcs from the other particles — the heavier grams of sand sinking to the
bottom of the vessel, while the Diatoms are still suppended in the fluid ; and
on the other hand, the decayed organic and other matters, lighter than the
frustules, will remain in the supernatant liquid after the latter are precipi-
tated, llepeatcd careful decanting and washing may be aU, therefore that is
required. '

Another method applicable to recent linng specimens, dependent on the

104

GENEKAL DISTOET OF THE INFUSORIA.

tendency towards the Ught, at least, of many species, may be adopted by
placing the half-liquid mud in shallow pans or plates in the sunshine, when
many species may be found to rise as a him on the surface, or to congregate
near the edge or sides of the vessel.

When the finistules are much intermixed with mud, which is, under cer-
tain circumstances, inevitable, various plans have been adopted for separating
them^ for examination. Mr. Okeden details the following plan, which, with
certain modifications to be mentioned, has been described also by Dr. H.
Munro : —

" The plan " {J. M. S. 1855, pp. 158, 159) " consists in making the deposits
fall thi-ough a constant depth of water, in various periods of time ; thus
dividing the Diatoms, according to their sizes, into portions of several dif-
ferent gravities." It is thus carried out : " Take about a cubic inch of the
clay to be examined, digest it for about four hom-s in strong nitric acid at a
moderate temjjerature ; now add gradually an equal quantity of hydrochloric
acid, eflPervescence takes place, a further action on the clay ensues ; keep
boiling for about thi-ee hours more, occasionally stirring, and then allow the
mixture to cool and settle down, which it will do in about an hour ; pour off
the superfluous acid and wash the residue repeatedly with water, so as to get
rid of the remaining acid.

" The next operation is to divide the sediment into portions of various
specific gravities : for this piu-pose it is necessary to have several beakers,
about 3 or 4 mches in height, and about 1-^ to 2 inches in diameter ; also
one very large beaker, about 6 to 9 inches in diameter : we will caU the large
beaker A. Wow transfer the sediment into one of the small beakers, and
pour in water tiU there is just 2 inches depth of water in the glass. Stir,
and let stand half a minute by the watch, and then pour off carefully into
the large beaker A ; repeat this about half a dozen times, each time poiu'ing
off into A aU that does not fall through the 2 inches of water in the half-
minute, and at last the small beaker avlQ contain only what falls thi'ough
2 inches of water in half a minute. Now let A stand about half an horn-,
pour off carefully, and transfer the sediment in A to another small beaker ;
put 2 inches of water with it, stir and let stand for 2i minutes, then pour
off into A. Eepcat this about six times, and there will now be another small
beaker containing aU that falls through 2 inches of water in 2^ minutes,
while in A is aU that does not fall through that distance in that period. Let
A stand half an hour, pour off and transfer the sediment to another small
beaker, stii' and let it stand ^^ve minutes, pour off into A as before, and repeat
this as before about six times. There is now another beaker, containing all
that falls through 2 inches of water in 5 minutes. After this I do not didde
them any fni'ther, but call the last remainder, or what remains in A after
it has stood its half-horn-, ' Not in five minutes.' Thus we have four
different glasses, containing Diatoms and clay mixed, of foui- different densi-
ties : thus, 0 to i ; | to 2^- ; 2i tO 5 ; not in 5. There is now a method of
concentrating the coarsest of these sediments, namely the 0 to ^, the ^ to
21, and sometimes the 21 to 5. It consists in taking the beaker containing
the sediment and pouiing about an inch of water on it. Let it settle about
5 minutes, and then place tlie glass on a table, and impart a whirliiig motion
to the whole by moving it roimd and roimd, when the greatest portion of the
Diatoms will rise up in a sort of eddy, while the particles of mud or sand
will remain at the bottom, even though they arc of the same specific gra\-ity
as the Diatoms, and have fallen through the same distance of water in the
same time. This is because tlie Diatoms are mo^ily jl^t and thin, wlule the
particles of sand and mud ai-c roimd ; in the same way, if we take a round

il

OF THE BIATOMEiE,

105

pebble and an oyster-shell both of the same weight, and throw both hon-
zontally into the water, the pebble will reach the bottom sooner than the
oyster-sheU. So, when the whirling motion is imparted to the glass, the thin
flat shells of the Diatoms wiU rise up in a cloud, whUe the round particles of
mud and sand -ndll remain behind; when the cloud rises up, pour it off quickly
and dextrously into another glass, and, if necessary, repeat the process ; and
a httle practice moU enable the operator to separate all the Diatoms most
effectually. I have said before that this process will only apply to the 0 to |,
^ to 2i, and sometimes the 2^ to 5 sediment, but not to any finer one ;
practice will soon teach this. The ' not in 5 ' cannot be concentrated — it is
too fine, and the whole rises together on imparting the whirling motion to it.

" It is not necessary to abide invariably by the divisions of time which I
have given here.

" These must be varied, of course, according to the nature of the clay to be
examined. For instance, ra a clay I have recently tried from 34 feet below
the bed of the river at Cardiff, neaiiy the whole of what was left after the
0 to -i- fell in the -I- to 2^. I therefore divided it thus : 0 to -I-, to 1^, and
to 2-i ; a little practice will soon teach this.

" The advantages of the plan are, I think, obvious. In the first or coarsest
sediments we get all the larger and finer Diatoms by themselves, unmixed
with, and consequently unobsciu'ed by, the innumerable smaller ones and
the fine particles of mud and sand, while, if any of them, such as the Evjpo-
disci or Campylodisd, are rare, they are sure to be found in either the first or
second division of densities, and by their being concentrated and brought as
it were tuto a small compass, the detection of them is easy and certain.

" In the next division, or the 2-1- to 5, we shall find the moderate-sized
Diatoms ; and lastly, in the ' not in 5,' we get a mass of the remaining eind
smaller Diatoms, all of which small ones are themselves the more readily seen
and identified when separated from theii' larger brethren.

" I would venture to add, moreover, that I think the examination of these
deposits for the various species is much facilitated, as the slides containing
the 0 to sediment may be examined with the inch objective, the i-inch
will do to examine the to 2^ and 2^- to 5, while the l-inch need not be
used till we come to the ' not in 5 ; ' whereas, were they all mixed, the -i-ihch
would be reqidred to examine the whole.

" I should add, that what is pom-ed off the large beaker A, after it has
stood the half-hour each time, may be flung away and the sediment only
transfeiTed to the small beakers, as from the large size of it there "SAill rarely
be more than 2 inches depth of water in it, and half-an-hovu' is ample time
to ensure every chatomaceous particle falUng to tlic bottom and being pre-
•served and detected in one or the other of the divisions."
■ Dr. Munro's plan is a variation of the above proceeding, and is thus de-
tailed (/. M. S. 1855, p. 242) : " I first boil the deposit in strong hydi-ocliloric
acid for five or ten minutes, then allow it to subside, pom- off all tlic acid, and
by a few washings get as much of it away as possible ; then treat the deposit
•in the same way ^^^ith. strong nitric acid, washing the deposit by repeated
washings to get rid of the remaining acid. "When this is done, I then sepa-
rate the Diatoms according to their different gravities by allo-ning them to
pass through a column of water in the following manner : —

" 1 take a long glass tube about four feet long mid half an incli in bore
At the bottom of this tube is fixed a stop-cock to enable me to let out any of
the Diatoms during any stage of the process. Having nearly filled this tube
with distilled water, I pour in my deposit washed free from the acids I
watch the deposit as it falls slowly and gradually down the tube, and with a

106

GENEEAL HISTOBT OF THE UfFtTSOMA.

Coddington lens can easily detect the larger Diatoms as they are precipitated.
In about a quarter of an hour, many of the larger forms wiU have descended
to the bottom of the tube. By turning the tap at the bottom of the tube, I
let out a drop of the mixtui'e on a sHde, and examine it -wdth a low power
(■1-inch) ; and if it be tolerably clear, and the Diatoms of one character, I then
let off five or six inches of the mixture into a test-tube, and set it aside for
re-examination after the Diatoms have subsided. In a quarter of an hour
more, I again let off into another test-tube six or eight inches more of the
mixture, and place it aside to settle. In half an hour more I let off into
another test-tube six or eight inches of the mixture, which will contain the
finer Diatoms by themselves, generally free fi-om all mud and sand. I then
pass each of these washings again through the long tube of distilled water ;
and by examining the mixture during the process of its subsidence, I am
enabled to let out the heavier particles of sand or mud, and to obtain pretty
clean all those Diatoms Avhich are alike in size, or at all events in specific
gravity. Some Diatoms take a longer time than others in settling to the
bottom of the tube, and separating themselves from extraneous matter, such
as the Nitzschia, Closterium, &c. ; but, by a little patience, and an extra
washing through the tube, these difficiilties may, in a great measure, be
overcome. By this method, I have found the Pleurosigmata, Pinnulai-ice,
Surirellce, and Synedrce yqtj well separated, those of a Uke character being
found together. I have been stimulated to send these few remarks on the
washing of Diatomaceae, on aecoimt of the great difficulty I have hitherto
experienced in procuring slides free from mud, sand, and other extraneous
matters."

Mr. Okeden offers the following plan for obtaining specimens imbedded in
mud at considerable depths, in making borings for engineering purposes. He
prefaces the description of his apparatus by that of the usual boiing ap-
paratus, wliich " consists essentially of any number of iron rods " (J. AT. S.
1854, p. 26), "which screw one into the other ; to one of these is screwed an
auger or a chisel-point, as the case may reqxiire. This is inserted into the
ground to be tested, and worked round by manual force and downward pres-
sure, length after length of rod being added as the ground is penetrated. In
addition, then, to this apparatiis, I obtained, first, several lengths of wrought-
iron gas-pipe, about an inch in diameter, and each screwing into the other :
and also a similar number of iron rods, each a few inches longer than the
lengths of gas-piping, and each also screwing into the other : to the end of
one of these lengths of rod is attached a cork of the exact diameter of the
gas-pipe, or a trifle larger. This cork is fixed by a washer and nut. The
gas-piping should be in lengths of about 8 feet each, as this is the most con-
venient in work : one of these lengths should also be again divided into two
parts, which must, however, screw and unscrew ; and this length is to be
the one Jirst put into the ground or mud, for reasons which I will presently
explain.

" The mode of proceeding is as follows : Fii-st, a hole is bored to the required
depth — say 20 feet — with the usual boring apparatus : this done, the appa-
ratus is drawn out, the jointed length of gas-pipe is now introduced. — the end
of it, with the rod to which the cork is attached, liaving been previously
stopped, the rod passing up the centre of the gas-pipe ; this is let down the
hole, another length of pipe being attaclicd, and another length of rod, and
so on, length after length of pipe and rod, until the bottom of the hole is
reached. We shall thus have a continuous length of gas-piping, which will
be penetrated by a continuous length of iron rod attached to the cork at the
end of the pipe. It is obWous that this cork wiU entirely prevent any foreign

OF THE DIATOMEiE.

107

matter from entering the gas-pipe. Having thus reached the bottom of the
hole, now pull up the cork into the gas-pipe about 4 feet, by means of the
rod attached to it, and then press the whole appai'atus into the' soft mud.
The' pressiii-e will now drive the mud up into the pipe as far as the cork is
drawn, up. Now remove the whole apparatus, and by means of the rod push
the cork back again to the end of the last length of pipe, when the charge of
mud will be diiven out in the form of a sausage ; and by rejecting the two
ends of it, and taking only the middle piece, we may be perfectly sure that
the mud at that depth, and that only, has been obtained.

" Having secured the prize, the short length of piping which contained it
is now to be imscrewed, and carefully washed with a common g-un-cleaning
rod and some tow, when it is ready for another experiment.

" With this apparatus, then, I have penetrated Neyland mud in various
places to depths of 20, 30, and 40 feet."

The Diatomeae existing often so abundantly in Guano may be separated on
a simpler plan to that pursued in the case of sedimentary deposits and col-
lections of fossil specimens. The proceeding is always preceded by several
washings in clear water, and by pouring it off carefully, after allowing
a sufficient time for the insoluble and more weighty particles to subside.
The subsided matter is then treated with hydrochloric (mimatic) acid several
times, — a due interval beiag allowed for the cessation of eflPervescence and
for the sohd particles to settle before the decanting of the liquid and the ap-
plication of a fresh quantity. "When the muriatic acid ceases to produce any
chemical action, as evidenced by effervescence, nitric acid should be substi-
tuted and used in a similar way two or three times, and the mixture raised
to nearly or quite a boiling heat, after which the powder collected at the
bottom of the vessel — a conical one should, by the way, be preferred, such as
chemists know by the name of " precipitate glasses " — ^is to be washed re-
peatedly in pure water. The resultant substance will be found to be com-
posed of silicious particles, which are either Diatomaceous frustules or the
siLicious spicules of Sponges.

Prof. Bailey, in a recent number of SilUman's Journal, 1856 (p. 145), re-
commends the following method of cleaning Diatomaceous deposits, as more
speedy and efficacious than any other he has tried, whether mixed with
sounings, guano, or with mud, &c. : — " Dissolve out the lime compounds, if
present, by means of nitric or hydrochloric acid, wash, and filter. Then put
the moist contents of the filter into a porcelain capsule with enough strong
sulphuric acid to make the whole a fluid mass. Heat the capsule over a spiiit-
lamp until the organic matters are all chaiTed, and continue the heat until
strong acid fumes are evolved. Keep the capsule hot, and add, in minute
portions at a time, finely powdered chlorate of potassa. If the acid is hot
enough to give off fumes, the chlorate wiU be immediately decomposed -with-
out the accumulation of explosive gases, and it will exert so powerful an
oxidizing action, that in a few moments a carbonaceous material as black as
ink wHL become perfectly clean and colourless. Nothing now will remain to
be done but to wash off the acid, which is best done by the addition of water
and repeated deeantations. I would also advise that the materials thus cleaned
shotdd not bo cMcd, but should be kept in bottles with a little alcohol, which
prevents their felting together, and does not aUow the growth of the byssoid
plants which often develope in water.

" It is nccessaiy to caution those not familiar with chemistiy against using
the chlorate of potassa with siUphnric acid in any other way than above di-
rected, as violent and dangerous explosions might result. The process as
•above given is perfectly safe and veiy effective."

Another plan of separation of the sliclls of Diatomeffi or of Foraminifera

108

OENEEAL niSTOET OF THE INFUSOEIA.

is successfully adopted by Prof. Bailey and D'Orbigny, and is thus described
by the former {Proceedings of American Assoc. for the Advancement of Science,
1849, p. 409) : — " Where the mixtm-e of inorganic matter is in large propor-
tion to the Infusoria and other microscopic organisms, and corresponds nearly
in specific gravity," the deposit is to be thoroughly dried, whereby the minute
unbroken shells will become filled with air, and consequently when rapidly
stirred up with water they will be buoyed up, and continue suspended after
the intermixed sand has settled at the bottom. They may then be easUy re-
moved from the siuface and transferred by alternately touching the siuface
of the water with the finger, and the glass slide on which they are to be placed.
The sediment, if dried again, will often yield another abundant supply of the
minute shells. " By the above means," adds Dr. Bailey, " I have obtained
exquisite specimens from the bottom of dried-up ponds, from the sands of
harbours, and from the mud attached to floating ice in the Hudson River, —
materials presenting the two extremes of very eoai-se gravel and the finest
sediment, neither of which would have given good results by any other
process."

In the case of some deposits the shells of the Diatomaceae are so far the
chief constituents, that no preparation is needed before subjecting them to
microscopic investigation.

The cohesion of Diatomaceous deposits is at times so great that a difficulty
is encountered in separating them. A method of dealing with such is de-
tailed by Prof. Bailey {Sill. Journ. 1856, p. 356) : — " Many masses of fossil
DiatomaccEe are so strongly coherent, that they cannot be diffused in water
(for the purpose of moimting in balsam) without a degree of mechanical vio-
lence which reduces to fragments many of the most beautiful and interesting
forms. This is particularly the case with some specimens from the ' infusorial
deposits ' of California. Some of these I endeavoured to break up by boiling
in water and in acids, and also by repeated freezing and thawing when moist-
ened, but without good results in either case. At last it occurred to me that
the adherence might be due to a slight portion of a silicious cement, which
the cautious use of an alkaline solution might remove without destroying any
but the most minute shells of the Diatoms. As the case appeared a desperate
one, a ' heroic remedy ' was appKed, which was, to boil small lumps of the
Diatomaceous mass in a strong solution of caustic potassa or soda. This proved
to be perfectly efficacious, as the masses under this treatment rapidly split up
along the planes of lamination and then crumbled to mud, which, being im-
mediately poured into a large quantity of water, ceased to be acted upon by
the aUiali, and gave, when thoroughly washed, not only all the large shclLs
of the Diatoms in a state of unhoped-for perfection, but also furnished abim-
dance of the minute forms. Having obtained by this method highly satis-
factory results from specimens from many localities, I can confidently recom-
mend it as an addition to our modes of research.

"The following directions will enable any one to apply the process: — Put
small lumps of the mass to be examined into a test tube, with enough of a
solution of caustic potassa or soda to cover them ; then boil over a spii-it-lamp
for a few seconds, or a few minutes, as the case may rcqiui-c. If the solution
is sufficiently strong, the ma.sscs -n-ill rapidly crumble to mud, which must be
poured at once into a large quantity of water, which, after subsidence, is re-
moved by decautation. If the mass resists the action of the alkaline liquor,
a still stronger solution should be tried, as, wliile some specimens break up
instantly in a weak solution of allcali, others require that it should be of tlie
consistence of a dense sjTup. Tlic mud also should be poiu-ed off as fast as
it forms, so as to remain as short a time as possible in the caustic ley.

"The only specimens which I have found not to give good results by the

OF THE DIATOMEiE.

109

method above described, are those from Tampa Bay, Florida, and_ the infii-
sorial marls from Barbadoes. In the masses from Tampa the lapidification is
so complete that the alkali destroys the shells before the lumps break up ;
and in the case of the Barbadoes marls the cementing material is calcareous,
and requires a dilute acid for its removal. In applying the above process,
one caution is necessary, which is to thoroughly wash the sheUs with water,
and not with acids, as the latter ^ill cause the deposit of a portion of the
dissolved silica, and materially injui-e the beauty of the specimens. When
the washings are no longer alkaline, the specimens may be thoroughly
cleansed by acids, or by the chlorate process described above."
• A very ingenious plan of getting transverse and oblique sections of Dia-
tomaceous shells is mentioned by Schleiden {Principles of Botany, translated
by LanJcester, p. 594), which is precisely similar to that for obtaining trans-
verse sections of hair, as first given in PritcharcVs Microscopic Objects. It
consists in mixing any very piu'e deposit with mucilage, and, before the
mixtiu'e is completely hardened, cutting oif delicate slices with a razor or
sharp knife. The preservation of Diatomete for examination is, on account of
their sOicious composition, easy ; and it is only in the case of the stalked, fila-
mentous, and frondose species that any special arrangements are necessary —
except, indeed, those demanded in order to mount them as permanent micro-
scopic preparations.

Before the structure of the silicious epiderm can be made out, the endo-
chrome of living specimens must be destroyed, which can be effected by heat-
ing the fnistules on a piece of talc or platinum-foil. But where it is wished
to preserve them in a fresh state, so that their natural Kving appearance may
as far as possible be retained, immersion in creosote and water is recom-
mended by Mr. Shadbolt. Prof Smith, however, finds distilled water supe-
rior to any mixture, which is not merely unnecessary, but injurious. " If,"
says the author last mentioned, " the filamentous and stipitate forms are not
mounted in a fresh state, the frustules separate fr'om each other, part from
their stipes, and lose their characteristic appearance. To remedy these in-
conveniences, I immerse such specimens as cannot be placed in cells when
freshly gathered, in spirits of wine and water, one part of the foi-mer to six
of the latter ; and theii' attachment to their stipes remains afterwards undis-
turbed, unless violence be employed t6 separate them."

FossU, and chemically-prepared and dried specimens are usually presei-ved
in Canada balsam, which is heated and rendered fluid, so that it enters within
the cavity of the frustules. The fluidity of the balsam is increased by the
addition of a little t"urpentine or rectified spiiit. The presence of balsam
however, obscures the marldngs of the sUicious epiderm ; and it has been
found better, where the resolution or determination of the supei-ficial sculp-
turing is very difficult, to moimt the frustules, in a dry state on a thin
object-glass, and imder cover of a very thin piece. " To prevent the admis-
sion of moisture, which would ultimately make its way to the object and de-
stroy its value, it is indispensable that the cover should be cemented to the
thin glass below." {Synops. i. p. xxxii.)

In a collection of Diatomeffi, wo may, by a magnifier, such as a Coddino-ton
lens, select certain specimens from the rest to be mounted. Tliis can be
effected, when the size permits, hj the projecting terminal hairs of a fine
camel-hair pencil, or by the moistened tip of a needle ; but if the shell be
too minute for this, a single stout hair or bristle will frequently suffice and
more satisfactorily and reathly if the hair be split at the end Pi-of Bedfem
of Aberdeen, pointed out the advantage of spUt hairs for the pui-pose 'in n binVf
communication to the ./. M. S. 1853, p. 235. He recommends a haii- split

110

GENERAL HISTOHY OF THE IITFUSOEIA.

into three to five or six parts at one extremity, to be fixed by the other in a
piece of cork, and held in a common needle-holder. Such split hairs are com-
mon enough in an old shaving-brush ; but the divergence of the split portions
should be so slight that, until pressed upon, the hair should appear single and
unbroken. He has also found entire hairs very useful when set in needle-
holders in a similar manner. The spUt hairs act like forceps, expanding by
pressure so as to embrace the object, and closing upon it by their elasticity
when the pressui-e is withdrawn.

To select certain portions of a collection of Diatomeae from others. Dr.
Cai'penter gives these directions {The Mio'oscope, p. 340) : — " Either of the
two following modes may be put in practice. A smaU portion of the sedi-
ment being taken up in the dipping-tube, and allowed to escape upon the
slide, so as to form a long narrow line upon it, this is to be examined with
the lowest power with which the object we are in search of can be distin-
guished ; and when one of the specimens has been found, it may be taken
up, if possible, on the point of the hair, and transferred to a new slide, to
which it may be made to adhere by first breathing on its surface. But if it
be found impracticable thus to remove the specimens, on account of their mi-
nuteness, they may be pushed to one side of the slide on which they are
lying ; all the remainder of the sediment which it is not desired to preserve
may be washed off ; and the objects may then be pushed back into the middle
of the slide, and mounted in any way that may be desired." See GoHiifG and
Pkitchakd's Microscopic Illustrations, Microscopic Cabinet, and Micrographia
for much original information on these matters.

or THE PHTTOZOA.

Ill

Sect. II.— OF THE PHYTOZOA.
(Plates XVni. XIX. XX. and XXVI.)

The Beings incltided undee this Name: theik Geitebal Chahactee. —
DryisioN into Geoups oe Teibes. — The collection of microscopic beings we
would comprehend under the term Phytozoa comprises most of the Anentera
of Ehrenberg, with the exception of Amcebcea, Arcellina, Dinohryina, Bacil-
laria, Clostenna, PericUnicea, and Cyclidina. After excluding these families,
there remain Monaclina, Cryptomonadina, Hydromorina, Volvocina, Vibn~
onia, and Astasicea, which, although they exhibit great diversity among
themselves, nevertheless have certain characters in common, whilst their
mutual differences in essential particulars of organization and vital endow-
ments are less than those separating them from the ciliated animalcules. On
the other hand, they — at least the majority — exhibit very marked genuine
afl&nities with the Diatome^ and DESMiniEiE as plants. In point of fact,
these organisms stand on the confines between the animal and vegetable
kingdoms,— some genera distinctly belonging to the latter, others doubtfully
to the former, whilst many pass through such phases of existence that at
one time they assume the characters of animals, at another those of plants.

This apparently mixed animal and vegetable nature is expressed by the
term Phytozoa, derived from two Greek words, signifying plant-animals.
Another term, used by Perty, viz. Phytozoida, is a simple expansion of the
word Phytozoa, signifying literally ammsl-like plants. Cohn employs in its
stead the term Flagellata, derived from the locomotive organ or Jlagellum
which most species possess, whilst others prefer the word Flabellifera.

In the opinion of the majority of modem wiiters, the Phytozoa are in
general undistinguishable from unicellular Algse, among the different families
of which they consequently seek to distribute them ; and doubtless the
creation of such a group is purely artificial, and cannot be admitted in any
attempted philosophical or natural classification of microscopic organisms.
However, since so much uncertainty and dispute stUl prevail on the question
of the animal or vegetable nature of very many, and since our knowledo-e of
the phases of existence of a large nimiber is so imperfect, it is really impos-
sible to establish any satisfactory classification. On this account, and also to
bring together for convenience' sake a mass of information respecting several
collections of beings enumerated among the Anenterous Polygastrica of
Ehrenberg, difficult or impossible to arrange under any other heading, we
resort to this artificial division, and in so doing have the example of Perty
and other writers. After describing what can be predicated of the Phytozoa
in general, wo shall find it necessaiy to consider them under several sections
or tribes, by reason of the differences which prevail among them in form
mode of growth, and other particidars ; and in speaking of each tribe shall
point out its general affinities to the others, and to any families of Infusoria
or of ^Ugse.

FiouEE. CovEEiNGS OF PiiYTozoA.-Tho Phytozoa are of more simple
organization and of less varied outlme than the ciliated Protozoa In ficure
they are commonly round, or oval, or eUiptical, and either present no processes

112

GENERAL HISTORY OF THE INFUSORIA .

or only nn elongated neck bearing one or more cilia (Jlabella) to sei-ve as
locomotive organs.

How greatly their figure and size are dependent on the external influence
of light, is well shown by some recent researches of Cohn on Steplianosphcera
{Nov. Act. Acad. Curios, xxvi. 1857). On placing specimens of this organism,
some in transparent glass vessels, others in semitransparent and green ones,
others in porcelain, and others again in perfectly opaque cups, the modifica-
tions in size and figure, according to the intensity of light they received,
were altogether incredible. In the opaque vessels, where they got little light,
the greenr cells remained delicate, small, and widely dispersed, whilst in the
transparent glasses, under sunlight, they became many times larger and
crowded together, and theii- figure fusiform, irregular, and produced into
numerous protoplasmic processes. Indeed, on placing two portions of the
same collection of Stephanosphcera-glohes, the one in a transparent, the other
in an opaque vessel, the swarming individuals in the two will be- found so
unlike that they might be readily conceived to be different species.

The outHne is fixed where the organism has a finn envelope ; and most of
the Phytozoa have such in one phase of their existence, viz. when they undergo
the encysting-process. We are not acquainted with the entire history of
many genera ; but from what we know of some, we may argue by analogy of
aU, that in the eai'liest stages of existence these cellular organisms have no
distinctly organized wall, although they may have a pellicle derived fi'om the
contact of the protoplasm, of which they consist, with surrounding media, — a
mere superficial indm-ation, but no separable membrane. Such is true of the
individual cells of Volvox (XX), of Euglena (XVIII. 45, 46), and of Monads
(XVIII. 1 to 28) in general. Subsequently a cell- wall, the primordial mem-
brane or sac, may be produced, distinct and separable fi-om the contained
substance. Pui'thermore, many examples do not stop here, but proceed
to throw out a second wall exterior to the last-named, sepai-ated frequently
from it by a small interspace, and having a much denser and firmer consist-
ence. The cell, or, as Prof. Henfi-ey caUs it in the case of Pandorina, the
gonidium (XIX. 61), encloses itself, in fact, within a cyst (XIX. 69), and in
so doing mostly alters its form materially, loses its previous animal chai-acters,
becomes ' stiU,' and at the same time qualified to sustain life under various
adverse external influences, and to continue the species by an ulterior act of
develoj)ment. In all this we trace an exact parallel with the histoiy of the
spores of the lower Algas ; and there is no question that many of the Phytozoa
are no other than spores, sporozoids, or zoospores. Moreover, it is equally clear
that many Monadma and Cryptomonadina described by Ehrenberg are but
two phases of one and the same organism.

Not a few Phytozoa present an additional covering in the shape of a muci-
laginous layer. This is found in isolated species, as Protococcus pluvialis,
and generally in aU the aggregated foi-ms ; indeed, it is the principal agent
in the construction of the latter. It lias generally been assumed that this
mucilaginous investment is an extracellular product, without a definite bound-
ary ; but Cohn (on Protoccocus, R. S. 1853) has a long argument to prove
that the true cell is represented by it, conjointly with the included, coloui-ed,
apparent cell. Thus, he writes (p. 631)—" Neither of these bodies are tnie,
perfect ccUs, inasmuch as the first wants the primordial utricle, and the second
is without the true cell-membrane. The two together would represent the
perfect cell." Again, it is stated in the same page, " that the internal globidar
body is not surrounded by any special cellulose-membrane, but only by one
readily destroyed by chemical or physical agency — probably nothing more than
a dense layer of protoplasm. On the other hand, the external membrane

OF THE I'HYTOZOA.

113

represents a true cell-membrane, enclosing betAvcen itself and the coloured
substance a colourless aqueous fluid, probably piu'e or nearly piu-e water."
And in the subsequent considerations of this structure, Colin appears to arrive
at the conviction that the internal colom-ed body generally spoken of as the
coll, the actual unicellular organism, represents the nucleus of a cell, of wliich
the periphery of the mucous envelope is the boimdaiy. In this interpretation
of the natiu-e of the mucilaginous envelope. Prof. Williamson coiicm-s. Indeed
this acciu-ate observer proceeds, fiu'ther, to show that there is in the case of
Voh'o.v a true enclosing delicate membrane to each cell, and that the hexa-
gonal form is owing to the mutual pressure of the aggregated ceHs (PL
XX. 38). In aggregate forms, such as Voh'0.v, Gonium, Pandorhia, &c., an
additional common external membrane would seem to be throAvn out, to unite
together into one symmetrical whole the various members of the colony.
Perhaps it should be rather called a pelUcle than a membrane, seeing that its
independent existence as a separable structiu'e cannot be demonstrated : yet
it has a power of resistance ; for when external force is applied to a globe of
Vohox, the surface, though at first depressed, presently recovers itself by an
innate elasticity ; and in the case of Pandorina it seems so resistant and fii-m
that it does not indent on pressure (XIX. 61 ).

Cell-contents. — The fluid distending the mucilaginous envelope around
most Phytozoa, in one or other stage of being, is, according to Cohn, as above
noticed, probably pure water. This opinion Prof. WUliamson does not enter-
tain ; for he says {J. M. S. 1853, p. 55) " it is apparently mucilage. In a
preparation in which a number of these objects [of Volvox^ are mounted in
dilute alcohol, this gimimy matter has changed to a brown eoloiu-, and refused
to mingle ■with the alcohol, as would be the case supposing it to be mucila-
ginous. This proves that it is a tnie secretion fi'om the organism, and not

merely water absorbed by endosmosis The secretion itself is, perhaps, little

more than a diluted condition of the same gnim as that which is more or less
completely converted into cellulose in the various investing membranes."

The central globule, or the whole recognized organism where a mucilaginous
envelope is not present, consists of a mass of protoplasm. At fii-st it is homo-
geneous and without colour ; subsequently it becomes generally colom-ed and
granular ; but very shortly the included matters gather together into a sort of
layer subjacent to the surface, and leave the centi'al part clear, sometimes so
completely so that it assumes the appearance of a vacuole. This substance
moreover has the property of contractility inherent in it, and would seem, in

all essential circumstances, homologous with the simple contractile matter

the sai'code of animalcules. Like the latter, it may hollow itself out into
vacuoles at anj^ part ; and such, says Cohn (B. S. p. 535), " arc present in all
yoimg cells, and play a considerable j^art in cell-division and the sap- currents."
The property of contractility is singidarly displayed in the ca.se of the actively
moving zoospores or sporozoids of the Algas, and in the motile form of Proto-
cocciwi, — i. e. in every instance where, from the absence of more or less inelastic
membranes, it can exhibit itself. The vacuoles of the protoplasm occur in
vaiying numbers, and change or chsappear from time to time : within they
contain an aqueous fliud,

Tlio contractile protoplasm is itself colourless ; yet, except in the earliest
stages of development, it partakes of a green or a red coloiir, or of both these
colours together, save in one spot, which in oblong fonns is situated at one
end, and in the projection or beak (proboscis, Ehr.. or rostellnm) extendin<'^
from the anterior extremity. " It appears," says Cohn {R. S. ]). 536) " ms
a delicate, almost imperecptiblc layer constituting tlie outer boiuidaiT of tho
coloured primorchal cell, the periphery of which then becomes sharply de-

I

OENEUAL UISTOUY OF THE INl'USOIilA.

fined, and,' as it wore, surrounded by a delicate transparent membrane."
The green colour is duo to chlorophyll vesicles and granules, either diffused
or collected in a layer just beneath the smfaco. Among other contents are
also starch-granules without colour, and very frequently globules of oU.

Green or red may exist alone : but more frequently gToen prevails ; and the
red pigment, sometimes termed erythrin or erythrophyll, is seen only at one
spot, occasionally at the centre, but usually on one side of it, or at one ex-
tremity: when occupying the position last-named, it was looked upon by
Ehrenberg as an eyo-speck or organ of vision.

Although, as Cohn (op. cit. It. S. p. 528) tolls us, the green and red colour-
ing matters differ in chemical and physical conditions, yet the one passes into
the other. The red or bro'vvnish-red colour is formed when the cells become
drier ; but neither deficiency of water nor the influence of light appears to be
the exclusive cause of the transition. It is especially in the transition to red
that vesicles of an oily asj)ect make their appearance. Indeed, that oil is really
formed, is supported both by analogy ^Yith. the spores of many Algae which
clearly secrete that substance, and by the vesicles in question having a similar
refraction to oil, and behaving Hke it with alcohol and ether. " The forma-
tion of fi:xed oil," says Braun {Bejuv., R. S. p. 200), " is intimately connected
with that of starch in the economy of ceU-Hfe ; its appearance, iu like manner,
announces the repose of age in cell-life ; its disappearance, the beguming of
rejuvenescence. We meet with fixed oil in the cells, either mixed with starch,
substituted for it, or gradually displacing it ; its occuiTence is perhaps stiU
more general than that of starch .... Like the latter, it is met with in greatest
abundance in those parts in which vegetation is destined to rest and to await
a future re-awakening ;" and such are the resting-cells of Phytozoa, in which
a red colour predominates or exists alone. Braun fuiTiishes an illustration of
this in his remarks on Ghlamydoinonas during its sleeping or resting state
(op. cit. p. 214). The opinion, moreover, that the so-called redeye-specks of
Phytozoa are no other than drops of oil, is shared by Perty (p. 117) and by
Nageli (Einzell. Air/, p. 9).

Speaking of Protococcus, Cohn remarks (op. cit. p. 526), " The red and the •
green portions of the contents appear to be of equal physiological importance
. . . .When still or motUe cells axe brought into contact ^^•ith a very weak
wateiy solution of iodine, they become internally, in most parts, of an int-cnse
violet or blue colour." Yet he does not believe this coloiir to depend, in
all instances, upon starch ; for the red contents are equally coloured blue, and
he therefore surmises there may be some other substance besides starch ex-
hibiting the same reaction with iodine.

Besides diffused chloropliyU-particles, to which the green colour is due, one,
two, three, or more large nuclear-Hke vesicles exist in Phytozoa — ^indeed, in
unicellular plants generally — described by Nageli under tlie name of ' chloro-
phyll utricles or vesicles.' The number of such in any genus seems commonly
to be constant: i\ais,m Sieplianospho'.ra there are two ; in Oonium only one.
However, they are occasionally absent, chiefly so in more minute examples.
In Protococcus (Chlamyclococcus), Cohn says they occur principally in the green
cells, to the number of one, two, three or more, ha^•ing tlie appearance of
minute green rings, about 0-002'" in diameter^ — the interior being sometimes
darker, at others more clear, and fi-oquontly almost opake. Niigeli regarded
them as minute membranous vesicles, containing a mucus coloured by chloro-
phyll. Cohn imagined tlmt iji Protococcus they stood in connexion Avith the
di^^sion of the ccU, but could not determine with certainty tliat tlieir number
corresponded with that of the secondary cells. Kiitziug looked upon tliem
as gonidia or cell-nuclei, conccmed in the propagation of the indindual.

OF THE PHYTOZOA.

115

Elirenborg entertained a similar notion, and called them the testes. " Caustic
potash," says Cohn (A. N. II. 1852, x. p. 340), "which destroys the rest of the
contents of the piimordial cells, makes the chlorophyll-utricles of Stephcmo-
sjahcera show themselves more distmctly as hollow riugs surrounded by a rather
granular membrane ; iodine colours them deep violet, which leads to the con-
clusion of the presence of starch." Iodine sometimes, however, produces a deep
bro-wn tint (Cohn, B. S. p. 529), due, we may suppose, to an ulterior mcta-
moi-phosis of the stai'ch, as it is itself a transitional condition of chlorophyll.

Another structure met with among the contents of some of the Phytozoa
is the contractile vesicle or sac. This sac has been noticed in Volvo.v., Oonium,
Pandorina, Chilomonas, Cryptomonas, and in Ghlamydomonas, and its rhyth-
mical contractions obsei-ved (XIX. 16, 33 ; XX. 40, 41). In Steplianosplmra
a similar vesicle was seen by Cohn, but its contractility not detected : so in
Astasia, Emjlena (XVIII.), and Pohjtoma (XX. 1, 2), a clear sac-like space
presents itself at the anterior extremity, immediately beneath the surface ;
but its alternate expansion and contraction have not been witnessed.

A mwleus is detected in Euglena, Astasia, Polytoma (XX. 1, 2, 3), and
others in which an animal nature predominates. Even among the vegetable
genera Volvox, Pandonna, and Qoniivm (XIX. 32, 34, 61), most writers, as
already seen, seem disposed to view the constant chlorophyll-vesicles as of
a nuclear character. In Oonium, indeed, Cohn {Entiv. p. 178) describes only
one such vesicle, which seems to demonstrate its nuclear natiu'e by breaking
up, during the process of fission, into as many parts as the piTmordial cell
itself. Braun (op. cit. p. 174, in note) mentions his observation of a central
vesicle or nucleus in GJilamydococcus (XIX. 22, 24, 26), and remarks, " in
most of the true Palmellacese there is a chlorophyll-vesicle in the centre of
the ceU."

The appearance of the cells of Phytozoa is much modified by valuations in
the relative quantity or in the arrangement and colour of the contents, so much
80 indeed that such varieties have been described as different species or even
as different genera. Thus the accidental presence of a red spot, called an eye-
speck, or the occuri'ence of a red central space, have had a specific importance
wrongly attached to them. The inutility of characters deduced from the
disposition and appearance of the ceU-contents, or from the figure, is further
shown when the effects of external agents — of tempcratiu'e, of the abimdancc
or deficiency of nutritive matters, of Hght, &c. — are taken into account ; and
it becomes even still more evident when the changes of form one and the
same being may undergo are duly considered.

In a previous page it has been stated that in the earliest phase of existence,
when the future cell is but one of several macrogonidia within its mother-cell
the protoplasm of which it consists is unenclosed by a membrane — has no cell-
waU. But it would seem that a cell-membrane is wanting even at maturity
in some genera, for example, in Stephanosp7ia;ra ; for Cohn writes (A. N. II.
1852, X. p. 326), " This is not only made evident by the multifold changes
of form which they undergo in the course of vegetation, and by tlio filiform
prolongations and ramifications which are produced directly from their sub-
stance (XIX. 38, 39-53), but is clearly shown by the transformations which
the primordial cells pass through in consequence of external influences.
I Under certain circumstances namely, the filiform ]n'ocesscs may be retracted'
being torn away from the cnvclope-cell and taken up into the substance of the
primordial ceUs ; the produced ends of the primordial cells also disapiiear tlio
latter becoming rounded off into their original spherical or short cylincbicnl
form. Such a change would be impossible if the primordial cells wore sur
rounded by a rigid membrane, such as that of the envelopc-ceU for example."

I 2

110

GKNERAL HISXOBY Oi? mjS INi'USOBIA.

According to Prof. Henfrey, the primordial cclla or gonidia of Pawlorina
(XIX. 59-63), and also, in tlie opinion of many, the Euglence (XVIII. 45-48),
are similarly undefended.

The internal globiUai- coloured body of the motile form of Protococcus is in
the same state. Thus Cohn (B. S. p. 531) points out that although this
body has a sharply defined outline, yet, " either by mechanical means, or by
chemical reagents, the internal globular mass may suddenly be made to lose
its contour, and to spread so as entirely to fill the cavity of the colourless
envelope. From which it would appear that the internal globular body is
not surrounded by any special cellulose membrane, but only by one readily
destroyed by chemical or physical agency — ^probably nothing more than "a
dense layer of protoplasm."

In the case of Volvox the cells oi-iginate without an enclosing membrane ;
but after the appearance of the red spot, a delicate one shows itself, and
extends at different points into the connecting thi-ead-like processes (XX. 37,
39, 41). So in Gonium we may presume the piimordial cells to be ongtnaUy
naked, although Cohn has not remarked this fact, but confined himself to
describing the mature cells (XIX. 32, 34), which have an enclosing wall of
cellulose (Enhv. pp. 175, 176). Lastly, in the 'still' form of Protococcus a special
membrane invests the protoplasmic gonidium. In Gonium (XIX. 34), and in
Volvo.v (XX. 37, 39, 40), filiform prolongations extend between the several
cells in the compound organism ; in Stephanospluera similar processes are
given off at the opposite poles of the cells, and are consequently not inter-
current (XIX. 39). Prof. Williamson has in the case of Volvox offered the
best explanation of these threads, which have by some been supposed inter-
communicating canals. He fii'st makes good his opinion that the green cell-
like organism represents the nucleus of a cell, the wall of which is separated
from it by a greater or less space ; and then he compares the processes in
question with the filiform extensions fi'om the nucleus which are met with
in many vegetable cells, suspending that organ in the centre. In the eai-ly
stage of the cell, the protoplasmic substance fills up more or less completely
the cell- wall (XX. 42, 44) : by-and-by the latter becomes outstretched fi-om
it by a sort of dropsical effusion within it (XX. 37) ; but as the protoplasmic
nucleus has contracted adhesions at different jjarts, it becomes di'awn out fi-om
the adherent points into thread-like processes (XX. 39, 40, 45), which grow
more and more filifonn in proportion as the cell- wall expands. This expla-
nation (agreeing in every particular with the observed phenomena of cell-
growth) being accepted, it follows that these elongations are bounded by the
particular cell-wall to wliich they belong, and are not continuous with those
of adjoining cells. The processes of Volvo.v arc therefore off-shoots of the
protoplasm of which each cell or gonidium consists ; they are given oft" before
any enclosing wall or pellicle appears, and whilst that substance is still duc-
tile, and they disappear on the commencement of the process of development,
whether of raacrogonidia or of microgonidia, and whether with or without the
process of encysting.

In the case of Gonium, Cohn gives (Entw. p. 176) a different account of
the connecting bands. It wiU be remembered that in tliis genus that ob-
server indicates an enclosing cellulose membrane to each cell or gonidium.
Now this cell does not closely invest the protoplasmic substance at aU points,
but is so separated as to produce a licxagonal cell-wnU aromid it. from eacli
angle of which the membrane is produced in a tubular form, and joins with
a similar process coming from the angle of an adjoining cell (XIX. 32. 34).
Ilenco each process of the membrane has a double outhne, and is in fact a
tube, only that its interior must lie pi-csumed to be shut-oft' from that with

OF THE rUYTOZOA.

117

A\ hich it joins, by a septum representing the divisional membrane of each of
the contiguous cells. The state of things here is tlierefore quite different
fi-om that in Volvox : for in the latter the eeU-membrane is widely detached
from the protoplasmic nucleus, but the adjoiiiing cells are adherent at aU
points ; the intercm-reut thi-eads are therefore within the cells, and uphold
an attachment between the nucleus and the cell- wall, — whilst in Gonium the
contrary obtains : the cells themselves are not in apposition, but held together
by a tubular extension from each angle ; and the nuclear protoplasm mthiu
neai-ly fiUs the cell-cavity, and has no bands uniting it with the wall — in
fine, the intercxu-rent processes of Oonium and of Volvox are not homologous.

Besides the wall and processes just described, calculated to give strength
and resistance to the organisms, there ai'e also the long c'dla or filiform ap-
pendages known as filaments, flabeUa, or flageUa, seen at one extremity of
most Phytozoa, derived from the protoplasmic mass. To these are entirely
or chiefly due the locomotive powers of these beings ; they also act the part
of rudders in tm-ning them on themselves, and in directing them hither and
thither. They do not belong to the class of vibratile cilia, but are larger,
fiHfonn or whip-like, and have an imdulating lashing movement. In some
cases they are many times longer than the organism to Avhich they are attached
(XVIII. 15, 21, 22) ; and when two, as more fi-equently happens, are pre-
sent, they will often cross and interhvine. At times, in elongated forms,
they appear to be the mere terminations of the tai)ering-like extremity or
neck ; but the rule is, they do not proceed from the apex itself, but from one
side of it. Where the species is encased in a fii'm integument, separated by
an intei-val fi'om the central protoplasm, the filaments actually extend from
the latter and peiforate the enclosed case ; in which, particularly when these
processes are fallen away, their points of issue are occasionally to be detected
by depressions or by pores. During frequent rapid movements these fila-
ments are not to be seen ; but when the motion is more gentle, or they ai'e
at rest, or othermse when colouring matter is mixed with the water, they
generally become visible. Even when theu- existence has not been noticed
during life, it may be sometimes demonstrated after the di-ying up of the
being, by the streak left upon the glass where it rested. Where more than
one or two filaments are present, their whirling, and the consequent agitation
of the fluid about them, mtikes their existence apparent.

The number of filaments in Phytozoa vaties. Two is the prevailing number,
which may or may not be of equal length ; but in not a few genera only one
is found, e. g. in Eiighna, Monas, and Chilomonas, — whilst in others more than
two may be counted, situated together anteriorly, or some in front and others
behind. Where two arc present anteriorly, it is not an uncommon arrange-
ment for one to extend in the direction of the long axis of the body whilst
the other trails behind (XVIII. 12, 22, 23).

Movements of Phytozoa. — The motion of many Phytozoa is but slow,
and rarely intei-mitted ; in others it is more rapid and varied. It wiU be
modified by the figure of the organism and by the degree of firmness of its
walls, with which it stands in inverse proportion. In Euglena the move-
ments are extremely varied and lively: the being is unrestricted in its
movements by an integument, and the contractile protoplasm has full scope ;
it is, in fact, in the condition of swanning gonidia, unenclosed l)y a wall of
cellulose. In many species of Moiias and Bwlo (Oercomomts), the motion is
iiTogular and peculiar ; it may be oscillating or rolling, at times leaping at
others backward. Among the Vihrlonla (XVIII. 57-60), an oscillating
spiral movement is a common cliaracteristic, and either end may be advanced
nic revolving rolling motion of Folvocinece has for many ycai-s attracted

118

GENEBAL niSTOEY OF THE INFUSOlllA.

attention, and for a long time was deemed suiRciont proof of the animality
of the beings exhibiting it. It is the consequence of the play of tlie ciliary
filaments of each of the component cells of the aggregate organism, which
project beyond the common envelope : it consists in a revolution on the axis,
and a simultaneous onwai'd movement — not, however, in a straight course,
but in an iiTcgular one, representing a spiral or series of cui-ves. " The
collective idea of such motions," says Cohn (A. N. H. 1852, x. p. 328), " is
best represented by the course described by a top, which nms through the most
vaiied curves, while at the same time constantly revolving on its axis."

Niigeli (as quoted in J. M. S. i. p. 198) remarks of swarm-ceUs (zoospores),
which many Monads undoubtedly are, that " under the microscope the motion
appears very rapid, somewhat of an infusorial character, consistuig in a con-
tinual progression, in which the hyaline narrower extremity is usually in
front, and the ceU is continually turning on its long axis. Although the
swarming bears a resemblance to the motion of Infusoria (i. e. of Ciliaied
Protozoa), it clearly wants the spontaneity of the latter. The Infusoria
advance, 'spiing back, tui-n round, return, all spontaneously ; the swann-
spores pui'sue a uniform and, for the most part, pretty straight eom-se, de-
viating from it, or turning round only upon meeting an obstacle, impinging
upon which they are diverted into another direction." To this account
Siebold (Zoc. cit. p. 201) adds that the spores do not retreat, as if frightened,
like the Infusoria, when they strike against an object, but " remain close to
it, and continue their motions according to the number and an-angement of
their ciliary ap^^aratus, in a rotatory or vibratory way for a little tinae longer,
as if they aimed at overcoming the obstacle by force, until at last, probably in
consequence of the death of the cilia, they become still, and germination goes on.
.... The movements of the swarm-spores in general have only a short dui"ation.
After the spores have come to a state of rest, they usually become attached
by the hyaline ciliated extremity, and the locomotive faculty is for ever lost."
In the aggregated families the process of reproduction is ever going on in
some members of the colony, and the movements are kept up much longer.
Braun {JEtejuv., B. S. p. 212) represents Chlamyclococcus as enjoying a longer
dui'ation of motion than is usual with the swarming gonidia of Alga), whilst
Protococcus viridis forms an intermediate link in this respect between it and
the Vol^odneoi. The kind of movement, he adds, is essentially the same in
these organisms as in all active gonidia, namely an luiinternipted revolution
round the long axis, combined with an advance towards the side of the
ciliated point. It is, indeed, in the swai'ming movement of gonidia and
spermatozoida that the phenomena of motion are most strikiug, " that is, in
ceUs wliich are either yet without theii- celbilose coating, or which never
acquii'e one."

Cohn {li. S. p. 558) states generally that, " lea^^ng out of the question
the more highly organized Infusoria fiu-nishcd -with a manifest mouth and
oesophagus, the motion of a large part of the Ancntera (Ehr.), the Asioma (Sic-
bold), is not essentially different from that of the zoospores of certain Alga3."
Likewise, in Ids description of Gonium {Entw. p. 180), he observes that the
movements of this organism resemble in every particular those of Stcphano-
sjjJuera, C'hlamydococciis, and other swarming-cells, which certainly do not
bear at all the character of pui-posing, conscious volition, but appear as an
activity determined not by any external causes, but by internal causes in the
organization and vital processes." {A. N, II. 1852, x. p. 328.)

The character of the locomotion of Phytozoa may be described in brief as
' automatic;' accepting that term as phj-siologists now agree to do, to distin-
giiibh sucla motion from the volimtary movements of animals. It cannot be

OF THE PHYTOZOA.

119

\ oliintaiy, or the result of volition, any more than the marvellous motion of
the leaves of Dioncea muscipula.

TiiocEss OF KuTRiTioN. — The process of nutrition of Phytozoa is of the
most simple kind ; and no valid evidence can be adduced in proof of the com-
plex polygastric organization represented by Ehi-enberg. In fact, an apparatus
of stomach-sacs could not, by any analogy, be presumed in a set of beings
destitute of mouths ; and Ehi-enberg was unable to demonstrate, even to his
own satisfaction, an oral aperture, except in a very doubtful manner and in
a very few instances. What he took to be gastric ceUs are no other than
vacuoles and clear vesicles — sometimes the chlorophyll- cells ; the last, how-
ever, were more commonly assumed to be ' testes.' To support his belief in
the presence of stomachs, and also of a mouth at the anterior clear space,
particularly where there is a projection of the protoplasmic mass, the Berlin
naturaUst appealed with most confidence to his experiments in feeding with
coloured substances. By this means he believed he demonstrated such
organs in some Monadina, — ^but so rarely, amid a large number submitted to
experiment, and moreover in so few species, that much weigh-t coidd not be
attached to the result, especially when it is considered how many difficulties
and doubts must arise where such very minute beings are concerned. Allow-
ing that particles of colour actually entered within the interior, and were not
merely adherent (a question which the magnifying powers of the instrument
Ehrenberg used could scarcely determine), it is even then much more rational
to suppose that their entrance was by mere mechanical causes (by pressiu-e
or the like), than by the medium of a mouth. This interpretation is adopted
both by Perty and Leuckart, who describe the introduction of such particles
as possible, although, indeed, exceedingly rare in the more clearly vegetable
structures, the Diatomeae. The former mentions (op. cit. p. 61) three in-
stances in which he encountered foreign particles within the substance of
Phytozoa ; but these would, instead of supporting, be really opposed to the
polygastric hypothesis. For instance, he discovered in a Peronema a species
of Badllaria as large as itself, and consequently not containable withm one
of the supposed gastric cells.

In the case of the soft, Uloricated minute Monadina, into which fine particles
have found their Avay, it is to be remembered that they are mere masses of
yielding protoplasm unprotected by a cuticle; and further, Ave may, along
with Perty, reasonably presume that, in some examples of the entrance of
external matters, it has been effected much ia the same way as with the
Amoebce, by the soft substance overlying and then surrounding them.

If a mouth and stomachs have no existence, it follows that nutrition must
be effected by imbibition — by endosmotic and exosmotic action — just as in any
simple vegetable or animal ccUs. Perty (oj?. cit. p. 62) adduces an experinient
showing that, to some Phytozoa at least, water rich in nutritive organic
material is necessary to theii- complete and healthy development ; for when
taken from such water and placed in other quite pure, they dwindled in size
although, curiously enough, they at the same time became more active. '

To complete what we have to say of their vital endowments (irrespective
that is, of the reproductive functions), the Phytozoa seek the light ; and all
their nutritive acts arc carried on more actively under its influence. The
only exception is when, in the process of propagation, they arc about to pass
into the ' still ' condition and to become encysted ; then they eschew the light
sink out of sight, and recede to the bottom, or under cover of aquatic plants
or of their debris. Under the influence of light they exhale oxv-^eu -as
and the green colour is especially developed,— whilst when kept in the dark
they lose colour, become pale, and present few chlorophyll-particles The

UJiNUllAL JIISIOIIV OF TUK IMia'SOKIA.

intensity of light may be too great, and destroy life ; and a great elevation of
tomporaturo is less favourable to vital acti\ity than a moderate one. Cold
retards vital action, and if considerable, arrests it, except in the case of the
encysted beings, which are so modified by nature as to resist it« injuiious
influence ; these consequently persist tlirough the winter when the motile
forms are cut off, and in the coming spiing biu'st forth into lil'e. The same
provision wliich imparts to the encysted organisms a tolerance of cold, enables
them also to withstand the effects of evaporation, which to the unprotected
motile varieties is speedily destructive, imlcss, indeed, so gradual as to aUow
them time to pass into the ' still ' form.

Htarch or cellulose may be detected chemically in the great majority of the
Phytozoa; and even where iochne fails to produce the characteristic blue
colour dm'iug life, it will at times act strongly when a brealdng-up of the
contents follows evaporation or some other injmious influence. The efficiency
of nutrition is manifested by the decided changes, chemical and vital, whicli
are seen ia constant operation mthiii the beings — such as, among others,
the transformation of chlorophyll into starch, and of one or both these into
an oily matter.

When in the ' stUl ' encysted condition (XIX. 44-69), aU nutritive changes
are at a standstill, and the organism may exist weeks, months, and even
years unchanged, until external conditions are supplied to awaken its latent
energies and to renew the cycle of life. In this toi-pid fonn the spores are
carried about with the dust, or remain bmied in the earth, or are elsewhere
hidden or stored up against the day of revival.

The passage into the ' stUl ' condition by the thi'owing-out of an external
denser envelope and by the loss of cilia, is governed, it woiUd seem, in some
measure by external circimistances. Motile forms are replaced by the ' still '
in whole or in part, and with greater or less rapidity, by ijouring the water
containing them into a larger and shallower vessel, and by gradual evaporation.

The protoplasm of Phytozoa being homologous in all perceptible particulai-s
with the ' sarcode ' of Protozoa, sirffers, like it, the destractive process of
' dif&uence ' or ' deliquescence ' when evaporation reduces the quantity of
water around tlie improtected motile forms below the quantity necessary to
vital action. The first noticeable result of evaporation is, according to Cohn,
at least in the instance of Protococcus {op. cit. p. 538), a more rapid change
of fig-ure and appearance, followed, if the evaporation continue, by difiiuence,
in which he distinguishes two stages or phases : — "In the fii'st, the outlines
appear less sharply defined, because the colom-ed substance is somewhat
I'ctracted from the border of the primordial cell ; the cells become flattened,
and at the same time wider : the contents are also now altered ; pre^-iously
more homogeneous and transparent, they now become throughoxit granulai-,
and the red substance nins together in large di'ops. At this time tlie forma-
tion of vacuoles commences ; and thoii' number continues to increase. In this
way the interior of the primordial cell again becomes colourless, clear as
water, and the graniilar colom-ed contents pressed against the walls. . . .The
figiu-e of the cell in the wami time is so much expanded, that it comes to be
ap])Hcd u])on the wall of the enveloping cell, alternately fiUing it altogether,
so that the entire zoospore appears to consist of only a single coltmred gra-
nular vesicular disc, corresponding in size ■with the original on^■elo])ing cell."

MuLTii'r,icATTON ANB Biu'RODUCTioN OF P^^"TozoA. Fissiox : Machogoxidta :
MrcKOGONiDiA : Encystino process: Puasks of kxistkxcf.. — The nniltiplica-
tion of the individuals of the species of Phytozoa is provided for hy \ho
process of self-di\-ision. deduplicatioii. or fission. Tliis takes place according
to the plan obtaining in vegetable and animal cells in general.

OV TUTS, I'HYTOZOA.

121

Tho cell-contents divide into two or more segments, each of wlucli can
further develope aroimd itself a gelatinous investment, and enter on an inde-
pendent existence. In Euglena, self-division occurs longitudmaUy into two
portions ; mu\ the newly-developing half is of smaller size than the other, but
becomes complete in aU its parts before its severance is effected.

The motUe ceUs of Chlami/dococcus undergo fission into two or foiu- seg-
ments (XIX. 23-26) : this takes place in the protoplasmic or primordial cell
contained within the hyaline spherical envelope-aeVL ; when division is com-
plete, the latter is ruptm-ed, the sections escape as independent beings, each
throws out around itself its envelope-ceU, and in aU points goes thi'ough the
same cycle of development as the parent-ceU. Many Monads also divide
into two beings, whilst others separate into four. In the above-cited ex-
amples the fission is complete, and each segment, on detaching itself fi-om the
other, becomes an independent, free being.

But this same act of fission may proceed under different circumstances ;
and instead of a single organism, a colony may be formed, consisting of
several individual ceUs imited together, either permanently or only for a
time, within a common envelope. These aggregate Phytozoa are especially
represented in the family Volvocinece.

■ In this second mode of fission the process is repeated a greater number of
times — for instance, some 3, 4, or 5 times — the result being a higher multiple
of 2, the product of the first act of scission.

Each repetition of the process of fission, from the commencement until
its completion, constitutes, in Niigeli's language, a transitional generation,
whilst the final repetition produces the permanent generation. For example,
in Ste/plianosplmra two segments are produced by the act of fission, Avhich re-
present the first generation (XIX. 45) ; then each of these subdivides, and so
developes four portions (XIX. 40, 46) — ^the second generation ; and, lastly,
each of the foiu- separates into two, and in that way produces eight segments
— the third, and in this organism the final or permanent generation (XIX.
41, 42, 56).

Unlike the segments resulting fronj a single act of division, or, as may
happen, fi-om this act once repeated, each newly-formed j)rimordial cell
does not commonly surround itself with an enveloiDe and enter on an isolated
existence, but the whole eight or more continue to live within a common
tunic, which presently expands by endosmotic action and acquires a more or
less spherical figui-e (XIX. 56, 57, 58). Simiiltaneoiisly with tliis expansion,
the previously contiguous particles are di'awn away more and more from
each other, and disposed within the common envelope, after a more or less
regular fashion, characteristic of the species to which they belong (XIX. 42,
58). In general, the separation of the primordial ccUs is not complete ;
bonds of union between them in theii" early state, when closely approximated,
become di-avvn out, and ultimately present tlicmselves as interciu-ront threads.
"WTicn tliis series of changes is terminated, we have before us a reproduction
of the aggregate organism of Avhich the dividing primordial coU -\vas but an
individual member,
development
above cited, \

and 02-66), and also in undoubted Algas, the HiidrodkUjon or Water-net
for example.

But the segmentation of the ceUs of Tlivtozoa occurs in yet another form •
I.e. the tission, instead of stopi)ing at the third or fourth generation Dro'
cecds still further, until 32 or 64, a hundred, a thousiind and upwirds of
mmuto coU-stnicturcs arc produced, tcchnicaUy called ' mkrogonidia ' in

c aggregate organism oi Avnicii tne cimcling primordial coU was but an
idual member. Braim has styled this variety of reproduction l)y fission
opmont by ' macrocjoiudia.' It is well illustrated in Stephan'mphara',
! cited, in Volvox (XX.), in Gonium and Fandorina (XIX. 35, 36 St'

122

GENERAL HISTOBT OF THE INFU80E1A,

tended to pci-pctimte the species by their ulterior development. Although,
like the ' macrogonidia,' they are formed within a common envelope, yet
each cell among them does not, as in tliose products, enclose itself with its

own tunic, and fix itself permanently within the general investment in

other words, assume at once the ' still ' condition ; but the whole, after entire
separation from one another, become endued with vital activity, and are sub-
sequently set fi'ee, by the dissolution or rupture of the surrounding parent-cell,
as so many moving zoospores (XIX. 51). The motion of these little bodies
within the original cell is of a hurrying to-and-fi-o or up-and-down cha-
racter, and has been styled ' swarming.' On emerging from the ruptured
cell, each little body is seen to have a spindle-shaped figure, terminated at its
anterior clear and usually elongated extremity by two or four cilia (XIX. 52).
In every essential particular these microgonidia are homologous with the
motile gonidia, swarming-cells, or spores of the common Algae, such as Bry-
opsis, Codiutn, Aclilya, Chcetophora, Ulothrix, Hydrodictyon, &c. Cohn's re-
marks on the formation of microgonidia in Stephanosphcera {A. N. H. 1852, x.
p. 346) may elucidate this subject still further. He says, " While, in the
formation of macrogonidia, the secondary cells become surrounded by a
common envelope and are not free (as an entii'e connected family of cells
aiTanged according to a definite law), in the mode of propagation of micro-
gonidia the little secondary cells finally become totally separated from one
another without secreting an envelope-ceU ; and in this way each of the
eight primordial cells of the perfect SteplianospJicera is broken up into 32 to
64 independent, green, elliptical or spindle-shaped corpuscles, which then
separate fr-om one another, commence an independent and active motion, and
fill up, in great numbers (as many as 256-512), the common pai'ent envelope-
cell (XIX. 51) .... The crowding-in among each other of the microgonidia of
Stephanosphmra presents a picture fixing the attention in the highest degree :
sometimes the cellules are scattered in a few large masses — then they unite
again into a knot in the middle — every moment the general aspect varies.
At length the common envelope is ruptured," and they escape in masses
into the water. " Their true form may then be detected readily by kiUing
them with iodine ; they are spindle-shaped and acuminated at both ends,
bright green in the middle, and run out into a colourless beak at each end —
on the whole not unlike young EuglencB, without trace of an envelope-cell
(XIX. 52)," On reaching the water their movements aa-e most active, and
then rapidly disperse out of sight. These bodies are true primordial cells,
" that is, primordial utricles resembluig cells, organized exclusively of co-
loured protoplasm, without any cell-membrane."

Upon a general survey of development by gonidia, Cohn remarks {A. N.
II. 1852, x. p. 403) — " Abstracting the differences which may always be
shown between two genera, we detect the same law of development in Hy-
drodictyon as in Stephanosplioira-. the bicUiated, less numerous macrogo-
nidia arrange themselves into a family of ceUs ali-eady within the parent-cell,
according to the character of the given conditions of the two genera, — the
cell-family being active in the Volvocinete and immoveable in the Proto-
coccacca3 ; whilo the more numerous, more actively-moving microgonidia
with four cilia leave the parent-ceU and enter upon a metamorphosis, tlie re-
trogradation from which to the normal ij^c of the genus has not been ob-
served yet hero, or indeed in the microgonidia of any of the Algaj." It may
be conjcctm-cd that these latter pass into a resting state, prior to any fui-thcr
development ; for botli Colm aiid Braiui have mtncssed this change in
Ohlamydococcus pluvialis.

The formation and escape of microgonidia have been observed by many

OE THE PHYTOZOA.

123

nahmolists— for instance, by Weisse in Chlomjonium, and by Pcrty m each
family of Phytozoa. The production of such bodies is frequently treated of
as development by germs, and, no doubt, is the same phenomenon Ehrenberg
represents as viviparous reproduction.

Microgonidia are not so commonly developed as macrogonidia ; and indeed
theii- formation would seem determined, at times at least, by external cir-
cumstances affecting their fimctions and vital activity unfavoiirably. Thus,
Cohn {Entw. p. 168) narrates the circumstance of the peculiar and pretty
general development of microgonidia, va. Chlamyclococcus, after a thimder-
storm.

Peocess of EwcTSTiifG : Condition of eest. — The perpetuation of Phytozoa
is provided for, as before intimated, by another process, which both secures
to the cells imdergoing it a power of successfully resisting influences that
to unprotected gonidia are destractive, and is connected with an ulterior act
of development. This faculty of self-protection is called " the encysting pro-
cess," since by it the cell encloses itself within an additional firm timic, which
suri'ounds it like a case or cyst, and transforms it into a still' or 'winter ' spore.

The process takes place in all the Phytozoa after the same fashion : the
protoplasmic coveiing of the gonidium or cell secretes around it a dense, firm
envelope, which in general becomes raised £i-om it aU round, so as to leave a
clear intervening space. On the assumption of this extra coveiing, cells
previously motile and active enter on the ' still ' condition and lose their
cilia ; at the same time, the character of the contents is altered, and a red
colour frequently acquired. The transformation in their physical structure
is accompanied by a physiological change ; for in place of seeking the light,
exhaling oxygen, and carrying on all the vital processes with a corresponding
activity, they sink to the bottom and conceal themselves from the light. It
appears, from Cohn's researches on Protococcus, Gonium, and other Phytozoa,
that they become released from their imprisonment, imder the influence of
favourable external conditions, by the dehquescence of the rigid external sac,
and sometimes by its transformation into an external mucilaginous invest-
ment, and by the breaking-up of the internal protoplasmic cell into a number
of motile zoospores.

The act of encystiag may proceed with macrogonidia in their ' still ' con-
dition ; or it may overtake motile primordial cells, as in the case of Euglena
and of some phases of Protococcus, and in such, just as in the zoospores of
Algse, prove antecedent to further acts of development by fission. Cohn im-
plies, in his history of Protococcus, that microgonidia may themselves be en-
cysted ; and the same eminent observer describes the primordial cells of that
plant as in some instances surrounding themselves with a fiinn external
envelope, pushing out two cUia, and moving about for a time in a 'swai-miu"-'
manner ere assuming the ' still ' condition, when the cUia disappear. But
further, he shows that gonidia, furnished with a rigid external wall, proceed
to develope others like themselves by self-division of their substance (XIX.
25), and that these secondaiy cells, each included within its own sac, go on
to divide into other spores, wliich, however, prove not to be ' stUl ' like'their
parents, nor like them encysted, but motile zoospores.

In the aggregated family Volvocineso, some or all the primordial cells be-
come encysted. AVhcn tliis takes place, their contents grow thicker, less
transparent, darker, and change from green to brown and broAvnish or to
a ycUowish red. At the same tunc, the intorcm-rent filaments disa])pcar the
cells themselves acquire a more spherical figiu-c, and graduaUy loosen th'cm
selves fi-om the common envelope, and move slowly about within it by means
of two cilia, untU they at length escape by a ruptm-e at some point (XIX 44

124

GENERAL UISTOET OF TH.E INFUSOKIA.

50). These encysted spores resemble Chlamydomonads, and are called ' Pro-
toccoeoid ' cells or globules, from their homology with the encysted cells of
Frotococcus,

Occasionally, instead of one or several of the individual gonidia of a com-
poimd organism being encysted, the process ensues wth a gonidium deve-
loped by fission into macrogonidia, and the whole mulberry or Uvella-hkii
mass becomes surrounded by a rigid envelope, either pretty closely appKed,
or separated by an interspace.

Examples of the encysted condition will occm- in the followdng account of
the several groups of Phytozoa ; it suffices at present to say that Prof. "Wil-
liamson and others have pretty clearly shown that Volvox- aureus is only the
encysted or ' still ' form of V. glohator, that Cohn has discovered the cysts of
Steplumosplwra, Gonium, and Euclorina, and Henfrey those of Pandorina.

The after-history of the encysted spores of Phytozoa has not yet been
elucidated : we have above referred to Cohn's researches upon it ; but they
are too indefinite to supply any positive information. The act of conjugation
is common with many of the lower Alga3, but has not been witnessed among
the Phytozoa.

Phases of Being a^td Alternation of Geneeation in Puttozoa. — From
the preceding account of Phytozoa, it is evident that those best known exist
imder a considerable variety of form — -in other words, present several phases
of existence, or, viewed in relation with a prevailing hy^jothesis, exhibit
an alternation of generation. The whole history of any Phytozoon is com-
prehended in the cycle of changes which the organism passes tkrough ; yet,
imdcr any transformation, it is the self-same being, and its existence may
be said to extend fi-om its most perfect through all intermediate phases until
the nice degree of perfection is again attained. As happens in alternation
of generations among other organized beings, the transition may not be
dii'ect and simple, but intermediate phases may reproduce themselves, and
these again develope into other forms of existence, as accessory or collateral
and usually imperfect cycles.

Perhaps the metamorphoses in question are most striking in EugJena} ; for
the contrast between the actively-moving, conti'actile, ever-changing being
in one phase of existence, and the encysted, ' Protococcoid,' spore-like and
motionless condition Avith a rigid unvai-ying outline, is so remarkable as to
give coloiu' to the hypothesis of the convertibility of animal into vegetable
Ufe, or of the transformation of animals into plants. It is not oui- intention
at present to give illustrations of the vai-jong phases iu the life of Phytozoa
involved in the process of fission, or of a duplicative multiplication under its
various forms. HoAvever, other more extended instances of transformation
require to be noted, as obseiwed by various microscopists, — although, it may
be, some errors have crept in, from the difficulty of tracing the relation and
succession of the different pliases of being.

As a veiy good example of the -v^-ide and varied range of existence enjoyed
by most Phytozoa, Ave may adduce the Frotococcus p7in7"«?(s (XIX. 20-31),
of which the industry and perseverance of Prof. Cohn have obtained for us
so complete an accoimt. According to the researches of tliis eminent natu-
ralist, the simple plant in question, in its motile and still conditions, assumes
the foi-m and characters of many microscopic organisms presumed to be, and
described by Elironbcrg and otliers as, distinct existences. To quote fi-om
Cohn's memoir (li. S. p. 550), " We see that a single species, 0A\-ing to its
numerous modes of propagation, can pass through a number of very A-arions
forms of development, Avliich luiA-e been either erroneously arranged as distinct
genera, or, at least, as renuiining stationary in tliose genera, allliougli, in

OF THE PHYTOZOA,

125

fact, only transitional stages. Thus, tlic ' stiU ' Protococcus-ccU. corresponds
to the common Protococcvs coccoma (Kiitz.). When tlie border becomes gela-
tinous, it resembles P.pulclier, and tlie small cells P. minor. The encysted
motile zoospore is the genns Gi/ges cjranulum among the Infusoria, resembling
also, on the other side, P. timfkhis (Kiitz.), and perhaps P. versatilis (Braim).
The zoospores divided into two must be regarded as a form of Gi/ges hipar-
titus, or of P. dimidiaius. In the quadripartite zoospores, with the secondary
ceUs arranged in one plane, we have a Oonium. That with eight segments
corresponds to Pandorina Morimi, and that with sixteen to Botnjocijstis
Volvox'. When the zoospore is divided into thii'ty-two segments, it is a Uvella
or Syncrypta. When this form enters into the ' still ' stage, it may be re-
garded as a foi-m analogous to Mkrolialoa protocjenita : this Algal genus is
probably, speaking generally, only the product of the Uvella-division in the
Emjleno} or other green forms. The naked zoospores, finally, would represent
the form of a Monad, or of an Astasia ; the caudate variety approaches that
of Bodo. A critical and comparative consideration of the foregoing facts
would therefore appear to render untenable almost aU the principles which
modem systematists have hitherto adopted as the basis for construction of
theii' natural kingdoms, fanulies, genera, and species."

Cohn (ojj. cit. pp. 541, 542) makes the following general deductions : —
" 1. The ProtoGOCcus pluvialis is a plant, subject to an alternation of genera-
tions ; that is to say, the complete idea of the species is not exhibited in it
until after a series of generations. The forms of development which can be
possibly comprehended in the idea of the species do not in reality maJce
themselves apparent until a series of independent successive generations has
been gone thi-ough. 2. The individuals of each generation are capable of
propagating themselves in new generations. The individuals of the second
generation are among themselves, speaking generally, of equal value : as re-
spects the individuals of the parent generation, they are sometimes of equal
value with them, sometimes not. 3. If the secondary cells are not of equal
value with the parent-cells, a series of successive generations must precede
the last generation, the individuals of which are again equivalent to the first
mother-ceU. The number of these generations does not seem to be deter-
minate." By equivalent, the author means such individuals or generations
as correspond with each other in their essential, physiological, and organo-
logical relations, although they may differ in unessential properties, such as
colour, size, internal consistence, SiC. Non-equivalent are those generations
which in their structure and vital relations exhibit essential differences, such
as ' stiU ' and * motile ' cells, and among these, again, their various forms,
and particularly those which are derived from a different mode of propa-

gation.

Major von Flotow (Nova Ada Acad. Nat. Curios. 1844, p. 413), it is
right to state, remarked on the similarity of various forms of develojiracnt
of Hamatocoecus (Protococcus, Colm) j^luviaJis v.-iili Infusoria, signalizing the
genera Chihmonas, Criiptomonas, Gyges, Ghlamydomonas, Pandorina, CJtce-
tofjUna, and Chcctotyphla of Ehrenbei'g's system.

Phytozoa, or structures undistinguishablc from them, constitute links in
the chain of still more marvellous transformations. Thus, Itzigsohn repre-
sents several in the history of the development of the 0.sciUatoriea;. For ox-
ample {J. M. S. 1854, p. 189)—" Tlio filaments of OsciUatoria tenuis break up
into perfectly distinct joints, wliidi, at first urceolatc, soon become spherical
The minute yellowish-green gonidia thus arising gradually increase in size'
become motile, and present in aU respects the aspect of Chhimndomonas''
These bodies " gradually onlai-go ; a rod eye-point becomes ^^8ibie in them •

126

GENERAL HISTOEY OF THE INFUSOEIA.

and, presenting a thousand intermediate forms, they grow into perfect
Eaglence." After awhile these Euglenm become encysted, and terminate in
the quiescent or ' P/-o<ococci(5-condition,' and subsequently, by self-division
of the contents, are resolved into motile microgonidia which escape free into
the water, " If a miniber of these remain conjoined, and move about with a
rowing land of movement, their locomotion being governed by a common
spontaneity, they represent a FoZvoar-Hke colony, which, perhaps, may even
have been described as Volvox by authors. The microgonidia of the Eit//lem,
like those of aU the Alga3 hitherto examined by me, are the motile parent-
cells of extraordinarily minute spiral filaments. They are at first green,
gradually becoming peUucid — exactty like the speiTnatospheres of Spirogyra,
presenting a Monadiform aspect. A peculiar appearance aiises when many
microgonidia in such groups remain green whilst the others have already
become clear as water ; the mass then presents, in fact, the aspect of being
composed of two kinds of animalcules. Such or similar conditions would re-
present several species of the supposed genus Uvella (atomus, glaucoma, Bodo,
&c.). Each ultimately colomiess microgonidium, then, by the dLssolution of
its minute gelatinous envelope, discharges a small motile spiral filament." . . .
" These spiral filaments do not appear to be destined for the purposes of im-
pregnation ; for they gradually increase in length and thickness, soon exhi-
biting numerous spural turns," and then exchange the S2nrilla-]2ke for a
Spirulina-form. " PinaUy, when their motile faculty has become weakened,
they affix themselves by one extremity to any larger object near (for instance.
Conferva-filaments, &c.), whilst the other extremity continues to move about
with a creeping motion — the peculiar Oscillatorian movement, in performing
which a young filament frequently returns to the spiral. The last-described
condition constitutes the Leptotlirix of authors. The filaments now gradually
become thicker ; and though at fii-st of the hghtest emerald-green, they gra-
dually assume a deeper and deeper tint. The fii-st indications of articiilation
are perceptible in them, until at last a young Oscillatoria is again perfected."

But the remarkable metamorphoses of this Oscillatona are surpassed
by those of the Phytozoa of antheridia, as recounted by Prof. Hartig
(J. M. S. 1855, p. 51) : the antheridia of Marchantla fonn the subject of
obsei-vation. Theii' Phytozoa first assume the fonn of Ehrenberg's genera
Sinrillum and Vibrio, of which the most frequent varieties met with arc
Vibrio rugula and V. prolifera ; " after twcnty-fom- houra most of these
Vibrios and Spirilla — after forty-eight, all of them — have become disarticu-
lated." The whole drop of water in which they float is now rendered
nulky and turbid by numberless globules, similar to Monas creptiscttlum, in a
state of active motion ; and it is an important circumstance that Sjiirillum
does not originate from Monas, but always Monas from SpiriUian. Mtcr
forty-eight hours, " groups of several hundreds may frequently be seen, in
which the primaiy active motion has ceased. Shortly aftei-wards a shai-jily-
defined hyaline skin is foi-med round these groiips, and. as it would seem,
by the amalgamation or conjunction of the exterior molecules ; by this
means the young Amceba (Proteus) is formed. This transformation takes
place pretty regularly towards the end of the third day. The original size
of the Amceba is 1-300"' in diameter. In the course of tlu-ee or four days,
it grows to about the size of 1-100"'. This species diffci-s from the Amceba;
hitherto described, in the fact that the inner portion of the body which beai-s
the granules is much smaller than a certain hyaline covering, which covering
is closely attached to the hinder part of such inner portion, but extends far
away from the antei-ior part ; and, in addition to this, the progressive motion
in this species originates in an alternate enlargement of the longitudinal and

OF THE PHYTOZOA.

127

transverse diameters, and is so slow as to amount at the utmost to no more
than 1-40"' per minute. The form of the body resembles that of Amoeba
princeps (Ehrenberg). The vesicle in the hinder part of the body, which
was fli-st described by Ehrenberg as a mouth, and afterwards as an ovarium,
is also present.

"After fom- or five days the Amoeba assumes a spherical shape and becomes
motionless, the vesicular body expanding and contracting rapidly as before,
in a manner similar to what takes place in many Vorticellce. These spherical
motionless Amcebce are then for the most part united by a mucilage into
groups of from ten to twenty. The mucilage appears to be produced by the
decomposition of a cast-off external skin.

" In about a fortnight after the commencement of the experiment, a green
point appears in the interior of the spherical colourless body of the Amoeba ;
this point gradually increases in size until it fills up the entire hoUow of the
Amoeba, and after becoming covered with a cuticle it escapes in the form of
an eUiptical bright green cell, 1-300"' in diameter, resembling a Protococcus.
It exhibits a round transparent cavity, devoid of chlorophyll, corresponding
in size and position to the vesicular body of the Amoeba, and resembling at
its coloiu'less apex the motile gonidia of Cladophora. A few days later the
eUiptic or roimdish cell lengthens, a fonnation of transverse septa commences,
and the imiceUular Alga becomes an articulated one.

" AH these transformations of Phytozoa into Spirilla, Vibriones, Monads,
Amoeba;, unicellular and articulated AlgjE, may be observed not only in the
detached Phytozoa, but in those which remain in the interior of the sections
of the antheridia. In those antheridia of which the Phytozoa are not fully
ripe, the Amoebce are seen to originate in the middle of the internal mass of
phytozoary cells : some of them make their way out thi'ough the softened
mass of ceUular tissue ; but others remain in the interior of the antheridium
imtil theii' development into an articulated Alga.

" Contemporaneously with Amoeba, and often earlier, there may be seen,
amidst the mass of Monads, bodies very similar in form and motion to the
genus Bodo (socialis), and which increase by transverse division ; they have
the front end furnished with a long whip-shaped antenna or cilium similar
to that of Euglena. At their fii'st appearance, their motion, their change of
foi-m, and their whole exterior differ so Httle from the earliest states of
Amoeba, that at this period they cannot be distinguished. In these early
stages they both resemble Chlamydomonas destruens of Ehrenberg.

"The above forms uniformly make their appearance, and always in the
succession above described. It is time that other fonns, such as Uvelloi and
even Leptomitce and Periconue, arc sometimes met with, the gems of which
may have been imported by the atmosphere during the observation ; but tlicse
organisms, wliich aliuays appear singly and after the commencement of the
observation, do not interfere with the above results when we consider the
immense number of the Phytozoa and their uniform and contemporaneous
transformations. If about a dozen preparations are made, and if they are
carefully covered with a beU-glass after each observation, and if caro be
taken not to extend the observations for too long a time at once, at least half
of the preparations will be free from all admixture of foreign organisms." '

Mr. Carter has advanced some remarkable statements respecting the de-
velopment of Amccbiform and other Infusoria from the so-called ' gonidial
cells ' of the mucous contents of various Alga;— as Chara, Nitclla Clad'o
phora, Spirogyra, and Hydrodictyon, and also of some Desmidicco and Fu
glene<B {A. N. IL 1856, xvii. p. 101). Again, ho finds (p. 114) the celb of
^piro^ryrfc pnrticulariy infested, during conjugation, with Euglen<^ which

aro

us

GENERAL HISTOllY OF THE INFTTSOBIA.

producod with sucli rapidity as would lead to tlie conclusion that the gems
from which they originate must have pre-existed in the cells in wliich tliey
appear (as in the Characea)), without interfering with their functions. " Young
Astas'm are also developed within the cells of Sim-oriyra to a great extent';
and although they at first have almost as much polymor2)liism as an Amceha,
still they retain their- cilium, and after awhile assume the form and move-
ments peculiar to Astasia. On one occasion I saw a large Amoeba with a
long cilium at one time assuming the fonn of an Astasia, and at another
that of an Amoeba, wliich thus gives the link between these two Infusoria.
The cilium, however, had not the power of the filament of Astasia, though it
occasionally became terminal."

Developments of a similar llhizopodous character are, he goes on to say,
fi-equent in Etujlena : — " I was led to notice this development by an apparent
metamorphosis of the cell-contents of some fixed and capsuled Euylence into
granuliferous Amoebce, of a pinkish colom-, within the old cell of Eiu/lem
itself ; and the presence of several such Amoebce creeping about the watch-
glass, while many of the cells of the Eugleme {viridis ?) were empty, or only
contained a little effete matter, left no doubt in my mind as to the origin of
both coloiu- and infusorium. It was also obsei-vcd in some instances, where
the contents of the Euglena had passed into an Amcebous mass, that the
latter underwent a kind of segmentation, so that several (perhaps eight)
small Amoebm were developed instead of one large one."

Of the nature of Phttozoa. AjfurAi and Vegetable Characters. —
The collection of organisms we have grouped together for convenience' sake,
and from want of a better arrangement, under the name of Phj/tozoa, is
actually so heterogeneous that no general discussion respecting the nature of
them as a class is practicable, whilst, at the same time, a separation between
vegetable and animal forms is equally impracticable. The remarkable phases
of existence through which any one species may pass upsets aU our notions
based on presumed constant characters : for, as we have seen, one and the
same being may at one period of its existence exhibit in a preponderating
degree the vital phenomena of an animal, at another those of a plant,
whence has arisen the hypothesis of the metamoqjhosis of plants into
animals, and vice versd, — an idea that has found little favour, being opposed
to the prevailing belief of the fixity of natiu-e imposed on all beings. The
real fact of the case is, that we have no certain criterion between the two divi-
sions of organic natiu'e which can be relied on and practically resorted to in
cases of difiiculty, such as many of the Phytozoa present.

Some natui-alists have broached the notion that the phases of existence of
a presumed animal or plant, which resemble in outward aspect supposed
independent species or genera, are not identical with them ; so that, for
instance, the animal-loolcing Amoeba Hartig met with in the developmental
scries of Phytozoa of antheridia should not bo considered really an animal
Amoeba, but merely a vegetable mass simidating one. So, again, in Profo-
coccus they would deny anything but external general cliaractei-s to exist in
common between its forms of development and the seveml genera Colin would
assimilate them witli. There may be some truth in this supposition — there
may be real animal organisms and true vegetable coinciding in form, yot
distinct in natiu-e ; but the onus probandi rests with those who will make
this distinction,

HoM'over this may be, the advance of science has rendered it ceitain that
some families and genera which Ehrenberg, and most obscrvoi-s before his eni.
reckoned among animals, are rightlj' to be numbered among jilants, whilst
of others, again, it must still be said their position is doubtful. Deferring

OP THE PHYTOZOA,

129

at present a detailed review, we will confine ourselves to a few general obser-
vations on the natiu-e of the several families brought together under the head
of Phytozoa. The Monadina (XVIII.) of Ehrenberg comprise a multitude of
beings differing vddely among themselves, and, for the most part, not placeable
with certainty either among plants or animals. Of the genus Monas, especially,
it may be said that its species are, with few or no exceptions, mere phases of
being of other organisms. Of other genera the like may be presumed, although
the organisms in whose cycle of life they enter as one of the links have not
been determined. Not a few are doubtless zoospores of Algae or of micro-
scopical Fungi.

Uvella (XVIII. 5) is, in the opinion of most authorities, a vegetable struc-
ture (see p. 134) ; but Cohn {Entw. p. 115) stiU seems disposed to consider it
an animalcule, and represents Anthophysa (see p. 135), which has likewise
been extensively behoved to be a parasitic Alga or Fungus, to be an animal
Uvella surmounting a branching stem. PoVytoma is another disputed posses-
sion between zoologists and botanists : among the most recent advocates of its
animal character is Schneider (see pp. 136-139).

The Cryptomonadina would, in the language of naturalists generally, be
called 'encysted' Monadina, and, Kke this family, are divisible into true
vegetable and into doiibtful animal organisms, the former certainly prepon-
derating. The next two families, Volvocina and Vibrionia, and more especially
the former, may without hesitation be counted with plants, whilst the remain-
ing one, Astasicea, the majority of naturalists reckon among animalcules.

Habitats. Occtjebence in masses. Colotjr caused by theie AccuMtrLA-
TioN. — By far the majority of known Phytozoa are of a freshwater habit ;
yet it may be that, were the search as diligent, marine species might be
found in nearly equal abundance, particularly in inland and shallow seas,
gulfs, or lakes affording appropriate habitats for the larger Algae. Monads
and Vibrios, Bodos, and the Cyclidia of Dujardin, are probably the most
abundant and widely diffused of all created organisms, — a fact not remark-
able when it is considered that those genera represent the ' primary or ger-
minal stage of so many organized beings, both animals and plants. They
make their appearance, in collections of water and in infusions, before all
others, and, unhke most microscopical creatures, find a fitting habitat in foul
or decomposing fluids as well as in sweet water. They also propagate them-
selves with such astonishing rapidity, that the fluid or other medium in
which they occur becomes coloured by them. However, this very rapid de-
velopment, and this capability of colouring the surrounding medium, are not
restricted to the genera named, but are partaken by others among the Phy-
tozoa,— for example, Uvella, Astasia, Euglena, and the genera of Volvodmce,
\ all of them denizens of pure water, incapable of existence in impure, stagnant,
and decomposing liquids.

The coloiir presented by their accumulation in large numbers, varies
according to the species. Thus, the Astasia hmmatodes and Euglena san-
guinea give a blood- red colour to water. The Monas ( Vibrio) prodigiosa is
j| - stated by Ehrenberg to be the cause of the blood-Uke spots which have made

5 their appearance at times in bread and meal, much to the consternation and
dismay of the ignorant and superstitious ; and, again, the Haimatococcus or the
I red-coloured stage of the Hysginum of Perty is the cause of the phenomenon
^ of red snow. A green colour is much more frequent, and due to a larger
• variety of Infusorial organisms; such are Monas bicolor, Uvella Bodo, Cryp-
tomonas glauca, Oonium, Chlorogonium, Etiglena viridis, Chlamydomonas
iPandorina, Volvox, Stephanosphmra, and others. '
Besides becoming thus obvious to common observation by their colour

130

GENEEAL.HISTOfiY OF THE INFTJSOEIA.

many Phytozoa render themselves so by the evident masses or accumulations
they form. The dust-like stratum frequently noticeable on the suiface of
water, or at the sheltered margins of ponds, is often composed of various
genera, such as Euglena, Chlorocionium, Pandorina, and Gonium, more or
less intermingled with other Infusorial beings, such as ciliated Protozoa,
DesmidieDe, and Diatomea3. The stratum at times assumes the appearance
of a slimy film, at others of a frothy scum.

Moreover, the variable affinity of different genera for light will cause a film
at one part of a pond to differ iu its composition from that at another, when
the degree of exposure of the two is different. Fm-ther, there may be a
transition of colour, by the changing phase and attendant change of hue of
these organisms, or by the eff'ects of the sun's heat and Hght at noonday,
and of the darkness of night. Hence a pond which may be coloured green iu
the warmth of the day, when the sun's iufluence brings the Phytozoa to the
surface and causes their rapid development, may iu the morning and evening
become quite clear, o-\ving to their settlement at the bottom.

Of the modes of obtaining the Phytozoa for examiuation there is nothing
special to record, except it be a plan mentioned by Colin in his accoimt of
StepJianosjihcera (A. N. H. 1852, x. p. 405) : — "At theu- stations," writes this
observer, " the Steplianosphcera-ST^liexes, occur mingled with Chlamydococcus,
but by no means in the abundance requisite for the investigation ; and although
green clouds do coUect at certaiu points in the water whoUy composed of our
Volvocinece, it is difficult to extract sufficient of them for examination, since
they immediately start apart when touched. I succeeded in overcoming this
inconvenience by a simple means, so as to bring thousands of these elegant
organisms on to the object-holder at any moment. I took, namely, a flat
bottle with a short narrow neck, and nearly filled it with the water contain-
ing Stephanosphcerce, stopped it with a cork, and then laid it horizontally, so
that the cork partly dipped in the water. In a few hours almost all the
Steplianosplicerce in the water collected on the cork, which was covered with
a green coat, composed exclusively of the revolving spheres, while the rest of
the water in the bottle contained only Chlamydococcus, and scarcely any
StepJianosjjJiaircc ; so that when I wished to examine them I had only to take
out the cork, and a drop of the water adhering to it fiu-nished me with aU the
stages of development of our organism simultaneously in very large nmubers.
After a short time the Stephanos2yJio37~ce had again assembled on the cork."

Por a more satisfactory elucidation of the Phytozoa, of theu- stnicture and
physiological action, it is necessaiy to enter into more detail ; and since there
is so much structural diversity among the several groups or tribes, this more
leng-thened account must be given of each tribe separately. And first —

FAMILY I.— OF THE MONADINA.

(Plate XYIII. 1-28.)

In the systematic portion of his great work, in 1838, Ehrenberg instituted
the following genera of Monadina, \iz. Monas, UvcUa, Poh/toma, Microghna,
Phacelomonas, Glenomorum, Do.vococcus, CUlomoiws, and Bodo. Subsequent
researches led him to add the genus Chlorastcr, and to remove Pohjtoma in
order to unite it with a newly discovered genus, named by him Spondyhmonnn,
in a distinct family, the Hydromorim. This family, however, deserves no
special consideration, but wiU fall vrithin the compass of our general remarks
on the Monadina, as vdll also the genus Anthophysa, in accordance with the
results of Cohn's researches. (See Part II., Systematic Histoiy of Monadina.)

OF THB PHTTOZOA.

131

Very little observation and reflection will soon convince the student that
the members of tliis group of beings can be distinguished by no such constant
definite chai-acters as suffice to establish genera and species with any pre-
cision ; theii- history is too imperfectly known, and theu- individuality is un-
proved. If they make their appearance in a fluid, it is only transitory ; for
they are soon replaced by a difterent series of existences, and direct observa-
tion has shown many of them to be no other than transitional phases of life
of other organisms. Thus, Dujardin advances as an apology for his attempted
classification of Monadina, that the generic distinctions he has essayed to
make " ai-e entirely artificial, and simply intended to facilitate the naming of
Infusoria which may have been meb with in any particular infusion, but
which, when better known, may prove ia some instances mere varieties of one
and the same species" {Hist. Infus. p. 273). Siebold entirely rejects this
family of Monadina from the Infusoria, believing them only embryonic forms,
and chiefly zoospores of Confervae, &c. (Anat. d. wirbellos. Thiere, 1848,
p. 8). In so doing he has had many approvers, — among them the eminent
natiu-alist M. Agassiz, who thus writes : — " Eecent investigations upon the
so-called Anentera have satisfaetoiily shown, in my opinion and in that of
most competent observers, that this type of Ehrenberg's Polygastrica, without
gastric cavities and without ahmentaiy tube, are really plants belonging to
the order of Algae in the widest extension of this group, while most of the
Monas tribe are merely moveable germs of various kinds of other Algae "
(A. N. H. 1850, vi. p. 156). Nevertheless the character of this treatise renders
it necessary for us to present Ehrenberg's views of organization. According to
these, " the Monadina are iUoricated, with a homogeneous body, and no external
appendages except cilia, having many separate gastric sacs or vesicles, but
no alimentary canal connecting them, and a bisexual or hermaphrodite pro-
pagative system. They multiply by simple and complete self-division of the
body into two, four, or more individuals. The uniformity or unvarying
external form may be considered one of the principal characteristics of the
family ; for no one of the Monadina can voluntarily alter the shape of its
body, nor can it extend any portion of it and then contract it again. Pro-
pagation by ova is assumed of all the Monadina, and by living young, or
viviparous reproduction, in Monas vivipara. Some of them have an eye--
speck, but no vascular or respiratory system is discernible."

Although the general characters of the Monads are rightly delineated in
this account, yet the peculiar hypothesis imphed wdll not at the present day
find supporters. Dujardin denied the presence of an enveloping skin or
integument ; and if a separable distinct tunic is intended, that natiu-alist is in
the right ; yet it would be an error to ignore the existence of a laj-er of
different consistence to the contained matter, i. e. of a peUicle. Besides such
a peUicle, some Monads, at least, have the power of secreting around them-
selves a second external envelope or cyst, or of ' encysting ' themselves.
When thus transfoi-med, Ehi'enberg woidd not recognize them as Monadina,
but as Cryptomonadina, or loricated Monadina. Hence one som'ce of error
in his chstribution of these minute microscopical forms.

The invariabihty of form and incapability of extending and retracting the
body, so prominently advanced as special features of Monadina, Dujardin
does not admit as facts, but, on the contraiy, states them to be without
integument, and susceptible of adliesion to one another or to foreign par-
ticles, and to be capable of stretching themselves out so as to alter thcii- fom
even so far as to produce an expansion which may at times be mistaken for
another filament. Some Monadina, he adds, can, while freely swamming
about, change their form, and by so doing approach the character of Amcehce.

K 2

132

GENEBAl HI8T0BY OF THE INFXTSOEIA.

This power of the Monadlna to become polymorphic is likewise alluded to by
Mr. Carter (A. N. H. 1856, vol. xviii. p. 122).

According to modem phraseology, we might describe these beings as com-
posed of protoplasm enveloped by a pellicle, and as having an extension of the
protoplasmic mass developed in the form of a flagelhform filament, to serve
as a locomotive organ. The presumed gastric cells are the vacuoles in the
protoplasm hoUowed out spontaneously within it, and ever changing in posi-
tion and magnitude. Dujardin afiirms that they at times form near the
surface, open externally, and on again closing up include foreign particles
which have found their way within them, and that they thus act in some
measure as instruments of nutrition in aid of the general process carried on
by endosmose or absorption.

That the Monadina had a mouth communicating with the ' gastric sacs,'
Ehrenberg believed to be demonstrated by the introduction of particles of
colour within those cavities from vrithout. " The nutritive apparatus," he
tells us, " may be readily seen in some species in their ordinary state (for
instance, in Monas guttula and M. vivipara), whilst in others it is proved by
using coloured food (for example, in Monas Termo and M. sodalis). It consists
of several distinct or separate cells (from 8 to 20), not aU filled at the same
time, but one after the other. These are always invisible when empty, but
when filled with limpid fluid appear Hke so many lucid vesicles." Cohn states
that he can confirm the accuracy of Ehrenberg's observation of the entrance
of colouring particles into some Monads, and therefore inclines to the belief
that such examples must have an oral aperture, and be of an animal nature
(Entw. p. 162). To this he adds that many of the Monads of Ehrenberg
may really be swarm-spores of microscopic Pungi ; still he holds it to be
improbable that true plant-cells should take up within them indigo-particles.
So, at p. 148, when remarking on the precise similarity in all visible features
of the swarm-spores of Achlya prolifera with Trichodina grandinella and
Bodo saltans, he says Ehrenberg's Bodo eats indigo-particles, which is not
the case with the form in question.

What weight should be attached to these observations of the reception of
molecules of colour within Monadina, as proving a mouth and stomach-cells,
must be decided by further experiments. Sometimes, possibly enough, when
the minuteness of the objects concerned is remembered, the colour-grains
have not actually been within, but above or below them, on the surface ; and,
again, other experimenters damage the force of the argument by affimdng that
they have succeeded in getting colour taken up by Diatomese, and by undoubted
vegetable-cells. This statement has been made, among others, by Braun.

After the consideration given in a previous page to the nature of the
supposed eye-specks, farther reference to them here is uncalled for.

Concerning the modes of multiplication, the great BerHn micrographer is
correct in his account of the process of fission ; yet few will join ynth him in
describing ova and viviparous reproduction among Monadina, or in imagimng
distinct male and female generative organs — in other words, an hennaphrodite
(monoecious) structure. Certainly the phenomenon Weisse witnessed in
GJilorocjonium euchlorvm, of the development and subsequent discharge of a
host of yoimg germs, might be termed viviparous reproduction ; but it is no
other than the usual plan of develoi)mcnt of microgonidia among Algffi. In
fact, no one has witnessed the development and extrusion of germinal ova,
although the brealting up of the substance of Monadina into minute particles,
by the process of diffluence or by often-repeated fission, and the reproduction
of gonidia may be constantly noticed. Perty so far countenances Ehrenberg's
views as to affirm the development of Monas vivipara and of M. Lens by

OF THE PHYTOZOA.

133

germs which, whilst still -witliin the parent-cell, exhibit an oscillating move-
ment. He would even extend the phenomenon to all Monads ; yet we regard
it as no other than that of gonidial development. Another circumstance
this same writer points out is, that in MoTias Lens and allied forms,_ the
anterior individual produced by transverse self-division is 3 to 4 times
smaller than the posterior, and that in Tetramitus rostratus, where longi-
tudinal fission prevails, the right segment is much less than the left. It is
this unequal segmentation of Monads which induced Dujardin to represent
their multiplication to occur by the detachment of a lobe or of an expansion,
and not by actual self- division : but in our opinion such a distinction is too
refined ; for the term self-division has a meaning wide enough to embrace the
phenomenon of fission whether by equal or unequal segments ; indeed the
latter variety is sufiiciently common where no difficulty is felt in reckoning
it a mode of self-fission.

In further elucidation of this act of segmentation in Monadina, we may add
the following remarks from Schneider (A. N. H. 1854, xiv. p. 327-328).
Speaking of Qhilomonas Paramecium, this author writes — "Whatever number
of these animals may be observed, no trace of division will ever be remarked
in them. Very rarely we may see two individuals adheiing by their middle,
evidently produced by a longitudinal division. We shall endeavour to ex-
plain this. On close examination, one or two reddish lines may be seen
running backwards from the bottom of the indentation, which might readily
be taken for organs lying in the interior of the body. I have convinced
myself, however, especially by the comparison of the process of division in a
species of Bodo, that these lines indicate furrows, which gradually divide the
whole by cutting deeper and deeper on each side. As during this process
the animal undergoes no change of form, except in becoming a little broader,
and the division takes place along its whole length, the process must readily
escape observation. The anterior end is always a little thicker ; the farrows
consequently are deeper and more distinctly recognizable in that part. With
a suitable arrangement of the microscope, it is evident that, the two furrows
being looked at simultaneously, two reddLsh lines are seen. It is only in
rare cases, when the division has taken place more slowly in some particular
spot, that the two specimens must endeavour to tear themselves free, ,and
thus, by twisting in contrary directions, di-aw our attention to them. That the
process of division is effected in a similar manner in other Monadina, appears

from an observation of Ehi-enberg's upon Cryptomonas cylindrica (p. 42) : * I

saw no instance of constriction or fissation ; but two individuals were swimming
whUst adhering together, which might lead one to suppose that a longitudinal
division from behind forwards had taken place.' And it is not improbable
that the specimen represented by him on tab. n. fig. xix. 2, with two seminal
glands (nuclei?) and two longitudinal Lines, was in the act of division."

That Monads are only the fijst and simplest stage of existence of numerous
animal and vegetable organisms, is an undoubted fact ; but, if we may credit
some observers, theii- transformations are, in certain cases, veiy extraordi-
nary. Thus, Stein represents the nucleus of encysted Vorticcllce to break
up into Monads (the Monas colpoda or M. scintillans), which by vaiious in-
termediate stages become reconverted into VoHicellcB. So, again, Hartig
(J". M. S. 1855, p. 52) and Carter (A. N. H. 1856, xviii. p. 122) represent
the conversion of Monads into AmoehcB, the former by a coalescence of a group
the latter by the simple assumption by individual Monads, on losing their
cilia, of polymorphism. Lastly, the resemblance of the zoospores of Acldya
to Bodo saltans has already been mentioned to be complete in every respect
save in the non-imbibition of colouiing particles.

134

GENESAL niSTOET OF THE INFUSORIA.

Few details, excepting those comprehended in attempted generic and specific
characters, have been published by observers on the genera of Moimdina in
general. Uvella, Anihophysa, and Polytoma have, however, received more
attention than the rest ; and the results arrived at we ^vill here abstract.

Uvella is, in the system of Ehrenberg, characterized by the aggregation of
numerous Monads (XVIII. 3), severally undistinguishable fi-om simple isolated
species (XVIII. 4), into spherical or mulberry-like masses, freely moveable in
the surroimding liquid. The individuals, like those of the genus Monas, have
a locomotive organ, consisting perhaps of two cilia, situated close to the
mouth at the anterior extremity, but neither tail nor eye-speck. They pro-
gress in the dii-ection of the longer axis of the body, and are capable of com-
plete self-division. . In the best-examined species, U. glaucoma, Ehrenberg
represented large iatemal vesicles, a double filiform proboscis, and a great
number of small colourless granules, conceived to be ova, lying between the
nutritive sacs. He supposed it to propagate both by transverse and longitu-
dinal self-fission, and stated that, on feeding it with indigo, as many as twelve
stomachs were filled, and that sometimes little blue particles like undigested
matter might be seen voided from its mouth, and, lastly, that he had dis-
cerned several green Monads within its body, which it had eaten, and which
proved it to subsist on prey directly transmitted into its interior. Individual
Monads, he added, can detach themselves from the mass, live apart for a time,
and again become members of the colony.

This account was rejected by Dujardin, who denied the existence of a
mouth, of gastric ceUs, and of ova, and doubted the occurrence of true self-
division. He likewise never witnessed the re-attachment into masses of the
Monadiform individuals after being once separated, but believed that the re-
union of certain Monads, occasionally observed in infusions rich in these beings,
is a fortuitous result of the glutinous nature of their sm-face.

These strietm-es of Dujardin are, without doubt, in general very just. The
supposed mouth is the clear space seen at the anterior extremity of most
unicellular organisms, whilst the supposed stomach-sacs are no other than
chlorophyll -vesicles or, otherwise, vacuoles. The green Monad-like cells seen
by the Berlin micrographer were probably starch- or chlorophyU-ceUs, or, it
may be, gonidia ; and it was a mere assumption to represent them as swal-
lowed particles.

Itzigsohn, Cohn, and Mr. Busk make Uvella, or at least an organism like
it iu all essential external features, a phase of existence of vegetable struc-
tures,:— the first-named of Oscillatoria (J. M. S. 1854, p. 190), the second of
Protococcus, the last of Volvox. Itzigsohn describes the i^a^Zejwi -phase of
Oscillatoria as breaking up into microgonidia which collect themselves in colo-
nies, resembling, according to the presence or absence of coloured contents,
Uvella atomus, U. glauca, Bodo, &c. Cohn's \icws ai-e sufficiently represented
in our remarks on Protococcus (see p. 124), and need not be here repeated.
Busk represents the ciliated zoospores of Volvox (T. M. S. i. p. 39) as sub-
dividing into minute ciliated ceUs (i. e. microgonidia), which " foiiu by their
aggregation a discoid body, in which the separate fusifoi-m cells are connected
together at one end, and at the other are free, and furnished each with a
single cilium. In this stage these compound masses become free and swim
about in the water, constituting in fact a species of the genus Uvella, or of
Syncrypta of Ehrenberg." If these representations be correct, Uvella is but
a phase of existence of Volvocina and of Oscillatoria, and probably of other
plants. If this be not allowed, then the alternative remains, of supposing
both a vegetable and an animal organism partaking like characters and
qualities.

OF TITE PHTTOZOA.

135

The genus Anihophijsa (XXVI. 2) has been more particularly studied by
Dujardin and Cohn. Ehrenberg provisionally placed it among the Vorticel-
Una as a doubtful species of Epistylis, as he was imable to detennine whether
it possessed a wi-eath of cilia at its head or only a single filament : if the
latter, he remarked, it would belong to the Monads. MiiUer, its discoverer,
had indeed more rightly seized on its trae position by associating it Avith
Volvox. Dujardiu subsequently made out its affinity with Uvella, and adopted
M. Bory de St. Vincent's generic appellation for it. In this determination of
its position Dujardin has the weighty support of Cohn, who has recently sub-
mitted it to careful examination. Dujardin's description is very accurate, and
win serve our pui-pose. " It is very difficult," he writes, " to distinguish a
Uvella from a free Anthophysa ; but no difficulty will exist if some of the
branching supports of the latter are seen in the surrounding fluid. These
supports have an arborescent figiu-e irregularly branched, are brownish at the
base, but cleai-er and even diaphanous at the extremities of the branches,
which are themselves nodular or rugged ; they are secreted by the animals,
and are found affixed to the sides of the vessel in which water containing
these Infusoria has been but recently placed. Each group of animalcules is
at first fixed on the diaphanous extremity of the branch which it has secreted
(XXVI. 2) ; but any agitation of the liquid, or sudden shock, easily detaches
it, and it then moves in a revolving manner in the liquid. This movement is
the result of the simultaneous action of the flagelliform filaments with which
each individual of the colony is provided. When, moreover, a group has been
detached, whether accidentally or spontaneously, isolated individuals may bo
seen moving aboiit precisely like Monads with a single filament. The branch-
ing support is at first soft and glutinous, but gradually acquires consistency
and a brownish and homy aspect, when it seems no longer to participate in
the life of the animalcules, and recalls to the mind the constniction of the
fibrous skeleton of certain sponges. It is conceivable either that the branches
themselves bifurcate, or that the division is the consequence of the multipli-
cation by fission of the groups of animalcules."

Cohn has little to add to this account. He describes the probably chitrnous
stem to be invested externally by a brownish mucilaginous layer ; and also
finds that from 2 to 8 and from that to 20 Monads may be aggregated at the
extremity of the branches. Frequently a branch is bare at its point, having
lost its animal colony ; and it would seem that the whole of the gi'oups are
in succession thrown ofi' and dispersed as free Monads and as UveUa-lilie
groups. Cohn, indeed, intimates his belief that Uvella and AniJiophysa ai'e
not actually distinct genera, but mere representatives of two conditions of
the same animalcule. UnEke Ehrenberg, he failed to get indigo-particles taken
up by the UveUa-lilce beings.

Before arriving at the conclusion that Anthophysa is no other than Uvella
Uva seated on a branching stem, and of animal nature, he canvasses the
question if this organism be not rather the myceUum of a Fungus bearing its
spores at the extremities of its branches, and decides against the supposition
chiefly from the irregular and indefinite multiplication of the monadifonu
members of the groups, from the detachment of these en masse instead of by
separate spores, and from the want of evidence to show that, when these
Uvclla-lilce groups arc detached, they assume the quiescent or ' still ' condition
and germinate into an arborescent mycelium like the parent, to develope in its
turn terminal masses of spores.

The branching stem has been described by Kiitzing and others as a micro-
scopical Fungus (ConfeiTa), under the name of Stereonema, and several species
instituted ; but Cohn points out its analogy with the pedicle of Oomphoncma

136

GENEEAL HISTOEY OF THE INFTTSOEIA.

and other Diatomese, in which both the branched stem and the beings it
supports are ahke part and parcel of the same organic structure. He has
met with fibres supporting but one or two Uvella-bundles, and others like
little trees beaiing ten such. The consistence of the stem is such that it
resists the action both of sulphuric acid and of solution of potash.

One other genus of Monadina, viz. Polytoma (XVIII. 5), has received special
attention from Schneider, Cohn, and Perty ; it nevertheless still remains in
that neutral ground claimed both by zoologists and botanists. Ehrenberg at
first placed it in the family Monadina ; but having subsequently met Avith a
similar form, Spondylomoi^m, he instituted a new family, Hydromorina, to
include the two genera, and set forth as its chief diflerential characters the
aggregate or compound nature of its members, dependent on imperfect fission.
He asserted also that individuals set free from the groups enter on the same
cycle of fission and compound development, and form similar groups. Poly-
toma was described to be destitute of an eye-speck, to have a trimcated
mouth and a dehcate double flageUiform proboscis, and, from repeated racom-
plete self- division, to form a mulberry -like mass, which eventually breaks up
into isolated Monads. " The ova," he adds, " from their minuteness and the
want of transparency, have hitherto eluded observation (XVTTI. 5) : but the
alimentary organization is, on the contrary, clearly demonstrable ; for al-
though for a long time the entrance of coloured food could not be displayed,
yet at length, by using a magnifying power of 600 to 800 diameters, the
entrance of indigo-pai'ticles into their bodies was rendered evident." In
addition to these structui'es, he mentions a large contractile vesicle as a msde
sexual organ, and a white spot at the anterior part of the body as a seminal
gland. In all essential particulars the associated genus Spondylomorum was
stated to agree with it, except in having a dorsal eye-speck.

Dujardin confesses his inability to distinguish by any definite characters
between Uvella and Polytoma ; he would seem, however, not to have per-
sonally investigated the latter. Cohn, after examraing both, declares them
to be identical in all particulars except that in Polytoma chlorophyll is absent,
and that it inhabits decomposing fluids along with Clilximydomx)nas pulviscu-
lus. However, it is to Schneider that we are indebted for the most complete
history of this organism (Inaugural Dissertation, " Symholce ad Infusorium
historiam naturalem," Berlin, 1853, translated in A. N. H, 1854, xiv. p. 321).
We extract the following copious details from the translation : — " Polytoma
Uvella is of an oval form ; it is from -jfu^^ Tu^'^ mch. long, and about
half that width. At one end, which, mth Elu-enberg, we will call the an-
terior extremity, it bears two filaments as long or longer than the body.
When the living animal is examined under a magnifying power of 300 dia-
meters, the body appears to be bounded by a simple outline. But in many
instances, and especially when a large specimen can be found at rest, it may
be seen that the internal substance of the body is suiTounded by a thin and
perfectly clear membi-ane, from which it is separated by a distinct space.
When the investing membrane is more closely attached, its existence may
always be demonstrated by the employment of reagents to produce the con-
traction of the substance of the body : chromic acid and solution of iodine in
chloride of zinc are the best substances to employ, the latter especially, a^ it
at the same time communicates a brown colour to the internal sac (PI. XX.
fig. 2). Under certain circumstances, the investing membrane divides into
minute granules, assuming when viewed from the side a regular necklace-
like appearance (fig. 8). A reproduction of the membrane then takes place.
The substance of the body is perfectly clear, with the same refractive proper-
ties as that of Amoeba. About the middle lies a clear globular nucleus, sur-

OF THE PHYTOZOA.

137

rounded by a narrow reddish halo (figs. 1, 2, 3, 8). DUute acids render
this more distinct. At the anterior extremity, close to the margin, there are
two reddish vesicles, the contractions of which may easily be recognized in
individuals in a state of repose. The hinder extremity always contains a mass
of granules with dark outlines, which are not altered by acetic acid. A weak
solution of iodine in iodide of potassium gives them a deep blue colour, gene-
rally verging upon black, as it is difficult to hit the right quantity of the reagent
to be added. The fine blue colour is better attained by the addition of dilute
solution of iodine in chloride of zinc, as with this the granules become slightly
liquefied, and when left standing for some time even form a blue paste. Muriatic
and sulphm-ic acids also dissolve them, so that the subsequent addition of iodine
gives the whole body a blue colour. When the putrefaction of the infusion
is going on veiy rapidly, the granules fill the entire body. They are not
arranged in balls like the nutritive matter in the bodies of other Infusoria ;
and it is by no means probable that they are taken in from the exterior.
Besides the two contractile vesicles, single, non- contractile, reddish vacuoles
are seen scattered through the substance of the body.

" The starch-like granules are often converted into an indigo-blue pig-
ment, which is then partially dissolved, and colours the whole parenchyma.
Such specimens as these stiU. retain the power of division, so that there
can be no doubt as to their identity with Polytoma Uvella. Individuals
were also frequently met with of which the substance of the body was of
a uniform green colour, but which in other respects agreed exactly with
Polytoma.

" Deviations from this normal form never occur singly in the same vessel,
but always make their appearance simultaneously in a great number of indi-
viduals. Certain peculiarities of their abode appear therefore to have an
influence upon the form. Very compressed forms are rare. However, it not
imfrequently happens that, whilst the investing membrane retains its normal
form, the substance of the body is not equally distributed in its interior.
Sometimes it lies to one side, so as to fill only half the interior of the sac ;
sometimes it is entirely collected in the anterior, and sometimes in the pos-
terior extremity ; in the latter case it is connected with the anterior extre-
mity by a slender filament (fig. 14). In infusions in which fermentation has
long ceased, and which contain a large quantity of brown humus -like matter
but very small portions of nitrogenous substances in solution, the two last
modifications of the parenchyma are most frequently met with. At the same
time the starch-like'granules disappear, the substance of the body acquires a
darker fatty outline, and finally disappears -with formation of the well-known
large vacuoles.

" The movements of Polytoma are the same as those usually ascribed to
organisms furnished with two filaments. "Whilst in motion the filaments are
always in front, the animal rotates upon its axis, and this again describes
circular vibrations upon a central point. If a movement in the opposite
direction is taking place, the animal is endeavouring to turn the anterior
extremity ; and until this is efi'ected it swims backwards. When a drop of the
infusion has been left for a few minutes upon a glass plate covered over -with
a piece of thin glass, a considerable number of the animals wiU be found
attached to both glasses by their anterior extremity ; the filaments are free
and it is probably by their vibration that the hinder extremity is made to
oscillate in the direction of the piano of the two filaments. They collect in
the same manner in crowds upon aquatic plants, as well as upon the sides of
the vessel containing them. Their mode of attachment is still unintelligible
to me. In any caee, some contrivance for this purpose, however simple, must

138

GENERAL HISTOET OF THE INFUSOUTA.

exist, either between the two filaments, or at the side of their points of issue
from the membrane.

" Diuing the swarming-state, a division of the substance of the body goes on
iminterruptedly at all hours of the day. The different stages of this process
follow one another with greater or less rapidity in proportion as the conditions
of nutrition are more or less favourable. Soon after the commencement of fer-
mentation in an infusion, the rate of increase attains its maximum ; it then
diminishes as the fermentation ceases, the offspiing at the same time undergo-
ing a diminution of size.

" The commencement of the process of division is indicated by the uniform
distribution of the granular substance. A constriction of the substance then
takes place, usually commencing on one side ; by tliis the body is divided
into two parts, which are still enclosed in the uninjured investing membrane.
Simultaneously with, or perhaps before the completion of this bisection, the
nucleus also divides (fig. 3). Although no constriction of the nucleus was
ever noticed, nothing certainly was observed to contradict the supposition
that the second nucleus was produced in this manner. The two halves then
become constricted from theii- siu-faees of contact, in such a manner that the
constriction of one half crosses that of the other at right angles (fig. 4). To
every depression thus produced on the one side there is a corresponding ele-
vation of the other. The quadrisection (figs. 9, 12) then takes place suddenly
as if by cutting, and without any appearance of a circular consti'iction, each por-
tion containing its proper nucleus. The divisions now acquire an oval form,
and arrange themselves in such a manner that the ends of the posterior pair,
which are turned towards the middle, alternate with those of the anterior
pair in the same place (fig. 12). In very favourable cu'cumstances (as for in-
stance at the commencement of fermentation), a third division into eight
parts takes place, each division being still furnished with a nucleus. As a
general rule, however, the young individuals acquire filaments soon after the
quadrisection, and move about in various directions within the investing mem-
brane, imtil this bursts and the young, which ai'e exactly like the mother
except in their smaller size, are set free. In favourable circumstances the
empty membrane remains with the two filaments. After the division of the
substance into four or eight parts, the investing membrane is always visible
without the employment of any reagents. This has not escaped Ehi-enbei^
(loc. cit. and tab. i. xxxii.) ; he explains the appearance as a consequence of a
superficial constriction. The filaments of the parent always appear to be con-
nected only with one of the yoimg individuals, although this is less distin-
guishable in the present mode of division than in that about to be described.

" In this the quadrisection takes place in another manner. After bisection,
the two portions shift their position in such a manner that the surfaces of
contact form a distinct angle with their original position. If tliis change of
position be but trifling, the quadiiscetion goes forward nearly in the manner
just described, and the arrangement of the developed young only diftcre as far
as is rendered necossaiy by this change of position (figs. 9, 12). But if it be
more considerable, the new surfaces of di-\asion ran parallel to each other and
nearly pei-pendiciUar to the surfaces of contact of the two halves. Tlic posi-
tion of the young indi^^dual^ is then completely diff'crent fi-om that seen in
the preceding case ; all four lie parallel to each other, with their longitudinal
axis oblique as regards the axis of the whole (fig. 10).

" This diftcrcncc may perhaps be explained as foUows : — Each portion lias
a tendency to acquire an oval form, so that soon after the bisection the ante-
rior portion extends itself posteriorly, and the posterior towards the front.
When sufficient time has not elapsed for the one dimension to predominate over

or THE PHYTOZOA.

■139

the other, the qiiadiisection takes place as in the former case ; but when, on the
other hand, one dimension has become predominant, the division into four takes
place in accordance mth the same law as the original division into two.

" The method of division fii'st described is always met with in the early
periods of an infusion, which are most favourable to the development of the
creatures. Towards the end the latter mode alone occiu's. This phenomenon
was so remarkable that, on the first occasion of my examining an infusion
towards the close of its action, I imagined that I had at first misunderstood
the mode of division.

" Under certain circumstances the individuals pass to a state of rest. They
are then completely filled with the starch-like granules, so that the nucleus
only appears as a reddish spot. The substance of the body becomes spherical,
and invests itself with a membrane which is frequently of considerable thick-
ness (fig. 7). In this state I have never observed them to undergo any divi-
sion or any other change ; and when dried the cysts still retain their contents.
When clear water is poured over them they do not retui'n to life, but would
probably do so in a fermenting iofusion.

" The mode in which the swarming individuals arrive at this state of repose
appears to be as follows : — The filaments are gradually shortened, their sub-
stance collecting at the free extremity in the form of a small knob, until at
last the filiform poiiion entirely disappears, and, in place of the filaments, two
vesicles are seen at the anterior extremity of the investing membrane. I
have observed a similar contractibility of the substance of the filaments in a
Bodo which is most nearly allied to Bodo grandis, Ehrbg. As this possesses not
three filaments only, as seen by Focke {Ehr. p. 34), but often as many as five,
the vesicles produced in this manner cannot easily be overlooked. I cannot,
however, state with certainty whether all the individuals which undergo this
change invest themselves with cysts. "When infusions containing Pohjtoma
are diied slowly, individuals with the vesicles just described are foimd in the
deposit, but no cysts ; and it is not impossible that such individuals may assist
in the continuation of the species in some other way."

After some valuable notes on other Infusoria, Schneider concludes his
history of Polytoma by the following arguments for its animal natiu-e : —

" That Polytoma is an animal may be maintained upon two grounds.

" 1. The constitution of the investing membrane. — As soon as the starch-Ulce
granules have been destroyed by the long action of concentrated sulphuric
acid, no part of the creatiu'e is coloured blue by iodine. Now we have no
more reason for believing that the vegetable eeU-mcmbrane must necessaiily
consist of cellulose, than that the animal cell-membrane shoiild not consist
of that substance, so that we are still compelled to seek for other chai'acters
for their distinction. These would be —

" 2. TJie contractile spaces. — A statement of Cohn has certainly rendered
it doubtful whether the occurrence of these is henceforward to be regarded as
an essential indication of an animal nature. He says, ' On the other hand
certain genera of Algae exhibit a stage of development in which, in cxternai
form, in the absence of a cellulose membrane, in the distinct existence of
ciliaiy organs of motion, red cye-lOce spots, vacuoles, and, according to a very
recent discovery, of internal pidsating spaces, they imdoubtedly appear very
similar to the Astomatous Infusoria.' If these pulsating spaces occur only
in unicellular Alga) provided Avith cUia, those perhaps should properly be re-
stored to their place amongst animals, notwithstanding the subsequent ap-
pearance of cellulose-membrane upon them. But if they occur in the swarm-
cells of the Confervac, they certainly cease to be a characteristic of animal
nature. Thus, if we are not yet in a position to refer Polytoma with perfect

140

GENERAL HISTORY OP THE INFUSORIA.

certainty to its proper place, there is decidedly no reason for excluding it
from the animal kingdom. We will not, however, venture to consider the
Infusoria fuiTiished with a mouth (Stomatoda, Yon Siebold) as formed, like
Polytoma, upon the type of a simple cell : for, high as we may rate the ad-
vantage acciTiing to science from the comparison of the Protozoa with simple
cells, difficulties stand in the way of its complete apphcation in the case of
animals of such complicated structure as the Vorticellce for example ; and
these cannot be considered as entirely done away with untO. the history of
their development has fui-nished proof that at no period does a fusion of
several cells take place.

" In conclusion, we bring together the results of the investigation as shortly
as possible.

" 1. Polytoma is an animal.

" 2. It is characterized by a clear investing membrane, which does not
consist of cellulose ; two contractile spaces in the substance of the body ; a
nucleus with a nucleolus ; two filaments ; and by the deposition of layers of
starch-hke granules.

" 3. The starch-granules may become converted into a blue or green co-
louring matter.

" 4. Polytoma divides within the investing membrane iuto two, four, or
eight parts, and propagates itself in this manner.
" 5. It passes into a state of repose."

These arguments will, we fear, not be deemed satisfactory to most natu-
ralists. That the investing membrane should not be coloured blue by iodine
is an unimportant fact in determining its natm-e ; for the same thing happens
with many undoubted vegetable tissues, and we are, besides, not sufficiently
acquainted with the chemical history of starch, cellulose, and aUied isomeric
substances, to appeal to their presence or absence as decisive of an animal or
vegetable nature. Then, again, as to the contractile spaces, these cannot be
considered peculiar to animal life, seeing that they are present in such gene-
rally recognized vegetable forms as Chlamydomonas, Gonium, and Volvox.

Moreover, Schneider himself describes starch -granules and chlorophyll-
vesicles within Polytoma, which, if these substances had any decisive bearing
on the question, would quite settle its affinity with plants, irrespective of the
constitution of the enveloping membrane. Besides, the whole history of the
organism accords so closely with the known phenomena of life and develop-
ment of the simplest plants, that this alone must carry much weight in fixing
its position in the scale of beings.

FAMILY II.— CRYPTOMO^^ADINA.

(Plates XVIII. 29—34.)

The Cryptomonadina, which follow the Monadina in the arrangement of
Ehrenberg, claim but a brief consideration, inasmuch as so little precise infor-
mation is obtainable Avith respect to them, and as the existence of possibly
aU of them as independent organisms is a matter of much uncertainty. The
genera enumerated were — Cry2Jtomonas, Ophidomonas, Urocentrum, LageneUa,
Cryptoglena, and Trachelomonas. To characterize the Cryptomonadina in two
words, they are encysted Monadina or Eugleneaj. Ehrenberg puts forward the
following account : — " They exhibit all the characteristics of the Monadina,
but have, in addition, an external diaphanous membrane or lorica, which
cither encloses them entirely — i. e. forms an urceolus, — or leaves one side
exposed, and so constitutes merely a shield — scutelhim. Locomotive organs,
in the shape of two delicate filiform and generally retractile filaments or pro-

OF THE PHYTOZOA.

141

boscides, extend from the mai-gin of the mouth in all the genera except Lagenella,
in which also, by the way, Wemeck thinks he has discerned them. Coloured
food has not been known to be received ; and hence the nutritive organization
has not been demonstrated: however, in six or seven species (nearly one-half the
family) internal gastric cells have been discovered. In two genera sensation is
exhibited by the presence of a coloured spot or ocellus at the fore part of the
body. Multiplication by complete division has been seen in some specimens."

Such is Ehi-enberg's account of Cryptomonadina. Dujardin has a parallel
family with it he names Thecamonadina, and details the following particu-
lars (op. cit. p. 323) : — " The Infusoria of this family having in some mea-
sure merely one negative character in common, viz. the non-conti'actiHty of
their integument, can be divided into several families according to the nature
of the enclosing membrane and the number and disposition of their locomo-
tive filaments. Thus, some are globular and others leaf-like ; some have a
hard, as it were stony shell, whilst others are covered only by a thin flexible
membrane ; some, again, have but one filament, others two similar ones or
two of different size, and others, again, more than two, UntH new observa-
tions have augmented the number and the knowledge of species, the differ-
ences just pointed out will merely serve to characterize genera which are
indeed much more really distinct in this family than in Monadina. The
Thecamonadina are in fact more advanced in organization than the Monadina ;
they are not, like the latter, produced in artificial infusions, nor do they change
figure and characters according to the medium in which they exist. They
stand ia the same relation to the Monadina that the Rhizopoda (ArceUina, or
Monothalamia) do to the AmcehcB : their organs are no more distinct ; but their
individuality is more pronounced."

" The Thecamonadina are all very small, although they may be rendered
^dsible to the naked eye by their accumulation in great numbers, and by the
colour they then give rise to ; their colour is usually green, .... but sometimes
red. They are mostly cognizable by the strfifhess of their body and the
uniformity of their movement." Dujardin ignores the stomach-sacs, the con-
tractile seminal vesicle, the testis,^ and the green ova which Ehrenberg attri-
buted to this family : he likewise can assign no value to the eye-specks as
generic features, and is compelled to deny the occurrence of shells in the
form of a shield, open on one side ; for those appearing so are merely flattened
on that aspect. He adds, the integument in all these cases is much more
roomy than the contents, from which it is separated by a clear space having
the appearance of a ring.

Perty adopts both the terms, Cryptomonadina and Thecamonadina, to ex-
press the two families under which he arranges the several genera enumerated
by Ehrenberg and Dujardin, together with some instituted by himself. This
is not the place to point out the distinctions he has drawn between the
two families so constructed ; but the original observations Perty has made on
some specimens wiU be of interest. For instance, he says that (op. cit. p. 81),
" "When the green animalcule of Trypemonas volvocina {TracheJomonas vol-
vocina, Ehr.) is about to self-divide, it contracts itself within its glass-like
globular shell, oscillates to and fro, whilst the motor-fibres become lost or
remain without further connexion with the animal, fixed in the circular
opening of the outer shell. Fission now proceeds in the usual mode iato
two and four mdividuals, which on their completion exhibit the red stio-ma
previously undistinguishable among the green molecules : the brealdng un
of the sheU, scarcely ^wwu^^ of a line in thickness, is eflFccted either bv
the movements of the contamed beings or by dissolution." The shells of
Trypemonas, Clionemonas, and Cryptomonas, whic' contain no silex in their

142

GENERAL HISTORY OF THE INFUSORIA,

composition, seem to be particularly prone to decomposition, so that their
empty shells or their fragments are extremely seldom to be met with in
water abounding in loricated Monads. " In Cryptomonas polymorpha I have
repeatedly witnessed this rapid breaking up of the shell ; the margin is resolved
into numerous drops Avliich separate fi-om one another, and in the course of
ten or twelve minutes the lorica spreads itself out as an inconspicuous mem-
branous structui-e. Moreover, in Chonemonas hispida a constant movement
is observed in the shell when the animal is about to divide, and when, as
almost always happens, the filaments are lost, or remain attached to the shell
without any connexion with the animal. Until the period of self-division
the connexion between the animal and sheU persists, for the latter is, at its
origin, simply the hai'dened periphery of the former ; but when fission hap-
pens this bond is ruptured and cannot be re-estabUshed, and the contained
animalcule, being thus set fi'ee, no longer moves with the shell, but in it, and
this in an uneasy, irregular manner." At p. 83 he goes on to say that in
Cryptomonas polymorpha internal germs (Blastien) are almost constantly
cognizable ; in smaller and young specimens in less abundance. In a pool
containing Utricularia in July 1848, he met with the dark green variety in
immense numbers, along with clear green germs from to -^-jj'", col-

lected in masses held together by a very dehcate pellicle, and either motion-
less or in active movement among the old individuals. In other varieties he
has seen similar germs. Thus, on pressiag the large brown variety the germs
escaped as independent isolated beings. In the hyaline variety ( Gliilomoiias
Paramecium, Ehr.) he not seldom witnessed astonishingly rapid development
by longitudinal fission ; in one specimen the two halves remained for a con-
siderable time tied together by a band, which became stretched thinner and
thinner by the long- continued movements of the two beings until it at length
gave way. After moving about for some time, vital energy is lost, and probably
one-half of the specimens sink to the bottom of the drop of fluid under obser-
vation. The germs in this hyaline variety are moreover very evident and
numerous. Amid the many specimens of nearly equal and minute size,
others much larger are not uncommon, fimiished with a red eye-speck.

Schneider gives {A, N. H. 1854, xiv. p.' 327) an account of Cliilomoiuis
Paramecium, difi'ering much from the foregoing. He describes it as having a
clear nucleus with a reddish halo around it, and, although he could distin-
guish no contractile space, observed a reddish vesicle always in the anterior
extremity, and, in direct opposition to Perty's observations, states that what-
ever number of these animals he examined, he never observed multiplication
by fission (p. 133).

In March 1848, Perty noticed Anisonema acinus (Duj.) in different stages of
development ; the smallest forms were evidently derived from the germs, about
JL'" in length, and circular ; by further growth they became eUiptic, and
presented a larger number of internal germs ; at the same time the fibres,
which are so easily seen in the full-growTi beings, were perceived with the
greatest difficulty in the smallest.

Among his Thecamonadina are enumerated two genera, named CJioncmonas
and Trypemoms: the latter is equivalent to Ehrenberg's genus Trachch-
monas ; but the former includes, besides Lagcnella, two genera whicli the
Berlin systematist placed in families far removed from his Ciyptomonadina,
viz. C7j(c<o(7?mft, placed among the Peridinia^, and Pautoinchum, classed with
the Cyclidina. Concerning the reproduction of these two genera, Perty has
some original observations.

In some decomposing water he met with Clioncmonas and Trypemonas in
great abundance— the greater part of a groon colom- with red cyc-specks.

OF THE PHYTOZOA.

143

without lorica, and of various dimensions. In both, the lorica fii'st made its
appearance as a smooth hyaline envelope, which grew stronger, then red, and
at length brown or blackish broAvn— becoming also in Ohonemonas still firmer,
and covered with asperities. Dming this transition from a soft periphery into
a shell, two sets of intersecting lines were at times visible, which by-and-by
vanished. Moreover, examples of Chonemooias occui-red which continued
smooth, and constituted the variety Ch. glabra. By using very high mag-
nifying powers to fully developed specimens of Trypenwnas volvocina, the
lorica appeared to be everywhere perforated, or more probably beset with a
series of depressions or thinner spots. On the shell becoming veiy dark, the
green contents and the red stigma ceased nearly or quite to be visible. Naked
Chonemonads and Trypemonacls are easily distinguishable from Euglence,
because their contractility is so much less, and consequently theii- actual round
form so much the more permanent. All these minute naked examples are
doubtless produced from germs : fission was witnessed' in no instance. Ordi-
narily the animal-Kke Clionemonas, furnished with a red eye-speck, had an
elliptical form prior to the constraction of the shell, just like loricated forms ;
yet ovate and obovate examples are also to be seen. Minute specimens are
poorer in endochrome, this material occuning only in one or two specks. The
locomotive filaments are absent at first, and after their appearance only gra-
dually attain the normal length. The construction of the lorica frequently
proceeds to completion in very small specimens, whilst large ones remain
naked, notwithstanding the formation of germs goes on in those where the
chromule is in a certain quantity. Many dead Chonemonads were encountered
having their contents either shrivelled up or even so completely removed as
to leave only an empty yeUowish-brown shell.

At a subsequent page (p. 131) Perty mentions certain abnormal forms,
among others Cryptomonas polymorplia, having but one instead of two fila-
ments, and at other times elongated into a tail-like process.

From all the preceding accounts of Cryptomonadina there seems sufiicient
to show that these beings are but a certain phase, the encysted state, of a
set of organisms which have a general resemblance to zoospores, or to simple
unicellular Alga3. The germs mentioned by Perty accord, to aU appearance,
with the microgonidia of other authors, and behave themselves in a similar
manner. Cohn observes {A. N. H. 1852, x. p. 335) — " Trachelomonas and
the analogous forms do not belong to the vegetable Idngdom at aU, but are
nearest allied to the Astasiaea, and appear to be loricated Eugleneoe, not
loricated Monads, as Ehrenberg assumed." "We shall hereafter see that this
indefatigable naturalist leans to the beUef that Eugleneae are animals ; hence
the idea he puts forwai-d respecting the Trachelomonads.

As these sheets were passing through the press, Mr. Carter's valuable
paper on Eudorina and Cryptoglena made its appearance {A. N. H. 1858, ii.
p. 237). The Crrjptocjlena described is supposed to be a new species, and is
named C. lenticularis, on account of its lenticular shape. It is compressed
and emarginate, and furnished with a pair of cilia. In tliis little being
Mr. Carter supposes an act of fecimdation to take place, the microgonidia
being supposed to represent the male, the macrogonidia the female element.
Among the numerous specimens met with, there was a number of deciduous
lorica, " some of which were split into halves which were separated, while
others only adhered together anteriorly, and presented a pair of cilia attached
to their point of union." In several instances, the internal cell, or the con-
tents enclosed in their protoplasmic sac, often distended by imbibition of water
to three or four times the dimensions of the germ lorica, wero seen cscaiino-
from the separated segments of the latter, and in their globular sliapo and

144

GENEEAL HISTORY OF THE INFUSOHIA.

general features undistinguishable from Chlamydococcus under similar fonns.
These escaping internal cells were divided into two, four, eight, and sixteen
parts ; and it was noticed that the variety which came forth with only two
gonidia was surrounded by a swarm of from ten to twenty much smaller
gonidia, which were identical in all appearance with those resulting from
division into sixty-four parts. But the cells divided into two segments were
not the only ones so surrounded by microgonidia ; for in two or three instances
a few were found around and adhering to the inner ceU of those divided into
four gonidia.

" It was also observed that the two-division did not always come forth in
one cell, but that sometimes this was also divided, so that each gonidium had
its proper cell. The form of the macrogonidia or female ceUs did not differ
from the internal cell of the parent, except ia being a little smaller, — while
the microgonidium, which was not more than l-7th of the diameter of the
macrogonidium, and therefore very small, appeared, though equally green, and
provided with an eye-spot, to have only one cUium. I cannot help thinldng,
however, that, with a higher power, I might have seen two."

The purpose fulfilled by the contact of the microgonidia with the macro-
gonidia, Mr. Carter concludes to be that of impregnation ; for he observed
one of the former, as a spermatozoid, fix itself to one of the latter (the spores
or female cells), and gradually become incorporated with it. The microgo-
nidium, after having so attached itself, assumed a conical or peg-top shape,
and thus appeared to gradually squeeze itself into the macrogonidium.

This mode of impregnation, thus directly observed by Mr. Carter, is the
copy of that the same observer witnessed in Eudorina {Pandorina), and of
that first noted by Cohn in Volvox. He, moreover, believes that it obtains
in the case of Trachelomonas, for he " has often seen the largest Trachelo-
monad of a pool divided up into a group of apparently sixteen cells within
the lorica ; and this may account for the myriads of three to four smaller
sizes that are fi'equently found together in this way. The latter certainly
appear in a green form first ; that is, without the lorica, which gradually
becomes supplied afterwards. Thus, impregnation also in the Trachelomo-
nads may take place Hke that seen in Eudorina, after the parent-ceU has
undergone division within the lorica." (See Part II., Systematic History of
Cryptomonadina. )

FAMILY III.— V0LV0CINEJ3 OR VOLVOCINA.
(Plates XIX. XX.) '

This is the most important and most interesting family of the Phytozoa.
The genera enumerated in it by Ehrenberg were G-yge^, Pandorina, Go-
nium, Syncrypta, Synura, Uroglena, Eudorina, Chlamydomonas, S2)ha;rosira,
and Volvox. The name is derived from the rolling (volvere, to turn) motion
of the genus Volvox, which is typical of the fanuly. Ehrenberg was the
first rightly to appreciate the true nature and compound structure of the
principal genera as the aggregation of numerous monadiform beings in a
common polypary-like mass. Ho correctly described the several indi^-iduals
as resembling Monads in most particulars of their organization, but was so
carried away beyond this simple natural statement by his peculiar views of
structure, as to describe them as having an unvarying body, without other
external appendages than a pair of cUia or filaments, and internally several
digestive sacs but no true alimentary canal, green ova, two roimded seminal
glands, a contractile (spermatic) vesicle, and eye-specks indicating the exist-
ence of sensation. The substance connecting the several beings, and in

OF THE PHYTOZOA.

145

which they are imbedded, he called the lorica, aud stated that propagation
occun-ed hy self-division within the envelope, and probably also by ova.

The genera Chlamydomonas and Gyges, or Ghlamyclococcus (XIX. 9-31),
offer an exception to the other members of the family in not producing
aggregate forms or colonies, at least not in their assumed typical phase.

Whilst denying in toto the elaborate animal organization presumed by
Ehrenberg, M. Dujardin nevertheless continued to recognize the Volvocina
as animal strvictiu'es, and contented himself with merely proposing a dif-
ferent distribution of the genera. However, since this distinguished French
naturahst wrote, the opinion has been powerfully advocated, and everywhere
gaining ground, that the Volvocinece belong to the vegetable kingdom ; con-
sequently their stnicture and vital phenomena receive quite a different inter-
pretation from that given by the writers above named.

The Volvocinece are now, in the language of algologists, ' Tetraspora,^ of
the family Palmellece or Palmellacece. The monadiform beings are ' primor-
dial cells,' and, in more general language, ' corpuscles,' whilst the common
pellicle or nidus connecting them is called by Cohn and others the ' envelope -
cell.' The author just named says (Entw. p. 165), that, from his observa-
tions on Ghlamyclococcus, Chlamydomonas, and Stephanosphcera, the Volvo-
cinece in general consist essentially of two parts : — 1. of a colouiiess, hyaline,
completely closed, and usually spherical envelope -cell composed of cellulose ;
and 2. of green primordial cells, single in the two first-named genera, but
eight in number in Stephanosphcera, enclosed within the envelope-cell. Li
each case these cells are simply primordial sacs, unenclosed by any special
firm cellulose membrane, and consist of a fine granular protoplasm, coloured
green or red by chlorophyll, or by a peculiar oil (XIX. 48, 49). The proto-
plasm forms only the outer layer of the cells, and is often prolonged on the
inner surface of the ' envelope-cell ' in the form of delicate mucous fibres
(XIX. 53). The primordial cells are moreover themselves elongated from
before backwards, forming a colourless apex fi'om which two vibratile fila-
ments take their rise, and passing through two foramina in the envelope-
ceU, stretch themselves outwards in the surrounding water, and by their
vibration serve to move the entire compound organism. The only difference
between Ghlamyclococcus and Stephanosphcera is one affecting the mode of
development, in which only the primordial cells (not in any way the common
envelope) take part. These cells divide fii'st into two, then into four, then
into eight or more daughter-cells (macrogonidia) (XIX. 40, 41, 42) ; but
after the third or the second, and often, indeed, after the fiLrst act of division,
a permanent generation results. Thus, in Ghlamydomonas and GJdamydo-
coccus, each of the daughter- cells becomes free and independent, encloses
itself within an envelope-cell of its own, and after developing two fibres,
breaks through, with their aid, the common envelope of the parent-cell (XIX.
23-26 and 30). In Stephanosphcsra, on the contrary, the eight primordial
cells produced by the third act of fission secrete around themselves a common
envelope (XIX. 56), which invests them like an integument, first l)-ing close
upon them, but afterwards, through the imbibition of water, raised from
them all round, assuming a globular form ; but so that the primordial cells
occupy the periphery at the equator of the globe like a ring or zone (XIX,
57, 58), having their eight pairs of filaments protruded through the openings
in the common envelope (XIX. 38). Chlamydococcus and Oklamydomonas
stand in the same relation to Stephanosphcera that Pleurococcv^ docs to Pal-
mella, Phycastrum to Desmidium, Navicula to Schizonema, Vorticella to Epi-
stylis, or as Hydra to Campanularia.

But, further, a second mode of development, viz. by microgonidia, prevails

L

146

GENERAL HISTOliy OF THE INFUSOKIA.

alilco in the three genera in question, tlio bisection of the contents of the
cell proceeding so far that they arc eventually resolved into numberless small,
mostly spindle-shaped corpuscles (XIX. 51), which at first oscillate by the
aid of two or four vibratile filaments within the common envelope-cell, but
subsequently escape singly from it, (XIX. 52), and, after enjoj'ing for a con-
siderable time very energetic infusorial movements, finally pass into a state
of rest, preparatory to some futm-e development.

" The larger un,dividcd macrogonidia, after swarming often the whole day,
are also seen to enter (as witnessed in Chlamydococcus and Stephamsphcera)
into the condition of rest, when each primordial cell contained within the
delicate envelope-ceU secretes about itself a second more compact cellulose
membrane which closely invests it, and is not perforated by the ciliary fila-
ments (XIX. 20, 21). It is, in fact, the counterpart of the membrane which,
in common plant-cells, overHes the primordial layer. In this distinctly
plant-like or protococcoid condition the cells remain without motion, and
may endure, even when dried, for a whole year, and then, on the addition of
water, undergo segmentation into two, four, or eight gonidia, which, imme-
diately after developing their filaments and envelope-cells, break thi-ough the
walls of the parent-cell and crowd the surrounding fluid."

The facts relating to the stmcture and functions of the genera above
adduced, apply in the main to all the Volvocinece ; for the differences between
the several genera, although demanding special consideration, are not essen-
tial. Thus, for example, in Gonium (XIX. 32) the figiu'e is a flattened sphe-
roid, and the green primordial cells, viewed collectively from above, resemble
a four-sided disc or plate, having each angle truncated. Moreover, the trans-
parent colourless envelope does not acquire the character and appearance of
a firm membrane, but presents itself as a mucous or gelatinous, not ceUiilose,
sheath.

Chxamydomonas. — The first of the genera included by Ehrenberg in his
family Volvocina, of which we shall attempt a description, is Chlamidomonas
or Chlamydomonas (XIX. 16). It recommends itself to oui* attention because
of its simplicity and its existence in an isolated state. This last fact seemed
to Dujardin a sufficient reason for removing it from the Volvocina to the
Thecamonadina, and for renaming it Diselmis, on account of its having two
filaments ; for he woiild admit into the former family only aggregate organ-
isms " enclosed within a common envelope, or having special envelopes
mutually adherent." On this same groimd he also advocated the ti-ansposi-
tion of Gyges from the Volvox family to that of the Thecamonadina, a genus
which we shall presently have to note imder the name of ChlamydococcKS or
Frotococcus pluviulis. To this arrangement Cohn objects {A. N. H. 1852,
X. p. 334) ; for, says he, " a more profoimd investigation, not only of the
structure, but also of the history of development, teaches us that Chlamydo-
monas (Diselmis, Duj.) possesses only external analogies with TracheJomoms,
while this form, as Ehrenberg ah-cady discovered, exhibits the closest alliance
to Gonium. and Pandorina. The relation of the colourless envelope to the
enclosed green globes, the position of the tivo cUia, which arise from the latter
and pass out through the former, and lastly, the laws of chvision of the green
cells inside the envelope, in powers of two, display themselves in exactly the
same way in Chlamydococcus as in the rest of the Volvocinecp ; and the only
distinction between "them consists in the circiunstance that in Chlamydovionas
(and Chlamydococcus) the indi^■iduals produced by the diAision of the green
globes separate after the absoi-ption of the parent envelope, and live on as
individuals, while in the other Volvocinem the daughter-cells produced by
the diA-ision of one green primordial cell remain connected by the persistent

OF TITE PHYTOZOA.

147

paxent-cell as by a common envelope, and move about as a well-defined body
composed of many cells."

The best accounts of the structure of Ghlamydomonas we have at hand are
those by Perty {op. cit. p. 85), by Braim {Bejuv., R. S. p. 214), and by
Thui-et (Sur les Zoospores, Ann. Sc. Nat. xiv. 1850). Unfortunately, each
of these writei-s describes a different species, which renders cm- attempt at a
general history the more difficult. The figure varies between ovoid and
globular ; and the ceU is not prolonged at the point from which the pair of
vibratile filaments proceed, although a colourless space exists there. The
organism consists of a green mass — the primordial ceU — suiToimded by a dia-
phanous delicate envelope, which, unlike that of ChlamyclococcuSj is closely
apphed to it, so that it leaves no clear interspace between the two. The
contents are green globules and lai'ger vesicles, with a single large chlorophyll-
utricle in the centre — the nucleus (XIX. 16) — very like in appearance to the
starch-globule so frequent in the cells of green Algae. In addition, there is
a red stigma, and in some rare instances two such ; in other examples, again,
it is altogether wanting. Motion is effected by the ciliary filaments, which
penetrate the external envelope from the enclosed globule; the envelope
resembles that of zoospores in general ; and, hke those structiu'es, these imi-
ceUular beings seek the light and exhale oxygen.

Perty describes colourless genns from which noAV specimens originate,— a
statement no doubt equivalent to saying that these beings reproduce them-
selves by microgonidia, as Cokn represents. Fission into macrogonidia is
binary or quaternary, as in Tetraspora, and gives rise to two, four, eight, and
even, at times, sixteen or thirty-two individuals. Generally whilst this act
proceeds the cells are quiescent, ceasing from their usual movements. This
process of multiplication is not influenced by the size of the Chlamydomonads,
for it occurs in specimens varying between -^-L to

Amid the film-like collections of Chlamydomonas, groups of individuals may
be encomitered in various stages of change and of breaking up : some have
entirely or partially lost their green contents ; others have acquired a yel-
lowish-brown, or, more seldom, a red colour ; others are much contracted as
small globides within the clear gelatinous cases, whilst others, lastly, acquire
a proboscis-like process, or, by pressure, an angular outline.

The variety and transition of colour just remarked depend upon the phase
of existence and the entrance on the resting or quiescent condition. The
cells of Chlamydomonas ohtusa, Braun tells us, when swarming ai'e of a dark
green colour, truncate at both ends, and, after miiltipljing for some time,
produce here and there very minute paler and more brownish-yellow micro-
gonidia. " In the course of a few weeks no more active cells could be found
in the water, the full-grown swarms having aU gradually come to rest and
sunk to the bottom. The original longish shape of the cells had changed
into a perfect sphere with the transition to rest ; the colour of these resting-
ceUs, originally green, gradually passed into a light yellowish brown ; at the
same time a number of small, sharply-defined, briUiaut globules were fomed
in the interior, ba^dng quite the appearance of drops of oil. In this altered
condition the Chlamydomonads remained, exhibiting neither growth nor
increase." It is added, in a note, that these resting (seed) coUs are about
in diameter, have a tough, colourless, and trnnsparcnt membrane, and
finally assume a flesh-red colom-. On awakening from tins ' resting '-stage
segmentation of the contents revives, with the disappearance of the red and
oil-bke elements. The resting-stago of the microgonidia has not been suffi-
ciently investigated.

Chlamydomonas Pulviscuhs, in the opinion of Cohn and most others, is

l2

148

GENERAL HISTOKY OF THE INFUSOBIA.

undistinguishable from Polijtoma Uvella in eveiy material point, — the absence
of coloui-, and its habitat in decomposing infusion alone offering tlieraselves
as distinctive of the latter. Nay, what is more, he discovers the intimate
resemblance of Chlamydomonas to the resting-stage of a Volvox which he
discovered in decomposing infusions, and named F. hyalina. From these
considerations he concludes that Chlamydomonas and Polytoma must be ranked
with Volvox in the vegetable kingdom.

But CJilamydomonas is made to appear a metamorphic condition of yet
other organisms. For instance, Itzigsohn states that, after the joints of the
filaments of Oscillaria tenuis are separated, they produce motile gonidia
"wliich present in all respects the aspect of Chlamydomonads, but which,
after passing thi-ough many intermediate forms, grow into perfect Euglence "
(J. M. 8. 1854, p. 189). Likewise Hartig, in his account of the transforma-
tions of the Phytozoa of Antheridia (J. M. S. 1855, p. 54), makes one phase to
resemble Chlamydomonas destruens of Ehrenberg. Lastly, Cohn confesses
{On Protococcus, B. S. p. 555) that the motile or swarming foi-m of Protococcus
is scarcely distinguishable from Cldamydomonas, except that the latter has
not been observed by liim in the ' stiU ' condition. But this presumed point
of divergence itself vanishes since Braun's observations have made us ac-
quainted with the quiescent phase of that organism (p. 147).

The relation of Chlamydomonas to StephanosjjJuera, and, in general, its
alliance Avith the Volvoeina as a plant, have been reviewed in the preceding
remarks on the family (p. 145).

Chlamydococcus (XIX. 20-31), another unicellular, isolated organism of
the family Volvoeina, has an-ested much attention, and been described at
large by Flotow, Braim, Cohn, Perty, and others under the additional names
of Protococcus, Hoimatococcus, and Ilysyinum. Ehrenberg has no geniLS
similarly named ; but modern researches show that Oyges is in part its
eqiiivalent, although but one phase of its existence.

Ehrenberg's account of Gyges is very meagre. He characterizes it as
wanting both filaments, eye, and tail, and as completely encased within its
lorica (an urceolus). He could discern no traces of a nutritive system, and,
except a very slight movement rendered evident by colouring the fluid,
could detect no indication of animality. On the other liand, Mr. Shuttle-
worth examined O. sanguineus, and stated it to have a lively motion (Edinb.
Phil. Journ. v. p. 29).

Li our preliminary notes on the Vohocinece in general, a vegetable nature
is assigned to the Chlamydococcus ; and its relation to other Volvocineo' is
thus laid down by Cohn (A.N.H. 1852, x. p. 335) :—

" Chlamydococcus is a imiceUular Alga in the strictest sense of the word,
never composed of more than one cell at any period of its growth, and eacli
division foi-ms the commencement of a new individual, whilst the remainder
of the Vohocinece [i.e. excepting Chlamydomonas'] present themselves as
families of cells, in which a definite number of equivalent ccUs are combined,
in some measure, into an individual of a higher order.

" The researches of Alex. Braun, lilce my own," he continues, " have
proved most distinctly that Chlamydococcus can only be placed with pro-
priety among the Alga3. It is distinguished, indeed, from the moving genn-
ceUs by which far tlie greater part of tlie species of Algaj arc propagated, both
by a somewhat more complex stracture and by the cii-cumstance that the
motion lasts for a very long time, and, finally, by tlie power of the moving
cells to propagate as such Anthout entering into tlie state of rest (germina-
tion) othei-Avise than as quite a teraporaiy condition. But these objections
touch only, to .'some extent, the ..specific character of Chlamydococcus and the

OF TUE PHYTOZOA.

149

Volvocmem generally as unicellular plants; and they do not stand there
among the Algee altogether without intermediate conditions, as Alex. Braun
has proved, especially from the long movement of the Volvocinece.

" On the other hand, the external form, like the chemical and moi-phological
organization of the contents, the laws of motion, and the general physiological
phenomena, especially however the behaviour in the transition into the con-
dition of rest, in Ghlamydococcus, agree so perfectly with the moving spores,
the transformation of which into undoubted plants has been demonstrated
with scientific clearness, that no unprejudiced observer can discover an
essential distinction. I have mentioned in my essay that Ehrenberg himself,
although he claims the moving condition of the forms allied to Ghlamydo-
coccus as Infusoria, has declared the resting-stage of this, or a most closely
aUied genus, to be an undoubted Alga ; and yet the moving Infusoria are
only a propagative form of the motionless Alga. Finally, I have succeeded
in demonstrating the membrane of the cells of OJdamydococcus, both in the
resting and particularly in the moving stage, to consist of cellulose, and thus
in estabhshiug the most important criteiion of a vegetable ceU we are at
present acquainted with — the ternary composition of the cell-membrane —
in the Infiisorioid condition of Ghlamydococcus. In fact, all the more recent
observers of Ghlamydococcus, the number of whom is not inconsiderable,
have, almost without exception, agreed in recogniziug in all conditions of the
development of this form, only a plant and nothing hut a plant."

Besides the valuable sketch referred to, of the relations of Ghlamydococcus,
Cohn has presented an elaborate memoir on this organism under the name of
Protoeoccus, ia a paper translated for the Kay Society (Botanical and Physio-
logical Memoirs, 1853), and has subsequently extended his views of it and
its affinities in his essay on the development of microscopical Algas {Entwich.
d. miJcr. Algen, 1854). Of these most important papers we shall make free
use in sketching the history of this genus.

" The moving cell of Ghlamydococcus is composed of two piincipal parts, a
hyaUne spherical envelope, which is formed of a delicate structureless mem-
brane consisting of cellulose, and immediately surrounds colourless contents,
perhaps consisting of pure water. In the centre of the envelope occui's a
coloured globule, composed of the universal nitrogenous protoplasm or mucus
of vegetable cells, coloured red or green by chlorophyll or a carmine-red oil,
and containing imbedded in it numerous granules of protoplasm, as weU as
one or more large chlorophyll- vesicles. This coloui-ed globule is attenuated
at the upper end into a coloiuiess point ; from this go out two cilia, which
protrude into the water through two orifices in the membrane of the enve-
lope, and produce the movements of the whole. The inner colom-ed globule
is not bounded by any rigid membrane, but merely by a thickened layer of
protoplasm ; hence its contoiu- is very changeable and passes through mani-
fold transformations in the course of its development. In particular it fre-
quently becomes elongated in aU directions into colourless radiating filaments,
which keep the internal colom-ed globule suspended freely in the envelope,
and are afterwards retracted in the course of the development.

" The motionless cells of Ghlamydococcus are of much simpler stinieture,
and, like all forms of Protoeoccus, consist simply of a tough spherical cellulose
membrane and green or red contents organized as primordial utricle. The
history of development shows that imder certain conditions the contents of
the motionless cells become divided into a number of portions, wliich always
correspond to two, or a power of two, in their number, that these portions
become organized into special primordial utricles, and as such break throuo-h
the parent-cell, each developing two cilia, and by the aid of these rotating

150

GENERAL HISTORY OF THE INFUSOKIA.

actively in the water. Duiiag their motion they excrete a delicate cellular
membrane over thcii- entire surface, which is gradually removed farther and
farther from the primordial utricle by endosmose of water, until at length it
becomes the wide envelope of the moving form described above. From this
it follows that the latter forms do indeed possess on the whole the character
of simple cells, but display some peculiarities in their structure and develop-
ment, since the internal coloured globide corresponds originally to the pri-
mordial utricle of other vegetable cells, yet is not surrounded by a membrane,
as usual, but suspended free in it lilce a cell- nucleus, while watery, unazotized
contents appear between the membrane and the primordial utricle. For this
reason I have called the enclosed coloui'ed globule, which is formed first, and
originally moves about without a special membrane in the manner of a cell,
and corresponds to the primordial utricle of vegetable cells in general, the
primordial cell, and the enclosing membrane with its watery contents the
envelope-cell. The moving (TZiZam^/cZococcws-condition is capable of propagating
as such, by the enclosed primordial cell dividing anew, the individual portions
slipping out of their envelope-cell and running through the cycle of develop-
ment of their parent-cells. In passing into the state of rest, the enclosed
primordial cell secretes over its surface, inside its envelope, like every pri-
mordial utricle, a new tough cellulose membrane, and through this metamor-
phosis assumes the form of an ordinary Protococcus-cell, while the envelope-
ceU is dissolved. But only such piimordial cells behave in this way as are
produced by the division of a CJilajnydococcits-gloh-ale in a lower power of
two : the primordial cells originating from a 16-64-fold division move far
more actively and do not secrete an envelope-cell ; they are incapable of any
propagation, and pass immediately into the condition of rest. Alex. Braun
has called these forms of Chlamydococcus, which develope an envelope-cell,
macrogonidia, and distinguished the smaller ones originating from multifold
division, as microgonidia."

The division of the spore- or red resting- cells of Chlamydococcus into two,
and then into four segments, each producing a new generation of resting-
cells, has of late been questioned by Cohn and Wichura ; but Mr. Currey
believes he can confii'm this occurrence, since he has " distinctiy observed
the process of self-division in some red resting-ceUs, which were probably
those of CJdarnydococcus. I say," he writes, "probably, because the red
resting-ceUs of Gldamydococcus are quite undistinguishable fi'om those of
another of the Volvocinece, viz. Stephunosplicera pluvialis, so that without
following out the development it is impossible to predicate whether such red
ceUs belong to one or the other." (J. M. S. 1858, p. 209.) A fui-ther refer-
ence to this topic wiU be found in the account of Stephanosphcera.

On reviewing his history of Chlamydococcus {Protococcus) pluvialis, Colm
attributes to this plant an ' alternation of generations,' and points out the
periodicity observed in the appearance in a collection of water of the several
phases, the one replacing the other {On Protococcus, B. S. 1853, pp. 549, 550).
Subsequently he details the number of very vaiious and changing forms of
development it passes through, " which have been either erroneously arranged
as distinct genera or at least as remaining stationary in those genera, although
in fact only transitional stages " (p. 559). " Thus," he continues, " the ' still '
Protococcus-cell (XIX. 20) corresponds to the common Protococcus coc^-otna
(Kg.) ; when the border becomes gelatinous it resembles P. pulchcr, and the
smaU ccUs P. minor. The encysted motile zoospores are the genus Gyges
granidum among the Infusoria, resembling also on the other side P. turgidtts
(Kg.), and perhaps P. versatiUs (Braim). The zoospores di\-ided into two must
be regarded as a foi-m of Oyges bipartitus, or of P. dimidiatus. In the quadri-

OF THE PHYTOZOA.

161

partite zoospores with the secondary cells arranged in one plane, we have a
Oonium. That with eight segments corresponds to Pandorina Morum, and
that with sixteen to Botryocystis Volvox. When the zoospore is divided into
tliii-ty-two segments, it is a Uvella or Stjncrypta (XIX. 27). When this
form enters the ' still ' stage, it may be regai'ded as a form analogous to
Microhaloa protogenita ; this Algal genus is probably, spealdng generally,
only the product of the Uvella-division in the Euglenm or other green forms.
The naked zoospores (XIX. 28), finally, would represent the form of a
Monad or of an Astasia (XIX. 29) ; the caudate variety approaches that of
a Bodo."

Perty has devoted several pages to recount his own observations and ex-
periments on the genus Ghlamydococcus, or, as he prefers to caU it, Hysgi-
num. He institutes two species, which he states to be equivalent to Proto-
coccus pluvialis and P. nivalis of other authors, and insists on their specific
distinctness. Probably, he adds, other varieties of Protococcm coloured red
are also referable to this genus, at least such of them as present an animal
phase of existence. To his mind, the vital phenomena of such organisms
are best explicable on the supposition of an animal natui-e ; for, says he,
cells which move altogether like Infusoria, and exhibit sensation in their
young condition, so long as they present such phenomena, are not vegetable
cells. Moreover, he thinks it established concerning the Phytozoa in general,
that in certain stages of their hfe they sometimes belong to one, and in
others to another kingdom of nature, or are so nearly allied to both that a
separation is impossible.

After the space already devoted to the structure of Chlamydomonas and
Ghlamydococcus, an abstract of Perty's long contribution on the subject can-
not be introduced ; and indeed, apart from Ms different interpretation of
their vital phenomena, little could be produced not included in Cohn's com-
plete examination. There is, however, a paragraph in Mi'. Carter's just
published valuable contribution on Eudorina, referring to Chlamydococcus,
which must not be omitted. He writes {A. N. H. 1858, ii. 244) : " CJilamy-
dococcus undergoes the same kind of changes in development as Eudorina,
from which it only differs in structure in being smaller and globular instead
of ovoid, in the absence of an external envelope, and in the cilia of the
daughter- cells being included within the parent-cell ; hence it also differs in
being motionless, though the compartments of the daughter- ceUs are sufii-
ciently large for them to turn round and move their cilia freely therein,
which they are continually doing. The primary cell of Chlamydococcus, like
that of Eudorina, divides up into two, four, eight, or sixteen ceUs, and those
of the eight- and sixteen-divisions again into groups of sixteen or thii'ty-two
each, so as to resemble the third stage of Eudorina. Hence we may perhaps
infer that its fecundating process is similar to that of Eudorina ; but this
remains to be discovered. Chlamydococcus has also a great tendency to stop
at the two- and four-division, from which it may pass into the ' still ' or
Protococcus -foim, and, floating on the water in a kind of crust, present cells
of aU kinds of sizes undergoing ' still ' division. In all its multiplications
partial and entire, however, it generally maintains its primaiy or spherical

form, and does not become ovoid or oblong like the groups of Eudorina the

only exceptions being in the two- and foui'-division, where the green cells
are sometimes ovate (probably from want of room in the parent capsule) as
represented by Ehrenberg in C. Palvisculus, to which I should refer it had
he not also given an ovate form to the type-cell of this species : nor can I
refer it to C. pluvialis ; for in all the changes I have yet seen it undero-o' the
red colour has not increased beyond the minute oye-spot, while this also'dis-

162

GENEEAL HISTOllY OF TUE INi'CSOlilA.

appeal's, and the cilia too, wlien this species passes into the ' still ' form.
Here it tmdergoes the same kind of division that it does in the active state ;
but the parent-cell, instead of becoming distended by imbibition, remains
closely attached to the daughter-ceUs, so as to give the group a mulbeny
shape. How long it remains in the ' still ' foi-m I am ignorant ; but
having only seen it in the active state dmiug the months of May, June, and
AugTist, and throughout the rest of the year in the ' still ' one, I am in-
clined to think that it only comes into the active state during the summer
months, and then for the purpose of fecundation.

In several instances, also, where I have found this ChlamydocoKus with
Eudorina, they have been accompanied by long Closteriform cells. It was
the case in that above mentioned, where the latter was undergoing impreg-
nation. Some of these have an eye-spot, which, with the nature, arrange-
ment, and general aspect of their internal contents, shows that they belong
to the class of organisms with which they are associated. Their cell- wall
also is more or less plastic, or was so when they were assuming this spiculai*
form ; for many have one or more diverticida extending from them, some are
bifid, and a few irregularly stellate. What they are, I know not ; but Dr.
Cohn has figured the same kind of cells, in company with Sphceroplea annu-
lina, under impregnation."

Mr. Currey (op. cit. p. 216) has noticed and figured what he conceives to be
a generative variety of OJdamydococcus (XX. 24). " This," he says, " I take
to be a state of Clilamydococciis. The outer membrane was colourless, and
the two internal globular cells of a clear, bright ruby crimson. The pecu-
liarity of the plant consisted in the fact of the cell being filled with minute
staff-Eke subcylindiical bodies in active motion, precisely similar to the
spermatozoa of Vaucheria. I watched these bodies at intervals for about
twenty-four hours ; and the motion was incessant. A1; the end of that time
the cell slipped amongst some other Algae on the same sHde and was lost.
Whether these little active organisms were really spermatozoa, or whether
they belonged to the mysterious bodies which, in some way or another, are
supposed to find their way from without into the cells of Algaj, it is im-
possible to say."

The next figui-e (XX. 25) is also copied from Mr. Currey, and, as he re-
marks, evidently "represents the final stage of some Volvocinecem wliich the
gonidia have become encysted." We aUude to it here, although it does not
belong to Ghlamydococcus. Mr. Ciu-rey obsei-ves fiu'ther, " I notice it be-
cause the encysted cells were of a pale yeUowish-brown colovu', and covered
with minute pits or depressions, and were altogether different from those of
any other Alga mth which I am acquainted. In Pandoritia and Stephano-
sphcera the resting-spores are red, in Volvox bright orange ; and in neither
case are there any such marldngs as those in the membrane of the cells
shown in the figure referred to."

GoNiTTM (XIX. 32-37). — Tliis genus received considerable attention from
Mullcr and Ehrenberg. The latter described it as composed of sixteen
Monads, resembling Chlamydomonas in all points except in the absence of
an eye-speck, collected together in a quadrangular tablet, vrith from three to
six intercommunicating tubes or cords. Each Monad was said to be enclosed
in a hyaline lorica, called here a mantle (lacemn), wliich it could at times
quit ; also to have two filaments (proboscides) extended from the mouth, re-
presented by a clear spot at their base ; several clear stomach-sacs, a con-
tractile vesicle, two round sexual glands, and numerous green ova. Detached
individuals, he added, swam like Monads, in ~ the direction of the longitu-
dinal axis of their bodies, with the mouth in advance ; but when in tablet-

OF XUE PHTTOZOA.

153

like colonies sometimes moved horizontally, at others verticallj', or rolled on
their- edges like wheels by the aid of the pair- of vibratile filaments of each
member projecting fi-om the surface.

The animal organization here represented is now-a-days generally ignored,
and Gonium takes up its position among plants. Prof. Cohn (to whom we
ai-e so much indebted for oui- knowledge both of Protozoa and Protophyta)
has contributed a valuable paper (Entiu. d. miJcr. Algen u. Pilze) on this in-
teresting being, of which we shall present an abstract.

The entii-e organism is invested by a colourless transparent muco-gela-
tinous envelope without any cellulose limit-membrane, whence it is that this
common envelope has frequently passed unobserved unless some colouring
matter, such as Indian ink, has been added to the water.

The fig-ure varies according as the plant is viewed fi'om above (on its
polar aspect) or fi-om its side (on its equatorial aspect), being in the former
point of view a quadrilateral tablet with truncated angles and rounded cor-
ners (XTS. 32), and in the latter a flattened spheroid.

The simple or primordial cells (XIX. 33) enclosed in this mucous sheath
are sixteen in number, disposed in a uniform manner, so that four cells,
leaving a square intei-val in the centre, are bounded externally by twelve
others, three of which form one of the four sides of the organism (XIX. 32).
The central cell of the three is, moreover, not in a line with the other two
on the same side, but set nearer to the centre ; hence each side of the tablet
is hollowed out ia the middle. Closer reseai'ch also shows that each of the
cells is not spherical, but polygonal, the four internal being six-sided (hex-
agonal), the twelve peripheral five-sided (pentagonal) ; the consequence is,
angular intercellular spaces are left, the central of all being quadi'angular,
and all the rest triang-ulax. This arrangement of the piimordial cells is
normally so regular, that Cohn represents it by a geometrical diagram ; stUl,
in aU tablets of Gonium this is not the case, and jjarticularly in veiy young
specimens.

The regular polygonal contour of the cells indicates that they are not
mere masses of soft variable protoplasm, like those of Stephanosphcera, but,
on the contrary, are each of them surrounded by a colourless, hyaline, deli-
cate but firm membrane, imposing on them their fixed form (XIX. 34).
This structure indeed is not generally discernible, unless by some abnormal
conditions, or by the occurrence of self-division (XIX. 35), in which, as
only the green contents are concerned, it comes to stand apart fi'om the latter
as a distinct, separable sac. It can, moreover, be demonstrated by crashing
the cells, when the chlorophyll escapes through the rent, and leaves the
colourless and fi-actm-ed case. Cohn is convinced that this membrane is
composed of cellulose, although, from the inability to isolate them, he has
been unable to prove it by chemical reagents.

"Without any preparation this investing membrane can, fiu-ther, bo detected
at the angles of the cells, from each of which it is prolonged in tlic form of a
short tubular process, empty and colourless, the contents being restricted to
the general cavity of the cell (XIX. 34). Each cell sends out such a pro-
cess from its several angles to luiite with a similar one from each contiguous
cell : in this way are formed tho intercurrent cords or canals iiUuded to by
Ehrenberg. It follows also from this structure that the link connectino- the
angles of conjoined ceUs, belongs one half to one and the other to its com-
panion-cell.

The nature of the G'omnm-cells and their connecting tubes is clearly dis-
played by observing the changes consequent on the gradual evaporation of
the water about them. For instance, on adding salt by degrees, a portion of

154

GENEEAL HISTORY OF THE INFUSOHIA.

the water included in the cells is withdrawn, whereupon their contents con-
tract themselves into a globular form, revealing the investing membrane in
its entii-e perii^hery. Again, when the mucous envelope breaks up by difflu-
ence, the ceUs show a tendency to separate : the link-like canals are first
drawn out, and subsequently give way at the point of junction of the two
processes which form them — and this with such a degree of elasticity, that
the cells appear to bui-st fi'om one another with a spring ; and thus at length
the entire organism is resolved into an irregular collection of cells.

In the immature period (XIX. 33-36) the outline of the ceU-membrane is
spherical ; for the angular figure and the development of the junction-pro-
cesses are subsequent phenomena. Further, the extension of the processes
at times goes on so far that the Gonium-ceHs at fii-st sight appear detached
from each other and free, which is never the case natui'aUy.

In other points of organization the ceUs of Goniwm correspond with other
loricated swarm-ceUs, pai-ticularly with those of Ohlamydoinonas. Theu- con-
tents consist of protoplasm coloured by chlorophyll, among which, in older
specimens, are numerous corpuscles (the ova of Ehrenberg) that impart a
deeper coloiu-ing ; of a central circumscribed darker corpuscle, which, as par-
ticipating in every act of fission of the cell, must be esteemed a nucleus ; of
several vacuoles, often numerous but occasionally wanting, and of two or
three sharply-defined vesicular spaces, constant in position at the base of the
filaments (XIX. 33). The last-named are the locomotive organs of the
organism, are two in number, and proceed from the protoplasm, passing
through foramina in the special ceU-waU, and afterwards through the com-
mon mucilaginous envelope, so as to appear, in the polar aspect, like out-
stretched fibres from the tabular organism.

The movements of Oonium resemble in all respects those of Stepliamsjylicera
and Chlamyclococcus and other swarm-ceUs. The plant revolves on its short
axis, so that in its polar aspect it appears lUce a rotating surface, whilst in its
equatorial it has on the contrary a linear outline.

In the course of its development by self- division, neither the general mu-
cHaginous coat nor the cell-membrane is concerned, but only the contents.
The fission into 16 segments to form a new colony has not that simultaneous
character which Ehrenberg implies, but takes place by four stages or genera-
tions, in every one of which a bisection of each ceU afready developed ensues
(XIX. 35). It is only in fully developed (?o»^^^tw^-tablets that self-division
is effected — for example, in such as have cells y^y-'" in diameter, and sepa-
rated from one another by the elongated intercommunicating processes, and
where those cells have the disposition described as characteristic.

On the completion of the act of self-division by the constniction of 16
small cells, these are found occupying just the same relative position within
the membrane of their parent-cell as do the members of a perfect Gonium
(XIX. 36). Amid numerous examples of the plant, specimens may be met
with abnormal in the number of constituent ccUs ; for instance, colonies of
only 8 cells occui", which are explicable on the supposition that the last
stage of fission, i. e. the last act of generation, has been arrested, and only
three such acts completed. The lUce irregulai'ities ai'e often noticed in other
Volvocinece.

The primordial cells of the newly generated colonics appear unconnected
with each other, whilst the mother-cell wall, which still includes them, is
considerably distended and elongated in one direction (XIX. 30). The move-
ment of the colony as a whole continues xintil the last stage of fission is com-
pleted, whereupon it ceases, and the newly formed groups commence a move-
ment within their enclosing cell, sometimes presenting themselves in one

OF THE PHYTOZOA.

155

plane as a disc formed by a collection of green globules, at others, on their
edge, looking little more than a green line.

At length the mother-cell ruptures, and, the mucous envelope having dis-
appeared at a previous stage (XIX. 37), the young colony escapes into the
suiTOunding water, moves freely about, and commences an independent ex-
istence. These young forms have usually a diameter of ^m'".^ Supposing,
which is very probable, that a yoimg Gonium after 24 hour's is capable of
development by fission, it foUows that under favourable conditions a single
colony may on the second day develope 16, on the third 256, on the foui'th
4096, and at the end of a week 268,435,456 other organisms like itseK.
This calculation sufficiently explains the extremely rapid multiphcation of
these organisms, colouring a collection of water, floating on its surface as a
scum, or settled in bad weather as a filmy stratum at the bottom.

The cells which break away from the group, and so leave vacuities in its
conformation, resemble in their isolated condition the eeUs of CJilamydomonas.
Such detached cells were deemed by Ehrenberg equally capable of fission as
the persistent members of a colony ; Cohn, however, has never observed the
phenomenon, and believes, on the other hand, that, after swarming for a time,
they enter into a state of rest, and by shedding their locomotive filaments
assume the Protococcoid state. This ' still ' form of the Ooniutn-ceQs is in all
likehhood also entered upon when the water in which they live is dried up
and the functions of life suspended ; and it may be that on the addition of
fresh water such cells give issue to motile forms, and thus a parallel series of
changes occur in this organism to that observed in Stephanosphcera. Never-
theless a resting-stage of Gonium is not positively demonstrated ; for although
analogy is in favour of it, and the occurrence of Protococcoid cells in com-
pany with the ordinary tabular groups suggests the probability that these
are ' still ' cells, yet the absence of characters to distinguish them from the
swarm-spores of other Algae renders their determination at best a matter of
doubt.

Development by fission as described is, therefore, the only mode proved to
exist ; it resembles that in Ghlamydococcus and Stephansophcm-a, by which
macrogonidia are formed. The production of microgonidia, as seen in both
the genera just named, as well as in Eudorina (Pandorina) and Volvox, is as
yet unlmown in Gonium.

Respecting its relation to other Volvocinece, it is to be observed that,
although there are striking diSferences, there are, on the other hand, decided
natural affinities betwixt them and Gonium. Thus, although the envelope-
cell is so imperfectly developed that it cannot be represented as a special
shut sac, as in the case of StephanosjjJuera, Ghlamydococcus, &c., yet it is
analogous to the envelope-eeU of those genera in its relation to the ceU-con-
tents ; and, besides, in the case of the intimately allied Eudorina eleqans, the
common envelope, which resembles that of Steplianosphmra, is foimd fii-st as
a simple, and later as a double fine ceU-membrane. (In Pandorina, indeed
Professor Henfrey asserts the mucous envelope to be devoid of a limitin"-
membrane.) *

Again, the primordial cells of Gonium are enclosed in a special membrane
and not mere globules of protoplasm unprotected save by a pellicular layer of
the same substance ; thus tho disposition in Gonium (the primordial cells
enclosed by a membrane, the envelope-ceU not invested) is just the reverse of
that in Ghlamydococcus, GIdamydomonas, and Sfephanosphafm. However the
existence of a membrane aroimd the primordial cells is not an anomalous' cir
cumstancc among the Volvocinece, since, in certain stages of development a
firm closely appUed membrane is produced around tho ceUs of the other

156

GENERAL HISTORY OF THE INFUtjORIA.

genera — as, for example, around the microgonidia of Chlamydococcus when
they enter on theii- resting-stage, and about the cells of Siephanosphm-a
when preparing to leave the common envelope. But, further, in these in-
stances, when this special closely applied membrane appears, the envelope-cell
breaks up into a mucUagiaous layer, and then presents the normal condition
of that of Gonium. In other structural matters, in the number of vibratile
fQaments, and in the history of development, Gonium entii'ely accords with
the other genera.

After this review of the afiinity of Gonium with the other Volvodnece, it
follows that, like them, it must be of a vegetable nature, although cellulose
has not been detected ki it. Still more, the evident relation of Gonium with
Pediastrum (II. 44), the plant-natui-e of which no one at the present day wiU
gainsay, points to the same natural position. It agrees with that plant in
general stnictiu'e, iu the union of several cells in one plane, in the number of
those ceUs and in their self-fission in the power of two, m the development
of new tablets and in obedience to the same laws. The only difference
between these two genera is, that in Pediastrum the swarming of the cells,
although siuTOunded by a common envelope-cell, ceases when they are asso-
ciated together in a tabular form, — whilst in Gonium the reverse is seen, the
power of motion becoming manifest when the several cells are ru combiuation.
To state this generally : in Pediastrum the indi\ddual cells swarm, and the
colony is qtiiescent ; in Gonium the colony swarms, and the quiescent state
of the several cells follows upon theii' separation.

However, there are organs in Gonium which, did they admit of proof as
essentially animal structures, would be fatal to aU these arguments for its
vegetable nature. These are the two, or more rarely three, permanent
vacuoles visible neai- the origin of the vibratile filaments, which are seen to
contract and expand alternately within a brief interval. These contractile
vesicles have a sharp outline, are colourless, and look lilce clear rings in the
midst of the green cells. To detect them and their movements, the most
translucent and large cells must be chosen ; they must also be perfectly stiU,
and lie flat upon the glass sUde, — an object attainable by a partial evaporation
of the drop of water.

The two vacuoles (XIX. 33) are but Httle apart, equally clear and large,
and apparently unconnected. Their action is alternate, each vacuole iinder-
going a systole and diastole iu succession, whilst the time occupied by the
systole, by the diastole, and by the interval is equal. The same equality
in time obtaius also between the two vacuoles of the same cell. Likewise a
uniformity prevails among the different cells of the same Gonium, but not
among the ecUs of different Specimens ; and Cohn holds the occm-rence of
rhythmical contractions of these vacuoles as a well-established fact.

These, therefore, are pulsating spaces, filling up with water, and after a
time expoUing it, and agree in idl points with the so-called ' seminal ve,sicle '
of Ehrenberg (the contractile sac or vesicle of other authors) met -with in
ciliated Infusoria. Cohn next proceeds to discuss the question if these pul-
sating sacs are to bo considered exclusively animal organs, and arrives at the
conclusion that they cannot be so considered, and cannot be appealed to in
the decision of the question of the animal or vegetable natui-e of any doubtfid
orgiinism.

To conclude tliis complete history of Gonium, as abstracted from Cohn's
elaborate essay, we must add that the description applies only to Gonium
pectorale (Ehr.), which, in the author's opinion, is the only species referable
to the Volvocinetv, the remainder enumerated by Ehrenberg being members
of the genus Merismospcdia of the PalmeUacea:.

OF THE PHYTOZOA.

157

Panborina (XIX. 59-69 ; XX. 22, 23).— This genus has recently been
veiy carefully and thoroughly examined by Prof. Henfrey (J. M. S. 1856,
p. 49) in an able memoii-, of wliich wo shall make free use to supply our
readers with a satisfactoiy description of this interesting and beautiful or-
ganism. The specimens examined were of the species Pandorina Morum,
of which, as Prof. Henfrey justly remarks, the description " given by Ehren-
berg is so incorrect, that no one would be able to determine the organism by
its aid ; but the figures in the Infusionsthierchen, although rude, are sufficient
for identification." Dujardin contributed nothing to our Imowledge of this
genus, which he treated as one with Eudorina, objecting, very justly, to the
worthlessness of the red speck as a distinctive generic character between them.

Prof. Henfrey's account is so succinct that it admits of no abridgement, we
are therefore induced to present it entii'e. " The forms," he writes (p. 50,
op. cit), "presented by this organism are exceedingly varied; and nothing
can be more beautiful than a number of them revolving slowly on their long
axes in a drop of water, as seen under a power of about 100 diameters. In
the fii'st place, the perfect form exhibits two patterns (shown in XIX. figs.
59 and 60) ; and there are minute counterparts to these, remaining in that
state, while, in the water where the species is actively multiplying, all si^es
between fig. 64, just emerged from the parent frond, and the full-grown form,
figs. 59 and 60, &c., occm-. The form with 32 gonidia residts from the ceU-
division going on one stage further than in the form with 1 6 ; but this dif-
ference is fixed during the earhest stages of development, as the form with
16 never changes into that with 32 after it has become free from the parent.
In the perfect forms the gonidia are arranged near the peripheiy of the frond,
in circles, lilte the equator and parallels of latitiide on a globe, — so that Pan-
dorina resembles Cohn's Stephanospluera more closely than any of the other
Volvodnece, that having a single equatorial ring of gonidia in its globular
frond. Among the forms with the isolated gonidia occiu' others almost equally
numerous with the gonidia collected together into berry-like heaps (figs. 65-
68) : these are smaller than the others, but equally varied in dimensions ;
their gonidia resemble those of the other fonn ; they appear destined to
form the resting-spores.

" The gonidia are almost globular ; they have no proper membrane, but
con.sist of a gelatinous gTanular substance which contains a thinner fluid in
the centre, as it contracts strongly by exosmosis when strong saline solutions
are appHed. There is a large nucleus-like body (the chlorophyU-vesicle of
A. Braun) at the posterior end of the gonidium (fig. 61) ; and at the opposite
side is a short beak-like process, with a coloiirless space behind it : the pair
of cilia arise here ; and a little to one side and below these is the reddish-
brown granule called the ' eye-spot.' We have never been able to observe a
pulsating vacuole, as described by Busk and Cohn in Volvox and Oonium.

"The gelatinous frond appears to be perfectly homogeneous, without "any
boundary membrane. Iodine and sulphui-ic acid do not coloiu- it blue. It is
tolerably resistent, and appears solid, as it does not give way or become
indented by external pressure, as is the case with the hoilow frond of Volvo.v

"The fronds are multiplied by the conversion of the gonidia into new
families. If they are viewed at night, many of the fronds may be found at
rest at the bottom of the vessel (in tlie daytime they assemble at the side
next tiic light), motionless, and with the gonidia rounded and deprived of
their nucleus. By covering up the bottie from the light, the development of
the new fronds, which naturaUy takes place very eariy in the morning mnv
be retarded, so as to be followed during the morning until noon Some of f ho
fronds may be found witii tlio gonidia converted into berrv-like heaps (fi<r 62)

158

GENEEAL HISTOEY OF THE INFUSOEU.

otliers with the gonidia already distinct (fig. 63), while many parent fronds
present the young fronds more or less regularly an-anged in the softened
and expanded parent mass, which ultimately dissolves and sets them free
(figs. 04, 65). They then increase in size in proportion to the favourable
conditions in which they are placed. I have never seen anything like what
are described by Cohn in Stephanosplmra as ' microgonidia.' In a letter re-
ceived from Professor A. Braun siace the above was written, he speaks of the
forms with small gonidia (fig. 64) as the ' microgonidial ' form.

"When kept for some weeks, an iacreasing quantity of fronds became
accumulated at the bottom of the water, and these chiefly of the character
shown in fig. 66, but devoid of cUia ; and while many of them decayed, in
others the gonidia became encysted so as to form globular cellules. Left for
a fortnight, the water was foimd without a trace of green colour, with merely
a brownish sediment at the bottom, upon examining which, it was found to
contain a large number of berry-like forms with the gonidia not only en-
cysted, but with their contents converted into a red, oUy, granular substance
(figs. 67, 68), as in the resting- spores of many Confervoids. The gelatinous
frond was here almost dissolved away ; and a slight pressure was sufficient to
detach and separate the cellules, which are doubtless resting-spores (fig. 69)
and destined to become subsequently developed into new fronds. This remains
to be decided.

" The organism thus described is a well-marked and distinct species, very
different from Volvox and Gonium, but approaching near to Steplmiwsplicera.
The form which produces the resting-spores, after losing its cUia, is Kiitzing's
Botryocystis Morum. I have met with a form Kke this not imfrequently, but
never before with the perfect Pandorina. Mr. Pollock teUs me that he has
collected from the same pond for some years past, but never found Pandorina
before, and yet it colours the water green this season. Volvox seems, m hke
manner, to come and go at intervals of years, its revivification from the rest-
ing-spores depending much on external conditions."

Mr. Currey's valuable contribution to our Imowledge of the British freshwater
Algce {J. M. 8. 1858, p. 213) furnishes the following memoranda on Pan-
dorina. He writes — " In speaking of the reproduction of Pandorina, Mr.
Henfrey mentions two processes : 1. the conversion of each gonidium into a
new frond within the parent mass ; and 2. the conversion of the gonidia into
encysted resting-spores, wliich are set free, and subsequently geiTuinate to
produce new fronds. Upon this I may remark, that the process of becoming
encysted does not invariably take place ivithin the parent frond, for I have
seen the gonidia of Pandorina escape from the parent frond in the form of
membraneless active zoospores ; and although I was not fortimate enough to
trace the subsequent fate of these zoospores, the probability is that, hlce those
of Ohlamydococcus and Ooniitm, they woixld become encysted at a subsequent
period, as', without undergoing this process, it is difRcvdt to sec how they could
produce new fronds. This mode of escape of the zoospores seems to throw
some doubt upon the suggestion of Mr. Henfrey with regard to the nature of
the frond of Pandorina, which he considers to be solid, inasmuch as it docs not
give way or become indented by prcssui-e, as is the case with tlie hollow frond
of Volvox. If, however, the frond were solid, the zoospores could not well
escape, except by its gradual dissolution ; but, in the instance I liave men-
tioned, the escape certainly took place by a rupture (as may often be seen
with Volvox), and not by a gradual process of dissolution. In a paper on
some Volvoeineo} by Dr. Frcsenius, in the second volume of the Transactions
of the Scnckenberg Natm-al History Societj^, he speaks of the easy escape of
the colls of Ooniiim pectoralc aa being evidence against the existence in that

OF THE PHTTOZOA.

159

Alga of any fii-m covering, and he draws a distinction in this respect between
Oonium and Pandorina. My observation, however, leads me to think that
Pandorina, as far as relates to its coat, does not substantially differ fi'om
Volvox- and Gonium. Besides the natm-e of its coat, there are some other
points of stmctm-e in Pandorina requiring further examination and elucida-
tion. Ehrenberg stated that the gonidia of Pandorina have one cilium, and
no eye-spot, a view adopted by Fresenius in the paper I have alluded to.
Pocke and Dr. Braim considered Ehrenberg's observations inaccurate, and
Mr. Henfrey agrees with them. As far as my observations go, I should say
that the gonidia have usually two cilia, but that they frequently have no eye-
spot. Mr. Henfrey has never been able to observe a pulsating vacuole, nor
was any such vacuole visible ia my specimens. Dr. Eresenius, on the other
hand, has observed one, sometimes two, such vacuoles ; and he remarks that
cilia and red spots are subject to considerable variation, and suggests that
Stephanosphcera and Volvox are probably the only distract forms to be met
with ia the Volvocinece. I should protest against including Gonium pectorale ia
the same genus as Step>hanosph(Bra ; but, Avith this exception, Dr. Eresenius' s
suggestion is probably correct. If, however, StephanospJicera and Pandorina
are only forms of the same plant, the generic name * StephanospJicera ' must
give place to ' Pandorina,^ the latter being of much earlier date."

According to Braun (Rejuv., R. S. p. 21, note), the colonies of Pandorina
revolve always to the right ; but Prof. Henfrey corrects this statement, assert-
ing that they change the direction constantly. Another circumstance re-
marked by Braim is, that both the birth of the first generation of gonidia,
and the production of the succeeding generations by the division of the earlier,
occur in the morning after nocturnal preparation (p. 224), — a circumstance,
indeed, which prevails in aU. the Volvocinece. We must also note that among
the many phases of development of Cldamydococcus pluvialis, Cohn discovers
two comparable in form to Pandorina Morum and to the Botryocystis Volvox
of Kiitzing (op. cit. R, S. p. 559).

The late valuable contribution of Mr. Carter on Eudorina (Pandorina)
(A. N. H. 1858, ii. p. 237) claims oiu- especial attention as confirmatoiy of
Cohn's discovery of the sexuality of Volvox, a parallel fact to that he had pre-
viously made out in the case of certain indubitable AlgaB. Mr. Carter identi-
fies the organism he has studied with the Eudorina elegans, Ehr., a species
which naturalists at the present day refuse to consider actually distinct from
Pandorina morum, inasmuch as the solitary character upon which the sepa-
ration was made by Ehi-enberg, viz. the presence of a red speck in Eudorina,
is well known to have no pretensions to a specific, and stiU less therefore to
a generic character. Indeed, Mr. Carter himself treats the ' ej-e-spot,' if not
as a mere accidental feature, yet as only an adjunct of a particular phase of
plant-life ; for in the very paper under notice he puts forward tho query,
" Docs not the disappearance of the eye-spot in the ' still ' form thus seem to
point out its analogy \vith the bright colours, especially tho red, presented by
plants in their flowers during the season of fecundation, rather than with tho
eye of animals ? "

We may consequently regard this excellent paper by Mr. Carter as an im-
portant supplement to Prof. Henfrcy's admirable and lucid memoir on Pan-
dorina, especially its developmental liistory. At the risk of some repetition, wo
shall allow the author to explain his researches and opinions in his oAvn words
and the more so as his plan of proceeding and manner of description do not
taUy very precisely with those observed in the preccdijig account of Pandorina

" Before gomg," Mr. Carter writes, " to tho fecundation, it is desirable that
we should trace the development oi Eudorina up to this point ; but not ha^nno-

160

GENEEAL HISTOEY OF THE INFUSOEIA.

been able to recognize this organism in its simplest form (that is, as a sohtary
single cell), nor any stage of its segmentation prior to the third degree of du-
plicative subdivision (that is, into 16 cells, when the mother-coverings have
dropped off), I must begin from this period.

" At this time, which we will caU the first stage, the Eudorina consists of an
ovoid green body, partially divided into the number of ceUs just mentioned,
each of which is provided with a pair of cilia which project thi-ough a thin
gelatinous envelope that surrounds the whole mass. It is now in its smallest
size, about 5-5400ths of an inch long, that is, not more than the diameter of
the Chlamydococcus-cell, and swims by means of its cilia, with the small end
foremost, and with a rotatory motion on its longitudinal axis, as often from
right to left as from left to right. An eye-spot is also present in each of the
four anterior cells, but seldom visible in the rest at this period.

" As the development progresses and the Eudorina increases in size, the di-
vision becomes complete, and each cell, in addition to the granular mucus and
chlorophyll which line its iuterior, may now be seen to be provided internally
with a spherical translucent utricle (which is the nucleus), an eye-spot situ-
ated peripherically and midway between the cilia and the opposite end of the
cell, a contracting vesicle at the base of the cilia, and the pair of cilia them-
selves. Each pair of cilia passes out thi-ough a single channel in the gelati-
nous cell or envelope, which has now become much thickened — and thus their
movements are limited up to this point, — while a defined line intemally marks
the boundary of the original ceU-waU, tkrough which, of course, the ciHa also
pass.

" During the second stage, each of the ceUs again imdergoes duplicative
division (the nuclei having been doubled previously) ; and the whole organism
becoming larger, they are separated from each other, and being no longer sub-
ject to the compression which, with the lines of fissiparation tending towards
the centre of the ellipse, and their confined position, induced a more or less
conical and polygonal shape, now become spherical and enclosed respectively
within distinct transparent capsules. The Eudorina is now 30-5400ths of an
inch long, and contains thii-ty-two green cells, which are evidently situated
between two large, ovoid, colourless, transparent cells, one of wliich bounds a
similarly-shaped cavity in the centre of the Eudorina, and the other is the
original cell- wall, round which again is the newly secreted envelope, — ^while
the green cells are further fixed in their respective positions by the passage of
their cilia thi'ough the two latter, both original ceU-wall and envelope. Thus
we see that the Eudorina is derived from a simple (daughter-) cell, and that
its green cells have resulted from a duplicative subdivision of the green matter
which lined the cavity of this ceU. Arrived at this state, which we shall pre-
sently see is that of matuiity, we also observe that tlie posterior part of the
envelope becomes crenulated, apparently from flaccidity.

" After this, however, it again presents another phase, which maybe called
the third or last stage of development. Here each cell again imdergoes a rapid
duplicative subdivision into sixteen or thirty-two ceUs, which, in the group,
assume a more or less oblong figiu'e respectively ; and thus the Etidorina'B
length is increased to 50-5400ths of an inch. The intcnial stinicture now
gradually breaks down before the external envelope, when for a short time
the groups may be seen swimming about the cavity thus formed, till at last
the envelope bui-sts and they become liberated. What becomes of them after-
wards, I cannot state from observation ; but the^green cells having been greatly
reduced in size by the latter subdivisions, it is probable that many of the
groups, if they do not foi-m new individuals, sooner or later become disinte-
grated, and the Evdorina thus eventually perishes.

OF THE PHTTOZOA.

IGl

" When, however, the process of impregnation takes place, the division stops
at the second stage,— that is, when the Eudorina consists of thii-ty-two cells of
the largest land, each of which is about l-1866th of an inch in diameter
within its capsule, which is therefore a little larger. The process is as foUows : —

" At a certain period after the second stage has become fuUy developed, tho
contents of the foiu- anterior cells respectively present lines of duplicative sub-
division which radiate fi-om a point in the posterior part of the cell (and this
distinguishes this subdinsion fi-om that which took place in the original cell
from which the Eudorina was derived, and that which takes place in the thii'd
or last stage of development just described, where the lines of fissiparation
tend towards the centre of the ellipse or ovoid cell). These lines, which ulti-
mately divide the green contents of the cell into sixty-four portions, where
the division stops, necessarily entail (from their radiating fi'om a point and
tei-minating a Uttle beyond the centre of the cell) a pyriform shape on the
segments, from whose extremities a mass of cilia may be observed waving in
the anterior part of the ceU of the parent, while yet her own pair of cUia are
in active motion, and her eye-spot still exists m situ on one side of her pro-
geny,— thus sho^ving that the latter may be almost fully formed before the
parent perishes. At length, however, this takes place, and the progeny, which
we shall henceforth call ' spermatozoids,' separate from each other, and finding
an exit, probably by rupture, through the eflFete parent-cell and her capsule,
soon become dispersed throughout the space between the two large ovoid cells
mentioned, where they thus freely come into contact with the capsules of the
twenty-eight remaining or female ceUs.

" The form of the spermatozoid now varies at every instant, from the activity
of its movements and the almost semifluid state of its plasma ; and therefore,
if we had not seen it in the parent-cell, it would be very difficult to define
what this form really is. Its changes in shape, however, are confined to
elongation and contraction, like those of Euglena viridis, and not polymorphic
like those of Amoeba ; hence it is sometimes linear-fusiform or lunular, at
others pyriform, short, or elongate. The centre of the body is tinged green
by the presence of a little chlorophyll, while the extremities are colourless ;
the anterior one bears a pair of cilia, and there is an eye-spot a little in front
of the middle of the body, also probably a nucleus. Thus we have a product
widely diSerent from the common cell of Eudorina.- It is about l-2700th of
an inch long, and 1 -10,800th of an inch broad.

" Once in the space mentioned, the spermatozoids soon flmd theu- way among
the female cells, to the capsules of which they apply themselves most vigor-
ously and pertiaaciously, flattening, elongating, and changing themselves into
various forms as they gUde over their surfaces, untH they find a point of in-
gress, when they appear to slip in, and, coming in contact with the female
cell, to sink into her substance as by amalgamation. I say ' appear,' because,
the female cells as well as the spenuatozoids being so small, so numerous, and
so nearly grouped together, and there being no point Hke a micropyle that I
could discover, and the Eudorina continually undergoing moro or loss rotation,
I do not feel so certain of having seen the act of union take place as if there
had been only a female cell present with a fixed point for the entrance of tho
spermatozoids, as in the resting-sporo of (Edogoninm. But the act itself does
not require to be seen ; for tho constancy of this form of Eudorina, the way
in which these little bodies are produced, their plastic nature, and their be-
havioiu' towards the female cells are quite sufficient to convince those who
have given their attention practically to such subjects that they are spenuato-
zoids, and that there can be no other object in their congregatiuo- about tho
female cells than unpregnation. If this be not sufficient, their number may

St

162

GENEEAL HISTOEY OP THE INFUSOBIA,

frequently be seen to diminish as they pass backward among the female celk,
Avhen their disappearance can only be accounted for by their having become
incorporated with the green cells. Eudorina in this stage also may frequently
be seen with all the four anterior cells absent, and only a few spermatozoids
left, most of which are motionless and adherent to the capsules, — radicating
that the rest have disappeared in the way mentioned. Lastly, many Eudorince
in this stage may be observed with not only the four anterior ceEs absent, but
with hardly a single spermatozoid left, — indicating that the whole had passed
into the female cells, or had become expended in the process of impregnation.
I have never seen any spermatozoids in the central or axial cavity, nor do 1
think that there is a means of their escaping externally without rupture ; so
that their being confined to the space between the two ovoid eeUs of the Eu-
dorina, where the green cells are situated, is another reason, if any more be
needed, for considering them fecundating agents,

" What changes take place in the Eudorina after this, I have not been able
to discover. At the time, the female cells appear to become more opake by
the incorporation of the spermatozoids ; and the crennlated state of the poste-
rior part of the envelope in this stage seems also to indicate an approach to
disintegration. I have also observed that those EudorincB which are under-
going, or apparently have undergone impregnation, are less active than the
rest, — that is, those in which the spermatozoids are scattered throughout the
interspace mentioned and applying themselves to the capsules of the green
cells, and those in which there are only a few spermatozoids left. But even
if they did become disintegrated, the latter, when free, would so closely re-
semble those of Chlamydococcus, which was also abundantly present, that un-
less the Eudorina could be found undergoing impregnation by itself, or apart
from this organism, there appears to me no chance of distinguishing the two,
and therefore no other means of completing this part of its history. It is
true that the impregnated cells may undergo some change in form similar to
those of Volvox glohator after impregnation ; but I think I should have seen this
among the numbers which came under my observation, if it had been the case.

" While undergoing impregnation, the female cells always contain from
two to four nuclei, as if preparatory to the third stage of development, into
which they are sometimes actually seen passing, with the spennatozoids pre-
sent and scattered among them ; but the effect of impregnation gcneraUj-
seems to arrest this stage, and thus save the species from that minute divi-
sion which leads to the destnictive termination of Eudorina already noticed.

" Sometimes aU the cells together imdergo the spermatoid fissuration, when
the Eudorina passes into Pandoriiia Morum, Ehr. ; but in this case the de-
velopment does not stop at the pyriform spermatozoids, but goes on to the
development of thirty- two larger globular cells in each gi'oup, similar to
those produced in the third stage of Eudorina above described, when they
assume respectively a dome-shaped form, held together by a membrane which
is fixed to the point in the posterior extremity of the cell from which tlic
lines of fissiparation first radiated. As the groups, however, progress in de-
velopment, this dome appears to become flatter, and. the Eudonna breaking
up, as in the third stage, these groups, when liberated, finally appear to pass
into the form of Gonium, when I think tliey perish like the corresponding
groups of the third stage. I did not obsciTC tins development (in which may
be included some abnormal states, where only one or two of the spermatic
cells fail, and one or more of the female cells take on this mode of fissiparation
irregularly) until the normal one of impregnation ceased to appear. Ehrcn-
berg was wrong in giving the ceUs of Paiulorina and Eudorina single cilia, as
has before been stated, and partly -wTong in leaA^ing out the eye-spot, both

OF THE PHTTOZOiV..

163

of Avhich, though disappQaring ultimately, indicate the continued life of the
parent-cell, as in the development of the spermatozoids, long after the forma-
tion of her progeny.

" Thus the process of impregnation in Eudorina agrees closely with that
described by Dr. F. Cohn in Voluox cjlohator, in which organism I had seen
some of the cells of the interior undergoing a spermatoid development exactly
like that above described, and also that previously figured by Mr. Busk, and
alluded to by him as one of ' microgonidia ; ' and therefore the moment I
perceived it in Eudorina, in connexion with Dr. Cohn's announcement, I felt
convinced that the latter was right, and that I had before me Eudorina also
undergoing a similar process of fecundation.

" So much for the spermatoid development ; let us now return to that of
the Eudorina in totality, concerning which there is still an interesting ques-
tion for our consideration, bearing on the early development of this organism,
which I have already stated my inability to supply, viz. how does the sixteen-
division of the ceU in the third stage of development take place, so as to allow
the cilia to become external ? It will be remembered that this cell in the
second stage, before it passes rate the sixteen-division of the third stage, con-
sists of its capsule or cell-waU. and the green contents ; and it should also be
remembered that, although these contents have now no other covering distinct
from the protoplasm but the capsule, yet in aU algal cells, whenever the green
contents take on a new form, such as that of a spore or group of cells, a second
more delicate coveiing is separated from them, for which I have heretofore
used the term ' protoplasmic sac ; ' these two coverings, then, are the parental
division of the mass, and become caducous as the rest takes on its new form
and developes on its surface a ceU-wall. Thus we get the sixteen cells sepa-
rated from their capside, &c., and surrounded by their proper cell- wall and
the external envelope, which may be a still further thickening of the former,
or a new secretion ; but, be this as it may, the cilia are seen outside it. And
at first it might be thought that they were formed before either the ceU-wall
or envelope, so as never to have been enclosed by either ; but if this were the
case, the cilia of the sixteen cells, which are added by duplicative division to
the fii'st stage of Eudorina to form the second stage, should be inside these
coverings, or protrude through the original sixteen channels with the other
sixteen pairs of cOia. However, neither is the case ; for these sixteen cells
have their channels respectively as well as the other sixteen cells, in which
case they must have been made by the sixteen new cells themselves, unless
the thirty-two-division is formed before the pellicle which subsequently forms
the cell- wall is supplied, and our fij-st stage does not pass into the second
stage, but both forms are produced at once and separately from the beginning,
— a point which can only be determined by following the development of the
Eudorina from the spore itself, and that, too, alone, since it is impossible to
say whether the sixteen-division groups, when pi'eviously mixed up with aU
the other forms of Eudorina, are or are not deiived direct from the spore, or
from the third stage of development of this organism. That the sixteen-divi-
sion or second stage may pass direct into a similar form to the tliird — that is,
into a form of Eudorina consisting of sixteen groups of sixteen ccUs each — I
have occasionally seen ; but then this form has been globular (only T^fl_j.ths
of an inch in diameter), and not ovoid, although the groups have possessed
the latter form : perhaps this is the spore, and the sixteen groups the youno-
Eudorina;, if not a different species. Again, the robust individuals of the
sixteen-division one would thinlc to be direct from the spore, and to pass into

the robust indi\'idnals of the second stage or thirty-two-division, while the

puny, meagre individuals one would think to come from the third stao-e and.

M 2 " '

164

GENEEAL mSTOKY OF THE INi'USOUIA.

as before conjectm-ed, end in disintegration and death. But all this, as I have
just stated, can only be dctennined by following the development of the spore
from the commencement. One fact I miglit add, however, viz. that the robust
forms of good size have the power of withdrawing their cQia and protruding
them again ; this happens when they are transferred, fi-om the vessel in which
they may be contained, to the slide for examination : many may just at this
time be seen to be motionless, with the channels for the cilia empty ; but
gradually the cilia are protruded thi'ough them, and as gradually the Evdo-
rina evinces increasing power of motion, until they are fully protraded, and
it swims away.

" Chlamydococcus undergoes the same kind of changes in development as
Ehdorina, from which it only differs in structure in being smaller, and glo-
bular instead of ovoid, in the absence of an external envelope, and ia the cilia
of the daughter- cells being included within the parent-cell ; hence it also
differs in being motionless, though the compartments of the daughter- cells
are sufficiently large for them to tiun romid and move their cilia fi-eely
therein, which they are continually doing. The primary cell of Chlamydo-
coccus,like that of Eudorina, divides up into 2, 4, 8, or 16 cells, and those of
the eight- and sixteen- divisions again into groups of 16 or 32 each, so as to
resemble the third stage of Eudorina. Hence we may perhaps infer that its
fecimdating process is similar to that of Eudorina ; but this remains to be
discovered. Chlamydococcus has also a great tendency to stop at the two-
and four- division, from which it may pass into the ' still ' or Protococms-foTm,
and, floating on the water in a kind of crust, present cells of all kinds of sizes
undergoing ' stUl ' division. In all its multiplications, pai'tial and entii'e,
however, it generally maintains its piimary or spherical form, and does not
become ovoid or oblong, like the groups of Eudorina, the only exceptions
being in the two- and four- division, where the green cells are sometimes
ovate (probably from want of room in the parent capsule), as represented by
Ehrenberg in G. Pulvisculus, — to which I should refer it, had he not also
given an ovate form to the type-cell of this species ; nor can I refer it to C.
pluvialis, for in all the changes I have yet seen it undergo, the red colour has
not increased beyond the minute eye-spot, Avhile this also disappears, and the
ciHa too, when this species passes into the ' still ' foi-m. Here it undergoes
the same kind of division that it does in the active state ; but the parent-
cell, instead of becoming distended by imbibition, remains closely attached to
the daughter-cells, so as to give the group a mulberrj^ shape. How long it
remains in the ' stDl ' form I am ignorant ; but having only seen it in the
active state dui-ing the months of May, Jime, and August, and thi-oughout the
rest of the year ia the ' stiU ' one, I am inclined to think that it only comes
into the active state during the summer months, and then for the pmi)ose of
fecundation.

" In several instances, also, where I have foimd this Chlamydococcus with
Eudorina, they have been accompanied by long Clostcriform ccUs. It was
the case in that above mentioned, where the latter was imdcrgoing impreg-
nation. Some of these have an eye-spot, which, witli tlic nature, arrange-
ment, and general aspect of their internal contents, sliow that they belong to
the class of organisms with which they are associated. Tlieir cell- wall also
is more or less plastic, or was so when they were assuming this spicular foi-m :
for many have one or more diverticula extending from them, some are bifid,
and a few irregularly stellate. What they are I know not ; but Dr. Cohn
has figured the same kind of cells, in company -with Sphan-ojylca anmdina,
under impregnation."

Steplianosphan-a. — To Dr. Ferdinand Cohn, to whom science is so deeply

01' THE rUYTOZOA.

165

indebted for his researches among the simplest organisms of creation, additional
thanks arc duo for the elaborate essay on a new genus of Volvodnece, m
which he has most phUosophicaUy displayed the structure and relations of
that family at large. The new genus is named by him Stephamsphcera, the
sti-uctui-al and physiological characters of which have been presented to the
English reader by an excellent translation of Cohn's original paper, in the
A. N. H. 1852, X. p. 321 et seq. Besides this account of Stephanosphcera
by its discoverer, none other exists ; we must accordingly make extensive use
of it in attempting an abridged description, — a difficult task on account of the
importance of almost every paragraph it contains.

The organisms to be described " exhibit an extraordinary variety of size and
shape," writes Cohn ; "but they are all essentially of similar structure, and
consist of eight green spherical corpuscles having their central points situated at
the circumference of a circle (XIX. 38), and of a large common envelope, en-
closing the former as a colourless vesicle, at the equator of ivhich are ranged
the said eight green glohides (XIX. 40-58).

" The common envelope is bounded by a membrane wholly devoid of struc-
ture and transparent, so that it may be overlooked if the illumination be not
properly modified, imder which circumstances the 8 green globules appear
destitute of any common bond of union. But the membrane of the envelope
always exists ; and although very delicate and thra while young (XIX. 57-58),
it becomes thickened with age, and then possesses an evident breadth, albeit
no compound stnictui'e can be detected. The membrane of the envelope is ab-
solutely rigid, and never changes its shape, excepting through the ordinary
expansion of gi-owth ; therefore it is not only totally devoid of contractility,
but is even elastic only in a slight degree.

" In whatever direction the total organism may lie during its movements,
•the envelope always appears as a perfect, absolutely regular circle (XIX. 38,
39) ; thence it results most decidedly that the membrane of the envelope forms
a sphere which may perhaps deviate but very little from the mathematical
ideal. The diameter of the envelope varies between tolerably wide limits :
while some younger forms possess an envelope ^^th of a line (0-028 mm.) in
diameter, most attain one of J^th. (0'044 mm.), and the largest are as much
as ^th of a line (0-055 mm.) in diameter.

" The phtenomena in dissolution and during propagation prove that the
membrane of the envelope immediately surrounds a colourless watery fluid,
the refractive power of which does not diifer from that of water. The enve-
lope may therefore be regarded as a broad spherical cell with a delicate strac-
tureless membrane, colourless and transparent like glass, containing a thin,
water-like, coloiuless fluid ; consequently I shall denominate it the envelope-
cell (Hi'dl-zelle).

" While the envelope-cell varies, generally speaking, only in size, and no
diflbrcnce whatever of shape and stmcture can bo detected in the different
individuals, the variations in the development of the eight green qlobes in its
interior are very great. In fact it is difficult to represent the multiplicity of
forms which here display themselves, so as to give a full and clear idea
of them; and om- figiu'os even can afford but a very insufficient pietm-e
since scarcely a single individual exactly resembles another in this respect'
The eight green bodies in the interior of each envelope-cell, wliich, for reasons
to be given hereafter, I shall call primordial cells, arc in their simplest
condition globvdar, and stand at equal distances in a cii'do at the largest
cii-cumfcrence of the cnvelope-ceU, so that tlio whole structure looks like a
i^'' ^^ith a rmg formed of eight green globules in its interior
(AlA. £}«). If the circular hnc in which the centres of the eight primordial

166

GENERAL HlSTOllY OF XnK INFUSOKIA.

cells stand, is regarded as the equator of the envelope-cell, we ordinaiilj'
jfind their position such that the equatorial zone lies parallel with the plane
of the object-glass, and the observer consequently looks down upon the pole
of the envelope-cell. In this, the polar view, the eight primordial cells
stand in a perfect circle and are placed very close to the circumference of the
envelope-cell. The distances between the primordial cells are more or less
considerable according as they are proportionately larger or smaller ; some-
times they constitute an elegant wi'eath composed of eight large green rosettes,
almost without any intervals between them, or resemble an interrupted eight-
angled star ; sometimes the green globules are so far apart as to look like the
eight spokes of a wheel. The diameter of a primordial ceU in the polar view
amounts in the former case to -j-g-yth of a line (0-012 mm.^, in the latter to
yi-g-th (0'0065), — on an average to y-^th of a line (0-0087 mm.).

" When, however, the whole revolves, so that the axis passing through the
two poles of the envelope-cell lies parallel with the stage of the microscope,
and the equatorial zone marked by the eight green primordial ceUs stands
perpendicular to the latter, consequently in the optic axis of the microscope,
the envelope-cell still looks Kke a cii'cle, because it is a sphere ; but the eight
primordial cells, lying in one plane, are then projected in a line which corre-
sponds to the diameter of this circle, so that the whole resembles, under the
microscope, a colomiess disk cut in half by a green zone (XIX. 40-58). And
in this, the equatorial view, according to the position, the four primordial
cells in the anterior hemisphere sometimes completely cover the four behind,
so that only four are seen altogether ; sometimes the latter appear through
the interspaces between the former, and all eight are seen in one line. This
view also, of course, gives very different pictures according to the size of the
primordial ceUs and the distance between them.

" Between the polar and equatorial views lie countless intermediate posi-
tions in which the ring of primordial cells, more or less contracted, appears
as an eUipse, with its longest axis constantly in the diameter of the envelope-
ceU, while the shorter axis appears longer or shorter, and the separate pri-
mordial cells are approached more or less towards each other, according to the
laws of projection.

" Besides this difference of the aspect which one and the same individual
affords merely in consequence of the different positions resulting from its
movements, a stUl greater variation is displayed in the sTuipe of the green
primordial cells themselves. I have called them globes above ; properly they
are always aciiminated to some extent, in the form of a pear, toward the
periphery of the envelope-cell ; and they are imperceptibly attenuated to a
point here, from which two cilia pass out (XIX. 38). These cilia therefore
arise from the p)ri.mordial cells inside the envelope-cell, and they emerge freely
into the water through minute orifices in the latter : from the analogy with
Chlamydococcus, I conjectui'c that there is a separate passage for each ciHum,
80 that the orifices corresponding in each case to the primordial ccUs are
placed in pairs, and all sixteen orifices occur in the equator of the cnvclopc-
cell. Hence in the polar view the eight pairs of cilia go out from the circum-
ference of the envelope-cell like elongated rays.

" The primordial cells moreover expand principally in the direction of the
axis perpendicular to the equatorial plane, so that in the equatorial Aiew tlioy
appear not spherical, but rather elliptical, or even sometimes stretched so
considerably in this direction, that they become cyhndrical or almost spindle-
shaped, without undergoing any remarkable enlargement on the other axis.
If in this case the primordial cells arc large and near togetlier, they form
in the equatorial \-icw a broad gi-cen zone inside the colourless envelope-

OF THE PHYTOZOA.

167

cell, filling lip a more or less considerable portion of this (XIX. 39), while in
the polai- view they form only a cii-cular wreath. In some instances the
proper green body of the primordial cells is only shortly cylindrical ; but it
becomes elongated at both ends into long beaks which reach ahnost to the
poles, and give each piimordial ceU something of the shape of the Closterium
setacmm figm-ed by Ehi-enberg. In this case the whole resembles a sphere
surrounded by eight green bands placed in meridians and swollen only in the
equatorial region. But even in this very frequently occm-ring preponderating
development of the one dimension, the cilia of each primordial cell are sent
out fi-om the middle of its shorter axis ; and when the primordial cells appear
projected in a zone, in the equatorial view, the motile ciHa are visible only at
four points of the diameter.

" The primordial cells are very frequently developed unequally in the two
hemispheres of the envelope-cell ; they axe not then divided into two equal
halves by the equator of the envelope-ceU, but show themselves crowded
principally into one hemisphere, which they almost fill ; and they reach almost
to the pole there, whUe they occupy but a far smaller portion of the other,
which consequently appears in greater part colourless. In such a case the
primordial cells almost touch -^dth one end, while they diverge widely at the
other, and thus they look like a kind of basket composed of eight pieces, like
the gaping dental apparatus of a ChUodon.

" Besides the two ciHa which pass out from each primordial cell, thi-ough
the orifices of the envelope-cell into the water, the former very frequently
send out other prolongations, which however do not perforate the envelope-
cell. These are colourless mucilaginous JUaments, going out from each pri-
mordial cell, especially from the ends of their longer axis, and which hence
present themselves especially clearly in the equatorial view. The ends of the
primordial cells are mostly not green but colourless, and elongated into numer-
ous, likewise colourless, broader or thinner bristle-like processes, which run out
like rays in all directions, are often ramified, and are attached to the inside of
the envelope-ceU, without however perforating it (XIX. 39). If these fila-
ments are much developed, they form a proper network, which maintains each
primordial ceU floating in the common envelope. The extremities of the pri-
mordial cells are also frequently divided dichotomously into colourless muci-
lagiaous bands, which again branch into radiating filaments and thus produce
the most wonderful forms. These colourless filiform prolongations of the
primordial cells may also be seen in the polar view, stretching in all dii-ce-
tions, and giving the total stnicture a most strange aspect, almost similar to
that of a Xanthidium.

" In the interned organization of the primordial cells, all that can be made
out is a green-coloured softish substance, of which they are composed, and in
which numerous delicate granules or points are imbedded. When the pri-
mordial cells are actively vegetating, they are of a transparent vivid green ;
but the colour exhibits various tints : in the youngest conditions it is purer',
more yellowish green, less obscured by dark points ; in the largest forms, on
the contrary, the contents appear brownish green and opake, with the dai-k
granules multiplied to such an extent, that the whole almost loses its transpa-
rency. In the middle of the primordial ccUs are found two larger, nucleus-like
vesicles, mostly symmetrically placed ; and these examined separately appear
annular, so that they possess an inter nal cavity ; iodine colours them remarkably
dark, with a violet tinge (XIX. 39). The centre of each primordial cell is
frequently occupied by a lighter circular space, which however does not vanish
penodically, and therefore cannot be regarded as a contractile vesicle (XIX 38")
" The primordial cells are not surrounded by any special rigid membrane-

168

GENKEAI. HISTORY OF THE rNFUSOIlIA.

and this is not only made evident by the multifold changes of fom which they
undergo in the conrso of vegetation, and by the filiform prolongations and
ramifications which are produced directly from theii- substance, but is clearly
shown by the transformations which the primordial ceUs pass through in con-
sequence of external influences. Under certain circumstances, namely, the
flUform processes may be retracted, being torn away from the envelope-ceU
and taken up into the substance of the primordial cells ; the produced ends
of the primordial ceUs also disappear, the latter becoming rounded off into
their original spherical or short- cyUndiical foi-m. Such a change would be
impossible if the piimordial cells were surroimded by a rigid membrane, such
as that of the envelope-cell for example. Still more rapid and decided are the
metamorphoses which the primordial cells undergo in the interior of the
envelope-cell, through influences destructive to the life of the organism.
These phfenomena, usually called dissolution, do not change the rigid enve-
lope-cell at all ; but they totally decompose the primordial cells, depriving
them of their form and dissolving them into a single structureless green mass,
which lies upon the inside of the envelope-ceU, frequently destroying all evi-
dence of the origin from eight spheres, while not a trace of special enveloj^ing
membranes comes to light. These pha)nomena of dissolution moreover indicate
that the envelope-cell, as I have already mentioned, is composed of a delicate
membrane enclosing a clear watery fluid, which cannot be dense, gelatinous, or
mucilaginous, since it is readily displaced by the radiating filaments and the
dissolved substance, and which therefore is very similar to pui-e water, if not
exactly the same.

" Motion. — The cilia which are protruded from the equator of the envelope-
ceU are but short inside this ; but the portion projecting iato the water is much
longer and vibrates actively, thereby causing all the movements. During
their vibration the cOia are difficult to detect ; but when dried on glass, and
still better by wetting them with iodine, they may readily be traced in their
whole length, especially if sulphuric acid is added, this rendeiing them more
distinct and giving them a darker coloui-. The motion of the entire organism,
depending on the eight pairs of cilia, exactly resembles that well kno^\Ti in
the Alg£e and many Infusoria. Pirst there is a rapid revolution roimd that
axis of the envelope- cell which passes thi'ough its poles and stands perj^en-
dicular to the ring of primordial cells, so that the envelope-ceU rotates like a
wheel upon its axle. In the polar view (XIX. 38), our form gives exactly
the impression of a revolving wheel, while in the equatorial ^-icw (XIX. 39),
where the primordial ceUs are mostly elongated, it has more the aspect of a
globe turning upon its axis. Besides this revolution on its axis, Avhich cndm-es
throughout the whole Ufe, there is an advancing movement, which produces
a very irregular course; in this way these organisms scretv themselves, as it
were, onwards in the water. Sometimes they SAvim straight out A\-ith unifonn
rapidity, the pole going first, the rotating ring of primordial ceUs standing at
right angles to the course and ai)pearing only in one line ; sometimes they
turn round, so that the equatorial plane presents itscU' as a circle again (in
the polar view) : they rotate thus round their centre without monng from
the spot ; tiion they set one pole forward and sAvim on in another dii-ection,
bend to the right or to tlie left, or turn quite roimd, mostly without any per-
ceptible obstniction, move in cm-ves of the most varied Idnds, ran round any
point in spiral lines, come into different planes, sometimes ascending, some-
times descending ; in short, they exhibit all those most complex and wonderful
dhncnomcna of locomotion wliich we ai'C acquainted with in the moving pro])aga-
tivc colls of the Algaj, — and, as I hiive demonstrated elsewhere, in cx^acihi the
same way in the Astomous and Anoiterous Inftisoria (Monadina, Asiasia:a,

OF THE PHTTOZOA.

169

Cnjjptomonadina, &c.), and which certainlj^ do not bear at all the character of
pm-posing, conscious volition, but appear as an activity determined not indeed
by purely external causes, but by internal causes in the organization and vital
process. The collective idea of such motions is best represented by the course
described by a top which runs through the most varied ciu-ves while at the
same time constantly revolving on its axis.

" Although Alex. Braim describes a constant revolution to the left in the
iu many respects analogous swarming- cells of Ohlamyclococcus and the swarni-
ing-spores of (Edocjoniimi, and to the light in the moving gonidia of Vaucheria
and the families of Pandorina, I must assert that no such constant law of re-
volution ea:ists in the structure here described.

" As to its systematic position. — It is evident tliat the organism we have
described belongs to the family of the Volvocinea;. For not only do we find in
it the two principal characters Avhich are characteristic of this interesting
family — the presence of a nimiber of green globes which, enclosed in a
common colourless envelope, represent a family of ceUs (polypidom), together
with the constant roUing motion which the Volvocineai possess through
almost the whole of their life, — -but our form also displays, as we shall see
hereafter, the third character of the Volvocinece, that the separate globes propa-
gate within the envelope. In fact, there exist the greatest analogies between
the knoMTi genera of Volvocinece, especially Gonium and Pandorina, and the
organism here described ; and these genera are only essentially distinguished
by the ai'rangement of the groen globes or primordial cells, which in Pando-
rina ai'e placed on a spherical siuface, in Gonium on a flat plane, while in
oiu- form they stand at the cu'cumference of a circle. Since, however, this
veiy law of arrangement is, in the family of the Volvocineas, the most im-
portant criterion on which the establishment of the genera depends, it follows
that we here have a peculiar genus which I do not find described either in
Ehrenberg's great work or in any later publication.

" If we now compare the conditions of organization of Stephamosphasra
Avith those of Chlamydococcus, we find the most essential agreement. In the
first place the envelope-cell of Stephanosphcera corresponds exactly to that of
the moving macrogonidia of Ghlamydococcus ; it is composed of a delicate
colourless membrane and contents resembKng water. Chemical actions to
Avhich I subjected the envelope- cell of Stephanospha'-ra, bear witness of this
agreement in the most minute particulars. The envelope-cell is indifferent
to acids and alkalies and is not dissolved in them ; but it suffers a peculiar
thickening by sulphmic acid, which causes it to apply itself more closely to
the primordial cell, and present itself very distinctly and clearly defined. In
general the application of dilute sidphuric acid is often the best means of
making clear delicate vegetable membranes which would otherAvise be readily
overlooked, especially when iodine is added, which then ordinarily colours the
membrane yellow. The cilia also are rendered more distinct by sulphm-ic
acid. The envelope-cells of Pandorina, Chlamydococcus, and Volvox behave
in exactly the same way.

" With regard to the chemical composition of the cnvelope-ceU of StepJia-
nosphrm-a, I have succeeded in demomtrating the characteristic reaction of
vegetable celMose, the blue colouring by iodine and sulphuric acid, in the enve-
lope-cell of Stephanosphami. Por this piu'pose it is requisite to allow a di-op
oi pretty concentrated sulphuric acid to act upon the swarming Stcphanospha;ra
globes until the green primorchal ceUs in the interior arc decomposed — bv
which time the proper transformation of the envelope -membrane has taken
place, and a drop of solution of iodine (iodine in iodide of potassium^ suffi
ciently diluted to prevent the sulphmic acid precipitating it in crystals \hcn

170

GENEEAL HISTORY OF THE INFUSOEIA.

produces a coloration of the envelope, which appears at first violet, gradually
becoming more intense, and at last beautiful indigo-blue. Thus the chemical
behaviom- of the envelopo-ceU in Stephanosphoira, as in Chlamydococcus, is
the most evident proof that the organisms to which they belong cannot be
regai'ded as Infusoria, but are simply Alga3. Moreover this behaviour of the
envelope-ceU of Steplianosphaira shows that the latter is bounded by a true
cellulose membrane, and not, as is assumed almost universally of the Volvo-
cinea;, and by Nageli even of aE. Algae, of secreted mucus or jeUy, The direct
obsei-vation of the envelope-cell of Stephanosjphcera likewise shows that this
is completely closed in its normal condition, and only perforated by orifices
in the spots where the cilia of each primordial cell pass out. Not until a
later stage, when the primordial cells singly leave the envelope or have begun
to propagate, does the membrane of the envelope tear, gradually coUapse, and
become dissolved, so that the included globes can make their exit freely.

" It is obvious that the eight green globes of Stepliamsphmra correspond
exactly to the primordial cell of Chlamydococcus. The primordial cells of
Stephanosplicera consist in like manner of nitrogenous protoplasm, in itself
colourless, which is colom-ed brown by iodine and almost whoUy dissolved by
caustic potash and ammonia. The protoplasm is coloured by the universal
colouring matter of vegetables, chlorophyll ; for alcohol and aether bleach the
green globules, and concentrated sulphuric acid changes the green colour into
a verdigris-green or blue, — a reaction which, from my observations, is cha-
racteristic of chlorophyll.

" The chemical nature of the fine granules in the primordial cells, which
"with age multiply so that the primordial cells at length lose their transparent
green colour and appear dull, opake, and olive-brown, is difficult to deter-
mine on account of their small size ; they are either protoplasm-granules,
or, as a bluish colour given by iodine might leave one to conclude, perhaps
starch-granules. On the other hand, the tivo darker nuclei in each pri-
mordial cell are undoubtedly the same structui-es which occur in Chlamy-
dococcus and, in like manner, not only in aU the Volvocinece, but also in most
of the Algae of the orders of Palmellece, Desmidece, Confervece, &c. Nageli
has called these chlorojjhyll-utricles, and demonstrated their universal occur-
rence in the vegetable kiigdom by comparative descriptions (Gattung. einzell.
Alg. n.). Ordinarily there exist only two in Stephanosphcera, which may
be distinguished in the earhest stages, — while, among other Volvocinea, for
instance, Gonium contains only one chlorophyll-utricle. It is difficult to settie
anything definite concerning their structure and fimction ; they must not be
regarded as ceU-nuclei, although they resemble them verj'- much, especially
when only one is present. Caustic potash, which destroys the rest of the
contents of the primordial- cells, makes the chlorophyll utricles of Stepha-
nosphcera show themselves more distinctly as hollow rings, surrounded by a
membrane which is rather granular ; iodine colours them deep viol-ct, which
leads to the conclusion of the presence of stai'ch. Ehi-enberg thought the
chlorophyll-utricles were to be recognized as the testes of the Volvocineee ; it
is certain, however, that these structui-es may be seen in greater or less
number, in exactly the same way, in undeniable plants, such as Hydrodic-
tyon, (Edogonium, Mougeotia, and others.

" I have already show that the primordial cells of Stephamspha;ra as well
as those of Chlamydococcus are destitute of a special rigid membrane ; con-
sequently they do not correspond to perfect cells, but on the whole only to
primordial utriclos. In lilvo manner the curious colourless mucous filaments
which extend out from the extremities of the primordial colls of Stepha-
nosphcera are evidently analogous to the rays which make one condition of

OF XUE rnrxozoA.

171

the CJilcmydococcus-CGlla look hairy (var, setlger, V. Flotow). They are
merely prolongations of the colourless protoplasm forming the substance of
the primordial cells, and correspond pretty well morphologically to the reticu-
lated branching filaments of protoplasm, the sap-currents as they ai-e termed,
which maintain the nucleus suspended freely in the interior of the ceUs oi
the articulations of Spirogyra or of the hairs of the anthers of Tradescantia.
Alcohol and acids cause these prolongations to be retracted into the substance
of the piimordial cells ; the same thing takes place diu'ing the course of the
development. Ehi-enberg has called these peculiar mucous rays, which also
occur in some other Volvocinece, in some cases a tail {Synura, Uroglena), in
others connecting canals or Ladications of a vascular system (in Volvox and
Oonium). These protoplasm-filaments natiu'aUy present a diff'erent aspect
according to the shape and arrangement of the primordial cells : while they
appear as a wi'eath of cUia in the globular Chlaniydococcus-ce]!, in the more
spindle-shaped Steplianosphcera they rather resemble bundles of rays passing
out from each end ; in Volvox, if seen only from above, they give the indi-
vidual primordial cells a polygonal, radiating aspect, and form threads of
communication between them : Focke has wi'ongly considered them as inter-
cellular passages between the individual animalcules. The connecting threads
in Oonium, on the other hand, are something quite different, and do not belong
at all to the domain of the protoplasm-filaments, as I shall explain more fully
at another opportunity.

" Thus the microscopic analysis, like the chemical investigation, of StepJia-
nosplicera, in exact analogy with Chlamydococcus and the swarming-cells of
the other Alga3, has enabled us to distinguish all the characters of a plant,
but not one mark of a true animal organization, in particular not a trace of a
mouth, stomach, and sexual organs. But the genus Stephanosphcera is thereby
pre-eminently important for the decision of the question of the limit between
the animal and vegetable kingdom, because the history of its development a ffords
the most convincing proof of the vegetable nature of this genus, and thm of all
the other Yolvocineae.

" Development of Stephanosphcera. — Both the very delicate envelope-cell
and the widely distant, transparent, green, globular, primordial cells of the
young StephanosphcBra are of a relatively small size. Both grow so much as
to double theu- dimensions during their vegetation : the former acquii'es a
tough membrane ; the latter fill up the greater part of the envelope-cell,
advance towards each other so as to touch, develope thicker, denser contents
and assume most cmious forms through the ramification of the protoplasm -
filaments. Finally the process of propagation shows itself in the primordial
cells. The radiating ends retract all their prolongations, and become rounded
into a perfect sphere ; the primordial cells are now merely attached to the
envelope-cell by their cilia, and thus are readily moved from their normal
corresponding positions, and then appear devoid of any definite arrangement
in the envelope-ceU.

" These changes take place in the course of the afternoon ; towards evening
more influential metamorphoses make their appearance. The primordial cclf
namely, extends itself predominantly in one direction in the axis perpendicular
to the equatorial plane, consequently in the position which represents from
above downwards. The two chlorophyU-utriclcs respectively repair to the
two ends ; the green contents likewise flow chiefly to the two sides, and leave
a broad colourless zone visible in tlie midrlle, such as we observe somewliat in
the same position in Closterimn. Finally the primordial coll becomes eon
stiicted, gradually from the periphery to the centre, in the middle line and
18 thus divided into two socondaiy cells, the septum of which, in the position

172

OENEBAL niSTOET OF THE INrUSOEIA.

above assumed, rans from right to left. Each of the halves cut off by the
division then expands somewhat in the direction from left to right ; a new
constriction soon presents itself in the direction from above doAvnwards;
when this is complete, the originally globular primordial cell is divided into
four- quarters (XIX. 40).

" This process of constriction and cutting off is repeated once more, each
secondary cell becoming divided by a new septum into two equal halves
(XIX. 41-56).

" This process of division, by which each primordial cell produces in the
fii-st generation two, in the second four, and in the third eight secondary cells,
is completed in the course of the night, so that early in the morning, in the
long summer days even by 3 o'clock, we perceive each of the eight primordial
ceUs divided into eight in the manner described (XIX. 41, 42). The gene-
rations produced in each case by this triple subdivision vaiy in the duration
of their lives and in their capacity of development ; the first two rapidly
divide again, and therefore are, according to Niigeli's expression, mere
' transitional generations ; ' the thii'd alone arrive at complete development
and persist a long time as such ; these form the 'permanent generation.'

" The process of division does not always take place simidtaneously in all
the eight primordial cells of Stejphanosphcera ; we not imfrequently find inside
the same envelope-cell some primordial cells still wholly unaltered, while
others are already preparing to divide into two, a third perhaps ah-eady into
four, and a fourth has abeady resolved itself into its eight secondary ceUs.
Very often most of the piimordial cells are foimd already completely sepa-
rated into eight, while one or other of them is still wholly unaltered.

" When the act of division has gone on favoui-ably up to the point to which
Ave have followed it above, some hours elapse before the young families of ceUs
escape completely from the envelope. The process which precedes their birth
consists principally in the more complete isolation, in a centrifugal direction
around their common centre, of the secondary cells produced by each pri-
mordial cell. Since the parting off of the secondaiy cells advances gradually
from the periphery towards the centre, they are akeady completely indivi-
dualized and separated by intercellular spaces at the peripherj% while all eight
remain still connected in the centre into a common colourless mucous mass
filled with protoplasm-granules (XIX. 42). But the flow of the contents fi-om
the centre to the borders, which continues up to this time, at length causes
the constriction of the central mass of protoplasm also into eight parts ; the
eight secondaiy cells then appear of a deep yellowish green externally, passing
internally into colourless green towards finely granular beaks which are all
connected in the centre, but become gradually attenuated, torn away, and
retracted. Then the young primordial cells become rounded into short
cylinders and stand in a circle, -without organic connexion, but placed closely
beside one another : seen from above (in the polar view), under the micro-
scope, they resemble a wheel Avith eight notches ; fi-om the side, examined in
the equatorial view, we see four or eight short cylinders lying side by side, —
so that the whole is not unlike a small Scenedcsmus ohtusus (XIX. 57-58).

" The piimordial cell undergoing division behaves as a whoh towai-ds
external things, until the parting off into eight is quite completed ; that is to
say, its two cilia move uninterruptedly, and consequently the entii'e Ste-
p7ianosj)hcera-gl6hc still rolls through the water according to the known laws,
even when most of its primordial ceUs have already become more or less com-
pletely divided into foiu" or eight secondaiy cells. Only shortly before the
completion of the division do the cilia of the parcnt-ceU lose their motion and
disappear, it may be by being retracted or by being thrown off; but the

OF THE PnYTOZOA.

173

orifices through which the cilia previously passed out into the water may
now he observed in the common envelope-cell, as miaute points surrounded
by a thickened border.

" Immediately after that, it is seen that the newly-formed secondary ceUs
have developed their owa cilia; for the yoimg generations formed in the
interior of the pai'ont- envelope now begia to move and to roll over like a
wheel, so far as the confined space allows of this. In consequence of this
movement of the eight small wheels rotating in the interior of the common
envelope-ceU, which constitutes a very pretty object, the parent-ceU _ soon
becomes enlarged and attenuated at certain points ; the cellulose of which it
is composed appears to be transformed into soluble jeUy, and soon afterwards
one after the other breaks through out of the common envelope and revolves
freely and independently in the water, according to the same laws as the old
spheres, but more actively and energetically. The young Steiihanosphaira
exactly resembles a green wreath composed of eight small cylinders, upon
which by itself no envelope and cilia can be detected (XIX. 42, 48, 49) ; but
if killed with iodine, the eight piimordial cells are seen to be surrounded by a
common envelope-cell in the form of an exceedingly delicate membrane, — only
this lies in all parts almost immediately upon the green globes, so that it
follows the waved outline they produce, and in its total form resembles a flat
spheroid with eight notches on its border ; it is perforated by the cilia, which
go off in pairs from each of the primordial cells ; and two chlorophyll-utricles
are already distinguishable in the latter. By degrees the envelope-ceU is
lifted up by the endosmotic absoi-ption of water ; its surface becomes smoothed
out, and it appears circular in the polar view ; on the other hand, it retains
for a longer time the form of an almost tabular spheroid, and hence presents an
ellipse in the equatorial view (XIX. 58) ; finally it expands uniformly in all
directions and thus acquires its normal spherical form, while at the same
time it becomes considerably thickened. This whole process of propagation
is completed during the night ; and on bright days Stephanosphmrm are rarely
seen in com-se of division at sunrise ; on dull days they may be observed in
this condition in the first part of the morning.

" The primordial cells, however, not unfrequently come to a standstill in
the stage of division of the second generation, so that they only separate into
four secondaiy cells ; these at once develope cilia and an envelope-ceU, with-
out dividing a third time, and make theii' exit from the parent-envelope in
this condition. Here therefore only the first generation of each piimordial
cell is a transitional generation, the second ah'cady a pennanent generation.
Hence arises the circumstance that we often find, among other eightfold Ste-
phanospJuera-glohcs, some in which the envelope-cell encloses only foiu- pri-
mordial cells standing at equal distances, which in other respects behave in
the ordinary manner.

"It is still more frequently observed, when the primordial ceUs have
already become constricted into four sccondai-y cells and are beginning to
divide again into eight, that this process of division is not perfectly completed
in all foui- portions, but that the young Stephanosphmra already becomes free
and developcs the envelope-ceU, although one or other of the foiir quadratic
segments of the sp)here has become constricted but not jiaried off! Hence origi-
nate monstrous foiTns, since the general envelopc-ccU then encloses only
seven primordial cells ; but in these cases it is always observed that one of
them is distinguished by most curious prolongiitions or mucous filaments, that
it appears twice aa large as the rest, that it contains four chlorophyll-utricles
instead of two as is usual, and that it is also more or less constricted in the
middle. AU this furnishes proof that here one secondary cell of the second

174

OENKllAL HISTOliY OF TUE INFUSORIA.

generation has not been divided the third time like the rest, but occupies l)y
itself the space which is ordinarily filled by two. Very often only six or
even no more than five primordial cells are found in one envelope-cell ; but
then two or three of these are twice as large as elsewhere. In like manner
Alex. Braun figures a Pediastrmn composed of fifteen instead of sixteen cells,
wherein one, however, is twice as large as the rest.

" On the whole, it is obvious that the mode of propagation of SlephanosphcBra
already examined corresponds completely to that we are abeady acquainted
Avith as formation of macrogonidia in Chlamydococcus. It both cases it de-
pends upon the envelope-cell remaining unaltered, while the primordial ccUs
become divided, first into two secondary ceUs, and then so on in a lower
power of two, each of the secondary ceUs immediately developing two cilia, and
secreting over its whole surface, as do all piimordial utricles of vegetable
ceUs, a delicate cellulose membrane, which, however, becomes gradually re-
moved fiu'ther from the secreting primordial ceU through absorption of water.
The only distinction between Chlamydococcus and Steplianosphcera arises fi'om
the formation of a special envelope-cell to each individual secondary cell in
Chlamydococcus, while in Stephanosjihcera all the generations produced by
division form one primordial cell, become enclosed by a common envelope,
and move away as families of cells. On the contrary, the developmental
history of Oonium, Pandorina, and Volvox agrees in all essential particulars
with the laws of propagation which I have just described in Stephanosplw^ra,
as will be shown elsewhere. We may caU. the mode of multiplication of the
Volvocinece by the general name oi propagation by macrogonidia.

" Another process is met with in Steplianosphcera, besides the above, and
which I have observed more rarely, viz. propagation by microgonidia. In
this mode of multipKcation the introductory processes are exactly like those
of the formation of macrogonidia ; in particular each primordial cell is at first
divided into two, then into four, and lastly into eight secondary cells. But
instead of this thii'd generation being permanent and becoming free, as is
usual, it not unfrequently happens that the process of division is not arrested
with the separation into eight — that the original piimordial cell becomes
parted off a fourth, fifth, and even a sixth time, in the same manner, and at
length is broken vp into a large number of cells (16, 32, 64), which naturally
are so much the smaller the greater number of times the subdivision into two
has taken place (XIX. 43, 51). These little secondary cells finally become
totally separated from one another, without secreting an envelope-cell. These
little cellules — I shaU follow the example of Alex. Braim and call them
microgonidia — exhibit a very active and energetic motion inside the envclope-
ceU, hurrying very rapidly up and doAvn in aU directions in its cavity, pro-
ducing by their great number that curious swarming which Alex. Braun has
very aptly compared with the intermingling of a crowd of peoijle in a confined
area, where every one is constantly changing his place, wlulc the whole
togetlier constantly occupy the same space. Sometimes the ccUules are
scattered in a few large masses ; then they unite again into a Icnot in the
middle ; every moment the general aspect varies. At length the common
envelope is ruptured where the microgonidia emerge one after another or in
large masses, but free and singly, into the water. Their true form may be
then readily detected by killing them with iodine ; they are spindle-shaped
and acuminated at both ends, bright green in the middle, and run out into a
colourless beak at each end, on the whole not unlike young Eugleno'. without
a trace of an envelope-cell ; the extremity which goes first in their swimming
bears delicate cilia ; the number of the cilia is four (XIX. 52). When the
microgonidia reach the water they move most actively in all directions, and

OF Tina PHTTOZOA.

175

in a short time all the eorpusclos emitted from an envelope-cell are scattered
and disappeai- ia the wide surface of the drop of water.

"I have not been able to make out what becomes of the microgonidia
subsequently, since they are ordinarily decomposed on the object-holder after
a brief swai-ming ; but it may be conjectured that they also serve for propa-
gation, and probably pass into a condition of rest. At least the latter has
been observed in the microgonidia of Ohlamydococcus pluvialis by Alex. Braiin
and myself: the history of the development of the latter agrees wholly with
those of the Stephanosplicera ; they originate also by the division of the pri-
mordial cell in a higher power, are distinguished by their minute size and
more active, pecuharly Infiisorioid movement, and never develope an envelope-
cell during their movement. The microgonidia of both therefore are true
primordial cells ; that is, primordial utricles resembling cells, organized ex-
clusively of coloured protoplasm, without any cellular membrane. The only
distinction between them is, that the microgonidia of Ohlamydococcus, Uke
their macrogonidia, possess tivo cilia, while in those of Stephanosphcera I
observed four. That the microgonidia of StephanosjpJicera correspond per-
fectly in morphological respects to the macrogonidia, and only depend upon a
higher power of division, is proved by a case in which seven out of the eight
primordial cells in one envelope-cell were broken up into microgonidia, while
one divided merely into eight secondary cells ; the latter were developed aS
macrogonidia, and formed a connected wreath surrounded by an envelope-cell,
which roUed slowly about in the parent-envelope, surrounded by the swarm
of free, rapidly moving microgonidia.

" Abstracting the differences which may be shown always between two
genera, we detect the same laiv of development in Hydrodictyon as in Stepha-
nosphasra, — viz. the biciliated less numerous macrogonidia arrange them-
selves into a family of cells already within the parent-cell, according to the
character of the given conditions of the two genera, the cell-family being
active in the Volvocinece and immoveable in the Protococcacea;, while the
more numerous more actively moving microgonidia with foiu' cHia leave the
parent-cell and enter upon a metamorphosis, the retrogradation from which
to the normal type of the genus has not been obsei-ved yet here, or indeed in
the microgonidia of any of the Algae. Such an imdeniable agreement of the
law of development of Stephanosphoira with an undoubted plant like Hydro-
dictyon, which testifies to a near relationship, would be inconceivable if the
former were to be regarded as of essentially different organization — as belong-
ing to quite another kingdom of nature. Thus the developmental history of
Stephanosphaa-a also furnishes the most convincing proof of the vegetable
nature of this genus, and consequently of the Volvocinea; generally.

" That the formation of macro- and microgonidia does not exhaust the
whole series of forms which Steplianospha;ra may pass through, is proved by
the following observation, which imfortunately I have not yet been able to
complete. Having cultivated some Stephanospha^rai for a long time in a little
glass cup, in the way described in my essay on Loxodes hursaria (l, c), all
the primordial cells at length exhibited dark, thick, greenish brown contents
so densely hlled with numerous granules that the two chlorophj-U-vesiclos
could no longer be detected ; their form was more or less globular, and the
mucous radiating processes were entirely absent ; their outlines wore remark-
ably sharply defined, as if they had become suiToimdcd by a rigid membrane.
At the same time I remarked that the piimordial cells were no lono-cr fixed
immoveably at the periphery of the envelope cell, never changing their relative
positions, but jerked hack-wards and fonvards, finally tore themselves away
from the envelope-cell, and then began to rotate slowly and lazily in the interior

176

GENEHAI, niSTOKY 01' TUE INFUSOEIA.

Soon after, I saw the envolopc-ccll also bm-st at some spot and collapse ; and
the eight primordial cells gradually emerged, one after another, as 'inde-
pendent globes : they were now seen to be enclosed in a pretty closely applied
envelope, through which penetrated two oiHa ; and hence they presented the
utmost resemblance to Chlamydomonas Pulviscidus. They moved about for
some time in the water and at length came to rest, losing their cilia and accu-
mulating nice little green Protococcits-globules at the bottom of the glass. We
therefore have here a motionless, perfectly plant-like stage of Stejyhanosphcera ,
such as we are acquainted with in Chlamydococcus and Chlamydomonas ; the
remainder of the Volvocinem undoubtedly pass into a similar condition of
rest, which is the means of their preservation when the water of ditches is
dried up in summer. The emergence of single globes from the common enve-
lope, in a form resembling Chlamydomonas, may also be readily observed in
Gonium.

" I conjectui'e that the motionless Protococcoid cells of Stephanosphcera are
the means of the presei-vation of the species when the water, as is always
the case in the shallow hoUows in stones, their natural station, is dried up
for a long time and all the living inhabitants are j^recipitated on the stone.
The observations of Major von Plotow have already demonstrated that the
diied-up muddy sediment always reproduces Stephanosphcerm when water is
again poured on to it. This capahility of reviving from the dried condition
is shared by StephanosphcBra with Chlamydococcus pluviaUs, in which likewise
the motionless cells remain living after being dried up for years, and are capa-
ble of giving birth to moving forms, while the swarming- cells themselves are
destroyed for ever by rapid desiccation. Herr von Flotow has sent earth with
dried Stephanosphcerce to Dr. Eabenhorst in Dresden, who, in like manner,
succeeded in reviving them by moistening.

" Since the moving Stephanospharce are destroyed, just like the swarming-
cells of Chlamydococeus, by rapid desiccation, I beheve that the motionless
Protococcoid globes, the development of which I have just described, are the
forms which do not lose their vitality by drying, but are capable, when wetted
again with water, of going through a cycle of ■ development, by which they
return to the normal moving form of Stephanosphcera. Yet I must remai'k
that I have not hitherto obtained sufficient material to observe the resting
Stephanosphara, and to trace the processes which occur in the revivification.

" Kespecting their vital manifestations, repeated experiments showed that
the moving spheres 0/ StephauosphaBra seek the darlcer part of the vessel, avoid-
ing however a total abseoice of light, and assembling in j)reference in a moderated
light or half-shadow. Since other Alga; and Infusoria exhibit a different
behavioui" towards the light, we thiLS possess a means of sorting, to a cer-
tain extent, the microscopic inhabitants of a specimen of water, as I did the
shade-loving Steplianosphasrai from Chlamydococcus, which ordinarily seek the
brightest light."

An important appendix to this history of StepJianosphaira has quite recently
appeared from the joint labours of Professor Colm and Wichura (Mv. Act.
Acad. Curios. Naturce, 1857, Part I.), and has been translated into English
by Mr. Currey {J.M.S. 1858, p. 131). _ .

The resting-stage above spoken of is again referred to concisely and clearly
in this paragraph : — " Under certain cii-cumstances each of the eight cells
secretes a cellular covering, and swims about in the interior of the globe in
tlie form of free Chlamydomonas-MVe cells (XIX. 44) ; eventually they escape,
cither by fissure of the globe, or by its gradual chssolution, lose their cilia ,
form a thicker membrane, become motionless, and accimiulate at the bottom
of the vessel. If the vessel bo then permitted to become thoroughly dry, and

OF THE PUYTOZOA.

177

afterwards be again filled with water, motile Stephanosphcerce reappear, from
■which it seems probable that the green globes are the resting-spores of the
plant." These, it may be added, ai-e with difficulty, if at all, distinguishable
from those of Chlamydococcus pluvialis : they vary very much in size, and
apparently grow after entering on the state of rest. Their colom- is deep
green (occasionally yellowish or oHve) ; and they have a nucleus, and fre-
quently a nucleolus. We cannot do better than copy Mr. Carrey's abridged
translation, in endeavouring to convey the results arrived at by Cohn and
Wichui'a : —

" When the water is permitted to evaporate gradually, the resting- cells
become yellow, and afterwards orange or red, and their contents have a more
oily appearance. The authors found that if the water was not permitted to
evaporate, the resting-spores, although continuing to Hv€, did not become
developed into Stephanosphcerce ; but when fresh water was poured upon de-
siccated resting-spores, twenty-four hours sufficed for the production of motile
Stephanosphcerce.

" The following is the process of transformation from the state of rest into
the motile form.

I " The dried resting-spores take up the water, and their contents (hitherto
somewhat misshapen) gradually fill up the cavity of the containing mem-
( brane, and become cloudy and granular ; the border becomes yellowish, and
i the red colouring matter is concentrated in the centre. The cells then begin
to divide ; and the successive forms assumed in this process will be better
I understood by reference to XIX. 44-47, than by description. In pass-
( ing from the state shown in fig. 45 to that shown in fig. 46, the outer mem-
brane has gradually become invisible. Up to fig. 47 the process has occupied
about two hours. The four daughter- cells (fig. 47) begin to quiver, and to
endeavour to separate from one another. Two cilia are now perceptible at
the pointed extremity of each of the four cells, by the action of which the
group begins to move as a whole, and in a laboured manner, in the water ;
ultimately, however, all trace of the enveloping membrane and of the gluti-
nous connecting substance disappears, and one by one the daughter-cells
escape and become free. Figs. 48 and 49 exhibit different forms of these
free daughter- cells, which contain two, three, or several granules (amylon ?)
and sometimes also vacuoles. The sharp end is often prolonged into a colour-
less beak. At this period there is no proper cellulose membrane. At the
moment of escaping, their diameter never exceeds 0-010 mm. ; but they soon
enlarge and attain a diameter of 0-013 to 0-015 mm.

" Their form and the length of the beak are variable, the latter being some-
times altogether wanting. In form and motion they resemble exactly the naked
primordial-cells, which are produced by division from the resting-cclls of
Chlamydococcus pluvialis. The authors have never seen the resting-colls of
I Stephanosphcerce divide into more than four parts, but think it not improbable
: that division into a greater number (eight or possibly sixteen) sometimes
occurs.

" The length of time which elapsed between the immersion of the di-ied
! resting-spores and the first appearance of the motile cells varied from nine to
twenty-four hours. It was noticed that those resting-spores wliich did not
produce zoospores within six days never did so afterwards, although they
continued to live and were perfectly licalthy.

" Zoospores, produced in the month of November, did not advance beyond
the first stage (fig. 49). Others, however, produced in March, remained only
a few houi-s in that conchtion, after which time a deUcate membrane was
formed round the body of the pi-imordial ceU (XIX. 50 ); this membrane was

N

178

genehal history of the inftjsobia.

at first closely attached to the primordial- cell, but became gradually enlarged
by absorption of water into a colourless enveloping vesicle (figs. 50, 54),
usually globular but sometimes oval, having two openuigs, through which the
cUia penetrate. In this condition they attain a diameter of 0-017-0-022'",
and arc not distinguishable from encysted forms of Chlamydocoixus plu-
vialis. Other zoospores, produced on the Ist of Apiil, 1857, attained a larger
size ; and the protoplasm of the primordial cell, instead of retaining its con-
tinuous outline, became elongated here and there into simple or forked muci-
laginous rays, which were either coloui'less or green from the presence of
chlorophyll (fig. 53). These rays are probably produced by the protoplasm
adhering at certata points to the surrounding membrane, and being carried
outwards by its growth.

The Ohlamydococais-like foi-m only lasted a few hours : towards the even-
ing the zoospores mostly began to divide. In the fijst place, the protoplasmic
rays are drawn in, and the primordial cell becomes round ; it then elongates
itself in the direction of an axis passing thi-ough the point of origin of the
cOia, and by the process of division assumes the forms shown in figs. 54 and
55. This state is usually attained by about nine o'clock in the evening ; and
about eleven o'clock a constriction commences in a plane at right angles to
the former plane of division ; and eventually the primordial cell is divided into
quadrants, each containing a nucleus and a portion of the red substance. The
two cOia, which have retained their activity, originate in the interspace be-
tween two quadrants. About midnight usually, but sometimes earlier, con-
striction recommences, and the fonn in fig. 56 is attained. This constriction
proceeds towards the middle point of the sj)heroid, by which the quadi-ants are
bisected, and idtimately divided into eight wedge-shaped portions, whose con-
tour-lhies, like the spokes of a wheel, meet in the middle.

" And now commences a further process of development, which forms the
ground of the generic distinction between Stephanosjphcera and Clilamydo-
coccus. For, whilst in Ghlamydoeoccus the individual portions of a piimor-
dial cell separate entirely from one another, each developing its own enveloping
membrane, and ultimately escaping as a unicellular individual, in Stephano-
sjphcera, on the other hand, the eight portions remain united as a family. The
coloured contents of the individual portions become di-awn back towards the
periphery in a centrifugal direction, a colourless plasma remaining about the
central point ; this disappears at fii'st in the centre ; a cavity is fonned in the
middle of the disk ; and as this enlarges, the eight portions assume the fonn of
a wreath, consisting of eight globular or ellipsoidal bodies in close cont-act
(fig. 57), and usually not exactly in one plane, o-wing to the outer membrane
not having expanded in proportion to the enlargement of the plasma. The
original cilia continue active, causing the motion of the whole organism, until
the eight portions are completely individualized ; and then their motion ceases :
but at this period each of the eight parts may be seen to be provided Avith two
cUia, which are in motion so far as their limited space allows.

The separate paris of the plasma now form eight independent but closely-
packed membraneless primordial cells. Shortly afterwards it is seen that a
delicate membrane, common to them all, has been secreted beneath the mo-
ther-ccU membrane, round the disk formed by the primordial cells ; tliis
membrane at fii-st lies in close contact -with the latter cells, following the
constrictions of the disk, but afterwards becomes further and further re-
moved as it swells and tends to assume a globular form (fig. 58). By tlie
motion of the cilia the mother-ceU membrane is gradually throAvn off", and the
young family escapes into the water. Its eight green primordial cells still
enclose the last traces of the red s>i1)stflnce, which gradually disappears, and

OF Trnj PHYTOZOA.

179

instead of which are seen two granules; the primordial cells are in im-
mediate contact at the sides, and are of an oval or globular shape ; their
common enveloping membrane is at first constricted at the border following
the outUne of the primordial cells ; it eventually becomes globular, although
continuing for a long time much flattened at the poles, in the form of a disk-
shaped spheroid. When the Chlamydococcus-]ike uniceUular Stephanosphcera
has commenced its division early in the evening, the division into eight is
perfected during the night, and eaiiy in the morning the young family quits
its cast-off mother-ceU membrane.

" In the course of the day the individual primordial cells, and their common
enveloping membrane, grow until the latter attains a diameter of 0-040 -
0-048'". During this growth the shape of the primordial cells is changed
by the formation of various prolongations in the manner above described :
but in the course of the afternoon the primordial cells again become round ;
and during the evening, division commences in them precisely similar to the
process in the uniceUular Ste]phanosphcera : on the following morning we
find eight young families, with the common enveloping membrane, which
soon escape and go through the same process. It I's calculated that in eight
days, under favom-able circumstances, 16,777,216 families may be formed
from one resting-ceU of Stephanosjphcem. It is remarkable that the division
of the primordial cells in Stephanosphcera is confined to a certain time of day :
it begins towards evening, and is completed the following morning. In the
observations made in Lapland, at a time when the daylight there lasted dui'ing
the whole night, the beginning and end of the division were observed to take
place at almost the same hours as in the observations made at Breslau in the
spring, when the day and night were almost of equal length. Sometimes
the division ceases after the formation of only foiu- primordial cells. On one
occasion the authors observed a family with only thi-ee cells, one only of
the two halves first formed having undergone a second division. In Lap-
land a family with sixteen cells was once observed.

" The authors then proceed to discuss the natm-e of the resting- cells in
StepTianosphcera and Chlamydococcus, and come to the conclusion that they
are not spores ; i. e. that they are not of the same nature as the red cells of
CEdogonium, Bidhochcete, Di'aparnaldia, Chcetophora, Sphceroplea, Volvox, &c.

" They come to this conclusion upon two grounds : 1st, that the resting-
ceUs in question continue to grow after becoming quiescent ; and secondly,
that it is probable (although not yet proved) that the resting-cells increase
by self-division, thus producing new generations of resting-cells. These two
characteristics the authors consider inconsistent with the idea of a spore.

" In conclusion, the authors notice the formation of microgonidia in Stcpha-
nosphcera, which takes place by the division of the piimordial cells into num-
berless smidl portions. Fig. 5 shows a Stephanosphcera, in which seven of the
eight primordial cells have formed microgonidia ; the individual microgonidia
(fig. 52 a, b, c) become free by the disintegration of these eight groups into
their constituent portions. The authors think it not improbable that the
microgonidia exercise an impregnative influence in spore-formation, but admit
that there is no evidence to prove it."

Mr. Curroy (J. M. S. 1858, p. 209) reopens the question concerning the
nature of the red resting-cells of Steplianospha;ra, and argues against the
conclusion drawn by Cohn and Wicluu-a. Ho says those observers have
noticed " that these cells in Stephanospha'.ra pliivialis, which arc at first of a
green colour, and furnished with cilia, iacreasc in growth after the green
colour and the cilia have disappeared, i. e. after they have assumed a state of
■ rest, a fact which they consider to militate against their character as spores.

N 2

180

GENERAL HISTORY OF THE INFUSORIA.

" ' We have seen,' they say, ' that these resting-cells, after they have been
formed by the metamorphosis of a motile primordial ceU, increase in g^o^vth
considerably, that they go through a further vegetative development, and
have, therefore, not reached the termination of their vital process.' And
they then add — ' It is contrary to the idea of a spore, that it should continue
to grow after having assumed the character of a resting-ceU ; and the fact has
never yet been observed in any single case.' It would seem that these
remarks are intended to be limited to the Algse ; but it is worthy of observa-
tion, that the spores of the ascigerous Fimgi frequently increase in growth
after escaping from the asci ; and if this circumstance is not to be looked upon
as affecting their character as spores, it is difficult to see why a different rule
should be applied to the Algae.

" Cohn and Wichm-a moreover consider that the increase by self-division
is irreconcileable with the idea of a spore. In speaking of the red cells of Chla-
mydococcus pluvialis, they express a doubt whether in those cells increase by
self-division takes place, but assert that, if such should prove to be the case,
it would be conclusive against their being spores, considering self-division (if
I understand them right) to be a process of vegetative development distinct
from germination. These observations are worthy of the careftd attention of
microscopists ; and without venturing an opinion as to their con-ectness, I
would only remark, that if the resting-ceUs of Chlamydococcus and Stepha-
nosphcera are not to be considered spores, that character must also be denied
to the resting-cells of (Edogonium, Bidbochcete, Draparnaldia, Sph<eroplea,
and Volvox, if, as is more than probable, there should be detected in these
latter cells, 1st, an increase in growth after becoming quiescent ; or, 2dly,
increase by self-division."

VoLvox (XX. 32-49). — This genus has always been an especial favour-
ite with microscopical students. Its colonies of numerous monadifoi-m green
bodies distributed over the surface of miniature globes, endowed with active
motion, revolving hither and thither, form one of the most pleasing objects
that the microscope can display. Moreover, the more minutely the globes of
the Volvox are examined, the more interest do they awaken, by reason of the
reg-ularity and beauty of their intimate structure, and of the results of their
vital processes.

The consequence of this has been a host of observers and writera on the
anatomy and physiology of Volvox, and a formidable array of conflicting
views on those topics, the consequence of careless and insufficient research,
of indifferent instruments, and of the influence of fanciful hyiDothescs. We
shall, however, attempt no analysis of the many accounts of Volvox in
existence, but restrict oui'selves to an abstract of the more recent important
observations and conclusions of Professors Williamson and Busk, particularly
of the former and earlier observer on that organism, premising it by a brief
notice of Ehi-enberg's views.

Formerly tlie whole globular mass was regarded as a single warty and
ciliated animalcule ; and the act of bursting, wliereby the smaller globes de-
veloped within it which had reached maturity were Uberated, was considered
to be the birth of young animals. This theory Elirenberg clearly proved to
be eiToneous, and showed that, to use his language, the supposed spherical
animalcule was in rcahty a colony of monad-like beings distributed over the
inner surface of a common lorica, and connected together by filiform cords or
tubes ; in other words, he proved each sphere or globe to be, if we may so
term it, a lioUow cluster of many liundreds or even thousands of liring occu-
pants, and to frequently contain within it other smaller hollow spheres,
similar in nature to itself, and in fact developed from it by a process of self-

OF THE PDYTOZOA.

181

division. The result of these considerations led Ehrenherg to perceive the
true homology between the spheres of Volvox and the four-sided tablets of
Oonium.

Each member of the colony, he added, has an individuality of its own, and
to aU appearance resembles an ordinaiy simple monad, enclosed within a
lorica (a lace'nia), having a red eye- speck, a double filiform proboscis or
filament protruding from the sm-face of the common spherical lorica and
giving the hairy or ciliated appearance to it, and at the base of these filaments
a mouth, indicated by a bright, clear spot. Internally Ehrenberg believed
he discerned clear digestive cells, a contractile seminal vesicle, one or two
round sexual glands, and numerous green ova. The foUovdng history of
Volvo.v conveys the present state of information and opinion on this interest-
ing organism.

The globes of Volvox are bounded externally by a hyaline stnictureless
membrane or peUicle, which corresponds to the " envelope-cell" as understood
by Cohn (XX. 34, 45). Distributed on the inner wall or surface of this mem-
brane, is (in Cohn's words J. M. 8. 1857, p. 140) " an infinitude of very
minute hexagonal cells, attached to each other in the same way as are the
elements of an epidermic tissue" (XX. 38). The protoplasmic matter or
the endochrome of each ceU constitutes the presumed monad of Ehrenberg,
which is flask-shaped, and protrudes its tapering extremity or neck outwards,
bearing at its apex two ciliary filaments which penetrate the common envelope
and vibrate freely in the surrounding water.

The green substance composing each monadiform individual or " primordial
cell," is the usual vegetable protoplasm, and contains chlorophyll-vesicles, a
cleai" globule or nucleus, one^or rarely two contractile vesicles, and usually a
brownish-red speck, regarded by Ehrenberg as a visual organ (XX. 35) ; the
filaments are, as usual, productions from the protoplasm. Further, each green
globule is enveloped in one or more partially organized special membranes,
which are in more or less close apposition with it according to the age and
the conditions of Hfe under which the Volvoxis placed (XX. 35,37), and give
it the essential characters of a cell with a cell-wall. In the early stage of
development the several protoplasmic masses in a colony are closely aggre-
gated ; but as age advances, a clear interval surroumds and separates them,
traversed by several prolongations of the protoplasmic matter connecting
together adjoining cells (XX. 37). These processes extend oiitwards lilce so
many rays from each primordial ceU, and as a rale encounter those from sui'-
rounding cells at a determinate distance, where they meet with an external,
delicate, transparent membrane — the wall of the ceU of which the central
green globule represents the nucleus. This thin membrane forms the bound-
ary of each clear space surroimding the contained green globule ; and from
the mutual pressure of the assemblage of cells composing the Volvo.v, it
acquires, as seen from above, a hexagonal figure (XX. 38, 39-41, 45).

We have observed already that, as age advances, the space or areola around
each primordial cell increases ; that is, the external cell- wall becomes fui'ther
detached from the contained protoplasmic mass, and hence the processes con-
necting the two — at first, and even for some considerable time during active
nutrition, thick, clumsy, and irregular (XX. 42, 43) — become gradually
stretched, until they are eventually converted into attenuated threads or
almost imperceptible lines. In fact, by over-distension of the coUs from
any cause, whether, as commonly happens, from advancing age, or from the
breaking up of the globe, those cords get raptured, and then, by retracting
themselves from the outer delicate cell-wall, coalesce mth the protoplasmic
<;entral mass. On comparing this stractiu-e with that of Ooninm as recorded

182

GENERAL HI8T0ET OF THE INFUSORIA.

by Cohn, a close homology is perceptible. In this plant the membrane sui--
rounding the hexagonal primordial colls gives off from each angle a tubular
process, which comes iato intimate apposition at its extremity with that from
an adjoining cell. However, between these processes of Gonium and those of
Volvox, there is this difference, that ia the former it is only the primordial
membrane which is di-awn out to form a canal or tubule, whilst in the latter
the protoplasm itself is at fii'st extended with its membrane, and subsequently
collapses into a delicate band.

The cii'cular contractile vesicle noticed by Ehrenberg has had its existence
confirmed by Mr. Busk iu mature cells {T. M. S. 1852, p. 35) : — " It may be
situated ra any part of the zoospore (XX. 35), not unfrequently in the base,
or even in the midst of one or other of the bands of protoplasm connecting it
with its neighboiu's ; it is pretty uniform iu size, and about 1- 9000th of an
inch in diameter." Its most curious property is its rhythmical contractility,
its pulsations occurring very regularly at intei-vals of about 38" to 41". The
contraction is rapid, whilst the dilatation is gradual." The vesicle " would
seem to exist, or at all events to present a contractile property only for a
limited period, and to disappear soon after the formation of the brown spot,"
i. e. the eye-speck. The coloured eye-speck or stigma lies close against
the primordial- cell wall, it is not invariably present, and consequently cannot
be esteemed of essential importance as a characteristic.

The wall of a Volvox has an appreciable thiclmess, represented by a vertical
section — ia fact by the depth of the cells, which are placed side by side, the
lines of junction being straight and perpendicular to the external surface of
the globe (XX. 36). The inner sides of the cells, bounding the internal cavity
of the globe, are somewhat convex, the result of mutual lateral pressure, and
the absence of centrifugal pressure. Prof. Williamson has well displayed
this by sectional diagrams taken from his preparations. These sectional views
also demonstrate the position of the roimded masses of green protoplasm —
the primordial sacs — to be immediately on the inside of the peripheral mem-
brane or envelope-cell of the Volvox (XX. 37, 38).

Development of Volvox. — Self-division of the primordial cells, or zoospores
(Busk), of Volvox is regulated by the same laws that prevail in other Volvo-
cinece and in other unicellular Algae in general. Among the yoimger speci-
mens of Volvox, one or more larger globules are observable (XX. 42-44), which,
if watched, wUl be found to undergo segmentation, fii'st into two (XX. 42),
then into four portions (XX. 43), and so on (XX. 46), always keeping to the
power of two and its multiples, until some hundreds of minute corpuscles are
developed (XX. 47), which, according to the nature of the genus, so dispose
themselves in a lamina as to enclose a hoUow spherical space, and to assume
the characteristic globular form. Thus a new Volvox is generated, but differ-
ing from mature forms in the contiguity of its component indi\-iduals, — a differ-
ence, however, which progressively vanishes with advancing age. The young
globe lies immediately within the parent beiag, to which for a time it adlicres,
as it would seem, by means of a delicate capsular membrane, within which
its development has proceeded. This indeed forms its solo bond of union with
the common envelope of the pai'cnt Volvox (XX. 33).

When first formed, the cilia of the primorchal cells do not penetrate through
the external envelope of the young globe : however, this condition is of short
duration ; for no sooner is the detachment from tlic wall of the parent about to
supei-vene, than the cilia protnide externally, and, commencing their A-ibratUe
movements, soon sot the newly-developed colony in motion -within the canity
of its parent. The detachment is consequent on the ruptiu'c of the investing
capsule, caused, no doubt, by the constantly enlarging bulk of the young

or THE I'Ui'TOZOA.

183

Constantly several young colonics are developed from the parent

at"the same time, or nearly so, by tlie self-fission of various primordial cells ;
hence, as a ride, a brood of young globes is to be seen revolving within the
parent sphere (XX. 33), from which ere long it is released by its rupture.

The condition of the individual cells of a yoimg Volvox has akeady been
mentioned, — viz. their close apposition at first, their gradual separation by an
interval, the appearance of radiating processes from the protoplasm, and their
progressive attenuation. To this account we may add that contiguous inter-
ciirrent processes, in their earlier stages, appear to coalesce, — a circumstance
which indicates that the protoplasm is then imenclosed by a peUicle or envelope.
Again, the protoplasm gradually contracts itself into its flask-shape, the retrac-
tion and coalescence of its processes being a simultaneous phenomenon ; indeed
contraction of the protoplasmic globules advances continuously until, as in old
specimens, only a small rounded mass appears in the centre of a large clear
space. Lastly, the coloured stigma is an after-production ; and its advent
would seem to indicate the maturity of the cell.

Analogy with other Volvodnece would lead us to look for a quiescent or
" still " stage of the cells of Volvox, and the formation of microgonidia, in
addition to the process described, viz. multiplication by self-division with
the production of macrogonidia. That a " stiU " form actually occurs is
pretty clearly shown by Mr. Busk's observations of Volvox aureus, from
which this presumed species appears to be nothing more than Volvox glo-
bator, having a vaaying number of its cells encysted to form the winter or
" resting " spores. The primordial cells which are to undergo this change
are at first indistinguishable from the ordinary ones, except in having a
deeper green colour (Busk, op. cit. p. 38). AfterAvards, however, they ac-
quire a thick wall, change to a yellow colour (hence the appellation aureus,
golden or yellow), without material alteration of size, and produce a second
equally firm and distinct envelope ; or rather, it may be, the original cells
contract somewhat, and then form a second coat around themselves. Even-
tually a considerable space exists between these two coats, occupied by a
cleai" and apparently aqueous fluid ; but upon the addition of a solution of
iodine, a granular cloudiness is produced in it. The contents of the inner
cell consist chiefly of amylaceous grains, mixed with a greenish material in
the one case, and with a bright yeUow, apparently oily fluid in the other.
The amylaceous particles are of an irregular botryoidal form, and far from
uniform in size.

Mr. Currey, in a recent interesting commimication on fresh-water Algse
(/. M. S. 1858, p. 208), states that he has seen " one of the large, orange-
coloured spores of the so-called V. aureus, which is only the resting form of
V. fjlohator, where the contents divided into five globidar colomiess cells
which floated in a mass of reddish plasma, being apparently the remains of
so much of the original contents of the cell as had not been absorbed in the
formation of the secondary ccUs."

Of the Volvox stellatus, Mr. Busk adds that it seems to him merely a modi-
fication of V. aureus, and appears to follow the same course of change, and
doubtless of future development. With those conclusions Prof. Williamson
coincides, and remarks (op. cit. p. 56) that " the ordinary power of gemma-
tion in V. stellatus appears to have worn itself out, since, though the gemmije
often exist with the spores (?), they are small, colom-less, and abortive "

It must also be mentioned that Perty suggests an analogous interpretation
of the nature of Volvox aureus, and doubts hkewise the specific imuortancG
of V. stellatus. ^

Since the above remarks were penned, Cohn's researches on Volvox ghbator

184

GENEEAL HISTOBY OF THE 1KFU80EIA.

have determined the reality of another mode of reproduction besides fission,
as surmised (Ann. Sc. Nat. and Comptes Rendus, 1856). The abstract of

this most interesting paper is translated in the J. M. S. 1857, p. 149 : <' The

second mode of reproduction of Volvox requires a sexual conjunction, and is
not obsei-ved indifferently in all individuals. The spherules endowed with
the sexual function are distinguished by theii" vohmie and the more consi-
derable number of their component utricles : they are generally monoecious ;
that is to say, they enclose at the same time male and female cells, although
the majority of their contents are neuter. The female cells soon exceed their
neighbour's in si^e, assume a deeper green colour, and become elongated like
a matrass towards the centre of the Volvox. The endochrome of these cells
does not undergo fission. In other cells, on the contrary, which acquire the
size and form of the female cells, the green plasma may be seen to divide
symmetrically into an infinity of very minute particles, or linear corpuscles,
associated into discoid bundles. These are furnished with vibratile cUia, and
oscillate at fii'st slowly in their prism ; but the movement soon becomes more
active, and the bundles speedily break up into their constituent elements.
The free corpuscles are very agile, and it is impossible to regard them as any-
thing but true spermatozoids ; they are linear and thickened at the posterior
extremity ; two long ciha are placed behind their middle, and the rostrum,
which is curved like the neck of a swan, possesses sufficient contractility to
execute the most varied movements. These spermatozoids, so soon as they
are they are able to disperse themselves ia the cavity of the Volvox, quickly
crowd around the female cells, into which they eventually penetrate ; arrived
there, they attach themselves by the beak to the plastic globule, destined in
each cell to form a spore, and with which they are gradually incorporated.
Fecimdation having been thus effected, the reproductive globule becomes enve-
loped successively by an integument exhibiting conical pointed eminences, and
by an interior smooth membrane ; the chlorophyll which it contained is now
replaced by starch grains, and a red or orange- coloured oil. This is the con-
dition of the spore at maturity ; and occasionally forty of these bodies may be
counted in a single globe of Volvox. The germination of these reproductive
bodies has not yet been observed, so that theu- history cannot be regarded as
complete ; but from analogy it may in the meanwhile be assumed that they
germinate in the same way as do the spores of (Edogonium, Spliceroplea, and
other Algae belonging to the same order. It may be maintained, moreover,
as certain that the S]}hcerosira volvox, Ehr., is nothing else than a monoecious
Volvox glohator ; that his Volvox stellatus is also V. glohator, observed at the
time when it is filled with stellate spores ; and lastly, that his V. aureus
differs from the other forms of the same species, simply in the smooth [and
coloured] condition of the spores."

FAMILY IV.— YIBRIONIA.
(Plato XVIII. 57 to 69.)

This family follows, in Ehrenborg's system, the Volvocinea ; yet, by reason
of the extreme simplicity of stracture of the beings composing it, it should, in
any attempted natm-al system, be placed even below the Momdina.

The distinguished author of the Infusionsthierchen attributed an animal
nature to the Vihrionia, and although obhged to confess his inability to detect
any internal organization, nevertheless argued, from analogy, that a polygas-
tric structure was to be presumed, and that their movements were voluntary,
and of themselves sufficient proof of animality. In Bacterium trihculare,
indeed, Ehrenberg believed he saw an internal granular ova-mass, a \'ibratile

OF THE PHYTOZOA.

185

filament, and spontaneous fission. Of the Vihrionia generally, lie stated that
they were unable to change the form of theii- body, although without lorica,
and that by imperfect self-division they formed chains or concatenated fila-
ments, which in Sjjirillum, from the obliquity of the junction-surfaces of the
component Vibrios, assume a spiral form.

Various later writers, among whom are Leuclvhart, Cohn, and Burnett,
would transfer the Vihrionia to the vegetable kingdom. The last-named
author contributed a valuable paper to the American Association in 1850 ;
but the most recent examination of the nature and structure of the beings in
question is from the able pen of Dr. Cohn (Entw.). We must also mention
that Perty has given considerable attention to the Vihrionia, and contributed
some original obsei-vations. It is to Cohn's account, however, that we shall
chiefly resort in our attempt to describe the minute and curious members of
this family, which, if not rich ia genera, is imsurpassed by any in the abun-
dance and diffusion of its members.

Some naturalists have considered the Vihrionia to be the active agents in
producing putrefaction, since they are invariably found in decomposing fluids,
just as the yeast-plant (Torula) always occurs in fermenting saccharine mat-
ters and appears to excite the process of fermentation.

The Vihrionia are for the most part colourless ; under certain conditions,
however, they assume a yellow, red, or a blue tint, but never a green colour.
Their movements, says Perty, are rapid and energetic, so much so that the
corpuscles of Hysginum nivale, although at least one thousand times larger,
are thrust aside by Bacterium Termo when in motion. They can advance
with either end forward with equal facihty, and mostly seem, after proceed-
ing a certain distance, to retrace their course to the point they started from.

The extreme minuteness of some Vihrionia may be conceived from the
statement of Perty , that, according to liis calculation, four thousand millions
occupy no more space than one cubic hne.

Dujardin, who retains the Vihrionia among animalcules, makes the follow-
ing remarks : — " The Vihrionia are the first Infusoria which present them-
selves ia all infusions, and which from their extreme smallness, and the im-
perfection of our means of observation, must be considered the most simple ;

for it is only their more or less active movements which lead to their

being regarded as animals at aU. I have been sometimes induced to believe
that there is a flagelliform filament, analogous to that of monads, or rather
perhaps a spiral undulating one, which produces the peculiar mode of loco-
motion. Is the Bacterium triloculare, described by Ehrenberg as having a
proboscis, a true Vihiio ?

" AU that can be with certainty predicated respecting their organization is
that they are contractile, and propagate by spontaneous fission, often imper-
fect in character, and hence give rise to chains of greater or less length."

Cohn modestly premises {Entw. p. 118) that his researches have been di-
rected chiefly to one species ; yet, from scattered observations, and from pre-
sumptive evidence, he would assign a vegetable nature to aU the species.

In decomposing infusions, often after a few hom-s, extremely minute
corpuscles may be seen in countless mmiber, having the figiu'o of a dot or
comma, or of veiy delicate lines with the ends somewhat thickened. Their
motion is tolerably active, darting liither and thither, contorting themselves
at the same time by a rotating movement upon their long axis, and, when in
masses, produce the appearance of a ceaseless swarming, in which the indi-
vidual specks are easily overlooked on account of theu- smallness Thov
however, differ in size among themselves, varying from 1-2000 to 1 VoO'" in
length. Ehrenberg attributed to this world-wide form the name of Ft6no

186

GENEEAL mSTOHY OF THE rNFUSOIlIA.

lineola, whilst Dujardin more correctly separated it fi-om the Vibrios under
the name of Bacterium Ternio. Under this latter appellation Perty has also
described it.

Now when we come to examine an infusion rich ia these organisms, nu-
merous jelly-like coloiu'less masses of different size and figure (XVIII. 69)
may be met with on the walls of the vessel, and on the surface of the fluid.
These when young resemble small balls, from 1-100"' and less in diameter ;
but as they continue constantly to enlarge, they aequii-e a clustered outline,
and exhibit themselves as colourless masses and films of very considerable
superficial dimensions and thickness, resembling soft Palmells in consistence.
Like these they are composed of a transparent mucus, ia which numberless
punctate or linear corpuscles are imbedded. These last are identical with
the isolated particles known as Bacterium Ternw. That these corpuscles are
held together by the common mucus, is evident to the eye ; even the largest
films are also composed of globular clusters agglomerated together, the out-
line of the gelatinous mass appearing sharply defined in the water. More-
over, the linear corpuscles appear more thickly congregated at the periphery
than in the centre of the spherical collections ; but this is an optical delusion.
Again, when colouring matter is added to the water, the Bacterium-mucus is
not tinged by it ; and when any passing Infusorium impinges against it, its
surface is pressed in ; and lastly, the absence of an independent and inherent
molecular motion among the particles show them to be enclosed within a re-
sistant medium. Frequently, whilst under observation, single corpuscles may
be seen to detach themselves and swim away in the characteristic manner.

The definite outline and figure of the mucilaginous globules, and of their
clusters, refute the notion that such are merely collections of dead Bacterium-
corpuscles. The indication is rather that the Palmella-Yike masses represent
the young condition of Bacterium ; indeed, the same cycle of development
proceeds as in Palmella, Tetrasjpora, and allied forms .... The only difference
betwixt the Bacterium-he&^s and Palmella- or Tetraspora-maases is, that in
the first the individual corpuscles are so minute that the characters of simple
cells cannot confidently be assigned them, and that, instead of being yeUow
or light green, they are quite colourless. Nevertheless, in Kiitzing's Palmella
Brehissonii and P. hyalina, the ceUs are only 1-3000 to 1-1000"' in length,
whilst their figure and distribution are indistinguishable fi'om Bacterium. The
absence of colour is a feature of the Fungi connected with their occurrence
in decomposing infusions ; yet Palmella hyalina has only a pale ochreous hue,
and Cohn seems to satisfactoiily establish that the mere presence or absence
of coloiu" cannot constitute that decisive character which the separation of
the microscopic Fungi from the Algte implies.

From the above it appears evident that the corpuscles knoAvn as Bacterium
Termo are the swarm-cells (zoospores) of a plant allied to Palmella and Te-
traspora, but referable, by reason of the want of colour, to the microscopical
aquatic Fungi. When these Vibrios pass into a state of rest, they accumu-
late on the surface of the water in the form of films,- &c., as do the resting-
spores of Tetraspora, Sticjeoclinium, Conferva, and other Algae, but, imlike
these, are connected together by an intercellular substance, within which
their growth proceeds, and leads frequently, as Perty has illustrated, to their
disposal in linear branching series.

From the analogy with Tetraspora and the other swarm-ccUs of Algae and
Fimgi, it must be assumed that the Bacterium-coT\)u?,(Acs move by means of
a vibratUe fibre ; indeed Ehrenbcrg intimates ha\ang seen a filament in
Bacterium triloculare, and Dujardin considered some such mechanism pro-
bable.

OF THE PHYTOZOA.

187

The growth of the mucous balls is the consequence of the constantly re-
peated transverse fission of the Bacierium-hodies, and is exceedingly rapid.
Von Flotow seems to have detected the compound masses, and named one
such Microhaloa teres ; but Cohn finds it necessary to create a new genus,
which he has named Zooglcea.

Of the remaining Vihrios, Cohn has not as yet complete researches ; yet he
finds sufficient support fi-om analogy to warrant him in assuming a like history
for them as for Zooylcea. The larger forms of Vibrio have (he says) a striking
affinity with the Oscillarice, whilst the longer, slowly-moving species have a
very great likeness to the shorter fibres of Hygrocrocis, from which, some have
stated, Vihnos derived their origin. The affinity of Vibrio with the colour-
less Oscillarice — with the genus Beggiatoa, in which also very delicate forms
occui- — may be especially pointed out ; but this affinity is yet more striking
with Siyirillihm and Sjnrochceta, the other two genera of Vibrionia. Further,
in Oscillariese we meet with straight species, e. g. Oscillaria, and spii'ally
convoluted foiTQS, e. g. Spirulina, just as we have straight forms in Vibrio,
and spirally-twisted ones in Spirillum and Sjpirochceta. Likewise, on com-
paring the movements of Spirochceta with those of Spirulina, we find no dis-
tinction between them except in energy and liveliness.

The results of his examination of Vibrionia are thus summarily stated by
Cohn (p. 130) :—

" 1. The Vibrionia apparently all belong to the vegetable kingdom ; for they
exhibit an intimate affinity with undoubted Algae.

" 2. By reason of their want of colour, and their occiuTence in decomposing
infusions, the Vibrionia belong to the group of aquatic fungi {Mycophyceoe).'"
Cohn, however, shows good reason for not admitting this as a natural group
distinct from Algee.

" 3. Bacterium Termo is the motile swarming-phase of a genus, Zooglcea,
allied with Palmella and Tetraspora.

" 4. Spirochceta plicatilis belongs to the genus SpiruUna, of which it must
be at once admitted as a species {SpiruUna plicatilis).

" 5. The long Vibrios which do not coil ( Vibrio Bacillus) ai-range them-
selves with the more delicate forms of Beggiatoa (Oscillaria).

" 6. The shorter Vibrios and Spirilla; resemble indeed, in form and charac-
ter of motion, the Oscillaria} and Spirulince ; nevertheless I cannot positively
decide on their true nature."

To this abstract of Cohn's paper on Vibrionia we must add a notice of
Dr. Burnett's essay, which is equally in favour of their plant-like natiire.
The chief observations and opinions of Dr. Burnett are — that a branchin"- of
the chains, similar to that of the ordinaiy forms of Alg£e, is observable in
Vibrionia, particularly in Spirillum; that, on watching theii- graduid "'rowtli
the smaller seem no other than the younger forms of larger species (for in-
stance, that Vibrio is the fii'st condition under which Bacterium and Spi-
rillum appear) ; thatbesides self- division, propagation is effected by buddino-,
a fact further exemplified by the occui-rcnee of ramifications ; and that in
young forms a nucleus is absent, although one becomes appju-cnt in advanced
Btages. Again, as to the movements of Vibrionia, Dr. Burnett can sec no
fni-thcr indication of movement in them than in spermatozoa and in vc"-ct'iblo
cells, like which thoy are unaflccted by electrical shocks, which are fatal to
the lower foms of animal Ufe.

" Their ccU-stnicture and their vital (not voluntary) motion would then
lead us to mfer that the Vbnoma are Algous plants, and not animals This
throws hght on several common phenomena. One in particular is, that the
Vhrwma shoidd abnost invariably be found in infusions and liquids that

188

GENERAL HISTOEY OF THE INFUSOBIA.

contain other Algse, and especially tte common Torula; for I do not re-
member to have seen the Torula without Vibrionia."

Perty moreover testifies to Vibrio Bacillus assuming a still condition, and
by its branching concatenation, a plant-like fonn, out of which are constructed
masses and films in the infusion and upon its surface, resembling Hygro-
crocis and other Algae and aquatic Fungi.

Dr. Ayres (J. M. S. i. p. 301) contributes the following observations on
the self-division of the Vibrionia : — " While," he writes, " the shortest of the
Vibriones were in active motion, the longer ones were comparatively quies-
cent ; and these exhibited, according to their length, from one to six trans-
verse lines, indicating the points of separation in the reproductive process.
Those of moderate length, presenting only one or two transverse lines, were
rather active, and often bent at an angle at the transverse lines, which pre-
sented the appearance of separation into two distinct individuals ; and the
character of the movements appeared such as to favour the separation. Those
with from three to six transverse lines were, for the most part, quiescent.
I imagined, although from their excessive minuteness and transparency this
was not plainly and unequivocally discernible, that there were indentations
of the extremities of the transverse lines, by which constrictions were pro-
duced, which, by their increase, would finally effect a complete transverse
division of the animals."

The occurrence of Vibrios, or at least of Vibrio-^jike forms, as one of the
metamorphic phases of the Phytozoa of the antheridia of Characece, e.g.
Marchantia, has been mentioned in a foregoing page (126), to which we
must refer our readers.

FAMILY v.— ASTASL^A OE EUGLEN^.
(Plate XVIII. 36—50, 52, 53, 55, 56.)

Dujardin very properly prefers to call this group Eiiglenoea (Eugleniens), on
account of the resemblance in sound of the first name with that of Astacicea
(Astaciens) used to designate a family of the higher Crustacea.

In Ehrenberg's system it constituted a family of the Polygastrica, and was
characterized by wanting a true alimentary canal, a lorica and appendages,
and by having a mouth surmounted by one or two proboscides, and in most
species by a changeable form. Internally, digestive sacs, ova, a seminal gland,
and contractile vesicle, and in most genera one or more red specks or eyes,
were represented as present. The genera included were — Astasia, Ambly-
ojohis, Euglena, Chlorogonium, Colacium, and Distigma. The value of these
genera has been called in question by various ■writers. Dujardin makes the
variability of form — ^in other words, a contractile integument — a leading fea-
ture, and rejects the eye-speck as neither distinctive nor constant ; conse-
quently he excludes from the family the Euglenai with rigid integument,
and transplants them to the Thecamonadina, and rearranges the remaining
species according to the number, disposition, and character of their locomo-
tive filaments. Likewise Schneider (A. N. H. 1854, xiv. p. 327) separates
Chlorogonium from the Astasiaia because of its unchangeable figure ; and
Mr. Carter {A. N. H. 1856, xvui. p. 116) would also detach Astasia from Eu-
glena, from the conviction that the former has an animal organization, and
that the latter is referable to plants.

In the foUowing general history of the Astasicea, our description will
chiefly apply to the two genera Astasia and Bhiglena, respecting which we
have very copious details in the papers by Mr. Carter, (A. N. H. 1856, xviii.).

OF THE PHYTOZOA.

189

Of the remaining genera, some comparative observations will be made in pass-
ing, and particular researches respecting them added from Perty and other
inquirers.

Euglence and Astasice are mostly spindle-shaped (fusiform), and give off
from their anterior extremity one or two delicate filaments, and posteriorly
a usually short blunt tail. Excluding the doubtful Euglenece, which, on
account of their rigid integument, we think, with Dujardiu, should be
transferred to another family, the remaining species of the two genera
in question are, from their inherent contractility, capable of varying their
form to a remarkable ext«nt; i.e., to use a technical word, they are " meta-
bolic" This property is, nevertheless, much more restricted than in the
Amcebce ; for the Astasicea can send off no offshoots or variable processes
like those animalcules, but in all their manifold contortions, elongations,
and contractions do not completely lose theii- primitive figure. In general,
the recurrence of the changes of figure is quite arbitrary and without regu-
larity. In Ehxtreptia viridis and Astasia margaritifera, however, Perty
represents an alternate or peristaltic expansion and contraction of the or-
ganism, so that first the anterior and then the posterior extremity expands.
He adds, besides, that in this Astasia the contained clear globules are not
transferred backwards and forwards, but only a fluid matter which runs in
channels between them.

The Astasicta are covered by a distinct flexible and elastic envelope,
which Ml'. Carter calls the " peUicle," and states that it resembles the cover-
ing of Amcebce, is structureless, and hardens after secretion. Stein also
affiims that in Euglena it is similar to the enclosing membrane of Qregarina,
and, like it, a shut sac without mouth or other apertiire. On the contrary,
the translator of KoUiker's paper on Actinophrys (J. M. S, i. p. 100, note)
denies the existence of a distinct envelope to this genus. Beneath the
peUicle, adds Mr. Carter, is a transparent moving substance, with an inhe-
rent property of contractility and polymorphism, which proves itself inde-
pendent of the superposed pelKcle when, in the process of encysting, the two
become separated; this substance is the " cliaphane."

Enclosed within these laminae are the contents, consisting of a proto-
plasmic matter with suspended particles and certain definite structures, viz.
a nucleus and contractile vesicle (XVIII. 46 a, c). The protoplasm is the
same matter Dujardin names the " sarcode," and is occupied with a vai'ying
quantity of corpuscles, differing among themselves in size, and imparting the
colour peculiar to the species.

" In Euglena," writes Mr. Carter (op. clt. p. 119), " the sarcode is separated
from the diaphane by a layer of pointed sigmoid fibres, arranged parallel to
each other, so as to form in Grumenula texta (Duj.) a conical ccU, which so
soon as the ovules have become developed, and the diaphane and other con-
tents of the sarcode have died off, becomes transparent, although it still
retains its conical form until tho resiliency of the fibres, now unrestrained
by the diaphane and other soft parts, causes dehiscence, and sets the ovules
at Uberty."

These fibres arc therefore the cause of tho spiral markings of several
Euglence, as well as of Phacus and Ghonemonas ; they are strongly marked
in Euglena spirogyra. " In another specimen of Euglena," says Perty (p. 67),
" of fully a sixth of a lino in length, and of a grass-green colour, some thii-ty
delicate longitudinal lines were perceptible, which, when the body tiu'ned on
itself, looked as if spirally disposed. Moreover, on examining Lepocimlis
globules when partiaUy dried, the spiral lines appear composed of rows of
closely an-anged dots "—a plienomcnon probably explicable on the supposi-

190

GENERAL HISTORY OF THE INFUSOIilA,

tion that the fibres, as a consequence of evaporation, have been broken up
into particles by the act of difiiuence.

Ml-. Carter distinguishes certain minute colomiess granules diflfused in
the general protoplasm of the interior, which he specially designates " mole-
cules." These, says this observer, are the first to appear in the homogeneous
sarcode, but afterwards become intermixed with larger corpuscles — " gra-
nules"— and with " ovules ;" and by the time the ovules have become fuUy
formed, the sarcode and its molecules have di-ied off or disappeared. " More-
over, in Astasia, digestive globules also appear ; but here the food is taken
in through a distinct mouth, while in Euglena the absence of such vesicles
would appear to indicate that its support is of a different kind, if not intro-
duced in a different way."

Ehrenberg noted the existence of a contractile vesicle at the anterior ex-
tremity of Euglena ; the Like is also seen in Astasia ; but in neither instance
have its pulsations been directly observed. A nucleus is also present of a
discoid shape, and surroimded, according to Mr. Carter, by a transparent
capsule, which appears like a naiTow peUucid ring around it, owing to its
greater size. In Chlorogonium and AmblyopMs, Ehi'enberg encountered
what he called a seminal gland, i.e. a nucleus, and, in the latter genus, men-
tions the presence of two wand-like bodies in front and three behind it.
Thirteen such peculiar structm-es were also seen by Perty in a large specimen
of Euglena spirogyra, which he concluded had originated from a pecuhar
disposition of the internal substance. The same ambiguous structures ai'e
doubtless referred to in the following paragraph by Mr. Carter, although,
indeed, structui-al peculiarities are detailed which would render Perty's ex-
planation inadmissible unless qualified in some measure (A. N. H. 1856,
xviii. p. 241) : — " With reference to the single, glairy, capsuled body which
exists in the centre of Phacus and in the large lip of Crunwnula texta, also
dually in Euglena geniculata, Duj. (Spirogyra, Ehi'.), on each side the nu-
cleus, I can state nothing further than that in the two fii'st it consists of
a discoid transparent capsule, which at an early stage appears to be filled
with a refractive, oily-looking matter ; that it is fixed in a particular posi-
tion, and remains there apparently unaltered, with the exception of becoming
nucleated, until every part of the animalcule has perished, and nothing is
left but the spii-al-fibre coat, and perhaps a few ovules. In Eughna geniculata.
it is bacilliform, and contains a correspondingly-shaped nucleus ; and al-
though I can state nothing respecting its uses, I cannot fail to see that it
has an interesting analogy, particularly in the latter instance, with two
similar organs which are commonly seen in the Navicula, and which in
N. fulva, e.g., are situated in a variable position between the nucleus and
the extremities on either side."

The numerous globules diffused throughout the body, which, in addition to
the foregoing, make up the contents of the Astasiaa, and according to
Ehrenberg are to be considered ova, have, after being denied that nature
by DujarcUn and others, been again brought to notice under the name of
ovules or germ-cells by Perty and Cai-ter. They are, in the words of the
latter observer (p. 223), nucleated cells, wliich, at an early stage, " consist of
a transparent capsule lined mth a faint yellow film of semi-transparent
matter, which subsequently becoming more opaque and yeUo-wisli, also be-
comes more marginated and distinct, and assumes a nucleolar foi-m.". . . .
" In the discoid cells of Astasia 1 have seldom been able to distinguish the
capsule from the intcrnid contents, on account of their smaUness and the
incessant motion of the animalcule. In Euglena, however, they are veiy
evident ; and it is worthy of remark, that each partakes of the form of the

OF THE PHYTOZOA.

191

Eiiglena to which it belong^. Thus, in E. acus it is long and cylindrical ; in
E. viridis, oblong and compressed ; and in Crumenula texta and Phacus, cir-
cular and compressed.

There is yet another set of structures pointed out by Mr. Carter, deve-
loped from the nucleus, to which he assigns the nature of spermatozoids,
or male reproductive particles. " In Astasia," he writes (p. 227), " irregular
botiyoidal masses, dividing up into spherical cells, colourless and translu-
cent, or of a faint opaque yellow tint, present themselves so frequently (and
generally inversely developed with the ovules, as in the Bliizopoda), that I
cannot help thinking that they are also developments from the nucleus ; but,
from not ha\dng seen them present that evident granular aspect which
characterizes this development in the BMzopoda, I have not been able to
determine satisfactoiily whether they are parts of the latter, or that kind of
division of the sarcode into green spherical cells which sometimes takes place
in Euglena.

" In Euglena, also, I have described a development of the nucleus partly
under the idea that it might be a pai'asitic Ehizopodous development ; but
now it appears to me a simple enlargement, granulation, and segmental de-
velopment of this body into polymorphic, reptant, mucous cells filled with

spermatozoid granules, as in Rliizopods I have never been able to see

the nucleus and its capsule in their original form when the spermatozoid
mass has been present, though I have occasionally in Amosba, and almost
always in Euglyplia, seen the empty globular capsule in connexion with the
latter."

The contents of Astasicea, even of the same individual, are subject to great
variations in colour, distribution, and other characters, indticed by age, the
action of the reproductive processes, and the influence of external conditions.
Thus, Perty teUs us (p. 57) Phacus pleuronectes is at times filled with a
homogeneous green mass, at others has a large, roimd, central spot (vacuole
or nucleus ?), at others a large, clear space in the middle, having a central
dark nucleus ; and at others, again, the contained endochrome forms three or
four segments, each exhibiting many dark green nuclei. In Euglena viridis
and E. Acus the contents become resolved into a formless mass, or into a
heap of nearly equal-sized germ-ceUs, and frequently the colour is changed
from green to red, or the whole organism is rendered hyaUne by the escape
of the colouring matter.

The coloured speck in Euglena, AinblyopMs, and other Astasicea, reckoned
as an eye by Ehrenberg, has in fact no pretensions to that character. "We
have pointed out that similar specks occur in Volvox and other generally
recognized plants, in all probability precisely similar to and structurally the
same as those of Astasicea. Sometimes in Euglena the red is diffused over
the entire body, as Cohn represents to occiu- in Spharoplca anmdina {A.N.IJ.
1856, xviii. p. 83), in small globules, which have the physical and chemical
relations of oil. In other instances, and occasionally in vciy yoiui"- forms
the red stigma is altogether absent. In Phacus pleuronectes, Perty states'
one speck is placed close behind another with an intermediate band uniting
them. Often in Eiglence, instead of one stigma, two or more red "-ranules
occur, whilst in Euglena deses the pigment-mass is quite irregular. In Cru-
memda the red spot is comparatively very large, and rests in the form of a
small obtuse cone upon the contractile vesicle.

" The eye-speck of Euglena viridis," says Perty (p. 117), " is round or oval
and exhibits an elliptic or spherical vesicle, within which the colouring matter
IS contained, surroimded by a more or less complete brownish-black rino- • at a
subsequent period the colouring matter is diff-used in a most irregular manner

192

GENERAL HISTORY OF THE INKUSOUIA.

beyond the i-ing." In AmblyopMs viridis the red pigment may either entii-ely
or only partially fill the dark areola. Perty very sensibly remarks, " AU
these red stigmata are deficient of all the requisites of an eye — .they have no
refracting medium ; and the presence of an eye is inconceivable among beings
which have neither nervous centres nor communicating nerves. They are
probably nothing more than drops of red-oil, like those which are produced
among the chlorophyll in unicellular Algas " (p. 118). Another fact, bearing
on the character of a red pigment-speck in Euglence, is the change of colour
these beings at times undergo from green to red, just as Chlamydococcus and
various unicellular Algae do when they enter on the " resting" stage.

Bejproduction of Astasicea. — In Ehrenberg's opinion, the members of this
family are reproduced both by self-division and by ova : he speaks of having
witnessed the former process in the genus Euglena, but only as a rare
occurrence. In other genera he failed to discover it. When fission takes
place it does so in the usual manner, longitudinally, and produces two equal
and similar organisms ; rarely, the new beings are of unequal size. More-
over, in the encysted condition, which was mistaken by Ehrenberg for the
death of the Euglena, or confounded with other structures, fission is a con-
stant phenomenon.

When the motile Euglena becomes "still," or enters into a state of rest, it
contracts itself into a ball, and, while retaining its red stigma, loses its fila-
ment. A gelatinous layer is thrown out around it, which gradually hardens
into a rigid colourless cyst : this at first lies close upon the mass of the Euglena,
but ultimately is removed from it all round by an interval ; and when quite
mature, it frequently acquires a brownish coloui* and opacity. In the encysted
condition, Euglena closely resembles the " still " cells of Protococcits ; hence
the term " Protococcoid," to express this condition. When Euglence have
undergone this transformation, they cohere together by a mucilaginous ex-
cretion, so as to form expansions or films resembling in appearance those
produced by many Palmellece.

This close resemblance subsisting between encysted Eugleiim and the rest-
ing-spores of numerous Algae, e. g. of CEdogonium, explains many of the
wonderful transformations recounted, such as the germinating of encysted
Euglena-ce)^ into branching filiform Algas. Again, the filmy masses pro-
duced by Euglence have been described as independent genera and species of
Algae, — as, for instance, those formed by E. viridis, as Microcystis olivacea,
and those by E. sanguinea, as Microcystis Noltii.

That the contained green Euglena is not dead within its case, is proved by
its sometimes being seen to revolve within it, and also by the circumstance
that, in the early period of encysting, on ruptiiring the cyst, the contained
being escapes and resumes the appearance and movements of its free brethren.
It would seem, indeed, that Euglenai are in the habit of temporaiily encysting
themselves as a means of protection against injurious external causes, such as
evaporation, and that, when a normal condition is restored, they throw off
their protecting envelope and reassume their active contractile character and
movements. The empty cases are often to be met with floating on the sur-
face of water, united with others and with encysted Euglena; in a common
membranous mass. The vitality of the enclosed being is further displayed
by the process of fission, which advances in the power of two imtil veiy small
segments are produced, which soon develope severally a red speck and fila-
ment, and, on the dissolution or rupture of the common cell-wall of the parent,
escape as small free-moving coi-pusclcs rather resembling Monads than Eu-
glence by their minuteness.

The encysting act maj' transpire in very small as well as in large EugJeno',

OP THE PHYTOZOA.

193

and the subsequent fission may be arrested at any point, so that either a few
sections which, in the phraseology of botanists, may be called macrogonidia,
or othermso very numerous small ones, or microgonidia, may be developed.

As the simply encysted Euglence have been represented as independent
genera of plants, so the same thing has occm-red when their contents have
been seen in the process of self-division ; thus, for instance, Perty thinks it
probable that Protococats twrgidus and P. chalyheus (Kiitz) are no other than
two such transitional conditions.

Another cii-cumstance attending encysted Euglenoi, is the forming an attach-
ment to other bodies by a sort of pedicle, which extrudes from what has been
the anterior extremity of the being. When viewing large collections of Eu-
glence, specimens may occur of two or several united together by the head or
tail, sometimes with the tail of one to the head of another. Examples of two
partially united have been explained by supposing the act of fission of a
parent-animal to be nearly accomplished ; but other observers have seen in
such united beings an instance of conjugation, i. e. of an act, to some degree,
of impregnation. The union, however, of several by the tail, sometimes seen,
is an argument against this supposition, and is rather suggestive that such
combinations are the remnants of primitive adhesions between gonidia within
the parent-cell or between germs before a pellicle has formed around them,
or, again, that a mucoid matter thi'own out from the siu-face, as happens in
many Phytozoa, may constitute the band of union, when incomplete fission or
persistent primitive adhesions cannot be considered its origin. There is cer-
tainly no a prior i argument against the occun'ence of conjugation in this family,
and some naturalists would, from analogy with related beings, look for it ;
but at present it has not, we think, been proved.

Ovules or germs. — That Euglence reproduce by internal germs is an opinion
now advocated by several natiiralists. To our minds this mode of propagation
is really homologous with the formation of gonidia in admitted plants. Kol-
liker writes {J. M. S. i. p. 34) — " Multiplication by means of germs generated
in the interior indubitably occurs in certain Infusoria : in Euglena fom* to six
embryos are seen in one individual, entii'ely filling it, which at length, fur-
nished with their red speck and filament, break thi'ough their parent, leaving
it as an empty case."

Mr. Carter {op. cit.) has entered very largely into an account of the ovules of
Infusoria and of their development. " In Euglena viridis," he writes, " the
ovules are of an oblong shape : they are foimd, like those of Spongilla, scattered
over the sides of the vessel, and evidently have in like manner the power of
locomotion in addition to that of tmrning upon their long axis when otherwise
stationary .... The pellucid central area in them corresponds with, the oblono-
shape of the capsule ; but beyond this and the central granule I have not
been able to foUow theii- development out of the parent, though, from the
number of young E. viridis present, it may be reasonably inferred that they
came from the ovules. The young Euglence, however, being so rapid in their
movements when once the ciUum is formed, it can hardly be expected that
except imder a state of incarceration, their development can be foUowed so
satisfactorily as that of the slow-moving Bhizopod. Instances do occiu- how-
over, where the ovules gain the cUium within the coll, and there boxmd about
when fully developed like the zoospores of Alga3 -ttitlihi theii- spore-capsules
In this way I have seen them moving rapidly within the effete transparent
capsuled body of E. viridis and in Crumenula texta, where the spiral-fibre
layer is so strongly developed as to retain thoi'qrm of the Euglena for a lonsr
time after aU the soft parts have perished. On these occasions the embryos
are perfectly colourless, with the exception of a central point which reflects a

194

QENEU.VL HISTORY OF THE INFtJSOEIA.

red tint ; and on one occasion, while watching a litter in rapid motion within
the encysted bodj^ of E. viridis, the capsule gave way, and they came out one
after another just as zoospores escape from the spore-capsule ; but, from their
incessant and vigorous movement, I was unable to follow them long enough
to make out anything more about them."

Tliis same observer, moreover, refers to a rhizopodous development of the
nucleus of Euglena, whereby the form of an " actinophorous Rhizojpod " is
assumed, from Avhich, in his opinion, young Euglence are probably developed.

Perty, again, records some original observations on the development of
Euglence from o\Tiles or, as he terms them, germs (Keime). At p. 79 he
states that, among numerous veiy minute resting genns, intermingled with
larger individuals, some were seen to acquire the faculty of motion, to stretch
themselves out, and to assiime the form of Cercomonas. Between such and
completely-formed Euglence every intermediate size occiuTed. The motionless
spheroidal germs set free by the dissolution of the parent-cell soon develope
a tapering extremity, terminated by a locomotive filament, at the base of
wliich is a hyaline space, and in and near to this a dark speck which subse-
quently changes to red. The diflferentiation of the homogeneous contents of
the granules, out of which the germs are to be developed, takes place at a very
early period, but not ia the same way or time iu all specimens ; neither do
all the young of a brood attain the same dimensions and figui-e ; indeed but
few attain a considerable size, and many acquire an abnormal figure. For
example, Perty regards Amblyophis viridis as only an accidental variety of
Euglena, of large size and tnmcate at one end ; for he has remarked numerous
small individuals, derived from a Euglena, also with a truncated extremity.
Further, he reports the multiphed varieties in form, in colour, and in arrange-
ment of contents, &c., which occur in collections of the same species of
Euglena, and adds that the great differences exhibited by E. viridis, when in a
dying condition, are most varied and inexplicable. In illustration of this
opinion, he remarks that the utmost variety of form occxu's ; or all the vesicles
and granules change to a red coloui' or become transpai'ent ; or the vesicles
vanish and the green mass contracts itself into a small ball, or otherwise dis-
appears, leaving only an empty shell. In the last-named state the stigma
often retains a black colour. The empty envelopes frequently accumulate so
as to form masses resembling a vegetable cellular tissue, and in one instance
approached, by mutual pressiu-e, a regular hexagonal figure. Some such acci-
dental groupings of withered Euglena-ceHs have been, as Perty beUevcs,
described under the name of Pahnella hotryoides by Kiitzing ; and Cercomonas
viridis, and also probably Bodo viridis, are merely phases of development of
Euglena viridis.

There is a distinct concordance between Carter's and Perty's account of
the development of the contents of Euglena; into minute germinal bodies, or,
as we may legitimately caU them, microgonidia ; and, on the other hand, the
formation of two- and four-fission products (in other words, the formation
of macrogonidia from these beings in their still-condition) has been a matter
of direct observation. Consequently the developmental history of Euglena is
so far complete ; and it only remains for naturalists to ^-itncss the actiial
relation, the contact and incorporation of tlie micro- Avith the macrogonidia,
to bring this genus within the same pale as Volvox, in reference to its
sexuality.

Mr. Carter has reverted to his notes on the ovules or germs of Euglejia, in
his j\ist-published paper on Eudorina {A. N. H. 1858, ii. p. 245), in the
following rcmarlcs : — " There is no doubt that E. viridis becomes dist<>ndod
with the cells which I have lioretofojo described, and thouglit to be oahIcs

OF THE PHYTOZOA.

195

or embryonic colls, and that diu-ing tliis time tho chlorophyll passes into red
grains, and subsequently disappears, while the organism is secreting a capsule
aroimd itself, and its original cell- wall passes into a tough spherical ovisac, so
to speak. But what becomes of this, if it be the result of impregnation, or
what the process of impregnation is like, or when it takes place, is for future
discovery to determine."

Chlorogonium euchlorwm (PI. XX. 15-21) was the subject of an interest-
ing observation by Weisse (Wiegmann's Archiv, 1848), who thought he had
demonstrated in this species propagation by ova or germs, and, in fact, elu-
cidated in it the development of microgonidia, by repeated acts of self-fission
of the contents, just as in the spores of Algae. For instance, he described the
contained green matter of the fusiform being first to contract in some mea-
sure upon itself (XX. 16), then to exhibit a constriction followed by a line
of division iuto two portions, which, by subsequent redivisions, resolved the
whole into a nodular mass resembling a bunch of grapes (XX. 17-18).
This grapebunch-like mass possessed a certain mobility within the enclosing
integument; and as the process of development proceeded further, its se-
veral particles or segments displayed a movement among themselves, which in-
creased in extent and vigour until the external envelope gave way before it,
and permitted their escape in the form of so many distinct particles or beings
(gonidia) endowed with ciliary filaments, whereby they kept up an active
movement in the surroimding water (XX. 21). The young forms produced
exhibited active movements within the parent- ceU, and at one stage prior to
their discharge, when connected together in heaps, resembled Uvella Boclo.
On the rupture of the cyst they escaped freely into the water with the figure
of CJilorogonium.

Schneider has also some remarks on this genus {A. N. H. xiv. p. 326).
He could discover no decided red speck, although as many as twelve reddish
spots were distributed over the surface of the green mass ; a contractile vesi-
cle, moreover, eluded his search. Of the mode of propagation he reports that
" division takes place in the interior of the investing membrane, in exactly
the same manner as in Polytoma. The number of individuals produced is
never less than four, but often as many as thirty-two ; in the latter case they
are very small, but always resemble the parent in other respects. A spheri-
cal state of rest also occurs. It appears that, when the requisite conditions
are present, the young proceeding from the division of the parent pass into
this state immediately after they are set free, — their soft investing mem-
brane probably rendering them fitter for this purpose. The contractions
which then take place are probably the same that were observed by Ehren-
berg. In other respects I have found the form unchangeable ; and Ghlo-
rogonium must consequently be separated from the Astasiaia, amongst which
it has hitherto been arranged. On the addition of iodine, only a few blue
granules are to be seen in the fusiform individuals ; the green spheres, on the
contrary, which are completely filled with green granules, acquire a deep blue
colour with this reagent : if the colouring-matter bo destroyed by means of
concentrated siilphuric acid, the granules are dissolved, and on the addition of
iodine, a beautiful blue colour is produced. By long keeping, the green of tho
cyst passes to red. The cysts are not to be roused from their torpid condi-
tion by the production of fermentation. I have, however, observed their re-
vivification under other circumstances ; but my materials are insufiicient to
enable me to describe the mode of reproduction of the investing membrane
and filaments, wliich would certainly be interesting. The conditions required
for the existence of Ohlorogonium are apparently quite different from those of
Polytoma: the former did not multiply abundantly in infusions until the

0 2

196

GENEEAL HISTORY OF THE INFt'SOEIA.

latter had passed to the state of repose." This view of the affinity of Chlo-
rogonium accords with that which Weisse indicates in the statement that this
genus and Glenomorum tingem (species of Elirenberg's family Monadina) are
but two phases of the same being.

Weisse has appended some remarks to the preceding account by Schneider
Miill. Archiv, 1856, p. 160). He says that he witnessed the revivification
of encysted Chlorogonia (a phasnomenon unnoticed by Schneider) on placing
some cysts, collected the preceding year, in water. The reddish and pre-
viously spherical cysts were seen to gradually lose their regular outline by
the elongation of one end, and thereby to acquire an. ovate form. After a
short time the narrower end of the cyst ruptured, and a very thin-waUed
vesicle protruded through the rent : whilst this took place, a movement of
the contents of the cyst became evident ; and after a while several constric-
tions appeared, which extended deeper until they divided the whole into four
portions. For a time the protniding sac elongated itself more and more, but
ultimately, owing to the pressure within it of the moving particles, gave way
and allowed their exit. The escaped sections were, as a rule, of pretty uniform
sizes, but had not the remotest resemblance to the matiu'e C'hlorogonium, and
indeed might have readily been assigned to another group of beings. Their
figure was elongated, irregular, and often triangular, on fii'st escaping from
the cyst ; they were also flexible in every dii-ection, and of a dusky brown
coloui\ After dispersion, on reaching the margin of the drop of water, they re-
sumed a globular shape, changed to a rusty red coloiu', and after a few hours
assumed the appearance of cleai'-green spindle or bodo-shaped organisms.
Between their evolution from the cysts and their development into the form
of Clilorogonium, two hours, less or more, intervened. This division into four
segments, representing foiir new beings of Clilorogonium progressively evolved,
apparently without actual metamorphosis, may be rightly esteemed an act of
reproduction by macrogonidia, whUst the breaking up of the organism into a
multitude of zoospores, as previously described by "Weisse, is a process of re-
production by microgonidia.

Natttre or AsTAsi^A. — It is vsdth certain members of this family that
Thuret pointed out {Ann. Sc. Nat. 1850, xiv.) the close resemblance to the
zoospores of Algae, amounting, as far as outward appearances indicate, to
actual identity.

"This affinity," he says, "is exhibited in the colour, form, in the number and
character of the ciliaiy filaments, in the contents, not excepting the colom-ed
eye-speck, in the mode of self-fission, and also in the power of locomotion.
What is stiU more, both zoospores and Astasicea tend to the light, disengage
a gas, most probably oxygen, and emit a peculiar spermatic odour. However,
by continued watching the zoospores are seen to affix themselves to some body,
surrender their seeming animal Hfe, and proceed to germinate, developing a
tissue similar to that of the plant which gave them birth. On the other hand,
the true Astasicea, if they attach themselves, it is but for a time, and no ap-
pearance of germination ensues. The closest similarity exists in the case of
the Ghlamydomonas pidviscul.us (Diselmis viridis, Duj.), and in a less degree

in the Eugleno} In the form of the body, in that of the flabeUiform ciha,

and in the disposition of those ciHa, as also in the contents of the body,
the resemblance is complete. The movements of Diselmis are like those of
zoospores ; and, like them, they tend to the light. In one distinct species, or
rather, in a particular state of the same specie^i, a very clear red spot is dis-
cernible, and a central globule, very like in appearance to the amylaceous
granules so frequent in the colls of green Algro. These Infusoria appear to
act on the atmospheric air like Alga> and the green parts of other plants, dis-

OP THE raYTOZOA.

197

engaging a gas (oxygen ?) under the influence of light. They exhale an evi-
dent spermatic odour. Their reproduction occm-s by spontaneous division,
2-4 yonng ones being formed within the common integument. I have ob-
served the same mode of reproduction in the Euglence, which act on the air
and turn to the light like Disehnis, but have an extremely contractile body
changing its figure every moment, which wUl not admit of their being con-
founded with zoospores, and leaves no doubt of theii- animality. This binary
or quatemaiy division is met with also in the various species of Tetrasporm,
which, though an-anged with the Algae, appear to me of very doubtful vege-
table nature. In Tctraspora gelatmosa I have recognized green globules, dis-
posed in fours, and each fiu-nished with two cilia of extreme length, which
are lost in the gelatinous mucus of which the frond of this supposed plant is
constituted. All these productions, as well as Gonium, Pandorina, Volvox,
Protococciis nivalis, &c., present, in my opinion, characters of animaUty
too decided and too permanent for it to be possible to refer them to the
vegetable kingdom ; and I think it would prove more convenient to
unite them, with all the other Infusoria {Polygastnca) coloured green, in
one and the same group, which might be called Chlorozoidece. We have
before noticed the sweeping statement of M. Agassiz, that all the mouth-
less Infusoria are nothing but various forms and phases of development of
Algffi."

Although many naturalists stoutly claim the Astasicea, and the genus Eu-
glena especially, as plants, yet others, and among them some of the most
able, particularly in Germany, stiK pronounce them animals. But, as we
have before noticed, there are undoubted Euglena-fovma which are actually
phases of existence of known plants, and Avhich, if watched, may be followed
in their development until by germination they assume aU the special fea-
tures of those plants ; and, on the other hand, there are Euglence which at no
period of their existence can be seen to germinate, although they may exhibit
a plant-Eke condition when encysted and motionless, like Protococcics resting-
ceUs.

As an example of the former set of transitional beings, we may appeal to
the observations of Itzigsohn ali'eady recorded (p. 125), showing that, in the
development of Oscillatorice, minute Chlamydomonads are ti'ansformed into
Eiiglence, that these in their turn generate microgonidia, which, after some in-
termediate transformations, eventually produce the ' Leptoilmx,' and lastly
the perfect Oscillatoria. Another illustration might be adduced from Cohn's
essay on Protococciis pluvialis, in which he points out both an Astasia- and a
Euglena-hke phase of that unicellular plant. Let it, however, be noted that
whilst Cohn records a Euglena-])hase in Protococciis, he nevertheless admits
the existence of animal Euglence, distinguished by their extraordinary con-
tractihty {Entiv. p. 208). Withal, this distinguished observer's discovery of
the mutual sexual relation of micro- and of macrogonicHa constitutes (sup-
posing these reproductive products, as seems to be actually the case, to be
generated in Euglenai) an additional argument for their vegetable nature, by
bringing them within the same categoiy of organized beings as Volvox and
Pamlorina.

K Mr. Carter be correct in his account of Astasia, this genus can no longer
remain in the category of doubtful organisms, but must forthwith be trans-
ferred to the animal Idngdom ; for he asserts the existence of a mouth with
a complicated buccal apparatus for biting off and taking in food, of a strong
prehensile organ, and stomach-sacs. Besides, he speaks of its near afiinity
%vith Amoeba, and refers it to the Bhizopoda. In Euglena, on the contraiy, no
mouth- or stomach-vesicles are discoverable, and the filament is comparatively

198

GENERAL HISTOHT OF THE INFUSOBIA.

imperfectly developed ; hence Mr. Carter allies this genus rather with, the
zoospores or gonidia of Algte, and assumes that it must, like other mouthless
organisms, derive its nutrition through endosmosis. Cohn, on the other
hand, although cognizant of many plant-like featui-es in Euglena, cannot ac-
qiuesce in detaching it from animalcules, because of its great contractility
and of the fact that there are undoubted animals, such as Opalina, BJdzopoda,
Gregarina, Trematoda, &c., which want the special animal characteristic of a
mouth.

Ml'. Carter would, it seems, recognize both Euglena and Astasia as close allies
with Amoeba, — an afiinity remarked by Ehrenberg, who placed the family As-
tasicBa between Glosterina and Amoebcea, treating the variability of the form of
the body as a leading characteristic. Indeed, the first-named observer alludes to
an actual transition of Astasice into Amcebce, in the following paragraph (A.
N. H, xvii. 1856, p. 115) : — " Young Astasice are developed within the cells
of Spirogyra to a great extent ; and although they at first have almost as
much polymorphism as an Amoeba, stiD. they retain their cilium, and after a
while assume the form and movements peculiar to Astasia. I might here
mention that on one occasion I saw a large Amoeba with a long cilium at one
time assuming the form of Astasia, and at another that of Amceba, which thus
gives us the link between these two Infusoria. The cilium, however, had not
the power of the filament of Astasia, though it occasionally became tenninal."
At a previous page, a rhizopodous development of the contents of Euglena;
into granidiferous ATnwbce of a pinkish colour has been adduced as a fact
noticed by the same observer.

We need not stay to examine the vital endowments and habitats of the
Astasice ; for, except the facts occurring in the preceding history of the family,
and in the general account of Phytozoa, there is nothing important to adduce.

OF TIU5 PROTOZOA.

199

Sect. III.— OF THE PROTOZOA.
(Plates XXI.-XXXI.)

The term Protozoa, borrowed from two Greek words, protos, first or primi-
tive, and zoon, an animal, has of late been very generally adopted to signify
the simplest forms of animal life. Upon a review of these rudimentary
animals, it is at once perceived that they differ among themselves' in organiza-
tion— that whilst some ai-e amorphous and almost homogeneous, others exhibit
a degree of differentiation of parts, and the first vestiges of internal organs to
carry on the processes of hfe ; again, it is seen that some have a distinct oiiflce
for the admission of food, or a mouth, which in others is absent, and, lastly,
that some with a definite figui'e are moved by vibratile cilia, whilst others
slowly progress by the alternate protrusion and retraction of ever-changing
and changeable processes derived from the general mass of their body.

From a consideration of these stnictural' differences, one division of the
Protozoa is suggested into those moved by cilia, and those moved by variable
processes or 'pseudocodes ' ; and a second, into those furnished with a mouth,
and those which are mouthless. We have accordingly constituted tAvo pri-
mary divisions, viz., 1. Ciliata, Protozoa moved by ciUa ; and 2. Bhizopoda,
moved by variable processes. The Bhizopoda (XXI.) are aU mouthless, or
' astomatous,' whilst the Ciliata (XXIV.-XXX.) have a mouth, and are
styled by Siebold ' Stomatoda,' with the exception of a small family, the
Opalincea (XXII. 46, 47), and perhaps also of that of the Peridinicea
(XXXI. 16-23).

However, besides the beings usually included among the Ciliata axiA Bhizo-
poda, there are several subordinate Protozoic groups, some of which either
stand as it were midway between them, or represent a development of the
amorphous and mouthless Bhizopoda in a different direction ; such are the
Gregarinida (XXII. 28-36), with the associated Psorospermia (XXII. 37-
41), the Spongiada, Thalassicollida, and Polycystina, aU which must rightlv
also be numbered with the Protozoa.

Of the Ciliata themselves, there is a further and higher development of
their type in the subordinate groups of Ichthydina (XXII. 46-47) and Noc-
tilucida (XXXI.), and, on the other hand, a degradation of it, as already
noted, in the case of the Opalinaia and Peridiniaia. Here wo would remark
that the term ' Infusoria ' has been employed by several writers, in lieu of
that of Ciliata, which we adopt ; stUl it is, to our mind, both less appropriate,
and also open to objection, not only on account of its meaning being quite
indefinite, but also by its having everywhere acquired a very much mden
signification, in consequence of which it wiU always be open to misconception
when appUed to a comparatively veiy small class instead of, as heretofore, to
a very various and wide collection of microscopic organisms. Another word
invented is ' Stomatoda,' which is precisely equivalent in the extent of its
signification with the term Ciliata, the mouthless families only being excluded.

Excepting their subordinate groups, the organisms comprehended among
the Ciliata and Bhizopoda formed, in conjvmction with the Dcsmidieo' Dia-
tomece, and the families we have brought together under the appellation
Phyiozoa, the great class Polygastrica in the system of Ehrenberg. Little
reflection is necessary to convince ourselves of the veiy heterogeneous nature

200

GENERAL HTSXOBY OF THE INFTJSOJilA.

of the collection of living objects assembled in that class ; and even Ehrenberg
himself would never have suggested such a grouping, had he not imbibed the
hypothesis of a pervading unifonnity of organization possessed by the simplest
animated beings in common Avith animals considerably advanced in the scale,
and under its influence, aided by his imagination, found in aU these various
organisms, a polygastric structure, viz. an apparatus of niimerous stomach-
sacs, communicating directly or indirectly with the mouth. Notwithstanding
the many prominent errors in Ehi-enberg's classification, he rightly recognized
in fi-aming it the value of the external means of locomotion, and distinguished
a group of Polygastrica under the name of Pseudopoda.

Siebold, who proposed the term Protozoa, Limited it to two classes, distin-
guished as the ' Infusoria ' and the ' Rhizopoda ', omitting the supplemcntaiy
groups above mentioned. The Infusoria he divided into two orders, the
' Astoma ' and ' Stomatoda,' the latter of which, together with two of the
three families of Astoma, is equivalent to our class Ciliata, its remaining
family Astasicea being a member of our group of Phytozoa.

The Protozoa, as understood by us^ may be thus exhibited at one view.

Ciliata. Rhizopoda.

a Astoma fOpalinsea a. Amoebsea

\ Peridinisea (?) b. Monothalamia or Monosomatia

^b. Stomatoda ^

c. Polythalamia, Polysomatia, or
Foraminifera.

Gregarinida
Psorospermia

{Polycystina
Thalassicollida
Spongiada

In treating of these several classes and groups we shall commence with
the Rhizopoda, omitting, however, lest our subject-matter be too much ex-
tended, the Polycystina, Thalassicollida, and Spongiada ; we shall next pro-
ceed with a brief description of the Gregarinida, an.d its subordinate family
Psorospermia, and then after considering the Opalintsa and Peridinicea as
intermediate groups, proceed to detail the history of the perfect Ciliata —
the Stomatoda, — finishing oiu- account with the Ichthydina and Noctilucida
as the highest developments of Protozoic life.

As a result of our inquiry, we shall see, on the one hand, in the true
Ciliata, simple animal organized matter, with a very sUght amount of differ-
entiation, attain its acme of development in the Vorticellina, and in these
animalcules exhibit a superiority in organization above tlie lowest Unks of
groups relatively higher in the chain of animal life ; and, on the other hand,
in the Ehizopoda, of stiU simpler organization, the same organic living
material developed in a totally different direction to a maximum in the most
beautiful and complex-shcUed Foraminifera, which in outward form, although
in no real homology, emulate the highest class of Invertebrata, viz. the
Cephalopoda

Another lesson may also be derived from the objects of oiu- present study,
viz. the fact of the marvellous vaiiations which can be made out of one or, it
may be, two clementaiy structm-es. Thus the simple contractile substance which
can live independently in the Amoeba condition (XXI. 1-4 ; XXII. 1-23)
encases itself in a one-chambered shell in the Monothalamia (XXI. 6-19),
and into a many-chambered one in the Polythalamia (XXI. 20-36), and again
lives partly within and partly without the curious silicious skeleton of Poly-

Ichthydina |
Noctilucida |

OF THE PEOTOZOA. RHIZOPODA.

201

cystina, and in singular relation with a spicula skeleton in Spongiada and
Thalassicollida, .

So, if we look to the Ciliata, we find that the hardening of the superficial
lamina of their substance into a sort of integument gives rise to numerous
modifications in external form and functions, according to the degree of
indvu-ation, and the processes sent out. The flexible-skinned Colpodea
(XXIX. 25-50) depend for theii- movements upon their garnitiu-e of vibratile
cilia, and are merely s'ndmmers, whilst the hard-coated Euplota (XXV. 350-
353) produce short moveable processes which act as legs, upon which they
can rapidly creep. Lastly, the selfsame primitive contractile substance is
formed into a stem in the Vorticella, which supports the animalcule at its
apex, and exhibits heKcoid contractions, astonishing both by their rapidity
and completeness.

SUBSECTION I.— EHIZOPODA.
(Plates XXI. XXII.)

The true BMzopoda constitute a large class of microscopic animated beings
of the most simple character. They may be defined as non-ciliated Protozoa
moving by variable expansions. Their organic animal substance presents no
distinction of tissues or of organs, but is homogeneous, contractile, and trans-
lucent, resembling a tenacious mucus or soft tremulous jelly, and is perpetually
changing its form by expanding itself at one or several points into processes
of ever-varying dimensions, arrangement, and number, and called in conse-
quence " variable processes." Inasmuch, moreover, as these shifting offshoots
are their only means of locomotion, they have frequently been called " feet,"
and, as they are also characteristic of the class, have given origin to the terms
" Pseudopoda " (with false feet) and " Rhizopoda " (root-like feet) to desig-
nate it. Again, the living mass is, in numerous instances, capable of enclos-
ing itself by a shell of various figme, consistence, and complexity ; and such
variations serve to separate the Ilhizof)oda into families and genera.

In the simplest shell-less beiags (XXI. 3, 4), vitality is exhibited by the
slow protrusion and retraction of the variable processes, by the change of
form, their onward movement, and the introduction of nutritive substances,
and by the gradual clianges of the introduced matters indicating a digestive
act. They therefore manifest vital contractility, a power of locomotion, a
degree of sensibility, and a digestive process.

Repeated observation likewise reveals the fact of progressive growth, and
the faculty of reproduction. The testaceous forms exhibit their vitality
after the same manner, and surpass the naked Ehizopoda only in the mar-
vellous power of secretion displayed in the production of their shells (XXI
6-36).

Although in organization the Ehizopoda stand even below the cUiatcd
Protozoa, yet an animal nature must be allowed them ; indeed the simplest
forms are the rudest specimens of animal existence. Under the term Rhizo-
poda are comprised three well-marked families, viz. the Amoehina or Amceb<va
which are without, and the Monothalamia and the Foraminifera, with shells.
The Monothalamia have one large opening to their raouolocular (one-celled)
sheUs (XXI. 6-17)— hence the name, — whilst the Foraminifera owe their de-
signation to the existence of numberless small orifices, generally distributed
over a midtilocidar (many-celled or chambered) testa (XXI. 20~3G).

We have frequently, in the following pages, used the term Arcellina as
synonymous with Monothalamia : for although the family known to Ehrenberg
under that name comprehended only a portion of the genera that Schultzc

202

GENERAL HISTOKY OF THE INFUSOHIA.

arranges in his group of single-chambered or monolocular shells, yet its
meaning may be equally extended.

It would probably have been correct to have placed the Acinetina (XXIII.)
among the Ehizopoda, as another family closely alUed to the Amcebina ; but
the detail of theii- peculiarities would have too much embarrassed the general
description of structure which we have endeavoured to give of aU the usually
acknowledged or true Ehizopoda ; we have therefore preferred to describe
them as a subclass in the following chapter.

The examination of the Ehizopoda requii-cs to be conducted with great care
and skill, — a requirement sufficiently illustrated by reference to the en'oneous
notions and descriptions of the older observers. They must be viewed ia aU
positions under diiFerent degrees and modes of illumination, by reflected as
well as by transmitted light, and, especially in the case of the testaceous
varieties, after submitting them to pressure and to the action of various
chemical agents, or, when sufficiently large, after making sections of them in
different directions.

The organic living mass of all Ehizopoda is alike, and corresponds with the
" Sarcode " of ciliated Protozoa and with the amorphous contractile substance
of Hydra and of other low organisms. It appears in the present class a con-
tractile, highly elastic, colomiess, almost fluid mucus, hyaline or diaphanous,
homogeneous, and in refracting power differing little from water. No di-
stinction into an enclosing firmer membrane or integument and contents is
discoverable ; and cilia are never found. These characters exist in entirety
only in very young animals ; for at a very early period molecules, granules,
and globules or vesicles, and various foreign particles, make their appear-
ance, diminish the transparency, and often impart colour.

A new species of Amceba, figui'ed by Schiiltze, the A. globularis, is repre-
sented as having a thin, transparent, colourless lamina of contractile substance,
from which the processes are given off, and which suiTounds a globular, co-
loured, and granular chief or nuclear mass (XXI. 1, 2). A similai" distribution
of the substance of an Amosha into a hyaline colourless cortical, and a granu-
lar coloured medullaiy portion, is represented by the same author in another
species ; and it is moreover a structiu-e homologous with that in the allied
genus Actinophrys (XXIII. 28, 29). As to the assigned character, of the
animal sarcode being destitute of a distinct investing membrane or integu-
ment, the shell produced by the testaceous forms might be considered equiva-
lent to one ; and if some observations hereafter alluded to be coiTect, a re-
sistant integument among the Ehizopoda must be admitted as an established
fact.

It is possible that in some instances the organic substance has a colour of
its own ; for instance, Ehrenberg describes Am<xba princeps as ha\-ing a yellow
colour. However, in general the occurrence of coloiu- is consequent on that
of granules, and on the introduction of food ; and observ^ation proves that the
depth of colour augments with age, and is othei-wise in direct relation with
the abundance of food. The colour is usually pretty uniformly diffused.
Sehvdtzo shows this, and also its relation with the thickly- distributed minute
granules, in many MiJiolida;, Botalida', and Oromia. In larger ^species (he
adds), such as Polystomdla strigilata and Oromia ovifonnis (XXI. 16), the
colour occurs in scattered and much larger particles or vesicles ; yet imder
what form soever found, it is, in the case of the many-celled or chambered
Foraminifera, deepest in the oldest ccUs, and progressively fades on approach-
ing those most recently formed, the last being commonly quite colourless
(XXI. 28, 33, 36). Experiment also showed that, by depriving the animals
of food which could convoy coloui", other chambers than the last lost their

OF THE PEOTOZOA. BHIZOPODA,

203

tint, and, vice versd, that by feeding- them abundantly with such food, even
the animal substance of the xiltimatc cell acquii-ed colour. Irregular accu-
mulations of colouring particles in the ultimate chamber are of rare occur-
rence. Ehi-enberg has figured such in Nonionina germanka.

The coloirrless, or ahnost colourless Ehizopods, principally Amoehce, are,
owing to their transparency, visible with difaculty, and requii-e nice adjust-
ment of the microscope and of the hght to demonstrate their vitality and
movements.

Concerning the chemical relations of the organic substance, it is stained
yellow or yellowish-brown by solution of iodine, like other proteine matters,
and, according to Schultze, is unaltered by diluted acetic acid, is slightly
hardened by a dilute solution of the alkalies, and more so by one of the car-
bonates. Moreover, its resistance to chemical action would seem to differ
in different species ; for the Oromia Dujardinii was the least affected of se-
veral animals experimented on.

"The colouring-material," to quote the same writer, " assumes by the action
of sulphuric and of hydrochloric acids an intense verdigris green, and by
that of nitric acid, first a green and then a yellow tint. Concentrated sul-
phuric acid destroys the coloured substance, but when combiaed with sugar,
renders it green. By concentrated solutions of potash and soda, the coloured
granules are dissipated without change ; and ia ether and alcohol they are
readily and completely dissolved. In these reactions the colouring-matter
agrees with Diatomece, from which, no doubt, it is derived in the form of food."

No definite figure can be said to belong to the animal portion of the Rhi-
zopoda, owing to its capability of throwing out processes in every direction,
of various dimensions and in different numbers, changing them almost every
moment. Auerbach, however, asserts of the Amoebce that they have normally
a spherical figure. Dr. Bailey has pointed out the influence of pressure from
within, due to the various articles swallowed, in modifying the figui'e. The
Amoebce, being untrammelled by a sheU, exhibit the Protean changes of form
in the highest degree, whilst the completely enclosed Foraminifera present
them in the lowest. In the latter the organic mass must follow the windings
of the cavity of the shell (XXI. 24), and can escape only from the foramina
(holes) as thread-like filaments, in the form, extension, and subdivisions of
which great latitude prevails. "We have said that the sarcode of Polytliala-
mia follows the windings or adapts itself to the figure of each segment of the
shell, and has actually no figui-e of its own. However, when separated fi-om
its calcareous investment by means of an acid, it retains the outHne originally
imposed on it. Thus (XXI. 24) Schultze exlubits the sarcode substance of a
Miliola so separated, which shows a constriction at each half turn of the spiral
and the delicate membrane which invests it or Hues the shell. So, again. Dr.
Carpenter, in his description of Orbitolites, states that the soft sarcode body is
made up of a number of segments equal and similar to each other, and aiTangcd
in concentric zones around a central nucleus. Among the Amcebce the varia-
ble processes may either be protruded at one time from every portion of the
little mucous mass, so that, as Ehrenbcrg remarks of the Aniceba radiosa it
may, when fiilly outspread, be hkened to a miniature porcupine ; or, otherwise
they may be produced chiefly or entirely from one side ; or, as when the ani-
mal is moving, they are throAvn foi-ward in the direction it is progressing, and
retracted on the opposite side. Among many Monothalamia the built of the
living mass issues through the one large orifice, and can spread out in a similar
manner to the free AmoeUna, — the shell, according to the dii-ection of the
pseudopodes, resting in the centre of the mesh or on one side. The Forami-
nifera have a like capacity of extruding their processes in one dii-ection rather

204

GENEKAL HISTORY OF THE INFUSORIA.

than in another, or in all directions together ; and accumulations of their
mucous substance, or fusions, may take place on any one side. In this family
the filiform fibres are, as a rule, not seen protruded at any one time tlirough
all the pores perforating the shells.

Many genera have, besides the generally- distributed small foramina, a larger
orifice in the ultimate chamber ; such is seen in liotalia and Textilaria. In
these, says Schultze, it may be remarked that the processes first thrown out
come principally from the large openings, and frequently a considerable time
elapses before the numerous fine pores give exit to fibres. Often, again, the
filaments are extended only from the two or three last-formed cells. Yet
after long lying undistiu'bed, fibres may be seen proceeding fi'om every part
of the sm-face of the finely porous shells. Still the question requii'es further
examination, to decide whether the processes can be extruded through aU the
foramina or only through some of them ia certain places. However, as
Schultze remarks, the universal porosity would seem without a purpose if it
does not give vent to the contained substance at all points.

The processes of PoJythalamia attain the greatest length and fineness, and
often constitute a network of several lines in diameter, — the sheU of the ani-
mal occupying the centre, like a spider lodged in the middle of its web. The
length of such fibres not uncommonly exceeds twelve times the diameter of
the shell. The processes of most Monothalamia are not so numerous, and do
not equal on an average those of the Polythalamia, whiLst those of the Amoeboe
are mostly shorter and broader. The length, number, and fineness of the
processes, together with their mode of termination, supply, under considera-
ble limitations, characters for disting-uishing species chiefly of the Amoebina,
and, in a less degree, of the single-chambered testaceous Rhizopoda.

The ever-fluctuating form of the animal mass and of its processes is ex-
pressed by the term " 'polymorphism." It is, as before noticed, a weU-mai-ked
character of Rhizojpoda, although not restricted to them ; for the hke is exhi-
bited by the yolk-cells of Planaria, and by detached fi-agments of the substance
of Hydra ; in fact, illustrations are not wanting in the vegetable kingdom.

The phasnomenon of polymorphism would seem to discountenance the hy-
pothesis of the presence of a limiting membrane or skin. Ehrenberg described
a resistant, very elastic, and contractile integ-ument, and, to explain the vaii-
ability of figure and the extension of the pseudopodes, supposed a relaxation
or suspension of the natural contractility of the integamient at the extending
point, and a consequent passive yielding before a pressiu-e from within exerted
by the contained substance. This explanation he endeavoui-ed to illustrate
by comparing the process with the formation of a hernia or ruptiu-e, — a com-
parison, by the way, involving an effort of imagination to discover any simi-
larity between the two occurrences. Thus he remai'ks of Amceha princfps
that " its normal shape, if such it can be said to possess, is globular ; but it
can relax any portion of its body, and contract the rest, so as to force the in-
ternal substance doAvn into tliis relaxed portion, which thus becomes, as it
were, a hernial timiour." This notion is opposed by the results of observa-
tion. The veiy characters of the processes, thoir great length and frequent
tenuity, theii- branching, adhesion, and coalescence contradict the a.ssimip-
tion ; and the fact of their not uncommon extensoin fi'om all sides of an ani-
mal involves, as a consequence of Ehrenberg's hypothesis, a behef in the
exertion of internal pressure in opposite directions at the same time. Other
evidence of the error of this liyi^othesis is found in the follo^\-ing foots, A-iz.
the adhesion and entrance of foreign bodies at any part of the sarcode sub-
stance, the cohesion of two individuals, and that, as pointed out by Dujanhn,
when the gelatinous mass of an Amoeba is torn or cut across, no escape

OF THE PBOTOZOA.-^EniZOPODA.

205

of a contained softer matter or of granules takes place, but each, segment con-
tracts on itself and continues to live, and, again, that when a Rhizopod is
shaken ahoiit, its processes become flexuous, and float loosely instead of being
mthdi-awn within the general mass, as shoiild happen if a general contractile
integument enveloped it. Among the Amccbce generally, a distinct hyaline
cortical substance is foimd enveloping the interior more fluid matters, and
restraining their escape. (See afterwards, on shells of Monothalamia, excep-
tional forms noticed by Dujardin and Bailey, and the researches of Auerbach.)

Although an integimient be, therefore, no part of the structure of Rhizopoda,
yet theu- soft substance is capable, as is shown best in the Amoebina, of resist-
ing internal pressure, such as that from silicious shells of Diatomece and other
hard substances, which oftentimes cause irregular and sharp projections during
the movements of the animals, but yet very rarely perforate them. On the
other hand, Ehizopoda become sometimes impaled upon the rigid fibres of
plants or other substances, and, though thus transfixed, wiU move fi'om one
extremity to the other, without any apparent inconvenience or injury. This
cii'cumstance has been long noticed in the case of the Amoehce ; and Schultze
has fig-ured a specimen of a testaceous Rhizopod— the Ch-omia Dujarclinii
— penetrated by a large curved hair.

Dr. Auerbach, in a recent Essay on the Amoebaia (ZeitscJir. 1855, pp. 365-
430), has advanced the statement, from observation, that all the Amoebce are
enclosed by an adhesive, elastic and stnictureless membrane or integument.
This fact has, he says, been so imiversaUy overlooked by reason of the diffi-
culty in detennining it, and, where caught sight of, has been misinter-
preted, as, for instance, by Schneider {Miillej-'s Archiv, 1854, p. 201), who
represents Amoeba enclosed by a membrane as being in a state of " rest," or
encysted.

Auerbach makes particiilar reference to two new species discovered by him,
as illustrative of the presence of an integument, viz. ^. bilimbosa (XXII. 7-
11), and A. actinopliora (XXII. 13), in both of which he detected a double
peripheral line. But besides this evidence he appeals to the effects of reagents,
of acetic or of diluted sulphuric acid and alkaline solutions, both on the species
just cited and on others well known — for instance, A. princeps — in demon-
strating the membranous investment. And what seems at least veiy strange,
we might say quite inexplicable, he asserts that upon all the processes, how-
ever branched, anastomotic, or fine, this membrane is extended to their very
extremities ; for on adding a dilute alkaline solution to Amceba radiosa, the
granidar and molecular contained mass became shi-imken, and retreated to-
wards the centre, leaving the figui-e of the animalcule Avith all its processes
as before the addition, the latter appealing as tubules ^vith closed ends which
ruptured by over-extension.

This same author accoimts for the entrance of solid particles from without
by imagining the integument to rupture to receive them, and then to close on
them so as to leave no trace of the proceechng. Fiu'ther, the membrane is
not soluble, at the orchnary tempcratiu-e, in acetic nor in mineral acids nor
in dilute alkaUne solutions, and therein agrees -with the tissue noticed by
Cohn in Paramecium and other Ciliata (vide chap, on Ciliata), and Avith the
cell-membrane of animal cells.

These obsers'ations of Dr. Auerbach are well deserving attention, although
we are indisposed to accept them in their entirety. The wonderful poly-
morphism, the coalescence of processes, and the particulars alluded to above
(p. 204) as inconsistent with the presence of an integument need not be
again adduced in argument. What is desirable is, tlmt observations sliould
be multiplied on this subject, which is one that strongly commends itself to

206

GENEEAL HISTOKY OP THE HTPUSOBIA.

the notice of microscopists on account of its bearing on the question of cell-
constitution.

The variable processes serve the Ehizopoda for locomotive organs. An ex-
pansion is thrown out in advance, into which a constant influx of the sarcode
substance sets, — whilst in the opposite direction a counter- current occurs,
effecting the retraction of the posterior processes. This onward flow of the
substance of the body proceeds until at length the whole is transferred into
the advanced process, moving from its base to its termination. In this manner
the animal progresses, the space passed over equalling the length of the ex-
pansion it protrudes. This method of locomotion may be designated creep-
ing or crawling, and is the only one with which this class of animals is en-
dowed. The consequence is that they are, as a rale, to be only found adherent
to solid bodies, and cannot move by swimming. However, they can move as
passive particles of matter, be rolled along by currents upon any substance
they are in contact with, or, from beiag (as m the case of Amoeba) of almost
the same specific gravity with the water in which they live, may float, or be
suspended in it for a long time. Their motion by creeping is exceedingly
slow, and oftentimes is appreciable only by attentive watching.

The graphic description of Schultze, of the expansion of processes in a naked
Amoeba and in a testaceous species, vi^. the Oromia oviformis, will make the
phsenomenon more distinct. The former is a new species discovered and named
by himself the Amoeba porrecta (XXI. 3). It is distinguished from other
species in the genus by the great extension it is capable of, and by the lively
motile energy of its contractile substance. " It sends out from its colourless
body, on aU sides, numerous fibrous processes, short and broad on their first
extrasion, but which gradually elongate until they exceed the diameter of
the body eight or ten times, and taper to such fine extremities that a mag-
nifying power of 400 diameters is needed to distinguish them. The figure
and extension of the body change every moment, according to the side in
which the ramifications are extended. If two or more of the fiHform pro-
cesses touch, a coalescence takes place, and broader plates or net-like inter-
lacements are produced, which, in the continual changes of figure, are either
taken up again into the general mass, or otherwise are further increased by a
fresh influx of matter, until finally the entire body is transposed to their place."

In the testaceous Oromia oviformis (XXI. 16), after a state of rest of some
duration, fine fibrous processes are seen to be extended from the single large
opening of the shell, which, on their first extrusion, move about in a groping
manner until they lay hold of some solid body (such as the surface of the glass
sUdc) on which they may stretch themselves out, receiving in the meanwhile
new matter from within the shell. The first fibres are extremely fijie ; but pre-
sently they grow wider, and proceed to elongate themselves, p\u-suing a straight
course, ramifying in their own way and coalescing with adjoining processes,
until, ijecoming progressively finer and finer, they attain a length exceeding
that of the body six or eight times. The fibres having now outsti-etched
themselves in every direction, and absorbed the greater part of the finely-
granular contractile substance, theii- further extension in length ceases.
However, the reticulations go on multiplying ; numerous bridges (inoscula-
tions) are established between them ; and by the continued changes of position
a constantly shifting protean web is produced, where a greater number of
fibres come together at the pcriphciy of the sarcode-nct as avo may term it,
broader plates (lamina;) of the perpetually-flowing substance ai-e fonned, from
which again new filaments are pushed out in new directions, as if it were a
separate Amoeba. In the PohjstomeUai, the long fibres are seen to converge
to form a pyramidal buncUo, and to coalesce into wide lamina? at its apex.

OF THE PROTOZOA. EHIZOPODA.

207

Dujardin made some precise observations respecting the characters of the
locomotive vaiiable processes and the rate of movement. In Gromia oviformis,
he describes a fflament to begin as a veiy fine simple and unifom offshoot,
which elongates and directs itself in different directions, in order to seek a
point of attachment ; sometimes it oscillates, at others it exhibits a tolerably
rapid imdulatory movement, or, otherwise, it rolls itself np in a spiral manner,
when the several . cods coalesce, and a mass is formed capable of thi'owing out
afi-esh other processes. Proportionately to the extension of the filament, its
substance is added to by an a&ux of new substance from the cliief mass, evi-
denced by the movement of irregular granules, which give the fibres an un-
equal and nodose appearance. Moreover, the fibre gives off branches here and
there at a more or less acute angle, which, in their tiun, ramify after the same
fashion, and establish communications or anastomoses with one another. Often
also films or laminae of the gelatinous substance form at the extremities of
contiguous fibres, which extend themselves variously. The filaments retreat
by an inverse movement ; and this is occasionally so sudden that the end as-
sirmes a button-like termination from the fusion of the mass of matter engaged
in its formation.

The expansions of Miliola, he fui-ther tells us, are six times finer than those
of Gromia, and the movement of the animal more rapid ; for during summer
it moves from about -Arth to -J-th of an kich in an hour. Cristellaria moves -i-th
of an inch, and Vorticialis from ^th to ird of an iach in a like period.

The variable processes also constitute the prehensile organs of the Rhizo-
poda. Any small objects serviceable for nutrition, with which they come into
contact, are laid hold of by them apparently by means of their viscid surface ;
and, except they are animalcules of considerable size and power, they are tm-
able to escape. When a filament or, as we may call it with reference to this
function, a tentacle has so seized its prey, adjokiing fibres aggregate about
it and coalesce, a current of the viscous substance sets in towards the spot,
and very soon envelopes the object by a film. The prey being thus secured,
the processes shorten themselves and draw it towards the chief mass or body
of the animal, or, otherwise, the object seized continues in the same place, and
the whole organic substance moves towards it, — the result being in either case
that it is engulfed. In the Amcehina this prehensile act proceeds as just
stated; in the Monotlialamla and in those Foraminifera having a large
opening in the last chamber, the body seized is directed to the lai'ge orifice
of the sheU ; but in those having no other than fine pores or minute fissures,
it would not seem to reach the general mass, but to be used up for the pur-
poses of nutrition externally to the shell, by a digestive action inherent in
the fibres themselves. The mode of entrance, therefore, of food within the
\iscid organic matter, is not so simple and mechanical an act as Dujardin re-
presented it, but has much more of a vital character. This observer's state-
ment was, that the mere pressure of the body of the animal on tlio siu-face it
moved over caused the penetration of foreign matters, which, by subsequent
extensions and contractions of different parts of the substance, became at
length completely involved in it. It would seem that animalcules may swim
about unharmed within the meshes of the sarcode-wob, but that so soon as
they touch one of its fibres, they are as it were paralysed and incapable of
fui-ther motion, and are consequently drawn deeper into tlie net without any
opposition. Schultzo, who has noticed this circumstance, believes it to be
quite explicable as a simple mechanical act, and no proof of a special be-
numbing property resident in the soft substance as Ehrenbcrg was inclined
to suppose. Food, or indeed any extraneous matters, may enter the soft
boches of Rhizopoda at any point of their sujfaco ; ?". e. in other words those

208

GENEnAL mSTOllY OF THE INFUSOEIA.

ammals have no definite apertui-o for food — no mouth. This absence of a
mouth, on anatomical grounds alone, involves that of an alimentaiy canal, or
of a polygastric structure such as Ehrenherg imagined. The digestive cells,
so called, of Arcellina are nothing more than hollow spaces or vacuoles (XXII.
7, 8, 9), which spontaneously and irregularly dcvelope themselves in the mu-
cous sarcode substance. They especially make their appearance after the in-
troduction of food, the particles of which generally appear enclosed within
them, and to be .siu-rounded by a fluid. In the allied organisms represented
by Actinophrys, M. Claparede states that the particle of food always lies in a
cavity fiUed with fluid — a vacuole, — and that the fluid is of a pale reddish
colour, with different refi-aetive powers to those of water, and is in aU proba-
bility a solvent or digestive fluid. This pale-red or reddish-yeUow tint of
the vacuoles is remarked also in Amoebce ; and the observed dissolution and
eventual disappearance of organic matters absorbed is a sufficient proof of
the presence of a digestive secretion. In an Arcella vulgaris, Perty witnessed
the successive appearance of four vacuoles, each in its turn enlarging from a
small round to a large reniform space, and thereby expanding the dimensions
of the animal itself. He believed them to be filled with air, and, like the
air-bladders of fish, to serve to float and turn the animals in the water, when
free and without soHd objects to crawl upon.

Ehi'enberg states that in some Arcellina, where "digestive sacs" were
othei-wise invisible, they were brought into view by feeding the animals with
coloured substances. He thus presumed on the prior existence of these cells,
supposing the colouring particles to be merely the means of bringing them
into view. The true explanation, however, is, no doubt, that the con-
struction of vacuoles is consequent on the introduction of food, and de-
pendent on the manner in which the animal substance enfolds the soHd par-
ticles which it has seized. Observation, indeed, proves that the vacuoles
have no constant and definite existence and position ; for they collapse and
disappear when the contents are removed or are reduced to a few fine
granules dispersable in the common mass. They also constantly shift their
position, and not unfrequently make their way to the surface, at which they
burst and disappear. As Dujardin also remarks, they sometimes form at or
near the surface, and may even serve as a medium for introducing foreign
matters into the body.

Dr. Bailey, in his description of a new species which he names pampliagus,
represents it as having (although a shell-less Ehizopod) a mouth from which
alone pseudopodes protrude, and a single stomach ; hence, he adds, it cannot
be considered polygastric. However, no evidence is adduced to support this
notion of a gastric cavity ; on the contraiy, indeed, the details given stand
opposed to such an hypothesis, — for instance, to quote only one, that of their
being frequently seen transfixed by deUcate fibres of foreign matters, and
moving unharmed up and down them.

Schultze states that in Foraminifera veiy clear vesicles are unifomily
diflused throughout the body, some entirely homogeneous, others finely
granular, or filled with coi-piiscles. However, nuclear corpuscles, which can
be regarded as cells in the ordinaiy signification, are never found. This
natiu-alist, moreover, indicates the existence of a larger species of vehicles in
Oromia oviformis (XXI. 16), containing other clear corjiusclcs, sometimes to
the number of eighteen, but never strung together ; he behevcs Ukewise that
similar vesicles exist among other Foraminifera, and seems disposed to attri-
bute to them a nuclear character.

Ehrenherg professed to discover in the Polythalamia, in each chamber,
saving the last, an alimentary tube, having a greyish-green colour and very

OF THE PROTOZOA. RnlZOPODA.

209

thick. This intestinal cavity, he affirmed, communicated with_ the ceU m
front, and the one next behind it by a narrower canal— the siphon,— ajid
that in this manner a sort of continuous mouiliform intestine was produced,
extenchng from the primaiy to the penultimate ccU. He adds that, after the
solution of the shell of Nonionina Qermanica by dHute acid, vanous sihcious
Infusorial shells could be seen within this digestive tube, as far back in the
animal as the fii-st chamber. Moreover, he was fortunate enough to be able,
after the dissolution of the sheU of BotaUa by acid, and by proceeding very
gradually, to set free an internal, spiral, jointed body, the segments of which
were Strang together in Nonionina by one, and in Oeoponus by from 18 to
20 tubes (siphons) ; strong acids destroyed the shell so rapidly that the con-
tained dehcate body became broken up into many insignificant fragments. In
none did he succeed in introducing coloured food. This digestive apparatus
others have sought in vain in the Foraminifera. The spiral articulate body
extracted by the Berlin naturalist from the shell, was undoubtedly nothing
more than the soft animal contents, somewhat acted on by the acid, such as
Schultze has pictui-ed from the cavity of a Miliola (XXI. 24).

Eespeetingthe penetration of food to the primordial chamber, which Ehren-
berg imagiaed he had seen in Nonionina, Schultze observes that, among the
many beings he has examined, he has not detected nutritive matters fuxther
back than the second or third cell.

The substances received from without, after having served their purpose
within the gelatinous body of Ehi^opoda, make their way outwards and
escape from any part of the surface, — an anus being, lUce the mouth, pro-
duced temporarily, at any point whatever, where matters present themselves
for discharge.

The materials taken within the body of Ehizopods are most heterogeneous ;
no selecting power being displayed by the animals, various Ciliated Protozoa,
fragments of the filaments and spores of Algte, frustules of Diatomece and
Desmidiece, even Rotatoria, faU. a prey : but along with these, from which
nutriment may be extracted, are other substances which can be supposed to
serve no useful purpose ; such are particles of sand, morsels of woollen and of
cotton tissues, and the like. The introduction of particles indiscriminately
is explicable from the mode in which they are captm-ed by the filamentary
arms, which seem to act in a prehensile manner, on feeling the contact of any
foreign object, be that what it may.

Dujardin threw doubts upon the nutritive pm-pose of the solid objects
swallowed, and supposed the act of nutrition consisted in the simple imbibition
or endosmosis of fluid from without. " It is," he writes, " difficult of belief
that these included particles, by reason of their consistence and the unaltcr-
abihty of many of them, can serve to nourish the Amoeba; ; yet, whilst admit-
ting that they are nourished by absoi-ption, I would not deny that they may
find means of stiU more readily appropriating nutritive materials, by swallow-
ing various foreign bodies, and by so increasing their absorbent surface." The
evidence of direct observation, however, is in favour of the conclusion that
the substances received within the simple animal mass actually afford ma-
terials for its nutrition. The contents are ever changing and maldng their
exit from it ; and an act of digestion or of solution is perceptible — slow, indeed,
even wlien soft Ciliated Protozoa are the subjects. Thus animalcules, when
■within the sarcode mass, are fii-st compressed into small balls ; the distinct-
ness of their parts then fades, and tliey arc presently con\'crtod into small
gelatinous globules, which in duo course disappear, from amalgamation with.
the enclosing substance. Where the included body consists partially of
insoluble material, this remains behind in tlie form of fine granules, or, in

210

GKNEKAL aiSTOIlY OF THJi INFUSORIA.

the case of the silicious-enveloped Diatomece, the dense skeleton, emi)tied
of its organic contents, contiaues visible for a longer or shorter time. The
robbing of the frustiiles of Bacillaria, and the appropriation of their coloured
endochrome, has been referred to in the foregoing remarks on the colouring of
Rhizopoda (p. 203) by the green colouiing-matter of plants.

The Ehizopods Bailey describes were met with in a vivarium, into which
" bits of boUed beans and potatoes had occasionally been introduced as food
for other animalcules ; .... on the application of tincture of iodine to these
animals, a distinct blue colour was often seen diffused over the whole surface
of many of the grains of sand iu their stomach."

The above facts — to which we may add another, viz. that the abundance of
granules in the interior is in direct proportion with that of food — furnish
sufficient proof of the occurrence of a digestive faculty, and of a power of
assimilation among the Ehizopods. This implies the existence both of a
digestive fluid, and of a secretoiy function ; the latter, too, is further ex-
emplified by the production of shells in the majority of the class.

Auerbach (op. cit. p. 422) distinguishes two leading varieties of granules in
Amcehce : — one of a pale coloui- and finely divided, and either soluble in
alkalies and acids, and turned brown by iodine, or, more rarely, insoluble in
alkalies ; the other, dark in hue, strongly refracting, and usually corre-
spondent in number and relative size with the animalcules to which they
appertain. These latter have the aspect of fat-molecules ; are spherical or
elliptic, or at times crystallized in a rhombic fonn ; and they are easily soluble
in cold allcaline solutions, and more slowly so in concentrated acetic and sul-
phuric acids. In one species, A. bilimhosa, he met with staxch globules ; but
these were probably of extraneous origin.

Movements of contained paeticles. — Every movement of the mucous sub-
stance of Rhizopoda is accompanied by one of the granules, and of the small
vesicles or globules contained within it. This motion of the contents follows
a certain course, and is especially observable in the outstretched variable pro-
cesses. Schultze thus describes it in the large Amoeba porrecta : — " A continued
current of the granules, imbedded in the contractile substance, accompanies aU
these phenomena (viz.. of polymorphism); and, in the processes, this cun-ent
foUows two directions ; thus the globules may be seen advancing on one side,
towards the end of the process, when ttey turn round to the other, and are
carried with a comparatively more rapid motion back towards the base of the
filament, where they are lost in the substance of the body, unless they happen
to meet another stronger stream by which they are reconveyed through the
same circuit." A precisely similar phenomenon is \vitnessed in the testaceous
Ehizopods. Thus in Gromia oviformis, Schultze says, the granules are seen
to depart from the substance within the shell to the end of the filaments, and
thence to return again to the point from which they set out. This cu'cula-
tion goes on in every process ; but it is in the broader filaments, containing
numerous granules, that the double stream is chiefly visible : for in the finer
ones, whose diameter is often less than that of some of the coqjusclcs, it is
more rarely seen ; in fact, in the latter the granules seem not to be included
within the substance, but to bo transported on the sui-face. Oftentimes a
corpuscle, on arriving at a point where a fibre bifui-catcs, is arrested for a
time, until drawn into one or other cuiTent, — whilst at the bridge-hke con-
nexions between adjoining filamenta, where the granules pass across from
one to the other, it not unfrequcntly happens that they are transferred from
a centrifugal to a centripetal stream, and are consequently turned back again
towards the body. Moreover, in the broader processes, granules are observed
to come to a stand, to pscillate for a time, and at length to take a retrograde

OF THE PBOTOZOA. BHIZOPODA.

211

course. Since there is no appreciable distinction of tissues, not even of
integument aud contents, the existence of vessels to account for these cur-
rents cannot be presumed.

A cm-ious exception appears to exist in Ch-omia Dujardinii, the filaments
of which exhibit no granules, but are perfectly hyaline, and moreover show
no circulation. In their transparency, Schultze remarks, they resemble the
processes of Arcella and Difflugia, and so also in the matter of breadth, but
differ by their greater length, their finely-pointed extremities, and by their
frequent ramifications. This species has also in its principal mass peculiar
corpuscles, roimd, oval, or irregular in figure, with a shai-p outline, and of a
brown coloui-, diffeiing fi'om all other known elementary particles in chemical
reaction, in resistance to alkaline solutions, and to mineral acids, even to
sulphuric.

Amid the many shifting corpuscles and small globules is a large vesicle,
constant in position, alternately collapsing and dilating, and hence called the
contractile vesicle (XXII. 4, 5, 6). This organ, which is homologous with
the pulsating sacs of Ciliated Protozoa, has not been remarked by every
observer, nor in many of the Ehizopoda ; nevertheless we presume it to be
an essential organ, and its existence general in the class. In Arcella a con-
tractile vesicle has been seen by many ; in Actinophrys Sol, Clapai'ede has
satisfactorily proved it a true sac, having a resistant membranous wall, and
has counted as many as ten such vesicles in Arcella vulgaris ; Auerbach treats
of the vesicle as general among Amcebcea; on the other hand, Schultze
was Tinable to discover such an organ among the many Foraminifera he
examined.

Nucleus. — Another definite body is mostly discoverable in Ehizopods, viz.
a nucleus in the foi'm of a more or less rounded or oval body, more opaque
than the rest of the contents, and consequently more solid in appearance
(XXII. 4, 5, 9, 16, 20). In Amoeha and Arcella, Ehrenberg and Siebold
admitted the existence of a nucleus ; Schneider says that Amoeba diffluens
and A. radiosa possess one, that a roimd reddish nucleus having a white
nucleolus is present in Difflugia at its hinder end (XXI. 19 a, b,f), and
that probably aU the Ehizopoda have such an organ. KoUiker, to whose
hypothesis of the ceU-nature of Ehizopods the recognition of a nucleus was
of much importance, remarks, with respect to the nucleus, it reaUy appears
to be present in some of them (see Ehrenberg's figures) ; and where it is want-
ing, as in Actinophrys, a true nucleus may have existed at an early period,
and be absent only in the full-grown animal, or, again, it may be entirely
wanting, and stOl the animal be regarded as a cell."

Claparedc, on the contrary, denies a nucleus to the naked Ehizopoda, at
least to Amoeba diffiuens ; and likewise to the testaceous species, such as
Arcella. However, he admits that the usual opacity of the shell is an
obstacle to an accurate determination of the question, and remarks concern-
ing the foregoing supposition of KoUiker, that there is no evidence of its
truth, and no foundation in fact.

Schultze has encountered an undoubted nucleus in nine difierent species of
Amoeba, in Difflugia proteiformis, D. acuminata, and D. Helix, in Arcella
vulgaris and several species of Euglypha. In Ch-omia oviformis a round
clear, delicate body filled with veiy transparent small vesicles may always
be found. In old fuU-grown individuals not one but several such bodies are
seen at the posterior part of the animal, aU of equal size and of similar stnic-
ture (XXI. 12, 13, 14). In one specimen as many as eighteen of thasp
nuclei were counted. In young smaU Gromia: only one nucleu.s is soon •
in a solitaiy instance two were found. ' '

2L2

GENEBAL HI8T0BT OF THE INFUSOBIA.

In JJiffluyia proteiformis usually several (8 to 12) nuclei are perceptible, a8
in Oromia oviformis, va the posterior portion of the shcU.

The nuclei of freshwater Ehizopods either appear to be homogeneous deli-
cate elastic globules, here and there finely granular, or they resemble the
nuclear body of Oromia oviformis, and consist of a group of small vesicles or
globules enclosed by a common membrane (XXI. 14).

The single nucleus of young beings, Schultze supposes to be derived from
the parent animal ; and he fui"ther presumes that, in the course of age and
growth, this organ is capable of multiplying itself, and may, moreover, serve
as a centre around which the fine granules of the living contents aggregate,
and that, after the formation of an enclosing membrane, an embryo is generated
fi-om it. On the other hand, this careful observer was not able to discover a
nucleus in Foraminifera, and admits that the above suppositions are highly
doubtful.

In a large specimen of Oromia Dujardinii, Schultze met with certain en-
closed bodies, having a firm shell and granular contents, and only wanting
a mouth to complete their resemblance to the parent animal (XXI. 18 a, b).
He also cites, as still more questionable examples of a nucleus, a clear spot in
the fii'st chamber of Botalia veneta, and in Textilaria 2>icta, a finely-gi'anular,
solid, and nucleariform body in each of the two last cells (XXI. 32).

On this point, the presence of a nucleus in Foraminifera, we have the state-
ment of Ehrenberg, that in each cell, except the last, there is a coarsely
granular yellowish brown mass, which represents an ovary in structure and
function. Unfortunately, however, the Berlin microscopist stands alone, both
in this observation and in its pendent corollary. Dr. Carpenter uses the
word nucleus to signify the primordial mass of sarcode seen in the first
cell, of which all the subsequent chambers and their contents may be deemed
the offehoots.

Scattered among the amorphous granules of the sarcode are, for the most
part, numerous refracting corpuscles of less size than vacuoles, which are
soluble in ether, and therefore concluded to be fat-globules (XXI. 14-16).
There are also other molecules dissolved by caustic potash. It is these
various globules and granules that some observers have esteemed to be ova,
without, however, any countenance from facts for the supposition.

To rectir to the naked Khizopoda, Auerbach, in the essay before quoted,
attributes a nucleus to the Amoebcea in general. He remarks that the
sohd-looking organ, of a dull aspect and commonly spherical figui-e, noted
by certain authors in some Amoeboi, is rather the nucleolus than the nucleus,
and that the latter is perceptible in the form of a hoUow space, oftentimes
having a glistening rosy hue, which siuTounds the other like a sac (XXII.
4, 5, 9, 10, 11). This sac is sometimes visible as a dai'k ai-eola, but at othera
requires the operation of chemical reagents to reveal it, or will manifest itself
in dead specimens when aU the ordinary vacuoles have disappeared. _ At
times, both it and its nucleolus have a dumb-beU figure, and thereby indicate
the occurrence of the process of self-division. A similar nuclear sac is men-
tioned by Schneider.

As to its chemical relations, Auerbach found that both nucleus and nucleolus
were readily soluble in allcahes, and that they became darker in dilute acetic or
sulphuric acid, which also caused the precipitation of a finely-granular matter
in the vesicular or saccular nucleus. In concentrated acids they fii-st expanded,
and were subsequently dissolved. The generally-assigned character of the
nucleus, viz. that it becomes darker on the addition of acetic acid, is true,
only when dilute acid is used.

Auerbach discovers a nucleus and nucleolus in Arc^lla, similar to those

OF THE PROTOZOA. KHIZOPODA.

213

of A-moebce, often displayed when, by a fracture of the shell, the animal con-
tents escape. The nucleus has the form of a thick- walled sac, and encloses a
lai-ge nucleolus. Eut it is remarkable that, whilst one or at most two nuclei
only are discoverable in Amcehce, several such organs are frequently present
in Arcelkv, their number beiag in dii-ect proportion with the magnitude of the
animals. In large specimens, of in diameter, above 40 such nuclei have
been encountered.

EEPKODTjcTioif OF Ehizopoda. — TMs functiou is not satisfactorily made out,
especially in the case of the Foraminifera ; what is known -will best be de-
tailed of each family separately.

Among the Amcehina self-division has been noticed by Ehrenberg to occur
in the Amoeba princeps ; and Dujardin remarks that " they may doubtless
multiply by spontaneous fission, or by the throwing off a lobe which imme-
diately commences an independent existence." This separation of a portion
of their substance is not unusual, as, when a large variable process has been
shot out far from the chief mass and become enlarged at the extremity, the
expanded end retains its position, whilst the portion connecting it with the
body becomes finer and finer by being withdrawn iuto the parent mass, until
it at last breaks across, leaving a detached piece, which immediately on its
own account shoots out processes, and manifests an independent existence.
This phenomenon is therefore one of simple detachment, and cannot rightly
be called a process of fission. Schneider terms it " propagation by gemma-
tion," and supposes it attended by a division of the nucleus, of which every
such ofi'set, in his opinion, iucludes a portion. This same obsei-ver fiu-ther
states that Amoeba has actually a " state of rest " (i. e. an encysted condition).
He observed it first to become round, and then to form a fii-m membrane on
one side, whilst the other portion continued its peculiar character and move-
ments. By degi-ees the membrane extended itself over the whole body, the
moveable portion constantly becoming smaller, until at last a completely-
closed cyst was produced, in the clear interior of which a round nucleus,
with a reddish halo, exactly like that of Polytoma and other Monadina,
might be distinctly observed. He adds — " In the nucleus of Amoeba I have
often noticed on the outer surface of the reddish halo, granulations which
united to form a closed membrane, whilst at other times the nucleus exactly
resembled that of Polytoma " (i. e. was without an enclosing membrane).
What is the next phase of development following this encysted stage,
Schneider has nothing to show.

If Lieberkuhn's observation be correct, a most extraordinary relation sub-
sists between Amxebce and Gfregarinoi, involving the existence of the former
as a distinct class of animated beings. This observer saw the production
of Amoebce from Navicellai, the origin of wliich from Ghegarinm is as good as
proved ; and also met with such Amoebce in every transition to perfect Qre-
garince. This fact is alluded to in a paper by Kolliker (J. M. S. i. p. 212),
who beUeves the AngiiiUida-\ike animal noticed by Hcnlo, and termed bj'
Bniet Filaria, to be an Infusorium allied to Opalina Proteus, and goes on
to say that the transition of this presumed Filaria into a Oregarina- and
finally into a iV(tytceM«-receptacle is nothing extraordinaiy. Auerbach asserts
the encysting process to be shared in by the Ammboia along with other
Infusoria ; but he looks upon Schneider's recorded instance as an erroneous
conception of a specimen clearly enveloped by an integument.

Monathalamia would seem capable of multiplj-ing themselves like the
Anwebina, by dctachijig portions of their substance, i. c. by a species of gem
mation. Peltier has described this occurrence, although Ehrenberg failed to

214

GENEKAL HISTORY OF THE INFUSORIA.

lleproduction by positive complete fission is opposed by the exifitence of
the sheU, which is a product from the siuface of the animals adapted to their
outline, and increasing only in proportion with the augmentation of the
animal substance.

The cohesion of two or even more Arcellina by means of their gelatinous
substance, and often with the near approximation of the orifices or mouths
of their shells, has been remarked by many observers, who for the most part
have pronounced it a sort of " conjugation," a true reproductive act. Cohn
has indeed designated it " copulation," and states it to be a general phe-
nomenon among Hhizopods. He affirms that he has many times seen two
Diffiugioi with the mouths of their shells so firmly connected, that strong
shaldng of the water about them failed to detach them ; and that likewise
one shell was often empty, and the contents of the two aggregated into a
globvilar mass in the other. Leclerc, the first describer of Difflugice, in 1815,
noticed a like cohesion between two individuals of Diffiiigia HelLv ; and Cohn,
moreover, is able to confirm the fact represented by Perty of the cohesion of
a brown and of a pale shell together.

Schneider has likewise noticed this adhesion of two animals, and thus
speaks of it : — " Tine double animals of Diffiugia Enchelys are fi'equently
met with (XXI. 19/), two bodies with membranous cases and nuclei being
attached to a common foot. The foot veiy often consists only of a thin
thread, but in other cases it exhibits aU the forms which have been described
as belonging to the foot of the simple animal. Eoth bodies are well filled
with food. Three, four, or five bodies are frequently seen hanging together
in the same manner ; these, however, are by no means in the same plane,
but stand out from the foot in various dii-ections. If these animals are ob-
tained in considerable numbers, the formation of these colonies by gemmation
may easily be observed. The foot is seen gradually to increase in size, and
acquire an oval form. A new investing membrane and nucleus are then
formed. The offset is always equal to the parent-animal in size. like the
foot of a single animal, the common foot of two or more is, as might be
supposed, still in a condition to form offsets." This adhesion Schneider
prefers to consider an act of gemmation rather than of copulation, and sup-
poses its occiu-rence among other Ehizopoda. He adds, " with Perty and
Cohn I have also seen a pair of the Arcella vulgaris attached to one another
by their openings, of which one (as was obsei-ved by those naturalists) was
provided with a white, the other "with a yellow shell. The white shell is
probably newly formed, and therefore indicates the yoxmg specimen produced
by gemmation from its companion."

An aggregation of the animal contents of a Monothalamous shell, such as
Cohn noticed in one of the two coherent Difflugia and attributed to an act
of conjugation, Schultze has seen in Rhizopods, quite independently of that
phenomenon. In Lagynis Baltica, he states he has frequently seen the con-
tents collected into a ball, ha%Tng a clear speck in the centre, and situated at
the posterior end of the shell, without trace of extended fibres ; and he adds,
" the origin of this globulai- mass may bo followed in a great number of
individuals. The posterior portion of the transparent body of the actively-
moving animal gradually becomes darker, OAving to the advancing develop-
ment of numerous molecular and strongly refracting particles. In the midst
of this dark portion a clearer spot is always visible, although it cannot be
isolated or more intimately examined. By degrees the dark portion en-
croaches upon the entire substance of the body, and at last fills up the whole
posterior portion of the shell, the body of the animal tlius seeming to shrivel
up into the ball-Uke mass described." This process, observed in numerous

OF THE PKOXOZOA. HHIZOPODA.

216

individuals in different stages, Schultze never saw accompanied by a con-
nexion between two animals ; and he was not able to discover what subsequent
changes awaited the spherical body produced.

The phenomenon just considered appears to us to be analogous to the
encysting process recounted by Schneider in the case of Amoeba, and by
Stein in so many Cihated Protozoa.

T^vo other probable modes of reproduction are briefly noticed by Schneider,
but require to have theu' existence confirmed by further observations. I
have observed," he says, " another mode of propagation in our Diffiugice ;
and although my observations have certainly not been frequent, they have
been sufficiently satisfactory. After I had kept a great number of these
creatures for some weeks in a clayey sediment, the substance of the body
in all the individuals contracted into a baU. All foreign substances had
previously disappeared. The ball, which had a fatty outhne, then divided
into two and foui- parts ; but the nucleus could not be traced during this pro-
cess (XXI. 19 d, e). This investing membrane fell to pieces, and the little
spheres which may perhaps be regai'ded as four quiescent spores, were no
more to be seen.

" "Whether another circumstance observed by me has any connexion with
the reproduction of Diffiugia must be ascertained hereafter. In all the
individuals of Difflugia contained ui one vessel, the substance of the body
became converted into granules closely packed together, the form and the
investing membrane being retained (XXI. 19 c). I often saw these granules
in quick molecular movement in the interior of a sac, which appeared to be
formed from the outermost layer of the body, but I watched in vain for any
issue to this ; after moving about for about half an hour, the' granules always
became quiescent again."

A note by Perty must not be omitted, although no considerable importance
can be assigned to a sohtary and ambiguous observation. That naturalist
tells us he " once saw two round motionless animals within an Arcella vul-
garis, each having a much greater diameter than the mouth of the shell con-
taining them. "Were these," he asks, " young beings to be set free on the death
of the parent and the breaking up of the shell ? " A somewhat similar fact
is recoimted by Schultze of Gh'omia Dujardinii, in one large specimen of
which he found several oval bodies enclosed possessing a firm envelope and
gramdar contents, and representing in every respect young Gromia, except
in having no evident opening iti their shell, which, however, may possibly be
formed when set free fi'om the parent (XXI. 18).

That the purpose of the nuclear bodies in Ch'omta oviformis (see p. 211) is
not connected with the function, Schultze feels compelled to assume, piinci-
paUy from the absence of such nuclei in Rhizopoda generally, and fi-om his
having failed to observe their undergoing those changes known to occur in
true nuclei when the generation of new individuals is in progress.

Young Arcellina, when fii'st recognizable as such, have the general form of
older individuals ; but their shells and tissues are much more transparent and
at first colouiicss and without granules. But it is very probable that the

yoimg of many Arcellina, when first thrown off from the parent, are naked

destitute of shell, — a view supported by an observation of Cohn, who records
having seen, amid the slimy matter about li\'ing Difflugice, a lai-ge number of
pecuUar animalcules consisting of a contractile greyish or broAvn finely-
granular substance, about -Jj^th of a line in diameter and upwards, of a roimd
ovoid, or angular outUne, and having a muco-gelatinous envelope, through but
chiefly at one end of which several fibres were extended. At a stiU ea'rUer
ponod these young beings may therefore be presumed to have been mere

216

GENEEAL HISTORY OJF THE INFU80EIA.

sarcode-likc particles or minute Amcebce. If this bo so, some ground may be
said to exist for the hyi^othesis of certain naturalists, who esteem the Arcellinu,
and even the Foraminifera, to be a more advanced stage of existence of the
simple naked Amoebina.

Schneider hints at the possibility of a still greater transformation in the
case of his Difflugia Enchelys. He writes—" A. Ehizopod occurred in com-
pany with Polytoma (see p. 136), the description of which -will show how veiy
readUy it might be supposed to be produced by a metamoi-phosis of the latter
animal. Unfortunately I cannot confirm this supposition, and must confine
myself to recording the fact."

Foraminifera. — It is very questionable whether the Idany-chambered Ehi-
zopods can reproduce themselves by offshoots after the manner of Amcebina,
and Monothalamia ; and, in short, nothing certain is known as yet of the
modes of propagation of this family.

A group of figures occurs in Schultze's Ulustrations of Pohjstomella (XXI.
39) which bear on this point of the possible production of new beings by de-
tachment of sarcode matter. The description of the figures informs us that
some of the sarcode-globules, separated from the chief mass by pressure, have
the tendency and power to throw out from themselves contractile variable
processes. They exhibit a finely-granidar delicate semifluid tissue, contain-
ing many flat globules and large coloured vesicles. Other portions, pressed
from the general mass, are almost exclusively composed of colouring-particles,
derived from the inmost part of the shell; such become entirely free, or
otherwise continue attached by a sort of pedicle.

In the following examination into the modes of development of Polyiluilamia
we are greatly indebted to Schultze's valuable monograph. Dujaxdin men-
tions seeing in some Ti-vMatulince the grouping of the contents of the cham-
bers into spherical masses, comparable to the green bodies in Zyynema.
Schultze, moreover, encountei'ed, in a deposit of living Foraminifera, along
with numerous empty shells of Rotalidce, several whoUy or partly filled with
black globules, the appearance of which suggested their connexion with the
reproductive process. Eepeated observation showed that these globules
differed in size, but mostly had the diameter of the siphon intervening be-
tween the several chambers, or of that of the opening of the last cell. They
occupied either every segment of the shell, when those of the innermost were
smaller than those of the outer compartments, or otherwise they occurred in
only one or two of the ultimate chambers. Every intermediate condition
was met with between these two extremes. The globules were composed of
a collection of dark molecular corjrascles not enclosed by a membrane, but
proved by pressure to be an aggregation, held together by some sort of
deKcate tissue. They were unacted on by sulphuric, nitric, and by hydro-
chloric acid, and by boiling alkalies.

The ordinary animal substance coexisted in some of the chambers of an
animal when others were occupied by these black balls ; but in such instances
no outstretched fibres were seen. These structures must be derived either
from ^vithout as foreign matters, or otherwise be the result of a metamorphosis
of the sarcode matter. The former supposition is discountenanced by their
appearance, by their resistance to reagents, and theii" presence even in the
inmost chambers. On the latter supposition they are cither the result of
decomposition of the substance, or they are jihysiologicid products, probably of
the trunsforniatiou of the entire body into germinal masses. The former origin
is opposed by the direct observation that such bodies have never been en-
countered among Foraminifera in coTU-se of brcaldng up or of decomposition.
-As to the second mode of origin, they bear an analogy to the germinal

OP THE PROTOZOA. lUIIZOPODA.

217

elements of Ch-egarinai, viz. to the Navicellce developed from the contents
of those animals, and to the brood of germs developed out of the contents of
an encysted Vortkella : and it may so happen with the Foraminifera, that
theii- entire substance is resolved into germs ; indeed, a progressive formation
of such germs is intimated by the circumstance of the ultimate chamber being
the last to become completely emptied.

Although, therefore, the figure and size, the peculiar and successive empty-
ing and distribution, the evident periodical appearance in the spring, and the
analogy of other Protozoa speak for the hypothesis of these globules beiug
reproductive germs, it must, on the other hand, not be concealed that theii-
peculiar composition out of granules imperfectly bound together aud enclosed
by a membrane, and their remarkable resistance to the strongest acids and
alkalies, are facts opposed to this supposition. Hoping to elucidate theii-
purpose, Schultze, in some few cases, isolated those shells filled with these
black balls, but, after keeping them several weeks, could discover no change
in them.

Ehrenberg surmised that the Polythalamia propagated by ova, and thought
he perceived in them a sexual apparatus. On the suirface of the shells of
some samples of Geoponus (Polystomella) and Nonionina, from Cuxhaven and
Christiania, he discovered stalked, yellow, membranous sacs, which he repre-
sented to be ova-sacs. When first thrown out they were soft and small, but
soon swelled up and hardened in the water. Schultze also met with many
specimens of Geoponm, at Cuxhaven, having CothurnicB afiixed to their shells,
and of a yeUow colour, which he behoves Ehrenberg mistook for ova-cases.

Being so unsuccessful by direct observation in his attempts to detect the
method of reproduction among Foraminifera, Schultze endeavoured by an ex-
amination of these beings ia their earhest recognized form to gather some
knowledge of it. The smallest and youngest beings he met with belonged to
the famihes Eotalido} and Milioliclce. Those of the latter family have a nou-
porous shell, and a spherical figTire exhibiting the commencement of the spiral
winding which eventually extends to several turns (XXI. 20 a, h). The sheU-
contents are quite colourless, and present few granules. As the spiral winding-
advances, the contents of the first-formed orbicular cell acquire a darker coloiu-
from the appearance of fat-drops and sharply-defined proteine corpuscles ; and
the shell simultaneously assumes the characteristic yeUow colour. The differ-
ence in size of the primary cell in difierent species is remai-kable. StiU younger
forms of Rotalidce occurred to him, 0-01 of a hue in diameter, spherical, and
colourless, with a delicate glass-like calcareous shell, through the fine open-
ings of which fibres protruded. Others also, entirely colourless, had a second
chamber superposed on the first, or even three or four ; but in the latter
instances the characteristic yellow hue made its appearance, and rapidly in-
creased on further growth (XXI. 31). A sti-iking variety was, moreover,
remarked in the size of the first chamber, even in the same species ; the
dimensions of the second and third cells were detennined by those of the
first. This great variation in size considerably lessens the possibility of the
certain specific detemunation of young specimens.

From these researches it follows, that in MiUoliiUt and Rotalido}, and pro-
bably in aU other Polythalamia, the first appearance of the animal is in the
form of a colourless spherical mass, invested by a delicate calcareous wall —
the mass consisting of a homogeneous, sparingly-grnnular Amoiha-hoiiy This
first-formed cell has the faculty of producing others lilco itself from those
portions of its sarcode substance.

Of the manner in which successive chambers are formed, wo learn from
Dr. Carpenter that the addition of now zones (in the Polythalamia) probably

218

GENEEAl HISTOKY OF THE INJFUSOaiA.

takes place by tlie extrusion of the sarcode through the marginal pores, so
as to form a complete annulus, thickened at intervals into segments, and nar-
rowed between these into connectiag stolons, the shell being probably pro-
duced by the calcification of their outer portions.

Since the above account was written, Schultze has produced a supple-
mentaiy sheet detailing further observations on the development of Forami-
niffera (Bericht der Naturforschenden Gesellschaft in Halle, 11th August,
1855).

Having met "with some large specimens of Triloculina in diameter and
■without a tooth in the oral aperture, he kept them for a length of time under
observation. Those which remained adherent to the sides of the glass vessel for
eight to fourteen days mostly became invested with a brownish sUmy matter,
which more or less completely obscured the view of the external characters of the
shell. After some more days had elapsed, the lens brought into view a num-
ber of small, round, sharply-defined corpuscles, which loosened themselves from
the soft enveloping mass, and gradually diverged from one another Tintil some
forty were visible. On removing these, and placing them under the microscope,
they proved to be young Miliolidce, with their process outstretched. Inter-
nally, neither vacuoles, cells, nor contractile vesicle, nor a nucleus could be
detected.

The brief abstract of Dr. Carpenter's elaborate essay (read before the Royal
Society, 1855) furnishes us also with the following memorandum of his views
regarding the reproduction of Foraminifera, with especial reference to Orbi-
tolites, " He is only able to suggest that certain minute spherical masses of
sarcode with which some of the cells are filled may be gemmxdes, and that
other bodies enclosed in firm envelopes which he has more rarely met with, but
which seem to break their way out of the superficial cells, maybe ova." Mr.
Jeffrey's views (^Proceedings of Royal Society, 1855) do not quite coincide.
Dr. Carpenter's " idea of their reproduction by gemmation," he says, " is also
probably correct, although I cannot agree with him in considering the granules
which are occasionally found in the cells as ova. These bodies I have fre-
quently noticed, especially iu the Lagenoe ; but they appeared to constitute the
entire mass, and not merely a part, of the animal. I am inclined to think
they are only desiccated portions of the animal separated from each other in
consequence of the absence of any muscular or nervous stracture. It may
also be questionable if the tenn ' ova ' is rightly applicable to any animal
which has no distinct organs of any kind. Possibly the fry may pass through
a metamorphosis, as in the case of the Medusce"

Of the many Amoehce seen in company with Foraminifera, the A. porrecta
is particularly remarkable, and might easily pass for one of the latter when
young and destitute of its shell ; for its processes resemble those of Miliolidce
and Botalidce in delicacy and extensibility and iu the cun-ent of granules
which passes through them. This circumstance suggests the possible deriva-
tion of testaceous Ehizopoda from the naked forms ; and if we recall to mind the
black globules surmised to be germs, their primary transformation into Amosbce
is imaginable, and the whole cycle of development of Foraminifera becomes
thereupon explicable. " However, I must," says Schultze, " confess that this
change of the black spheres into Amceha: is a fiu'ther argument against their
nature as germs, since between these granulai- bodies, so unaffected by che-
mical agents, and Amoeba; no intermediate link is discoverable.

Of 'rnn Shells of Testaceous Ehizopoda.- a. Shells of Monothalamia. —
The family Arcellina (Ehr.) corresponds in most points with the section Mono-
thalamia of Schultze. The 13crlin Profossoi-, hoAvever, beUeved that his family
Arcellinn and tho Pohjthalamia belonged to entirely different classes of ani-

OF THE PROTOZOA. RHIZOPODA.

219

mals, because, as lie supposed, the Polytlialamia are aggregated animals with
calcareous shells, and the ArcelUna solitaiy animals with a sQicious testa.
Subsequent researches prove, on the contraiy, that all these diiferential cha-
racters are wanting. Each foraminiferous shell contains a solitary inmate ;
and although, as a rule, of a calcareous composition, yet a genus, Pohjmor-
phina, is poiuted out by Schultze, which, as in the instance of Diffiugia, has
its testa made up of coherent sUicious particles (XXI. 38). Besides all this,
the shells of ArcelUna are not silicious, but of a chitinous natui-e, and the
basement membrane in which the earthy matter is deposited in Foraminifera
is the same. These circumstances, together with the homology in the animal
contents both of Monothalamia and of Polytlialamia, the absence of the hypo-
thetical polygastric organization in the former, and of the imaginary internal
structures in the latter, render Ehrenberg's distinction of the two families as
separate classes im tenable.

The Aixellina of Ehrenberg, and the Monothalamia of Schultze, do not en-
tirely accord in respect to the genera grouped under them. Ehi-enberg in-
cluded in his family the genera Diffiugia, Arcella, Cyphiclitim, and SpiriUina.
The last-named genus departed much fi-om the others by having a marine
habitat and a convoluted, spiral, porous shell,- — its only real relationship, it
would seem, being comprehended in the one assigned featui'e, its silicious
lorica. On the other hand, Schultze (see tabular view of his system, p. 241),
by not employing the chemical constitution of the shells as a distinctive cha-
racter, includes among his Monothalamia calcareous, membranous (chitinous),
and such silicious shells as are exemplified by Diffiugia. The essential cha-
racter employed is that of the unilocular chamber ; for the other nearly general
feature, viz. the presence of one considerable orifice, is departed from in the
instance of the porous shell of Orhulina.

The shells of Monothalamia are of a more or less spherical figure ; some-
times they are ovoid (XXI. 11, 12, 16) or pyriform (17), at others compressed
in one or other direction (XXI. 8), and even at times in opposite dii-ections, so
that everal faces are produced. Thus in the genus Diffiugia the spherical out-
line prevails (XXI. 10) : the shells are globose, or subglobose, or elongated in
a pear-shape (XXI. 17), or in a club-like (clavate) manner; in Arcella they
are frequently compressed, and assume a more or less discoid figure, mostly
convex above and flat beneath (7, 8, 9). In Oromia, again, the ovoid or o-lo-
bular shape is diversified by the elongation of the portion about the mouth
of the shell into a sort of neck (16). In Lagynis (Schultze) this tapering of
the oral end developes a retort-shaped shell. In Squamulina (Schultze), again,
the testa resembles a plano-convex lens. An exceptional form is described
by Ehrenberg, imder the name of Arcella disphoira, as oblong, ahnost divided
into two by a central constriction. The fii-st impression would be that the
supposed species was no other than two animals coherent by the mouth of the
shell ; that such, however, is not the case is inchoated by the next clause of
the description— that one segment is nearly occupied by the large foi-amcn
Another example of a remarkably-formed shell is afforded by Ci/phidium
(XXII. 24-27), which Ehrenberg states to be cubical, with largo protuber-
ances, giving it in some positions a four-sided or an irrogidar figure. Again
in the genus SpiriUina (Ehr.) (XI. 37) and Cornuspira (Schultze) (icXI 25^'
we have examples of spirally-roUod equilateral shells, hke those of Plaiwrbis
In consistence the shells of most ArcelUna are firm, with a degree of flexibilitv
and elasticity, and are composed of a dense membrane proved by its ehemienl
lu'operties to be of a chitinous natiu'e. Tliis shell not only resists the actio^
ofboihngsolutions of the caustic alkalies and of vinega\-, but also concen-
ti-ated nitric and chloric acids, and a mixture of the two, also chromic a( d

220

GDNEBAL niSTOEY OP THE INFU80EIA.

in the solution of wMch chitine itself is dissolved. Further the shell is dis-
solved in sulphuric acid, and, unlilce cellulose, is not coloured blue by this acid.
Such are the chemical relations of the testa of Gfromia according to Schultze ;
and such we may presume with him are those of the freshwater genera
Arcella, Euglypha, and Trinema.

The shells of Difflugia are peculiar by being composed in many species of
a softer substance, to which various foreign particles, shells of Diatomece, grains
of sand and the like, adhere and thereby furnish an accidental or supple-
mentary shield to the animals (XXI. 17). The substance on which those
accidental matters are affixed we may presiune to be chitinous, but not con-
densed or hardened as iu the true testaceous forms. Schultze is disposed to
think that, besides merely agglutinated silicious particles accidentally, as it
were, appropriated, the investing tunic has actually the power of secreting
silicious molecules, represented by the smallest and most intimately adherent
granules of the testa. He would also extend this hypothesis to the siUcious
polythalamous shells, illustrated by PolymorpMna silicea (XXI. 38) and
another newly- discovered species.

Cohn apparently saw young Difflugice in the act of bmlding their shells.
These young beings consisted of a mass of sarcode siuTounded by a muco-
gelatinous envelope, through which fibres were protruded in different direc-
tions. These processes, by retraction, brought to the surface of the animal
various foreign particles, which had become af&xed to them, and were then
imbedded in the mucous involucre. At length all other pseudopodes, save
those from one extremity, were permanently withdrawn, and the exterior of
the animal was clothed with a layer of silicious particles, grains of sand, shells
of Cyclotella, and of other Diatomece, many of them of a blackish or brown
colour.

Dr. Bailey indicates an exceptional tunic in a Ehizopod, having much of an
Amceba-Yike character, which he names Pampfiagus. It would seem to be
enveloped by an integument, which, although resistant, admits of an immense
modification of figure, both from external and intei-nal pressure, and offers no
impediment to the animal transfixing itself, jiist as if it were a completely
homogeneous jelly. " These creatiu-es," says their discoverer, " connect the
genus Amoeba with Dvffiugia, agreeing with the first in the soft body without
shell, but differing in having true feelers or rhizopods confined to the interior
part of the body." Just as in Diffiugia, they are limited to the region of
the moiith. From this last-named genus, " and from the whole family of
Arcellina, these forms are distinguishable by having no lorica or shell." A
very similar tunicated amcebiform animal is described by Dujardin imder the
name Oorycia (A. 8. iV. 1852), which, although clothed by a membranous
envelope, can be twisted and folded in every direction by the movements and
contractions of the animal, and permits the extrusion of processes from any
part of its suiface. In this respect it differs from the Pamphagus of Bailey,
and certainly exemplifies a peculiar phenomenon, which, in the case of the
usual variable processes -with circulating contents, would not be conceivable,
but become so upon the explanation of Dujardin, that they do not contract
on adhesion to the surface on which the animal moves, nor glide along it in
the ordinary manner, but remain free, and, as we are told, seem only to sen-e
to change the centre of gravity of the animal. " It must, therefore," says its
describcr, " form a now genus of yLmosblna," intoraiediato between the naked
Amoebic and the Arcellina ; and in imother direction indicating an aUiaucc
with the Noctiludda.

With reference to these peculiar beings, it is Avorth while to boar in mind
the account given by Colin of the development of young Difflngin and tlio

OF THE PliOTOZOA. RHIZOPODA.

221

progressive formation of the shell. To recall the particular points of interest,
in the primary stage the Difflugia was seen covered by an integument, but
having processes extruded fi-om various parts of its surface, so far resembling
the Corycia of Dujardin, — whilst in a later stage all processes were withdraw,
except those at the one end where the single large orifice or mouth is placed,
and thus came to resemble the Pamphagus of Bailey.

Calcareous-sheUed Monothalamia are represented by the genera Squamu-
lina, Orhulina, and Comttspira. Such shells are brittle, and in aU essential
featiu-es resemble those of the next-considered family, the Foraminifera.

The shells of Monothalamia are generally coloured. When seen, as they
often may be, empty, they have an orange-yeUow, a brown, or brownish-black
tint. This colour is acquired by age ; the yoimger the being the less is it,
cceteris paribus, coloured. In the youngest, as before noticed, the whole sub-
stance and its commencing envelope are quite colouiiess. Most shells are
also translucent or diaphanous when empty ; but in others the colour is so
deep, that, when filled, scarcely anything of the contained substance is dis-
cernible through them. Thetestse of Bijflugice are mostly opaque. The sur-
face of the shells is subject to numerous modifications. Occasionally it is
uniformly smooth ; but many, which so seem when occupied by the animal, are
found when empty to be reaUy finely sculptirred (XXI. 11-15).

Arcella hyalina is represented by Ehrenberg to have a smooth and colour-
less testa ; A. vulgaris and A. clentata, one superficially divided into facettes ;
A. aadeata, A. spinosa, and A. cauclicola, a delicately hispid shell. Where
the intersecting lines or ridges are not sufficiently developed to produce fa-
cettes, they give rise to areolas and an areolated or reticulated surface. The
surface is beset with rounded tubercles or eminences in Euglypha tuherculata,
and by spirally-disposed polygonal depressions (alveola) ia Euglypha alveo-
lata (XXI. 11). In Diffiugia acanthophora (Ehr.) (XII. 64), the surface
looks as if covered by scales laid on in an imbricated manner and in a spiral
direction. The same species and Euglyplia. alveolata (XXI. 11) afford instances
of testae armed with large and strong spines. This same Diffiugia presents
likewise an example of the mouth of the shell being strongly serrated. Several
Arcellina have small depressions or pits on their surface, which at fii-st sight
resemble pores, e. g. Arcella OTcenii ; and both this species and A. vulgaris,
according to Perty, present very numerous striae diverging from the centre of
the closed end, and concentric circles, the outermost of which in Arcella Olccnvi
are dentatcd, and foUow the stellate expansions of the shell (XXI. 15).

Among Difflugioi the shell is more often rough from the adhesion of parti-
cles of sand and of other extraneous substances {c. g. in D. proteiformis, D.
gigantea, D. acuminata), but in others consists of a smooth membrane as in
D. Enchelys, D. ohlonga, and D. globulosa. Moreover, Ehrenberg enumerated
D. ciliata, D. acanthophora, and other species as having an areolated surface
D. ampulla as punctated, D. dryas and D. reticulata as cellular, D. Bructerii
as rugose, and D. striolata as striated. He further states that D. ciliata has
a bristle or cirrus in the centre of each posterior areola.

Where spines or other elevations of the smfacc — or, in fact, marldno's in
general, exist— they may not be uniformly disposed, but be produced in lar"-er
number or of larger dimensions in some parts than in others. Thus Ehrenberg
signalizes an in-egular disposition of the spines in Arcella aculeata ; and not
uncommonly such processes are produced only from the vicinity of the mouth

These examples ^vi^ sufficiently illustrate the diversity of surface preva *
lent among monolocular sheUs ; but these shells moreover differ as romari-
ably among themselves in size, figure, and chai-acter of the margin 'ami
likewise in the i-elative position of their mouth, foramen, or orifice These

222

GENERAL HISTOEY 01'' THE INFT780EIA.

differences supply specific and generic characters of much value by reason of
theu- constancy. Where the mouth has an even uninternipted margin, it is
said to be " entire." Its normal figm-e may be considered circular (XXI. 9).
However, in many instances it is irregular (XXI. 15), or a projecting portion
encroaches on it (XXI. (i). In Difflugia clepressa and D. gigantea it is uneven ;
in Arcella lunata, semilunar ; in Difflugia ampulla, ovate ; in Sphenoderia, so
contracted as to be linear. Still more frequently the margin of the aperture is
dentated or spinous : examples occur in Diflugia denticulata, D. Icevigata, D.
oligodon, D. acanthopliora (XII. 64), and D. ciliata, in Arcella dentata and
in Euglyjjha. The symmetrical position of the mouth is wanting in several
species ; and Schlumberger elevated this variation to the importance of a ge-
neric distinction. The obliquity of the aperture — its position out of the median
line — is noticed in Arcella Americana, A. constricta, A. ecornis, and in A. lu-
nata, also in the genus TrinemM (Duj.) and in Cyphoderia (Schlumberger).
When the mouth appears formed by the mere incompleteness of the outline of
the shell, and is without a neck or deep margin, it is often said to be truncate
— in fact, the oral end of the shell is truncated or abruptly cut off by the
orifice.

The shells of Arcellina may be fractui'ed by pressure when the contained
sarcode matter escapes through the fissiires, extending itself in lobe-Hke pro-
longations, which take on the characters of ordinary expansions (XXI. 7).
Since the opacity of the shell is generally an impediment to the observation
of the contained matter, its rapture by pressure, or its partial solution by
some reagent, as sulphuric acid, which acts upon the ehitinous basis, must
be resorted to in order to discover the natui'e of the animal mass within.
With or without such preparation, it is not unfrequently seen that the living
mass is not uniformly adherent to the inner surface of the shell, but is, on
the contrary, detached at different parts, leaving interspaces between it and
the testa, varying in size and number. ITiese vacuities may possibly arise
from the detachment of the soft matter by reason of the quantity poirred out
from the mouth of the shell, or otherwise fi-om the formation of vacuoles at
those points, just as often happens on the surface of an Amoeba.

b. Shells oe Poltthalamia oe Foeaminifera. — These have a great diver-
sity in figure and size, and are often very beautifully coloured and sculptured.
From the resemblance of many to the shells of Cephalopoda, especially to those
of Nautili (XXI. 28), they were for a long time ranged along with those
highly-developed Mollusca. The shells of Polythalamia consist of a greater
or less number, according to age and species, of communicating chambers or
cells, aggregated together or superposed on one another in different ways,
the mode of disposition, however, varying within certain limits even in the
same species. Thus Dr. Carpenter, speaking of Orhitolites, says {Proceedings
Royal Society, 1855), — " Starting from the central nucleus, which consists of a
pear-shaped mass of sarcode nearly surrounded by a lai"ger mass connected
with it by a peduncle, the development may take place either on a simple
or upon a complex type. In the former (which is indicated by the circular
or oval foi-ms of the cells, wliich show themselves at the surface of the disk,
and by the singleness of the row of marginal pores), each zone consists of but
a single layer of segments, connected together by a single annular stolon of
sarcode, and the nucleus is connected with the first zone, and each with that
which surrounds it, by radiating peduncles proceeding from this annulus,
which, when issuing from the peripheral zone, will pass outwards thi'ough the
marginal pores, probably in the form of pscudopodes. In the complex type,
on the other hand (which is inchoated by the narrow and straight-sided form
of the superficial cells and by the multiplication of tho horizontal rows of

OF THE PROTOZOA. RHIZOPODA.

223

marginal pores), the segments of the concentric zones are elongated into
vertical columns, with imperfect constrictions at intervals ; instead of a single
annular stolon, there are two, one at either end of these columns, between
which, moreover, there are usually other lateral communications, whilst the
radiating peduncles, which connect one zone with another, are also multiplied,
so as to lie in several planes. Moreover, between each annular stolon and
the neighboui-ing siuface of the disk, there is a layer of superficial segments
distinct from the vertical columns, but connected with the annular stolons ;
these occupy the nai-row elongated cells just mentioned, which constitute
two superficial layers in the disks of this type, between which is the inter-
mediate layer occupied by the columnar segments.

" These two types seem to be so completely dissimilar, that they could
scarcely have been supposed to belong to the same species ; but the examina-
tion of a large number of specimens shows that, although one is often
developed to a considerable size upon the simple type, whilst another com-
mences even fi'om the centre upon the complex type yet many individuals,
which begin life and form an indefinite number of annuli upon the simple type,
then take on the more complex mode of development."

Each ceU is occupied by the animal sarcode substance — sometimes not
completely, so that intervals exist at points between the contained matter
and the enclosing calcareous wall, just as in Monothalamia. The first cell pro-
duced, about which all others are arranged and may be considered ofi'shoots
or dependencies, is called the piimary or piimordial cell ; and in it is con-
tained the mass of condensed sarcode which Dr. Carpenter calls the nucleus.

The link-like portions connecting one chamber with another are called by
Schultze bridges (Briicken) or isthmi, by Ehrenberg siphons, and by Car-
penter ' stolons.'

In chemical composition the shells of Polythalamia are calcareous, with the
exception of those of Polymorjohina silicea, which, like those of many Diffiugioe,
are composed of small granules and tablets of sUex. Schultze observes that,
in addition to this species, Spirulina agglutinans and Bignerina agglutinans
have their surface covered by adherent grains of sand, to give it the fii-mness
and resistance provided for in other forms by their shells. The consequence
of theii' calcareous composition is, that the shells are hard, brittle, and opaque,
and their contents only visible so far as pro traded in the form of processes.
To examine, therefore, the animal matter, it is necessary to crush the shells
or, better, to carefully remove some portions and so expose the subjacent tissue
to view ; or they may be acted on by dilute acid, which dissolves out the
earthy matter, leaving the transparent organic basis of the testa. Dujardin
employed dilute acid mixed with alcohol, which contracted and rendered
the sarcode substance harder, and gave it the appearance, in the many-
chambered cells, of laminated or lobulated masses connected together by
thinner portions.

When the calcareous earthy matter is dissolved out of the shells of Forami-
nifera, the organic matiix or basis is left as a transparent membrane, retaining
the precise form and markings of the complete shell, and perforated by the
characteristic pores. Its chemical relations are those of the membranous testa
of Gromia. In thin shells the organic matter is in relatively greater abxmd-
ance than in the thick ones. Acids produce an active effervescence, and so
prove the presence of carbonate of Kmc as the principal mineral constituent
Schultze has also detected the presence of phosphate of lime, at least in some
shells, viz. in those of OrhicuUna adunca and Polystomella strigilata

Tlio sheUs of Polythalamia are commonly white, when viewed bv reflpf>f^.d
light, and when emptied of their organic contents. When the latter remain.

224

GENEEAL HISTOHY OP THE INFUSOBIA.

a reddish- or yellow-brown colour is produced. Sufficiently transimrent
specimens and opaque fragments, viewed by transmitted light, exhibit either
a glass-like (vitreous) colourless appearance, or have a brown hue. Examples
of the latter condition are aiForded by all solid and not finely porous shells, by
MilioUdce, Ovulince, and others. Moreover, the youngest, thinnest, and most
transparent shells are rendered visible by their apparent intense brown colour.
Amongst porous species are some, such as Orhiculina and Sorites, which have
the brown colour only in stripes. Lastly, Schultze has never met with the
peculiar yellow, red, and violet tints mentioned by D'Orbigny in some
Rotalince, Mosalhice, and Planorhulino}.

The figure assimied by various Polyihalamia is extremely varied, but is
nevertheless reducible to certain types. We will restrict ourselves to a brief
description of the primary forms established by Schultze ; these are thi-ee in
number: — 1. In which the chambers or cells axe superposed on one another
in a straight seiies. 2. In which they are disposed in a spiral manner;
. and, 3. in an irregular fashion.

The Nodosaridce, which have their cells placed one on another in a simple
row, are examples of the first type ; the Spiroculince of the second ; and the
Acervulince of the third (XXI. 34).

In spiral shells the chambers may be rolled in one plane, so as to form a
symmetrical shell with opposite sides aKke, e. g. in Cristellaria, or, otherwise,
in an asymmetrical mode, so as to produce a shell like that of the common
snail {Helix), e. g. Rotalia and Roscdina (XXI. 25-28). This latter variety
may be so modified by the great elongation of the spiral, as to produce an
elongated conical outline, as in (Jvigerina and Bulimina, when the chambers
above and below each other may present an alternate arrangement. Other
varieties of the spii'al are exemplified in Orhiculina, Alveolina, and Nonionina.
In many instances a simple or regular spiral disposition is commenced in young
animals, which is departed from variously as they attain the adult condition
and characters. Thus in PlanorbuUna the regular spiral is transformed
eventually into a completely irregular form. Lastly, the Acervulince con-
sist of spherical or spheroidal cells aggregated into formless colonies.

With reference to the minute stnictuje of the shell. Prof. Williamson
(Report of British Association, 1855, p. 105) recogTiizes three principal
types : viz. — " 1. The hyaline, generally consisting of a transparent vitreous
carbonate of Hme, with, usually, numerous foramina. 2. PorceUanous, white,
opaque, and rarely foraminated. 3. The arenaceous, mainly consisting of
agglomerated grains of sand." Schultze makes two types : in the one, the
shell is perforated by numerous fine pores or canals; in the other, it is
homogeneous and solid. The contents of the second series ai-e brought into
relation with the external world by means of one large opening, or by many
smaller ones collected in one group. This division corresponds, in the main,
with that of Prof. Williamson, except that the German naturalist has omitted
to notice, as a third series, those shells constituted of a membrane covered by
extraneous particles of sand and the like.

The size and distribution of the foramina, along vnth. other stnictiu-al pecu-
liarities, aff'ord the best specific characters. To examine those details the
shells must bo viewed by transmitted hght, and by high powcre. The thick-
waUcd opaque Foraminifera are best explored, as Ehrenberg first pointed out,
after being soaked in some strongly refracting varnish, either entire or when
cut into thin sections.

The dimensions of the canals vary in different species from -0003 of a line (a
scarcely measurable size) to -005 of a Kne. They are of cxtraorcUnary fineness
in PolystomelJn sfrigilafa, in P. gihhn, and P. venusta, wliilst in Orhxdina

OP TUK rilOTOZOA. KHIZOPODA.

225

universa and in Acervulina glohosa (XXI. 35-37) they obtain their greatest
diameter. In the latter, and in Qlohujerina, the canals dilate towards the
surface, and are consequently funnel-shaped (infimdibuliform). In a few
instances two different sorts of pores exist, as in OrbuUna universa and
liosalhia varians, the finer kind being more abundant.

A peculiar sort of slits is chai-acteristic of the genus Polijstomella ; that they
completely perforate the shell is shown by sections. They are largest in F.
stngilata, and in P. gihba appear to be only shallow excavations.

Besides the openings named, the surface of the shells often presents regularly,
disposed eminences or elevated lines. In Polystomella strigilata and P. venusta
(XXI. 28-30) there are hemispherical or conical eminences, perforated severally
by a fine opening. In Textilana pkta elevated lines ai'e arranged around the
Avidely-separated pores, so as to produce an elegant design (XXI. 25). Lastly,
many shells have a spinous or stellate appearance, from the prolongation of some
canals into long and fine projectiag tubes, or from that of the whole of them
into thick processes. Illustrations are afforded by Rosalina Imperatoria, Cal-
carina, and particularly by Siderolina cahitrapoides.

Cai-ter has described a greenish, perishable, organic membrane as investing
the entire sm-face of the shells with all their irregularities ; and d'Archiac
has assumed this to be the secreting membrane of the calcareous matter.
Schultze, however, has failed to detect such a "stiiicture in every specimen he
has examined, whether in a Uving or in a dried condition ; and he observes
that, even if this membrane does exist in certain cases, there are abundant
facts to prove that it is not the secreting organ of the shell.

The foramina are, as a rule, uniformly distiibuted over the shells, those
parts only being free which are placed immediately above the partitions
between adjoining cells. Exceptions, however, occirr. Thus, in the inequi-
lateral Rotcdidce (XXI. 33) and their allies, the under or umbUieal side has
fewer pores than the upper. Also, in some of the thick-shelled species the
position of the. subjacent septa are not indicated by the absence of pores.
The long winding canals pass in different directions, unite, and appear on the
surface in groups, producing a complex wavy pattern on the surface, as in
many Calcariiice.

The partitions between the several cells are perforated by orifices, wdiich
difiFer in size, number, and distribution in the several species. They occiu- in
the septa as fine pores similar to those of the siu-face, but in less number.
Again, in species having a single large opening in their terminal chamber,
there is a similar one in each partition, as in Nodosarida, Miliolkla (XXI. 21,
22), Textilaria (XXI. 36), Botalida, and m Nonlonina, Ilohdina, Cristelhiria
&c. Among this group the Convlina form an exception, in having numerous
foramina in the last cell and in the septa between the others. In Acervtdina
again, the several colls communicate by a single opening. In Pcneroplis,
Coscimspira, and in PolystomeUa the septa have numerous pores ; and tlie
foramina proportionally increase in number with the incixsasing size of the
septa, i. e. from the first- to the last-formed chamber (XXI. 28-30). In
Orbiculina the thick septa are penetrated by canals.

Ehrenbcrg pointed out the presence, in several species, of numerous pcr-
pendicidar calcareous columns interposed between the septa, which he sup-
posed to bo hollow tubes, opening up a communication between tlie whole
series of chambers and the exterior. Both their function and their- tubular
nature Schultze disbelieved, and asserted that Lumdites (Etw.) is not one of
the Polytlialamia, but actually a colony of Bryozoa.

Mr. Carter (J iyr. h. 1852, x. p. 170), on the contrary, assorts the ex-
istence ol such tubes in the septa, in the following passage :

Q

226

GENEEAL HISTOIIY OF THE lOTUSOElA.

" The septa occupy (in Opercul'ma Arabica), transversely, about |th of the
breadth of the chambers ; and each septum encloses within its walls two
calcareous tubes or vessels, one on each side, some little distance below the
contiguous siu-face of the shell (fig. 7 a, a) ; these we shall call interseptal
vessels. They are irregular both in their size and course, though generallj'
about YsiVu-th of an inch in diameter, in the last-formed septa of a shell
having the dimensions of the one described, and diminish in calibre back-
wards or towards the fii'st-formcd whorls. Each vessel commences in the
centre of an intricate network of smaller ones, spread over its own side
of the margin of the preceding whorl, and under the layers of the shell ;
these networks, which are joined together, we shall caU the marginal plexus.
In its coiirse each interseptal vessel gives off two sets of ramusculi, and the
marginal plexus one set. Of those coming from the interseptal vessel, one
set terminates on the surface of the shell, particularly about the borders
of the septum ; the other goes into the walls of the shell, and through
the septum, to open probably on the inner surface of the chamber, while
the set from the marginal plexiis opens on the margin. As this vascular
system appears to extend throughout every part of the shell, and must be
for the circulation of some fluid, we will call it the interseptal circulation."

Prof. Williamson has likewise described a series of rntraseptal canals in
Faiijasina, and illustrated their arrangement by engTavings. We have not
space to give the details, but can quote only the general results : — " The intra-
septal spaces are vertical, and give off true divergent cyhndrical canals from
their external mai-gins, penetrating the thick parietes of the shell. These
spaces extend from the top to the bottom of each septum, and only assume
the foiTQ of canals when they approach the peripheral sheU-walls. The con-
necting branches which unite the sj)aces of different convolutions are also
tubular. In no instance do these spaces or their divergent canals communi-
cate with the interior of the segments (chambers) ; for the only direct com-
munications between the two parts of the organism are through the pseudo-
podian foramina, many of which open into the tubular portions of these
passages ; but never, so far as I have observed, into the intraseptal spaces."
Again, " the cavities in the translucent shell ai'e thickly lined with a dark
olive-brown substance, which, if it be the desiccated soft animal, proves that
in this species the gelatinoiis tissue has not only filled the true chambers, but
has also occupied the intraseptal canals and passages. If this be so, it is
curious that the only medium of communication between the soft tissues in-
habiting the spiral segments of the shell and those occupying the intraseptal
and central passages, should be the minute pseiidopodian foramina .... It is,
however, obvious that this organism supports the conclusion at which I ai-rivcd
in a previous memou', viz. that the soft animal had the power of extending
itself externally far beyond the limits of any indi^^dual segment, and woidd
thus be able to secrete calcareous matter in other situations than the mere
parietes of its own. segment. It is only in this way that Ave can explain the
production of the dome-like coveiing which encloses the central umbilic.nl
cavities and their ramifying canals. But if it should be ultimately proved
that the soft tissues have occupied all these irregular cavities, we shall then
have a form of organization which, from its great variability of contour, wiU
approach much more closely to the calcareous sponges than any liitherto de-
scribed."

Schultze says that the species referred to by the two observers just quoted
have not come in his way, but that in none of the genera he has examined
has he met with a similar stracture. He has been equally luisuccossful in
finding the interseptal spaces noticed by Cai'pcnter in Nummvlites : and in

OF THE PnOTOZOA. BHIZOPODA.

227

no genus ho has examined, has he been able to discover its shell to bo com-
posed of calcareous spicula, such as Carter represents in OpercuUna Arabica,
and refers to as incUcative of the intimate affinity between Foraminifera and
sponges, in the ensuing paragraph {A. N. H. x. 1852, p. 173) :— " It must
be now generally allowed that the Rhizopodous natiu-e of Foraminifera is
identical with that of the Amoeba or Proteins, and through the latter with the
Sponge-cell ; and in addition to this, we have the former, at least the genus
Operculma, still more ncaiiy allying Foraminifera to the Sponges,_by possess-
ing a spicula structure, if not a cii-culating system also, like that of
Sponges."

The calcareous shell of Rhizopoda is lined (XXI. 16) within by a delicate
organic homogeneous membrane, with a sharp outline, and of a more or less
deep-brown colour. It is in immediate contact with the animal, and closely
applied to the shell, and has the same perforations (XXI. 24). It penetrates
from one chamber to the next thi'ough the intermediate pores and canals.
During life it is, in the last-fonned chambers, coloirrless. It is not equally
visible in all species. By the addition of dilute acid to Rotalia, Rosalina, and
Textilaria, it is readily brought into view ; but in Miliolida this is difficult,
owing to its delicacy and want of colour'. In the first-formed (primordial)
chamber, occupied by colourless substance, it would seem to be absent. In
its chemical relations it resembles the chitinous shell of Q-romia, and is so
very slowly destroyed by decomposition, that it may be demonstrated in
empty shells foimd amidst the sand at the sea-side, and, according to d'Archiac
and Jules Haiine, even ia fossil specimens.

DiMEN'sioNS ANT) CONDITIONS OF LiFE OF Ehizopoda. — The size of the Ehi-
zopoda is very varied, even among members of the same genus. Ehrenberg
describes Amoehce from -g-gVirt^ ¥Sir^^ Tu^^ °f ™ ^^^^ 5 Difflugim fr'om
■gJjju-th, and yyW^ *° Ti7^^> Arcellai from ro-yth to yfoth of an inch.
Between individuals even of the same species, he represents a diversity of
size of neaiiy equal extent. Schiiltze states the diameter of the shells of
Gromia oviformis, and of G. Bujardinii, to be of an inch, whilst that of
Lagynis is only -g-J-uth in length. Dujardin remarks that the largest fresh-
water Ehizopoda attaia a diameter of -^-^t^A., whilst the marine Foraminifera
are for the most part visible to the naked eye, and have a length of from j^th
to -i-th of an inch. The Nautiloid shells of PolystomeUa have a diameter of
Jg^th to -gLth of an inch, and the ii'regularly- chambered Acervulinai a length
of from -Jg-th to ith of an inch. Among fossil Foraminifera larger sizes
prevail : thus, Sir E. Belcher brought one species from Borneo measmino- more
than 2 inches in diameter ; and many Nummidites are found an inch and
upwards in diameter.

Mr. Jeffreys gives the following account of the habits of Foraminifera
(Proc. lioyal Soc. 1865) : — " Most are free, or only adhere by their pseudo-
podes to foreign substances. Such ai'e the Lagena of Walker, Nodosaria Vor-
ticialis, and Textidaria, and the Miliola of Lamarc. The last genus has some
although a vciy hmited, power of locomotion, which is effected by exsertino- its
pseudopodes to their full length, attaching itself by thorn to a piece of seaweed
and then contracting them like india-rabbcr, so as to draw the shell alonf Avith
them. Some of the acephalous moUusks do the same by means of their byssus
This mode of progression is, however, exceedingly slow ; and I have never
seen, in the course of 24 hours, a longer journey than a quarter of an inch

accomplished by a Miliola Some are fixed or sessile, but not cemented at

their base hke the testaceous AnneUds. The only modo of attachment appears
to be a thin film of sarcode. The Lohatula of Eleming, and the Romlia and
Planorhxdina (D'Orb.) belong to tliis division. Dr. Cixrpenter considers the

q2

2^8

GENEBAL HISTORY OF THE rNFUSOIlIA.

Foraminifera to bo phytophagous, in consequence of his having detected in
some specimens fragments of Diatomaccae, and other simple forms of vegetable
life. But as I have di-edged them alive at a depth of 108 fathoms (which is
fai- beyond the Laminarian zone), and they are extremely abundant at from
40 to 70 fathoms, ten miles fi'om land and beyond the range of any seaweed,
it may be assumed, without much difficulty, that many, if not most of them,
are zoophagous, and prey on microscopic animals perhaps of even simpler form
and structure than themselves. They are in. their turn the food of MoUusca,
and appear to be especially relished by Dentalium entale." The assumption
that, because the Laminarian zone ceases at a much less depth than that at
which Foraminifera occur, therefore no Diatomeas are found, is quite gra-
tuitous, and opposed to observation. The notion also that animal life fur-
nishes nutiiment to Foraminifera at depths Avhere vegetable existence, and
where the doubtful Diatomeae cannot be sustained, is opposed to all proba-
bility.

Of the rate of growth and of the duration of Ehizopoda we have few re-
corded observations : we must, however, suppose them regulated by external
circumstances, such as abimdance of food, moderate temperature, and the like.
Schultze observed of Foraminifera living in a small quantity of sea- water, so
to speak, in captivity, that they grew exceedingly slowly. In only one Po-
lystomella out of many, kept under observation for several months, did he ob-
serve the production of a new chamber. Rotalice, however, were more fre-
quently seen in process of growth, the walls of the new-formed segments
being extremely dehcate and deficient of calcareous matter. Some very young
specimens of Miliola obesa were found to produce two new chambers, £^r the
completion of the primary one, in the course of fom- weeks.

From this fact of their very gradual growth, says Schultze, we may con-
clude that a year or more may elapse before the construction of a many-
chambered shell is completed. This naturalist has, indeed, kept the same
specimens of Polystomella and of Rotalida in captivity for nine months ; and
their persistence for a much longer period is highly probable. If, he adds,
the production of germs put a termination to life, then this phenomenon
entails a fixed limit to its duration. Dujardin, again, foimd Arcellce alive after
two years, in a vessel in which he had preserved them.

The testaceous Ehizopoda possess the power of repauing the efiFects of me-
chanical injuries to their shells. This has been proved by Schultze in the
case of the Polythalamia ; and we may conclude the same faculty is possessed
by the Monothalamia. He has seen almost one-half of the shell of Poh/sto-
mella strigilata, which had been broken away, repaired by a new calcareous
wall resembling the normal one both in its pores, eminences, and markings.
He also frequently noticed in this same species irregularities in the conforma-
tion of the shell, which he attributed to damages previously inflicted ; and
experiment showed him that, even on the same day tliat a considerable portion
was removed, the animal set vigorously to work to replace the lost shell, and
protruded its processes just as before.

Occasionally the destniction of a portion of the shell gives rise to monstrous
(abnormd) fonns. Thus Schultze noticed a double Poh/stomcUa stricfilaia,
and Ileuss a monstrous Nodosaria annulata, which he called N. dichotoma : and
Dr. Carpenter has found several " monstrosities of OrbiioUtes rcsidting from an
unuHual outgrowth of the central nucleus."

The Ehizopoda can, doubtless, maintain life luider very prejudicial condi-
tions. The power possessed by the sarcode substance, of sustaining existence
when even the greater part is torn away, and the capability of rcpaii- mani-
fested by the testaceous species, are facts indicative of tlicu- tenacity of hfe.

OF THE PROTOZOA. — ^hhizopoda.

229

Another proof is found in the capacity of Foraminifera to exist for weeks and
months in the same water. Schvdtze states that ho has found them lying
motionless, with retracted processes, at the bottom of a vessel of putrid water,
in which they had been kept a long time, and that when this water has been
changed, or its foul odour removed by an acid, they have recommenced to
move about, and to thrust out their fibres. In a small glass containing mud
fi'om the lagoons of Venice, and in which life appeared extinct, he found Bo-
talidoi and Miliolidce creeping on the sides, and in great numbers in the sedi-
ment at the bottom. Some still more recent ex^^eriments have convinced this
eminent natiu-alist that fresh water is not very detrimental to them, but that,
on the contrary, they may be kept alive in it for a considerable time. He
found at the same time that some dried Folyihalamia from mud obtained at
Muggia, and let dry for five weeks, continued motionless after six weeks'
immersion in sea- water.

Habitats and Disthibution of Rhizopoda. — Fossil Foems. — The Amcebce
are met with particularly in water containing much organic debris, provided
that decomposition is not proceeding. They are common inhabitants of infu-
sions, and of stagnant water, and are foimd adherent to foreign bodies, to plants,
ConfervEe, and the Hke. Although imable to swim, they are frequently floated
to the surface on the matters to which they stick, such as dead leaves, AlgSB,
or stalks of plants. They occur both in fresh- and in sea -water, but are much
more commonly seen in the former.

The Monothalamia, with reference to their habitats, form two groups,^
one marine, the other freshwater, Arcella, Difflugia, and Euglypha arc
essential freshwater genera, whilst Sjpirillina (Ehr.), Qromia, Lagynis (Sch.),
ajid Squamella (Sch.) ai-e marine. They are not met with in infusions arti-
ficially prepared although common in stagnant water holding organic matters
in suspension, and found crawling on these or on the sides of the vessel
containing the water.

Polytlialamia are all marine. Their abundance and extent of distribution
are surprising ; this is true of them both in the living and in the dead or
fossil condition. Schultze states that on the northern level shore of the har-
bour of Ancona, the shells of the Foraminifera cover the siuface here and
there like a fine sand, and are discovered in many places in smaller numbers
at a depth of 20 feet. When this sand was placed in water in a glass iai- no
specmiens were found to crawl up the sides ; and obsei-vation showed that few
among them retamed any organic contents. From a smaU rocky islet in the
harbour he scraped into a fine net the slimy mud, and then separated the
lighter suspended particles from the mixture of animal and vegetable matter
and placed them m another glass. On examining, a few hours later the fine
sand so separated, he found it almost entirely composed of Polythalamia fiUed
mth their orgamc substance and aHve, many of them having crawled up the
sides of the vessel. His experiments at Venice were entii-ely correspondent • no
living bemgs were found in the sand from the shore, but countless specimens
in the debns about the Algffi m tlic lagoons. Once, however, at Cuxhavon
on the Jilbc, he met with Uving Foraminifera in the sand '
Dujardin also says of the Polythalamia, that, from being unable to swim
they are only to be foimd attached to the surface of bodies on which thov
crawl, such as aquatic plants, or, otlier^vise, lying amidst the debris coveiin-
the base of such plants or m the liollows between the asperities of the shoUs
of marine Mollusca. Sponges, again, form a convenient habitat for t^t
PolyiJudarma, having their pores at times pretty weU filled with tliem n
the same way Corals and Corallines are frccpiently beset with im T, "
necessity of attachment cannot universaUy prevail/since the Foran^niferlall

230

GJiNEKAL HISXOllY OF THE INlfUBOUIA.

SO often found scattered over the bed of the oceaxi, as -well in the living as in
the dead state, without any Algae near, whereto they can adhere.

The extraordinary abundance of Poraminifcrous shells in the sand of some
sea-shores has been long observed. Plancus, in 1739, counted, with the aid
of a low magnifying power, 6000 individuals in an oimce of sand from Rimini,
on the Adriatic; and D'Orbigny states that 3,840,000 exist in an eqmd
quantity of sand from the Antilles. Schultze also counted 500 shells of Ilhi-
zopoda in ^th of a grain of sand collected from the Mole of Gaeta, which had
previously been passed thi'ough a sieve and separated from aU particles above
Y^th of an inch in size.

Ehrenberg describes finding Polytlialamia both on the surface of the sea
and also at the bottom, even at a depth of 12,000 feet. From these great
depths they are procured by soundings ; the lead, after being coated with
grease at the bottom, biings up attached to it the small particles of sand and
other matters with which it comes into contact at the sea-bottom. Numerous
such soundings were taken by Sir J. Eoss in his Antarctic expedition, and
have been practised by others in different regions. Dr. Bailey records the
results of a series of deep soundings made in the Atlantic, over a considerable
geogTaphical area, from latitude 42° 4' to lat. 54° 17', and depths varying
from 1080 to 2000 fathoms. " None of the soundings," he states, " contain a
particle of gravel, sand, or other recognized unorganized mineral matter.
They all agree in being almost entirely made up of the shells of Foraminifera.
.... But neither the surface-water nor that of any depth . . . collected close
to the places where the soundings were made, contained a trace of any hard-
shelled animalcules." Schultze is unable to receive Ehrenberg's statement of
finding shells floating on the surface of the sea, seeing that they natui'aUy
sink in water. Still he admits that in shallow water they may be suspended
by the tossing of the waves, and that they may float on the surface attached to
sea- weed torn from the bottom, or to other floating substances. He likewise,
and, we think (judging from the laws of distribution of organic life at different
depths as pointed out by the late Prof. Edward Eorbes), very justly, demiu-s
to Ehrenberg's conclusion, that the Polythalamian shells fished up from the
great depths cited, and others approaching them, lived at those depths, and
had become empty by speedy decomposition of theii- animal contents. At
depths far less considerable, we believe all organic life ceases, and should
consider the Foraminiferous shells there found to have been drifted from other
less profound places by currents in the ocean. Prof. Bailey also started the
question, whether the Foraminifera found at the bottom of the sea actually
lived there, or were home there by submarine cmTcnts, but admitted that
these and other like questions could not be at present decided. "^Tiat, however,
is very remarkable, is that the species " whose shells now compose the bottom
of the Atlantic Ocean have not been found living in the surface waters, nor in
shallow waters along the shore. It is but fair, also, to state that Mr. Jefft-eys
has di'cdged li-ving Pohjihalamia from a depth of 108 fatlioms (648 feet).
So far as Schultzc's researches go, they prove a very limited geographicd
distribution of some species of Polytlialamia. Thus, he has never found the
Rotalia Veneta elsewhere than at Venice and Muggia, near Tiieste, wliOst
the Polystomella strigilata, of Ancona, is altogether absent at Ycnice and
Trieste. Nodosaridce, which are common enough at Ilimini, are sought in
vain at Ancona, close by, whilst llotalia Beccarii occurs at both those places.
So Penei-oplis planata is found in tlic sand on the Istrian coast, from Citta
Nuova to Pola, but is absent at Trieste, Venice, and Ancona. Similar iUiis-
trations miglit, says Schidtzc, be multiplied, to show the considerable diversity
of local fauna.

OF THE PKOTOZOA. RHIZOPODA.

231

A limited distribution, both in reference to place and to the conditions of
existence, has been determined by Ehrcnbcrg and other observers of the Polij-
tlialamia, and also employed by geologists in fixing the period of the deposi-
tion of certain strata, and the cu-cumstances under which it has occurred.
Thus Bailey records of the Atlantic soimdings, that they " contain no species
belonging to the group Agathistegia (D'Orbigny), a group which appears to
bo confined to shallow waters, and which in the fossil state fii-st appears in
the tertiary, where it abounds." Again, they " agree with the deep soundings
oft" the coast of the United States, in the presence and predominance of species
of the genus Globigerina, and in the presence of the cosmopolite species Orbic-
lina universa (D'Orb.) ; but they contain no traces of the Marginulina Baclm,
Textilaria Atlantica, and other species characteristic of the soundings of the
Western Atlantic. In the vast amount of pelagic Foraminifera, and in the
entire absence of sand, these soundings strikingly resemble the chalk of
England, as well as the calcareous marls of the Upper Missom-i ; and this
would seem to indicate that these also were deep-sea deposits. The cretaceous
deposits of New Jersey present no resemblance to these soundings, and axe
doubtless littoral, as stated by Prof. H. D. Eogers."

A fixed geographical distribution is also implied by the division made by
D'Orbigny of the species he observed, — ^viz. into 575 peculiar to the torrid
zone, 350 to the temperate, and 75 species to the fiigid zone. Moreover, Dr.
Carpenter stated (in the Annual Address at the Microscop. Soc. 1855) that
he and Prof. WiUiamson find " that there are certain species whose range of
distribution is limited, and whose form is remarkably constant, but that, in
. by far the greater number of cases, the species of Foraminifera are distributed
over very wide geographical areas, and have also an extensive geological
range." Mr. Jeffreys remarks that, in his opinion, " the geographical range,
or distribution of species, is regulated by the same laws as in the Mollusks and
other mariue animals. I have found in the gulf of Genoa species identical
with those of our Eebridean coast, and vice versa."

Fossil Foraminifa-a. — In a fossU form the Polytlialamia are veiy common,
and enter largely into the formation of several rocks, chiefly calcareous or of
the tertiary series, in every part of the world. Ehrenberg, in his microscopic
examination of the chalk formation, represents these shells as the most im-
portant constituent; and Dr. Bailey speaks of them as largely concerned in
the foi-mation of the tertiary rocks of South Carolina, and adds, they "are stiU
at work in countless thousands on her coast, filling up harbours, forming
shoals, and depositiig their shells to record the present state of the sea-
shore, as their predecessors, now entombed beneath Charleston, have done with
regard to ancient oc3ans. For the city just named is buUt on a marl 236 feet
thick. The marls from the depth of 110 to 193 feet arc tertiaiy, as also,
in all Hlielihood, are those beneath, extending from 193 to 309 feet, and also
of the Eocene epoci. The lithological characters of the marls from 236 to
309 feet difi"er from those above them, although many of the same species are
Btm to be detected ' {A. N. H. 1845, vol. xv.).

The most Vih\m^(nt Foraminifera of the chalk belong to RotaVia, Sjpindina,
and Textilaria: the fossil genus Nummulina abounds in tertiaiy strata; and
their shells constitute the chief ingredient in the composition of many lime-
stone rocks used in building, such as those in Egypt, from which the hu"-e
stones of the Pyramds are quarried. In America this genus is largely re-
placed, as a comporont of limestone, by the genus Orbiloldcs. Species of
Textilaria arc the nost abundant in Oolitic formations. In the cretaceous
earths, says D'Orbigiy, genera and species augment in rapid progression from
the lower to the higl.er formations. On arriving at the tertiary rocks Fora-

232

GENEEAL mSTOBy OF THE INFUSOliTA.

minifera become still more multii)lied, and many previously unobserved genera
make their appearance. In the Silurian and Devonian rocks of the palajozoic
series, Foraminifera appear to be absent. In the carboniferous deposits
D'Orbigny found one species, but detected none in the Permian, Triassic, or
Jui-assic strata. Mr. Elng has, however, discovered shells in thcPei-mian rocks.

Many genera have liitherto been found only in the fossil state : some such
wo may suppose to have become extinct ; but others will probably be discovered
when the search after hving specimens is farther prosecuted. It may be
generally stated that the relative number of identical fossil and recent species
is much greater in this family of Foraminifera than in any other known ; and
specific forms have continued from the Mesozoic era until the present day, so
connecting, as by an imbroken chain, the fauna of our own time and that of
almost countless ages past.

Question of the Cell-natuice op Rhizopoda, and of the Characteb of
FoRAMiNiFEEA AS luDivrDTJALS, OS AS CoioNiEs OF Animais. — The prevaiHng
theory of the cellular composition of all animal and vegetable tissues induced
several distinguished naturalists to represent the Ehizopoda as cells. KoUiker
ingeniously argued (J. M. S. 1853, i. p. 101) in favour of this view, and for
a time succeeded in persuading most scientific men of its tnith. It had the
character of a grand generalization, and recommended itself by its simpUeity.
Various stiTictural peculiarities and general considerations are, however,
opposed to this theoiy: these we will adduce after Kolliker's arguments
have been stated. He first assumes that the Ehizopoda and COiated Pro-
tozoa are comprehended in a single class of simple animals, which, like the
Gregarince, are unicellulai- ; and he fui'ther groups the Actinopliryina with
Ehizopoda. The absence of an integmnent to represent the ceU-wall, and
in most of them of a recognized nucleus, are difficulties he would explain
away. First, he supposes that, where a nucleus is not seen, it " may have
existed at an earlier period, and be absent only in the full-grown animal, or,
again, that it may be entirely wanting, and still the animal be regarded as a
cell." Secondly, " with respect to the membrane, it may be regarded as certain
that there are cells with a membrane of such extreme tenuity as to be hardly
distinguishable from the contents," and others in which it a later period all
difi'erence between the membrane and contents disappears, — ^for instance, the
elements of the smooth muscles of the higher animals." Which of these two
possible conditions obtains in the Rhizopods, he cannot uadertake to say, but
would remark " that their other relations are not opposed to the notion that
they may be simple cells, — such as their stnictureless honogeneous contents,
their contractihty, and the vacuoles which occui- in then, resembling in all
respects the contents of the body of unicellular Infasoris. So, Ukewise, the
simplicity of their foim and mode of taldng food, so clcsely rcscmbhng the
way in which Infusoria introduce a morsel into tlieii* parenchyma. Certainly
the presence of a ceU-membrane is scarcely reconcUeable -with the circumstance
that the body is capable of admitting a morsel of food at my part of the sur-
face ; but in one point of view it is not indispensably lecessarj^ to assume
that such exists in the fully-dovelopcd Actinopkrys, and in another it is by
no means wonderful that a membrane, in consistence alnost the same as the
rest of the parenchyma, should be capable of being ton and of reuniting."
It is tiierefore, he concludes, best to consider the llhizopda simple, altliough
modified, ceUs, especially since there is little else to be made of them. " It
cannot be admitted that they consist of a whole aggroga'.ion of cells ; and as
Uttle is it to be supposed that they arc simply a ma.ss ofaniTual matter with-
out further distinction — a.s it Avero, indopendent living cell-contents. And
the less can this opinion be entertained, because " ceUi are the clementai-y

I
I

I

I

OF TnE PBOTOZOA. — EIUZOPODA.

233

parts of the higher animals and plants, and the unicellular condition the
simplest form in the animal kingdom." The existence of an investing mem-
brane in the Hhizopoda he finally considers probable.

The arguments here quoted from KoUilvcr's paper on Actinophrys, have been
examined by several later \mters, and have had theii- defects pointed out.
Pei-ty declares himself opposed to the cell-theory since Rhizopoda are waJit-
ing the essentials of the cell-nucleus and cell-wall ; and the hypothesis cannot
be applied to animals composed not of cells, but of an amorphous piimitive
substance.

M. Claparede attacks Kolliker's arguments in detail. The question raised,
whether the nucleus and membrane may not disappear in the course of
growth, he answers by another query — " We may conceive the possibility of
this ; but where do we find any proof of it ? " — and proceeds to remark his own
failirre, and that of Ehrenberg and of most others, to discover a nucleus, even
in very small animals, and after treating them with dilute acetic acid. " The
supposition, that Actinoplirys and other Rhizopoda pass through a previous
cellular condition, has consequently no foundation in fact." He cannot agree
with Kollilver, that of the three parts of a cell — the nucleus, membrane, and
contents — two " may be deficient, — that for example, we may attribute the
signification of a cell to the contents remaining alone and contained in
nothing .... If, therefore, with KoUiker, we regard the Rhizopoda as a class
of imicellular animals, the organisms which it iacludes will be principally
distinguished by their having nothing to do with cells, as they consist of a
shapeless mass of a structureless homogeneous substance."

M. Claparede next subjects to examination the argument for the cell-nature
of Rhizopoda deduced from analogy with Ciliated Protozoa, which KoUiker
takes for granted to be unicellular organisms. This assumption, and conse-
quently the analogy dependent on it, are shown to be erroneous ; and then
the writer goes on to say that, " even if we admitted that Actinophrys was
the equivalent of a cell, it would still not be unicellular, inasmuch as an
endogenous cell-production has taken place in it. The contractile vesicle is
nothing but a cell" invested by a membrane ; and this being the case, the
existence of such a membrane in other Cihated Protozoa becomes all the more
probable. " KoUiker himself supposes that the contractUe vesicle, when pre-
sent, is the equivalent of a ceU-membrane ; and with the proof of the exist-
ence of siich (an endogenous) formation in Actinophrys, his hyjiothesis of the
uniccHular constitution of the animal consequently faUs to the gi-ound."
Leuckart has also briefly argued against the ceU-theory of Rhizopoda; but
as no novel views are taken of the question, we shaU not quote his remarks.
Our own opinion is, that to insist upon the unicellular natm-e of Rhizopoda
and of other Infusoria is to Umit the operations of natiu-e, in the manifesta-
tion of animal Ufe, to one sort of mechanism, as though Ufe could not be
exhibited except by an organic substance enveloped by a membrane and
enclosing a nucleus. Reasoning by analogy should teach us diff"erently ; for
everywhere in the animal series do we sec tjqics or grades of organization
progressively developed fi-om theii- simplest to a more or less compUcated
degree, as if nature would show us by how many different plans she can
attain similar and equaUy beneficial results. And are not the Rhizopoda an
illustration of this fact, an example of the establishment of indoiiendcnt
animality in primorchal animal matter, and, as in the case of the multUoculai-
Polylhalamia, of the possible extent of dcvelopmout this simple t^c miv
undergo without the separation or addition of any other definite structuj'nl
clement?

If Schneider's researches bo confirmed, wo must admit several Rhizopoda

234

6ENEBAL HISTORY OF THE INFUSOEIA.

to be possessed of a nucleus. On the other hand, a large number of species
are able to produce new individuals by the mere detachment of a portion of
theu" sarcode substance, — an act in wliich no nucleus is concerned, whereas
in ccU-propagation by fission a preparatory section of the nucleus appears a
necessary process. In the Rhizopoda, therefore, we may conclude that, in
the language of Professor Owen, " the spermatic force " is diflnsed through-
out their entu-e substance, and not, as it were, concentrated in a paiticular
organ or nucleus.

The question respecting the nature of the many-chambered Foraminifera,
whether they are to be considered siagle individuals or colonies of animals, is
elaborately examined by Schultze, who comes to the conclusion that the
inhabitant of each shell is a single animal. Ehrenberg is the supporter of
the opposite view ; but Schultze shows that several structural details given
by him, upon which the colony-theory is partly established, are erroneous,
and that it is one common connected substance which occupies each and every
chamber. Prof. Williamson {T. M. S. 1851) has the following pertinent
observation on this colony-theory. Speaking of the Orhiculhia adunea, he
says — " The attempt to isolate the various portions, and to raise each portion
to the rank of an individual animal, even in the limited sense in wHch we
should admit such a distinction in the polypes of a Sertularia or of a Oorgonia,
appears to me whoUy inadmissible." Moreover, the soft-structui-es being
devoid of visible organization, " the whole animal wiU be very little raised
above the Polypifera, only possessing a symmetrical calcareous skeleton,
which is at once both external and internal " (i. e. the Porifera).

Of the Affestities of Ehizopoda. — That the Rhizopoda constitute a class
of animalcules distinct fi-om eveiy other is evidenced by their characteristic
vital structiu'e and phenomena, their power of producing their like, their
growth, their faculty of digesting and appropriating nutrient matters, and by
the ascending stages of development seen among them, advancing from the
simple Amceba to the compound testaceous Oristellaria and Polystomella.

In the natui'e of theii' animal portion they resemble Ciliated Protozoa ; it con-
tains similar vacuoloD and granules, and also a contractile vesicle. On the other
hand, they differ from them in having no definite outline to the animal tissue
boimded by a limiting membrane or integument, and particularly in possess-
ing no cilia, which, as locomotive organs, are replaced by the peculiar and
characteristic pseudopodes. In variabOity of outline an approach is- made to
Rhizopoda by some genera of the heterogeneous family, Enclielia of Ehrenberg ;
but they never exhibit any such changeable character as the smface of the
former, never protrude similar variable processes, nor present a cii'cxilation
of granules. The D'mohryina might perhaps be cited as affording an example
of a considerable variability of form ; but our knowledge of this family is too
incomplete to render analogies based on it of value.

The affinity between Rhizopoda and Phytozoa is no closer. Some of the
latter can greatly modify theii- foim in moving ; biit in none docs tlus partake
of the character and extent of the variability exhibited by llhizopods. More-
over in none are variable processes found, but in general one or more elon-
gated cUia or filaments, which, by their undulation, serve as the piincipsil organs
of locomotion.

Between the Testaceous Rhizopoda and Cniated Protozoa the alliance is even
less evident ; for in none of the latter do we meet with shcUs like those of tlie
former, and in none is the relation between a lorica and its contents corre-
spondent to that of tlie shell and sarcode substance of Rhizopoda. It has
already been noted that the distinction between the two classes of Protozoa
foiindcd on the sUicious chai-actor of tlic shells or lorica) of the Ciliated, and

OF THE PEOTOZOA. — EHIZOPODA.

235

the calcareous nature of those of the Pscudopodous class, is not in accordance
with fact ; for although all, or almost all, Pohjthalamia have calcareous shells,
yet the flexible loricte of many Monothalamia are chitinous, just as those of
loricated CUiata.

In the presumed fact of the sheUs of Arcellina being silieious, Ehrenberg
discovered a relation between that family and the BaciUaria. This affinity he
traced stiU fui-ther ; for, when describiag the genus CypUdium, he remarked
— " It forms a connectiag group between Arcella and Badllaria, by reason of
the simple locomotive organ (like a snail's foot), and approaches very closely
to the group Desmicliece." However, even if he be right as to the single un-
divided process of Cyphidium, the presence of any extended foot or pedal
organ fi-om the silieious fi-onds of BaciUaria, whether Diatomece or Desmidiece,
is not now admitted by any naturalist.

If Stein's observations and opinions be correct, an indirect relationship
actually exists between Cihated Protozoa and Ehizopoda ; for that pains-
taking observer has convinced himself that the VorticeUina, by ulterior de-
velopment, become transfonned into Acineta-'like or Actinophryean organisms,
of the intimate aflSnity of which no doubt can be raised. The questions
raised by this apparent transformation do not require discussion here, since
they are folly entered upon in the history of the CUiata, and in that of the
Acinetina, considered as a subclass of Ehizopoda.

Another aUiance was formerly assigned to the MiUtUocular Ehizopoda, viz.
mth the Cephalapoda, of which they were treated as a subdivision. This
association was suggested, by the Nautilus-]jke form of some genera, to the
earUest obsei-vers of the Foraminifera — Beccarius in 1731, and Plancus in
1739 ; and the error was perpetuated by D'Orbigny in 1826. Dujai'din has
the great merit of first combating this mistaken opinion, and of pointing out
the extremely simple nature of their contents, and their true affinity with the
simple Amoebce.

Several naturalists, and among them M. de Quatrefages, have classed the
compai-atively large Noctilucce with the Ehizopoda. But direct observation
seems to show that, although in a few particulai-s a Likeness obtains, yet
the siun of the differences greatly sm-passes that of the resemblances. 'The
Noctiliicce show a more complex organization ; they have an integument com-
posed of two layers, an evident mouth and gastric cavity with appenda"-es
and motUe fUaments, but no variable processes. * '

A stiUdng general resemblance subsists between the Faked Ehizopoda

Amcebce — and the like isolated individuals and the germs of freshwater Spono-es
or Sponfjillce, which Mr. Carter has named Proteans (XXI. 5 a, h, c). The
resemblances are weU conveyed in the foUowing quotation from Mr. Carter's
paper :— " A ragged portion torn off with a needle, ^vUl be seen graduaUy to
assume a spheroidd form ; and if there be a spiciUum, it wUl embrace it witliiu
its substance, it may even be seen to approach it, and it may bear away the
spiculum, having, as it were, spit itself upon it. On its cu-cumfcrence aa^U be
obsci-ved little papUla;, which graduaUy vary their form, extenchng and retract-
ing themselves, untU one of tliem may be seen to detach itself from the parent
mass and go off to another object. This little animal, one of tlie group which
it has left, may remain stationary on the second object, or descend to tho
watch-glass, assuming in its progress aU forms that' can be imaoincd snlie
roidal or polygonal, wliilst eveiy point of its body appeai-s camblc 'of ox"
tcnchng Itself into a tubvUar attenuated prolongation .... Tlicso transparent
Uttle sacs (the gemmides of Grant and Hogg) are sometimes filled ANith o-roon
matter. Ihey appear to be able to adapt themselves to any form thnt^ninx'
be convenient for them to assume; and when forcibly sepiatcd from each

23G

OENEEAL niSTOBY OF THE INFUSORIA.

other (by tearing to pieces a minute portion of the sponge under water in a
watch-glass), the isolated individuals may be seen to approach each other,
and apply themselves together in twos and threes, &c. and so on, untU, from
a particle only discernible by the microscope, they assume the form of an
aggregate mass visible to the naked eye ; and such a portion, groAviug and
multiplying, might ultimately reach the size of the largest masses adhering
to the sides of the tanks at Eombay. They appear to belong to the genus
Amoeba of Ehrenberg."

These changeable globules Mr. Carter, in the subsequent part of his
paper, designates Proteans, and states that they commonly resemble the Pro-
teus diffiuens (Miiller). (" Notes of the species, &c. of the Fresh-water Sponges
of Bombay," Trans. Med. and Phys. Society, Bombay, 1847. Appendix.)

In his more recent contribution on the freshwater Sponges, Mr. Carter
describes cells, capable of greatly and rapidly changing their form, endowed
with considerable motile powers, and furnished each with an undulating
locomotive filament (XXI. 5). These organisms he considers to be zoosperms,
or the spermatozoa of Sjpongilla. Speaking of one, he says — " When its
power of progression and motion (of a serpentine creeping character) begins
to faD., and if separated fi-om other fragments, it soon becomes stationary', and,
after a Httle polymorphism, assiunes its natiu-al i)assive form, which is that of
a spherical ceU. During this time the motions of the tail become more and
more languid, and at length cease altogether." On the other hand, it may
attach itself to some fragment, or to another ceU, and become indistinguish-
able fr'om the common mass ; and the tail, floating and imdulating outwards,
is all that remains visible." In these structures there is, therefore, polymor-
phism as in Ehizopoda, but no actual extriision of pseudopodes ; and the points
of agreement, after all, are really accidental, and not demonstrative of a
structural affinity. In them we have reproductive germs, which coalesce and
disappear as independent existences, whilst in the case of Amoeba each speci-
men is an independent individual, and is never seen to coalesce with others
into a common or sponge-hke mass.

Dujardin devoted a couple of pages to speak of this affinity between Amosboe
and Sponges ; and Perty even goes so far as to make the latter a third class of
the Ehizopoda, intermediate between Arcellina and Amoebhm, on accoxmt of
the calcareous, sUicious, or homy spicula which occur in their compoimd
mass, and constitute a sort of skeleton.

The affinity with Sponges is traceable even in the case of the testaceous
Polythalamia, as Prof. Williamson pointed out in 1848, and in a subsequent
memoir in 1851 (Trans. Mic. Soc.) thus enters on the question : — " Looking at
the structure of the shell of the Orbimlina adunca, and especially at the large
orifices which communicate between its various cavities, we cannot fail to
observe that it is a reticulated calcareous skeleton, whose proportionate rela-
tion to the size of the soft animal has differed but httle from that of the
sihceo-keratose network of many Sponges to the shmy substance with which
they are invested."

So Dr. Cai-jjcnter (Proc.Boy. Soc. 1855), in his critical examination of Orblto-
lUes, " i)laces that genus among the lowest forms of Foniminifera, and con-
siders that it approximates closely to Sponges, some of Avhich have skeletons
not very unlike the calcareous network which intervenes between its fleshy
segments." With respect to this idea of Dr. Caqjcnter, tbat they are allied
to Sponges, Mr. Jeftreys (same journal) woiild remark " tliat PolystomcUa
cri.'ipa has its poriplieiy set roimd at each segment with sQicious spicula, like
the rowels of a si)iu'. But as tlicre is only (me terminal cell, which is con-
nected with idl the others in the interior by one or more oi)cuings for the

OF TltE PEOTOZOA. — MIZOPODA.

237

pseudopodcs, the annlogj- is not completo, this being a solitary, and the Sponge
a compound or aggregate, animal." In a previous page the theory of Ehren-
berg, that the Foraminifera are eompoimd or aggregate animals, has been
referred to. It was on this hypothesis that he assumed their aflSnity with
Polypes — -with PlustroB and Bryozoa, at the head of which he arranged them.
This association, like the hypothesis it rests iipon, is untenable. In his
work on the Foraminifera of the Vienna basin, M. D'Orbigny assigned a
position to these animals as an independent class between Echinoderms and
Polypes, which, from the present knowledge of the stractui-e and reproduc-
tion of those classes, we cannot suppose he would seek to maintain.

CiASsiEicATioN OF Ehizopoda. — The first division of Ehizopoda that suggests
itself is into naked and testaceous forms, or, as Ehi-enberg would say, into
iUoricated and loricated. The naked forms constitute the family Amoehina,
represented by the single genus Amoeba .

The determination of specific characters in this family is attended by almost
insurmountable difficulties, and can only be unsatisfactoiy, by reason of the
absence of any definite figxu-e, and of detenninate organs or parts. More-
over the semifluid body of any one presumed species must be much influenced
by external causes, and in some measui-e by the matters which may have
entered into its substance ; and the like causes will doubtless operate by
modifying the outline, dimensions, and number of the processes. Among
such causes the density of the liquid in which they live, and the quantity of
organic matter contained in it, may be particularly mentioned. Claparede
remarks — " It appears almost absurd to attempt the distinction of species
amongst the Amoebce xmtil we know something more of their intimate
organization. Thus Ehrenberg's A. radiosa is characteiized by the reg-ularity
of its processes, and its generally stellate form when at rest ; but when the
creature creeps, it slowly expands and the peculiar outline disappears; it
Jloivs along like a cloudy veil or di'op of oil, and A. radiosa has become converted
into A. diffluens." Yet, this author afterwards goes on to say — " even the
changeable Amoebce- have their typical forms, such as the stellate and globu-
lar." Other grounds of specific distinction (of no very certain value, indeed)
are found in the shape, length, and mode of termination of the variable pro-
cesses, and in the size, colour, transparency, activity, and habitats of these
beings.

The Testaceous Ehizopoda naturally fall into two groups, — one distinguished
by having a unilocular, the other a multilocular, sheU — the former called, by
Schultze, Monothalamia, the latter, Polythalamia or Foraminifera. These
grand divisions have been recognized by eveiy natui-alist ; but some have been
led, from giving importance to other particulai-s, to arrange differently cer-
tain genera, or, otherwise, to detach some as additional families.

Thus Ehrcnberg, swayed by his polygastric hypothesis, and satisfied in his
own mind that the Arcella;, Difflugia;, and one or two other monolocular genera
possessed a series of stomachs and other oi^ans like other Polygastria, united
those genera into a family which he called Areellina. This dcitachmen't of one
group of pseudopodous beings from the rest, he further justified, as heretofore
stated, by representing it to have silicious instead of calcareous shells In
this dislocation of evidently-allied forms he finds no imitators, and is unsun-
ported by facts. ^

D'Orbigny clistinguishod the one-chambered, sac-like, slicUed Ilhizopoda
as one of the six onlers into which he separated the Foraminifera, and named
It Monostecpa This order is nearly equivalent to that fi-amod by Ehrenbere
under the title of Monosomatia, to comprehend the genera Oromia, Orbulina
and Ovulina,—^ term subsequently borrowed by Siebold, but extended by hiin

238

GENERAL HISTOEY OF THE DTFUSOEIA.

SO as to include not only the particular genera enumerated, but also the
families Aniceba; and Arcellina of that ^laturalist.

The term Monothalamia contrasts well with that of Polythalamia, expresses
the fact, and involves no hyi)othesis as do Ehrenberg's words Momsomatia
and Polysoinatia, which are foiuided on his belief in the colony-like aggrega-
tion of several individuals within a Foraminiferous sheU.

The Monothalamia of Schultze (as before remarked) do not precisely cor-
respond with the one-celled group of either of the other authors named ; for,
besides the Monostegia of D'Orbigny, it comprehends the Arcellina of Ehren-
berg and a few other new genera. The groupings and relations of the several
species are represented in the appended table exhibiting Schultze's system.

In the classification of the Monothalamia certain and constant characters are
deducible from the shells, whilst those drawn from the soft parts, from the
length or tenuity or mode of termination of the pseudopodes, are of compara-
tively secondary importance, and not to be relied on alone. Definite charac-
ters are derivable from the fig-ure, size, composition, sculpturing or appendages,
and colour of the entu-e sheU, from the presence of a single large aperture or
of many small pores, and from the form of the apertui'e and of its margin ;
consequently it is in the shells of the Polythalamia that we must seek generic
and specific distinctions. As animals, they have all alike the same sarcode sub-
stance, which extrudes similar variable fibres : hence any diversities observed
in its colour or transparency, in its contents, or in the manner in which the
processes are extruded or otherwise comport themselves, seiwe but a sub-
ordinate purpose in the scheme of classification. On the contraiy, the cha-
racters of the shells are, within certain limits, determinate and fixed. They
are derivable from the fig-ure, size, colour, and consistence of the shell ; fi'om
the markings, processes, pores, and slits occupying its sui-face; from the
relative position and figiu-e of the several chambers; from the mode and
degree of theii" connexion ; and from the presence or absence of large apertures
in company with the usual foramina ; and last, not least, from the intimate
structiue of the shell. Dujardin recognized the value of the shells to supply
the basis of a classification of the Ehizopoda ; but he had rccoxu-se to the form
of the variable expansions to make his primaiy division, " although," as he
remarks, " it has no absolute value." He arranged aU the Ehizopoda, with
the exception of the Amosba; (which he treats as a distinct family), into two
sections, — one having a single unilocular shell with a single lai-ge aperture ;
the other a foraminiferous compound sheU, or one having several aggregated
chambers, each with a simple oiifice, as represented by the tribe Mil i oh. It
is in the subdivision of these sections that he employs characters derived from
the variable processes. Thus he separates the fii'st into — 1. those animals pro-
vided with short and thick processes rounded at the extremities, viz. Difflngia
and Arcella ; and 2. into those having filiform expansions, acutely diwvn out
at the ends. The latter division is more largely represented ; and he separates
its numerous species into three tribes, viz. Tnnema, with a lateral oiifice ;
Eucjlypha, with a tuberculated or areolated sheU and few simple expansions ;
and Gromia, with a membranous spheroidal shcU and expansions, thick at
the base, but very long and branching. He has not attempted the classific^i-
tion of the whole of the Foraminifera, but restricted his account to some few
genera which ho has found in a living condition.

D'Orbigny instituted five orders of the Polythalamia, viz. — 1. Stichostegia,
having the cells arranged one above another in a straight or shghtly-curvcd
line ; 2. Uclicostcgia, mth ccUs disposed spirally around an axis ; 3. Ento-
mostegia, having tho chambers alternating and coiled spirally ; 4. Enallo-
stegia, with alternating but not spirally-disposed chambci-s : 5. Agathistcyia,

OF THE PROTOZOA. IiniZOPOBA.

239

having the cells spirally arranged, but eacli one occupying only one-half the
circuit.

The three sections proposed by Schultze are— 1. shells disposed m recti-
linear series or in a slightly- curved line, Rliahdoidea ; 2. those coiled in a
spiral, Helkoidea ; 3. those irregularly aggregated, Soroidea. The first of
these corresponds to the Stichostegia of D'Orbigny ; the second includes all
the remaining orders of that wiiter; whilst the third sectionals represented
by a smaU number of species, previously un mentioned, which Schultze unites
in the genus Acervidina.

What structural peculiarities should be employed to determine species, is a
question now much mooted with respect to the Foraminifera. In reference
to this subject, Dr. Carpenter (in the annual address at the Microscopic So-
ciety, Feb. 1855) obsei-ved " that a large proportion of the species, and even
of the genera, which have been distingmshed by systematists, and especially
by M. D'Orbigny, have no real existence, being nothing else than individual
varieties." This error is at once accounted for by M. D'Orbigny's mode of
proceeding (as stated) : " for that, in examining any new collection, he set
an assistant to pick out the most divergent forms, and then described all that
might prove new to him as distinct species, without troubling himself in the
least about those connecting links, the existence of which should have at once
convinced him that he was following an altogether wong method. Tkrough-
out the whole of his labours on the group, in fact, I find the influence of the
erroneous ideas which he originally entertained with regard to the nature of
the animal of the Foraminifera ; for in the formation of his orders, as well
as of his genera and species, he has proceeded as if the characters of the tes-
taceous skeleton were of the same distinctive value when its construction is
due merely to the solidification of the sui'face of a minute fragment of animal
jelly, which is subject to an almost indefinite variation both in size and in
shape, as when it belongs to a mollusk of high organization, the plan of
whose confonnation is definitely fixed .... When a collection is brought to-
gether containing large numbers of individuals of one generic type, which
appear, however, to belong to several distinct species, it very commonly hap-
pens that, although it would be easy to make 6, 8, 12, or 20 species by
selecting the most divergent forms, yet, when the attempt is made to sort
the entire collection under these types, only a part of it can be unhesitatingly
arranged around them as centres, the remainder being transitional or inter-
mediate forms, for which another set of species must be made, if the principle
of separation be once adopted. In fact, to such an extent docs individual
variation often go, that (as in the case of the human race) no two specimens
are precisely alike, and there is no satisfactory medium between groupino-
them aU as varieties of one species, and raaldng every individual a species, w^hich
is manifestly absurd."

The error of D'Orbigny has not escaped Schultze's notice ; for in his chapter
on classification he has repeatedly pointed out the insufficiency of the charac-
ters on which that observer relied in fi'aming his species, genera, and famUies.
For instance (p. 52), he points out the erroneous separation of the Stichostegia
(D'Orb.; into two families, according to the equilateral or inequilateral con-
dition of the shell. And further on, he remarks that the variations elevated
by_ D'Orbigny to the rank of specific distinctions arc merely accidental diver-
sities in growth, connected together by eveiy intermccHate variety. Hence
for example, he combines the genera Triloculina and Quinqueloculina (D'Orb \
into one genus Miliola, and the Orhitoidcs and Orhitidina (D'Orb ) into a
single genus Orbitolites. Various other iUustratious might be adduced for
instance, the family Nantihidce ; but it is unncceasary to multiply them ' It

240

OENEEAL HISTOBT OF THE INFUSORIA.

is only fair, however, to state that D'Orbigny is not alone guilty of unduly
manufacturLng species, but that Elu-cnberg, Reuss, and others are equally
involved in the fault, which, by the way, is one almost inseparable, and
therefore very excusable, in the case of the first observers and systematiats of
any newly- discovered group of organic beings.

Mr. Jefl&"eys {Proc. Boy. Soc, 1855) deplores the multiplication of species
and genera in the present day, and observes that " the Foraminifera exliibit a
great tendency to variation of form, some of the combinations (especially in
the case of Marginulina) being as compUcated and various as a Chinese puzzle.
It is, I beHeve, undeniable, that the vaiiabOity of form is in an inverse ratio

to the development of animals in the scale of Nature I am induced to

suggest the following arrangement : —

" 1. Lagena and Entosolenia.

" 2. Notlosaria and Marginulina, Sec.

" 3. Vorticialis, Rotalia, Lobatula, and Globigenna, &c,

" 4. Textularia, Uvigerina, &c.

" 5. Miliola, Biloculina, &c.

" This division must, however, be modified by a more extended and cosmo-
politan view of the subject, as I only profess to treat of British species. To
Ulustrate McLeay's theory of a quinary and circular arrangement, the case
may be jjut thus : —

" The first family is connected by the tyi)ieal genus Lagena with the second,
and by the Entosolenia with the fifth ; the second is united \xith the thii-d
through Marginulina ; the thii-d with the foiu'th thi-ough Glohigerina ; and
the fourth with the last thimigh Uvigerina."

"We append a tabular view of the groupings into families and genera, as
proposed by Trof. Schultzc, since it presents the most complete system yet pro-
duced, and advances much nearer a true arrangement of the Foraminifera
than that made by M. D'Orbigny,

OF THE rnOTOZOA. RHIZOPODA. 241

RHIZOPODA.

A. NUDA.
Qen. Amoeba (Noctiluca?).

B. TESTACBA.

I. MONOTHALAMIA.

Testa or sheU one-chambered ; animal imdivided, having the same confoi-mation as the shell.
Fam. 1. Lagynida.— A sacciform, calcareous or membranous, non-porous testa, with a large
opening.

Gen. ArceUa, Difflugia, Trinema, Euglypha, Gromia, Lagynis, Ovulina, Fis-
surina, Squamulina.

Fam. 2. Orbuhnida.— A globose, calcareous testa, finely porous throughout, without a
large opening.
Gen. Orbulina.

Fam. 3. Coknuspirida. — A calcai'cous shell, convoluted like that of a Planorbis, with a
large opening.
Gen. Cornuspira.

II. POLYTHAIiAMIA.

Shell polythalamous ; the animal composed of segments, connected by commissural bands.

1. Group Helicoidea.
The chambers disposed in a spiral.

Fam. 4. Miliolida. — Each chamber occupies a half-spiral, which is developed either in
one plane or in various planes. The shell has only one large opening
at the extremity of the last spiral, and no pores.
Gen. TJniloculina, BUocuHna, Miliola, Spiroloculina, Ai'ticulina, Spha:-
roidina, Adelosina, Eabularia.

Fam. 5. Turbinoida. — ^The chambers so disposed spirally as to resemble the sheU of Helis
or Turbo. The spiral is only visible on one side of the shell. Some
are so much elongated that the chambers are, aa it were, disposed
alternately in two contiguous rows. The shell has a large opening
in the last chamber, and its surface is almost always finely perforated.
Subfam. 1. Eotalida. — Shell flattened or conical; chambers do not encircle each
other ; shell glass-like, transparent ; finely perforated.
Gen. Eotalia, Eosalina, Truncatulina, Anomalina, Planorbulina, Asterigerina,
Calcarina, Siphonina, Planulina, Colpopleura, Porospira, Aspidospira.
Subfam. 2. Tlvellida. — SheU in the form of a longer or shorter cluster like a bunch
of grapes. The chambers frequently appear to almost completely
embrace one another. Shell usually tliick and coarsely perforate,
or solid.

Gen. Globigerina, Bidimina, Uvigerina, Guttulina, Candeina, Globulina,
Chrysalidina, Pyrulina, Clavulina, Polymorpliina, Dimorphina, Ver-
neuillina, ChUostomeUa, Allomorphina, Rhyuchospira, Strophoconus,
Grammobotrys.

Subfam. 3. Tcxtilarida. — Spire so much produced that the chambers form a double
row and alternate.

G«n. Gaudryna, Toxtilaria, Virgulina, Vulvulina, Sagrina, Bigenerina, Bo-
livina, Gemraulina, Cuneoliua, CUdostomum, Proroporus.
Subfam. 4. Cassididinida. — Textilaridce curved once in a direction perpendicular to
the original spiral.
Gten. Ehrenbergina, Cassidulina.

Fam. 6. Nautiloida. — The chambers so disposed spirally that the shoU has a general
resemblance to that of an Ammonite or Nautilus. The spire is either
visible or, otherwise, concealed on both sides of tlie shell. The anterior
wall of the last chamber is furnished with one larger or several smaller
openings ; the other portion of the shell is usually finely perforated
Subfam. 1. Griitellarida.—'&\\^\S. thick, finely perforate, colourless, transparent-
chambers encircling, witli a large opening at the upper angle of the
anterior wall of tlio last chamber, which corresponds in position with
the communicating opcnmgs between the several chambers.
Gen. Cristellaria, Eohidina, Marginulinn, Flabellina.
Subfam. 2. iVo«w««rf«.— Shell tliick or thin, colourless, transparent, fi^iely perforate •
chambers either encircling (imbricate) or not. The opening is in' the

R

242

GENEKAL HI8T0EY OK THE INPUSOKIA.

anterior wall of the first chamber on the under side looking towards
the penultimate spiral ; the communicating openings of me several
chambers have a similar position.

Qen. Nonionina, Hauerina, Orbignyna, Fusulina, Nummuh'na, Assilina,
Siderolina, Amphistegina. OperculLna and Heterostegina should pro-
bably be formed into a sjjecial subfamily of Nonionida.
Subfam. 3. Peneroplida. — Shells usually thin, always brown, and transparent vrith or
without fine pores ; the chambers very narrow, either imbricate or not.
Numerous openings, scattered over the whole of the anterior wall of
the last chamber ; or, instead of these, a large opening produced by
the coalescence of numerous smaller ones.

G«n. PeneropHs, Dendritina, Vertebrahna, Coscinospira, Spirolina, Lituola.
Appended genus, Orbiculina.
Subfam. 4. Polystoviellida. — Shell tolerably thick, colourless, transparent, finely por-
ous ; chambers imbricated ; the anterior wall of the last chamber
has, besides the fine pores, either no larger opening at all, or a few
very small irregular scattered fissures, on the contrary side to the
penultimate whorl. The same applies to the septa. On the surface
of aU the chambers, rows of fissure-like, often perforating, depressions
are placed at right angles to the direction of the septum.

Gen. PolystomeUa.

Fam. 7- AiiVEOLiNiDA. — Globose, ovoid, or barley-shaped shells, composed of spiral tubes,
each resembling a cornuspira, and furnished with a special opening
at the end of the turn or spiral. The tubes all communicate by con-
necting openings, and, besides this, are all subdivided by incomplete
dissepiments (partitions), in the same manner as species of Nonionina.
The situation of these septa, which are but few in nmnber, and of the
connecting openings, is indicated by lines, which traverse the shell in
the dii'ection of meridional lines.
Gen. Alveolina.

Faon. 8. Soritida. — Discoid, multicellular ' shells, exhibiting an indication of a helicoid
spiral only in the centre ; elsewhere cycloid, that is, growing uniformly
at the whole border of the disk. The brown, transparent, finely porous
shell is formed of minute chambers, connected together in the direc-
tion of straight or curved radii, and each presenting a large opening
at the border of the disk.
Gen. Sorites, Amphisorus, Orbitulites. Appended genius, Cyclolina (cham-
bers perfectly annular, with numerous openings on the border of the
disk).

2. Group Ehabdoidea.

The chambers piled one on another, in a straight or slightly curved Une, in a single row.

Fam. 9. Nodosarida. — Rod-shaped shells, whose chambers are superimposed one upon
another in a row, and commmiicate with each other by a large
opening; a similar opening in the last chamber (except in tlie
genus ConuUna, which haa numerous openings instead of tlie single
one). The shell usually thick, probably always perforated by fine
pore-canals.

Gen. Glandulina, Nodosaria, Orthocerina, Dentalina, Frondicularia, Lin-
gidina, Eimuliua, Vaginulina, Webbina, Conulina.

3. Group Soroidea.
Chambers groujDed in irregular masses.

Fam. 10. ACERVULINIDA.— Chambers usualljr globose, disposed very irregularly, and of
prettjr uniform dimensions ; shell fijiely pecforate, with a few larger
openmgs at indeterminate places.
Qtjn. Acei*vulina.

The preceding account of the Rhizopoda we believe to be ample to lead tlie
student forward in the study of that peculiar class of animals. Yet, with re-
spect to the division Foraminifera it may bo considered less complete : for.
from the close attention given of late to those beings, every monthly and
quarterly periodical of natural science teems with fi-esh facts and opinions
concerning them ; and, abovo all, we have had placed in our hands, since the
foregoing history was written, the very elaborate and critical researches of

OF THE PROTOZOA. ACTINOPHEYINA.

243

Prof. Williamson and Dr. Carpenter, to which we would particularly refer
the iaquii-er intent on following out his knowledge of the Foraminifera, but
which both the dimensions and the character of the present work forbid the
attempt to condense or analyse in its pages. Prof. WUliamson's work, ' On the
Recent Foramhiifera of Great Britain,' forms the volume for 1857, published
by the Eay Society. Dr. Carpenter's learned essays on the structui-e of
shells, on the value of form and other external characters in generic and spe-
cific groupings, and on the structm-al and physiological relations of several
genera, are to be found in the ' Transactions ' and in the ' Proceedings ' of
the Royal Society.

Additional facts concerning both the structure and relations of the several
groups of Rhizopoda will be found in our Systematic History of them in Part II.

SUBFAMILY OF RHIZOPODA, ACTINOPHRYINA.
(Plate XXIII. 24-37.)

This is a remarkable group of Protozoa, which can take its place neither
with Ciliata nor strictly with Rhizopoda, although its aflBnities with the latter
are very close. Ehrenberg attached the several forms of this family with
which he was acquainted to his heterogeneous collection — the family Enchelia,
and referred them to five genera, viz. Actinophrys, Tricliodiscus, Podophrya,
Dendrosoma, and Adneta. Moreover, according to his fundamental hypothesis,
he represented them to have a mouth and an anus, an alimentary canal with
offshoots in the shape of stomach-vesicles, a sexual gland, and ova. Since
the Berlin pi-ofessor's investigation of these animalcules was made, several
distinguished naturalists have most carefully studied them, and particularly
the Actinophrys Sol.

In oiu' last edition we named a genus Alderia, in honour of Prof. Alder, to
distinguish certain organisms described by him in the Annals of Natural His-
tory (1851, vii. p. 427). Subsequently, however, that eminent natiu'alist wrote
us to state that the name proposed had been already applied to a genus in an-
other class of animals ; and on farther consideration and reference to Stein's
researches, we were inclined to renoimce their claim to a generic independ-
ence, and to consider them three forms of Podoplirya. Dr. S. Wright has,
however, apparently obsei'ved the same beings very lately, and instituted a
new genus, Ephelota. to receive them (Edinb. New Phil. Journ. 1858, p. 6).

Notwithstanding the very close affinities of Actinophryina and Acinetina,
there are sufficient differences between the two, and so many peculiar forms of
the latter that they deserve a particiilar consideration.

The liistory of the first family is very fairly represented by that of Actino-
phrys Sol, or of Act. Eichornii, both of ^^'l^ich have been veiy completely
studied by Siebold, Kollikcr, Claparcde, Stein, and "Weston. Some diversity
prevails among these several obsei-vers respecting a few points in their organ-
ization, which it will be incumbent on us to notice in the proper place. The
species of Actinophrys have a circular figm'e, and are either spherical or so
compressed as to have a discoid fom (XXIII. 28, 29). The distinctive
peuliarity of their figure is, however, due to the filaments or tentacles, which
radiate from aU parts of theii- surface and give the beings (to employ a
familiar and not inapt illustration) the appearance of a ball of cotton stuck
thickly over with pins ; for tho filaments have nodular exti-emitics, or, in
technical phrase, are capitate. The figure is determinate, and in this respect
contrasts with the protean changes of form exhibited by Rhizopoda. Not
that the figure is completely unalterable ; for slight variations are possible.

R 2

244

GENEBAL HISTOBT OF THE INFUSOBIA.

although slower than even those of Amoeba. Stein represents the usual orbi-
cular figui-e to be frequently exchanged for a pear-shaped, an oblong, or a
partially ang-ular and lobed one, — varieties dependent, according to his state-
ments, upon inherent changes taking place in connexion with progressive de-
velopmental phenomena. The aspect of the entire organism is, moreover,
modified fi'om time to time, by the altered length, direction, and disappear-
ance of a portion of the filaments, chiefly consequent on the act of prehension
in which they are engaged. Stein, indeed, represents still more considerable
modifications, involving the complete disappearance of tentacles from various
portions of the surface, and the aggregation of the rest upon angular emi-
nences in a penicillate manner, — an occurrence which would assimilate still
more closely the ActinophryiTia and the Acinetina. Lastly, the figure is varied
during the acts of self-division and of conjugation, as will be presently noticed
at large.

In colour the Actinophryina are commonly of a milky-yellow or gi-eyish
hue, the intensity of which is determined by the number of contained granules,
or, in other words, by the supply of nutriment. Acetic acid and cold solution
of potash remove coloui- ; the latter fluid, when heated rapidly, dissolves the
entire mass, and indicates its nitrogenous nature. Observers are not agreed
on the point of the existence of an integment. Dujardin, Kolliker, and Cla-
parede deny it, whilst Stein, Perty, and Mr. Weston (J. M. S. 1856) afSjm its
presence. Among the latter, one speaks of it as a hyaloid membrane ; another
declares it to be double, consisting of a delicate elastic membrane immediately
investing the contractile substance of the animalcules, covered by an outer
fii-mer timic. This statement is especially made by Stein of Pocloplirya, which
is, in his opinion, a merely stalked variety of Actinophrys, and indistinguishable
from it even as a species (XXIII. 1, 3, 4, 5). On the contraiy, Cienkowsky
(J. M. 8. 1857, p. 98) remarks that he could discover no membrane surround-
ing the body of that animalcule. To account for this diversity in descriptive
details, we must suppose that the diff'erent authors have not had the same
animalcule under observation ; indeed Stein asserts that Kolliker did not
examine Actinophrys Sol, as he supposed, but Act. EicJiornii. Lieberkuhn
likewise suggests that Claparede and Kolliker have written upon different
species under the same name ; and Stein must, we believe, have committed
a similar mistake ; for the Actinophrys and Pocloplirya described by him differ
in so many important particulars from beings beai-ing the same name in the
writings of others, that it seems impossible they can be identical with them.
The fact seems to be that certain Acinetoi have in external characters so close
resemblance ioActinopliryina,t\ia.i they may be mistaken for them. Be this ho^^■
it may, if we take into consideration the peculiar relation of the tentacles with
the body, their movements, and especially the mode of introducing food into
the interior, it seems quite improbalile that there should be a firm investing
membrane. These remarks, indeed, apply only to the usual forms or phases
of these beings ; for when an encysting process proceeds, then, certainly,
an external envelope will manifest itself, yet not without the saciifice of the
tentacula and of the orchnary phenomena of vital actidty, the ingestion of
food and the lilce. " It is impossible," to quote Claparede {A. N. H. 1855, xv.
p. 286), " to admit the existence of a general integument, as Actinophrys can
push out the mucous or gelatinous matter of which its body is composed, take
in nourishment, or evacuate the residue of digestion, from any point of its
surface at pleasure." In this same observer's opinion, Perty's notice and
figures of a capsule are evidently erroneous, the consctjucnce of optical illu-
sion. Mr. Carter adopts an intermediate opinion, by admitting the existence
of an enveloping pellicula, like that in Amceba, wliich, although not a separable

or THE PROTOZOA. — ACTINOPHEYINA.

245

layer or skin, is a somewhat firmer or more condensed tissue than that sub-
jacent.

The Actinopliryhia are composed of a homogeneous elastic sarcode, occupied
by granules ia varying number, and by vacuolaj. The granules are especially
accumulated in the centre, to wliich they consequently impart a greater opacity
and deeper coloiu-. Hence several authors have spoken of a central medullary
mass sm-roimded by a clearer cortical lamina (XXIII. 28, 29). Still there
is no natiu-al separability into two such portions ; for their relative size varies
according to the supply of food received. Dr. StrethUl Wright (in a letter)
proposes to apply the imexceptionable terms " endosarc " and " ectosarc " to
the medullary and cortical portions respectively. The contained granules arc
rounded, opaque, and, for the most part, of a fatty character. The granules
are less abundant in the ectosarc ; but those of a; finer sort are seen in smaller
numbers even in the lower end of the filaments, and Lachmann (A. iV. IT.
1857, xix. p. 223) asserts that he has seen their motion there, as weU as in
the general substance of the body. Mr. Weston also remai'ks (op. cit. p. 122),
" With a -i-th objective I can distinctly see granules in constant motion in the
body of the Actinojfhrys, similar to those always found in the points of Clos-
terium Lunula." The vacuoles occur both in the cortical and meduUaiy
portions, but are smaller in the latter, and they never penetrate into the
substance of the filaments.

At first sight, as Kolliker notices, the tissue appears delicately cellular : a
closer inspection, however, shows that this is not the case ; for on pressure
being made, a coalescence into larger, or, otherwise, a subdivision into smaller,
areote is the consequence (XXIII. 28, 29, 30).

The tentacles or filaments give to the Actinophryina their most distinctive
features. They are usually pretty regularly and uniformly distributed over
the entire surface, and in figure taper from the base to the apex, which is
surmounted by a rounded knob. Unlike other observers, Cienkowsky {J. M. S.
1857, p. 101) represents the capitate form to be exceptional, and that the
rule is for the filaments to taper like sette. Dujardin, by the way, appears to
have thought the capitate extremities accidental ; for he describes the filaments
as often becoming globular in the act of contraction. In smaller specimens
the filaments exceed the diameter of the body in the length, but in larger
ones are not more than equal to, or are even less than, it. In the same
species their number and position are tolerably constant. In composition,
the tentacula are processes given off from the sarcode mass, and are destitiite
of an integument, as proved by their power of coalescence when approximated.
'I'hey are retractile, and can be withdra^vn into the common mass ; they can
iilso be directed towards different sides, and curved upon themselves. Perty
Nlatcs that they can assume so rigid a condition that other animalcules some-
times impale themselves upon them ; this statement is nevertheless uncon-
lirmed, and, indeed, seems scarcely probable. KoUiker (op. cit. p. 31) speaks
of the filaments as undergoing various changes of form, " such as elongation,

shortening, local sweUing, bending, &c It is especially interesting to

observe that the filaments, singly or together, frequently disappear entirely,
i iitering at last, as it were, by continued retraction, into the substance of the
liody, leaving no trace of their former existence. . . .whether the filaments
\\ liich disappear are always reproduced in the same spot is not determined •
in some instances this did not appear to be the case, although in every

instance the number and position of the filaments is pretty constant " unlike

(ho variable processes of Amoeba. Ehrenborg assigned to the tentacles,
iniong other purposes, that of organs of progression ; chrect obser^^ations arc'
liowever, wanting to prove this purpose, and both KoUikcr and Stein are

246

GENEHAL HISTOEY OF THE INFU80EIA,

quite iinable to admit it as even probable. They have been supposed by
several authors to have a benumbing effect upon the prey they may seize ;
but this view is merely hypothetical. " It is nevertheless," says Claparede
(qp. cit. p. 287), " quite certain that small animalcules and plants remain
adherent to them ; for these rays are true tentacles. Indeed, their contact
must have something very unpleasant about it ; for larger Infusoria, even
such as Paramecium Aurelia, on coming accidentally within their reach, staii;
back with the greatest rapidity, sometimes even dragging the Actinophrys a
considerable distance with them." So, again, Weston states — " on the instant
of contact with these tentacles, the victim appears paralysed." Yet, -wdthal,
it seems clear that, unless actual contact ensue, no harm attends proximity
to the formidable prehensile organs ; for animalcules may frequently be seen
swimming about unharmed among them. KoUiker rejected the supposition
of an intrinsic fatal influence existing in the filaments, which appeared to
him to serve only for retaining the prey by theii- adhesive surface, and pro-
bably to involve it with their extremely fine extremities, until they drew it
by their progressive contraction to the surface. Even after being seized upon,
an animalcule may escape, both by great exertions ia tearing itself away, and
sometimes, as Mr. Weston remarks, by the act of the Actinophrys, when, as
it would seem, its appetite was " sated, or the prisoner was not approved ;
for after remaining stunned sometimes for a few seconds, four or five, some-
times much longer, ciliary motion (of a Vorticella, for instance) is feebly com-
menced, not with sufficient energy to produce motion, but as if a return to
vitality were being effected by stiniggles ; shortly it is seen to glide off the
tentacle (as if this appendage possessed the power both of appropriation and
rejection), and, frequently with but little sign of recovered hfe, it slowly floats
out of the field." One function distinctly possessed by these tentacula is
that of sensibility. KoUiker has thus well conveyed this fact (op. cit. p. 33) :
— "Actinophrys perceives mechanical influences, and reacts upon them by
movements. This is proved by what takes place when animalcules, &c.
remaia afiixed to its tentacles, and moreover by the circumstance that, when
the water in which it is contained is carelessly agitated, eveiy Actinophrys
contracts its tentacles and even makes them disappear altogether (and,
indeed, with greater speed than is othei-wise perceived in these creatm*es),
and when all is quiet they are again protruded. These filaments, conse-
quently, may just as Avell be called tactile as prehensile ; or it may more
generally be said, that the substance of the body is both contractile and
sensitive."

Movements. — There is not much to be said respecting the movements of
the Actinophryina ; for these beings are even more sluggish than the Amoehcfa,
and appear to change place rather as mere passive particles of matter than as
living animals. They may float hither and thither in the fluid surrounding
them, or rise to the siii-face ; but how this latter movement is eftccted we have
no data to show. On this subject Kolliker has the following pai-agraph:—
<' Its power of moving from place to place is indubitable ; for it was foimd, for
instance, that when a vessel, with several individuals of Actinophrys, was
emptied into a flat glass capsule, they were all at fii-st scattered about at the
bottom, but subsequently, after fi-om 12 to 24 houi-s, were all floating at the
surface, and, indeed, at the side of the capsule. Ehrenberg and Eichhom
assert that the ascension of Actinojyhrrjs m the water is effected by the taking
in, and the descent by the giving out, of air. But tliis is ccrtaiidy not the
case ; for whence could they obtain this air ? Can it be said they secrete it
within themselves like fishes ? In that case it must be ^^sible. It appears
to the author move natural that the rising and sinkijig should be effected by

OF THE PBOTOZOA. ACXINOPHRYINA.

247

alternate contractions and expansions of the whole body. Other motions can
affect both the filaments and the body, but in any case only through the
slowest possible contractions." Besides these ill-understood translations
from place to place, and those movements chiefly affecting the tentacles_ m
the act of taking in food, to be presently noticed, there also occur, according
to KoUiker, " faint indications of contraction, such as slight undulations of
the border, and inconsiderable quivering motions here and there. The creature
also seems to be capable of altering its entire form to a certain extent, and to
be able to expand and to contract itself m toto." Stein contradicts these
statements, affirming that he could neither observe any movement in the
organic mass, nor any change of position, whilst Claparede, on the other
hand, writes, " nevertheless the animal, in its ordinary sun-like form, is able
to move slowly in a given direction ; but during this movement no contraction
of the body or bending of the tentacles is to be observed." A singular obser-
vation is recorded by Mr. Boswell {T. M. S. 1854, p. 25), which needs con-
firmation before it can be accepted, viz. that the Actinophryina can suddenly
change their place by a leap. This phenomenon, he tells us, he witnessed
twice among a number of the animalcules found floating on the surface of the
water. Usually the Actinophrys is found attached to some object, and that
so firmly that large animalcules may strike against it, or strong succussions
of the water take place without loosening it from its hold. Podophrya and
Dendrosoma are exceptional Actinophryina, by possessing a pedicle. In the
former this stem is commonly short and always simple, whilst in the latter
and hitherto little-known genus it is branched. As elsewhere noticed, Stein
will not admit the pedicle of Podophrya to be a generic, indeed not even a
specific, distinction, and therefore treats Actinophrys and Podophrya as
identical. In connexion with his belief in the presence of an enclosing
integument, he describes the wall of the hollow pedicle of Podophrya to be
continuous upwards with the external envelope of the body (XXIII. 3, 4).
It is proper, however, to remember that Stein wanted both to establish his
hypothesis of the conversion of Vorticella into an Actinophrys and Podophrya,
as a consequence of the act of encysting, and preparatory to embryonic repro-
duction, and, further, to assimilate those genera with various Acinetce, which,
in his opinion, were derivable from other members of Vorticellina. This
detracts from the value of his details of the structure and functions of Actino-
phrys ; and, as expressed above, a great doubt suggests itself whether he has
always examined the selfsame animalcules, and whether what he has de-
scribed appUes to the Actinophrys investigated by KbUiker and Claparede.
Cienkowsky, who has latterly tested Stein's hypothesis, asserts, respecting
the question of the structure of the stem of Podophrya, that the pedicle is
an appendage to the body, which has no integument. * " I am imable " (op.
cit. p. 100), he ^vrites, " to adopt Stein's view that the Podophrya are enclosed
in & membrane, of which the slender pedicle is simply a tiibiilar protiiision.
This is true only -with respect to tho short peduncle of the encysted Podonhrva "
(XXIII. 36, 37). ^

Prehension ajjd Entrance or Food. — The movements of the tentaciUa of
Actinophryina are chiefly directed to the prehension of prey for food. This
they efi'ect primarily by seizing it by means of their apparentiy sticky surface,
and then, by shortening themselves, (bag it to the surface of the animalcule!
If the prey has been caught by one tentacle, tho neighbouring ones conspire to
clutch it more firmly, and (to use KoUiker's words) " apply themselves upon
it, bending their points together, so that tlio captive becomes gradually en-
closed on aU sides." This concurrence and crossing of tho tentacles is men-
tioned also by Stem ; but Mr. Weston states that he has never witnessed it

248

QENEEAX HISTOBY OP THE INFUSOBIA.

Concerning' the mode of entrance of the nutritive matter when drawn to the
siu'face, some difference of opinion prevails among the several writers wlio
have treated of it. Ehrcnberg, true to Ids hypothesis, attiibuted to Actino-
■phri/ina a mouth surmounted by a proboscis, and an anus at the opposite side
with an intercommunicating intestine and nimierous stomach-sacs opening
into it. In short, they wore, according to his scheme of organization,
Enantiotreta, of the class Enterodela. Dujardin rejected this accoimt, and
supposed them to be nourished by absorption, carried on by the general
surface, or by means of thick expansions from it. At the present tune all
observers unite in denying a mouth, anus, and alimentary canal to Actino-
phryina, and in admitting that food may be iatroduced, and its debris dis-
charged, at any part of the siuf ace, — a fact patent to direct obseiTation, which
shows the seizing and the entrance of prey going on, occasionally, at more
than one point at a time (XXIII. 29-32). We have followed the captured
morsel imtU it approaches the sni-face, and when the force of the tentacles
behind it still tends to press it onwards into the body. The following pro-
ceeding, accordiag to KoUiker {op. cit. p. 28), now takes i^lace :— " The spot
of the sui'face, upon which the captured animalcule is lying, slowly retracts
and forms at first a shallow depression, gradually becoming deeper and deeper,
in which the prey, apparently adherent to the surface and following it in its
retraction, is finally lodged (XXIII. 29 m). The depression, by the continued
retraction of the substance, now becomes deeper ; the imprisoned animalcule,
which up to this time had projected from the surface of the Actinophrys,
disappears entirely within it ; and at the same time the tentacles, which had
remained with their extremities applied to each other, again erect themselves
and stretch out as before. PinaUy, the depression acquires a flask-Hke form,
by the di-awing in of its margin, the edges of which coalesce ; and thus a
cavity closed on all sides is formed, in which the prey is lodged. In this
situation it remains for a longer or shorter time, gradually, however, ap-
proaching the central or nuclear portion, and at last passing entirely into it
in order to await its final destination. In the meanwhile the external por-
tion of the Actinophrys regains in all respects its pristine condition. The
engulfed portion is gradually digested and dissolved." Whilst admitting
the general correctness of this account by KoUiker of the act of inglutition.
Stein asserts that, prior to the appearance of the prey in a depression of the
body, a large vacuole, rising above the sui'face, comes into contact Avith it, and
then, by its collapse, drags it downwards into the substance of the animalcule.
This stage he supposed KoUiker to have overlooked. However, Claparede
denies that the reception of food is ever effected by means of the expansion
and contraction of a vesicle, or that, as KoUiker behevcd, the food penetrates
the substance of the body by the force exercised upon it behind by the
tentacula : it is rather, he says, the substance of the body which approaches
and embraces the food ; for before the latter has touched the surface of the
body, it is seen to be enveloped in a kind of mucus. Tliis mucus is com-
pletely undistinguishable from the parenchyma of the Actinophrys ; it appears
as though the substance of which it is composed had suddenly draAvn itself
over the captured object. The elevation thus produced then slowly flattens ;
and by this means the food is graduaUy di'awn into the body. Astasia, which
I frequently saw sucked in by Actinophrys in this way, continued to move
for a little time, endeavouring to break thi'ougli the substance that enveloped
them ; their movements, however, soon ceased ; they became converted into
a globular mass, which circulated very slowly thi'ough the parenclijnua wnth
the so-caUed vacuola." . ..." At first I tliought the substance, which so
suddenly enveloped the object to be swallowed, was produced hy the mere

OF THE PROTOZOA. AOTINOPHBYINA.

249

bending, expansion, and fission of the tentacles. I could not, however,
retain this opinion: an extension of a mucous substance, apparently the
pai-enchyma, really takes place from the side of the Actinophrys ; and this is
afterwards drawn in with the prey. This expansion sometimes takes place
very slowly ; a thick, regularly lobed mass is seen to embrace the object ;
and I have once obseiTed this extension -without the presence of any prey.
I can only compare this process with what takes place in Amoeba." Dr.
Strethill Wright (in lit.) expresses the same fact in a condensed form,
thus : — " In Actinophrys the tentacles bring the food to the surface of the
ectosarc, which closes over it and carries it to the endosarc." Mr. "Weston's
observations tend to a similar interpretation of the mode of introduction of
food. " From the margin of the body of the Actinophrys," says this gentle-
man, " a thin pellucid membrane is projected up the side of the creature
destined for food (XXIII. 24-32), which proceeds rapidly, but almost
imperceptibly, to surround one side of it ; a similar membrane springs
sometimes also from the Actinophrys, but more frequently from the tentacle
on its other side ; these amalgamate on the outer surface of the prisoner,
which is thus enclosed in a sac composed of what I take to be the extended
outer vesicle of the Actinophrys. This vesicle gradually contracts, or, rather,
seems to return by elasticity to its original position ; and the food thus be-
comes pressed within the body, there to become digested." The conclusion
to be drawn is, that, after the act of prehension by the tentacles is complete,
the retraction of those processes is succeeded by the protmsion of a sort of
variable process, similar to those of Amoeba in character, and also in its mode
of enveloping and engulfing the morsel.

After its admission into the soft substance of the interior, the nutrient
matter undergoes a process of digestion, by which, if soft, it suffers complete
dissolution and absorption; but if it contain insoluble matter, this remains
behind, after the disappearance of the rest, as a residue to be sooner or later
cast out through an aperture temporarily formed at the point of the surface
it comes into contact with, and of which aU trace is lost so soon as the act of
extrusion is accomphshed. The molecular and granular matters derived from
food collect especially in the central or nuclear portion of the body, the depth
of colour, opacity, and strength of which are directly proportionate to the
supply of food. The particle of food (the animalcule or other substance),
when in the interior, is surrounded by or suspended in a drop of fluid, or, in
Dujardin's phi-aseology, occupies a vacuole. This fluid is either di-awn' in
by the act of inglutition, or is a secretion poiu'ed out aroimd the food for the
pui-pose of digestion. Claparode takes the latter view, and states that the fluid
always exhibits the same pale-rcdcEsh colour as the contents of the contractile
vesicle, and indicates cUfferent refractive powers from those of water. Tliis
observation accords with one made by Schneider, of the digestive vacuoles of
Amoeba.

The process of digestion is slow. Claparede obsci-ved the changes of a
Chlamydomonas, and states that three hom-s scarcely sufficed for its conver'-
sion into an unrecognizable gelatinous mass. KoUilcer represents the time to
vary from two to six hoiu's ; but this must diff'er perpetually accordino- to the
nature of the food, the vitaUty of the animal, &c. <' The number, as well as the
size," wntcs Kolliker, " of the morsels taken at one time by the Actinonhrm
18 veiy yanous. Veiy frequently there may be 2, 4, or 6 at the same time
frequently also more than 10 or 12. Ehrenberg coimted as many -is Ifi
stomachs, r e. m other words, so many separate morsels. He also noticed the
'"J-^u'I^T^'"'"^.'^ not have gained admission in any other way
than that by which the Infusona and other ahmcnts enter. The largest moi"cls

250

GENERAL HISTOKY OF THE INFUSORIA.

noticed consisted of a Lynceus and a young Cyclops. Eichhom, indeed,
mentions a water-fiea (Daphnia ?), about the size of which, however, no re-
mai-k is made." Indeed, the Actinophryina are rapacious animals, and will
appropriate to themselves any organisms, vegetable or animal, which fall in
their way. Thus, besides those beings alluded to already, Rotifera, various
minute Cinistacea, Ciliated Protozoa, Phytozoa of aU sorts, Desmidieas, Dia-
tomeae, minute Algae, and their spores alike fall a prey to these remarkable
animalcules. The excrementitious particles of food, as already stated, pass
out at any spot where circumstances may direct them ; and no definite anal
aperture, such as Ehrenberg imagined, has an existence. The expulsion of re-
sidual matters, Mr. "Weston {J. M. S: 1856, p. 121) states he has " frequently
seen, — in one specimen twice in less than half an hour, at different spots. In
watching the digestion of a Rotifer, it occurred to me to see a dark body,
composed apparently of the case, remain for some hours in the same spot,
and then gradually approach the side, as if for expulsion ; but while waiting
for this to take place, an opening in another part occurred, and excrement
was voided in quantity : this voided matter lies amongst the bases of the
tentacles, whUe the opening through which it has passed closes ; and then,
with the same stealthy motion I have before described, it is apparently driven
along the tentacles (as if by repulsion) beyond their extremities, finally dis-
appearing in the surrounding medium."

Contractile vesicle. — The rule is, that only one conti'actile vesicle belongs
to each animalcide (XXIII. 36, 37). K more appear, it usually indicates
either the approach of fission, or the conjugation of two or more individuals
(XXIII. 33-35). KoUiker failed to recognize this organ in Actimplirys, and
concluded that Siebold had described as such the mere changeable vacuola.
However, Stein, Claparede, Cienkowsky, and others concur in representing a
contractile vesicle as normally present ; the first-named writer, indeed, de-
scribes in a few instances two such, as Siebold has done before him. Stein
exhibits, in Actinophrys Sol, the vesicle as central (XXIII. 1) ; but other
naturalists concur in representing it as superficial, — so much so, according to
Siebold, that it will frequently during its expansion project above the general
sui-face, and thereby prove itself to have a distinct wall (XXIII. 29 m) ; for
if composed .of only the gelatinous parenchyma of the body, it would burst at
the moment of greatest expansion. It is, therefore, a closed sac or cell.
Claparede has never found more than one vesicle, and thinks both Siebold
and Stein in error in describing two. " Several vesicular elevations," he
writes, " often occur on the margin ; but only one of these is contractile. I
have, however, observed two contractile vesicles in several individuals ; but
in these cases the form always gives rise to a suspicion of fission, or of an
amalgamation of two individuals (Act. cUfforinis, Ehr.). The pi-esenee of a
single contractile vesicle does not, however, appear to be universal among the
Rhizopoda ; I have observed two in Arcella vulgcms .... It is suri)rising that
KoUilcer, who was acquainted with Siebold's observations, should have cha-
racterized them as inexact, and as aiising from an illusion. According to
him, Siebold had mistaken accidental expansions and contractions of the sub-
stance enclosing the vacuoles, in which the latter were pei-sistent, for phe-
nomena indicating the existence of contractile reservoii's. Tliis, however, is
not the case ; the size, the unchanging position, and the regular expansion
and contraction of this organ will prevent its being confounded with a
vacuole. That KoUHcer should have overlooked it is particularly iminteUigi-
blc, as the phenomenon is immediately presented by nine out of ten specimens
of Artinophrys."

Carter (A . N. H. xviii. p. 129) makes the curious assertion, that the "Aciino-

OF THE PROTOZOA. ACTINOPHKYINA.

251

^yJiri/s Sol, Elu-., is surrounded by a peripheral layer of vesicles " (he is speaking
of contractile vesicles), " which, when fuUy dilated, appear to be all of the
same size, to have the power of communicating with each other, and each,
individually, to contract and discharge its contents externally, as occasion may
require, though generally only one appears, and disappears, in the same
place." Stein describes and flgui-es a row of vesicles immediately beneath
the sm-face of a new species he calls Actinophrys oculata (XXIII. 24, 25),
but does not, like Carter, treat them as so many contractile sacs, an interpre-
tation which cannot be received without much more extended inquiry and
confirmation. Notwithstanding this assei-tion, Mr. Carter, in his outline of
facts relevant to contractile vesicles in general, has the following clause, ap-
plying specially to the animalcules under consideration, and giving a most
apt illustration of the phenomena witnessed: — "In Actinophrys Sol, and
other Amcebce, during the act of dilatation, the vesicula projects far above the
level of the pellicula, even so much so as occasionally to form an elongated,
transparent, mammilliform eminence, which, at the moment of contraction,
subsides precisely like a bhster of some soft tenacious substance that has just
been pricked with a pin." At another part, this same author says, generally
(op. cit. p. 128), and in some measm'e contradictorily to the first statement
quoted from him, that "in Amoeba and Actinophrys the vesicvila is generally
single ; sometimes there are two, and not unfrequently ia larger Amoebcea a
greater number." It should be mentioned that Stein found in the animal-
cule, which he took to be Act. Eicliornii, a superficial group of vacuola, ren-
dering the outline irregidar, — a phenomenon no doubt the same as that
intended by Carter. Stein, moreover, described in the same animalcule two
contractile spaces, one at each pole, immediately beneath the surface, but
capable of alternately elevating themselves above, and depressing themselves
within it, and of thereby aiding to introduce food.

Podophrya has, accordiag to Stein and Cienkowsky (XXIII. 34, 35, 36,
37), a single circular contractile vesicle. Stein, iadeed, figures two in one
specimen. So far as appears, the vesicle is not placed so close to the surface
as in Actinophrys. Among other structures mentioned by Ehrenberg, was a
contractile proboscis, by means of which the animalcule was supposed to re-
ceive food ; but other observers have looked in vain for any process to which
such an appellation coiild with justice be applied. The structure intended
by Ehrenberg is, in Claparcide's opinion, no other than the contractile vesicle,
—an opinion ia which Mr. Weston seems to agree (see below), although he
attributes to it a structiire and action without parallel in other Infusoria. A
glance at the quotation above made from Mr. Carter's paper wiU show also
that the contractile sac was intended. The following ai-e the observations of
Claparede, referring to the matter in question:— "From time to time a "-lobular
prominence rises slowly and graduaUy from a particular point on the^'surface
of the ammal ; this mcreascs more or less in different cases, sometimes espe-
ciaUy m smaU mdividuals, attaining nearly a third of the size of the' entire
body, but generally reaching only ith or -jl^th of that size. The maro-iji of
this projection is always weU defined, much more so tiian tiie other parts of
the body, especially when it has attained its greatest evolution At this
moment It contracts suddenly and disappears entirely, so that a flatteninff of
the outline is often to be obseiwcd at the point previously occupied bv this
remarkable elevation : the margin soon becomes rounded again ; the elobulnr
prqjection gradually rises attains its previous highest development, and then
suddenly clisai)pcai^ again." Tlie following paragraph from Mr Weston^
paper {J M. S. 1856, p. 116) refers, doubtless, to the selfsame expanding and
contracting process distinguished by Claparede ; but the function of '^sS^on

252

GENERAL HISTOHY OF THE INFUSOEIA.

and a valvular structure of a very extraordinary nature are attributed to it.
"We suspect, indeed, that Mr. "Weston lias been led into error by appearances,
— a supposition he wiU pardon us for making, since, as he himself tells us, his
microscopic experience is loss than two years old. His account runs thus : —
" There appears to be no doubt about the existence of a valvular opening : I
have had some thousands of these animalcules under my observation, and
have never met with a specimen where the valve was absent. It is best
distinguished when about the edge of the seeming disc, and, so far as my
observations go, is never still night nor day, — being slowly, but without cessa-
tion, as it were, protruded, occupying fi-om 10 to 70 or 80 seconds in its
development, and then, Uke the bm-sting of a vesicle, rapidly and totally
subsiding ; for an instant it has utterly disappeared, only to be again as
gradually and as certainly reproduced. Should that side of the creature,
where the valve is placed, be tiu-ned from the observer, the effects of the
contraction are distinctly seen, although the valve itself is not ; for at the
instant of its bursting and closui-e, some half-a-dozen or more of the tenta-
cles, situated on or ahout it, which have been gradually thi'ust from theii'
normal position by the act of its protrusion, now rapidly approach each other
with a jerk-Hie motion, caused by the sudden biinging together of their
bases.

" "With ith of an inch objective, I have been led to imagine the valve to be
formed of a double layer of the external hyaloid membrane, the edges of
which appear to adhere to each other tenaciously, notwithstanding the
growing distension from within, until the force becomes so great that the
lips, as they may be called, suddenly separate, apparently to give vent to
some gaseous product ; and at this moment there is, as I have stated, enough
seen to induce the belief in the existence of a double Hp-like valve, perhaps
the organ of respiration."

He afterwards adds (p. 118) — " In many instances I have seen half-a-
dozen or more prisoners attracted to the tentacles of an individual, each gra-
duaUy absorbed ; and although thus busily occupied, no cessation of the action
of the valve takes place." Stein imagined the movements of the contractile
sac to be subservient to the reception of food ; but this supposition, as men-
tioned already (p. 248), is opposed to analogy, and is wanting in direct obser-
vation to establish it.

Among the general contents of tha body of Actinophrys, KijUiker {op. cit.
p. 27) mentions some separable nucleai* ceUs as detached by crushing from
the innermost portions of the animal. "When isolated by pressure, they be-
have themselves as cells, with nucleus and nucleolus, sometimes as free
nuclei. " The author is, in fact, inclined to regard them as ceUs and nuclei,
lying in some of the interior vacuoles ; for such, and such only, are the vesi-
cular spaces in which they are enclosed." (XXIII. 29.)

Nucleus. — KolHker appHcd the term nucleus, very improperly, to the more
granular and darker central or medullary portion of the body (XXIII. 29/)),
and overlooked the presence of the real nucleus. However, Stein, Carter,
Cienkowsky, and others have determined the existence of this organ in the
genera Actinophrys and Podophrya. Unfortunately, some difference prevails in
the descriptions of this organ by the several observers, which it is most desirable
to have removed. Carter {A. N. H. 1856, xA-iu. p. 221) represents it to be a
cloudy body, " dLscoid in shape, of a faint yeUow colour, and fixed to one side
of a transparent capsule, which, being generaUy more or less larger than the
nucleus itself, causes tlic latter to appear as if surrounded by a narrow pel-
lucid ling." Stein describes it in Actinophrys Sol as finely granular, band-
shaped, and curved, or roniform, or rounded oblong (XXIII. 1 h). Cicn-

OF THE PROTOZOA. ACTINOPIIllYINA.

253

kowsky says that the nucleus of Podojphrya is " transverse and frequently
ciu-ved," and thereby implies that it is an elongated body. The nucleus of
Actinophrgs ocidata (says Stein, p. 159) may be brought into view either by
crushing the animalcide, or, much more satisfactorily, by adding dilute acetic
acid (XXIII. 24 b, 25 </). On viewing it from above, it appears like a round
hyaline ceU, containing a granular nuclear mass in its centre, and surrounded
by a rather condensed layer of the meduUaiy matter. On its entire detachment,
by means of the acid, it is seen to possess a distinct wall, having a double out-
line ; its nucleolus, on the contraiy, seems imdefined and irregular in shape,
composed of a mere heap of fine granules. The relative size of the nucleus
to the whole animal is very considerable. Thus, whilst the majority of spe-
cimens had a diameter of 1-38 to 1-35"', the micleus measured 1-125"', and
its nucleolus 1-250"'. Prom his account of Act. Eichomii, Stein would appear
to have seen a similar nucleus in that species ; for he states that the round
nucleus appeared like a nucleus-holding cell, having a double contour and
clearly-defined wall, and containing a large, finely-granular nucleolus.

ENCTsinsTG Aim Repeoductive Peocesses of AcirNOPHEYXN'A : — Encysting —
PissioN — Gemmation — Embetos — Conjugation. — Stein represents his Acii-
nophrys Sol and Fodophrya Jtxa as having a double integument (XXIII. 1, 3),
through which the tentacles penetrate, — whilst, as we have seen, other ob-
servers insist upon the naked state of the muco-gelatinous body of those as
well as of the other species of Actinopliryina. The questions therefore arise,
whether the being so named and described by Stein is identical with that in-
tended by other natui-ahsts, and, if so, whether it is not, in the so-called
encysted condition, at least in its earlier stage. Eor Stein subsequently
describes and figures truly encysted examples, in which the cyst appeal's like
a plicated loose sac around the contracted body, and the tentacles in part or
wholly gone (XVIII. 3). Cienkowslri affirms (op. cit. p. 101) that the being
described as ActinopJirys by Ehrenberg is really a non-pedunculate Acineta ;
and he further remarks that, although numerous points of relation exist
between certain J.cme<a-forms and Fodophrya Jiwa, he is unable to determine
whether they should be regarded as identical, or as the extreme links in the
morphological cycle of one and the same species. The same critical obsei-ver
details the process of encysting of Fodophrya, — a process, by the way, which
he has not met with in Acineta-form. organisms having a general resemblance
with it. To quote his account (op. cit. p. 99), " If Fodophrrjoi are allowed
to remain several days upon the object-glass, and care is taken not to let the
water diy up, every stage towards the quiescent condition — that is to say
towards the ' encysting ' — may be followed (XXIII. 34, 36, 37). '

" In Fodophrya this process takes place in the foUo-\^ang manner : On the

surface of the body a gelatinous mucous layer appears to be secreted, through
which the tentacles pass. The tentacles disappear in the neighbourhood'of
the peduncle ; and the gelatinous layer in this situation hardens into a loose
transversely-plicated membrane, whilst at the upper end it is still soft, and
the tentacles clearly visible. Ultimately these also are retracted, and the
entire body of the Fodophrya is enveloped in a wide loose membrane • the
plications are caused by parallel annular constrictions, placed at cquai di-
stances apart, and separatcd'by circular, angular, or rounded ridges ; these pli-
cations are in a plane perpendicular to the peduncle. At the summit of the
Fodophrya, and often also at the base, the membrane presents deep deures
sions ; the inclosed body of the Fodophrya acquires on its suifacc a sharalv-
defincd smooth membrane, whilst the contents of the body become somewlvit
• "P'''^''^' f?^''''^^ a round clear space. The Fodophrya-cyst thus formed is
supported by a peduncle, which is widened at the base. lu many instences

9

254 GENERAL HISTORY OF THE INFUSORIA.

in which the membrane was not plicated, but loosely enclosed the Podophrya
like a sac, I noticed that the peduncle of the cyst Avas continued uninterrupt-
edly into the membrane, of which consequently it must be regarded as a pro-
trusion, and that it had no connexion whatever with the original slender pe-
duncle of the Podophrya itself. In fact, I noticed cysts in which this original
slender peduncle was appended to the saccular envelope. I am unable, there-
fore, to adopt Stein's view that the PodopTiryce are enclosed in a membrane,
of which the slender peduncle is simply a tubular protrusion. This is true
only with respect to the short peduncle of the encysted Podophrym.

" What afterwards becomes of the cysts I have been unable, in spite of ob-
seiTations continued for months, to determine."

Multiplication by Spontaneous Division seems now to be sufl&eiently de-
monstrated. Ehrenberg and other earlier writers, indeed, mentioned the
occurrence of self-fission ; but their accounts were too uncertain and inde-
finite, and strong doubts prevailed whether they had actually witnessed that
process, or the act of conjugation, to be presently noticed. Mr. Biightwell
appears {Fauna Infusoria of Nor folic) to have confounded the two processes ;
for he says — " They multiply by division, so that two and sometimes three
individuals are seen adhering together by their outer edge — ^the middle one,
the parent, being the largest," — an explanation inconsistent with the process
of fission as generally understood. Claparede states distinctly that he has
seen the act of fission ; Weston describes it in Actinophi-ys, and Cienkowsky
in Podophrya. " With regard to the reproduction of Actinoplirys Sol," writes
Mr. Watson (op. cit. p. 119), " I can positively affirm that self-division is
one mode ; for I may say I have witnessed it a hundi-ed times and shown it
to others .... First was noticed a deep depression above and below, not far
from the centre of the body ; this, as it increased, threw the tentacles across
each other, in a manner similar to that described by KoUiker, when in the
act of inclosing an object of prey. This crossing, however, in the act of self-
division would appear to be only the necessary consequence of the depressions
alluded to, and the position into which the outer membrane (in which the
tentacles are inserted) is drawn. As division proceeded (XXIII. 31), the
two animalcules steadily, but rather quickly, increased the distance between
them, until the connecting medium was apparently a long membi-anous neck,
which, to my unpractised eye, appeared composed first of four, then of three,
then two irregular lines of cells (possessing no nuclei), which ultimately di-
minished into a single cord composed of three simple cells elongated like the
links of a chain, this becoming gradually more attenuated, imtH the exact
moment of its division could not be seen. AU this latter portion of the pro-
cess was rather rapidly performed, — that is, from the fii'st formation of the rows
of cells to the time of what I supposed to be the final sepai-ation, occupied
only about a quarter of an houi* .... Dming the whole of the process, the valve
{i. e. the expanding and contracting superficial vacuole) of each segment, situ-
ated at nearly opposite extremes, was in constant action, and each creature
was busily employed seizing its food." On following one segment after its
separation, " a floating faint line, the broken thread " (of connexion), extended
from it ; and two of the cells, formerly contained within this bond, were attached
to its side, but were in a few minutes dravm into the body of the Actimphrys,
which there assumed a perfectly normal character. In Podophrya the process
of fission is similar (XXIII. 34) ; at first an annular constriction displays it-
self, and so rapidly deepens, that in an about half-an-hour complete trans-
verse fission is effected. The histoiy of tlie segments is tlius portrayed by
Cienkowsky {pp. cit. p. 98), about ten minutes after the commencement of the
act of division: — " The upper segment had assumed an elongated form, was more

OF THE TROTOZOA. ACTINOPILRYINA.

256

cylindrical, a little indented in the middle, and rounded at each end ; and at
the extremities, slight oscillations to the right and left could be perceived. A
transverse, and frequently curved, nucleus was visible in the fluid contents ;
and a lateral contractile space could be clearly distinguished in the upper
parts. The vibrations iacreased in frequency and force rmtil the segment
became wholly detached and escaped. During the process of division both
segments were furnished with tentacles ; but when the oscillations of the
cylindrical portion commenced, very fine and short cilia might be seen, though
with difSculty, vibrating on the free end, — the tentacles at the same time being
retracted, and remaining visible only on the posterior segment. I now followed
uninterruptedly the movements of the liberated segments. They moved for the
most part in curved hues, in the course of which the motile segment appeared
to seek the illuminated side of the drop of water. Cilia could not be perceived
over the whole surface. The contractile space during the movements was al-
ways in front. The motions were rapid, but still such as to allow of theii- being-
followed with a magnifying power of 370 diam. After waiting patiently for
twenty minutes, I saw the motion cease ; and at the same time short tentacles
made their appearance, which were protruded more and more ; and in a few
minutes afterwards the segment regained the spherical form : thus, after
moving about freely for a time, it was again transformed into a PodopTirya.

" This process of division was witnessed by other observers. It takes place
more especially when sufiicient nutriment is supplied by numerous Stylony-
cMce to the Podophryce. The Podophrya does not always divide into two
equal halves ; the segments are more frequently unequal. After repeated
division, the specimens always become more transparent." This temporaiy
production of vibratile cilia from the surface of one of the Actinophryina, in
connexion with the process of fission, is a phenomenon so opposed to received
notions, that it will necessarily be admitted with great reserve until confirmed
by repeated observation.

The process of Gemmation is recorded by Lachmann to occur in Dendrosoma
radians, a being of which we know too httle to pronounce with certainty if it

be one of the Actinophryina or of the Acinetina, He says (pp. cit, p. 231)

" In Dendrosoma radians, Ehr., a branch of the nucleus grows into the bud
whilst it stiU remains imited to the parent animal."

_ Eeproduction by Embryos or Germs has been presumed by several autho-
nties. Stem, in pursuing the history of the organisms he identified with
Actmophrys Sol and Podophrya fixa, satisfied himself of the successive
development m theu- interior of a ciliated germ, which he compared to the
gemma ^^^/"'l^^' j^to ^hich, indeed, he supposed it subsequently to
fully unfold Itself (XXin. 2, 4, 5). However, as before noted, Cienliowskv
rejects the beings observed by Stein from Actinophryina, and treats them
as Acinetina; yet he, at the same time, confirms the production of ciUated
motile embryos within ^cmete, but declares them reconverted into similar
Podophryoi to those that give biiih to them. Apart from the researches of
Stem, which have mvoked so much attention to the development of Protozoa
generally, and particularly to that of Actinophryina and Acinetina, the idea
that the members of the former family probably reproduce themselves bv
gems has been suggested by the occurrence of very minute individuals
either alone or m clusters. Thus KoUiker remarks {op. cit. p. 34) that the
smaUest mdividuals oi Actxnophrys Sol measured only O-Ol'" to O-O?" n^^
presented very inconspicuous and few granules, and that the granular ^d
yesicular^ coipuscles withm the nuclear portion of the body nfay be Lm«
just begmnmg to be evo ved. Mr. Weston is also led to^believe if the
rntemal generation of minute germs ; but the observation he Jecords as

256

GENEEAL HISTORY OF THE INFU80EIA.

possibly an instance of such a process, entirely fails, in our opinion, to sus-
tain the supposition. The occurrence alluded to was that of a thin, pellicular,
irregularly-shaped sac — sometimes of two or three such, — which elevated itself
above the surface of the Actinophrijs, and presently burst, emitting some
fluid and fine granular matter, and then contracted. " Does this emitted
fluid," he asks, " contain the germ of future generations?" We think not ;
for, to our mind, the phenomenon witnessed was nothing more than the
bursting of superficial vacuola, probably acting as excrementory media ; and
if this view be not correct, Mr. Weston's is improbable, inasmuch as such a
discharge of germs from superficial sacs is without parallel in the history of
Protozoa.

CoKJUGATioN. — The remarkable act of conjugation, also known as Zygosis,
has attracted very much attention in the class of animalcules imder consi-
deration, among which it is of very frequent occurrence. Much discussion
has taken place concerning the purpose of this process. Most of its early
observers considered it a reproductive act, a sort of copulation between two
individuals ; but the tendency of opinion at the present day is to deny it this
nature, and to treat it as little more than an accidental phenomenon, without
apparent object or aim. Nevertheless its occurrence is so frequent, and the
process of so complete a character, that it is hard to believe it to be in vain
and to no purpose in the economy of the Actimpliryina. A difference of
opinion likewise prevails as to the nature of the process, one set of authors
maintaining that there is an actual fusion and intermingling of substance
between the conjugating animals, whilst another party asserts that there is
no fusion, but merely a temporary adhesion or accretion between their bodies.
The determination of this question is very necessary before we can speculate
fairly respecting the purpose of the act. KoUiker, who was among the first
to carefully explore this phenomenon, described it as a process of complete
fusion, and surmised it to be of a reproductive character. Stein speaks at
one place of conjugation (op. cit. p. 148) in Actinojphrys and Podophrya as
consisting in a fusion ( Yerschmelzung) of the animalcule. At another (p. 160)
he describes it as an organic union of two or more individuals into a group,
involving no fusion of their contents, but only a cohesion by their surfaces ;
and goes on to say (p. 161) that the coming together of two Actinoplirides is
due to external forces, and that the first thing observed is an entangling
together of their tentacles, which act precisely in the same manner as when
a foreign body is seized upon, and by their conti-action biing the bodies into
apposition. At the same time they fuse together and form a sort of commis-
sure, which is sometimes areolated, owing to interruptions to its continuity
by the incomplete confluence of the tentacles. In the case of Act. oculata,
several — as many as seven — individuals were seen by Stein comiected toge-
ther, in a line, by this intermediate commissiu-al matter, which he calls a
common mantle, — but all of them preserving thcii' indinduality, just as in the
instance of other species. This mode of connexion, by means of an interposed
matter derived from the tentaeula of the conjoined sm-faccs, explains what Stein
means by conjugation being a fusion of the animalcules concerned — not a
fusion or commiagling of their substance in general, as some have thouglit it.
Cohn, in his account of the conjugation of Acfinophrys (Zeitschr. Band iii.
p. 66), noticed the connecting band or commissure to sometimes contam,
besides granules, particles of food, and vacuola, a vesicular body wliich he
presumed to be nuclear, or a germ, developed as a consequence of the zygosis
in operation. Stein cncoimtered once or oftcncr a similar body, but concluded
that it was accidental, probably of vegetable origin, and not in any degree
embryonic; and (p. 164) he expresses himself satisfied that this act of con-

OP THE PROTOZOA. — ACTINOPnRYINA.

257

jugation is not associated with the reproductive faculty. In fact, he has
never met with the development of an embryo in conjugated individuals of
his (Acinetiform) Actinophrys and Podoplirya. Claparede questions {op.
eit. p. 286) whether the compound forms noted by Stein and Perty were, as
they supposed, all derived from conjugation ; and he proceeds to say that, if
it be proved that more than two individuals may thus be fused together, the
connexion of conjugation with reproduction will become exceedingly doubtful,
and that the term had better be dropped, and either Stein's phrase " process
of fusion," or Ehi-enberg's word " zygosis," adopted in its room. Whatever
value attaches to Claparede's deduction from the circumstance of more than
two being fused together, there can be no doubt that this may, and indeed does
frequently, happen. Lieberkiihn, one of the most recent investigators of this
group of beings (Zeitschr. 1856, 308), recognizes the occurrence, and observes
that the number united may be estimated by that of the contractile vesicles.
The process, he further asserts, is not one of genuine conjugation, but merely
a temporary cohesion ; for, after watching a group for six houi-s, he saw the
separation of the several component individuals, preceded by a narrowing of
the connecting bands or commissures. Such is an outline of the opinions and
statements of some leading naturalists respecting the nature and design of
this so-called act of conjugation. The balance of authority and evidence is
against the supposition of its reproductive purpose ; but when this view is
rejected, we have no other to replace it, and are sensible of the want of
STifficient data from direct observation before a hopeful attempt can be made.
Ehrenberg, it should not be omitted to state (Monatsb. Berl. AJcad. April
1854), started the notion that conjugation is intended as a means of invigo-
rating the species : " a curious idea," says Claparede (op. cit. p. 286), " and
not very reconcileable with the ordinary laws of nature."

KoUiker {op. cit. p. 100) canvassed the question, if Actinoplu-yina, along
with Ehizopoda, are to be considered cells, and, after an elaborate examina-
tion of the point, concluded that they must be regarded as peculiarly modified
simple cells. Claparede, after weighing KoUiker's arguments and reviewing
the structui'al peculiarities of these animalcules, comes to the opposite conclu-
sion, viz. that, " as regards Actinophrys Sol in particular, we must either
drop the class of unicellular animals altogether, or refer this animal to some
other place." We do not deem it at all necessary here to enter upon tliis con-
troversy ; it has already engaged our attention va. other places, and has of late
lost much of its interest by the extended modifications introduced latterly in
that particular hypothesis of ceU-natm-e, which, at the date of KoUiker's
paper in 1849, exerted so powerful an influence over the histological specu-
lations of all the writers of that period.

Localities. — Actinophryina are inhabitants both of fresh and salt water.
They occur often as parasites upon the larger Protozoa, such as Stylonychia,
and on various small animals of other classes, and seem to draw nomishment
from them. They are also common among the filaments of Conferva and the
stallis of Lemna, where other animalcules congregate. Another locality is
amid the vegetable debris and minute animals which often float together as
a dust-like film, on the surface of ponds. '

Affinities of Actinophryina. —All recent writers refer this group of beings
to the Rhizopoda, except Siebold, who curiously enough retains Actinophn/s
in the family Enchelia, along with Leiwophrys and Prorodon, two gen^a of
Ciliata of quite a different type of organization. Although the preceding
sketch of the history of Actinophryina will afford ample evidence of manv
homologies with the Rhizopoda, yet it will equally display not a few diff^er
ential charactera, siiflicient, we believe, to separate them at least as a subclass

258

GENEHAL HISTORY OF THE IKFUSOEIA,

The most striking points of divergence are the more definite and constant
figau-e of Actinopliryina, their peculiarly fonned tentacula in lieu of ordinary-
variable processes, and, of minor moment, their greater immobility, and the
operation of the tentacles in the introduction of food. Acineta was placed by
Ehrenberg with Actinophrys in a family or order Acinetina ; and most writers
treat them as if the relation between these two families were actually so near.
A closer attention will, however, prove that something more than a generic
difference subsists, and that Acineta had better stand as the representative of
another gToup, well named Acinetina, although more limited in its significa-
tion than that so termed by Ehrenberg. The most tangible differences
between Actinojpliryina and Acinetina are, that no food enters the substance
of the body in the latter group, and that the body is covered with an integu-
ment. The history of this division, as far as at present known, reveals yet
other distinctions ; for self- division has never been observed, whilst the pro-
duction of motile cUiated embryos from the interior has been seen over and
over again, without, as far as is known, an antecedent act of conjugation. It
must likewise not be forgotten, that it is the Acinetina which, according to
Stein's hypothesis, constitute an intermediate phase of existence in the de-
velopment of many Vorticellina. Indeed, could this naturalist's supposition
be proved, the existence of Acinetina as a class of independent beiugs would
at once be saciificed. Another affinity is discoverable with the Polycystina,
both in the nature of the soft, muco-gelatinous mass, iu the long, tentacular
filaments, and in the currents of granules detected iu the processes. This
relation is best seen with some Acanthometra (vide Midler's paper, Monats-
bericht, Berlin, April 1855). The Actinophryina are related to the Cilia ta also
by their sarcode, by the structure and action of the contractile vesicle, by the
formation of alimentary vacuoles, and by the nature and composition of their
granules. But, over and above these general resemblances, a more special
affinity is manifested if Cienkowsky's statement, that the fission produced is
clothed with vibratile cilia, be correct. This degree of affinity must be ad-
mitted in the case of the Acinetina which appear", as a rule, to generate
ciliated embryos.

Since the above history was written, Dr. Strethill "Wright, of Edinburgh,
has most kindly furnished us with notes on several Infusoria, among others
of two new forms of Actinophryina, presenting great peculiarities in struc-
tui-e. The account of these novel genera will be foimd in the second part of
this work, in the Systematic History of the Actinophryina.

SUBFAMILY ACINETINA.
(Plates XXIII. 1-23; XXYI. 3, 4; XXX. 3, 4, 7, 8, 21-26.)

The reasons for separating Acinetina from Actinophryina, with which they
have generally been united, have been stated in the last chapter, where
likewise the difierential characters of the two groups, and the supposed part
they play in the cycle of development of Vorticellina, have been examined.
There remains therefore, to fill up the history of the Admtiim, nothing more
than some further remarks on the various forms they assume, and on certain
peculiarities in their structure.

The form of Acinetm is subject to great variety. Pyriform and ovoid shapes
are the most prevalent; but some are almost spherical, and others, again,
nearly triangiilar (XXIII. 6, 7, 8, 15, 17, 22, 23). A lobulated anterior end
is common ; and then the tentacles are usually restricted to the lobules (6, 17,
18). Those lobed forms have no such firm integument or capstile at all as

OF THE PROTOZOA. ACINETINA.

259

that seen in others ; or the anterior lobed part is undefended by such a cover-
ing, except of a very delicate and yielding stractiu-e. Cienkowsky speaks of
the Acineta he examined as naked without limitary membrane (XXIII. 40).
Very frequently, on the other hand, the Acineta is entirely enclosed within
a stoxit capsule. This capsule is readily discerned when, as frequently
happens, the internal animal mass of the Acineta does not fill it ; or it may be
brought into view by the apphcation of diluted acetic acid or alcohol, either
of which causes the shrinking of the contained body. In general the capsyde
appeai-s to be a very thin, colourless, hyaline membrane ; but after the action
of acetic acid, Steia represents it to be, in the supposed Acineta of Opercularia
Lichtemteinii, of considerable thickness (XXIII. 22, 23). This thickemng
is doubtless due to the action of the acid in causing the membrane to sweU
out. With the exception of the so-called Actimplirys Sol of Stein, and the
Dendrocometes, the Acinetina are attached by a stalk of vaiying length,
more commonly very short, to the body on wMch they live (XXlII. 17, 18,
22 ; XXVI. 3, 4). This stalk or pedicle is a tubular prolongation backwards
of the capsule itself, Hke which, it is hyaline and transparent.

It is not articulated with the body of the Acineta, but expands more or
less abruptly into the capsule, and has a proportionately greater or less
infundibuliform figure. Occasionally the stem at the upper part has trans-
verse rugae, and in a few instances exhibits a sort of longitudinal striae, par-
ticularly near its junction with the body (XXIII. 3, 4). Stein describes the
stem of the supposed Acineta of Epistylis, to be solid like that of an Epistylis
itself. Preqiiently the capsule is thi'own into transverse folds, at times, of
considerable depth. There is no aperture in it ; but it is penetrated by the
tentacles which rise from the contained organic being. The capside, if in
some specimens of considerable firmness, would seem to be in others, even
when thick, veiy yielding, — so much so as to allow great variety in figure by
the contractions of the contained body, as instanced by Stein in the Acineta
attributed to Opercularia Lichtensteinii. The tentacles of Acinetina have not
the imiformity of structure seen in those of Actinopliryina. In some Acinetce
they closely resemble those of Actinoplirys, are long, gently tapering, and
capitate ; in others they form parallel tubular processes, dilated a little, or
not at all, at the extremity, and either straight or slightly curved or undu-
lated ; in others, again, they rather resemble bristles, appear stiff, and taper
to a sharp point. In the remarkable Acineta called Dendrocometes, the
tentacular character is entirely lost, and a few most bizarre branched tubular
processes spring from one to six points of the surface (XXX. 22, 23). Per-
haps these processes are homologous with tentacles ; yet, imlike them, they
seem to be formed from the capsule of the animal, into which the granular
contents of the interior penetrate, as into hollow tubules prolonged fi-om the
surface of the organism.

In certain Acinetina that approach Actinophrys in external chai'acters, the
tentacles are equally diffused over the body. In the large pjTiiform Acineta,
assigned by Stein to Opercidana articulata, the short slender tubular pro-
cesses appear chiefly marginal (XXX. 3, 4). The digitate Acineta is covered
by long tapering and thick processes on its dorsal convex surface (XXIII.
21); and the Diademiform Acineta has its long sctiform tentacles in twos
and threes at considerable intei-vals, chiefly on the margin (XXIII. 15, 16)
The Aclinophryean Acineta of Epistylis pUcatilis bears a bundle of long
finely capitate ten taenia on each of its four lobes (XVIII. 2); that of
Voriicella nebulifera has two such bundles, — whilst the triangular Acineta
with its tongue-like process (XXIII. 17, 18, 19), carries a large expandinc^
pencil of shorter obtuse tentacles upon each angle at its base. "

s 2

260

GENERAL HISTOEY OP THE INFUSORIA.

The tentaciila arc moveable and retractile, the divergent bundles may be
collected into parallel groups, and drawn inwards, with the protruding sup-
porting lobes, to a greater or less extent. Stein affirms that, in the first stage
of development, Acinetce have no tentacula.

The body of an Acineta, within the capsule or external integument, con-
sists of soft colourless sarcode, rich in granules, fat-corpuscles, and minute
globules. It is enveloped by an elastic yielding membrane, which becomes
most distinct when the body shrivels vsdthin the capacious cavity of the
capsule (XXIII. 3, 6, 8). The body appears in some Acinetce capable of
extending itself above the capsule, which must therefore be fissured in front,
in the form of a tongue-like process (XXIII. 17, 18, 19). A finely granular
and opaque nucleus is always distinguishable in the interior, usually near the
centre. Its shape is very varied, and may be oval, ovoid, elavate, reniform,
band-like, vermiform, or horse-shoe shaped (XXIII. 1, 6, 17, 22). In a
few examples, e. g. of the supposed Acineta of Opercularia, it is much and
irregularly branched (XXX. 3, 4). The addition of dilute acetic acid is a
ready and effectual means of bringing the nucleus to light, and of demon-
strating its enclosing sac ; and as it is more solid and compact than the
contents around it, it may now and then be separated by crushing the Acineta.
The nucleus is enveloped by its peculiar membrane ; a fact which becomes
evident in several cases by the apparent double line surrounding its gra-
nular mass (XXIII. 6-22). In a few instances, moreover, Stein has de-
scribed a contractile space within the nucleus, e. g. in that of Opercularia
berberina.

Not unfrequently the nucleus looks as if double, or as sending off" a process
from itself; a critical examination of such specimens has convinced Stein that
the off'shoot is the commencing development of the germ or embryo of the
Acineta (XXIII. 7, 8, 19). This he has proved by watching the nucleus
through aU its intermediate stages, from a simple ovoid or elongated figure
until the embiyo has groAvn and separated itself from it prior to its escape
from the Acineta. The nuclear appendix, when separated, is found to have
an enclosing membrane, which iiltimately surrounds the embryo like a sac,
and admits of a certain degree of movement within it (XXIII. 4, 5).

Another distinct organ of Acinetina is the contractile vesicle. Usually one
only is present ; but in some instances two, and more lurely three or more,
make their appearance (XXIII. 1, 5, 21). Near the external margin a series
of clear vesicular or vacuolar spaces presents itself, as in the Diaderaiform
Acineta (XXIII. 15, 16) ; such, however, present no rhythmical contractions,
and cannot be regarded as trae contractile sacs. The embryos developed
from Acinetai are likewise furnished with one, and occasionally with two, of
those organs (XXIII. 2, 4, 5, 15, 27). Excepting the embryos or germs, no
other special structures are seen amid the granular contents of Acinetina.
Alimentary vacuoles and particles of food or other matters derived from witli-
out never make their appearance ; for the body, even if not entirely enclosed
within the shut sac or capsule, is covered with an integument, and has no
sign of a mouth for the admission of food. Yet Acinetce generally have the
power of nourishing themselves, by the medium of their tentacula, which
appear to act as suckers, drawing in by endosmosis the n\itrient juices fi'om
the animalcules which get entangled by them.

If Stein's details be correct, some Acinetifonn beings would appear to have
no power of self-nutrition ; for their substance is described as gradually used
up in the formation of germs, and this decrease to be followed by a shrinking
or collapse of the capsule, but at a comparatively slower rate. This phe-
nomenon is illustrated by Stein in the Acineta ascribed to Vaginicoln

OF THE PROTOZOA. ACINETINA.

261

crystalKna, and in the so-called Acineta with the tongue-like process
(XXIII. 17, 20). ^

If this account be admitted, that certain Acinetm display no power of self-
nutrition, and seem destined only to subsei-ve, as mere media, the puri}oses of
reproduction, an independent nature could scarcely be attributed to such
beings, and their history would be entirely comprehended in that of the
beings in whose cycle of development they might enter as one link. Lach-
mann {A. N. H. 1857, xix. p. 222) has the following account of the mode in
which Adnetina nouiish themselves :— " Each ray " (tentacle) " is a sucking
proboscis, and we soon see that a current of chyme-particles runs from the
alimentary cavity of the captured Infusorium into the body of the Acineta,
through the axis of the rays, which, after seizing the prey, have become
shortened and tliickened. In the body of the Acineta the chyme-particles
still run at first ui a slender row, but aftei-wards they collect m a drop, which
although drops are also formed in the chyme of the Acineta by other suckers,
soon becomes amalgamated with these. When a considerable quantity of the
chyme of the captured animal has passed over iato the body of the Acineta,
a remarkable change gradually takes place in its appearance : if it was previously
pale, nearly transparent, and only very finely granulated, larger dark globules,
resembling fat-drops, now make their appearance here and there ; and these
soon increase so that the body (which at the same time, of course, increases
in thickness) acquires a coarsely-granular aspect, and becomes opaque. The
globules or drops which make their appearance can only be formed in the
body of the Acineta, as they are far larger than the chyme-particles which
are seen fiowing through the sucker. The animal whose contents are thus
sucked out, gradually collapses and dies ; many become liquefied when only
a little of the chyme is extracted from them, others still live for a long time ;
in large animals, such as Stylonychia Mytilus, Paramecium Aurelia, &c., the
sucking often continues for several hours."

Ohigin and Development op Acinetina. — In our history of the development
of Vorticellina, Stein's hypothesis of the transformation of those highly-de-
veloped Ciliata into Acinetiform beings as a stage of existence necessary to
their development by embryos, and of the reconversion of the embryos into
Cihata of the primitive type, is sufficiently enlarged upon. In the same
chapter, moreover, Cienkowsky's contradictoiy statement and observation are
detailed, viz. that, though Acinetce develope cihated embryos, yet these
embryos give origin to beiags like those they issue fi-om, and are not trans-
formed into Vorticellina. According to this opinion, the Acinetina take a
position as independent beings in the animal series. Stein determined, to
his own satisfaction, an Acinetiform phase in the following Vorticellina and
Ophrydina : —

Cothurnia maritima. Spirochona gemmipara.

Epistylis branchiophila. Vaginicola crystallina.

Opercularia articidata. Vorticella microstoma.

Opercularia berberina. Vorticella nebulifera.

Operculana Lichtensteinii. Zoothamnium affine.

Ophrydium versatile. Carchesium pygmceum ?

The description of the Acinetiform beings assigned to the species enume-
rated is given in the Systematic History of the Acinetina, wliich ^x'ill likcAvise
afford a more complete idea of the stnicture and forms of this pec\iliar class
of beings than the above general history itself.

262

GENEHAL HISTOEY OV THE imFUSOHIA.

SUPPLEMENTARY FAMILIES OF PIIOTOZOA.

A. — GREGAUiNrDA. ' Theib Geneeal Chabactees, Stbuctuee, and Affini-
ties.— The Gh-egarinida constitute one of the three groups into which several
eminent naturahsts subdivide the Protozoa ; they therefore claim from us a
brief description.

They are of the most simple structure ; indeed, some writers place them
below the Rhizopods in the animal series, because, unlike these, their simple
type undergoes no further elaboration or developmental complication. They
are parasites, Hving in the visceral cavities of other animals, and in their
simple structure are comparable to a cell, or to the ovum of higher animals.
Thus they consist of a homogeneous albuminous-hke matter, with numerous
granules of coarser and finer character and fat-like globules, enclosed within
a membrane of more or less perfect sti-ucture, which in all essential points
represents a cell- wall ; besides, they have always one distinct centi'al vesicular
body or space containing one or more granules, and evidently of the nature
of a nucleus. Of these parts, the general mass may be taken to resemble the
yelk-matter, and the nucleus the germinal vesicle of an ovum.

The enclosing membrane is very yielding, and admits of great and constantly
fluctuating alterations of figure by the varying contractions and extensions
of the internal contractile mass ; but there is no such thing as the formation
of pseudopodes, as happens among Rhizopoda. It is entire, Avithout orifice
either in the shape of a mouth or anus ; consequently no foreign particles are
ever seen in the interior. Moreover, the Gregarinida contain no contractile
vesicle, and have never been found to undergo either fission or gemmation.
Their vital endowments are so slight, that their animality is at first sight
doubtful ; but, unlike vegetable organisms, their envelope contains no cellulose.

The above brief account comprehends all that can be stated generally of the
organization of these simple creatures, which, if above the Amoehaa in the
possession of a more or less definite membrane, yet sink beneath them in not
possessing a contractile vesicle.

Notwithstanding their simplicity of stnicture, they yet are timly animal
organisms, enjoying an independent existence, manifesting the phenomena of
motion, growth, nutrition, and reproduction, in the last of wliich they exhibit
a peculiar cycle of changes.

Moreover, there are various notable differences between the various Grega-
rinida known, with respect to size, figure, to the activity of their functions,
and to some minuter points of structure. Hence their division into genera
and species.

In size they vary from four or five lines (as in the genus Didymophrys) to
a few thousandths of an inch. Of their figure, some are simply rounded or
oval sacs, as in Monocystis ; others constricted ai'oundthe middle, e. g. Grega-
rinida. Again, the majority have a smooth, naked membrane, wliilst otliers
are armed with a ring of uncini at one extremity, Hkc many Uclm'mthida.

"When two nuclei occui- in a single animal, it probably betokens an act of
reproduction. The encysting process is exhibited among the Gregarinida, in
connexion, however, only witli their reproductive processes, and has this pe-
culiarity, that it does not occur to a single indiridual, but to two together,
which become enclosed within the common cyst or capsule. In their progress
to this union the two Grcgarinm are seen fii'st to appi'oach, and then by mu-
tual pressure to flatten, the opposed sm-fiiccs, so that the binatc being acquires
a globular form. The substance to form the cyst is in the meantime thrown
out, of a soft gelatinous consistence, but gradually becomes condensed and
contracted into a membranous-looking capsule.

OF THE PKOTOZOA. — GIUEGARUTIDA,

263

Stein stated that, on the completion of the act of apposition, an actual
fusion of the contents of the two animals transpired, the opposed walls being
previously removed by absorption. Other observers state, however, that there
is no such removal of the external membranes, and that the reproductive
processes in the interior of each being proceed without any real commingling
of their contents, which is a subsequent and probably not a necessary
event.

This act, which, from its general resemblance to the zygosis of plants, is
spoken of as one of conjugation, appears immediately concerned in the de-
velopment of a multitude of germs within each Gregarina, by the general
breaking up of the granular contents. Still, if Lieberkiihn's account be ad-
mitted, this process of conjugation is not a necessary prelude to the develop-
ment of the internal germs ; for, according to it, this result may accrue in
individuals which have never conjugated.

The germs assume a rod- or spindle-shaped figure, which, from its re-
semblance to the prevailing form of the Naviculce, has suggested for them the
name of " NavicetlcB " or " pseudo-Navicellce." They consist of an external
comparatively firm waU, enclosing a finely-granular gelatinous substance.

When the " Navicellm " are sufl&cieutly mature, the cyst of the Gregarince
bursts and sets them at large. Their future history, according to Lieberkiihn's
researches, is, that the case of each pseudo-Navicella ruptures and gives exit
to the soft contained matter, which at first much resembles a minute Amosba,
but gradually assumes, by progressive growth and the formation of a peUicle
around it, the characters of a Gi'egarina.

Between this mode of development of Qregarinida and that of the Ciliated
Protozoa, Leuckart draws this distinction, that in the former it consists in
the production of granular germs, in the latter of living embryos. But it may
be questioned whether there is a positive difference in kind between these
two results of the reproductive process, and whether, on the contrary, the
Navicellce of the Gi'egarinida may not be considered as merely encysted em-
bryos, homologous with those of Colpoda Cumllus among the Ciliata.

The act of conjugation in the Qregarinida is not precisely like that occur-
ring among the lower Algae, the leading difference being that in the former
there is no commixture of the two approximated beings. In all essentials,
indeed, conjugation in this family resembles that believed to happen in the
Actinophryina.

There has been much dispute whether the Qregarinida are to be held in-
dependent animals, or merely embryonic phases of others ; the balance of
authority is in favour of the former view. Kollilter and Leydio- advocated
the opinion that they are metamorphie stages of AnguiUuloi or Fdarice, or a
link in the series of development of the Uelmintludm. The arguments adduced
by Leydig are thus briefly stated {J. M. S. i. p. 208, and Miiller's Archiv,
1851) : — "In the intestine of a largo species of Terebella he was enabled to
observe the most distinct transition between Filaria-like Nematoid worms and
Chegarinoi. The forms of the latter, which he observed not once only, but
many times, were — 1. A Qregarina of from 0-02'" to 0'04"' long, wliich had
the form of an elongated sac, rounded at one extremity, and sharp at the
other. The contents were those usual in the Gregarince — a consistent fluid
with a corpuscular substance, which did not occupy the pointed end, and im-
bedded in this a clear vesicle with a nucleus. 2. A Gregariniform'crcatiu-o
of a spindle-shaped figure, closely resembling Gregarina Terebella;, Kold!
3. A Gregarina, generally resembling the preceding, differing only in two
particulars: the internal substance is arranged in longitucUnal streaks-
and the body, instead of being straight, is" more or less ciu-vcd at each end'

264

GENEKAL HISTOKY OF TITE INFUSORIA.

4. The same form, but with the body more elongated, vemiform, and for the
first time exhibiting motion. 5. A very pretty Nematoid worm, about O'lO'"
long, blunt at one end, sharp at the other; the contents in longitudinal
streaks, as in the two preceding forms, but with the spaces between them
wider. Its motions are very active."

This view of a metamorphosis being admitted, the question arises, do the
Gfregarince become changed into Filance ? or is it that the Filaria-like woi-ms
are transformed into Gregarince ? Although at first inclined to consider the
former as the true state of the case, Leydig is now disposed to follow Heule
and Bruch, and adopt the latter view ; otherwise it would seem impossible
to account for the formation of the pseudo-Navicellce and " Psorosjjermia "
within the " Gh-egarince."

KdEiker has the following remarks on this subject (J. M. S. i. p. 212) : —
" Although the change of a Filaria into a Gregarina ia not an impossible cir-
cumstance, before we admit such a thing it is first necessary to inquire whe-
ther the facts stated may not be otherwise explained. It is by no means
proved that the Anguillula-hke animal noticed by Henle, and termed by
Bruch Filaria, is really a Nematoid worm." Kolliker is more inclined to
regard it as an Infusorium alHed to Opalina, Proteus, &c. If this be the case,
there is nothing extraordinary in its transformation into a Gregarina, and
finally into a Navicella-r ece^taclo.

" For many reasons," says Stein {Zeitschr. iii. 1852), " the endeavour to
show the Gregarince to be larvae of higher animals, and especially to connect
them vdth encysted Nematoid worms, appears to be a vain attempt. Thus, I
am acquainted with Gregarince of such peculiar fonns that one requires a
very strong imagination to deduce them from Nematoidea, or to suppose they
can pass into these. The encysted Nematoidea are always found in the cavity
of the body of insects, never in their intestinal canal, where alone encysted
Gregarince are to be found." Again, the cysts of the Nematoidea of insects
are made up of nucleated cells, and are plainly a product of the vital activity of
the insects, not the exudation of the enclosed wonn, while the cysts of Gre-
garince are produced as an amorphous secretion from the animals themselves.
" If, therefore, encysted Nematoidea change into Gregarince, or vice versa, their
cyst must undergo a metamorphosis which, perhaps, no one will assume, and
of which no observer has seen anything."

Lieberkiihn's observations have gone far in showing that, under usual con-
ditions at least, the Gregai-inida are not converted into Filai-ice or any other
form of Vermes, but that their germs, after a short-lived Amcebiform period,
not amounting, however, to a true metamorpliic stage, assume the characters
of their parent. Thus the cycle of development of these beings appears com-
plete ; the saccular animal constructs, by a process of segmentation of its in-
ternal substance, a host of germs, which, after breaking loose fi-om theii-
parent and involving its destruction, emerge from their cases in a soft Amce-
biform condition, and soon acquii-e the matuj-e Gregaiiniform condition. The
Gregarinida exhibit a marked afiinity with other Entozoa, particularly \\\Xh.
the Trematoda and Opcdina;a ; and, as before remarked, they arc allied with
the Amoeba^a in the extreme simplicity of their stnicture. By the possession
of a limiting membrane (not indcpondont or separable, indeed), they stand
between the mucilaginous fluctuating Amcebcna and the Ciliated Protozoa.
Unlike the Anicebcea, they do not receive into their substance soUd particles,
— a circumstance explicable by their being covered by a somewhat resistant,
hardened lamina or tegument, which necessarily impedes that peculiar intus-
susception of solid matters witnessed in that family.

As to habitat, the Gregarinida are parasites in the intestines of various In-

OF THE PROTOZOA. PSOROSPERMIA.

26o

Vertebrate animals — woi-ms, mollusks, and insects, — but have not been found
in Vertebrata.

B.— PsoEosPERMiA (Plate XXII. 37-41).— This is a small group of para-
sitic animals, fii-st observed by John Miiller in 1841, closely related to the
G-regarinida, of which, indeed, they might be included as members. Unlike
the Ch-egannce, they live upon vertebrate animals, viz. upon many species of
fish, about their skin, gills, and internal organs, several together enclosed
within sacs.

Leydig has more recently applied himself to the study of these minute
parasites, and has given the results of his observations in MiiUer's Archiv for
1851, of which an abstract appeared in the Journ. of Mic. Science, i. p. 206,
which we shall here take the liberty of using, as sujficient for our pur-
pose : —

" The Psorospermia are microscopical coi-puscles of a peculiar kind, which
may be generally characterized, in the full-grown condition, as rounded
organisms, having a shai-ply- defined outline, with or without a tail-like ap-
pendage. They are flattened and lenticular in figure, and one pole is usually
acuminate ; and towards this pole several internal vesicles converge in a
symmetrical manner. These creatures were discovered by John Miiller in
1841 (Miill. Archiv, 1841, p. 477). He found in a young pike minute round
cysts in the celliilar tissue of the muscles of the eye, in the substance of the
sclerotica, and between this and the chloroid coat. The contents of the cysts
was a whitish substance, which, when examined microscopically, was found
to consist of peculiai- elements — the ' Psorosjpermia.' [A detailed notice of
these observations is given in the Microscop. Journal, vol. ii. p. 123, and in
the Brit, and Foreign Med. Rev., January, 1842.] In the following year the
same observer (Miiller's Archiv, 1842, p. 193) discovered parasitic coi-puscles
in the swimming-bladder of a Oadus Callarias, which, although specifically
distinct from the Psorospermia, approached very near to the latter in their
organization. They resembled in general a smooth ventricose Navicula, and
consisted of two elongated cases appHcd to each other at the cavity, and with
an elliptical outline and convex outer surface. They were in part free, in
part enclosed in masses within a tunic. Similar cysts, containing Psorosper-
mia, have been foimd by Leydig in several species of fish, and in all parts
nearly of their bodies, and even in the blood contained in the heart and in
the peritoneal cavity.

" Some facts, however, observed by him, connected with this subject, which
came under his notice in 1850, during some researches on the cartilaginous
fishes, served to throw a more general light upon these mysterious forms,

" In the gall-bladder of a Squatina Angelus there occurred in the bile, and
in large quantity, peculiar forms of various organization, but which were
manifestly developmental forms : — 1. Rounded vesicles, consisting of a delicate
membrane and a consistent fluid ; the latter was of a yellow colour, and con-
tained a multitude of also yellow granules. 2. Other vesicles presented, be-
sides these, other elements of a new kind : in the middle of the granular
contents were several perfectly transparent cellules ; small vesicles had only
one of tliese cellules, larger ones as many as six. 3. Other parent vesicles
agiiin, exhibited, besides their membrane, a granular contents and secondary
vesicles, containing Psorospermia, always one in each secondary vesicle. 4.
In the latter form, finally, the secondaiy vesicle had attained a large* size'
and the Psorosperra floated in a spacious clear chamber, which occupied nearly
the whole of the parent cyst. Besides these motionless cysts, there were nu-
merous free Psorospermia in the bile.

" He found, upon examination, very similar things in other fishes of the

266

GENEllAL IIISTOKY OF THE INFUSOHIA.

same class, — as in Spinacv vulgaris, Scyllium Ganicula, Torpedo Narlce, and
Baja Batis, in which the Psorospermia differed from the more usual form, in
being grooved or ribbed.

"It was very remarkable that the above-described organisms were never
met with in any other part or tissue of the body than the gaU-bladder or
biliary duct.

" With respect to the nature of these bodies, Leydig is inclined to think
that the cyst should be regarded as belonging to the family of the Gregarhue,
and that the Psorospermia must be looked upon as generically analogous to the
pseudo-Navicellcn which have been observed to be generated within the Gre-
garince.

" The question next arises, as to the existence of similar Gregariniform or-
ganisms producing Psorospermia in fr'esh-water fishes. Leydig thinks there
is reason to suppose that the animalcule discovered by Valentin in the blood
of Salmo Fario is a Gregarina, Moreover, John Miiller and Leydig have ob-
served two or three ecaudate Psorospermia in Leuciscus Dobulst enclosed in a
cyst, — whence it might be supposed that secondary cells may be developed
within one of Valentin's Htematozoa after it has been conveyed in the course
of the circulation to one organ or another, in which cells Psorospermia may
originate. With the growth of the latter, the granular contents of the Gre-
garinoi gradually disappear, which are thus transformed into cysts filled with
Psorospermia. Such a cyst would then be equivalent to a Navicella-rece^-
tacle."

Prof. Huxley, in his Lectures on Natural History (Medical Times, 1856,
xxxiii. p. 508) has the following account : —

" The Psorospermia are pyriform sacs, frequently provided with an elon-
gated, filiform, motionless appendage, and containing two or fom- clear rounded
bodies, attached side by side, within their smaller ends, and besides these,
as lieberkiihn has lately pointed out, a rounded mass of plasma. Under fitting
conditions, the Psorospermia burst, and the plasmatic mass emerges as an
Amoebiform creature. The sacs in which the Psorospermice ai-e developed,
on the other hand, can be traced back to Amoebiform masses fall of granules ;
and it seems a legitimate conclusion, that the Psorospermia are the pseudo-
Navicellce of an Amoebiform Gregarina or Gregarinoid Amoeba."

SUBSECTION II.— CILIATA.
(Plates XXIV.-XXXT.)

According to the arrangement we have adopted (p. 200), the Ciliata. as
a subsection of Protozoa, are divisible into two gi'oups: — 1. Of such as ai-e
mouthless ; 2. Of those possessing a mouth. The former gi'oup constitute the
Astoma, the latter the Stomatoda.

In Ehrenberg's system the Astoma were not recognized ; for where he did
not find a mouth in any ciliated Polygastrica, he nevertheless assimied its
existence, supposing that from its minuteness, or some other cause, it merely
escaped obsei-vation. This procedm-c was, indeed, rendered neccssaiy by the
hypothesis with which he set out, of their polygastric organization.

It must be admitted, to Ehrenberg's credit, that recent researches have
proved him right in assigning a mouth, in by veiy far the largest number of
Ciliated Protozoa, contrary to the assertions and opinions broached by many of
the most eminent microscopists a few years since. Yet there is a limited
number of mouthless Ciliata, independently of the peculiar family repre-
sented by the genus Actinophrys, placed veiy erroneously in the family

OF THE I'EOTOZOA. CILIATA.

267

Enclielia by Elirenberg, which must be separated not only from Stomatoda,
but also from the Ciliata. This separation we have canied out, in consti-
tuting the two groups Actinophryina and Acinetina, intermediate between
Rhizopoda and Ciliata. Excluding these very remarkable creatures, the
Ehrenbergian families comprehended in oui- history of Ciliata are the Pen-
clinicea, Dinolryina, VorticelUna, Ophrydina, Enclielia, Colepina, Trachelina,
Ophryocercina, Aspicliscina, Kolpoclea, Oxijtnchina, and Euplota.

Among the Trachelina were enumerated those very simple parasitic beings
which late observations have proved to be mouthless, and are referred chiefly
to a genus Opalina. These we therefore abstract, and, treating Opalina as the
type, have constituted a new family, Opalincea, a member of the group Astoma.
In connexion with this we have placed the very imperfectly known Peridinicea,
although some recent writers seem disposed to attribute to them the posses-
sion of a mouth and digestive apparatus. The organization of the Dinoh-yina
is, if possible, stiU less understood ; and since we have no other descriptions of
it than those supplied by Ehrenberg, we shaU. allow it to be mustered with
the other ciliated families named in the large group of Stomatoda.

GeOUP a. AsTOMA, ASTOMATOFS OE MoCTHLESS ClXIATA.

FAMILY I.— OPALIN^A.
(Plate XXII. 46, 47.)

General Chaeactees and Functions. — This family, represented by the
genus Opalina, consists of minute miscroscopical animalcules, moved by vibra-
tile cilia distributed generally over the body, without mouth, of an oval or
oblong compressed figure, hving parasitic in the interior of larger animals,
upon whose juices they nourish themselves. Their contents consist of a
finely-granular substance, hollowed out into a small number of vesicular
spaces, with no contractile power ; extending through the centre is an elon-
gated band-like (ligulate) nucleus, enclosed by a definite but delicate mem-
brane, and composed of a homogeneous finely-granular substance. In two
species, 0. Planariarwm and 0. undnata (XXII. 46, 47), a large pulsating
vascular canal is found ; the latter species is also furnished with strong hooks,
whereby it eff'ects its attachment to the intestinal surface, from which it cbaws
its nutriment. Propagation takes place by transverse self-division, and also, in
the opinion of a few observers, by germs or embryos. The Opalina; are com-
posed of sarcode enveloped by an integimient, and rapidly imdergo diffluence.
In several species the existence of a mouth has been sm-mised, — for instance,
by Ehrenberg in Bursaria {Opalina) Ranarum, and by Dujardin in Opalina
Lumbrici. AU doubt on this point may be always removed, Stein toUs us
(op. cit. p. 181), by using chemical reagents, such as alcohol, acetic acid, or
weak solution of iodine, which destroy the fold, and prove no real opening to
exist. If fiu-ther proof were wanted, the constant absence of foreign particles
in the interior might be adduced. This absence of a mouth aflx)rds evidence
of the merely transitional natiu-o of Opalincea ; for the same featiu'e prevails
in the case of embryos produced from the Acinetina, &c.

The vesicles or, as Dujardin calls them, " vacuoles," seen in gi-cater or less
number in all the Opalina'a, are irregularly disposed in the interior, and
according to this author and Stein, have no limiting membrane. However
this may be, they remain clear and transparent when the rest of the contents
are coloured by the bile of tlie animals tlio Opalina; inhabit. This fact
moreover, attests another, viz. that they cannot owe their formation to fluids
received from without, but that it must depend on the pecidiar properties of
the contents themselves. The formation of vacuoles in Opalince was adduced

268

GENERAL HI8T0HY OF THE INFUSOHIA.

to disprove the origin of the alimentary globules in the Ciliata generally by
the introduction of liquid from without ; but it is to be remembered that in
these two groups of organisms we have very different structural conditions,
and that in the Ciliata the entrance of water mostly holding solid particles
in suspension, through the oesophag-us, and the moulding of it into a more
or less spherical outline, are matters sufficiently proved by direct observation.
"We have stated above, that the vesicles are not contractile ; Dujardin has,
however, described those of LeucopTirys striata as irregularly so.

The ciUa are disposed in longitudinal lines, and in some instances, where
there are ridges or margins, present a greater length and thickness, as, for
instance, upon the edges of the cui-ved suiface by which the 0. Planariarum
adheres.

The sui-face can throw itself into plaits or folds, — an occurrence, however,
probably limited to animals in a diseased or dying state, as Perty remarks in
speaking of Opalina Banarum (op. cit. p. 156).

The Opalinaia axe not very active ; they swim onwards, moving at the same
time in an oscillating manner.

The above account comprises all that can be stated of the Ojjalmcea gene-
rally, since the differences in internal structure among the several reputed
species are so great, that it constitutes, as Stein points out (op. cit. p. 182),
a strong argument against the existence of the family as a group of inde-
pendent beings. However, from the study of the peculiarities of the several
members of the admitted genus Opalina, this author reduces them to three
types, viz. : — 1. The most common form of Opalina, represented by the
Leucophrys striata of Dujardin, has an oblong body, marked by some 35 longi-
tudinal granular striee, and contains a number of vacuoles varying according
to external conditions, and a central band-Hie nucleus. This animalcule
occurs in the interior of the common earth-worm (Lumbrims). Stein found
them of different lengths from 1-60"' to 1-14"', and in all stages of the
process of transverse fission. When placed in water, they become more active.
2. The second form differs from the preceding by the irregular distension of
the body when placed in water : a strong endosmotic currents sets in through
the enclosiagwall and raises it from its contents, so that these at length pro-
duce the appearance of a smaller Opalina enclosed within a large one. Du-
jardin has described this variety under the name of Leucophrys nodulata.
This Stein would unite with the first named, under the term of Opalina Lum-
brici, which, indeed, Schultze applied to the same animalcule. 3. The third
modification of Opalina might be treated as an independent species ; for,
notwithstanding a general resemblance, it has a striking peculiarity of its
own, visible under a strong magnifying power (such as 100 diameters), in the
shape of a single, strong, horny apparatus, placed near the anterior end on
the flat abdominal surface of the animal (XXII. 47). From a short common
base situated to the right of the median line, slightly curved, uncinate,
pointed processes are given off, of which one is much longer and stronger
than the other. To the left of this organ a fold or furrow occurs in the
sm-face, which might be mistaken for the entrance to a mouth. The deve-
lopment of this organ may be readily followed during self-di-\-ision. It
appears first as a homy protuberance close to the line of section (XXII. 47),
which extends backwards into the base of the process, and forwards or up-
wards into the two hoolcs. It is also worthy of notice, that generally a greater
or less number of solid oval nucleoli and short rod-hko bodies make theu"
appearance within the homogeneous substance of the nucleus. The Op>alina
Lumbrici of Dujardin is no other than the animalcule described, although its
characters are incorrectly represented by that author, who, fi-om his figure.

OF THE PHOTOZOA. — OPALINiEA.

269

has evidently seen a specimen which has very recently completed the act of
self-fission and not yet reacquired its rounded posterior extremity. The
dark stripe shown at'the fore part, and supposed to indicate a mouth, repre-
sents the uncinate apparatus above described. Stein would call this form of
Opalina the 0. ai-mata, and regard it as a further stage of development of
his so-called 0. Lumbrid.

This view is supported by the fact that he has never met with young
individuals of 0. armata ; for all the specimens he encountered were of a nearly
equal size, and lai-ger than the largest of 0. Lumbrici, in company with
which yoimg beings are veiy common. Thus 0. armata attains a length of
1-12"' to 1-9"', and 0. Lumh-ici of not more than 1-14"' ; even the products
of fission of the former are from 1-16"' to 1-14"'.

" If now it be considered that, excepting the homy process, not the least
difference in structure exists between 0. Lumbrici and 0. armata, it is ren-
dered very probable that the latter is merely a further stage of development
of the former. If this be the case, a subsequent more considerable meta-
moi-phosis of 0. armata may be presumed, when it becomes transferred to a
more favourable habitat, as happens when the worm it inhabits becomes the
food of some other animal. I have not actually seen Opalina armata adhering
to the surface of the intestine, for I have always found it amidst the undi-
gested mineral and organic fragments which fill the aHmentaiy canal of the
earth-worm. Hence it is more likely that the adhesive organ is destined to
subsequently fix the Opalina in a more permanent manner."

The long pulsating vessel seen in Opalina Planariarum and in 0. uncinata
deserves particular notice, by reason of its peculiaiity. Stein has described
it in the first-named species, where it extends the entire length of the ani-
malcule, as bounded by a definite, delicate, structureless membrane, and to
be without the outlets Schultze imagined. It contains a clear liquid like
water, which, by its rhythmical movements, it forces to and fro within it.
On killing the animal with alcohol, the waUs of the vessel are rendered very
evident. It becomes divided through the centre in the act of self-fission, and
is, in Stein's opinion, not homologous with the contractile vesicles of the
CiUata.

Nucleus. Self-divtsion. Supposed Embryo. — The nucleus is a veiy evident
organ in all the OpalincBa, with the single exception of 0. Ranarum, in which
Stein has sought for it in vain among miiltitudes of specimens and by the aid
of various reagents. In this same exceptional species it is also to be noted
that he never witnessed the act of fission, yet Siebold (" Ueber 3Ionostomiim,"
Wiegmann's ArcUv, 1835) described, in an Opalina living as a parasite in
the intestines of a frog, the existence of a number of small embryos within
a cavity of the posterior extremity of the body : whether this animalcule,
however, was the Opalina Ranarum does not appear ; for the peculiar habitat
does not by any means prove such to be the case.

A contrast occurs in the Opalina Branchiarum, where the nucleus which
lies in the axis of tlie body has the same figure as the entire being, and one-
half its dimensions. Even among examples of the same species the position
of the nucleus varies exceedingly. Simultaneously with the appearance of a
constriction in the general figure, the nucleus shows signs of approachino-
fission ; but ere this is mam'fested it assumes a central position (whatever may
have been its prerious one), so that each of the two future segments may
acquire an equal section of it. Moreover, it woiUd appear, in some cases at
least, that the constriction and scission of the body advance more rapidly on
one side than on the other of the animal. '

According to Stein, the production recorded by Schultze {Bcitriigf zi^r Natur-

270

GENEEAL HISXOET OF THE INFUSORIA.

geschichte der Turbellarien, 1851, p. 67), of a granular germ-mass in Opalina
Planariarum, at the posterior extremity of the animalcule, was nothing more
than the act of fission misconceived. The granular contents of the nucleus
(says Stein) are finer or coarser in the animals irrespective of their size ; and
the supposed germinal masses, as the figvu'e given shows, were merely the
segments of the nucleus in process of division, and not illustrations of the
ulterior development of that organ into other beings. Schultze witnessed
this process but once, in a specimen he named Opalina polymorpha, but which
was the same as the 0. Planariarum of Siebold and Stein.

Habitats, Yital Ekdowments, &c. — As stated before, the Opalincea are pa-
rasites of various animals, the most common of which are fi'ogs, newts, and
other Batrachia, earth-worms (Lumbrici), some sheU-fish, as the Anodon and
the common muscle (Mytilus edulis), and of Planarice and several Entozoa.
They are found in the intestines in the earth-worm, in the rectum and bladder
in the frog, among the cilia of the tongue of that reptile, or among those of
the gills in the shell-fish, &c.

As a memorandum touching the vital properties of Opalincea, we may quote
here an experiment made by KoUiker on the vitahty and development of the
spermatic filaments {J. M. S. 1855, p. 298) : — " The Opalina; move in a solu-
tion of common salt of 1 per cent., and of phosphate of soda of the strength
of from 5 to 10 per cent. In a solution of salt of 5 per cent., and of sugar of
from 10 to 15 per cent., they shrink up and become quiescent, though reviving
upon the addition of water. I have even succeeded in reviving the Opalince after
they had been treated with a solution of common salt in the propoiiion of
one-tenth."

Nattjee of OpAinsriEA. — The observations of microscopists in general concur
to prove that these simple beings are not independent, but the mere embry-
onic or transitional phases of other animals. This opinion was put forward
by Schultze, and has been seconded by Agassiz, Stein, and others.

Agassiz asserts (SiUiman's American Journal, 1853) that the deficient link
in Steenstrup's history of the succession of alternate generations of Cercaria,
and its metamoi'phosis into Distoma, is supphed by his discoveiy that a ge-
nuine Opalina is hatched from the eggs of Distoma. Stein coincides also in
considering them metamorphosed into Vermes, and states that Stecnstrup has
watched the transformation of Leucophrys anodonta (Elir.) into an intestinal
worm. He saw first that the cilia vanished, that they fixed themselves, and
became by-and-by changed into oval motionless bodies, which continued to
grow, and formed an internal space, within which a germinal mass was de-
veloped, out of which Cercaria originated.

Affinities and Classification of OpaltnjEA. — Upon this head the first
point is to settle what genera and species are to be numbered with the Opali-
ncea. Eor our part we are disposed to place in this family aU Cihata wliich
are mouthlcss, and which lead a parasitic life. As already noted, the absence of
a mouth is indicative of an embiyonic character, an indication strengthened,
if not confirmed, by observation ; consequently this group of beings is at best
but provisional, ser%ang only the pm-])oses of definition and nomenclature,
until science sliall be enabled to indicate the particular animals into whose
cycle of life they severally enter.

Furthermore, we have seen that some reputed species are, in all probability,
only different stages of existence of the same Opalina, — for instance, the 0.
armata a more adult state of 0. Lumbrici. And, again, the structural difi"er-
ences between 0. uncinata and 0. Planariamm (consisting in the possession
of a singular pulsating vessel) and the rest of the group are so strildng, that
they can scarcely be rightly included in one genus.

OF THE PROTOZOA. OPALINiEA.

271

On turning to the systematic descriptions of various writers, we find much
discrepancy in detail, and much difference in opinion, respecting both the
species to be counted among Opalincea and their generic distribution.

The family ' Leucojphryens ' of Dujardin, and the Cobalina of Perty, severally
include most of the species which we would reckon as Opalincea. These, in
Ehi-enberg's system, were scattered through several genera, — the majority,
however, being comprised in his genus Bursaria. Stein points out thi'ee prin-
cipal modifications of form, but is not prepared to constitute them into genera.

In the classification adopted by the three first- named writers, the Opalincea
were accounted ordinary Ciliated Protozoa. Perty and Dujardin so far re-
cognized their peculiarities as to erect them into a distinct family. Siebold
went further, and, on accoimt of the absence of a mouth, placed them, with
Astasicea and Peridinicea, among the Astoma. We coincide with Siebold in
thus more completely separating them from the stomatodous Ciliata than the
other authors named, but at the same time look upon them as more nearly
allied with Ciliata than with either Periclinicpa or Astasirea, and consequently
prefer to treat the Opalincea as a subgroup of those Protozoa.

Neither the intimate structure, nor the developmental history of the Opa-
lincea, is sufiiciently well understood for them to be arranged in well- defined
genera ; nevertheless, as both Dujardin and Perty have each essayed a sy-
stematic distribution, it behoves us to set their schemes before the reader.

Dujardin divides the Leucophryens into three genera, viz. Spaihidium,
Leucophrys, and Opalina, Besides these, he has other mouthless genera in
his fanuly Ploesconiens, viz. Diophnjs and Coccvdina, marine but not parasitic
animalcules ; also a genus Trochilia without distinct mouth, also marine in
habit, located in the famHj Erviliens ; and last, the genus Plagiotoma, among
the Biirsariens, parasitic in habit, and supposed to have a mouth situated at
the bottom of a fossa, but which contained no foreign matters, and could not
be fed artificiaUy with colouring matter. Of these genera Coccudina, Dio-
phrys, and Trochilia axe imperfectly known, particularly the two last, and

the absence of a mouth cannot be predicated of them with any certainty

whilst of the last named (Plagiotoma) the balance of evidence is against the
existence of a mouth, and, as we shaU see, this genus is a member of Perty's
family Cohcdina, and has, moreover, in Stein's opinion, no claim to rank as a
distinct genus.

The parasitic family Oohalina, Perty, comprises the genera Alastor Plaqio-
toma, Lemophrys, and Opcdina. The characters of these several o-cnera placed
by observers among the Opalincea, or some paraUel group, together Avith their
mutual relations and differences, wiU be fully treated of in the systematic
section of this work.

FAMILY II.— PEEIDINI^A.
(Pkte X. 224-226 ; XXXI. 16-23.)

This family in Ehrenberg's classification, comprehended four genera, viz
Ohcetotyphla, Chatorjlena, Peridmmm, and Glenodlmum ; but as Duhrdni
rightly judged, the two first genera belong rather to the OryptomonadiL by
being destitute of the cihary fun-ow, the leading characteristic of the Perl
dmicea. Our description wiU therefore particularly apply to the two other
genera, Pendimum and Olenodinium. ^^^^

The beings imder consideration have received Httle attention from natu
rabsts, and arc stiU imperfectly understood. Indeed, wo feel that no «^ffi • I
data are at hand .hereon to ground an opinion rol^^l ti^^'^l''^^
nature, and affinities. We place them here as a supplemental^^ group

272

GENERAL HISTOHY OP THE INFCSOBIA.

Ciliated Protozoa, first, because of their wreath or general clothing of cUia a

phenomenon seen among none of the Phytozoa or FlageUata, which have never
more than one or two, or, rarely, four filaments or flabella ; and secondly, be-
cause every author who has described them treats them as animalcules.
Perty, althoiigh recognizing them as animals, nevertheless groups them with
his Phytozoidia, probably owing to their bizarre form and to the characteristic
internal organization of Ciliata not being perceptible. Siebold, on the con-
trary, places them, together with Euglencea and Opalincm, among the asto-
matous or mouthless Protozoa.

Ehrenberg's description of the Peridinicea is as follows : — The animalcules
of this family are polygastric, but have no alimentary canal ; the mouth is
usually found in a depression near the middle, and from its vicinity a delicate
filament (proboscis) is given ofi" in three of the genera. They are clothed
with a shell or lorica, having a transverse furrow or zone occupied with a row
of vibratile cilia ; and besides this wreath, several species have also fine setae
or cUia scattered over them. In Feridinium acuminatum, P. fulvum, and P.
( Ceratium) cornutum the digestive sacs are visible without recourse to artificial
means ; but in P. Pulvisculus and P. cinctum those organs can be demonstrated
only by the use of coloured food, chiefly because they are hidden by the
clusters of ova, to which the colour of the animalcules is due. This is com-
monly red, yellow, or brown, and rarely green. In Peridinium Tripos and P.
Fusus a seminal gland (nucleus) is visible, and in Chcetoglena and Glenodinium
a red eye-speck. Longitudinal self-division has been observed in P. Pulvisculits
and P. Fu^us.

Dujardin, unable to accept these views of their organization, described the
' Peridiniens ' as " animals without known internal organs, enveloped by a
definite resistant membranous lorica, which sends ofi' a fiagelLiform filament,
and has, in addition, one or more furrows beset with vibratile cilia. The
lorica would appear to have no orifice, since foreign particles and colouring
matters cannot enter it ... . The members of this family are distinguished
from Thecamonadina by the ciliated furrow or furrows."

Further, Dujardin ignored the red stigma as a generic distinction, and in
this is followed by Perty. Ehrenberg created a subgenus of Peridinium for
those species which have the lorica prolonged into hom-like processes, under
the name of Ceratium. Both Dujardin and Perty retain this appellation, but
would elevate the group comprehended under it to the rank of a genus.

Let us now proceed with a resume of the facts at present received respect-
ing the organization and habits of the Peridinicea.

The lorica is double, consisting of an outer, more or less firm, non-contrac-
tile layer, and an inner, homogeneous, hyaline membrane : usually a space
occurs between the two coats ; but in Glenodinium they are in close apposi-
tion— a double contour, however, being perceptible. The inner layer may
be taken to represent the primordial utricle ; it immediately envelopes the
contents, which consist of a homogeneous protoplasm, enclosing within itself
numerous globules, granules, and vesicles. In the case of the smallest Peri-
dinitea, such as P. Pulvisculm, P. monadicum, and P. Oorpusculum, the di-
stinctness of envelope from contents ceases, and when in a dj-ing condition the
whole figure undergoes a great variety of changes — a fact indicating a less
perfect development of the lorica — and there is a rapid breaking up of the
contents. In the larger species the outer tunic is more elaborated, and either
displays a minute cellulai- or reticulate structure, or appears quite smooth and
structureless, although firm and resistant (as in Glenodinitim cinctum). A
cellular lorica occurs in Ceratium, and also in various Peridinia, wliich Perty
separates from the rest, under the name of Glenodinium, by reason of this

OF THE PROTOZOA. PEKIDINIiEA.

273

stmcturo. This external tiuiic is decomposable, although it resists destruc-
tion much longer than the contained matters ; and it is especially after a
certain amount of change has proceeded, that its deUcate retiform structure
is more distinctly exhibited.

The figui-e of Peiidinicea is very various and bizarre : the simplest is that
of a spheroid divided into two segments, equal or unequal in size, by a trans-
verse ciliated fuiTOW or zone. In some instances one side is flatter and concave,
and, according to Perty, presents a wide opening, or elongated fissure (XXXI.
16), from which the filament may sometimes be seen to proceed. Moreover,
besides the transverse furrow, a second is seen in some species to proceed from
it at right angles, as far as the vertex of the anterior' half,— as, for example, m
Dr. Allman's species Peridinium uberrimum (XXXI. 16, 18), and in P. fuscum
and P. ocidatum (Glenodinium cinctum, Ehr.). Indeed, in. Qlenodinium ajoicu-
latum Ehrenberg describes several subsidiary, shallower, hispid furrows branch-
ing over the surface (X. 224-226), and in Q. tabuUtum a series of non-hispid
lines or ridges. These last two forms recall in general features the pollen-ceUs
or grains of the higher plants, and may, indeed, from the deficiency of a loco-
motive filament, and from other exceptional characters, be considered doubtful
members of the family Peridinicea. An inequality of the two segments, as
separated by the ciliary zone, is seen in Peridinium Corpusculum and P. mo-
nadicum, and in a less degree in P. ocidatum (Glenodinium cinctum). The
figure, however, is very curiously and materially altered by the production of
tapering or hom-like processes, of a large diameter and great length relatively
to the principal portion or body of the organism. These processes differ in
number in different species, and give rise to very bizarre forms, departing
widely from those of any Phytozoa or from any other ciliated Protozoa. The
number of horns in Ceratium Fusus is two, and, being in the same line, produce
the spindle-shaped figure of the entire being (X. 222, 223). In C. furca
two occur in front and one of larger dimensions behind ; the same is seen in
P. Tripos (X. 219, 220), in which, however, the two anterior processes are
curved, — ^whilst P. cornutum (Ceratium HirundineUa) has from two to three
posteriorly, and one, usually curved, anteriorly. In Ceratium Michaelis (X.
221), again, we see three short processes project from the posterior half ; and^
lastly, in C. macroceras (Perty) three are represented behind, of which the
central is much the longest and straightest, and in front one stiU. longer but
rather curved. The length of the horns compared with the body of the Ge~
ratia affords, however, no specific character, inasmuch as it varies according
to age and probably also other conditions. The vibratile cilia ai"e usually con-
fined to the groove surrounding the lorica, and to the direct continuations
from it. Nevertheless Dr. AUman discovers in P. uberrimum the whole sur-
face sparsely covered with them ; and Elirenberg mentions the supplcmentaiy
furrows of Glenodinium apicidatum as occupied with hispid hairs (X. 224-
226). The locomotive filament, which Ehrenberg failed in seeing in all even
of his genus Peridinium, is usually of great length and tenuity, and, accord'^
ing to the great Berlin micrographcr, proceeds fi-om the neighbourhood of the
mouth which he believed ho detected in Peridinium Fiisiis in a liollow near
the middle of the animalcule. Allman more definitely points out its situation
as being near the junction of the transverse and vertical furrows in the species
he has described (XXXI. 16). Lastly, Perty states that Ceratium HirundineUa
(C. cornutum., Ehr.), when swimming, stretches out the filament as if stiff, and
that, although 2| times longer than tlie body, it may bo easily overlooked, on
account of its active swinging movement. It is apparently a production of' the
protoplasm, protruded externally through an apcrtm-e in the investing tunics;
Opinion is divided respecting the existence of a mouth. Ehrenberg repre-i

274

GENERAL HISTOHY OF THE IK i^' t SOltlA .

sented one, and also the possible admission of coloured food, but was contra-
dicted by Dujardin, who denied both. Siebold reckons Peridinicea among
moiithless Infusoria (Astoma). Perty mentions the fossa in the shell, but no
aperture ; and Allman remains sUent on the matter. On the other hand, Lach-
mann admits its presence, and thus discusses the mode of reception of food
(A.N.B:.1857, vol. xix. p. 220) :— "From the point of insertion of the flagel-
lum, on one side the large notch, in the upper part of the row of ciha, a clear
canal passes into the body of the animal, and dilates at the extremity to form
a cavity of variable diameter. The flagellum is often seen to contract rapidly
into a spii'al form, and apparently disappear ; and not unfrequently we may
then succeed in perceiving that it is jerked back into the above-mentioned
cavity, from which it soon returns into its previous position. Now it cer-
tainly appears worth while to see whether small particles of food are not
carried into the cavity by this jerking in of the flagellum."

Contents. — These may be divided, as in the Eiiglence, into minute shapeless
molecules, and globular corpuscles and vesicles with red stigma and nucleus.
Sometimes the corpuscles are green, and resemble chlorophyll, but more fre-
quently they are red, yeUow, or brown, or intermixtures of those colours. In
the earliest stages, indeed, colour is absent, and, just as in Euglencea, only
minute moleculse are found interspersed in the colourless protoplasm. More-
over, when a colour appears, it may not simply become more intense or darker
by age, but change to another tint belonging to the same series of coloui-s.

In yoimger specimens again, the contents more completely occupy the
entire being, whilst frequently in old, and more especially in specimens
withering or dying, they become contracted into a ball, placed either in the
centre or more or less to one side (excentric). A swelling out of the external
tunic, the disappearance of the red stigma, the vibratile cUia, and the filament
accompany this shrinking of the cell- contents. The retrograde change in
the contents is further manifested by the appearance of a large vesicle about
the centre, or of several dispersed smaller ones at that or in other pai-ts.
Some at least of these vesicles are merely oil-drops, which, as Braim shows
in his essay on Rejuvenescence, are the usual concomitants of a process of
destructive assimilation. After the destruction of the ceU-contents, the firm
lorica remains hke an empty shell, boldly displaying its sculpturing, and in
many instances also a curved, apparently internal, stripe about the middle or
to the right of it, which Perty presumes to be either the line of attachment
of the contents or a fold.

Among more constant stnietui'es. Dr. Allman describes a central nucleus —
the organ probably alluded to by Ehrenberg under the name of an oval semi-
nal gland, in Peridinium Tripos and P. Fusus. Allman describes the nucleus
to be of an irregular oval form, quite colourless, and marked on the surface
with cui-ved striae (XXXI. 20) ; under pressure the envelope gives way, and
the nucleus escapes ■with the other contents. A contractile vesicle has not
hitherto been discovered. One or more large clear vacuoles may originate in the
internal substance ; but such have not the pulsating power of definite vesicles.

The red speck or stigma (XXXI. 16, 17) has no pretensions to the nature
of a visual organ. It is not always present even in examples of the same
species ; or it is multiplied ; and it is known also to disappear with advancing
age. Again, Perty recoimts the fact of the diffusion of the red colour
of the speck throughout the whole contents, at times leaving a narrow ex-
ternal ring which retains its green colour. This phenomenon was witnessed
in a specimen of Olmodinmm cinctum. In yoiuig individuals of Pendiniuni
Uibidatum, which are of a light-green colour and translucent, there is no trace
of a red speck ; yet Perty met with a collection of these beings of apparently

OF THE PROTOZOA. PERIDINLaSA.

275

smaller size than usual, yellow iu colour, and not, like older animalcules,
greenish-bro-mi or brown, which had from 10 to 12 red vesicles or globules
about the middle of the anterior segment. Still the general rale is that iu
veiy young individuals no stigma is present. The inconstancy of the presence
of the red speck, even in mature specimens, its absence in very young, its dis-
appearance in old ones, and the many irregularities, not only in its occun-ence
but also in size and number, are facts which sufficiently prove its worthless-
ness as a generic or even as a specific distinction, and which declare against
its assumed fimction of a visual organ in this as in other families of Protozoa.

Reprodtjotion. — Longitudinal fission has been seen to take place in several
species. Self-division, says Perty, presents many peculiarities among the
Peridinicea. In Ceratium Hirundinella, fission is longitudinal ; it commences
anteriorly close to and on the left side of the great horn (as the animalcule
is viewed from above), and advances towards the posteiior extremity. The pro-
cess is not confined to the large specimens, but is equally enjoyed by the small.

During the act of fission in Peridinium Pidvisculus, Perty noticed that
before its completion the newly-formed segment continued to augment in
size until it siu-passed the original being, which underwent no enlargement.

Dr. Allman noticed, in the species he examined (/. M. S. 1854, p. 25), that
spontaneous division took place " parallel to the annular furrow " (XXXI,
18), i. e. therefore transversely, " and in the unfurrowed hemisphere." He
also remarked the important fact, that this process appears to be invariably
preceded by a division of the nucleus ; and he had succeeded in isolating nuclei
presenting almost every stage of transverse fission. But besides their reproduc-
tion by fission, Perty adopts Ehrenberg's views and insists on their development
from ova or ovules, which present themselves in the form of brown or green
corpuscles in the interior. Peridinium tahulatum is often seen to be frill of
such, elliptic in figure, and as much as 1-150"' in length, and which can be
expelled by pressure from the animalcule. In P. Pulvisculus Perty met with
specimens fr-om 1-400"' which were aggregated together in masses, and moved
together. In P. Oorpuscidwm, he asserts, development from ovules may be
directly observed ; and he gives figures of ovules set free, and of the young
generated from them, which would seem the same stractures mth the addition
of a cell- wall. The ovules, too, are large and very evident in Oeratitt/m comukim;
and he regards the smaU brown organisms which may be found in company mth
mature individuals at various times of the year, as the primitive stage of ge-
neration of those ova before acquiring the perfect figure of Cerativm. In some
specimens, indeed, he remarked the long filament peculiar to the species and a
red stigma in the posterior segment. The smallest examples measured 1-200"'
and were at first elliptic ; from this they changed to reniform, and became
distinguished into an anterior and a posterior half. Their movement was ro-
tatory or spiral, and qiiicker than in old individuals. On one occasion he saw
small examples of Ceratium Hirundinella only 1-25"', of the same figiu'c as the
large specimens, but completely colourless ; at another time he encountered
pale brownish-green incUviduals, with a beautiful red stigma, and the poste-
rior lateral horns scarcely developed, — whilst in one instance the anterior
comu was completely formed, and the posterior extremity rounded. Tliese
examples, he observes, appear to be different structural phases through Avhich
the products generated from the ovules have to pass.

The reproduction by ovules or internal germs has its parallel in Eughnma •
and, like as in this group, so in the family Peridinicea a quiescent, resting or
" still " stage appears to occur. Dr. AUman has put forward this fact most
clearly. He writes (J. M. S. 1854, p. 24)—" Before death, and also when
passing from a motile to a quiescent state, most likely preparatoiy to under-

T 2

276

GENERAL HISTORY OF THE rNFU!?ORIA .

going some important developmental change, the contents contract towards
the centre ; and then an external transparent and perfectly colomiess vesicle
becomes visible, while the flageUum and cilia disappear. The contracted
contents present a very definite and general spherical boundaiy, and are e\d-
dently included in a distinct cell " — the primordial utricle. On a subsequent
examination of the pond in which the species examined occurred in prodi-
gious quantity, he found " immense masses " of the Peridiniim " towards
the bottom, where they appeared quite healthy, though presentiag the condi-
tion described above as characterizing the quiescent state of the animalcule."

Our imperfect information respectiag the organization of the Fei-idinioea
renders any arguments concerning their nature unsatisfactory and inconclu-
sive. Perty, to whom we owe most of our knowledge respecting these crea-
tures, agrees with Ehrenberg in assigning them an animal nature ; and we
gather from the few remarks Dr. Allman has made, that this opinion has also
the advantage of his support. Dujardin, we may add, treated the Peridiniaa
as animalcules. Of the opposite opinion, viz. that they are members of the
vegetable kingdom, we know of no advocates, although some facts, such as
the apparent absence of the known internal stractui-e of the GUiated Protozoa,
the non- contractility of their bodies, the character, colour, and changes of
their contents, might be adduced in its favour. However, the force of those
presumed facts will be much lessened by the consideration that the internal
organization of the Ciliata may yet be discovered in these organisms when
they receive their due share of attention from microscopists, that even the ab-
sence of a mouth and rudimentary digestive tube would not absolutely exclude
them from the animal kingdom ; and that in the form and character of their
ciliary armature they present an animal much more than a vegetable type.

Of their Vital Endoavments, we may state that some swim with consi-
derable activity by means of their flagellum, aided, no doubt, by their ciliary
wreath, which probably gives the oscillating and rolling character to their
movements.

They are inhabitants both of salt and of still fresh water, among aquatic
plants, but not of infusions ; and they disappeai* fi'om water when long kept.
Most of the genus Peridinium are marine. They may occm* in .such enormous
multitudes as to colour the pond or other collection of water in which they
have accumulated. Of this phenomenon Dr. Allman mentions an example
in which his Peridinium uberrimum was so abundant in the ponds of Phoenix
Park, Dublin, as to colour the water brown : — " This colour was sometimes
uniformly diffused through the water ; at other times it appeared as dense
clouds varying from a few square yards to upwards of a himdrcd in extent."
This was in Jime ; in July " the coloration of the ponds had much increased
in intensity .... The colom* in some parts was of so deep a brown, that a white
disk half an inch in diameter became invisible when plunged to a depth of
3 to 6 inches, while a copious exit stream, which constantly flowed away
from one of the ponds, presented the same deep-brown tint."

The most remarkable vital phenomenon presented by the Peridinicea, and
which is particularly common in them as a family, is that of phosphorescence,
which is possessed in a high degree by several of the marine species, having
a yellow or yellow-brown colour. In nine phosphorescent drops of sea-water
from near Kiel, taken up one after another by Ehi-enberg, nothing save a
single individual of Peridinium {Ceratium) Tripos was discoverable. Besides
this species, the following other Ceratia are phosphorescent, viz. Ceratium
Fusm, C. acuminatum, C. Michaelis, and C. Fiirca.

Ehrenberg lias reported the occurrence of fossil Peridini(m ; but the or-
ganisms so considered are pecuUar in having a sUicious shell, which renders

OF THE PEOTOZOA. CILIATA.

277

tlieii- alliance to this family somewhat doubtfid. They are met with in chalk,
j the only secondary stratum, and here in the substance of flints ; but they
also occur in strata of later formation. Theii- presence in flints renders it,
indeed, supposable that their silicious constitution is an ulterior result of the
infiltration of silex in a state of solution into the textiu-e of their previously
membranous envelope. They are found in company with fossil Pyxidicula
and Xanthidia. Ehrenberg described two fossil species under the name of
Ceratium pyroplwrmi and C. Delitiense.

CILIATA.
Geotjp B. — Stomatoda.
(lUustrated by Plates XXIV.-XXXI.)

The animalcules whose general history we have now to wiite are, as before
mentioned, comprehended for the most part in the families Dinobryina,
VorticelUna, Ojphrydina, Enchelia, Colepina, Trachelina, Opliryocercina, Aspi-
discina, Kolpodea, Oxytnchina, and Ewplota, as instituted by Ehrenberg, with
the removal of the Opalincea from the Trachelina, and of the Acinetina and
Actinophryina from the Enchelia.

The descriptions of the beings composing these several families, as furnished
by Ehrenberg, are so tinged by his peculiar views of organization as to mar
their utility ; and therefore, for precision and accuracy of detail, we have to
rely in great measure on the observations made within the last few years,
chiefly by German naturalists. Notwithstanding the persevering industiy
with which these scientific men have piu'sued their inquiries, many genera
yet remain almost unknown, or little understood, in respect to their structure,
whether internal or external.

The Ciliated Stomatoda, or as we shall more briefly style them the Ciliata,
are microscopical animals having a definite limiting membrane or external
tvmic covered more or less completely with vibratile cilia, by which they
swim ; and when it is indurated, as not unfi-equently happens, it is fiu'ther
furnished with bristles or other tegumentary appendages, by which they
are capable of crawling or leaping. They aU possess a more or less di-
stinct mouth, which opens into an oesophagus or gullet, continued to a vaii-
able extent into the interior as a digestive or alimentary tube, but ending
abruptly by an open extremity. In many genera a discharging orifice or
anus is perceptible ; and in aU there are a nucleus and one or more contractile
vesicles. They propagate by self- division, by gemmation, and by internal
germs or embryos, with a greater or less degree of metamorphosis, and they
imdergo the encysting process : the act of gemmation appears Limited to a
few genera ; but self- fission and embryonic development may be predicated as
general phenomena.

Dimensions. — In dimensions all the Ciliata are microscopical ; for if some
such as Spirostomum, Stentor, Opercularia, Zoothamnium, Vaginkola, and
other genera of Volvocina and Ojphrydina are visible to the naked eye as
minute specks or globules, they are far beyond its ken for any purposes of
investigation, and are therefore essentially objects for the microscope. Yet
amid these hosts of equally microscopic beings, the range in point of size is
actually as great as that between the dog and the elephant among animals co"-- "
nizant to our ordinaiy obsei-vation. Even among members of the same genus
and, indeed, of the same species, their dimensions may vaiy within limits
extremely wide. To quote a few examples : Spirostomum ambicjiium (Ehr )
has a length of -j^th of an inch ; the branching polyparios in Epistylis and
Operculana reach ^th in height, those of Zoothamniwn |th, whilst many

278

GENEEAL HIbTOKY Ol-' THE INEUSOUIA.

stalked Vorticelke oxteud themselves to -^th. in length. Paramecia are men-
tioned by Ehi-enberg from ^th to piVu^^ length ; and specimens of the same
species of Vorticella, viz. V. microstoma, are described to vary in size between
2"3"Vu^^^ and -gT-yth. Stein has also noticed examples of Chilodon Cucullulus
from -g^ ^th to j-gLj-^th. A most sm-prising magnitude is attained by the polypoid
masses of Ophrydium versatile, which range between mere microscopic globviles
and aggregated masses the size of the fist or even of the head of a man.

FiGUHE. — In figure the Ciliata exhibit an immense variety, but have a
roimded outline in all instances. The prevailing figure is oval or oblong ; but
some taper much at one or both ends, and acquire a spindle-, or a flask-, or a
club-shaped aspect, whilst others, as the Vorticellina (XXVII. 1, 2, 4, 16 ;
XXX. 1, 9, 11), present a bell-shaped or campanulate outline, and others
again, as Spirostomum (XXIV. 298), an elongate ribbon- or band-like one.
However, the best idea of the manifold forms can be gathered by inspecting
the subjoined plates of the Ciliated Protozoa, which render verbal description
unnecessary.

The figure is determinate and constant under like phases of existence for
each species, although liable in the majority to very great changes by the
contraction and movements of the animalcules, by their contact with more
solid bodies, and by the introduction of food. These changes are propoitionate
to the elasticity of the integument and to the contractile power of the contents ;
and hence, in several with firm integument, they are very limited, or not
possible.

The figure is also much modified by the processes of mrdtiplication and of
reproduction. The act of fission materially modifies it ; gemmation does so
to a less extent ; but the most remarkable change is caused by the encysting-
process, which is generally a prelude to the peculiar set of phenomena attend-
ing the reproduction by germs or embryos, and, according to Stein's views,
would seem to tenninate in actual metamoi'phosis or transfonnation of the
beings concerned. Indeed the Ciliata in general appear to pass through a
cycle of changes, each of these entailing a distinct figure ; in other words,
in the history of each ciliated Infusorium, there ai'e several phases of ex-
istence, differing from one another in form and other particulars. The history
of an animalciiLe, therefore, is comprehended m that of no one form or phase,
but in that of every one it normally assumes ; nevertheless it is necessary to
fix upon one phase, either as the most important or the most perfect, and to
characterize and name it, just as is done in the case of insects, which are
described in their most developed or " imago " condition.

Another point to be remembered is, that the figiu-e of a specimen appears
different in most cases, according to the aspect in which it is viewed ; and,
again, there is often much diversity in shape between young beiogs and those
arrived at maturity. Perty has appUed the term ' mctabolia ' to express the
changes of figure animalcules may assume. The figure is extremely varied
in Lacrymaria by its movements, and chiefly by the lengthening or shorten-
ing of its elongated anterior portion or neck. This variability of form strack
Baker and other old observers so forcibly, that they applied the term Proteus
to designate the animalcule (XXIV. 274, 275). Tracheloccrca (XXIV. 317-
319) and Phialina have a similar power of vaiyiug tlicir outline ; and all three
genera are further remarkable by the manner in wliich their surface can be
thrown into transverse or even intersecting folds or plaits.

The influence of food when swallowed in modifying the figure, Ehrcnbei^
particularly illustrated in his Eiu-helys Farcimen (XXVIII. group 64). This
animalcule devours others nearly as large as itself, and, to effect this, widely
dilates its mouth, and so becomes shorter and broader ; and as during the

OF THE PllOTOZOA. — CILIATA.

279

operation it continues to swim about, its appoaxance with the half- swallowed
being is veiy ciuious. Again, when engulfed the anterior portion contracts,
whilst the posterior becomes dilated, giving the Enchelys a flask-shaped outline.
I In descriptions of the Ciliata, authors have used various terms, applied to
I the segments or members of higher animals, to designate vaiieties in the form
and in the mutual relation and position of their parts. The application of
many of these terms to the Protozoa is indeed very arbitraiy and fanciful ;
and it is only from the absence of better that we continue to employ them.
The end of the body which advances foremost in swimming, and at which or
near to which the mouth is ordinarily placed, is called the head, and often has
an additional claim to the appellation by its construction as a segment distin-
fl guished by some points of structm'e from the rest of the body. The opposite
portion of the animal constitutes, when tapering or provided with some sort
of process, the tail, but is more generally spoken of, especially when not
distingmshable as a segment, as the posterior or caudal extremity.

A ' dorsum ' or back, and a ' venter ' or abdominal surface, are usually de-
scribed, but are not readily determinable in all genera, as, for instance, in the
Vorticellina and Ophrydina. To distinguish the one surface from the other,
regard must be had to the position of the mouth (which indicates the abdo-
minal surface), to that of the locomotive cilia and other processes, and to the
mode of progression. But, after aU, the distinction will oftentimes be arbi-
trary, and in consequence the description of a right and a left side frequently
so too. It is a general character of the Ciliata, that they are asymmetrical,
i. e. not formed of two equal and similar halves. An exception to this rule
exists in CoZeps (XXIV. 284) and in the Ichthyd'ma (XXXI. 28-30), which
in Ehi-enberg's system were included with the Rotatoria. Where, although
symmetry is not visible, a right and a left side are distinguishable, such Infu-
soria are called ' bilateral,' — e. g. the Oxytrichina (XXYIII. 10), Paramecium
(XXIX. 2.5-30), Chilodon (XXIX. 48).

Of minuter modifications in the figm-e of Protozoa, a large number have
foimd names which will be best understood in the special structiu'al details of
particular animalcules. However, to mention some here used by Ehrenberg,
we may cite the frontal region or forehead — the obtuse or trancate part of
the head above the mouth ; the lips — projections above and below the mouth,
when this aperture is situated in a fissm-e ; the tongue or palate, usually a
process in the oral fissure ; the rotaiy or ciliary disk, seen as a ciliated pro-
jectile process above the margin of the anterior extremity of the Vorticellina
(XXX. 1, 2, 9, 11, 14). In several genera the anterior portion of the body
is much produced, and looks like a long tubular neck or a trunk, and hence
is called frequently by Ehrenberg proboscis, — e. g. in the genera Lacriimaria
(XXIV. 274, 275), Trachelii(^ (XXIV. 287-289), AmpUleptus, and Trache-
locerca (XXIV. 317-320). This term proboscis we have ali-eady seen used
to designate the long locomotive filaments or flabella of Phytozoa, totally
different processes from those called by the same name in the Ciliata just
enumerated. Its use for one or the other should be set aside ; and althouo-h
at the best it conveys a very erroneous impression — for no such tiiino- as'' a
proboscis or trunk, in the proper meaning of the word, has an existence in
any of the Protozoa — its application to these is less objectionable than to the
Phytozoa. In Uroleptus (XXV. 333) the posterior extremity is abniptly
elongated, and forms, according to the description of the same distinguished
naturalist, a tail.

Consistence.— The Ciliata arc composed principally of a very soft almost
mucilaginous matter, which has been well named ' sarcodc,' since like the
flesh or muscular tissue of higher animals, it seems to present an' inherent

280

GKNERAl HlSTOfiY OF THE INFUSOUIA.

contractility and elasticity, and is the active agent in the movements of their
bodies. It is hyaline, transparent, and colomiess ; but its refractive power
is not much greater than water, which is essential to the exhibition and
continuance of its properties, for when this fails the homogeneous mass of
sai-code breaks up into minute globular portions, which disperse themselves
on every side. This disruptive process has received the appropriate name,
from Dujardiu, of ' diffluence.'

Ecker states tliis self-same sarcode to be the common contractile element
of all the lowest forms of animal life — ^for instance, of the Polypes. The par-
ticles set fr-ee by ' cUrffluence,' he also represents to be contaractile, and to
assume Amceha-^e movements ; but this, according to Cohn and Stein, is
an error, inasmuch as they are simply elastic. Cohn also adds that the
variable movements of the sarcode-particles of Hydra are merely a physical
phenomenon due to endosmosis. The process of diffluence, whether from
external injurious conditions or damage, or from noxious matters received
within, varies so much in rapidity, that Cohn (Zeitschr. 1851, iii. p. 267) con-
cludes that it must indicate some variations in its composition and structure
in different animalcules. Eor instance, he says, Stentor ccerideus bursts ; and
its contents break down by diffluence as rapi(Uy as sugar- in water, streaming
out from the rest until the funnel-like pharynx only is left behind. On the
contrary, in other animalcules, e. g. Paramecmm Aurelia, the sarcode exudes
through the surface at all points, and swims away, leaving a vacuolated or
ai'eolated interior. Again, Loxodes breaks up into fragments of a considerable
size, which escape through lacerations of the surface.

Integument. Markings on the Sttrface. Condensed Integument oh
LoBicA. Appendages of Integtjment. Cilia. Spines. Exteknai Sheaths.
— Ehrenberg described his Polygastrica as in aU eases defended, and their
figure defined, by an iategiiment or skin, — a statement as generally contra-
dicted by Dujarchn, though now confirmed (in the case of aU the tine Cihated
Protozoa) by the researches of numerous later naturalists. The means resorted
to for its demonstration, where not otherwise evident, consist in the application
of chemical agents — ^for example, of acetic acid, of tinctui'C of iodine, and of
diluted alcohol, all which operate in a different manner upon the integument
and on the contents of the body, most fr-equently causing a sepai-ation of the
two by corrugating the latter, and, it may be, colouring it at the same time.

Perty could not convince himself of the existence of an epidermis, although
he believed the external surface to be modified so far as to render it more
resistant, or in fact to form what Mr. Carter calls a pellicle ; at the same time
he attributed marks or lines visible on the sui-face to fat- or other corpuscles
subjacent to it. " The pellicula," Mr. Carter says, " is a structm-eless pro-
duct, which hardens after secretion ; and the inference is that there is a layer
below specially organized for its formation," and that it is not secreted by
the lamina known as the " cortical layer " or the " diaphane."

On the other hand Meyen, Siebold, Kdlliker, Frey, and Leuckart concur
in describing a distinct enveloping delicate membrane, which Frey thought
evidenced both by the manner in which an animalcule ruptures iinder pressure
and gives vent to the soft contents, and by the appeai-auce of Uttle slireds he
noticed on the torn edges of a Stentor. A more direct demonstration was
afforded by Cohn, who resorted to chemical reagents for the purpose.

This excellent observer experimented with several of the larger CiUata, but for
illustration referred chiefly to Loxodes {Paramecium) Bursaria. Stein argues
that the animalcule so described by Cohn was not a Loxodes, but a Paramtcium,
since all its cilia were of equal length, a featui'e peculiar to tlus genus (Stein,
op. cit. p. 239). On adding a little alcohol to a drop of water containing

01" THE PROTOZOA. CILIATA.

281

specimens of this animalcule, death ensued ; but before this happened a deh-
'cate membrane was seen to elevate itself at parts of the suiface, producmg a
vesiculai- appeai-ance, and accompanied by a shrinking of the contained matters ;
whHe these changes proceeded, several contiguous vesicles would run into one,
and thus strip more or less completely the subjacent tissue, until, by the pro-
longed action of the alcohol, a central shrunken mass appeared, surrounded by
a loose membrane, adherent to it only at the spot where the mouth was con-
tinued inwards as a pharynx. This membrane, so demonstrated, is homoge-
neous and transpai-ent, but not entirely structureless ; for close obsei-vation
reveals, over its entire surface, two series of spirally- disposed, dehcate, and
dosely-approximated Hues, which so intersect one another as to produce a
miniatui-e diamond pattern (XXIX. 26). Fiu'ther, the notched or serrated
appearance of the periphery (XXIX. 28, 29, 30) shows that these hnes are
actually folds or furrows, and that each little diamond may be represented as
a minute four-sided pyramid beaiing a cilium at its summit.

By pursuing a similar plan of investigation, a separable integument has
been demonstrated in many Ciliata. For instance. Stein described such a
covering in the several genera he subjected to obseiwation, and proves its ex-
istence also after the process of encysting has taken place. On adding dilute
acetic acid to the Vorticellina — for example, to specimens of Epistylis or Oper-
cularia — the contents shrink into a denser mass, and in so doing detach them-
selves from the integument, which is then rendered evident as a transparent,
sti-uctureless, homogeneous, and smooth membrane, having a clear, sharp out-
line. When tincture of iodine is applied, the integument remains uncoloured,
whilst the contents acquixe a golden-yeHow tint. A solution of sugar, and
afterwards a dix)p of concentrated sulphmic acid, being used, causes the con-
tents to swell up and to assume a rose-red coloiu', the external wall continuing
uncoloured.

Eespecting the chemical constitution of the membrane of Loxodes, Cohn
Lnfoi-ms us it is soluble neither in sulphuric acid nor in potassa, whilst the con-
tents are dissolved and dispersed by the latter. From this reaction he con-
cludes that the cuticle is not a proterne compound, like animal membrane in
general, but the substance called chitine, and therefore in this respect similar
to the cuticle of plants. In Paramecium, he adds, an integument having the
same sort of markings and a similar chemical reaction exists, and that, with-
out doubt, all the species described by Dujardin as having a reticulated
envelope, in his families ' Bursarions ' and ' Parameciens,' have a like structure.
Moreover, this skin has its special characters in different genera, as is illus-
trated in the above accoimt of Paramecium Bursaria, and may be exemplified
in other cases. Thus in Coleps and Stentor polymorphiis, the cuticle is so
intersected by lines as to leave intermediate four-sided prisms, each of which
bears a cilium at its apex, whilst at the intersection of the lines, single long
hairs are also seen, similar, says Lachmann {A. N. H. 1857, xix. p. 1 25, in foot-
note), to the hairs of many Turhellaria. Again, Ophrycl'mm versatile has its
integument th^o^vn into fine, closely-aggregated, annular folds, and into three
longitudinal nigae on one side (XXX. 5), which disappear when the animal
shortens itself by contraction (XXX. 6). Spirochona (XXX. 17), says Stein
(p. 208), has a hyaline, firm, inflexible parchmont-lilce skin, with a distinct
double outline, but without any inherent contractility. It is most like the
integument of Ewplotes, but differs apparently in not being capable of falling
into folds around the body. It resists the action of acetic acid, wliich dis-
solves out the whole of the living contents, and leaves it in an isolated state.

Whilst representing all animalcules to be covered with an integument,
Ehrcnberg distinguished those enclosed by a firm, more or less unyielding^

282

GENERAL mSTOIlY OF THE INEUSOUIA.

envelope or sheath, as ' loricated,' in opposition to the rest, which he called
' Uloricated.' These terms he has, however, employed in so loose a manner,
that they really possess no definite and constant meaning. For example, the
sheaths of encased animalcules represented by the Ophrydina are designated
loricae, the enclosed animal, although possessing a distinct integument, being
considered naked, — ^wlule, again, the indiu-ated closely-fitting integument of
Euplotes and Goleps is equally styled a lorica, although so different in cha-
racter and relations. The term lorica could only, indeed, be legitimately
employed either to designate the sheaths of such animalcules as the Ophry-
dina, or the indurated integument of others, as Ooleps, — to one or the other,
but not to both ; to the former it is unnecessary, to the latter it is admissible.

The integument of the Ciliata has generally been regarded to be in itself
contractile ; but it seems that this is an error, and that, in fact, it is simply
elastic. As such, its action must be counter to that of the subjacent con-
tractile layer, and be therefore the chief agent in restoring the figure when
the contractile force is relaxed ; at the same time its elasticity will allow of
considerable alterations in form, from contact and pressure of external more
rigid objects. To this an exception occiu's in the case of those Ciliated Pro-
tozoa in which the integument is much hardened, and foims a lorica or shield.
This induration may be more or less extensive, so as either to cover the dorsum
with a shield-like plate (scutellum), as in (Jhlamidodon, or to entirely sur-
round the animalcule, as in Coleps, when it constitutes an " urceolus," open
at the ends.

The external envelope, when thus hardened, has developed from it various
processes, of a more or less rigid character, which look like spines (sette)
(XXIV. 284, 285), or hooks (uncini) (XXV. 344, 347), or are elongated as
styles (XXXVni. 10 ; XXV. 350, 351), all which ai-e oftentimes made sub-
servient to the act of locomotion, and less frequently to that of prehension also.
It must, however, be admitted that such processes are not confined to genera
in which the integument is very appreciably indurated, but occur where it is
of softer consistency — ^for instance, in Stylonychia (XXV. 343, 344).

The integument is combustible and also diffluent, even when indurated, just
as are the softer contents, although more slowly.

ExTEBNAL Sheaths oe Cases. — Before quitting the account of the common
integument or cuticle immediately investing the body of the Cihated Protozoa,
a description of an homologous membrane, in fact, of a prolongation, dedu-
plication, or process of it, in the form of an external sheath or case about
certain fixed species, becomes necessary.

The species so encased are either sessile or have only a short stallc attach-
ing them to the bottom of the case ; thus Vaginicola (XXVII. 10, 11) is
stalkless or nearly so, whilst Tiiitinnus has a more appreciable pedicle : on
the other hand the case itself may be stallced, as in Cotlmrnia (XXX. 12-16) ;
where this happens, the stem does not equal the lengtii of the sheath, but is
short, solid, and thick, expanding upwards to its attachment with the base
of the latter, and frequently thrown into transvei-se folds and curved (XXX.
12, 15). It is homologous -with the rigid stem of Epistylis, which it resem-
bles also in chemical characters.

A very remarkable exception to the general rale of the attachment of
tunicatcd Vorticellma to the bottom of theii- case, occurs in the new genus
Lagenophrys, in which the animalcule is suspended from the narrow aperture
of the sheath, so as to leave a more or less considerable space around it
(XXX. 29-34). The margin of the head of the animal, ?. e. the peristom, is
beneath the opening of the sheath, whicli has the further peculiarity of being
veiy narrow and two-lipped (XXX. 29, 32, 34). In one species (L. nassa) a

or THE PROTOZOA. CILIATA.

283

cylindi-ical short tiibe, with a serrate edge and longitudinally striated, is re-
presented by Stein to project from the opening of the sheath. It is, he adds,
separable above into two lips, which close when the animal retracts itself.

It is not veiy imusual to meet with sheaths occupied by two animalcules,
— a circumstance due to the act of self-division (XXVII. 10 ; XXVIII. 19).
In a few instances also, one, two, or more small young individuals lie free
within the sheath of the parent, e. g. LagenopTirys (XXX. 29, 34). The
sheath is always a product secreted from the animalcule, and first makes its
appearance aroimd its base as a soft, homogeneous, colourless, jeUy-Hke matter.
During the process of its formation, the animal presei-ves a contracted state,
which diminishes, however, as the excreted layer advances, and ceases on its
completion ; and since each genus has a characteristic outline, as well in the
contracted as in the expanded condition, the sheath acquires also its special
character only. More or less of the posterior extremity is concerned in ex-
creting the formative matter ; but this having adhered to the anterior part
whilst iu a contracted state, becomes drawn forward by the progressive
elongation of the entire body, until at length, on full expansion taking
place, the connexion is broken and the sheath acquires a free edge. So soon
as excreted, the gelatinous layer proceeds to solidify, and simultaneously to
contract itself ia thickness, so as to form a membrane, which, on its subse-
quent detachment fi-om the fore part of the animal, forms a loosely-investing
case around it. This description of the construction of the sheath applies to
all those genera where the animal is fixed at the bottom ; but in the iustance
of Lagenophrys, where it is suspended from the constricted orifice of the case
by its peristom, some other plan of formation must be presumed, concerning
which, however, we have as yet, unfortunately, no direct observation to teach
us. In several species, as Cothurnia imherhis, the sheath not merely acquires
a parchment-like firmness, but also a decided colour — ^mostly yeUow at first,
afterwards a rusty red.

Dr. Strethill Wright, of Edinburgh, has kindly sent us some notes on the
iatitnate sti-uctm-e of the sheath of Lagotia ; and doubtless they hold good to
a greater or less extent, so far as they represent general facts, in the case of
sheaths of other Ophrydina. He writes — " The tube consists of yeUoMdsh
chitine, Hned vrith a layer of dark-green sarcode of varying thickness (which,
I beheve, secretes the chitine), and covered externally by a much thinner
layer of matter, which appears to be equivalent to the ' colletoderm ' of the
Hydroidce." This structure is illustrated by figs. 12 and 13, PI. XXXI.
The following account applies specially to the sheath of Lagotia (XXXI. 7, 8*
12, 13), which presents a series of rings, apparently spiral, but, in our opinion'
not so. " The Unes," says Dr. Wright, " are seen to consist of the remains of
the trumpet-shaped mouth, which is partially absorbed as the tube increases
its length, but still remains as a slightly-overlapping ridge over the new part
of the tube growing within it. The groove thus formed is filled up with the
' colletoderm.'' The spiral character seems to be in some way connected with
this mode of growth ; but I have not satisfied myself in what way." In a
subsequent letter he wiites— " The chitinous matter of each successive ring
is not continuous with that of the rings above and below it ; it is only at-
tached to it by the inner lining of sarcode and by its outer covering (XXXI
12, 13). We have by tliis conchtion a provision for the growtli of the tube*
both in width, length, and thickness, similar to that which occurs in the
sheU of Echinus. Growth in length may be eff-ectcd by deposition of chitine
on the upper and lower edge of each ring, growtli in breadth by the gradu-.l
unrolling of the spiral, while a continuous deposition of hard matter froiii
the mner hning of sarcode thickens and strengthens the whole tube "

284

GENEllAL niSTOUY OF THK INFUSORIA.

In speaking of the attachment of the sheath, we have mentioned only that
by the base, with or without a stalk. But there are a few forms which affix
themselves to foreign bodies by one side of their sheath, e. g. Vaginicola
decumbens (Ehr.) and the genus Lagenophrys. In such cases the attached
side is flattened, so as to increase the surface in contact.

But, apart from the mode of attachment, the sheaths of different genera
vary in figure ; and as to size, there is no constant relation between that of the
case and that of the enclosed being. The figure of the sheath, even in one
and the same species, is subject to modification from age and from surrounding
circumstances. Thu^, in Vaginicola crystallina it is usually cylindrical and
truncate (XXVII. 11), but at times it may be beUied posteriorly (XXYII. 10),
or, otherwise, have its anterior border expanded and curved outwards, or be
narrowed in front, or compressed in one direction. Nevertheless there is
usually a general resemblance in figiu'e among individuals of the same species or
genus, sufficient to furnish descriptive characters. For example, C'othurnia
imberbis has commonly a cylindrical sheath, bellied posteriorly and sHghtly
contracted anteriorly (XXX. 15), whilst C. Sieboldii is campanulate, and has
its anterior half compressed in one direction, and its angles in front prolonged
and tapering (XXX. 13, 14). In the genus Lagenojihrys, when adherent by
its flattened side, the sheath appears ovoid or shaped like a bellied oil-jar, with
a contracted truncate mouth (XXX. 29, 30). A peculiar form of sheath is
presented to u^ in the genus Lagotia (XXVIII. 21, 23), which may be de-
scribed as retort-shaped, the relative diameter and length of the body and
neck diff'ering in different specimens or species. In one species, at least, the
neck has the further peculiarity of being thrown into spiral or, otherwise,
annular folds or rings (XXXI. 7, 8), the presumed form and origin of which
have just been described.

We are further indebted to the discoverer of Lagotia for the recognition of
a remarkable valvular structure within the tubiilar sheath of a species of Va-
ginicola, which he in consequence names Vag. valvata (XXVIII. 18, 19).
Dr. "Wright states (Edin. New Phil. Joum. April, 1858) — " On examining
the valve in situ, 1 found it to consist of a rigid plate imbedded in a thick
layer of transparent sarcode (XXVIII. 18 6), which latter was continuous at
the lower end of the valve with a thin layer of the same substance, lining
the whole of the interior, and coating the upper part of the exterior of the
tube. The valve was closed by a contractile process passing fi-om its under-
surf'ace to the wall of the tube .... I am disposed to consider the whole ap-
paratus to consist of an oval plate of soft sarcode, supported by an included
bar or naiTow plate of horn or chitine .... In some specimens the tube was
marked with close transverse or circular strise."

In Stenior Milleri (XXVIII. 16, 17), we have the cmious instance of an
animal living indifferently with or without a sheath, and enjoying fi-eedom of
movement. Amidst mmicrous specimens of this species, not a few (says Cohn)
may be seen swimming freely about, or, otherwise, attached, enclosed witliin a
roomy ovate sheath, composed of a soft gelatinous substance, and open at one end
(XXVIII. 17). The animalcule is fixed by its posterior extremity (apparently
converted for the time into a suctorial disk) to the closed end of the sheath : but
it is still able to evert its spiral ciliary wreath, and to extend itself beyond the
open mouth, or to retract itself in a contracted condition within its interior.
Ehronborg remarked the exudation of a mucous sheath around this animal-
cule when kept confined for some time for observation within small glass
tubes, but mistook it for a sort of morbid act preparatory to death. Cohn, on
the contrary, has shown {Zcitschr. 1853, iv. p. 263) that it is in no way con-
nected with disease or with approaching death, but happens with indi^iduaIs

OF THE PROTOZOA. — CILIATA.

285

i in full vital activity and suiToimded by favom-able external conditions, and
I adds that gemmation frequently proceeds in these encased beings, and that,
■ when from evaporation of the surroimding fluid or other prejudicial cause the
animals are thi'eatened with injmy, they quit their sheaths and swim away,
the previously suctorial extremitj'^ resolving itself into a pencil of bristles.
The result of these observations of Cohn is to disassociate this phenomenon of
sheath-formation in Stentor from that of the encysting process, to which
Ehi'enberg's account of it would have led it to be referred.

Dr. Strethill Wright coincides mth Cohn in denying the relation between
the presence of the sheath of Stentor Mulleri and the diseased or dying state
of the animalcule. Indeed he speaks of the presence of a gelatinous case
as the rule, and adds that " as the zooids (animalcules) divide they form a
gelatinous mass, which is attached to weeds and often to the surface of the
water, from which I have seen some 10 or 15 combiaed Stentor s hanging
with their heads downwards."

CiuA AND CiLiAEY AcTioN. — The most common, and at the same time the
characteristic external appendages of the Ciliated Protozoa are the cilia, which
constitute their most active and powerful locomotive organs. Cilia are,
moreover, not wanting internally, but are there comparatively few, since
they are appendages only of free siu-faces. They are met with lining the
oesophagus, where they, no doubt, sei-ve to facilitate the ingestion of food and
of the water taken in for the purposes of aeration.

The natui-e and cause of ciliary movement have been much debated. To
account for the energetic and pecuHar movements of cilia, Ehrenberg imagined
the existence of a muscular apparatiis at their globular roots, consisting of four
muscles, each pulling in an opposite direction, but, by acting in succession,
causing the apparent rotation of the axis around the fixed base. This bold
idea has met with no favour among physiologists, who condemn it as pui-ely
imaginary and as opposed to the simplicity of natiire, to aU analogy, and to
aU the admitted facts and principles of histology. Most inquirers despair of
attaining a satisfactory explanation, of ciliary action, and treat it as an ulti-
mate fact. However, Cohn, looking to the peculiar structure of the integu-
ment of Paramecium (Loxodes) Bursaria (XXIX. 26), fancied that cihai-y
motion admitted of explanation, since, on the supposition of an inherent
contractility in that membrane, each Httie pyramid might be imagined to
contract its sides m turn, and make the ciUum surrounding it revolve in the
figure of an inverted cone. But granting the possibility of this explanation
in the case of the ammalcule cited, it could in no wise be appKed generally
to ciliary motion; for a similar structure is found in comparatively few other
examples and the innate contractiHty of the supporting membrane, assiuned
m the instance m question, has certainly no existence in many ciliated sur
feces, and mvolves nearly an equal stretch of imagination to conceive as
Ehrenberg's muscles.

Retiirning from this digression on the natiire and cause of ciliary action,
let us bnefly review the mode of distnbution of ciha in the Protozoa In
many genera they are distributed imiversaUy over the siu'face (XXIX. 20,
^a, 4» ; AX VIII. 1, 8, 31), not at random, however, but in definite parallel
hnes, more or less approximated, usuaUy travei-sing the length of the body
A distribution in parallel Imes is also not unfrequentiy observed acrS
or aroimd the body. Even where generally diffused over the body, thev are
commonly more developed at certain parts, as about the mouth, the headend

Lfiuodon (AXiX. 48), Bursaria, Leucophrm, Stentor &c Stmn tL^J^ 7^
It as a generic character, that in ParLJ^ (SiX 28) alT Ve E'^^^^

286

QENEllAL HISTOEY OF THE INFUSORIA.

of imiform length. In Colejos (XXIV. 284), the lorica is divided into a mul-
titude of minute facettes by intercurrent lines or sulci, and the cilia are placed
at the points of their intersection. In Colpoda Cucullulus (XXIX. 35, 36, 37),
the cilia are much longer at the anterior prolonged extremity, the lip, just
as in Ohilodon ; but there is besides, in the deep sulcus where the mouth is
found, a dense pencil of long and strong cilia (XXIX. 37), which Ehrenberg
mistook for a solid process of the body, and called the " tongue." From this
fasciculus or bundle, a row of long cilia is, moreover, seen to extend backwards
to the posterior extremity (XXIX. 37).

Other groups of Ciliated Protozoa have the cilia confined, more or less strictly,
to one part or organ of the body, — a circumstance exemplified in the Vorti-
cellina and Ophrydina (XXX. 1, 2, 5, 9 ; XXIX. 1, 3, 4, 5). This limita-
tion, as contrasted with the general diffusion of cilia, impHes an advance in
the scheme of organization, and is attended by the constraction of a special
apparatus about the head of the animalcules. Thus, in the families named,
the rule is that the anterior extremity is bounded by an evident, mostly thick-
ened margin, either curved or straight^ — the "peristom " — crowned with vibra-
tUe cilia and complicated by an internal, usually extensile, ciliated disk or
rotary organ (XXX. 1, 2, 9 a, 29 a), the whole apparatus recalling the struc-
ture of the rotary organ of the Rotatoria. The cilia appertaining to the pe-
ristom and disk are highly developed and strong, although, instead of serving
for locomotion, they only subserve the processes of nutrition and aeration or
respiration, by reason of the fixed condition of the animalciiles possessing them.

Another peculiarity of the ciliary apparatus of the Vorticellina and Ophry-
dina is that it is retractile (XXX. 6 a), or can be involuted and withdrawn
into the interior of the animal (XXX. 13), and the peristom closed completely,
and contracted sometimes so far as to di'aw in a part of the waU around it,
and not leave a single eilium visible externally (XXX. 11 b, 31, 33). When
thus retracted, the ciliated organ appears like an internal, irregular-sigmoid,
contracted cavity or fissure, with the cilia closely packed together and scarcely
distinguishable (XXYII. 5 a, b ; XXX. 11 b). The retraction of the ciliary
wreaths, which takes place veiy rapidly, is caused by the presence of snr-
rounding objects in the immediate vicinity of the animal, by their contact
with it, by any shocks it may feel, and by the presence of noxious matters in
the water. On the removal of such and similar causes of annoyance, the ex-
tension of the delicate apparatus follows ; this act, however, is less rapid than
that of retraction, and may be arrested at any point.

A more permanent withdrawal of the rotary apparatus, in the families
named, occurs when the process of self-division is about to proceed (XXVII. 3 ;
XXVIII. 18), and also when the animalcule prepares to enter into the en-
cysted condition (XXVII. 5, 7).

The disappearance of cilia is witnessed not only in Vorticellina and Ojphry-
dina when the process of encysting takes place, but is a general phenomenon
among ciliated organisms under the same circumstances ; yet it would appear
that in some cases, even when an animalcule has siuTounded itself vnth a
cyst, its cUia are not actually lost, but only withdi-awn from view, — a fact
adverted to by Stein ia his accoimt of Ohilodon Cuctdhdns, which at times,
after encysting itself and developing one or more living germs within the
cyst, has been seen to renew its original appearance, to regain its cilia upon
its surface, and, after rotating for a while within the sac, to burst at length
through it and escape (XXIX. 55, 58). Moreover many observers have
asserted the fact that an animalcule may, soon after encysting itself, be set
free by rupturing the cyst by pressure, and then reassume its previous cihated
and active condition. Nevertheless the act of enc>'sting. when advanced to

OF THE PBOTOZOA. CILIATA.

287

a certain point, or when the reproductive process consequent upon it differs
from that seen in Chilodon, appears to involve the final disappearance both
of generally diffused cilia and of specially organized cUiary wreaths.

The arrest of the motion, and the ultimate disappeai-ance of cUia, are phe-
nomena attendant also on the death, or on the approaching diffluence, of ani-
malcules— when the surrounding water dries up, or when their vitality is
injured by chemical agents or by physical forces, such as electricity and heat.
Stein, however, states that, although the animalcule, e. g. a Paramecivm, is
killed by the addition of veiy dilute acetic acid, yet its cilia continue visible
and of their normal length. Cohn beUeved the cilia to be very much longer
than Ehrenberg represented ; but, as Steia affirms, this notion origiaated from
an unnatural appearance consequent on the dying state of the animalcule, from
evaporation of the surrounding water ; and he adds that a similar elongation
of cilia appears immediately at the point where strong acetic acid comes into
contact with the siuface. But this explanation has since been set aside by
Prof. AUman's discovery of the existence of trichocysts, or thread-cells,
within the subtegumentary layer of the body (XXXI. 1-4), to which he at-
tributes the phenomena observed and discussed by Cohn and Stein.

An instance of a temporary formation of cUia is seen in the Vorticellina
and OpJirydina when the offspring, fomied by fission or by gemmation, is pre-
pared to detach itself from the parent being. Under such circumstances, and
prior to the development of the interior retractile ciliary organ, a wreath of
cilia makes its appearance (XXYII. 4, 11) near the posterior extremity — but
which, indeed, for the time, advances first in swimming, and continues to do
so until the animalcule has attached itself and proceeds to unfold the ciliated
apparatus at its head.

In the above account, reference has been chiefly made to vibratile cilia, but,
as before noticed, there are tegumentary processes of larger size, coarser and
stiffer, and withal not vibratile, although moveable. Such serve frequently
as special organs of locomotion, or of prehension, or of both, and may also be
occasionally considered weapons of offence and defence. According to their
form they are named setce, or bristles ; uncini, or hooks ; dm, styles and
filaments.

Some of these tei-ms are both loosely defined and used. Thus the bristles
so called of one author, are spoken of by another as cirri, or styles or fila-
ments,— the structures thus variously called being long bristles, mostly taper-
ing, and either straight or but sUghtly curved. The term " cirri " (in English
tendrils) should be disused, both as being unnecessary and also as conveying an
erroneous conception ; for no organs like tcndiils exist among Protozoa Un-
cini (hooks) are very thick at the base, strong, eiu-ved, and comparatively short
processes (XXIX. 15, 17) ; styles are stout setiform bristles, articulated at
their base to the cuticle, and of considerable length (XXVIII. 10 • XXV
350, 351). These last-named processes, Lachmann teUs us, are sometimes
split up at the apex into two, or oven as many eight, parts, as happens in
various Euplotes (for instance, E. Patella, m which species, moreover one
style bears a number of small lateral setiform branches). The divided styles
occur at the posterior extremity, and are trailed along in the movement of
the animals, and only occasionaUy employed in pushing them forwards whilst
the uncmi m advance seiTO for actual creeping and climbing. As ex'amnlcs
of these tegumentary appendages, may bo adduced the set® of Urostula anA

;^Tv%4^V.?f ''f^f^r^^ «¥«7f O^riftricMna (XXVIII. 10), Eunlotes
(XXV. 350-353), and o{Ploescoma. Intermediate grades, between the hiehlv
developed setose processes cited and ordinary vibratile cilia, may be seen in
the larger and more ngid ciliary stnictures alluded to above as often found

288

GENERAL HISTOEY OF THE INFUSORIA.

along the margin of animalcules, on eminences and in depressions and other
particular pai'ts ; such Lachmann would name " ciliary bristles." In Tricho-
dina Pediculus (XXIX. 17), Stein describes a circle of uncini supported on a
cartilaginous or corneous ring, and external to this a yellowish membrane of
corneous consistence and extraordinary flexibility, with closely-placed strise
across it. On a lateral view of the animalcule, this membrane is seen to lise
round the circlet of uncini like a raised rim (XXIX. 17/).

Locomotive and Fixed Forms op the Ciliata. Vakieties of Locomotion.
Transitory Power op Locomotion among tke Attached Genera. Pedicle
Single and Branched. Yabied Outline op Eamipied Stems, Steuctuee of
Stem. Conteaotile Stems. Rigid Stems. — The Ciliata, with respect to the
function of locomotion, present themselves under two groups, — one compre-
hending those genera which at all periods of their existence can move from
place to place at wiU, the other embracing all those which under ordinary
conditions are attached by means of a stem or pedicle, of greater or less length.

The former — the locomotive group — includes the larger number of genera,
ia all of which the cilia are more or less generally distributed over the entire
body. Their swimming movements are especially due to the ciha, but may be
aided by other tegumentaiy processes, by setae, styles, or unciai, and in several
instances by the general figure of the body. It is rare that swimming is a
simple onward movement ; on the contrary, it is usually attended with a
rotary motion about the long — seldom the short — axis of the body ; and when
the animalcule is considerably elongated, it becomes undulating, as in an eel.
In the case of Spirostomum (XXIV. 297, 298), the elongated ribbon-Kke
figure is particularly favourable to rapid wiithiag motion. In short, as before
intimated, the developement of the body to a greater extent in one or more
parts, so as to form processes, or the constriction of a portion, reducing it
to the dimensions of a member, or the lengthening of the entii'e animal into
a band-like or Ugnlate figure is made subservient to the purpose of locomo-
tion, and imparts to it a more or less special character. Moreover, the loco-
motive Ciliata have the power of altering the direction of their movements,
and will often retrace their course, and this frequently without turning them-
selves round in order to advance the same extremity foremost.

The simple movement of swimming is common to all the Ciliata ; but in
the case of those furnished with setse and uncini, a creeping or crawling
motion is superadded, as, for example, in StylonycMa (XXVIII. 10), Himan-
tophorus, Euplotes, and Kerona (XXV. 322, 328, 347, 353). In several
of these examples we find one side of the body covered with a more resistant
integument or shield, whilst the locomotive imcini or sette are disposed
along the other, just as in the case of a myriapodous insect, and supply a
locomotive apparatus whereby the animalcules can rim, with much activity,
over the surface of an Alga or other solid body, or climb it without difficulty.
The movements of the seta3, ia creeping, are not independent like those of
vibratile cilia, but are produced by the contraction of the substance into
which their bases are fixed.

Every microscopist has obseiwed Ciliata suddenly arrest their course and a.-;
qmckly reverse it. This phenomenon Pcrty calls ' diastropJiy and asserts
(op. dt. p. 122) that this change in movement is accompanied by such a
transition, that not only does the posterior extremity become, for the time, the
anterior, but it also acquii'es the size and appearance of the latter. There is,
in his language, an actual polar reversion of the organism. This peculiarity is
observed among the swimming, but not among the creeping Protozoa, whicli
always advance with the anterior end first. "\^Tien Paramecium versutum or
P, leucas becomes diastrophied, its figure elongates and changes to cylindrical

OF THE PROTOZOA. CILIATA.

289

— the present anterior portion (formerly the posterior) grows thicker, whilst
the opposite end becomes somewhat more pointed. For a few seconds the animal
swims about, revolving at the same time upon its long axis, and after sud-

i denly making a tm-n, reassumes its regular form and its usual movements.

; It is singular that the cilia of the reversed anterior extremity acquire a greater

i length and strength, and act with iucreased vigour, whilst those at the oppo-
site end become ruconspicuou* and passive. Diuing diastrophy, moreover,
rotation upon its long axis is particularly rapid. Perty illustrates this pecu-
liar act of diastrophy in many other species, of which we may mention Para-
mecium Col])oda, Colpoda Ben, Colejis hirtus, Occytricha PellioneUa, &c.

A very indifferent conception can be formed of the energetic ever-vai-ying
movements of the Ciliata by any attempted descriptions of their maimer
and direction. One method is combined with or rapidly exchanged for an-
other ; and we see the little beings not simply swimming, but revolving and
curving on themselves in a marvellous and beautiful manner, to be appre-

j ciated only by observation.

i Could we imagiae the existence of a will, or of a power of control, in
such tiny creatures, we should say that cUiary motion is at its bidding; we
see it incessantly varying in the same individual, both in activity and power,
at one moment urging on the moving atom at full force, at another merely
revolving it rapidly, at another slackened and presently stopped. These va-
riations, too, appear not fortuitous, but directed to certain ends — to the pro-
curing of food, to the avoiding of an obstacle, or to the escape fi'om an enemy.
Yet, on the one hand, the belief in the need of a special organization for the
manifestation of volition, and, on the other, the obsei'vation of very similar
movements in the ciliated cells of higher animals when detached and free in

; water, in the Phytozoa and in the spores and filiform cells of plants — are

\ circumstances which make us hesitate in attributing such phenomena to

I any other than purely physical forces.

\ "There is no sufficient reason," says Dr. Carpenter (' The Microscope,' p.
I 476), " to regard such actions as indicative of a wonderful adaptation, on the
I part of these simple ciliated cells, to a kind of life which enables them to go
in quest of their own nutriment, and to introduce it, when obtained, into the
interior of their bodies."

Prof. Owen remarks, in his lectiu'es on the Comparative Anatomy and Phy-
: siology of the Invertebrated Animals (1843), p. 19, — " If you watch the
1 motions of the Polygastric Infusoria, you will perceive they avoid obstacles
I to their progress, rarely jostle one another ; yet it is difficult to detect any

I definite cause or object of their movements." Further on, he mites " The

i motions of the Polygastrica have appeared to me, long watchiag them for indi-
cations of vohtion, to be in general of the nature of respii-atoiy acts, rather than
attempts to obtain food or avoid danger. Very seldom can they be constraed as
voluntaiy, but seem rather to be automatic — governed by the influence of sti-
muli -svithin or without the body, not felt, but reflected upon the contractile
fibre — and therefore are motions which never tire. "Wo may thus explain
the fact which Ehrenberg relates (not without an expression of siu-prisc),
namely, that at whatever period of the night he examined the living Infu-
soria, he invariably found them moving as actively as in the day-time • in
; short, it seemed to liim that these little beings never slept." '
; Turning now to the fixed Ciliata, we perceive that the true Vorticellina
ji not invested by an external sheath, arrange themselves under two sections'
according as the stem is flexible and contractile, or non-contractile and almost
. or completely inflexible. The genus Voriicella is the tyi>c of the contractile
group, and Epiatylis that of the non-contractile and inflexible. The stem

u

290

GENEBAX HISTOKY OF THE INFUSOEIA.

of the genus first named is always simple or unbranched (XXVII. 1, 2, 3, 4 ) ;
but in that of the other genera of Vorticdlina — viz. Carchesium (XXX. 9)
and Zootliamnium (XV. 69) of the contractile -stalked group, and Epistylis
and Opercularia of those having rigid stems (XXX. 1, 11) — the young beings
produced by fission continue adherent to the parent stem, and then proceed to
develope secondary branching pedicles of their own, and in this manner give
rise to compound ramified collections of polyparies. Since this ramification
is consequent on the division of a parent-being into two, it has necessarily
a more or less regular dichotomous (forked) character, and wiU be more com-
pound the oftener the process of fission has been repeated.

The stem produced by each half continues to acquire length and strength
until the being which surmounts it begins in its turn to undego self-division,
when its growth at once ceases ; and it undergoes no further change whilst it
exists, excejjt in acquiring increased consistence.

" The individuals on the same stem have," says Steia (p. 75), " as a rule,
similar dimensions, those undergoing fission, and therefore wider, excepted.
At times, indeed, one may be found smaller than its neighbours ; but this will
be traceable to some accidental circumstance, such as a less supply of nu-
triment to it, and is never very considerable. The size of the members of the
same colony agrees in general with that of the iadividual from which the
whole have spnmg. When the newly-developed fission-segment, after detach-
ing itself from its parent, forthvrith proceeds to fix itself and secrete its stalk,
the newly-developed colony will coincide in dimensions with that from which
this animalcule has proceeded. On the contrary, if the detached member
enjoys its freedom a longer time, appropriates nouiTshment, and attains a
larger growth, the new arborescent polypary developed from it will be larger
in aU respects than the parent colony. Hence it is, that in the same species
we have great variety in the dimensions of individual members as weU as of
colonies ; and therefore the height of the pedicle, the thickness of its branches,
and the size of its individuals are useless as specific characteristics."

The style of ramification is equally devoid of constancy in the same species :
for (to continue our extracts from Stein) " the several branches may attain
an equal elevation, and so produce a corjonb or cyme ; or the inner may out-
grow the outer branches, and the whole poly]3ary resemble a bunch of grapes
or a panicle ; or, as occasionally happens, the branches may be all incompletely
developed, but at the sarne time bear numerous individuals on short stems,
an-anged in close series on one side, when there wiU be a resemblance to an
car of com."

In the case of Ophrydium there is a considerable departure from the ordi-
nary structure and arrangement of the polj^aries of Vorticellina and the rest
of the Ophrydina. Elirenberg considered the globular masses of Ophryd'mm
to be constituted by the cohesion of their gelatinous sheaths, and to ho the
consequence of their incomplete soH-division. Tins, however, seems to be
incorrect ; for Stein (p. 246) confii-ms the statement of Frantzius, that the
gelatinous ball is not made up of coherent sheaths, but that the bodies of the
Ophrydia arc merely attached by their tapeiing posterior extremities to its
surface, and not imbedded within it. The animal sends, indeed, a prolonga-
tion of its tapering base some short way witliin the homogeneous matiix,
like a root ; and when it forcibly contracts itself, a slight depression of the
surface occurs ; but in no strict sense can the gelatinous excretion be called a
sheath or lorica.

Although, in their usual phase of being, the attached Ciliata have no power
of locomotion, they are nevertheless cajjable of considerable relative move-
ment. The highest degree of this is seen in the actively contractile stems of

OF THE PROTOZOA. CTLIATA.

291

Vorticella, CarcJmhim, and Zoothamniuni, and the lowest in the nearly sessile
Vaqimcola, and ia the rigid-stalked Episiylis. The movements of the stems
of Vorticellce are most astonishing by their activity and energy. _ In their
contraction, which is much quicker than extension, the pedicle is twisted into
a close spu-al comparable to a coiled spring ; and besides this action, by wliich
the animal is instantaneously drawn down to the point of attachment, the
; body itself shortens, and the cUiated head and appendages are retracted under
, cover of the general integimient. The branched pedicle of Zoothamnium is
I less actively contractile, although still capable of considerable movement,
i whilst that of OjJercularia and Epistylis is quite rigid, or very slightly
; flexible, and this in most species only in younger stems, before they are in-
j durated by age. In Opercularia herberina we have the most marked example
of flexibility of the stem among rigid-stalked genera.

Apart from the movements of the animacules dependent on their pedicles,
others are due to the contraction and elongation of their bodies, and to the
retraction and extension of their rotary apparatus. In the instance of Vagi-
I nicola (XXVII. 11), of CotJmmia (XXX. 12, 13, 14, 15), and of Tintimius,
these, indeed, are the only movements of which those genera are capable, — the
external sheath constituting of itself a safe house of defence when the ani-
malcule retreats within it, and thaa offering a compensatoiy provision in lieu
of the locomotive power of the freely-swimming Ciliata, or of the actively-
coihng spiral of Vorticella. On the other hand, when not in retreat, the ani-
j malcule outstretches itself, and, advancing its ciliated delicate head beyond
I the Hmit of the case (XXYII. 10, 11), expands its ciliary apparatus.

The animalcules fijced on rigid stems appear exposed to every passing
. danger without defence ; nature, however, has furnished them with a firm
i resistant integument within the anterior margin or peristom, of which they
. can completely retract the delicate rotary disc and ciliated head. However,
they are not positively motionless ; for a certain latitude of motion is allowed
them by theii" mode of articulation, and by the annular segmentation of the
posterior extremity (XXVII. 16), in addition to the possible contraction into
an ovoid or more or less globular figure. In Opercularia herheriformis the
contraction of the body is facilitated by the transverse rugae which normally
exist, — ^whilst in Ophrydium it is carried so far that the elongated figure be-
comes oval, and, the head being retracted, the animal presents itself as an
inconsiderable prominence above the sui-face of the gelatinous mass it rests
upon. The absence of a protecting sheath in this genus is partly compen-
sated for, further, by the aggregation of the Ophryclia, since the globose mass
produced is of itself a security, and is rendered still more so by its revolving
movements, the result of accidental external forces, and, we may suppose,
also by the activity of the animals projecting from its surface.

The Vorticellina and OplirycUna live as free beings for a certain time after
their production, whether by fission or by gemmation, or by internal gonns
i or embryos. In the case of the products by gemmation and fission, this
'i locomotive power is due to the temporary formation of a wreath of cilia be-
hind the posterior thii-d of the body, as mentioned in a preceding page ; and
it is curious that it is not then the head which moves in advance, but the
jl hinder extremity, by which attachment is to bo presently made. There
I seems to be an object in this backward progression ; for by it the animal is
: brought directly into contact with any object to which it can affix itself, and
I its attachment made more finn. The part to be attached is the first to come
into contact with the supporting medium ; and whether it proceeds to secrete
about itself a sheath, or to dcvelopo a peduncle, it finds itself rightly placed
without any revolution of the body.

TJ 2

292

OENKRAL HISTOHY OF TnH INFUSORIA.

Structure of Pedicles. — The intimato stincturo of the stem of the Vor-
tkellina is different in the contractile and in the rigid forms. The highly-
sensitive, contractile, simple pedicle of the genus Vorticella has challenged
especial study. It is evidently a compound stmcture, consisting of a hoUow
tube containing a cyhndiical band. The tube is a poition of the general
integument, and continuous with it ; in diameter it is unifoi-m thi-oughout,
except at its point of junction with the body, where it undergoes a very slight
expansion. Owing to the excessive rapidity of its spiral contraction, this act
can ■with difficulty be observed, except after the addition of a weak solution
of corrosive sublimate, wliich renders it so much slower that its progress may
be watched. Ultimately, indeed, the solution kills the animal.

The contained band, or, to borrow a term from general anatomy, the " axis-
cylinder," does not fill the cavity of the tube, bu.t is disposed within it in a
loose spiral manner. Opinion has been much divided as to the nature of
this structure. Ehrenberg, judging from its active contractility, pronounced
it a muscle, and went so far as to represent it as striated, i.e. as belonging to
the highest-developed condition of muscular tissue, which, however, com-
parative anatomy teaches us is absent in the lowest classes of animals. Many
other writers have united with Ehrenberg in considering the band muscular,
and some few also striated, whilst others, again, have regarded it as a simple
primitive contractile substance, less elevated than muscle proper in the range
of tissues. Indeed, when we contemplate the contractility exhibited by
certain plants, and can find nothing more than spiral vessels which can
be conceived the seat of this property, we are forced to admit that musculai-
tissue is not the only actively contractile element in organized bodies.

Stein, after remarking that the histology of the stem in Vorticella,
Garchesium, and Zoothamnium is essentially similar, proceeds to describe the
axis-cylinder as an opaque, solid, finely-granular mass, presenting delicate
longitudinal hues or stripes. In Vorticella nebulifera, V. convallaria, V.
Campanula, and in Garchesivm jpolypinum (XXX. 9), it extends into the body
as a single tapering band or streak, and in other VorticelUna in two such
diverging from one another, as remarked by Ehi-enberg, who concluded them
to be two muscular cords. When the stem contracts spii-ally, ti-ansverse lines
or stripes appear in the axis-matter, which are no other than cross folds, not
parallel, and most strongly marked on the concave side (XXX. 10) ; they
have therefore no homology with the transverse strife of muscle. That the
contractile power is dependent on the contained axis-cylinder is shown by
the facts, that where this is deficient at any part, as not mifrequently hap-
pens in Zoothamnium, that portion is rigid, as in Eiiisti/lis or Opercularia ;
that when destroyed by maceration, or by chemical agents, the stem is out-
stretched and remains immoveable ; and that, as is not seldom seen both in
Garchesium and Zoothamnium, this axis-matter may bo torn across, at one or
more parts, without the external sheath being injured : the contractility is
destroyed, except in that segment which is still in continuous union with the
body of the animal ; and generally the pedicle is only so far and so long con-
tractile as its axis-cylinder continues its imbroken connexion ^vith the body.

"Although," observes Stein (p. 80), "these phenomena are in favour of
the axis-matter being a muscle, yet there are othera sufficiently conclu-
sive against the notion. For instance, were the axis a muscle, its move-
ments should cease when it loosens its hold from the object it is affixed
to : but this, although asserted by Eckhard, docs not happen ; for when
Vorticellce and Garchesia relax their hold and swim freely about witli their
stems, these last are seen to actively contract in their usual spiral manner,
and presently again to extend themselves. In Uke manner Vorticellce, when

OF THE PllOTOZOA. CILIATA.

293

detached from theii- stems, alternately contract and extend their bodies ; and
yet no one pretends to see any distinct lines or bands in their interior to be
termed muscles."

Stein's conclusion therefore is, that the contained substance of the stalk of
the contractile VoHiceUina is not muscular, although it is the organ through
which the will of the animal is exercised over the pedicle. Ru'ther, as the
action of chemical reagents upon the enclosing tube or sheath of the pedicle
con-esponds with their action upon the cuticle of the body, so also is there a
similar correspondence, in chemical relations, between the axis-cylinder and
the internal tissue of the body.

Czermak, in his essay on the stem of Vorticellce (Zeitschr. iv. p. 442), describes
in that of Garchesimn three distinguishable structui'es: — 1, the hyaline
coloiu'less sheath ; 2, a yellowish contained fibre or band ; and 3, a finely-
granular fibre lyiag parallel to the last (XXX. 10). These three portions he
terms three isotropous helicoids, with reference to their spiral mode of con-
traction. Eckhard supposed the efi'ective cause of the contractility to consist
in the constant intimate connexion between the motions of the stem and
those of the body : but there is no such constant connexion ; for the cUiary
wreath may be retracted frequently without any contraction of the pedicle.
According to Czermak, the explanation of the movements is to be found in
the external hyaline fibre or tube being elastic, and tending naturally to keep
the stem outstretched, wHlst the yellow contained filament is contractile,
serving to throw the stem into folds, — the one consequently antagonistic to
the other. To the third or granular element, he is disposed to attribute only
a vegetative function. The elastic force of the stem is constant, whilst the
contractUe is momentary in operation ; the result of this, coupled with its
tiibular structm-e, afi'ords an explanation of the particular spiral mode of
contraction. This, Czermak has taken much pains to elucidate by reference
to physical laws, and an appeal to arguments which we deem unnecessaiy to
reproduce here.

More recently, the idea of the muscular nature of the axis-cylmder of
Vorticellce has been revived by Lachmann (op. cit. p 229), who does not
hesitate to call it a stem-muscle, and " cannot allow any value to Stein's
objection, that it stiU contracts even when the stem is not attached to another
object ; for the muscle does not thus loose its insertion, as it is attached to the
sheath of the stem itself by its hinder extremity, and not to the foreio^n obiect "
This reply to the objection seems perfectly admissible, although for our part
we do not at all perceive the necessity of regarding the axis-matter as muscle
in the exact sense of the term, even if it is in fimction homologous with that
compound tissue of higher annuals. A further statement made by Lachmann
is, that the muscular tissue of the stem extends upwards into the body where
it joins with the supposed muscular lamina lining the cortical layer '

TTie manner in which the axis-cyUnder is produced and disposed,' is shown
by Stein to afford a distinction between the allied genera Carchcsium and
Zoothamniitm. In the former, each branch dovelopes its own canal and' its
own central .substance, so that neither of them is directly continuous with the
canal or the contractile matter of those portions previously formed (XXX 9^ ■
in Zoothamnhim, on the contrary, both the sheath and the axis-cylinder of
the stalk are continuous throughout the ramified polypidom (XII G9) Tt
is in this genus, particidariy, that the oldest portion of the stem is often solid •
indeed imperfcctly-dcvclopcd stems occur, iji which after one or more cUvision^
thLS same solid and rigid condition is seen. Such varieties, as Stein uoints
out (op at. p. 218) are to a certain extent difficult to distinguish fromsnoc"es
of B^7Styh3; nevertheless they are never so rigid as the latter, but admit of

294

GENEEAl HI8X0BY OF THE INFUSOBIA.

being curved and are more elastic, and, besides all this, tbey exhibit trans-
verse folds or constrictions, of different depths, which are rendered still more
evident when the animals contract and shorten themselves upon their stems.

The rigid stems of Opercularia (XXX. 1) and Epistylis (XXX. 11) are
solid, without internal canal and contractile matter ; frequently they appear
finely striated longitudinally, and in several species (e. g. Opercularia articu-
lata) present transverse lines (XXX. 1), along which they more readily fracture.
These last are commonly described as articulations or joints ; but they occui- at
irregular distances, and are, even in the same species, neither constant in num-
ber, in distinctness, nor in distribution, and are consequently worthless in
specific descriptions.

The substance of these rigid stems is, however, not uniform, but divisible
into a cortical layer and an inner or medullary substance. This is manifest by
the fact of the transverse lines, which become more evident during the limited
undulating movements of the stem, penetrating only through its cuticle or
covering. " On the addition of concentrated sulphuric acid," says Stein (p.
112), " the pedicle swells up, and both longitudinal striae and transverse lines
or folds vanish, the whole mass appearing homogeneous and hyaline. Tincture
of iodine colours it yellow ; but sulphuric acid being added, it is again rendered
coloiuiess."

CoMPorarD Special Oegans of Locomotion and Peehension. The Peeistom

AlfD ROTAET OE CllIATED DiSK. ThE SpiEAiLY-COILED HEAD OF SpIEOCHONA.

— Before entering on the description of the internal organization of the Ciliated
Protozoa, there is one set of organs, belonging to the important genera Vorti-
cellina and Ophrydina (Ehr.), which demands our attention. The organs in
question are appurtenances of the head, and consist of a ciliary wreath and
a retractile ciliated disk.

Ehrenberg appears not to have recognized the existence of the ciliated disk
as a special structure ; for in his several generic descriptions of VorticeVdna
and Ophrydina, he speaks of the head as simply crowned by a wreath of
cilia, more prominent at one part, which he called the forehead, and inter-
rupted at one spot by a sort of gap where the oral aperture is placed. Stein's
researches, however, show clearly that the armature of the head, in most of the
genera of those families, is much more complex. The excepted genera are
Stentor, Triclwdina, Urocentrvm, and Tintinnus, which ai'e, in fact, not time
members of the family. Stentor fimiishes an example of the structure of
ciliary wreath, presumed by Ehrenberg to belong to all Vorticdlina, being
in fact a single line of cilia fringing the periphery of the head, and bending
down spii-aUy to the mouth (XXYIII. 16 ; XXIX. 7, 8). Triclmlina is
very curiously fringed with an anterior and posterior wi'cath of cOia, and
has besides a firm collar-like ring, within which is a cii-clet of stiff imcioi
(XXIX. 15, 16, 17).

In the genus Vorticella the apparatus is most simi)le ; it is slightly more
developed in Oplirydium and in Vaginkola, still more so in Epistylis, and
most of all in Opercularia and Lagenop)hrys ; lastly, in Spirochona, Ghcetospira,
and Lagotia, totally exceptional forms occur. When examined closely,
Lachmann says (A. N. H. 1857, xix. p. 118), we find the wreath is a spii-al,
and not a complete circle (XXIX. 1, 2, 3, 4, 7). It begins in the vicinity
of the orifice of the vestibule, nms above it towards the left, and round the
margin of the ciliary disk; but before it again reaches its starting-point,
it descends, upon the stem of the rotary organ, into the commencement of
the digestive apparatus («. e. the vestibulum) .... The portion of the ciliary
spiral, which is outside the vestibulum, is not of equal length in all^ Vortkd-
Una ; in many — Vorticella, Carchesium, ZootJiamnium, Scyphidia (XXIX. 3),

OF THE PROTOZOA. CILIATA.

295

Trichodina (XXIX. 15, 17), some species of Epistylis, &c.— it scarcely de-
scribes more than one circuit roimd the disk, whilst in Ojpercularia articulata
and Epistylis jlavkans it nms roimd the disk three times, and ia other forms
the length lies between these two extremes. This portion consists of a double
row of cilia ; those of the outer row are usually somewhat shoi-ter than those
of the inner, and inserted upon the ciliaiy disk nearly in the same Une, but at a
different angle, as they appear to be far. more strongly bent outwards. In
the vestibulum and oesophagus the cilia appear to stand in a single row.
The peristom bears no cilia ; those represented upon it by Stein belong to the
outer series of cilia of the disk, or to that portion of the spiral which descends,
on the stem of the rotatory organ, into the vestibulum. The latter also,
perhaps in conjunction with the bristle above mentioned, appear to have been
what indiiced Ehrenberg to suppose the existence of a fi'iUed lower lip in
Epistylis nutans, and Stein in all the Opercular'm.

" To see the pai'ticulars above described, it is peculiarly advantageous to
observe animals which have died during expansion."

In Voriicella (XXVII. 1, 2, 4 ; XXIX. 1) we have a truncate anterior ex-
tremity, the margin of which, i. e. the peristom, is ciliated, expanded, and
often rather roUed outwards, and has within and rising slightly above it the
rotary or ciliated disk. This is separated by a fissure from the peristom
(XXVII. 1, 2), except at one part, where the two are continuous, and on
examination the disk, with its supporting stem narrowing downwards and
outwards obliquely into the body, appears to be a fold reflected from the
inner margin and surface of the peiistom. The mouth opens at the bottom
of the fissure or cavity (the vestibultmi), and is furnished with several cilia.
The ciUated disk when outstretched is elevated a little above the peristom,
but can be retracted and covered in by it completely. The peristom, like-
wise, can so curve itself iawards as to include its own ciUa within the ring
of integument which closes over, like a sphincter, the whole ciliary ap-
paratus of the head. The rotary disk has some general resemblance to
a cork or plug, which can be drawn inwards by the animalcule itself, or
pushed outwards, so as to serve, by its ciliated margin, to produce a vortex in
the fluid, and thereby fulfil the pui'pose of a prehensile or pui-veying organ,
in addition to its locomotive power when the Vorticella is free. The tapering
biisis of the disk ends below ia the general cavity of the body, and is held in
situ by its retractor fibres, which proceed to it from the sides of the animal-
cule posteriorly. Its interior is continuous with the general cavity of the body.

The unfolding of the ciliary apparatus of the head is more gradual than the
retraction ; and, so to speak, the animal seems to feel its way by first everting
a portion of its dcUcate peristom (according to our own observation, in a sinuous
manner) along with a few of its stronger cUia, before expanding the rest.

In Ophrydium (XXX. 5), the disk is rather more convex on its sm-facc,
and advances somewhat higher above the peristom, but in all essential parti-
ciilars resembles that of Vorticella. On the retraction of the disk, the peri-
stom contracts above it into a short cylinder, and the head swells out in a
globose manner (XXX. 6). Between Ophrydium and Vaghiicola (XXVII.
11) there is a close resemblance in the conformation of tlio ciliated organs
except that, in the latter, the act of retraction agrees rather with that of
Vorticella than with Ophrydium.

A truncated, thickened, somewhat everted peristom, fringed mtli cilia
(this Lachmann denies, see above), belongs to Epist^ilis (XXX. 11) as well as
to the above-named genera, and to Garchesium (XXX. 9) and Zoothamnium
It has also a similar rotary disk, only rather more developed, and its stem
short and thick.

296

GENEKAL HISTOEY OF tHE INFUSOHIA.

In Opercularia, on the contrary, the peristom is neither ciliated, expanded,
nor everted in a campanulate manner, but, by the tapering of the anterior
thii'd of the body, is narrow (XXX. 1, 37), and frequently throw into longi-
tudinal rugse, and withal simply truncate. Further, the disk has a flat
sou-face, and is supported on a long stem which tapers internally to a fine
extremity ; and the whole organ assumes a trumpet-like figure (XXX. 1 a,
2 a, d). Moreover, instead of an infundibuhform fissure conducting to an
oral aperture or entrance to the alimentary canal, there is a wide throat or
pharynx, occujtying almost the whole diameter of the peristom, having its
border extended upwards in the form of a free edge (XXX. 2, 3), which
Stein calls an under Hp, in contradistinction to the rotary disk, which Ehren-
berg represented to be a forehead and upper lip.

The tapering stem of the disk bounds one side (the upper) of the pharynx,
and by its narrow extremity communicates with the general cavity of the
body. The flat disk itself is surrounded by two or three concentric rows of
long cilia, and when drawn inwards suffices, with little aid from the constric-
tion of the peristom, to close that opening. When, however, contraction is
more forcible and complete, this process is entii-ely retracted, and the peristom
closed above it (XXX. 37). When in this condition — and this is true also of
the other allied genera, — the only indication, as before mentioned, of the
ciliary apparatus of the head is an irregularly-shaped streak or space, in
which cilia may still be discerned. This iiTegular space is nothing more
than the remnant of the pharyngeal cavity not occupied by the retracted
organs.

On the retraction of the rotary disk a portion of its contents is transfeiTcd
from the expanded free extremi^ into its stem, the quantity so removed being
in direct ratio with the degree of contraction ; when tliis is considerable the
trumpet-Kke process appears like a mere internal lobe (XXX. 37 b, /i).

In Lagenophrys the peristom is pecuHar in being adherent to the narrow
two-lipped aperture of the ' sheath ; the diameter of the two orifices is
consequently equal. From the peristom a long tmmpet-shaped rotary organ
projects, similar to that of Opercularia (XXX. 29, 32, 33, 34).

The most singular conformation of the head occurs in a now member of
the VorticelUna, described and figiu-ed in Stein's admirable monograjA (p. 205)
under the name of Spirocliona (XXX. 17, 27, 28). In this the ordinaiy struc-
tiu'e of the head is entirely departed fi-om ; and we have in its place a con-
voluted spiral membrane or lameUa, rolled inwards around a sohd central
axis, forming a sort of exaggeration of the single spii'al wi-eath of Stentor.
In full-grown specimens of Spir. gemmipara, two complete circuits (XXX.
17) are made by the lameUa, each of wliich is morpliologicaUy the same as
the ciliated peristom expanded and flattened out. The smiacc is clothed
with cilia ; and at its termination in the body, near the axis of the spu-al, is
placed the mouth, into which foreign substances are rapidly transmitted by
the action of the cilia.

Among the several members of the families passed in review, we have seen
a considerable range in the complexity of the ciUaiy wreath ; and on extending
our examination to other genera, intermediate gradations in structtire may
be discovered. Thus, through the simple sjurally-curvcd wreath of Stentor
(XXIX. 7), we have a connecting link between VorticcUa, on the one hand, and
several genera, of wliich, in respect of the ciliary arraatiu-c of the head,
Trichodinn may be taken a.s tlic representative.

ChaUospirn, a new genus instituted by Lachmann {A. N. H. 1857, xix.),
has a cihary apparatus so abnornud and pocidiar, tliat it would seem rather a
representative of another family than one of the VorticelUna. The anterior

OF THE PKOTOZOA. CILIATA.

297

portion of the body is much elongated, and supports a ciliated process, when
fully extended, straight and of a sword-shaped figure, fringed along one side
and at the end with cilia (XXIX. 5) ; but when in active vibration and twiii-
ing the animalcide onward ia a spii-al manner, the greater part of this cUiated
process becomes curved like a sickle (XXIX. 6).

Another bizarre form of cihaiy apparatus is exhibited by the genus Lagotia,
described by Dr. Strethill Wright as a member of the family Ophryclina.
The head of this animal protrudes a pair of horn-lLke divergent processes,
fringed around with ciha, flat or folded longitudinally, and straight or recui'ved
at the extremities. These ciliated appendages, together with the elongated
body they surmoimt, enjoy a very great latitude of motion by alternate con-
traction and extension, and by curving and twisting in different directions.
The mouth lies in the angle between the processes. The whole being may be
said to stand in a position, -with regard to the rest of the Vorticellina and
Ophrydina, similar to that of Stephamceros to the other Rotatoria.

INTERNAL ORGANIZATION OF THE CILIATED PROTOZOA.

SuBTEGUMENTAEY LATEB ; Chloeophtll ; Theead-cells ; MtTSCLES. — Sub-
jacent to the cuticle is a layer of granules and smaU. globules, which is
often spoken of as a second lamina, just as the cutis vera in higher animals
is of the cuticle. Its thickness is considerable ; it is hyaline, and more con-
sistent than the contents, and, although homogeneous itself, contains a multi-
tude of granules, and, at least in several genera {e. g. Paramecium, Ophryclium,
Nassula), numerous chlorophyll- vesicles, often so thickly disposed as to impart
a lighter or deeper green coloiu- to the animal (XXIX. 28). In young, and
also in very old, specimens this colouring-matter is wanting, and only colour-
less granules with a dark outline, resembUng small fat-particles, present.

In Mr. Carter's phraseology this cortical lamina bears the name of the
" diaphane," and is said to lie beneath the " pellicula," but not to be secreted
from it. The property of contractihty resides in it, whence it becomes so
far analogous to the muscle or flesh of animals, that to it the term ' sai-code '
may most appropriately be applied. Dujardin, however, who fij-st employed
this term, did so to desig-aate the entire component organic mass of Protozoa •
but as later observers seem to make out the presence of a somewhat dis-
similar substance, of a much looser and more mucilaginous consistence sui'-
rounded by the contractile layer in question — in other words, within the
so-called abdominal cavity — we feel quite justified in limiting its signification
as we have done.

That the cortical layer alone is contractile, Lachmann considers {A. N. H.
1857, xix. p. 126) to bo shown by the fact, that " in torn Infusoria fragments
of it not imfi-equcntly contract, whilst the internal mass, the ' chyme,°which
flows out, never does so." Its contractions eftbct tiie various alterations in
the figure of animalcides, whilst by its greater consistence compared Avith the
abdominal contents, and its fixity as a layer subjacent to the cuticle, it affords
a surface, and even a nidus, for the attachment of the nucleus and contractile
vesicle, which it therefore serves to retain in situ, notwithstandin"- the
opposmg forces of the circulatoiy current and of particles of food propelled
against them (see section on Circulation). To demonstrate this qiucsccnt
cortical lamina and the inner moving stratum also, chromic acid affords the
most effective means.

The cavity enclosed by the cuticle and subjacent cortical lamina is occupied
by an almost fluid matter, for wliich the term " abdominal mucus " is suo-o^ested
by Carter, and that of "chyme" by Lachmann, the former wo cstcGn/thc
better, although it impcrfcctiy represents the actual state of things • for in

298

GENEUAL HISTORY OF TILE INFUSOBIA.

these central almost fluid contents, two portions are dLstinguishablc — one
occm-iing as a stream moving around the animalcule, within and upon the
cortical lamina, the other as a thinner central medium, apparently (juiescent,
and in direct communication with the surrounding water through the channel
of the alimentary tube and mouth. To the first only of these two portions
Lachmann's term ' chyme ' is rightly applicable, since it no doubt represents
the nixtritive material drawn from the alimentary matters swallowed, and to
the elaboration of which the watery fluid of the centre most likely contributes.
Both portions contain food- vesicles, granules, and molecules ; but the former
possesses them in much greater abundance. When an animalcule dies, the
central contents are the fii'st to escape, streaming forth fi-om the mouth as a
diffluent film with granules and molecules imbedded in it ; a similar discharge
and " diffluence " also ensue when the protecting envelopes are torn through,
and the more so when some pressm-e is at the same time exerted.

The follovraig quotation from Lachmann elucidates very well several points
concerning the contents of the body in general. " When," he writes {op. cit.
p. 126), " an Infusorium is sucked out by an Acineta, the cortical layer or
parenchyma of the body may often contract for a long time, and the con-
tractile vesicle placed in it may also continue its contractions for houi's ; nay,
I have observed a StylonycMa, which, although a considerable part of its
chyme had been sucked out of it by an Acineta, stiD. imderwent division, so
that one of the gemmules of division swam away from it briskly, and only
the other half of the old animal was destroyed. This appears also, to a cer-
tain extent, to prove that the mass sucked out does not represent the true
parenchyma of the body ; and as it only fills the large cavity of the body in
the form of a tenacious fluid mass, and becomes mixed with the nutritive
matters, especially when no small masses are formed, it is certainly the most
natural course to regard it as chyme. It cannot be urged against this view,
that in those Infusoria which contain chloroj)hyll-corpuscles in the substance
of their bodies, we sometimes meet with single corpuscles in the rotating
mass, as they may certainly be easily loosened from the parenchyma, and
thus get into the chyme-mass. The nucleus, indeed, projects into the chyme-
mass ; but as a general rule it appears to be affixed to the parenchyma of
the body, as we do not see it rotate with the chyme-mass : in Opei'cuJaria
bei-berina, Stein sometimes saw the nucleus moved a little out of its previous
position by a mass of food stiiking against it ; but as it soon returned again
to its position, this rather speaks for than against its attachment."

Imbedded within the cortical layer a collection of remai'kable structures is
discoverable in many species — for instance, in Parainecmm, OphrnogJcna, and
Bursaria — kno'wn under the name of thread- cells or trichocysts (XXXI. 1-4).
We are indebted to Prof. Allman for the minute and complete examination of
these bodies {J. M. S. 1855, iii. p. 177). He behoves it was these structures
which Cohn represented (as mentioned in a pre\ious page) to be exceedingly
long cilia, and which Stein, in criticising Cohn's account, aflirms to be cUia of
ordinary length, but appearing abnormally lengthened under external circum-
stances, such as the addition of strong acetic acid. Prof. Allman's description
is the best we have : —

"When Bursaria leucas is examined under a sufficiently high power,
minute fusiform bodies may be detected tliicldy imbedded in its walls.
These bodies are perfectly colourless and transparent ; they arc about the
■j^th of an inch long, and may easily, oven without any manipulation, bo
witnessed at the margin, where they are scon to be arranged pcq)cndicidarly
to tho outline of the animalcule, while on the surface turned towai-ds the
observer the extreme transparency and want of coloui* render them invisible

OF THE PROTOZOA. CILIATA.

299

against the opaque background, and it becomes necessary to crush the
animalcule beneath the covering glass, so as to press out the green globules
which it contains, in order to bring the fusiform bodies into view. To these
bodies I propose to give the name of trichocysts.

" As long as the animalcule continues free from annoyance, the trichocysts
undergo no change ; but when subjected to external ii-ritation, as occurs dming
the drying away of the surrounding water, or the application of acetic acid
or other chemical irritant, or the too forcible action of the compressor, they
become suddenly transformed into long filaments, which are projected from
j all parts of the surface of the animalcule ; and it is these filaments which,
being mistaken for ciHa by Cohn and Steiu, gave rise to the erroneous views
just mentioned.

" The rapidity with which this remarkable change is effected, joined with
the great minuteness and transparency of the object, renders it extremely
difficult to follow it ; and for a long time I could only satisfy myself of the
fact that the fusiform bodies were suddenly replaced by the projected fila-
ments. After continued observation, however, I at last succeeded in wit-
nessing the principal steps in the evolution of the filament.

" It is not difficult, by rapidly crushrug the animalcide, to force out some
of the trichocysts in an unchanged state. If the eye be now fixed on one of
the isolated trichocysts, it will most probably be seen after the lapse of a few
seconds to become all at once changed with a peculiar jerk, as if by the sudden
release of some previous state of tension, iato a little spherical body. In this
condition it wOl probably remain for two or three seconds longer, and then a
spiral filament will become rapidly evolved from the sphere, apparently by
the rupture of a membrane which had previously confined it, the filament
unrolling itself so quickly that the eye can scarcely follow it, until it ulti-
! mately lies straight and rigid on the field of the microscope, looking like a
1 very fine and long acicular crystal.

" This remarkable body, when completely evolved, consists of two portions
— a rigid spiculum-like portion acutely poiuted at one end, and continuous
at the opposite end with the second portion, which is in the form of an ex-
cessively fijie filiform appendage less than half the length of the spiculum :
this second portion is generally seen to be bent at an angle on the fii-st, and
is frequently more or less ciu'ved at the free end. The form of the evolved
trichocysts is best observed in such as have floated away towards the mai-"-ia
of the drop of water, and are there left dxy by the evaporated fluid. °In
many of them the filiform appendage was not visible ; and they then merely
presented the appearance of a simple, long, fusiform spiculum.
j " The resemblance of the organs now described, to the weU-known thread-
I cells of the Polypes and of certain other lower members of the animal Idnw-
! dom, is obvious. That they are entii-ely homologous, however, mth these
1 bodies we can scarcely jet assert. Their origin, at least, appears to be
I different ; for, if we admit the unicellular stnictiu-o of the Infusoria, we have
the trichocysts apparently developed in the substance of the ceU-wall, instead
of being produced in special cells, as we know to be the case with the' thread-
cells of the Polypes."

These structures have also arrested the attention of Oscax Schmidt
Leuckart, and Lachmann. The second-named observer surmised tliem to
1 be " poison organs ; " and very probably they have a defensive purpose for this
i is suggested both by AUman's liistory of them, and by Lachmann's obsorva
i tions (02). cit. p. 126, in foot-note) "of similar, but much tliickcr corpuscles
I which presented a deceptive resemblance to the urticating organs of the
Gampanularm, in an animal living as a parasite " upon iuflinduals of that

300

GENERAL HISTORY OF THE rNFUSOBIA,

family of Polypes, and " which is probably to be referred to the Acinethia ....
In the oval embryos, cUiated on one side, which were squeezed out of the body
of the mother, we were enabled to convince ourselves that these corpuscles
were enclosed, from two to nine together, in a roundish proper vesicle " (cell).

Muscles. — Ehrenberg presumed the existence of internal muscles, to ex-
plain the varied and active movements of the CUiata, — a presumption required
by his hypothesis of the repetition of the organization of higher animals in all
lower forms, but entirely unwarranted by analogy. Dujardin considered the
whole bulli of the body to be composed of ' sarcode,' having an inherent con-
tractihty, and the source of all the movements. Little doubt can exist that
the cortical lamina is the seat of contractility, — not that it is muscular on this
account, but that, as animal tissue in its simplest condition, it possesses the
property of contractility as one of the characteristics of such tissue, along
with others, such as sensibility, all which, in highly-organized animals, have
severally their special stracture elaborated for theii* more complete operation
and independent action. In short, in the language of physiologists, the
tissues in more perfect animals are differentiated, in the lowest are not so.

This physiological fact being admitted, the existence of nerve-fibres and of
nervous centres, or ganglions, can be no more than imaginary. The same
follows of the supposed organ of sense, the so-called eye of Olenodinium,
which many have concluded to be homologous with the coloured specks of
Protozoa, of Euglena, and the like. Lieberkiihn's obsei'vations would lead,
however, to the conclusion that the eye-speck of Opliryoglena rightly deserved
that epithet, and is something more than a pigment-spot. His account of it
runs thus {A. N. H, 1856, xviii. p. 321) : — " Close by the oral slit, on its
concave side, lies the pigment-spot. Its form is extremely iiTegular, some-
times globular, sometimes ellipsoidal, in many cases toothed. Ordinarily it
is so distinct as to be at once perceived ; sometimes, however, it is so small
that it can only be detected by close examination. In animalcules filled mth
strongly -refracting substances alone, it is always difficult to discover it. The
pigment-spot of Ophryoglena atra has, on the whole, more imiformity of form
and magnitude. If we squeeze down an Opliryogle^ia jlavicans between the
coveiing glass and the slider, we find that the pigment-spot is composed of a
heap of minute, scarcely measurable granules, strongly refracting hght. I
never could discover a lens in the pigment. AU the specimens examined by
me possessed but a single pigment-spot. Beside this hes alwa^-s a hitherto
unobserved stnicture, the fonn of which is perfectly described when we call it
a watch-glass on a small scale. This watch-glass-like organ is transparent
and colourless, and shows no trace of fibrous or any other stractiu-e. The
circular base has a diameter of about j^th of a millimetre ; its depth
amounts to about a thu-d part of this diameter ; the convexity is veiy con-
siderable. The watch-glass-shaped organ usually turns its convex side
towards the pigment-spot ; its concave side is directed towards the point of
the head ; it does not seem to be moveable by the animalcule. "NAlicn isolated,
it withstands the action of water for a longer time than is usually the case
with the other parts of the body of tliis Infusorium. After lying some time
in water, it swells up in some degree, and frequently becomes perforated by
a hole in the middle. The presence of the watch-glass-shaped organ is not
dependent on the presence of a pigment-spot ; for Ophnjoglfna atra possesses
a pigmont-spot, but no watch-glass-shaped organ, while Biirsaria f<iya has
a watch-glass-shaped organ, but no pigiucnt-spot. In other Infusoria ^rith
ej^c-spots, as in the Evglom and Peridhiia'a, I have sought in vain for this
organ. I have not met with any facts throwing light on its function."

Notwithstanding, in the interior of the Ciliated Protozoa there is not nn

OF THE PBOTOZOA. CILIATA.

301

actual homogeneit}' of tissue. The act of diftbrcntiation is carried so far that
certain distinct organs and parts become distinguishable. Thus there is a
mouth or oral oiifice for the entrance of food, succeeded by a dilated cavity —
an oesophagus or phaiynx, which is contracted posteriorly into a tubular
prolongation of various length, homologous with a digestive or alimentary
lube. Apart fi'om this radimentary aUmentary apparatus, mimerous globular
or vesicular spaces containing granular particles or objects evidently swallowed,
are met with in the general loose contents of the body ; these were the di-
gestive sacs, or stomach-vesicles, so much insisted upon by Ehrenberg ; other
included organs are the contractile vesicle, a certain striated cylindrical organ
in one or two genera described by Ehrenberg as a dental cylinder or teeth,
the nucleus with usually its nucleohis, the red speck (eye) in Ophryoglena,
and in one genus a pair of organs imagined by Stein to be glandular. To
these contents Carter adds spermatozoida, and Perty internal germs or ovules.

We have ah'eady mentioned chlorophyll-corpuscles in some genera, and
the general prevalence of fat-vesicles and granules interspersed within the
substance of the body, or collected into a layer as in several of the Vorti-
cellina ; the collection of fat-corpuscles is remarkable in the contracted portion
or base above the point of attachment, whether this be by a pedicle or not.
" Perhaps," he adds, " the transverse annulations which are exhibited by the
bodies of some Vorticellina are to be attributed to muscular fibres ; at nil
events they do not belong to the skin, but to the parenchyma (i. e. the cor-
tical lamina) of the body."

Lately, Lachmann has broached the hypothesis that an actual muscular stra-
tum lies within the cortical layer. He writes {A. N. H. 1857, xix. p. 228) — " I
was so fortunate, in common with my friend Claparede, as to observe an indu-
bitable separate contractile layer, in which longitudinal striae were generally
to be detected in various Vorticellina, in which Ehrenberg states that he saw
muscular striae at the posterior extremity. It forms a hoUow cone, the apex of
which is situated in the hinder extremity of the animal, and, in the contrac-
tile-stemmed species, is produced into the muscle of the stem : in its apparent
section it of course appears like two small fibres separating from each other
Hke a fork — as which, indeed, it has hitherto been always regarded, except
by Ehrenberg. This layer is very beautifully seen in Epistylis plicatilis, in
which we may most completely convince ourselves that it is a special stratum,
which possesses contractility. In Epistylis plicatilis, namely, dui-ing the con-
traction of this stratiun, the non-contractile part of the parench^a which
surrounds it, with the sldn covering it, separates from the contractile layer,
and forms the well-known folds, whilst the contractile or muscular layer be-
comes shortened and thickened without folding."

Ohoaits of Digestion, Nutrition, and Sechetion.— To take the several parts
or organs in succession, we wiU first consider those concerned in the processes
of digestion and nutrition, beginning with the oral oiifice or mouth. This is
variously situated in different CUiata, its position having reference to the fio-ure
and the mode of life, and being generally indicated by the particular piwd-
sion made to secure a proper cuiTcnt of water into it, such as a tuft, a curved
row, or a circlet of larger cilia, a process or a depression of tiie body, the axis
of a convolution of the sm-face, and the like. Thus in Lacrymana, Enchcl'iis
Prorodon, Coleps, &c., it is at the anterior narrower extremity ; in 'I'rachelLs
and AmpUleptus it has a similar position, but is besides under cover of a
process of the body. In CModon a stiU larger segment surmounts it; in
Nasstda, Parameaum (XXIX. 28), and in Pletironema (Dui ) it is lateral •
and lastly among the Vorticellina it is within an involution of the intesni'
ment of the head, called the ' vestibulum,' on one side of the ciliated Isk

302

GENEBAL UISTOHT OF THE INFUSOEIA.

(XXX. 1,2). Tho opening of this vestibule or ante-room to the entrance of
the digestive tube, i. e. the mouth, should not be confoimded with the latter,
as often has been done. A funnel-hlce hollow having the time oral aperture
at its bottom, is met with in Parmnedum, and may have the same appellation
extended to it. Among the processes about the mouth facilitating the inglu-
tition of food, we have just aUuded to the wreaths, rows, and tufts of cUia,
mostly lai'ge and strong like bristles, and to special developments of the sur-
face of the body. Several species possess a tuft of cilia almost indistinguish-
able from a plaited membrane ; for instance, Colpoda Cucullus (XXIX. 37)
and Chilodon Cucullulm have what Ehrenberg called a tongue, but which, as
we have seen, Stein has resolved iato a thick pencil of ciliary bristles. A
similar structure prevails in Pleuronema and Alyscum (Duj.), in Cyclidium
and Aphthonia (Perty). In Glaucoma (XXVIII. 4) and Cyclidium marga-
ritaceum, " the margins of the buccal orifice appear," says Lachmann (ojj. cit.
p. 216), "to be produced into two valves which are ia constant motion." A
special curved or spirally- turned row of cUia directs a current into the mouth
in Stentor, Spirostomum, Bursaria, Olmtospira (XXIX. 5, 6), Oxytrichhut,
Euplotes, and Aspidiscina, and a nearly straight row in Cliilodon and Colpoda.
In Coleps, TracJielius, Enclielys, and Trachelocerca, the mouth opens imme-
diately upon the surface without any conducting cUiary channel, and is sur-
rounded by a simple circle of ciha. The mouth is protrusible in Prorodon and
Nassula (XXVIII. 8, 65), and not distinguished by any special external aiTay
of cilia. In the true Vorticellina and in the Ophrydina, as above mentioned,
the complex ciliary apparatus directs the current into a cavity, the vestibu-
lum common to both the mouth and anus ; and lastly, in Paramecium the
cilia are uniform at aU parts, and the course of food to the mouth provided
for by a wide and deep tapering channel. In size the mouth varies both in
different genera and in relation to the dimensions of the animals ; but in aU it
is more or less extensile, so that foreign particles or other animalcules are
engulfed within it even when their diameter equals that of the body itself.

The oral aperture opens below into a rudimentary digestive tube (XXVII.
1, 10, 11 ; XXIX. 4 ; XXX. 1, 11, 29), formed by an involution of the ex-
ternal integument. It is commonly a fimnel-shaped space, which, for the
sake of a name, may be called the pharynx or digestive tube ; within this,
and especially near its entrance, a few vibratile cilia ai'e mostly seen, serving
by their action to accelerate the onward transmission of the particles of food.
The walls of this cavity are formed by a special very extensile membrane,
which, as supporting the internal cUia, may be called a 'basement mem-
brane.' The pharynx extends (as a gently tapering, mostly cm-ved, tube)
obliquely inwards towards the centre of the general cavity of the body, where
it abruptly ends. Its length is subject to considerable vaiiation in different
genera. In Paramecium and allied genera, and in Oxytrichina, it is short and
of greater relative width ; in Cliilodon, Nassula, Prorodon, and others it is
continued, from the posterior extremity of the so-called cylinder of teeth, far
into the interior. It is also of very considerable length in the Vorticdlitm
generally, as illustrated by Epistylis and OperculaHa (XXX. 1).

" In Ehrenberg's famiUes," Lachmann tells us {op. cit. p. 217), " O.i-yin-
cJiina, Eivplotes, and Aspidiscina (as also in Stentor, Bursaria, and Sjyirosto-
mum), we meet with an internally ciliated oesophagus, and a curved Hne
open towards the right, composed of strong cilia leading to the mouth." Tliis
oisophagus always forms " an open tube, and is often collapsed at its inner
extremity, and thus forms a transition to the oesophagus of the following
groups.

" Many Infusoria," he continues, " have a completely collapsed oesophagus,

OF THE PROTOZOA. CILIATA.

303

wliich, as forming a tube distinct from tlic parenchyma of the body, and
hanging freely in the alimentaiy cavity, is perhaps entirely wanting in some
species ; at least, I have hitherto been unable to detect it ia Anvphileptus,
most species of Trachelms, Enclielys, Coleps, and Trachelocerca, in which it
only appeared to be a canal thi'ough the parenchyma of the body : and these
are generally incapable of forrdng roundish morsels like the species hitherto
imder consideration ; but they usually swallow larger particles, which then
pass separately into the cavity of the body, often even without being accom-
panied by water. It is very difficult to determine whether the oesophagus of
these animals is furnished internally with cilia. In some, such as Coleps,
this almost appears to be the case : these swim to any slimy mass, such as a
deliquescent Infusoriiun, press the anterior extremity of the body against it,
and open the mouth and oesophagus, which are usually closed, so as to form
a wide canal ; the mass lying before the Coleps then passes through this canal
into the interior of its body, apparently without any swallowing movements
on its part, so that it can hardly be driven in except by ciliary action. In
others, on the contrary, the cUia of the oesophagus appear to be wanting, as
in AmpMleptus, Enchelys, Trachelius ; these perfonn regular movements of
deglutition, in order to overcome their prey, which usually consists of Infu-
soria of tolerable size : they push themselves, as it were, with swallowing
motions, like the Snakes, over theii" prey (so that they can very rarely be fed
with coloui') ; and this never forms stomach-Kke morsels, except when it is
contained in this form in the Infusoria devoured."

Stomach-sacs. The Polt&asteic Hypothesis. — The next organs, con-
cerned with digestion, to be considered, are the stomach-sacs or vesicles of
Ehrenberg— the "digestive globules" of Mr. Carter (XXYIII. 8/). The
former has described these to be disposed after certain definite types, which
form the basis of his system of classiiication of the Polygastrica. To describe
these tyi^es, we must premise that the families comprised in our group of
Ciliated Protozoa represent the Enterodela of the Berlin naturalist, or those
Polygastrica having a true alimentary canal uniting the stomach-sacs together,
and continuous throughout from the mouth to the assumed discharging orifice.
The Enterodela were subdivided into sections according to the relative posi-
tions of the moiith and anus. The first of these was named Anopisthia, in
which the intestine was so curved upon itself that its two extremities were
conterminous in one aperture, which therefore served the double ofiice of a
receiving- and a discharging- orifice. This curvatiu'e of the intestine fiu-ther
suggested the term Cydocoela to express it. The families in this section were
Vorticellina and Ophrydina. The next section, called Enantiotreta, included
animalcules in which the oral and the anal apertures wore at opposite ends of
the body. When this was the case, the intestine might cither pass straight
between the openings, or be more or less twisted in its coiu-se : in the former
case, the Polygastrica were called Orthoccela ; in the latter, Campylocosln.
The EncJielia and Colepina were the two families of Enantiotreta. The third
section was the Allotreta, having one orifice terminal, and the other lateral
and the fourth the Catotreta, having the two orifices on the same side not
terminal but abdominal. The members of these two last sections, lastly 'had
either a straight or, more commonly, a contorted intestine, or, in other words
were either Orthoccela or Campyloccela. '
r.^^^^\ 'I ""^^ of Ehi-cnberg's views of the alimentary apparatus of the

Ciliated Protozoa, as advanced in his great work of 1838, and never since re-
caUed. rhey rested chiefly on some imperfect observations and experiments
made with coloured food, and have failed to bo confinncd in the hands of
other microscopists. Although cUligently sought after, no one has been able

304

GENEEAL HISTOEY OF THE INFU80J1IA.

to demonstrate the intestine connecting together the several gastric ca^dties ;
and what is of more weight than the absence of direct evidence, are certain
facts subversive of the notion that any such tube exists, — viz. the irregularity
in the course talien by the bolus of food when transmitted into the interior ; the
intermingling of the first- and last-swallowed morsels; the movements hither
and thither, and the actual rotation within the interior of the globules called
stomach-sacs ; the occasional coalescence of these sacs, and the not infi-equent
occm-rence internally of frustules of Diatomece and joints of various micro-
scopic Algae of great relative length to the animalcule (XXVIII. 31) — some-
times, indeed, so long as to stretch the soft body itself (XXVIII. 1). On the
strength of these facts, coupled with the absence of demonstrative evidence
of its truth, the polygastric theory, and the system of classification founded
upon it, have together been all but universally rejected.

Meyen was one of the first seriously to examine the statements of Ehi-en-
berg : his conclusions were quoted at large in our last edition. He rejected
the polygastric hj^pothesis because he failed to discover the connecting intes-
tinal tube represented by Ehrenberg, and, on the other hand, detected the
rotation and coalescence of the assumed stomachs. His views of internal
organization closely tally with those now generally admitted. He recognized
the digestive tube, the formation of the globule of food at its apparently open
termination, and its onward course into the interior of the animalcule, where
it constituted one of the supposed stomach-sacs. He seems, indeed, to have
imagined a sort of stomach-like dilatation at the end of the alimentary canal,
which served to limit the dimensions of the food-globule there formed. The
circulation of the globules he attributed to the force of deglutition and to
the pressure of others subsequently swallowed : the residue left after diges-
tion he described as escaping by an anus.

An extract from Mr. Carter's valuable paper {A. N. H. 1856, xviii. p. 123)
may with propriety be introduced here. " I cannot," he says, " with some
others, think that there is any intestinal canal in the abdominal cavity, be-
cause the digestive globules and other particles of food are constantly under-
going circulation round the wliole of its interior. In Vorticella, particles of
food may occasionally be seen to circulate throughout, and accumulate in
every comer of its interior, particularly those which do not happen to be en-
closed in globules. Moreover, the intimate resemblance which exists between
the alimentary organs of higher Infusoria (viz. Nassula, Otostoma, &c.) and
those of the binocular and so-caUed blind Planaria; — in the distance of the
mouth from the anterior extremity, the presence of a buccal apparatus, and a
simple sac-Uke stomach in the latter, lined with a layer of mucous substance
(sarcode ?), charged with the ' spherical cells ' about to be described — is so
great, that, with such a simple gastric organ in an animal so closely alUed to
these Infusoria as Planaria, I do not see what reason we have, in descending
the scale, to expect a more complicated digestive apparatus, but, on the con-
trary, one still more simple, in which there would be no stomach at all, — a
condition which appears to mo to be common to all the Infusoria that have
come under my notice."

The results of actual observation show that food is di-awn mto the mouth
by the action of its surrounding cilia, and is thence transmitted rapidly through
the pharynx and its continuation, the digestive tube, into the loose tissue of
the interior, assuming at first an elongated oval shape, but wliich soon changes
to globular in its passage. The food so introduced appears mostly like a
minute di-op of water holding some soUd particles in suspension, and presents
a clear areola around a darker centre. Its course in the interior seems to
depend on the varying force of projection exerted by tlie contractility of the

or THE PEOTOZOA. CILIATA.

305

tube behind it and by the primaxy impetus given it by the action of the cilia ;
thus, the more rapidly it is propelled, the greater is the circuit it describes.
Stein represents it to make a wide spiral ciu-ve of one or two g-jTations in
Opercularia, and in 0. berberina to escape finally by a determinate discharg-
ing oiifice situated at the bottom of the vestibule. In tliis latter species, he
moreover describes the impetus of the swallowed portion to be so strong as
to drive the nucleus from its usual position. Although a discharging orifice
in a particular site is thus referred to by Stein in the Opercularia berberina,
yet at another page (p. 17) he says, generally, that he has been unable to de-
tect such a fixed vent in any animalcule, hut that where the excreted matters
do not, as in CJiiloclon and other species, escape by the mouth, they make
their way to one particular region of the body, through which they escape,
not by an opening with a visible margin, but through a rupture of the in-
tegument, which closes up and disappeai's immediately after their exit.

This production of a fortuitous opening for the escape of the excreta, had
been previously described by Dujardin as general in the Ciliata. Siebold, on
the contraiy, upheld the opposite opinion of the existence of a defined anal
apertm'e among them. In most Stomatoda, the anus (he writes) is generally
situated at the opposite extremity of the body to the mouth, and on the under
surface ; but where it is absent, the mouth seiwes both as inlet and outlet, as
among the Polj'pes. Cohn admits, at least iu certain cases, the presence of a
definite anus ; for in his recent figures of Nassula elegans (ZeitscJir., 1858)
he indicates .such an aperture (XXYIII. 11 g). Lachmann is very positive
on this question. He states (op. cit. p. 127) that " a long and careful ob-
servation of an individual will always show that the faeces are invariably
thrown out at the same part of the body ; and in many Infusoria we may
frequently recognize the anus in the form of a small pit on the surface of the
animal, even for a considerable time before and after excretion (this is often
the case in Paramecium Aurelia, P. Bursaria, and Stentor). That the fasces
are not forced through the parenchyma at any point on the smface of the
body, is proved especially by the careful observation of Spirostomum ambi-
guum, and some new animals which are to be united with the Stentors in one
family. In the former, the anus is situated at the hinder end of the animal ;
and close ia front of it is the very large contractile vesicle. "When fully ex-
panded, this vesicle appears to be suiTounded only by a thin membrane • but
nevertheless we see balls of excrement, often several at the same time, on
different sides of the vesicle, separating the laminae of its apparently simple
covering, and forming projections which are often neariy hemispherical both
towards the vesicle and the outer sm-face of the body. If masses of excre-
ment do usually penetrate through the parenchyma of the body, we should
expect it to be the case here when the tension of this is so great ; we should
also expect to see the masses of excrement pass into the contractile space if
' it were not a vesicle but only a space in the parenchyma without proper
walls. Neither of these things occurs, however ; the fecal masses are not
deposited from the body until they have reached the anus at the hinder ex-
tremity of the body. A similar strong expansion of a thin part of the body
by fa3cal masses, without any nipture, is seen, as already mentioned, in some
new Stentonna, which are distinguislied from the genus Stentor by their
having that part of the parenchyma of the body which beara the ciHarv
spiral and the anus (which in aU the Stenforina Hcs on the dorsal surface of
the body close under the ciliary spiral, and not in a common pit with a mouth 'I
drawn out into a thin process. In one genus, of which I observed two species
(one IS the Vorticelhna ampulla of 0. F. Midler) in company with E Clnna
rede on the Norwegian coast, and which I will describe elsewhere tiiis pro"

306

GENERAL HISTORY OF THE INFUSORIA.

cess is broad and foliaceous, and bears the rows of cilia on the margin, whibt
the anus is placed far up on the dorsal surface of a thin plate. In the other
genus, Chcetospira (Lachmann), observed by me in fresh-water near Berlin,
the process is narrow and bacillar ; the series of cilia commences at its free
extremity, and only forms a spiral when in action by the rolling up of the
lamina ; in this genus also the process bears the anus. In both, fsecal masses
which are thicker than the process in its extension, pass through it to the
anus, without breaking thi-ough it, notwithstanding the great expansion of
its walls.

" Not unfrequently several balls of excrement unite into a large mass
before the anus, in order to be passed out together. When an excretion takes
place, the anus is seen to open (but often closes once more and opens again
before the expulsion of the masses is effected), and then the fsecal masses are
often expelled slowly."

He fiu'ther describes the situation of the anus in Ehi-enberg's Oxytrichina
and Eu/plota, in Colpodea with the exception of the species of Amphileptus
and Uroleptm, in the Cyclidina, and in Glaucoma, Trachelitis, ChUodon, and
Nassula, to be on the ventral surface near the posterior extremity, or at the
posterior extremity itself. In Bursaria and Spirostomum it is placed at the
posterior extremity, as also more commonly in Coleps, Enchelys, and Trache-
locerca. In the Stentonna it occui's on the back close beneath the series of
cilia, and in Chilodon Ouculhdus it is nearly on the right margin of the body
near the hinder end. Among the true Vorticellina and Ophrydhw. the anus
opens into the vestibule very close to the oral aperture, a stout curved bristle
being placed between the two (XXIX. 2 e, i).

Excepting on this point of a preformed, constant, and definite discharging
orifice, there is among microscopists an almost universal accord in the pre-
ceding account of the phenomena connected wdth the reception and digestion
of food. It would be a useless expenditure of space to insert even an
epitome of the observations and arguments of only the most eminent of
modern naturalists who coincide with it ; it will be sufficient to cite their
names and their contributions on the subject: — Meyen, mEdiyib. Phil. Journ.
vol. xxviii. ; Dujardin, Ristoire des Infusoires, 1841 ; Siebold, Anatomic der
Wirhellosen Thiere, 1848 ; Boek, Ohen's Isis, 1848 ; Wagner, Zootomie, sect.
Infusoria, 1848 ; Van der Hoeven, Lehrhuch der Zootomie, 1850 ; Leuckart,
in Yan der Hoeven's new edition, 1856 ; Stein, Die Infusio-nsthiere, 1854 ;
Lachmann, "On the Organization of the Infusoria," A.N, H. 1857,xix. ; Carter,
Huxley, and CariDenter ; indeed, all British authorities, with whose works we
are acquainted, who have ■written on the subject. This is certainly a long
array of authorities against Ehrenberg's theoiy of polygastric organization ;
and almost the only advocate he has foiuid on his side is Eckliai-d, once a
pupil of his own. This gentleman has published some observations which
seemed confij-matory, but are undoubtedly erroneous in several particulars.
The folloTOng remarks, bearing specially on the subject at present under con-
sideration, may be quoted : —

He writes — " In such forms as are not too minute, we can distinctly see
how the nutriment, ai-tificiaUy supplied, constantly takes a definite course in
the body : in some instances the first portion of the alimentary tube can,
when not in action, be observed, as in Ej)istylis grandis ; it is then frequently
seen to be covered on the inner sui-face wnth. cUia. which, in the Opercnlaria,
may even be counted. But that this alimentary canal does not, after a short
coixrse, terminate abniptly in the body, can also be proved in the Epistyhs
grandis.

" In this animalcule a portion of colouring-matter swallowed is seen to

OP THE PEOTOZOA. CILIATA.

307

course along an intestine and enter a cell. I also once attentively observed
what appeared to be the extremity of the intestinal canal, to ascertain what
the fm-ther course of the coloured particles would be. At this time the animal
had not filled any of the cells in its inside ; suddenly two lateral cells became
filled, although I did not perceive any nutriment pass along the common tube.
This clearly points out that the two cells must be in connexion with the com-
mon cavity from which they had become filled ; and when, after the animal
has fed for a considerable time, we see that similar filled cells are diffused
thi'oughout the body, this phenomenon affords a ground for the supposition
that the intestinal cavity is of greater length than we should at fii'st sight
imagine." (Wiegmann's ArcUv, 1846, translated in A. N. H. 1847, xviii.
p. 433.)

M. Pouchet, of Eouen (Coinptes Bendus, xxviii. pp. 82-516), has also
adopted Ehrenberg's notion of definite gastric cells, but has been unable to
convince himself of the connecting intestine. Mr. Samuelson also (J. M. S.
1856, p. 165 ; 1857, p. 104) seems to coincide with this view ; but in his se-
veral papers on Glaucoma, cited, there occiu" variations in description, which
very much detract from their weight in deciding on any disputed point.

Lachmann gives the following details {A. N. H. xix. p. 118) : — " The vesti-
bulum continues the spiral line formed by the row of cilia, constituting a bent
tube, which contains a portion of this spire of cilia. In accordance with the
direction of this spiral, the concavity of the tube is turned towards the right,
and its convexity towards the left : on the convex side the lumen of the tube
is still more enlarged, especially in the parts placed furthest inwards, where
the anus opens. Between the anus and the mouth which leads further in-
wards into the oesophag-us spriags a bent bristle, which is generally long
enough to project outwards beyond the peristome. This bristle is stiff, and
is only displaced a little to one side occasionally, when balls of excrement,
which are too thick to pass between it and the wall of the vestibulum, are
thrown out from the anus ; but it immediately retm-ns again to its old position.

" From the mouth a short tube, the oesophagus, with a far smaller lumen
than the vestibidum, leads to a rather wider fusiform portion, which we will
caU the pharyruv."

This selection of terms we consider imfortxmate, because it is opposed to
their customary usage in comparative anatomy, — the pharynx being always
said to be prolonged into the oesophagus, and not the latter into the former.
In aU the CiHata, except the Vorticellina, the canal continuing from the oral
aperture is not distinguishable into two portions or segments ; and one term
would siiflSce to designate it throughout. In that class, where a division may
possibly be remarked, it would be better to call the upper segment the pharynx
or oesophagus, and the lower the alimentary tube ; by so doing, no false con-
ceptions could well arise. However, in quoting from Lachmann's description
we must let the words abide with the meaning he has assigned them.

To continue our extract — " In most Vorticellina (those with a contractile
stem, and the species of Episiylis and Trichodina) the longitudinal axis of
the vestibulum and oesophagus runs tolerably parallel to the plane of the ciliaiT
disk, wliilst that of the phaiynx has rather the direction of the axis of the body
In these, therefore, the axis of the ciliary spiral, which is continued as far as
the phaiynx, changes its direction at the commencement of the vestibulum •
whilst it coincided Avith the axis of the body outside the vestibulum it stands
almost perpendicular to it within the vestibulum and in the oesopha'o'us In
the very elongated foims of the Ophrydina (Ehr.), which inhabit" sheath-,
(Ophrtjdium, Vagimcola, Cothurnia), the longitudinal axis of the vestibulum
and oesophagus coincides more with that of the body, as also in the genera

X 2

308

GBNEHAL HISTOEY OF THE INFU90HIA.

Opercularia (as circumscribed by Stein) and Lagenophrys, Stein ; in the two
latter the vestibulum is very wide, whilst in the elongated species it is narrow,
but generally possesses a deep excavation for the anus."

" Besides the cilia of the spiral (ciliary wreath), some stronger cilia also
stand in the vestibulum, in front of the mouth ; these do not take part in
the regular activity of the others, but only strike forcibly sometimes, — appa-
rently to remove from the vestibulum coarse substances which may have got
into it, and also the masses of excrement."

" The morsel passed from the pharynx into the interior of the body nms
nearly to the posterior extremity of the Vorticella, and then, turning upwards,
rises on the side of the body opposite to the pharynx. During this portion
of its course, it usually still retains the spindle-shape communicated to it by
the pharynx, and only here changes to the globular foim, often rather sud-
denly : this induced me at fii'st to thiak that the morsel was still enclosed ia
a tube during this part of its course ; and this opinion seemed to be supported
by the cii'cumstance that, before and behind the morsel, two lines are not im-
frequently seen, which unite at a short distance from it, like the outhnes of
a tube which it has dilated. Subsequent obsei-vations, however, have again
shown me that this opinion is an imi^robable one ; for the circumstances de-
scribed must also occiu- Avhen a fiLsiform morsel is passed with some force and
rapidity through a quiescent or slow-moving tenacious fluid mass : the above-
mentioned lines, before and behind the morsel, must be produced by the se-
paration and reunion of the gelatinous mass, even if the morsel is not sur-
rounded by a tube. But the existence of a tube depending fi'om the phaiynx
appears also to be dii-ectly contradicted by the fact, on the one hand, that the
curves described by the morsel are sometimes larger and sometimes smaller,
and on the other, that the morsel acqim-es the globidar form sometimes sooner
and sometimes later, according as it is pushed out of the pharynx with greater
or less force and rapidity. The masses whirled into the phai-ynx ai'e not
always aggregated into a morsel ; but sometimes, under conditions which
have not yet been satisfactorily ascertained, all the masses which reach the
pharynx are seen to pass quickly thi'ough it without staying in it ; they then
stream through the mass suiTounding them in a clear streak which, hke the
morsels, describes a curve at the bottom of the beU, and only mix with the
mass when their rapidity of motion has diminished. A roundish morsel, which
might be regarded as a full stomach, is then never formed. We might easily
be inclined to regard the clear bent streak ■«ith the pai'ticlcs flowing in it as
an intestine ; and this has probably been done by Ehrenberg, who states that
he distinctly saw the bent intestine in some VorticelJtna, especially in Ejji-
stylis plicatilis, in -n'hich I have also been able to study the jjheuomenon very
closely. But in this case also there are the same reasons against the sup-
position of an intestinal tube, as in that of the lines appearing before and
behind a fusiform mass : here likeAvise, not only the form, but also the length,
of the cui-ve varies : whilst at one time it is but short, and soon tcnninates
by the intermixtui-c of the particles contained in it with the siu-rounding
mass, it may immediately afterwards be twice as long or longer — ^it may even
make a complete circuit and return nearly to its point of commencement be-
neath the pharjTix — a variation wliich appears only to depend upon the force
with which the cilia of the rotatory organ act ; so that we cannot explain the
whole phenomenon other\\ise than that the water with the particles contained
in it, streaming with some rapidity into the mass vrith which the body is
filled, cannot mix with the latter immediately, but only when its rapidity of
motion is diminished by friction, — just as we see a rapid stream which falls
into a sluggish or stagnant pool, or into the sea, still retaining its indepcnd-

OF THE PEOTOZOA. CILIATA.

309

ence for a certain space, so that, if it differs in its colour or turbidity from the
-water of the sea or pool, we may distinguish it from the latter (with which
it does not mix for a long time) in the form of a streak, which is often of
great length.

" When the nutritive particles hi the body of the Vorticellce have attained
the end of the clear streak imder a constant diminution of theii- rapidity — and
in the other case, when the morsel has lost its spindle-shape and become glo-
bular— they have no longer any separate movement, but now only take part
in a circulatoiy motion, in which all the parts iu the interior of the body,
with the exception of the nucleus and contractile vesicle, are engaged."

This account appHes in general to the alimentary mechanism of all other
Ciliata besides the Vorticellina, except so far as concerns the dilated lower
half of the oesophagus (i. e. pharynx of Lachmann), which is never seen.
' The ciliated oesophagus ends by an obliquely trancate extremity, through
i which the di'op of water introduced by the mouth enters the tenacious fluid
I mass of the interior, where it expands into a rounded vacuole or stomach-sac,
: which continues its onward curvilinear course untU, by absorption or by ex-
pulsion thi'ough the anal outlet, it disappears. Yet it may happen, just as in
the Vorticellina, that the water and food, instead of, as usual, being united
into drops and morsels, may be mixed at once with the contents of the abdo-
men, and no semblance of a full vacuole be produced.

A remarkable fact is recorded by Lachmann, of the digestive organization
of Traclielius Ovum, in which, by the way, Ehrenberg declared the alimentary
canal was more easily seen than in any other animalcule. " In Traclielius
Ovum," writes the author we quote (p. 127), " alone we see a proper stomach-
wall separated fi'om the rest of the parenchyma by spaces filled with fluid,
and thus form an arborescent ramified canal, which, however, must not be
confounded with the nucleus." To this statement he adds, in a foot-note,
■ — " The animalcules devom-ed {Trachelius Ovum is one of the most voracious
robbers) are always seen lying in the ramifications of the stomach, in the clear
spaces between them, except in crushed animals. The clear round spaces in
the pai-enchyma (cortical lamina) of the body, are certainly no stomachs, but
contractile spaces." This stnicture was affii-med to the writer by Licberk'iihn
and was, no doubt, seen by Ehrenberg, but misunderstood by him in most
points. Its gastric character, however, has not past unchallenged, for both
Cohn and Leuckhart (Wiegmann's ArcMv, Bericht, 1855) assert that it is no-
thing more than a fibrous band extending inwards from the integument in
different directions through the soft contents of the interior. In this expla-
nation Gegenbauer seems to agree— the granular bands described hr this
observer under the name of " trabocula) " appearing identical mth the fibres
of the two last-named wiiters. These trabeculaj are stated to be eontr;ictile
and to have a definite arrangement, the priucipnl one extending backwards
from the long, cihated, oral fissm-e along the same side of the l)ody, and having
• secondary trabecula; branching fi-om it and proceeding to the cortical lamina
where they are lost. And although Gegenbauer .speaks of an intestine-like
structure prolonged backwards from the mouth, in which numerous food
globules could be seen, yet he says that there was no perceptible diff-ercnoG
m structiiro to distmguish this so-caUcd intestine from the rest of the bodv

' ""u"" ^^f often seen passing

through the smaller rabocidic. Besides the oral fissui-e, he remarked another
opening situated further forward than it, beneath tiie motile prol,oscis, whore
the tcgumentary wall is thick, and connected mth a trabecula ex , n 1
mwards to umte with others. This opciing he found to be cltant ^^'^
and position, (o l,e ,,rolnnged inwards to the chief trabecula as a \wde

310

GENEIU.L HISTOHy OP THE INFTTSOHIA.

fimnel- shaped tube, often delicately plaited longitudinally, and surrounded
with cilia. Artificial feeding was tried ; but no colouring particles were swal-
lowed. The existence of a digestive power is shown by the disappearance of
organic matters which have been SAvallowed, leaving Uttle or no residue un-
absorbed. Thus other smaller animal organisms are often the prey of Ciliata ;
and their gradual absorption into the general mass may be occasionally
watched : the same, too, is true of vegetable matters such as Diatomece, Des-
midiece, portions of Oscillatorice, and of various minute Algas, — although here
a certain amount of unassimilated matter iu the hard lorica or valves remains
over and above, to be subsequently got rid of. The changes ensuing in food
during the act of digestion are illustrated by Ehrenberg iu his account of
Bitrsaria vernalis. This animalcule feeds very much on Oscillatorice ; and on
watcliing the fibres, they are seen, when first swallowed, to be elastic, rigid,
and of a beautiful bluish-green colour, but presently they become lax and
of a bright green hue, which afterwards changes to a yellowish green, and
ultimately to a yellow, the filaments at the same time breaking up into de-
tached joints.

An assimilative function is evidenced both by the foregoing facts of the
absorption of foreign organized matters, and also by the circumstances, that
the magnitude acquired and the activity of other functions are regulated by
the quantity of nutriment received, and that after certain substances have
been taken as food they may be detected in certain parts, or throughout the
tissue of the animalcule. Of the latter, the introduction of chlorophyll into
the subtegumentary tissue, by the medium of food containing this vegetable
constituent, is an example ; and in general the colour of an animalcule depends
directly on the food taken, or is indirectly influenced by its quahty and
quantity ; for an animal well nourished always exhibits its pecuUar colour
in the highest degree, whilst ill-nourished sickly examples present little or
none.

This topic suggests another closely allied to it, viz. the artificial feeding
with coloured substances, so much resorted to by Ehi-enberg in his researches.
It consists in the introduction of a very small quantity of some insoluble
colour, not a poison, capable of minute division, into the water in which the
animal floats whilst under observation. The coloui-s genei-aUy employed are
indigo and carmine, a little of one or other of which is rubbed on the wet
margin of the slide, surrounding the thin glass cover, whence it gradually
steals under the cover, and disperses its fine particles through the little drop
in which the animalcide floats.

Another substance has been proposed as preferable, by Mr. Thomas "VNTiite
(J. M. S. 1854, p. 282), viz. the red eyes of the common fly, reduced to fine
powder by pressiu-e. By feeding animalcules with this in heu of carmine, the
disadvantage arising from the dark particles of the latter crowding the field of
view and obscuring the objects is obviated ; and, on the other hand, it has the
actual advantage of being more readily imbibed, and therefore of appearing
more speedily in the apparent stomach-sacs.

Ehrenberg imagined that the Ciliata enjoy the sense of taste, leading them
to choose or refuse at will among articles of nourishment witliin their reach.
Thus he says that, amidst a number of indi^nduals of Paramecium Aurelia,
some took one sort of food, and others another, — no doubt a correct observa-
tion, but insufficient to prove the existence of taste. Nevertheless it must be
allowed that some animalcules are especially found in company either with
certain other small animal organisms, or Avith particular plants, or in water
holding certain matters in solution, — a fact upon which our knowledge con-
cerning their habitats and modes of life rests, but in itself no proof of the

OF THE PROTOZOA. CILIATA.

311

existence of a sense of taste. Indeed, in the case of minute plants we per-
ceive a similar apparent selection of localities abounding in appropriate nutritive
I matters. Another assumed vital characteristic was, that Cihated Infusoria
I have a feeling of company (a fondness for society), inducing them to con-
gregate together, — an idea requiring considerable effort of imagiaation to
conceive, but which, we fear, mil scarcely find acceptance as a fact by any
person who will look abroad for parallel instances of the congregating together
of the same organisms ; and plenty such are at hand, even among the lowest
plants.

Dental Appakatus, oe Teeth.— Before qiuttiag the subject of digestion and
of the digestive organs, some notice must be taken of the pecuhar formations
considered by Ehrenberg to represent a dental apparatus concerned in the
preparation of the food for digestion. This apparatus occurs in the form of
a cyUnder of apparent bristles (XXIV. 282, 283, 308, 309 ; XXIX. 48)—
the supposed teeth — placed behind the mouth, as seen iu Chilodon (XXIX.
48), Nassula, Chlamidodon, and Prorodon (XXVIII. 8, 65). The cylinder
of teeth was farther stated to be wider in front, to be able to expand itself to
receive, and afterwards to contract on the engulfed particle of food, so as to
crush it and drive it inwards.

To these notions of the natiu'e and action of the organ in question. Stein
cannot assent. He states (p. 128) that he has frequently tried iu vain to
isolate it. On killing an animalcule with solution of iodine, or with dilute
acetic acid, the funnel-like tube, at times straight, at others curved, is di-
stinctly displayed, as well in the smallest as in the larger specimens. It
tapers posteriorly, and ends abruptly by an open extremity in the cavity,
and is composed of the same resistant elastic membrane as the cuticle.
Stein gives it the name of the " oesophageal funnel." Its wider and thicker end
is truncate and dentate or seiTate, having from 8 to 16 dentations : between
these the membrane appears to be plaited or groved for a considerable distance
downwards ; and it is these plaits or folds which Ehrenberg took to be long
bristle-like teeth arranged side by side. This cyhnder, therefore, is nothing-
more than an involution of the integument. It can be retracted and appear
like a tapering oesophageal tube, or be protruded like a tmmpet-shaped pro-
cess beyond the general surface. It has not, however, that independent
motile power in itself represented by Ehrenberg ; but aU its movements
depend upon those of the integument ; for Stein has never seen it either con-
tract or dilate, except simiUtaneously with the contractions of the general
surface. It bends, and is doubled up under pressure, and is neither denser
nor a more brittle tissue than the cuticle ; nor can it be resolved into rod-Uk©
segments.

The plaited upper portion is not a])parent hi aU species which have a
homologous organ: thus in Nassida amhi(jua{^tQm,\). 249) the infimdibulum
is smooth, although the double outline its membrane exhibits iuchcates its
very considerable thickness.

Seceetion. — Sufficient evidence of the operation of tliis function is found
in the Ciliated Protozoa, although no special organs or tissues can be pointed
out for its exercise, unless, indeed, the pair of peculiar solid-looking organs
in the head of Opercidaria berbenformis, hereafter mentioned among accessory
undetermined stnicturcs, be considered glandular (XXX. 2 c).

The production of cilia may be considered an act of secretion, exercised so
soon as an animalcule assumes a definite outline, and, luider certain circum-
stances in connexion mth the encysting-process, repeated a second time
within the life-time of an individual. Again, the excretion thrown out
around Protozoa wlien about to encyst themselves is another example of the

312

GENEEAi HISTOEY OF THE INFUSORIA.

same process ; so is also the special production of cuticular matter in the con-
struction of the dense resisting sliields and urceoU of loricated species, e. g.
Coleps, or that of the substance used in the formation of stems and of
external sheaths. Another instance of a secretion maybe seen in the solvent
fluid poiu-ed out for the solution of solid particles of food in the interior, — a
fluid certainly not demonstrable apart, but presumable from the phenomena
of digestion.

Having observed the particles of food in the abdominal cavity to be fi-e-
quently sui-roundcd by a clear space filled mostly "with colourless, but some-
times mth a coloiu'ed hqiiid, Ehrenberg at once attributed to it a digestive
faculty, and termed it the bile. He speaks of this in the history of the geniLS
Bursaria, where it is stated to be either coloiu'less or reddish. In Nassula,
again, he figures bihary glands in the shape of vesicles forming a Avide circlet
around the mouth, filled with a violet- coloured juice, which is discharged
with the excrementitious particles, and which at first ajij^ears like drops of
oU, but soon mixes with and becomes diffused through the water. The
following species are enumerated as possessing one such vesicular gland : viz.
CJiilodon ornatiis, Bursaria vernalis, Trachelius Meleagris, Ampliileptus inar-
garitifer, A. Meleagris, and A. hngicollis.

The bodies thus represented by Ehrenberg as vesicular glands have not
escaped the notice of Stein, who pronoimces distinctly against theti' glandular
natui'e, and insists upon their being nothing but sections or joints of the fibres
of the Oscillatorioi and other plants that the animalcules feed upon, and which,
in the course of their digestion, change from green to a dusky blue, afterwards
to a reddish-brown coloiu", and at length, when broken up, become difiFused
throughout the interior, and impart to the entire animalcule a reddish-
yellow hue.

Cohn (Zeitschr. 1857, p. 143) has remarked in Nassiila elegans numerous
granules of a yeEowish-brown and violet coloui", either collected into heaps
or scattered through the interior. On the imder surface, near the anus, is
usually a large violet mass, and at the opposite extremity a similar smaller
one, which have been described by Ehi'enberg as biliary glands (XXVIII. 11,
12). If they are not particles of vegetable-coloured food altered in hue by
the process of digestion or solution, they may, says Cohn, be considered
analogous to the chlorophyll-corpuscles of Paramecium (Lo.vodcs) Bursaria,
of Sjoirostomum, or of Voriicella viridis, and a special form of colouring
matter. The collection of the coloured mass about the anus, and its dis-
charge in the shape of bluish particles — ^facts noticed by Ehrenberg — indicate
its nature to be effete and excrementitious. Yet it is not the mere ciiide
joints of Oscillator ia, as Stein supi)osed, but matter which has been digested.
The heap about the neck is by no means constant.

CoNTEACTiLE Vesicle. — Passing now to the other contents of the CUiata,
the contractile vesicle or space first arrests our attention. Mr. Carter would
call it simply the ' vesicida ; ' but this word, without the adjimct " contractile "
to particularize it, seems insufficient, especially when the Latin language is
used in description.

This organ is of universal occun-encc among the Ciliata ; it is mostly single ;
but in a few instances two and even three such, mostly of unequal magnitude,
occur. It did not escape the notice of Elircnbcrg, who has figured it in all
his plates of these licings. It occurs as a clear, hollow, mostly rounded space
in the interior, its precise position diffbring in different species. It is always
placed in, or closely connected with, the cortical or contractile lamina, and is
not affected by the oirculiitorj' current. In tlie great majority of species it
is situated nearer the anterior extremity, and in very close relation with the

OP THE PHOTOZOA, CrLlATA.

313

mouth or alimentaiy tube: thus in Ophnjoglena, Bursaria, Ojoercularia,
Epistylis, and Zoothamnium it lies close iipon the vestibulum within, or
almost within, the region of the ciliary wi-eath (XXVII. 16 ; XXX. 9-11) ;
in Vorticella and Vaginicola it is placed against the upper part of the ali-
mentaiy tube, and in Trkliodina, Nassula, and many others, near it at its
termination (XXX. 5, (5, 17 ; XXIX. 4). Exceptions to this position are
met with in Goleps and Colpoda (XXIX. 35-37), where it occupies the
posterior extremity, placed very close to the external sm-face. When two
vesicles exist, they are often placed on opposite sides of the body, the one
more or less anterior to the other, as seen in Paramecium (XXIX. 29, 30),
In Chiloclon Cucullulus a third is sometimes seen near the posterior extremity
(XXIX. 48).

On watching these clear spaces, they are observed to disappear for a few
moments and again to reappear — ^in other words, to exhibit rhythmical con-
tractions, a feature which distinguishes them from any other vesicxilar spaces.
The contraction is known as the ' systole,' the re-expansion as the ' diastole ; '
these movements may be either regular or iiTegular, and they differ in dura-
tion in different species. Perty states that the pulsations in Stylonychia
pustidata occupy from six to seven seconds : in SpirocJiona and Colpoda they
ai'e more prolonged ; indeed, as Stein affii-ms, they are slower in the former
genus than in any other animalcule he has examined. When more than one
vesicle is present, no uniformity ia the order of their movements has hitherto
been proved, although Siebold believes they must follow some rule. As evi-
dence of the independence of the vesicle of the general contents of the body,
Lachmann records {A. N. H. 1857, xix. p. 126) the fact that, even after the
contents of an animalcule have been sucked out by an Acineta, the vesicle
lodged in the still present and contractile layer may continue to pulsate for
several hours.

With regard to the number of these vesicles in particular species, much
discrepancy has existed among observers. Siebold affirms that Ehrenberg has
proceeded in a purely arbitrary manner in calling one a conti'actile or sper-
matic sac, and others, indistinguishable from it, gastric cells, and quotes in
illustration the Berlin Professor's description of the vesicles of Amphileptus
meleagris and of A. longicollis. To this objection Eclchard rejoined by assert-
ing that Ehrenberg was guided in determining the natm-e of vesicles by cer-
tain appreciable differences in the character and contractions of different sacs
and that Siebold had erroneously represented lateral abdominal vesicles in
Stentor, and an elongated one in Spirostomum ambiguum. In this, however
he was wrong, for the description of Siebold has been confii'mcd by Lachmann
and others (XXIX. 7) ; and on the other hand, Ehrenberg is not so much in
error respecting the numbers of these vesicular spaces as Siebold was led to
suppose.

It is, indeed, only by careful and repeated observations tliat such variations
can be reconcUcd. In pronoimcing a space contractile, a sufficient criterion
seems to be found in the circumstance of a Hlce organ being found in all
specimens of the same animalcule, constant in position, and^rhythm'ical in
its movements. Gastric cavities or alimentary vacuoles may collapse' and
disappear ; but this movement is not fbUowcd by renewed acts of disappear
ance and reappearance m regular succession, and in the same spot • for if ono
such vacuole do replace another, a general movement onwards in 'the courso
of the mteraal cyclosis may be discovered. Another test to distineiiish a
stomach-vesicle fixmi a true contractile sac may be found in the use of coloured
food. Now that the special contractUc sac is achnitted gcneraUy to be morel v
the central organ of a system of contractile vessels disposed at vai-ious parti

314

GENERAL HISTORY Oi" THE INrUSOfilA.

of the body, the appearance at times of additional vesicles, and consequently
also the discrepancies of authors as to the numbers present, are explicable
by supposing the accidental dilatation of a tube here and there — as a vari-
cose vessel, — the dilatations representing for the time additional contractile
spaces.

This explanation occurred, among others, to Mr. Carter. Thus he remarks
(A. iV. H. 1856, xviii. p. 128) that in Chilodon, where the vesicle is normally
single and near one extremity, it is not uncommon to meet, amid a group of
these animalcules, various individuals presenting a variable number of con-
tractile vesicles irregailarly dispersed through the body, without one being in
the true position of the ' vesicula.' *' That," he writes, " the ' vesicula ' does
make its appearance now and then, may be inferred, as it perhaps may also
be inferred that from over-irritabiHty, or some such cause, it does not remain
under dilatation long enough to receive the contents of the sinuses ; and hence
their accidental dilatation, and the appearance of a plui'aHty of vesiculae."

To this accidental dilatation of vascular channels at particular points may
be referred the 50 to 60 reg-ularly placed vesicles described by Gegenbauer
in Trachelms, the 12 to 16 mentioned by Siebold and Perty in AmjjhilejJtus,
and also the row of them seen along the side of Stentor, In this last-named
genus there is a circular canal surrounding the head or cihaly wreath, which
sends oE a branch at right angles along the side to nearly its posterior end
(XXIX. 7). In Sjpirostomum, again, a long contractile channel occupies the
length of the body.

The existence of a second vesicle in an animalcule normally possessing but
one, Ehrenberg explained by supposing an act of fission to have occuiTed
prior to division of the entire being, — an explanation in which Mr. Carter
concurs. But if Stein be right, the contractile vesicle does not undergo
fission, but makes its appearance in the newly-formed half by an act of
development de novo. In this statement Wiegmann concurs (Perty, p. 63).

Ehrenberg concluded the contractile spaces to be tnie sacs, limited by a
definite membrane, — a conclusion sanctioned also by Siebold, forasmuch as,
during successive conti'actions and dilatations, the vesicles retain the same
place, flgiu-e, and number. Mr. Carter supphes direct evidence of the fact
(A. N. H. 1856, xviii. p. 130), having observed on one occasion a vesicle re-
main pendent in a globular foi'm to the buccal cavity of a Vorticella. " when,
by the decomposition of the sarcode and the evolution of a swarm of rapidly-
moving monadic particles, these two organs, with the cylindrical nucleus or
gland, though still sUghtly adheiing to each other, were so dissected out as
to be nearly separate ; and thus yielding in position fi-om time to time, as they
were struck by the little particles, their forms and relative positions respect-
ively became particidarly evident." Moreover, Lachmann (A. N. H. 1857,
xix. p. 226) argues at length in favom- of the true vesicular character of
contractile spaces. Thus he remarks — " The mode of contraction, which
differs from the other contractile phenomena of .the pai-enchyma of the body,
appears to speak decidedly in favour of the vesicular natui-e of the contractile
space. The circumstance tluit, before its complete expansion, it frequently
appears to be divided into two or three, is not opposed to tins, as a vesicle
may very well be constricted into two or more pai-ts by tlie partial contrac-
tion of annular portions, or by strictures. Some other facts appear to be in
favour of the vesicular nature of the contractile space, such as the phi«nomenou
presented by Spirostommn ambiguum, ab-eady referred to, in which balls of
excrement pass to the anus between the contractile space and the outer sldn
of the animal, and, although often arching the wall of the contractile space
into a semiglobular form, yet never break through into it. In Actinophnjs, the

OF THE I'KOTOZOA. OILIATA.

315

supposition that there is a membranous boundary, at least on the outside of
the contractile vesicle, can hardly be rejected, as its wall, which is situated
on the outermost sm-face of the body, must burst at the moment of greatest
expansion, if it were only composed of the gelatinous parenchyma of the
body."

Still the contrary opinion, viz. that the contractUe spaces are mere vacuoles
in the substance of the interior, without a limiting membrane, has found able
supporters in Meyen, Dujardin, Stein, and Perty. The fii-st-named writer
compares them to the changing vacuoles which spontaneously generate in
the vegetable protoplasm of plant-cells, by an inherent property or process
known as that of vacuolation, and which is equally a phenomenon of simple
animal protoplasm or conti-actile tissue. Indeed, there is no doubt that clear
hollow spaces or vacuoles may appear and disappear within the substance of
Protozoa, and that some of those remarked by Dujardin, Siebold, and others
immediately beneath the iategument were of this number ; yet such vacuoles
want the constancy in position, figure, and pulsating power belonging to true
contractile sacs. Besides, as we shall presently see, the evident ramifications
or canalicuK of many contractile vesicles among the Cihata afford fui'ther
grounds for distinguishing between these and mere vacuoles, which, as far as
we ai'e aware, never have such oifshoots.

Another questionable point among observers is, whether any communica-
tion exists between the cavity of the contractile vesicle and the free surface
near to which it is placed. The majority concur ia the negative ; but several,
among whom are Oscar Schmidt (Froriep's Notiz., 1849, vol. ix. ; Lehrbuch
der Vergleichend. Anatomic, 1853), Mr. Gray (Silliman's Journ. 1853), Mr,
Kood {Silliman's Journ. 1853, p. 70), and Mr. Carter, axe of opinion that a
direct communication, between the fluid contents of the vesicle and the watery
medium bathing the external surface, is established by means of foramina in
the waUs. On this question Lachmann remai'ks {op. cit. p. 227) — " In many
Infusoria we see one or more pale spots upon the contractile vesicle, which
may easily be mistaken for orifices, but on closer examination prove to be
only thin spots in the parenchyma of the body and the skin, by which the
action of the external water upon the contents of the vascular system is
certainly facilitated, so that they probably serve for respiratory purposes.
These round clear spots are particularly numerous upon the contractile space
of Spirostovium ambiguum." The admission or the denial of such a commu-
nication wiU very much affect the opinion held concerning the nature of the
office performed by the vesicle, to which we shall immediately advert.

The supei-ficial vesicles or vacuoles before alluded to, considered by Dujardin
of the same natiire as the contractile vesicle itself, have not been sufficiently
examined and defined of late to warrant a conclusion as to theii" real cha-
racter : yet probably some of those spaces are no more than mere vacuolte
whilst others are dilatations of the channels of the ramified vascular system'
Mr. Carter would in general assign to them the latter character. Ilowcver"
we believe that many of those which have attracted attention have been
isolated vesicles, developed from time time, and to bo concerned in securin"-
a more perfect aeration of the contained fluid. Siebold, indeed, went so far
as to presume they opened upon the external surface, and brought their con-
tents into relation with the surrounding water.

In figure, contractile spaces are, for the most part, round or somewhat
oval, and as to size stand m no direct relation with that of the animalcules
they appertain to. Examples of the prevailing figvu-e ai-e seen in Ophn/dmm
Zoot1mmmum,CModon, Colpoda, Trichodina, &c. Even in some of these aiim '
rentiy simple globular sacs, Mr. Carter discovered a series of spherical sinuses

31G

GENERAL lUSTOUT OF THE INEUSOEIA.

slUTOimding and communicating directly with them. These accessory vesicles,
he tells us {op. cit. p. 130), are, " under exliaustion of the animalcule from
vai-ious causes, so distended, and thus so approximated, as to assume the
appearance of an areolar stnictm-e immediately in contact vnth. the vesicula.
Each globular sinus would, however, appear to be the proximal or largest of
a concatenation of smaller ones, which diminish in size with theii- distance
from the vesicula." This account tallies with that recorded by Mr. Samuelson
(J. M. S. 1857, p. 104), respecting the single globular vesicle of Glaucoma
scintillans, which " when it contracts forces the fluid into others which
appear temporaxily formed around it ; " and these, by contracting in their turn,
refill the central vesicle.

Besides the seemingly simple spherical vesicles, there are others that pre-
sent evident branches and a different figure. Such, for instance, are the
elongated vascular canal of Sinrostomum, and the annular canal with its row
of vesicles dowoi the side, — ^which seem capable of coalescing into a continuous
channel, seen in Stentor (XXIX. 7). In Paramecium Amelia (XXV. 329),
each contractile vesicle assumes a steUate form, owing to the radiating pro-
cesses it sends ofi" on aU sides, and which Eckhard represented as prolonged
through the body by interrupted channels. It is from the study of this
Paramecium especially, that observers have generally arrived at the belief in
the existence of vascular canals in the Ciliata, connected with the contractile
vesicle as a central organ. That there exists a vascular system more or less
distributed through the body, most recent microscopists are in accord : we
may mention Lieberkiihn, Lachmann, Mr. Carter, Professor Busk, and Mi-.
Samuelson.

As this apparatus vtill be best considered in connexion with its assigned
functions, we shall speak of them together, premising our account with the
history of Ehrenberg's conjoctiu'es on the nature and function of the con-
tractile vesicle. This distinguished natui'ahst was led by his hyjiothesis of
organization to seek for each of the organs of higher animals a parallel or
analogue in the Infusoria ; and one of the most curious analogies he hit upon
was that of the contractile sac with the spermatic vesicle. In tliis office he
represented the vesicle as receiving from the testis (nucleus) a reproductive
fluid, which it again ejected among the ova (granules, alimentary vesicles,
&c.) occupying the interior of the animalcule. In this peculiar notion
Ehrenberg has met with few disciples : for, as Siebold has justly objected, it
is a perfectly gratuitous hypothesis, without analogy in the animal kingdom :
for in no animal is such a thing seen as an incessant projection of seminal
fluid into the iuterior ; and fiu-ther, both the nature of the nucleus as a testis
or secretory organ of spermatic fluid, and the existence of recipient ova, arc
at best very doubtful hypotheses.

The opinions now in vogue concerning tlic fimctiou of the contractile
vesicle and of its prolongations or processes are that it is either (1) a water-
vascidar and respiratory system, homologous with that of the Rotatoria,
or (2) homologous vnth a blood-vascular system, or (3) an excrctoiy appa-
ratus. The first conjectui'e presupposes a dii-cct commimication between the
fluid in this vascular system and the surrounding aqueous medium ; by the
second, no such direct communication need be presumed ; the third view is
especially supported by Mr. Carter, Bergmann, and Lcuckliart.

In his notions concerning the organization and fimction of the contractUo
vesicle. Stein diff'ors from most other recent investigators. As we have
already seen, he denies a limiting membrane to the vesicle ; he, moreover,
can neither acquiesce in the belief of the existence of outlets, nor in the
respiratoiy pm-posc attributed to it by Siebold and O. Schmidt. Ho is oven

OP THE PROTOZOA. CILIATA.

317

doubtful of the stellate structure, as an actual fact, in the Parameeia ; for in
P. Bursaria, in Nassula, and other animalcules this apparent structui'e may-
be, he believes, produced at wiU by the exercise of shght pressm-e, as by that
of the thin glass-cover upon the object, when the diastole of the vesicle is
incomplete. Again, he objects against the supposed water-vascular system
and its respii'atory office, that, in comparison to the large ciliated pharynx,
within which a fresh supply of water is perpetually introduced, and through
whose delicate waUs a respu-atory act may be readUy conceived to take place,
the small contractile space commonly appended to it appears of inconsider-
able importance as an aerating organ. Further, he cannot conceive the
necessity of a respiratory apparatus in any animalcule which lives surrounded
on all sides by water, besides receiving it incessantly within its interior, and
which can therefore so readily absorb its oxygen through its delicate tissues.
Another fact adverse to this assigned function is, that the vesicles of embryos,
whilst stiU within the parent, are seen in full activity, although in that posi-
tion no renewed supply of fresh water is afforded them.

These objections of Steia lessen upon consideration : thus his opinion that
the vesicle is a mere vacuole, that its radiating canals are probably accidental
appearances, and his ignoring the existence of a set of vascular channels
through the interior, are set aside by the direct observations of several
naturalists to the contrary. So, although his arguments, generally, against
the presence of a special respiratory appai-atus are not without force, yet the
remark that he can conceive no need of such an apparatus in animalcules so
circumstanced as the Ciliata is worthless as an argument ; for in all such
inquiries into the phenomena of life we are not to suppose an organization
and then to find it, but, on the contrary, to discover facts, and then, if possi-
ble, to determine on their nature.

That the contractile vesicle and its connected channels do not constitute a
water-vascular and respiratory system, is also the opinion of Lachmann and
Carter. The former able observer has confirmed and extended oiiv previous
knowledge of the vascular apparatus, and thus conveys his researches and
opinions (op. cit. p. 224) : — " When the contractile space (of Paramecium
Aurelia) is full and wide open, the rays can only be observed as fine Knes, or,
when the light is not good, are entirely imperceptible ; by the sudden con-
traction of the space, however, they instantly swell into a pyriform com-
mencement close to the position of the contractile vesicle which has disap-
peared. "With favoiu-able illumination, when the animals possess the proper
degree of transparency, the rays may be traced in Paramecium Aurelia across
the half of the animal, and we may sometimes perceive a bifui'cation of one
or other of them. During the slow reappearance of the contractile space,
the rays gradually decrease ; and they have almost entii-ely disappeared, or
become reduced to fine lines, when the vesicle has attained its full extension.
These rays, as well as the contractile spaces, lie, as in aU Infusoria, close
under the skin (' cuticula ' of Cohn), in the parenchyma of the body (' corti-
cal layer ' or ' cell-membrane ' of Cohn).

" In many Vorticellce we also find processes going off from the contractile
vesicle (Ehrenberg even states that he has frequently seen the contractile
vesicle of Oarchesivm polypinum lobate or almost radiate) ; of these I have
been able to trace one particularly, in V. nehulifera, V. Campanula, and Carche-
sium polypinum, up to close beneath the skin of the ciliary disk ; this, when
seen fi-om above, exhibited a longish section. From this a fine branch appears
to run, on the upper wall of the vestibulum, transversely across tliis to the
other side ; at least, I have seen a thin process hanging down like a short
curtain into the vestibulum from the side turned towards the ciliaiy disk

318

GENERAL HISTOHY OF THE INFU80KIA,

which swelled up when the above-mentioned process became enlarged in con-
sequence of the contraction of the vesicle.

" In Denclrosoma radians (Ehr.), a fine vessel runs through the whole
length of the body, and sends branches into its ramifications : it is furnished
with a number of contractile spaces, partly in the stem and partly in the
branches.

*' The processes of the contractile space are seen with remarkable distinct-
ness in the large Stentor polymorjjhus (including /S. Eosselii and S. Mulleri), in
which a very considerable portion of a vascular system may be recognized.
The large contractile space lies a little to the left of the oesophagus, near the
plane of the cUiary disk. From it a longitudinal vessel runs to the posterior
extremity of the animal, and an annular vessel round the ciliaiy disk (Stirn)
close imder its series of cilia. Both these are visible even during the expan-
sion of the contractile vesicle, but swell up suddenly like the vessels of the
above-mentioned Infusoria during its contraction : at this time the longitu-
dinal vessel usually exhibits considerable dilatations, which, when superfi-
cially examined, may easily be taken for independent, disunited cavities
(vacuoles). The annular vessel exhibits a more uniform lumen ; only two
roundish dilatations make their appearance in it — one close to the anus on the
dorsal side of the animal, and the other close to the oesophagus on the ventral
surface. Both vessels gradually decrease dming the reappearance of the con-
tractile vesicle, apparently without any contraction of their own, in the same
way as the vessels of the Paramecia. The longitudinal vessel of the Stentors,
and a similar one in Spirostomum amhiguum, were first described by Von Sie-
bold, whilst their existence has been erroneously denied by Eckhard.

" As we thus find a vascular system in the Stentors, and in other Infusoria
recognize the parts lying nearest to the centre (the contractile space) some-
times easily and sometimes with difificulty, we may certainly conclude that
such a system exists in aU Infusoria which possess a contractile space, even
when no branches have been detected running out from this. That this
system does not merely consist of accidental chasms in the parenchyma of the
body (vacuoles of Dujardin), is apparent from its regularity. When it is as-
serted, in proof of the inconstancy of these vacuoles, that exactly similar ones
frequently make their appearance in other parts of the body, this appears to
me to arise from very difierent things being confounded together. The swell-
ing dilatations of existing vessels are certainly often regarded as such vacu-
oles, without its being remembered that these dilatations always gradually
decrease again, whilst the true vascular centres, the contractile spaces, always
diminish suddenly in healthy animals. Moreover, in diseased Infusoria, an
exudation of a fluid, with which the parenchyma is normally imbued, appeara
to take place from it even into the cavity of the body, and perhaps into chasms
of the parenchyma, as we often see it take place in Infusoria and many other
low invertebrate animals, on the smface of the body. These sarcode-drops
appear to be incapable of ever being again absorbed ; but their fonnation
always appears to lead, although slowly, to the death of the animal."

After the above details, Lachmann inquires the nature of the function this
vascular apparatus performs ; and having satisfied himself of tlie nonexistence
of a communication between the interior of the vesicle and the external sur-
face, he rejects the idea of its being a water-vascular system, as " we do not
possess the certain proof of one of the most essential requirements of a water-
vascular system — the existence of an external orifice, — and some things
appear directly opposed to it."

Mr. Carter coincides with Lachmann in many particulars respecting the
structure of the vascular system of Ciliata ; but in others he materially differs :

OP THE PEOTOZOA. CILIATA.

319

for instance, he thinks he has made out the existence of apertures opening
on the fi-ee surface whether of the ahmentary tube or of the general integu-
ment, close to one or other of which he always finds the vesicle ; and, with
this view of the structure, he connects the function of an excretoiy organ
with the sac in qiiestion.

To support this view respecting the office of the contractile vesicle, he ad-
vances the following obsei-vations (op. dt. p. 126) : — " 1st. It is always seen
either close to the peUicula or close to the buccal cavity, and always sta-
tionary. Thus, in Paramecium Aurelia it is close to the surface, and although
it, of com-se, passes out of view as the animalcule turns on its long axis, yet
it always reappears, after contraction, in the same place, — while in Vorticella
it is attached to the buccal cavity, and, being centrically situated, seldom
passes out of view, except when it disappears under contraction, after which
it also reappears in the same place.

" 2nd. In Actinophrys Sol and other Amcehcn, during the act of dilatation,
the vesicula projects far above the level of the pelliciila, even so much so as
occasionally to form an elongated, transparent, mammUlifoiTa eminence,
which, at the moment of contraction, subsides precisely like a bUster of some
soft tenacious substance that has just been pricked with a pin.

" 3rd. Lastly, when we watch the contraction of the vesicula in a recently
encysted Vorticella, we observe that at the same moment that it contracts
the buccal cavity becomes filled with fluid, and, further, that this fluid dis-
appears from the buccal cavity, and all trace of the latter -with, it, long before
the vesicula reappears, — thus proving at once that the fluid comes from the
vesicula, and does not return to it, whatever may become of it afterwards.

" The position of this organ, then, its manner of contracting, and the buccal
cavity of encysted Vorticella becoming filled with fluid the moment it disap-
pears (where we know it to be attached to the buccal cavity, and not to the
pellicula), are almost concliLsive of its excretory office."

Adopting SpaUanzani's observation (which, however, wants confirmation to
estabHsh it as the rule) that the fusiform sinuses of Paramecium Aurelia be-
come empty as the vesicle fills, and do not reappear until some time after it
has contracted, he infers " that the fluid with which the vesicula is distended
comes through the sinuses, but is not returned by them to the body of the
Paramecium."

" Now in some cases," he continues, " faint hyaline or transparent lines
may be seen to extend outwards from each of these sinuses, which lines
Eckhard has stated, ' traverse the body in a stellate manner.' 'Hence when
we add Eckhard's evidence (which I have been able to confirm in a way that
wiU be presently described) to the observation of SpaUanzani, and connect
this with the facts ab-oady adduced in favour of the excretory office of the
vesicula, it docs not seem imreasonable to conclude that the whole to"-ether
forms an excretoiy vascular system, in which the vesicula is the chief recep-
tacle and organ of expulsion.

" While watching Paramecium Aurelia, 1 on several occasions not only ob-
served that the vesiculac were respectively surrounded by from seven to
twelve pyi-iform sinuses of diff-erent sizes, and that hues extended outwards
from them m the manner described by Eckhard, but I further observed that
these hnes were composed of a series of pyriforra or fusiform sinuses which
diminislied m size outwai-ds ; and frequently I could trace as many as three
in succession, including the one next the vesicula. Hence I am incUned to
infer that this vascular system throughout is more or less composed of chains
of such smuses, and that nU have more or less contractile power like that of
the vesicula. Just precedmg death, when Paramecium Aurelia is compressed

320

GENERAL HISTOKY OF THE INFUSORIA.

and under other favourable circumstances, these sinuses run into contiauous
hyaUne lines, and may not only be seen extending in a radiated vascular
form across the animalcule, but even branching out round the position of the
vesicula, which, having now become permanently contracted, has thus poured
back the contents which render them visible. They enter the lower or inner
part of the organ, and at this point, therefore, are pushed inward as the vesi-
cula becomes distended. Under the same circumstances, also, when the vesi-
cula is slowly dilating and contracting, it may be seen to be attached to a
small papilla on the surface, about twice the diameter of those which sur-
movmt the trichocysts, and through which it probably empties itself (XXVIII.
25). In Oto stoma there appears to be a similar arrangement of vesicles round
each vesicula ; and here also they seemed to me to be branched — at least
such was my impression after having watched this animalcule for a long time
in order to determine the point."

" Of the use of the vesicula and its vascular system," Mr. Carter concludes.
" we are at present ignorant, further than that its functions are excretory ;
and when we observe the quantity of water that is taken into the sarcode
with the food, and try to account for its disappearance, it does not seem
improbable that the vesicula and its vessels should be chiefly concerned in
this oflB.ce. Another service, however, which it performs, is to burst the
spherical membranes of Vorticellce and Plcesconice when they want to return
to active life after having become encysted : this it effects by repeated dis-
tension, until the lacerated cyst gives way sufficiently for the animalcule to
slip out."

" Should it have any other uses, they are probably similar to those of the
' water-vascular system ' of Rotifer a."

In answer to the question, if all vacuolar spaces, excepting those produced
by the deglutition of food, belong to this excretory system of contractile si-
nuses, he replies — " Certainly, where there is a plurality of actively-con-
tracting vesicles without the appearance of the vesicula, as in CJiilodon Cucid-
lulus, we may, as before stated, attribute this to a kind of over-irritability or
constrictive spasm of the vesicula, and therefore consider that these vesicles
are accidental dilatations of the sinuses in connexion with it, as we may set
down the dropsical state of irimanto2yho7nis CJiaron (Ehi\), and other animal-
cules of the kind, to an opposite condition of this organ, viz. that in which it
is unable to reheve itself of its contents : this I have often seen occur under
my own eyes."

Many thanks are due to Mr. Carter for his painstaking investigation on
this subject. We are nevertheless very doubtful of several of his details of
structui'e. For example, he describes globular sinuses to appear around the
vesicle when an animalcule is exhausted, and those of Param^cmm to run
into radiating hyaline (moniliform) hues just before death and under a
certain amount of compression. Now, such conditions are ill-adapted to
accurate research ; and kno^ving how readily the integrity of the soft filmy
substance of the Protozoals disturbed, and diffluence induced, by unfavourable
external circumstances, the observation in question must be received " cum
grano salis." Moreover, looldng to most of his figures (which, we regi-ct,
are rather diagrams than exact delineations after nature), the impression
forces itself upon the mind, that he has many times mistaken the commence-
ment of diffluenco, and, in some instances, vacuolation resultiug from the
entrance of water into the tissues, for the manifestation of sinuses about
the contractile vesicle or scattered over the body in connexion with it.
Thus we should rather attribute the several vesicles this naturalist saw in
different numbers, and variously and irregularly dispei-scd, in different spe-

OF THE PROTOZOA. CILIATA.

321

cimens of Chihdon CuculMus, to one or other or to both of the conditions we
have mentioned, than to the purely hypothetical notion of the presence of a
state of "over-irritability" in a presumed vascular network. It is here
worth calling to mind Stein's belief that gentle pressure may give rise to a
stellate or branched appearance of the vesicle, and that the conflicting ac-
counts between Ehrenberg and Focke are reconcHeable on the supposition
of this occurrence (Stein, p. 240).

With reference to the hypothesis that the vascular apparatus is only ex-
cretoiy in function, we may remark that the exercise of such an office is no
bar to that of a respiratory function, since the latter is in itself in part an
excretory process, and among the lower Invertebrata many examples might
be cited where one and the same mechanism is equally respiratory and ex-
cretory in purpose.

We may add that Mr. Samuelson (J. M. S. 1857, p. 105) agrees wth
Lachmann in attributing to the contractile vesicle a cardiac nature, and sup-
phes the following particulars : — " In ParameMiin caudatvm a species of
AmpMleptus, a freed Vorticdla, &c., I have frequently and clearly traced
the canals that empty themselves into the contractile vesicle. In the second-
named species these canals were very perceptible ; they proceeded along the
edge of the body where the cUia were the most active (also probably because
there the current of fresh water would be constantly renewed), and, at the
embouchui-e into the central vesicle, swelled into a bulb-shape. In the Vor-
ticella, the contractile vesicle had a canal which either communicated with the
external surface through the oral aperture, or passed round the oral wreath.
I was inclined to beUeve the latter to be the case (perhaps my bias may have
influenced the observation).

" In certain Infusoria there appears to be a more active vital power than

in others. Thus in Glaucoma (especially such as are probably larval

forms), the contractile vesicle appears to have the power only to form a row
of auxiliary vesicles around it, whilst in Amphileptus (which approaches the
Planarians in its character), the Setifera or bristle-bearers, and other types
it is more powerful, and the fluid is ejected with sufficient force to work its
way into the body, and form canals or arteries, however primitive they may
be. The progressive vitality I have often noticed in the same form at dif-
ferent stages of its growth."

On a survey of the facts and opinions now passed in review, it seems to us
that the contractile vesicle is a closed sac representing a central circulatory
organ or heart in its most rudimentary condition ; that this cardiac sac pro-
pels its contents through a more or less complex system of channels, probably
■waUed, extended through the cortical lamina of the body ; that the contents
represent a chyle or blood, formed by the process of digestion, and absorbed
by the vessels ; that this chyle is exposed in the cardiac pulsating vesicle
especially, and in the ramified channels less, to the indirect action of the water
incessantly introduced within the body, or constantly sm-rounding it exter-
nally, and thereby becomes aerated, and consequently in aU probability fur-
ther elaborated; lastiy, that the perfected chyle is circulated throuo-h its
channels, and brought by them into the immediate vicinity of the tissue in
which the most active vital changes are going on, and Avhich, on account of
its higher differentiation, espcciaUy when in the form of cUia, integument
&c., demands the greatest supply of nutritive matters to repair its waste and
to provide for the processes of gro^vth and development perpetually nroeeed
rng in it or m its appended organs.

Since the foregoing review of the structure and functions of the contractile
vesicle was wntten, Lieberkiihn's valuable contribution, founded on orioinal

322

GENEEAL HISTORY OF THE INFUSORIA.

researches cliiefly concerning Bursana and Ophryoglena, have come into oui-
hands {A. N. H. 1856, xviii. p. 323). Since the introduction of it piecemeal
in our history of the organ would hoth have sacrificed its merits a.s an original
essay and have disturbed the continuity of our own account, we have deter-
mined to reproduce it here as a supplement.

After describing the existence of two vesicles in Ophryoglena and Bursaria,
one near the mouth, the other situated posteriorly, he goes on to say that if
we examine a Bursaria jlava containing only the smallest forms of the
strongly refractive granules, " with a power of 300 diameters, we perceive
near the sui-face a quantity of light streaks, which run together towards the
contractile vesicle from the anterior and posterior parts of the body, in more
or less considerable curves. In each streak we detect an extremely dehcate
but perfectly distinct canal, terminating ultimately in the contractile vesicle ;
its walls and its contents are readily distinguished by their different refrac-
tive power. When one of these canals is traced backwards from its orifice,
we may often perceive, after it has inm a short distance, a ramification : this
may frequently be traced to one of the extremities of the body, and some-
times it gives off another branch ; ultimately the canals become so excessively
fine that they ai'e invisible. Their opening into the vesicle and their course
in running from it are seen very distinctly when the contractile vesicle is
turned directly upwards ; we may then recognize how the canals run between
the contractile reservoirs, which lie very close to the surface of the body, and
between the surfaces of the body iaside the cortical substance ; and the ori-
fices may likewise be seen. Another remarkable position is when the nucleus
is turned next the observer at the surface of the body ; the canals are then
seen remarkably clearly on its bright backgroimd. A few canals always run
over directly, with a slight curvatui-e, towards the posterior part of the mouth.
When the animalcule lies so that the contractile vesicle appears at the
margin of the body, there is sometimes an appearance as if one or more of
the canals opened exteimaUy at this point ; but close examination shows that
they curve round and run towards other parts of the body.

" The number of vessels opening into the contractile vesicle in Bursaria
jlava is about thii'ty ; this number, or a few more or less, existed in aU the
specimens which I examined in reference to this point. They are ajjparently
uniformly distributed over the whole surface.

" The specimens of Bursaria Jlava with two contractile vesicles have the
system of canals double, each system grouped independently around its re-
servoir. The canals of the posterior reservoir stretch into the district of the
anterior ; but I have never been able to detect any communication between
the two. In the Ophryoglena: from the Spree veiy little could bo detected
of the canals, even when the interior of the body contained only sHghtiy re-
fractive substances. When a suitable specimen is somewhat compressed be-
tween the glasses, so that it cannot move about, the vessels are especially
seen when they have the nucleus for a background, and when they end in
the contractile vesicle.

" I have never been able to trace any vessels into the interior of the body
— for instance, towards the nucleus. I am also ignorant at present whether
that part of the contractile vesicle which is turned toward the centre of the
body of the animalciile receives any vessels.

"Both Bursaria jlava and Ophiyoglena jlavicans belong to those Infusoria
in which the contractile rcser\'oirs may assume tlie weU-known stellate form.
Von Siebold describes this phenomenon in Paranucium in the following
words : — ' These pulsating spaces have a very striking shape ; they consist of
two central round cavities, around which stand from five to seven smaller

OF THE PKOTOZOA. CILIATA.

323

pear-shaped resei-voirs, with points directed outwards in the shape of a
star. In the p\ilsation of these strange star-shaped reservoirs sometimes
the stars disappear entirely, sometimes only the central roimd spaces, and
sometimes only the rays.' The opaque Bursarice exhibit this phenomenon
just in the same way as it is described by Von Siebold ; and those speci-
mens in which the vascular system can be detected, offer the explanation
of it. The small pear-shaped spaces are really the commencements of the
vessels, which expand with the accumulated fluid ; and the rays are the
further prolongations of the same, which may be traced to the ends of the
body.

" At the moment when the contractile vesicle has attained the greatest ex-
pansion (that is, when the diastole is terminated), it appears in the form of a
globe filled with colourless fluid, fi'om which the vessels run out on all sides
in the cortical substance as canals, apparently of equal diameter ; they have
at this time the smallest diameter they can assume at their embouehtu'e into
the reservoir. In opaque specimens, this is the moment when the opened
contractile vesicle is observed. A little before we observe the commencement
of the systole, the vessels begin to expand slowly, at points distant about one
diameter of the contractile vesicle from the surface of the latter, to many times
their original size. The more the systole progresses, the wider and longer
become the swollen places, and they approach gradually to the contractile
vesicle. If we make an observation at the moment when the diameter of the
contractile vesicle is diminished to about one-fourth of its original size, the
shape of the apparatus agrees in. all essential points with the weU-known
stellate figiu-e represented by Dujardin ia Paramecium Aurelia, with the
single exception that the embouchures of the rays are distinctly visible, and
theii- peripheral prolongations run out widely iu the form of canals over the
entire animalcule. Opaque specimens of the Biirsaria display the phenome-
non only in such a degree that the rays terminate in delicate attenuated
points, at a distance of about one diameter of the reservoir from the latter.
"When the contractile vesicle has closed completely, the fusifonnly- expanded
vessels only are seen, as they run together with their apices to one point.
This completes the systole. The diastole then recommences. If we examine
the animal at the moment when the reservoir has again attained half its
greatest diameter, we find a totally different appearance from that at the cor-
responding epoch of the systole. The vessels are not expanded noAv in the
form of a spindle, but of a funnel, with the base of the funnel in the contrac-
tile vesicle, and the point prolonged out into the vessel. This is the form
which Ehrenberg has figured in Paramecium Aurelia, only omittino- the fui-
ther prolongations of the vessels. Von Siebold rejects Ehi-cnbei-g's fio'iu-e
and recognizes Dujardin's; but both are really correct, only representin"-
different instants ; Dujardin gives a stage of the systole, Ehi-enberg of the
diastole.

" The more the contractile vesicle now expands, the more is the depth of
the funnel decreased, and its diameter proportionately increased ; or, in other
words, the vessel expands only at its embouchure, and the depth of the ex-
panded part decreases in proportion with the advance of the diastole. In
opaque BursaricB we sec at this time only the contractile vesicle produced out
in various directions into short funnel-shaped processes. By degrees these
processes entirely disappear,— the contractUo vesicle having expanded to its
original volume. We now see again how, from the fully-expanded contrac-
tile vesicle, the whole of the vessels run out in the cortical layer in aU di
rections, as slender streaks; in opaque specimens only the contractile reser
voir IS visible.

T 2

324

GENERAL HISTOHY OF THE INTDSOEIA.

" The processes above described are those usually observed when a suitable
specimen is placed so that it cannot move, or only move veiy little, upon the
slider. If, however, a Bursaria is compressed somewhat more with the co-
vering-glass, or if the water on the slider is almost all evaporated, some other
peculiar phenomena present themselves, not only in the contractile vesicle,
but in the vessels. The last diastole coming perfectly to rest, and nothing
unusual being observed, except that the reservoir is more elongated, with the
systole appear suddenly two contractile vesicles instead of one ; that is, a
portion of the surrounding substance makes its way across the middle of the
contractile vesicle while it is contracting, and thus divides it into two parts.
Each of these two new reservoirs has its own systole and diastole. In most
cases their contractions do not occur at the same moment. Each is in con-
nexion with those vessels which opened into it before the separation. The
vessels exhibit the same play as if there were but one iminjured contractile
vesicle. Sometimes the two reservoirs reunite into a single one. I saw this
happen during a diastole which occurred exactly simultaneously in both : they
advanced near together, projected out points toward each each other, which
came in contact and formed a dumb-beU-shaped resei-voir ; and this was ra-
pidly converted into a globular vesicle, which contracted and expanded as at
the origin.

" Von Siebold has already observed in Phialina vermicularis, Bursaria
corcliformis, &c., ' that in strong contractions of the whole body, a largish
round pulsating space was draAvn out longitudinally, constricted in the mid-
dle, and at length was separated into two smaller round spaces — exactly as
occui's when a drop of oil is separated into two portions.' Dming the above-
described alterations in the contractile vesicles, alterations ordinarily take
place in the vessels also. Thus expansions appear in them at points lying
very distant from the contractile reservoirs. These enlai-gements are not,
however, subject to rhythmical disappearance and reappearance, but are per-
manent ; they are filled with the same colourless fluid as the conti'aetile vesi-
cles, and are mostly globular or ellipsoidal. If such enlargements of the vessels
are seen in specimens which, from unfavourable optical conditions, do not
display the vessels themselves, they may be taken for vacuoles (in Dujardin's
sense). Their connexion with the vessels, and their mode of origin, which
is readUy accessible to observation, prove that they are totally distinct from
the vacuoles in the interior of the body, part of which contain nutrient sub-
stance, while part do not.

I have not succeeded in any case in isolating a membrane of the contrac-
tile reservoir or of the vessels. I find no trace of cilia in the interior of the
vascular system. This alone suffices to distinguish essentially those Infusoria
furnished with vessels fi-om the Distoma-cmhYjo in which G. R. Wagener has
discovered ciliated vessels.

" Diiferent hypotheses have been put forth in explanation of the function
of the contractile vesicles. There is a detailed accoimt of these in Claparode's
paper on Actinophrys. Claparede rightly explains the contractile vesicles as
organs of the circulation. As to the direction in which the fluid flows in the
vessels, nothing can be directly observed in most cases, since we cannot per-
ceive in the fluid any solid corpuscles at all similar to the blood-corpuscles of
other animals. Is it a perfect circulation ? or does the fluid flow back again
in the same vessel in which it has been propelled forward by the contractile
vesicle ? or are the contents of the contractile vesicles constantly expelled
externally? Tlie last view has been set up by Oscar Schmidt. He states
that he has seen the place of exit in the genera Bursaria and Paramecium.
Claparede is opposed to this, since, in the most minute examination, lie was

OF THE PROTOZOA. CII-IATA.

325

unable to discover that the contents of the contractile vesicle were expelled
externally in the systole. Actino^hrys is better suited to the settlement
of this question than a ciliated Infusorium. I have many times sought for
currents in the fluid surrounding Actinophrys Sol and A. Eichhornii, when the
fluid contained masses of fine globules immediately in front of the projection
of the contractile reservoii- ; but I have never seen, any more than (Jlaparede,
any corresponding displacement when the vesicle contracted. In Bursaria
leucas, B. Vorticella, Paramecium Aurelia, and P. Chrysalis, I obtained the
following results :— The contraction takes place exactly in the manner de-
scribed by Schmidt ; the vesicle contracts from the interior of the animalcule
towards a point lying near the surface, and it expands on the entrance of the
fluid in such a manner that it increases in diameter gradually from the surface
of the animacule inwards toward the centre. But does this teach iis what
Schmidt concludes from it, that the reservoir expels its contents outwardly
every time when it contracts toward the outside, and becomes filled fi'om without
when it expands toward the interior ? If the contractile reservoir- is attached
by that part turned toward the surface of the animalcule to the internal surface
of the cortical substance, while the portion projecting into the interior of the
body is free in the soft medullary mass, "sviU not the contraction take place
from within outwardly, and the expansion from without inward, whether the
fluid flow inwards or outwards ? In ActinopJirys, sometimes in Arcella vul-
garis, and in Urostyla grandis, a totally different import must be attributed
to the contractile reservoir, if Schmidt's criterion be valid ; for here the re-
servoir does not contract toward the surface, but toward the interior of the
body, and forms an elevation on the siuface when it becomes filled, as de-
scribed minutely in Actinophrys by both Von Siebold and Claparede. But
it is not on this alone that Schmidt rests his opinion : he asserts that he has
observed also an actual external orifice of the contractile vesicle. I must
admit that Bursaria Vorticella has a distinct orifice at the hinder part of the
body, and this exactly at the place to which the contractile vesicle contracts
until it vanishes. But regarding this orifice which I saw, only so much is
established — that it is the anal oiifice which Ehrenberg has ah-eady described.
I have seen the emergence of remaius of devoured substances, of loricae of
Bacillaria, of fine undetenninable granules, &c., fi-om this veiy hole, so fre-
quently, that there can be no doubt on this point ; and it is even not rare for
a corpuscle to slip out from the anal orifice dming the diastole, — that is to
say, at the very time when, according to Schmidt, the fluid should flow in
i from the outside. I found the Bursaria just named during spring and sum-
mer in standing water near TempeUiof ; it agrees in the main with Eliron-
berg's Bursaria Vorticella. The buccal orifice is situated as in Bursaria
truncatella, in which, however, I did not obseiwe any contractile vesicle at
the posterior end of the body. The specimens of B. Imncatella I observed
I were all about ^ of a line or more long, those of B. Vorticella at most ^
! of a line. The latter is in any case not a Leucophrys ; therefore, in case
I Ehrenberg considers his Bursaria Vorticella a Leucophrys, it is a different
animalcule from the latter. I was equally unable to satisfy myself of the
correctness of Schmidt's view in the Paramecia. When a specimen of Para-
mecium Aurelia lies so that the contractile vesicle, either the anterior or pos-
terior, is seen at the margin, it appears, under certain circumstances, as though
a short canal ran directly out through the integument of the animalcule •
but in reaUty it only runs into the integument, and turns round toward the
side of the body directed away from the eye : I found the same in Parame-
cium. Chrysalis also : it was always one of the rays of the contractile vesicle
which presented to Schmidt the appearance of an external orifice. The same

326

GENEEAL HI8X011Y 01' THE INFUSOEIA.

is the case in Bursariaflava, v^here I could always trace the curvature of the
vessel toward the opposite side of the body most distiactly. F. Stein strongly
questions the external opening of the contractile vesicle in the Vorticellce.
Hence it is clear that the explanation of the contractile vesicles as part of a
water-vascular system is unproven.

" Is it, however, established, on the other hand, that the contractile reser-
voirs pour back their contents agaia into the parenchyma whence they re-
ceive it, as Von Siebold says ? And if this is the case, how does it happen ?
Everything indicates most strongly that the contractile vesicles are filled out
of the vessels during the diastole. We see how, during this process, the
swoUen part of the vessels near their embouchure gradually or suddenly re-
tiu-ns to its smallest diameter as the stellate figure vanishes ; and I have
observed a part of a vessel ioflated with the fluid, originating at the extreme
end of the animalcule, traverse the whole distance up to the contractile vesi-
cle dming a single diastole. This phenomenon may be supposed to show that
the absorbed fluid which had inflated the vessel into a globule, flowed during
the said period into the contractile reservoir.

" But if there is a fair presumption that the conti'actile vesicles are fiilled
out of the vessels, the above observations teach us nothing whatever on the
question as to where the fluid flows during the systole.

" I have hitherto only become acquainted with one fact relating to this point.
In Bursaria Vorticella we may detect the following fact : as soon as the con-
tractile vesicle which lies at the posterior end of the body has contracted, we
may observe at the margins of the animalcule, in its usual position of swim-
ming, that two long narrow cavities originate, filled with transparent colour-
less fluid ; and these stretch fi'om opposite the mouth as far as the region of
the contractile vesicle. They both gradually enlarge, and thus approach near
to the anal point ; here they meet, lose their often veiy ii-regular form, and
change into the globular : the remaining contents of the body are displaced
upwards by this ; and then these globular reservoir's contract until they
vanish, without it being perceptible where the fluid has been driven to ; after
some time the narrow light streaks reappear, and the process is repeated
in the way above described. The aflPerent canals, therefore, are not filled
at the commencement of the systole ; but must this not be so much the
more expected if the fluid flowed back in the same path as it came in, the
vanishing of the contractile vesicle taking place much more rapidly than
its production ?

" I have never yet found in any Infusorium special canals in which the
fluid is seen to flow back into the body dming the systole, and which would
give the means of a perfect circulation."

Nucleus, Nucleolus. — A most important internal organ remains for
description, viz. the nucleus. This name, if not accurate, is convenient to de-
sigTiate the stnicturc in question : it took its rise in the hypothesis of the
unicellular nature of the Ciliata, and has ever since replaced the name
" testis," or male spei-matic gland, assigned it by Ehrcnberg on the sup-
position of its being the male reproductive organ in these presumed herma-
phrodite beings. Indeed, when viewed as the centre of reproductive activity,
or, in Prof. Owen's phraseology, the seat of the * spermatic force,' the Berlin
naturalist's name for it does not appear so inappropriate ; nevertheless no real
homology can be said to exist between the testis of higher animals and tliis
body, Avhich, on the contraiy, has several points of analogy, at least, with the
nucleus of plant-cells ; nor can a hermaphrodite natiire be rightly ascribed to
the Ciliata.

The nucleus is present in aU the Ciliata, and is mostly veiy readily seen,

OF THE PROTOZOA. CILIATA.

327

imless the body is much occupied by food and opaque particles of any kind.
If not at once appai-ent, it is demonstrable by the disniption of the body by
pressure ; by the process of diffluenco, which disperses the surrounding tissues ;
or by the addition of acetic acid, which dissolves the rest of the animal,
lea\'ing the nucleus more or less completely isolated.

It occui's as a well-defined, finely-granular, more or less opaque body,
having a more solid look than the surrounding parts, and frequently also
a tawny or slight yeUow blush (XXIX. 28 c, 30 c, 48 c; XXX. 1, 11
VZh, 27 /). It varies both in position and shape in different species, and
either presents one or more internal spots or small bodies of a circular outhne
which represent the nucleolus or nucleoli, or this organ may appear as a
distinct appendage to it (XXVIII. 9-15 ; XXIX. 28). The nucleus is im-
bedded in or closely united with the cortical lamina ; and although it may be
thrust aside by the impetus of passing particles of food, it retains its hold.
Under the usual point of view of an animalcule, its position wiU look more
central than it really is ; for it is either in advance or in rear of the real
centi'e, or to one side or other of it, and often lies across the alimentary tube
when elongated or band-hke. But what is curious about this organ is, that
it is not at all firmly fixed in its position, but is pushed forward or backward
to one side and to the other by the movements of the animal, particularly by
those of the retractile cUiary wreath, and also by the ingestion of food. This
may be witnessed in Opercularia and Epistylis. Lastly, even in examples of
the same species its position is not constant.

The usual figure of the nucleus is circular or oblong, but it may be clavate or
reniform, or sinuous and band-like. The first type of outline prevails in Para-
mecium (XXIX. 28), Colpoda (XXIX. 37), Nassida (XXVIII. 1), CJiihdon
(XXIX. 48), Spirochona (XXX. 17), and Stylonycliia (XXVIII. 10 d). A
reniform or kidney-shaped one is seen in Epistylis plicatilis, in Opercularia
articulata (XXX. 1), and in 0. berberina ; a horse-shoe figure in Vorticella and
Zoothamnium ; whilst in Epistylis brancliiopJiila, in Ophrydium (XXX. 5, 6),
Carchesium, Trichodina (XXIX. 16, 17), Lagenophrys (XXX. 29, 30), '&c!
it is still more elongate and band-like and much curved, or actually sinuous]
Cohn represents it as having a thick clavate figure in Nassula elegans. The
figure, moreover, is very much modified during the reproductive processes
and in the metamorphoses which befaU some at least of the Ciliated Protozoa •
these modifications, however, we shaU not here consider, but reserve them to
the details on development. Again, even among examples of the same species
sUght variations occur in length and width, and in curvature or sinuosity'
where no reproductive act is discernibly in progress. Lastly, not a few of
the nuclei, which are at first sight simply oblong, are, on closer examination
seen to have a depression or sulcus on one side, and consequently to be strictly
speaking, bean- or Iddncy-shaped. Tliis is exemphfied in the nuclei of Para-
mecium, certain Nassidce, and in Prorodon.

Where the nucleus is elongated, it is a common event to see it bent par
tiaUy round the phaiynx or the oesophagus, at some little distance from it'

The nucleus being the last of the soft contents to break up after death
is presumably of a more soUd texture. Its tissue may be described as
normally homogeneous ; but various changes are ever occurring in it render
ing it at one time more transparent, at another more granular and' opaoue"
It must owe a certain degree of resistance to external injuries to the fact
that It is enclosed by a tough elastic membrane or sac, which sometimes is
separated from it by a clear interspace or areola, but at other times is closelv
adherent, and only demonstrable by artificial means, such as the appUcation
of chemical reagents, or of a solution of potash, or of acetic ac d- thi^

328

GENEHAL HISTOEY OF THE INFUSORIA.

happens in Vaginicola. When loose, this membrane not unfrequently falk
into plaits or folds. It is represented in Cohn's figure of the nucleus of
Nassula elegans as a very distinct and stout tunic.

The rule is, that the nucleus is single, and it has been assumed as a fact'
that the appearance of a double nucleus or of two nuclei is a general indica-
tion of the approaching or progressive act of fission. However, Stein in a
recent figure of Stylonychia mytilus (XVIII. 10), delineated in Carus's Icones
Zootomicce, represents two ovoid nuclei as present without the accompanying
process of self- division. In Chilodon Cucullvlus, he also represents the
nucleus (XXX. 48 e) to be composed of a moderately thick external or cor-
tical portion surrounding a clear cavity, in the centre of which the opaque
solid nucleolus is placed. The cortical lamina, he afiirms, consists of the usual
homogeneous granular substance which makes up the mass of most nuclei,
but rather firmer ; and its internal free surface towards the cavity is, he
says, undulated or dentated. The interspace between the nuclear lamina
and the nucleolus is not always clear, but occasionally occupied by a cloudy,
finely-granular matter, — whence the nucleus acquires rather the characters of
a homogeneous tissue, having a central, weU-defined nucleolus. Although
the last-named structure is probably never absent, it has nevertheless escaped
Stein's notice in very young specimens. The nucleus of Spirochona in young
specimens is either sohd and homogeneous, or transversely divided into two
by a crescentic space (XXX. 28/) ; the nucleolus occupies the middle of the
nuclear cavity, and has around it a finely-dotted areola (XXX. 17).

In the case of Paramecium both Cohn and Stein describe the nucleolus to
be included in a depression or hilum on one side the nucleus. Like the
nucleus it is formed of a membranous coat and homogeneous contents (XXIX.
28 d) ; the connexion between the two appears to be only by the adhesion of
their membranes, an adhesion readily broken through by pressure or by the
action of acetic acid. Fiu'ther, in the long band-Eke nuclei, the nucleoli
seem to be multiphed in number.

On the subject of its chemical nature. Stein concludes from the reaction of
tincture of iodine, and of acetic acid with a solution of 'sugar, that the nucleus
is a proteine compound, like the other contents, except the fat-coi-puscles.

Although its ofiice in secreting a spermatic fluid may be justly called in
question (dii-ect observation being contrary to it), yet tliis so-caUed testis, or,
perhaps more correctly, this nucleus, certainly plays a most important part
in the well-obsei-ved mode of propagation by spontaneous fission ; for Avhenevcr
fission, whether longitudinal or transverse, is about to occur in an animalcule,
the fii'st change observed is a progressive constriction of the nucleus, suc-
ceeded by that of the body generally. This constriction goes on tiU division
is complete, eacli segment of the body being consequently provided -n-ith a
nucleus. The division of the nucleus, as an essential element in the process
of spontaneous fission, may be wcU observed in the transverse division of
Paramecium, Bursana, or Chilodon.

Professor Owen, in his learned and able Essay on PartJienogenesis, refci-s
to the initiative, assumed by the nucleus of Infusoria, in their reproduction
by spontaneous fission, between wliich and the essential contact of the sper-
matozoon with the germ-ceU, as a preliminary to tlie primary process of
self-division of the latter, in the com-se of tlie development of more perfect
animals, ho in(hcates an analogy ; and, after ha\nng completed the comparison
of the results in the two cases, goes on to say, — " This is certain, that the
analogy between these phenomena in the multiplication of the parts of the
germ-mass, and those of the nucleus in the multipUcation of monads, is so
close, that one cannot reasonably suppose that the nature and properties

OF THE PKOTOZOA. CILIATA.

329

of the nucleus of the impregnated germ-cell, and that of the monad can be
different.

" Therefore, I infer, that the nucleus of the Polygastric animalcules is the
seat of the spermatic force ; it can only he called testis, figiu'atively, it is the
essence of the testis. It is the force which governs the act of propagation by
spontaneous fission : and, if Ehi-enberg be correct, in viewing the interstitial
corpuscles as germ-eeUs (to which opinion Professor Owen iacHnes), these
essential parts of ova may receive the essential matter of the sperm from the
nucleus, which is discharged along with them in the breaking up of the
monad, which Ehrenberg regards as equivalent to an act of oviposition ; and
impregnated germ-ceUs may thus be prepared to diffuse through space, and
carry the species of Polygastric animalcules to a distance from the scene of
life of the parent " (p. 67, Ed. 1849.)

Lieberkiihn (A. N. H. xviii. 1856, p. 321) makes the nucleolus of import-
ance in founding specific characters. He says, that, excepting the eye-point,
the nucleolus is properly the only part which distinguishes Opliryoghna
jlavicans from Bursaria flava. — "This body," he proceeds to say, "is shaped
like a grain of barley, and is marked at each end with a few shai'ply- defined
streaks or furrows ; its length is somewhat more than of a millimetre,
its thickness in the middle about of ^ miUimetre. Its substance has a
stronger refi-active power than that of the rest of the body, but far less than
the fat-like globules. Under the highest magnifying power, no structure
could be distinguished, and it withstands for a considerable time the action
of water. The nucleolus is situated on the middle of the nucleus, which is
about one-fifth of the entire length of the animalcule, and its breadth in the
middle about one-third of its length .... It is of ovate form ; its substance
displays no recognizable structure.

" The nucleolus has very different characters in aU the specimens of Bur-
saria flava I have hitherto observed. It was always so small that it was
difiicidt to find it, and never became visible until the Infusorium was com-
pressed, while in Opliryoglena flava it may usually be seen thi-ough the
integuments. Its form is globular, and it presents no structiu'e. It gene-
rally adheres firmly to the surface of the ovate nucleus."

The same lesson concerning the utility of the nucleus and nucleolus in
distinguishing genera and species, might be gathered from the desciiptions
of Stein and others, which show clearly enough that these organs have a
determinate figure and relation in several genera, as, for example, in Spiro-
chona and Paramecium.

The figure of the nucleus and the relation of the nucleolus to it in Pro-
rodon teres and in Nassula elegans, are deserving attention. In the former
species the nucleus is represented as globular, with a nucleolus surmoimtino-
it (XXVIII. 9) ; in the latter, the nucleus is stoutly clavate, and terminated
by a small oblong nucleolus at its narrower extretnity. These woU-marked
peculiarities in the two examples named, coupled with the views of Li'ober-
kuhn just cited, and the conclusions of Stein and Balbiani concerning the
physiological relations of the two organs in question, wUl challenge for them
much more attention than they have hitherto received.

M. Balbiani has lately contributed to the French Academy two most im-
portant papers, in whicli he lias endeavoured to demonstrate a sexual ropro"
duction of the CiHata, the nucleus representing the female, and the nucleolus
the male, clement. In his first essay he illustrates his h jqiothcsis by reference
to Paramecium Bursaria {A. N. H. 1858, i. p. 435), and thus writes-—

"For several generations the Paramecia multiply by spontaneous scission
each of the two now inchviduals obtaining half the primitive iiucleus

330

GENEEAL HISTORY OF THE mPDSOBIA.

But under the influence of conditions of which wc arc still ignorant, the
species propagates itself in a very different manner, and in the midst of phe-
nomena far more complex than those which preside over the multipUcation
by fissiparity. In this new mode we shall see the actual anatomical sigmfi-
cation of the nucleus and nucleolus, the function of which, if we except the
division of the former of these two organs in the act of spontaneous division,
has hitherto been perfectly passive. It is, in fact, at their expense that the
male and female reproductive elements which characterize this mode of
propagation are formed.

" When the period arrives at which the Paramecia are to propagate with
concourse of the sexes, they are seen assembling upon certain parts of the
vessel, either towards the bottom, or on the walls. The copulation is always
preceded by certain prehminaries which are very curious to observe, but upon
which we cannot dwell here. Soon they are found coupled in pairs, adherent
laterally and as it were locked together, with the similar extremities turned
in the same direction, and the two mouths closely applied to each other. In
this state the two conjugated individuals continue moving with agUity in the
Liquid, and turning constantly round their axis. There is nothing, before the
copulation, to announce the considerable changes which are about to take
place in the nucleus, and the nucleolus which accompanies it. It is during
the copulation itself, of which the diiration is jirolonged for five or six days or
more, that their transformation into sexual reproductive apparatus takes place.

" The nucleolus has undergone a considerable increase in size, and has
become converted into a sort of capsule of an oval form, of which the surface
presents longitudinal and parallel lines or streaks. Kearly always, it soon
divides in the direction of its greater axis, into two, or more frequently into
foui', parts, which continue increasing independently of each other, and in a
very irregular manner, and form so many secondaiy sacs or capsules. At a
period which is stiU near that of division, these latter appear to be composed
of an extremely fine membrane, enveloping a bimdle of small, curved bacilla,
extending from one extremity of the sac to the other, inflated towards the
middle, narrowed towards the extremities. It is these which, when seen
through the enveloping membrane, give the capsule the striated appearance
which is characteristic of it, and which even exists in the nucleolus at almost
all the other periods of the life of the Infusoriimi. It also contains a perfectly
colourless and homogeneous fluid.

" At the same time the nucleus has also changed its form and aspect ; it
has become rounded and widened ; its substance has become softer and lost
its refractive power, and towards its margins it presents notches, which,
penetrating more and more deeply into its mass, isolate one or more frag-
ments, in which a sufficient magnifying power enables us to see a certain
number of small transparent spheres with an obscure central point. In other
cases the nucleus, whilst still almost entire, presents this aspect, and then
appears as if stuffed with these little rounded bodies, the analogy of which to
ovules cannot be doubted in the least. The evolution of the nucleus and
nucleolus being identical and progressing at the same rate in the two coupled
individuals, it foUows, if from this moment we regard the former as an ovary,
and the second as a testicle or seminal capsule, not only that each of them
possesses the attributes of both sexes, but that they fecimdate each other,
and sei-ve at the same time as male and female. As rcgiu-ds this fecimdation
itself, cveiything seems to prove that it takes place by means of an exchange,
made by the two couiilcd individuals, of one or more of their seminal ca])sules,
which pass, through the apertures of the mouths closely applied against each
other, from the body of one Paramecium into that of the other ; for, very

I

OF THE PKOTOZOA. OILIATA.

331

often, altlioiigh we may not be able to perceive this passage itself, we may
at least detect the moment when one of the capsides already engaged in one
of the mouths, is on the point of clearing this aperture. Does the exchange
which causes fecundation take place with all the capsules m a single copula-
tion, or in so many successive copulations with different individuals ? _ This
is a question the solution of which is not easy, and which, to keep within the
field of our observations, we shall not attempt to solve at present,

" However this may be, each capsule, after its transmission, still continues
to increase in size in the body of the individual which has received it ; for we
have never found any which had attained the limit of their development in
individuals which were still coupled. They then fi-equently attain a volume
greater than that of the nucleus itseK ; but there is nevermore than one that
arrives at maturity at th6 same time. When, having arrived at this state,
it is examined after being pressed out of the body of the animalcule to free
it fi'om the granulations which mask it more or less while there, it appeal's
under the form of a large ovoid body, the surface of which presents a multi-
tude of parallel strise directed longitudinally, and due to the arrangement in
series of the corpuscles contained in the interior. Compression, carried so far
as to cause its rupture, distinctly shows it to be formed by a membrane of
extreme tenuity, and contents, enclosing an innumerable quantity of small
fusiform corpuscles, of which the extremities are completely lost to sight in
consequence of their extreme fineness. As soon as they are free, these little
bodies show themselves to be animated by a vacUlatory and ti'anslatory move-
ment, which soon causes their dispersion in the circumambient fluid. These
ai-e the spermatozoids of P. Bursaria. Iodine, alcohol, and acetic acid instantly
stop their movements ; they are insoluble in the last-mentioned reagent when
concentrated, although this dissolves all the other elements of the body, with
the exception of the green granules.

" It is usually from the fifth to the sixth day foUowiug the copulation, that
the first germs are seen to make their appearance, in the form of small rounded
bodies, foi-med of a membrane which is rendered very evident by acetic acid
and greyish, pale, homogeneous, or almost imperceptibly granular contents^
in which neither nucleus nor contractile vesicle is yet to be distinguished'.
These organs do not appear until afterwai-ds. The observations of Stein
and r. Cohn have shown how these embryos quit the body of the mother in
the form of Acinetce furnished with knobbed tentacles — true suckers, by
means of which they remain for some time still adherent to the mother
deriving their nourishment from her substance ; but then- investigations did
not reveal to them the ultimate fate of these yoimg animalcules. I have
been able to follow them for a considerable time after they detached them-
selves fi-om the body of the mother, and have convinced myself that after
losing their suckers, becoming sm-rounded with vibratilc cilia, and obtdnino-
a mouth which first shows itself in the form of a longitudinal fui-row thev
definitely acquired the form of the mother, becoming penetrated in the same
way by the green granulations characteristic of this Paramecium, without
undergoing any more important inetamoqAoses."

At the time this fii-st record of his observations was read, M. Balbiani stated
that he had collected them from the investigation of six or seven species but
since that period he has pui-suedhis observations in several other species' and
completed some old ones previously interrupted fi-om want of materials
(A. N H. 1858, n. p. 439). In his latest paper, he enunciates the remark-

able statement that he has been led to regard, in a great number of cases
what neariy all authors have considered to be a spontaneous division in a
longitudinal direction, as a sexual union of two individuals. " Very often

332

GENEILVL HISTORY OF THI! INFTTSOHIA.

in fact, I have been able to ascertain that this state coincided with cer-
taia remarkable changes which took place in the internal organs of these
animals."

The following is the general summary of the results M. Balbiani has
arrived at : — " I. The corpuscle which, iu the Infusoria, has been desciibed
under the name of nucleolus, and which I have shown to be the male genital
gland, has hitherto only been indicated in a few rare species. In connexion
with this, I have examined a great number of individuals belonging to numer-
ous and varied forms, and I have convinced myself that, far from constituting
an exception, the presence of one or even several nucleoles was a nearly con-
stant fact in the different types of this class ; but frequently the simple or
multiple nucleole which they contain is so intimately confounded with the
substance of the nucleus, that it only becomes apparent when it is separated
therefrom accidentally by the action of reagents, or spontaneously at certain
determinate periods in the life of these creatui'es, principally at the time of
theii- sexual propagation. I have counted fourteen species in which this
organ was very evident to me, and in which I have also been able to follow
its evolution, to a greater or less extent, at the breeding-season, at the same
time that I was an eye-witness of the other actions which concur in assuiing
the reproduction of these animalcules by fecundated gei-ms.

" As regards the number and sitiiation of the testicular organ of the Infu-
soria, I have met with the following varieties. It is simple, roimded, and
lodged in more or less deep depressions of the nucleus in Paramecium Aurelia
and P. caudatum, and also in a third species, nearly allied to P. Bursaria, but
smaller and destitute of green granules. The genus Bursaria (B. leucm,
Jlava, and vernalis) also presents a simple nucleole situated in the vicinity of the
nucleus. The same thing occurs in GJiilodon Gucullidus. But with regard to the
latter, I must remark that I do not regard as the analogue of the nucleole of the
preceding species the corpuscle to which M. von Siebold has given this name,
and which is placed in the interior of the granular mass of the nucleus, in
the centre of a broad transparent zone. The true nucleole or testicle of
GJiilodon appears in the form of a small, rounded, briUiant grain, provided
with a proper membrane, and situated quite to one side and towai-ds the
middle of the nucleus. It is veiy easUy perceived in large specimens by
employing the action of reagents. As regards the nucleus and its internal
parts, I make no difficulty in regarding them as representing all the elements
of an ovum, of which the nucleole of the celebrated German naturalist would
be nothing but the gei-minal spot. The disappearance of the clear zone and
of its central coi-puscle in the animals which have just copulated, especially
appears to me to militate in favoiu' of this view.

" II. I have met with a multiple testicle in many species belonging to the
groups of the Oxytriclvina. and of the Euplotes or PJoesconias, including the
highest types of this class. In the genus O.vytriclia the two nuclei, which
are elongated in the dii-ection of the greater axis of the body, are each accom-
panied by a smaU, rounded, testicular body, veiy distinct from the correspond-
ing nucleus. There tire also two, placed one to the right and the other to
the left of the long nucleus, which is ciu-ved into the foi-m of a horse-shoe,
in Euplotes Charon and E. viridis. In the genera Styhnychia (S. Mytihis,
pustulata, and lanceoJata) and Urostyla (U. grand is) the nucleoles, to the
number of four or five, are distributed in two groups in the A-icinity of the
nuclei, of which the anterior is accompanied by two, and the posterior also
by two or sometimes three, of these little organs. They are remarkable from
their distinctly- rounded outline, their gieat refractive power, and tlicir
homogeneous structure. In Sjjirostomnm amhiguum, each of the gi-ains of

OF THE PROTOZOA. CILIATA.

333

the long moniliform cord which here replaces the oval nucleus of the other
species, gives lodgment, in a deep depression of its smface, to a small rounded
corpuscle, which corresponds with the nueleole of the preceding species ; this
bi-ings the number of testicles in this animal to forty-five or fifty. I have
only been able to perceive them in individuals which have been copulating
for a certain time, and by employing dilute acetic acid. It is very probable
that an analogous arrangement wall be found in the other types, in which the
nucleus is formed of grains placed in a single row, like a necklace, such as
Stentor, Kondylostomum, Trachelius moniliger, &c.

" III. The evolution of the male genital apparatus of the Infusoria, as just
characterized, in the other species of the genus Paramecium does not dififer
from that presented to us by P. Biorsaria. In the Oxytrichina each of these
organs remains entire, becomes enlarged, and exhibits in its interior, applied
against its waU, a thick granular body, furnished with a tubular appendage,
which projects into the cavity of the capsule, and appears to be open at its
free extremity. This tube, which seems to be an excretory duct, often
appeared to be filled with capillary filaments of extreme fineness, arranged
parallel to the axis of the duct in question, in which they were fixed by a
portion of their length, whilst the remainder, escaping by the orifice of the
tube, radiated in aU directions in the interior of the capsule. Subsequently
the granular body and its duct disappear, and the filaments, becoming free,
collect into a bundle, which fills the whole of the formative sac. Although
I have never seen them execute any movements, I do not hesitate in consi-
dering them as the spennatic filaments of these animals.

" rv. It is with equal certainty that we may call the nucleus the female
genital organ of the Infasoria, in opposition to the perfectly hypothetical
assertion of Ehrenberg, who regards it as the testicle. Its evolution likewise
only commences at the time of reproduction, and often during the sexual
union itself. In P. Aurelia and P. caudatum, towards the end of the copulation,
its surface is traversed in all directions by numerous furrows, which, penetrat-
ing deeper and deeper into its mass, finally divide it into a great number of
unequal and irregularly-rounded fragments, having a clear centre more or
less surrounded by granules. I should compare these with the first nidi-
ment of a viteUus, and the transparent central portion to a more or
less developed germinal vesicle. The fragments thus formed are soon dis-
persed in the surrounding parenchyma. Here a very small number of them,
almost always fom-, never more and very rarely less, complete their evolution^
and soon acquire the appearance of complete and well-developed ova. In
this state they present themselves in the form of small biiUiaut bodies ' per-
fectly equal in volume, shghtly oval, and of a bluish-grcy appearance ' Sve
may very clearly distinguish in them a finely-granular vitcUus, surrounded
by its proper membrane, which separates from it more or less after a few
moments' exposure to water. The germinal vesicle and spot are also visible
with a distinctness truly surprising, considermg that we have to do hero Avith
the smaUest of Uving organisms. I have met with these ova stiU enclosed in
the body of the animal on the seventh day after the copulation : thev no
longer exhibited either germinal vesicle or spot ; and theii- volume had slightly
increased. In the alhod species, P. Bursaria, the reniform nucleus becomes
imrollcd before brealong up, and in this state resembles the ribbon-shaped
nucleus of the Vorhcellm. About twenty or twenty-five of the frafrmcnta
produced from it contmue their development and become so many nerferf
ova. In the nucleus of ChUodon CuculMi^, also, wo observe, after the conu
lation, the disappearance of the transparent zone with its central obscure
spot. In the genera Styhnychia and Urostyla the ova are four in number

334

GENERAL HISTORY OF THE HTPtrSORIA,

as in Paramecium caudatum, but thoy are produced by a different mechanism.
Each of the two nuclei divides into two halves, as in the act of spontaneous
division ; and the four fragments thus produced form an equal number of
perfect ova. Lastly, in Spirostomum amhiguum, we have seen, in individuals
which have been copulating for some time, the forty or fifty grains of the
long flexuous cord which traverses the body become rounded and detached
from each other. But we have been unable to discover in these all the
characters of an ovum with the same distinctness as in the preceding species,
no doubt because they had not yet arrived at their complete development.

" V. I have not witnessed the deposition of the ova m these animals. It
is very probable that they escaped by the anus, or by some neighbouring
aperture. Thus, in the Stylonychiai, I have seen them collect in the posterior
part of the body, which bears the anal orifice, and diminish gradually in num-
ber from the first or second day after the copulation. It is a singular thing,
that about this period a round pale body begins to make its appearance in the
centre of the animal ; this becomes constricted about the middle, and recon-
stitutes the double nucleus of Stylonychia.

" VI. The Infusoria are destitute of copulatory organs. In most cases the
copulation is effected by simple juxtaposition, the two mouths establishing
the sexual communication (Paramecium, Bursaria, Euplotes, Ghilodon, Spiro-
stomum). In the Oxytrichina the union is more intimate, and goes so far as
to constitute a true soldering of the two individuals for more than two-thirds
of their anterior part. Any one who had not witnessed all the phases of this
singular copulation, would be unable to avoid regarding this state as a longi-
tudinal division, proceeding from behind forwards, in a single animal. But,
even if direct observation were wanting, the concomitant changes of the
internal organs, which are so characteristic, cannot leave the least doubt as
to the actual signification of this act."

Ovules. — In Ehrenberg's organology of Infusoria, ovules or ova assumed a
high importance. The structures he so designated had no distinctive features
assigned them, whereby they could be distinguished from other corpuscles
and granules in the interior ; and, in consequence, their existence could not
be confirmed by other microscopists, who for the most part declared that the
supposed ova were indifferently alimentaiy vacuoles, particles of food, fat
globules, or the ordinary granules of the interior. The general opinion became
pronounced against the very existence of ovules and of development by their
means, whilst the deposition of ova, which Ehrenberg believed he witnessed in
several instances, was explained to be an act of diffluence misconceived. This
explanation, for instance, has been given to his recorded observation and his
figures of the act of oviposition in Colpoda Cucidhdus, wliich represented this
animalcule as bm'sting and giving vent to strings of ova, which first ran
together ui a reticulate manner, and then, after a time, became individually
developed into young Colpoda;. According to the opposite view, the bursting
and extrusion of contents arc no other than the phenomena of diffluence and
the dispersion of particles of sarcodo, whilst the young supposed to originate
from those pai'ticles arc merely minute Monads or mouadiforra corpuscles
found in company with the Colpoda:.

One objection brought against the assumption of ova being ejected from
Protozoa in the exercise of a generative function is certainly frivolous — y\7..
that the empty or broken shells of the ova ought to be met with ; for the shell
of an egg, however useful in larger animals as a defence against injury, is no
essential part of an ovum from which a new being can be developed.

Altliough the existence of ova among the Ciliata has been denied by the
great authorities on Infusoria — by Kiilliker, Siebold. Leuckart, Cohn. Stein.

OF THE PROTOZOA. CILIATA.

335

Van der Hoeven and others, yet it has latterly foimd two advocates in Prof.
Perty and Mr. Carter. The latter wi-iter (A. N. H. 1856, xviii. p. 225) can
adduce little dii-ect evidence to support his views, and seems to rest more
weight upon argument from analogy with AmoebcBa, Arcellina, Astasice, and
Euglence, in all which he has satisfied his own mind of the presence of ovules,
and of their development in the two latter genera. "The same kind of develop-
ment," he writes, " of the ovule probably takes place in aU the Ehizopoda as
in Spongilla and in Astasia and Euglena:" but this is not proving that Rhi-
zopoda are developed by ova; and the entire value of the presumed analogy
with Astasice depends on our admitting a natural affinity and close similarilyr
in organization between that family and Ciliated Protozoa, on the one hand,
and Ehizopodous Protozoa on the other. Indeed, we imagine the prevailing
opinion to be, that the history of development of Astasicea corresponds rather
with that of vegetable organisms than with that of the Protozoa ; for this so-
called ovular reproduction of the Astasicea certainly seems analogous with the
development of zoospores in many unicellular Algae.

To recur to Mr. Carter's statements, he tells us he applies the term
" ovules " to " a number of discoid or globular nucleated cells, which appear
together in the sarcode of some of the Infusoria ; " and he subsequently pro-
ceeds to uphold his views by his own personal observations, and by inferences
drawn from others. " In many of Ehrenberg's enterodelous Infusoria it is
not uncommon to see a number of defined globular bodies, of nearly equal
size and of a faint opaque yeUow colour, which closely resemble ovules —
e. g. Amphileptus fasciola (Ehr.), Himantophorus Charon (Ehr.), &c. ; nor is
it improbable that many of his Trachelina, which come near Planaria, possess
ovules similar to those which are found in the latter ; but, from being so much
mixed up with the spherical cells, pass equally unnoticed while in, as well as
when out of, the body, under such circumstances. M. J. Haime, however, has
distinctly seen iastanees in which these bodies have been ejected from Infusoria,
and have passed into locomotive animalcules under his eye. Thus he states
that in Plcesconia they form a group of from forty to fifty in the middle of
the body, are round, issue one by one, remain tranqtdl some time, then deve-
lop two filaments, one in front, the other behind, and move about rapidly.
In an ' imdescribed ' species of Dileptus they are whitish, and form a wreath
extending almost throughout the whole length of the body, become yellow
towards the anal extremity, where they pass out with the remains of the
food, soon develope two opposite filaments, and move about rapidly. In
Paramecium Aurelia, M. Haime states that an ovary appears some hours
before death, about the middle of the body, which becomes fiUod with about
sixty little nuclei : these increase in size, burst the ovisac, and thus pass into
the body of the parent, from which they finally escape by an openino- in the
tegumentary covering, formed by the diffluonce of the latter ; and the ovisac
follows them."

Perty has used groat dUigenco in searching for the presence of ovules or
more accurately, of germs (Blastien), and has adduced various arguments for
their existence. He states (op. eit. p. 66) that their aspect is distinctive
although their colour varies in different species, that, unlike food thev re '
tain their form, increasing only in size, and that, on the dissolution or brealdne
up of the animalcules, they display themselves aa free individualized stmc-
tures. It 18 only, he adds, in incomplete forms, in young and imperfect beines
that any doubt can exist respecting the character of these corpuscles Ovulir
development does not take place aa Dujardin surmised, by detached morsels
of the saroode, nor by ova such as Ehrcnberg supposed, but by a peculiar
set of bodies, onginatmg m the interior of the animals, and progressively

336

GENEEAL HI8T0EY OF THE INFUSOBIA.

imiltiplied. Their minuteness is a bar to observation ; and it is pnly by the
concurrence of favourable circumstances — by the presence of the ovules in
their first, intermediate, and finished stages — that they can be satisfactorily
made out, as in Nassula aurea, Eaglena viridis, Clwnemonas bicolor, &c.
rission may be several times repeated ; but the formation of germs takes place
at the expense of the contents of the parent.

The unusually small size of many animalcules is another argument advanced
in favour of propagation by germs or ova, since the act of fission is limited to
a certain size, and the natural characters of the species are to be preserved.
Thus Pertymet with examples of Kerona piistulata as small as 1-70"', which
could scarcely originate from fission. They were exactly like the original
animalcule except in being more round. Specimens of PUuronema crassum
occur no larger than 1-90"', devoid of molecules, more transparent and slender
than old ones, with a more pointed apex, but otherwise theu- coimterpart.
Again, Nassula aurea varies from 1-150"' to 1-12"' ; and in those of 1-50"' the
rudiments of the " dental" apparatus are distinguishable. AxiAmphileptus mo-
niliger, 1-6"', having a very short neck, was distended by 100-150 germs or
ovules surrounded by some thousands of fine molecules ; that these were neither
vacuoles nor stomach-sacs was seen at places where they displayed themselves
as individualized corpuscles. Moreover there were no other animalcules or par-
ticles of food in the glass containing the Amphileptus, and all the germs were
imiform in size, in hue, and in refractibility, and readily distinguishable from
some swallowed Infusoria present in some spots. The gi'een spheroidal cor-
puscles in Paramecium versutum, having a medium size of 1-450"', are true
ovules: they do not change colour, like the green nutritive matters of Infusoria,
to yeUow, red, or brown ; and when the animalcule is left diy by evaporation,
they become isolated. Although no germinal speck is discoverable in these
bodies as in ordinary ovules, yet it is remarkable that a fold, streak, or darker
space is visible. Small specimens of this Infusorium also occur in which the
ovules are colourless or pale green ; and on one occasion Pertj' saw, amid the
fully-developed individuals, oval greenish animalcules of about 1-60"', which
seemed no other than the escaped genns of the Paramecium.

Such are some of the principal observations Perty appeals to in order to
substantiate his hypothesis of internal germs and of development from them.
He has given, in illustration, a number of figures ; but they are too rudely
drawn to efficiently answer their object ; and we must confess our inability to
receive the fact of the existence of ova or germs as at all demonstrated in the
Ciliata either by the researches of Mi*. Cai-ter or of Perty. The discoid or
globular nucleated cells which the first- named writer makes out so clearly in
the Astasicea, are merely supposed to be represented by certain " defined glo-
bular bodies of nearly equal size and of a faint opaque yeUow colour, which
closely resemble ovules " (why ?), not uncommon in many ciliated Protozoa,
e. g. "Amphileptus fasciola, Himantopliorus Charon, &c." Such evidence is
purely presumptive, and is little aided by M. Jules Haime's anomalous obser-
vations, llespccting Perty's arguments and reported phenomena, it may be
objected that he does not establish his attempted rigorous description of germs
— does not show their distinctive peculiaiities as stated, and seems to liave
confounded together various internal bodies in his description of germs. Tlius
in the Paramecium versutum (which he presumes to be the same animalcule
described by Colin as Loxodes Bur sari a) the green spheroidal corpuscles
look to be nothing more than the chlorophyll globules pointed out by
Cohn and Stein. Again, of the ambiguous corpuscles in other Protozoa cited
as ovules or genns, it is simply from their doubtful character tliat tlus
can be presumed ; for our knowledge of the contents of the Ciliatfl, of the

OF THE PKOTOZOA. CILIATA.

337

changes they may visibly undergo from tlie action of external agents, from
jige, and other conditions, is at ^jresent too imperfect to signalize certain par-
ticles, definable by no sufficient characteristics, as special structures, such as
ova, — unless, indeed, we can watch their origin, growth, extrusion, and de-
velopment into animalcules assuming the particular form and organization of
the ptirent animal at an earlier or later date. Pcrty, indeed, has imagined — ^not
proved — certain minute organisms floating in the \icinity of an animalcule,
having about the same size as the supposed internal ovules, to be the young
resulting from those germs ; and although it cannot be denied that he is in
the right, yet it is for him to show that he is so, by elucidating the phases of
development ; and we must always keep in view the very erroneous fancies
Avhich result from these supposed relations between contiguous organisms,
very probably only accidentally brought together, — of which we have an
illustration in the visionary hypotheses of spontaneous development and
ascendant embryogeny put forth by Gros and others.

We have stated the preceding objections against the particiilar statements
of Cai'ter and Perty, and not against the hypothesis of the production of in-
ternal germs ; for sufficient examples are on record of the production of such
germs and of living embryos within animalcules, after preparatory develop-
mental changes, fi'om the fission and breaking up of the nucleus. Before leaving
this hypothesis of the existence and development of internal geiTQS, it is but
right to mention that it has been received, among others, by Eckhard and by
Oscar Schmidt, both of them supporters, in almost all their details, of Ehren-
berg's views, and who are believed by most authorities to have too much the
character of advocates of a particxilar theory, to discuss or to observe in ge-
neral without prejudice. To allude briefly to their observations, Eckhard
(A. N. H. 1847, xviii. Suppl. p. 446) in the first place remarks, as others
have done, on the very different sizes of animalcules of the same species, as
a proof of ovular development, arguing that the very smallest cannot result
from fission or gemmation. To this he appends an observation made on
Stentor cceruleus (XXIX. 8), which, from its completeness and apparent
truthfulness, desei-ves quotation when we come to speak of the development

Kof ova. Schmidt corroborates Eckhard's statement of tlie production of
living germs from Stentor cceruleus, and affij-ms, in addition, that germs are
frequently extruded and developed outside the parent, and that their subse-
quent development from minute globular and conical transparent and almost
colourless organisms, with long cUia, may be watched through all the inter-
mediate stages imtil the complete animalcule, ynth. its spiral ciliary wreath
and mouth, is perfected.

The preceding speculations on the development of ovules and germs havo
their importance materially modified by M. Balbiani's recent researches and
hypotheses respecting the prevalence of a sexual mode of reproduction anion"-
the CUiata, as detailed above (pp. 329-334). °
Spermatozoids ( ? ). — This term is provisionally a^jplicd by Mr. Carter to
granules originally developed from the nucleus in Ama'ba, Euffh/jjJia, and
I SpongiUa, and supposed by him to impregnate the o^^llos. " Wi'tli reference
' to the organs of generation,"' he wjitos (^'l. N. H. 1856, xviii. p. 228), " iu
I the other Infusoria, I can state no more than that, altliough there is a fusifoi'm
nucleus va. Oto&toma (XXVIII. 2.'5, 2()), I have also constantly seen a bunch
of string-like filaments floating about its interior, wliich appeared to bo at-
j tached near the buccal cavity ; and although I coidd make out nothing more I
I could at tlie same time only liken these to the generative apparatus in the
Plnnaria mentioned, which floats round the bTU'cal cavity and upper part of
1 the membranoiLs stomach in a similar manner."

z

338

GENERAL HISTOEY OF THE INFUSOHIA.

The notice of Mr. Carter, of the peculiar structures he would designate
spermatozoids, is as yet unconfirmed by other writers ; and we must therefore
consider their nature and purpose still sub judice.

Since the above was written, M. Balbiani's researches (A. N. H. 1858, vol. i.
p. 435) confirm Mr. Carter's opinion so far as relates to the development of
spermatozoids or male reproductive elements, but refers their origin to the nu-
cleolus instead of the nucleus. In om* history of these last-named organs, we
have presented M. Balbiani's views, andnmst here refer back to them (p. 329).

AccEssoET Contents : — Geanules ; Molecules ; Spheeical Cells ; Sup-
posed Glands. — Among the remaiuing contents of the Ciliata are numerous
granules, molecules and fat-cells. Mr. Carter {A. N. H. 1856, xviii. p. 121)
makes a distinction between granules and molecules — two terms which by
others are veiy loosely used and not specially defined. This writer, however,
would restrict the term molecules (moleculee) to coloui'less granules more
minute than those he understands by the latter appellation. " They differ in
size, and are the first bodies that appear in it (i. e. the sai'code) .... By the
time the ovules have become fully foiTued, the sarcode and its moleculae have
died ofi^ or disappeared,"

The granules " make their appearance among the moleculae, and are cii"-
culated round the abdominal cavity iu the manner of the digestive globiiles
and particles of food. They are of different sizes, but chiefly characteiizcd
by being much larger than the molecula3, few in number, of a circulai', ellip-
tical, elongated, subround, or irregular shape, with thick dark edges, appa-
rently produced by obstruction to the passage of light, — coloiu-less, or of a
yellowish-green tmt. When large, and with no other gTunular matters pre-
sent but the molecula3, they form a striking featui'e in the interior of Amoeba,
VorticeMa, Oxytricha, Paramecium Aurelia, &c. ; but at times they are so in-
significant in size as to be undistinguishable from the moleciilas, even if
present at all. That they are not ovules may be satisfactorily seen when
both are together, — the dark, thick, and frequently ii-regular edges and colour-
less state of the former contrasting strongly with the thin circular margin
and faint yellow tint of the latter. They appear to increase in size and
number with the age of the Infusorium, and, when fully developed, to remain
unaltered in size, though apparently somewhat shrivelled in fonn, until theii-
dissolution. On one occasion, while watching the metamorphosis of an O.n/-
tricha (similar to, but not the same as, that described by M. Jules Haime.
and of which I hope to give a detailed account hereafter), these granules,
dnring the formation of the globular cell within tlie body, which enclosed tlio '
mateiials from which the Floesconia was ultimately developed, became con-
gregated together at the posterior extremity of the O.vytricha, and remained
there in a roundish mass, shxit out from the cell, until the latter buret for
the liberation of the Floesconia, when, -with the deciduous coverings, tlioy
passed into dissolution. Of the nature of their office I am ignorant ; but they
arc sufficiently remarkable and constant to demand particular notice,"

Pcrty speaks of molecules and granules together, and oxpi-osses his opinion
that some arc simple fat-corpuscles, and others the first rudiments of internal
germs or ovules. Stein also carefully distinguishes fat-granules from others |
not fatty. In Opemdaria, Epistylis, and alhed genera of Vorticellina. this
observer points out that no particles of food peneti'ate to the posterior extre-
mity, Avhore its cHamctcr is naiTowcd to luiite with the stem, but tliat this
region is occupied with a heap of large fat-corpuscles and of minute granules
of probably the same nature. Isolated coi-pusclcs resemble jirecisely the fat-
particles scattered through the body. He cannot assent to Ehrenberg's pro-
position, that this heap of granules represents a sort of loose ovary, but would

OF THE PEOTOZOA. CIUATA.

339

consider it to be a store of nutritive matter specially intended to furnish the
material requii-ed in the construction of the stem.

Under the name of " spherical cells " Mi-. Carter {op. cit. p. 124) describes
some special structures, which, so far as we know, are not mentioned by any
other observer. " They aboimd," he writes, " in the sarcode of Otostoma
(XXVIII. 25, 26), and apparently in many of Ehi-cnberg's ' AUotreta.' In
Otostoma they are of different sizes, because they are in aU stages of develop-
ment ; and to keep up their numbers without distending the animalcule, they
must be continually undergoiag rapid decay as weU as reproduction. The
most remarkable featm-e in them is, that the largest contain, besides other
granular bodies, several small cells filled with a yeHowish-brown fluid ; and
these cells are also found free among the general group ; but of what theii-
ultimate destination is, as they do not appear to grow larger, or to become re-
productive, we know nothing." On comparing these cells with those seen
in the stomachs of Planarice and Eotifera, Mr. Carter concludes that they are
homologous with them, and represent a bihaiy secreting organ. "Although,"
he adds, " ovules may occasionally issue together with these eeUs from Oto-
stoma, &c. as well as from the Plaoianm, yet the two can hardly be con-
foimded."

On the correctness of this description we have no means of deciding : the
genus Otostoma has not fallen under oui" observation ; and the figm-es to illus-
trate these spherical cells convey no clear conception of their characters. We
might hazard the conjecture that these supposed definite cells are only glo-
bules of food ; for we are scarcely prepared to admit the existence of hepatic
cells in the simple tissue of Protozoa, between which and the complex organ-
ization of Eotifera, mth their true membranous stomach, so wide a difference
subsists that no tnie homology can obtain.

Perhaps the colom'ed " spherical cells " of Mr. Carter are identical with
the yellowish and brown vesicles Perty (op. cit. p. 53) separated from Nas-
sula aiirea by crusliing it between the glass slide and cover, from -^jjj)'"
to j-^uo" " ^ ^^'^^> ^'^'^ which he concluded to be fat-globules, and only
another stage of development of numerous smaller white corpuscles he met
with in the same being.

Stein has estabEshed the existence of a pair of oblong or rcniform solid
glandular-loolting organs a little beneath the peristom of Opercularia arti-
eulaia (XXX. 20), the purpose of which cannot be surmised. Lachmaun
has hinted at the possibility of their being nervous ganglions, but neverthe-
less feels quite unable to express an opinion.

The chlorophyll-corpuscles, chiefly confined to the soft subtcguraentary
lamina, have ah-cady been spoken of (p. 297), and need no further notice
except it be to recall an opinion of Cohn, that the coloured masses, called
by Ehrenberg ciliary glands, seen in a few species of Nassula, are probably
of the same nature as those coipuscles.

CnicuLATTON OF CONTENTS (XXIX. 25). — The remarkable phenomenon
of the circulation or rotation of a portion of the contents, similar to the cy-
closis in the colls of many plants, is witnessed in moat of the Ciliated Protozoa.
. It had attracted the notice of several observers before Ehrenberg published
I his great work in 1838, and was very speedily urged in argument against his
'views of polygastric organization, to which, indeed, it seemed fatal, inasmuch
! as, such a rotation is clearly incompatible with the existeiicc of stomachs at-
Itached to, and connected together by, a fixed intestine. To meet the objec-
ttion thus raised, the Berlin professor suggested that the apparent circulation
ji-waa abnormal, or a diseased condition, the consequence of an over- distension
; of one stomacli-sac at tlio sacrifice of others, an explanation quite inadmissi-

340

GENEItiVL HISTORY OF TirE INFUSORIA.

ble, since tho phenomenon is one to be very frequently oljserved in animal-
cules evidently in full functional activity and uninjm-ed, and because the
particles of food entering the interior assume their usual globular form (i. e.
acquire the characters given by Ehrenberg to his so-called stomach-sacs), take
their usual course, and do not accumulate in a confused manner within a largo
sac, such as the supposition in question implies.

Microscopists are now agreed in representing this rotation to be confined
to a layer or stratum of the contents within the subtegumentary or cortical
lamina, and not to extend to the central portion, as Cohn represented (Zeitschr.
1851, p. 265). The cm-rent is from left to right, as we look down upon
the animalcule (XXIX. 25) under the microscope, and therefore is actually
the reverse, or from right to left, with regard to the animal itself. It never
changes its direction or com'se ; but its rapidity varies in different species, and
even in the same species under different cii'cumstances affecting its vitality :
such are, among external conditions, light, air, warmth, and food ; others, age,
the encysting and reproductive acts. Cohn observed that some particles in a
Paramecium Bursaria occupied 1-L to 2 minutes in making the circuit. In
Vorticella the current is slower. The stream is composed of a thin mu-
cilaginous matter, bearing in it numerous granules and molecules, fat-cor-
puscles, globules of food (the stomach-sacs of Ehi-enberg), and the remnants
of alimentary matters in their passage to the dischai'ging outlet. The chlo-
rophyll-corpuscles of the cortical layer, the nucleus, and the contractile vesi-
cles are not involved in the current, imless, indeed, a few of the first named
when accidentally detached fi-om their matrix. The nucleus lies more or less |
within the stream ; and although moveable to a considerable extent at times
by the onward pressure of a bolus of food, it yet seems to maintain a con-
nexion with the subtegumentary lamina, and to escape being di-a^wTi into the
rotating ciu'rent. Fiu'ther, in the large Vorticellina, such as Epistylis and
Opercidaria, the mass of fat-corpuscles at the base of the body does not join |
in the current ; and it must be noted that the food-globules do not circulate ;
until they have lost the independent motion received by them on their pro- t
pulsion from the extremity of the oesophagus. J

The most correct view, in our opinion, of the nature of the rotatiag stream, j
is that of Lachmann, who conceives it to be the nutritive fluid elaborated from j
the food, — in a word, " chyme." Such a fluid, analogy suggests to be needed |
by the cortical and sarcode laminae over which it spreads itself, to supply ma-
terial for their renovation and rebuilding, and to compensate for the constant
waste consequent on the perpetual movements of the animal. And may
we not fui'ther presume that this cm-rent also sen-es to bear away from
the lamina effete particles prior to their elimination, just as the blood
of higher animals serves both as a pabulum to the tissues and a channel for
the removal of their worn-out material? Moreover, this circulation of a nu-
tritive fluid around the inner layer of the animalcule has its analogy in tlic
rotation of a similar fluid around the general abdominal cavity of the Coelen-
torata, such as the Hydrozoa and Actinozoa.

Respecting the cause of this rotation of the contents, sevei-al explanations
have been broached. Some seeing in it a close similarity to the cyclosis of j '
plants, have attributed it to a like cause ; but wliat this is in vegetable cells
is anything but certain. According to some, the nucleus of the plant-cell is
tho exciting force, since the stream seems to set out from and to return to
tho nucleiis ; but this is not univereally the case. Others, again, imagine cilia
to cover the interior of tho cell- wall — but this is only an hyjiothesis. — whilst
others find in the functional activity of growth and nutrition, coujilod with
the co-ordinate actions of light, heat, and chemical affinity, a sufficient cause

I

OP XHE PROTOZOA. CILIATA.

341

for the phenomenon. This last view comprehends the interpretation Stein
puts upon the movement in question in the Protozoa, which is, that the chlo-
rophyU-globules by their action on light, by the exhalation of carbonic acid
gas, and the resultant chemical forces developed, produce the revolving move-
ment ; for, as he remarks, the movements of the animals have nothing to do
with the rotation, as some have suggested, seeing that it goes on when
they are in perfect repose ; and moreover is seen only in those rich in chlo-
rophyll, and not in colourless individuals.

In elucidation of chemico-vital action as a motor force, we may allude to
vegetable physiology, which teaches us its power in the circulation of the sap
through the appointed channels in the leaves and thence downwards through
the inner bark. But, apart from the influence of chemico-vital forces, we cannot
exclude the idea that the propulsive force of the oesophagus, in impelling food
or water into the general ca^ity, must aid the current, even if its axis do not
precisely correspond with the course at the point where it is fii-st operative,
since, from the difi'erence in the arcs described by the coui'se of the stream
and by the oesophageal current, the two must eventually become coincident
and concurrent.

In a recent letter to us. Dr. Strethill Wright remarks that " in Carche-
sium polypinum active molecular movements may be detected throughout
every part of the zooid (animalcule), even in the thickened rim upon which
the cilia are placed. This movement seems to be distinct from the rotatoiy
motion of the whole contents of the body, so readily seen in Epistylis grandis,
and which only occasionally occurs in Carchesium. The zooids of the class
of Protozoa seem to be composed of sarcode in its most fluid state, enclosed
in a delicate contractile coat. In this sarcode a desultory circulation occurs,
either as molecular motion or as steady rotation, or as a backward and for-
wai'd flowing occasioned by change of shape in the body, as in Ophrydimn
versatile."

The ENCTSTrNG-PEOCESs the Ciliated Protozoa (XXVIII. 6, 7, 66,
67, 74-76 ; XXIX. 18, 19, 21-23, 39-46, 52-58).— Although the encysting-
process is very frequently associated with the act of reproduction, yet it is
also concerned with the preservation of individual life, and, so far, deserves
consideration apart from the former. "Were it not for some provision against
such a contingency, animalcular life would be exposed to wide-spread destruc-
tion by the change of fseasons, by the drying up of the pools and ditches they
inhabit, and by other injurious external influences. Such a provision is made
by the act of encysting, which enables these minute animal organisms at all
ages to resist those destructive agencies, and also provides for their almost
unlimited diffusion. The construction of sheaths around animalcules is an-
other protective act (see p. 282), but differs from encysting in not completely
enclosing them.

When an animalcule is about to encyst itself, its movements become less
active, and presently cease ; at the same time it withdraws and folds up its
rotary or other prominent process, closes its oral aperture and contracts itself
ra a more or less spherical shape, and its cUia disappear. Having proceeded
thus far, an excretion is thrown out around, whicli gradually hardens, assumes
a membranous form, and invests the animalcule as a cyst or case. It may
happen that the construction of the cyst commences before the animal is
quiescent, while it still moves slowly about or revolves on itself by the out-
pouring of the soft gelatinous matter out of which it is to bo elaborated as
is seen in Amphileptus (XXIX. 19), Colpoda (XXIX. 35— 43), and Ohilodon
(XXIX. 48-58). Moreover, after the animalcule is enclosed within its case
it may for a time vary its figure, and also turn on itself with more or less

342

TtEneeal uistohy of the infusoria.

activity, by means of its cilia, which yet remain apparent. Stein mentions
this phenomenon in Stylonychia pustulata (XXIX. 18), and in the encysted
embryos or gemma3 of Coljpocla ; and we know that similar movements precede
its revival from its quiescent condition in aU cases.

The cyst-wall is, at least in some examples, double, consisting of an outer,
finely-granular, softer layer and an inner, consistent, elastic, homogeneous
membrane (XXIX. 21, 22, 41, 43). It may be that two such laminse always
exist ; for the outer one criimbles away so soon as the enclosed animal prepares
to reassume its activity, and it is after the onset of internal changes that
most observations have been made upon cysts. The two coats were remarked
by Auerbach (ZeitscJir. 1854, p. 431) in Oxytricha Pellionella (XXIX. 21-23) ;
by Stein in Ghilodon CucuUulus (XXIX. 53, 54), in Stylonychia pustulata
XXIX. 18), and in Nassulu amhigua ; and by Cienkowsky in Nassula viridis
(XXVIII. 67), &c. In Ghilodon, indeed, Stein represente several concentric
layers to the cysts (XXIX. 55, 56), and states that in this instance the walls
acquire no firmness, but remain soft and gelatinous.

Another pecuHarity attaching to cysts in some species, is, that they
produce folds or plaits on theii- siu-face, and therewith acquii-e an ajjparent
angTilar outline, as Stein exhibits in his figures of encysted Epistylis 2^licatiUs
and E. hranchiophila, where the Hnes are longitudinal, and in encysted Oper-
cularia berberiformis, where they are transverse or annular.

Again, the cyst-walls are not always smooth : thus, in Nassula ambigua
Stein represents them as punctate in longitudinal lines ; in Stylonychia pus-
ttilata (Midler's ArcJiiv, 1856, iv. ; A. N. H. 1857, xix. p. 228) they have
stellate markings, and in a small undescribed species of Epistylis a finely-
shagreened siu'face.

The changes which the encysting animal itself undergoes have been men-
tioned generally ; but a few more details, aided by reference to particular
examples, are required for a more complete elucidation of them. So soon as
the animalcule becomes quiescent ■within the sac secreted aroiuid it, the ciha
which covered the surface, including any of larger dimensions disposed along
certain tracts, or uijon particular processes, disappear, and have generally been
presumed to be destroyed ; however, various observations are on record wliich
seem to show that this is not universally the case, but that not unfi-equently
they are merely concealed from view ; and this being so, it becomes ques-
tionable whether — especially in the ordinary process of encysting, where
only the conservation of the individual is intended — theii- destruction or
absorption is the rule. An observation of Stein may be quoted on this ques-
tion : — An encysted Ghilodon Gucidlidus, after developing several embryos,
ceased this process of propagation, redisplayed its ciha as if by simple evolu-
tion, and commenced moving within its cyst along with, one of its embryos
(XXIX. 68). The inference deduciblc from this particular observation in
the case of the encysting-process, even when exorcised for the distinct purpose
of generation, is greatly strengthened by the oft-repeated observations of the
release of the imprisoned beings, by pressiu'e causing the mpture of the newly-
foi-med cyst, in the possession of their complete figure and their cihary arma-
tiire. We may add that no proof exists of an actual new formation of cilia
upon beings when emerging from their cyst ; all that can be predicated is,
that ciha reappear in their normal positions and arrangement.

To sketch now the history of the encysting-process by a reference to some of
the many examples recorded by vaiious microscopists ; for the act has been
witnessed in so many species and genei-a, that it is assmncd to be common to
vidl. The description given by Cohn {Zeiisclir. 1 853, iv. p. 267) of the oncyst-
\g of Trachelius Ovum may be given as an example (XXIX. 19, 20): — The

OF THE I'KOTOZOA. CILIATA.

343

movements of the animalcule become slower, and before ceasing altogether,
consist in a simple rotation without change of position. The cilia are next
seen to become indistinct and to disappear ; and a delicate line, removed some
little distance fi-om the peripheiy of the enclosed animal, makes its appear-
ance, radicating the limit of a soft gelatinous envelope. Wlulst this proceeds,
the animal assumes a more globular and contracted figure, chiefly by folding
down its lip- or ti-unk-hke process upon its general surface. The secreted
covering in the meanwhile gains in firmness, but loses in thickness, and thus
acquires the character of a membrane, which closely invests the Trachelius,
except at places where the two surfaces are separate and distiuct.

This may be termed the first degree of encysting, and afiects the creature
so sUghtly that it can shake off its coating of its own accord, and, by rupturing
its sac, reassume its pristine appeaa-ance and activity. This phenomenon was
witnessed four times in the same iadividual by Cohn, and supposed by hina
to have been induced by the abnormal conditions (the action of light, &c.) in
which the animalcule was placed under the microscope. Stein (op. cit.
p. 133) in a similar manner recounts the formation of a cyst around Chilodon
Cucullulus, and the possibility of setting it free by breaking down the cyst by
pressiu-e. In Trachelius the development of the cyst, to the stage described,'
occupied, according to Cohn, only ten minutes. Where the process advances
beyond this degree, the cyst commonly acquires a denser and firmer con-
sistence ; the animalcule can no longer deliver itself at once of its own accord
from its prison, but undergoes a further change from its normal form, and
requires those vivifying influences of external warmth, light, and moisture,
such as spring-time brings with it, to arouse it from its torpid state, and to
cause the reappearance of its hitherto obliterated organs.

Stein has very copious details of the whole process of encysting in various
CUiated Protozoa ; but in none is that process more interesting to foUow than
in the Vorticellina. In members of this family the state of extreme contrac-
tion, induced by some external cause obnoxious to them, becomes fixed, and
only the irregularly- curved space covered over by the completely-closed
peristom indicates the complicated ciliary apparatus of the head ; and even
this decreases to a streak, and at length vanishes altogether. Wlulst this
goes forward, a membrane forms around the being which is now detached
from its stem, and a globular or ovoid cyst, containing a nucleus and a con-
tractile vesicle, is the representative of the once active and elaborately-
organized Vorticella.

To what degree the encysting process may advance without depri^'ing the
animal of its abihty to recover its freedom and original character, is weU ex-
emplified by Auerbach's observation on the cysts of Oxytriclia Pellionella
(XXIX. 21, 24) {Zeiischr. 1854, v. p. 430). This able microscopist foxmd a
number of globular cysts, with two coats, enclosing a homogeneous, finely-
granular, brown substance, witliin which was a darker, rounded body (XXIX.
21), or at times two, and more rarely three such, seemiugly derived from it,
indicating the nucleus. The contents natiu-ally filled the capsule ; the addi-
tion, however, of a little muriatic acid caused them to slu-ink into a roundish
body, somewhat more extended on one side, and traversed by a few deep
folds or fissures (XXIX. 22). Such were the bodies met Avith during the
continuance of Avintor ; but when early spring arrived, these began to exliibit
signs of vital activity within.

The fii-st change remarked was the appearance of a vesicle, which by
degrees acquired increased contractility ; tiicn the body retracted itself from
the cyst-wall and commenced to revolve in a vacillating manner, whilst the
outer granular lamina of the cyst broke away. Cilia now coidd be seen dis-

344

GENEHAL HISTORY OF THE INFUSOEIA.

tiibuted over the sui laco of the animal, and a close row of much stronger ones
along a fold recalling the characteristics of StylonycJiia or of Oxytricha,
although the animal still wanted the general conformation of the body
peciiliar to either of these genera (XXIX. 23). All this time the darker
nuclear body or bodies had retained their existence and position, whilst the
contractile vesicle, on the other hand, grew smaller, apparently by the ex-
pulsion of part of its fluid contents to occupy the space left between the
animal and its capsule by the contraction of the former. The enclosed body,
when freed from the wall of the cyst, commenced moving, not in a regular
rotation, but in a jerking manner, fi'om side to side as it turned, until at
length it ruptiu'ed the walls of its prison and made its escape. The animal
thus set at large presented the characters of Oxytricha (XXIX. 24) di-
stinctly enough to recognize it as belongiug to the genus ; and at the same
time the numerous escaping germs and the rapid appearance of a multitude
of Oxytricha PellioneUa of all sizes confirmed this view of their nature.
Nevertheless a slight difference existed between the newly-emerged indi-
viduals and matiu-e specimens, — the former being more oval, and their contents
less hyaline, more granular, and of a yellowish colom* by transmitted light :
still, specimens occurred of eveiy intermediate shade.

This observation by Auerbach demonstrates to us how completely modified
and actually lost the characters of an animalcule may be when it becomes
encysted even temporaiily, during what has been termed the winter-sleep ;
for, as that ■wiiter shows, the Oxytricha-ajsts he discovered could not have
been ova, or a mere transitional phase to a higher form of existence. Similar
instances of cyst-evolution are recorded by other observers ; but generally the
whole history of the cyst is not given, but only that portion in which an
actual animalcular form, in movement by means of ciUa, has revealed itself;
such is the instance of Amphileptus Fasdola mentioned by Cohn (Zeitschr. v.
1854, p. 434). Purthemiore, variations in the internal appearance and per-
ceptible contents of cysts vary in difterent species, just as do their walls ;
thus, for example, in Oxytricha-cjsts the contractile vesicle had vanished and
appeai-ed de novo only when its vital activity was resumed, — while in other
cases this sac or space never disappears, but is even more prominent than
the nucleus before the action of reagents, which is tnie of most, or of aU,
Vorticellina.

The particulars recounted by Mr. Brightwcll respecting Zooiliamnmm
Arhuscula (' Faima Infusoria of Norfolk,' 1848), which he thought indicative
of a mode of development by alternate generation, appear to us to represent
probably the act of encysting, or that degree of it assumed by gemmaj prior
to detachment from their parent stem, and retained by tliem until they have
taken up a fixed position and proceed to develop a peduncle (sec section
on Mission and Gemmation). We extract Mr. Brightwcll's account, so that
our readers may form their oAvn opinion of the nature of the phenomena

detailed : — . „ , . , , r

" Sept. 16th, 1846. Eariy in the morning of this day, we obsen-cd one of
the Zoothamnhmi arhuscula, a large old specimen, which had lost all its
small bell-shaped animals, but had several medlar-shaped buds or ova re-
maining upon it. It was seen to detach from its stalks nearly aU these ova,
which went off as free animals. One of them soon after settled at the side of
the water-trough, and after agitating its anterior cilia it suddenly, and with
a kind of violent effort, opened into a cup-shaped form, and darted about
with great rapidity, occiTsionnlly settling, and darting ofl' again.

At nine in tlie moniing, one of these buds, or ova, wa.s observed fixed to
glass by n sheathed pedicle ; a ciliaiy motion became perceptible at the

OF rUE I'KOTOZOA. CILIATA,

345

top of the biilb ; and at ten it had divided longitudinally into two buds, each
supported by a short stalk. The ciliary motion contiaued in the centre of
each of these two buds, which by degrees expanded longitudiually, and at
twelve had become four- buds. By four iu the afternoon, these four buds had
divided in like manner and increased to nine, mth an elongated foot-stalk, and
interior contractile muscle.

" During the development of another specimen, the stalk appeared to have
transverse ribs or joints, and, whilst a drawing was making, gradually bent
downwai'ds, and all the buds severally detached themselves from it, and went
off as free animals, leaAnng only the bent stalk. In this interesting process
we see something analogous to what Steenstrup describes as * a mode of
development by means of nurses or intermediate generations.'

" This mode is described as that in which an animal produces a progeny
permanently dissimilar to itself, but which progeny produces a new generation,
in itself or its offspring, returning to the form of the parent animal. It
win be seen that this development differs from that of metamorphosis, in
the circumstance of the intermediate animal (the niu'se) being itself a perma-
nent and producing form.

" To show this to be the case with ZootJiamnium, it would be necessary to
prove that the medlar-shaped animals were a permanent form, producing a
race which, in themselves or in what they produced, returned to the form of
the parent animal.

" We have not been able to carry the development of these buds or ova
further than PI. 12. f. 67, 68, 69, and wood cut " (see Part II.). " And it is
remai-kable that in all these the buds have produced, not the little beU-shaped
animalcules hke the parent animal, but other buds hke themselves. May it
not be the case, that these medlar- shaped bodies are propagated at the close
of the year, and that, when the plant to which the Zoothamnia bearing these
bodies are attached dies away, they remain in the mud, protected from the cold
of the winter, and in the spring burst forth, and settle upon the new-growino-
plants, and produce animals of the parent-form. They would thus form an
intermediate niu'sing race answering to Steenstnip's description."

Prof. Cienkowsky has witnessed (ZeitscJir. 1865, vi. p. 301) cyst-construc-
tion in Nassida viridis (Duj.) (XXVIII. 65—71), Stylomjchia xnistulata
(XXVIII. 74 — 76), S. lanceoJata, in various Vorticellce, in Bursaria trunca-
tella, B. lateritia, Podojjhrga f xa, Loxodes CucidMus (Duj.), Leucophrys
Spatlnda, Amphileptiis margaritifer, Holophrya brunnea, and less completely 'in
AmpMleptus Anas, Stylonychia Mytilus, Paramecium chrysalis, Spirosfomum
ambiguum, Stentor pohjmorphus, St. Mulleri, Paramecium Aurelia, and Loxodes
Bursar-ia.

In Loxodes Cmidhdus (Duj.) and Stylonychia pustulata he saw the dis-
charge of the whole of the contents of the cyst in the form of encysted Infu-
soria. The embiyo born from the cysts of Stylonychia pusttdata resembles
closely the Tnchodu Lynceus, and can multiply itself by self-fission just in
the same manner as mature and independent beings.

In cyst-development, he observes, the whole of the contents are, as Jules
Haime stated, not metamorphosed nito tlie resultant embryo, but one or more
portions escape in the form of globules, apparently ciliated, and move off \nth
a rotating motion.

llEPRODUCTION OF THE CiLIATED PrOTOZOA :— FisSION, MOBES OF ; GeMMATION •

INTEUXAL Ova pnoDUCiNG Gbrms ok Embryos ; Impreonation ; Productton
OF new Beings with and without METAMORpnosis ; Transformation into
AciNET^, AND Development of EMKRVos.—UntU lately, naturalists in general
did not acknowledge other methods of reproduction than by fission or as

346

GENERAL HISTOEY OP THE INFUSOEIA.

some would call it, fissation, and by gemmation or budding, which, from not
being true generative acts, have been called ' vegetative ' modes of propagation
or multiplication. Eecently, however, the CUiata have had attributed to them
true generative processes, resulting in the development of embryos either with
or without intercurrent metamorphoses.

The simpler processes of fission and gemmation are, in Stern's opinion, modes
of propagation peculiar to immature beings, and are replaced in mature
animalcules by the agency of germs or embryos.

Fission. — This duphcative subdivision may be longitudinal, transverse, or
obhque ; and whilst some species divide in only one dii-ection, others are
capable of so doing in two, for instance, in the longitudinal and transverse,
but not simultaneously. Among the Vorticellina longitudinal fission alone
occui's ; Paramecium (XXIX. 27), Ohilodon, and others divide both longi-
tudinally and transversely; Lagenoplirys obliquely only. Fission has not
been witnessed in Spirocliona nor in Trichodina, nor in Colpoda when in a
free state and not encysted.

Ehrenberg came to the conclusion that multiplication by spontaneous divi-
sion is the character which separates animals from plants. It is true (he
argued) that gemmation in plants, especially in veiy simple ceUs, is at times
very similar to the division in animals ; but this relates to the form, not the
formation. A vegetable cell, apparently capable of self-division, produces
one, or contemporaneously many exterior buds (gemmai), without any change
in its interior. An animal which is capable of division, fii'st doubles the inner
organs, and subsequently decreases exteriorly in size. Self-division proceeds
from the interior towards the exterior, from the centre to the periphery ;
gemmation, which also occurs in animals, proceeds from the exterior towards
the interior, and forms fii'st a wart, which then gradually becomes organized.

This supposed distinction between fission in vegetable ceUs and that in
simple animals like Infusoria is set aside by modem researches, which show
that, when a plant- cell is about to divide, the mucilaginous layer of the wall
(i. e. the primordial utricle) manifests a constriction, which presently involves
the wall itself, and, gradually deepening, at length cuts the cell into two. The
observations on this subject in the chapters on DESMmiEiE and Diatomeje wiU
more completely elucidate it.

Considered with respect to the condition of the animalcule, fission occurs
in the active and unchanged state, as in Paramecium ; or In a contracted state,
as in Vorticellina ; or only when encysted, as in the ease of Colpoda. Hence
it foUows, that it presents several slight modifications in its coiu'se. One
general fact is, that whilst fission proceeds, the rotation of tlie contents of the
animalcule is at a stand- still. In its simplest variety, the dividing being first
presents a constriction at each pole or side of the body, which gradually ex-
tends until it completely cuts it into two equal or unequal parts. Simulta-
neously with the fii'st indication of an act of fission, and in some cases before
a sign of it is to be detected in the peripheiy of the animal, it has been
generally taught that the nucleus, after elongating and usually disposing
itself across the direction of the line of scission, takes the initiative in the
act, by commencing a fission of its own substance (XXIX. 27), which sub-
sequently proceeds step by step with that of the entire body, until complete.
This statement is, accorchng to Lachmann (A. N. U. 1857, xix. p. 230), a
mistake when made respecting the Protozoa gcncnilly ; for in some cases the
di\dsion of the nucleus is consecutive to that of the body, and " in others,
again, the actual fissation of the nucleus does not lead to that of tlie body,
but embryos arc developed in it ; " on the other hand, " fissation is generally
commenced rather by a new formation of contractile vesicles."

OF THE PHOTOZOA. CILIATA.

347

In some species where fission proceeds on its simple type, food may con-
tinue to be received for a short period by the dividing animal. The small share
the abdominal contents witlmi the cortical lamina have in the vital processes,
is shown by Lachmann's observation of a Stylonychia, " which, although, a
considerable part of its chyme had been sucked out of it by an Acineta, still
underwent division, so that one of the gemmules of division swam away from
it bi-iskly, and only the other half of the old animal was destroyed."

The direction of the Hne of section is perhaps, when longitudinal, usually
from before backwards, the constriction appealing first and advancing more
rapidly at the head ; but the contrary, according to Stein, prevails in CJiilodon
Cuadlulus, where the constriction makes its way solely from the posterior pole.

AVhen fission is transverse or oblique it necessarily involves the reproduc-
tion, in the posterior half, of the organs existing in the anterior, viz. the ciliary
apparatus of the head, the oral aperture, the tube prolonged from it, and the
contractile vesicle. So far, therefore, it approaches nearer the act of gemma-
tion than does longitudinal fission, wherein segments of the already existing
organs are separated for the purposes of the new individual, and are not
actiially reproduced or created anew. " In those Infusoria," says Lachmann
(A. JV. H. loc. cit.), " in which a peculiar series of stronger cUia leads to the
mouth (such as Oxytrichince and Eivplotece), the farrow in which this series
of cUia is situated is seen, subsequently to or simultaneously with the division
of the contractile vesicle, to become produced backwards over the mouth ; in
this prolongation cUia are produced, and its posterior extremity becomes
deepened into a mouth and oesophagus, which then opens towards the ali-
mentary cavity of the animal ; then, simultaneously with the external con-
striction of the body, the new furrow is separated from the old one. (In
Stenior the new frontal series of cilia first makes its appearance on the old
animal as a lateral straight series — the crista lateralis of Ehi-enberg). In
animals which also possess peculiar processes of the body as organs of motion
(hooks, styles, &c.), the fissation usually takes place in such a maimer, that
each of the newly-formed animals acquires a portion of these from the old
animal, whilst the other part is of new formation."

The manner in which self-division proceeds in Protozoa Avith a firm, and
seemingly almost brittle integument, is exemplified in Coleps (XXIV. ''284
285). Along the line of section a new secretion of chitinous substance takes
place, soft in consistence and transparent, Avhich by its increasing width
separates the two portions of the original lorica; in this interposed new
tissue a constriction presently manifests itself, and advancing in depth, the
two segments are finally simdered. It thus comes to pass that each product
of fission is one half covered with a dense shield, and the other half with a
soft, yielding integument. After a while, more molecules make their appear-
ance in the latter, wliich gradually assumes a firmness equal to that of the
old lorica.

The Vorticellimi, including the OphryiUna, do not divide until tlioy have
assumed a sort of semiquiosccnt condition, by the complete withdrawal of
their ciliary apparatus and the contraction of the body generally into a more
or less rounded or oval shape,— in short, until they have advanced one sten
towards encysting themselves.

Ehrenbcrg portrayed their fission as a simple constriction advancing from
before backwards to separation of the body ; but Stein pointed out the actiial
antecedents of the process. According to tiie latter wiiter, the head-nortion
and Its appendages ^^^tildraw ; tlie rotary organ is absorbed, and also the
(Esophagus ; at the same time the contractile space vanishes ; the bodv ox
pands m vvadth, the nucleus outstretches itself across it, a constriction appcai-s

348

GENERAL HISTOHY OF THE INFtTSOEIA.

on its anteiior border, and, extending constantly in depth, at length effects its
complete division. When the section has reached the third of the body, a
conical space displays itself towards the anterior portion of each half (XXVII,
3), lined by a special membrane, covered by cilia on its posterior side or base,
which are seen to vibrate within the cavity. This formation is the rudiment
of the future rotary organ. The apex of the conical hoEow is prolonged by
a canal which eventually opens on the surface, and thus establishes a con-
tinuity between the lining membrane and the external integument. At the
same time the internal angle at the base of the cone is produced inwards so
as to form the alimentary tube. When these changes are accomplished, the
body is half cut through, and the appearance is rather that of two individual
animalcules miited posteriorly, having their ciliary appai'atus retracted, and
the peristom contracted in a splinter-like manner over it. Lastly, the
advancing act of scission divides the nucleus ; and the whole body becomes
resolved into two individuals seated upon the same stalk. From this accoimt
it follows, that, of the original organs of the animalcule, the nucleus is the
only one divided between the two resultant beings by the process of fission ;
all the rest are formed anew out of the homogeneous substance of the body,
viz. the peristom, the rotary organ, the alimentary tube, and the conti'actile
vesicle.

This absoi-ption and renewal of parts diuing lissation is denied by Lachmann,
who affii-ms that the movement of the cilia upon the cihary apparatus, and
in the vestibulum and oesophagus, which are closed up by the peristom, may
be observed during the whole process. W^e have no means of deciding which
of these two statements is correct : yet we rather incHne to Stein's account ;
for when we admit that in fission there is a separation of all the organs and
appendages of the body into two portions, one to each resultant being, an act
of structural development becomes necessary to reproduce the remaining por-
tion, so as to perfect each new animal and to assimilate it in characters to
the parent. This being the case, the method of development stated by Stein
is more consonant with our views of histogeny than that of Lachmann.

The oblique fission of Lagenophrys vaginicola (XXX. 32, 35, 36) presents
several peculiarities. The Une of section commences below the peristom on
one side, and proceeds diagonally across to the opposite, and thus gives rise to
an anterior lateral segment retaining aU the special organs, and a posterior
lateral possessing nothing save its half of the elongated divided nucleus.
During the process, the anterior half continues in the enjoyment of all its
functions and activity (XXX. 32), whirls its cUiary organ, and takes in food
bv the mouth : the food, however, does not reach to the segment behind ; and
whatever alimentaiy particles might be present in this vanish, and its whole
contained substance becomes homogeneous and granular, the half of the
curved band-like nucleus extending into it. "ViQien the line of section is fully
formed. Stein remarks that the posterior lateral segment rather resembles a
gemma than the result of self-division, and proves liow closely united are the
two processes of gemmation and of fission.

When the scission is nearly complete, a contractile space appears, and,
either before or behind this, a curved elongated cavity, cUiated on one side
and produced upwards as a tube from one angle, is formed (XXX. 35), out
of which the rotary organ and peristom are developed. As there is no room
for movement, the new being lies motionless close against the old one : how-
ever, its contractile space acts energetically ; and the alimentary tube, fiUcd
with fluid, moves upwards and downwards, and from side to side •\\'ithin it. At
length a row of cilia appear aroimd the circumference of the body ; and now
two beings occupy one case, the anterior adhering by its peristom to the narrow

OP THE PBOTOZOA. CILTATA.

349

oi-ifice of the sheath, whilst the posterior lies immediately behind it, fixed from
want of space, and unable to free itself (XXX. 36). The question that now
presents itself is, how is the newly-formed animal to escape its prison and
to exercise its vital endovnnents ? This, Stein has been able to solve by ob-
servation of another species of Lagenophrys, viz. L. Ampulla. The upper seg-
ment ceases to put forth its ciliary organs and to take in food, and shortly
contracts itself and detaches its hold from the opening of the external sheath,
developing simultaneously a row of cilia around its margin (XXX. 35). It
also not unfrequently happens that the body is divided from the peiistom,
leaving this portion adherent in its natural position to the orifice of the
sheath, and possessed of such remai'kable vitality, that it continues to con-
tract and dilate, and to implicate the orifice of the sheath itself in its move-
ments (XXX. 35). "When the peristom, with a portion of contractile sarcode
(35 6) enclosing at times a contractile space within it, thus plugs the
only outlet from the cyst, the two products of fission cannot gain their
liberty, and only enjoy the limited degree of locomotion allowed within their
narrow prison-house. But where, as is more common, the orifice is opened,
they sooner or later make their way out, experiencing, nevertheless, some
difficulty in passing through the narrow outlet.

A curious circumstance pertains to these fission-products of Lagenophrys,
and indeed to those of all the Ophrydina and Vorticellina, viz. they are not
precisely like the parent. Thus, the young of Lagenophrys, produced as
above described, exhibit the rotaiy organ and peristom in a contracted con-
dition, whilst a row of cilia siuTounds the body in a ring-like groove on the
abdominal siufacc, and serves the pui-pose of a locomotive organ (XXX. 35,
36). On the ventral aspect, adds Stein, the figure of the animalcule recalls
that of StylonycMa, between which and the normal form of Vorticellina it
may be considered a transitional type.

Turning now to the other members of the Vorticellina and Ophrydina, we
see that the history of the fission-products differs according to theii- habits
and structiu-al peculiarities. In the branching forms many of the newlj-
formed beings proceed each to secrete from its base a pedicle, and so continue
the dichotomy of the little arborescent colony they belong to. Others on
the contrary, detach themselves from the parent-stem and enter on a fi-ee and
independent existence. In this case one of the two segments consequent on
self- division, in order to enter on its new mode of life, undergoes certain
modifications in stnicture, viz. it continues in a completely contracted state
and a fm-row appears about the posterior third of the bodj-, within which a
ciliary circlet develops as the locomotive organ of the animal (XXVII. 11)
This occurrence is general among Vorticelloi and Ophrydina ; for amonf the
former the pedicle never ramifies, and in the latter one fission-product must
quit the capsule, which serves as the nidus of only one being at a time

The after-history of these locomotive segments is widely diff'erent in dif-
ferent specimens. Some, after summing about for a time, come to a state
of rest, affix themselves by their posterior extremity, and produce, according
to their natural habit, either a stalk or a sheath, and resume all the charac-
teristics of the parent-stock. Others, again, become quiescent, but instead of se-
creting a pedicle or sheath, proceed to encyst themselves, either for their own
preservation or preparatory to the fulfilment of an act of reproduction In-
deed, the process of encysting may overtake the animals whilst stiU seated
on their stalk or within their case, and thus anticipate the fomiation of tlie
posterior ciliary wreath.

Lastly, in a few genera, fission seems only, or at least mostly, to occur
after the animalcules are encysted. Stein represents this to be the case ge-

350

GENEKAL HISTORY OF THE INFTJSOKIA.

nerally in Colpoda Cucullulus, whicli he never found in process of fission
(XXIX, 38-47). Indeed, Ehrenberg himself never saw self-di\Tsion of
this animalcule, although he has, on the authority and ambiguous observa-
tions of some of the old observers, described its occurrence. According to
Stein's researches, encysting would not appear absolutely necessary ; for he
witnessed self-division in some specimens only contracted in a spherical foi-m :
however, in others, the more numerous, a cyst was thro-svn around the body
before that process ensued. According to the general plan, the Ciliated
Protozoa divide into two ; yet there are some — and Colpoda is one of such —
in which the act of fission is repeated, and 4, 8, and even 16 segments and
upwards result. The products of fission have a certain latitude of motion
within their cysts, and ultimately escape by rupture. Another peculiarity
about Colpoda is, that the segments resulting fi-om fission secrete individually
a capsule around themselves, and thus we have encysted beings enclosed
within a general cyst. Lastly, each young cyst has its own nucleus and
contractile vesicle (XXIX. 43).

The fission of the animal when encysted appears to be the rule in Glau-
coma ; for example, in G. scintillans ; and Stein surmises that it is this
occuiTcnce which 'Cohn witnessed in Chilodon uncinatus, and thought to be
two animalcules enclosed within a common cyst, as happens with Grec/arince.

The importance of fission as a means of multiplying individuals among the
Ciliata admits of numerous striking illustrations. "We may quote one given
by Ehrenberg, by no means an extraordinary instance. He made out that
a single individual of Stylonycliia Mytilm hved nine days : dming the first
24 hours it divided into 3 ; and during the next space of 24 hours each of
these three had subdivided into two beings ; so that by self-division alone
this animalcule can multiply itself three or fourfold in four and twenty hoiu's,
and in the space of ten days be represented by a million derived beings or
offshoots. Another instance may be adduced from the same distinguished
micrographer. On the 14th of November, he divided a Parameeiicm Aurelia,
•jLth of a line in length, into four parts, each of which he placed in a sepa-
rate glass. On the 17th, the glasses numbered 1 and 4 each contained an iso-
lated Paramecium swimming actively about. The pieces in Nos. 3 and 2 had
disappeared. On the 18th, there was no change. On the 19th, each animal-
cule presented a constriction across the middle of the body. On the 20th,
No. 1 had propagated 5 individuals by transverse fission, and No. 4 eight
such. On the 21st, no change had taken place. On the 22nd, No. 1 contained
6, and No. 4, 18 specimens. On the 23rd, the beings jiroduced were too nu-
merous to be counted. Erom these notes Ehi-enberg calculated, if this process
continued in activity for a month, 268 millions might be produced. Apart,
however, from these, which we may term speculative considerations, we have
in Ophrydium the clearest and most dii'ect evidence of the extent to whicli
fission is carried out. On the completion of self-di^dsion in tliis animal, tlie
products remain together, connected by a common gelatinous mass at their
base exerted by themselves. Ey the repetition of the process again and again,
through a long series, the OplLrydla accumulate in largo greenish masses, or
polyparies, at times of the size of the fist or even of tlie head of a man. Now.
by comparing the size of the individual Ophrydia (about T-J^th of an inch in
length) with that of the masses they fomi, "some estimate," says Dr. Car-
penter {The Microscope, p. 487), " may be formed of the number included m the
latter ; for a cubic incli would contain nearly eigid millioixs of them, if they were
closely packed ; and many tunes tiiat niunber must exist in the larger masses,
even maldng allowance for the fact that the bodies of the animalcules arc
separated from each otlior by their gelatinous cushion, nnd that the masses

OF THE PROTOZOA. — CILIATA.

351

have their central portions occupied only by water. Hence we have in such
clusters a distinct proof of the extraordinaiy extent to which multiplication
by duplicative subdi\-ision may proceed without the interposition of any other
process. These animalcules, however, free themselves at times from their
gelatinous bed, and have been observed to undergo an ' encysting process '
corresponding with that of the Vorticellina. It is much to be desired that mi-
croscopic observers should devote themselves systematically to the continuous
study of even the commonest and best-lmown forms of these animalcules,
since there is not a single one whose entire life-history, from one generative
act to another, is known to us ; and since it cannot be even guessed at, vpith-
out such knowledge, what, among the many dissimilar forms that have been
described by Prof. Ehrenberg and others, are to be accounted as traly di-
stinct species, and what are mere phases in the existence of others that are
perhaps very dissimilar to them in aspect, it is obvious that no credit is
really to be gained by the discovery of any number of apparently new species,
which shall be at all comparable with that to be acquired by the complete
and satisfactoiy elucidation of the life-history of any one."

Gemmation (iUustrated by XXYII. 1-4 ; XXX. 17, 27, 29, 31, 33, 34).—
This is the next process of multiplication to be considered. It has much
analogy with fission, but is not nearly so widely diffased, being restricted
apparently to the families Vorticellina and OpJirydina, that is, to attached
species of Ciliata ; yet even among these it would seem not to be general ;
for Stein has failed to observe it in the genus Ojpercularia. In it a promi-
nence fonns upon the surface, mostly near the posterior extremity, and of the
same granular homogeneous substance as the rest of the animal : a line of
constriction soon displays itself, and gradually deepens, whilst the budding
process increases in size and developes internal organs and external ap-
pendages, xmtH, being sufficiently perfected for an isolated existence, it severs
itself from the parent stock. The gemmae or buds thus produced ai"e much
smaller than the parent, and, even when they have acquired their largest di-
mensions before separation, are less than the new beings originating from
self-division. In every instance of fission the nucleus becomes divided be-
tween the two segments ; and some authors, as we have seen, hold the opi-
nion that these share between them a portion of other pro-existent organs of
the divicUng animal ; on the other hand, in gemmation the bud is a mere
offshoot of the general substance, containing no portion of any pre-existing
organ — not even, so far as can be seen, of the nucleus ; and consequently all
the specially-organized parts are developed in it de novo. If the doctrine of
internal germs be admitted, then it may be imagined that each gemma origi-
nates from one of these, which takes on this external direction of "development.

On the completion of the gemma, we find that it resembles (except in Spi-
rocJiona and Lagenophr;/s) a completely- contracted specimen of the parent
animalcule, and possesses, in lieu of the usual ciliated whorl on the head,
a posterior cihary wi-eath, whereby, when detached, it swims freely away!
mth the posterior extremity, however, in advance. It resembles, tliorefore,
in all respects the product of fission when separated from its fellow, and,
like it, may either presently attach itself, losing its posterior circlet of
ciha, and acquire all the characters of its parent — as well as, in process
of time, its dimensions, — or advance to a completely encysted state, prepara-
tory to a process of development, or sijuply for the object of preservation
from untoward external conditions. The act of gemmation goes on alike in
small and in large specimens. Stein notes its occurrence in Vorticdhv of nnK-
in length. "'^

A few illustrations may render the above account of gemmation more clear.

352

GENERAL HISTORY OF THE JNl'L'SORIA.

Speaking of this process in Vorticdke, Stein {op. cit. p. 28) says, the interior
of the knob-like process is quite homogeneous at first (iJCXVII. 1) ; but when
it has attained a hemispherical shape, a crescentic cavity foiTns at its anterior
part, from which the peristom, rotary organ, and alimentary tube are even-
tually developed (XXX. 17, 27), just as happens in the result of fission.
Whilst this proceeds, the swelling acquires an oval or globose figure, and
the width of its attached base dwindles to a constricted neck or isthmiis.
The addition of acetic acid proves that no portion of the niicleus extends into
it, but that this organ retains its noi-mal curved reniforra figure. Stein here
adds tlie remark, that no sharp line of distinction exists between self-fission
and gemmation — that the latter may be looked upon as an act of unequal
division, in which the whole organization has to be created, and not, as in
fission, simply pei-petuated ; or fission may be described as a variety of
gemmation, one segment being regarded as a bud ; at least this view holds
good in the case of transverse fission. Longitudiaal fission consists in the
formation of two gemmae, which subsequently involve the entii-e being. So
also in one sense gemmation does not always end in the production of a single
bud ; for Vorticellce with two are common, and occasionally with three, one of
which is ready for detachment, whUst the other or others are very incomijlete.

In Spirocliona (XXX. 17, 27), which does not multiply by fission, gem-
mation is very frequent ; and often two buds are produced, one immediately
behind the other, the hindmost being first in development. "Where two
exist, the first-formed usually appears on the side of the bodj' at its widest
part ; and the second forms subsequently in front of it, nearer the neck. Re-
latively to the size of the parent, the bud is usually of greater dimensions
than in Vorticella, and may, by thmsting aside the head of the Spirocliona,
place itself in the longitudinal axis of the body. When the gemma com-
mences to contract its base and to acquire the form of an independent being,
an opaque, sharply-defined, homogeneous speck makes its appearance about
its middle, or, rather, in front of it, which, by further development, becomes
the nucleus (XXX. 17), whilst a shallow groove displays itself at its anterior
truncate end, and somewhat later is transformed into a curved and rather
angular ciliated fissure extending some way down one side of the body.

In this so-formed gemma of Spirocliona there is, therefore, a wide depar-
ture from the rule observed in any of the VorticelUna and Oplirydina. Xo
posterior ciliaiy Avreath is formed ; and the anterior ciUaiy apparatus, together
with the head itself, is at fii'st developed in a temporaiy and rudimentary
manner. After moving about for some time by means of the ciliary antero-
lateral channel, the free gemma fixes itself by its posterior extremity, by an
adhesive substance, or occasionally by a short stem ; and then the opposite
sides of the ciliated furrow approximate, and coalesce behind, whilst in front
one edge rises above the other (XXX. 19), and soon forms a spirally-con-
voluted membrane, which becomes clothed with cilia replacing those of
the old furrow, which are absorbed and disappear (XXX. 20). This growth
into perfect Spiroclionce does not happen Avith all gemmaj ; for some assume a
quiescent condition, become encysted, and, if Stein be right, are ultimately
converted into veiy peculiar Acinetiform beings — the Dendrocometes para-
doxus (XXX. 23). Before encysting, the cilia cease to play, and disappear ;
and veiy soon the furrow itself closes up. Wlien enclosed within the trans-
parent but firm capsule, nothing but a finely-granular homogeneous substance
appears, containing the peculiar nucleus, which, however, requires the action
of acetic acid to displaj- it (XXX. 21).

The process of gemmation presents several peculiarities in the genus La-
genophrt/s, due mostly to the peculiar connexion between the enclosed nni-

Of TllK rROTOZOA. — CILIATA.

maleide aud its sheath. The rule seems to be that two or four gemma5_ are
produced within the sheath at the same time (XXX. 29, 34) ; but since
Stein had never encountered four, and very rarely three, gemmae upon any
animalcule, the idea crossed Ms mind that these small buds of Lagenophrys
might perhaps be embryos developed within the interior, and subsequently
discharged. Another explanation was possible, viz. that they were animal-
cules wliich had found their way into the sheath, and were quite foreign to
it. However, both these hypotheses are set aside by the history of deve-
lopment and by the characters of the beings produced. The process consists
in the enlargement of the posterior extremity (XXX. 33), or of a part of the
side of the Lagenophnjs, and the progressive detachment of the enlargement
as a segment or bud, and simultaneously the production of a band-like nu-
cleus and contractile vesicle within it. This stage being so far complete, the
gemma does not proceed to develope into the form of the parent animal, but
self -fission takes place, and two similar ovoid bodies, each with its contractile
vesicle, is the result (XXX. 29). When the constriction of the single gemma
announces approaching fission, a circlet of cilia appears on each side of it
(XXX. 34) ; and on the completion of the process, each segment has a conical
head siUTOimded with a wreath of cilia.

From this mode of production in paii's, the number of gemmae within the
sheath of Lagenoplirys should always be two or a multiple of two ; hence,
when three are seen, it is to be presmned that one has i)reviously made its
escape. From the peculiar way in which the body of the Lagenophrys is sus-
pended by its attached peristom to the orifice of the sheath, it is cleaily im-
possible that an}i;hing can dii-ectly either make its entrance into or its escape
from the animal, without rapture, of which we have no indication. The way
in which this impediment is surmounted is, on Steia's authority, by the sudden
contraction of the body of the Lagenojjlirys ruptming the adhesion of the
peristom to the orifice of the sheath, and by its subsequent retraction within
it (XXX. 31). In this manner a free exit is afi'orded to any contained
gemmae ; and after a certain time allowed for their passage, the anterior part
of the body again enlarges itself, and reassnmes its adhesion to the sheath.
After their exit. Stein has no observations to show what becomes of them •
but his idea seems to be that they do not produce a sheath until nearly
ai-rived at maturity, since they are so much smaller than the least of the
sheathed examples to be met with.

If this account be correct, the gemmation of Lagenophrys is actually a
compound process of budding and fission, whilst the resultajit beino-s differ
widely from those of other Vortlcellina in aU details, and are so very aberrant
in form from the parent, that they reqiiire to undergo a metamoi-phosis before
they gain it.

Development from Ova. Internal Germs and Embryos. Althouo-h the

reproduction of the Ciliated Protozoa is so largely provided for by the two
processes of fission and gemmation as just described, it is even more

marvellously so by their possession of true generative functions a fact

clearly established by the latest observers, although denied by Siebold
Kolliker, and others some years since, when the unicelhaar hypothesis
of Protozoic life militated against the notion of the existence of internal
ova or germs. Even now, indeed, when Ave look to the researches disclosine
to us the development and discharge of genns and of living embryos we find
diverse and contradictoiy statements concerning both the antecedent or nre
paratorj' acts, and the final results. We cannot attempt to reconcile thes«
discrepancies, but will record the principal opinions of naturalists and tho
obseiTations on which they are based.

354

GENERAL HISTOEY OF THE INFUSORIA.

In a previous page we have stated the views of Carter and Pei-ty, relative
to the existence of ova or germs in the interior of Ciliated Protozoa, and
have rejected them as unsatisfactory. Further, when we come to inquire
the process of development of the presumed ovules, theu- mode of exclusion,
and other particidars necessary to complete their histoiy and even theu*
identification, we find , that those naturalists have no direct ohsei-vations to
adduce, but can appeal only to analogy and to some casual and unconfirmed
observations of others. For instance, Mr. Carter, when treating of the develop-
ment of ovules, appeals to the process in Spongilla and Englypha, and endea-
voiu's to make out that, with some modifications, the ovules of EugJence, and pro-
bably those of all the Rhizopods and Astasice, have a similar mode of generation.

Perty, likewise, unable to advance any direct proof of the existence
of ovules and of their discharge, appeals to Eckhard's observations on Stentor
ccmnileus, which Oscar Schmidt repeated and generally confirmed. In the
recorded observation of Eckhard (A. N. H. xviii. 1846), thi-ee or four
globules, in diff'erent stages of development occurred in the interior of the
Stentor in a row (XXIX. 8-13) : — " In the fii'st stage, the contents of the
globules, consisting of minute granules, exist most imperfectly developed :
but few granules at present occur, and the globule, when it hes in the
body, is not very distinct, on account of the granular parenchyma of the lat-
ter. In the second stage of development (fig. 9) the granules appear more
numerous, the contents are therefore more concentrated, and the globules
can then be very distinctly observed in the body. Fig. 11 shows the third
stage ; granules commence aiTanging themselves in a row Or, as some-
times happens, they appear grouped in the same manner at two spots. The
granules thus arranged and closely pressed together, blend into a glandular
but clear oi'gan (fig. 12), in which the granular stnicture cannot be any longer
detected ; frequently it is also divided in two parts. Lastly, in the situation
of the transparent glandular organ a row of cilia appears, evidently the mouth
(fig. 13). Whether this organ is formed immediately from the former, I
have not been able to ascertain with certainty ; yet that it is so, is extremely
probable, since on the one hand the row of cilia occiu's in the situation of the
bright gland, whilst, on the other hand, in all the germs which exhibit this,
the former organ is absent. Simultaneously with the development of the
mouth there appear one or two clear" vesicles (fig. 13). On the ISth of
May I observed in the interior of St. cceruleus a germ as in fig. 12 ; I saw
the cilia very distinctly in motion ; the vesicles were, however, stiU absent,
and they did not escape on this occasion. On the 21 st, I saw the perfect
form (fig. 13), which issued out, whilst the parent animal swam away. I
now attentively observed the young one to follow up its fui-tlier changes,
perhaps the bursting of the carapace ; but I was obhged to leave of^ watching
it in half an hour, as I could not vouch for the accuracy of fiu-ther observa-
tion on account of the strain upon my eyes. On the 4th of June I saw a
germ escape, as in fig. 13 : it differed from that obsei-ved on the 21st of
May ; for, being at first round, it at once exhibited an incuiTation at its lower
extremity — an appearance frequently observed in young Stentoi-s, sometimes
in old ones, when they contract from the elongated form to one more or
less rounded. I have subsequently once seen tlie escape of a similar germ ;
and it appears to me that the true point of maturity is that at which vesicles
begin to be visible. In Stentor polymorphus I have observed two such
globules, but I have not succeeded in seeing any perfectly formed escape. In
autumn I have often sought for the recurrence of this phenomenon, but liave
never been able to observe it so perfectly as in the spring, altliough similar
globules are not rare in the later parts of the year."

OF THE PKOTOZOA. CILIATA.

355

From the perusal of this account, the thought arises, whether, instead
of pro-\dng the existence and progressive development of internal ovules or
germs in the sense Perty adopts, it is not another illustration of embryo-de-
velopment by a sort of gemmation or breaking up of the nucleus, such as the
researches of Cohn, Stein, Laclmiann and others have made known to us, and
concerning which we have now to speak {see Balbiani's researches, p. 329).

The development of the nucleus into embryos takes place under different
circumstances and in a varied manner in different genera of Ciliated Protozoa.
It may occui- either without the previous encysting of the animalcule, or after
this process is completed. Again, in the latter condition, and without ulterior
change or metamorphosis, either a few active embryos, or some encysted
gei-ms, may be the result, or the whole nucleus may resolve itself into a
brood of monadiform beings, or, lastly, according to the views of Stein, the
encysted animal may be metamorphosed into an Acinetiform being, out
of wliich embryos are developed diverging in character more or less com-
pletely from the original ciliated Protozoon, to which, however, they eventually
recur. The development of embryos without the previous encysting of the
animalcule has been followed out by Focke, Cohn, and Stein in Nassula and in
Paramecmm {Loxodes, Cohn) Bursaria (XXVIII. 10-14, XXIX. 28 to 34).
A portion of the nucleus is separated by fission or by an act of gemmation,
and constitutes a more or less orbicular body, in whicli a nucleus (XXIX. 34),
and then a contractile vesicle, shortly declare themselves (XXIX. 29).
Focke sm-mised that the so-caUed nucleolus originated this geiTu, which then
found, as it Avere, a lodgment and nutrition in the nucleus as in a uterus {see
Balbiani, p. 329) ; but Stein affirms that this body has nothing to do with the
origin of the germ, and is frequently to be seen separated and removed to some
distance from the nucleus (XXIX. 29). In appearance the disk-like germ is
finely granular, paler than the nucleus, and not surrounded, like the latter,
with a special membrane. Cohn represents it as existing in a distinctly
limited cavity, prolonged to the external smface as a tube or oviduct, and
terminated by a two-lipped orifice, through which the embryo makes its exit
(XXVIII. 11, 12). According to Stein, however, no such duct and external
orifice have an existence, except temporaiily, during the passage of the germ,
or germs when two or more follow in succession. This assertion of Stein
is supported by Cohn's own observation, that the point of extrusion varied
in different individuals in its position, being at one time at the middle,
at another above it, at a third below it, and, as the rule, on the left side'
although as an exception on the right side or even towards the anterior
margin. The act of birth occupies about twenty minutes ; and when the
embryo is about to escape, it exhibits a vibration on its surface, which causes
a motion in the surrounding water and hastens its detachment. This motion
after continuing a short time, ceases, and the little being attaches itself to the
exterior of tlie parent (XXIX. 30). The chasm produced in the parent
during the extnision soon closes up, and leaves no trace, except, it may be, a
slight hollow in the surface. The embiyo has an elongated fissui-e, is rounded
at each end (XXIX. 30), and frequently rather contracted at its middle ;
internally it is finely granular and colourless — not greenish, asFocke assorted—
and contains, besides a darker nucleus, one or two contractile spaces (XXVIII.
14). Cohn could discover no mouth ; but Stein displays in liis figure an
obUque fold or groove (XXIX. 30), which may possibly represent the oblique
funnel-hke vestibule of the mature Paramecium. The vibratile movement
visible about the surface indicates ciliaiy action ; and if the cmbiyo be kiUed
with iodmc, the presence of long cilia is demonstrated. Still tlio most
peculiar feature in the new-born animalcule is the possession of sevei-al soft

2 A 2

356

GENEEAL HISTOEY 01' THE INFtrSOEIA.

tentacular processes at each end, siUTOunded by small knobs, recalling- in
figiu-e the knobbed tentacles of some Acinetina (XXVIII. 14, XXIX. 30) ;
by means of these the embryo secures its hold to its parent. Such pro-
cesses are not present in aU specimens, and are therefore non-essential ; or
it may be they have disappeared by withdrawal into the general substance
of the body.

The embryo once freed from its parent, commences an independent existence,
moving freely about in the water — ^much more similar in figure and structure,
however, to some of Ehrenberg's Cycliclina or to Dujardin's EncJielyens than
to Paramecium, Cohn notes its affinity with the Cydidium margaritaceum,
or to the Pantotrichum Enclielys (Ehr.), and also with several species of
Dujardin's genus Enclielys (CyclicUum Ehr.),

Cohn adds that, in his opinion, sevei-al embryos are developed simultaneously,
and that, where only one or two are found, others have ah-eady escaped. In
some instances he has noticed as many as six or eight in process of develop-
ment, and, it woidd seem, in almost precisely the same stage, although theii-
birth is successive. Further, besides these normal embiyos, he has fre-
quently witnessed the escape of others having a globular fignu-e, clothed with
cilia and fiu'nished with tentacular processes and a contractile vesicle.

During the act of birth, the pulsations of the contractile space of the
pai'ent are uninterrupted, and the rotation of the contents is arrested imtil
every germ has escaped. Another cimous fact is, that the birth of embryo.s
may proceed as usual even whilst the act of fission is taking place in the
pai'ent animal.

The further history of the free embi'yo is not knoAvn ; yet, in all pro-
bability, it is ultimately transformed into a perfect Paramecium, — an event
which, from its figTire and stractiu'e, ensues readily and perhaps without more
than one intermediate phase.

Judging from the above details, it is probable, as before remarked, that the
development of embryos in Stentor casruleus (XXIX. 8) recorded by Eekhard
{supra, p. 354) was a precisely similar phenomenon to that jiLst described in
Paramecium ; and it is clear that the like obtains in Stentor polymorphus, in
an Opalina or Bursaria noticed by Siebold (probably the Bursaria Entozcon
Ehr., parasitic in a frog), in Urostyla grandis, as mentioned by Cohn, and in the
animalcule which we conceived to be Trichodina pediculus {A. N. H. 1S49,
iii. p. 269).

Siace tliis was written, the indefatigable laboui-s of Cohn have added
another instance of this endogenous mode of development, in Nassula
elegans {ZeitscJir. 1857, p. 143 ; XXVIII. 11-14). Tliis animalcule possesses
an elliptic nucleus, having its nucleolus lodged in a fossa near one end, and
surrounded by a vesicle, just as in the Paramecium Bursaria. Among
many specimens, Cohn found several having a large, eUiptic, liollow space,
evidently limited by a membranous wall. "VSTiere this space approaclied
nearest the external sui-face of the animalcule, this was depressed in a cup-
like form, and from its centre a canal or fissm-e (XXVIII. 11 /) penetrated
the interior of the space, where were two, never more, large globules,
in diameter (XXVIII. 11 d). After a longer or shorter delay, these globules
escaped and appeared motionless, without colour, but granular, and having a
central nucleus and an exccntric contractile vesicle. As in the instance of the
germs of Paramecium Bursaria, no cilia, but a few short, knobbed, radiating,
tentacular-looking processes (XXVIII. 14), were visible on the surface. Lastly,
Cohn noticed the formation of these gemis in animalcules recently produced
by self-fission, and which had attained only one-half their normal dimensions.

Tlio development of an embiyo within an encysted animalcule is illustrated

OF THE PEOTOZOA. CILIATA.

357

in Stein's history of Chilodon CucuUulus {op. cit. p. 134). At a preceding pago
(p. 342) we have given an abstract of the mode of encysting of this animal, and
have stated that the capsule remains gelatinous and soft. Inside the cyst,
Stein discovered an actively-moving embryo contained within a special cavity
(XXIX. 54-56), occupying precisely the spot where in other encysted Chilo-
dons the nucleus is foimd, viz. in the diagonal line connecting the two oppo-
site contractile spaces. The embryo had an oval or ovate compressed figure,
A^dth one side straight or gently ciu'ved, and the anterior extremity notched.
Its entire surface was covered with longitudinal, -widely-separated rows of
imusually long cdia, in uicessant motion, which turned it in a spiral or venni-
cidar manner. Pressure on the cyst caused its expulsion (XXIX. 59), either
alone or together with the substance of the parent- cyst, to which it always
remained adherent. This embryo. Stein concludes, is derived from the nucleus.
Many cysts may be met with in which the nucleus is replaced by a much
larger body, having a ditferent consistence, opaque and motionless, and
possessing in all respects the outline of a germ. On pressing it out of its
place, its siu-face is seen to be not quite naked, but to have short, stiff, and
imperfectly- developed cilia at one end or entirely around its margin.

Since the embryo occupies the site of the nucleus, it might at iirst sight
be supposed that the latter was whoUy transformed into it; but analogy
leads us to the contrary inference, that the nucleus, although obscured fi'om
view by the internal germ, is nevertheless present ; and this conclusion is
further supported by the fact, that a successive development of embryos goes
on untU the entire contents of the cyst are used up in their formation, an
event that does not occur without the influence of a nucleus.

Stein declares the embryo (XXIX. 59) to be precisely similar to Cyclidium
Glaucoma, both in figure and movements. Its size varies with that of the
animalcule producing it ; and individuals of aU sizes may undergo the
encysting process. The smallest cysts met with were -JL.'" in length, and
their embryo not more than -g-gi)'" 5 the largest yJg-'", and their embryo from
-j^'" to (XXIX. 56).

A remarkable circumstance happens in the case of some encysted Chilodons,
even after they have given bii'th to one or more embryos, — viz. that they
seem to emerge from their quiescent state and resume their active form. For
instance. Stein met with cysts containing a freely-moving CIdlodon, together
with an active embryo, both which ultimately escaped by an aperture in
their walls (XXIX. 58). This revivification of the ciliated Chilodon as above
refeiTed to, is urged by Stein as an argument to prove that the cilia are not
lost or destroyed when encysting takes place, but probably merely closely
compressed against the surface.

Another variety of development of germs within an encysted animalcule
is seen in Colpoda Oucidlus (XXIX. 35-47), which we have described under
the head of " Fission," since the formation of the germs is the consequence
of sclf-divison of the whole animal either into two or, as a rule, into four
segments, which themselves become individually encysted, and present their
own nucleus and contractile space. This plan of development explains the
occurrence of very small encysted Colpoda;.

It was in this genus that Ehrenberg conceived he had made oxit very
clearly the hermaphroditism and cyclical development of " Polygastriea."

A third way in which the encysting of an animalcule is made to seiTe the
process of development is by the resolution of the nucleus into a multitude
of minute segments, each eventually assuming an independent animal ex
istence. This formation of what may be called brood-cysts, occiu-s as
shown by Stem's later researches, in Vorticclla microstoma (XXIII. 10-14)

358

GENEKAL HISTORY OF THE INFUBOIilA.

Among cysts of the usual form and dimensions, are some in which a sac, not
unifoi-mly adherent to the inner surface of the capsule, contains from two to
eight, or, more generally, from four to six, oval or reniform secondary sacs,
ii-regular both in position and size (XXIII. 10, 11), and containing a didl and
fine or coarse granular matter, witliin which, again, is a clear (contractile ?)
space, but no nucleus is discoverable even when acetic acid is added. Pre-
sently these vesicles elongate, and, becoming flask-shaped, protmde their
necks through the enclosing sac and the cyst-waU (XXIII. 12, 13), and
proceed to discharge their contents (XXIII. 14) thi'ough theii- open extremi-
ties ; after which, they cornigate and wither. The discharged matter is
composed of a mass of monadiform corpuscles united together in a globose
gelatinous mass, the whole of the organic matter filling the cyst being used up.

A precisely similar act of propagation Steia also witnessed in an encysted
Vorticella nebulifera. Cienkowsky (Zeitschr. Band vi. p. 381) also reports
its occurrence in Nassula vh-idis, Duj. (XXVIII. 65-71); according to this
author's researches, the contents of the cysts of Nassula vhidis break up
into a number of globular cells (XXVIII. 68-70), which soon partake of a
certain degree of rotating movement among themselves, develope ia their
interior a multitude of what he terms swarm-spores, and at a certain period,
when mature, severally produce, in turn, a tapering neck-Hke tubular process
(XXVin. 68, 69), which perforates the softened cyst-waU and gives exit
to the spores or germs (XXVIII. 71). This accoujit tallies with that given
by Stein of certain Vorticella-cjsts. Lachmann has the following remarks
on this topic (A. N. H. 1857, xix. p. 238): — " It was only ia his most recent
observations on Vorticella microstoma, that Stein saw the production of larger
globules, ' daughter-vesicles' (TocJiterblasen), in the interior of the mother-
vesicle ; but previously he had seen nothing of the kind : it must remain
uncertain whether he had overlooked them, whether, instead of several
globules, only one veiy large one, entii'ely filling the mother-vesicle, had
been produced, or whether two different modes of development actually
occur in this case. This is the only mode of reproduction of the Infusoria
which has hitherto been observed in encysted animals alone ; but some ob-
servations made by E. Claparede and myself upon an undesciibed vagini-
coloiis Infusorium, indicate that encystation is not a necessary condition
even for this mode of propagation."

The last plan of generative development to be considered is that wherein,
according to Stein's hypothesis, the encysted animalcule undergoes an actual
metamorphosis, and subsequently, as a rule, produces an embiyo which,
although very dissimilar to the original ciliated animalcule, is nevertheless
presumed to be convertible into it after passing through one or more trans-
itory phases of existence.

This cycle of life, or, according to Steenstrup's hypothesis, this " alterna-
tion of generation," in the generative acts of ciliated Protozoa, Stein has
most diligently sought to establish as a fact, but, in the opinion of most of
the best natiu-alists, has failed so to do. Still the hypothesis is too ciuious
and interesting to be omitted from om' description, and, what is more, has
been adopted as trae by several obsen-ers. It -naU therefore be best, first
to set forth Stein's own account, and then to add the remarks and objections
of others.

On some of the branching stems of Epistylis plicatilis, and of E. nuians,
Stein encountered not only the ordinary animalcule in fidl acti^•ity and in a
contracted state, but also some pear-shaped bodies, presenting merely the
ordinaiy nucleus and a contractile space, without mouth or any remnants of
the alimentary tube or of food. On other branches, again, wci-c other

OF THE PHOTOZOA. CILIATA.

359

bodies having tlie figui-e of Acinetce, fimiishecl with tentacles slightly move-
able and more or less retractHe (XXVII. 17, 18, 19, 20). These Aciaeti-
form beings were noticed andfigm-ed by our countryman Baker a century ago ;
they, moreover, did not escape the observation of Elirenberg, in the allied
genus Opercularia, but were regarded by him as parasitic animalcules.

On another occasion, Stein met with a stem of Epistylis plicatilis bearing
some thirty Acinetoi, difFeiing among themselves very much, both in size and
in their stage of development. Each was supported on a branch presenting
the characteristics of this species, b\it smaller in dimensions, and tapering
from the base of the Acinetiform body (where it had the usual thickness of
an ^is<_i/Z/s-stalk) to its junction with the stem below. The length of the
branches also varied greatly, being in some instances not quite so much as that
of the body they supported, in others twice as long ; however, there was no
proportion between the length of the stem and the size of the body. Most
of the Acinetce had a smooth siu'faee and no tentaeula ; they were of a pyri-
form compressed figui'e, and contained a coarsely granular and homogeneous
substance, two or three irregularly-placed contractile spaces, and a central
nucleus having either the normal horse-shoe- or an elongated oval shape.
Where the Acinetce had tentacles, these processes were few and smaU, and the
surface of the body thrown into ii-regularities by its contractions ; their nuclei
were either round or oval. These Acinetce exhibited no movements, except
some slight ones affecting the tentaeula. Were their anterior extremity uja-
folded and their tentacles outspread, they would assume the figure presented
by those described in the first observations on this species, whilst the closed
pyriform bodies were precisely alike.

The further developmental history of this particular Epistylis could not be
followed out, and to arrive at the purpose of its ^cmeto-metamorphosis, the
research was extended to other species. A particular form of Acineta occurs
in company with Epistylis cligitalis, which Stein concluded to be derived from
it by a similar process to that presumed in E. pilicatilis, although Acinetce
were isolated and seated on short pedicles. At the anterior part of each
Acineta, amid the large granules crowding the homogeneous contents, were a
contractile space and, in many specimens, a moving embryo having a cylin-
drical figiu'e, roimded at each end and narrower iu the middle, where several
zones of long cUia, in apparent folds of the surface, surrounded it. In ge-
neral characters it would, as an independent organism, be referable to the
genus Trichoclina, and is probably no other than the T. vorax or T. gran-
clinella, Ehrenberg. The embryo escaped through a temporary openino-,
which closed very speedily afterwards, leaving the animal apparently unin-
jured ; moreover the tentacles, which are retracted during the birth, were
again outstretched. The conclusion arrived at is, that the ^cmeta-con'dition
is specially provided to cany out embiyonic development, and that in so doin"-
the Acineta gradually exhausts itself. *

Stein's fii'st impression was, that the embryo resulted from the develop-
ment of the entire nucleus, and that this organ was formed anew from the
general contents of the Acineta ; however, later researches lead him to be-
lieve that only a portion of the nucleus is concerned in building up the em-
biyo. No particular season seems devoted to this Acineia-iormation since
Stein ha.s observed it from the middle of March through the whole' sum-
mer, and in fewer instances until December ; moreover, embryonic gene-
ration is not restricted to any particular size of Acineta, but occurs in all
except the very smallest; nevertheless the embryo is smaller proportionablv
to the decreasmg size. Active embrj'os were seen in Acineta; of only i "'
the germ itself being only ^ '

360

GENEllAL UiaXOUY OF THE INFCSOfilA.

Besides the cysts and Aeinetce supported on brandling Episli/lis-Htema,
Stein found others attached separately by very short stalks, or nearly sessile ;
these, his observations go to show, arc probably derivable from the beings
produced by fission or gemmation, which have detached themselves from the
parent-stem in the strongly-contracted or partially-encysted condition, and,
on afterwards fixing themselves, proceeded either to complete their encysted
state or to assume the Acinetiform condition.

Another set of beings Stein is disposed to introduce in the developmental
history of Bpisti/lis digitalis, in the shape of miniature branching Vorticellina.
The branches are dichotomously disposed, very slender, short, and rigid.
Seated at the extremity of each is a small campanulate being, Avith a stiff
bristle proceeding fi'om each angle of the base (XXYII. 22, 23). Internally
they are finely granular. They exhibit slight changes of outline and jerking
movements upon their stalks ; they, moreover, can detach themselves and
swim freely away like a detached Epistylis digitalis, and may sometimes be
seen to affix themselves again by their base and produce a pedicle. These
beings, whether derived from E. digitalis or from Carchesium pygmceum —
for they occur in company with both these animalcules, — their discoverer
would regard as their earhest phase of development, and believes that not
improbably similar miniature beings belong to all the pedicellate Vorticellina.
This notion involves no great stretch of the imagination ; for there is no extra-
ordinai-y metamorphosis necessary, and we may thi'ow out the suggestion that
such minute Vorticellina are developed from the monadiform contents of the
brood-cysts.

To take another iUiistration of Stein's hypothesis from the allied genus Oper-
cularia — the 0. herherina. Direct observation is wanting to identify the Aci-
neta as belonging to this Opercidaria, except so far as contiguity on the same
filament of a plant or on the same member of a marine animal, and their frequent
occurrence, be allowed to have weight. Stein argues that the conversion of an
encysted Opereularia into an Acineta is readily conceivable, by reason of theii-
congruity of form and the existence of intermediate phases, whilst, on the con-
trary, the transformation of the cUiatcd embryo into an Acineta, without fii-st
passing through the intervening stage of an Opereidaria (a change easUy
imagined), is a circumstance scarcely probable : on similar grounds he would
associate the pear-shaped Acineta, having a ramified nucleus (XXX. 3, 4),
with Operculana articiduta (XXX. 1), as a phase of existence intei-posed
between it and its embryonic stage of a free ciliated animalcule ; but his
developmental history of Vorticella microstoma, is by far* the most elaborate,
although much too long to present here except in abstract.

His first step in the investigation of this species was the illustration of
the act of encysting (XXVII. 5 a-d) in its widest range, and the next,
to identify certain globiilar cysts, found in company with the Vorticellce, with
the cysts of those animals. These cysts were about in diameter ; they
had a clear double outline, and contained a homogeneous, transparent, colour-
less and granular substance. In most, the characteristic band-like nucleus
and contractile space were visible, together with, in many specimens, the in-
voluted ciliary apparatus and oral cavity, looking, as a whole, like a fissure
at the anterior part of the cyst (XXVII. 7, 9). In other cysts, again, nought
could be discerned save the nucleus and the contractile space, sometimes di-
vided (XXVII. 1, 8) ; and lastly, in othcre, all distinction of organs was lost,
the nucleus being the last to disappear (XXVII. 9).

Stein considered, at first, those peculiar capsules to be connected with the
process of reproduction, and, from meeting with torn empty sacs, supposed
that the interior was broken up into germs which made their escape through

01' XnE I'llOTOZOA. CILIATA.

361

the walls. With this interpretation, however, he was not satisfied ; and at
the same time his attention was aroused to the circumstance of VorticellxB
occuiTing so frequently in company with Actinophrys and Podox>hrya, and to
that of the increase in the nimiber of the one as that of the other decreased.
He therefore apphed himself to watch the changes going on in the cysts de-
scribed, and at length satisfied himself of the intermediate clianges in their
transition into Actvmplmjs or Podophrya — two varieties of the same animal-
cule, in his opinion, and not two genera, as usually represented. Stein was
brought to the conclusion that this transition takes place, by comparing Podo-
phryce at an early stage of development -«nth metamorphosed Vorticella-cjsts.
AmongPodophryce of the common form, examples occurred having their usually
wide roimded capsule produced into a hollow funnel-shaped pedicle, and thrown
into annular folds, alternating with acute, parallel, angular ridges (XXIII.
3). Most of these individuals were unarmed ; but some had numerous capi-
tate tentacles. On the other hand, old Vorticella-cjsts were foxind in which the
enclosed animal had detached itself from the cyst- wall, and become thrown into
sinuosities and elevations, the latter of which pressed against the wall, threat-
ening to rupture it. These and the above-described Podophryce Stein supposed
to merge into one another. The leading changes noticed in the encysted
Vorticellce consisted in the disappearance of the nucleus, in the multiplication
of the contractile spaces, and in the detachment of the contents from the
waUs of the cyst (which they no longer completely filled), and their disposi-
tion into in'egular and changing lobes. Thus far, in detecting such Vorticella-
cjsts, Stein proceeds by direct observation ; but his next step is simply hypo-
thesis, viz. supposing their contents to shoot out tentacula through the dense
capsule, and assume the figiu-e of Actinophrys or of Podophrya (XXIII. 1, 2,
4, 18, 19). That the metamorphosis should at one time be into the one ge-
neric form, at another into the other, he endeavours to explain by assuming
that where no resistance is offered on any side to the developing Actino-
phryan, it assumes the form of an Actinophrys, but where resistance occui's
ut one point, it there developes a stem and becomes a Podophrya. To coun-
tenance his hypothesis fui-ther, he appeals to the great similarity between
the Acinetce met with in company with Vorticella nebidifera on duck-weed,
and Podophryce — so great, he says, that when the former are detached, it is
difficult to know them from PodopJiryce.

Granting that the history of metamorphosis is thus far complete and
satisfactory, it remains to show what becomes of the Actinophiyans thus
transformed from the cysts of Vorticellce, and to reply to the question whe-
ther they originate & generative act. At the outset of this inquiry Stein
finds himself at variance with KoUiker and others respecting the structure
and vital endowments of Actinophrys. The writers referred to state Acti-
nophrys to receive food Avithin its interior, to excrete xmdigcsted matters, and
to exliibit certain powers of locomotion ; these peculiarities Stein ignores' and
insists on identifying the Acinctiform beings he has encoimtered with Actino-
phrys Sol and Podophrya fixa, which, he affirms, give bii'th to a ciliated embiTo.

This embiyo, he asserts, is produced within a defined cavity, so far laro-cr
than itseH" that it can move mthin it (XXIII. 2, 4, 5). Its figure is pear-
shaped with a central constriction, and several folds occxipied by cilia ; and
it appears composed of a finely-punctate sarcode, containing, in the axis of
its posterior and larger segment, an oval or band-like nucleus, and' near
to this a circular actively-pulsating space, and occasionally, on the other
side of the nucleus, a second smaller one. No mouth could bo detected
The being, as a whole, very closely resembles a detached gemma of Vorticella
microstoma, mto which it can be very easily conceived to be changed on fix

362

CIENEEAL KISTOKY OF THE INFUSOEIA.

ing itself by its anterior end and then developing, in its larger and hitherto
posterior segment, a mouth and cUiary wreath.

After lively rotary movements within what might be called its uterine
cavity, the embiyo escapes with a sudden bound, and gains a free, active
existence. The passage by which it has made its way through the substance
of the parent Actinoplirys continues for some time open, but i« gradually
closed up from behind. The size of the embryo is proportioned to that
of the parent, and varies between ^1^'" and -j^'". The diameter of the
smallest parent being ia which a matm-e germ presented itself, scarcely
exceeded

One other instance will suffice to illustrate Stein's hypothesis of Acineti-
form transformation. The one we select is the Vaginicola o-ystallina, which
that author attempts to show becomes, by a metamorphosis, Acineta mystacina
(XXVII. 10-15). Out of a large number of specimens contained in a
vessel of water, few could be found at the end of foui'teen days, the place
of the great majority having been assumed by Acinetina. This occurred
even when great pains were taken to isolate a certain number of Conferva-
filaments richly covered with Vagiyiicolce, and to place them in iiure spring-
water, so as to avoid the introduction of other colonists. That the Acinetai
were derived from the Vaginicolce, a comparison of the stnictm'e of the two
will indicate. The contracted body of the Vaginicola may be recognized in
the Acineta detached from the bottom of its sheath and raised to the upper
part, which it completely fills, — the mouth of the sheath having previously
been bent inwards over it as a cover, and a layer of gelatinous matter poured
out to bind the two together. The outermost parts of the roof-hke cover
project freely above this layer, and are traversed by several radiating folds or
fissiu'es. The clearest notion of the transformation effected is obtained Avhen
we can look down upon the top surface of the capsule, by getting the axis
perpendicular to the eye.

The contained body is closed in on all sides ; and its contents are substan-
tially the same as those of the body of the Vaginicola (XXYII. 12), with
numberless fine granules, and sometimes with a preponderating number of
large granules scattered through them, rendering the body opaque and of a
greyish -yeUow colour. There is Hkewise a similar round contractile space ;
but instead of a band-like nucleus, there is a rounded one. This difference
in respect of the nucleus is not important^ inasmuch as its length varies
greatly in Vaginicola according as the animal is extended or in a contracted
state, — being in the latter much shortened or merely elongated-oval, whilst
in the former its length exceeds two or three times its width. Hence it is in
no way remarkable that, in the very contracted condition of the encysted and
Acrnetiform state, the nucleus should be veiy much shortened and roimded, —
a change which analogy, indeed, with various encysted animals would lead
us to anticipate.

From the upper surface of the encysted body veiy many bristle-likc
tentacles with laiobbed ends are given off, wliich penetrate the gelatinous
layer through the fissures in the cover of the sheath, and outspread them-
selves in a radiating manner. These tentacles are for the most pai-t straight,
and slowly extend and retract themselves in length. Pressure causes their
contraction, and hudcUcs them together ; but they are not entirely \\-ith(li-a\\m.
Some smooth Acinetiform specimens are met with, which may be considered
to bo in an earlier stage, and similai' to the incomplete Acineta of Einstylis
plicatilis.

The origin of the Acinetai from Vaginicola is further substantiated by the
relative dimensions of tlio two. Thus Vaginicola; were found on Conferva;

01? TUE PliOTOZOA. CILIATA.

3G3

having sheaths betmxt and in length ; those most common were
from to 3V'" ^ length and in width. The height of the cap-
sule oie the Acineta was from to and its width not much leas.
Moreover, intermediate phases between Vaginicola and Acinetina were met
with, — as, for instance, capsules occupied anteriorly by the contracted body,
which still exhibited, upon being moved up from the bottom of the case,
the posterior annular fiuTow and traces of the ciliaiy wreath previously
existing, and had its anterior half enveloped in a gelatinous lamina, imiting
it to the inner surface of the sheath, which was at one time more, at another
less, incui-ved upon the animal, but had as yet not been converted into the
peculiar' pent-housc-likc cover.

The metamorphosis, therefore, of a Vaginicola into an Acineta may be
thus explained. The animaeule is in the first place contracted in the ordi-
nary manner ; it then developes its posterior fuiTow and ciliary wreath
(XXVII. 11), and, detaching itself from the bottom of its sheath, rises to the
upper part, which it entirely iills and closes up. From this time the rotary
apparatus and digestive tube disappear by absorption ; the excretion of the
gelatinous matter from the fore part ensues, and fixes the animal in its posi-
tion, while its tendency to fall to the bottom of the case, and to contract,
draws inwards the mouth of the case, and completes its enclosure within a
shut sac or capsule (XXVII. 12). The contractile tendency of the body
still continuing to operate, brings about a narrowing of the anterior part,
and with tliis a consequent elongation of the sheath ; in this way an ex-
planation may be given of the very long specimens frequently encountered.
The extrusion of the tentacles is an after-occurrence (XXVII. 13).

The complete Acineta can entangle small Infusoria with its tentacula,
which, by their crossing and retraction, di'aw the captured particles to the
surface, where probably theii" nutritive matters are absorbed through it;
at all events, no food or foreign particles ai'e seen in the interior.

Stein next attempts the identification of this Acineta of Vaginicola crystal-
Una with the Acineta inystacina of Ehi'cnberg, and in a subsequent paper
proceeds to show that it developes within itself a ciliated embiyo. Amid
many Acinetce, he discovered some bearing a clear oval or rounded cyst, or,
less commonly, several such, upon the surface of the enclosing lid ; where there
was a pliurality, they were evidently in different stages of development. The
cyst contained a shai-ply-defined Infusorial being, of a homogeneous finely-
graniilar substance, and having an actively-pulsating sac. At first Stein
imagined these might be animalcules casually affixed to the Acineta; ; but fiu'-
ther observation proved their organic connexion with, and derivation from it

The cyst-walls were internally soft and gelatinous, and their substance
continuous, through the fissures of the cover, with the gelatinous layer of the
Acineta, of which they might be more correctly represented pouches or
diverticula. The appended animalciile is not a bud produced from the
Acineta-hody ; for it is never foimd in organic connexion with it, but un-
doubtedly has its origin as a germ within it, and makes its way outwai-ds
In fact, it is developed from the rounded nucleus by its elongation and sub-
sequent transverse fission. The youngest cysts are round or shortly oval
and have no other inchcation of life and movement than that exhibited by the
contractile space. In the next stage they arc sUghtly cmarginato at one
end and stiU motionless, wWlst in the oldest the fissure or emaroination
extends deeply into the interior in acui-ved manner, and very clearly exhibits
a number of vibratilo cUia. In this mature state they enjoy considerable
locoraotivo powers within their capsule, and recall in their form that of con
tracted VoHicellma. Ihus, at thcii- fore part they present a rounded ciliated

3G4

GENERAL HISTOEY OV THE INFUSOEIA,

lobe, resembling somewhat a retracted rotary organ, whilst the fissure ex-
tending inwards indicates the alimentary tube.

There is yet another a^jparent mode of embryonic development in the
Acinetce of Vorticellina described by Stein, which occurred in some specimens
not provided with tentacles. In place of these, one or two short closed
tubular- processes extended from the fore part of the animalcule; of the usual
granular contents scarcely a trace remained ; and the nucleus and contractile
space had entirely vanished. The membrane of the enclosed body, thus
deprived of its ordinaiy constituents, contained, in their room, six elongated-
oval cell-like bodies, -J^'" long, which seemed to have been developed at
the cost of the contents of the original Acineta. These structures had a
shai"p outline, and contained a coarse granular substance and a contractile
sac. They seem to develope into embryos ; for in one case a ciliated furrow
Avas observed, assimilating the being to the more usual embryos of the
Acinetce. Probably the ^cmeto-condition of the Vaginicola is terminated
in this manner, after developing for a pei'iod embryos according to the plan
above mentioned, by the final breaking up of the nucleus into several large
germs.

In addition to the species described. Stein believed he made out the
^mieia-state of several other species of Vorticella, of Epistylis, and Opercu-
laria (XXX. 1-4), as well as of Zooiliamnium, Ophrydium (XXX. 5-8), and
SjpirocJiona (XXX. 18-26). However, sufficient details have been given to
illustrate the presiuned fact in the developmental history of the Ciliated Pro-
tozoa ; and we must refer those of oiu' readers desirous of more fully testing
the views of that most excellent observer, to his often-cited work, ' Die
Infusionsthiere auf ihre Entwickelungsgeschicte,' Leipzig, 1854. Jlore-
over, the several new forms of Acinetina he has pointed out wiU be found
referred to in the general history as weU as in the systematic views of that
group.

It is now incumbent on us to review the opinions of other natm-alists upon
this remarkable and interesting hypothesis. A few have accepted it, among
whom are Mr. Eusk (as we gathered from his lectiires at the College of
Surgeons in 1857) and Mi-. Carter. The latter has the following remarks
on the subject (A. N. H. 1856, xviii. p. 237) : — " I could not discover an
elongated nucleus, as Stein has figured, in the Ainoebce and Acinetce, which I
saw developing young Vorticellce, the former in plurality (one to three) and
the latter singly : if present in the Amoebous form, it was circular, and if in
the AcinetcB, undistinguishable fi-om the general ' granulation.' Again," he
goes on to say, " where are these transformations to end ? Into what kind
of Ehizopods do the sheathed Vorticellce pass ? How many of the fresh-
water Rhizopocla are alternating forms of Vorticellce ?" At the time of his
Avriting the above, Mr. Carter had not seen Stein's latest work, which would
have resolved some of the doubts and queries expressed. Thus, the German
naturalist finds the nucleus, if elongated and band-like in the encysted being,
to become orbicular or oval when in an ^ci)iete-state, and points out that acetic
acid will reveal this organ when obscui-ed by the granules of the interior.
Moreover, his later researches have been extended to sheathed Vorticellina
or Ophrydina — for instance, to Vaginicolct, of which we have given the par-
ticulars. However, it is very important to obtain Mr. Carter's st,at«meut
that he has seen young Vorticellce developed from Acinetce and Amosbce, — in-
tending by the latter, wo apprehend, Acinetce without tentacles and capsule,
and not the simple Amosbce commonly understood by that term.

The objectors to the hypothesis are by far the more numerous. The emi-
nent physiologist Johannes MiiUer, to whom Stein sliowed Actinophrys and

OF THE PllOTOZOA. CILIATA.

365

Podophrya developing embryos, could not agree with the conclusion the latter
anived at (viz. that they became Vorticellce), but was more disposed to believe
that they relapsed into Acinetce. Ehrenborg (Ueber die Formhest'dndiglceit
mid den Enhviclcelnnrjshreis der organisclien Formen, Berlin, 1852, at pp. 23,
24, and 34) attributes the theory to erroneous and hasty observation. The
supposed embryo of Acineta is, to his apprehension, simply a THchodina
which has been swallowed. To these strictures Stein replies that the Acimta-
bodies have no mouth, that they never contain any foreign matters taken as
food, and that no more than one Trichodina appears in them at a time, al-
though many may live around them, and several would, no doubt, if taken
as food, be often foimd together in the interior. It is, moreover, to be noted,
that Acineta collected fi-om the most ditferent localities contained the self-
same Trichodina-iorm, and that such forms occurred in sparing number.
Again, it must not be forgotten that the embiyo may be watched in active
movement within the Acineta for the space of an hour, whereas Infusoria swal-
lowed by other animalcules are speedily reduced to a state of rest and de-
stroyed. Lachmann rejects the hyjiothesis, and gives, in much detail, his
reasons for so doing. At the same time he confirms the fact of " the fonna-
tion of embryos, not only in many Acinetina, but also in numerous other In-
fusoria " (A. N. H. 1857, xix. p. 232), and attests the fact of the nucleus
being primarily concerned in this act of development, adding some particulars
which requii-e to be recorded. " The nucleus," he writes {loc. cit.), " is
usually seen, first of all, to divide into two or more parts, when the same
processes take jjlace in one or several of these parts, Avhich in other cases
occur in the undi\ided nucleus. Upon or in the wall of the nucleus, or of
one of its products of division, we now sometimes perceive small roimd glo-
bules, which increase in size, finally acquire a contractile vesicle, and become
converted into embiyos ; these at last become fimiished with cilia, escape out
of the parent animal, and swim about freely, generally in a fonn more or less
difi^ering from that of the mother. Veiy different numbers of embryos may
be formed in one section of the nucleus ; in the same species we sometimes
find many, and sometimes only one embryo formed in it ; and an embryo
which has been developed alone in a fragment of the nucleus is usually as
large as all the embryos formed in a similar fragment which has developed
many of them taken together.

" The tnie import of the nucleus, of course, is not decided by this state-
ment ; [we cannot say] whether it is to be regarded as a genn-stock, in
which germs are formed asexually, as an ovary, in which the ova are de-
veloped at the same time, or, in accordance with Focke's views, as a utenis
in which the ova or germs fomed in another place (perhaps in the nucle-
olus ?) are further developed.

" The fate of the embryos which are unlike their parents after their birtli
is still imknown in most cases."

Perty displays distinct opposition to Stein's views, but has not thorouglily
examined them, contenting himself with an occasional critique in passing.
For instance, he states that those miniature beings regarded as the brood of
Vorticella, both by Stein and Ehronberg (sec p. 357), are in his opinion no more
than specimens of Cercomonas tnmcata (Duj.). Again, he remarks, FMistidis
anastatica is very rai-e at Bemc ; and the TricJwdina (jrandinella, which Stein
represents to be its embryo, is veiy common in evciy collection of water •
also Vorticella microstoma is most abundantly chstributcd, but its supposed
metamorphic condition, viz. Podophrya, very uncommon. Rcspectin"- the
latter ammalcule, and Ukcwise Actinophrys, he adds an observation of his
OM'n, which convinced him of the reproduction of these animals by minute

366

GENERAL HISTORY OF THE INFUSORIA.

internal germa, which, when set free, immediately assumed the special
characters of theu- parents (Kleinste Lebenform. p. 74).

To Dr. H. Cienkowsky we owe the latest examination of this subject
(J". M. S. 1857, p. 96). He rejects Stcra's theory because, instead of finding
Podophrya fixa in company -with Vorticella microstoma, he met with it in
great abundance along with multitudes of Stylonychia myiilus and St. picstu-
lata. Having watched its process of encysting, he felt " unable to adopt
Stein's view, that the Podoplirym are enclosed in a membrane of which the
slender peduncle is simply a tubular process." In fact, he noticed cysts in
which the original slender peduncle was appended to the sacculate envelope.
He also traced, step by step, from Podophryce, the derivation of the supposed
transitional stages between Vorticella-cjsta and Podophryce, and asserts
" that they are most certainly not metamorphosed Vorticella-cjst'i, but the
commencement of the encysting of Podophryce. Podophryce are not formed
out of them ; but, on the contrary, from the latter aiise the forms above
described, which Stein looks upon as Podophryce remaining at an early stage
of development. The metamorphosed contents of older Vorticella-cjst'i, re-
garded by Stein as the first commencement of the formation of a Podo-
phrya, indicate, according to what I have seen in other infusorial cysts,
and to what Stein himself states with regard to Vorticella microstoma, the
commencement of the breaking up of the entire contents into numerous
smaller ' swarm '-cells."

Dr. Cienkowsky's next proceeding was to show the relations of the motUe
embryo developed from the Podophiyean animalcule Stein met with. He
encountered numerous Acinetce precisely lilce those fig-ured by Stein. " Most
of these Acinetce Avere without peduncles, and had no limitary membrane,
although numerous specimens might be seen with a short peduncle and
imbedded in a mucoid thick envelope ; and this was especially observed when
the Acinetce had lived for about a week on the object-glass (XXTII. 33-39).
Although numerous points of relation exist between these Acineta -forms
and Podophrya fixa (Ehr.), I am nevertheless imable to determine whether
they should be regarded as identical, or, with Stein, whether Podophrya and
Actinophrys should be considered as the extreme hnks in the moi-phological
cycle of one and the same species (Stein, loc. cit. p. 143). The peduncle of
an Acineta is a tubular elongation of the enveloping membrane, whilst in
the membraneless Podophrya it is an independent fomiation. T^Tien the
Podophryce are left in water for a few days upon the object-glass, they form
the very characteristic pedunculate cysts ; but, under the same conditions, I
have never been able to follow the Acineta-forms now in question to the
formation of cysts ; the former multiply by division, whilst in the Acinctcv
I have never noticed the occiu'rence of that process. What Stein describes
as Actinophrys is really a non-pedunculate Acineta ; the Actinophryce have
no tentacles, but seta;, though perhaps occasionally some of these set«j are
capitate. In almost every specimen of the Acineta; in question might be
seen rotating a roimd or oval embryo, of various size and position, with
one or two contractile spaces. This embryo slowly approached the wall of
the Acineta, caused it to protrude a httle outwards ; and after remaining
for a short time quiescent, it slowly made its way through the wall (XXIII.
41), and quitted the pai-ent site with the rapidity of lightning when it had
freed about half of itself. This rapidity was so great, that the course could
not be traced with a magnifying power of 170 diametera. About five minutes
elapsed from the commencement of perceptible motion to the complete libe-
ration of the embryo ; and on many occasions I saw two rotating embryos
liberated in succession. When the cmbrj'o is half out of the parent-cyst,

OF THE PROTOZOA. — CILIATA.

3G7

a transverse ring of very fine vibratile cilia may be perceived at a short
distance from its summit."

This rapidly-mo\'ing embryo was followed in its course, under the mi-
croscope, and was seen to traverse " the di-op of water from one side to the
other, in divers straight and imdulating lines, as quick as Lightning. _ Upon
meeting a mass of mucus on the edge of the drop, it bounced back again, re-
peating the manoeuvre on each occasion of the same kind ; sometimes, though
more rarely, the movement was cu-cular, around the margin of the drop.

" Judging fi-om what I had noticed in the division of the Podophryce, I
expected that the movement would not be of long duration. But after a
contiimous observation, for fully five hoiu-s, of the active motions of the tiny
biilliant point, a determination of blood to the head obliged me to desist.

" A fresh drop of the infusion, in which two embryos were in active mo-
tion, was observed at intervals of a quarter of an hour. At the end of five
hours, the rapidity of the movement was notably diminished — it became tre-
mulous, and then, perhaps, for a time, as rapid and energetic as before. I
now placed the object tmder the compoimd microscope, and continued my
observation of the indefatigable embryo for another quarter of an hour ; , the
embryo became stationary. I waited with di-awn breath what would come
next : its form from oval became spherical ; at the border appeared short,
thick, equidistant rays, wliich, after a while, were developed into elongated,
capitate tentacles ; the contractile space was visible ; and I could no longer
doubt as to the ^cf/ieia-nature of the creature (XXIII. 42, 43). This obser-
vation was twice repeated.

" It can, therefore, no longer be doubted that from the ^cmeto-embryo,
after a prolonged motile stage, another Acineta is formed. My observations
do not, of course, show that it is impossible that the motile ^a'neto-embiyo
should be transformed into a VoriicelJa, and a Vorticella-ejst into an Acineta ;
but the field of possibilities is very wide ; eveiything is possible if it only be
founded on facts. I believe, therefore, that it may justly be concluded that
Stein's Acineta doctrine, as concerns Vorticella microstoma (Ehr.), mirst be
regarded as hypothetical, and not based upon facts."

Lachmann and Claparede have jointly examined iato the facts and appear-
ances upon wliich Stein's hypothesis is based, and have presented an abstract
of their views, which are entii-ely adverse to it, in the Annales des Sciences
Naturelles, 1858, in anticipation of the publication of their essay, to which
the French Academy awarded the first prize for original researches into
the development of Inftisoria. They state that they have witnessed the
development of embryos in many other Acinetina besides those recognized
by Stein; that the embryos of diff'ercnt species vary; that the tentacles
of Acinetina are suctorial and active in seizing food, which is absorbed
with avidity into the interior ; and that the internal organization of those
animalcules is in all probability more elaborate than Stein supposed.

The appearance of the joint essay on the development of the Infusoria, by
the gentlemen mentioned, as weU as of that by Lieberkiihn, Avliich shared iii
the prize offered, will be anticipated with much eagerness and pleasm-e by
all naturalists who feel how obscure and confrised is the present state of in-
formation on the subject.

At the present time, we may say that Stein's hypothesis of the transform-
ation of Ciliated Protozoa (or, more .strictly, of the VorticeUina and Ophry-
dina, to which alone it has been sought to refer it by observation) remaijis
unproven ; yet doubtless it is a step in the right direction to arrive at a know-
ledge of the true generative process of these animalcides, and lias already proved
the development of ciliated embiyos in Acinetina and in various Ciliata.

368

GKNKHAL UISXOBY OF XHK INFUSOIIIA.

The history of the metamorphoses of Trichoda Lynceus recounted hy M.
Jiiles Haime {Ann. d. S. N. 3 sdr. xix. p. 109) calls for notice in this place,
although we are not disposed to assign it much value, inasmuch as some
of the phenomena stated are very extraordinary, are unsupported by any
parallel facts, and are in actual opposition to those best ascertained respect-
ing the organization and functions of the Ciliata. "We would especially direct
attention to the statement of the exudation of sarcode, and the consequent
reduction of size, as a necessary step in the developmental phases, — an occur-
rence, in our belief, without analogy and quite anomalous.

He first asserts that " O.vytricha (Ehr.) is a larval phase of Tnchoda I/yn-
cetis, and next that, on its fissiparous division, generally one of the two seg-
ments produced assumes a globular form, losing almost all its appendages,
both cilia and setae, and, at the same time, gives exit to successive portions
of its sarcode, so that vacuoles multiply in its interior. At this stage a ge-
latinous cyst is excreted around it which ultimately hardens into a mem-
branous envelope. In a short time the contents of the cyst shrink from the
cyst- walls and leave a space around them, when ciliary movement appears
at one part, and, a fui'ther escape of granular sarcode having taken place
through the cyst-waU, the figure becomes more or less modified. Two por-
tions are now distinguishable -within the cyst — a ciliated embryo and a mass
of eff'ete granular matter ; and, as time elapses, the former seems to grow
at the expense of the latter, and eventually makes its escape fi-om the nearly-
emptied cyst. The freed animalcule is not at first veiy difi'erent in appearance
from the parent Oxytricha, although only about two-thirds its diameter ; but
ere long it developes itself into a very dilferent being. In so doing, it first
exudes some more of its substance, then produces numerous short stiff seta;
to serve it as feet, acquires a hard integument in the fonn of a shield, or
carapace, and forms a mouth, in the fonn of a slit on one side, and, in front
of this, a gyrating filament to produce a current for the introduction of
food. In this transformed being the Aspidisca (Ehr.) is recognizable, having
a very much smaller size than the original Oxytricha. The reversed course
of development, viz. that of Aspidisca into Oxytricha has not been fol-
lowed ; but it may be conjectured that a sexual process is interposed, pro-
bably in connexion vdth other metamorphoses."

Before taldng leave of the subject of reproduction among the Ciliata, it
is important to add a statement made by Laehmann in liis excellent and
oft-quoted essay (p. 239). He writes — " With regard to the peculiar pro-
cess of copulation or zygosis of the Infusoria, as its object is still entirely
unknown, I shall only state that, except in the Diatomacece and Desmidiacea',
the position of which is still doubtful, it has hitherto been observed par-
ticularly in Actinophrys and Acinetina. According to an oral statement,
E. Claparede has also seen Vorticellina (especially V. microstoma) in zygosis ;
and I have twice met with double animals of Carcheslum, still sitting upon
a double stalk and constantly becoming more amalgamated, so that the
cavities of both the fused animals communicated, and the moi-scl which was
passed from the pharynx of one animal usually ascended in the cavity of
the other, up to the lower surface of its ciliaiy disk. The rotatory organs
remained separate ; and after the lapse of some time, the double animal cast
itself loose from the stems, and swam about for more than twentj'-fom- hours
by means of a circlet of cilia, which was produced ai-ound tlie roimded hinder
extremity formed by the coalescence of the two posterior extremities of the
individual animals."

Nature op tde Ciliathd Protozoa. Their Existence as Inbepexdext
Oboanisms. Cell Theohy applied to them. — That the beings we have com-

OF THE PROTOZOA. OlIIATA.

369

prehended under the appellation Ciliated Protozoa are indubitably animals,
has never been called in question ; nevertheless their claim to be considered
independent organisms has been challenged by a few naturalists, who insist
on their being generally nothing more than phases of development of animala
more or less elevated in the scale. These objectors have, however, hitherto failed
to produce sufficiently direct and exact obsei-vations in proof of this general
assertion, which rests mainly upon presumed external resemblances, and on
analogy with many of the inferior animals, among which the so-called
" alternation of generations " is the rule. In the foregoing pages there is
certainly sufficient evidence that some Infusorial forms are merely stages of
development of others ; and nothing is more probable than that some may
similarly be phases of animals belonging to other classes than the CiHata ;
yet, on the other hand, the independent character of several families (for
example, of Vorticellina, Ophrydina, and Colepina) has not been at all shaken
by the researches of naturalists.

There is, we believe, a true typical organization appertaining to the CUiata,
of a distinct character from that of other animal organisms, and inconverti-
ble. It may be more or less perfected, or more or less degraded, and may,
in the process of development, be put iu abeyance for a time, though not
replaced by another ; and under this impression, Stein's views of Acineti-
form metamorphosis have, to our mind, an air of improbability.

The very distiuguished naturalist M. Agassiz stands among the foremost
in advancing the sweeping conclusion, that the Ciliated Protozoa have no
existence as a class. Most of the Enterodela of Ekrenberg, he says (A. N. H.
1850, vi. p. 156), " far from being perfect animals, are only germs in an
early stage of development. The family of Vorticellce exhibits so close a
relation with the Bryozoa, and especially vrith the genus Pedicellina, that I
have no doubt that wherever Bryozoa should be placed, Vorticella should
follow, and be ranked in the same division with them. The last gr'oup of In-
fusoria— Bursaria, Paramecium, and the like — are, as I have satisfied myself
by direct investigation, germs of fresh-water worms, some of which I have
seen hatched from eggs of Planaria laid under my eyes." In these statements
Mr. Girard (Proceedings of Amencan Association, 1848, p. 402) coincides,
and adds that Ooljjoda Ciicidhdus is one of the embryonic stages of fresh- water
Planaria.

To these statements it may veiy fairly be objected, that the embryonic
animalcules presimied to be identical with certain Ciliata may possess merely
a deceptive outward resemblance, and, again, that in the case of the assigned
affinity of the Vorticellina, an exact comparative examination of the organi-
zation of this family with that of Bryozoa will show that there is no true
homology, but simply some general points of similarity, between them.

When Schleiden and others unfolded the cell-theory as a general fact in
organic beings, attempts were at once made to apply it to the simplest animal
structures, among which the CUiated Protozoa are numbered. The Protozoa
were called unicellular animals; a ceU-waU, more or less modified, was
everywhere discovered or supposed ; and the more solid body, the testis of
Ehrcnberg, was at once assumed as the " nucleus." This name we have for
convenience' sake retained, although its special relation with cell-structure
and the ceU-theoiy cannot, in our opinion, be sustained.

The cell-theory, in its application to Protozoa, found a very able advocate
in KoUiker (J. M. 8. 1853, i.), and was uphold by many others ; its simpli-
city, and the generalization as to stmctm-e and function it suggested, recom-
mencHng it to philosophic minds. Latterly, however, a more exact apprecia-
tion of the true organization and functional history of animalcules has caused

2 B

370

GENJJKAl HISTOfiY OF THE INFU80EIA.

the abandonment of the hypothesis, the greatest names in microscopic science
having pronoimcecl agtiinst it.

To Slim up the leading circumstances opposed to the theorj' in question.
The processes of the surface, both in variety of character and of movements,
ai-e not pai-alleled in any Imo^vn simple cell ; the same may be said of the
pedicles and branched stems of Vorticellina, and of the sheaths of Ophrydina :
the presence of a mouth, and, according to the descriptions of many excellent
observers, of a discharging aperture or anus, and the involution of the external
surface in the form of an alimentary tube, are facts irreconcileable with the
idea of a cell. So, likewise, the beautiful and complicated cihary apparatus
of the Vorticellirui and Ophrydina — the existence of cells, or at least of
vesicles, in the interior — the reception of external matters into the general
cavity, where they are either entirely digested or partiaUy or wholly extruded
again — and, lastly, the activity, persistence, and apparently voluntary cha-
racter of theii' movements, are circumstances without parallel in the economy
of simple cells. In the face of all these discrepancies in structure and func-
tion between the bodies of Ciliated Protozoa and simple cells — closed sacs,
containing a nucleus amid their protoplasmic substance — it appears to us it
would be a mere visionaiy notion to insist upon a homology betwixt the two.
To conceive such a thing, the accepted idea of a cell must be set aside, and
replaced by so loose and general a definition as would be worthless.

Without quoting their remarks, which is uncalled for here, the following
observers may, among others, be cited in opposition to the hypothesis of the
unicellular nature of the Ciliata ; viz. Leuckart, Lachmann, Claparede, Perty,
and Schneider. Our countryman, Mr. Busk, is, as we gathered from his lec-
tures, to be reckoned in the number.

CoNDiTiOKS OF LiFE. — Under this head we have to consider the habitats
of the Ciliata, the usual conditions under which they live, their successive
appearance in liquids, the influence of heat and cold, and of chemical agents
upon them, and their probable duration of life.

The majority of the CUiated Protozoa are inhabitants of fresh water; few
are marine ; or perhaps it would be more, coiTcct to state that few marine
species are known. Cohn afiirms that fresh water acts as a poison and IdUs
the marine forms (Entiv. pp. 132, 133) ; that the several genera of Entero-
dela (Ehr.) — Cydidium, Paramecium, Eiiplota, Oxytricha, and Vorticella —
occur in water holding organic matter in solution or decomposition ; and that
Stentor, Oplirydium, and Loxodcs are found only where the water is pm*e and
uncontaminated with dead matter. This statement must not be taken arbi-
trarily ; for among the former series, specimens are constantly seen in wat«r
free from appreciable organic impui-ities. Moreover, in all cases, the aqueous
medium in which the Ciliata live must contain a certain proportion of organic
materials (either living in the tissues of minuter organisms, or in a state of
transition, commencing decomposition or breaking up into mineral or dead
matter), from which they can derive the elements of their nutrition.

Animalcules indeed, if wc may so say, stand between the li-\-ing and the
dead, rescuing the atomic fragments of organic matter wliich are ready to
perish and to lapse into the domain of dead matter. Tluis wc find them
constantly in infusions, either ai-tificially made by steeping animal or, more
particularly, vegetable substances in water, or natm\illy occurring in ponds
and ditches containing gl•o^ving aquatic plants or their detached portions, or
in tlie turfy hoUows of commons and bogs. At times, indeed, the water in
which they occur appears to the eye almost pure, and free from extraneous
matters ; but a closer examination -will prove it to be inhabited by multitudes
of monadifoi-m existences, of minute plants, Desmidiece, Diatomece, Nostochmea,

OF THT! PROTOZOA. CILIATA.

371

Confervm, and Algm, which are diffused throughout, or float upon the surface,
or form a stratum at the bottom.

The attached forms find appropriate habitats upon the stems of aquatic
plants, and very commonly upon the surface of various animals living in
water ; for instance, on the shells of Mollusca, such as the water-snaUs, and
on the siu-face of the Entomostraca. A few species find a suitable locality
within the interior of larger animals, of which, therefore, they are esteemed
the parasites, — a fact illustrated in the genus Bursaria. This subject of the
habitats of the several genera needs not here to be enlarged upon, since it
recurs again and again ia the generic and specific descriptions of the systematic
division of our work.

The Ciliata do not so" frequently constitute the colouring ingredients in
water as do the Phytozoa. Nevertheless there are several species which
make their presence knovm by their colour, either when collected in a stratum
upon the surface of plants or of the water, or when generally diffused in a
small pool. Thus Stentor polymorjjJius and Vorticella chlorostigma coat the
stems of aquatic plants green, whilst several species of Vorticellina cover them
as with a bluish-milky film, and Stentor aureus with an orange- coloured in-
duvium. Bursaria vernalis, Trachelocerca viridis, Coleps viridis, Olaucoma
viridis, and Paramecium Chrysalis are found dispersed through the water — the
four first imparting to it a green, the last a milky tint. The greenish masses
of Ophrydium versatile at times float on the surface, driven about by the
wind, and at others are attached to the tendrils of roots and to the stalks of
aquatic plants.

The distinct colours, such as green, yellowish-red, and orange-brown, are
in all cases, we believe, not essential to the animalcules exhibiting them, but
due to the food they swallow, and to its changes in course of digestion.
These changes, as aff'ecting the colour, have been illustrated in a precediiig page
(p. 310) in the instance of Bursaria vernalis, for which the Chilodon oiiiatus
might have been substituted. Moreover, in Nassula the reddish-blue or violet
spots, conceived to be glands by Ehrenberg, are apparently the product of di-
gested Oscillatorice (p. 312).

Sttccession of Species. — If a fluid containing Infusoria be examined from
time to time over a considerable period, it will be found that certain species
disappear, and are replaced by others not before found in it. This succession
of forms in the same hquid has been remarked from the earliest period of
microscopic research, and has been the fruitful source of the wildest theories
of the metamorphoses of Infusoria. Succeeding animals have been forth-
with concluded to be the transformed states of previous ones, however wide
the dissimilarity between them : no intermediate phases or transitional chano-es
have been watched; but the conclusion that the one is derived from the
other, has been jumped at without reserve. Some theorists have even pro-
ceeded further, and, like Unger, behoved in the transformation of vegetable
into animal life, or, like Laurent and Gros, have imagined the conversion of
mineral matter into organized animalcules, and these last into beings of still
higher position in the animal scale, such as Annehda and Cnistacea.

A partial explanation of the succession of animal forms in a collection of
water is to be found in the following facts :

First, no vessel of water of ordinary dimensions can be so thoroughly ex
ammed but that some animalcules may be overiooked ; the same accident will
happen stiU more frequently with their minuter germs or embryonic condi
tions, or with their encysted state. The earliest phases, again, may in theii-
transient form, very nearly resemble certain known independent species and
be readdy mLstaken for them, or even for encysted simple plants. So, also 'por-

2b 2

372

GENEEAL HISTOBY OF THE INFUSOKIA.

tions of plants, small aquatic animals, organic debris, and other substances in
the water may conceal in their cavities or interstices either mature animalcules
or theii- immature or encysted forms. Further, we know the air to be per-
meated by animalcular life ; that every wind wafts organized beings, for the
most part in an encysted state, together with germs and spores, animal and
vegetable, to and fro ; and every exposed collection of water, unless protected
by the most careful and complex contrivances, must perpetually receive fresh
colonists. Now, among all these mature, encysted, immature, and embryonic
inhabitants of a portion of water, existing in it when first submitted to obser-
vation, or subsequently introduced into it from without, there must neces-
sarily be a constant change in their relative abundance, and even in their con-
tinued existence in it. Mature individuals may die out, be devoured by other
animals, or be otherwise destroyed before multiplying themselves, or may,
by encysting and reproduction, develope beings of a different general character,
i. e. imdergo a real transformation ; encysted beings may merge into life,
immatui-e and embryonic forms take on their perfect conformation ; hidden
organisms may come out from their concealment ; or the new ones borne by
the air may manifest themselves ; and in these and other conceivable ways
new series of inhabitants may make their appearance on the scene.

Lastly, the siiccession of species is greatly influenced by the changing con-
ditions of the water and its contents, by atmospheric conditions — cold, heat,
and electricity, and the moisture or dryness of the air. All the facts collected
under the head of Habitats indicate the mutual relations between the appear-
ance of certain animalcules and the presence of particular plants or even of
certain animals, or the existence or absence of decomposing organic matter.
We have, moreover, so to speak, carnivorous and herbivorous Ciliata, each
and all severally requiring their special nutritive elements in the water.
From these circumstances it is evident that particular species will disappear
when the conditions favourable to them fail, to be in all probability replaced
by others to which the change is favourable and necessary ; for instance, the
vegetable feeders wiU decrease and disappear when the minute plants on
which they feed are consumed ; so those animals requiring pure water will die
out when decomposing organic matters multiply, and will be replaced by the
forms which delight in their presence, but have remained imdeveloped until
the conditions favourable to their existence are brought about. The little
Coleps (to give a particular illustration) delights in the eggs and contained
substance of Entomostraca, and makes its appearance in company with those
animals, without which it is only occasionally seen. And it remains to be
noted, that imless an animalcule is duly supijlied with appropriate nourish-
ment, its reproductive powers remain in abeyance, and consequently its whole
race may vanish fi-om this cause.

A particular example of the succession of species may be qiioted from
Cohn's essay on Eeproduction of Infusoria (Zeitschr. 1851, p. 258). In a
vessel containing decomposing Sjnrogyra, at iirst appeared countless speci-
mens of Paramecium Aurelia ; these were replaced by the Proteus of Baker,
either the Lacrymaria Proteus or the Trachelocerca Olor (Elir.) ; these in
their turn were followed by Chihdon Cmullulns, and after a few days by a
Colpocla ; afterwards large Euphtes with prominent green globules, probably
a new species, and lastly, colourless specimens of Euplotes Charon exhibited
themselves, — all these species following each other in succession in the course
■of three weeks, a new form appearing on the decline of a preceding, attaining
its maximum in number, and then decreasing in its tm-n to make room for the
next in the series. Moreover, this excellent observer remarks that a similar
succession is obsei-ved in the case of microscopic plants, such as Oscillatona.

OF THE PROTOZOA. CILIATA.

373

Duration of Life. — Wliat this may be among the Ciliata is little known to
us. "The Infusoria have a comparatively long life " was one of the general facts
enunciated by Ehrcnberg. Under favourable conditions certain species have
been known to live four or five weeks. This applies to them only in one phase
of existence, viz. that which we regard as the normal and mature one. But
when we take into consideration the cncysting-process as an act of conserva-
tion, we are compelled to assign them a dui-ation of life of a very much longer
range ; for by its means the Ciliated Protozoa are preserved in a quiescent,
torpid, or hybematrag state, not only over periods of drought when the ponds
containing them may be diied up, but also during the entire winter.

Fui-ther, by the medium of fission and gemmation, the existence of the
animalcule is prolonged or perpetuated through all the multiplied series of
divisions and subdivisions and of gemmation, primary, secondary, and multi-
fold, until the chain is broken by a sexual act of generation, and the being
perishes in the production of its offspring.
- The resuscitation of Infusoria, after apparent death, forms a chapter in
Ehrenberg's great work ; but the facts discussed have little or no bearing on
this group of Ciliata ; and the marvel formerly attaching to the subject is much
diminished by our knowledge of the phenomena of encysting, whether for the
purpose simply of self-preservation or the carrying out of the process of de-
velopment.

Intluence of Externax Agents. Heat and Cokd. — The Ciliata can sup-
port very considerable variations of temperatirre. Even in winter, beneath
the ice, various species may be found still liviag. Ehrenberg tells us that
■ Vorticella microstoma will live after being exposed to a temperature of 8°
Fahr., and the ice gradually thawed ; in fact, however, not more than one in
a hundred will survive this process. Below this temperature none can Uve.
The same is true of ParamecuLm Aurelia, Cyclidium Glaucoma, Glaucoma
scintillans, and Colpoda Gucullus. When death is caused by cold, no rupture
or injury of the body is perceptible, except in the case of Chiloclon Cmullulus
and some few other species, which are frequently quite disintegrated and dis-
persed. Stentor polymorphus and S. Mulleri will not live many hours at a
temperature of 9° Fahr. ; and arborescent Vorticella, subjected to the same
degree of cold, faU from their stems and die.

Perty gives a Est of about 40 species of Ciliata which he found in Switzer-
land diuing the cold of winter, beneath the ice ; we name a few as a guide to
investigators : — Coleps hirtus (often without a shell), C. inermis ; Oxytricha
pellionclla, 0. caudata, 0. prisca, 0. gibba ; Pleuronema crassa ; Euplotes
striatus ; Vorticella patellina ; Stentor Rdsellii ; Paramecium Colpoda, P.
versutum, P. leucas; Trachelius Anas, T. Lamella, T. Meleagris ; Tracheloccrca
Olor ; Glaucoma scintillans ; Lacrymariarugosa ; Enchelys Farcimen ; Chilo-
don Cucidlidus ; Spirostomum ambiguum ; Amphileptus Fasciola &c.

Ehrenberg affirms that when animalciilcs are fi-ozcn in ice, they are as it
were lodged in a little cavity, and surrounded by water. This circumstance
he imagined to be duo to their animal heat, — an explanation too improbable
to be admissible ; and, if the observation be correct, it must give place to some
other.

Respecting the effects of cold, it is a general law of the Ciliata, that their
numbers rapidly diminish when winter sets in, and that, on the contrary
they rapidly augment so soon as the warmth of the sun in spiing manifests
itself, and continue to increase in number and variety until the height of
summer is passed. °

Their endurance of heat is almost equally extraordinary as that of cold
Some are found in hot springs : thus Perty found speoimens in the hot spmgs

374

GENEHAL HISTOliY OF THE INFUSOTilA.

of Leiik, at a temperature of about 80° ; and Elirenbcrg heated water gradu-
ally to 120° Fahr., when Colpoda Cuculhts and Chilodon Cumllulus survaved.

Necessity of Am. — The water which Ciliata inhabit must be duly aerated
to support their existence, as is shown, by the experiment of pouring a layer
of oil on the top of a vessel of water contaioing them, and by their disap-
pearance from a bottle which has been kept too long corked.

They decrease in number and variety after water has been kept for some
time in. the house, even though it remains sweet ; this is probably due in part
to the more stagnant atmosphere and the consequent diminished admixture
of air vnth the water.

Chemical Agents. Electricity ai^d Galvanism. — For chemical substances
to act, they must be soluble in the water. Sea-water is generally more or
less speedily fatal to fresh- water species ; and, on the other hand, fresh
water is destructive to marine species, especially when the change of medium
is sudden. However, some species are common both in sea- and in spring-
water ; and there are others living in brackish water which can readily ac-
commodate themselves to a change of habitation.

There are also substances, such as sugar, which, although not in them-
selves poisonous, are damaging to animalcules, probably by eausiug an in-
jurious alteration in the density of the water. Other substances, havtag
active properties as poisons to animal life at large, such as corrosive subli-
mate, strychnine, arsenic, and the like, are also poisonous to animalcules.
Reference has been made to several chemical compounds which, by reacting
variously on the tissues of animalcules, are employed for the purpose of
demonstrating points ia their organization: such are acetic acid, alcohol,
tincture of iodine, solution of potassa, &c. The last acts as a solvent, caus-
ing diffluence, as Mr. Addison pointed out some years siuce (A. If. H. 1843,
xii. p. 101).

Of the effects of electricity, galvanism, and magnetism, we know little : ex-
periments with these forces are few and imperfect. Ehrenberg collected the
accoimts of several, among which are the following : — A shock from a Leyden-
jar charged with twenty sparks from an electrophorus having a resinous plate

inches square, and a collector 5^ inches, suddenly killed Stentor niger,
St. aureus, and AmpTiileptus moniliger. The bodies of Ophryoglena atra and
Stentor poJymorphus were entirely dissipated by it, as were also those of
Epistylis fiavicans, after having first been thi'own from theii* stalks. It
generally required two such shoclcs to kill the Paramecium Aurelia. When
the electrical current passed near and not thi-ough them, their movements ap-
peared unsteady. Electricity slowly produced has a more powerful effect than
in the form of rapid shocks ; and when either it or the magnetic current de-
composes the water in which the animalcules are, then death is a necessary
consequence.

Mr. Rood (Sill. Journ. 1853, xv. p. 71) has experimented more recently,
and states that, when a feeble galvanic ciuTent is passed thi'ough water con-
taining Paramecia, the animals are brought to a stand-stUl, particularly in
the neighbourhood of the negative pole, and after rcvohiiig for a time on
their own centres, entirely cease to move ; ciliaiy action is also arrested, and
diffluence quickly ensues.

On the subject of the operation of chemical reagents on Protozoa, or, strictly
speaking, on Paramecia, -with which he cliiefly experimented, Mr. Rood ha.s
the following remarks : — Alcohol stopped theii- motion, coagulated their con-
tents so that they shrunk mthin theii- integument, and caused speedy death.
Phosphate of soda killed in a few minutes ; and Epsom salts, the aramonio-
chloride of mercury, acetate of lead, and perchloride of racrcmy destroyed

OF THE PllOTOZOA. CIIIATA.

375

life instantly. Cyanide of potassium did tlio same, producing at the same
moment ruptiu-e of the integument and the discharge of the contents. On
adding a quantity of oxcilate of ammonia to the water, a stupefying effect at
once follows, but after a few minutes the animalcules revive, and death does
not result — at least, not for some hours. Likewise, neither ferrocyanide of
potassium nor neutral chromate of potash kills — at least, not under several
hours. This last-named fact suggests the possibility of chemically injecting
or impregnating animalcules, whilst still living, with a mixtiu'o of suitable
reagents to produce coloured precipitates which might serve in demonstrating
their internal stnicture.

Geogkaphical Distribution. — "We know as yet of no special laws of geo-
graphical distribution of the Ciliated Protozoa ; and a long time must, we
fear, elapse ere the waters of the earth are sufficiently explored to warrant
even an approximative sketch of such laws. Wherever on this globe we
may seek for these animalcules, they are, it seems, to be found — even the
same families, genera, and species ; and if our present knowledge leads us to
define particular localities for particular species, it amounts to little more
than stating that they have there arrested the attention of some observer or
observers, and have been overlooked or searched for at the wrong season, or
under unfavourable circumstances, in other places. For, as our remarks on
the succession of species imply, the animalcules present in any collection of
water one week, may be in vain searched for the next ; and the inhabitants
of a pool or stream of one season, or of one year, may be exchanged for
others the next. Although, therefore, laws of geographical distribution
are wanting, yet we may be very much guided in our search for particulai*
genera and species by a knowledge of their habitats and of the conditions
which prove most favourable to their existence.

Since the whole framework of CUiata is sooner or later destructible by
diffluence, their occurrence in a fossil condition is not to be looked for.

Affinities of the Chiated Pkotozoa -with othee Animals. — Regarding
as we do the "organization of Cihatcd Protozoa as belonging to a type sui
generis, their affinities with other animals partake rather of a general than
of a particular character. They possess an affinity with Bhizopoda, Che-
garinida, and Spongilla, with Opalincea, Polypes, and with many Phytozoa,
such as Euglenoi, in the nature of their contractile substances or sarcode ;
also with the first and last-named, in the presence of one or more contractile
vesicles. Multiplication by fission is also common to those several tribes and
that by gemmation to Vorticellina, Ophrydina, and Polypes ; lastly, 'they
agree with the Ehizopoda and Polycystina in the process of dissolution by
diffluence. In the process of encysting, also, they ai-e related with the Opa-
lincea and Phytozoa, with some, at least, of the Ehizopoda, and, in general
characters, with the Qregarinida.

Of the mutual relations between the Ciliata (Opalinma, Gregarinida) and
Ehizopoda, we shall have further occasion to speak. But the CUiata ai'o
also allied to the Eotifera by the chitinous constitution of their intco-ument
by being moved chiefly by cilia, and more closely so through certain families'
e. g. the Vorticellina and Ophrydina, which liave a frontal ciliary mechanism
approaching in structure that of the rotary apparatus. So, again in some
general features, the sheathed Ophrydina (e. g. Vaginicola) may be assimi-
lated with the encased Eotatoria, such as (Ecistes and Conocliiius Lastly
by means of the Ichthrjdina an additional link is estabUshed between tliese
two classes, and also between them and the Turhellaria ; for some as Schultze
(Miiller's Archiv 1853, p. 241), seem disposed to range the IcMhydina with
the last-named family. A homology may be perceived between the hardened

376

GENEBAI, HISTOEY OF THE nTFtlSOaiA.

integument, with its uncini, styles, and setae, in such forms as Coleps and
Euplotes, and the coveiing and appendages of Entomostraca and of some in-
ferior Annelida ; and some would note the similarity in movements between
Coleps and Daphnia.

Through the Vorticellina a relation is established with the Bryozoa or
cilio-brachiate Polypes — one, indeed, which some naturalists (Agassiz, for
instance) affirm to be so intimate, that the two families should be placed to-
gether in the same group.

Lastly, there is, in the case of many Ciliata, a very close apparent affinity,
almost amounting to identity (at least, so far as form is concerned) be-
tween them and certain embryonic stages of other animals, — for example,
of Planarice and of several of the lowest among the Vermes. It is possible,
indeed, that some of the presumed independent Ciliata are nought else but
larval conditions ; but unless this can be shown by direct observation of their
development and transformation, they must be still retained in their present
place. The group represented by Bursaria and Paramecium are, as Agassiz
{A. N. H. 1850, vol. vi. p. 156) asserts he has satisfied himself by direct in-
vestigation, no other than germs of fresh-water worms, " some of which," he
writes, " I have seen hatched from eggs of Planana laid under my eyas."
To this assertion Mr. Girard assents {Proceedings of American Association,
1848, p. 402). However, there is one caution to be borne in mind in seeking
to establish the unity of certain sxipposed specific forms and known embryonic
phases of any animals — viz. not to confound general resemblance with specific
identity. For, notwithstanding the former may be very distinct and close,
this is not enough (as the history of development of the higher animals
teaches us) whUe there is aught wanting in the image, to render it an exact
counterpart of the original, identical in kind with it.

The above offers a general sketch of the most evident affinities of the
CUiata. By the exercise of the imagination directed simply to external form,
these might be greatly multiplied : this, however, would, instead of advancing
our knowledge, lead only to misconceptions.

CLASsrFicATiox OF THE CiLiATED Peotozoa. — Among the many heteroge-
neous groups of beings which have at a previous period been assembled imder
the name of Infusoria, or other tenns tantamount to it, that of the ciliated
animalcules has been more or less clearly distinguished from the rest, and
has received much attention from the several propounders of schemes of clas-
sification. However, as our knowledge of the Ciliata, both with respect to
the number of known species and to their minute organization, on which
alone any connect classification can be based, has been so greatly extended
during the last few years, it would be useless to describe the various systems
which were suggested when, as we may say, this branch of natural history
was in its infancy.

"We shall therefore omit all notice of any systematic arrangement of the
Ciliata prior to that proposed by Ehrenberg. Now, although tliis arrange-
ment is very imperfect and incorrect, and founded, moreover, upon certain
views of their organization now generally rejected, yet, as it was the system
adopted in previous editions of this work, and will be generally followed in
the present one ; and as, moreover, no other classification can lay claim to
such completeness and accuracy as to command its adoption instead, it
behoves us to detail its principal features. Besides this distribution of Ciliata,
suggested by the great micrographer of Berlin, there are three others it
will be necessary to describe in this place, severally proposed by Dujai-din,
Siebold, and Perty. Of these, however, it wiU only be necessary to present
the outline as given by theii" respective authors, since the examination of the

OF THE PBOTOZOA. CILIATA.

377

characters, limits, and mutual relations of the families described will form
the subject of the Systematic portion of this work.

The Ciliata, in our meaning, are very nearly the same beings that Ehren-
berg called Enterodela, or Polygastrica furnished with an intestine connecting
together their stomach-sacs. A division of the Enterodela was made, accord-
ing to the mutual relation in position between the two orifices of the body —
the mouth, and anus or discharging vent — into, 1st, Anopisthia, in which the
intestine is so cui-ved on itself that its two ends unite together in a common
aperture ; 2, Enantiotreta, having an oral opening at one extremity, and the
anal at the other, i. e. opposite to each other ; 3, Allotreta, with the two
orifices placed obliquely with reference to one another ; and 4, Catotreta,
with both situated on one surface — the abdominal. The subjoined tabular
view will display these divisions, and also their subdivision into families.^

We have departed from this arrangement of Ehrenberg chiefly by omitting
a few genera and species, viz, Actinophrys, Trichodiscus, and Podophrya
among the Enchelia, and some species of Bursaria from the Trachelina, and
also by adding several new genera and families. Concerning the necessity of
detaching the Actinophrys and its two congeners from the Enchelia, no doubt
can be entertained when their structure comes to be considered ; we have
throvm them together into one family under the name of Actinophryina
(p. 243), and have brought them and the peculiar beings known as Acinetina
(p. 258) together as two subdivisions of Rhizopoda. The peculiar parasitic
Bursarice without mouth constitute, with some similar ciliated mouthless
beings, a subdivision of the Ciliata, standing in near relation with Qregari-
nida, and, in some measure, intermediate between the Ciliata and Rhizopoda.
Lastly, we have removed the Ichihydina from the Rotatoria, and treated them
as a subclass of Ciliata. The additional families and genera we shall not here
specify, but must direct the reader for information to the systematic descriptions.

The following tabular view represents Ehrenberg's classification.

SECTIONS.

f

FAMILIES.

One receiving ^
and discharging
orifice only for

nutrition. [ loricated Ophrydina.

Anopisthia. J

illoricated VorticeUiria.

Two orifices
one at

each extremity, f , ■ , ■,
Enantiotreta. ) ^o'''<^^^

I illoricated Enchelia.

Colepina.

f mouth furnished

(mouth furnished with pro- "I m i ,•
boscis, tail absent ) Trachelma.
mouth anterior, tail present Ophryocercina.

illoricated Aspidi

obHquely,
Allotreta.

liscma.

Orifices
abdominal.
Catotreta.

illoricated

^ loricated

locomotive organs, cilia Kolpodea.

vai-ioiis Oxy trichina.

Euploto.

Dujardtn's distribution next claims attention. Having, as we have seen
entirely rejected Ehrenberg's polygastric hypothesis, and at the same time
failed to recognize many important points of internal organization noAv
well established, ho had, to construct his system, recourse to external

378

OENEHAL HlSTOfiT OF THE INFX780KIA.

characters only — to the presence or absence of locomotive organs, to the
characters of those organs, to the nature of the external surface, whether
protected by an integument or not, or defended by a lorica, to the general
conditions of attachment of fixed forms to other objects, and to the cha-
racter of their movements when free. Moreover, his CUiated Infusoria com-
prised not only oui- group of Ciliated Protozoa, but also the Phytozoa, — the
Vibrionia only excepted ; for he made no distinction between organisms moved
by a single or few filaments, and those moved by vibratile cilia generally dis-
tributed, or associated together in the constraction of special locomotive organs.

In his tabular view, the beings we have brought together under the appel-
lation of CiHata are aU comprehended in the fourth and fifth orders of Infu-
soria, with the exception of Coleps and the IcJithydina, which, in his opinion,
belong to a type of structiu-e differing from aU others reckoned by him as
Infusoria, in being symmetrical.

The accompanying outline of this system of Dujardin wiU sufficiently Ulus-
trate it at present, without further remarks on the value either of the piin-
ciples he has adopted, or of the families and genera he has instituted.

DUJAEDIN'S CLASSIFICATION OF CILIATA.

Order IV. — Ciliated animalcules without a contractile integument. All swimmers.

A. Naked.

Fam. 11. Ench61yens, without mouth; cUia disposed without order.

12. Trichodiens, with the mouth either visible or indicated by a Mnge of ciKa, with-

out cirrhi.

13. K^roniens, with a mouth and a fringe of cUia, together with some cirrhi or

strong cilia in the form of styles or uncini.

B. LORICATED.

Fam. 14. Ploesconiens. Lorica or shield diffluent or decomposable like the rest of the body.
15. Erviliens. Lorica genuine and persistent. A short pedicle.

Order V. — Ciliated animalcules provided with a lax, reticulated, and contractile integu-
ment ; or having their ciUa so arranged in regular linear series as to
denote the presence of an integument.

A. Always free.

Fam. 16. Leucophry ens, without a mouth.

17. Parameciens, with a mouth but no prominent row of cilia.

18. Bursariens, with a mouth and a prominent row of cUia.

B. — Either voluntarily attached or fixed by the medium of organs.
Fam. 19. Urc6olariens, voluntarily attached.

20. Vorticelliens, attached at least temporarily either by their organs or by some
part of their body.

Symmetrical Infusoria. — Of several types without mutual relations.
Planariola. Coleps. Cliaetonotus. Ichthydium.

With the exception of the family Leucophry ens, which is neai-ly equivalent
to our subgroup Opalincea, and of the genera Planariola, CJicpto7wti(s, and
Ichthydium (the two last constitute our family Ichthydina), all the other
families and genera ai'e members of oiu* class of Ciliata, and are described in
the Systematic portion of this work.

Prof. Siebold (Anatomie der Wirhellosen Thieve) agreed with Dujardin in
rejecting the Polygastrica of Ehrenberg as a class, and at the same time em-
ployed the term Infusoria, applied after Ehrenberg's example to a multitude
of various organisms both animal and vegetable, to designate a compai-ativcly
limited group. To this restricted use of the term we have already objected
(p. 199) ; we will now, therefore, proceed with the classification in question.
Siebold's Infusoria included all those microscopic organisms, exclusive of the
Rhizopoda, of supposed animal nature, whether possessing a mouth or not.
Of those ho made two classes: one named Astoma, the other Stomatoda, the
latter equivalent to our Ciliata. The following tabulai- outline is presented

OF THE PaOTOZOA. — CILIATA.

379

by Siebold, without any comments on the characters and distinctions of the
several families, which, however, agree in general with those instituted hy
Ehi-enberg, the most striking dcpartui-e being the exclusion of Ophryocercina
and Aspidiscina.

SIEBOLD'S CLASSIFICATION OF CILIATA.
Class I.— ENFUSOKIA, Animals moving by cilia.
Order 1. — Astojia, Infusoria without a moutli.
Fain. 1. Astaslea. — Gen. Amblyophis, Eiiglena, Chlorogonium.
Fam. 2. Peridini^a.— G^ew. Peridinium, Glenodinium.
Fam. 3. OpALiN.i:A. — Gen. Opalina.

Order 2. — Stom.vtoda, Infusoria with a mouth.
Fam. 1. VoRTiCELLiNA. — Gen. Stentor, Tricliodina, Vorticella, Epistylis, Cai-chesium.
Fam. 2. Ophbydina. — Gen. Vagiiucola, Cothurnia.
Fa7n. 3. Enchelia. — Gen. Actinophrys, Leucophrys, Prorodon.

Fam. 4. Trachelina. — Gen. Glaucoma, Spirostomum, Ti-achelius, Loxodes, Chilodou,

Phialina, Bursaria, Nassula.
Fam. 5. Kolpodea. — Gen. Kolpoda, Paramecium, Amphileptus.
Fam. 6. Oxytrichina. — Gen. Osyti-icba, Stylonychia.
Fam. 7. Euplota. — Gen. Euplotes, Himantophorus, Chlamidodon.

Perty is the latest writer, as far as we can discover, who has attempted a
classification of Infusoria, among which he distinguishes, as we do, a class
under the name of Ciliata, having also in almost all respects similar limits,
except in the retention of the ActinopJiryhia as one of the two sections he
makes, viz., 1, animalcules with vibratile ciHa ; and 2, with non-vibrating
but slightly contractile cilia, or filaments. Leaving this second section out
of view, the other is divided into three subsections, with the titles Spastica,
Monima, and Metabolica, according to the varying character of their move-
ments, which in the first are sudden and jerking, in the second, unvarying
and constant, and in the third, associated with striking changes in the figui'e
of the body. Under these three subsections he distributes aU the Ciliata into
families, to many of which, in departing from Ehrenberg's groupings, he has
given new names. He moreover describes many new genera and species.
Besides the Actinophryina, we exclude also the family Cobalina, which is
equal to our family OpalincBa, and to Dujardin's Leucophryens.

We shall attempt to represent this system of classification by a tabular
outline : —

PERTY'S CLASSIFICATION OF CILIATA.

A. Spastica. — Animalcules capable of contracting their bodies and their stems when stick

exist, in a sudden spasmodic manner, so that their more or less elongated
figure is rendered oval or globular, and the stem coiled spirally. Thcij
are the only Ciliata which live associated, and are related to Brvozoa
and many to Eotaioria. '

Fam. I. Vaginiper.1.— Enclosed in a sheath, into which they can withdraw tliemselves
Mouth with a ciHary wreath.

Fam. 2. Vorticellina.— Without a sheath ; living isolately, or in arborescent polyparies ■
with a contractUe body and evident mouth, but no intestine. Deve-
loped by fission, by germs, and gemmation, and by means of transi-
tional phases.

Fam. 3. Ophrvdina.— Numerous animalcules associated together in a solid gelatinous mass
but virithout contractile fibres. '

Fam. 4. Urceolarina. — The Urctolarions of Dujardin, Ophrydium being excluded and
Spirostomum added. '

B. Uomuk.— Animalcules which, although very contractile, neither undergo chanae of form

nor exhibit jerking movements. a J J

_ a. General covering soft.— I. Free fonns, with a mouth ; nutriment received solid
Fam. o. Bursarina. o^hu.

Fam. 6. Paramecina.— Body covered by longitudinal rows of cilia. MouUi lateral oft««

situated in a furrow. . '
Fam. 7. Holopiiryina.— Mouth anterior; anus posterior. Cilia in longitudinal rows.

380

GENEEAL HISTOET OF THE lUFUSOfilA.

Fam. 8. Aphthonia. — Surface ciliated, and furnished besides with filamente.

Fam. 9. Decteria. — Moutli provided with a circlet of bristles ; in three genera lateral, in

two anterior in position.
Fam. 10. CiNETOCiiiLiNA. — Mouth on the upper surface, furnished with a vibrating flap.

Cilia in longitudinal lines.
Fam. 11. Apionidina (in part the Enchelia, Ehr., and the Param^ciens, Duj.). — Bodies

small, soft, thicker at one end than the other ; cUia in longitudinal

rows. Mouth, where perceptible, at the anterior extremity.
Fam. 12. Tapinia. — Cilia scattered, or collected in particular spots, but never in rows.

Body usually very small. Mouth only proved to exist by means of

artificial feeding.

Fam. 13. Traohblina. — Body elongated into a neck-like anterior process, or a laterally
curved trunk.

Fam,. 14. Oxytrichina. — ^Equal the Kdroniens of Dujardin.

2. Parasitical forms, with or without a Tnouth, mostly receiving only the juices of
other animals.

Fam. 15. Cobalina. — ^Body mostly flattened, oval, elliptic or reniform, covered by numer-
ous rows of fine cilia, and oftentimes vrith jointed cilia on the under
surface. A raised margin or hollow fold occupied by cOia often
indicates the mouth, of which, however, in several cases, no trace is
evident. The animalcules commonly live internally, upon the juices
of other beings, and occasionally on their outer surface, in which case
the food they take is soUd. They jjresent among themselves numerous
peculiarities and points of agreement, and at the same time many
anomalies, and are lower in the scale than free living forms similar to
them, e.g. Oxytrichina; their movements are rather automatic. Tlie
genera included are, Alastor (Kerona, Ehr.), Plagiotoma, Leucophrys,
and Opalina.

B. General covering firm by induration of the integument, or by excretion of hard

granules.

Fam. 16. Euplotina.— Equal the Ploesconiens of Dujardin.
Fam. 17. Colepina. — Represented by the genus Coleps (Ehr.).

C. MjiTABOLicA. — Very contractile ; undergoing protean alterations of their figure through
a contraction and extension of the body. Cilia scarcely observable on
the body at large, but collected on the necJc-like process.

Fam. 18. Ophryocercina (Ehr.), including also Trachelocerca and Phialina.

FAMILY I.— ICHTHYDmA.
(Plates XXY. 357, 358. Plate XXXI. 28, 29, 31.)
This family, wHch in our arrangement forms a subgroup of Ciliata, con-
stituted in Ehrenberg's system a section of Rotatoria, — an association which
cannot be maintained now that their more intimate and essential organiza-
tion is known. Indeed, these beings seem to have received but little atten-
tion from that great naturalist, who had only an imperfect accoimt of them
to offer. They were described as Eotatoria with a single continuous rotary
organ, not cut or lobed at the margin, and -without lorica or sheU. Pour
genera were enumerated — viz. Ptygura, Ichthydium, CJicetoiwtios, and Oleno-
johora. Their relative peculiarities were thus stated : — Ptygura and Gleno-
phora had a simple rotary locomotive organ; Ichthydium and Chcetomtus,
only a long ciliary band upon the ventral surface. Again, the two former
had a simple foot-Like process, and evident oesophageal teeth ; the two latter
a forked taU and no visible teeth. Dujardin, who has given a very good
account of Chcetonotus, rejected that genus, together with Ichthydhtm, from
among the Rotatoria, and placed the two in a sort of subfamily of Cihated
Protozoa, under the name of ' Symmetrical Infusoria.' Of the other two
genera, Olenophora and Ptygura, he ignored altogether the former, and
transposed the latter to his family of ' Melicerfiais.' Since the date of his
systematic treatise {Hist, des Inftis. 1841), ho has sketched the liistorj' of a
genus under the name of ElUmoderia, which is evidently alUcd to Chatomtus
(A. S. N. XV. p. 158).

OF THE PROTOZOA. TCHTHTDINA.

381

The latest researches, we have seen, on the Ichthydina are contained in a
paper by Dr. Max. Schiiltze {Mull. Archiv, 1853, p. 241), on Chcetonotus and
IchtJnjcl'mm, and on a new allied genus, Turbanella. In this communication
Schvdtze clearly shows that Chcetonotus and IcMhydium are not Eotatoria,
whilst he admits Ptygura and Olenopliora to be so. The leadmg and suffi-
cient reasons for separating Ichthydium and Chcetonotus from Eotatoria are,
that they want the peculiar ciliary apparatus of that class have no retractile
rotary disk, no jointed tail-like process, no water-vascular system with
vibratile tags, and no perceptible muscular and nervous system. The best
account of the organization we have of any of the Ichthydina is furnished by
Schultze's contribution above quoted, wherein he details that of Turbanella.
Of this we will present an abstract, but, before so doing, wiU preface a few
notes from Dujardin on Chcetonotus. This genus has a symmetrical elongated-
oblong body slightly contracted at its anterior third, and having its posterior
half expanded ; covered on its upper or posterior surface by cilia or by ciliated
scales ; terminated anteriorly by a rounded edge, near to which is a distinct
circular oral aperture ; and posteriorly ending by a bifurcate process. Some
long vibratile ciha are visible on the anterior half of the ventral surface ; and
Dujardin thought he discovered four or five minute papOlas around the mouth.
This aperture he represents to lead iato a long narrow oesophagus, which
abruptly ends in a wide intestine, that continues a straight course to the
posterior extremity, where an anal opening is probably placed. The Turba-
nella hycdina, of Schultze, has an elongated, rather compressed, colourless
body, from -^th to -^th. of an inch long, and j^th to -g^th broad. The head is
separated from the body by a constriction (XXXI. 28). Along the body, at
apparently regTilar distances, numerous bristle-hke processes stand out at right
angles on each side. The posterior extremity is slightly contracted, and
divided into two comb-Hke flattened processes or lamellae, having an inter-
vening fossa, into which the anal apertm-e opens. A dorsal and ventral
surface are distinguishable, — the latter ciliated throughout, the former bare.
The head is entirely covered on its iipper surface by fine cilia, besides which,
it has a circlet of larger ones around its middle. The cihated condition of
the under surface is displayed by a side or a transverse view of the animal.
The bristle-hke processes on each side are growths from the integument, and
neither articidated nor separable (XXXI. 28, 30). The row is double on
either side ; the under setae from 20 to 25 in number ; the upper, only from
G to 8 on a side. The latter are rather appendages of the dorsal surface,
and are, moreover, not at right angles Hlce the others, but bent backward!
Each cutaneous process is terminated by a motionless cilium, equal to or ex-
ceeding it in length. The cuticle and its processes are soluble in a wai-m
solution of potash, and are not chitinous.

The alimentary canal passes straight through the middle of the body (XXX.
28, 29). The mouth, situated at the anterior extremity, is circular, and sur-
rounded by a finely plicate or dentate margin ; it opens into a muscular
oesophagus, which very much resembles that of Anguillula, and terminates
below in the straight intestine. The oesophagus extends for the first fourth
of tlio length of the body ; and its muscular coat is so developed, that its canal
looks Uke a mere central hue. Its muscles are annular. The tubular intes-
tine has, on the contrary, thin walls, in which numerous molecules and fat
corpuscles are distinguishable, except, indeed, at its posterior conical termina-
tion. The intestine Hes in a soft, finely-granular parenchyma. No water-
vascular apparatus with vibratile tags exists. At the posterior thii-d of the
body on the dorsal surface of the intestine, a large ovaiy is placed, and in
front of It a very much smaUer testis. Both glands present a mi^dberry-

382

GENERAL HISTOET OP THE INFUSORIA.

like aggregation of rounded cells. The posterior portion of the ovary exhibits
ova, having a germinal vesicle and spot suiTounded by a fine granular yelk-
mass ; and one or two ova are frequently seen separated, having a deUcate
colourless shell developed around them. The diameter of the largest ova
equals xItf^Ii* mature eggs lie close to the testes. Besides this distinct

male organ, two groups of spematozoid-ceiia seem present, lying apparently
free in the loose parenchyma, and apparently without any investing membrane
or envelope. As to their affinity, Schultze makes no doubt that they are
Vermes, and belong to the group of Turbellaria, considered as a division of
the Cestoidea. Among Turbellaria they are best placed with the Ai-hynchia,
including Microstomum and Dinophilm. They resemble Nematoklea and
Anguillulce in the form of the intestinal canal, but are unlike these in their
figui-e, their ciliated integument, and their hermaphrodite structure.

The Ichthtfdina are inhabitants of fresh water, living among aquatic plants.
They have a sluggish, creeping gliding movement, resembling that of most
Turbellaria.

FAMILY II.— NOCTILUCIDA.

(Plate XXXI. 32-39).

This small but remarkable subsection is represented by only one animal,
the Noctiluca miliaris, which has attracted much attention as one of the
sources of the phosphorescence of the sea. By several recent authors it
has been treated as a near aUy of the CUiata, although it must be confessed
to have few outward indications of such a relationship, and, in our estima-
tion, is a representative of quite a different and independent group of
animals. At first sight, a Noctiluca appears a round gelatinous corpuscle
having a depression or groove at one part, surmounted by a filamentary pro-
cess or tentacle. Compared with the Ciliated Protozoa, it is of gigantic pro-
portions, attaining -^th of an inch in diameter. On closer examination it is
found to have an integument of two layers : the outer smooth and reticular,
structureless, and of considerable density ; the inner a delicate, granular,
gelatinous membrane, which Dr. Webb (J. M. S. 1855, p. 103) describes to be
in union at all points with the whole system of reticulations spreading from
the central organs, — a fact rendered evident by the action of indigo and the
primary changes consequent on death. " The internal fibrous reticulations
gradually contracted, drawing the ' vacuoles ' together, and with them the
inner membrane. This was detached without ruptiu'e, but after a time feU
into folds, which so included the other structxu-es as to have the look of a
wrinkled tube with a series of pouches ending in a larger membranous sac.
The external layer distended by degrees till it suddenly burst. I should
mention that a new supply of water had been given before most of these
changes happened. I have also been successful in separating the two layers
mechanically, by means of pressure, slowly and steadily applied to the animal
under the screw compressor." The external membrane is extended at one
point into a tapering process, which acts as a locomotive organ. ^ It springs
from the edge of the infundibulum, which is extended backwards into a pha-
rynx or gullet. This process or tentacle appears transversely striped, and
breaks short ; of the nature of those stripes we know nothing. Dr. Webb
believes this process to be tubular, with an orifice on the inner side at
its base. " At any rate," he writes, " I have seen the coloxir, when iodine
has been used, proceed towards the distal extremity ; and under the influence
of indigo poisoning, the granular matter of which the striation consists has
been disarranged, scattered up and down the interior of the organ, and in the
end has aggregated together in small globules, without much impairing the

OF THE PROTOZOA. NOOTILUCIDA.

383

power of motion." These appearances do not at all convince ns of the tubular
character of the tentacle ; for they are attributable to the difference of action
of the chemical reagents upon the contained matter and upon its investment.
Dr. Webb adds — " I have never perceived any tendency to restoration of the
lost part, nor any independent movement in the detached fragment. The
stump continues active, and readily comes off at the base. The point is a
little flattened. When the animal is kUIed in such a manner that this organ
has free play, it always shows a disposition to coil up spirally."

Prof. Huxley's compaiison of the Noctiluca, in figure, to a peach is very-
good, and conveys a clear idea of the relative position of the external groove
and its appendages (J. M. S. 1854, p. 50). " One surface," he writes, " is a
httle excavated ; and a groove or depression runs fi-om one side of the excava-
tion, halfway to the other pole. Where the stalk of the peach might be, a
filiform tentacle, equal in length to about the diameter of the body, depends
from it, and exhibits slow wavy motions when the creature is in full activity.
I have even seen a Noctiluca appear to push repeatedly against obstacles with
this tentacle." Eehind the tentacle is a rounded or oval mouth, having a
harder margin extending from the base of the tentacle, along its right side, in
the form of an elevated ridge. This ridge has a horny appearance (although
Dr. Webb declares it to be of fibrous consistence), and is usually described as
sigmoid in outline. About its middle is a triple (tricuspid) tooth-like eleva-
tion, composed of a middle, bifid, large portion, and a smaller one on each side.
Dr. Webb says that when this tooth is " seen in profile, it has the appear-
ance of a conical papilla, or, with a slight change in the point of view, of a
hooked process terminating in a sharp nib. It readily yields to pressure ;
and I have seen it become shrivelled up from the use of astringents, before
motion ceased in the cihum and tentacle .... The ridge may be sometimes
observed in regular contractile action. Corresponding with these contrac-
tions, I have witnessed a to-and-fro motion of the tooth, as though working
on an axis in a direction towards the base of the tentacle. A good illustra-
tion of this performance is given by bending the fore and middle fingers, and
flexing them on the palm of the hand." On the other hand. Prof. Huxley
states that he never observed any movement in this tooth-like body.

The oral aperture opens into a funnel-like cavity or pharynx, from the
bottom of which a ciliary process extends, having a rapid undulatory move-
ment, and retractile. Mr. Huxley only now and then detected this cilium

and states that it is difficult of observation ; but Dr. Webb says " The

cilium may be found in every instance in which it is looked for with a
quarter-inch glass, or even with the half-inch, provided the creatm-e is left
at perfect liberty, and is made to move if not in the right position. It often
remains at rest for some time, and then from above looks liko a smaU bright
spot at the base of the ' tooth ; ' or it may occasionally be seen extended over
the S-shapcd ridge, or even the base of the tentacle. I have many times
detected it in motion from behind, through the intervening substance of the
body, and have noticed it vibrating vigorously long after ruptui-e of the
integument and partial discharge of the contents. A Chara-trough, or shallow
concave cell, is most convenient for observations on this part, as 'the animal
swims close to the under surface of the thin glass, and may be made to turn
in any direction."

_ A minute oval aperture is represented both by Huxley and Webb as open
ing into the funnel-shaped oral cavity. This last expands into an alimentarv
space "of very vanous form and dimensions, capable of great dilatation and
presenting no distinct walls, but rather excavated in the central substance of
the body, which IS connected with the parietes by numerous granular radi

384

GENERAL HISTOllY OF THE 1NFU80EIA,

ating filaments " {Huxley's Lectures, Medical Times, 1856, vol. xxxiii. p. 511).
These granular filaments radiate, from a central portion which seems to
serve as a bond of union and a basis of support for all the organs about the
oral cavity, to the integument in every direction ; and probably the apparent
reticulation of the external membrane is due to the crossing of the very
fine terminations of those filaments as they proceed to attach themselves to
it. Lying amid the meshes of this fibrous network, chiefly towards the
centre of the Noctiluca, axe more or feAver vacuolar bodies. " The whole
internal network of fibrous tissue," writes Dr. Webb (op. dt. p. 104), " with
the manner in which it invests the so-called vacuoles, is most beautifully
demonstrated by the effect of iodine. The creature dies suddenly, without
collapsing. The progress of the fluid can be traced along the fibres into the
minutest meshes ; and there remains for a long time a transparent ball,
traversed in every direction by the brown fibres, headed with the vacuoles
and granules, and having every reticulation on the surface sharply defined."

The " vacuoles " referred to are not homologous with those of Protozoa,
and, to avoid confusion, another name should be found for them. They are
actual sacs or cells, with a definite membranous wall, and thus appear to
resemble in structure the contractile sacs of Protozoa. Dr. Webb asserts
them to be alimentary sacs ; and we gather fi'om him the following account
of them (op. cit. p. 105) : — "When empty, they are usually contracted and
grouped near the membranous tube which leads from the oral aperture —
a few only being scattered among the internal reticulations. Their situa-
tion is constantly changing, sometimes with a steady advance, at others by
jerks, while the fibrous meshes with which they are connected undergo a
relative alteration in shape. Gentle pressure wlU occasionally expel them
through the oral or anal aperture ; but I have seen them spontaneously
ejected without rupture, and float away from the body. In one instance
where this occurred, and where the contents consisted of granular matter,
fragments of Diatomacece, and particles of sand, the sac remained entire for
some time. When it burst, the membrane doubled up, the contents escaped,
and the bits of silica were characteristically shown with the polariscope. I
have never laiown these gastric pouches, or alimentaiy substances to be
voided by any other outlet than those connected with the central depression."

At the bottom of the infundibulum is a large-sized oval, or ovoid, brownish
body, of granular consistence, and strongly refracting Hght, which is the
nucleus. It lies in front of and above the gastric cavity, and, Prof. Huxley
states (op. cit. p. 54), assumes the appearance of a hollow vesicle when acted
upon by acetic acid. Dr. Webb writes (op. cit. p. 106) — " The nucleus may
be demonstrated as a nucleated vesicle, sometimes solitary, more frequently
with several similar but smaller nucleated vesicles grouped around it. By
careful manipulation it may be removed from the other structures ; and as it
floats about, its true form is displayed. Seen in one position, you have a view
of a round vesicle with a smaller vesicle attached to it by a sort of houi-- glass
contraction ; in another, of a roimd vesicle with a central spot, a nucleated
ceU. I have found the nucleus enclosed in a second membranous envelope
with a granular yelk-lilte fluid, which could be seen pouiing out when the
membrane gave way."

The reproduction of the NoctiJucida is as yet not understood. Quatrefages
and Krohn, Prof. Huxley informs us (op. cit. p. 54), " consider that a process
of fissiparous multiplication takes place, and that both of these observers have
found double individuals, though very rarely. According to tlic latter writer,
division of the body is preceded by that of the nucleus. I have not had the
good fortune to meet with any of these forms ; and the only indication of a

OF THE PROTOZOA. NOCTXLUCIDA.

385

possible reproductive apparatus, which I have seen, consisted of a number of
granulai- vesicular bodies of about ^r^sjs^^ diameter, scattered over

the sui-face of the anterior and inferior part of the body." Dr. Webb (op.
dt. p. 105) has the following observations on this subject : — " I have never
met with a double individual, but on one occasion witnessed the process of
di\ision, without, however, noting any proof of its connexion with that of
fissiparous miiltiplication. Contractions of the integument took place in such
a way as to cut off a globular mass fi-om the body, about one-fourth of the
whole. The two portions aftei-wards retained their form, with a puckered
mark at the point of separation. The nucleus was not involved in this ope-
ration, which occupied about two hours.

"It is also a matter of eveiy-day observation, that when the body has
been torn and nearly all the contents have been lost, the animal continues to
live in a deformed state, if the nucleus and central parts are left together.
They acquire a new investment ; or a portion of the original integument
gathers up round them, while the ragged shi'eds are cast off.

" When several of these creatures have been kept for some time in still
water, it is not imusual to find two of them in apposition ; but I have never
discovered any indications of conjunction, and look upon the condition as one
of mere adhesion. It may, however, have given rise to the mention of double
individuals, as the adhesion is tolerably firm. It may easily be broken up
without injxiry to either animal."

In the Jom-n. of Micr. Science for 1855, p. 99, is the translation of a paper
by Dr. Biisch on the structm-e and function of Noctilma, in which several
original obsei'vations are given which appear to bear on this question of de-
velopment. There is, however, such uncertainty about them, and the want
of confirmatory evidence, that we deem it unnecessary to quote them, and must
therefore refer our readers to the Joiimal cited. The fourth volume of the same
excellent periodical (p. 74) contains a translation of a paper by Prof. Miiller,
from which it appears that this distinguished natiu-aUst had discovered Nocti-
liica in an encysted condition. The accoimt he gives stands thiis : — " These
encysted bodies constituted the principal limiinous animalcules observed at
Messina in the autumn of 1853. Free JSfoctihtcce at that season were not
seen there ; and in 1849 the same kind of encysted bodies were very common
at Nice. The cyst is a perfectly transparent, spherical capsule, with a light-
bluish brilliancy at the edge, and appearing like the egg-membrane of some
Crustacea. Within this cyst is lodged a body in all respects resembling the
Noctiluca miliaiis, except that at this time no vibratile filament can be per-
ceived. The Noct 'duca-\\ke creature fills the cyst more or less entirely, though
occasionally it is much smaller. In this condition the animalcules are lumi-
nous without being agitated. When the cysts are examined under the
microscope in a small quantity of sea- water, in such a way that during the
obsei-vation the saline contents are notably increased in consequence of the
evaporation, a moment speedily arrives when the Noctilma-VikQ body sud-
! denly contracts itself within its case into a little nodule ; that is to say, it
contracts upon the yellowish granular nucleus from which the filamentaiy
strings of the interior proceed. I have noticed this vital phenomenon, not
on one occasion only, but in many of the encysted animalcules.

" The size of the case is usually from i'" to 1'". But many are far smaller,
even down to Occasionally also, instead of a Noctiluca, cysts may be

observed, containing a yellow nucleus in diameter ; and once I noticed
a cyst in size, containing, besides this rounded yeUow nucleus, quite
isolated, an extremely minute Noctiliica-]\\.& body. Of the free Noctilucerv.
taken near Heligoland in the autumn, the smallest were and the larger

2 c

386

GENEEAL HISTOEY OF TBTE INFUSOEIA,

■3S'" *o diameter. The common variety of fonn, with a constriction

of the circumference, which is noticed in free Noctilucoe, and the radiating
filamentary branching striae beset with extremely minute granules in the
interior, were also characteristic of the encysted bodies, which 1 should be
more indisposed to separate from the Noctilucce, from their possessing the
most remarkable luminous power. At present we want the key to these re-
remarkable phenomena, as well as aU knowledge of the development and
course of life of the Noctilucce."

We have, in our prefatory observations on this family, alluded to the
opinion of the affinity of Noctilucida with Ciliated Protozoa. Prof. Huxley
(op. cit. p. 54) has the foHovping notes on this subject : — " If the preceding
account be correct, it is obvious that the animal is no Rhizopod, but must be
promoted from the lowest rank of the Protozoa to the highest. The exist-
ence of a dental armature and of a distinct anal aperture, are structural
peculiarities which greatly increase the affinity to such forms as Colpoda
and Paramecium, indicated by Krohn. Noctiluca might be regarded as a
gigantic Infusorium with the grooved body of Colpoda, the long process of
TracJielius, and the dental armature of Nassula united in one animal.

" On the other hand, the general absence of cUia over the body, and the
wide difiPerences in detail, would require the constitution of at least a distinct
family for this singular creatui-e."

To our apprehension there is no homology between the dental armature of
Noctiluca and of Nassula. In the latter, the so-called teeth appear to be
nothing more than hardened folds of the membranous tube of the oesophagus,
which may disappear by distension, — ^whilst in Noctiluca it is the condensed
uncinate margin of the oral cavity on one side which constitutes the dental
apparatus. Again, as to the presence of a distinct anal aperture, this cer-
tainly establishes no other affinity with the higher Ciliata than it does with
any other microscopic animalcules which possess such an outlet. On the
contrary, there is force in the particiilars mentioned as opposed to their re-
lation with the Ciliata, viz. " the general absence of cilia, and the wide differ-
ences in detail;" for cilia either diffused over the body, or collected into
groups to form a special ciliary organ, are, when taken in connexion with
the peculiar internal organization, so very characteristic that no microscopist,
unbiassed by imagination, would reckon Noctiluca among CUiata. In further
opposition to the notion of such an affinity, it may be ujged that Noctiluca is
destitute of a ciliated contractile oesophagus, and of a contractile vesicle,
that it does not produce vacuoles in the introduction and transmission of food,
and that its so-called vacuoles appear to be actual closed sacs, separable from
the body. Other distinctive peculiarities between the two might be ad-
duced ; but we think that, on reflection and a comparison between them, ob-
servers will agree with us that Noctiluca is not a member of the Ciliated
Protozoa, that it cannot be included among them as a new family, but must
be placed in some other class of animalciHes, or of itself form the representa-
tive of a new class.

The Noctilucida are inhabitants of the ocean, of the luminosity of which
they seem to be the most potent cause, of the many which have bfeen
foimd in operation. They occur in the British seas, as well as elsewhere,
floating on the surface of the water. Mr. Byerly, of Liveipool, noticed
their prevalence in such numbers that the water acquired a rose-colour :
and Dr. Webb (op. cit. p. 102) intimates that their luminosity must depend
on some peculiar condition of their organs, or the media acting upon them.
ITiis supposition is analogous to that made by Ehrenberg respecting the
phosphorescence of the Peridinicea, which he believed to be due to what he

OF THE PROTOZOA. DYSTEBIA.

387

termed the " ovaries," or the masses of brownish-red matter which sometimes
nearly fill the interior. Perhaps the bro-\vn granular matter which at times
accumulates in and about the nucleus of Noctilvm, and which is probably
related to the reproductive function, is the luminous material in this ani-
mal ; and there is nothing contrary to analogy in supposing the development
of phosphorescence to be associated with a particular period of vital activity,
but rather everything in its favour. The following valuable note on the
collection of specimens occurs in Dr. Webb's excellent paper {op. cit. p. 102) :
. — "As a caution to those who may undertake the further examination, I may
state that the buoyancy of the Noctilvxa is such as to bring it to the surface
of tranquil water without any apparent effort, and that the best way to
effect its capture is, not as is most frequently done, to use the muslin net, by
which means the greater number of the creatures are lost or destroyed, but
to skim the top, and especially those parts near the sides of the vessel in
which the water has been standing. If removed in this way, and kept by
themselves in a test-tube, they may be preserved for two or three weeks
without a fresh supply of water. Even at the end of that time, if they die,
it does not appear to be from having reached the natural term of their ex-
istence, but as the result of some accidental cause ; they will not, however,
bear carriage to any great distance ia closed vessels."

We gather the following hints for the capture of Noctilucida from a paper
by Col. Baddeley {T. M. S. 1858, p. 79) :—" Attach," he says, « a fine muslin
net to the end of a light pole, and proceed to some spot where the Noctilu-
cida are likely to be driven. A breakwater which causes an eddy to collect
Medusae, &c. generally yields a good harvest. Skim the sui-face, and wash
the net repeatedly in a can of salt water. At night these creatures are easily
seen by their lumiuosity ; by day, if plentiful, they cover the surface of the
sea in brownish streaks .... The best winds ia which to capture these crea-
tures appear to be those from south to west ; during their prevalence, I
have taken Noctiluece every month of the year on the east coast of England ;
but it is during the summer months they are most abundant, and during
calm weather. Abroad, they are constantly to be met with in warm lati-
tudes ; and I feel confident some interesting results might be obtained by
securing these creatures in various parts of the world." In conclusion he
refers to the Diatomece which are so commonly found in considerable quantities
in their interior.

FAMILY III.— DTSTERIA.
(Plate XXXI. Figs. 24-27.)

Dysteria, which is clearly the type of a new family of animalcules, was so
named by Prof. Huxley in honour of its discoverer, Mr. Dyster. Although
its exact systematic position and affinity are not agi-ced upon, it certainly
occupies a position in the zoological scale above the Ciliata, if it does not
rightly take its place, as Mr. Gosse contends, among the Rotatoria

As we have unfortunately no knowledge, personally, of this interestine
I being ; we must avail oiirselves of the excellent description afforded by Prof,
Huxley (./. M. S. 1857, p. 78), and of the critical examination of its affinities
furnished by Mr. Gosse (ibid. p. 138).

" Dysteria armata has an oval body, -jj^^th to ^th of an inch long, by
thi^^ to ^th broad, which is not altogether syrameti-ical— the one side
] presenting a considerable evenly-rounded convexity, while the other, less
prominent, is divided by an angulated longitudinal ridge into a smaller
dorsal, and a larger, ventral area. The edges of both lateral surface.? are

2 c 2

388

GENERAL HISTORY OF THE INFUSORIA.

sharp and thin ; dorsally they are separated by a shallow gi-oove ; but along
the ventral line of the body the groove is deep and narrow, and the produced
edges of the lateral parietes resemble the valves of a bivalve shell.

The ventral and dorsal grooves pass into one another in front ; but pos-
teriorly the lateral edges are united for a short space. The edge of the left,
less convex, side of the body ends anteriorly in an obtuse point, which cor-
responds with the anterior termination of the angulated ridge, and does not
extend by any means so far forward as the edge of the right side, which re-
mains thin, and forms the anterior extremity of the body.

" At the anterior extremity, the large oral aperture is seen, just below the
angulated ridge, and occupying the bottom of a deep fossa, which here takes
the place of the dorsal and ventral grooves. The left waU. of this fossa is
thickened, and projects inwards so as to form a cushion-like lobe, clothed
with remarkably long cilia ; and these cilia are continued into the oral aper-
ture itself, — the posterior ones being large, usually directed transversely to
the axis of the body, and having at times much the appearance of vibratile
membranes.

" The bottom of the oral fossa is strengthened by a curious curved rod,
which terminates superiorly in a bifid tooth, while inferiorly it appears to
become lost in the waU of the fossa.

" But there is a much more prominent and easily distinguishable apparatus
of hard parts situated on the opposite or ventral side of the mouth, and ex-
tending thence through two-thirds of the length of the body. It consists of
two portions — an anterior, somewhat rounded mass, in apposition with a
much elongated, styliform, posterior portion.

" It is very difficult to assm-e oneself of the precise structure of the ante-
rior portion ; but it would seem to be a deep ring, composed of three pieces —
two supero-lateral and mutually-corresponding, united with a third, inferior,
azygos portion. The latter is somewhat triangular, with a broad base and
rounded obtuse apex, — the latter being directed foi-wards, and immediately
underlying the oral aperture, while the former is turned backwards, and
unites Avith the two supero-lateral pieces. Each of these is concave inter-
nally, and convex externally, so as to form a segment of a circle, and presents
a clear median space, the optical expression either of a perforation or of a
inuch-thinned spot.

" The anterior edge of each supero-lateral piece is nearly straight ; but the
posterior is convex, and it is by this edge that it articulates with, or is ap-
posed to, the anterior extremity of the posterior division of the apparatus.
Viewed laterally, this posterior portion appears to consist of two styles,
which are somewhat like nails in shape, — their anterior extremities being
tnmcated, so as to present a sort of nail-head, while the posterior ex-
tremity seems to taper to a fine point. Rather in front of the middle of its
inferior edge each style seems to give off a short process downwards ; and
this process is, in botanical language, docurront upon the style. Careful
examination of the dorsal or ventral aspect of these parts shows that tlie
decm-rent process is, in fact, only the expression of a delicate membrane, which
is bent so as to have a ventral convexity, and connects together the two
styles. It might be said, therefore, that the posterior part of the apparatus
is a triangular mcml)rane, deeply excavated in front, bent so as to be convex
downwards, and ha^nng its margins thickened and produced into stylifom
enlargements. This curious piece of mechanism is directed upwards and
backwards, and terminates in the substance of the body without any apparent
connexion with other parts.

" The whole apparatus is moveable. The posterior portion is pushed against

OF THE PBOTOZOA. DYSTEEIA.

389

the anterior ; and the heads of the styles come into contact with thepostenor
convex edges of the siipero -lateral pieces, and push them forwards; the
posterior portion is then retracted, and the whole apparatus returns to its
previous arrangement.

" In one Di/steria, which had swallowed a filament of Oscillaioria so long
that the one extremity projected from the mouth when the other was as far
back in the body as it could go, these movements took place as many as
twenty times in a minute.

" Mr. Dyster fiu-ther informs me that in one of these animals which he
saw feed, the fi-ond of Oscillatoria was rather ' swum upon ' than seized —
ingestion being accomplished by a smooth gliding motion, apparently without
displacement of the styles, — but that, when the act was completed, the styles
* gave a kind of snap and moved slightly forwards.'

" Mr. Dyster is inclined to think that the Oscillatoria passed through the
anterior ring-like portion of the apparatus. I have not seen the animal feed,
but, on structural grounds, I should rather have been inclined to place
the oral aperture at, and to suppose that the food would pass above, the
anterior ring. The apparatus is destroyed by caustic potash, but remains
imaltered on the addition of acetic acid ; it is therefore probably entirely
composed of animal matter.

" Immediately above the anniilar portion of the apparatus, there is inva-
riably present a remarkable amethyst-coloured globule, apparently composed
of a homogeneoiis fluid. It has on an average a diameter of -^-^y^ in., and
it is entirely lodged in the more convex portion of the body. In many spe-
cimens no other colouring matter than this can be detected ; but in some,
minute granules (jYkwo ^0 ^ similar colour are scattered through the
body. "What connexion these have with the large constant globule is not
clear, since, although the dimensions of the latter vary fi'om the size given
above to one-fourth or less, no relation could be observed between this
diminution and the presence of the gi-anules in other parts of the body.

" Behind the amethystine globule, the substance of the body has the ap-
pearance, common to the Infusoria generally, of a mass of ' sarcode,' in
which the ingested matters are imbedded, and no clear evidence could be
obtained of the existence of any digestive cavity with distinct walls.

" A little behind the middle of the body, and towards its ventral edge,
there is a clear spheroidal ' contractile space/ which varies a good deal in
size. One measured ^ J^^th of an inch in diameter, and became entirely
obliterated in the contracted state.

" The contractions arc not rhythmical, but take place irregularly. On the
approach of death, the space becomes ii-regularly and enormously enlarged,
until it occupies perhaps a third of the whole contents of the body.

" Immediately beyond the contractile space there is a ciuious oval body,
having its long axis (-7^ in.) directed upwards, and containing a compara-
tively small central cavity, so that it appears like a thick- walled sac.

" Indications strongly suggestive of an inferior opening wore sometimes
observed ia this body ; but no demonstrative evidence of the existence of any
such aperture could be obtained.

" The walls of the ventral groove are provided with long and powerful
cUia— a remarkably strong one being attached behind the base of the
' appendage ; ' and by their means the animal, when free, is propelled at
no very rapid rate through the water. Its more usual habit, however, is
to remain fixed by means of the peculiar appendage ; and tlien the cilia 'act
merely in creating currents, by which nutiitive matters are brought towards
the mouth.

390

GENERAL HISTOIIY OF THE INFUSORIA.

" The appendage referred to is attached to the surface of the body, rather
towards the convex side, at the bottom of the ventral groove, and is distant
about one-fifth of the whole length from the posterior extremity. It is
fW*^ ToW]''^ of an inch in length, and is not altogether unlike a boot
with a very pointed toe in shape ; and the toe appears to be viscid at its
extremity, so as readily to adhere to any foreign object. The appendage
then forms a pivot on which the whole body turns about ; and this appears to
be the habitual and favourite position of the Dysteria.

" Internally, the appendage contains a canal, wider above than below, and
apparently blmd at each extremity.

" No ' nucleus ' could be foimd, though carefully sought for with the aid
of acetic acid.

" The occurrence of transverse fission was noticed very distinctly in one
case ; but it is remarkable that, notwithstanding the great number of speci-
mens which were observed, no other iastance of this mode of multiplication
came under the notice of Mr. Dyster or myself. It would appear that the
' apparatus ' disappears, and is reproduced during fission ; for, in the single
case observed, mere nidiments of it were to be seen in each half of the
strongly-constricted mass.

"Dysteria has not hitherto been observed to become encysted, although
this condition has been earefiiUy sought for.

" The creature was found in swarms among the Algae, coating the shells
of a Patella and a Idttorina which had long inhabited a marine vivarium.

" There can " (p. 82) " be little doubt as to the tnie systematic position
of Dysteria. The absence, in an animal which takes solid nutriment, of an
alimentary canal with distinct waUs, united with the presence of a contrac-
tile vesicle, with the power of transverse fission, and with cilia as locomotive
organs, is a combination of characters found only in the Infusoria. In this
class, again, the existence of a sort of shell or lorica, constituted by the
structureless outer layer of the body ; the presence of a submarginal ciliated
groove around a large part of the margins of the body ; and the inequality
of the two lateral halves, leave no alternative save that of arranging Dysteria
near or in the Euplota of Ehrenberg.

" Indeed, there is one species figured by Ehrenberg (Infusionsthierchen,
p. 480, pi. 42. fig. 14), Euplotes macrostylus, found at "Wismar, on the Baltic,
which, in general aspect, and in the possession of a foot-like appendage,
so closely resembles the present form, that, were it not for the absence of
any allusion to the amethystine globule, or to the ' apparatus,' I should be
strongly inclined to think it identical with Dysteria. That an internal
armature is not inconsistent with the general plan of the Euplota, is shown
by Chlamidodon, whose apparatus of styles would probably repay re-exami-
nation.

" Notwithstanding certain analogies which might be shown to exist be-
tween the manducatory apparatus of some Eotifera (see, e. g., that of Furcu-
laria marina, figured by Mr. Gosse, in his excellent memoir, P7ii7. Travis.
1846) and the ' apparatus ' of Dysteria, I see no gi-ounds for regarding the
latter as in any way an annectant form between these groups."

Mr. Gosse dissents from this conclusion of Prof. Huxley relative to its
connexion with Euplota, and considers it a member of the family Monocer-
cadece among the Kotifera.

" Presuming," ho says (J. M. S. 1857, p. 138), " Dysteria to be an In-
fusorium, it must be a species sui generis, with no close affinity ^\^th the
Euplotidce. An animal whose soft parts are enclosed between two deeply-
compressed valves, and which crawls by the aid of a hinged shelly foot, is

OF THE PROTOZOA. DYbXEfilA.

391

widely different from one gi-eatly depressed, covered with a dorsal plate, and
whose organs of locomotion are short flexible seta) scattered over the soft
ventral surface.

" But I am by no means sui-e that it should be placed among the Infusoria
at all. Mr. Huxley obseiTCS that ' the absence, in an animal which takes
solid nutriment, of an alimentary canal with distinct walls, united with the
presence of a contractile vesicle, with the power of transverse fission, and
with cilia as locomotive organs, is a combination of characters found only in
the Infusoria.

" Now the presence of a contractile vesicle, and of locomotive cilia, are
quite as characteristic of the Eotifera as of the Infusoria. The absence of
an alimentary canal is, I think, not proved : it seemed to me that the animal
possessed a defined digestive cavity, though very ample. In Sacculus — an
indubitable Rotiferon, which carries its large eggs in the manner of a Bra-
chionus — the alimentaay canal, without apparent distiuction of stomach and
intestine, is so large that it occupies fully five-sixths of the whole volume of
the lorica ; and though it is invariably found filled with a green Alga, on
which the animal feeds, the waUs of the digestive cavity are not better defined
than in Dysteria. There remains, then, only the fact of increase by trans-
verse fission. This, I confess, is a strong point, if well established. But it
does not seem certain, from Mr. Huxley's words, whether he witnessed the
progress of constriction from an eaiiy stage until two perfect animals wei'e
formed out of one, or only saw an inividual so strongly constricted that the
result seemed legitimately inferable. If the latter was the case, is it not just
possible that it was an example, not of spontaneous fission, but of malforma-
tion, instances of which are frequent among the highest animals ? It is highly
worthy of note that the nucleus, so characteristic of the Infusoria, was not
found, even under careful search with acetic acid.

" The presence, position, and movements of the foot, hinged as it is upon
a tubercle, and the form of the principal organs of manducation, seem to me
to determine the place of Dysteria within the class Eotifera ; while, at the
same time, the lack of internal motion, the apparent want of distinct muscle-
bands, the great extent of the vibratory ciha, and the absence of a rotatory
arrangement, show that it occupies one of the vanishing points of the class."

Mr. Gosse next proceeds to examine to which group of Rotatoria it ap-
proaches most nearly, and concludes, as above intimated, that it ought to
have a place in the family Monocercadece, represented by the genera Mono-
cerca and Mastigocerca, although, at the same time, a very aberrant ^enus.
He adds " that it has also remote relations with the Salinnadce, and especially
with the ColuridcB (through Monura) ; and that it is an annectant form be-
tween the Eotifera and the Infusoria (i. e. the Ciliata), with a preponderance
of the characters of the former class."

392

GENEUAL HISTORY OF THE INFCSOBIA.

Sect. IV.— OP THE ROTATORIA OR ROTIFERA.
(Plates XXXII.-XL.).

Genfeal Chaeactees. — Symmetrical animals, having a distinct head and
body; the former surmounted by a wreath of cilia, the latter presenting
transverse folds or joints, with a simple alimentary canal and internal maxil-
lary apparatus ; a muscular and a water- vascular system ; nerves and nervous
ganglia, but not an-anged in a symmetrical chain ; reproductive organs sepa-
rate in opposite sexes ; and propagation without undergoing actual metamor-
phosis, by ova of two forms. The Eotatoria, moreover, are destitute of limbs
in pairs, but have mostly the posterior extremity of the body produced as a
powerful, although a symmetrical, organ of locomotion, in which a transverse
ai-ticulation is particularly evident.

This is a very natural group of animals, — its chai-acters being definite, and
readily recognized by reason of the comparatively large size and transparency
of the organisms. The name Rotatoria, sometimes exchanged for Rotifera,
is derived from the apparent whirling or wheel (?-oto)-like motion of the
ciliary wreath around the head, seen in most species. Since this rotary
movement is not universal, and at best but an ocular deception, some ob-
servers have been discontent with the appellations derived therefrom ; and
Dujardin, for one, has suggested as preferable the term ' SystoUdes,' as
inicative of the remarkable contractile and flexible nature of their bodies.
They are also still spoken of under the old name of ' wheel-animalcTiles ; '
indeed, the early observers of the class actually believed the animals to be
furnished with wheels, by the rotation of which they moved.

ExTEENAL FoEM, Integtjment, AND AiFENDAGES. — The Eotifera are symme-
trical, and in this respect contrast mth the asymmetrical Protozoa. They
present a determinable dorsal and abdominal surface, and consequently a right
and a left side. They have an oblong, ovoid, or much-elongated figure, and
are mostly separable, by the presence of a constriction more or less developed,
into an anterior segment or head, and a larger posterior one or trunk. The
extension of the latter in a tail-like fashion may be regarded as a thii-d seg-
ment. The constriction or narrower portion behind the head is frequently
called the neck ; this is wanting in many cases, and then the head is undistin-
guishable from the trunk as a distinct section, e. g. in Notonimata MyrmeJeo.
On the contraiy, the separation of the head from the tnmk is well seen in
Brachionus (XXXIX. 15-18 ; XL. 11), Steplianops (XL. 8-10), Eudilanh
(XXXIX. 4), Noteus (XXXVin. 25), and Melicerta (XXXVII. 17). The
articulation of the tail-like segment is always evident. In a certain number
this prolongation is wanting ; and the animal is then tailless, — e. g. Anuraui
(XXXV. 495-498) and Sacculus (XXXIX. 18).

To facilitate the recognition of the general divisions of the body of Rotatoria,
considered as bilateral symmetrical animals, Mr. Gosse furnishes the foUoAving
remarks (Phil. Trans. 1855, p. 424) : — The bilateral organization is, he ob-
serves, in most cases " obvious, — the motions of the animal, like those of the
footed larvae of insects, being performed on the belly, with the head foremost.
Where this is not the case (as with those genera Avhich, either with or witli-

OF THE ROTATORIA.

393

\ out on enveloping tube, adhere to foreign substances by the tip of the foot,
ond elevate the body in an erect position), the dorsal aspect is always deter-
minable by the eye or eyes being towards that smface, by the stomach and
intestine passing down it, and by the cloaca being on that side of the foot.
The ventrtd aspect has the manducatory apparatus and the ovary."

But, besides these great divisions, all the Kotifera exhibit transverse lines,
folds, or joints, analogous to those seen in the Articulata, especially among
the Crustacea, such as the lobster and shrimp. Mostly, such are but folds or
wrinkles^ and not true articulations, in the Eotatoria (though perhaps as much
so as the like in the larvae of many insects), and consequently disappear on
the extension of the animals. However, in not a few instances, veritable
articulations occirr, — e. g. Hydatina, Rotifer, Eosphora, Philodina (XXXVIII.
1, 2). In Eiiclilanis dilatata, writes Ehrenberg, the abdominal surface pre-
sents four decided articulations. The minimum development of the articulate
condition occurs in those genera the most removed from the Rotatorial type,
viz. in Stephanoceros (XXXVII. 1), Lacinularia (XXXVII. 19), and some
anomalous Notommata (XXXVIII. 28), which only present fine lines under
the surface, looking like annular threads. The construction of the joints is
peculiar, one portion or segment sliding within another after the manner of
the tubes of a telescope. This telescopic action is best illustrated in the
genus Philodina, where the entire body is fusiform and articulated ; but it is
oftentimes to be seen also in the tail-process, when absent or imperfect in
the rest of the body, — e. g. Brachionus, Noteiis (XXXVIII. 25), Stephanojps
(XL. 8-10), Scaridium (XXXVIII. 22). An incomplete articulation, or
mere wi-inkling, is seen in the pedicle of Megalotrocha, Melicerta, and Lacinu-
laria (XXXVII. 17-19).

All the Rotatoria are invested by a firm, usually smooth and elastic,
integument or skin, which follows the contained pai-enehyma in all its con-
tractions, accommodating itself to the various movements of the body. It is
more delicate on the head, where the ciHa are inserted, and there becomes
continuous with the membrane of the iaterior. It is composed of two layers
— an external, the cuticle, and an irmer, immediately subjacent, the dermis
(XXXVIII. 26). Where the structure is not evident, it may be rendered so
by the use of chromic acid. The cuticle is homogeneous, structureless, and
firmer than the dermis, which is soft, granular, and contains in its thickness
numerous fat-globules and nucleated particles (XXXVII. 29). The latter
tissue acts as a lining to the general cavity of the body, and gives attachment
to the muscular cords of the interior. It is much developed about the head
beneath the vibratUe ciliaiy apparatus, and there sends inwards numerous
projections or lobes (XL. 2), which Ehrenberg assimied to be of a muscular
natm-e, and to be permeated by vessels and nerves. At other parts also
delicate fibres or threads are seen to pass inwards from the dermis to the
viscera, sustaining and connecting them together. Those fibres have some-
times been described as muscles, at other times as nerves. The former is
apparently their tnie nature, although, as Cohn believes, nerve-fibres may be
mixed among them.

_ The integument is histologically, i. e. in its anatomical nature, a connective
tissue derived from the coalescence of branching cells, and stiU presents in
its inner layer the scattered nuclei of the original ceUs, in the form of the
nucleated particles described. Where the dermis is much developed its soft
ti-ssuc becomes here and there hoUowed out into clear spaces or vacuoles
which h-jvc been mistaken for nerve-ganglions, especiaUy when situated in
the head (XXXVII. 29). So, again, at the posterior part of the body
behind the viscera, and in its prolongation or foot-process, where the dermic

394

GENEHAL HI8T0KY 01? THE INFUSOEIA.

tissue abounds, the vacuolar thickenings have been conceived to represent
ganglions or, otherwise, glands.

The cuticle, or external limiting membrane of the integument, is hardened
by the deposition in it of the peculiar chemical principle chitine, the same
which imparts firmness to the coveiing of Entomostraca, Insects, and other
Articyilata ; or if not actually chitine, it is a substance closely allied thereto.
This is Leydig's opinion, and it seems sufficiently confirmed by the reaction
of chemical agents. Thus, he shows that caustic alkali (potash) does not dis-
solve the cuticle when it possesses, as it usually does, moderate firmness, in
other words, when an infusion of chitine exists in its substance. But when
the animal lives within an external case, and does not need the protection of
an immediately investing skeleton, the chitine is absent, and the integument
dissolves in the alkali. The analogue of this may be found among the
Articulata.

The prevalent opinion has been, that the dense cuticle or external skeleton
of Eotifera diifered from that of the Crustacea and other Articulata in not
being of a chitinous nature ; and this hypothesis was used in arguments
relative to the affinities of the Rotatoria. Thus Kaufmann advances it as a
decided distinction between this class and the Tardigrada; but, as Leydig
remarks, the skin of the latter animals is even more affected by potash than
that of the Rotifera (see section on the Affinities of E.otatoria).

The cuticle, as just intimated, differs much in firmness and thickness in
different species. It is softest in those which live in an external case — e. g.
Stephanoceros, Melicerta, Tubicolaria, — and in such as are invested by a
gelatinous sheath — e. g. Notommata centrura. In Diglena, Notommata aurita
(XXXVI. 3, 4), Asplanchna, and others, it is fii-mer, but stiU flexible ;
whilst in such genera as Brachionus (XXXIX. 16, 17, 21), Noteus, Sdlpina,
and EuManis (XXXIX. 4) it attains a rigid, horny consistence, resembling
that of the shells of Entomostraca. Even where the skin is of considerable
flrmness, it is yet capable of distension, as Perty observed in the Scandium
longicaudum when its stomach was stretched with food. The form of the
body is much modified by the degree of firmness of the iategiunent. "When
this is soft and yielding, or flexible, the figure is rounded, and more or less
elongated, and may taper towards one or both extremities ; but when the
cuticle is much hardened, the rounded configuration is often lost, and various
irregularities in form result. Por example, in Metopidia and in Etichlanis
dilatata (XXXVIII. 5) the body is ovate and compressed, or depressed ; in
Euchlanis triquetra it is triangular (XXXIV. 443) ; in E. liipposideros and in
Lepadella (XXXTV. 430-432) the dorsum is convex, the abdominal siuface
flat ; in Noteus quadricornis (XXXVIII. 25-27), suborbicular and com-
pressed ; ia Mastigocerca carinata and JRatulus carinatus (XXXTV. 438-440)
it is prismatic, with one angular ridge or crest ; in Golurus, compressed
laterally.

There is, besides, a direct relation between the segmentation of the integu-
ment, the perfection of its articulate condition, and the degree of firmness of
the integument. The soft-skinned Rotatoria only tlirow their bodies into
folds during contraction, whilst those with firmer cuticle, such as Phihdincea,
develope the sliding joints, and, lastly, those (c. g. Lepadella and Euchlanis)
which have a dense homy covering present two or three decided segments,
recalling in form and disposition the divisions of the external skeleton of the
monocular Entomostraca, or even of the liigher Crustacea.

Where the cuticle is condensed into a rigid, homy lamina, defending the
animal like the shell of a Crustacean or the carapace of a tortoise, it may
well be termed a testa, testula, or lorica. This last name was very loosely

OF THE KOTATOHIA.

395

used by Ehrenberg, being alike applied to the soft, pliant skin, to the hard
sheU-like cuticle, and to the loose and large external cases in which some
Rotatoria hve, as do the Coralliae Polypes, in a cell or chamber. If limited,
however, in its signification, as above suggested, the term may still be use-
fully retained, and is preferable to the word ' shell,' which peculiarly belongs
to the habitation of the Mollusca. By some authors the term carapace is
employed ; but to this there occurs a similar objection.

The lorica received fi-om Ehrenberg vaiious names, according to its form.
Where a fii-m cuticle entirely enveloped the trunk, leaving the head and tail
free, it constituted a testula, as in Pterodina ; where it covered only the upper
surface and sides, it formed a scutellum or shield, as in Monura (XXXIV.
457-459). The term ' carapace,' employed by some authors, is equivalent
to scutellum. The anterior and posterior openings of a testule vary much in
different species ; and an equal diversity occurs in the space left uncovered
by a scuteUum. This space is small and very narrow in Euchlanis Lynceus,
in Kpyriformis, and in E. dejiexa. In the last, moreover, the fi-ee edges are
bent outwards at right angles. In several genera, again, the lorica appears
composed of an upper and an under plate, or is, in other words, bivalved.
This is seen in Dinocharis (XXXIV. 454, 455), Salpina, and Golurus, and
resembles the envelope in some of the lower Crustacea, as Cypris. In a few
Eotifera, e. g. Euchlanis (XXXVIII. 5), the lorica appears much too large,
the contained viscera only partially filling it. An increased firmness of the
lorica enables it to resist decomposition longer than its soft contents ; hence
the occurrence of empty ones. Where the integument is of sufficient firmness
to present an anterior and posterior margin, it is subject to many variations
in form. Thus it may be truncate in fi-ont, as in Hydatina, Diglena
(XXXIII. 403-405), and Polyarthra (XXXVIII. 30) ; or behind, as in
Notommata Felis. It is crescentic in Metopidia ; deeply and widely notched
in Lepadella patella ; has several spines, in front only, in Anuroia ; and both
anteriorly and posteriorly in Noteus, Salpina (XXXIV. 447-453), and Bi-a-
chionus (XXXIV. 499-501). Sometimes the spines are so short and wide,
that the border appears simply dentated or undulated ; in other cases, spines
may be long and strong, and themselves dentated, as in Noteus quadricornis
(XXXVni. 25). Not only do the anterior and posterior margins diflfer, but
even those of the upper and under surface of the lorica, for example, in
Salpina spinigera and in S. mucronata. Animals with spines projecting from
the anterior margin, Ehrenberg speaks of as ' horned.'

The surface of the integument is variously modified. Ths slightest change
from the normal smooth condition consists in a shagreened, dotted, or stippled
surface, or in the presence of fine lines, — e. g. in Anurcea inermis, Dinocharis
and Diglena lacustris. In Notommata centrura, fine silky prominences clothe
the surface. In Noteus quadricornis and Brachionus militaris, the points are
elevated, and give the surface a rough (scabrous) aspect. Lines crossing each
other, producing a tessellated or reticulated concUtion, are seen in A7ittra;a
curvicornis and in Brachionus BaJceri ; whilst in Anurcea testudo, Brachionus
militaris (XXXIX. 21, 22), and Noteus quadricornis (XXXVIII. 25) the
lines assume the character of ridges, and divide the sui-face into squares or
facettes. Radiating or curved striae arc seen in Anurcea striata and A.
foliacea, which in Euchlanis Lynceus are replaced by flutings.

The elevated points may assume a further development, and project from
the surface in the form of curved spines or hooks {acidei), as in Fhilodina
aculeata ; or they may be so extended in length as to form long spines or
rigid styles or setae having particular functions, as in Triarthra (XXXVIII,
30, 31, 32), and Polyarthra, where they are important organs of locomotion'.

39G

GENERAL HISTOEY OF THE INFUSOKIA.

In the last-named genus they attain a still more complex nature, and assume
a plumose (feather-like) stioicture (XXXVIII. 30).

The opposite condition is seen in depressions or pits, few and scattered, on
the surface of the integument, often apparently surroimded by a margin.
Illustrations are found on the dorsum of Folyarthra, of Notommata Myrnuleo,
and of N. Sieboldii (XXXVII. 32).

AH the marldngs and processes of the integument of Rotatoria are produc-
tions of the chitinous cuticle, just as haii-s, feathers, horns, and claws in the
Vertebrata originate from the epidermis. They are similarly affected by
chemical reagents, and decompose with the same facility as the integument
which supports them. They are, moreover, of much value in supplying
generic and specific characters.

Several genera possess, in addition to the integument immediately investing
them, an external sheath or case, to the bottom of which they are attached
by a prolongation of the body in the form of a contractile pedicle. This
external sheath received from Ehrenberg the particular designation of
' urceolus ; ' and consequently the beings inhabiting it were said to be urceo-
lated, or, as many prefer to say, are ' encased.' The composition of the case
varies greatly ; for, although it originates always as a secretion from the
animal itself, the substance differs in different genera, both in its characters
and modes of formation : moreover, in some species, particles of foreign
matters are superadded, to give it strength and solidity.

The cases of Floscularia (woodcut. Part II.) and Stephamceros (XXXVII.
1) are colourless, and apparently structureless, and, though roomy, are visible
with difficulty on account of their tenuity and transparency. They are best
demonstrated by the addition of some colouring matter, such as indigo, to
the water in which they are examined. An exception to the usually ti-ans-
parent homogeneous case of Floscularia occurs, according to Dr. Dobie, in F.
campanulata. Dujardin, again, asserts that the m-ceolus of Floscularia may
vanish during the lifetime of the animal, and that in many French species
it is always absent ; he therefore denies its value in generic distinctions.
His statements, however, require confirmation, being opposed to the observa-
tions of other naturalists.

Again, the tubes of (Ecistes, ConocMlus, and Lacinularia are hyaline, with
a more gelatinous consistence, and, in the two last genera, adhere together.
In ConocMlus the individuals are aggregated around a central globule of
gelatine, from which they project Kke so many rays ; whilst in (Ecistes each
urceolus is free, but has its surface encrusted ■with foreign pai"ticles. Tiihi-
colaria (XXXII. 379) has a thick gelatinous case, of a mUky hue, which,
from its effervescing on the addition of an acid, is attributed to a deposit of
carbonate of lime within it. In young animals the case is quite ti"ansparent.
This is also true of the urceolus of Lhnnias (XXXVI. 2), which, as it grows
older, changes to a brown and brownish-black colour; and, as it is viscid,
various extraneous bodies affix themselves to it. In one newly-discovered
species, the usually smooth suiiaco is departed fi'om, and the case becomes
annulated, and is also semitransparent. Dr. Bailey found in North America
a species of Melicerta mth a brown annulated urceolus. But the most re-
markable tubular sheath is that of Melicerta ringens (XXXII. 386 ; XXXVI.
1), which is composed of equal-sized lenticular pellets, of a bro-wnish-red
colour, and of a substance secreted by the animal itself and deposited in a
regular oblique or spiral series. This wonderful phenomenon yyiH be consi-
dered hereafter, in the section on Secretion. The cohesion of particles of
foreign substances to the enclosing tubes is scon also in some Annelida, and
in the aquatic larvaa of certain Insects.

OP THE KOTATORIA.

397

The m-ceohis serves as a place of shelter and defence for the adult animal,
and also for the ova it deposits. The latter often remain within the case
until they are hatched. The necessity for shelter is entailed by the fixed
condition of these Rotatoria, because, unlike the free animals, they cannot
escape their pm-suers by flight. By means, therefore, of their highly con-
tractile pedicles they can entii-ely withdiw themselves within theii- tubular
dwelling, until the threatening danger is oveiTJast. Ehrenberg, however,
states that the animal may detach itself fi-om its case and swim away free :
if this be true, we must suppose it will again affix itself and proceed to con-
struct another urceolus. The possibility of this acquisition of freedom is
favoured by the analogous detachment of Vorticellce, and the formation by
them of a new pedicle on reattaching themselves. Empty urceoli are indeed
not uncommon ; but, unless the process be witnessed, it is impossible to say
whether the inhabitant has quitted its abode at wiU, or disappeared by de-
composition after death or by becoming a prey to other animals. Mr. Gosse
noticed that a Melicerta, which had its case slit up for some distance, pro-
truded itself through the opening ; and during several days' observation,
though it made pellets, they were never deposited in order to repair the
breach, but were allowed to float away : this observation does not support
Ehrenberg's above-cited opinion. Each member of a colony of adherent
Rotatoria is generated fi-ee, and swims at large until it chooses to join its
fellows in becoming fixed. The encased Rotatoria attach themselves to any
convenient siibstance in the water, especially the stems and leaves of water-
plants. The single individuals are many of them just visible to the naked
eye ; and where they imite in compound masses, they can be detached in the
form of jelly-like globules, having a milky hue, often ^th of an inch and
upwards in diameter. Tubes of Melicerta and Tubicolaria occur from ^th to
■^th of an inch in length.

An external envelope is found in a few fi'ee Rotatoria in the fonn of a soft
gelatinous coating, — for example, in Notommata Copeus and N. centrura
(XXXYIII. 26). In the latter species, moreover, this coat exhibits a regular
an-angement of fine molecules within it, and a consequent apparent striation.
Ehrenberg describes the confervoid fibres of Hygrocrocis as sometimes para-
sitic on this gelatinous involucre; but this account Leydig doubts. It is
certainly, however, not improbable, since urceoli of every variety furnish a
favoui-able nidus to parasites, both vegetable and animal; and this writer
himself speaks of Vibrios adherent to the hyaline case of Stephanoceros, on
the surface of which, as he imagines, they sometimes give rise to an ap-
parent striation.

Appendages of Rotatoria. — Each great division of the body is fiu-nished
mth certain prominent parts or appendages, adapted to supply various re-
quirements of the economy. The appendages of the head and neck exceed
all others, both in number and importance, — the rotaiy organ, the peculiai-
characteristic of the class, being one of them.

This latter organ is essentially a ciliated wreath or circlet, mostly sup-
ported on an expanded margin or disk, and subject to considerable variations
Avhich are employed in the classification of these animals ; the rotary is also
called the rotatory organ or disk, the trochal disk, at times, less definitely
the ciliated disk or wreath, or the wheel organ.

Ehrenberg employed the rotary organ in its diff-erent modifications as the
basis of his classification of the Rotatoria, making two chief types in one of
which the cihated ring was single and complete, in the other subdinded into
several independent portions or secondary wheels. A subordinate tyne nre
sentod two equal symmetrical circlets of cilin,. forming a pair of wheels To

398

GENERAL HI8T0EY OF THE INFUSOfilA,

the first of these groups he gave the name of SorotrocJia, to the second Poly-
trocha, and to the last Zygotrocha. The further subdivisions which he formed,
and the names he applied to the varieties of the rotary organ, will be ex-
plained in the section on Classification. The belief in actually compound
trochal disks has been shared by nearly all observers, and both Perty and
Siebold adopt it along with Ehrenberg's classification. On the other hand,
it is denied by Leydig, who affirms that the disk is never divided into
such secondary wreaths or lobes, but always constitutes one continuous
margin, variously extended and folded, and, it may be, furnished with inde-
pendent accessory ciliated disks. This able writer remarks — " It is only to
the exceptional genera Stephanoceros and Floscularia, that Ehrenberg's term
Polytrocha can be rightly applied. In truth, an observation recorded by the
great micrographer himself negatives his hypothesis of polytrochous division,
that, viz., where he applied strychnia to the rotary organ of Hydatina, which
became thereby reduced to a simple whorl of cilia."

The various degrees of complication assumed by the trochal disk are thus
detailed by Leydig : — " It forms a simple ciliated margin around the mouth
of Notommata tardigrada ; in Stephanops (XL. 8, 10) it is wider, more pro-
minent, and triangular ; in Euchlanidota, Polyarthra (XXXVIII. 30), Di-
glena, Distemma, Hydatina (XL. 1), Pleurotrocha, and others, it occupies the
entire periphery of the head, and is not at aU, or but very slightly, elevated
as a distinct disk above it ; in Notommata Gopeus, N. aurita (XXXVI. 4),
and in Synchceta, it is enlarged and elevated as a distinct disk on each side of
the head, forming the " ears " so called by Ehrenberg ; in other instances it
is enlarged, and projects on the ventral surface of the animal Kke a cUiated
trunk or proboscis. A higher development is seen in Brachionus (XXXIX.
15-18) and Philodina, where the cOiated border is involuted and extended
upwards laterally (XXXVIII. 2) ; and lastly, in Megalotrocha, Lacinularia,
Melicerta (XXXVI. 1 ; XXXVII. 17), and Limnias (XXXVI. 2), the high-
est complexity is reached, and the trochal disk appears to be an appendage
surmounting the head, expanded in the form of a sinuous or lobed cUiated
margin." In the variety last mentioned, Mr. Gosse speaks of the expanded
lobes under the name of " petals."

The row of cilia fringing the rotary organ is often single, but in several
species is double, and even treble. Mr. Huxley has noticed its double con-
dition in Lacinidaria socialis. To quote his description — " The edge of the
disk has a considerable thickness, and presents two always distinct margins,
an upper and a lower, of which the former is the thicker, and extends beyond
the latter. The large cilia are entii'ely confined to the upper margia, and
form a continuous horse-shoe-shaped band, which, upon the oral side, passes
entirely above the mouth. The lower margin is smaller and less defined than
the upper ; its cUia are fine and small, not more than one-fourth the size of
those of the upper margin. On the oral side this lower band of cilia forms
a V-shaped loop, which constitutes the lower and lateral margins of the oral
aperture. About the middle of this margin, on each side, there is a small
prominence, from which a lateral ciliated arch runs upwards into the buccal
cavity, and, below, becomes lost in the cUia of the pharynx. The aperture
of the mouth, therefore, lies between the upper and lower ciliated bands
(XXXVIII. 21)."

Prof. WUhamson has signalized a Hke arrangement in Melicerta (XXXVII.
17), and Leydig in Brachionus, Pterodina (XXXVIII. 29), and Megahtroch<r.a .
The latter writes — " On the free surface of the head of Brachionus (XXXVIII.
14, 15), two lateral and and a median lobe elevate themselves, which Huxley
compares to the two ciliated bordera of Lacinidaria, — an interpretation that

OP THE HOTATORIA.

399

has very many arguments in its favoui-, and in support of which I may
adduce the structui-e of the rotary organ of Pterodina. This species, belong-
ing to the family of Brachioncea, has its free projecting lobes furnished -with
a double row of cilia, analogous to what occurs in Megalotrocha. _ That the
wheel organ of Philodincea also is referrible to the same type, is evident
from the account Huxley gives of it."

Cohn {Zeitschr. 1855, vii. p. 437) describes two complete rows of cilia,
besides five or six special cihary bundles, on the head of Hydatina senta
(XL. 1). On the outer margin is an unbroken row of long and fine cilia,
extending thence into the oral fissure, and still further, into the oesophagus.
Within this circle is an interrupted one formed by 6 or 7 (Ehrenberg counted
11) bundles, having few or many broader and longer cilia, nearly resembling
the setae on Stylonychia, and supported on as many cushion-like eminences.
Lastly, the third series is unbroken like the first, and composed of finer cilia,
disposed in a quincuncial manner in two lines. All the parts of this ciliary
apparatus work harmoniously together in effecting the movements of the
animal or in securing the capture of food.

The figure of the trochal disk (XSXVIII. 14, 15, 20, 21) varies exceed-
ingly, as the quotation from Leydig indicates, and is especially influenced by
the addition of supplementary ciliated eminences. In Megalotrocha (XXXII.
374-378) the disk is horse-shoe-shaped ; in Melicerta it is petaloid, or, as
Prof. Williamson called it, flabelliform ; in Eotifer it is seen under two forms,
according to its degree of expansion, either as a single conical eminence, or,
when completely unfolded, as two cylinder-like processes, one on each side
of the head, apparently whorling like two wheels. In the family Brachio-
ncBa (Ehr.) accessory disks or processes give rise to much complication
(XXXIX. 15-22). Ehrenberg described this family as having two ciliated
organs — a central one of three parts, and a lateral one of two, — the latter
being the true wheel organ, and the former, frontal processes which are stiffly
extended whilst the rotaiy organ is in action. Aji appendage such as that
last named, in Noteus, he designates a three-lobed ciliated brow.

Exceptional or aberrant forms of the ciliated disk are seen in Floscularia.,
in Stephanoceros, and in Lindia (XXXIX. 1, 3). In the first, the head
(XXXVII. 1) is surmounted by five ciliated flattened lobes, ending in knob-
like processes which bear very long, divergent, non-vibratile haii's or eiHa
of imiform thiclmess {see woodcut. Part II.). " These exceptional ciKa," says
Dr. Dobie, " are slowly moved and spread out by the contractile substance
of the lobes of the rotary organ." In Stephanoceros, the departui-e from the
normal structure is still greater (XXXVII. 1), — so much so, that the
ciliated appendages have no claim to the title of a rotary organ. ' Five lono-
arms extend from the head, like five tentacles, covered by cilia in rings (ver-
ticeUate cilia). These arms not only act lilie a common trochal disk by pro-
ducing a vortex directing aU particles within its range to the mouth, but also
as organs of prehension, closing themselves on any larger object which may
come within their grasp. This ciliated armatui-e around the head bears a
close resemblance to that of the ciUo-brachiate Polypes or Bryozoa, to which
class of animals, indeed, several distinguished naturalists have referred the
genus Stephanoceros, not merely on account of this one affinity named but
also from several other coincident characters. A third peculiar form of rotarv
organ has been recently pointed out by Cohn in Lindia {Zeitschr. 1858 p
284). It takes the form of a club-shaped process on either side of the head
(XXXIX. 1, 3), having its extremity somewhat expanded and spherical
CUia exist only on the round summits of these processes ; there is no whorl
around the margin of the head, none elsewhere on the body • and this ex

400

GENERAL HISTORY OF THE INFUSORIA.

ample may be adduced as that of the least complicated rotary organ among
Botifera.

It is in these aberrant forms alone that the cUiated apparatus can be strictly
called " polytrochous in them, also, the wheel-like motion is completely
absent. This pecuKar motion, on the contrary, is most evident where the
wreath is a simple circle, as in ConocMlus and Actimirus, or where, as in
Rotifer and Philoclina, it is peculiarly involuted, although continuous. Where,
on the contrary, it is interrupted by a notch at any point, or Ls siauated, or
complicated by supplementary processes, as in Hydatinu (XL. 1), Diglena,
many Notommata (XXXVII. 29, 32), Synchceta, &c., the illusion of com-
plete revolutions vanishes.

Formerly, the belief existed that an actual whii-Hng of the ciliated cephalic
appendages took place, and that the little animals moved along, by the aid of
these wheels, after the manner of a steamer with its paddle-wheels. Such
an opinion is no longer entertained ; and various explanations of the apparent
rotary motion are now offered in its stead. Dutrochet attributed it to the
undulation of a delicate membrane fringing the head of the Rotatoria.
Faraday explains it by supposing the distinct cilia to become visible by
slowly returning to an erect state, after having previously been suddenly
bent. Ehrenberg assimied the existence of four muscles at the base of
each cilium, — each muscle acting in its own du-ection, and so producing a
revolution around the fixed point of attachment or base of the cilium. In
this way, each cilium would be alternately nearer to or more remote from
the eye, and more or less visible.

Another explanation has been offered by Dujardin. He says — " The vibra-
tile cilia being arranged parallel and at equal distances, will equally refract or
intercept the light, and none will be more visible than the rest ; but if, by a
movement propagated along the row of ciHa, some, momentaiily inclined, are
brought into juxtaposition with adjoining cilia, the light will be more inter-
cepted, and a band more or less dark will be the result. It can be imagined,
therefore, that if the cilia come to be inclined one after another, a series of
juxtapositions, or of apparent intersections will be produced in the direction
of the general movement. Further, if each of the intersections preserve the
same form, as if produced by a number of equal lines, and are equally in-
clined to each other, an appearance of a solid body of a definite fonn, like the
teeth of a saw or the spokes of a wheel, moving uniformly, presents itself to
the eye."

The action of the trochal disk is under the control of the animal. The
ciliary movement can be arrested at will or exercised with vaiying rapidity ;
or the whole organ may be retracted, partially or entu-ely, within the body.
When completely withdrawn, the ciliary wreath can frequently be detected
at the fore part of the animal, oftentimes deep ^vithin the tnink, and gene-
rally in the form of a striated cyUnder at the bottom of a funnel-like canal.
In complete retraction the anterior extremity of the body is involuted, or
doubled inwards, and supports, as it were, the cUiated wreath within, wlulst
the contractility of the integument at the mai-gin closes the entrance pretty
accurately, giving a more or less conical outline to the fore part of the ani-
mal (XXXVII. 19 ; XXXIX. 17). In complete retraction of the trochal
disk, the antenna-like processes which may be seated on it are also with-
drawn ; but at other times, when the inversion is incomplete, these processes
continue to project from the head, and in the process of evolution are ahvays
the first to appear, as if intended to test the safety of unfolding the delicate
ciliary wreath.

The inversion of the ciliarj' apparatus and appendages is effected by strong

OF tut; rotatoria.

401

muscles arising within the abdomen, which draw downwards, and therefore
inwards, the disk to which they are attached. At the commencement of
theii- traction, they draw together the sides of the ciliary whorl, then pull
inwards the cilia, which are previously collected in a cyUnchical manner, and
at last cause the inversion of the integument immediately beneath the disk,
when the now anterior extremity of the body contracts itself upon the in-
cluded parts. This process of involution may be arrested by the animal at
any stage ; thus, sometimes it is stayed when the cilia are grouped together
in a cylinder-like heap, and still project from the head like a pencil ; or,
as above mentioned, the cHia may be withdrawn, and some process or an-
tenna be left protruding. The collection of the cilia into a bnish-like gi-oup
during the process of retraction is well exemplified in the long cilia of Flos-
culana ; and in Rotifer and Phtlodina we have a special example of the pro-
trusion of a ciliated process during the involution of the major part of the
trochal disk (XXXVIII. 1). In the genera last cited, this median process
serves as the anterior organ of progression when the animals advance in a
leech-Ulce manner, and disappears when the pair of trochal organs are
evolved and the crawling movement is changed to swimming.

The retraction of the trochal disk we may suppose to be controlled by the
will of the animal to arrest its motion or to avoid danger. Another motive
is conceivable, especially in the case of the attached species : for the cilia,
when in active operation, attract every sort of particle within their vortex —
as well those appropriate to nutrition as others noxious or which have
been lately discharged and still float about the animal ; hence it may be ne-
cessaiy to arrest their action, withdraw the disk, and close all access to the
interior, until these unfit substances are floated away and have been replaced
by others.

The ciliated mechanism of the head is, as just hinted, the active agent in
procuring food, by di-agging within its vortex the nutritive particles in reach,
and transferring them to the mouth, which is so situated that the current
produced sets directly into it. Where the ciliaiy wreath is double, as in
Melicerta, "the food" (to use Prof. Williamson's description) " that reaches
the mouth is whirled around the wheel-organs along the groove that sepa-
rates the two circlets of cilia; and since these cu'clets diverge near the
' chin ' (or fifth ciliary lobe), the mouth being located between them, the
food is necessarily conveyed directly to the latter organ. The two sets of
marginal cilia, by bending towards each other whilst in motion, almost con-
vert this groove into a sinus, especially in the two large segments." But
besides locomotion and nutrition, the rotary apparatus must be admitted to
subserve the function of respiration, both by its own delicate stracture, and
by its action in constantly renewing the water around the animal ; also, by
forcing fluid within the aUmentary canal, it may serve to aerate and renew
by endosmosis, the fluid in the general cavity surroimding the viscera.

In the fixed species of Eotatoria the rotary organ can have no locomotive
use, merely subserving the functions of nutrition and respiration. In addi-
tion to the rotary organ, the head is often beset with various appendages
in the shape of styliform and tubular processes, lobes, disks, uncini, and
spines. These are situated either witliin the circle of the ciliary wreath on
its margin, or immediately external to it. Examples of tapering, styliform,
■ and bristle-like processes are found in Notommata Myrmeleo, Monocerca bi-
cornis, in SynclurM, Monostyla, Brachionus, and others.' On the head of Com-
chilus are four stout wart-Uke elevations. In Polyarthra platyptera two long
i bristles project from near the mouth, each bent on itself midway at a right
I angle (geniculate). Dujardin describes, in his genus Colurella, an uncinate

2d

402

GENERAL HISTOKY OF THE INFU80E1A.

retractile appendage surmounting the troehal disk. In Brachionus urceolaris
(XXXIX. 15, 16), straight non-vibratilo cilia occur between the ciliated lobes
of the rotaiy organ ; and in Polyarlhra there are fleshy tentacular appendages,
wliich kSiebold suggests are antennae or feelers. The 2-4 styliform processes
of Synchceta, Ehrenberg supposed to possess prehensile powers. In Cono-
cliihis, fom- processes, terminated by bristles, project from the ciliary disk ;
in Melicerta are two curved hooks. To some of these appendages, and to
others about the head, various fanciful names have been given, boiTowed
mostly from remote resemblance in appearance, situation, or function to parts
existing in the higher animals. For instance, on each side of the head ol
Notonimata aurita, N, Oopeus, and Diglena aurita, a lobe of the troehal disk is
more elevated or elongated than the rest, and has received the appellation of
" ear " or " auricular ; " the 2-4 supplementary processes of the head of
Polyarthra (XXXVIII. 30 a, h) have been called " horns," — a name applied
to a similar projection in other Rotatoria.

In Steplianops a prominent scale-like process of the head is kno'wn as the
" hood " (XL. 8-10). Mr. Gosse speaks of a projecting spoon-shaped lobe
in Melicerta, covered with cilia, as the chin, which Williamson recognizes as
a *• fifth lobe " of the wheel organ (XXXVII. 17 c). The latter writer, again,
adopts from SchiifFer the appellation of " lips " for two hook-Kke appendages
of the head of Melicerta, and further describes, on each side the oral apertm-e,
two projecting " flattened lobes, with ciliated margins continuous with those
of the ' chin,' which obviously assist in directing the food into the oesophagus."
Lastly, Ehrenberg frequently employs the term " frontal region " or forehead,
to signify the anterior surface of the head.

Certain tubiUar-looking processes, frequently furnished Avith a pencil of
fine non-vibratile cUia or bristles at the extremity, have gained particular
consideration owing to the functions assigned them by Ehrenberg and others.
They protrude from the head near the troehal disk, and more commonly from
the neck, as is seen in Rotifer, PJiiloclina (XXXVIII. 20), Brachionus
(XXXVIII. 15 ; XL. 11), Actinurus, in Euchlanis Lynceus, in Melicerta
(XXXVII. 17), in Salpina mucronata, in Notommata clavulxita, N. Myrmelco,
N. Sieholclii, and other species. In aU the above the appendage is single,
but in Tubicolaria and Melicerta (XXXVII. lid) it is double. In Calli-
dina Ehrenberg mentions a thicldy-eiliatcd proboscis, appai'ently retractUe,and
attached to the troehal disk ; occasionally, instead of tenninating by a bunch of
seta3, these processes have a horn-like prolongation, as in Notommata centriira
and N. Copeits. The short conical elevations of Sijncliaita and Polyarthra
belong to the same category with the tubular variety. A long flabelliform
process occiu's in connexion with one of the ciliary lobes of Floscularia, which
is often called a proboscis, and supposed to be tubular. Ehrenberg has as-
signed two different appellations to these tube-like appendages. At one time
he calls such a process a spior (" calcar "), and imagines that it subserves the
generative process as an intromittent organ ; at another he represents it as
a respiratory tube {siphon), thi'ough which water may enter to act on the
vibratile tags (giUs) seen within the abdomen. The former view has found
no supporters, and is entirely sot aside by our present knowledge of the
reproductive act of the Rotatoria ; the latter lias been admitted by several,
among others, by Siebold, although recent researches now render it untena-
ble, and demonstrate the analogy of these appendages wth the feelers (an-
tenna; and palpi) of Entomostraca and other Cnistaceans. Dujardin seems
to have been the first to suggest the analogy mentioned. Referring to these
processes and to others less considerable, terminated by a bundle of stiff ciUa,
he observes that they recall, to some extent, the palpi and antenna? of

OF THE ROTATORIA.

403

Entomostraca and Ci/pris, and that no trace of the entrance or exit of water
is perceptible, even when particles of colouring matter are diffused through
the liquid, calculated to indicate the slightest current."

Since this was written, Perty, Gosse, Wilhamson, Huxley, and Leydig in
particiilar, have minutely studied the point in dispute, and coincide with the
French natm-alist as to the non-perforated character of the organ, and its ho-
mology with antennte. Mr. Gosse writes — " The tubes or spurs on each side
of the head (of Melieerta) below the chin (XXXYII. 17 d d) are evidently
consimilar with the antennae of Rotifer, &e. There is a slender piston in
each, capable of being retracted, and bearing at its extremity a tuft of very
fine, divergent, motionless hairs." Mr. Williamson's account is more detailed ;
he calls them " tentacles," and states that, when fully protruded, they are
seen " to be terminated by a brash of fine divergent setae implanted on the
convex side of a small deltoid body (the jyiston, Gosse) (XXXVII. 12) ; from
the flat side of this latter appendage there proceeds, along the interior of the
tube, towards the body of the animal, a delicate muscular band (XXXVII.
13, 14), which, by its contractions, draws the deltoid body backwards, thus
inverting the extremity of the tube, and forming a double sheath protecting
the setae (XXXVII. 14). This inversion of the tube was, we believe, first
noticed by Dutrochet. The whole apparatus is, as suggested by Schafier, very
similar to that seen in the tentacles of the snail, and appears to constitute a
tactile rather than a respiratoiy organ. This is rendered more probable by
the fact that, when the animal fii'st emerges from its tessellated case, the ex-
tremities of these two tentacles are the first pai-ts that make theii- appear-
ance (XXXVII. 17 dd), — the two curved hooks being the next (XXXVII.
17 h). The setae are usually half di-awn into the inverted tentacle ; but they
project sufficiently forward to constitute delicate organs of touch, supposing
the deltoid body, into which they are inserted, to be endowed with sensi-
bility. The animal cautiously protrades these tentacles before it ventm-es
to unfold its rotary organs, but it does not direct them in an exploratory
manner fi-om side to side, as an insect does its antennae."

But there are many strictly homologous processes with a terminal tuft of
setae which are tubular and not retractile, or otherwise neither tubular nor re-
tractile, but horn-Kke in figure, or merely conical. Examples occur in Notom-
mata Myrmeleo (XXXVIII. 26 h) and N. Sieholdii (XXXVIII. 32 g), and
in the shorter conical elevations on the disk of Synclioita and Polyarthra, and
in the horns of the last-named genus. '

A fiu-ther departure from the highly-developed antennte of some Rotatoria
is exemplified in the fossae, pits, or apparent apertures (XXXVIII. 28-30)
oftentimes with elevated edges, containing a tuft of bristles, wliich are met
with usually on the necks of the animals. These fossaj, as well as the
retractile and non-retractile antennae of all forms, Leydig believes to be in
immediate and special relation with nei-ves which extend to the base of the
brush of rigid cilia. The number of such fossae varies in different species.
In accordance with his hypothesis of respiration, Ehrenberg called them
"ciliated respiratoiy openings." In Enteroplea (XL. 2), Hydatina (XL. 1)
Diglena, Oiocjlena, in Euchlanis triquetra, and in several Notommata'' an
apparent aperture exists on the neck. More than two are seen in Pohi-
arthra, Notommata Myrmeleo, and in N. Sieholdii (XXXVIII. 20), arrann^ed
along the back ; and in AKplanchm. Briyhtivellii (Gosse), Dalrymple met
witli two on the back, which he supposed to be and described as lateral
apertures, but which, Leydig affirms, have the unbroken cuticle Uning them
(XXXVI. 9).

Interesting variations are found in Nofeus, in which Ehrenberg describes

2 D 2

404

GENERAL HISTORY OF THE INFUSORIA.

a short, stout, respiratory tube, or, as it actually is, a depression surmounted
by a veiy elevated margin. In Notommata cenirura (XXXVIII. 26 b), and
in N. Gopexis, a long seta projects from a smaU elevation of the cuticle, on
each side of the back, having its extremity divided like a brush. The doubtful
cUiated depression conceived by Prof. Huxley to be the nervous centre, belongs,
in Leydig's opinion, to the categoi-y of tactile fossse.

Appendages of the Trunk. — The account already given of the cuticle and
lorica and their processes, leaves no special appendages of the trunk to be
described. Thus vfe have spoken of the spines from the anterior and posterior
margins of the lorica, of those which, in a few examples, are produced from
its surface, and of the setae or cfrrhi which extend fr-om it in Anuroea biremis,
in Notommata Copeus, and, on a larger scale, in Triarthra and Polyarthra
(XXXVIII. 30 c).

The pseudopodium, or false foot, may either be accounted a production or
appendage of the trank, or a distract segment of the body. Its dimensions
and figure vary much in different species ; and in several it is entirely ab-
sent. It attains the highest development in PMlodincea (XXXVIII. 1, 2),
where it consists of several progressively diminishing segments united by
sliding joints, like the tubes of a telescope, and is analogous to the tails of
many Entomostraca, e. g. the Cyclopidce. In this family, Philodiruea, the body
tapers into the pseudopodium by a gradual lessening of the articulated seg-
ments ; so that the termination of the trunk proper and the commencement
of the process have no external indication, except what is supplied by the anal
orifice of the alimentary canal, which usually opens at the base of the tail. In
other families the termination of the trunk is more abrupt, and the distinct-
ness of the pseudopodium as a subordinate segment or member strongly pro-
nounced (XXXVIII. 25, 26). The high development of the organ gradually
diminishes, until the telescopic-jointed foot-process is degraded to the condi-
tion of one or two stiff styles, supported on an enlarged base (XXXVIII. 22),
the intermediate stages being represented in various species (XXXV ill. 23,
24, 25, 81). In Brachiomts, Oolurus, Stephanops, and Dinochat'is the foot-
process, although of three or more telescopic joints, is of much smaller
diameter, and depends like an appendage from the tinnk, and is a transition
between this form and the usually tapering figui-e of the Phihdina;a, as seen
in Rotifer macrurus, the trunk of which is abruptly attenuated into a long
foot. A further reduction of the many-jointed telescopic pseudopodium to
one or two joints, terminated by a single, double, or triple styhform or
pincer process, is exemplified in many Notommatce (XXXVIII. 26), in
Cycloglena, Lepadella, Metopidia, Salpina, Diglcna, Eospliora, Hydathia
(XL. 1), Ratidus, Sec, where the ai'ticulate structure is reduced to the
condition of an appendage of the trunk, its terminations assuming the chief
importance. Indeed, in some cases, one or two styliform processes seem to
be produced immediately from the trunk without the intervention of an
articulated segment at the base (XXXIX. 1-3). At the same time a styli-
form foot-process is, as a rule, a veiy short pseudopodium supporting one or
more long styles. In the case of the less-dcveloped or perfect tail-processes,
the section of the body is frequently attached obliquely to the trunk. .

In a very few examples the posterior dorsal surface of the body is pro-
longed as a ti-ue tail, having the pseudopodium fixed in front of it, the
anal orifice being between them. This is witnessed in Notommata Copcus
(XXXVIII. 26).

The pseudopodium has in some genera styliform processes attached to
it throughout its length, as seen in the highly- developed telescopic pro-
longation of the Philodincea (XXXVIII. 1), in CalUdina, Rotifer, Actinunis,

OF THE aOTATORIA.

405

and PUhdina, and also on the shorter foot-process of Dinocharis. These
styles are moveable and flexible, and occui- in a single paii- or in two or thi-ee
paii-s ; Ehrenberg gave to such, when short and not rigid, the name of * toes,'
and distinguished the prolongation on each side of the posterior border of the
sliding-joints, seen in Rotifer, Actinurns, and Callidina, as ' hom-lOfe pro-
cesses.' In Scandium (XXXVIII. 22) and Dinocharis, the foot, though
jointed, seems not to be retractile.

The pseudopodiimi differs much in its length and mode of termination.
Where the articulated segments ai-e few and smaU, the foot, if terminated by-
styles, oftentimes acquires a great length. In some species the terminal
styles are three in number — e. g. Actinurus, PMlodina Neptunitis, Dinocharis,
and in some Stephanopes ; and more frequently the central style is shortest.
Two terminal styles are more common. IRustrations are found in Furcidana,
Scaridium, Distemma, &c. A foot ending in a pair of styles is said by Ehren-
berg to be ' forked' (furcate).

In niunerous species the styles have much rigidity, and are greatly elon-
gated ; in such instances they are known as styliform setae, or simply ' setce.'
Two such terminate the trunk in Notommata longiseta, N. cequalis, and in
N. Felis — in the last-named they are also curved backwards, — whilst but one
is produced from the body in Monocerca (XXXVIII. 399), Mastigocerca
(XXXIV. 438-440), and in Batulus ; in the last, moreover, the base of the
setae is surrounded by stiff hairs.

Another very common ternunation of the foot is by a pair of short thick
flaps, moveable on their base, and named ' piacers,' or ' pincer-like processes.'
Such are seen in Brachionus, Hydatina (XL. 1 ), Enteroplea (XL. 2), Diglena,
Eosphora, Noteus (XXXVIII. 25), and in several Notommatce (XXXVIII. 5,
25, 26).

All the preceding varieties of the pseudopodium are modifications of the
articulated telescopic type, and associated with a tolerably firm cuticle. But
there is yet another type, in which no articulated segments occur, and which,
from the softness of its tissues, is thrown into wrinkles or folds during con-
traction. Illustrations of this are found in all the ui-ceolate genera of the
Rotatoria, viz. in Conochilus, Lacinularia, Melicerta, Tubicolaria, Stephanoceros
(XXXVIII. 1, 17, 19), &c., and, besides these, in the free Megalotrochcea
(XXXII. 374-378) and in Pterodina (XXXV. 502-504). In the attached
genera especially, this form of pseudopodium rather merits the name of
'joedicle ' or footstalk. In Pterodina the cylindrical foot-process is trumpet-
shaped, and discoid at its free extremity, which is supposed to act Kke a
sucker. A suctorial end to the pedicle is likewise presumed to exist in some
or aU of the fixed genera.

Cilia have been discovered on the extremity of the pseudopodium of Ptero-
dina and Tubicolaria, and on that of Megalotrocha, Lacinidaria (XXXVII.
10), and Brachionus in the young or immature state.

Lastly, a pseudopodium is absent in Anurcea, Asplanchna (XXXVI 9 •
XXXVII. 29-32), Polyarthra, Triarthra (XXXVIII. 30), and Ascomorpha.

The observations of these and other particulars concerning the pseudopo-
dium, its presence or absence, its structure, its length relatively to the body,
and to its own processes, supplies valuable characters in the systematic chstri-
bution of tlie Rotatoria ; and the details so derived furnish the fimdamental
divisions of the classification proposed by Leydig (see Classification).

The foot-like process is essentially a rausculai- organ ; it contains no viscera
but m highly-developed forms some smaU bodies supposed to be glands and
m some examples certain vesicular spaces supposed by some to be "gangUa bv
others, vacuolar thickenings of the connective tissue (XXXVII. 17 n) The

406

GENEEAL niSTOllY OF THE INFUSOHIA.

auiis always opens at the base of this segment, and on its posterior aspect ;
henco it is that, though often called a tail, it is really not homologous -with
that appendage of liigher animals ; and consequently most writers prefer to
namd it pseudopodium, foot-process, or foot. It certainly has no evident re-
semblance to a foot, although anatomically it is a limb or member, and is
functionally an organ of locomotion and of support. It is much less con-
cerned with motion than the rotaiy organ, and, from its occasional absence,
is evidently a non-essential organ. A principal pm-pose which it seems to
answer is that of a redder, steering the animal in its course like the tail of a
fish. However, occasionally, when developed in a styhform manner, as in
Scaridium (XXXIII. 423), it is a powerful and peculiar locomotive append-
age, enabling the animal to leap. The pincer-hke tennination seems to
enable the animals to hold fast to or grasp objects, or to push themselves
forward. The short flexible toes developed on the pseudopodium, and the
supposed discoid extremities, sei-ve to attach the animal whilst the head may
be moved fi'eely about, or whilst it advances in a leech-like manner by the
alternate forward movement of the head and foot.

Op the Muscular System jlnd Movements of the Eotatouia. Mt;scul.\e
System. — In this class a muscular system, subsei-vient to the functions of
locomotion, nutrition, &c., is weU developed ; and, the integument being
transparent, its structure and arrangement are distinctly visible. The
muscles (XXXAT. 5 ; XXXVIII. 28 a) resemble fine lines, cords, or bands
passing from one part to the other, and may generally be distinguished by
being thickened diuing contraction, and attenuated by extension. AU those
attached to the walls of the body arise from the inner layer of the integu-
ment, which is thickened at the spot. They may be considered, with refer-
ence to their functions, to be of two kinds — ^the one concerned in the general
movements of the body, the other in acting upon special organs or viscera.
The first constitute two sets — the one annular, encompassing the body, the
other longitudinal. The annular or transverse muscles (XXXIII. 5, G t ;
XXXVIII. 26 v) are separated from each other by considerable intervals ;
and to them is due, in many species, the apparent segmentation of the tiimk.
They are, so to speak, imbedded in the inner epidermic layer. Ehrenberg
mistook them for vessels.

The longitudinal muscles are more numerous and definite (XXXVI. 51,9 I;
XXXVIII. 28 a ; XL. Im). Mr. Williamson believes that delicate fibres occur
in the thickness of the skin of the tnmk, designed to shorten the animals by
corrugating the sm-face. The long muscles extending from the posterior ex-
tremity of the body to the rotaiy organ and the maxillaiy bulb, and serving
to retract those parts, are the most highly developed. Dr. Dobie describes
muscular bands in Ploscularia, passing up between the lobes of the ciliated
head, and more delicate fibres along the centre of each lobe towards its ex-
tremity. The muscles of the tail (foot-process) arc also numerous, lai-ge,
and strong, and traceable to its terminal segments (XXXVI. 5 h ; XXXVIII.
26 n) on the one side, and on tlic other as far fonvard as the anterior part
of the body and the maxillary bulb. WiUiamson states that tlie fibres
reaching the extremity of the foot-process are inserted into a little concavo-
convex body found there. By its muscular appai-atus tlie tail can be cui-ved,
moved from side to side, and shortened, and in a few examples, e. g. Scai-iifnm,
doubled beneath the beUy. The counterforce, whereby the pseudopocliiim
recovers its straight figure and ])osition relative to the body, is the elasticity
of the integument. AVhere the sliding joints exist, this elasticity must
chiefly reside at the Unes of junction, since the segments themselves have
great rigidity, and do not admit of cornigation. However, the extension of this

OF TUE KOTATOllIA.

407

process mucli depends on the influx of fluid forced into it by a general trans-
verse contraction of the body which is seen to precede it. The extension of
the body, after having been shortened by the contraction of its longitudinal
muscles, is chiefly due to the elasticity of its integument, which has an in-
herent tendency to constrict itself or to lessen its diameter. Prof. Williamson
dissents from this explanation, believing the extension to be due to the cir-
cular muscular bands, as in the pseudopodia of the Echinus and starfish, or in
the trimk of an earthworm. The shortening of the body is provided for by
the sliding stractru'e of its segments, and by the wrinkling (XL. 1) of its sur-
face (XXXIX. 1-3), sometimes by both these modes together, at others by
one alone. Even where its length is diminished by the formation of mere
folds of the skin, those folds are constant in position and arrangement.
Longitudinal folds pretty regularly disposed occur in the softer-skinned
varieties— for instance, in various species of Notommata and Hydatina.

Muscles supplying special organs are seen in connection with the trochal
disk, the maxillary head and jaws, the alimentaiy canal, and the reproduc-
tive apparatus (XXXEX. 7). Excepting the muscles moving the rotary
organ, these wall be best described in the account of the organs with which
they are connected.

The trochal disk, and, indeed, the whole head supporting it, is constricted,
coriiigated, contracted, and moved from side to side by considerable muscles,
extending from it to the maxillEB, and to the sides and posterior boundaiy of
the abdominal cavity (XXXVLLI. 28 a) ; special muscular threads act upon
particular lobes, prominences, or processes which may extend fi-om the head
or its ciliated disk. In the trochal disk of Melicerta, Prof. Williamson de-
tected interlacing threads which he supposed to be muscular ; and Mr. Gosse
has remarked in the same animal " a seiies of five or six annular threads
set in the inner skin, which are probably muscular, and aid in the complex
movements of the head." Some of the interlacing tkreads, which Ehrenberg
described in several Eotatoria (as, for instance, in Lacilunaria), and which
at one time he regarded as vascular, at another as a nervous or muscular
network, probably were muscular, although most of them were merely fibres
of connective tissue.

The extrusion of the head and trochal disk, after retraction, is principally
effected, as in the case of the pseudopodium, by the elasticity of the integu-
ment, consentaneous with the relaxation of the muscular contraction this

elasticity serving to imroll the involuted head and trochal disk, and to expand
their parts, and, by its general operation on the body, to elongate the whole
figure, and thereby press the contained fluid forward and backward a"-ainst
the retracted organs, so as to push them out. Prof. Williamson would also
attribute the protrasion of the head to the action of the circular muscles
as he docs not think there is sufficient proof of such elasticity independently
of muscular fibres. The retracted head and appendages of the Bryoaoa are
thiTist outward in a similar manner.

The cilia of the trochal disk have generally been assumed to be seated on
a muscular mass, forming the cushion-like contractile thickenings on the
head of the Eotatoiia (XXXVI. 93). These stractm-es display, according to
Dujardin, no distinct muscular fibres ; but in the opinion of others, such^are
present. Ehrenberg, as before stated, went so far as to imagine, not merely
a network of muscular fibrils moving the entii-e apparatus, but also a scries
of foiu- muscles at the base of each ciliura moving it in eveiy dii-ection. Such
an an-ay of definite muscles to move an almost imperceptible organ' is not
only entirely hypothetical, but most improbable. Lcydig, on the other Innd
opposes the idea of the musciUnr nature of the troclial dislc, and regards

408

GENERAL HI8T0KY OF THE DTFUSOEIA.

it as consisting solely of the soft epidermic tissue, or, whicli is nearly
the same thing, of connective tissue. Much discussion has aiisen concern-
ing the structural composition (t. e., in a word, the histology) of the muscles
of Rotatoria. Dujardin and Ecker questioned the existence of actual mus-
ciilar fibres, but recognized a soft contractile substance, often di'awTi out
into threads. The former, however, inclined to the belief in the existence of
determinate muscles, although observation, when he wrote, had not made it
certain. Thus, at p. 611, when describing a new species of Floscularia, he
remarks that, " by gentle compression of the animal, five independent cords
were brought into view, contractile and tolerably regular in outline, which
perhaps ought to be called muscles ; they extended through the pedicle and
to the extremities of the lobes of the rotary organ."

Ehrenberg noted the presence of muscles in most Rotatoria, and in a few
specimens believed he had detected transverse striation, — a fact which would
establish an analogy between them and those of the highest animals. This
highly-developed organization was denied by Siebold, who described the
muscles to be of the non-striated variety so largely distributed among other
Invertebrata as well as Yertebrata. But the belief now prevails, that the
possession of transversely-striated muscles is one of the characteristics of the
Rotatoria, although non-striated fibrils may Ukewise occur.

Ley dig thus treats this subject : — " The element of muscle is the primitive
cylinder, which is of two sorts — fine and thick, — the former in clear homo-
geneous threads, which, when traceable, are perceived to be branches of
cells ; such occurs principaUy in muscular networks ; the latter — the thick
primitive cylinder — originates from cells coalesced in rows, and it, therefore,
presents iutemally, at considerable intervals, the still-remaining ceU-nuelei.
These cylinders exhibit a gradual advance iu their further histological phases.
They may remain homogeneous like the finest primitive cylinders, or resolve
themselves into a homogeneous sheath, and an axial substance in the form
of molecules. Lastly, the contents of the cylinder may break up into mus-
cular (sarcous) particles, and therein approximate to the so-called trans-
versely-striped muscles, to which at length it may attain a complete resem-
blance." Thus the cell- wall comes to form an investing sheath or sarcolemma
of each fibre, and the cell-contents the vital conti'actile substance, or the sai--
cous particles. Leydig adds — " Both varieties of muscle, simple and striated,
occur in the same species, so that the gradual transition of one into the other
is unmistakeable." The existence of striated muscle ha.s been noted by Ehren-
berg in Euclilanis triquetra ; by Oscar Schmidt in Pterodina Patina ; by Perty
in the foot of Scandium longicavdum, in Polyarthra (XXXVIII. 30 in
the marginal muscle of Diglena lacustris, and of BracMonus tripos ; by Leydig
in Notommata Sieboldii (XXXVII. 32 a) and Noteus ; by Dahymplc, in No-
tommata Anglica ; by "Williamson and Gosse in Melicerta : and, without doubt,
it may be discovered in most other genera (XXXIX. 7).

Perty has noticed in the foot of Floscularia rows of granules, and fijie
longitudinal striae, — an intermediate condition referred to hx the dcsciiption
of Leydig, given above. Bergmann and Leuckart mention in a note (p. 377)
in their work, that in some animals transversely-striated muscles ai-e visible.
Prof. Williamson's observations support some of Leydig's views. " ^\Tien one
of these muscular fasciculi," writes the English natm-alist, " is di-awn out
at full stretch, its sm-face is seen to be mai-ked, at very regular intervals, by
dark transverse bars (XXXVII. 18). Each fasciculus has a diameter of about
■g-^th of an inch ; and the transvcrac strife recur at distances of about
•jrnVfrth. These intervals arc rather larger than those seen in the fascicidi
of human voluntary muscle. . . . On rupturing the fasciculi transversely, we

OF THE EOTATOKIA.

409

perceive that each one is invested by a delicate sarcolemma. This is well
seen at the upper part of the tail, where, on the contraction of the muscle, the
non-elastic sarcolemma becomes corrugated, and only recovers its smooth
aspect when the muscle becomes relaxed. These rugje of the sarcolemma
must not be confoimded with the transverse strife of the muscular fibre." ^

Movements of Rotatoria. — These are very various ; at the same time
some varieties are so constant in several genera and species, as to furnish
characters of much utihty in the systematic distribution of the class. There
are two piincipal modes of locomotion, — one by simple motion onwards, or
swimming, with or without rotation of the body on its long axis (e. g. in
Brachiomis), the other, confined to the family PhilocUncea, by crawling after
the manner of leeches, each extremity of the body being alternately fixed.
The latter mode of locomotion is partaken with the first, and the one or the
other resorted to at the will of the animal.

The rotaiy organ is almost exclusively concerned in producing the uniform
swimming movement and in turning the animal on itself, whilst the muscular
tail acts as a rudder in directing the course. The trochal disk is worked
with various degrees of energy and completeness ; when in full action, the
velocity attained is very great.

Usually the Rotatoria swim on the abdomen ; but exceptions occur, as in
Eosphora Najas, which, like the PhyUopoda, swims on its back. Noteus and
a few others turn on their short axis, or, iu common parlance, head over
heels. Other exceptional modes of locomotion are met with in 8caridium, in
Triarihra, and Polyartlira (XXXYITI. 30, 32), which have, besides the or-
dinary swimming movement, the power of leaping or skipping, — in the first,
by means of the elongated styliform tail, which can be doubled imder the
body, and then suddenly relaxed like a spring ; in the two last, by the aid of
some rigid biistles, or eiri'hi, attached to the body, and acting like the long
legs of a flea. A skipping movement is likewise attributed by Ehrenberg to
Notommata longiseta, due to its double, long, caudal styles, and an act of
rowing, by means of a long lateral spine on each side, to Anurcea biremis.

The preceding remarks apply to the locomotive Rotatoria ; but the encased
species, although unable to change place, have, nevertheless, a considerable
power of movement within and about theii' urceoli. They can extrude the
greater part of their body, and bend themselves over the edge of their case,
or withdraw themselves entirely within it. They owe this latitude of motion
chiefly to their long pseudopodium or pedicle, which contracts by throwing
itself into very numerous and deep Avrinkles ; for in none of the attached
species is this organ articulated. In comparison with that of the pedicle,
the capacity of the tiimk of the animal to shorten or contract itseK is but
small, and its transverse folds few, distant, and collected, mostly towards the
posterior extremity. The movements, in fine, of the m-ceolated Rotatoria are
limited to those of extension, retraction, and flexion ; and the extent to which
they may be exercised is in dii-ect proportion to the length of the pedicle. Ne-
vertheless, when forcibly expelled from its case, which can easily be done
without injury to the soft animal, the mature MeUcerta svnms about with
considerable velocity by means of its ciliated rotary disk, — the peduncle being
partially drawn up towards the body.

Although incapable of movement as individuals, a cluster of sucli as live
in compound masses, OonocMlus for instance, may float about freely, remind-
ing us of the spheres of Volvox. The locomotive Rotifcra also enjoy, in a
considerable measure, the power of moving their own bodies,— thus frequently
altering the relative positions of the vai-ious parts, and modifying their general
form. Their rotary organ, as already seen, may be extruded or retracted

410

GENEEAL IIISTOIIY OF THE INFUSOlilA.

within the body ; tlie body itself may be extended at full length, or very
much contracted on itself. So much may the whole animal bo contracted,
that, except by the detection of the characteristic llotatorial organization, its
nature would certainly bo mistaken. An illustration of this is furnished in
the figm'es of Dujardin and Perty (XXVIil. 4).

The mode of termination of the pseudopodium permits many of the Rota-
toria to attach themselves at will to any object, some {Pterodiim, for in-
stance) assuming a fixed position for a long time together. When thus at
rest, the rotary organ may be retracted or extended ; in the latter case, al-
though suspending its fimction as an organ of locomotion, it is in full operation
as a respiratory organ, as well as serving to procure food. The body, more-
over, is often in active motion when fixed by the extremity of the foot-process
— oscillating fi'om side to side, bending itself, and even tui-ning as on a pivot.

The Digestive System. — The Rotatoria possess a distinct and undoubted
alimentary canal, evident as a tube, traversing the interior, from a mouth to
a posterior outlet or anus, composed of distinguishable parts with accessory
organs. One group of the family is deficient of the anal outlet ; and in male
animals the digestive apparatus is atrophied or wanting.

The digestive tube is mostly straight throughout its course (XXXIX. 1 ;
XL. 1) ; the exceptions to the rule occur with the encased genera, in which
the intestine is curved on itself, and the anus advanced forwai-ds to some spot
beneath the head (XXXVII. Hi).

The parts to be distinguished in the alimentary canal are — 1st, the mouth
or oral cavity ; 2nd, the pharynx or vestibule (XXXVII. 19 o) between the
1st and 3rd, the oesophageal head (XXXVII. 19 h) ; 4, the stomach, with
appendages (XXXVII. c, d) ; 5, the intestine with its outlet ; and 6, the
cloaca (XXXVII. e,f). Each and all of these parts present great diversity
in figure, size, and accessory organs ; but yet in neaaly all forms the peculiar
type of the digestive canal of Rotatoria is well marked.

The mouth is situated, as a rule, on the margin of the trochal disk, at
the centre of its ventral aspect. WTiere the cii-clet of cilia is double, as in
Lacinularia and Melicerta (XXXVIII. 21), the mouth, as we have already
seen, is placed between the two rows ; and in Floscularia and Steplianoceros
it occupies the centre of the area formed by the ciliated apparatus of the
head. The mouth is, moreover, subject to variations from the presence of
appendages about it. Thus, in Melicerta, Prof. Williamson describes two smaU,
projecting, " flattened lobes with cUiated margins, continuous with those of
the ' chin,' which obviously assist in directing the food into the oesophagus."
Leydig notices, in Notommata Sieboldii, a sort of upper lip, not ciliated ; and
Huxley, in Lacimdaria, states that the moutli is vertically elongated, and its
cavity expanded into " tAvo lateral pouches, which give it an obcordate form ;
these lateral pouches contain the lateral ciliated arches that become lost
below in the cilia of the pharynx." In Floscularia the cavity of the mouth
is funnel-shaped (infundibuliform) (woodcut), and is termed by Dr. Dobie the
" infundibulum," who describes the edge to be "frequently divided into
lobes."

The mouth opens posteriorly into a canal, through which the food passes
to reach the " oesophageal bulb." Tliis canal has Tinfortimately received
various names, viz. mojiliagm, pharynx, vestibtde, infundilmlum, and "buccal
funnel." The first term lias Hkcwise been applied to another tube intci-vcning
between the " asopJiafjeal head " and the stomach ; hence a looseness of no-
menclature, tending to confusion and error in description. If, as is usually
done, the name " cesophageal hidh " be given to the jaws and their muscular
envelope, then that of oesoi^liagus rightly belongs to the canal leading thence

OF THE HOTATOEIA.

411

to the stomach. If, on the other hand, the " oesophageal bulb " be regarded
as an accessory stomach containiag a dental ajiparatus, as in the lobster, then
the term oesophagus belongs to the tube extending between the mouth and
the bulb. The following physiological distinction is, however, noted by Prof.
Williamson, who says — " The stomach of the lobster, with its dental append-
ages, is that in Avliich the digestive process is carried on. Such is never the
case with the pharyngeal bulb of the Eotifera. The digestive sac is situate
lower do-\vn. The phaiyngeal bulb bears closer afSnity to a gizzard, resem-
bling that of Bowerbankia and other Bryozoa, differing, however, from that
of a bird, which is located below the " proventriculus " or true stomach.
However, some confusion will be removed by avoiding the term " oesophagus"
and, without troubling oiu'selves with the precise homologies of the parts, by
naming the tube between the mouth and jaws the "pharynx " or " vestibule,"
the jaws themselves with their surrounding mass the " maxillary bulb " or
mastax (Gosse), and the canal between the last and the stomach the pro-
ventricular or gastric canal. The name " buccal fimnel " has been imposed
on the tube leading from the mouth to the maxillary apparatus by Mr. Gosse,
and might advantageously have been adopted.

To proceed. The pharynx (XXXVII. 19 a ; XL. 23 m) varies much in its
dimensions : sometimes it is a narrow tapering tube, and, when contracted,
visible only as a double line ; at other times it is wide and short, and then
especially deseiwes the name of "vestibule," since it ceases to be a canal.
Several peculiarities in its stnicture occm- in different genera, — the most re-
markable in Floscularia and Stephanoceros. In the former genus, the oral
cavity (infundibilum, Dobie) is separated from the pharynx by a rim armed
by non-vibratile ciha ; the pharynx itself is again subdivided by a fissured
partition or diaphragm, iuto an upper space (vestibule), and a lower large and
very dilatable cavity, called the " proventriculus " or " crop." The crop ends
below in, or in some measure embraces, the maxiUary bulb (see woodcuts,
Pai't II.). A similar structure obtains in Stephanoceros.

In Melicerta Prof. Williamson observed, within the pharynx near its
junction with the maxillary bulb, the ciliated lining membrane " to hang in
several loose, vibratile, longitudinal folds ; " and Prof. Huxley, in his account
of Lacinularia, gives the subjoined summary of these folds and valvular par-
titions :— " A narrow pharynx leads horizontally backwards from the lower
part of the buccal cavity, and becomes suddenly widened to enclose the pha-
ryngeal bulb in which the teeth are set (XXXVII. 19 a). "VSliere the buccal
cavity meets the phaiynx, a sharp line of demarcation exists. In Melicerta
two curved lines are seen in a correspondiag position, and evidently indicate two
folds projecting upwards into the oesophag-us (pharynx). In BracJiionus these
folds are stronger (XL. 1 b), while in Stephanoceros and Floscularia (XXXVII.
1 &, 19) this partition between the pharynx and what may be called the
crop is stia more marked. From the inner margin of the apertiu-o in the
partition, two dcHcate membranes hang do-mi into the ca\ity of the crop
which have a wavy motion ; and it is to them, I think, that what Mr. Gosse
describes as an appearance of ' water constantly percolating into the aliment-
ary canal ' is due. Dujardin had ah-eady noticed these ' vibrating membranes '
in Flosculann."

Observers coincide in describing the cilia of the oral cavity to extend into
and hne the pharynx (XL. 23 m). The walls of tliis tube are so very dilat-i
ble, that bodies of veiy considerable size can traverse it to the niaxillakr
apparatus. In the genera Lacinularia, Melicerta, Brachionus, Noteus and
Micolarm, close to the waU, or actually within its substance, as Levdisr
represents in Noteus, are two conspicuous structures, described by that author

412

GENEBAX HISTORY OF THE INFUSOBIA.

to be vesicular, and not improbably salivary glands (XXXVIII. 27 I). Mr.
Huxley alludes to these structures in the ensuing account : — " On each side
the pharynx is a yellowish homy-looking mass, which sometimes appears
cordate, at others, more or less completely composed of two lobes. I believe
its function is to give strength to the delicate walls of the pharynx, and that
it is, therefore, to be considered a part of the horny skeleton."

The phaiynx ends mostly below, and partially embraces the " maxillary
bulb " or "mastax," which contains the maxillEe or jaws supporting the "teeth,"
and has its mass made up of nuclear ceUs and muscular fibres (XXXVUI.
26 m). In the living animal the bulb is almost constantly in motion, con-
tracting and expanding itself in what some have called a " peristaltic " manner.
This alternate and constant movement, visible even in the embryo before escap-
ing from the egg, was mistaken by Bory St. Vincent, and other of the older
microscopists, for the pidsating action of a heart. The apparatus, however,
is rather comparable to the gizzard of birds, or to the tooth- crushing
mechanism in the stomach of lobsters and other Crustacea, though not,
indeed, homologous with it. The " maxillaiy bulb " is bulky, more or less
globose, vsdth a prevailing tendency to a triangular figure with rounded
angles (XL. 20, 23, 24). Sometimes it is oval or ovoid, and stUl more com-
monly heart-shaped, from being notched or fuiTowed on one side, indicating
a bilobed structure. In Melicerta Mr. Gosse figures and describes a third
lobe, below the usual " two globose bodies (or rather the bilobed single
mass), equally hyaline and probably muscular, which seems imited to the
two others, and alters in form as they and the jaws work, lengthening down-
ward as they approach, and dilating and shortening as they recede "
(XXXVII. 23).

The mass of the " maxillary bulb " surrounding the maxillae has been
generally assumed to be muscular, and, as such, actively concerned in work-
ing the contained jaws. Gosse calls it a " muscular sac," and has even
attempted the description of its component muscular bands. Leydig has re-
presented the jaws to be acted on by exquisitely striated muscles (XX'^T^I.
31). Prof. Williamson admits the existence of muscles affixed to the pro-
cesses of the jaws, but states that the conglobate organ in which these are
imbedded " is transparent, and composed of numerous large cells, each of
which contains a beautiful nucleus with its nucleolus. The cells are only
seen when the organ is ruptured between two plates of glass, when they
readily separate from one other ; but the nuclei, with their contained nucleoli,
are distinctly visible in the living animal. Dehcate muscular threads
most probably penetrate this organ to reach the dental apparatus, though I
have not yet detected them." Here a great discrepancy of opinion appears,
between Mr. Williamson and Leydig and most other writers, respecting the
constitution of the globose mass of the maxillary bulb, and such as only
reiterated examination can remove.

Dr. Leydig asserts that the bulb is covered externally by a chitinous
membrane, of the same nature as the cuticle, and that the existence of a like
membrane in its interior, developed for a special end, constitutes the maxiUjB
and appendages, just as bristles and homy plates and processes are developed
out of the extemal cuticle.

The maxillary apparatus, contained within the soft mass of the bulb, is
visible without any preparation, but may, from its hardness, be detached by
strongly compressing or cmshing the animal. Although much denser than
the soft tissues of the body, yet like them the dental apparatus disappears
by decomposition. Ehrenberg having an enormous number of Brachioni
in a vessel of water, evaporated the fluid, and ha^ing burnt the desiccated

OF THE ROTATORIA.

413

animals, examined their ashes chemically, convinced himself they contained
much phosphate of lime, derived, as he supposed, from the maxillfe. Mr.
Gosse likewise concludes that, from theii- great solidity and density, and
from the action of menstrua upon them, they are of calcareous nature.

The construction of the jaws, and the number and position of the transverse
bars or ' teeth,' afforded Ehrenberg characters of primary importance in the
construction of his system ; and he indicated three leading types, under which
all the Eotatoria could be classed, viz. : — " 1 . Agonvphia, toothless ; 2. Gym-
nogomphia, free-toothed (unconnected) j 3. Desmogomphia, connected or
attached teeth. In Gymnogomphia the teeth are fi-ee in front, and, like
the fingers, united behind by a common band — the jaw ; in Desmogomphia
they are attached transversely across the jaw-piece, like an arrow lies across
the bow. In the former, again, the teeth in each jaw are single or several in
number ; in the latter, either two or many. Hence there are 5 groups : —
1. Agomphia — e.g. Ichthydiiim, Chcetonotus, Enter oplea ; 2. Monogomphia
(one-toothed) — Pleurotrocha, Furcularia, Cycloglena, Monostyla, Lepadella ;
3. Polygomphia (many-toothed) — Hydatina, several Notommatce, EucTilanis,
Steplianoceros, Brachionus, &c. ; 4. Zygogomphia (twin-toothed) — Callidina,
Rotifer, Actinurus, Philodina, Monolabis, and Fterodina ; 5. Lochogomphia
(teeth set in rows) — Ptygura, Megalotrocha, Melicerta."

This classification of the Eotatoria, however, Ehrenberg confessed to be
imperfect, as wanting repeated researches to fix on the truly generic and
specific resemblances and differences of the dental apparatus. In fact,
although the conditions may be constant in the same species, yet they are so
minute, that they frequently can be made out very imperfectly and with un-
certainty ; and, besides this, the variations in the positions of the animal
when moving its body appear so materially to alter the form of the mechanism
in question, that careful students often differ respecting it in the case of the
self-same animal. To illustrate these remai'ks, we may appeal to the descrip-
tion of Melicerta ringens, as separately and independently detailed by Prof.
Williamson and by Mr. Gosse. The latter represents three or four transverse
bars or teeth to each lateral jaw (XXXVII. 23), the former above a dozen
(XXXVII. 26) ; the one detects a trilobed bulb, the other speaks of a sino'le
conglobate organ, but which, from his figures, might be called bilobed. Addi-
tional illustrations of such doubt and imcertainty are to be found on compar-
ing the descriptions of the maxillary organs recoimted by any two observers.
Ehrenberg's representations are now set aside by aU, improvements in the
microscope, and repeated examinations, having demonstrated theii- erroneous-
ness. The whole tribe of Agomphia or toothless Rotatoria must be set
aside ; for it seems a well-established rule, that no female of the class is de-
ficient of dental organs, and the genera Ichthtjdium and Chcetonotus cannot
as before shown, be retained in the class. Enteroplea, again, is in all ])roba-
bility a male animal, and Cyphonautes wants, according to Ehrenberg's plates
the characteristic organization of Rotatoria in all its details. But it would
be useless to continue an analysis of the other types established by the Berlin
Professor, the existence of any one of which, having the particulars of struc
turc assigned to it, is not to be demonstrated. Wliat is worse, we must con
fess to the absence of any one detailed account of the dental apparatus wliich
can be received with impUcit confidence in its accuracy ; so greatly have the
leadmg wntcrs on the Rotatoria difi-ercd among themselves in describing tho
mechamsra m question. "

.^,^»?7'"'' the following parts in the maxillaiy apparatus —

the ' fidcrum or support a single central piece with two articulated branches •
the .sc^p,« or lateral branch ending in an articulated point, " acies " and

414

GENERAL HISTOJiY OP THE INFUSOHIA.

itself single or multiple, which is the jaw properly so called. In most cases,
says Siebold, the homy jaws consist of two bent, geniculate processes, an
anterior and a posterior ; the latter gives attachment to the muscles moving
the apparatus, whilst one or several teeth are developed on the former. In
some many-toothed Eotatoria, each jaw is provided with three homy arches
(«. g. in. Philodina, Lacinularia, and Melicerta). Two of these arches (arcus
superior et inferior) are turned inwards, whilst the third {arcus exterior) is
directed outwards. To the under arch the muscles of the jaw are attached,
wliich move the other two arches, with their transverse teeth, against each
other.

Williamson gives the following particular account of the giiuding apparatus
of Melicerta : — " The gastric teeth consist of two essential portions, a pair of
strong crusliing plates, which bmise the food, and various appendages afford-
iug leverage and facilitating the action of the muscles upon them. The
crashers are two broad elongated plates (XXXVII. 26), each being about
•g-^th of an inch long, and sepai-ated from each other at the mesial line, near
which they become much thickened. Erom each of these plates there proceed
laterally numerous parallel bars, aU of which are somewhat thickened at their
inner extremities where they are attached to the plates, whilst at their oppo-
site ends they are united with the others of the same side by a curved con-
necting bar (fig. 26), from the outer sides of . which are given off various
loops and processes. The three uppermost of these bars ai-e the largest, the
rest gradually diminishing in size and strength as we descend, the inferior
ones being almost invisible. Prom the upper extremities of the two crushers
there project upwards and backwards two slender prolongations united by a
kind of double hinge-joint near their apex, where they not only play upon
each other, but also on a third small central fixed point, lodged iq a Httle
conglobate cellular mass. Ehrenberg only describes three transverse bars
on each side, which he regards as teeth. It is obvious that he has only
noticed the thi-ee upper and larger pairs. It is equally evident that these
transverse teeth, as he terms them, do not move upon the strong longitudinal
plates, as he imagines, but are firmly united with them. Muscles are either
attached to the divergent peripheral processes, or to the ccUular mass in
which these processes are imbedded, causing the entire apparatus to separate
into two parts along the mesial line by means of the hinge joint, the so-
called teeth merely transmitting the motor force to the two longitudinal
plates. These latter appendages are thus made to play upon each other with
great power, and act as efficient crushei-s, bruising the food before it passes
into the stomach, as is the case with the gastric teeth of the Cmstacea.
From the above remarks it will be seen that, though in its construction the
dental apparatus is more complex than is represented by Ehrenberg, in its
mode of working it is less so."

Prof. Huxley, to quote another accurate English observer, has seen in
Lacinularia socialis, as also m Stephanoceros, the " pharyngeal armature com-
posed of four separate pieces (XXXVII. 30) : two of these (wliich fonu the
' incus ' of Mr. Gosse) are elongated triangular prisms, applied together by
their flat inner faces ; the upper faces are rather concave, while the other
faces are convex, and upon these the two other pieces (the mallei of Mr.
Gosse) arc articulated. These last arc elongated, concave internally, convex
externally, and present two clear spaces in their interior ; fi-ora their inner
siuface a tliin curved plate projects inwards. At its anterior extremity this
plate is broMTiish, and divided into five or six hard teeth with slightly en-
larged extremities. Posteriorly the divisions become less and less distinct,
and the plate takes quite the appeai*ancc of the rest of the piece." Tliis is

OF THE ROTATOBIA.

415

essentially the same structure as that of tho teeth of Notommata described by
Ml-. Dahymplc {Phil. Trans. 1849), and by Mr. Gosse (XXXVI. 6) (T. M. S.
1851), and vciy different from tho stirrup -shaped " armature " represented
by Ehrenberg- and Dujardin in Lacinularia. Prof. Huxley notes, moreover,
the omission of the two pieces constituting the " incus," in tho description
given of the apparatus by Leydig.

The last-named author has attempted no general description of the dental
organs, and has, in the specific details, so briefly adverted to their structui-e,
that he would seem to attach to them little importance. He has, however,
figured the maxiUas of Notommata Sieholdii (XXXVII. 31), wishing especially
to represent the transversely- striated muscles acting upon them. He men-
tions the maxiUte, which occupy the spacious angular maxillary bulb, as ex-
hibiting a bifid or forked portion, hooked at the ends, with a spine projecting
from the inner side, and a margin on the outer side : to the latter the strong
muscles for opening and shutting the maxillae are affixed. The transverse
sti-iation of the muscles is particularly brought into vioAv by pressure on the
apparatus. Cohn (ZeitscJir. 1855) has some veiy precise details respecting
the sti'ucture of the dental mechanism of Hydatina senta, and of two or thi'ee
other Eotatoria ; but it would lead us beyond oiu' scope, to transfer them to
our pages.

The most elaborate attempt to unfold the true struetiu'e of the maxillsa,
and to reduce aU the varied foi-ms to a common type the essentials of
which are always detectable notwithstanding any degree of general modifi-
cation, has been made by Mr. Gosse. The diversity of descriptions met with
among writers on the Eotatoria, respecting the maxillae, is materially due to
the limited examination, undertaken by any one of them, of those organs, —
each observer having studied some one, or at most but a few species, and
then describing the peculiar maxillary organs met with as pervading the
whole class : such as is essential to the discoveiy of their true relations, a
comparison of their stnictiire among aU the genera, has been neglected. The
right mode of study seems to have been undertaken, by Mr. Gosse ; but his
conclusions require to be tested by repeated observation {Phil. Trans. 1855).
His method of manipulation, for tho purpose of examination, is well worth
noting. He says {op. cit. p. 424),—" In the course of experiments with
various chemical reagents on these animals, I found that a solution of potash
had the eff'ect of instantly dissolving the flesh and most of the viscera, leaving
the general integument, the walls of tiie pharyngeal bulb, and all 'the solid
parts of the manducatory apparatus uninjm-ed. In most cases also the last-
named organs are expelled from the visceral cavity by the contraction of the
integuments, so that they float at large in biilliant cleai'ness, undimmed by
intervening tissues, and as patent to obsei-vation as when crut*hed between
plates of glass, with the advantage of all the parts being unbroken and re-
taining their relative positions. Now, by turning the screw of the compres-
soiium, flattening or deepening the drop of water, waves were communicated
to it, by means of which the floating bulb, being nearly globular, was made
to revolve irregularly, and thus to present, in succession, various aspects to
the eye." ^

To display liis researches ever so briefly, wo must first introduce his no
mcnclatiirc. The gizzard or enclosing maxillaiy bulb, ho calls the nxasta.v
(XL. 20) ; and declares it to be a muscular trilobate sac. The maxiUce con
sist of two geniculate bodies {mallei) (XL. 20 b), and a thii-d on which thev
work {rnciis){XL. 20 f) Each malleus is of two piu'ts-l, the manubmnn
(c), and 2, the uncus (e),— united by a liinge joint. The manubrium is a
piece of irregular form, consisting of carinrr of soUd matter, enclosing three

416

GENEUAL HISTOHY OP THE INFU80EIA.

areas, which arc filled with a more membranous substance. The uncus
consists of several slender pieces, more or less parallel, ai-ranged like the teeth
of a comb, or Ulce the fingers of a hand.

The incus consists of two rami (g) articulated by a common base to
the extremity of a thin rod (fulcrum) (/^) in such a way that they can open
and close by proper muscles. The fijigers of each " uncus " rest upon the
corresponding ramus, to which they are attached by an elastic Ugament. The
" mallei " are moved to and fro by distinct muscles ; and by the action of these
they approach and recede alternately, the " rami " opening and shutting
simultaneously, with a movement derived partly from the action of the
" mallei " and partly from theii' own proper muscles.

Under aU the variations in form and disposition of the parts presented in
Euchlanis, Anurcea, SyncJiceta, Diglena (XL. 24), Polyarthra, Asplanchna,
Monocerca, &c., the same type prevails as in BracMonus (XL. 20-23) (which
is the genus Mr. Gosse uses as his standard of comparison). The modifica-
tions in those genera may in general " be considered as successive degenera-
tions of the ' mallei,' and augmentations of the incus. Ln another collection
of genera (the fixed or urceolate), the organs, although essentially the same
as in the former type, are somewhat disguised by the excessive dilatation of
the ' mallei,' and by the soldering of the unci and rami together into two
masses, each of which approaches in figure the quadrant of a sphere. The
ascribed ' stirrup-shaped ' armature of the Philodincea arises fi-om misappre-
hension ; for it has no essential diversity fi-om the common type, their analogy
with the genera last mentioned being abundantly manifest, though they are
still further disguised by the obsolescence of the ' manubria.' Lu Floscularia
(XL. 25, 26) and StepTianoceros (XL. 27, 28) the most aberrant Rotatoria,
the ' mastax ' is wanting ; and in the former genus the incus and manubria
are reduced to extreme evanescence, though the two-fingered unci show,
in theu- structure, relative position, and action, the true analogy of these
organs."

As to their homology, he argues they have no true affinity with the gastric
teeth of the Crustacea, though he states his conviction that the Rotifera belong
to the great Arthropodous division of animals.

"The action of the homy jaws," Mr. Gosse remarks in his account of
Melicerta, " is not exactly that of two flat-surface mullers, working on each
other in a grinding manner, but a complex motion impossible to be explained
by words." Since the nature of our work has compelled us to limit oui-selves
to a mere outline of Mr. Gosse's most elaborate and important researches on
the manducatoiy organs of the Rotifera, we cannot too sti'ongly recommend
the student to refer to that gentleman's essay in the Transactions of the Royal
Society, both for a more complete acquaintance with his views and discoveries
relative to those particular organs, and for a host of valuable details on
other parts of the anatomy of this class of animals.

Some Rotatoria, the so-caUed single-toothed species, have the faculty of
protruding their maxillae beyond the mouth, and of using them, in this curious
position, as prehensile organs. Thus the animal is enabled to seize upon
prey without awaiting its being casually engulfed within the vortex of its
ciliated head. Examples are found in Syyichceta mordax, in Disteinma
Forficula, and in Diglena (XL. 24).

The Tnn.xil1n.ry bulb communicates immediately, or by the medium of a mem-
branous canal, with the stomach — the next division of the alimentary tube.
This canal is very commonly termed the oesophagus ; but we prefer to call it
the proventricular canal, to avoid confusion and doubtful analogies. It com-
mences at the posterior inferior part of the bulb.

OF THE EOXATOMA.

417

Leydig represents this tube to be lined by a continuation of the chitinous
inner layer of the maxillary bulb, and uses this view to explain the distinct-
ness of outline frequently remarkable in the walls when of considerable
thickness, e. g. in Notommata cmtt-ura (XXXVIII. 26 q) and N. tarcligrada.
This shai-p contour is especially manifest during contraction of the canal,
whereby it is thrown into transverse folds or wrinkles, noticed by Ehrenberg
under the title of hard oesophageal folds," and elsewhere of a " rather firm
framework at the commencement of the oesophagus." Leydig adds—" The
organs described by Ehrenberg in Notommata saccigera, as ' large vibrating
giUs,' must, I think, be considered transverse folds of the chitin membraiie
in question." The existence of so dense a lining to the gastric tube implies
the absence of cilia on its surface ; and, in fact, Leydig declares he has never
seen the least sign of such organs, although both Perty and "Williamson affirm
their existence. The folds into which this tube is thrown when contracted
are occasionally (e. g. in Notommata Sieboldii) (XXXVII. 22) longitudinal
instead of transverse. Mr. Gosse says of it that it is " composed of longitu-
dinal and annular contractile tissue," and that, at least in Asplanchna prio-
donta (XXXVI. 9 1), " it is capable of immense dilatation, but commonly takes
the form of a slender tiibe Avith the lower extremity swollen, where an oval
pancreatic gland is attached on each side. The passage of a small morsel,
such as a Chilomonas, shows that the walls of this organ are thick, leaving
only a slender tube when corrugated." However, in different species the
width and the thickness of its walls vary much. The proventricular canal
has a considerable length in Diglena and SyncJiceta ; it is rather long in
Triarthra, Lacimdaria, and Hydatina, and very short in Euchlanidota, Bra-
chionma, and Melicerta. In not a few genera it is altogether wanting, the
maxillaiy bulb being superposed immediately upon the stomach : such are
Ascomorpha and the genera of the family Pliilodinaia.

The stomach succeeds to the gastric canal as a distinct segment separated
from the alimentary tube below by a constriction, and is remarkable also in
general by its greater capacity (XL. 1 e). Leydig affirms that a portion of
the digestive canal separated from the rest by a constriction, and essentially
representing a stomach, exists in all true Rotatoria; but other writers describe
as in Philodina (XXXVIII. 1, 2), and in Lhulia (XL. 1, 3), the existence of
a straight, slender, ftmnel-Hke alimentary canal extendiiig from the mouth
to the cloaca without any constriction or any stomach dilatation. In Jly-
datina and Synchceta, Perty says the canal is unifonn in calibre, without any
stomach-hke expansion ; yet Cohn distinguishes the narrower lower end of
the alimentary tube of Hydatina as an intestine, because it is less constantly
occupied with food, is colomiess, and, imlike the stomach, has no such cells
on its wall. Moreover, as an irregularity, he twice met -with a sphincter-
like constriction {pylorus) separating the two. In Euchlanis and Brachionus
on the other hand, the division is clearly indicated (XXXIX. 16). '

The opposing statements of authors on this question may probably be re-
conciled on the supposition that, of different observers, some have \T.ewed the
canal when it has been fuU and distended, others when empty and contracted
and that the constriction indicating a definite stomach has appeared only
during repletion, just as happens -with the human stomach, wliieh, when fuU
and engaged in digestion, is deeply constricted, and for the time appears
almost lilie a double organ.

Ehrenberg distinguished four types of Rotatoria, according to the cha-
racters of the alimentary tube, which he respectively named— 1. Tracheio-
gastnca; 2. Cnelogastrica ; 3. Oasterodeh ; 4. TracMocystica.

1. The Trachelogastricu comprohondod animals having a long filiform gullet

2 E

418

GENEHAl, niSTOnY OF THE INFUSORIA.

rapidly transmitting and not retaining the food, and terminating in a compa-
ratively short conical intestine, without a stomach dilatation, e. g. Ichthydium,
Chcetonotm.

2. Goelogastrica, Rotatoria with a very short gullet, a long conical in-
testine, and no stomach, e, g. Hydatina, Synchceta.

3. Gasterodela, those Rotifers having an evidently developed stomach, or
a dilatation of the alimentary canal limited hy a definite constriction,
e.g. EucManis, Bracliionus, Lepadella, Diglena, &c,

4. Traclielocystica, with an indistinct gullet, hut having a very long, fili-
form, small intestine, in which the food is detained, and aLso a large globular
intestine (rectiim or cloaca) placed close to the discharging orifice, e. g. Rotifer,
Actinurus, Philodina.

Subsequent independent observers have been able neither to recognize aU
these distinct types of structure nor to admit their value. Leydig, in fact,
insists that the so-called " gasterodelous " type is the only one seen in Rota-
toria ; but, as just now stated, several authors admit the existence of a simple
conical or tapering alimentary tube, without dilatation or stomach, in several
of the class.

The Trachelogastrica are represented only by beings which are now, by gene-
ral consent, excluded from the Rotifera. The termination of the intestine in
a dilated sac-Eke expansion, in which also the generative canals end, whence
its name, " cloaca," is the rule ; or, to use Ehrenberg's term, the majority of
the Rotatoria are Traclielocystica.

The stomach dilatation, lake the rest of the alimentary canal, is capable of
great expansion, by which its figure is considerably altered. Usually but
one gastric cavity has been described ; but in some species there is a second,
and Huxley, in his history of Lacinularia (XXXVII. 19), describes three
portions or divisions between the gastric canal and the rectum, — ^the first
with two pyriform sacs opening into it, the middle one frequently with several
short ceUular caeca, and the lowest with several cellular casca projecting ex-
ternally, and clothed within with very long ciha. According to Prof. Wil-
liamson, the stomach of Melicerta (XXXYII. 17) consists of an upper and
lower segment, separated the one from the other by a marked though vary-
ing constriction, — the upper stomach elongated, the lower almost spherical.
Mr. Gosse describes this same organization in Melicerta, but calls the upper
segment "a wide cylindrical stomach," and goes on to say that the food
passes from this into a globose intestine which ends in a slender but dila-
table rectum.

A similar double organ is found in Floscularia, Ste^hanoccros (XXXYII.
1/), and Tubicolaria. Moreover Ehrenberg noted a sac attached to the
stomach of Megalotrocha, which ho called a caecum. The configimition of
the stomach is otherwise altered by tubular and saccular appendages, and in
a few instances is lobular, as stated by Mr. Gosse in Aq^lancJina (XXXYI.
9 s). Ehrenberg states, at p. 399 of his great work, that the stomach of
Lacinularia is complicated by two blind tubes (intestines), and yet, at p. 403, '
reverses this statement by saying that it is " without blind intestine-like ap-
pendices." Leydig admits the latter as the ti-uth ; but, as ali-cady seen,
Huxley remarked two pyriform sacs attached to the first, and casca to each
of the other two segments. Ehrenberg further describes ca;eal appendages to
the stomach of Notommata clavidata, and of Diglena lacustris, but such were
probably the turgid stomach-cells presently noticed.

The tissues or histological elements entering into the fonnation of the
stomach arc — 1, a hmiting external membrane, and, 2, an internal layer of
epithelium (XL. 4). The former is tlxe same tissue with that constituting

or THE ROTATORIA.

419

the walls of other portions of the alimentary canal, and is supposed by many
to contain muscular fibriUoe, although so vciy thin, pellucid, and apparently
structureless. Leydig, however, calls it a homogeneous connective tissue.
The hning of epithehum is made up of large turgid cells, rendering the wall
thick and of a pulpy appearance (XXX7III. 26/). In young animals the
epithelial cells are colom-less ; but in adult beings their_ granular contents
are coloured and interspersed with fat-globules, whence it is that the waUs
of the stomachs assume a yellowish hue often intermingled with green and
brown tints. The cells, moreover, commonly possess a nucleus and a nucle-
olus, and their free surface is constantly ciliated. They are readily detached
from the subjacent membrane and from each other, and are then seen to have
a spherical or ovoid figure.

" The great thickness of the epithelial layer," writes Mr. Williamson, " as
compared with the entire diameter of the organ, is curious : whilst the latter
averages about j^th. of an inch, the former is often not less than y^-^th,
or -l-th of its entire diameter. The cells, when detached, vary in size, from
a diameter of ^ J-^ ^th to -g-^^th of an inch ; one of these was fringed with
cilia Yjrljj-jjth of an iach long, and had a nucleus ^^^^^)th of an inch. After
being detached, some of the ciliated cells floated slowly away, like so many
animalcules."

Although this description and the measiu'ements refer specially to the
Melicerta ringens, yet the relatively large size of the cells is a feature com-
mon to all the Eotatoria, and has been pointed out and figured by Leydig,
Siebold, and others.

The second stomach, noticed by "WLlliamson in Melicerta, also had a layer of
epithelial cells bearing cilia " even longer than those of the upper viscus,
— although the parietes were very much thinner and more transparent, the
cells being less easily traced." In the third or lowest dilatation, seen by
Huxley in Lacinidaria, the interior was clothed with very long cilia (XL. 4).

Ehrenberg remarked the existence of large stomach- cells in Diglena la-
cmtris, and of less distinct ones in Notommata Myrmeleo and N. Copeus, The
pouches he speaks of around the alimentary tube of Hydatina senta, and
which imparted the appeai-ance, to his eye, of a bunch of grapes, are no other
than epithelial cells. In Philodincea the intestinal canal is stated to be fili-
form, and enveloped in a granular ceUular mass ; that is to say, the calibre is
very much reduced by the tirrgid cells lining the walls. The compact mass
of blind tubules, so described in Rotifer, admits a like interpretation.

In Notommata tardigrada Leydig failed to detect cilia either in the stomach
or intestine.

In the great majority of the Rotatoria a definite " intestine " foUows the
stomach, and ends below in the cloaca. This intestine is generally laiown as
the " rectum," and is supposed to represent the large intestine of hi"-her ani-
mals. It varies much in its dimensions in different species, especidly in ita
length and course. It is long, straight, and capacious in Notommata centi-ura
(XXXVIII. 26), and in Euchlanis triqiietra (XXXYIll. 5), short in Lacinu-
laria, and extremely short in Notommata tardigrada.

Among the encased Rotatoria it is of considerable length, owing to its
curving forwards from the second stomach, so as to reach its outlet near the
margin of the enclosing urceolus, or in other words the neck of the animal
and thereby provide for the immechate removal of the excrcraentitious matter
from contigiuty with it (XXXVII. 17). In Stq^hanoceros and FloscuUria as
exceptions to this rule, this intestine is short. Looking at the so-caUed second
stomach, placed at the head of the rectum in those fixed Rotifers wo might
rather assimilate it to the caicum, which in some of tlio liigher classes forms

2 e2

420

GENEBAL HISTORY OIT THE INFUSOBIA.

a sort of subsidiary stomach, where the digestive process is finally completed.
Still it is not j)ossible to establish aU the minute homological relations be-
tween these animals and those of the vertebrate class. The intestine, like
the stomach, has a limiting membrane, possibly muscular, and is lined by a
ciliated epitheliimi which, unlike that of the stomach, is not coloured, and
its cells less easily detected. It is capable of very great distension. The
rectum commonly ends in, or, it may be said, expands into, a globular sac,
which, from its likewise receiving the eggs from the oviducts opening into it,
is analogous to the cloaca of birds (XXXVIII. 26 i). This cloaca has a
fine, transparent wall, and opens, posteriorly or dorsaUy, at the base of tho
pseudopodium, or, where this segment is absent, near the extremity of tho
body, by an oiitlet usually called the anus.

The cloaca is particularly dUatable ; for sometimes it is much loaded with
accumulated faecal matter, and at others is distended by one or more of the
enormous eggs the Rotatoria habitually produce. In discharging an egg, or
in emptying itself of other matters, the cloaca is everted and thrust out
through its external orifice.

From the mode in which the walls are drawn into longitudinal and cii-cular
folds, as exemplified in Notommata centrura (XXXVIII. 26), Leydig is in-
duced to admit the presence of muscular fibrils regularly disposed in the
two corresponding directions. Moreover the manner in which the cloacal
orifice is closed, after the extrusion of any mass, indicates, in this author's
opinion, a sphincter power, and consequently the presence of muscular fibres
aroimd it. The contraction of the entire canal on itself is sometimes so great
that it is only manifest by a streak.

A most remarkable structural exception is met with among certain female
Eotatoria, viz. the entire absence of an intestine and anus. It prevails in
the gemis AsplancJma (Gosse), in the Notommata Sieboldii (Leydig) (probably
in N. Syrinx), m Ascomorjiha Helvetica (Pevty), and iaA. Germanica (Perty)
(XXXVI. 9 ; XXXVII. 32 ; XXXVIII. 28). This want of a discharging
posterior outlet necessitates the rejection of excrementitious matters from the
stomach through the mouth.

This structure is so very exceptional and peculiar, that Prof. Williamson
is not prepared, without further evidence than has yet been advanced, to
admit it as true of any Eotifera. It is, he writes (in lit.) contrary to pro-
bability, and, if established, would induce him to exclude the animals so
organized from that class.

Reception of Food — its Deglutition, &c. — The food of the Rotatoria, as
before noticed, is attracted towards the mouth by the vortex caused by tho
rotation of the cilia crowning the head. An exceptional means of prehension
is seen in those Rotatoria which protrude their jaws beyond the mouth, using
them as piacers or forceps to seize any larger prey. " In general," Avrites
Mr. Gosse (Phil. Trans. 1856, p. 429), " the cihary vortices are sufficient to
bring the prey within the buccal funnel (pharynx) ; but in several genera
of the family Euchlanidota, as Metojndia, Colunis, Monura, and Stephanopf.
there is a curious accessory organ, Avhich aids in the capture of the prey ; at
least I am sure it is so employed in several species of Mctopidia. Thus in
M. acuminata the frontal region is formed by an arched fleshy process occi-
pitally, which is approached by a small one on the ' mental ' side ; and be-
tween these is the -wide entrance of the buccal funnel. The occipital process
is protected by a homy crystalline plate, fomiing a segment of a sphere, and,
when viewed laterally, taking the appearance of a curved horn. It can be
partially protnidcd and retracted, and also bent down to meet tlie mental
lobe. This appoi-atus, when the animal is taldng food, is kept in vigorous

OF XnE BOTATOniA.

421

action. A strong vortex is produced by the ciliary wheels ; and as the
floating atoms whirl by, the moveable plate is thrown forward with a grasp-
ing motion, the fleshy head being at the same time protruded, and, when
the lobes are in contact, retracted. This is repeated almost every instant
with manifest eagerness and discrimination, the manducatory apparatus
working vigorously all the while.

" The same cmious organ is frequently employed in another way. It is
bent considerably downward ; and as the animal crawls deliberately up and
down the stems of aquatic plants, it is used to rake and grub, among the
floccose deposits, the minute Biatomacece, Sec, that adhere to them."

Having entered the mouth, it is usually rapidly conveyed along the pharynx
to the jaws. In those species which have the pharynx expanded into a " crop,"
such as Floscularia and Asplancha, this transmission of the food is less speedy.
Mr. Gosse imagines the " crop " to possess a suctorial power. He says —
"I think that when the animal {Asplanchna prioclonta) is cognizant of food
brought to the mouth by the ciliary vortices, it suddenly expands the crop by
the action of the muscles that go from it to the skin, when the water rushing
into the vacuum carries in the prey. Then the network of fibres contracts
again, and the prey is secured."

Having reached the "maxillary head," the food is "lodged" (to quote
Mr. Gosse's paper) " upon the ' rami ' between the two ' unci.' These con-
jointly work upon the food, which passes on towards the tips of the ' rami,'
and enters the oesophagus (the proventricular tube), which opens immediately
beneath them."

Having escaped the mandibular apparatus, the food is subjected to the
action of some digestive fluids which are poirred iato the portion of the ali-
mentary tube below, whether that portion be dilated into a distinct stomach
or retaiu a nearly uniform calibre. How long this process of digestion need
be continued, we have no data to determine ; but we may conclude that the
time will vary according to the nature of the food, the condition of the animal
its species, and other circumstances. In Melicerta ringens, which has a double
stomach, Prof. Williamson remarks that the upper one " appears to be chiefly
a receptacle for the food. From time to time, especially when the viscus is
distended, a portion of its contents pass down into the lower stomach." In

this the mass of food usually distending it " is constantly revolviu"- the

motion being due to ciliaiy action. This process goes on for some rainutes
after which the creature contracts its body, and forces the entire exuvite out
of the viscus into a long narrow cloaca (rectum), which terminates externally
by an anal outlet. As it does this, it everts a considerable portion of the
cloaca, thus almost bringing the cloacal outlet of the stomach to the exterior
and causing, at the same time, a large transparent protuberance to be deve-
loped on the corresponding side of its body. At other times the creatui-e can
draw in these appendages, so that scarcely any trace of a cloacal canal is visi-
ble." Mr. Gosse suggests that this protrasion, at the moment of discharge
is designed " to shoot the faDcal mass out of the case " (urceolus) • for tlie
outlet is then projected above the rim. " The foeces," he adds, " arc slightly
coherent and jelly-like, not at all like the coloui-ed pellets of which the m-ce-
olus is built up."

The food of the Rotatoria consists of the lower Algaj, of Protozoa Ento
mostraca, other Kotifers, and even the weaker members of the same succios"
" The stomach," remarks Mr. Gosse, " of the Asplanchna is frequently oceu '
pied with ammals ; the smaUer AnuTaio}, as A. aculeata, A. curvkomis m
and A. stijnlata {?), seem to constitute its chief food. I have taken one with
the species last-named m its stomach, which, after about an horn-, was ejected

422

GENEBAL JUSIOEY OF THE rNFTJSOKIA .

and swam about as lively and apparently uninjured as ever. In one I saw
several specimens of a long slender FragUaria loose in the cavity of the body,
and in the stomach of another the long cell of a Conferva."

From the manner in which the food is obtained, apparently without any
selection on the part of the animals, the vortex driving into the mouth what-
ever particles may come within its reach, we might conclude that the con-
tents of the stomach must be of a veiy miscellaneous character. This is true
to a great extent ; yet the Eotifers can eject what is unsuitable, and they
have the power of moving from place to place in search of suitable nutri-
ment, or at least, as in the fixed forms, of an-esting and withdrawng the
ciliary apparatus until noxious materials are floated past, or appropriate ones
have come within reach. That they are passive recipients of the current
setting into their mouths, is indicated by their swallowing carmine or other
colouiing matters mixed with the water, which, as Mr. Gosse observes, are
deleterious to them.

The feeding of Rotatoria with colouring matter serves a practical purpose
in the examination of their structui-e ; for it helps to reveal, by the contrast
of coloured with uncoloured parts, details of structure not apparent amid the
uniform and delicate hue of the entire organism in its natural state. For
example, Mr. Gosse writes — " The process of swallowing carmine enabled
me to see (in Melicerta), very distinctly, that the oesophagus enters the giz-
zard between the larger ends of the jaw-mullers, and that the stomach-duct
leads off from their smaller ends through the semiglobular lobe beneath."
The same observer employed this means to demonstrate the manner in which
the case of the Melicerta is deposited, and with very satisfactory results
(see p. 425).

The Seceetds'g System. — Special organs of secretion exhibit themselves in
the Rotatoria under the simplest form of ceUs, and of involutions of the lining
membrane of the alimentary tube, as sacs and tubules. Frequently theii-
contents are coloured ; and these always differ in density and physical ap-
pearance from the general fluids of the body. The glandular organs situated
about the walls of the digestive canal, are supposed to have discharging ducts
through which their contents percolate into that tube.

The testes or spermatic glands in the male, and the ovary in the female —
both of them secreting organs, — together with some accessory secerning vesi-
cles, will be described under the section on the Reproductive Organs. Some-
thing has already been said of some other glands in the last section, on the
Digestive Organs : a more precise account is, however, necessary.

The most constant glands are the two situated on the upper siu-face of the
stomach near the entrance of the gastric or proventriculai" tube, and some-
times on that tube itself (XXXVIII. 26 7i, 211). _ They are usuaUy hemi-
spherical or oval, but assume other shapes, as pp-iform, conical, cylindrical,
reniform, crescentic, and forked. In a few, e. g. Noteus and some Brachiona'a,
they are stalked, or, more properly speaking, have an elongated, tapering ex-
tremity. Cylindrical or club-shaped glands are seen in Notommata cJnvxdata,
and forked ones in Dirilena lacustris. In these two species, and also in Mc-
galotrocha there are likewise four long filiform tubes, equalling the glands in
length, and of the like colom-, but opening at the centre instead of the fore-
part of the stomach. In Pohjarthra, Leydig noticed two elongated secreting-
sacs attached to the posterior surface, and in Lacimilaria, a pair of glands,
instead of a single one, at the fore part of the stomach. Not being able
to detect the ducts of the "2-3 pyi-iform glandular (?) -loolung bodies often
attached to the base of the upper stomach (of Melicerta) near the constriction
which separates it from the lower one, Prof. WiUianison licsitatcs to call

OF XHE BOTATOKIA.

423

them glands, and doubts likewise the secretoiy character of the similai- but
larger bodies seen in the neighbom-hood of the oesophagus."

The glands are usually transparent, or have only a slight milky opacity ;
they contain fine nucleated granules and molecules, and in some examples,
e. g. Polijarthra (XXXVIII. 39) and Pterodina, a few small oil vesicles.
Externally they are invested by a transparent homogeneous membrane, to
wliich, in Albertia, Dujardin assigned an active contractility; but this is very
doubtful. " They are," says the French naturahst, " stalked sacs, placed at
the commencement of the intestine, susceptible of contraction, pouring out
theii- secretion into the intestine, from which they again fill themselves, and
undergo dilatation : in this example at least, these appendages must be con-
sidered cteca rather than glands." Sometimes," Leydig obsei-ves, " the
elements of the contaiued granular mass have an elongated figure, as in iVo-
teiis; and then the contents of the glands assume a striated appearance."
This account recalls that given by Mr. WilHamson of a glandular structure
he supposes may possibly represent a spermatic gland ; but of this hereafter.
Cohn believes he detected the exudation of a blackish granular fluid from
these glands in Hydatina senta, and its entrance within the stomach by a
definite aperture.

The granular vesicles of the glands were termed " vacuoles " by Dujardin,
and have been represented by Ehrenberg in many figures, e. g. of Euchlanis
macrura, E. dilatata, Megalotroclia, and Lacinularia ; they have also been
spoken of by him as " glands, vesicular within." Moreover the sharply-
defined clear vesicles he has represented in Theorus (XXXIY. 427-429) and
Pterodina, and termed " eyes," Leydig believes to be nothing else than fat-
yesicles of the gastric glands. Mr. Dalrymple has accurately figured these
glands in his so-called Notommata {Asplanclma) Anglica (XXXYI. 9 g).

The function and homologies of these gastric glands are doubtful. Ehren-
berg's fii-st notion of them was that they were spermatic ; but he subsequently
changed his views, and called them " pancreatic." Eor what reason," says
Prof. Rymer Jones, " Ehrenberg has given the name of pancreas to these se-
creting caeca, it is difficult to conjecture, since the fii-st rudiments of a pan-
creas are only met with in animals far higher in the scale of animal existence ;
every analogy, indeed, would lead us to denominate these caeca the fii-st ru-
diments of a liver, by far the most important and imiversal of the glandular
organs subservient to digestion, and in a variety of creatures presenting an
equal simplicity of structure."

However unsupported the notion of the pancreatic or salivary nature of
these glands may be, it has met with several advocates, who have in aU pro-
bability assigned to them this function rather from the want on their part of
any definite opinion of their character than for any other reason. Thus Dal-
rymple aUudes to them as salivary glands ; and Perty affirms of two filiform
vessel-like appendices of the stomach (?) in Enteroplea, that they are repre-
sentatives of the pancreas or of salivary glands. Siebold adopted a similar
hypothesis ; but Leydig, on the contraiy, regards them, in a morpliological
point of view, not as pancreatic glands, but as the analogues of those pro-
cesses often seen on the stomach of Arthropoda ; ho would therefore desig-
nate them generally gastric glands, — a view with which we are disposed to
coincide. The small glandular appendages on the dorsal surface of the sto-
machs of starfish, suggest themselves as of the same nature as the appendages
under consideration.

A yellowish clear body is situated on each side of the pharynx, imme-
diately m front of the raaxiHary bulb, in Lacimdaria, Tubicolaria, Meliceria
and Braehionus (XXXIX. 16), and rather Avithin the substance of the bulb

424

GENERAL HISTOUY OF THE INFUSOMA.

in Noteus. This is possibly the stnicture alluded to by Mr. Gossc as " several
yeUow glandular (?) spots " seated on the top of the cushion of the dental
organs of Asplanchna (XXXVIII. 28), and the same with the yellowish,
clear, homy-looking masses mentioned by Huxley in Lacinularia (XXXVII.
19 g) and Brachionus. The last-named naturalist refers these bodies to the
" homy skeleton " (see p. 412), Leydig considered they might possibly be
" salivary glands."

The epithelium of the alimentary canal has probably a glandular purpose :
its large cells are filled with a granular matter, and many oU-vesicles, besides
a micleus. The number and large size of these gastric cells have been already
illustrated (see p. 419) ; they are mostly coloured — yeUow or yellowish bro-svn,
with sometimes green spots interspersed. Ehrenberg remarked these ccUular
accumulations, and advanced the hypothesis of their homology with the liver
of higher animals. The colouring matter was consequently esteemed to be
the bile. We have seen that Kymer Jones has assigned the functions of a
liver to the so-called " pancreatic " sacs, or " gastric glands." However,
most naturalists favour Ehrenberg's view ; among them are Dujai-din, Sie-
bold, Leydig, and Dahymple. The belief, indeed, of the great BerHn natu-
ralist was, that the cells grew from the exterior of the wall of the aUmentary
canal, and were so many saccular appendages ; this view modem research,
does not countenance, but affirms the presence of the cells within the canal.
The examples of secerning cells given by Ehrenberg deserve to be mentioned.
He remarked that ia Enteroplea the biliary cells and ducts were most pro-
nounced, and that there was great accumulation of cellular or glandular ele-
ments about the intestiae of Rotifer, Oallidina, and Philodina. ; in the last
two he also asserted that the mass becomes coloured by colouring particles
swallowed by the animals.

Mr. Gosse puts the question whether the little granular body near the
tip of the pedicle of Melicerta is a secerning gland for the secretion of an
adhesive glue, by which the foot adheres, as in Monocerca. This faculty
of secretiig an adhesive matter from the end of the pseudopodixmi is sur-
mised by Perty to be possessed by several Rotatoria, viz. by Comchilus, La-
cinularia, CEcistes, Floscularia, lAmnias, Tuhicolaria, and StepTianoceros.
This idea is countenanced by Cohn (Zeitschr. 1855, p. 439), who inclines to
the belief that the sohd-looking elongated-oval bodies situated at the poste-
rior extremity of the abdomen of Brachionus and other species, and usually
considered muscular (moving the tail-process), are rather of a glandular na-
tui'e, and possibly secrete an adhesive glue to fix the animal. More recently
(Muller's ArcJiiv, 1857, and A. M. E. 1857, xx. p. 292) Leydig has accepted
this view, and thus treats of these stractiu'es in Hyclatina senta : — " The
elavate bodies in the tail consist of a delicate envelope and pale molecular
contents, in which beautiful nuclei, each with a nucleolus, may be distin-
guished ; in many individuals, small fatty points ai-e also present in variable
amount. I regard the organs in question as glands, wliich in their position
and function con-espond with the caudal glands of Enoplus for example ; they
open at the apex of the caudal appendages {Fusszangen) ; and as the worm
just mentioned ' can attach itself fii-mly to the object-bearer by the posterior
extremity of the body, in order to cany the body round this point with a waving
motion,' so also can the Jli/datina fix itself by the tips of the caudal append-
ages, probably by means of the sticky substance excreted here. It seems to
me also, that in a certain upright position of the caudal aj^pcndages, I have
detected the opening at their tip."

Other large vesicles, which some think may be glandular, occur in different
parts of the body, and in the foot-process of several genera. Such are noticed

OF THE KOTATOMA.

425

by DoWe in the pseudopodium of Flosculana ; and Leydig mentions a clear
gland or space at the root of the tail of Laoinularia, from which he supposes
a duct to extend to the extremity ; such a structure Huxley cannot discover,
but states that the extremity of the tail always seemed to him " to present
a cihated hemispherical cavity, closed above the supposed gland at the base
he called a " vascular mass."

An active secreting power is displayed by those Rotatoria which invest
themselves in cases or urceoh ; for such cases are always produced from the
animal, and are the result of excretion. The formation of its case by the Meli-
certa ringens has often been most thoroughly examined ; and Mr. Gosse was
enabled to watch the deposition of pellet by pellet of the excreted matter.
This direct observation has entirely overthrown the prevalent notion first ad-
vanced by Ehi-enberg, that the case was built up of excrementitious particles
discharged from the ahmentaiy canal. The organ actively engaged in the
building of the case is seated immediately above the long tubular process
extending from the neck of the animal (XXXYI. 1 c) ; it is cup-shaped,
and its concave surface so cUiated, that when in full activity it seems
to revolve. In this, which Mr. Gosse calls the "pellet-cup,'" the building-
material seems to be prepared and fashioned into an oval or hexagonal figure,
and then the pellets so moulded are regularly laid down in rows, " straight
and xminterrupted perpendicularly," but zigzag transversely, so that a dia-
gonal disposition is the result. " Each peUet, examined separately, is of a
yellowish or olive colour, composed of granules ; the whole tube is of a red-
dish-brown (XXXYI. 1 d). After a certain number were deposited in one
part, the animal would suddenly turn itself round in its case, and deposit
some in another part." It seems that the action of the peUet-cup is volun-
tary, and not always coexistent with the passing of the ciliary cuiTent over
the chin. The animal frequently makes abortive eff'orts to deposit a peUet,
and sometimes bends forcibly forward to the edge of the case before the pellet
is half formed. Coloured particles in the water are hurled round the margia
of the ciliated disk until they pass off in fi-ont through the great sinus be-
tween the large petals ; and the atoms, if few, glide along the facial siu-face,
following the irregularities of the outHne with great precision, and, dashing
round the projecting chin, lodge themselves one after another in the little
cup-like receptacle beneath, in which they are whorled round with o-reat
rapidity, and prepared into pellets for the construction of the case. On mix-
ing carmine with the water, the torrent that poured off in fi,-ont and the ap-
pearance of a rich crimson pellet in the cup were instantaneous. A lai-"-e
animal which had its case accidentally sUt for some distance, watched for
several days, was seen to make pellets frequently ; yet it never deposited them
nor attempted to construct a new case, but let the pellets float away."

Such is a resume of Mr, Gosse's interesting observations. Prof. "Williamson
adds that, when the animal is not engaged in its architectural occupations,
the sac (peUet-cup) becomes so contracted as to be almost invisible, '

In connection with this subject of secretion, must bo mentioned the views
of Leydig respecting the accumidation of granules or crystalline particles
seen in many embryonic and yoimg Rotatoria, enclosed in a sac contiguous
to the cloaca (XXXVII, 4 ; XXXVIII, 7, 8). Ehi-enberg remai-ked these
granular heaps m Mtcrocodon, Lacinularia, Stephanoccros, Floscularia omnia
Enteroplea, and in Notommata granidaris, and called them at one time " a
dark glandular body or speck," at another " a single glandular organ " having
no evident fimction. Weisse represented them to be unconsuraed and
stiU-remammg ycUc-substance, and supposed the animals presenting such
granular masses " premature " or " aborted." Williamson noticed siniUar

426

GENERAL HISTOET OF THE INPT7S0UIA.

masses in Meliceria, and found that they disappeared soon after the youn"
animal escaped from the ovum. °

Leydig's conclusion, from optical and chemical qualities of tlie granules, is
that they are ui-iiiary or uric concretions, and that the clear- space containing
them is formed by the end of the iatcstinal canal, or by the cloaca. To
elucidate this view, an analogy is pointed out in the case of those insects
which undergo complete metamorphosis, in which solid urinaiy concretions
accumulate in the rectum during the pupa-state, but are evacuated when the
insect emerges from that toi-pid condition.

The actual secreting organ of these urinary concretions, or in other words
the kidney, must, says Leydig, be sought for in the cells of the intestinal
wall, which stand out in a knob-Uke matter. Ehrenberg's account of the
" dark bodies " about the rectimi of Enteroplea, and of Notommuta granularis,
favours this opinion ; and the granular heap near the termination of the
intestine of the larva of Cyclops may be adduced as another allied fact in
illustration of the nature of the bodies in question. Vogt, however, is opposed
to this presumed analogy, and states that this peculiar collection in the cloaca
of embryo Cyclopes is originally produced of a green colour, within a sac on
each side of the intestine, and when subsequently dischai-ged into the cloaca,
is of a yeUow hue. These sacs therefore have, in his estimation, rather the
signification of a liver than a kidney. The like structures are common enough
in Vermes. Excepting therefore, Leydig contends, male Rotifers, urinary
concretions occur only in the embryo and in the first period after birth, and
the existence of a primordial kidney must be admitted as a fact. Cohn has
come forward to oppose these views of Leydig, and says that this whole hy-
pothesis falls with the proof that in Enteroplea the vesicle with the dark
granules stands in no sort of connexion with the intestine, nor, indeed, can
do so, as no intestine exists, and it is rather firmly adherent to the outer wall
of the testis. To this adverse opinion Leydig rejoins (Miiller's ArcMv, 1857,
p. 404, and A. N. H. 1857, xx. p. 295) that Cohn's " undoubted proof" is
itself an error ; " for the clear space containing the dark gi-anides is not ad-
herent to the true wall of the testis, but to that outer envelope which repre-
sents the nidimentary stomach and intestine ; or, more properly speaking, the
clear space enclosing the concretion belongs to the abortive alimentary canal
itself, which extends from the notch of the rotary organ to the cloacal open-
ing, so that Enteroplea displays the same characters as the other Rotatoria,
although this is in complete opposition to the description given by Cohn. My
opinion, that the granules in question are uiic concretions, is, of com-se, no
more strongly supported by the position of matters detected in Enteroplea
than before ; but the obj ection raised by Colin appears to be removed. The
opinion first put forward by Weisse, which is also favoured by Cohn, that the
granules are the remains of imuscd yelk-masscs, I must reject, without taking
other reasons into account, if only because the viteUino elements and the
granules in question have no resemblance to each other, but are perfectly
different things."

Several authors have suggested that the vascular apparatus to be described
as a respii'atory organ in the following chapter has also in part, or even
principaUy, the fimction of a kidney or excretory organ. These views can
be best propounded after the apparatus in question has been described.

TuE Yascular and RESPnuTORY Systems (XXXVIII. 26 c,i,l', XL. 1 i, 5).
— The existence of vessels subsement to the circulation of a fluid analogous
to blood was surmised by Ehi-onberg. Among such assumed stracturcs were
the transverse cords to which the semblance of articulation is often due,
as well as other similar bands now ]iroA-cd to be muscular fibr&s of con-

OF THE EOTATOTITA.

427

nective tissue. For instance, the intercm-rent fibres about tlio head and neck
of the Rotatoria, and the interlacing cords passing forward to the lobes of
the rotary organ, and backward to the maxillary head, were reckoned parts
of the vascular system.

The piu-pose of a cii'culatory system is to convey the blood (the nutritive,
reparative fluid) within the reach of eveiy tissue and organ, so that all its
parts may be renovated, and their effete, worn-out particles removed. The
necessity for such a contrivance is at once intelligible in large animals, where
the parts have considerable size and thickness, and are pretty closely packed
within the limits of the body ; but in the case of the Rotifers, the proto-
plasmic fluid fills up all the large space within the body unoccupied by the
viscera, and is in immediate contact with them, whilst none of them have
such a density or thickness as to preclude their being readily permeated by
it. The result of digestion within the alimentary canal is the production of
a nutritive juice or chyle, which apparently passes by exosmosis through the
walls of the canal into the general cavity of the body, mixing there with that
already existing, and is the representative of the blood of higher animals.
But, in addition to this, a constant renovation of the chyHferous liquid of the
body, by water taken in from without, appears to be necessary.

Ehrenberg witnessed a periodical transparency in the body, with an alter-
nating distension and collapse occuriing regularly in almost all Rotatoria.
Duiing distension, the outhne of all the viscera seemed clearer, whilst, upon
the collapse, the organs approximated their limits, became less defined and
somewhat confused, and the integument crumpled. These movements he attri-
buted to the alternate entrance and exit of water from without, thi'ough the
medium of the supposed siphon tube on the head, or of openings upon other
parts of the body. It has, however, been shown that the siphon and apparent
openings have no external commimication ; we must consequently believe, with
Leydig, that the imbibition and exudation must be, in great measure, the
result of endosmotic action, — not forgetting, however, the influence which is
necessarily exerted on the alternate movements in question by the action of
the respiratory apparatus to be presently described.

Leydig remarks that " the mingling of the sanguineous fluid with M'ater
from without seems, at first sight, extraordinary ; it is, however, a fact in
physiology, founded on direct observation, Van Beneden having detected it
in marine Mollusca, myself in Paludina vivlpara, and, more recently, Gegen-
baur in Eeteropoda and Pterojpocla." The nutritive or sanguineous fluid of
the Rotatoria is, as a rule, clear and colouiiess, but in some species it has a
red or yellowish hue, e. g. in Notommata centrura, Synchceta, and Pohjarthra ;
it is, moreover, usually destitute of distinct floating particles or elements :
exceptions occur in Eosphora Najas, EucUcmis, and a few others, in which
small clear corpuscles move about in it just as in the blood of Annelid'a. '< Such
genuine elements," continues Leydig, " of the cii-culating fluid must, however,
not be confounded vnth the minute particles wMch at times detach themselves
from the tissues within the body and float about in the liqidd. Such false
corpuscles are not uncommon in animals whicli have been partially crushed
or left dry by evaporation ; those noticed by Elirouberg in Hydaiimi scuta
were, in all probability, of this accidental kind."

Dr. Dobie has recorded an obsei-vation of seemingly genuine raoA-ing cor-
puscles, which deserves a place hero. He foimd, <' immediately below the
integument of Floscularia cornuta, groups and lines of veiy small granules
continually in a state of rapid molecular motion, in appearance exactly rcscm-
bhng the molecules in tlio cusps of Closterium. Besides the molecular, they
are subject to another motion ; for occasionally thoy move from one pai-t of

428

OENEEAX HISTOUT OP THE rNFUSOEIA,

tho surface to another, in currents not very distinct or persistent, and in no
definite dii-ection. He has seen them running in lines down the tail, and
collecting in groups. This flowing movement occurs chiefly during the con-
tractions and relaxations of the entire animal. He thinks it probable that
these granules are connected with the nutrition of the animal, and analogous
to the free floating corpuscles of the Tardigrada, described by M. Doyere."

In his recent paper (Miiller's Archiv, 1857, p. 404), Leydig notes that
"wten individuals of Hydatina senta have been plentifully fed with Euglena
viridis, the fluid (blood) which fills their abdominal cavity, contains numerous
clear globules, or blood- corpuscles, of a roundish form and unequal size. We
would rather compare these corpuscles to those seen in chyle during the
process of digestion, as more strictly homologous with them than with blood-
disks. Although no true vascular system is discoverable in the Rotatoria,
there is, nevertheless, a tubular apparatus readily seen in most animals of the
class (XXXYI. 6 « a, 9 m ; XXXVII. 29 d, 32 ef; XXXVIII. 5 d d, 25 ef,
2Q eil, 27 g). It has the form of an apparent band, extends upwards from
the cloaca, or near to it, on each side of the body ; and within this a cord or
vessel is visible, more or less coiled or convoluted in its course, from which
small vibrating organs, often pear-shaped, and likened by Ehrenberg to
vmtten notes of music, project towards the cavity of the body. These vessels
may possibly communicate by one or more transverse vessels running across
the neck of the animal ; whilst below, they end either in a vesicle endowed
with an active power of contractility or immediately in the cloaca itself.

Now it hajjpens that the mechanism of this organization, as well as its
functions and relations to the other parts of the body, have been so variously
described by different writers, that it is difficult to draw up any satisfactory
general account of it ; we shall therefore be compelled chiefly to confine
ourselves to the reproduction of the several statements as presented by their
aiithors respecting the side bands and the contractile vesicle. Ehrenberg
adopted the curious notion that they were parts of the sexual organization.
The side bands with their coUed canal he represented to be the testes, and
the contractile vesicle a sperm-sac (seminal vesicle). The inconsistency of
this notion with all our knowledge of animal structure and functions, has
stiTick every observer. To adduce but one coimterargument : — the constant
discharge of spermatic fluid in a profuse quantity, and in no relation with the
number of eggs contained within the ovary, is an idea which is per se at vari-
ance with all analogy, and directly opposed by the fact that the apparatus is
in fuU activity even when the embryo is still unhatched -within the body of
its parent, — and entirely negatived, at least in several instances, by the disco-
very of distinct male beings.

Again, Ehrenberg called the tremulous tags (XXXVIII. 26 e) giUs or giU-
like organs, and therein recognizes them as parts of a respiratoiy system. He
thus refers to them : — " Oval, tremulous bodies are in some species obsei'ved
attached to a free filament-like tube generally placed longitudinally within
the body ; in some instances they are attached to the two sexual glands (i. e.
the side bands), as in Hydatina. Their function is respii-atory, and they ai-c
analogous to gills ; the tremulous motion observable is that of the lamina)
composing them. The reception of water within the body for these giUs to
act upon, is provided for by one or more openings at tho anteiior part of the
body, or in some species by spur-lilve processes or tubes (siphons)."

The erroneous belief that the siphon-like antcnna3 (XXXVII. 17 d;
XXXVIII. 27 e) and the cuticidar fossaj were channels for tiie admission of
water into the body was countenanced by Sicbold, who explained tlic respi-
ratory act to consist in the entrance of water, by tho supposed apertures, from

OP THE ROTATOBIA.

429

without into tho general cavity of tho body, its percolation through " short
lateral vessels " (the oscillatory tags) into the winding canal of the lateral
band of each side, and its passage thence into the contractile vesicle, by which
it is pumped out through the cloaca. This process Siebold designated a water-
circulating system.

Mr. Dalrymple, in his excellent description of a supposed new Notommata
(the Asplanclina Brightwellii of Gosse), differs from Siebold in the account
of the respii-atory apparatus in several particulars. He says — " This pecu-
liar organ consists in a double series of transparent filaments (for there is no
proof of their being tubes or vessels), arranged, from above downwards, in
cui'ved or semicircular form, synametrical when viewed m fr-out (XXXVI.
6 a a). These filaments, above and below, are interlaced, loop-Uke, while
another fine filament passes in a straight line hke the chord of an arc, uniting
the two looped extremities. To this delicate filament are attached little tags
or appendices, whose fr'ce extremities are directed towards the interior of the
animal, and are effected by a tremulous, apparently spiral motion, lilie the
threads of a screw. This is undoubtedly due to cilia arranged round these
minute appendices. The tags are from eight to twelve, or even twenty, in
number, varying in different specimens (XXXVI. 6).

" I believe the organ in question to be a peculiar circulatory system. The
body of the animal is filled with fiuid, most probably analogous to blood,
while the cUiated tags, in perpetual motion, must produce currents in this
fluid, and probably in a uniform and determinate direction. In this way the
nutrient plasma wlU be brought regularly in contact with all parts of the
body, and the process of nutrition go on as in insects, without the interven-
tion of tubular vessels, — the dorsal heart in them serving only to give direc-
tion and circulation to the blood. I am the more impressed with this beHef,
since these filamentous organs are in close approximation with the large con-
tractile sac, which probably performs a respiratory function."

Moreover Mr. Dalrymple does not believe in any communication between
the sac and the apparatus furnished with the cihated tags, as Siebold supposes ;
on the contrary, he represents the sac to communicate directly with the ex-
terior. He writes — " This sac, spherical when distended, is placed just
above the ovisac, and communicates with the vaginal canal. It is ex-
ceedingly deUcate, and may be seen to contract, by the action of muscular
fibres, with great rapidity, in which act it is thi-own into numerous regular
folds or pouches, and in that condition appears not very dissimilar to tho

large ceUiilar limgs of Batrachia The explanation which I ventiu-e to give

is, that this sac draws in water and expels it again by the vaginal orifice •
and it is by bringing the blood, by means of the ciliaiy movements of the
tags, into immediate contact (the doUcate membranous wall of tho sac iu-
tei-vening) with the air of the water, that aeration or respii-ation is per-
formed. An analogous contractile sac may be seen in Rotifer vulgaris."

Lastly, tho author adds that ho is convinced, from repeated observation
that the contractile sac has no relation with the generative function and
that " the supposed vascular ramifications upon it are neither more nor less
than the muscular fibrLlla3 by which the contractions are effected."

Porty coincides with the explanation offered by Dahymplc, and reproduces
it m his work. Mr. Gosso presents, in his notice of Asplamhrm priodonta
the foUowmg description of the mechanism in question :— " On the upper
side of the oviduct sits a contractUe bladder, which, when full is perfectly
globular and small, being scarcely, if at aU, larger than tho two pancreatic
glands put together. Eound this, attached at or near its base, passes on each
.side a tortuous thread, apparentiy glandular, wliich goes up along each side

430

GENEBAL mSTOllY OF Till; INFUSOHTA..

of the ventnil region, and is attached to the head-mass behind the jaw-
cushion. The middle part of each thi-ead is wrinkled into a large plexus of
four or five pairs of doublings, laid with some regularity ; on this plexus are
placed four tremulous tags, dii-ected inwards, making eight in aU. None are
visible on any other part of the threads. The presence of these organs, as
weU as of the contractile bladder, in the female, shows that these are not con-
nected with impregnation.

From the above extract it appears that Mr. Grosse believes that the
" tortuous threads " of the apparatus have a glandular office ; and though he
so far countenances the hyiDothesis of Ehrenberg, nevertheless pronounces
against their sexual nature.

Dujardin expresses an opinion that the contractile vesicle is a respiratory
organ, and that the water freely penetrates into the interior of the body to
bathe the vibratile organs, as the variability of volume of the animals proves.

Leydig has very elaborately described the structiu-es in question, and their
several modifications. We feel justified in submitting an analysis of his
researches, even at the risk of some repetition : —

" The canal of the respiratory apparatus extends along each side of the body.
Generally there is a single canal on each side, much contorted in its course,
and forming actual coils or plexuses, e. g. in Steplianoceros, Brachioncea,
Lacinularia, Euchlanidota, and many Notommatce. Two canals, which
coalesce at either end, are seen in Notommata Myrmeleo, N. Sieboldii, N.
Syrinx, N. davulata, and N. Anglica. The canals have a thick cellular wall,
and their ca\ity is clear and well defined. They are not solid cords, as Perty
and others afiirm. The cellular walls may be much thickened, and contain,
besides the usual fine granular contents, many fat-particles, as seen in Ste-
plmnoceros, Notommata centrura, and in Lacinularia. In the first-named,
indeed, the deposit of fat is so great that the coils of the respiratory canal
near the head rather resemble a collection of fat-vesicles (XXXVII. 1 t). I
have not been able to discover any anastomoses between the canals of opposite
sides, as Huxley represents in Lacinularia."

In many Eotatoria, particularly in small species, such details of structure
escape our powers of observation, and the canals described are invisible, as, for
example, in Floscularia, Polyarthra, andAscomorpha; a more close and search-
ing inquiiy may, however, reveal them, particularly where the contractile sac
shows itself. Indeed, Perty has detected the tubes in Ascomorpha Helvetim.

" The vibratile or ciliated tags are processes of the respii-atory canal (XL.
5). They are constructed after two types, which do not concur in the same
animal, but are found as peculiarities of different genera. In one type the
process is of equal "width and cyUndi-ical throughout, as in Notommata
Myrmeleo (XXXVII. 29 e, 32 h) ; in the other, the extremities are dilated
and a trumpet-shaped figure assumed, as in Notommata centrura (XXXVIII.
26 e), Euchlanis triquetra, and in Eosphora Najas.

" In Lacinularia I have been unable to satisfy myseK if these processes of
the respiratory canal discharge themselves freely into tlie abdominal cavity.
Huxley states that they have bUnd extremities ; but I regard it as still an
open question, for in other species, for example in Notommata Sieboldii and
N. centrura, it can be most satisfactorily made out that they open freely into
the cavity of the body.

" VibratUe hairs (cilia) project from their free end and in the trumpet-
shaped processes ; the direction of the ciliary motion is evidently inward.

" The number of the vibratile organs varies much in different species :
usually there are but from 4 to 8 or 10, distributed at unequal distances along
the respiratory tube ; but in some animals, <». f/. in Notommata Cojyeu.i, N.

OF TOE ROTATORIA.

431

Syrinx, N. Sieboldii, N. Ancjlka, N. davulata, and in N. Myrmeleo, tho
number is greatly augmented, and from 30 to 50 tags may be counted. When
thus multiplied, they are for the most part appended to a clear canal of little
width and thickness, rather than to one with thick cellular walls. (The tags
are mostly more numerous on one side than on the other.)

" Tho posterior exti-emities of the respiratory canals either open at once
into the cloaca, as in TuUcolana, or more commonly expand to form the
contractile sac, the respii-atory vesicle (XXXVIII. 26 1).

" At the first appearance of the respiratoiy vesicle, it is of insignificant size,
and clearly a dilated state of the united ends of the two respiratory canals.
It is then little or not at aU contractile. This condition is illustrated in
Lacinularia and Steplianoceros. " It generally, however, exists as a consider-
able and actively contractile sac opening into the cloaca. Its walls are very
thin, and covered with a fine muscular network, discoverable in most species,
and imagined by Ehrenberg to be vascular. The openings of the respiratory
canals into this sac are readily perceived by a proper adjustment of the focus
of the microscope."

From this organization, Leydig concludes that a portion of the water sur-
rounding the animal enters by endosmosis, or possibly by minute orifices
hitherto unperceived, within the cavity of the body, and there mixes with
the nutritive juices, the analogue of the blood of higher beings. The simple
act of respiration is consequently limited to the imbibition and the intermix-
tui-e of fresh water with the blood. Further, it would appear that the waste
material is discharged tkrough the vibratile processes, which by their ciliated
appendages direct the fluid into the respiratory canals, from which it escapes
either first into the contractile sac, and thence into the cloaca, or at once into
the latter.

Here the question of a glandular, a renal fimction performed by the re-
spiratory tubes meets us ; but it will be more convenient to defer its consi-
deration until we have set forth the researches of Mr. Huxley, who diffei's in
not a few details from Leydig : — we must premise that they apply specially
to the Lacinularia socialis, to which, among other peculiarities, he assigns the
•absence of a contractile sac, although Leydig affirms a veiy small one to
exist.

Prof. Huxley acquaints us that the opinion of Oscar Schmidt is, " that the
ends of the water- vessels are closed, and that the vibrating body is within
them." And he goes on to say — " There is no contractile sac opening into
the cloaca as in other genera ; biit two very delicate vessels about i th of
an inch in diameter, clear and colouiiess, arise by a common origin upon tlio
dorsal side of the intestine. Whether they open into this, or have a distinct
external duct, I cannot say.

" The vessels separate ; and one inms up on each side of tho body towards
its oral side. Arrived at the level of tho phaiyngcal bulb, each vessel divides
into three branches : one passes over the pharynx and in front of the pha-
ryngeal bulb, and unites with its feUow of the opposite side, while tho other
two pass, one inwards and tho other outwards, in the space between the two
layers of the trochal disk, and there terminate as eroca. Besides these, there
sometimes seemed to be another branch just below tho paiacreatic sacs.'

"A vibratile body was contained in each of the ctecal branches ; and there
was one on each side in tho transverse connecting branch. Two or moro
were contained in each lateral main trunk, one opposite the pancreatic sacs
and one lower down, making in all five on eacli side. Each of these boclics
was a long cihum (j^th of an inch) attached by one extremity to the side
ot the vessel, and by the other vibrating with a quick undulatorj- motion in

432

GENERAL niSXOBY OF THE rNFUSORIA.

its cavity. As Siebold remarks, it gives rise to an appearance singularly like
that of a flickering flame.

"I particularly endeavoured to find any appearance of an opening near the
vibratile cUium, but never succeeded, and several times I thought I could
distinctly observe that no such aperture existed. Animals that have been
kept for some days ia a limited amount of Avatcr are especially fit for these
researches. They seem to become in a manner dropsical ; and the water-
vessels partake in the general dilatation.

" The band which accompanies the vessel appeared to me to consist merely
of contractile substance (connecting-tissue), and to serve as a mechanical
support to the vessel. It terminates above in a mass of sumlar substance
containing vacuola attached to the upper plate of the trochal disk."

This account differs from that of Leydig chiefly in the denial of the patent
condition of the free ends of the vibratile tags, and consequently of the en-
trance of the fluid from the cavity of the body through them into the lateral
vessel. It also casts doubt upon coUs of the water- vessel in the neck, and
upon the presence of a small non-contractile sac at the inferior termination
of the lateral vessels, whilst, on the other hand, it represents anastomosing
branches between the vessels of opposite sides in the neck. Mr. Huxle^^'s
description therefore appears rather to favour Mr. Dahymple's hypothesis
as to the contractile vesicle, whilst, with respect to the lateral canals, it is
suggestive of a glandular excretory function.

Dr. Carpenter adopts Prof. Huxley's description of the tags, and of the
inosculating vessels in the neck.

Cohn, in his account of Hydatina senta (ZeitscJir. f. Zool. 1855, p. 444),
describes two tubes as springiug from the thick-waUed, muscular contractile
sac, lying on the abdominal surface of the animal, immediately subjacent to
the skin, and communicating with the cloaca. These tubes are " respiratory
canals ; " they have a finely granular waU, and advance with more or fewer
cm-vatm-es and coUs towards the head, where they appear to end in straight,
blind, pointed ends or in loops, which attach themselves to the skin of the
rotary organ. The "tags," four on either side, affixed to the canal are
triangular in one aspect, and shortly cylindrical in another, and supported
on short pedicles, through which their cavity becomes continuous with, the
interior of the canals. The different figure of the tags from different points
of view has given rise to the error of their being of two sorts — cylindrical
and triangular. In Bracliionus militaris the contractile vesicle is remarkable
on account of its very large dimensions. It occupies as much as two-thirds
of the abdominal cavity, and is composed of two chambers, of which the
posterior is the larger. The diastole and systole of the two chambers are
alternate ; the posterior opens into the cloaca, through a small duct. That
there is a direct commimication betAveen the contractile sac and the cloaca,
Cohn decisively proved by mingling coloiuing matter in the water, and wit-
nessing a current inwai'ds duiing each dilatation, and one outwards on each
act of contraction, alternately — an experiment sufficiently conclusive of the
respiratoiy nature of the sac.

The mechanism under consideration appears, as Leydig also remarks, to be
occasionally absent — or perhaps only imperceptible. Dr. Dobie states that
in Floscularia " no trace of a vascular system can bo observed. The tremulous
giU-like organs found in some Kotifers are here absent." After his complete
examination of Melicerta ringens, Prof. Williamson says — " I have found no
special organs of circulation or respiration. . . .1 detect no vessels or pulsating
organs." Nevertheless a stmcture at least resembling the vibratile tags was
noticed in tins animal by Mr. Gosse, who states that between the gizzard

OT" THE ROTATOUr.V.

433

" and the base of the stomach there was one httle tremulous tag, of the same
structure as in Notommata aurita. Prom the same spot also project, into a
space of peculiar clearness, two trumpet-shaped bodies of the greatest delicacy,
and without motion." Prof. Wilhamson reminds us, in a note, that he has
described two tubes springing from a pyriform organ, apparently hoUow, and
located immediately below the stomach. Though he saw no pulsation in this
organ, it appeared to be the homologue of the contractile vesicle in other species.
He believes the two filamentous organs to be tubular, and suggests the possi-
bility of their supplying a spermatic secretion, though he is not able to affirm it
as a fact. He moreover observed the \'ibratile spermatozoon-Hke corpuscles
" in various parts of the body, where they are apparently enclosed within
hollow canals. I have never seen them occupying the two main trunks of
the water-vascular system, as caeca, nor can I succeed in tracing any con-
nexion between them ; " but it is probable that they were really located in
some of the branches of that system, as observed by Mr. Huxley in Lacinu->
la)'ia.

The glandular renal function of the lateral tubes and appendages has the
support of analogy among other lowly- organized forms allied to the Eotatoria ;
but such an hypothesis falls to the ground, if, as Leydig thinks, the urinary
concretions noticed and so named by him in embryo and young animals are
deposited within the cavity of the intestine, and not in the contractile sac.
However, naturalists generally will certainly not accept the doubtful disco-
very of the position and the interpretation of the nature of the particles
offered by Leydig as conclusive evidence of the nature of those structures,
but will, in the absence of direct and exact observation, be rather guided by
analogy. "We will therefore append some extracts, showing the comparative
physiology of the supposed respiratory mechanism.

Leydig writes — " There is the greatest similarity between it and the
organs in Lmihridnm and Hirudince, which are conceived to have a respira-
tory office. In these are similar contorted and coiled tubes, with a clear
canal opening either without an intermediate contractile sac, as in Clepsine,
or with one, as in Nephelis. Moreover, the canal opens by a wide ciliated
aperture into the cavity of the body ; and in this termination of the tubes I
recognize the homologue of the vibratile tags of the Eotatoria. Moreover
the direction of the ciliary motion in the ^nelida is inwards to the main
canal. In the Liombricince, Gegenbauer has attributed a renal function to
tlie otherwise-called respiratory canal."

Dr. Cai-penter describes a " water- vascular system " among all the vermi-
form members of the Articulata, and as represented in its simplest type in the
Rotifers. " Similar lateral vessels, often ramifying more minutely (especially
in the head and anterior part of the body), are found in many of that group of
vermiform animals clothed over the whole surface of their bodies with cilia to
which the designation Turbellaria has been given." This writer sunnises
that the water-vascular system may contain some other fluid than pure water
and, as Van Benedcn has suggested, may serve as a urinary apparatus.

Prof. Huxley presented the following philosophical summary of the com-
parative relations of the respii-atory mechanism of the Eotifer ; before the
British Association :— " In certain Distomata, such as Aspidogaster, there is
a system of vessels of essentially similar character with that in Rotifer ■ but
the principal canals, those lateral tnmks which come directly from "the con
tractile vesicle, present regular rhythmical contractions. The smaUer branchel
are all richly ciliated. In otlier Distomata the lateral trunks appear to be
converted into excretory organs, as they are full of minute granules • thev
remain emmently contractile ; but their connexion with the system of smaller

2 F

434

GENERAL HIBTORY OF THE INFUSOEIA.

ramified vessels ceases to be easy of demonstration. They still form one
system ; but the cilia are no longer to be found in the smaller ramified vessels.
In certain Nematoidea the vascular system is reduced to a couple of lateral
contractile vessels altogether devoid of cUia, but communicating with the
exterior by a small aperture, Nov?- in all these cases there is no doubt the
vascular system is, physiologically, a respiratory and perhaps a urinary system,
while the common cavity of the body represents the blood-vascular system of
the Mollusca and Articulata. If this system, then, be not at aU homologous
with the blood-vascular system of the higher Annulosa, it is so Avith the
traehete of Insecta."

"We may repeat here that the delicate and ciliated rotary organ must in
some measui-e subserve the purpose of respiration, after the manner of the
gills of a reptile or of a fish, by providing for the aeration of the liquids
contained witliin it through the agency of the constantly renewed contact of
fresh water flowing over its actively- vibratile surface.

OF THE NEKVOUS SYSTEM AND THE OEGANS OF SENSE ; PSYCHICAL

ENDOWMENTS.

a. Of the Nervous System, — The existence of a rudimentary nervous
system is now universally admitted ; but at the period when Dujardin wrote,
that talented observer felt that the state of knowledge respecting the Rota-
toria was not sufficiently precise to estabhsh the existence of nerves and of
nervous ganglions. His scepticism was, no doubt, increased by observing the
unphilosophical facility with which Ehrenberg described and represented
nerve-cords and ganglions according to preconceived notions and loose ana-
logies. Illustrations of Ehrenberg's supposed nervous apparatus, and of its
modifications of form in different animals, are to be found in his descriptions
of every family and genus. Thus in giving the characters of Ladmtlaria, he
says that " near the oesophagus is situated a nervous mass, the analogue of
a brain divided into four or six lobes ; also, as in Megahtrocha (XXXII. 374),
two ring-like and radiating masses with a row of ganglions lying beneath the
muscles of the ciliary wreath." In Melicerta, he speaks of a cur\-ed gland-
like band of nerve-matter ; in Enterojylea , which has no eyes, of a brain-Hke
knot, sending ofi" a thick tortuous nerve-cord along the dorsal siu-face to the
second transverse vessel, where the respii'atory opening probably exists ; of a
ganglion placed beneath the eye in twenty-six species of Notonvnata, wliich
in N. Copeus and N. centrura is three-lobed and seated above the maxillary
bulb, whilst in the remainder it consists of one or more nervous gangha
seated amidst the muscles of the ciliary apparatus ; and in Otoglcna, of an
oval cerebral ganglion with two dark appendages, a red eye, a long nerve-
loop in the neck, with a prolongation backward, a forked ventral nerve, and
two ear-shaped frontal protuberances bearing two visual points.

It would be useless to midtiply these references ; the general deduction
from the many descriptions of Elirenberg is, that there exists a cerebral or
brain ganglion, which supports the eyes, and by its extension encircles the
oesophagus like a loop, sending off nerve-cords in cveiy direction, and often
complicated by the presence of other nerve-ganglions about the head, neck,
and body. Moreover, the apparent reticulations frequently \asible below the
ciliary wreath, whicli he sometimes viewed as a vascidar network, he at
others spoke of as a nervous plexus.

The present prevailing o])inion is similar to the above, viz. that there exists
a brain or central neiTC-ganglion above the oesophagus, with outgoing nerve-
fibres, and sometimes accompanied by supplementary ganglia in otlicr regions.
Nevertheless the special descriptions of Elirenberg arc not accepted ; the

nv THE KOTATOKIA.

435

portions of tissue fixed on by him as nervous masses, receive in general an
entii-ely different intei-pretation. Thus in the case of Ladnularia the sup-
posed 4-6-lobed brain, with extondiag nerve-fibres, is set down as mere col-
lections of " vacuolar thickenings," with intercui-rent fibres of connective
tissue. The same intei-pretation is extended to the " nine paii's of ganglia,
with fine interlacing nerve fibres," in Notommata clavulata, and to the foui-
or five such in Diglena lacitstns ; yet in both these species, the central or
brain ganglion represented by Ehrcnberg is allowed to retain this character
by Leydig, who sets aside all the rest as mythical.

The following critique on Ehrenberg's views is from Prof. "Williamson : —
" The small organs so common amongst the Kotifera, {|,nd which Ehrenberg
regards as nervous ganglia, are abundant in the MeKcerta, but they afford no
countenance to the hypothesis of the great Prussian Professor (XXXVII.
17 k). They appear to be nothing more than small cells, or vesicles, formed
of granular viscid protoplasm, very similar to those into which the yelk of the
egg becomes divided. Sometimes they fioat freely in the fluid which distends
the integument and bathes the viscera ; at others, thin ductile threads pass
from one vesicle to another .... There is no uniformity in their an-angement
in different individuals. They differ as widely as possible in their size,
number, and distribution. So far fi'om being nervous vesicles, they appear
rather to be cells modified into a rudimentary form of areolar (connective)
tissue. That they are hoUow vesicles or ceUs, very viscous, readily cohering,
and, owing to this coherence, readily drawn out by the movements of the
various organs to which they are attached, are facts capable of easy demon-
stration."

A central nervous mass or brain, immediately subjacent to the eye-specks,
and above the oesophagus or pharynx, which sends off nerve-fibres in different
1 directions, isj as already intimated, generally admitted to exist. It is men-
! tioned by Siebold, Perty, Gosse, Dah-ymple, Leydig, Cohn, and others. The
j two first-named authors allude to it as a group of ganglions ; but Leydig
i affirms that, although it may be lobed, it is always a single and xmdivided
' organ. Some, again, have treated of it as forming a loop or ring around the
gullet ; but such a condition is denied by Leydig, who states that it only
I extends itself in the form of diverging nerves, which end by enlarged extre-
mities, and never form loops, such as Ehrenberg represented, around the
I tubular process or respiratory siphon.

This nervous centre or brain, supporting the eyes, is seen in the families
Hydatincea, Euchlanidota, and Brachioncea. Leydig, however, cannot admit
I the masses supposed to represent the cerebrum in the families (Ecistina, Mega-
lotrochcea, and Floscidaria, nor the pairs of nerve-like gangKons at the base
of the trochal disk of Stephanoceros, to have a cerebral character ; he supposes
them rather to be " coUs of the respiratory canal, or heaps of granules or
nuclei, such as are met with beneath the cuticle."

Prof. Huxley discovers the nervous centre under a peculiar and unusual
usual form in Ladnularia sodalis. To quote his words — " On the oral
side of the neck of the animal, or rather, upon the under surface of
the trochal disk, just where it joins the neck, and therefore behind and
below the mouth, there is a small hemispherical cavity (about -r-Vrth of
an inch in diameter), which seems to have a thickened waU, and is\'iclily
ciliated within. Below this sac, but in contact with it by its upper edo-e, is
a bilobed homogeneous mass (about -gi^th of an inch in diameter), resembling
in appearance the ganglion of Brachionus, and running iiito two prolongations
below ; but whether these were continued into cords, or not, I could not make
out,

2 F 2

(

\

,1

436

GENERAL HISTOllY OF THE INFUSORIA.

" I believe that tliis is, in fact, the true nervous centre, and that the sac-
in connexion Avith it is analogous to the ciliated pits on the sides of the head
of Nemertidce, to the ' ciliated sac ' of the Ascidians, which is similarly con-
nected with their nervous centre, and to the ciliated sac which forms the
olfactory organ of Amphioxus.

" Mr. Gosse has described a similar organ in Melicerta ringens ; and I have
had an oppoi-tunity of verifying his observations, with the exception of one
point. According to this observer, the cilia are continuous from the trochal
disk into the cup ; so far as I have observed, however — and I paid particular
attention to the point, — the cilia of the cup are wholly distinct from those of
the disk. The interesting obsei-vations of the same careful observer, upon the
architectural habits of Melicerta, would seem to throw a doubt upon the pro-
priety of asci'ibing to the organ in question any sensorial function. "But
however remarkable it may seem that an animal should build its house with
its nose, we must remember that a similar combination of functions is ob-
vious enough in the elephant."

Tliis last analogy is assuredly very far-fetched, and can sei-ve nothing in
the argument ; and to us it seems a much more reasonable supposition that
the homogeneous bilobed body below the ciliated cup is a gland, than that it
is a brain ; were it a brain, surely some nerve-fibres would be traceable from
it into the interior of the animal. Of this body Prof. Williamson says — " I
see no sufficient reason for assigning to the small organ nervous functions ;"
and he further remarks that " the ciliated sac or cup becomes so contracted when
the animal is not busy in constructing its case, as to be almost invisible," which
is another circumstance discountenancing Prof. Huxley's notion of its pur-
pose. Cohn has no doubt of the cerebral nature of the large semiglobular
mass, noticed also by Ehrenberg, in the head of Hydatina senta ; and he
records having frequently observed in its interior a large, transparent, circu-
lar vesicle or vacuole. A large number of nerves are given off from its an-
terior portion ; but from its posterior, two thick fibres proceed backwards and
outwards to the apparent ciliated opening on the sui-face of the back, and
constitute a cervical loop. There is, however, no actual opening, but merely
a ciliated fossa, which is probably a sentient organ. About the large cerebral
ganglion are other lobules, also probably nen'ous, from which fibres are given
off and possibly form a plexus between the alimentary tube and ovary, be-
sides supplying the muscles. Above the ciliated fossa named, is another de-
pression supplied with nerves ; and, according to Ehrenberg, a similar one
is present on the opjiosite side of the body.

Various accessory ganglions or nei-ve-centres have been represented by
authors at different parts of the body, mostly in relation with some of tlie
principal organs, this arrangement being suggested by the kno'ttTi nervous
system of other Invertebrata — for instance, the Mollusca, which have usually
a special ganglion for the nervous supply of each principal organ of the body.
Such a multiplication and disposition of ganglia, Oscar Schmidt endeavoured
to demonstrate in Bracliiomis urceolaris and in Hydatina senta. His inter-
pretation has, however, not been accepted by others, and, generally, the
characteristics of ganglions are so ill-defined, that the bodies considered to
be such by the observer are pronounced to be no other than vacuolar thick-
enings of connective or other dissimilar tissue by others.

Perty makes the statement that in Hydatina, Synchwta, and Diglena there
is a series of ganglions along the anterior surface of the abdomen, with con-
necting nerve-fibres between them and the brain. A nen-ous system of this
sort belongs to the higher Crustacea ; but although many have sought it in
the Ttotatoria, Perty is the only observer who has affirmed its existence in any.

OP THE ROTATOIUA.

437

Mr. Dali-ymple mentions the presence, in his Notomvuita anylka, of a small
ganglion sending off nei-ves to the stomach, salivary glands, and ovaiy ; but
Leydig looks upon this structm-e as no more than the cells and fibres of con-
nective tissue, and states that " similar clear cells, of various size, having
delicate elongated branches, ai-e seen in Notommata centrura, N. Myrmeleo,
N. clavulata, and in Digleim lacustris. The delicate branches, or threads,
extend between the epidermis and the viscera of the body, and were described
by Ehrenberg to be nerves, but are actually the means of retaining the vis-
cera in situ," — a conclusion supporting that of Prof. Williamson.

There is, however, one set of nerves recognized by most observers, which
proced from the cerebral ganglion to the surface of the body, ending at the
bottom of the epidermic pits described above (p. 40!^), from which stiff cilia or
bristles project, or, otherwise, running to the extremity of the protuberances
and antenna-like processes, which are also armed vsdth bristles. Dalrymple
noticed nei-ves so distributed in iVbio?nmato anglica ; and Leydig has indicated
the like in many species. The supply of a nerve to the so-called siphon or

Irespii-atory tube imparts to it the character of an antenna, tactile organ, or
feeler. The evident delicate band or cord seen within the tubular process of
Melicerta is indeed called by Mr. Williamson a muscular band ; yet at least
some portion of it must be esteemed a nerve-cord, if the organ in question
really possesses tactile powers.

A similar distribution of nerves is witnessed in the Tui'beUaria, and, as
Leydig says, among the Phyllopoda and Arthropoda.

Nervous substance has its origin in simple cells, which in ganglia retain
their cellular character, but in nerves appear to be elongated as tubes, — the
• cell- wall constituting the nerve-sheath or the neurilemma — the cell-contents
(the contained nerve-tissue) existing as a fine moleculai' matter. In nerve-
masses or gangUons the original nuclei remain, and the several constituent
j cells are aggregated and held together by diffused connective tissue. Some
j peculiar structures, supposed to stand in especial relation to the nervous
! system, are described by Leydig. We cannot do better than follow his
account in an abstract.

Immediately above or about the brain-ganghon, in many genera, a sac is
observable filled with a whitish substance, called by Ehrenberg the " chalk-
sac " (Kalkbeutel). Leydig confesses that he has hitherto been unable to
determine whether this sac is in immediate connexion with the brain, or in-
dependent of it. In Notommata centrura (XXXVIII. 26 t) it appeal's as a
process or lobe of the brain ; but in another species, N. aurita, the sac is so
elongated as to form a thin stem filled vsdth the chalk-like matter, wliich it
seems to discharge by an opening on the head. This organ would' therefore
seem to partake of the natm-e of a gland. Beside the genera named, this sac
is seen in Notommata tripus, in N. collaris, and in N. tardigrada ; also, if the
black speck noticed by Perty be the same structure, in N. roseola. Ehrenber"
refers to its existence in Diylena, Megalotrocha, and Brachionus ; but in the
last-named genus Leydig has failed to discover it.

The vesicular space or sac is, in several instances, not single ; but two
three, or four are noticeable. Thus in Megalotrocha Ehrenberg mentions four
.opaque, white, spherical bodies at the base of the rotary organ.

Another sac, distinct fi-om the foregoing, is seen in Eucldanis and Notom-
mata centrura, lying in the median line close above the brain, and dischargins
itself by a duct passing forwards to the cuticle. It contains no chalky matter
but 18 translucent trnd composed of clear cells. The peculiar and considerable
organ which Leydig met with in Stephanoceros, placed in advance of the sto
raach, and consisting of a group of hyaUne vesicles with a dischai-ging orifice

438

GENEHAL HISXOKY OF THE INFUSORIA,

on the neck, its obsei-ver is inclined to refer to the same categoiy with the
problematical structm-es of Euchlanis and Notommata centrura. He more-
over seeks to establish an affinity between these organs and the small clear
space surmounted by a ring on the cnticle, situated in the middle line of the
body, behind the frontal speck in Phyllopoda, such as Branchipus ; but even
if this affinity be admitted, no light is thrown upon the functions of these
questionable structures.

b. Organs of Sense. — The existence of some of the senses is to be in-
ferred from that of a nervous system. The sense of touch is one concerning
which there can be no question ; that of taste, in its natui-e allied to the
tactile sensibility, is very doubtful, whilst those of smelling and hearing may
be pretty safely stated to be entirely absent. Lastly, the sense of sight
is generally admitted to exist, and to have special organs, or eyes, for its
exercise.

Touch may be supposed to be diffused as common sensibility over the
entire surface of the body, and especially developed in the soft tissue of the
rotary organ, in its processes and antennae, and in the soft processes and
termination of the pseudopodium. Something approaching a sense of taste
has been imagined present, particularly in the antennae or feelers. If the
faculty of hearing seems occasionally exercised, we must attribute the cir-
cumstance in part to the perception of the distiu'bing cause by vision, and in
part to the vibrations produced in the hquid.

The visual organs (XXXYIII. 16-19, 33) have claimed particular atten-
tion, and now have their existence in the majority of Rotatoria, at some pe-
riod of their life, satisfactorily proved. Dujardin, dissatisfied with Ehrenberg's
hasty generalizations, and compelled to deny the visual character of the co-
loured specks in various Protozoa and Phytozoa, looked, no doubt, with greater
scepticism upon the Berlin Professor's representations of eyes in Rotatoria
than he otherwise wotdd have done, and started some objections against them.
He says — " I will not deny a certain analogy between the red s])ecks and the
coloured points observed in Cycloj)idce, and which may be called eyes ; but I
cannot assign to such specks a very high importance, seeing that they con-
stantly disappear in the adult condition of many Rotifera, and otherwise show
themselves more distinctly, according to the degree of development as deter-
mined by the season and the place of development." It should be noted,
however, in reply to this objection, that a similar disappearance, on the at-
tainment of the adult state, occiu'S in the parasitic Crustacea, the visual cha-
racter of whose eye-specks or oceUi is not questioned. Moreover, although
some coloiired specks in the Rotifera are imdoubtedly mere heaps of granules,
yet others have assuredly a definite optical organization and function. These
possess a refracting medium, the essential part of an eye ; and theu* organ-
ization, though simple and imperfect, yet elevates them to the rank of eyes,
eyelets, or oceUi.

Ehrenberg gave much attention to the position, number, and other pecii-
liaritics of the eye-specks of Rotatoria, as he emploj-cd them largely in
framing liis classification. Unfortimatcly, however, he did not acquaint him-
self sufficiently with their minute structure, but was content to call all the
coloured specks he met A\nth eyes, and insisted on unimportant and inconstant
particulars as generic and specific characteristics. These en-ors have conse-
quently much vitiated his classification (see chapter on Classification) ; and
the tendency at the present day is to assign to the coloured eye-spots an al-
together secondary rank among the characteristics of Rotatoria.

Ehrenberg described the eye-specks as variously situated, on the fore part
of the head (forehead) or on the neck, as mostly sessile (i. e. situated imme-

OF THE UOXATOIUA.

439

diately on the part), and rarely pedunculate (i. e. supported on a pedicle or
stem), as in OtoyUna. In some species, as in Rotifer, the eyes are placed
on a protrusile part of the head, and consequently appear at one time in ad-
vance of the head, and at another far backward -vvitliin the body. In Monura,
Ehi-enberg states they are moveable. The number of eye-spots varies con-
siderably : in several genera there is but one, e. g. Furcularia, Monocerca,
Notommata, and Brachionus ; but two eyes are more common, as in Melicerta
(XXXVII. 15), Lacinulana, MegalotrocJm (XXXII. 376), Rotifer (XXXV.
476-478), and Diqlena ; thi-ee eye-specks occur in Asplanclma, Triojjhthal-
miis (XXXin. 4i2-414), Eospliora, and Otoglena ; four in Squamella ; and
from six to twelve coloured spots and upwards are met with in Oydoglena and
Thcorus (XXSIV. 425-429), but their visual character is more than doubt-
ful. These last " conglomerate eyes," as Ehrenberg calls them, appear to
be no other than collections of coloirred (it may be oil) particles, and are
akin to the lai'ge coloui'ed spaces seen on Notommata forcipata and Synchceta
Baltica, having neither a definite nor a regular outline (see p. 440). Subse-
quent research has proved Ehrenberg in error respecting the number of eyes
in several species, — an error which seriously affects his classification.

The ordinary colour of the eye-specks is red, but sometimes it is reddish-
brown, and rarely violet or black. The colour may change in the lifetime of
the individual, as from red in the young to black in the adult state. In a
few instances no eye-specks are visible.

Except some of the doubtful collections of coloured specks, the eye-spots are
placed immediately above the great ganglion of the head, the homologue of the
brain, or, as Siebold affirms, are united with it by intermediate nerve-fibres.
The intimate stinicture of the eyes was ill-understood by the great Prussian
Professor. He was unable to convince himself of the existence of a cry-
stalline lens and of a cornea. Thus, in his account of Rotifer vulgaris, he
states that the eyes consist of several cells fiUed with a granular pigment,
and sometimes they separate abnormally into several portions. He thinks
there is no crystalline lens, although they are probably compound, Kke the
eyes of insects.

Siebold insisted on the coloured specks of Kotatoria being sharply defined,
and in many cases, at least, furnished with a capsule, in contradistinction to
the ill-defined vanishing pigment-masses imagined to be eyes in the Protozoa.
Wagner also speaks of a lens in the eyes of Lacinularia. Perty is adverse
to the notion of a lens or cornea, or of a capsule ; yet in Pteroclina Patina
he notes that the eUiptical eye-specif, viewed on the side and from below is
seen to consist of an upper red and an under white half. That the latter
represents a refi-acting medium is highly probable. A compoimd stnictiire
is further indicated by Perty in Scandium longicaudum, in which he perceived
" a mass of smaU granules resembling a gland, in the midst of the red pig-
ment-corpuscles, which are outspread irregularly, and paler at the circum-
ference. Moreover, in Euchlanis triquetra there is an irregular brown scale
with reddish-brown contents, whilst in E. Luna the unusually large eye-spot
appears to be made up of ten to twelve distinct red granules.

Leydig arranges the single eye-specks imder three types :— 1. an ordinary
pigmcnt-spot, of a rounded or irregular outline, a reddish-brown, black or
\iolet colour, not sharjily defined, e. g. in Notommata Synchoita ; ' 2 a de-
fined, sharply-bounded speck, actuaUy composed of two coalesced hemi-
spherical portions, such is seen in Brachionus ; 3. a speck having a clear
refracting body projecting from the mass of pigment— a structure discovered
by Leycbg in Euchlanis unisetata (XXXVIII. 19). The first type is the mo^t
prevalent. ^

440

genehal histohy of the infusohia.

Leydig next proceeds to show that the single eye-specks, appearing only
as an accumulation of pigment- granules, are precisely homologous structures
■with the reputed eyes of Cyclops and Daphnia among the Entomostraca, and
of Argulus, Artemia, and Branchi'pus among the PhyUopoda. In neither the
one nor the other does a lens, cornea, or capsule exist, although in a few (for
instance, in Notommata Myrmeleo) a glistening white substance is intermixed
The single eye-spot of Brachionus, with its coalesced central segments, has
its counterpart in the eye of the larva of Cyclops, and an evident analogy
with that of Cyclopsina, as also with that of Caligus, in both which a refract-
ing lens makes its appearance, it is likewise similar in general conformation.

Who then, asks Leydig, can advance any direct arguments against the
hypothesis that, by the medium of the pigment-granules in immediate con-
tiguity with the nerve-ceUs of the brain, without a refracting body, a percep-
tion of light is possible ? That the Rotatoria, on the contrary, may possess,
equally with the Crustacea, a refracting medium, is illustrated by the example
of Euchlanis unisetata. With reference to those species having two eyes, Leydig
has convinced himself of the presence of a lens in both in Pterodina, Ste-
phanops, Metopidia, Rotifer citnnus, and in R. macrurus ; and he thinks he has
seen one in the eyes of the young of Tiibicolaria, Melicerta, and Stephanoceros,
although the soft state of the pai'ts and theii- indistinct outHne render the
observation less certain. In the last-cited animals, when any trace of the
eye-pigment remains, none whatever of the crystalline lens is visible. Of
the other binocidar Eotatoria, not mentioned, Leydig's opinion is, that ana-
logy intimates the existence of a refracting medium, and their nature as true
eyes. The presence of a special homy skin or a particular capsule sur-
rounding the pigment is doubtful ; for the cuticle probably performs the office
of a cornea.

Of the many-eyed Eotatoria, Leydig has particularly examined Eosphora
and Theorus. He finds Ehrenberg in eiTor respecting Eosphora, which, in fact,
possesses a single eye-speck above the brain ; and what that naturalist took
to be two clear eye-points on the frontal margin are merely intensely orange-
or yeUow-coloured spaces, which are at once seen to be without any affinity
with the other eye-specks. The eyes of Theories are nothing more than oil-
drops within the stomach-glands. Ehrenberg, moreover, describes colourless
eyes, the visual nature of which may well be doubted. Although he has no
direct observation, Leydig believes that in Squamella the pigment is composed
of numerous portions disposed around a crystalline lens, and that the animal
may consequently be called many-eyed.

The conclusions ai'rived at by Leydig are, " that the single-eyed species of
Rotatoria have, many of them, a refracting body in their eye-specks, which
are therefore true simple eyes, but that in most cases a lens is wanting, and
the specks are merely rudimentary eyes ; wliilst in those Avith two eye spots,
each of them is, by the presence of a lens, an actual simple eye."

Ehrenberg stated that eye-specks were entirely absent in several genera :
such were the doubtful Rotatoria Ftygura and Ichthydium, also Chcetonotus,
Cyphonautes, Tubicolaria, Enteroplca, Hydatina, Plcurotrocha, LepadeUn,
Hydrias, Typhlina, and Noteus. With reference to Tubicolaria, Leydig
shows that in the young state this genus has two eye-specks ; of the other
' exceptional forms, several have been insufficiently examined to found any cer-
tain statements upon.

The curious fact of the disappearance of the eye-spots in several Rotatoria
has been already referred to. Examples occm- in the genera Melicerta, Laci-
nularia, Floscularia, Tubicolaria, and Mcgalotrocha.

c. The Psychical Endowments of Rotatoria are probably of the nature of id-

OF THE KOTATOltlA.

441

stinct ; some so supposed are simply acts dictated by external circumstances,
Perty intimates that the apparent sinking after one another, the gamboling
among themselves, and the fact of their depositing thcii- eggs in chosen and ap-
propriate localities, to which, after an absence, they will retui-n, are pheno-
mena evidencing perception, design, and a sense of company. This last imagined
sense Avas one suggested by Ehrenberg, who afiirmed that he had observed it
in the case of Philodina roseola, which, when kept in glasses, deposited its
eggs in heaps, the parent remaining a long time with the young ones pro-
duced from them, and so constituting a sort of family or colony, — an act
dictated, as he sm-mised, by a sense of company or family.

The occasionally-observed rejection, and ejection, of what may be deemed
disagreeable or unsuitable nutriment, are acts which some might interpret to
be indicative of volition, and, in some degree, of pain or unpleasant impression ;
but they are quite explicable without reference to a sentient nerve-centre, or
to high psychical endowments. The same thing may be said of other reputed
evidences of the existence of psychical or mental faculties.

Of the Eepeodttctive Oegaits aijd Development of Rotatoeia. — The
Rotatoria were for a long time assumed to be hermaphrodite or monoecious,
e. that each individual possessed a perfect male and female reproductive
apparatus, by which ova"' are formed, and fructified without the presence or
contact of any other individual. There has never been any difficulty in
determining the female generative organs, which are very clear and well
defined ; but the greatest diversity of opinion has subsisted respecting the
coexistence of male and female organs in the same individual.

Dujardin attempted no explanation of this matter, whilst Siebold candidly
affirmed that in the absence of any precise knowledge as to the male organs,
it is impossible to say whether the Rotatoria are monoecious, or have the sexes
separate — are dioecious.

The clearing up of this questio vexata, in several at least of the Rotatoria,
is due to our countiyraan Mr. BrightweU of Norwich, who demonstrated the
existence of distinct male animals, and figured them (XII. 65, 66) in his
' Faima Infusoria.' This discovery was further carried out by Mr. Dal-
rymple, and has subsequently been extended by Mr. Gosse, Leydig, and
' others. Inasmuch, however, as the monoecious or hermaphrodite condition
is very prevalent among the lower Invertebrata ; as the males of the majority
of the Rotatoria have as yet escaped detection ; and as there are parts dis-
cernible in several of them presenting some similarity with recognized male
organs in other animals, not a few eminent obsei-vers still incline to the
belief that, at least in a portion of this class, the sexual organization is of the
monoecious type. These doubtful organs will be discussed after the weU-
1 determined female apparatus, and the male animals, have been described.

Female Repeoduotive Oegans. — These were pretty accimitely determined
by Ehrenberg, who noticed a single or double ovary, an oviduct, an ovisac
( and a vaginal sheath or outlet leading to the cloaca or the rectum. '

The ovary, in which the ova or eggs are generated, lies immediately beneath
\ or behind the alimentary canal, between it and the contractile sac (XXXVIII.
: 26 0, p ; XXXVII. 1 e, 19 7t, 32 c) ; its anterior border often advances as far
1 forward as the maxillary (oesophageal) head. Oftentimes its position is rather
I transverse, and it lies across the intestine, or is curved to some extent around
1 it. It varies in size, but is always a very large organ, and occupies a consider-
: able space in the interior of the body. It also presents much diversity of
I figure, being sometimes round, oblong, or oval, at others flattened, elongated
1 reniform, bilobed, homed, or curved like a horse-shoe. It is enveloped by
I a delicate membrane, rendered very obvious by the action of acetic acid

442

GENERAL THSTOTIY OF THE INl'USOEIA.

(XXXVII. 220), which contracts the substance of the ovarj', and throws the
membrane into sharp folds. This membrane may likewise be detected with-
out the assistance of chemical reagents, where it is contracted below into an
outlet or duct opening in the cloaca. It forms a pellucid membranous bag,
which may be ruptiu-ed by pressure, giving exit to its viscid contents ; and
Leydig assorts that the wall of the ovary is contractile, as the addition of
alcohol demonstrates.

The substance of the ovaiy is called the ' stroma ' or protoplasm ; it has a
finely-granular appearance and a viscid consistence. It is usually of a milky
or a light-grey colour, and has interspersed in it, besides granules, numerous
clear bodies of a vesicular appearance (XXXVII. 1 e ; XXXVII. 7), but
which, Leydig says, are really homogeneous. Williamson counted between
20 and 30 in the ovary of Melicerta, varying in diameter from ^ .^o^^
yyL_th of an inch (XXXVII. 22). These, by development, constitute the ova
or eggs, and may be termed rudirnentaiy ova. Within each a finely-molecular,
more or less opaque, and rounded body is perceptible (the nucletis), surrounded
by a clear, transparent ring, apparently filled with fluid (the germinal vesicle)
(XXVII. 6, 7). "These are," writes Huxley, "the germinal vesicles and
spots of the futiu'e ova. Acetic acid, in contracting the pale substance, groups
it round these vesicles, without, however, breaking it up into separate masses.
It renders the nuclei more evident." This author further remarks, " the
pale clear space is sometimes seen to be limited by a distinct membrane." The
measurements of the nuclei in Melicerta are, according to Williamson, from
■^Jjj-jjth to j-jnnj^^ m.(-h in diameter. Within each nucleus are usually

from one to three clear spots — the nucleoli. The nucleolus, as imderstood by
Williamson, corresponds with the nucleus in the preceding description, whilst
this last term is applied by Huxley to the entire genninal body or rudi-
mentary ovum.

FoEMATioK OP Ova, their Extritston, and Development. — After fructifi-
cation, and preparatory to their transition into ova, the geiToinal spaces undergo
various changes in constitution and appearance. The germinal vesicle en-
larges, its nucleus disappears, and the ovum is indicated only by an ill-defined
transparent spot, which may, by pressiu'e, be isolated as " a small spherical
ceU. about ^ ^^^^th of an inch in diameter, having very thin pellucid walls,
and scarcely any visible cell-contents " (Williamson). Consentaneously with
these movements in the germinal space, the construction of the ovum pro-
ceeds by the attraction and separation of a portion of the surroimding proto-
plasm forming a yelk. The portion so appropriated is jDarticularly rich in
granules which have previously congregated in the ovaiy, and now attracted,
it may be supposed, by the active vital action set up in the nidimentary
ovum. This abimdance of granules produces a deeper colour and an increased
opacity in this portion of the ovaiy ; so that when, as Prof. Williamson re-
mai-ks in the instance of Melicerta, this process of development proceeds in
the centre of the ovary, the latter organ appears divided by the incipient ovum
into an upper and a lower half.

The consequence of these several changes is that the resultant ovum is of
considerable size (XXXVII. 170) and stands prominently outward from the
general surfiice of the ovaiy, acquiring at the same time an independent
character by the production of a limiting membrane about the vitellus or
yelk, called the ^dtelline or vitellary membrane. Huxley, indeed, docs not
regard this as a distinct and specially produced covering, but as derived from
a portion of the enclosing membrane of the ovaiy, pinched off from the rest.

Prof. Williamson enters into a comparison of the development of the ova
of Melicerta vf\i\i that of the higher Mammalia, to show the close relationship

OF THE EOTATOKIA.

443

that subsists between them diuing this process. We have not space to follow
out this piece of comparative physiology in the words of the author, but can
only state his conclusions : viz. that the elements which are contained in and
solely occupy the o%dsac of the Melicerta, are those which, in the ovaries of
the higher Mammalia, are restricted to the interiors of the Graafian vesicles ;
that, whilst in the former the protoplasmic stock forms one undivided mass
from which portions are successively pinched oif to form the ova, in the latter
(the Mammalia) it is divided into small portions, each being contained within
a special receptacle or Graafian vesicle, the interspaces being occupied by the
stroma or tissue of the ovary.

It is in the yelk-matter, derived from the protoplasm, that the red tint
noticed by Ehi-enberg and others occurs ; the colour depends on red element-
ary granules, and on highly refractive oU-like particles, Mr. Gosse suggests
that " possibly the colouring matter of these reservoirs may be resolved into
the red pigment of the eyes, and the yellow of the jaw-cushion and other
parts ; " such a destiny we deem scarcely probable. Moreover the appear-
ance of oil-molecules often refracting a red colour, about parts in which active
development is proceeding, is a fact very generally observed. A red hxxe of
the ova is seen in Philodina roseola, Brachiomcs ruhens, Mastigocerca carinata
and Folyarthra ; in Notommata Sieholdii, Asplancha, Anurcea curvicornis,
Synchceta jpectinata, and in Lacinularia socialis. Leydig believes that in
many forms, e. g. Brachionus, Noteus, and Euchlanis, one portion of the ovary
produces almost exclusively the yelk, and has in consequence a darker colour
than the other part, which developes the germinal spaces. This phenomenon
has, he remarks, its analogue in various Crustaceans — the Hexapoda and
Asellina. It may be here stated, however, that the darker portion of the
ovary has assigned to it, by other naturalists, the ofiice of preparing the
winter ova, presently described, rather than the yelk, as supposed by Leydig.
The preceding account, indeed, applies particularly to the production of the
ordinary ova ; the early history of the winter ova referred to wiU be given in
the account of development.

The Ova. — ^The Eotatoria develope two varieties of eggs, called re-
spectively " summer " and " winter " ova, besides male eggs. Much difference
obtains between them, especially in their developments, contents, and later
history. The summer eggs have thin, smooth, firm, and elastic shells, so
transparent that the course of the changes proceeding within may be watched
throughout. In figure they are ellipsoid, oval, or ovoid (XXXVII. 5, 6, 8, 9).
They are laid by the animals during the whole course of the summer, and' are
forthwith hatched. The winter ova, on the contraiy, are cliicfly produced in
the autumn, and are destined to remain in an inactive or torpid state durin<>'
the winter. They are generally of larger dimensions, often irregular in form*^
from inequality of the two sides, or from prominences or depressions of the
surfaces (XXXIX. 20), and opaque on account of their dark granular con-
tents and of their double shell (XXXVII. 21, 22, 24). Caustic potash
renders the shells clearer and more transparent, and causes some of the
inequalities of theii- surface to decrease. Huxley says that the tough elastic
membrane or shell is soluble in both hot nitric acid and caustic potassa
IJotween the tAvo shells is an interspace, more roomy, at the opposite ends of
the egg. The inner shell is thin and delicate, and immediately envelopes
the yelk enclosed in its vitelline mcmlirane. The external one is thicker
fii-mcr, and usually of a brownisli-yollow colour. Its surface is mostly
roughened, or tubcrculatcd, striated, or tlirown into ridges, areolatcd ceUular
or divided into facets, beset with longer or sliorter hairs and bristles, and occa '
sionally with spines, Examplee) of such modifications of the sm-face occur in

444

GENERAL UISTOKY OF TDE INrUSOKIA.

Anurcea Testudo, A. serrulata, Notommata Suboldu, N. Mynndeo, Melicerta
ringens, Ascomor^ha Oermanica, Lacinularia socialis, Scaridium longicaudurm,
Hydatina senta, Anurcea valga, &c. Ehrenberg was not prepared to admit
the existence on ova of actual hairy processes, but supposed them to be the
hair-like filaments of Hygrocrocis, or of other Algae. This supposition may
in some cases be correct ; for ova, like other bodies in the water, may become
the nidus for the growth of various microscopic plants and animals. That
some ova, however, are actually hairy is evidenced by theii- visible occurrence
in that state even whilst still within the abdomen of the parent ; as may be
seen in the ova of Hydatina senta, of Notommata Parasitus, &c. Both Avinter
and summer ova may often be met with in the same animal (XXXIX. 16) —
the one kind perhaps still in the ovary, the other on the point of expulsion ;
or, it may be, both sorts may be canied about attached to the posterior part
of the parent animal. This last occurrence is noticed by Leydig in Brachionus
Balceri.

These two varieties of ova were recognized by Ehrenberg, who assigned
them the names applied to them. Mr. Huxley suggests, instead of the term
' winter ova,' the appellation, ' ephippial ' ova, to indicate their analogy with
the similar eggs of Daphnia and other Entomostraca.

When recounting the propagation of Notommata Sieboldii, Leydig remarks
that male and female ova are not developed together in the same animal.
This fact has been extended by Cohn to apply to the whole family of Eota-
toria. According to him the ephippial are always distinguishable by their
external characters from the common summer ova, particularly by their much
smaller dimensions. They have thin, transparent shells, and ai-e chiefly pro-
duced at those seasons when ' ephippial ' ova are generated. Theii- develop-
ment follows the same coui'se as that of the ' summer ' ova ; but they are pro-
duced in very much smaller numbers, — a circumstance that affords another
reason for the paucity of males compared with females, whenever a collection
of Rotatoria is examined.

When the development of summer ova in the ovary has proceeded to the
point we have mentioned, and the egg is already become a distinct body from
the general substance of the ovaiy (XXXVIT. 2d), it is slowly moved down-
wards towards the passage or oviduct (XXXVII. 2/), which ends in the
cloaca (XXXVII. 32 d) ; and it is in this part of its course that the shell
becomes perfected. In the majority of the Rotatoria the ova are at this stage
extruded, the further phases of development proceeding externally to the
animal ; in others they are detained in their passage until the embryo is
more fully elaborated, or even until it is perfect and released from its sheU.

The size of the ova prior to expulsion XXXVII. 32 d ; XXXVIII. 26^)
is very extraordinaiy, so much so that a single ovum wUl sometimes occupy
the larger portion of the interior of the animal. The completed egg of Me-
Ikxrta has an average length, says Williamson, of -j-^th of an inch, and a
diameter of ^iij-th. The eggs of some Hydatince are -jr^th, of Lacimdaria
^j-^th of an inch and upwards in diameter.

* In several Rotatoria, two or more ova become agglutinated together near
the tei-mination of the oviduct, or in the cloaca, and ai-e expelled together en
masse, and still remain adherent to the parent, close to the cloacal outlet at
the base of the tail. This is exempUficd in Triarthra (XXXVIII. 30 d), Po-
lyarthra (XXXIII. 400, 401), Anurcea (XXXV. 496; XXXIX. 16), and
Noteus.

The oviduct, or ptissagc from tlic ovary to the cloaca, is a membranous tube
fomed by a prolongation of the tunic of the ovaiy. It is always extremely
dilatable ; and sometimes an egg is so long detained in its lower part, that it

OF THE BOTATOKIA.

445

seems to serve the purpose of a uterus, and has received the name of ovisac.
The orifice of this oviduct or ovisac into the cloaca is called the " vaginal
orifice;" the vaginal sheath, spoken of by Ehrenberg, would appear to be
either the tei-mination of the oviduct or sometimes the cloaca itself. The
oviduct may occasionally be deficient. Prof. Huxley states that he could
discover no such passage in Lacinularia.

The egg, having descended into the cloaca, is expelled thence by means of
a strong contraction of the whole body, and, in the act of escaping, involves
the eversion of the cloaca. The time occupied in the formation of the sum-
mer egg, from its first appearance as a vesicular space in the ovary to its
completion and extrusion, is very brief, generally only a few hours.

We have noted the discharge of several eggs adherent together, and their
subsequent attachment at the anal outlet. In other Eotatoria, likewise, ova
expelled singly attach themselves at the posterior extremity of the body,
singly or united together by a gelatinous matter, and not uncommonly at-
tached by evident cords or pedicles to the parent. This is seen in Megalo-
trocha, in Brachionus rubens, and in B. Pala.

In the species last named, as many as ten may often be seen in a group
near the cloacal orifice. In AscomorpJia, some six may be found adherent.
In Polyarthra (XXXVIII. 30), not more than one egg is found attached at the
same time. Thus the eggs are carried about by the parent one after another,
arriving at maturity and escaping from its shell. The like phenomenon is seen
in various Entomostraca, and in Polynoe, Exogona, and other Vermes, which
likewise produce both summer and winter ova. Among the urceolate Eo-
tifers, the eggs escape into the case or gelatinous investment, and there pro-
ceed to their vdtimate development, safe from many obnoxious influences and
from destruction by other animals.

Development of the Embeyo. — The following changes transpire pre-
paratory to the construction of the embryo. The nucleus is seen to elongate,
and then to present a constriction aboiit its middle (XXXVII. 5) ; the yelk
at the same time shows a similar constriction, which continues to deepen in
correspondence with that of the nucleus, until at length there are two seg-
ments, each with its contained nucleus — the result of the fission of the primary
one. Leydig states that this division is not into two equal portions, but that
a segment is cut off from one end or pole (XXXVII. 2 6), and that in the
continued segmentation which ensues, this same unequal fission is again
and again repeated. However this may be, the act of division goes on
(XXXVII. 8) until at length the whole yelk is broken up into a mass of
minute cells, and its opacity increased by the number of molecules they con-
tain (XXXVII. 2 c, g). Out of this mass, the tissues and organs of the em-
bryo are developed, appearing in their characteristic forms without any or
otherwise very slight, transitional phases (XXXVII, 2e,d; XXXVIII 9)
It is characteristic also of Rotatoria, in common with all the Vermes "that
the embryo is generated from the entire yelk, and not, as in Crastacea and
still liigher animals, from an accessoiy body supci^iosed upon the yellc into
which the yelk is gradually taken up. Dr. Carpenter remarks that the mode
of development is in all essential respects the same as that of the Nematoid
Entozoa, each group of coUs evohang some one principal organ.

The order of succession of the parts of the embryo in the egg is thus de
scribed by Ehrenberg in the instance of the Megalotrocha albo-favicans •—
" A turbid central spot appears, which becomes the oesophageal bulb and
teeth ; a blackish granular oval body is also seen posteriorly • the eves era
dually become red, and a motion of the cOia of the head is visible ■ after some
hours the wliole foetus, which is folded up, turns itself round, the shell bursts

446

GENEHAL HISTOHY OF THE INTOSOHIA.

and tho young animal creeps out." In a specimen of Brachionus Bakeri the
first thing Mr. Brightwell detected was a motion like that of the ihuscular
oesophagus of the parent.

The best account we have of the subject is that given by Prof. "Williamson
of the Melicerta ringens : — " The first trace," he says, " of future organiza-
tion which presents itself, appears in the form of a few freely moving cilia
.... at two points, one of which corresponds with the future head, the other
near the centre of the ovum .... with the cavity of the stomach ; shortly
after .... traces of the central parts of the dental apparatus present them-
selves, this, again, being soon succeeded by the union of the entire mass of
yoUc-ceUs, and the foi-mation from them of the various organs of the animal.
The cilia now play very freely, especially at the head. The creature twists itself
about in its shell ; two red spots appear near the head, which Ehrenberg re-
gards as organs of vision, and along Avith them a very dark-brown and some-
what larger spot is developed in the integument near the lower stomach.
The young animal now bursts its shell ; . . . . and although its external ap-
pendages (XXXYII. 15), and especially the rotatory organs are imperfectly
developed or unexpanded, yet the whole of its internal organization, though
but obscurely seen, is nevertheless that of the perfect animal, and not that of
the larval state."

In the embryo animal, whilst within the egg (XXXVII. 2 h), as well as
for a short time after its escape (XXXYII. 3, 4 b), Leydig finds in most Ho-
tatoria the collection of black or dark-brown particles close upon the cloaca
(XXXVIII. 7, 8, 9), which has been described in the section on Secretion,
as a supposed mass of urinary concretions.

The period occupied in the development of the embryo differs in different
species. Ehrenberg stated that in Hydatina senta, eleven hours after the
deposition of a complete ovum, vibration of the anterior cilia was visible, and
in 24 hours the young being escaped from its shell. Mr. BrightweU, in his
notice of Brachionus BaJceri, states that " about 2 o'clock the animal was ob-
served with one egg placed externally between the two posterior spines of
the shell, and another small egg in the left side of the animal, which increased
much in size in the coui'se of the day ; at 9 in the evening a motion was per-
ceived in the exterior egg Uke that of the muscular oesophagus of the parent ;
and about this time the internal egg was protruded and placed by the side of
the other, being longer than it. At 11 the yoimg Brachionus burst with a
boimd from the egg in which the motion was perceived, and afiixed itself by
its tail."

The egg-sheU splits open, longitudinally or transversely, to give exit to the
young animal. This seems brought about by the active movements of the
embryo itself, which sometimes bursts (as BrightweU says) with a bound or
spring from its prison. Where the eggs have been attached, the empty fissured
shell continues stiU adherent for a time, until by the movements of the parent,
or by some accident, it is detached.

The variation among different Eotatoria in the stage of development in
which the ovum is found when it quits the ovary, or when it is expelled from
the body, has been afrcady remarked ; but adchtional illustrations arc desira-
ble. In the greater number, the egg is laid just before or very soon after
the process of segmentation of the yelk commences ; for example, in Meli-
certa, Lacinularia, and Brachionus. In many genera the ovum continues in
the oviduct, the ovisac, or the cloaca, or otlierwisc remains v\itliin the ovaiy
itself until the embryo is complete and even free. Examples of this are foimd
in Stephanoceros, Actinurus, in Rotifer, and xa Notommata Syrin,r, N. Si£-
holdii, and in Asplanchna. . In Rotifer, Ehrenberg remarks that, in the ova-

OF IHE BOTATOllIA.

447

rium, foiu' or live ova sometimes so completely develope themselves, that tlie
young creep out of theii- envelopes, in wliich they were coiled up in a spiral
manner, extend themselves, and piit their wheels into motion while within
it ; and they sometimes occupy two-thirds of the bulk of the parent. So
Mr. Gosse tells us that in Asplanchna " the ovum produces the living young
in the ovisac, which, when matui-ed, occupies the whole lower part of the
parent." The occurrence of embryos free within the saccular ovaiy of Ste-
phanoceros (and still more, if as some have thought, they detected them loose
in the general cavity of the body) forms another bond of affinity between this
aberrant genus of Eotatoria and the Bryozoa. Where the young in general
quit the parent in a free, and so far perfect form as to be able to lead at
.once an independent existence, the animals may be said to be viviparous
(producers of living young). This viviparousness (viviparity) is still more
pronounced in some Philodincea and in Alhertia, in which the formation of
an actual egg-shell seems to be omitted, and the developed embryo to be at
once liberated within the sac of the ovary, where it may be seen in active
movement.

The Embeto Metamoephosis. — It has already been remarked, generally,
that the embiyo on emerging from the egg has all the characters of its class,
and is complete in its internal organization ; that any dissimilarity between
the new-born and the adult animal is due, not to the absence of parts or
organs, but to their lesser growth and their imperfect expansion or evolution.
In other words, the Rotatoria undergo no positive metamorphosis ; they pass
through no intermediate phases of existence, no laiwal form resembling that
of any Protozoa, in advancing from the embryonic to the complete and per-»
feet condition.

Leydig does not partake this opinion, but thinlcs that a metamorphosis is
exhibited in the course of development of most or aU Rotatoria, certainly not
complete, but still sufficient to advance it as a phenomenon of the class. He
specially adduces the instance of the embryo of Stephanoceros, as the most
striking proof (XXXVII. 3, 4), and he adds that, if the representation by
Ehrenberg of the young of Triarthra lotigiseta be correct, the fact of a meta-
morphosis must be recognized also in that genus. Again, he notes the great
difference between the newly-bom and the adult animals in several genera,
e. (J. in Tuhicolaria and Melicerta, where the cUiary wreath is stUl veiy
simple, and the absence of the tentacles (antennce) sufficiently notable
(XXXVII. 15) to render the subsequent 'modifications an act of metamor-
phosis. Moreover, the disappearance of the bunch of cilia in the young state
at the end of the pseudopodium, and HlceAvise that of the coloured eye-specks
in many genera, when the adult condition is attained, are also indications of
the same phenomenon.

The advocacy of this opinion was especially incumbent upon Leydig, in
order to furnish an additional argument in favour of the affinity of the Rota-
toria with the Crustacea. But even were the e\-idenccs of mctamoi-phosis
among the Rotifora as complete as he rejircsonts, they would serve his pur-
pose, of demonstrating the affinity he advocates, but Httle, seeing that the
immature Rotatoria have no real resemblance to the larval Crustaceans with
their three pairs of jointed feet. Cohn (Siebold's Zdtschr. 18.55, p. 481) has
discussed this question, and surmises that tlie peculiar embryo of SfepJiano-
ceros, which Leydig cites as the strongest instance of an act of metamor-
phosis, IS a male being (XXXVII. 3). As to the other supposed instances
Cohn (Usprovcs its occurrence in Brachwnus, and considers tlic disappearance
of the eye-spock m Tuhicolaria and Melicerta too tri\-ial a circumstance to
urge in its support.

448

GENKRAL HISTORY OF THE INFUSORIA.

Perty seems struck by the considerable variations in form between many
embryo and adult Rotatoria, and enunciates the opinion that many supposed
perfect forms are no other than embryonic conditions, — for example, Gleno-
phora Troclius, Monocerca valga, Notommata Fells, and Cycloglena elegans.
We do not understand whether he believes in a metamorphosis, or if he
■would simply state that Ehrenberg unnecessaiily multipHed genera and spe-
cies by describing immature beings as distinct foi-ms. If the latter be all
that Perty intends, we entirely concur with him.

It is necessaiy to detail the form and structure of some embryo Rotifera,
to illustrate the preceding statements. The embryo of Stephanoceros
(XXXVII. 3, 4) is thus described by Leydig : — " It has in general a vermi-
cular figure. The head, which supports the eyes, is separated from the trunk
by a well-marked constriction, and is famished with long ciHa. The head
and cilia are retractile. The red specks {two in number) appear actually to
be of the nature of eyes ; they have a sharp outline and are slightly concave
in front, as if a refracting body was there seated. Within the abdominal
cavity behind the head, a peculiar striation is observable, the purpose of
which I cannot imagine ; further backward is a clear space in which long
cilia are seen in activity, and which indicates the cavity of the alimentary
canal. Moreover, the maxillary apparatus, and the special vesicle containing
the inorganic particles (urinary concretions) are perceptible. The termina-
tion of the body bears some delicate vibratile ciHa." Beyond this phase of
development, the embryo does not advance in the egg, but after being hatched,
it would seem to assume another intermediate form before arriving at the
adult state. Leydig found, in water containing Stephaiioceros, a young
animal still possessing in some measm-e the previous vermiform figure and
apparent articulation of the trunk and foot, and a proboscis-like head with
four projecting arms. The eye-specks were still present. Prom the trunk-
like process of the head, two considerable tubular appendages were out-
stretched, ciliated at the extremities : the cUia on the end of the foot-process
had disappeared, but were very evident in the abdomen, near to the sac con-
taining the inorganic particles. The mandibular apparatus had the regular
structure. He frequently encountered also another variety, which, together
with the figure of the perfect animal, had five arms, but was without any
apparent sexual organs, while the foot-process and the whole body were
strewn with numerous fat-globules.

We will now continue the description (see p. 446), by Prof. WUliamson, of
the embryo of Melicerta after escaping the egg-sheU. He writes — " The
young Melicerta stretches itself out, and, everting the anterior part of its
body, unfolds several smaU projecting mammiUse covered with large cilia, by
means of which it floats freely away (XXXVII. 15, 16). These mammillae
are in this stage not unlike those of Notommata clavulata, but they soon en-
large and become developed into the flabeUifoi-m wheel organs of the mature
animals. The dental apparatus is now fully developed ; the alimentary canal
and muscular fasciculi are all present, — only the epithelial cells of the former
have not as yet obtained their yellow granular contents ; consequently the
viscera exhibit the same hyaline aspect as the rest of the organism. The two
red specks are imbedded in two of the mammUlffi. After swimming about
for some time like other free Rotifera, the animal imdergoes further changes.
The dark-brown spot is tlie first to disappear ; and soon after, the two pink
ones cease to be visible. Tlie animal attaches itself by the tail to some fixed
support, and developes from the skin of the posterior portion of its body a
thin hyaline cylinder, the dilated extremity of which is attached to the sup-
porting object. The formation of the case is now begun ; tlie first-fonncd

OF THE EOTATOEIA,

449

spheroidal or tentaculai' pai'ticles ai'O arranged in a ling ronnd the middle of
the body, and appear to have some internal connexion with the thin mem-
branous cylinder. At fii-st, new additions are made to both extremities of
the enlai'ging ling ; but the jerking contractions of the animal at length force
the caudal end of the cylinder down upon the leaf, to which it becomes se-
curely cemented by the same viscous secretion as causes the little spheres to
cohere. AU the new additions are now made to the free extremity, which,
as Elu-enberg remarks, never extends beyond the level of the cloacal aper-
ture of the outstretched animal. In the new-bom being, therefore, the parts,
as in the adult, are all present ; they only require to be expanded by the
ordinary process of growth."

- Mr. Grosse's account of a newly-hatched Melicerta implies a greater aber-
ration of form than that narrated by Prof. Williamson. He states that
" its form is trumpet-shaped Kke that of Stentor, with a wreath of cilia
around the head, interrupted at two opposite points. The central portion of
the head rises into a low cone." After various movements and gp^ations for
an hoiu', the yoimg animal settled itself, and the form of the adult became
manifest : " the foiu' petals of the disk were well made out, though the sinu-
osities were yet shallow ; the antennae at fii'st were only small square nipples,
but soon shot out into the usual fonn ; the ciliated chin was distinct, as was
also the whirling of the pellet-cup immediately beneath it."

We are indebted to Mr. Huxley for an elaborate description of the young
of Lacinularia socialis (XXXVII. 10, 11). " The youngest foetuses," he
writes, " are about Jjjth of an inch in length. The head is abruptly trun-
cated, and separated by a constriction from the body ; a sudden narrowing
separates the other extremity of the body from the peduncle, which is ex-
ceedingly short and provided with a ciliated cavity, a sort of sucker, at its
extremity. The head is nearly cii-cular seen from above, and presents a central
protuberance, in which the two eye-spots are situated. The margins of this
protuberance are provided with long ciHa ; it will become the upper circlet
of cilia in the adult. The margin of the head projects beyond this, and is
fringed with a circlet of shorter cilia in the adult. The internal organs are
perceived with difficulty ; but the three divisions of the alimentary canal,
which is as yet straight and terminates in a transparent cloaca, may be
readily made out. The water-vascular canals cannot be seen ; but their prp-
senee is indicated by the movement of their contained cilia here and there,

" In young Lacinulance ^th of an inch in length, the head has become
triangular ; the peduncle is much elongated, and it gradually takes on the
perfect form. The young had pre-\dously crept about in the gelatinous in-
vestment of the parents ; they now begin to " swarm," uniting together by
their caudal extremities, and are readily pressed out as imited free swim-
ming colonies, resembling in tliis state the genus Gonochilus.-'

Mr. BrightweU gives the appended brief accoimt of the Brachionus Bakeri
on its escape from the egg :— "At first it had the appearance of an oblono-
ball ; by degrees the anterior part spread, and the wheel processes were de-
veloped. Soon after, the posterior sheU (lorica) processes were visible in a
semilunar shape, with the poiiits nearly touching each other, which gradually
expanded." °

These examples are sufficient to iUustrate the general character of embrvo
Rotatona and thcu- progressive assumption of the adult fom • thev more
over furnish evidence of the doctrine that there is no metamorphosis or
transformation, m the proper sense of the word-no change but what is ex'nli-
cable by the ordinary laws of growth, or progressive expansion or evolution
Ehrenberg has announced it as a fact (Monafsh. cl Bcvl. Ahid. 1853, p 532)

450

GENERAL HISTOBT OF THE DfFUSOKlA.

that Rotifera found at great altitudes among snow do not attain a complete
development, but retain, as he expresses it, an ovate contracted figure within
an egg-like envelope or capsule, thi'ough which food reaches them hy a
funnel-shaped canal. All the functions of life he represents to go on a-s
usual under these peculiar conditions of existence, including the deposition and
hatching of eggs. This account reads like a description of an encysting-
process in the first degree — that, viz., for self-defence and presei-vation —
such as is illustrated in the formation of an open sheath around Stentor, as
stated by Cohn (see p. 284).

Contents and Development of Winteb. Ova. — The contents of " winter "
widely differ fi.-om those of " summer " ova. Mi-. Gosse gives the following
account of those of Melicerta ringens. He writes — " Opening one or two
cases (urceoh), I find one and another very curious egg-like bodies, not sym-
metrical in shape, being much more gibbous on one side than the opposite,
and measuring y-^th by -g^th of an inch. Each was encircled by five or
six raised ribs running parallel to each other longitudinally, somewhat Hke
the varices of a wentle-trap : viewed perpendicularly to the ribs, the form
is symmetrical — a long narrow oval. The whole surface between the ribs
appeared pimctured or granulate, and the colour was a dull- brownish yellow.
Under pressure it was raptured, and discharged an infinity of atoms, of an
excessive minuteness, but every one of which for a few seconds displayed
spontaneous motion. Their whole appearance, and the manner in which
they presently turned to motionless disks, were exactly the same as the
spermatozoa which the male eggs of other Rotifera contain, except that
these were so minute."

Mr. Dalrymple describes similar peculiar ova in Notommata {Asplanchna)
to consist of an aggregation of cells and of pigment-graniiles, without a dis-
tinguishable germinal vesicle.

The most complete and satisfactory account of the stracture and develop-
ment of the winter ova is supplied by Prof. Huxley in his History of Luci-
nularia (T. M. S. 1852, vol. i.); we will, however, preface it by Leydig's
description. We leani from this writer that in winter ova, a space filled
with fluid usually intervenes between the yeUc at each pole or end of the
egg, and the inner shell, as in Tuhicolaria, and that, according to Weisse's
observation of Brachionus urceolaris, the outer shell, when the embryo is
ready to come forth, springs open in a valvular or a lid-like manner. The
central portion of the yelk has a darker and more granular appearance, and
is siirrounded by a clearer perijiheral or cortical lamina, as in Brachiomts
BaJceri, Notommata Myrmeleo, and N. cmtrura. Intermingled with the yelk-
molecules are numerous clear vesicles, and oftentimes fat-particles ; moreover,
the yelk oi Notommata Sieholdii has a yellowish -red coloui- (XXXVII. 27, 28).
These " lasting ova," as Ehrenberg has otherwise named them, ai-e always
developed externally to the animal. Like the summer eggs, they are fre-
quently carried about by the parent ; it would not seem, however, that they
ever accumulate in groups about the cloaca, but that mostly the egg is
solitary, and that two or three arc of rare occurrence. Tims in Brachionus
BaJceri and in Ascomorpha never more than one is present, in Brachionus
ruhens a couple are occasionally noticed, and in Notomimta Sieholdii the
highest number seen was thi'co.

Concerning the changes ensuing on development, Leydig states that, " on
the formation of a membrane around the commencing ovum in the ovary,
the peripheral portion of the yelli exhibits numerous clear spots, wliich recall
the appearance of the small cells originating from repeated fission of the
yelk of the summer ova. From this we may conclude, either that the germi-

Oy THE ROXATOIUA.

451

nal vesicle may, by repeated fission, resolve itself into numerous clear vesicles,
without any further change, except that of an attendant grouping of the yelk-
particles about the products from the germinal vesicle, or that perhaps the
winter eggs, at their origin in the ovary, enclose a number of nuclei (germinal
vesicles) unlike other ova, which never commence with more than one nucleus
(germinal vesicle). If," continues Leydig, I rightly understand Huxley,
this is the manner of development of the winter eggs of Lacinularia socialis ;
and the bisection into two equal halves, which I formerly referred to fission,
has, according to this writer, no relation to it."

Eespecting this description. Prof. Huxley remarks that he thinks Leydig
" has not observed the genesis of the ephippial ova with sufficient care, and
he thence interprets their stnicture by supposing that they are ordinarily
fecuudated ova, which have undergone a peculiar method of cleavage ;" and
having quoted the opinion of other naturalists, he goes on to say — " it will be
observed that all these authors consider the winter or ephippial ova and the
ordinary ova to be essentially identical, only that the former have an outer
case. The truth is, that they are essentially different structiires. The true
ova are single cells which have undergone a special development ; the ephip-
pial ova are aggregations of cells (in fact, larger or smaller portions — some-
times the whole of the ovary) which become enveloped in a shell and simulate
true ova.

" In a fully-gi'own Lacinularia which has produced ova, the ovary or a
large portion of it begins to assume a blackish tint (XXXVII. 22) : the cells,
with their nuclei, undergo no change ; but a deposit of strongly- refracting
elementary granules takes place in the pale connecting substance. Every
transition may be traced, from deep-black portions to unaltered spots of the
ovarium ; and pressure always renders the cells, with their nuclei, visible
among the granules. The investing membrane of the ovary becomes sepa-
rated from the dark mass, so as to leave a space (XXXVTI. 24) ; and the
outer surface of the mass invests itself with a thick reddish membrane, which
is tough, elastic, and reticulated from the presence of many minute apertui-es.
This membrane is soluble in both hot nitric acid and caustic potassa.

" The nuclei and ceUs, or rather the clear spaces indicating them, are still
visible upon pressure, and may be readily seen by bursting the outer coat.

" By degrees the ephippial ovum becomes lighter, imtil at last its colour is
reddish -brown, like that of the ordinary ova ; but its contents are now seen to
be divided into two masses, hemispherical from mutual contact (XXXVII
21). If this body be now crushed, it will be found that an inner, structure-
less membrane exists within the fenestrated membrane, and sends a partition
inwards, at the line of demarcation of the two masses. The contents are
precisely the same as before, viz. nuclei and elementary granules. This
indeed, may be seen through the shell without crushing the case.

" I was unable to trace the development of these epliippial ova any further.
Those of Notommata, it appears, lasted for some months without change (Dal-
rymple). °

"It is remarkable that in Lacinularia these bodies eventually, like the
ephippium oi Daphnia, contain two ovum-like masses ; and there can, I think
be littie doubt that the former, like the latter, are subservient to reproduction'

"There are two kinds of reproductive bodies in Lacinularia :— 1. Bodies
which resemble true ova in their origin and subsequent development and
which possess only a single viteUary membrane. 2. Bodies half as large again
as the foregomg, which resemble the ephippium of Daphnia, like it havine
altogether three investments, and which do not resemble true ova either in
their ongin or subsequent development; which, therefore, probably do not

2 G 2

452

GENERAL niSTORY OF THE INFUSORIA.

require fecundation, and are thence to be considered as a mode of asexual
reproduction."

The multicellular chai-aeter of the contents of these ' ephippial ' ova, Cohn
is unable to confirm. In his very valuable essay on the " Development of
Rotatoria " (Zeitschr. 1855), this able observer has promulgated the hypothesis
of the occurrence of the phenomenon of " alternation of generations," of par-
thenogenesis or virgin-development. A resume of the reasons for this view
may stand thus : — Female Eotifera lay eggs of only one sex ; and winter eggs
are produced only by certain females and at certain periods — contemporane-
ously, that is, with the generation of males : again, the males are too few to
impregnate the whole of the apparent female beings, which are so largely
found, and always replete with ova in course of development, at all seasons.
The conclusion, therefore, forces itself upon us that the common " summer "
ova are produced within the parent animal without any antecedent genera-
tive act or impregnation ; that is, in other words, they are asexual products or
germs. If this be true, it follows that the beings producing them are not
true females, but merely asexual nurses (Ammen), furnished with a germinal
mass, but destitute of a real ovary, and not demanding the action of the male
for the development of its germinal elements. On the other hand, the
"winter" must be considered the trae ova, and the beings producing them
the only true females, furnished with an ovary, to which the energy of
the spermatozoa of the male is necessary. But, notwithstanding these phy-
siological differences, the mere nurses and the actual female Rotifera are in-
distinguishable in structure. In illustration of this hypothesis, its analogy
with what occurs in Aphis, Daphnia, and Artemia, may be quoted.

Of the rate of development of these winter eggs, we know little. Huxley's
account would render it a final act, involving the sacrifice of a large, or even
of the largest, part of the ovary, and consequently one which we cannot sup-
pose capable of frequent repetition. Leydig has, indeed, an observation which,
if acciu-ate, proves a rapid reproduction of such ova by the ovary. He
informs us he observed an isolated individual of Notoimnata Myrmeho lay
the solitary bristle-shelled winter ovum which its oviduct contained about
12 o'clock ia the day ; and on renewing his researches at 3 in the afternoon,
discovered another such egg completely formed in the ovaiy.

This author recounts also, ia his history of Notommata Sieholdii, the following
particulars, which, if confirmed, would prove the formation, whether of winter
or of summer ova, to be determinable by accidental external cii'cumstances :
— " "Wlien I kept the Notommata for some days in clear water containing no
nutiiment, the ovary shrivelled, the granular mass (yelk) altogether vanished,
the germinal vesicles became simple bodies, and all such individuals produced
only winter eggs."

That the Rotatoria, on the approach of winter, are likely to be placed under
conditions in which food is scarce, and which are imfavourable to ngorous
Ufe, is at once admissible, and, if Leydig's observation be correct, fimiishes
an explanation of the generally apparent limitation of the production of
winter ova to that season. Be this as it may, the -winter ova miist be re-
garded as inchoating the conservative tendency of natiu-c in pro^-iding for the
continuance of the species by organisms so constracted as to endure the
severity of the winter season, and to retain a dormant vitality tlirough it,
until the genial influence of spiing awakens them into activity and hfe.

Fecundity of Rotatoria. — Although the Rotatoria are not endowed with
the various faculties of reproduction possessed by the Protozoa, yet their vast
increase by eggs only is astonishing. Elirenberg wrote that he insulated
a single specimen of HyfJatina senta. and kept it in n separate vessel for

or THE UOTAl'OBIA.

453

eighteen days, that dui'ing this interval it laid four eggs per day, and that
the young of these, at two days old, lay a like number. Erom these data he
made an erroneous calculation, that one million individuals may be obtained
from one specimen in ten days, that on the eleventh day this brood would
amoimt to four millions, and on the twelfth day to sixteen millions.

This is the only dii-ect observation we have met with intended to prove
the remarkable fertility of the class, yet, throughout the history of the
Kotifera now detailed, numerous incidental illustrations of the fact occur, —
for example, the presence of several ova in different parts of the sexual
apparatus, ia various stages of development, and the observed rapidity of the
phases of development, at least of summer ova.

The latter contiuue to be formed and deposited thi'oughout the whole of
the warm part of the year ; and when this draws to its close, the production
of the winter ova provides for the continuous propagation of the species.

Ehrenberg, in his specific descriptions, notes the number of ova he met
with at the time of obseiwation, intimating that some animals bring forward
but one egg at a time, others two or several.

There is, very probably, a difference in the productiveness of various species ;
but differences in this respect will also occur from accidental and external
circumstances, such as abundance of food, and changes of temperatiu'e.

MALE EOTATOBIA AND MAIE HBPH0DT7CTIVE OEGANS. ftlTESTION OF MALE
A^^D FEMALE OEGANS THE SAME INDIVIDTIAIS.

Male Rotatoria. — Few male Eotatoria have as yet been determined. Those
decisively made out are those of Asplanchna Briglitwellii {Notommata anglica,
Dahymple), Asplanchna priodonta and A. Boivesii (Gosse), and the Notommata
Sieboldii (Leydig). This able German observer argues also that Enteroplea
Hydatina is the male of Hydatina senta, Notommata gj^anularis that of N.
Brachionus, and Diglena granidaris that of Diglena catellina. Since this was
written, Cohn has pursued the inquiry, and confirmed Leydig's conjecture,
that Enteroplea Hydatina (Ehr.) is the male of Hydatina senta. He has
moreover discovered the males of two other species, viz. of Brachionus urceo-
laris and Br. militaris. Still more recently, Leydig has been able to confirm
his belief of Enteroplea Hydatina being the male of Hydatina senta (Midlei-'s
Archiv, 1857, p. 404) ; and Cohn has discovered the males of Eucldanis dilatata
and Notommata Parasitus (Zeitschr. 1858, p. 284). Meanwhile Mr. Gosse
had discovered the male animals and theii' eggs in the undermentioned genera
and species: — Brachionus Pala, B. ruhens, B. amphiceros, B. BaJceri, B. angu-
laiis, B. Dorcas, B. Midleri, Sacculus viridis, Polyarthra platyptera, Synchaita
tremula (?), and in aU probability Melicerta ringens, besides the three species
of Asj)lanchna pre\iously detemiined {Phil. Trans. 185G).

The first male discovered was that of Asplanchna Brightivellii, then sup-
posed to be a species of Notommata, and is thus described by Mr. Brightwell
{A. N. U. 1848, ii. p. 155) :— It is " about half the size of the female, and
differa from it in form, being much shorter and of a rude triangular shape.
It is more difficult to detect than the female, being exceedingly transparent'
and, from the emptiness of the body, appearing little more than a transparent
ciliated bubble. It is very active, and occasionally puffs out the sides of its
body, so as entirely to alter its form, and remains thus distended some time
Kiere was no inchcation of any digestive apparatus, or of matters in course
of digestion.

" At the bottom of the body, on one side, is a conspicuous round sperm-
vessel or testis, m wluch, under a high power, spermatozoa in active vil^r-i
tUe motion may be seen, and at its external side a duct, closed by distinct

454

GENERAL HISTORY OF THE INFUSORIA.

lateral muscles. Connected with the testis is a well-defined intromittent
organ, and a conspicuous passage or opening for its extension from the body
of the animal. In the opposite lower angle are three small, irregularly-
formed, kidney-shaped bodies, connected with an angular lobe or muscle
lying beneath them. The male is also furnished with the delicate mem-
branous plicated bag, and rudiments of the curled tubular structure, found
in the female."

Besides determining the dioecious character of this Rotifer, Mr. BrightweU
was also enabled to repeatedly verify the occurrence of an actual coitus occur-
ring between the sexes, and enduring the greater part of a minute.

The male of the allied species Asplanchna priodonta was described by Mr.
Gosse. As the description supplies additional particulars concerning the
organization, we extract it entire.

Having isolated an adult female, in which the developing young seemed
different from the ordinary embiyos, he at length had the satisfaction of
seeing two males born. " Another was produced the same evening from
another parent, likewise under my eye."

" The length of these specimens (XXXVI. 7, 8) (male) was YToth. of an
inch (that of the females was -jL-th to -^nd of an inch). They had a general
agreement in outline with the female. But the outlet corresponding to the
vagina was at the very bottom of the ventral side (XXXYI. 7, 8 6), which
ran down to a point, while the dorsal side was rounded off. At the base of
this tube was a globular sperm-sac, with a short thick penis in front, the
whole nearly sui-rounded by a delicate glandular mass. The place of the
stomach was occupied by a long sac, having a slender neck originating from the
fore part of the head mass, and at the bottom broadly attached to the sperm-bag.
This whole organ was filled with minute granular matter, except three or four
clear globular bladders ; the sperm-bag showed a structure very similar.

" The principal muscles agreed with those of the female. The tortuous
threads, and their plexuses, were represented by two thickened glandular
bodies, extending fi-om the head mass to the foliaceous substance surroimding
the sperm bag .... The three eyes ' were present, situated as in the female,
but no trace of jaws was discernible, even on pressure, nor any crop, nor
true stomach. These animals were very active, swimming rapidly about, and
scarcely still an instant. On one or two occasions, I observed one of the
males with a slender process protruded to a considerable length fi-om the
sexual orifice, and adhering to the glass by its tip, moving round on it as on
a pivot."

Leydig admits the bisexual or dioecious nature of the Rotatoria as a general
fact ; and although, he says, his studies have been diverted fi-om special re-
searches on this matter, yet, from the descriptions and representations of
others, he believes he can detect several male forms aiTanged in the class as
distinct species.

Of the male of a new species, which he calls Notommaia Sieboldii, but
which is equally a member of the genus Asplanchna with " the supposed new
Notommata " of Brightwell, ho has given an elaborate description and draw-
ings. He remarks that in all details of organization it agrees with Mr.
Dalrymple's account, but, unlike the English species, differs considerably in
figure from the female, especially by the presence of four pointed arms
(XXXYII. 29). He remarks that " the so-called " spei-m-hag of Dalrymplc
is the testicle, and what that author terms the " penis " is its duct. The
figures he gives of the seminal corpuscles arc not altogether distinct, although
the resemblance between them and those of Notommatn Sieholdii arc immis-
takcablc. However, I must point out an error into which Daliymple has

OF THE KOTATORIA.

455

fallen, in describing the linear seminal corpuscles that lie parallel to one
another about the outlet of the seminal vesicle to be bundles of muscular
fibres attached to the base of the penis, and acting as " ejaculatores seminis."

The Enteroplea Hydatina (Ehr.) is, in Leydig's opinion, the male of Hydatina
senta : the reasons for this beHef briefly are, that, according to Ehrenberg's de-
scription and figures, the Enteroplea has neither jaws nor teeth ; that its
ovary is homogeneous and granular ; that the animal is always smaller than
Hydatina senta ; and that among the eggs of this last-named species, those
developing into embryo Enteroplea were intermixed. Now each and all these
differential, and some of them very exceptional characters, are at once inter-
preted by assuming Enteroplea to be a male animal. Indeed, in no female
perfect Eotifer are the jaws wanting, and even in very young specimens the
ovary is not homogeneous, but contains many germinal vesicles or spaces. A
reference to Dujardin's description and engravings adds additional weight to
this opinion. This supposition has been confirmed, both by Leydig himself
Mutter's Archiv, 1857, p. 404, and A. N. H. 1857), and by Cohn (Zeitschr.
1855, p. 451), and we would refer the reader to their memoirs for an ex-
tended description of this male being. By these researches, the testicle and
its contained spermatozoa, together with a male projectUe organ, the absence
of a digestive apparatus, and other sexual peculiarities, have been satisfactorily
made out.

In the ease of Notommata granulans, the arguments for its male character
are, the absence of the maxillae, and probably of the ovary also — for neither
Ehrenberg nor Weisse could satisfactorily make out the existence of the latter,
— and, further, the presence, as the Berlin Professor points out, of two sorts of
eggs upon Notommata Bracliionus, the smaller of which bring forth individuals
of the supposed different species, Notommata granularis.

The evidence for the male nature of Diglena gramdaris (Weisse) is its
constant occiu-rence in company with D. Catellina, and the production of
two sorts of eggs by the latter, the smaller of which give bu-th to embrj'^os
wanting the dental appai'atus. Such imperfect beings as the Diglena gramt-
laris and the Notommata gramdaris were explained by Weisse to be immature
or premature embryos. " It is truly interesting," says Leydig, " that Weisse
at the time he -wrote perfectly ignorant of male Rotifera, should arrive at the
conclusion that Notommata gramdaris, Diglena gramdaris, and Enteroplea
Hydatina were not distinct species, but the incomplete and toothless yoimo-
of the several species, Notommata Bracliionus, Diglena Catellina, and Hydatina
senta." It is added in a note—" Under the name Notommata gramdaris may
Avell be associated together the veiy similar males as well of Notommata Bra-
chionus, as also of B. urccolaiis and B. Pala." A few notes in illustration
may be added from Cohn's account of the male of Bracliionus urceolaris
(Zeitschr. 1855, p. 471). This is much smaller and more active than the
females. Its rotary apparatus forms a wide ciliated rim ; but its cilia arc not
tiuTicd inwards and downwards, as in the females, to enter the mouth, for no
such orifice exists : hence there is no maxillary head, no intestmo, and no
gastric glands. In the place of those organs lies a large pyriform 'saccidar
testicle, as much as y^th of an inch in longth, incompletely filled with fine
dark corpuscles, wliich, when mature, acquii-e the characteristic fio-ure and
swarmmg movements of spermatozoa. The wall of the testicle is ex^'cossivclv
thick, perhaps muscular, and is extended upwards into a thick cylindi'ical band
which appears to serve as a medium of attachment to fix the gland above to
the region of the cephalic disk. At its posterior end, the testis presents a close
longitudinal stnation, and is perforated by an aperture which opens into a
wide canal ending in the penis. This last-named organ has the aspect of a

456

GENIillAL mSTOEY OF THE INFUSOfilA.

short tube, which, as a rule, lies free upon the foot, and extends neaiiy to its
extremity. Its inner canal, and its external border, exhibit vibratile action.
The foot is transversely wiinkled, and ends in two small toes. About the
oiigin of the penis fi'om the testicle are two club-shaped glands which pour
their secretion into the canal ; and noar them is the contractile vesicle, giving
oif its respii'atory canal on each side, with the usual tag-Kke appendages.
Several spherical cell-looking bodies occiu- about the head, vnth. the largest
of which the eye-specks are in connexion, and which may therefore be con-
sidered the cerebral ganglion. Upon the testis, near its lower end, two or
three vesicles are placed, filled with dark granules, resembling those seen in
Etitercyplea Hydatina, and of which we cannot predicate further than that
they are not of the nature of ui'inaiy concretions (as Leydig imagined), but
in some way belong to the sexual apparatus, or else are uncoasumed cells
of the yelk-mass.

The tubular or band-Uke prolongation from the upper extremity of the
testicle, noticed by Cohn, and considered by him a " snspensor testis," repre-
sents, in Leydig's opinion, rather the rudiment of the undeveloped alimentary
tube. This author Ukewise denies Cohn's statement that the walls of the
testis are thick and muscular, asserting that they consist of a thin membrane.

The spe^^matozoa, i. e. the fecundating male particles, have been desciibed
by Mx. Dalrymple, Gosse, and Leydig. We borrow the description of the
latter as the more recent : — " The testicle (XXXVII. 29 c) of Notommata
Sieboldii is at once seen to be more or less completely filled with spermatozoa,
arranged about the excretory duct in a radiating manner; when not too much
compressed, they move about within the testis. On isolating by slight pres-
sure the contents of the organ, may be noticed, 1, large round vesicles, in
which, by a stronger magnifying power, two, or probably more, hyaline nuclei
with nucleoli, entirely occupjong the space, may be distinguished (XXXYII.
30 e) ; 2, somewhat larger ceU-formed elements, disposed in a radiating
manner about a centre, and larger towards one side (XXXVII. 30 c) — at
the rounded extremity a clear nucleus, with a nuclear coi-puscle, is always
placed; 3, elongated, mostly falcate or ciu-ved structures, which have the
before-mentioned nuclei in their iaterior, and on one mai-gin are expanded
into an evidently imdiilating membrane (XXXVII. 30 a, b, d). They move
about, and swim hither and thither, in such a manner that they remind one
not a little of many Infusoria, having a clear shai-ply-defined eontom- and a
rod- like figure, with a slight enlargement at the middle. It is these bodies
which lie around the commencement of the excrctoiy duct, and give rise to
the apparent striation above alluded to." In Hydatina senta the spermatozoa
are likewise of two forms, and are noticed sometimes to have a swarming
movement even within the testis.

Leydig has been imable to satisfy himself whether the stave- or rod-like
vai-icty (XXXVII. 30/) is to be considered the ripest of the spermatozoa,
and derived from one of the other forms, or whether there are two sorts of
spermatozoa in Notommata Sieboldii, as there are in Paludim vivlpara, one
of the MoUusca.

Perty states briefly and generally, of the spermatozoa of Rotatoria, that they
have a broad-oval refracting body, and a tail-like appendage.

The spermatozoa liave been seen within the abdominal cavity of not a few
female Rotifera, fi'eely moving about wthin it. For instance, it ha.s been
witnessed in Brachionus, ConocMlus, Lacimdaria, Megahtrocha, and Hyda-
tina. It is not known how they reach this cavity, since the cloaca into
which they are normally received is a closed sac. Cohn imagines they may
enter through some aperture in the integument as yet unnoticed ; it is, how-

OF TJir, ROIATOlUA,

457

ever, more conceivable that they may pass from the cloaca into the respiratory
tubes, and escape into the general cavity through the vibratile tags— supposing
these last to terminate by open mouths. On the other hand, it is just possi-
ble that some supposed examples of the presence of spermatozoa within the
abdominal cavity, have rather been instances of parasitic beings (Entozoa) in
the interior. Thus, in Hydatina senta, Leydig describes the interior occupied
by many numerous active animalcules, which ho refers to the genus Astasia.

The minute male beings just considered are brought into existence for the
sole purpose of fertilizing the ova of the larger and highly-organized female
animals. In relation to the females, they may be looked upon as little other
than parasites ; they are even deficient m organs necessary to carry on their
own existence : the one pxu'pose of impregnating the opposite sex being
fulfilled, theii- career is ended ; and this career is so brief, that the complicated
apparatus otherwise required to nom-ish and sustain the beings can be dis-
pensed with.

The early history of the male Eotifer is that of the female. The evolution
of the ovum from the ovary, and the changes transpiring in the contents of
the egg irntU the several organs become distinguishable, ai'e identical in the
two. The following particulars from Cohn's paper {Zeitsclir. 1855, p. 471)
■will serve for illustration. The males of BracMonus urceolnris are developed
from smaller eggs than the females, and which are adherent in large number
at the same time to the parent-animal. These eggs are very spherical, and
reach -g-J-y th of an inch in length and -s-g^^th in diameter. Theii' shell is more
delicate, the contents clearer and much more transparent, from containing
fewer granules, and of a pale- yellow hue, whilst the usual summer eggs are
dusky gTey. Even when matru'e, this greater transparency and absence of colour
persist. Fission proceeds in the same way as in the female ova ; and after
it has been many times repeated, the different organs of the embryo begin to
make their appearance, — the red eye-specks being among the first. However,
unlike what happens in the female ova, no signs of the maxillary apparatus
come into view, but two or three dark heaps of granules which are not seen
in those. When mature, the embryo springs from the shell through a trans-
verse niptiire, and is then seen to have a totally different figure from the
female beings, and at least three times smaller. When completely extended,
it measui'cs only between -aYrth and y^th of an inch in length, and ^ i^^th
to -g-l-fj-th in width, and is observed at the first glance to be destitute of" the
firm integument or shield of the female animals, and to have a short-cylin-
drical figure, prolonged anteriorly in the fonn of a short head separated by
a constriction from the body. The foot is short and tubular, the head croAvned
by a flattened disk expanded into a wide mai-gin, which is clothed with Ion"-
vibratile cUia and a few non-vibratile bi-istles. Their movements arc extra-
ordinarily energetic.

The same female may lay in succession several male ova. According to
Leydig, both male and female ova are not generated at the same time. The
small size and relatively incomplete organization of the male Rotifera is a
circumstance not pecuUar to the class; the like is seen in the imperfect
" imago" of many Insects, destined only to a sexual purpose, in the para-
site-like males of Lernaa, in the miniature and incomplete males of Daph-
niadce, and in the equally inferior male representatives of Folynoe, E.vo(ione
and of the Nematoda generaUy, among Vermes. Leydig, moreover, iinds an
analogous fact m the Siphonophora, in which he assumes the so-called genital
capsules, distributed every^vhere in the aggregate mass of animals, to liave'a
male character, and shows this opinion is in harmony A\dth the views nut
forward by Leiickart respecting them. ^

458

GENEHAI, HISTOEY OF THE INFTJSOUIA.

Mr. Gosse's conclusion {Phil. Trans. 1857, p. 322) is, that " a distinction
of sex is the normal condition of the class, or at least of that group which is
most typical, viz. such as have articulated mallei working upon a separate
ai'ticulated incus. Whether the same rule prevails so generally in those which
have the mallei and incus fused together into quadrantic masses, and in those
in which the organs exist in a rudimentary condition, is a question yet to be
determined. As these are certainly the lowest forms of their class, it is pos-
sible that hennaphi-oditism may be found in them — in the Phihdinadoe, for
instance."

The summary of the facts as yet ascertained, concerning male Rotatoria,
will form a valuable addendum to our account : —

" The most prominent thing that strikes us is the absolute and universal
atrophy (so to speak) of the digestive system in male Rotifera. Another
curious peculiarity is the dissimilarity that always exists between the sexes.
In Asplanchna and Hydatina the resemblance is at its highest point ; in
every other instance observed, the sexes are so unlike, that they would be
taken for widely-remote genera. The male is always inferior in size, and
also in organization, to the female.

"Whether certain individuals produce only male, and others only female
young, or whether separate impregnations are required for the production of
the separate sexes, I do not Icnow ; but from all my observations I gather
that the development of the one sex never takes place coetaneously with that
of the other ; for male and female eggs are never seen attached to the same
parent, and the immature eggs in the ovary invariably develope themselves
into the same sex as those which are already extruded.

" The duration of life in the male is always very brief. I have never been
able to presei-ve one alive for twenty-four hours. Their one business is to
impregnate the females, which is the work of a few minutes, probably, in a
state of freedom ; and for this momentary occupation no supply of loss, by
assimilation of food, is wanted ; and hence we can understand the lack of the
nutritive organism.

" Some organs are found, with greater or less distinctness, in all. The
(presumed) male of Hydatina senta received its names of Enteroplm and
Organ-Jisch from Ehrenberg on account of the copiousness of its internal
organization. A muscular system is well developed there, and in the msiles
of Asplanchna and of Brachionm Miilleri ; and, from the varied movements
of all, its existence may be inferred where it is not detected. The frontal
cilia are, in almost all cases, much more developed than in the females ; the
result of which endowment is seen in the excessive rapidity with which the
male shoots in all directions through the water. The great head-mass of
granular substance is generally distinct ; and in several cases (as in the As-
planchnce and in Brachionus Dorcas and Br. Miilleri) the great occipital gan-
glion is weU-defined, with the red eye seated on it as in the other sex. Even
where the ganglion is not apparent, the eye is conspicuous, with the exception
of Sacculus and Polyarthra ; and in this last instance the small size of the
animal must be borne in mind, and the density of the anterior parts.

" In the (presumed) male of Hydatina, in those of all the Asplanchnfe, and
of Brachionus Dorcas, there are organs answering to the lateral convohitcd
threads of the female ; and, in Asplanchna Brighttvellii at least, these are
accompanied by tremulous tags, and by a contractile bladder.

" A large mass of substance which, being perfectly opaque, appears black
by transmitted light, but is wliite when tlie rays are reflected, is so generally
found in male Rotifcra as to be characteristic, though it is not universally
present. I do not find it in the As^^lanchna:, nor in Sacmhis. On the other

OF THE HOTATOEIA.

459

hand, I have obsei-ved it in the young of Stephanoceros, Floscularia compla-
nata, and F. cornuta ; and Ehi-enberg mentions it in F. ornata and Ladnu-
kiria. In Stephanoceros, it was certainly associated with well-developed
jaws ; and hence I presume it is not exclusively an indication of the male
sex. The mass is sometimes broken up into fragments, of irregular size and
shape, and sometimes apparently pulverulent. In general, it appears to lie
loosely in the midst of the granular amorphous matter that occupies the pos-
terior region of the body-cavity ; but in BracMonus Pala, and especially in
Br. amphiceros, I have fancied that I discerned traces of a vesicle, within
which the white substance seems to be contained.

" On the nature of this substance I have no light from personal research.
Dr. Leydig, however, considers it to be a urinary concretion {Harnconcre-
mente), analogous to the chalky fluid which is (fischarged by many insects
immediately after their evolution from pupae.

" In the male oi Asplanchna Brightwellii, there is, as its discoverer observes,
' a conspicuous round sperm-vessel, or testis, in which .... spermatozoa in
active vibratile motion may be seen.' Mr. Dabymple, and subsequently
myself, also saw these, both within the sac and discharged by pressure.
Each spermatozoon, according to my own observation, consists of an oblong
body, J ^1- qth of an inch long, and an abnipt, slender, vibratile tail of equal
length. In the sperm-sac of A. Sieboldii, Dr. Leydig finds various seminal
elements, viz. round cells ; pyriform cells, drawn out to a fine point, and ad-
hering to each other by their rounded ends in a stellate manner ; oblong
bodies, with one side dilated into a free, undulating, membranous border ;
and slender, stiff, rod-like bodies, with a central swelling ; all containing
nucleated nuclei. On the male of A. priodonta, my observations were too
limited to determine more than the existence of the globular sperm-sac.

" In BracMonus rubens and Br. Mulleri I found spermatozoa, which I have
above described. In the latter, the sperm-bag is of great size, and contains,
besides the spermatozoa of imusual development, slender spiculiform bodies,
which may be the equivalents of the little rods described by Dr. Leydig in
Aspl. Sieboldii. The sperm-bag (in Br. Mulleri) is closed posteriorly, as it
is also in Asp. Brightiuellii, by what appears to be a true sphincter ; and
such I conjecture to be the explanation of those diverging lines which
M. Dujardin saw in Enteroplea (so-called), which he considered to be pedi-
cles of his ' touffes de (^ranides,' while the ' touffes ' themselves I take to
have been the masses of urinary concrement. Dr. Leydig, however con-
siders the whole to have been masses of spermatozoids. '

" The outlet of the sperm-bag is, in all cases, by a thick protrusile and
retractile penis. Wherever a foot exists, this intromittent organ is continu-
ously united to its dorsal side, and is often so gi-eatly developed that the foot
itself appears as an appendage. The protrusion of the organ, at least in most
of the examples that I have noticed, is by the eversion of the integuments.
When these arc evolved to the utmost, the organ is seen to be a thick
column, conical or nearly cylindiicaJ., with the extremity tnmcato, and sur-
rounded by a wreath of vibratile cilia. It was doubtless the extremity of
the penis that M. Dujardin saw as ' iin onjane cilie entrc les mmcles de la
queue,' m the (so-caUed) Enteroplea. The male of Saccidus viridis, a species
which IS footless m both the sexes, is the only example in which I have not
seen the penis ; but the organ is probably wholly retractile Avithin the body
and my observations, on the only incUvidual of this sex that I saw, were in-
sufficient to determine anything concerning it."

That male Rotatoria have been recognized in comparatively few species
admits of several explanations. The smaller size and comparative rarity of

400

GENEHAL HISTOEV OF THE INFUBOIUA .

the males ; theii- dissimilarity of figui-e to that of the females, which, cou])le(i
with imperfect examinations or misconcei^tion of their interior organization,
would readily lead to their- institution as new species or genera ; the influ-
ence of the prevalent hypothesis of a hermaphrodite nature, and the conse-
quent exclusive search for male organs in the perfect female forms, in which,
too, the uncertainty appertaining to the purpose of several ai)preciahle tissues
or organs would tend still further to lead astray ; the short existence of the
males, and even that brief Life hmited, it would seem, to a pai-ticular period
of the year, the early spring, when such creatures are less sought after ;
each and all these axe circumstances which have caused the male Eotatoria
to be overlooked, and continue to do so. However, the non-recognition of
the male animals occurs not only in the case of the Rotatoria, but also of
other classes of animals, even more highly organized and so lai-ge as to be
capable of examination without the aid of the microscope. Among minuter
organisms in which an uncertainty prevails, may be mentioned the Daph-
niadce and other Entomostraca, among the majority of genera of which the
males are still undetected, nevertheless the bisexual character of the class
is admitted.

The comparative rarity of male Eotatoria admits of an interpretation de-
rived from analogy. It is a well-recognized fact, that in several classes of
Invertebrata (for example, in Daphniadce and, among Insecta, in the genus
Aphis) several generations succeed one another without the concurrence of
a male animal in their production, — a phenomenon well named by Prof.
Owen, Parthenogenesis or Virgin-generation. Now it clearly appears that
one contact with a male Rotifer may suffice for the fertilization of all the
germinal cells in any female ovary, and be followed by their successive de-
velopment. To use the language of Prof. Owen, the spermatic force once
applied suffices for the impregnation of a multitude of ova, or, in fact, of the
whole ovary ; and the fact quoted, of Apliides developed by the immediate
action of the spermatic force being in theii- tiu-ns capable of reproducing
others by gemmation without a renewal of that force, warrants the supposi-
tion that an analogous phenomenon may exist in the Eotatoria. This analogy
is strengthened by Mr. Huxley's interpretation of the natiu-e and puiijose of
" winter " ova, Avhich he believes to be the instmments of an asexual repro-
duction. A portion of the ovary seems to be modified and extruded, and sub-
sequently to generate a couple of embryos. On the other hand, in the Aphides
an internal geiminal mass remains within the body, and a portion of it ap-
pears to be abstracted by each successive indi\ddual produced, until at length
the spermatic force is exhausted. This internal germinal or reproductive body,
the instrument of an asexiuil generation in the Aphides, is then surely homo-
logous with the extmded external generative bodies, or "ephippial ova," of Eo-
tatoria. Such an asexual reproduction implies a fewness of male beings com-
pared with the multitude of young which must be developed by the generative
processes. Again, the male Eotatoria are not only developed in smaller numbers
than the female, but their whole term of existence is very brief, only long
enough to fulfil their generative purpose ; and, lastly, they arc to be found
only at particular seasons, mostly in tlie spring.

Another obvious reason for the scarcity of male Eotifcra suggests itself,
viz. that the social institutions of the class may not be on the monogamous
model, but that one little active male may divide his favours among a whole
harem of fcmiJes before he completes his brief ciu-ecr. However this may
be, to discover the male of any one species, continuous obsen-ation is needed,
particularly at certain times of the year ; and it must be confessed that but
few Eotatoria have hitherto had their histoiy fidly investigated. In most

OF THE ROTATORIA.

461

cases, the examination of a species has been casually undertaken ; the attention
has been dii-ected to it only by some accidental circumstances, and this only on
some one occasion. We cannot, therefore,wonder that therarely-occiirring males
have not often been encountered. But the most satisfactory means of deter-
mining the existence and characters of the males of any species of Eotatoria
have latterly been fiimishod by the careful descriptions of the special cha-
racteristics of male ova, whereby they can be distinguished even before leaving
the oviduct, and their developmental histoiy traced foi-wards until their ma-
turity.

We may mention that Mr. HaUett, formerly demonstrator of anatomy in
the University of Edinbiu'gh, and subsequently a student in anatomy at the
College of Surgeons, London, directed his special attention for many years to
the Eotatoria, and especially to the detection of the male individuals ; and
although his early death has deprived naturalists of the published results of
his researches, yet, from repeated verbal commimication, we can state that
he had arrived at the discovery of the male beings of the majority of the
Rotatoria.

Doubtful Male Organs. — Many natiu-alists are unprepai'ed to admit bi-
sexuality to be the universal rule in Rotatoria ; and several eminent obsei-vers
are disposed to consider certain organs in female animals to be of a male
sexual character.

Prof. Williamson, in his history of Melicerta, says — " I have sought in
vain for any organ to which the fimctions of a spermatic gland can be indis-
putably assigned. Immediately beneath the lower stomach and the conti-
guous oviduct, there is an elongated pyramidal organ, apparently hoUow, the
thick extremity of which is directed towards the ovaiy, and its opposite at-
tenuated portion passes upwards toAvards the cloaca, between the oviduct and
the general integiunent. Into the thick inferior extremity of this organ,
there are inserted, exactly opposite to each other, two long-cylindiical ap-
pendages, which diverge, and, passing on each side of the alimentary canal,
proceed towards the upper part of the body, where their extremities are not
easily traced. Li but one instance I observed them to terminate in a series
of irregular convolutions near the base of the two tentacles. Though not yet
capable of demonstration, it appears probable that this eimous appendage
may be a filamentous spermatic tube resembling those found in many Arti-
culata. That they are tubes, and not muscular bands, appears unquestionable ;
and as they have obviously a dii-ect connexion with the cloaca, they mio-ht
easily discharge a fertilizing secretion into that common excretory canal, from
which it Avoiild find its way to the ovary through the oviduct " (p. 432)

Now it is to be remarked that Mr. Williamson states he could discover
"no special organs of circulation or respiration, no vessels or pul'satino-
organs," and that the two tubes he has referred to as being possibly sper-
matic ducts are the homologues of similar ones in other Rotifera, to which
Ehrcnberg has assigned fertilizing fimctions. Fm-ther on he observes—
" The singular bodies resembling spermatozoa exist in various parts of the
organism, where they are apparently enclosed mthin hoUow canals. I have
never seen them occupying the two main trunks of the ' water-vascular
system ' or cajca ; nor can I succeed in tracing any connexion between them
In several cases I have seen one or two of these curious bodies opposite the
centre of the upper stomach, very near to, but independent of, tiie main crecal
canal, and at some distance below tiie point where the latter probablv sub
(hyides into branches. Near tiie neck there are usually from two to three
pairs. Their vibratile motion ceases the moment tiic animal is killed bv
pressure. This fact does not countenance the idea that they are sponnnto7oa "

462

GENEKAL HISTOEY OF THE INFUSOEIA.

From the above remarks and statements, it seems to as quite clear that
the pyramidal sac opening into the cloaca, and its upwardly-prolonged canals
referred to, are nothing more than the " water-vascular system " of the Me-
licerta, and that more or fewer of the observed vibratile bodies are, in fact,
the cUiated tremulous tags. Had the pyramidal sac represented a testicle,
spermatozoa ought to have been seen within it ; for these particles are readily
cognizable by their size, figure, and movements.

Prof. Huxley having failed to find a male among some scores of female
Lacinularice, or a single ordinary spennatozoon, is disposed to recognize the
male sexual element in some singular bodies met with in many individuals he
examined. These bodies " answered precisely to KolHker's description of
the spermatozoa " of Megalotroclia. They had a pyramidal head about ^ o'o(,th
of an inch in diameter, by which they were attached to the parietes of the
body, and an appendage four times as long, which underwent the most ex-
traordinary contortions, — resembling, however, a vibrating membrane much
more than the tail of a spermatozoon, as the undulating motion appeared to
take place on only one side of the appendage, which was zigzagged, while the
other remained smooth. "According to KoUiker, again, these bodies are
found only in those animals which possess ova undergoing the process of
yelk-division, while I found them as fi'eqiiently in those young forms which
had not yet developed ova, but only possessed an ovary.

" Are these bodies spermatozoa ? Against this view we have the imques-
tionable separation of the sexes in Notommata, and the very great difference
between them and the spermatozoa of Notommata. Neither the mode of de-
velopment, nor the changes undergone by the ovum, afford any certain test
that it requires or has suffered fecundation, inasmuch as the process closely
resembles the original development of the Aphides.

" In the view that KoUiker' s bodies are true spermatozoa, it might be said,
1. That the sexes are united in most Distomata, for instance, and separated
in species closely allied (e. g. D. Okenii). 2. That the differences between
these bodies and the spermatozoa of Notommata, is not greater than the dif-
ference between those of Tritons and those of Bana. 3. That their develop-
ment from nucleated cells within the body of Megalotrocha (according to
KoUiker) is strong evidence as to their having some function to perform ;
and it is difficult to imagine what that can be if it be not that of spermatozoa.
However, it seems to me impossible to come to any definite conclusion upon
the subject at present."

In Melicerta, Prof. Huxley notes having met with " an oval sac lying below
the ovary, and containing a number of strongly-refracting particles, closely
resembling in size and foi-m the heads of the spermatozoa of Lacinularia."

These views of Mr. Huxley are of no value in deciding the question ; they
rest on a supposed simUarity between the bodies discovered and those which
KolUker believed to be spermatozoa in Megalatroclia, — an opinion not incon-
trovertible. On the other hand, their spermatozoid nature is discountenanced
by their simUarity (which, indeed, Huxley remarks) to undoubted sperma-
tozoa of Rotifera.

In a new species of Melicerta discovered by Prof. BaUey in America, that
accurate observer found that pressure between two plates of glass liberated
vast numbers of spermatozoa ; but he was unable to ascertain from what
organ in the animal they were set free. The observation, however, is im-
portant as indicating the existence of true male organs in Melicerta of a very
different character from those suggested by various observers as having pos-
sibly fecundating functions.

Respecting these questionable male elements, Leydig has the following

01' THE ROTATORIA.

463

remarks, premising that the detection of spermatic particles in one species
furnishes u criterion in pronouncing upon the signification of some other
bodies : — " I have heretofore mentioned my idea that the hairy corpuscles of
Lacimdaria (occupying the general cavity of the body, and impelled hither
and thither by its movements) are seminal particles : although this is still
questionable, yet these presumed parasites of Lacinularia must, I believe, be
still rather looked upon as unequivocal spermatozoids. The form and strac-
ture, moreover, of the bodies figiu-ed by Huxley, and doubtfully called by
him spermatozoa, have an evident affinity vdth the seminal elements of No-
tommata Sieholdii. It also seems to me probable that the spermatozoids
portrayed by KoEiker in Megalotrocha are reaUy such, and that the animals
in which they ai-e found should be esteemed as previously impregnated
females. I moreover consider that the illustrations furnished by Ehrenberg
of Conochilus volvox, show an individual with two spermatozoa; and the
account referring to it, in which he says ' I lately saw oscillating, very pe-
culiar, gill-like organs, in the form of two spiraUy-twisted bands, at the pos-
terior extremity of the body,' also speaks in favour of this signification. The
entire delineation of these ' spiral gills ' might replace very well that of the
peculiar seminal elements with undulating membranes."

Afterwards, when speaking of the parasites of Eotatoria, Leydig observes
that having formerly eiToneously described the seminal corpuscles of Lacinu-
laria as parasites, he must now, on the other hand, class the once-presumed
spermatic particles with parasitic organisms.

In the course of subsequent researches on Hydatina senta (MiiUer's Archiv,
1857, p. 104), Leydig has discovered the same sort of structures in that ani-
mal. He writes — " They are globular bodies with sharp outlines ; and their
margin looks as if clothed with fine hairs. Towards the end of March, the
entire abdominal cavity was in many specimens so filled with them that the
animals presented a white appearance by reflected light ; yet the animals so
affected swarm about just as briskly as the others." This repletion with such
particles appears to us to intimate that they cannot be spermatozoa, either
generated within the beings themselves or received from without from male
animals. Indeed then- occurrence within the abdomen of Hydatina senta
is of itself an argument against their being spermatozoa derived from a male
gland within, inasmuch as this species is proved to be impregnated by its
own male partner, formerly known as the Enteroplea Hydatina. The ques-
tion presents itself, whether they can be derivable from the food, as products
of digestion or chyle-globules. '

The search for male Eotatoria has led the occasional connexion of two in-
dividuals to be noticed, and to be explaiaed as of a sexual character. Perty
noticed two individuals of Cohcrus uncinatus, and two of Lepadella ovalis, in
union. But such connexions may rather be considered accidental ; for Perty re-
marked a Colurus so attached to Lepadella, and a CJmtonotus Larus to Lepadella
ovalis Cohn has had his attention directed to the same circumstance, and
remarks that two Eotatona of the same or even of a different species are
very often to be seen attached together, sometimes by the back, at others bv
the abdomen at others by the pseudopodium, and to swim about together for
a length of time. This he has seen in Dujlena, Colurus, and LepadelU ; it
ha^ however, no connexion with the reproductive function.

Of the Duration and Conditions of Life of the Eotatoria, and of their
Habitats and DiSTRiBijTioN.-It is next to impossible to determine, by direct
obsei-vation the duration of life among the Eotatoria when placed under
natural and favourable conditions. Many may well be supposed to survive
from their birth m the spring untU the M^nter, and not a few even through

464

GENEEAL HISTORY OF THE INFUSOHIA.

this season until some future period, since observations prove their power of
assuming a torpid condition when existing circumstances are unfavourable
to the full exercise of life. It has been noticed by Ehrenberg, of some Rota-
toria living, so to speak, in confinement, or ia a limited quantity of water
under examination, that when the weather was warm and nourishment
abundant, life was prolonged to 18 or 20 days and more ; and Mr. Gosse also
speaks of a Melicerta which lived in confinement for 14 days.

The conditions of life, or the causes affecting the vitaUty of Rotifera
favourably or unfavourably, are in some respects very remarkable, as an ap-
peal to their habitats alone would abundantly illustrate.

It is during the height of summer that the Rotifera are multiplied most
abimdantly ; but when the cold frosty nights of autumn supervene, their
numbers undergo a rapid reduction. However, often during the most beauti-
ful pai-ts of the year, as Perty remarks, a sudden decrease wiU occur.

" Two kinds of disease," writes Ehrenberg, " destroy the Hydatina and
most of the Rotatoria : 1, the formation of vesicles, which give rise to the
appearance of small rings aU over the creatm-e ; and, 2, the formation of
granules which so penetrate the internal organs that these seem composed of
them, and have a shagreen appearance." The first condition has been noted
by Weisse, who regards the apparent vesicles as parasitic organisms.

the Rotatoria also suffer fi-om the overgTOwth upon their suiface of Algae
and of parasitic animals. Protozoa and the like, and are at length destroyed
thereby. Foul or decomposing water is incompatible with their existence, as
are some chemical mixtures, whilst to others they seem indifferent. Thus
Hydatinm have been fed with rhubarb and indigo in powder without sensible
effect, and neither calomel nor corrosive sublimate kills them ; at least, they
live for some time after these substances have been mixed with the water.
Strychnia causes instant death.

The deprival or the want of renewal of aii- in water inhabited by Rotifera
causes their destruction, for example, when collected in abottle for examination,
the cork being allowed to remain too long. In like manner the exclusion of air
by a pellicle of oil on the surface of the water, or the withdrawal of air by
means of an air pump, speedily destroys the Rotatorial inhabitants. Ehren-
berg affirms that they exist much longer in an atmosphere of nitrogen than in
one of carbonic acid or of hydi-ogen, and that the vapom- of sulphui- speedily
puts an end to their existence.

Still a very imperfect renewal of air seems, at least in some instances, to
suffice — as in the case of the Rotifer vulgaris and 11. jjarasita, which have
been seen within the sphei-es of Volvo.v and in the cells of aquatic plants
(the Vaucheria clavata.) Perty likewise mentions the Notommata Werneckii
as inhabiting the Vauchei'ia ccespitosa ; and Albertia vermicularis is parasitic
within the intestine of earth-worms and slugs. In all these instances life is
compatible with a very slight renewal of atmospheric air, or, in fact, is sup-
ported amid the gases generated within these organic beings and mixed witli
their fluids.

The evaporation of the water from around Rotifera, as when under exami-
nation by the microscope, is a frequent cause of their destruction, by the
breaking up of their soft parts. But there is a happy provision against such
evil consequences ; for, so soon as the animal experiences the deficiency of
water around it, it withdraws its tender wheel apparatus, and limits its ex-
posed parts as much as possible, by retracting its pseudopodium and contract-
ing itself into a l)aU-lilce fonn, so' that only the denser integument is exposed
to the injurious influences, and the evaporation of water from the contained
organs reduced to its minimum.

OF THE ROTATORIA.

465

Indeed the Rotatoria, in part at least, have a remarkable power of preserv-
ing their vitality, not only when left dry by ordinary evaporation, but also
when thoroughly desiccated by the assistance of heat. Leuwenhoek and
Spallanzani experimented on them, and announced the fact of their revivifi-
cation on the addition of moisture, months and even years after their com-
plete desiccation. Schrank, Bory St. Yincent, and Ehrenberg questioned the
tmth of this statement, at least in its full acceptation ; and the writer last-
named affirmed " that wherever these creatures ai-e completely desiccated,
Ufe can never again be restored. In this respect the Eotifera exactly
correspond with animals of a larger kind : like them, for a time they may
continue in a lethargic and motionless condition; but, as is well known,
there will be going on within them a consumption or wasting away of the
body, equivalent to so much nourishment fi-om without as w^ould be needed
for the sustentation of life." Neither the last statement nor those preceding
it are correct ; MM. Schultze and Doyere have repeated and confirmed the
experiments of the old observers ; and the latter authority concludes that
Rotifera may be completely dried in pm'e sand ia the open air, and in a
vacuum, without losiag the capability of being revived by moistiu-e. Many
iadeed are sacrificed in the process ; but enough recover to demonstrate the
possibility of the fact.

This extraordinary power of resuscitation after drying explains the re-
appearance of Rotatoria on the collection of water in shallow pools which
have been entirely dried up by the hot sun of summer, and theu- con-
stant presence in the diy debris of the roofs, and even of the interiors of
houses.

In their relation to temperature, also, the Rotatoria exhibit great tolerance.
M. Doyere proved that when placed in water at fi'om 113° to 118°, they
could afterwards be revived, but that when thrown suddenly into boiling-
water (at 212°) they were at once killed. In the latter case, the sudden,
heating is supposed to coagulate the albuminoid contents of the animals, and
in that way to cause death, because individuals previously dried by a gradually
raised heat of 216°, 252°, and even of 261°, were many of them still capable
of being revived.

On the other hand. Rotatoria can live in water at the freezing-point. They
are to be foimd imder ice, and also within the hollow cavities of ice ; and
Perty mentions a score of species which he met with in such localities. He
also recounts meeting with individuals contracted in a more or less globular
figure, preparatory, as he surmises, to a winter sleep or torpor. He fio-ui'es
a Philodina erythrophthalma (XXXVIII. 4) in this condition, which is pre-
cisely the same as that assumed when the animal is left dry ; and lie adds
that when Scaridium loncjicaudimi assumes this state, it \\'ith'draws its head
within its envelope and doubles its tail under the abdomen, just in the same
way as a Podura. Ehrenberg doubtless refers to this same contracted con-
dition in the account before quoted from him (p. 449-50) respecting the
Rotifera found at great altitudes among snow, Avhich he described as havino-
an ovate figure and enclosed in an egg-shaped envelope.

Conochilus and LacinuJaria are examples of Rotifera living in aggregated
masses. The former recalls, by its compound revolving spheres, the appear-
ance of Vohox Globator, whilst the latter occurs in small transparent ielly-
like balls adherent to the leaves of aquatic plants. ' '

At times the Rotatoria multiply so rapidly in small stagnant pools a.s to
colour the water. Hi/datina ncnta, DUjlmn catelUnn, Triarthra, and Lepa-
della are adduced by Elirenbei-g as producing a milky turi.idity in water and
the Ti/phlina viridls a.s imparting a green colour. ' ' '

2 a

466

GENEEAL HISTORY OF THE INFUSOEIA.

The Synchceta Baltica has been presumed to be phosphorescent; and
Anur(xa hiremis was discovered in phosphorescent sea-water.

The Eotatoria are distributed everywhere over the surface of the earth, in-
habiting its waters, both fresh and salt. Of the known species, by far the
greater number are dwellers in fresh water, abounding ia pools, ditches, and
gently-flowing sti-eams, especially where aquatic plants grow in sufficient
quantity to afford shelter and indirectly supply food by the hosts of animal-
cules which congregate on and about them. A too much overgrown or shaded
piece of water is less favourable ; for they require a complete intermixture
of air with the water, and the vivifying influence of the sun, for their healthy
existence. Some species especially delight in the little turfy pools on moors
or in boggy ground; others have been especially found in green-coloured
ponds — the colour being due to Protozoa and minute Algse, which furnish
them with suitable food.

Some of the early observers sought these animalcules especially in infusions,
very generally made with sage-leaves and chopped hay ; but the Rotifera are
comparatively rare in infusions : a few common species only appear ; and unless
the infusion be comparatively fresh, none will be found ; for they occur in no
fluid in which decomposition is going forward. When they do exist in these
infusions, they appear at a later period than do the Monadina and less highly
organized iufusorial forms.

The Imown salt-water species are comparatively few ; this is very possibly
owing to their being much less sought after than the freshwater animals.
The principal marine forms recognized are Brachionus MuUeri, B. heptatomus,
and Synchceta Baltica. Distemma marina and Furcularia marina, Colunts
uneinatus, G, caudatm, and Anurcea striata are encountered in both fresh and
salt water : several are found in brackish water.

Immersion in water is, however, not necessary to their existence : thus they
are to be found in the damp earthy deposit from rain-water spouts, and in the
detritus of the walls and roofs of houses ; in the moist himius or decaying
vegetable matter about trees, and especially upon the moist roots and leaves
of mosses and lichens — for example, among the tufts of Bryum and of Eyp-
niim, from which they may be separated by washing with a little water.

We have mentioned the peculiar habitat of Alhertia, within the intestine of
the earth-worm, of which animal it may be accounted an entozoon ; the
Notommata Parasitus also leads a parasitic existence within the hoUow spheres
of Volvox Globator ; and M, Morren, many years since, gave the following
interesting histoiy of the habitat of Rotifer vulgaris in the cells of Vauclieria
clavata (A. N. H. vi. p. 344) : —

" The labours of Keeper show that the cells of Sphagnum are sometimes
furnished with openings, wliich place their interior cavity in communication
with the air or water in which they are immersed. This skilful observer
satisfied himself that, when circumstances are favourable, the Rotifer vulgaris,
one of the Infusoria whose organization has been explained by the researches
of Ehrenberg, exists in the cells of the Sphagnum obtusifoliiim. This grew
in the air, in the middle of a turf-pit : but Keeper obseiTed its leaves in water ;
ho does not mention whether the infusorial animal came from thenc«, or
whether it was previously contained in the ca\ities of the cells. _ The general
purport of the paper seems to imply that these Kotifers exist in the cells of
that part of the plant which was exposed to the air ; and m this case, the
presence of an animal so complicated, living as a parasite in the cells of a
utricular aerial tissue, is a pha;noraenon of the most curious kind in the phy-
siology of plants, and the more so as this animal is an aquatic one.

" I recollected that, the last year of my residence in Flanders, I found at

OF THE KOTATOBIA.

467

Evergliem, neai- Ghent, the Vaucheria clavata, in which I observed something
similar. M. Unger had ah-eady published the foEo-ndng details respecting
this plant in 1828 : ' Beneath the emptied tubercles and at several points of
the principal stalk, at different angles, rather narrower branches are produced ;
these branches are generally very long, and greatly exceed the principal stalk
in length. At the end of ten or twelve days after their development, there
are seen, towards one or other of theii' extremities, here and there, at different
distances from the summit, protuberances of a clavate form, more or less
regular, straight or slightly bent back ; and others on the sides of the stalk,
which have the form of a capsule or vesicle. These vesicles are at first of a
uniform bright-green colour ; and without increase of size, which exceeds
several times that of the branches, they always become of a blacldsh-green
colom-, darker towards the base ; and then one or two globules of a reddish-
brown may be clearly distinguished there, often surromded by smaller gra-
nides, evidently destitute of motion, whilst the great ones move spontaneously
and slowly here and there in the interior of the capsule, by unequal contrac-
tions and dilatations, whence arise remarkable changes of form. I saw these
globules, at the end of eight or ten days after their appearance, stUl enclosed
in the capsule, moving more and more slowly, receiving no very decided in-
crease, whilst the base of the capsule became more transparent ; at last I
observed that, instead of their expulsion, which I was watching for, the
extremity of the capsule at the end of some days took an angular form, and
subsequently gave bii'th to two expansions in the form of horns ; it remained
in this state and became more and more pale, whilst the animalcule became
darker and died ; and afterwards it ended by perishing at the same time as
the other parts of the Conferva.'

" Subsequent researches have not succeeded in informing us what this
animal might be, of which Unger spoke. As this author di'ew so much atten-
tion to the spontaneous movements of the propagula of the Vauchenm, and
as he admitted the passage from vegetable life — characterized, according to
him, by immobility — to animal life, the principal criterion of which was
motion, his animalcule was confounded with the propagula ; and no one, so
far as I know, has returned to this very interesting subject.

" When, therefore, I found the Vaucheria clavata at Everghem, I was as
much siirprised as pleased to see the mobile body noticed by Unger better
than he did. With the aid of a higher magnifying power, I found it easy to
ascertain the true nature of the animal ; for it was not a propagulum, but
a real animal, the Rotifer vulgaris, with its ciha imitating the wheel, its
tan, <fec.

" The first protuberances or vesicles which I saw containing this animal
enclosed but one of them ; afterwards they laid eggs and multipUed ; but it
seems that then they descend the tubes of the Vaucheria and lodge themselves
in new protuberances, whose development they may possibly stimulate, as the
gaUs and oak-apples, or organic transformations attributable to the influence
of parasitic beings.

*' The Rotifer vulgaris travels quite at his ease in these protuberances ; he
traverses the partitions, displaces the chromule and pushes it to the two'ex-
tremities of the vesicle, so that this appears darker at these parts. One day
I opened a protuberance gently : I waited to see the Rotifer spi-ing out and
enjoy the liberty so dear to aU creatures, even to infusorial animals ; but no
—he preferred to bury himself in his prison, descending into the tubes of the
plant, and to nestle himself in the middle of a mass of green matter, rather
than swim about freely in the neighbourhood of his dwelling.

" Some of these protuberances had greenish threads appended to theii- free

2 H 2

468

GENERAL HISTOET OF THE INFTTSORIA.

end, and others had none : I thought at first that these threads were some
mucus from within, escaped thi'ough some opening which might have sen'ed
the Rotifer as an entrance ; but an attentive and lengthened observation con-
vinced me that in this there was no solution of continuit)^ and that the arrival
of the Botifers in the Vaucherice was not at all to be explained in this way.
How are these parasitic animalcules generated within them ? Tlus is what
further research has some day to show. Meanwhile I have thought that it
should be made known that the animalcule found in the Vaucherice by linger
was the Rotifer vulgaris of zoologists."

Several of the Philodinaia, and particularly the Oalliclince, have been met
with in snow, along vnth the so-called red snow, in very cold regions, and
at considerable elevations, such as above the perpetual snow-line of the
Alps. Perty informs us that mosses and Hchens collected in the Swiss
mountains, at a height of 9000 feet, have yielded, on washing with distilled
water, numeroiLS Infusoria, including several Rotatoria, viz. Callidina. ele-
gans, Rotifer vulgaris, Philodina roseola, Diglena catellina, and Ratulus
lunaris.

We have no data whereon to constmct laws of geographical distribution
for the Rotatoria. Observation has proved no definite regional Hmitation of
species ; wherever searched for, the same species seem discoverable.

Owing to the perishable nature of their tissues, the Rotifera do not occur
in a fossil state ; they are, moreover, rare components of the showers of In-
fusorial dust.

Of the Affinities and Classification of the Rotatoria. — That the
Rotatoria, by their high degree of organization, should be elevated in the
animal scale far above Protozoa, is now universally admitted. Indeed they
cannot be rightly comprehended among Infusoria if this tenn be accepted to
indicate a definite class of beings ; for although there are slight general rcr
semblances between some Rotatoria and Protozoa, no true near affinities of
structure exist between them.

While naturalists generally are in accord on this necessaiy separation of
Rotatoria from Protozoa, they are much at variance respecting the relative
position of the Rotatoria in a classification of the Invertebrata, or, in other
words, concerning the trae affinities of the class. Thus Bm-meister, Owen,
Leydig, Dana, and Gosse would range them among Crastacea as a pai-ticular
order ; whilst Wiegmann, Milne-Edwards, Wagner, Sicbold, Colm, Perty.
Williamson, Huxley, and others would class them with Vermes — a section
comprehending Helminthae, TurbeUaria, and Annelida.

We shall first state the arguments used to demonstrate the Crustacean
alliance, which are most fully and poweifoUy brought forward by Leydig ;
they are, that

"The external figure is rather that of Crustacea than that of Yemi-.
None of the latter have a jointed organ of motion, such as most Rotifora
possess in their annulated or jointed pseudopodiura devoid of all viscera.

" The shield-like hardened integument or lorica of some species, ^ich as
Euchlanijf and Salpina, has its analogue among the Crastacea, wlulst in noiK^
of the Vermes is a similar indiu-ated cuticle to be foimd.

" Vermes arc destitute of striated muscles ; but Rotifera, equally with
Crastacea, possess them. The movements of many species recall in a striking
manner those of Crastaceans. The nervous system suppUes fiu'ther cndonco ;
for although the Rotatoria have no pharyngeal ganglionic ring and no cham
of abdominal ganglia proceeding from it, yet a similar deficiency prevails Avith
the Lophyropoda and the Daplmia:, recognized Crastaceans, which liavc only
a cerebrnl ganglion and radiating nerves like the Rotifera ; consequently it

or THE KOTATOllIA.

469

cannot be adduced as a law, that the highly developed nervous system of the
higher forms is an essential chai-acter of the Crustacea.

<' The mode of termination of the sensitive nerves is that seen in Cnistacea
and Insecta ; but the like is not known among Vermes. Ehrenberg pointed
out the similaiity of the eye-specks to those of Crustacea. The several seg-
ments and texture of the alimentary canal afford no decisive evidence, since
many Vermes have horny jaws, as have the Rotifera. The masticatory
apparatus of the young Dcvphnice presents a pretty close resemblance with
that of Rotatoria — the two opposed jaws expanding into a plate toothed with
numerous transverse ridges, like those of Lacinularia. The stomach-glands
probably have their analogues in the lobed glandular appendages — the so-
called ' salivary glands ' of Cirripedia.

" Similai- organs, however, exist in many dorsibranchiate Vermes ; and like-
wise in many Vermes and loAver Crustacea the liver is represented by large
ceUs with peculiar contents, situated in the waUs of the stomach and intes-
tine. The absence of an intestine in a few Rotifera may appear opposed to
their Arthropodous type ; yet in the Neiu'opterous larva of Myrmeleo the
feeces are discharged by the moiith, and the rectum itself is transformed into
a spinning organ. Moreover, the intestinal canal of many Rotifera, e. g.
EucJilctnis and Steplianoceros, recalls, in its peculiar bell-like movement, the
exactly similar character of the intestine of certain parasitic Crustacea
{Achtlieres, Tracheliastes, &c.).

" The substance regarded as urinary concretions is evidently closely re-
lated to that formed in the larva of Cyclops ; but no such point of resemblance
is found among Vermes.

" Lastly, the anatomical and physiological phenomena of sexual life greatly
favour the Crustacean relationship. Several minor particulars may be alluded
to — such as the production of two kinds of ova (indeed the winter ova of
Triarthra have a great likeness in the construction of the shell with the
ephippial ova of Daphnia), the fact that many species carry theii' eggs about
with them (although it is true the same is seen among Vermes, for instance
Clepsine), and the occurrence of coloured oil-coi-puscles in the yelk of not a
few Rotatoria — all indicating a Cnistacean type. The striking analogy be-
tween the male (in some sense aborted) Rotatoria and the males of many
Cnistacea is one of far higher import. It is only necessary to call to mind the
diminutive parasitic males Nordmann discovered in the females of Achtheres,
BracJiiella, Chonclr acanthus, and Anchorella, and such as Ki'oyor foimd in
other Lernceopoda and Lernmce.

" Moreover, the embryonic histoiy of Rotifera is in favour of the alliance
— viz. the imperfect development of the young of several species, on theii-
emergence fi-om the egg, and the necessary metamorphosis they undergo
before attaining the adidt condition. Lastly, the diminution or even com-
plete disappearance of the eyes after birth fiu-thcr indicates an analogy with
certain Crustacean forms.

" Whilst the foregoing considerations approximate tlie Rotifers to the
Cnistacea, the nature of the respiratory api)nrntus and the })rescncc of the
yibratile cilia separate the two, and assimihitc the Rotatoria to N^ennes ; yet
in both these particulars they make an equal approach to Echinodcrmata
inasmuch as tlio pccuUar vibratile organs of Synapta diqltata appear to bo
similar stnicturcs with the vibrating organs (tags or gills)."

Now, argues Leydig, it seems but just to allow the sum of the resem-
blances to any class, if greater than that of the differences, to dotormine the
systematu. position If this be granted, as the sum of resemblances of the
llotitera with (he Crustaceans seems assuredly greater llian that of their

470

GENEEAl HISTOEY OF THE INFUSOEIA.

differences from tliem, their alliance with them must be admitted. Making
due allowance, therefore, for the vibratile cilia and the peculiar respiratory
apparatus of Eotatoiia, Leydig would constitute them a special class of
Crustacea, under the name of Ciliated Crustacea.

The foregoing arguments of Leydig for the Crustacean nature of Rotatoria
have been severally met and replied to by C. "Vogt, ia a recent paper " On
the Systematic Position of the Eotifera " {Zeitschr. 1855, p. 193). The ob-
jections advanced are these : —

That Leydig assigns an undue importance to external resemblances ; and
that, as to movements, there is as much similarity between those of Philodina
and a leech, as between those of any other of the Eotifera and the skipping
motions of Entomostraca. The figure is no actual evidence of affinity : no
perceptible likeness exists between fixed Eotifera, or a sac-Kke Notommata
and a Crustacean, whilst, on the contrary, an undoubted similarity prevails
between a Stephanoceros and a Bryozoon ; and between Notommata tardigrada
and many of the Vermes the resemblance is more pronounced than that be-
tween any of the Eotatoria and a water-flea. Besides, there are Vermes of a
smooth, oval, discoid, and expanded figiu'e, and others with bodies not less
clearly divided into regions than the Eotifera.

An annulate articulation, like that of the pseudopodiiun of Eotifera, is also
a featiu'e seen among Annelida ; and the telescopic joints and movement are
witnessed in Eunice. It is the possession of limbs, each consisting of several
segments, which is characteristic of Articulata, both in the full-grown and
in the larva condition, and not an asymmetrical process actually forming but
a single segment. Further, spiaes and hooks, in some degree moveable like
the pincer-processes on the pseudopodium of Eotatoria, occur in many Vermes,
especially among the parasitic species. Lastly, a pair of jointed locomotive
organs is never found among Eotatoria at any period of theii- existence. The
assertion that the thickening of the integument as a lorica is not seen in any
Vermes is correct, if the constitution of the lorica of one piece be a necessary
featiu'e, although the thick cartilaginous tube of Gordiacece and the firm in-
tegTiment of many other Annelids may be adduced as analogous conditions.
But if a lorica may be composed of several pieces, the whole family of marine
Annelida, in which the skm is hardened into a fii-m shield, may be cited as
homologoiis. To Leydig's remark that he knows of no Vennes with a lorica,
the rejoinder may be made, that no Crustacean is foimd enveloped in a gela-
tinous sheath, like Notommata centrura, whilst, on the contrary, such :m
investment is common among Vermes, and especially exemplified in Siphono-
stomum.

Striated muscles are not unknown in Annelida ; they have been seen in
Salpa ; and in some Eadiata the particles of muscles separate as so many
disks. Moreover, such muscles occur- in other Invertcbrata besides Cnistacea,
and they therefore furnish no real ai-gument for allying Eotifera -with the
latter.

The nervous system lends no support to Leydig's views, as he professes it
does. A coalesced cerebral gangUon sending off nerves to depressions in the
cuticle aiTued with bristles, finds no analogy among the lower Crustacea, but
exhibits, on the other hand, an actual identity of structure wath the nervous
system of the TurbeUaria. The same resemblance is apparent among all the
Cestoidea, the Nemertm, Planaruc, and Trcmatoda. Again, the Uke degrees
of development of eye-specks, from a simple heap of pigment to a definite
organ with a refracting mediimi, is illustrated by all those sections of the
class Vermes, as Quatrefages shows in his figures of the Ncmerta:. The mode
of termination of the nerves described by Leydig in Eotatoria and Crustacea

OF THE ROTATORIA.

471

is also seen in Vei-mes ; and in general the organization of the nervous sy-
stem is much more in accordance with that of Cestoidea than with that of
the lowest Crustacea. Leydig remarks the great similarity of the maxillaiy
apparatus of young Daphnice with that of some Rotatoria, but forgets that a
similar structui-e occm-s in many Vermes. On the other hand, there are no
Crustacea which can, like several Mtommatce, protrude the maxillary organs
as prehensile instruments ; yet it is a common phenomenon with many Vermes.
Fui-ther, in no Articulata are the anus and rectum wanting, as happens with
some Rotatoria ; for although in the larva of Myrmeleo, as Leydig states, the
rectum is transformed into a spinning organ, still the viscus is present, though
modified for a different functional purpose : however, among Vermes such
an imperfect intestinal canal is common enough. From the preceding con-
siderations, the structure of the alimentary tube must be admitted to accord
rather with that of Vermes than with that of Crustacea.

The secreted solid matter ia the cloaca of embryo Cyclops, compared by
Leydig to the " urinaiy concretions " of Rotifera, is, however (unlike them),
produced originally of a green colour, within a sac on each side of the intestine,
but subsequently becomes yellow, and is discharged through the cloaca. Such
sacs or cells have rather the signification of a liver, and are common among
Vermes.

Leydig relies most on the phenomena of the sexual system and the occur-
rence of distinct male animals. But Polynoe, Exogone, and the Cystoneidce
produce both summer and winter ova, and carry them about. And with re-
ference to the existence of small distinct males, Krohn has proved it iu Au-
tolytus prolifer, whilst among Nematoid worms generally a marked difference
obtains between the males and females ; and what, indeed, can be more
stiiking than the difference between Distoma Olcenii and D. hcematohium'!
The variation iu form and stracture between the two sexes can therefore
furnish no differential character, seeing that it occurs alike in some Crustacea
and in most bisexual Vermes.

The occuiTcnce of a metamorphosis, and the shrivelling or obliteration of
the eyes, are phenomena common to Vermes and Cnistacea. The laiwal Ste-
phanoceros is equally comparable and similar to the occasional type of Annelid
larva, having a frontal ciliary wreath in advance of the eyes, or otherwise to
the larvae of Nemertidce, such as Alarclus caudatus, as to the embryos of any
Crustacea. "Wherefore all Leydig's characters, even where they indicate
some afilnity with the Crustacea, exhibit, at least, an equally close one with
Vermes.

The presence of vibratile cilia and the peculiar respiratory organs are, as
Leydig admits, circumstances approximating Rotifera to Annehda. A tor-
tuous canal mth ciliated tags occurs in none of the Articulata, and is incon-
sistent with the type of their water-breathing apparatus. At best there is
only a remote analogy, whilst a close similarity, and even an identity, is seen
between such structures and those of most Cestoidea.

The history of development is in favour of the Annelid alliance, and op-
posed to Leydig's hypothesis ; for in all Crustacea the embryo originates
from a primitive part superposed upon the yellv, whilst in Rotifera, in com-
mon with all Vermes, such a supplementary part is wanting, and the embryo
is generated from the entire yolk.

The appeal to metamorphosis lends its support to the present argument :
for no trace of resemblance is perceptible between the larva) of such Crusta-
ceans as undergo transformation, having tlu-oe pairs of jointed logs or feet, and
the embiyo stages of Rotatoria — for instance, of Stephanoceros, vnth ciliary
wreath, posterior bunch of cilia, lateral eyes, and vermiform trunk; yet in

472

GENEBAL HISTOEY OF THE INFUSOBIA.

all these particulars it, on the contrary, assimilates to the larvse of Vemcs,
between which and the adult state the diversity is equally great.

The accompanying tabular statement given by Vogt briefly presents the
chief points of the discussion.

SYSTEMATIC POSITION OP THE ROTATORIA.

Characters inconsistent
with Crustacea but in
accordance with Vermes.

1. Ciliary motion.

2. Vessels with cili-
ated tags.

3. Developmeut of
embryos from the
entire yelk with-
out primitive
part.

4. Typical structure
of the larvaa and
young, without
jointed locomo-
tive organs.

5. Total absence of
articulated limbs
in pairs during
their entire exist-
ence.

Characters common
to Crustacea and
Vermes.

An nutation of
the bodies
with telesco-
pic segments.

Structm-o of the
nervous sy-
stem and or-
gans of sense.

Maxillary ap-
paratus.

Formation of
eggs and
their carry-
ing about by
parent.
Dissimilarity
and imper-
fect organiza-

tion of
males.

the

Characters incon-
sistent with
Vermes.

Characters peculiar
to Crustacea.

Characters not ex-
clusive but common
to other chigses.

Formation of a
lorica.

Sti'ucture of the
muscles.

Structure of in- i
testinal canal.

Urinary secre-
tion (?).

Cohn's name may now be added to the list of opponents to the Crustacean
alliance. We have already seen (p. 447) that he denies the occun-ence of any
metamorphosis in the course of development of the Rotatoria, and by so
doing sets aside one indication Leydig brought forw'ard in faroui" of their
alliance with Crustacea. The following is a summaiy of his argiunents against
that relationship : — " The ciliated condition of the Rotifera, their respiratory
apparatus, theii- nei'vous system, the position of the intestine, and even their
general form, are all of them circumstances in favoirr of their affinity with
Vermes." Cohn can find no true articulations, but merely shallow folds of
the skin in the principal portion of the body ; and even the pseudopodiuni
and toes are not articulated motory organs (or limbs), but prolongations from
the common cavity of the body. The circumstance of his having united the
Tardigrada with the Systolidcs (llotatoria) indicates Dujardin's recognition
of the affinity of the latter -with Crustacea ; for in structure the Tardigrada
make an immistakcable approach to Arthropoda by the paii-s of limbs and
chain of ganghons on the abdominal surface, and to Arachnida also by tlie
Htractm-o and disposition of their digestive organs, by their suctorial mouth,
and by other details of organization. Their association -with Rotatoria, how-
ever, is not recognized by any other naturalist besides Dujardin ; and they
are generally placed amongst the lowest Arachnida, near the P)jcno(jtmi(t(r
and Acarincc (the lowest famiUcs of Arachnida) (see Section V., Of rm; Tak-
hioiiada).

A stUl higher affinity has been recently claimed for the Eotiitoi-ia by ilr.

OF THE EOTATORIA.

473

Gosse, viz. with Arthi'opodti and Insects. He supports this notion by an
appeal to the structure of the maxillary apparatus and to supposed analogies
of its several parts with the mandibles, jaws, &c., of insects. The " mastax
(see chapter on Digestive Apparatus) he identifies with a true mouth ; the
" mallei " with mandibles ; the " manubria " possibly with the cheeks, into
which the "mallei" are articulated; the "rami" of the "incus" with
maxilla; and the "fulcrim " he imagines to represent the " cardines " sol-
dered together. Wliile maintaining this connexion with Insecta through
the maxillary organs in their highest development, he suggests their afianity
Avith Polyzoa by the same organs at the opposite extremity of the scale, since
the oval muscular bulbs in BowerhanJcia approach and recede in their^ action
on food, and seem to represent the quadriglobular masses of Limnias and
Rotifer further degenerated. If this affinity be correctly indicated, the in-
teresting fact is apparent that the Polyzoa present the point where the two
great parallel divisions MoUusca and Articulata unite in their coiu-se towards
the true Polypi (see Mr. Gosse's valuable paper in the PhilosopMcal Trans-
actions, 1855). In a memoir since read before the lioyal Society {Phil.
Trans. 1857) by this same distinguished naturalist, the Crustacean alliance
is further insisted on upon the ground of the sexual peculiarities of the Eo-
tatoria. In this paper the author remarks that we must look, for a parallel
to the curious facts established concerning the dioecious character of Eotifera
and their peculiar males (see p. 455), to the Crustacea, " The economy of
the Hectocotylus of certain Cephalopod MoUusca, though perhaps even still
more abnormal, is only remotely analogous. Nor is the parallelism very close
of those Entozoa in which the males are organically united to the females, as
the genera Heteroura and Syngamus, described by Professor Owen.

" In the class Crustacea, however, many examples occur of a sexual differ-
ence, which may instructively be compared with the one before us. Thus,
among the Isopoda, we find the parasitic genera Bopyrus, Pliryxus, and lone,
in which the males are notably smaller than the females, very diverse in
foiin, and in some respects raferior in structure. In the Siphonostoma ' the
males are extremely small, and do not iu the least resemble the females,'
though those of different genera bear a strong resemblance inter se, even
when the females are very dissimilar. So low is their grade of organization,
that Burmeister has attempted to prove these minute creatiu'es to be embiy-
onic or larval forms. And, finaUj^, in the Cirripedia, Mr. Darwin has proved
the existence of males in the genera Ihla and ScalpelJum, which are very
minute as compared with their females, excessively abnormal in form, and in
some respects in an embryonic condition, though unquestionably mature, as
shown by the spermatozoa. And, what is still more interesting, the same
accurate zoologist observes — ' After the most careful dissection of very many
specimens, .... I can venture positively to assert that there is no vostio-e of a
mouth or masticatory organs, or stomach.' Again, ho describes the internal
structure as ' a pulpy mass with numerous oil-globules,' and the spunn-
vcsicle as ' a pear-shaped bag at the veiy bottom of the sack-formed animal
containing either pulpy matter, or a great mass of spermatozoa,' — terras which
might have been employed in describing some of the male BracJiioni.

" In all these analogies I conceive we may find additional reasons, to those
that have been before adduced, for assigning to the llotifera a zooloo-ical po-
.sition among the Articulata."

The attempt of Mr. Gosse to identify parts of the maxillary mechanism of
llotatoria with that of Insects, although praiseworthy, is in our opinion un
successful, and involves a consideral)lo stretch of imagination, ^lorcovor if
tlio idcntjfications, or more correctly sp(<aking the homologies, bo correct we

474

GENEEAL HISTOKY OF THE INFUSORIA.

do not see that this circumstance is per se adequate to establish an alliance
with the Insecta, particularly when, in most other respects, the differences
between the two groups of beings are so very considerable. Eeferring only
to the particulars mentioned in Vogt's critique, we may observe that if the
aberrations of organization of Eotatoria from the lowest Crustacea render
their alliance with the latter more than doubtful, still less possible is their
connexion with the highest Articulata, in which every differential character
becomes more developed.

The argrmients and illustrations of Vogt in favour of the close aflinity
of Eotatoria with Vermes will to most minds appear convincing ; but should
any demand further evidence, it is supplied by the opinions of the majority
of natm-alists and by the reasons adduced in their support. At present we
will confine ourselves to the views and arguments of Perty, Siebold, William-
son, and Huxley.

Perty enters into no discussion, but merely states generally that the posi-
tion of Rotifera with Vermes is indicated by their want of jointed feet in
pairs, and of a ganglionic abdominal chain such as Crustacea have, whilst, on
the contrary, they are provided with external voluntary and internal invo-
luntary cilia, after the type of Vermes. The class to which he would refer
them is that of the Thoracozoa (Arthrozoa).

Siebold affirmed that the affinity of Rotifera with the Crustacea is but
remote, since they are, he conceives, deficient of a distinct abdominal mem-
brane, of limbs in pairs, and of striped muscular fibre, — undergo no meta-
morphosis like Crustacea, — have organs of respiration (cilia) both externally
and internally, and an epithelium lining the alimentary tube, such as no Ar-
thropoda or Crustacea possess. Subsequent reseai-ch has invalidated a few
of the reasons put forward by Siebold, such as that of the absence of striated
muscles ; but the majority retain their force.

Prof. Williamson argues, from the particular instance of Melicerta, against
a Crustacean relationship. His words are — " In the possession of so highly-
organized a form of voluntary muscle, in the investment of the fasciculi by a
sarcolemma, and in the existence of a well-defined, ciliated, cellular epithe-
lium lining the alimentary canal, we have indications of an organization ap-
proaching that of the lower Articulata. The dental apparatus appears to
constitute a splanchno-skeleton, like that of the Crustacea ; but, on the other
hand, the absence of a visible nervous system removes the Melicerta far below
the Homogangliate animals. That they should possess a nervous system of
some kind appears almost a matter of necessity if the presence of a striated
muscular fibre indicates volition ; but its actual existence has yet to be de-
monstrated. I have foimd no special organs of circulation or respu-ation. On
watching the movements of the small free cells which float in the visceral
cavity, as well as in the tail, it becomes obvious that the fluid contained
within the integument moves freely mth eveiy contraction of the body. I
detect no vessels or pulsating organs. These facts also tend to associate the
animal with the Acrita rather than with the HomogangUate Crustacea. At
the same time its organization is of a higher tyije than that of the Bryozoa.
.... Again, many Vermes possess homy jaws not wholly imlike those of
Rotatoria, together with similar stomach-glands, equally resembling those of
some lower Crustaceans ; and, moreover, many Vermes, e. g. Chpsim, carry
their eggs about with them."

Prof. Huxley has very ably examined the question of the affinities of the
Rotatoria. Containing, as his opinions and illustrations do, many additional
facta, wo shall, at the risk of some repetition, add them to the preceding dis-
cussions and details. In the first place, ho adopts, as a group of the lower

OF THE HOTATOEIA.

475

Annulosa, under the name of Annuloida, the several families Annelida, Echi-
nodei-mata, Trematoda, Turbellaria, and Nematoidea, and in company with
these he would place the Kotifera. " The terms of resemblance (to the An-
nuloida) are these : — 1. Bands of cilia, resembling and performing the func-
tions of the wheel organs, ai-e found in Annelid, Echinoderm, and Trematoda
larvae. 2. A water-vasculax system, essentially similar to that of Eotifera,
is found in Monoecious Annelids, in Trematoda, in Turbellaria, in Echino-
derms, and perhaps in the Nematoidea, the Cestoidea, and the Nemertidas.
3. A similar condition of the neiTOUs system is found in Turbellaria, 4. A
somewhat similarly armed gizzard is found in the Nemertidse ; and the pha-
ryngeal armature of a Nereid lai-va may well be compared with that of
Alhertia. 5. The intestine undergoes corresponding flexures in the Echino-
derm larvae. There are therefore no points of their organisation in which
the Eotifera differ from the Annuloida ; and there is one very characteristic
circumstance, the presence of the water- vascular system, in which they agree
with them."

Prof. Huxley next proceeds to inqmi-e to which of the Annuloida the Eoti-
fera are most closely allied, and in so doiag seeks for the fundamental types
of their organization by an ingenious mode of demonstration, adducing the
genera StepJianoceros, Philodina, Notommata, Brachionus, and Lacinularia as
" the types of the great division of the Eotifera, and of which whatever is
true will probably be found to be true of all the Eotifera." The result he
arrives at is, "that the Eotifera are organized upon the plan of an Annelid
larva, which loses its original symmetry by the unequal development of various
regions, and especially by that of the principal ciliated circlet or trochal
band." After some further remarks. Prof. Huxley adds — " I do not hesitate
to draw the conclusion " (which at first sounds somewhat startling) " that
the Eotifera are the permanent forms of Echinoderm larvce, and hold the same
relation to the Echinoderms that the Hydraform Polypi hold to the Medusae,
or that Appendicidario} hold to the Ascidians.

" The larva of Sipunadus might be taken for one of the Eotifera ; that of
Ophiura is essentially similar to StepJianoceros ; that of Asterias resembles
Lacinularia or Melicerta."

Again, this talented naturalist believes that the Eotifera furnish the Ii'tiTt
between the lower Echinoderms (which otherwise seem to lead nowhere)
and the Nemertidse and Nematoid worms, the Eotifera themselves forming
the lowest step of the Echinoderm division of the Annuloida, the proposed
subkingdom of Cuvier's Eadiata.

To elucidate his views, Prof. Huxley has appended to his essay a series of
diagrams showing the essential correspondence between Eotifera and Annelid
or Echinoderm larvae.

When Lcydig wrote his memoir on the Eotatoria, ho had the advantage of
seeing this contnbution to their history by Prof. Huxley, and has remarked
m general terms, of the above views and their Ulustrations, tliat althou"-h the
ingenmty of the attempt to prove Eotatoria permanent larva) of Echinoderms
must be admitted, he is nevertheless imable to adopt the hypothesis of the
English observer, and must hold to his own idea of their Crustacc-m ohn
racter.

The conclusion which it seems to us must be adopted is, that the Eotatoria
belong to the great group of tho Eadiata knoAvn as Vermes, and stand i^
more particular relation with those families which make up the piX)posed cU^
vision "Annuloida." ^ "jj^olu lu-

We must now add a few observations concerning the affinity exhibited bv
the Eotatoria with the Ciliobrachiatc Polypes or Bryozoa (a family of Polyzoa)

476

GENEKAL niSTOllY OF THE INFUSOKIA.

This affinity is particularly marked in the genus Stephanoceros on the part
of the Kotifera, and in that of BowerbanJcia on the side of the Eryozoa,
The members of the latter genus live in an elongated tubular case, and have
themselves an elongated, rather club-shaped figure. The case is transparent ;
its upper portion is soft, so that it can close over the animal when retracted!
The head of the Bryozoon is armed with several long processes or tentacles
similar to those of Stephanoceros, which are clothed with cilia and spines ;
and the margin of the head itself is also ciliated. This whole armatui-e is
retractile. Muscles are distinguishable, moving the several parts. The di-
gestive system comprehends a mouth, oesophagus, gizzard, stomach, a gastric
tube or pylorus, and an intestine, lined with cUia, returning upwards, so that
the anus opens near the mouth. The lining membrane of the gizzard is
moreover finished with many horny teeth, seated on oval muscular bulbs,
which, according to Mr. Gosse (see p. 473), "approach and recede in their action
on food, and seem to represent the quadriglobular masses of Limnias and Ro-
tifer further degenerated." The Bryozoa as a class ai-e reproduced by three
modes: 1. by ova; 2. by ciliated gemmules; and 3. by budding (gemma-
tion) from the common stem or polypidom where they grow. The second
mode is not met with in BoiuerhanJcia, but only in species having fleshy or
gelatinous polyparies (e. g. Halodactylus), where the ciliated gemmules occur
in sacs, which appear as whitish points imbedded in the general mass. Is there,
we may ask, any analogy between these and the winter ova of Eotifera, which
are in some cases cihated or hairy ? The ovary producing the ordinary ova
is placed close above the stomach ; and contiguous to it is the testis, filled with
spermatozoa. The ova when ripe escape into the general cavity of the body,
where they are surrounded and impregnated by the spermatozoa ; and after
several have accumulated about the base of the tentacles, they are at length
discharged through the anus. The ova are remarkable from their irregularity
of shape. The embryo escapes as a fi-ee being, not unlike some cOiated Pro-
tozoon, but by-and-by it fixes itself, produces its pedicle, and assumes the
form of its parent.

On comparing this description of BoiuerhanJcia with that of StejpJunwceros,
the points of similarity between the two are veiy many and stiiking. The
points in which Bowerhanlcia chiefly diff'er are — 1. its character as a member
of a compound mass or polypary from which it may itseK have gi-own as a
bud, whilst reproduction by gemmation is unknown among Eotifera ; 2. the
position of the ovary above the stomach, in close proximity, with an evident
testis ; 3. the apparent absence of an oviduct, and the consequent escape of
the ovum, followed by its fertilization, within the general cavity of the body ;
4. the imperfect development of a maxillary apparatus ; 5. the absence of a
water-vascular system ; 6. the greater length and stLfihess and more slender
figure of the tentacles or arm-like processes of the head ; and 7. the different
disposition of the cilia upon them — for these in Stcplianoceros are arranged
in little bunches or whorls at short distances from each other.

But several of these distinctive particulars lose much of their force from
other corapaiTsons and considerations. Thus the absence of an o^^duct is
admitted as an occasional event in Eotifera ; and the escape of the embrj-os
into the general ca\dty of the body has been stated by many obscrvoi's to
occur in Stephanoceros ; Leydig, however, denies this ; yet the bii'th of the
young in Philodhia and their active life "ttitliin the body of tlie parent may
present the analogy in request. It cannot be affirmed \vith certainty that
BoiuerhanJcia is uniiko StepiJianoceros in having a testis in company with the
ovary ; for no male SfepJianoceros has yet been found, and some doubtful
Htructurcs have been by some assumed to represent the testicle. To cilc yet

OF THE KOTATORIA.

477

another circumstance, a water- vascular system is indistinct in Stephanoceros,
and would be overlooked, as Leydig remarks, did not the knowledge of its
form and of its existence in other Eotatoria dii-ect in the search for it ; and, on
the other hand, such a structure has not been sought after in BowerhanUa.

These and other considerations, which might easily he added to, lessen the
differential characters, and, together with the many undoubted points of re-
semblance between Boiverhcmhia and StepJianoceros, incLLne us to the veiy
prevalent opinion that there is a real affinity between Eotifera and Bryozoa,
although we would not go so far as some naturalists and place the genus
Stephanoceros among the latter.

Huxley entertains an adverse opinion, and beHeves that " there is a funda-
mental error in approximating the Polyzoa and the Eotifera at all, that the
resemblance between Stephanoceros and a Polyzoon is very supei'licial, and
that the relations between the Polyzoa and the Eotifera are at the best mere
analogies."

The resemblances between the Eotatoria and the Ciliated Protozoa are
merely superficial. Vaginicola is enclosed in a transparent sheath, Kke a
Floscularia or a Tuhicolaria ; the urceolated individuals of Ophrydium are
grouped into gelatinous balls, Like those of Oonochilus ; the ciliaiy wreath
about the head of Yorticella, Stentor, and Vaginicola makes an approxima-
tion to that of Eotatoria ; and the contractile muscular pedicle of Vorticella
and ZoQthamniwm recalls, in some respects, the retractile pedicles of the fixed
Eotatoria.

A connecting link is, however, supplied between the Ciliated Protozoa and
the Eotatoria by most genera of the family Iclithydina, which Ehrenberg
indeed numbered among the latter class. This great microscopist had but an
imperfect acquaintance with their organization ; and at the present time our
knowledge of it is far from complete. The genera referred to are Iclithydium
and Oliwtonotus ; and perhaps Mr. Gosse's genus Sacculus should be united
with them. The genus Glenophora of Ehrenberg is not recognized by most
naturalists.

They differ from Eotatoria in having no transverse joints or folds to the
body, no water-vascular system, no appreciable muscles or nerves, whilst
the ciHary wreath is on the model of COiated Protozoa, and the alimentary
canal after the type of that of Nematoda and of Anguillula. The vibratile
cilia extend also over the abdominal sm-face of Ichthydium, and over both
the ventral and dorsal of Chcetonotus. Lastly, according to M. Schultze they
are hermaphrodite, and have pin-shaped spermatozoa. These peculiarities of
organization have induced observers generally to exclude these genera from
Eotatoria. Dujardin has found a place for them along with Ooleps ; and a
doubtful subgenus he named Planariola, as a subclass of Ciliated Protozoa
unlike the rest of this class in being symmetrical. '

Another link between Eotifera and the Ciliata is to be found in the peculiar
genus Dysferia, which Prof. Huxley referred to the Euplota, and Mr. Gos'so
to the Monocercadece among the Eotatoria (see p. 387).

Classification. — Since no observcra, prior to Elu-enberg, duly recoo-nized
the Eotatoria as a class distinct from the Protozoa, we may at once commence
with an analysis of the classification he has proposed.

This was based on the apparent stracturc of the rotaiy organ, of which he
distinguished two types : 1. in which the cii-clet of cilia is complete— J/oho-
irocha ; 2. in which it is divided into two or more f^esmonU—SoroirocJia
Each typical fom was subdivided ; the first into Hohtrocha, in whicli the
ciliated ring is entire, and Schizotrocha, in which the wreath is notched The
second (Soroirochr,) into Polytrocha, with a compound wreath of several lobes-

478

GENEHAL HISTOEY OP THE INFUSOIllA.

or secondary circlets, and into Zygotroclia, where the organ consists of two
(a pail' of) symmetrical wreaths.

The further division of these sections into families was founded on the
cii'cumstance of the animals being either loricated or not loricated ; and the
distribution into genera was made, primarily, according to the number and
disposition of the red eye-specks, and in a secondary degree, according to
the characters of the jaws and teeth, or of those of the foot-process, or other-
wise, more rarely, of the lorica.

This classification we present in a tabulated form for convenience of
reference.

CLASS EOTATORIA, ACCOEDING TO EHREITBERG'S SYSTEM.
SECTION I. MONOTEOCHA.

FAMILIES.

GENEEA.

(

Illoricated :
thydina

Ich-

Loricated : Qilcistina

eyes absent fi • t , f with truncated foot Ptygura.

I nair aDsent | ^^^^ ^^^^^^ ^^^^ Ichthydium.

[ hair present Chaetonotus.

eyes present Glenophora.

f loricee distinct CEcistes.

\ loricae agglomerated Conochilus.

/'th • i J r eyes absent Cyphonautee.

lUoricated: Mega- I [one eye Microcodon.

lotrochsea |^ eyes present ••• | eyes Megalotrocha.

/' eyes absent

one eye (when

Loricated : Floscu-
larisea

young)

two eyes (when
young) ..

rotary organ bifid |

rotary organ 4-fid
rotary organ 5-6-fid

urceoli distinct

urceoli agglomerate

Tubicolaria.

Stephanoce"

Limnias.

Lacinularia.

MeUcerta.

Floscularia.

a

•I

SECTION II. SOEOTEOCHA.

Division I. Polyteocha.

r no teeth

eyes absent \ , J" jaw many-toothed

[ "[jaw one-toothed

'frontal

/'foot styHform

{frontal cUia alone
do. with styles
do. with uncini
foot absent ; body with lateral cirrhi. .

foot furcate

1. i. i_-Ti- f ciri'lii on neck

foot styhform | ^^^.^.j^^ wanting

cervical . .".foot furcate

one eye

two eyes

cervical

frontal .

three eyes

eyes numer-
ous

Euchlanidota. . . eyes absent

Enteroplea.
Hydatina.
Pleurotroclia.
Furcularia.
Monocerca.
Notommata.
Synchffita-
Scaridium.
Polyarthra.
Diglena.
Triarthra.
Eatulus.
Distemma.
Triophthalmus.
Eosphora.
Otoglena.
Cvcloglena.
Theorus.
Lepadella.
Monostyla.
Mastigocerca.
Euchlanis.
Sal pin a.
Dinocharis.
Monura.
Colunis.
Metopidia.
Stephanops.
Squamella.

OP THE ROTATORIA.

479

FAMILIES.

Pliilodintea

eyes absent -

eyes present

' eyes absent.

BracMonsea

Division II. Zvgotrocha.

GENERA.

with a proboscis and foot-processes Callidina.

without proboscis ; no f ^.^^ ^ pedicled ... Hydrias.

^ I'l^- processes I not pedicled TyphUna.

foot with horn- f terminal toes two . . . Rotifer.

like processes \ do. three Actimirus.
foot without such processes ; terminal

toes two Monolabis.

cervical " PMlodina.

foot furcate Noteus.

horn-like
on the foot

two frontal

two

eyes present

, • IN f foot absent Anursea.

one (cervical) | ^^^^ ^^^^ Brachionus.

two (frontal), foot styUform Pterodina.

Many serious objections attach even to the fundamental principles which
Ehrenberg has adopted in his systematic distribution of Eotifera. Leydig
has weU argued against the existence of an actually compound trochal disk
(p. 398) ; and to designate the peculiar ciliated organs of Ploscularia and
Stephanoceros simple notched wreaths is certainly a misnomer, and conveys
an erroneous impression.

The employment of the " loricated " and " lUoricated " condition, as un-
derstood by Ehrenberg, in the construction of families, is even more faulty ;
for, as before observed (p. 394-5), he uses the term " lorica " so loosely, that
it designates no one special structure. The existence and position of eye-
specks, as characteristic of genera, are very uncertain and iasufficient. These
coloured specks, especially when numerous, are not constant either in number
or position ; they disappear with age in numerous instances, in some even
before the adult condition is attained ; they may be deficient from various
external circumstances of development ; and, in general, they have not that
importance in the organization and life of the Eotatoria which can warrant
their employment as generic distinctions. The formation of the jaws and
the number of the apparent teeth might afford valuable characteristics ; but
they are facts difficult of determiuation on account of the minuteness of their
parts. Prom the above considerations it is evident that the descriptions of the
Berlin Professor are open to much question, and the generic characters based
on them uncertain.

That this artificial system of Ehrenberg is erroneous, is also evidenced by
the separation of undoubtedly allied forms which it often entails. This evil
involves another, that of the unnecessary multiplication of genera and of di-
stinctive names. ThiLs Dujardin rightly insists on the erroneous distribution
of a naturally single genus, from the really unimportant variation in the
number of coloured specks, into the several genera Lepadella, Metojoidia
Stephanops, and Squamella ; and also indicates the division of the families
Philodinaa and Hydatincea as carried too far. On the other liand the ex
tensive genus Notommata comprehends many very dissimilar animals, includino'
for instance, not only such as possess the typical aUmentary canal of the
Eotifera, but also those recently discovered forms tliat diverge from that tvue
in wanting a separate anal outlet. Such a genus requires revision The
same may be said of the genus Diglena. In the opinion of many naturalists,
the Berlm Professor falls mto an additional error in admitting the familv
Ichthydma among the Eotatoria. In fine, the result of modern icsearch is to
caU equally m question several of the subdivisions and genera which he ha.^
in.stituted.

Although the defects and errors of Ehrenborg's system bo generally ad-

480

genehal msToiiY of the infusohia.

mitted, yet several writers, such as Siebold, Perty, and Gosse, have been con-
tent to employ it in the absence of a better. Indeed, before a con-ect natural
classification of the Eotatoria can be made, the organization of each inde-
pendent form must be investigated, and the signification and relative import-
ance of its parts determined.

Various temporary arrangements have been suggested. Ehrenberg himself
indicated a division of the class according to the form and disposition of the
alimentary canal, and another according to the structure of the dental appa-
ratus. Both these are unsatisfactory and artificial ; and even their author
was compelled to admit that genera and species were thereby associated in
alliances quite different from those they occupied in his accepted system.

Dujardiii considers that, " in the present state of science, we do not possess
the elements of a definite classification ; " and therefore proposes, as a merely
provisional scheme, four grand divisions of the Eotatoria, including the Tardi-
grada: viz., 1. those which live fixed by theii' posterior extremity; 2. those which
have but one mode of locomotion, and are always swimmers ; 3. those which
enjoy two modes of progression — by crawling, after the manner of leeches, and
by swimming ; 4. those which creep by moveable imeini on their lower sm--
face, and are destitute of cUia. It is the Tardigrada which constitute this
fourth division ; and they so far diff'er from Eotatoria, particularly in the ab-
sence of a ciliaiy apparatus and the presence of rudimentary feet, that theii-
alliance with the latter is generally objected to ; even Dujardin himself views
it as of doubtful propriety.

The classification of Dujardin, omitting the Tardigrada, is as follows : —

Families.

, _. , J, r FLOSCULARrEXS.

1. Fixed forms \ Melicertieks.

I Braciiioniens.

2. Having one mode of locomotion, viz. by swimming < Furc0lariens.

[ AliBERTIEXS.

3. Having two modes of locomotion: 1. by swimming ; 1 ■g^^^jp^.^^^g

2. by crawUng J

For the ftu'ther division into genera we must refer to Dujardin's work.
The system, as Leydig remarks of it, is founded on a correct principle, and
recommends itself by its simplicity. The groups of individuals it brings
together generally consort by natural aflB.nities ; stiU some are exceptional and
abeiTant, and occur as disjecta membra.

Leydig makes the attempt to form a division, primarily according to the form
of the body, and secondarily, to the nature and the jiresencc or the absence
of the foot-process. There are three primaiy foi-ms : — 1. in which the figure
is club-shaped or cylindrical ; 2. in wliich it is sacculai- ; 3. in whicli it is
compressed. The accompanying plan represents in fuU the system in ques-
tion. The Ichtliydina are omitted.

LEYDIG'S CLASSIFICATION.

A. Figure club-shaped or cylindrical.

I. With a long, transverscli/ wrinldcd, attached foot.

In this section arc comprised the families (Ecistina, Mpgalotroch<pa, and
FloscidaricEa of Ehrenberg, excepting the genera Pti/gxra, Glcnophorn.
Cyphonatdcs, and Microcodon. The last belongs to another section :
and the other three are uicomplete forms.
II. With a long, jointed, telescopic, and, retractile foot.

Is represented by the family J'hilodinaa (Ehr.).

III. With a long, jointed, not retractile foot.

Includes" the genera Svaridium and Dinocharis (Elir.).

IV. With a short foot and long foot-jjroccsacs.

Includes the genera 'Monocerca. Furctdaria, and Microcodon (Ehr.), and tlie

I OF THK ROTATORIA. 481

species Notmmata Tigris and N. longiseta (Elir.). Leyclig surmises that
Microcodon is a male animal.
V. With a short foot ; the foot-j^rocesses equal to the foot in length, or but slightly
shorter or longer.

Comprises tlie genera Hydatina, Pleurotrocha, Biglena, Bafulus, Bistemma,
Trio'phthalnms, Eospfiora, Ci/cloglena, Theorus, SyncluBta (Ehr.), and
lAndia (Duj.) ; together with the species Notommata Tuba, N. petro-
myzon, N. saccigera, N. Copeus, N. centrura, N. brachyota, N. collaris,
N. Najas, N. aurita, K gibba, N. ansata, N. decipiens, N. Felis, N. para-
sitica, N. tripits (Ehr.), N. tardigrada (Leydig), N. vermicularis (Duj.),
N. roseola and N. oniscifomiis (Perty), and the Furcularia Wieinhardtii
(Ehi-.), wliich is, however, actually a Notommata. The genus Lindia
(Duj.) is doubtful ; and that of Enteroplea (Ehr.) is the male of Hyda-
tina sent a.
VI. Without a foot.

Is represented by the genus Alhertia (Duj.).

B. Figure saccular.

I. With a short foot.

Such are the species Notommata clamlata?, N. Myrmeleo, N. Syrinx, and
Biglena lacustris.
II. Without a foot.

Includes Notommata anglica (Dalrymple), N. Sieboldii (Leydig), Polyarthra
platyptera (Ehr.), and the genera Triarthra (Ehr.) and Ascomorpha
(Perty).

C. Figure compressed.

a. Compressed horizontally.

I. With a foot.

Eepresented by the genera Euchlanis, Lepadella, Monostyla, Metopidia,
Stephanops, Sqiuanella, Noteus, BracMonus, Pterodina (Elir.), and
Notogonia (Perty).
II. Without a foot.

The genus Anurtsa (Ehr.).

b. Compressed laterally.
Includes the genera Salpina, Mastigocerca, Montira, and Colurus (Ehr.).

This arrangement of the Eotatoria the author confesses to be defective.
In our opinion, it has no advantage over the scheme of Dujardin, and, on
the other hand, wants its simplicity. Its basis is not such as will combine
the species according to their natural affinities ; for there is no necessary or
direct relation between external form and internal oi-ganization, and it is on
the latter alone than any classification can securely repose.

482

oknehal history ov 'mv. infusoria.

Sect. V.— OF THE TARDIGRADA.

Theie Strtjctuee, Habitats, and AiriNTTiES. — The Tardigrada or Tardi-
grades (in German, Wasserbdren, lit. luater-hears) constitute a small group
of animals, fli'st noticed by Eichhorn, and latterly more fully investigated by
Doyere, Dujardin, and Kaufmann.

Their size is so considerable (from ^th to -^th of an inch in length) that
they are visible to the naked eye. They have oblong, symmetrical, non-
ciliated, and very contractile bodies, admitting of their roUing themselves into
a ball, and of otherwise vaiying their figiu'e. The head is somewhat pro-
duced, assuming a conical or pyi-amidal figure ; but they have no pseudopo-
dium or other posterior process.

They are invested by a resistant, fii'm, and sometimes homy integument,
composed of two layers. The firmness is due to the chitinous composition of
the external lamina or cuticle, which is not affected by caustic alkali. In
Emyclium, M. Doyere describes the integument to consist of foiu' homy
plates. During contraction, the integument is thrown into transverse folds,
and the anterior and posterior segments reti-acted. Its surface is generally
smooth ; but in Emydium there are a few pretty regularly disposed bristles
(setse) on the back and sides ; and in tbe neighbourhood of the mouth there
are, as a rule, several soft flexible processes, palpi or antennae. Numerous
and definite muscles extend between the inner skin or epidermis and the
various organs and members.

The under or abdominal sui-face is clearly distinguished from the dorsal by
the presence of four pairs of radimentary feet without joints, each consisting
of a nipple-like (mammilliform) process supporting on its extremity from two
to four well-developed curved and acute uncini or hooks. These are the
locomotive members by which the animals crawl upon and adhere to solid
substances.

The head is without a trochal disk or ciliary wreath, vibratile cUia being
entirely wanting. The mouth, opening at its extremity, in the median line,
is modified so as to form a sucldng-tube ; it is naiTow, and di'awn out to a
more or less fine extremity ; it is bounded on each side by a lateral, rigid,
horny, narrow or lincaa* process — the maxilla, which is moveable upon a
single or double central piece or fulcram. The whole organ constitutes a
tube-like sucker, and is protrusile at will beyond the head, like the suctorial
mouths of Acari and Insecta. On each side of the mouth are the small re-
tractile palpi already noticed.

The mouth opens posteriorly in a pharyngeal muscular bulb, furnished
internally with a homy articulated dental apparatus, serving to crush food, but
less highly organized than in Rotifcra. Under the polarizing microscope the
manducatory organs exhibit the same appearance as hom. From them the
food passes into an elongated tubular stomach or intcstuie,_continucd straight
through the body, and terminating in an anus at the posterior extremity. In
its course it presents numerous lateral offshoots or diverticula.

No form of respiratory or eii-culatoiy apparatus lias been detected ; but a
multitude of granules and coqniscles are seen to float freely in the general
cavity between the integument and the alimentary canal, wliich Doyere sup-
posed to be concerned in the processes of nutrition, and to be analogous to
blood-coi-pusclos. M. Quatrefagcs states that the fluid ^^^thin the body is in
perpetual irregular motiou.

f OF XHE TABDIGBADA. 483

The nervous system is well developed. It consists of a chain of ganglia,
with intercommunicating (anastomosing) nerve-fibres, besides a central or
cerebral ganglion.

The eyes are variable and fugacious. The sense of touch may be presumed
to reside specially about the suctorial mouth and its contiguous palpi. All
the Tai-digi-ada are hermaphrodite. The ovary is of large size ; but the ova,
according to Kolliker and Prey, do not in the coui'se of development exhibit
a germinal disk : in this they differ from Ai-thi'opoda. Pew eggs are pro-
duced at a time, and are of large size. They are, curiously enough, found in
the exuvise or moultrngs of the animals ; for from time to time the outer skin
is cast off. M. Doyere convinced himself of the existence of a testis and
spermatozoa. Dujardin says the embryo emerges from the ovum perfect in
form ; but Kaufmann, on the contrary, afiu-ms that they undergo some de-
gree of metamorphosis ere they attain the adult stmctiu-e.

The Tardigrada have received their name from their slow movements. They
are parasitic animals, and live by sucking the juices from other beings. They
are common upon water-plants and vegetable debris in ponds ; yet immersion
in water is not necessary, since they axe found, like Rotifers, in the dust and
rubbish on the roofs of houses (a locality in which they were first encountered
by Spallanzani), and especially amid the small lichens, mosses, &c., which
spring up in such situations. The Brywm is a favourite moss for these crea-
txu'es. On shaking poriions of this or of other mosses or aquatic plants in a basin
of water, the Tardigrada wiU fall to the bottom, and may be easily collected.

In most vital phenomena they very closely accord with Rotatoria ; thus,
like these, they can be revived after being put into hot water at 113° to
118°, but are destroyed by immersion in boiling water. They may be gra-
dually heated to 216°, 252°, and even 261°. It is also by their capability
of resuscitation after being dried that they are able to sustain their vitality
in such localities as the roofe of houses, where at one time they are subjected
to great heat and excessive drought, and at another are immersed in water,

0. Miiller (in 1785) seems, from the name {Acarus Ursellus) which he
imposed on the species he then knew of, to have rightly conceived their
natural affinity, Ehrenberg and Schultze (1834) placed them among the
Lemece. Dujardin (in 1841) advocated their alliance ^vith the Rotatoria, and
constituted them one of the divisions of that class, under the name of " Sy-
stolides Marcheurs," or creeping Rotatoria ; for he considered them to form a
link between the Rotatoria and the Hehninthidte on one side, and the Anne-
lida and Arachnida on the other. M. Doyere at first coincided in this opinion ;
but his subsequent researches led him to give it up and to constitute the Tai'-
digrades a distinct group. Dujardin himself has, moreover, modified his first
opinion, as appears by his memoir in the Annales des Sc. Nat. for 1851 •
for he there remarks that the Tardigrada are equally allied to the Rotifera
and to the Ncmatoid Helminthidae, and that it is uncertain wliethcr they
ought to be referred to Articulata or Vermes. Our countryman Mr. "Wliite
(in a paper read before the Linnean Society in 1851) stated his belief " that
the so-called Acarus folUculorum, and probably also Tardigrada, are parasitic
Rotatoria, with legs or leg-like appendages adapted to their peculiar habits,
and that their retractile, antenna-like, subtelescopic appendages may have
eyes passing through them, as in snails, and may also bo the equivalents of
the rotce (rotaiy lobes), but, from the limited, or rather the absolutely re-
istricted, power of motion of these animals, have neither the ciliary processes
inor the movements and economical uses of the appendages so characteristic
lof most of the Rotatoria."

Perty tells us that in 1848 he constructed a family Xenomorphida; which

2 I 2

484

GENERAL niSTORY OF THE INFUSOIUA.

was accepted by Ehvenborg, to comproliend the Tardigrada, the best-known
of which were inchided in a genus Aretiscon, so named by Schrank. His
opinion now is, that " perhaps they should rather be associated with the class
Arachnida, as a lower type, near the Acarina)," and not be numbered with the
Crastacea, as he formerly proposed. " Doycre's figures of Emydiurn indicate
their alliance with the Acaiinae, like many of which the Xenomorpliklce (Tar-
digrada) suck the juices of other animals. Their development diifers from
that of Rotifera ; and their skin is composed of chitin." lliis last distinction,
also insisted upon by Kaufmann, vanishes if Leydig be correct in his state-
ment that Rotatoria likewise have a chitinous cuticle.

The most recent writer on Tardigrada we have met with is Kaufimann
(Zeitschr. 1851, p. 220), who has presented an able memoir on those berags.
He indicates the following distinctive features between them and Rotatoria :
— The history of their development accords with that of Ai-thropoda, and
disagrees with that of Rotifera : the epidermis is composed of chitm, a sub-
stance only found in Arthropoda (this we have already stated is probably an
error) ; the pairs of indistinctly-jointed Umbs and the abdominal chain of
ganglia no Rotifer possesses, whilst, on the other hand, the Tardigrada have
no trochal disk and no vibratile cilia, but possess a suctorial mouth ; lastly,
they are deficient of a water- vascular system, and are aU hermaphi-odite.

Cohn, in a recent paper (Siebold's Zeitschrift, 1855, p. 481), thi'ows some
doubt on this presumed monoecious nature of the Tardigrada. Thus, he says,
Doyere, whilst maintaining their hermaphrodite character, has noticed seminal
corpuscles (spermatozoa) in only two individuals. On the other hand, he men-
tions certain examples in which the oral organs were aborted, and both sucto-
rial disk and maxillary head were wanting ; this happened most fi-equently
in Macrohiotus Hufelandii, and more rarely in other species. Another notable
fact is, that in the two closely-allied species, Macrohiotus Hufelandii and
MacT. Oherliauserii, the ova of one are thick-shelled and tuberculated, and
those of the other thin-shelled and smooth. In these circumstances Cohn
is disposed to find a parallel between Tardigrada and Rotatoria in what
relates to their sexual peculiarities, — ^inferi-ing by this, that, as in the latter
family the sexes are separated, and ova of thi-ee sorts — male, " siunmer "
(asexual), and "winter" — are produced, so, from the facts indicated, the
Tardigrada may also be bisexixal (dioecious) and may deposit eggs of each
several land.

The relation of Tai'digrada to Ai-achnida through the lowest divisions of
the latter, Kaufmann proceeds to demonstrate by the foUowing particulars : —
They have suctorial mouths, like most Acari ; in the stracture and disposition
of the digestive organs they agree with Arachnida ; by the absence of circu-
latory and respiratory organs they arc allied to the Acaiina in part, and to
the Pycnogonidce entirely ; like many mites (Acarina), they lay few and
largo eggs. But, again, the occurrence of a metamorphosis to some extent
detaches them from the Pycnocjonidce and from most Acarina ; and they
differ from all Arachnida by being hermaphi-odite ; liowever, the cii-cumstance
of the separation of the sexes, or their union in the same individual, in no
class of animals can supply the basis for constituting family distinctions.
Even among Arthropoda a family of hermai)hi-odito animals occurs, viz. the
Cin-ipedia. In this respect the Cnistacea and Arachnida, by their lowest
members, through which they are linked to other classes of animals, accord:
in the former the Cirripedia, wliich aUy them witli the Slollnsca, — in the
latter the Tardigrada, which approximate the Arachnida to the Annelida,
bring the two into connexion.

The conclusion therefore is, that' the Tardigrada constitute the lowest
section of the Arachnida, by the side of the Piienogonido' and the Acarina.

PART II.

A SYSTEMATIC HISTORY OF INFUSORIA.

[Note. — The several groups whose general history is treated of in the fli-st part of this
work, viz. Bacillaria (p. 1), Phytozoa (p. Ill), Protozoa (p. 199), and Rotatoria (p. 392),
being independent of each other, their respective families, genera, and species will not, for
the reason stated in the Preface, be described in the same order in this second part, but
those of the Bacillaria will be printed last. For an explanation of abbreviations, see end
of Contents.]

OF THE GROUP PHYTOZOA (p. 111).

Families: — 1. Monadina; 2. Hydromorina ; 3. Cryptomonadina ;
4. Volvocina; 5. Vibrionia; 6. Astasisea.

FAMILY 1.— MONADINA.

(Plate XVIII. figs. 1 to 28.)

The Monadina are among the most minute living creatui'es which have been
discovered by man. They are (according to Ehrenberg) destitute of an ali-
mentary canal, are dloricated or sheU-less, and have a uniform body without
any appendages issuing from it, cilia not being considered as such. They
increase by simple and complete self-division into two, four, or more indi-
viduals. The uniformity or unvarying appearance in their external form (he
says) may be considered as one of the principal characteristics of this family ;
for no one of the Monadina can voluntaiily alter the shape of its body, whether
into a filifoi-m, knotty, or globidar figure, nor can it extend any poi-tion of it,
and then contract it again. AU possess organs of locomotion, nutrition, and
propagation, the last of the hermaphrodite character. Some of them have a
rudimentary eye ; but it has never been discerned that they are furnished yvith
a vascular or circulating system, which, however, is not surprising when we
reflect that, should they possess it (a supposition by no means to be rejected),
the diameters of the tubes of this system would necessarily bo of such extreme
minuteness as to defy investigation. None but microscopes of high magnify-
ing powers can display their structm-e ; indeed they cannot bo observed
accurately with a less amplification than 500 diameters, by glasses of consi-
derable penetration and good definition.

The apparent eye of some Monadina is used as a generic chai-acter for
Microglena (XVIII. 6), Phacelomonas, &c. ; but its possession does not prove
the existence of sensibility, although, as Ehrenberg thinks, this facidty is pre-
sumable from the alternate vibration and quiescence exhibited by the pro-
boscis when one of tluise beings is in a place abundantly supplied with food

The details given in the first part of tliiswork (p. 130),of the natnre and struc-
ture ot the animalcidcs comi)nHcd by Ehrenberg in this famUy, render it unne-

486

SYSXUMAXIC niBIOKl- OF THE IHFUSOfilA.

cessary here to state more than that the beings so grouped together are hete-
rogeneous both in nature and character, and partake scarcely any other featui-es
in common than those of minuteness and the possession of one or of few elon-
gated ciUa or filaments as locomotive organs. The deficiency of characteristics
necessary to constitute a natural family, and the absence of any proof of the
animality of the several genera, were perceived by Siebold, who rejected the
Monadiaa from his group of Infusoria. Agassiz says of them that they are
mostly moveable germs of various kinds of Alga3 ; and in this statement, wc
believe, as far as relates to the majority, he is correct. Dr. Burnett (Boston
Journ. Nat. Hist.lSdSfYi.'p. 319) has the foUowing remarks on these topics : —

"As the family Monadma now stands, it imdoubtedly includes very hetero-
geneous elements, particles being gTouped together from theii- general aspects
rather than from their physiological characteristics. I cannot pretend to take
them up in that systematic way in which they have been arranged by Ehren-
berg ; for I have found but little system about them, and for the most part
have been unable to follow his descriptions. If we are to judge of them by
mere form and size alone, I should say that the varieties they present under
the microscope are numberless. Indeed, in watching the same particle for a
long time, I have seen it change its form and size four or five times, and each
as distinct from the other as many of Ehrenberg's species. Those which con-
tain chlorophyll must, it appears to me, in virtue of that fact, be regarded
as of a vegetable nature. As to the others this point would be doubtful."

Again, Dujardin, whilst admitting generally the animal nature of the ge-
nera in question, differed widely from the Berlin natui'alist both as to their
organization and distribution. Siace, however, ia the present state of our
knowledge, it is impossible to fijc on the organisms of which they are but de-
velopmental phases, it is well, for the purpose of futui'e identification and
future researches, to attempt definitions and descriptions of these simple
beings, although, as an artificial and temporaiy proceeding, the whole he
doomed to ultimate neglect and destruction. Consequently, we shall retain
all Ehrenberg's genera and species, which, however ill-defined and unsatis-
factory, give the best representation we possess of these varied and variable
microscopic organisms.

The views of Ehrenberg on the special organization of the Monadina have
been widely criticised and condemned. The possession of an integimient, the
fixed invariable outline, and the ocular natiire of the red speck, are statements
which have encoimtered the opposition of Dujardin and of very many subse-
quent naturalists. The existence of a mouth and the reception of coloured
food have likewise been widely denied, in accordance with the prevalent
hypothesis of their vegetable nature as early phases of Alga; and Fungi ; but
latterly Cohn has witnessed the entry of coloiu-ed particles into their interior, —
a circumstance confixmed by Lachmann, who moreover adds that he has twice
observed Monadina which contained a small Diatom, the excretion of which,
in the vicinity of the posterior extremity, taking place soon aftcnvards, also
made him consider the existence of an anus probable. Schneider remarked
in Chilomonas Paramecium one or two reddish lines limning from the inden-
tation into which the filaments were fixed, to tiie opposite end, and, from a
comparison of these ^vith the process of fission as seen in Bodo, concluded
that they wore furrows which gradually deepen until the imimalcule is bisected.
As during this process the being undergoes no change of form, except in be-
coming a Little broader, and the di\-ision takes place along its whole length,
the process must readily escape observation. The anterior end is always a
little thicker ; the furrows consequentiy are deeper and more distinctly recog-
nizable in that part. It is only in rare ca.scs, Avhen the division has taken place

61' THE MONADINA.

487

more slowly in some particular spot, that the two segments must endeavour
to tear themselves free, and thus, by twisting in contrary directions, draAV oui-
attention to them. It was without doubt a specimen of Cnjptomonas eylitidrica
in this condition which Ehrenberg conceived to be two individuals adheiiag
together and not in the act of fissation. Dujardin faUed m seeing spontaneous
fission among the Monadina, and thinks it more probable that their multi-
plication takes place by the separation of a lobe or of the termination of an
expansion, which his notion that they are without any sort of integument
presupposes they may, after the manner of Amoeba}, push out from theii- mass.
The family is distributed into nine genera, as follows : —

Eye wanting

B

i

("Single Monas.

[ Aggregate TJvella.

f Swimming

an
•43

Eye present

Single

I Microgle

Proboscis one or
two

Proboscides not | ^jj^^g^jg^.
more than lour J

Proboscides 1 pi^^eelomouas.

k many J

Aggregate Glenomorum.

Eolling Doxococcus.

Lips present Cbilomonas.

TaU present Bodo.

Dujardin was unable to recognize all the genera of Ehrenberg, and believed
that Microglena, Phacelomonas, Glenomorum and Doxococcus appertain to
another family, and that the distinction between the genera Polytoma and
Uvella is erroneously deduced from the supposed fission of Polytoma in two
opposite directions and the periodical grouping of Uvella. He thus reduced
the genera of Ehrenberg to foiu' in number, viz. Monas, Uvella, Chilomonas
and Bodo, the last comprehending in part his He.vamita, Amphimonas and
Cercomonas. The subjoined table represents the distribution he proposed : —

Isolated

A Single
FlageUiform
EUament.

Proceeding from the ante-
rior extremity.

MONADINA.

^Moveable in its en-
tire length Monas.

Thickened, and
moveable only
I towards the ex-

. , ^ V ti-emity Cyclidium.

Proceeding obbquely fi'om behind an anterior

prolongation Chilomonas.

Seyeral
Filaments.

' A second filament or lateral appendage ....

A second filament or posterior appendage

Two equal filaments, terminating the rounded
angles of the anterior extremity

Four equal filaments in front, two thicker be-

liind

A second filament proceeding from the same
point as the flagclliform filament, but tliicker,

trailing and retractile

^ A filament and vibratile cilia

i„.,«o«„t., / C^roups always free and wliirlins
Aggregate | ^^^^^^ ^^^^ extremity of a

extremity of a branching polypidom

Amphimonas.
Cercomonas.

Trepomonas.

Hexamita.

Heteromita.
Trichomonas.

Uvella.
Anthophysa.

488

SYSTEMATIC H18T0EY OP THE INFPSOfilA.

" These generic distinctions are, however," Dujardin veiy justly adds, " cn-
tii-ely artificial, and simply intended to facilitate the naming of Infusoria one
may have met with in such and such an infusion, and which, when better
known, may prove in some instances only varieties of a single species."

Perty appends to his histoiy of Monadiiia the following observations :

" Ehrenberg's Monadina are very difficult to detei-mine ; many, Hke Moims
bicolor, M. Colpoda, M. Enchelys, M. Umbra, M. hyalina, M. ovalis, M. Mica,
M. cylindrica, M. deees, M. flavicans, M. simplex, M. inanis, and M. sdnlillans,
appear to be only the earlier stages of other Monadina, or the yoimg stages
of CiHata. M. Ci-epusculum forms my genus Acaiicmm; M. Termo is a
Cercomonas ; M. Gruthda and M. vivipara are most likely varieties of the
multifonn M. Lens ; M. grandis and Microglena monadina are Sporozoids ;
Monas ocliracea, M. erubescens, M. vinosa, and probably M. gUscens belong to
the genus Ghromatium (XIX. 1) ; M. Punctum is no other than the one fila-
mentary variety of Polytoma ; M. socialis goes along with Cercomonas ; M.
tingens is the young condition of Cldorogonium euchlorum ; Uvella virescens
possesses one filament and no cilia ; U. Uva may be a colourless variety
of it ; U. Glaucoma scarcely belongs to the genus Uvella, as it has always
two filaments U. Bodo appeal's a developmental phase of Ihiglena viridis ;
Polytoma Uvella is equivalent to my P. Uva ; Microglena punctifera is nn-
known to me. The genus Doxococcus I consider untenable ; D. ruber and D.
Pulviscidus are merely resting forms of Astasia ; Ohilomonas Volvox and C.
destruens are in aU probability embryos of Ciliata, and Ch. Parameci%im is the
hyaline variety of my Cryptomonas polymorpha ; and Bodo is divisible into
Anisonema (XIX. 8) and Cercomonas (XVIII. 11, 12, 20)."

The new genera instituted by the Swiss natui-alist are Tetramitus (XIX.
3), Mallomonas (XIX. 4), Pleuromonas (XVIII. 25), Spiromonas (XVIII.
24), Menoidium (XIX. 2), Chromatium (XIX. 1), and Acariceum. Fresenius
accepts two of these new genera, viz. Mallomonas and Tetramitus, and creates
in addition two others, Rhabdomonas and Ch-ymcea, — the fonner not identical
with the lihabdomonads (staff'-lilie monads) mentioned by Ehi'enberg as a
group of his genus Monas.

Respecting the large contribution by Perty to the number of Monadina
catalogued by Ehrenberg and Dujardin, the question arises, whether the
forms named are really different and distinguishable. We fear, indeed, that
the increased number will rather perplex and eucimiber the observer than
advance his real knowledge of microscopic forms. Still, to make our resume
complete, they must be enumerated. In effecting this, the plan pursued will
be to describe the several genera admitted by Ehrenberg first, adchng the
species noted by others, and after these to give the charactei's of genera and
species constituted by Dujardin, Perty, or any other naturalist: where the
same being has had a second name given it, it ■will be added as a sj-nonym.
In the systematic details we shall preserve the descriptions and remai-ks in
general which appeared in the last edition, and are largely borrowed from
Ehrenberg's most valuable works. These, indeed, are evciwhcrc tinged
with the peculiar hypothesis of that wi-itor, the value and bearing of which,
however, have been sufficiently examined in the first part of this work to
render explanations and corrections here unnecessaiy. The description,
therefore, of mouths, eyes, stomach sacs, glands, vessels, hennaphrodilc deve-
lopment, ova, and of aU other stnictiu-es or oi-gans of higher animal organiza-
tion, Avill have no other value as api:)lieable to such special organs than that
accorded to it in the mind of eveiy indiA-iduid reader of the chapter on the
structure and functions of the Monadina, who can draw for himself his own
inferences from the facts and opinions therein recorded.

OF THE MONADINA.

489

Gemis MONAS (XVIII. 1, 2, 15, 17, 19, 21).— The animalciUes of this
genus — the true Monads — are described (see table) by Ehrenberg as dpstituto
of an eye, with projecting lip and tail, and as always swimming in the direction
of the longitudinal axis of the body, their mouth being situated at the anterior
end. It is another distinguishing character of the true Monad, that it is never
seen to cluster, like others of its famUy, so as to form a berry-Hlce mass ; and
hence it is designated single, in contradistinction. Amongst the several
species distinguished, some few are green, yellowish, or of a reddish tint ;
but the majority are colourless ; colom-, moreover, is not a characteristic to
be reUed upon. Monads may often be present in water, under inspection, with-
out being seen, owing to the magnifying power employed being insufficient.
They will be sought for in vain with a power of less than 300 diameters ; and
even this, in some cases, wiU be found insufficient. They are, besides, as a
genus, difficult to be accurately determined, not only on account of their ex-
ceeding minuteness, but becaxise the young of other genera are so likely to be
mistaken for them, — for instance, the yoimg of the Bacterium, Vibrio, Uvella,
Polytoma, Pandorina, Goniiim, &c., when separated from their clusters. And
this difficulty in disciiminating them will be more likely to happen when they
are not observed whilst undergoing the process of self-division, or when seen
in water contaiaing but a small number of them ; under which circumstances,
however anxious we may be to ascertain their name, we must often rest con-
tented with probable siu-mise. When the water swarms with the creatui'es,
the decision will be far easier, and more trustworthy, since the characters are
then more easily discoverable, and theii- possible variations appreciable. The
observer may, however, be guided to a certain extent by the following rule : —
Suppose that in a di-op of water containing species of the genus Vihio, Bac-
terium, Uvella, or Polytoma (easily distinguished by their clustering forms),
separate Monad-like bodies were to be observed ; the probability is that they
would be either single forms, or the young of the clusteiing animalcules ; and
if there were no great difference in the size of the separate individuals and
those forming the clusters, this conclusion Avould be generally correct : and
this rule apphes equally to those gi'een Monad-Uke creatui'es found amongst
Pandorina and Gonium. Chlamidomonas Pulvisculus, when young, is veiy
deceptive, and may often be mistaken for an illoricated and eyeless green
Monad.

The only locomotive organ which has been discovered in the genus is the
single filiform proboscis (filament) issuing from near the mouth. The numer-
ous cilia sometimes apparent thereabouts are nothing more than this filament
in a state of vibratory or rotatory motion. This organ, Ehrenberg observes
has a twofold office, one being locomotive, and the other to pro\dde the creature
with food, and hence may be called a purveying organ.

Vacuoles arc readily seen in some of the species (e. g. M. Guttula and M.
viviiKira) without the aid of coloured food ; in others {M. Tcrmo M. Guttula
and M. socialis), its aid is required. '

The propagative apparatus Ehrenberg represented in M. Guttula and M
vivipara to consist of a vast number of granules formed into a nct-likc mass"
dispersed generally throughout tlie creature, having a comparatively large
spherical body (the nucleus) which divides in the process of sclf-fission

Monads multiply rapidly by self-division, either transversely, as in Mono
Guttula, M. hyahna, M. r/liscem, M. Olcenii, and M. socialis ; or longitudi
nally, as m M, Punctum (XVIII. 2) : both methods have been obsciTcd
31. vivipara.

As the members of this genus are chiefly curious on account of their extreme
minuteness, only the leading characters and size of the several species

nas
li-
in

are

490

SYSTEMATIC HISTOHY 01? TIEE INFUSOEIA.

given. Most of them are inhabitants of water in which organic matter is un-
dergoing decomposition.

The Monads of Ehrenberg are arranged under two divisions, according to
theu- external form. The fii-st division contains all those of a globular or oval
shape (globular Monads) ; the second those of a lengthened form, the length
bemg more than twice the breadth (elongated Monads).

A. — Globulab Monads.

MoNAS Crepusculiim (xvm. 1). — The
smallest of all living creatures; of a
spheroidal fomi, and hyaline, although,
when seen in masses, with the naked
eye, of a whitish hue. Thej' are active,
and feed on animal as well as on vegeta-
ble substances, and are found in water
holding animal matter in solution ; but
as decomposition proceeds, they die, and
their bodies rise to the surface of the
water, and form a thick and colourless
gelatinous stratum. Rarely 1-1200" in
diameter ; never larger.

M. Termo (M.), so named fi'om its
having been supposed to be the limit of
animal organization ; globular, active,
herbivorous ; foimd in stagnant water ;
increases rapidly where there is an
abundance of vegetable matter imder-
going decomposition. 1-6000" to
1-12000", and less.

M. Guttula (M.). — Roimd, inactive ;
may be preserved by di-ying; 12 di-
gestive vacuoles seen by the aid of in-
digo or carmine ; sm'face appears gi-anu-
lated. In vessels of water contahiuig
plants or flowers. 1-2300" or less.

M. vivipara. — Spherical, inactive. In
stagnant water; coloured. 1-620" or less.

M. gratidis. — Spherical ; colour green-
ish, except near the mouth ; filament
short, l-3rd or l-4th the length of the
body ; motion sluggish. In marsh water,
very rare. 1-430".

M. hicolor. — Globular; colourless, ex-
cepting one or two green spots within
it ; attenuated anteriorly ; motion vacil-
lating. 1-1440".

M. ochracea. — Globidar ; of a yellow-
ochre colour. In water-courses. 1-6000"
at most.

M. erubescens. — Circular ; rose-co-
loured ; motion slow but continued. In
salt water. 1-1728".

M. vinosa. — Globidar, colour of red
wine ; motion tremidous ; rejects co-
loiu-ed food. In vegetable infusions.
1-12000" to 1-6000".

M. Kolpoda. — Colourless, oval or egg-
shaped ; motion vacillating. In water
in tno silver mines of Siberia. 1-7200". ,

M. Enchchjs. — Colourless ; continuous |

slow motion. In marsh water. 1-1200"
to 1-960".

M. Umbra. — Ovate, colourless ; motion
rapid. Among fresh Confervse. 1-2400"
_ M. hyalina. — Ovate, colom-less ; ac-
tive, and seems to leap or jmnp. In stale
water in glass vessels. l-6000"to 1-2880".

M. gliscens. — Ovate, colourless ; mo-
tion gliding. In infusions of the sting-
ing-nettle. 1-4500".

M. ovalis. — Oval, colomless ; motion
tremidous. In water from the Anodonta
MoUusca. 1-9600".

^l. Mica. — Oval, coloiu-less; rotary
and vacillating motion. In clear fresh-
water. 1-1440" to 1-1200".

M. Punctum. — Egg-shaped ; revolves
on its longitudinal axis (xvm. 2) ; the
lower figure exhibits one undergoing
longitudinal division. In water with
tannin. 1-1150".

M. Semen. — Large, green, rather obo-
vate, subcompressed ; anterior end di-
lated, rounded ; posterior attenuated ;
oral apei-ture (!) triquetral beneath the
fi'ontal portion ; vibrates by numerous
cdia (!). Length 1-48"' ; motion vacil-
lating, slow ; a central, hyaline, subglo-
bose gland ; ovides large, green, ovate.
It readily shows by diffluence the o^-a,
gland, and bacUlaiy spicula. Frontal
end exhibits rugas extending fi'om the
mouth. With deca;\4ng Sphagnum from
mai'shes, Berlin, ^luely this organism
is not a Monad.

B. — Elongated Monads.

M. cyUmhica. — Solitaiy, elongated,
coloiuless ; motion revohong. In salt
water. 1-1150".

M. Okcnii. — Elongated, red ; motion
revolving, vibratory, social. In running
water. 1-2300".

M. dcscs. — Conical, green, solitary. In
water from hills. 1-1200".

M. socialis. — Conical, colourless, so-
cial. In water-butts. 1-700".

M. flavicans. — Top-shaped ; social ;
motion gliding. In ditch-water. 1-1720".

M. simpkx. — Spindle-shaped : colour-
less ; motion gliding and rotary. In
water of the Nile, and at Berlin. 1-1720".
M. manis. — Fusifonn, colomless ; nio-

OF THE MONADIITA.

491

tion vacillating. In stagnant and foul
water. 1-3600".

M. scintillans. — Fusiform, veiy active ;
motion vacillating. Amongst fresh-
water Conferv£e, &c. 1-6000" to 1-4600".

M. Dumalii. — Of a deep red colour;
in vast numbers in the saltmai-sh-water
of the Mediterranean, to which they
give a deep blood-colour. Discovered
by M. Joly.

M. prodif/iosa. — A very minute red
Monad, so named by Ehrenberg fi'oni
its surprisingly rapid development. It
is this animalcide which has produced
the blood-lilie spots occasionally appear-
ing mysteriously on bread and other
farinaceous substances, and which have
ever been a cause of teiTor to the super-
stitious. Cohn assei-ts this organism to

be a Vibrio, and not a 3Ionas.

Being desirous of making this manual as complete as possible, the following
species, described by M. Dujardin, are inserted ; but it may be that some of
them refer to Monads already characterized, but differently named.

M. Lens (xvra. 10, 21). — ^Roimded or
discoid; surface in appearance tuber-
cidai-. 1-5200" to 3-5200". This spe-
cies, one of the most frequent in animal
or vegetable infusions, has been recog-
nized by most of the ancient microgTa-
phers. It sends out obliquely a flagel-
liform filament, three, foiu-, or even five
times as long as the body, andmobile in all
its length. Probably =M. Gtittula (Ehv.).

M. concava. — Cii'cnlar, concave on one
side, thin in the centre, margin tumid ;
filament long, moveable throughout. In
marsh water, Toulouse. 1-2080".

M. glohulosa (xvm. 17). — Globular;
form mostly constant; compressed at
origin of filament ; more globular than
M. Lens, and its siu-face smooth. In sea-
water at Cette, France. 1-2000".

M. elonqata. — Elongate ; nodidar,
flexible, of variable form. 1-1200".
In marsh-water.

M. atienuata (xvin. 19). — Ovoid, ta-
pering at each extremity, nodulai', va-
cuolse lai'ge and distinct, as is also its
filament. 1-1660".

M. ohlonga. — Ovoid, oblong, unequal,
tubercular, hollowed by vacuolte.
1-3600". In vesretable infusions.

M. nodosa. — Oblong, in-egular, nodose,
tapering behind, truncate in front, fila-
ment arising from centi-e of truncate ex-
ti'emity. 1-2170". In sea-water at
Cette, France.

M. gibhosa. — Oblong, angidar, irregu-
larly distended and gibbose ; filament
springing mostly fi'om an anterior con-
striction. Length 1-2000". In infu-
sions of gelatine.

M. varians. — Oblong, naiTower in
front, very soft, and variable in form.
1-650'; to 1-700".

M. intestinalis. — ^Very elong-ated, fonn
constantly changing, or one end roimded,
the other tapering to terminate in a long
filament ; motion undulatory. 1-1600".
Found in the excrement of a newt
{Triton palmipes). "I think this is one
of the species of Bodo, described by
Ehrenberg as met Avith in the intestines
of fi-ogs" (Duj.).

M. fiuida.. — Soft, semifluid; form
variable, iiTegnlarly ovoid, sometimes
constricted posteriorly, hollowed bv lai'ffe
vacuoles. 1-2600".

M. cows^rwia.— Elongated, four or five
times longer than broad; constricted,
often much so at the centi-e. 1-1300".

Pertyhas distinguished the following Monadiform beings by specific names:

MoNAS curvata. — A variety of M.
Lens ; tapering posteriorly.

M. (tstasioides. — Of variable form, often
with one or two longitudinal lines, and
a central vacuole. 1-1340".

M. irregularis. — more or less globidar,
sometimes with capillai'y or angular pro-
cesses; numerous dark internal mole-
cules. 1-2000" to 1-1250". In ponds,
Beme.

M. pileatorum. — In-egularly oval ;
pointed anteriorly; colourless; motor fila-
ment short, scarcely IJ times the lengtli
of the body; movement sluggish; nearly
resembles M. socialis. 1-1400".

M. succisn. — Oval ; usually truncate.

rarely pointed behind ; colomless, ti-ans-
parent, with large vacuoles; filament
twice the length of body; movement
active and revolving. In water contain-
ing decomposing Anodonta, and foul
pond-water. 1-1800".

M. cordata. — Cordate seen on one
side, on another oval and truncate;
rounded anterioriy ; hyaline or gi-oyish
from internal gi-nnules ; swims tolerably
fast with an oscillating motion, and sel-
dom revolves; occurs singly and not
often; filament extremely difficult to
see, more than double the length of the
body. 1140" to 1080". In freshwater
ponds.

492

SYSTEMATIC HISTOKY OF THE INFUSOEIA.

filament apparently short ; onward
movement slow, although it revolves
rapidly upon its long axis. 1-3000"
to 1-600".

M. Farcimen. — Cvlindrical, greenish,
with red spots ; flexible ; onward move-
ment and rotation rapid. 1-1800"
to 1-1080".

M. Hilla. — Globular, or slightly elon-
gate ; of a dusky-green or brown colour.
Larger specimens at times present a
clear areola around coloured contents,
with vacuoles in the latter ; progi-ession
tolerably fast, turning more rapidly on
the long axis. Length from 1-6000" to
1-600". The three species last named
approach veiy closely to sporozoids of
plants.

M. wceolaris. — Very smallj m-ceolate,
obliquely emarginate in front; colour-
less,_ transparent, with scarcely an ap-
preciable differentiation of substance ;
filament indicated by the movement
produced in the -water at the anterior
extremity; motion slow. 1-2640".
Li brooks with Hysginuni pluvialis.

M. excavata. — Round or oval, with a
conspicuous speck in the anterior half;
colourless, or occupied with amoi-phous
brovsmish or greenish matter ; filaments
very fine, from 2 to 2^ times longer
than the body. Motion active, in a
straight line, and rarely revolving.
1-2100" to 1-1200". At Berne, in ponds
among Cliara.

M. Hotulus. — Elongated, cylindrical,
of a homogeneous pale-green colom-;

Fresenius has added the following species of Monas to the number already
distinguished : —

Monas triincata. — Hyaline, colour-
less ; figure oval and roimded, ti'imcate
anteriorly, compressed; one larger and
many smaller vacuoles often seen, the
former near the middle. The trimcate
end supports two filaments, mostly on
one side, equal to or rather longer "than
the body. Close beneath the anterior
margin a small transverse corpuscle is
mostly visible, of a faint green hue, and,
some way beneath this, a small contractile
vesicle. A side view shows a slight
hollow on the imder surface. Swims
without revolving, and mostly in a
straight course. 1-150 to 1-100 miUim.
in diam.

M. consociata. — Ovate, with one end
tapering and tnmk-like, and tenninated
by a filament more than double the
length of the body. The proximal half
of this filament often seems rigid, and
only the distal or temiinal half, which
is difficult to detect without the use of
iodine, motile. Body and its corpuscles
colourless ; among the latter is one pro-
minent vacuole, not conti'actile. A mul-
titude of these Monads occupied a trans-
parent mucoid matter, which was not

Genus UVELLA (XVIII. 3, 4).— Well characterized by the aggregating
together occasionally of the indi\adutil Monads, so as to fora a grape- or
mulbeiiy-lilic mass, and by their genernUy possessing two (?) hair-like fila-
ments at the mouth. Like the Monads, says Ehrcnberg, they are deficient of
the projecting lips, visual organ, and tail, and have the mouth situated at the
anterior extremity. They progress also in the direction of the longer axis of
their body, and are capable of complete self-division. Of the several species,
three arc green, and the remainder colourless.

This genus belongs to the Aggregate Mouadina of Dujardin, and is thus

seen in motion. In still spring-water at
Walldorf in Jime and July. It bears the
nearest resemblance to Cercomonas vorti-
cellaris (Perty). 1-100 to 1-75 miUim.

M. Oherhauserii. — A carmine-colom-ed
Monad found in the sulphui'eous spring
at Frankfort, allied to 3Ioms Okenii
(Ehr.), and possibly the same as C/iro-
matium Weissii (Perty). Cylindrical,
rounded at each end, hyaline ; faintly
carmine-colom-ed, with a variable num-
ber of iutenselj' crimson globules inter-
nally. Some specimens, however, have
only a homogeneous red colour. Trans-
verse fission frequently seen. It rotates
rapidly, and advances with a tumbling
sort of movement, no doubt by means of
a filament ; but this eludes observation.
1-83 to 1-46 millimeti-e.

M. hijmnctata. — A much smaller
species was found in the same glass with
the preceding, having a red colour, an
elongated oval figiue, and a red point
at each end. Longer specimens were
noticed ^^^th four such red points, which
might be in the act of fassion. This
fonn may be the some as the Monas
rosea of Moitcu.

OF THE MONADIN.V.

493

defined by him :— " animals globular or ovoid, having a single flagellifonn fila-
ment, and living aggregated in spherical masses, freely moving about in the
liquid." He fiulher obsen^es that isolated individuals are not at all distinguish-
able from simple Monads, that there is no good reason to suppose them to live
alternately isolated and in masses — a circumstance therefore Avhich cannot,
according to Ehrenberg's statement, be employed to distinguish them from
Polytoma.

Busk describes an early stage of development of Volvox 8ph(xros{ra as
constituting " a species of the genus Uvella, or of Syncrypta, Ehrenberg "
{M. T. vol. i. p. 40). Again, Cohn (on Protococcus, Bay Soc. 1853, p. 559)
makes one of the multiform phases of development of Protococcus pluvialis,
" when the zoospore is divided into thirty- two segments," equivalent to a
Uvella or Syncrypta.

Perty, in his accotmt of Uvella virescens, denies the existence of a common
envelope, stating that when the water evaporates from around a specimen,
the coverings of each individual corpuscle coalesce, and give rise to the appear-
ance of a general investment ai'ound them. He adds, moreover, that at
times the coi-puscles are green, with a clear central stripe ; at others, hyaline
with a distinct green border, and some scattered specks ; and at others, again,
hyaUne throughout.

Dujardin describes only two species, viz. U. virescens, and U. rosacea = U.
Glaucoma (Ehr.). Perty contributes to the list U. stigmalica.

which it had swallowed. When fed on
indigo, as many as twelve vesicles were
filled, and it was sometimes seen to void
little blue particles, like undigested
matter, fi-om its mouth. With a power
of 800 diameters, a gi-eat number ofsmall
colourless gi-aniiles, which he called ova,
were discerned lying between the nutri-
tive sacs. Fission both ti-ansverse and
longitudinal (xvm. 3, 4 : figm'es mag-
nified about 350 diameters). In water-
butts. 1-2.300" to 1-2350"; diam. of
cluster 1-430".

U. 5orfo.— Rounded in front, attenu-
ated posterioriy; coloiu- a beautiful
gi-een. In stagnant water. 1-4030" to
1-3450"; diam. of cluster 1-2350".

Xi. stigmalica (Perty).— Corpuscles of
a tmiform sea-green colom- ; each with
a very fine red stigma. Tliey are also
soniewliat broader than those of U.
urcsccns, and have a more decidedly
hyaline and apparently crenulated enve-
lope. At ]3orne mucli rai-er than U.
virescens.

Uvella viresemis {Volvox Ulva, M.).
— Ovate, colour gTeen, occurs in dense
clusters amongst ConfervaB and Lemnse.
1-2000"; diam. of cluster 1-280."

U. Chamcemoiiim. — Smaller than the
preceding one. In water-butts.
1-2880"; diam. of cluster 1-570".

U. Uva. — Has indistinct vesicles, and
is very small. In stagnant water.
1-4800"; diam. of cluster 1-9G0".

U. atomus (Motias atomus, M. Lens et
Volcox socialis, M.). — Voracious, with
large vesicles. 1-6900" to 1-3406";
diam. of cluster 1-1150".

U. Glaucoma (Volcox socialis, M.). —
Oval, inclining to conical ; as it advances
in age the posterior extremity is attenu-
ated, and an elongated outline is assumed.
Hyaline, with large vesicles, and two
evident filaments : individuals loosely
aggi-egated. In 1831, Ehrenberg first
observed a vibration at its anterior part,
and its reception of coloured food. In
1835, he discovered within the body of
tliis minute creature some gi-eon Monads

Genus MICllOGLENA (XVIII. 6).— Characterized by the presence of a
mmute red cye-Uko speck at the anterior part of the body. In other respects
the species resemble tnic Monads, having a very delicate filament no nro
jectmg hps and tail, and swim in the dii-ection of the long axis of the bodv

They multii)ly by complete self-division. ' ' - *

one yellow, and the other green.

Iwo species only are known — the

MiCROOLKNA punctifera {Enchelys
punctifera, M.). — Yellowish, oval, or al-
most conical ; posterior extremity acute.

Eye-speck red with a blnclcish central
spot. Among slimy-water plants. 1-620"
M. monadina.—Oi a beautiful green •

494

SYSTEMATIC HISTORY OF THE INFUSORIA.

form ovate, rounded equally at both ex-
tremities ; red stigma ; filament distinct,
neaiiy as long as its body ; motion vibrat-
ing, rotary on its long axis, (xviii. 6.
Three animalcules magnified, the first

800 diameters, exhibiting the internal
organization as represented by Ehren-
berg.) Among slimy-water plants
(ITampstead and Finchley). 1-2.300"
to 1-720".

Genus CHLORASTEE. — Solitary, without tail ; mouth terminal ; with a
frontal oceUus or eye-speck ; central portion of body with radiating rows of
raised points (verrucce). It is allied to the genera Olenomorum and PJiacelo-
monas, but differs from the former by being solitary (not clustering), and by
the greater number of filaments, and from Phacelomonas by having fewer
filaments.

CHiiORASTER gi/rans. — Green ; central
part of body fusiform; extremities

acute; centi-al rays of puncta four.
Filaments from 4 to 5". 1-632".

Genus PHACELOMOJSTAS. — Filaments numerous (8-10) around the mouth.
In other respects it resembles Microglena : it has the smaU red eye, the trun-
cated mouth at the anterior extremity, but is without a tail. It swims
in the direction of the longitudinal axis ; and its self-division i-S simple and
complete, but not constant in occui'rence. Many vacuoles are seen within
the body, but they have not been noticed to admit coloui-ed food. This genus
has not been figured by Ehrenberg.

Phacelomonas Pulvisculus (Moiias
pulviscuhis, M.). — Figm'e oblong or
slightly conical, attenuated posteriorly;
of a beautifvd green colom-. Just pre-
vious to self-division, its body becomes
cylindrical, then contracts at the centre ;

when dying it changes to a globular
shape. In swimming, it turns quickly
upon its longitudinal axis, without any
vibration. In gi-een puddles. 1-1152".
Ph. Bodo (Stem) = Ucella Bodo (E.).

Genus GLEJTOMOEUM (XVIII. 7).— Charactei-ized by having a single
red eye-speck, a tnincated mouth, and two filaments ; tail absent. Self-
division simple and complete ; their clustering is voluntary as occasion may
require, and gives them the resemblance to a bunch of grapes. They swim
in the direction of their long axis.

In this enumeration of the characters belonging to tliis genus, we are pre-
sented with an excellent illustration of the table (and one that exceedingly
well explains its use), under which all the genera of the family Monadina are
so arranged as to exemplify in what respects they are alike, and in what they
differ from each other. For example (see Table, p. 487), Glenomorum
closely resembles Uvella, but differs from it by the superaddition of the red
stigma ; it differs from Monas and Microglena in occasional!}' aggregating ;
from Chilomonas, in being deficient of the projecting lips ; from Bodo, in not
having the tail ; from Phacelomonas, by the double proboscis ; from Boxococcus,
by swimming instead of rolling over or revolving in tlie water; and from
Polytoma, by never appearing in clusters whilst undergoing self-di^^sion.

Glenomorum tinrjais (xvin. 7). —
Fusiform, three or four times longer than
broad, of a beautiful gTcen colour, -with
double, exceedingly delicate proboscis
about half the lengtli of its body. Inter-
nally are some small whitisli vesicles,
and the minute granides wliich give rise
to the gi-een colom*. About the centre
of the body is a large transparent colour-
less organ, the nucleus. The beautiful
Jted eye-speck is placed about one-third

from the anterior extremity of the body.
These animalcules constitute a great
portion of tlie green matter commonly
seen on stagnant water, and discovered
by Priestlev. They appeal- to be nearly
allied to Cercaria ri'ndi'.t, from wliicli
they difler only in magnitude and in
the" unalterable' form of their bodies.
Plentiful at Ilanipstead. Size 1-3600"
to 1-1700".

OF THE MONADINA.

495

Genus DOXOCOCCUS.— The Monads forming this genus differ from aU
others of the family Monadina by the singularity of their motion, which may
be defined to be neither that of swimming nor of rotation, but a sort of roll-
ing over and over. In other particulars they are like other Monads : they
have the same unvarying form, and are destitute of the eye-speck, project-
ing Hps, and tail ; and self-division is simple and complete. Tour species are
known.

Doxococcus Globulus. — Subglobose
or ovate; transpai-ent as water; easily
known by its tedious rolling motion;
month not discerned. In salt water.
1-860".

D. ntber (xvm. 8). — ^Brick-red, glo-
bidar, and opaque. Ehrenberg appears
to doubt whether this animalcule be-
longs here (though its motion is veiy
peculiar) or to the genus Trachelomo-

nas ; and he has not been able to satisfy
himself of the existence of a lorica.
Amongst Confervas, &c. 1-1720".

D. Pulvisculus. — Green, perfectly (?)
globular, and opaque. Amongst Con-
fei-vae. Not exceeding 1-1280".

D. inequalis. — Irregularly globular,
transparent, and covered with green
spots. Amongst Confervse. 1-2400".

Genus CHILOMONAS (XYIII. 14, 18).— Characterized by the obHquity
of the mouth with respect to the longitudinal axis of the body, which occasions
a projection above the mouth of a lip-Uke appearance. Motion in the direction
of the long axis of the body ; form invariable ; devoid both of eye-speck and
tan. Whether the projecting Hp is furnished with cUia, or with a double
filament, Ehrenberg has not satisfactorily determined, except in the case of
-amedum) in which he states two filaments are to be clearly seen. On
C. destruens there are a number of indistinct cUia. Self-division is simple and
complete.

Dujardin's characters of this genus are, "Animals with an ovoid, oblong
body, obliquely notched ia front, with a very slender filament proceeding from
the bottom of the notch. Movement from before backwards, on its centi-e.
It is with doubt that I refer the Infusoria I thus name to the genus Chile-
monas of Ehrenberg. The mode of insertion of the filament behind a pro-
jecting lip-like portion, approaches the animals to the Euglence and to certain
Thecamonadina ; but I cannot discover any trace of an integument either
contractile or resistant."

Chtlomonas Volcox. — Ovate, attenu-
ated and tnmcated anteriorly, trans-

{larent and coloiuless ; projecting lip
ong; ^vill feed on indigo. In stagnant
water. 1-1440".

C. Paramecium (xvin. 14). — Oblong
or ovate, wider at one end than at the
other, keeled longitudinally ; colom- like
that of du'ty water. The contained gi-a-
niiles have the reaction of starch. At the
posterior end a clear nucleus with a red-
dish halo may be obsei-ved ; and at the
anterior is areddish vesicle, probably con-
tractile. It refuses coloured food. This
animalcide is easily distingxushed by its
shape and peculiar lip-like process. With
a power of about 240, numerous vesicles
are \-i8ible, and with 380 the two fila-
ments, which are half the length of the
body, and proceed from a sinus in the
wider end. It moves in the direction of
its long axis, in a fluctuating or waver-

ing manner. It sometimes clusters. In
water wherein wheaten bread has been
steeped. 1-1020". The colourless va-
riety of this species is enumerated by
Perty as one of the many forms of his
Cryptomonas polymor2^ha.

C. destruens.— Ohlon^, but variable in
torm, on account of its softness, neailv
colourless or faint yellow. In salt and
trcsh water, and in tiie bodies of dead
Rotatoria, e. g. Aimrcea foKacca and
Monoccrca Rattus. 1-860"'.

C. c/ranulosa (Duj.) (xvm. 18).— Co-
lourless, oblong, larger anteriorly, al-
most invariable in form, although of ge-
latinous consistence ; filled with graniUes
which seem to project from its surface ;
filament very fine, arising from an ob-
lique notch. 1-940" to 1-850".

0. ohliqua.-~0\-o\A or pyi-ifomi, no-
dular, of variable form; the filament la-
teral. 1-2600".

4d6

SYSTEMATIC HISTOHY OF THE INFUSORIA.

Genus BODO (XVIII. 9). — The caudal appendage at the posterior extremity
of the animalcules is a decisive character of the genus ; mouth terminal, fur-
nished with a (single ?) filament ; self-division simple and complete ; eye-
speck absent. They never constitute true or perfect clustere like some of
the family Monadina, although, like Uvella, they occasionally aggregate. In
B. grandis, several vacuoles have been observed, and (as also in B. intestinalis)
a simple (perhaps double ?) filament. B. didymus has been knofloi to divide
transversely.

This genus Bodo partly comprehends the genera Hexamitti, A-mphimonas,
and Cercomonas of Dujardin, which are, with others, introduced as addenda
to this family Monadina. Dr. Burnett has made the following very correct
and just remarks on this genus Bodo and its division into species : —

"The tailed Monads or Bodos are found in the intestines of the common house-
fly or in those of the frog. Those fi-om the fly, when first seen, resemble in shape
a kernel of rye, and are about l-6000th of an inch in breadth, and l-2000th
in length. Attached to the body is a delicate hair-like taU, four or five times
its length. By the addition of water, the body enlarges by endosmosis, as-
suming a perfectly spherical shape after passing thi-ough aU the iutermediate
ones, so that, when magnified by the highest power of Spenser's microscope,
it is nearly one inch in diameter, pennitting the most thorough and satisfac-
tory study of their structure, which I find, after repeated observations, has
no peculiarities except those belonging to cells. It is a closed cell sac, ■with
a filiform caudate process, and capable of the actions of cell-membranes, viz.
endosmosis and exosmosis. In the interior of this sac are found sometimes
a few granules and sometimes a nucleus.

" In the Bodos of the frog, which are larger, I have seen distinctly, in some,
a nucleus with a nucleolus, in others two nuclei, and in others still, four
nuclei of equal size, thus showing that here the multiplication of ceUs takes
place, as elsewhere, by segmentation of the nucleus.

" Apart from these characteristics, which are insufficient, the fact that I
have sometimes met with them in the interior of epithelial ceUs, would be
strongly presumptive of their cell origin from minute granules that pass
through the ceU-waUs. The representatives of the genus Bodo therefore
appear to be simple cells, each with a fiHform appendage for locomotion, and
which locomotion, therefore, can have no adaptive chai-acter.

" There are differences in them as they may be taken fi-om difterent locali-
ties ; but, because these particles are cells capable of much change by dilata-
tion and contraction, these difi'erences can never sei-ve as the basis of species,
which would also be true from the fact that, having no indi^•iduality of their
own, there is necessarily no absence of type characteristics.''

species, and with the Bnrsaria ranmtim.
1-1440".

B. viridis. — Green, neaily globular;

Bono intestinalis (xvm. 9). — Almost
conical, transparent, and colourless ; tail
of equal length with the body. Found
in several living animals, such as frogs
and toads. Amongst the watery mucus
of the alimentary canal Ehrenberg has
observed gi'eat numbers of these crea-
tures, and remarlcs that the Cercoria
Gyrinm of MiiUer (a different animal-
cule) might pass as a representation of
this species, and that it was confounded
by its discoverer with Spermatozoa.
1-1720".

B. ranarum(= Cercoiiionas Ranantm,
Perty). — Body tuvgid, ventricles indi-
stinct. In live frogs, with the preceding

tail very short. Amongst Conferva?.
1-2400". Perty believes this species to
be nierelv the young of Eiighna viridis.

B. soct'alis (Monas Lens, M.). — Ovate
or subgloboso ; tail often longer than the
body ; transparent and colourless. Cliis-
tera in a mulberry shape. Single fonns
are sometimes observed hopping. Com-
mon in stagnant water. 1-2970".

B. vo7iire//aris (= Cercomonas, Perty^.
— Body tlu-ee times as long as it is
broad ; "tail verv short. In fj-esh water.
1-11200".

OF THE MONADINA.

497

B. didpnm. — Generally constricted
about midway, tail short. 1-9600".

B. saltans. — Very small ; body with
ample ventiicles ; tail short. This
creatm-e, most probably from its small
size, has been mistaken for Miiller's
3IonasTermo ; but its brisk leaping move-
ment will sufficiently distinguish it.
1-1200".

B. grandis. — Oblong ; vesicles ample ;
tail rigid, setaceous, anixed to the abdo-
men. In stagnant water. 1-864".
Lachmann states that an animal which
was probably Jiodo grandis, but might
have been an Astasia, devom-ed Vibrio
of two to foiu' times its own leng-th,
and in this way acquired the most
exti-aordinaiy forms ; the mouth was

close to the insertion of the flagellum,
B. ostrece (Pritchard). — Globular ; the
anterior three-fourths occupied with ve-
sicles, the rest hyaline ; length of tail
foui' times the diameter of hoAy. This
active creature was discovered in the
liquor of an oyster, swimming freely
among the ova (Sept. 1834). Diam.
1-2000".

B. ? Mastix (Ehr.). — Obovate, turgid,
smooth; terminal seta flexuose, acute,
exceeding some two or three times the
length of the body. Length 1-48"' to
1-30"', with the hlament 1-20"'. The
filament trails behind ; motion slow, not
leaping. This is the largest fonn of Bodo
obsei"ved by Ehrenberg. Foimd about
Sphagnum.

The following genera, named and described by Dujardin, are introduced
into his family Monadina : —

Genus CYCLIDITJM (D.) (XXVI. 14, 15).— Body discoid, compressed, or
lameUifonn, scarcely variable ; the filament thicker and more rigid near the
base than that of Monas, the free extremity only being moved.

This genus is as yet but artificial, and indeed provisional ; for true Monads
pei-fectly developed may possess a filament with a thicker base, and, again,
the constant outline of the body may be the consequence of the presence of
an integument — in which case the animalcules in question would be referable
to the family Thecamonadina. Movement slow and uniform.

It is to be regretted that Dujardin uses this generic name, as Ehrenberg
previously employed it to designate certain ciliated animalcules which cor-
respond but partially -nith those of Dujardin. Indeed this natnralist ob-
serves that " the genus Cyclidium (Ehr.) contains Monads also, and very
probably some of those to which I have applied the same ' generic ' name."

Cyclidium nodidosum (Duj.). —
Flattened, discoid, with rows of nodules
and vacuoles; movement exti'emely
slow. Length 1-5200". In water from
the Seine.

C. abscissum (Duj.) (xxvi. 15). —
Membranous, lamellifomi, ti'uncated
posteriorly ; filament rigid ; movement
slow, regular. 1-1040".

C. crassum (Duj.). — Oval, thick, and
rounded ; filament thickened at its base
and rather sinuous ; movements more
active, zigzag. 1-1090". Length of fila-
ment 1-000".

C. dtsiortum (Duj.) (xxvi. 14) ( =
Spirommias voluhdis, Perty). — Oval, fiat,

nodular, in-egularly bent, with a tumid
border. 1-1800" to 1-800".

"This species is perhaps only one phase
of development of Monas Lens ; it was
foxmd in Seine water kept during three
months. WTien young it has the form
of a disk, with a tumid and nodidar
margin ; when, however, it has grown
larger, it becomes twisted upon itself,
and its movements irregular. Some in-
dividuals ollered a certain alHnity witli
the Trepomonads, which favours the
opinion already advanced, that the ma-
jority of the Monadina arc but modifica-
tions of one or of several types."

Gcnu.s CERCOMONAS (D.) (XVIII. 11, 12, 20, 22, 23).— Body rounded
or discoid, tubercular, with a posterior variable process in the form of a tail
of gi-eatcr or less length and fineness. '

The Ccrcomonads differ from the Monads by the posterior prolongation
which sen-es, by the adhesion of its extremity, as a point of support : it occurs
either as a very fine thread or contracted into a small tubercle ; it is some-
times nearly as fine as the anterior filament, and susceptible of an undiilatory

K

498

SYSTEMATIC HISTOBY OF THE INFUSORIA.

motion, I have not unfrequently witnessed the transition of Monads to the
condition of Cercomonads.

We may conclude that many of the animalcules described in the genus
Bodo (Ehr.) are examples of this genus (Cercomonas, Duj.), although suffi-
ciently marked characters are wanting in order to discover specific identity.

Cekcomonas detracta. — Discoid or
oblong, granular, with a thick tail.
1-7000" to 1-2300".

C. crassicauda. — Elongated, nodular,
flexible, or variable in form, more or
less contracted posteriorly into a tail.
1-3400" to 1-2600".

C. viridis. — Ovoid, oblong, tubercular,
green, prolonged posteriorly iato a tail
of varying tenuity, or into a rounded
lobe or spathulate expansion. 1-1500".
Pei-ty believes this to be no other than
an early stage of development of Euglena
viridis.

C. laayma. — Globular, unequal, elon-
gated posteriorly as a long flexuose tail.
Length of body 1-5200" to 1-3000" ; of
tail 1-2600"; of filament 1-750".

C. acuminata (xvm. 20). — Globular or
ovoid, contracted posteriorly into a short
tail, tei-minated by a very fine filament.
1-2600" to 1-1900".

0. Globulus (xvra. 23). — Globular,
with a filament at each extremity double
its length, the anterior one more actively

moved. Length 1-2600". In marsh-
water.

C. longicauda (xvm. 22). — Fusiform,
flexible, terminated posteriorly by a long
and very slender flexuose filament.
1-1800".

C. fusiformis. — DUated at centre, con-
stricted in front, and prolonged behind
iato a long delicate tail. Length of body
1-1900".

0. cylindrica. — Elongated, cylindri-
cal, constricted posteriorly, tenninated
by a long, straight, and very thin tail.
Length of body 1-2600"; of tail the same.

C. truncata (xvm. 12 a, b). — Con-
tracted posteriorly; truncate in fi-ont,
with a filament springing from each of
the ti-uncated angles ; the posterior
angle extended more or less into a
lobe. 1-3000" to 1-1900".

C. lobata (xvm. 11 a, h). — Variable in
form, tubercular, sending out a flageUi-
fonn filament from the end of an ante-
rior lobe, and emitting also one or two
other lobes. 1-3250" to 2-3250",

It is right to mention that Dujardin has noted the occiuTence of several of
the above Cercomonads in organic infusions, in conjunction particularly with
Monas Lens, and that he inclines to the idea that these diiferently-named In-
fusoria are merely different conditions of the same animalcule.

Perty adds the following species : —

C, intestinalis. — Has a posterior vi-
brating filament, and probably an ante-
rior one also. Internal molecules very
fine; body transparent; posterior fila-
ment about three times the length of the
body. Is common in the intestine of the
frog, and is in part equivalent to Bodo
intestinalis (E.). 1-3000".

C. curvata. — Cylindrical, cm-ved, with
an anterior and a posterior filament. In
some specimens apparently two fila-
ments occuiTed in front. 1-2400". Very
active : occurs among the ova of the
frog (Rana temporana).

C. vorticeUaris=Bodo socialis and B.
vorticellaris (E.).

C. B.anam7n=Bodoranarum ? (E.). —
Colomless, soft, more or less conical ;
tapering or rounded behind, but without
posterior filament. In water with Mol-
lusca, and in the intestine of frogs.

C. clavata. — Colourless or grejnsh,
thickened anteriorly, tapering poste-
riorly, club-shaped ; motion rather
quick; periphery clearer than the
centre. 1-570".

C. Fakula. — Colourless, transparent,
compressed and ciurved (?), much
wdened in front, truncate and emar-
ginate ; posterior portion tapering to
a blunt apex ; movements sluggish.
1-720".

Genus AMPHIMONAS (Duj.) (XVIII, 13).— Animals of variable, irre-
gular form, having at least two filaments, of which one is either in front, and
the other on one side, oAving to a constriction of the body, or both are lateral,
and accompanied or not yviih. a caudifonn prolongation. The leaping move-
ments of A. cauclata are remarkable, and the variability in form is charac-
teristic of each species.

I

OF THE MONADINA.

499

Amphimonas dispar (xvm. 13 a, b). —
Oblong, of very variable form, one or other
end consti'icted, or prolonged laterally
into two filaments. 1-3500" to 1-2900".
Movement active, jerking.

A. caudata. — Of very variable form,
mostly depressed, tubercidar, convex on
one side, angulai' on the other, with a
filament proceeding from the summit of
each angle. 1-2180" to 1-1300".

" This species seems to me," says Du-
jaxdin, " to be allied to the Bodo saltans
of Ehrenberg. In every example, I saw
two flageUifonn filaments, one from the
anterior, the other from the lateral angle ;
a caudifoi-m prolongation, obtuse or drawn
out as a thu'd filament, often adhered to
the slide."

A. brachiata. — Under this name is in-
dicated an animalcule of the family Mo-
nadina, which Dujai'din only once met
vdth, of an ovoid or pyiifoi-m shape,
filled with gi'anules, and giving off from
its narrower anterior end a simple flexu-
ose filament, too^ether with a variable
dilated lobe emitting two other fila-
ments having an undidatory motion.
The animal progressed by leaps, revolv-
ing at the same time.

A. exilis (Perty). — Colom' soft grey;
figure wedge-shaped, oftentimes emar-
ginate anteriorly ; filaments two, twice
the length of the body, colomiess j mo-
tion oscillating. 1-2000".

Genus TEEPOMONAS (D.) (XVIII. 16 & 27).— Body compressed, thicker
and more rounded posteriorly ; its anterior extremity presents two thin lobes,
bent to one side and each terminated by a flageUiform filament, which pro-
duce an active whirling and jerking movement.

" The examples of this genus are very common in aU collections of marsh-
water containing decomposing plants, but are most difficult to determine,
owing to the irregularity of their form and the rapidity of theii- movements.
I have rather glimpsed than certainly detected their flageUiform fiQ.aments
and have in vain attempted accurately to delineate them."

Tbepomonas agilis (xvm. 16, 27).— Body gTanular, unequal. 1-1300".

Genus HEXAMITA (D.) (XXVI. 1).— Animals with an oblong body
rounded in front, constricted and bifid or notched behind. Two to four fila-
ments extend from the anterior border ; and the two posterior lobes are pro-
longed as two flexuose filaments.

This genus, characterized by the number of its motor filaments, appeara
sufficiently distinct from the preceding. Its species occur in decomposino'
marsh-water and in the intestine of Batrachians, but not in ai'tificial infu-
sions.

Hexajhta nodulosa (xxvi. 1). — Ob-
long, with three or four longitudinal
rows of nodules, the two lateral of which
are extended into tapering slender lobes,
each terminated by a filament; move-
ment vacillating. 1-1300" to 1-1500".

H. infiata. — Oval oblong, rendered
almost quadrangular by the processes

rS"t?T-i3°5)f *°

H. iH!!es<MjaZw.— Fusiform, prolono-ed
mto a bifid tail. Very common in the
abdominal cavity of the Batrachia (frogs
and newts). It moves in a sfraight line
oscillating from side to side. '

Genus HETEROMITA (D.) (XXVI. 5 ; XVIII. 26).— Body globular
ovoid, or oblong, with two filaments extending from the same point in front
—one slender, undidating, and producing an onward movement, the other
thicker, stretching posterioriy, and free, or contracting adhesion Avith the o-lass
slide along which it moves, so as to cause a sudden movement backwards

« The several sections of the Monadina, together with the Thecamonadina
and the Euglena?, contain Infusoria possessing two filaments, by one of which
they progress, by the other adhere for support to any solid body, and produce
a sudden movement backwards by its contraction. To prevent confoundin!
specimens of these several families, the same distinctions which mark

2 K 2

the

500

SYSTEMATIC HISTOET OF TnE INFXTSOEIA.

Monadina generally, must be found in order to constitute the Heteromita
members of that family, — such as the absence of integument, the gelatinous
appearance of the entire mass admitting of agglutination to other objects,
and the drawing out of its substance into filamentous processes, together with
the existence of certain coi-puscles, which can only have penetrated the inte-
rior as a consequence of the formation of vacuoles at the surface " (Duj.).

_H. angusta. — Narrow, lanceolate,
slio;htly bent, tapering at each end, with
a flagellifonn and a second filament from
the same point anteriorly, erect at the
base, but floating fi-eely the rest of its
length. 1-1050".

lliis is a doubtfid species; it is of the
shape of a lanceolate leaf, with a mid-
rib or longitudinal fold.

Hetbeomita ovata (xxvi. 5). —
Ovate, naiTower anteriorly, containing
vacuoles, granules, and Naviculse.
1-1050" to 1-1150".

This is probably the Bodo grandis of
Ehrenberg. His other Bodos are not
Hetei'omitce, but imperfectly-observed
Cercomonads or Ampliimonads.

H. Granulum. — Globular, sm-face gra-
nidar. 1-2600", In rather putrid sea-
water.

The following species are from Perty

H. picsilla. — Colourless, very delicate,
cylindrical or Euglena-like in figure,
constricted at the centre, often emargi-
nate posteriorly ; filaments 2 to 2^ times
longer than the body; movements in-
active, oscillating ; few fine granules in-
ternally. 1-3000" to 1-2160". AUied
to, but smaller than, H. angiista, and

's work : —

like Ampliimonas dispar, in which, how-
ever, both filaments are equal. In ponds
at Thun.

H. exigua. — Oval or spheroidal, co-
lourless ; filaments about three times
the length of the body ; movements in-
active. 1-7000" to 1-4800". In turf-
hollows on the Bernese Alps.

Genus TRICHOMONAS (D.) (XVIII. 28).— Body ovoid or globular, capable
of being drawn out when adherent, and in this way presenting sometimes a
caudal prolongation. The anterior flageUiform filament is accompanied with
a group of vibratile cilia.

tiu-ning on its axis. 1-1730". Found in
the intestine of Limax agrestis.

T. Batrackiorum (Perty) (xnn. 28 «, h,
c, d). — Widely oval, at times sHghtly
emarginate in fi'ont, mostly with a keel
along the back, colourless, and 8 to 10
cilia on the left side; i"esembles T.
Limacis, but is more finely granular.
1-2400" to 1-1300".

Trichomonas vaginalis. — Gelatinous,
nodular, unequal, hollowed by vacuoles,
often adheiing to other bodies ; move-
ment oscillating. 1-2600".

T. Limacis. — Ovoid, smooth, pointed
at each end, and terminating in front by
a flagelliform filament, from the base of
which a row of vibratile cilia is directed
backwards ; progi-essive movement act-
ive, the animalcule at the same time

Genus ANTHOPHTSA (D.) (XXVI. 2). —Animals ovoid or pyriform,
furnished with a single flagelliform filament, and collected in clusters at the
extremities of a branching stem, or polypidom, secreted by themselves; clusters
when detached resembling those of Uvella.

The trec-liko polypary is brown at the base, but clearer and even dia-
phanous at the tei-mination of the branches, which appear nodular. The
groups of animalcules are easily detached from the stem, and then commence
a rotatoiy movement by the action of the filaments of each indiA-idual in the
group. Detached solitaiy animalcules move Like the common monads with a
single filament. The branching support, at first soft and gelatinous, becomes
by degrees more consistent, brown, and of a homy character, appearing to
partake no longer of the vitality of the animalcules.

A. Miilleri was erroneously placed by Ehrenberg in the genus Epistylis,
among the Vorticellina, and called E. vegetans.

The delicate branched fibre or stem has been considered a microscopic

OF THE MONADUrA.

501

fimgus, and been named by Kiitzing Stereonema. Upon this view, the
monadiform beings crowning the summits of the branches have been con-
ceived to represent the spores. This opinion has been carefully investigated
and rejected by Cohn {EntmcTc. d. mikroskop. Algen u. Pike, pp. 114-115),
who confirms Dujardia's description, and regards it as a stalked Uvella.

monadifonn beings, looking like so many
short hyaline fibres. Each monad con-
tains a comparatively large non-con-
tractUe vacuole having a red refraction,
and is fimiished with a filament at its
free extremity. Length of monads

Anthophysa Miilleri. — With the
characters described.

A. solitaria (Bory). — A species was
described imder this name by Bory de St.
Vincent, and is again brought to notice
by Fi'esenius, who met with it in some
standing water with Salvinia. The
stem is simple (not branched), and has
a clear- outline to its extremity. Its
length is from 1-25 to 1-8 millim. ; and
in water it has a clear brownish-green
colour'. Its apex is surmounted by the

1-100 to 1-75 "millim. The fixed stem
can bend itself from side to side. In
one specimen a contractile vesicle was
seenin one of the monads. This organism
appears to be precisely the same as the
Epistylis Botrytis (Ehr.),

Genus PEEONIUM (Cohn), represented by one species.

consists of a delicate coloui-less fibre sur-
moimted by a globidar head, which re-
solves itself into numerous swarm-ceUs
of a monadiform character.

Peronittm adculare has been newly
described by Cohn (Entioick. &c. p. 158)
as a form allied to Anthophysa. It is
parasitic on the spores of Pikilaria, and

The two next genera are named by Werneck {Monatsbericht der Berlin.
AJcad. 1841, p. 377), and thus briefly described : —

Genus ANCYRIUM = Enterodelous Bodos (i.e., siccording to the nomen-
clature of Ehrenberg, Bodos furnished with an intestinal tube) with a
moveable setaceous foot.

The existence of an alimentary tube (so supposed) removes the Bo do
grandis and the six allied species (i. e. the genus Ancyrimn) far above the
Monadina of Ekrenberg, whilst the possession of the setaceous foot also indi-
cates a higher organization.

Genus EE,ETES= Loricated Phacelomonads.

The following are the new genera of Monadina instituted by Perty •

Genus TETRAMITUS (Perty) (XIX. 3).— Figure conical, taperii^g pos-
teriorly, and having four vibratory filaments in front. Hexamita differs in
having in addition two posterior filaments.

TExnAMiTUS clescisstis (xix. 3). —
Wedge-shaped, curved, tinmcate ante-
riorly, and colourless or pale gi'ey. Sur-
face mai'ked by cross-lines. Movements
tolerably active and oscillating. Fila-
ments nearly twice the length of the
bod^. 1-1860".

T. rosti-atus. — Colourless, with an an-
terior border; one side elongated as a

Genus MALLOMONAS (Perty) (XIX. 4-6).— Body oval, elliptic, or discoid
with brown or greenish contents. Surface covered with long motionless
hairs. A single filament anteriorly, double the length of the body.

prominent angle or bealc. Smallest
specimens 1-7000", the largest 1-1080"
in length. Bern. Li stale pond-water.
Fresenuis describes it as rather pjaiform,
ti'uncate anteriorly, witli a sliort trunk-
like process from one side ; elongated and
pointed behind. A vesicle (contractile P)
at the anterior extremity.

Mallomonas Plosslii (xix. 4-0)
(foiTnerly described m M. acaroidcs), —
Mostly oval ; the smaller end anterior ;
rarely elliptic or discoid ; the periphery
apparently crenulatcd — an appearance
probably due to the points of insertion

of the hairs ; these are commonly
longer on the posterior half Contents
sometimes seen longitudinally or trans-
versely divided. INlovenieiits rather
rapid, but rarely attended by a rotation
of the body. In one example the hairs

602

SYSTEMATIC HISTOET OF THE INFUSOEIA.

seemed tenxiinated by a Imob. It is not
improbable that Pantotrichum Enchelys
(E.) is also a member of this genus.
1-1440" to 1-960". Bern. In ponds.
— A variety (ilf. epilis) occm's, hav-
ing the hau-s short or actually absent,
although covered with little nodules
■which serve as bases for hairs. Frese-
nius has noticed this organism. He
adds, the ends are often pointed. The
hairs or bristles are long, and tolerably
numerous — as many as 30 have been
counted, placed at all parts of the peii-
pheiy. The anterior setiform hairs are
most concerned in locomotion ; those

placed laterally either lie along the sides
pretty closely, or stand out at a greater
or less distance, and appear concerned
chiefly in changing the position. The
two most in advance seem to have the
character of feelers. A clear vacuole
was sometimes seen m the middle of the
dusky-green contents. A few small,
contractile, optically red specks have
also been observed. 1-720"' to 1-444"'.
Fresenius considei-s it ought to be re-
moved from the Monadina; and Perty
is himself imable to decide whether this
genus is referable to the CUiata or to the
Phytozoa.

Genus PLEUROMONAS (Perty) (XVIII. 25).— Body reniform, extremely
delicate, smaU, colourless ; filament extended from the concave side of the
body, and three times its length.

Pleubomonas Jaculans = Chilomonas
obliqua (?) (Duj.) (xvni. 25). — Colom--
less, transparent, with a few small mole-
cules. Movements eccentric, hither
and thither in a jerking and leaping

manner, followed by intervals of rest.
Veiy young specimens are roimd.
1-6000" to 1-3160". Bern. In stale
water and infusions of Lycopodium
seeds.

Genus SPIEOMONAS (Perty) (XVIII. 24).— Body leaf-like, compressed,
roimded at both ends, and rolled spirally on itself longitudinally.

Spibomonas voluhilis = Cyclidium dis-
tortum (Duj.). — Colourless, transparent,
smooth, very delicate. Revolves rapidly
on its long axis. Not nodidar on the
margin, like the Cyclidium distortum

of Dujardin, but is probably (as Dujar-
din believes the latter to be) merely a
phase of Monas Lms. 1-1800" to
1-1300". Bern. In foul water.

Genus MENOIDIUM (Perty) (XIX. 2).— Body small, crescentic, thicker
on the outer or convex margin ; containing internally small molecules and
vesicles ; colourless, or occupied with a little chlorophyll.

MENororuM pellucidum (xrx. 2). —
Recalls by its figm-e a little Clostcrium
lunula ; not rounded, but flattened like a

sickle. Movement tolerably rapid, jerk-
ing and revohing. 1-670" to 1-430".

Gemis CHROMATIUM (Perty) (XIX. 1).— Body extremely small, rod,
brown, violet, or green in colour, containing in the mature condition some
internal vesicles. A motor filament at the anterior extremity (?). Multipli-
cation by transverse fission. To this genus Perty would refer the greater
part of the Monads described by Ehrenberg which possess a brilliant colour ;
and he is in doubt whether they are not all rather referable to the genus
Bacterium, as well as the next genus named, i. e. Acarimm. However, he
at present retains Chromatium and Acariceum among the Monadina, and
establishes two species of the former.

CnnoMATiUM Wcissii (xrx. 1). — Of
a violet or brownish colom', rounded
and truncate both before and behind;
vesicles within sharply defined. The
Monas Okcnii of Weisse is very closely
allied, but still more minute. It pro-
grosses and revolves rather rapidly, taking

a straight course. The vesicles are not
present in very yoimg specimens : they
first show themselves as dark points, and
afterwards assume the vesicular form.
Perty cannot discover the filament de-
scribed by Ehrenberg in 3Ionas Oketnu
Eichwald savs of this species that it swims

or THE HTDEOMOBINA.

503

backwards or forwai-ds indifierently, —
a circiunatance adverse to the existence
of a filament at aU. 1-4800" to 1-2400".
Occm's among Characeae.

C. v-iolescem. — Globular or elliptical,
transparent, and of a very pale violet
colour. It appears closely related to, al-
though not identical with, Monas vinosa
(E.). A filament could not be detected,
nor any internal organs. At Bem, with

Chai-a. 1-14,000" to 1-3000". These
coloured organisms form a coloming
layer on the mud at the bottom of
ponds, &c. The several species men-
tioned by authors referable to the genus
Cliromatium are — Monas o-osea, Morren ;
Monas Okenii, Weisse ; Monas vinosa, M.
erubescens, M. ochracea, and probably
M. prodigiosa and M. gliscens of Ehren-
berg's category.

Genus ACAEL/EUM. — Extremely minute, globular or elliptical ; perfectly
transparent, without a trace of either external or internal organs.

AcABi^UM Crepuseulum = Monas Cre-
pmculmn (E.). — They swim rapidly paat
each other, yet have nothing in their

movements in common with those of the
Monads, but much rather with those of
the Bacterium Termo.

Genus EHABDOMONAS (Fresenius).

RHABDOMONAS inmrva. — Stout,
.elongated and cylindrical, slightly fal-
cate ; anterior extremity rather the
thicker; three prominent longitudinal
ridges ; green vesicles or granules occupy
the anterior half of the body ; progi'esses

in a straight liae, with a rotaiy or semi-
rotary motion on its long axis ; filament
11 the length of the body. 1-60 to
1-50 nullim. In stagnant water with
Confervse, &c.

Genus GEYIVLEA (Fresenius).

Grym^a vacillans. — Colom-less, hya-
line, compressed; when seen on its fiat side
its outline is cu'cular, but on the nan'ow
side, pyiifonn, the posterior compressed
portion gi-adually thickening towards the
thicker front part. Advances with the

thick end foremost, slowly revolving on
its long axis, with an oscillating motion.
Filament revealed by iodine. In stand-
ing water with Vallisneria in the Botanic
Gardens. It is, not milikely, the same
being as Monas urceolaris (Perty).

FAMILY II.— HTDEOMORINA.

Characters. — Anenterous Polygastrica without appendages ; body uniform
like that of the Monads, but, by reason of the spontaneous fission beino- im-
perfect, developed into a moniliform mass or polypary ; lorica absent. Indi-
viduals are at periods set free, which commence the same cycle of compound
development as the parent beings to which they originally belonged (Ehr )

The genera belonging to this family are Polytoma and Spondylomor'um.
Polytoma was described by Ehrenberg in the family Monadina ; but the sub-
sequent discovery of the genus Spondylomorum, ha^ing the same "•eneral
characters, and differing lilce it from the other monads, led him to create this
new family Hydromorina to embrace the two.

Pcrty has also recognized the propiiety of detaching those Monadina which
by the act of self-fission continuing incomplete, live together in compoiuid
masses, and to designate them has invented the term " Monadina Familiaria "
equivalent in English to "gregarious or aggregated Monadina." Under this
group, however, he has placed two other genera, wliich Ehrenberg lias let
remain, somewhat unaccoimtably, among those Monadina li^dng in an isolated
or free state. These other members of the Hydromorina °or Ago-re<rated
Monads are, Uvella and Antliophysa. Schneider {A. JSf H 1S54 jdv 32fi^
observes on the near alliance of Polytoma to Chloroqonium eurJdorum It
would seem that Cohn fails to find any truly distinctive characters between

504

SYSTEMATIC HISXORV OF THE INFUSOEIA.

Polylonia and Chlamydomonas ; for lie proposes {Bhitwiclc. p. 140) to apply to
P. Uvella the name of Ghl. hyalina.

Genus POLYTOMA (XVIII. 5 ; XX. 1-14).— Mouth terminal, truncate,
surmounted by a double flagelliform filament situated as in Monas and Uvella ;
eye and tail wanting. It wiU not imbibe colouring matter. A large con-
tractile vesicle and the trace of a nucleus are sometimes observable. Self-
division occurs both transversely and longitudinally, and produces a berry-like
cluster of many individuals. As the young increase in size, the parent body
assiimes a decussated or wrinkled appearance, like a mulberry, and in this
manner indicates its approaching self- division into many sections (as the name
Polytoma denotes), or numerous individuals. In swimming, the filaments are
extended in advance. In putting forward the self-division of Polytoma as a
peculiar feature, Cohn says that Ehrenberg has mistaken a transitional for a
permanent condition. It was known to MiiUer and "Wrisberg.

this more distinct (xx. 2). At the
anterior extremity are two reddish vesi-
cles, which ai'e contractile ; and other
non-contractile reddish ones are scattered
in the interior. The creatm-e " rotates
upon its axis ; and this, again, describes
circular vibrations upon a central point."
Self-division takes place at first into two
(xx. 3), then into four (xx. 9), and, under
favom'able conditions, into eight seg-
ments, each of which acquires its fila-
ments, and moves about within the en-
velope of the pai'ent with the rest imtil
set tree by its niptine. Under certain
circumstances the individuals pass to a
state of rest (xx. 7), and then do not
imdergo fission or any other change, but
remain in a torpid condition. In assum-
ing this state the filaments contract
gi-adually, and at length seem to be
withdl•a^vn completely within the con-
tained substance of the encysted being.
The internal granules of Poh/toma are,
according to Sclineider, composed of
starch, and are convertible into a blue
or a green coloming matter.

Polytoma Uvella (Manas Uva, M.).
— Coloiu'less, of an oval or oblong fomi ;
extremities equally obtuse. It is often
abimdant in water where animal matters
are in solution, upon which it appears to
be nourished ; generally in company with
species of Vibrio and Spirillum, and some-
times with Uvella Uva and U. Atomus.

Group 5 shows two isolated indi-
viduals ; another about to divide longi-
tudinally; a cluster of eight united
within a common envelope ; another
cluster, of which the common envelope
has disappeared prior to the separation
of the individual Monads, and in the
two isolated beings the double filament
is very distinct. 1-200" to 1-90";
diam. of clusters 1-380".

Schneider (Part I. p. 136) has closely
examined this species (xx. 1-14). The
hyaline investing membrane, he says,
can be distinctly displayed by using
chromic acid, or solution of iodine in
chloride of zinc. A globidar nucleus
lies near the centre, with a narrow red-
dish halo aroimd it : dilute acids render

Party has distinguished three additional species, viz. —

Polytoma Uva. — Divides into as
many as ten segments. The mode of
fission much resembles that of Chlamy-
domonas, but differs in exhibiting active
movements dirring the process, instead of
the state of rest seen in the latter. The
coi-puscles are usually oval, and hya-
line ; rarely yellow or brown ; filled with
larger or smaller vesicles, and in old
specimens with black molecules. Self-
cuvision proceeds rapidly. Movements
darting and revolving. An enveloping
cyst has been noticed in some examples.
Uncommon in frosh, but frequent in
water holding animal doromposmg mat-
ters in solution. Two varieties nre

distinguishable : viz. — Vai". a umjilis,
having only one filament, resembling
Trachelim globiilifer (E.), and very pro-
bably identical with Manas punctum ;
Var. b. rastrata seu hysginoidcs, of a
feeble yellow colour, with a prominent
cyst-wall, within which it is contracted
and deprived of its filament^!. It does
not break up on drying, but can continiie
several weeks without change. [Tliis is
evidently not even a variety in the proper
sense, biit simplv an encysted Polytoma.']
V. ocellata. — 0\a\ ; filled with vesi-
cles, like P. Urn, except that it has a
clear-rod stigma at the centre. Motion
languid. Self-fission produces few new

OF THE CBYPTOBIONADINA.

505

beings; and these lie parallel to each
other. Has the dimensions of P. Uva.
Foimd in decomposing infusions.
Schneider describes a peculiar mode
of fission seen at times in P. Uvella, in
which the segments lie parallel to each
other : very probably this supposed spe-
cies, P. ocellatum, is nothino' more than
that phase of P. Uvella. The reddish
vesicle is vrorthless as a specific character.

Genus SPONDYLOMORUM. — Individuals famished with a dorsal ocellus,
are destitute of a tail, and, in consequence of their imperfect self-division, deve-
lope a compound body (polypary) resembling a whorl or cluster of berries.

slender ; colour gi'een ; filaments foiu" to

P. ? virms. — Greenish or actually green,
sun-oimded by a hyaline cyst. Seen only
in process of fission, when each segment
had its own filament. These organisms
were for some seconds at i*est, and soon
afterwards moved here and there with
activity. Very probably this being is
only a sponile, and seems nearly aMu to
CJilainydomonas.

Spondyxomorum quaternarium. — A
gi'oup of four alternating corpuscles,
of which the terminal one is the most

five. Length of polypary 1-576", of each
individual 1-1728".

PAMILY in.— GRYPTOMONADINA.

(XYIII. 29-34 ; XIX. 7-16 and 20-31 ; XXVI. 6, 8, 9, 10.)

Th_e Ciyptomonadina {vide General History, p. 140) are Monadina enve-
loped within a distinct gelatinous, membranous, or hard induvium, forming a
sheU-like covering or lorica. According to Ehrenberg, the lorica sometimes
resembles an open shield (scutellum), at others a closed box or pitcher {uree-
olus). The construction of the lorica, however, as a scuteUum, open on one
side, is denied by every recent writer ; and in all'cases it woiild appear to
completely enclose the contents. Two delicate, filiform, and generally re-
tractile filaments, capable of being put into very powerful whirlmg and lash-
ing motion, are clearly perceptible in all the genera, excepting, perhaps, the
genus Lagenella ; and even in this. Dr. Wemeck believed he had discerned
them. Six or seven species exhibit internal vesicles ; and in two genera a
coloured spot is present at the fore part of the body. From the position of
this speck the dorsal line may be readily conceived, and a right and left side
described. Self-division, when it occm-s, is simple and complete. " It is
possible," says Ehrenberg, " that the fossil animalcules discovered in the flint
of chalk and porphyritic formations, and named by me Pyxidicula (see Plate
XVII. upper figiu'es), belong to the genus Trachelomonas,"

Lachmann (qp. cit. p. 219) asserts that in aU transparent Monadina and
Cryptomonadioa a contractile vesicle exists, and that even in the more opako
Chilomonas Paramecium and Cryptomonas ovata he was able to observe its
contractions. Mr. Carter confirms this statement.

The genera were thus tabulated by Ehrenberg : —

^ f Form short; solf-di vision "1 p .

longikidiiial or wanting J '-'''ypt^'

Eye-speck
absent.

Eye-speck
present.

Lorica obtuse and smooth.

itomonns.

Form long and tortuous : i ^ ,

self-diTision trimsverso j Opl^aomonas.

Lorica pointed anteriorly Prorocentrum.

Lorica with a nock and nan-ow orifice Lagenella.

Lorica an open shield

{scufeflum).
Lorica a closed box 1 ™

(urccolus). I Trachelomonas.

Lorica with orifice, but no
neck.

J Cryptoglena.

506

SYSTEMATIC HI8T0KY OF THE INFTJSOEIA.

The members of this family are reacUly recognized by the stifl&iess or in-
flexibility they display while swimming or when brought into contact with
other bodies. The lorica of Prorocentrum and Lagenella is at once perceived
to be a distinct covering. "When any doubt, however, exists upon this point,
a slight degree of pressure upon the specimens placed in an aquatic live-box,
or between two sHps of polished glass, will easily determine it. The lorica
of Trachelomonas Ehrenberg affirmed to be sihcious, and indestructible by
fire. Dujai'din has a parallel family he names Thecamonadina, consisting of
eight genera. These, however, are not the same as the genera of Cryptomo-
nadina of Ehrenberg, of which only two are retained, viz. Trachelomoims
and Cryptomonas. In the last-named genus are included CryptogU'oa and
Lagenella, which Dujardin considers have no claim to generic distinction.
Prorodon may, he thinks, be the same as his genus Oxyrrhis ; and under the
head of Trachelomonas he unites CJicetotyphla and Ghoitoglena, numbered
among the Peridiniaea iu the classification of Ehrenberg. A new genus,
Phacws, is constructed by the same author, to receive those green organisms
having a rigid inflexible tunic, which Ehrenberg placed with the flexible and
protean Evxjlenai. Another group, styled Diselmis, includes many of the
Chlamidomonads of Ehrenberg. Besides these, three other new genera, viz.
Crumenula, Ploeotia, and Anisonema, enter into this family Thecamonadina,
and are described as addenda to the Cryptomonadina of Ehrenberg, The
accompanying tabular view represents at a glance the distribution adopted by
Dujardin : —

Thecamonadina.

_ , 1 u 1 f Inteffument hard and brittle. . . 1. Trachelomonas.
Body ovoid or globular | lnte|ument membranous 2. Cryptomonas.

Body fattened or leaf-like, f With a caudal prolongation ... 3. Phacus.
with a single filament \ Without such 4. Crumenula.

The two filaments equal 5. Diselmis.

r Body prismatic or navicular ... 6. Ploeotia.
One flagelliform, one trailing I Body ovoid, in form of a grape- "1 Anisonpma

[ seed, with two filaments J '

With several filaments { ^^^o^iS°!!f } O^^"!^-

Perty borrows from both Ehrenberg and Dujardin, by instituting two
families, Cryptomonadina and Thecamonadina, and distributes the several
species in another fashion, under new generic names. The distinctive cha-
racters of the two families are thus set forth : —

Cryptomonadina. — The surface of the body more or less hardened, but in-
separable from the contained substance as a distinct testa.

Thecamonadina. — Possess a distinct red stigma, and, though naked at first,
acquire an apparently separable, brittle, silicious shell or testa, having an
opening at its fore part for the protrusion of the filaments. In the act of
fission the beings (which may or may not entirely occupy the shcU) divide
into two or four new individuals.

The Cryptomonadina comprise the genera Cryptomoms, PJutcotus, Anisomma,
Phacus, and Lepocinclis ; and the Thecamonadina include Chcetotyphla, Try-
pemonas, and Chonemonas.

Cohn (Siebold's Zeitschr. 1853, Band iv, pp. 275-277) sanctions this sub-
division of the Cryptomonadina into two families ; for he remarks that Crypto-

OF THE CEYPTOMONADINA.

507

monas and Cryptoglena, and other forms, have a hard integument or lorica
(Panzer) inseparable from the subjacent mass, whilst Trachelomonas,Lagmella,
and Chcetoglena possess a distinct separable capsule or cyst, within -which, at a
certain period, the contained Euglena-like being can contort itself and revolve
at pleasure. Moreover, Cohn's opinion is that these capsuled forms should
be detached from the Monadina or Cryptomonadina, and placed with the
Euglense. In this opinion we entirely coincide, and would regard the cap-
suled monadiform beings as simply encysted Euglence. Indeed, the present
state of knowledge, especially respecting the process of encysting, irresistibly
leads to the conclusion that this entire family Cryptomonadina of Ehrenberg
must be broken up, and its several forms distributed among various groups of
animalcules and plants, as representing their encysted phase or condition.

Fresenius adds a new genus to the Cryptomonadina, which he calls Dre-
panomonas.

Genus CEYPTOMONAS (XYIII. 29).— Coloured stigma absent; lorica
obtuse, or not attenuated anteriorly ; body short, but not filiform ; self-divi-
sion, if any, longitudinal ; flageUiform filament very fine.

Dujardin writes, " In this genus Gryptomonas I comprise all Thecamo-
nadina vdth a single filament, and with a lorica neither hard nor brittle, and
whose body is not depressed (compressed) like that of Pliacus or of Crummula ;
and I moreover do not doubt that when these Infusoria are better known,
other genera may be distinguished by their more or less globular form, by
the consistence of their envelope, and especially by their mode of existence.
I already indicate as subgenera, Lagenella with an elongated lorica, and
Tetrahcena, the species of which are united in groups of four, not enclosed,
however, within a common envelope. As to the character supplied by the
presence of a red speck in some individuals, assumed by Ehrenberg to be an
eye, I cannot discover in it a generic distinction ; nor am I able to admit the
existence of a lorica open on one side (below) like a shield (carapace). On
the contrary, I have always observed the lorica to be closed and entii-e,
though sometimes compressed on one side, adapting itself to the living mass
enclosed. The covering in every case is evidently larger than the contained
mass, a diaphanous space intervening between the two visible in the fom
of a clear ring." Of the species enumerated by Ehrenberg, Dujardin re-
marks that " 0. curvata is so compressed that it is properly refei'able to our
genus Crumeniila." C. glauca and C. ftisca he regards as doubtful species.

Perty briefly characterizes his genus Cnjptomonas thus : — " Body an elon-
gated urceolus, from the anterior and mostly-rounded extremity of which two
filaments arc protruded, somewhat exceeding the length of the body ; within
arc usually one or more dark nuclei, from wliich the vesicular germs seem to
be developed."

CnypTOtoNAS curvata. — Green, com-
pressed, slightly bent like the letter S,
and twice as long aa broad. Amongst
Confervfc. 1-570".

C. ovata (JEncIieli/s viridis, M.) (xviii.
29). — Green, depressed oval, and twice
as long as broad ; motion slow, vacil-
lating, and rotating on tlio longitudinal
axis, but when obstructed (says Eln-en-
berg) is seen to leap ; lorica paper-lilfe,
not hard; numerous internal transparent

vacuoles and gi-een granides. In the
middle of the creature there are two or
three egg-shaped nuclear bodies, and at
the posterior part a single vesicle ; self-
division not observed. Found amonirst
Conferva). 1-570". ^

C. erosff.— Greeiij hyaline anteriorly,
depressed, oval. In clean water amoiiff
Conferva). 1-960". ^

C. cyUndnca {Enchclys viridis, M.).—
Elongated, subcylindrical, three times as

508

SYSTEMATIC HISTORY OF THE INFUSOHIA.

long as broad. Amongst Conferva).
Almost 1-1000".

C. (?) glauca. — Oval, twice as long
as broad; anteriorly truncated with a
double flageUifonn proboscis ; body tm--
gid, and of a bluish-green colour.
Foimd with Clilamydomonas Pulvisculm.
1-864".

C. (?) fusca.—Oval, turgid, and of a
brown colour. Amonffst Confen-ae.
1-1500".

C. lenticularis. — Orbicular, resembling
a lens ; colour gi-een : lorica thick.
1-1729".

The following are described and named by Dujardin : —

C. Globulus. — Globular, green, often
with folds (stiipes), the diaphanous en-
velope neai-ly filled. 1-2600" to 1-2250".
This species, in Perty's opinion, is a
sporule of a plant, or a 'sporozoid.'

C. inwqualis. — Ovoid, green, of less
thickness than breadth, with a longitu-
dinal depression, and one or two unequal
notches in the coloured portion, which
is always smaller than the envelope.
1-2600". In stagnant sea-water, impart-
ing to it a green coloiu'.

C. (Lagenella) iiiflata. — Ovoid, en-
larged posteriorly, conti-acted anteriorly ;
envelope transparent, thicker about the
anterior neck-like portion, filled with a
green substance, having a central red
speck; motion zigzag. 1-1180". In a
vessel of marsh-water with Lemna.

C. (LAGBNELLA)e«<c7tZ0J-a(XVIII. 31). —

Ehrenberg has described under this name
an Infusorium of the same size, differing
from the last by its more elongated form,
and especially by the green contents more
completely occupying the anterior neck-
like portion, whereas in ours but a nar-
row sti'eak is visible.

C. (Tetbab-ena) socialis. — Regularly
ovoid, green, with a central red poiut,
enveloped by a thick diaphanous lorica ;

commencing self - division frequently
seen; occurs in regular groups of four
individuals, simply agglutinated, and
having their filaments directed all to
the same side. 1-1700" to 1-1300".
In a water-butt in the King's garden,
Paa-is. "I should have taien," says
Dujardin, "the specimens of Tetraheena
socialis at first for Gonia, if a trace of a
common enclosing envelope had been
foimd ; yet I cannot doubt that they have
the closest analogy with the true Gonia,
and vsdth what Ehrenberg has called
Syncrypta in his family Volvocina. One
may suppose that the commencing self-
fission observed in some individuals
would give rise to such gi-oups upon the
desti'uction of the lorica (integument) in
these different genera. This mode of
propagation occurs undoubtedly in most
of those having a soft gelatinous integu-
ment ; but in animals like Trachelomonas,
whose lorica is hard and brittle, we can-
not understand how multiplication does
take place."

In the addenda to his treatise, Dujar-
din has this remark : " I am convinced
that my Ci'yptomonas (TetrabcBna) be-
longs rightly to Gonium."

The generic characters of Ci-yjptomonas, as understood by Perty, have been
detailed ; the following are the species he describes : —

C. polymot-plia. — Is so veiy vai'iable in
form that no single description can be
applied to it. It ranges between 1-840"
to 1-300" in length, and may be green
or colouiless, brown or golden yellow,
and contain at one time red specks, at
another not. The smallest are usually
yellow or of a verdigris-green : many
small ones are hyaline ; the largest sea-
gi'oen and brown. These changes of
colour are doubtless duo to the choro-
phyll developed within these minute
organisms, and to the modifications this
matter undergoes in dillbrent slftges and
conditions of life — a subject well exa-

mined and illustrated in Braim's work
on Rej uvenescence in Nature. In figure,
individual specimens are oval or globu-
lar, compressed, and emarginate. Small
ones move rapidly, frequently in circles ;
larger examples more slowly, and at
times backwards. The species is com-
mon among Confervns the whole rear,
and under the ice in ^vintcr. terty
assumes it to represent the following
species of Cryptomonas named by Ehren-
berg, ^-iz. C. curvata, C. ovata, C. crosa,
C. cylindrica, C. ylauca, and C. fttsca,
and also Chilomonas raramccium.

OF TKE CRTPTOMONABINA.

509

C. dubia. — Quite flattened, elliptical,
not rounded anteriorly ; of a dear green
colour, with a hyaline central band,
and, in most instances, a red stigtaa.
Movement rather quick; the filament
not seen. 1-1900" to 1-1400". It is

allied to Cnjptoglma pigra, C ccerulescens,
and, in a less degree, to C. conica of
Ehrenberg.

0. urceolaris (Smarda). — ^Belongs, by
reason of its firm testa, to the Theca-
monadina.

Genus OPHIDOMONAS. — Body filiform ; eye-speck absent ; lorica smooth,
obtuse, and tubular with a single filament ; self-division transverse and com-
plete ; internal vacuoles numerous. Its extremely small transverse diameter
is the gTeat impediment to a better acquaintance with this being. (It has not
been figured.)

Ophidomonas Jenensis. — Very thin,
curved spu-ally, and equally obtuse at
both extremities; colom* olive-brown;
motion brisk. In well-water. 1-570".

0. sanffuinea.—Vevy slender, the in-
terspaces between the vacuoles filled
with a red coloiu:. 1-576". In brackish
water.

Genus PEOEOCENTEUM (XVIII. 30).— Lorica resembHng a Httle box
(urceolus), smooth, pointed at the anterior extremity ; eye-speck absent ; pro-
boscis filiform ; vacuoles numerous. Self-division has not been observed. "It
is worthy of remark," says Ehrenberg, " that the only species of this genus
with which we are acquainted [i. e. in 1838] belong to the luminous crea-
tures of the sea, which, perhaps from some peculiar organic relation or con-
dition, yet unknown to us, are instrumental in producing that curious and
certainly vital phenomenon usually termed phosphorescence." It may be
further noticed, that aU the luminous Infusoria of the sea, hitherto discovered,
are characterized as being of the same yellowish waxy colour as the best-
known species of this genus — P. micans ; and it is probable that this condition
is immediately connected with the interesting phenomenon in question.

cates the position of the supposed
mouth. 1-430".

_P. viridis. — Ovate, suborbicular, tiu--
gid; posterior end rovmded; anterior
shortly pointed ; colom- green. 1-1100".
In the Baltic.

Probo CENTRUM micaus. — Oval and
compressed, attenuated posteriorly, but
dilated and pointed anteriorly ; colour of
yellow wax. In sea- water, (xvui. 30).
Two figm-es, magnified 300 diameters;
the first is a side view, the latter a back
view ; the filament in the former indi-

Genus LAGEISTELLA (XVIII. 31). — Distinguished from other loricated
monads by the lorica being extended anteriorly, or flask-shaped. The lorica
is perfectly distinct, and crystalline. Within are the bright-red speck and
green granules. (Vide Cryjptomonas Lagenella, p. 508, and Chonemonas
Perty, p. 613.) '

Lagenella eucldora (xviii. 31). — crystalline ; colour
Oval, neck short and trimcated ; lorica Confervro. 1-1200".

green. Amongst

Genus CETPTOGLENA (XVIII. 32).— Lorica open, in the form of a shield
(scutellum), folded or rolled inwardly at the sides, and without a proiectino-
neck. Eye-speck distinct ; granules green in all the species. In C. conicn
two oval greyish masses are seen in the centre, and also two filaments. Self-
division not observed. These characters, given by Ehrenberg, are valueless to
distinguish Onjptoglena from other Cryptomonadina, or from CMamydococcus
The scutollar form of the lonca is an error ; for it forms a complete investment'
mten-upted only at the point where it gives exit to the filaments The red
eye-speck is no distinction, as so often remarked ; and the absence 'of a neck
like extension of the lonca is seen in Cryjptomonas, Chlamydococcus, and other
genera Carter describes one species with four filaments. Wo unite m'th
Dujardin in rejectmg this as an independent genus.

510

SYSTEMATIC HISTORY OF THE INFU«0EIA

Cbyptoglena conica (xviii. 32). —
Conical, anteriorly dilated and trun-
cated ; filanaents two, half the leng:th of
the body ; posterior end acutely attenu-
ated. Colour blmsh-green. Abundant
in river water, in company with Crypto-
monas glauca, from which they are
readily distinguished by theii" form,
larger size, and red eye. They move
briskly in the direction of the longitudi-
nal axis of theu' bodies, but when ob-

structed spring or leap out of their direct
course. 1-1100".

C. pigra. — Oval, approaching to glo-
bular, and emarginate anteriorly ; colour
a beautiful green ; movement slow. In
water when covered with ice. 1-3000".

C. cesrulescens. — Depressed, elliptical
and emarginate anteriorly ; colour bluish
green; motion quick. Amongst Con-
fervse. 1-6000".

Mr. Carter has added and figured some new species, viz, —

thick envelope, and are divided into

C. lenticulmis {A. N. H. 1858, p. 253).
— Spherical, compressed ; lorica distinct
and stout; endochrome separated fi'om
it by a distinct clear zone ; contrac-
tile vesicle seated at the point of in-
sertion of the two filaments, where
there also seems to be an intemiption
in the continuity of the lorica (emar-
ginate) ; ej'e-speck on one side, nucleus
visible. The horizontal view is ovate,
and acimiinate at both ends. Fission
takes place in the power of two, just
as in CJilamydococcus, from which in-
deed no satisfactoiy distinctive fea-
tures are perceptible in the engravings
famished.

C. cordiformis. — Distinguished by its
cordiform lorica. The contents are orbi-
cular, and do not nearly fill the lorica ;
filaments four ; a resting-stage perceived,
wherein the contents are covered by a

numerous ce lis (microgonidia.)

C. angulosa {A. N. H. 1859, iii. 18).—
Lorica compressed, oblong, angxilar,
shield-shaped, transparent, round poste-
riorly, sqimre anteriorly, where it pre-
sents a short neck in the median line for
the passage of the cUia; border thin,
curled up posteriorly and anteriorly on
opposite sides. Internal or green cell at
some distance from the lorica, angular,
lined with chlorophyll, provided with
two cilia, which issue through the neck
of the lorica ; two conti-actile vesicles at
their base; an eye-spot median and
peripheral, and one to four starch-ceUs
of a circular foi-m. Swimming with its
cilia foi-wards in an extremely in-egulai"
line. Length of lorica 1-1080", and
breadth 1-1800". Freshwater tanks in
the island of Bombay.

Genus TRACHELOMONAS (XYIII. 33, 34 ; XIX. 9-11).— Have a single
long filament, an eye-speck, and a closed elongated or spherical lorica, with-
out a projecting neck. Very minute transpai'ent vesicles have been discerned
in T. nigricans and T. volvocina. It is probable that some of the highly inter-
esting ajaimalcules which enter so abundantly into the silicified substances in
certain chalk formations belong to tliis genus. The genus Trypemonas
(Pertj) is equivalent to this, the characters of which are hereafter given at
large in Perty's words (p. 513).

Trachelomonas 7i{g}-icatis. — Oval,
approaching to globular; coloiu- rarely
gi-een, mostly of a reddish or blaclrisii
brown. Eye-speck brown. 1-1700".

T. volvocma (xvin. 33, 34 ; xix. 9, 10).
— Spherical, with a delicate filament;
colour mostly green, sometimes of a
brownish hue, with a distinctive red
ring around the body : between the in-
ternal vesicles is a very fine gi-anidated
substance, to which the colour of the
body is due. The red circle, so re-
markable a feature in this species,
always appears in the same horizontal
position, now c^uickly soever the creature
may be revolving on its long axis. The
uppermost figure represents the flnbellum

extended ; in the next it is retracted ; the
lowest of the three is a very young spe-
cimen; and 84, a full-gi*own one that
has been forcibly pressed and the lorica
broken. ^Vjnongst Confervaj. 1-860".

T. cylindnca (xix. 11). — Oblong, ap-
proaching to cyluidrical ; filament almost
aa long as the body. Colour a beautiful

freen ; eye-specli red ; ring piuTile.
-1000". 'Perty points out the fact that
T. nigricans is nothing more than an
old specimen of this species, brown and
opake by age.

T. arfiolata. — Globose, surface areo-
lated.

T. as])era. — Similar to preceding, but
its surface covered with rough points.

OF THE CRYPTOMONADINA.

611

T. gi-anulata. — Similar, but its surface
very minutely granulated.

1". l(eins. — Globose, with its surface
smooth. The assigned differences be-

tween the surface of this and the two pre-
ceding are too trivial to be characteristic.

T. pyrum. — Oblong or pear-shaped
(pyrifomi), smooth.

Dujardin, in his family Thecamonadina, includes some genera of animalciiles
not described by Ehrenberg, or described by him under different names and
according to a different arrangement. They ai'e appended here as best agree-
ing mth the Cryptomonadina.

Genus PHACUS (D.).— Body flattened, leaf-like, and mostly green. It
displays a red speck in fi'ont, together with a flagelliform filament ; and the
resistant membranous integimient is prolonged posteriorly in the form of a tail.

" Three out of the fom- species are referred by Ehi'enberg to his genus
Euglena, on account of similarity in colour. The difference between the two
genera is, however, considerable ; for iu Euglena the iutegument is contractile,
and permits of a freqiient change of form, whilst iu Phacus, on the contrary,
the iutegument appears quite wanting in contractility, and the animal inva-
riable in form.

" The enclosing integument of Phacus persists after the death of the animal
and the destruction of the contained green mass, and also after the action of
various chemical agents, becoming, in the latter cases, quite transparent.
The motor filament disappears with the living contents; globules of the
latter remain after death."

Mr. Carter {A. N. H. 1856, xviii. p. 241) describes a single, glairy, discoid,
capsuled body in the centre of Phacus, as weU as in the large lip of Crume-
nula texta.

1. Phacus pleuronectes = Euglena pleuronectes ; 2. P.longicauda — E.longi-
cavda ; and 3. P. triquetra = E. triquetra. (See Ettglena.)
The new species, of which the characters are given, is

Phacus tripteris. — Oblong, with
three longitudinal plaits meeting along
the axis, rather twisted on the midrib,

with a red speck in front and a dia-
phanous caudiform prolongation behind.
1-420" to 1-312".

Genus CRUMENULA (D.) (XXVI. 6).— Oval, compressed, covered by a
resistant integument (testa) apparently reticulated, sending out a long flagelli-
form filament obliquely from a notch in the anterior border. Motion slow.
There is no tail-like prolongation, as in Phacus, A contractile vesicle present.

Cbxtmenula texta. — Envelope re-
ticular, filled with a green matter, toge-
ther with vacuoles or hyaline globules,

and having a large red globule anteriorly.
1-520". Testa persistent after death.

In this species Mr. Carter (op. cit.
p. 119) describes an inner layer of

pointed sigmoid fibres aii-anged pai-aUel
to each other, so as to form a conical
cell, which remains behind when the
softer contents have dispersed.

The anterior notch is produced by a
sort of overhanging lip. The filament
is three times longer than the body.

Genus DISELMIS (D.).— Ovoid or globular, covered by an integument, not
contractile, of almost gelatinous consistence ; two equal locomotive filaments
proceed from the anterior extremity.

" This genus nearly corresponds to the Chlamyclomonas of Ehrenberg, placed
by him in the family Volvocina by reason of its apparent self-division into
two or four segments within the testa. Dujardin, on the other hand, admits
none as Volvocina which do not exhibit an aggregation of perfect individuals
within a common envelope."

The removal, by Dujardin, of the Chlaraydomonads described under this
name of Diselrm^, from Volvocina to Cryptomonadina, is genoraUv held to
be an error, dependent on an imperfect conception of their characters and
true affinities. (See genus Cui.amydomonas.)

512

SYSTEMATIC HISTOEY OF THE INPUSOllIA.

The integument of Diselmis is non-resistant, diaphanous, breaks up after
death by diffluence, and is sometimes filled with a green substance. Like
plants, these beings are sensitive to light, fix themselves to the lightest part of
the containing vessel, and disengage oxygen when exposed to the sun's rays.
In the green substance are seen granular masses, a disk with an expanded
border, and a red speck. The motor filaments proceed from the same opening
of the integument, and often form a diaphanous lobe projecting from the
opening; The red colour oftentimes seen in the water of the Mediterranean
appears due to Infusoria of this genus.

Diselmis viridis = Chlamydomonas
pulviscidus (Ehr.) (xrx. 16).

D. marina, — Nearly globular, obtuse
and rounded in front, gi-anular within.
1-1050".

This species is larger than J), viridis,
more globular, and apparently deficient
of the red speck. In stagnant sea-water
of a green colour.

D. a7igusta, — Pyi-iform, oblong, ap-
pearing to be plaited and tubercular

inside, sometimes with an indistinct red
speck. 1-2600" to 1-1850".

D. Dunalii. — Oval or oblong, often
constricted about the middle ; colomless
when very young, then green, afterwards
red ; with 2 flagellifonn filaments longer
than the body, seated on a projecting aud
retractile anterior lobe. Interior occupied
by coloured globules. Discovered by
M. Joly to be the chief cause of the red
colom- of the water of the Mediterranean.

Genus ANISONEMA (D.) (XIX. 8 ; XXYI. 8).— Colourless, oblong, more
or less compressed, having a resistant envelope giving exit by an opening to
two filaments, one directed forwards and flageUiform, the other trailing back-
wards and retractile ; movement slow.

" In other genera, as in Heteromita, two similar filaments exist ; but the
present genus is known by its non-contractile resistant integument, which is
often met with empty and transparent. It may be that the Bodo grandis
(Ehr.) is allied to this genus as well as to Heteromita.'"

ti'ailing : he supposes it in the act of
fission ; but his tigm-e does not show it.

A. sulcata (xxvi. 8). — Oval, depressed,
with 4 to 5 longitudinal ftuTows, and an
oblique notch m front, from which the
two filaments proceed ; movement vacil-
lating, circular. Perty has seen it divide
longitudinally. 1-1300". The proiecting
filament is three times, and the fioating
one about twice as long as the body;
in this, however, says Perty, there is no
constancy.

Anisonema ^cmws (xix. 8). — Oblong,
depressed, roimded posteriorly, and nar-
rower in front, like the seed of an apple,
with an opening close to the apex;
colourless and transpai'ent, except a few
vesicles, mostly green, but occasionally
red ; movement m a sti'aight line for-
wards. 1-1300" to 1-850". In pond-
water. This species = Bodo grandis (?)
(Ehr.). Perty gives afigm-e of an organ-
ism he identifies with this species, hav-
ing foiix filaments anteriorly and none

Genus PL(EOTIA(D.) (XXVI. 10, a, 6).— Diaphanous, having several ribs
or longitudinal ridges along the middle,and a cu-cular ti-anslucent margin, giving
the whole a navicular fonn ; two locomotive filaments proceed from one end.

This distinct form might be mistaken for one of the Bacillaria, were not
the filaments clearly ^^sible. The characters of the filaments are similar to
those of Anisonema — one extending forwards with an undulatoiy movement,
the other trailing and capable of suddenly arresting the movement of the
body by its adhesion and power of retraction.

Plceotia vitrea (xxvi. 10 a, h). — Ily- I 1-180" ; movement slow. In sea-water
aline, with 3 to 4 londtudinal salient j kept for two months,
linos at the centre, and some granules. I

Genus OXYRRHIS (D.) (XXVI. 9 a, 6). — Ovoid, oblong, obHquely
notched in front, and pi-olonged into a point ; several flagclliform filaments
proceed laterally from the bottom of the fissure.

OF THE CKYPTOJIONADINA.

513

vidual. Medium size 1-1440". Amoug
Confervffi. Bern. It = Ch-yptomonas
lenticular is (E.). Like Dujai-din, Perty
removes Chcetotyplila and Chcetoglena
from the Peridinisea to the Thecamo-
uadina. The fonner genus he retains,
but merges the latter in liis group
Clionemonas,

The name is indicative of the elongated apex. These Infusoria being but
imperfectly known, one species only is described : —

OxYKRHis marina (xxvi. 9 a, 6.)— Colomless ; subcylindrical rugose, roimded
posteriorly. 1-520". In the Mediterranean.

The next three genera are taken fi-om Perty, the first being one of his
Cryptomonadina, the others Thecamonadina : —

Genus PHACOTUS (XIX. 7, a, h, c).— Body round, biconvex, -ndth two
(possibly fom-) filaments.

Phacotus viridis. — Green, usually
divided thi'ough the middle by a clear or
a dark line. Margin acute ; the central
part more or less convex, sometimes
elevated into a shai-p angular ridge, ren-
dering the figiu-e four-sided. The shell
shows a double contom*, and persists
some days after the death of the indi-

Genus TEYPEMONAS = generaUy TRACHEL0M0NA8 (Ehr.) (XIX. 9,
10, 11). — Shell globular or elliptic, with a small round aperture (the elevated
margin of which frequently produces a funnel-like appearance), from which
the filament protrudes ; colour green, with a red stigma ; lorica at first hyaline,
then purplish, and lastly brown, thick and opake ; not armed, but apparently
porous ftom the presence of numeroxis puncta indicating the absence of
deposit, as elsewhere. Perty justly objects to the term TracJielomonas, as
prone to cause confusion of ideas from its etymology signifying beings with
necks, which none of those it includes possess.

Trypemonas vohocina (xix. 9, 10) = Trachelomonas volvocina; and T. cylindrica
(xix. 11) = Trachelo7nonas cylindrica and T. nigricans (Ehr.).

Genus CHONEMONAS (XVIII. 35 a, h, c, c^).— Green with a red stigma ;
testa hard, eUipsoidal, with a fimnel-shaped opening at the anterior end — from
which two filaments proceed. It represents in part the genera Chcetoglena,
Fantotrichum, and Lagenella (E.).

Chonemonas Schrankii (xvin. 35 a,
b, c, d), fonnerly named U. hisjnda. —
Lorica clear or dark brown, more or less
spinous. Filaments double the length,
and hyaline. Portions of the lorica ex-
hibit apparent pores, and empty speci-
mens often decussating lines. The green
contents escape unhurt on fracturing
their enclosing case, which they gene-
rally do not fill. When fission proceeds,
the contents alter their foi-m, and the
filaments disappear. Onward movement
not rapid, seldom oscillating, but actively
revolvmg. 1-900" to 1-540". At Bern,

in pools of snow-water, and beneath the
ice. Two varieties occm- : — a. glabra,
with a smooth lorica, which is no other
than the Lagenella cuchlora (E.) ; b.
unifilis, with a single filament, equi\-a-
lent to Chatoglena vohocina (E.). The
very hispid examples of this Chonemonas
ai-e = Pantotrichuin Laqcmila, placed by
Ehrenberg among liis Cyclidiua.

C. acuminata. — Shell oval, strongly
pointed posteriorly ; bristles scarcely ob-
aorvable. Funnel at front distinct.
1-500". Hyaline and c^uite smooth speci-
mens also occurred. On the St. G othard

Genus DEEPANOMONAS (Fresenius).

Drkpanomonas dentata. — Colourless;
falciform, compressed; pointed at each
PTid, with five outspreading furrows, of
wliich two are on either flat side, and
one on the convex edge. In the centre
of the concave surface is a ventricose
swelling with a small tooth-like process ;
a similar process is remarked beneath

the apex. From near the last, several
fines extend upwai-ds and outwards. In
one aspect an undulating line is percep-
tible along the convex margin; this is
also visible in tlie loricte of dead specil
mens. Internally are only colouriess
gi-anulcs, in;parting a pearly hue. On
one occasion a vacuole was seen havin.>-

2l

514

SYSTEMATIC HISTOEY OF THE INFUSOEIA.

a reddish glinuuer ; possibly a contrac-
tile vesicle ; moven^ents slow ; no con-
tractions of figiu'e obsei-ved. Both ends
furnished with delicately motile fila-
ments, those on the anterior longer

than those on the posterior extremity ;
but still seen with diiliculty. In swiiii-
ming it lies on the flat surface ; it also
revolves on itslong axis. 1-15"' to 1-14"'.
In water from Walldorf.

FAMILY IV.— VOLVOCINA. (See p. 144.)

(XIX. 32-69; XX. 22-47).

This family deiives its name from the genus Volvox, and from the rolling
motion with which the beautiful creatures belonging to it make their way
through the water. They resemble the Monads in most particulars relating
to their organization ; have an unvarying form, and, except a filament, no
appendages ; vacuoles present. Whilst propagation by self-division is pro-
ceeding, and the young are increasing in size, the surrounding envelope or
lorica is observed to expand in a con-esponding degi-ee, but continues entire
until its numerous occupants have come to matiuity, when it bursts and sets
them at liberty.

All the genera are provided with organs of locomotion, which consist, as
•with the Monads and Cryptomonads, of a single or double very delicate fila-
ment ; and hence it is that when they are clustered, the entire group appears
to be ciliated, or beset with haii's. Besides granules, one or two round nuclei
and a contractile sac are present.

This family Ehrenberg disposed into ten genera — five furnished with a red
stigma, situated at the anterior pai't of the body, and five without it. In the
foi-mer, a sensitive system was presimied on the supposition of the red speck
being an eye.

The following is an analysis of the family : —

f ( ( vibrating

filament absent

Lorica box-like <
Tail J Lorica single ' | vibrating |

absent ' I, filament present J

J Gyges.

Pandorina.

\ Clusters tabulated or in plates Gonium.

^ Lorica double Syncryiita.

Tail present Syiuu*a.

u

Self-division both
equal and perfect
(no internal globes)

Self-di\'ision unequal
(forming internal
globes).

j^TaU present Uroglena,

filament single . . . Eudorina.
filament double . . . Qilamydomonas.
Filament single Sphjcrosira.

Tail absent

Filament double Volvox.

The above account, derived from Ehrcnberg's work, affords a veiyjmpcrfoet
conception of the Volvocina, especially of their stnictui-al characteristics as a
family, — a defect wc have endcavom-ed to supply in the chapter on^tlieir
general history (p. 144). Moreover, as there noticed, these beings are
numbered by the majority of natui-alists, at the present day, among plants,
although a respectable minority, among whom are Thiu-ct and Lachmann,
incline to the opinion that they are for the most part animals, as Ehrenberg
represented. Thui-et expressed this opinion now several years since, when
the physiology of the simplest vegetable organisms was imperfectly imder-

OF THE VOLVOCrNA.

515

stood, and supported it on the fact that an act of germination, similar to
that seen among the spores of the lower Algfe, was never witnessed among
the Yolvocina. This absence of a supposed vegetable characteristic, more
recent reseai-ches appear clearly to set aside as an ai-gument against the
vegetable nature of a doubtful organism ; for in the whole cycle of life of
many of the simplest, or so-called imicellular plants, an act of germination,
as understood by Thui-et, never oeciu-s. Dujardin, when he published his
work on Infusoria in 1841, admitted the Volvocina among animalcules, but
proposed a different distribution of thieir genera to that put forward by
Ehi-enberg. Thus, he transferred Oyges and Chlamydomonas, owing to their
not being aggregated mthin a common envelope, to the Thecamonadina, and
united Eudorina with Pandorina (XIX. 59-69), and Synura with Uroglena,
because he could not regard the presence or absence of a red speck to be a
generic characteristic. Further, he considered Synorypta a doubtful genus,
and combined Sphcerosira with Pandonna.

Although the present state of science proves that the appearance of a red
speck or specks in a monadiform being is mostly a transitory phenomenon,
associated with a certain condition or phase of existence, and that therefore
the union of Eudorina with Pandorina, and of Synura with Uroglena, is a
correct proceeding, yet Dujardin erred both in detaching Oyges and Chlamy-
domonas (XIX. 16) from the Volvocina, and in considering SpTimrosira and
Pandorina modifications of a common form. The relation of Chlamydomonas
to the Volvocina has been well shown by Cohn, Braun, and others ; and
Gyges itself might probably be dispensed with as a distinct genus, since there
is good evidence to show that its species are simply stages of development of
Chlamydococcus or Protococcus (XIX. 20-31), and of Chlamydomonas. Again,
Spha'^'osira, instead of being a varied phase of Pandorina, is a member of the
genus Volvox ; indeed Prof. Busk inchnes to the notion that it is merely a
developmental stage of the common Volvox Globator {T. M. S. i. p. 39). Perty,
however, advances as an argument for its independent nature, that it is com-
mon about Bern, whilst Volvox Globator is not met with. This fact speaks
at least for the specific independence of Sphoirosira, although its generic
must be given up. Moreover, a genus Botryocystis was instituted by Kiitzing,
of the independence of which, however, there is no good evidence. The con-
dition ot Protococcus pluvialis (Cohn, Ray Soc. 1853, p. 559), when divided into
sixteen segments, corresponds to the Botryocystis Monim. Fm-ther, the last-
cited author in another treatise {EntwicJc. d. Mihroslcop. Alg. und PiJze, p. 209)
treats Botryocystis as synonymous with Pandorina, and in this agrees "with
Prof. Henfrey, who remarks {M. T. 1856, p. 51) that the form of Pandorina
which produces the resting-spores, after losing its ciUa, is Kiitzing's Botryo-
cystis Morum. Perty coins two new genera, called Synaphia and Hirmidium
(XIX. 15). Cohn points out a natural division of the Volvocina into two
sections, in the first of which, represented by CJilamydomonas and Chhmy-
dococcus, the fission of each primordial cell is complete, and the products
single and unicellular, whilst in the second section, including all the rest of
the Volvocina, the cells formed by the fission of the parent primorchal cell con-
tinue united in groups or clusters. The difference between the several genera
obtains from the disposition of the produced cells ; and this, again, depends on
the direction of the line of fission. Thus, in Stephxmosphmra (XIX. 38-52)
the plane of fission is the meridian of the sphere ; in Oonium it occurs in two
planes at right angles to each other, and in Vohox and its allies in three
planes. If the Volvocina are referable to the vegetable kingdom, they consti
tute a famUy of the order Palmellacete (Cliamacphycca;, A'.), among the Alefe
Tlie separation of Syncrypfa from Oyges, and its independent generic ex-

2 r, 2

516

SYSTEMATIC niSTORY OF TUE INFUSOniA.

istence, arc vciy questionable ; for the possession of a double loiica, attributed
to Symnjpta by Ehrenberg, cannot serve as a generic distinction from Oyges,
■udth a single lorica, since Cohn has shown in Chlamydococcus that the pro-
duction of a distinct, loosely investing, and apparently second covering, is one
of the series of developmental phenomena in the selfsame being. The same
statement is true of the so-called tail which is used to separate Synura from
other allied forms ; for caudate beings make theii- appearance in the cycle of
existence of non-caudate : thus a caudate variety of naked " zoospore " re-
sembling a Bodo is represented by Cohn in his illustrations of the multiform
phases of Protococcus. The presence of a mouth, and the constniction of the
envelope with one side or end open, through which the animal can protnide
itself at will, are statements now generally ignored.

After excluding the iaadmissible and the very doubtful genera of this
family of Ehi-enberg, there remain only Pandorina, Gonium, Chlamydomo-
nas, and Volvox. To these, other naturalists add Ghlamydococcus (Braun),
Gloeococcus (Braun), StephanospJuera (Cohn), and Stephonoma (Wemeck).
Ehrenberg himself has added a new genus he names Trochogonium ; but, from
the imperfect description given, it is not possible to decide accurately whether
it is distinct from some of the genera instituted by other natm-alists.

Genus GTGES. — Lorica of a simple box-like form (urceolus) ; eye-speck
and ' tail ' absent ; filament doubtfully present ; the internal organization is
little known. Two species are mentioned by Ehrenberg, both of a green
colour and enclosed in a transparent lorica.

Gyges Granulurn (Volvox Granulum,
M.). — Oval, or nearly globular; con-
tained granules of a darldsh green coloiu'.
Amono-stLemnEeandConfervfB. 1-1150".

According to Cohn (on Protococcus,
p. 559) the encysted motile zoospore
(xrx. 3l) of Protococcus ( Chlamydococcus)
pluvialis is the same as this species Gyges
Granulum; whilst the same zoospores di-
vided into two must be regarded as the
next species, Gyges hipartitus.

G. hipnrtittis. — Crystalliae, gelatinous,
and nearly spherical ; the superficies co-
lom-less, but its granular contents yel-
lowish green ; it is sometimes seen di-
vided into two, at others as a simple
sphere. Amongst Confervte. 1-480".

G. sanguineus. — Oval, red, inclining to
crimson, surroimded by a broad colom'-
less ring representing the enveloping
lorica. This species was discovered by
Mr. Shuttleworth in the red snow which
fell at the Grimsel in August 1839. Its
motion is lively. Group 527 (xra.)
shows several highly magnified. Found
with Astasia nivalis and 3Ionas glimms,
among the globules of Protococcus nivalis
(Ed. Phil. Journ. v., xxix.). 1-1200" to
1 -300". This is probably only the ' stUl '
phase of CJdamydococcus pluvialis.

M. Vogt gives a very singidar account
of the mode of reproduction of this
being. He says, " It gives off from se-
veral parts of its body small transparent
buds, apparently vesicular, and for tli«

most part fiUed with granular matter.
As they enlarge they become gradually
detached ; sometimes two of equal size,
of which one is red and loricated, the
other colom-less, adhere by a very naiTow
point of attachment, which subsequently
gives wfiy, and the bud appeal's as an
Infusory animal, like what Mr. Shuttle-
worth has represented in his 7th and 8th
figures, and which approaches Pandorina
hyalina (Ehr.)."

This account of the reproduction of
this species of Gyges is so peculiar and
exceptional, that the questions arise
whether it reaUy is a member of this
genus and family, and, if it be, whether
the description is a correct interpretation
of the facts obsei'ved.

M. Vogt adds that Gyges sanguineus
ought not only to be looked upon as the
type of a new genus, but even of a now
family, on accoimt of its very peculiar
mode of reproduction. He lather de-
scribes a new species : —

G. Vogtii. — Globidar, containing in its
interior from two to five individuals,
enveloped by an apparently silicious
lorica ; colour dark rea ; frequently found
adherent and an-anged in tJie fonn of a
cross, also often separate. " The small
individuals, probably the young, were
of a clear yellow hue. I could not ob-
son-e the slightest motion in them."
—On the Animalcules of the Eed Snow,
Bihliofhhque Univ. de Geiibve, May 1841.

OP THE VOLVOCINA. '

Genus PANDORINA (XIX. 59-69) (Part I. p. 157).— Destitute of eye-
speck and tail, hut provided \vith a globular lorica and a slender filament.
Dui-ing self-division the creature acquires the appearance of a mulbeny.
Transparent vesicles occur in one species : two exhibit green, and a third
colomiess granules.

Dujardin esteems the presence of the red speck to be insufficient to distin-
guish Eudorina as a genus distinct from Pandorina ; and most recent observers
agree with him.

It has been shown by Braun (Rejuvenescence, Ray Soc. 1853, pp. 169-209),
as -well as by others, that Ehrenberg was in error in assigning a single fila-
ment only to Pandorina, and no eye-speck — since two flabella extend from
the more pointed extremity of the being, and close to their base is a brownish-
red speck.

Prof. Henfrey details (M. T. 1856, p. 49) the characteristics of Pandorina
much more fully, and corrects the errors into which Ehrenberg fell. He
assumes it to be a plant, and thus describes it : — " Pandorina. — Frond a mi-
croscopic, ellipsoidal, gelatiaous mass, containing, imbedded near the peri-
phery, sixteen or more biciliated, permanently active gonidia, arranged in
several cii-cles perpendicular to the long axis of the frond. The gonidia, al-
most globose, -with a short beak-Kke process, a red spot, and a pair of cilia
■which project through the substance of the frond to form locomotive organs
upon its surface. Reproduction : 1. By the conversion of each gonidium
into a new frond within the parent mass. 2. By the conversion of the go-
nidia into encysted resting spores, which are set free, and (?) subsequently
germinate to produce new fronds." The genus more closely resembles Ste-
phanosphcera than any other of the family.

Pandobina Morum (Volvox Morum,
M.) (xix. 59-69). — Body simple or mid-
tipartite, enclosed within a simple lorica.
Colour gi'een ; filament twice as long as
the body. In water with Lemnse and
Confervse. Size of individual 1-1150",
cluster 1-120". Some individuals broken
from the cluster by Ehrenberg have not
been above one-thu'd the former mea-
sm'ement.

P. Morum is much more satisfactorily
and correctly described by Mr. Henfrey,
thus: — "Fronds hyaline, from about
1-80" downwards. Gonidia either 16,
and then arranged into circles of 4; or 32,

and then in 5 circles — 2 at the poles, of
4, and the intenuediate 3 of 8 gonidia ;
which, in the perfect form, stand near
the periphery, and wide apart. In the
fonns which produce the resting-spores,
the gonidia are crowded together m the
centi'e. The gonidia are green ; but the
contents of the restiag-spores, after they
have become encysted, are converted
mto oily and gr-anular matter of a bright
red colour."

P. hyalina.— Form globular. In the
Nile with Confervse, and is a doubtful
species. 1-5760".

Genus GONIUM (XIX. 32-37; Part I. p. 152).— Deficient both of eye-
speck and tail ; lorica simple ; in the process of self-division, form rcndar four-
cornered tablets or plates. The lorica (a lacerna) of each individual (as' is seen
after its separation) is nearly roimd ; and the organism can cast it oft' and form
it anew. In one of the species ((?. Pectorale), two vibratoiy filaments are
placed at the mouth as organs of locomotion, &c. ; in the other species these
have not been observed. Vacuoles are seen within G. Pectorale ■ and a red
speck (produced probably by refracted light) at the base of the filaments hns
been conceived by Ehrenberg to indicate the mouth.

Cohn's elaborate account furnishes the foUowing additional notes on Go
nmm {Enlmcl:. p. 1 .9 ; and Part I. p. 152) :-The qua(bate tablets consist of
sixteen polygonal (mostly lioxagonal) cells, imited together by tubular prolon
gations Irom their angles, the whole being surrounded by a common gelatinous

518

SYSTEMATIC HISTOEY OF TITE INFrSOaiA.

investment (the envelope-cell). Each cell or gonidium has its own hyaline
membrane, is somewhat elongated into a neck-like form on one side, and con-
tains a homogeneous protoplasm, chlorophyll, and dark gxanules (except in tho
neck-like portion), and in. the centre a single chlorophyll vesicle ; besides these,
several vesicular spaces, and one, two, or rarely three contractile vesicles.
From the pointed end two filaments proceed, and pierce the common envelope,
to vibrate freely on the outside of the tablet. Reproduction by fission is not
a simultaneous act, as represented by Ehrenberg, but is effected by repeated
divisions thi'ough four generations or series, in each of which the ' daughter
cells' severally resolve themselves into two others, as happens in all the Vol-
vocina andPalmeUese. The result of this act of reproduction, when uninterfered
with and complete, is the formation of sixteen tablets similar to the parent,
but without any organic connexion, each young tablet, however, being enclosed
within the wall of the parent cell, out of which it has been produced, for this
cell-wall takes no part in the process of fission. Sometimes a tablet breaks
up, setting its component gonidia free, when, their angular processes becoming
absorbed, and their membrane further removed from the contents, they as-
sume the general aspect of a Chlamydococcus or Chlamydomonas, and probably
enter on a resting-stage like the gonidia of Stephanosphcera. Ehrenberg be-
lieved the isolated cells to be reproduced by fission like those united in the
tablets ; but Cohn never observed this take place. If this resting-stage actually
occui's, then Oonium is propagated by ' macrogonida' ; but of * microgonidia' no
evidence has been discovered. The tablets revolve on their shorter axis, and
hence, on a polar aspect, appear like a disk, on an equatorial like a line of
cells. A peculiar structural relation obtains between Qonium and Pedias-
trum. Lastly, Cohn asserts that Qonium Pectorale is the only true species of
this genus ; that the others enumerated by Ehrenberg are motionless, and
belong to the genus Merismopedia among the PalmeUacese.

GoNitTM Pectorale (M.) (see p. 152).
— Consists of sixteen spherical bodies
enclosed within a transparent lorica, and
disposed regularly in a quadrangular
form, and in the same plane, like the
jewels in the breast-plate of the Jewish
High Priest, whence the specific name.
The foiu' centi-al ones are generally larger
than those which smToimd them; and the
combined diameters of the three smaller
balls are about equal to the two larger
centre ones to which they ai'e attached ;
the external corners are consequently
vacant. As these animalcvdes swim and
revolve in tho water, they occasionally
present a side view to the obsei-ver, when
tho circumference of the larger central
globules may be seen projecting beyond
the others. Sometimes the clusters ap-
pear irregular. They are of n heautiml
transparent gi'cen colour ; and in swim-
ming, the globules often appear of on
ellipsoidal figm'e.

In order to observe the structiu-e of
tliis liighly curious and beautifid crea-
ture, considerable adroitness is necessary
in the management of the microscope ;
while a little indigo conveyed into tho
water with the point of a camcl's-hair

pencil win be required to see the whorls
and cmTents set in motion around it.

The single animalcules (xrs. 33) swim
like the Monads, in the direction of the
longitudinal axis of then* bodies ; but the
tablets have a variety of movements:
sometimes they move quite horizontally,
at others vertically, at others again on
their edge, revohing like a wheel. A
magnifying power of 200 diameters is
sufficient for general examination ; but
to exhibit all the structm'es shown in
the engravings, foiu times that power
will be required. In clear water, salt
and fresh, near the surface. Discovered
by Midler in clear water at Copenha-

fen, 1773. Size of animalcule from
-460" to 1-1150", of tablet not exceed-
ing 1-280".

G. pnndatum. — Coi-puscles green,
spotted ^vith black, and enclosed within
a crystalline lorica. Amongst Conferra3.
1-4000": a tablet of 16, 1-570" m breadth.

G. tranquiUum. — Corpuscles green,
within a crystalline lorica, each 1-2880";
a tablet of '16 coi-puscles, from 1-140" to
1-220" in breadth. Tablet sometimes
twice as broad as long.

G. Corpuscles transparent,

OF THE TOLVOCINA.

519

The niunber of animalcules in the tablets
varies from four to sixty-four. In sea-
water. Size 1-5000" ; tablet 1-500" iu
diameter.

within a crystalline envelope. In stag-
nant water. Corpuscles 1-3000" ; tablet
of 20 to 25, 1-600" in breadth.

G. r/laucimi. — Coi-puscles bluish-
green, within a crystalline envelope.

Gonium tranqu'dlum and G. glaucum, says Perty, are Algaj (?'. e.
say, are not members of this genus). He adds as a new species,

he would

G. helveticum. — The gi'een, spherical
corpuscles combined in a tabular, gela-
tinous envelope, without any intercom-
mimicating bands, each furnished with
a fine red stigma and two ciliary loco-
motive filaments. On a polar view, one
large round vesicle is visible ; on the
lateral aspect, two such ai'e apparent,
one larger than the other. On drying

the specimen, the stigma itself assumes
the form of a vesicle. It is readily dis-
tinguished fi'om G. qttadrangulatum by
the absence of the connecting bands or
tubules between the several corpuscles
in the tablet. Diameter of tablet 1-360",
of corpuscles 1-1300". Filaments 2\
times longer than the gouidia. In ponds
about Bern.

Genus SYNCRTPTA (XX. 26-28).— This genus is mainly charactemed
by secreting or hiding itself (as the name implies) within a second envelope.
Each individual is provided with a special lorica of the form of a little shield
(scutellum), and is united with others in a common gelatinous envelope (la-
cerna) into which it can retreat ; neither eye-speck nor tail is present, but
there is a large filament ; self-division longitudinal. The filaments of the
several corpuscles give the cluster an appearance of being surrounded with
hairs.

With this genus Dujardin would identify his Cryptomonas (Tetrahcena).
The very doubtful position and independence of this genus as a member of
the Volvocina have been remarked on in the general notes on this family
(p. 144). Mr, Carter, in a paper lately published (A. JSf. H., 1859, iii. p. 1 et
seq.), represents Syncrypta to be the " spermatic form " of Volvox or of Sphai-
rosira (Ehr.), (See notes on SpHiEEOsmA.)

Synchypta volvox (xx. 26-28). —
Fonn oval ; colour green, with whitish
rays in the centre. Generally in water
di'ained from Confei-vse. 1-2880"; a clus-
tered globule in its crystalline tvmic,
hardly exceeding 1-570". Fresenius
states that he has seen a red stigma in
each coi-puscle, which was overlooked by
Ehrenbei-":.

This ben'y-like cluster of animalcules,
when rolling through the water, is a
beautiful object for the microscope ; and
vsdth the aid of a little indigo, the nu-
merous cmTents it creates are readily
perceived : xx. 27. magnified 260 dia-
meters ; fig. 26. 400 ; ancl fig. 28 a cluster
about to sever into four.

_ Genus SYNURA (XX. 29, 30).— Eye-speck absent ; tail filiform, attached
cither to the base of its own lorica or to the centre of the cluster to which it
belongs. The general envelope is spherictd, gelatinous, and is hollowed out
by as many compartments or cells as there are individuals in the little com-
munity. From out of these cells they can stretch themselves a considerable
distance, whilst they continue attached by the extremely delicate and exten-
sible taU. This so-called tail or pedicle is homologous with the connecting
rays or threads of the several corpuscles m the globe of Voluox, and is, like
them, a production of the protoplasm of the interior. As before remarked
this genus is doubtfuUy retained ; for the chief distinctive featui-e Ehrcnbere
insists on, viz. the presence of a double lorica, loses its significance now that
modern researches have shown that the formation of a second or common en-
velope is an ordinary phenomenon at a certain stage of existence of most or
of aU Volvocma. Moreover, the description given of this genus is too loose
and faulty, and its accompanying dlustrations too rude, to render it possible

520

SYSTEMATIC HISTOIIY OF THE INFUSOllIA.

to rightly appreciate its characters and to assign it its proper place, even if
it is admitted to be an independent organism. Mr. Carter has lately pul)-
lished (A. N. H. 1859, iii. p. 10) the opinion that Synura is the " spermatic
form " of Volvox or of Sphcerosira. (See notes on Sph^eosiua),

SYNtiTtA uvella. — Corpuscles oblong,
yeUow, capable of extending themselves
to three times their usual length, by
means of the extensile tail. The cluster
has the fonn of a mulbeny, and its mo-

tion is rolling like that of Volvox Gloha-
tor. XX. 29, XX. 30, show a portion of

a cluster, and the manner in which the
tails are inserted in the common enve-
lope. This species, along with Hxjmrijpla
aud Uroglena Volvox, may have often
been confounded with Uvella virescem.
Length, exclusive of tail, 1-700" ; dia-
meter of cluster from 1-190" to 1-280".

Genus UROGLElSrA (XX. 31).— The members of this genus, unlike other
Volvocina, possess both an eye-speck and tail ; they live in clusters under a
common envelope (lacerna), which is subdivided into cells for the accommo-
dation of the several individuals. Self-division takes place simply and equally
in these individuals, whilst in their clustering condition. They are placed at
uniform distances from each other, attached by their tails, which radiate from
the centre. Each monad is furnished with a filament, which projects ex-
ternally and gives to the entire group the appearance of being covered with
hairs. "When the creatures divide, the mantle or lacerna enlarges only, and
does not itself undergo fission. The red speck is in the fore part of the body ;
the tail is fihform, resembling that of Vorticella and Bodo.

The tail mentioned in the above description is the same as that of Synura :
the use of the term is very inappropriate in both cases. It maybe that
Uroglena should be ixnited with Synura as Dujardin proposed, since the
presence of an eye-speck in the former and its absence in the latter is not
distinctive; still we know too little of the being which Ehrenberg would
call a Uroglena, to come to a decision respecting its affinities and generic
independence.

This genus is another which Mj.\ Carter would set aside, as he considers it
(^A. N. H. 1859, iii. p. 10) the same with Sphcerosira, or the " spermatic
form " of Volvox. (See notes on Sphjeeosiba.)

Uroglena Volvox (xx. 31). — Cor

famUy. Ehrenberg states that he has
obsei-ved individuals with tvs^o or three
coloured specks, which he conceives to
have been a symptom of approaching
self-division. In tm-f water. Diam. ot
cluster 1-90".

puscles yellow, oblong ; tail extensible,
from thi'ee to six times the length of the
body, and even more ; cluster mulbeii-y-
shaped. There is little doubt that single
coi-puscles of this genfis have often
been taken for creatm-es of a different

Genus EUDORINA. — Has no tail, but possesses a distinct cye-spcck, and
a simple vibratory filament anteriorly. Self-division proceeds simply and
equally, whilst the corpuscles retain their clustered condition. They are
poriochcally able to cast off their globular envelope (lacerna), and to exude a
now one, Kite certain Annelida. To observe the eye-speck, a power of 300
diameters must be skilfully employed.

Dujardin's proposition to combine Eiulorina with Pamlori'na has been
already mentioned (p. 515), and appears to be a correct one. The assigned
characteristic difference between those two genera is worthless; for Pamlorina,
like Eiulorina, has a coloured speck (see p. 157 ct seq.).

EuDoniNA elcf/ans. — Corpuscles green, generally from 30 to 50 individiials, and
globular,Dever protruding from their cells never less than 15. Motion revolving,
beyond the common envelope. Stigiua Fig. 47 exhibits the filaments cxtPTidea,
sparkling red. The elnstors, which are and the bodies of the animalcules within
of an oval or globular form, contain ' the Incenin (i.r. the "common onve-

OF THE VOLVOCrNA.

521

lope"). Clusters of these beautiful aui-
lUiilcules are often seen in sucli amazing
numbei-s, along with the Volvox Globator
and Clilainydonionas Pulcisculus, as to
render the water (othermse colourless)
of a decided green colour, especially
towards its edges. They ai'e exceed-
ingly delicate — so much so that it is
difficult to preserve them alive for more
than a day or two : whenever it is at-

tempted to retain them in large quanti-
ties, the second day -will generally ex-
hibit a thick mass of dead ones at the
bottom of the vessel. When a few
only remain alive, if the stale water
be poured away, and they are removed
into a vessel of clear water, they will
live for weeks. At Hackney and Tlamp-
stead; most abimdant in the spring of
I the year. Diam. of cluster 1-180".

Gemis CHLAMTDOMONAS (XVIII. 40, 51-54; XIX. 16) (Part J.
p. 146). — Tail absent, eye-speck distinct red, filament double ; multiplication
takes place by self- division within the common envelope, which is ruptui'ed
to give the products liberty. The lorica indistinct in young beings.

Braun {On Rejuvenescence, Bay Soc. 1853, p. 158) appears to elevate this
genus, in union with Ghlamydococcus and Gloeococcus, to the rank of a family
parallel with the Volvocina, under the name of Chlamydomonada. Indeed,
although, as Cohn has well shown, these genera agree in aU essential particu-
lars and relations with the Volvocina, yet the existence of each gonidium
as an independent being contrasts so strongly with the aggregate condition
of the rest of the Volvocina, that there seems snfficient ground to group them
as a sub-family. In order, therefore, to retain the Chlamydomonada toge-
ther, we shall depart from our usual custom, by inserting the new genera
Ghlamydococcus and Gloeococcus after Chlamydomonas. Chlamydomonas was
erroneously transferred, as before noticed, by Dujardin to the Thecamonadina,
and renamed Diselmis. Its characters are thus discussed by Braun (op. cit.
pp. 214, 215) : — " OJilamydomonas is distinguished from the genus Chlamydo-
coccus by the closely applied membrane of the old swarming- cells, also by the
absence of the little starch-vesicles in the interior, while, however, as is
usual in most of the PalmeUacese, a single large chlorophyll utricle exists in
the interior. There is no central red nucleus, as in the gonidia of Ghlamy-
dococcus ; but some species have a parietal red spot. Motion is effected
by two cilia, as in Ghlamydococcus. As in that genus, there is a growth of
the gonidia during swarming, which lasts over the day and night. There is
also a formation of microgonidia," and a resting-stage in which the coloiu-
changes from green to yellowish red, or to red.

Chlamydomonas Pulviscuhis (Manas
Pidvisculus, M.)(xix. 16). — Coloiu- gi-een ;
lorica oval ; eye-speck brilliant red ; fila-
ment double. (See Diselmis viridis,
p. 512.) Cohn identifies it yv'ith. Polytoma
Uvella.

These creatures forni a lai'ge portion
of the green matter which colours the
water contained in water-butts, ponds
and puddloa in the sunmier and autumn,
and especially after a storm. They will
rarely fail to be observed when any of

this green water is examined under the
microscope. Whenever these creatures
exist in large quantities, niidtitudes of
them and of their envelopes rise to the
smface of the water, and form a green
stratum upon it. Although this film
somewhat resembles one of UlvacojB, yet
it is easily distinguishable by its com-
position of living coi-puscles witli red
specks, connected together by a loose
mucous tissue, formed of dead speci-
mens and empty loiica3. 1-550".

Kutzing affirmed that this species was merely a phase of St,/geocUnium into
the filaments of which it became transfonned by an act of gemination 'rtZ
opinion has not been accepted, as it is supposed that Kiitzing confounded the
spores of that Alga with the gonuha of Chlamydomonas Puhlsculvs

Among the additional species of Chlamydomonas, those forms described bv
Dujardui as members of Diselmis (^. 5^2) should probably tXTheii pla^

522

SYSTEMATIC HXSTOUY OV THE INFUSOKIA.

here. Braun describes the foUoAving new species, premising the remark that
" the species are doubtless very numerous, but the distinction of them from
one another, as well as from the swanning cells of many other Algaj, is
very difficult without a complete acquaintance with the history of theii-
existence."

C. obtusa(Bmmx). — Colour dark gi'een;
ti'uncate at both ends, and oblong, chang-
ing to spherical and a yellowish brown,
and at length a red colour on assuming
the resting-stage. "The macrogonidia
grow dming swarming, from l-60th to
'almost l-30th of a millimetre long ; they
are longish, of equal diameter on both
sides, and very obtuse, almost truncated,
having a colourless space at the ciliated
extremity, presenting the form of a notch.
The contents are dark green, finely
gTanular, with a large vesicle at the pos-
terior extremity, a roimdish lighter
space in front of this, and no red point.
They midtiply by simple or double
halving in several successive genera-
tions. Sometimes a fm-ther continua-
tion of the division of the fiill-grown
macrogonidia occurs, fonning 16 or 32
macrogonidia from l-200th to l-120th
millimetre long, of ovate shape and
lighter colom*, tending towards brownish-
yellow. The resting (seed-) cells are
globidar, about l-40th millimeti'e in dia-
meter, at first gi'een, subsequently light
yellowish-brown, finally flesh-red ; tney
have a tough, colom'less, and transpa-
rent membrane. In the Rhine valley,
near Freibui'g, in pools in sand-pits,
which are occasionally almost completely
diied up in summer."

C. tingens (Braim). — Gonidia smaller
than in the preceding species, 1-120 to
1-60 millim. long, ovate, lighter green,
likewise destitute of a red spot; the
membrane is more distinct in old age.
Increase by double, rarely by single
halving ; in the foimer case, by decussat-
ing sections. Contents granulai', punctate
in appearance, green, Avith one large
vesicle. In the resting-stage they ac-
quire a pale reddish colour ; the vesicle
becomes indistinct, and the contents
coarsely granular in aspect fi-om the
formation of oil. Microgonidia also are
fonned. "The resting- but still green
condition seemed to me to con-espond
to Protococais Fclisit (K.), that which
turned red through desiccation, to Pr.
Orsinii." In pools near Freiburg. Cohn
(Eukcick. pp. 202, 203) detected two
vesicles in Chlamydomonas, below the

point of insertion of the filaments, very
slowly but rhythmically contractile, ani
mentions a species under the name of
Chlamydomonas hyalina, which he makes
synonymous with Polytoma Uvella (E.),
and states to differ fi-om Ch. Pulvisculus
only by the want of chlorophyll and of
a red speck (op. cit. pp. 140 & l69). He
moreover notes a new fonn, probably
genetically distinct by having not a
globular but a winged prismatic figure,
quadi-angular on a ti-ansverse section,
with the two veings like two outstretched
points, although in other respects agree-
ing with Chlamydomonas Pulvisndus.
Perty (p. 85) objects to making CJda-
mydomonas a genus of Volvocina, and
refers it instead to the so-called "Spo-
rozoidia." He fm-ther teUs us that Cld.
Pulvisculiis (E.) is rare about Bern, but
there is a smaller fonn very common,
which he proposes to call

C. communis (Peiiy), — He finds also,
but less frequently, a more globular
variety, which appears to be the Ti a-
chelomonas emarginata (Eichwald), but
is in^ fact a Chlamydomonas, which he
names

C. glohulosa (Perty). — His species
Hysginum pluviale ^and 3. tiivale (i. e.
Chlamydococciis) he suggests uniting,
vnth the species of Cldamydomonas, into
a gToup (ot Sporozoidia) under the name
of Schizoncma.

C. midtifiUs (Fresenius). — Round or
oval ; a distinct nucleus m the centre ;
granular contents green ; filaments four,
longer than the cell ; at their base a rose-
coloured contractile vesicle, and poste-
riorly to this a red stigma. Loi-ica thin,
closely investing contents. As many as
six filaments seen in some larger speci-
mens. 1-92"' to 1-63"'. In fresh water.

C. hyalina (Cohn, Fi'esenius). — Elon-
gated elliptical ; roimded at both ends ;
filaments two, longer than the body;
posterior half of ca\aty occupied by gra-
mdes ; a clear non-couti"actde space in
the centre ; a small conti-actile sac at the
base of the filaments. 1-66"' to 1-46"'.
In ponds coknu'ed by Etiglen^.

It is doubtfully separable from Clil.
Pulvisculus.

Genus CHLAMYDOCOCCUS (Part I. p. 148) (XIX. 20-31).— Gonidia

OF TITE VOLVOCINA.

523

spherical; colour green or red, enclosed by a hyaline structureless mem-
brane, removed some distance from the colom-ed contents by a clear interspace
or areola. The central protoplasm, coloui'ed by chlorophyll or a red oil, and
having one or more chlorophyll utricles at the centre, has its spherical figm-c
destroyed by an elongation at one part into a tapering process, from which
two filaments proceed, and, after perforating the external " envelope cell,"
protrude as motile vibratile organs. The inner, coloured globule has no
special membrane, and in consequence undergoes multiform transformations
of its outline in the course of development. In the resting-stage the enclosed
coloiu-ed mass, the " primordial cell," secretes over its surface, inside its enve-
lope cell, a new, tough, cellulose membrane, whilst the envelope cell is dissolved
into a mucous layer. In such still cells macrogonidia are produced by fission of
the contents, ia the power of two,and after a time burst through the parent cell,
develope their two ciliary ^fidaments, and proceed to develope a cellulose mem-
brane over their entire surface, which becomes further and further removed
until they acquire the characters of the ordinary moving cells. When divi-
sion is more fii-eqiiently repeated, microgonidia are formed, which move much
more actively, and do not secrete an envelope cell ; they are incapable of
propagation, and pass immediately into the condition of rest. The motionless
cells of Ghlamyclococcus are of much simj)ler structure than the motile, and
consist simply of a tough, spherical, cellulose membrane, and green or red
contents, organized as a primordial utricle. Yactioles are foirnd among the
contents of Chlamydococcus-ceUs ; but a contractile vesicle has escaped obsei'v-
ation. Ghlamyclococcus and the two allied genera, Qloeococais and Chlamydo-
monas, differ ftom the true Volvocineae in this respect : viz. they separate from
each other after complete fission, as primordial utricles, and then severally pro-
ceed to form an independent envelope ceU ; whilst the rest of the Volvociuea3
contiaue, on their production by fission, to live in groups and produce aroimd
their aggregated mass an envelope cell in common. It bears the same rela-
tion, therefore, to the rest of the VolvociuoEE that Pleurococcus does to Pahnella,
Cyclotella to Meloseira, or Vorticella to Epistylis. Ghlamyclococcus is distin-
guished from the moving germs (sporozoids) by which the greater number of
Algse propagate, both by a somewhat more complex structiu'e, and by the
circumstance that the motion lasts for a very long time, and, finally, by the
power of the moving cells to propagate as such, without entering into the
state of rest otherwise than as quite a temporary condition. Perty, who has
studied this genus very minutely, employs the term Eysginum to designate
it, although it had previously received other names from other observers
besides that we have employed. Indeed, owing to the various appellations
given, and especially the specific names invented for the multiform varieties
of the same organism, the synonyms became very perplexing and a positive
impediment to the progress of our knowledge of this genus. Among the
multitude of proposed species, two only are now accepted, viz. Ghlamyclococcus
pluvialis a.nd Ghl. nivalis ; but their distinctive characters are nowhere
detailed in a definite and available form for our purpose. The red snow of
Alpine regions is the red variety of both these species. The other varieties of
Ghlamyclococcus have been more widely described under the title of Proto-
coccus, and those of a red colour under that of ffa^matococcus. Cohn cites
two prmcipal synonyms for Ghl pluvialis, viz. Ha;matococcus phwialis and
Ghlamydococcus vcrsatilis, and in his Monograph on this organism employs
the term Protococcus pluvialis, although in a subsequent contribution L
adopts Braun s designation as employed by us. The many modifications of
ft)rm of this one species imdcr different circumstances of development and
habitat have received as many different names, from tlic notion of thdr

524

SYSTEMATIC HISTOEY OF TIIE rNFUSOHIA.

being specifically distinct. These Cohn has pointed out in his essay ; but only
that portion of them is worth citing which has attracted notice 'in various
works. " Thus the still Protococcns-cc]l corresponds to the P. Coccoma (Kiitz.) :
when the border becomes gelatinous, it resembles P. pulcher, and the small
cells P. minor. The encysted motile zoospore, on the other hand, is the Gyges
Oranulum, and resembles also P. turcjidus (K.) and perhaps P. versatilis
(Braun). The zoospores divided into two must be regarded as a form of
Oyges hipartitus, or of P. dimidiatm." A red variety of the cell was de-
scribed by Girod Chantrans as a Volvox, under the name of Volvox lacusiris ;
but Perty refers it to Hcematococcus.

CwLAT^TTDOGOccns pluvialis. — Sufficiently characterized in the above history.
Chl. nivalis. — Unsatisfactorily distinguished.

Genus GLCEOCOCCUS. — This is a new genus suggested by Braun (On
Rejuvenescence, p. 159), who thus describes it : — " Ovate, gi-een ceUs, with a
colourless point, from which a fimnel-shaped, lighter space extends inwards ;
a rather large vesicle also is formed at the posterior extremity. Multiplica-
tion by simple or double, in the latter case decussating fission, after which
the cells remain loosely connected together by the secretion of soft, gela-
tinous, confliient coats, forming globular and finally amorphous families
(clusters). The cells of all the generations succeeding each other during the
formation of these families (excepting the transitory cells in the case of
double halving) are provided with two veiy long persistent cilia, which dis-
appear only when division commences. The cells exhibit a feeble motion
inside the enveloping and connecting jelly, the anterior end jerking in and
out, or suddenly retracting a little. The last generation of the family leave
the gelatinous mass, and swarm out, to settle down quickly in some other
place. It is probable that the formation of a new family is preceded by a
rather long state of rest — ^perhaps there are several resting generations ; but
we have no observation on this point." A red speck is not perceptible. Two
species are named : —

G. minor. — Perhaps specifically di-
stinct. Appears in the spiings at Frei-
bm-g early m the year, in the fonn of
light-yellowisli-gi-een, often pear-shaped
stocks " (masses), almost as large as a
hazel nut, attached to the sides of the
mitters of the spiings, finally becoming
detaclied, swimming, and shapeless. The
cells are somewhat small, 1-100 to 1-75
miUim. long.

Glceococcus mucosus. — The fidl-
gi'own cells are 1-60 to 1-50 millim.
long : the clusters, fonning at the bottom
of little ponds, attain the size of an
apple, and are of compressed glohidar,
often lohed-shaped foim ; but at length
they break up, and come to the sm-face of
the water in in-egular fragments. The
gelatinous mass has a peculiar greenish
spotted aspect, which depends vipon sub-
ordinate groups of generations being
more closely packed together.

Genus SPHJEROSIRA.— Tail-Hlce process absent; eye-speck and fila-
ment single. Self-division, unlike that in the preceding genera, occurs im-
cqually within the envelope, and fonns young clustei-s at once from the parent
ones. This genus differs from Pandorina in having the eye-speck, from
Eudorina by its unequal mode of self-division, and from Volvo.v by its
simple filament. Self-division in tliese creatiu-es takes place in the longi-
tudinal direction, in parallel planes ; so that laminae are produced, as in the
case of Gonium. i i

Splmrosira, n.s heretofore remarked, is regarded by Prof. Busk as a doubttiU
independent organism ; ho is, however, unable to speak po.sitivcly on this
point, and therefore, whUst still keeping it distinct from Volvo.v Globalor, ot

or THE VOLVOCrNA.

525

which he had some reason to suppose it a peculiar mode of development,
ranks it as only a species of Volvox, instead of elevating it to the rank of a
genus, and calls it Volvocc Splmrosira. Dujardin also denied the distinction
drawn by Ehrenberg between S;pha'r-osira and Volvox, but did so from mis-
taken views ; for he represented Volvox to have only a single filament, whereas
both this and Sphcerosira have two. " It presents the appearance," says
Mr. Busk {M. T. 1852, p. 33), " of a transparent globe, set with gTeen spots,
but it differs from the ordiaary varieties of Volvox Olobator in two important
respects : 1, in the absence of any internal globules or embryos ; 2, in the
irregular size of the green granules liaing the wall which, instead of being of
imiform size, are of various dimensions. The different-sized granules are
iiTeg-ularly disposed, although, in relation to the sphere itself, they, or rather
the centres of them, are as regularly distributed as in the three just-described
forms (of Volvox). What is rather remarkable with respect to this form is
the circumstance that the lai'ger granules are not disposed over the whole
periphery of the sphere, rarely occupying more than two-thirds of it towards
one side." Again, he adds — " The smaller ones appear to resemble in all
respects those of Volvox Glohator, and each to possess two cilia, which is im-
portant, if true, because the only distinction between Volvox and Sphcerosira
in Ehrenberg's classification depends upon the circumstance that in Sphce-
rosira there is only one cilium to each zoospore, whilst there are two in
Volvox.

" My supposition that S. Volvox and V. Glohator are allied is founded, it
must be owned, not upon any direct observation, but chiefly on the fact that
in the water in which the specimens of Volvox were contained there were at
fii'st none of SpJicerosira, any more than of V. aureus, and that after some
days both were very numerous. The difference I am about to describe in the
after-development of the ciliated zoospores is not by any means a sufficient
gi'ound upon which they should be deemed distinct species, because much
greater differences are known to exist in other of the lower Algse during their
various forms of development, without it being thence allowable to suppose that
they are of different species. In Volvox Sphcerosira, then, as at all events it
may be termed, the larger green granules are in fact the ciliated zoospores in
a state of further progressive development. In the same specimen they will
be seen in all states of division or segmentation, — first into two, then into foiu-
and so on, tOl, as in the case of the embryo Volvox, the ultimate result of the
segmentation constitutes numerous minute ciliated cells or bodies, not how-
ever, iis in that case, lining the inner surface of the wall of a spherical case
but forming by their aggregation a discoid body in which the scpai-ate fusi-
form cells are connected together at one end, and at the other are free and
furnished each with a single cilium. In this stage theii' compound masses
become free and s\\im. about in the water, constituting, in fact, a species of
the genus Uvella, or of Synar^jpta of Ehrenberg." '

Mr. Carter affirms {A.'n.H. 1859, iii. p. 4) that Sphcerosira is not a distinct
genus, but the " spermatic form " of Volvox Olobator, which he describes as
one phase of development of this species, wherein upwards of a hundred of
the gonidia, scattered over the periphery of the primary gemma) of the pai-eut
globe, divide repeatedly until they are broken up " into 128 (?) linear ciliated
segments, which are ultimately arranged verticaUy upon the same plane in i
circular tabular group, with their ciHa upwards; and when the latter are
sufficiently developed, the group oscillates and rotates by their aid both unon
Its long and short axis These segments are, in fact, the spermatozo d.s
each of which, when thoy separate, is observed to be linear, hom- shaped'
and colourless antenoriy (where it is attenuated), and green sh posteriorly

526

SYSTEMATIC HISTORY OF THE INFUSORIA,

provided with a paii- of cUia whicli are attached to the anterior extreniit}-,
and some distance behind them with an eye-spot ; their progression is
vermicular from their extreme plasticity, and they keep up an incessant
flagellating movement with their cilia. As yet, I have never seen any of
these free in the daughter bearing the spermatic ceUs when the former has
been outside the parent ; nor have I ever seen them free under any cir-
cumstances, except once, in the old Volvox, when the daughter containing
the spei-matic cells from which they had been developed had been partly
eaten up by Rotatoria,

" This is the form of Volvox Olobator which has been called SpJmrosira
Volvox by Ehi-enberg ; and, Hke the daughters bearing the spore-ceUs, it
becomes liberated from the parent before the spematic cells attain their
ultimate development, that is, before the groups of spei-matozoids become
sepai-ated, not before they are formed. It is worthy of remark, too, that the
daughter bearing spermatic cells is never more than half the size of the spore-
bearing daughter, at least as far as my observations extend.

" Thus we have the spore-ceUs and the spermatic cells in different daughters ;
and as I have never seen them together in the same daughter, nor the
daughters respectively bearing them in the same parent Volvox, out of some
scores of instances, I can come to no other conclusion than that the two
daughters meet after they have left their respective parents, when, both the
spores and the spermatozoids having become ripe for fecundation, individuals
forming the groups of the latter separate, burst from their capsules into the
cavity of the daughter, and from thence find theii- way out into the water,
and then into the cavity of the daughter bearing the spore-ceUs, where they
become incorporated with the latter.

" Hence Volvox Glohator would appear to be dioecious, and not monoecious
as stated by Cohn ; and Splmrosira Volvox not, strictly speaking, another
form of Volvox Glohator, but the spermatic form. Cohn, considering Volvox
Olobator and Volvox stcllatus the same species, has taken his fecundating
character from the spermatic form of the latter."

The spermatic groups above described, Carter subsequently remarks, con-
stitute in all probability Ehrenberg's genera Syncrypta, Synura, and Uro-
glena.

SpHiEBOsmA Volvox. — Coi-puscles compressed clusters within it. Found in
pale gi-een, of nearly a globular shape, considerable numbei-s in company with
enveloped in a common mantle. Eye Volvox Glohator, and often attains its
bright red. The cluster resembles a size. Sometimes found by itself,
great ball of coi-puscles, containing small

Genus VOLYOX (XX. 32-47) (Part I. p. 180).— The genus Volvox, which
is the type of the famUy Volvocina, was instituted by Limueus, and promul-
gated to the world in 1758, in the tenth edition of liis ' Systema Natm-a;.' As
first described by him, the two species F. Glohator and V. (Jliaos comprehended
all known Infusoria, excepting eleven of the tribe Vorticdla, whicli were
separated from them, under the denomination of Hydra. In his twelfth edi-
tion (1766) of the same work, he distributed the Infusoria into four genera,
viz, Vorticella, Volvox, Hydra, and Chaos.

Volvox is characterized' by the aggregation of its ceUs or gonidia over the
internal surface of a transparent lorica or common envelope ceU, of the form
of a hoUow globe. Each coi-puscle or gonidium jiossesses a red speck and two
filaments, which protnide beyond the suiface of the lorica so as to give the
whole globe the appearance of being covered Avith cilia. The mode of
increasing by a sort of internal gemmation is chai-actei-istic of the genus.

OF THE VOIVOCINA.

627

Dujardin was unable to detect more than one filament ; but Ehrenberg's
description of two is now amply corroborated.

The stnictm-e of Volvox has received the careful study of many eminent
microscopists, who have been compelled to differ largely from Ehrenberg in
their accounts of it. The resume given in the general history of Phytozoa
renders it perfectly unnecessary to repeat in this place the particulars of the
organization of the members of this genus or to enter into the discussion
respecting their trae nature as organic beings.

Volvox Globator (M.) (xx. 32-47) rent difference between them consisting

(p. 180 seq.). — So called from the in the deeper green colour of the internal

globular figure of the aggi'egate mass or globes. These, however, soon exhibit a

colony constituted by the individual more important distinctive character, in

monadiform beings or gonidia. "When
blue or red coloiu'ing matter is mixed
with the water, strong cun-ents may be
observed imder the microscope aroimd
each globe, which, when in motion,
always proceeds with the same part
foremost, xx. 32 represents a lai'ge
globe with eight smaller ones (tei-med
by Ehrenberg, sisters) within it. xx. 34
is a section of a globe, more magnified.
XX. 35 represents three gonidia in situ
within the common envelope. In
shallow pools of clear water, in spring
and summer. The largest globes mea-
sure 1-30" in diameter ; the smallest
free swimming ones 1-360" to 1-240".
Size of a single coi"puscle 1-3500".

Ehrenberg notified the peculiar occur-
rence of hving Rotatona within the
globes of the Volcox Globator. Mr. John
Williams has communicated (T. M. S.
1851, iii.) an interesting observation,
confirming Ehrenberg's account.

Within the cavity of a large specimen
of this species, evidencing its usual
vitality, and the ciliary movements on
its surface, he noticed a veiy active
Rotifer, which he believes to have been
the Notormnata parasitica, and which
was subsequently accompanied by
another of the same species, but smaller,
lie adds, " By the most carefid examina-
tion, no opening could be perceived by
which they could have been introduced ;
neither did there appear to have been
any viscera by which their motions
might be impeded, as they swam about
a-s freely a.3 fish in a glass globe, to
whicli, indeed, they bore no faint resem-
blance."

The two following species, named V.
aureus and V. stdlatus, are, in the opinion
of Profs. Busk, Williamson, and I'ertj-,
merely developmental phases of V. Glo-
bator— V. steltatus being the later stno'e.
" V. aureus" says the writer first nanrcd
(op. cit. p. 32),"exhibits precisely the same
structure as V. Globator, the only appa-

the formation of a distinct cell-weU of
considerable thickness around the dark-
gi'een globidar mass. This wall becomes
more and more distinct ; and after a time
the contents change from dark gi'een into
a deep orange-yellow, and simultaneously
with this change of colom- the wall of the
globide acquires increased thickness, and
appears double.

" The third foi-m, or V. stellatus, differs
in no respect from the two former, except
in the form of the internal globules,
which exhibit a stellate aspect, caused
by the projection on their surface of
numerous conical eminences formed of
the hj^aline substance of the outer wall.
The deep colom- of the contents of their
embryos, and their change into an orange
colour, at once point out their close
analogy with those of V. aureus. I have
no doubt of their being mere modifica-
tions of the latter, and I have obsen-ed
smooth and stellate globides in the in-
terior of one and the same parent globe."

]Mr. Carter, however, does not share
this opinion with reference to V. stellatus,
which he treats (A. N. H. 1859, iii. p. 6)
aa a distinct species.

These extracts from recent and well-
known aiitliorities are further valuable
as suppljring an explanation of Laurent's
statements that two sorts of reproduc-
tive bodies appear in the globes of Vol-
vox. Little weight is attached to this
gentleman's microscopical researches,
winch are mostly ideal.

V. aureus. —'Grcan, nearly globular,
liie small secondary globes within them
are of a golden colour, and smooth sm--
faco. In rain-water standing on tmf
Diam. of globe 1-30".
_ V. stelhtus.—^mv^, subglobose, some-
times oblong, or of an angular form, and
green colour. The contained globes
within them arc of a green colour, and
have their surfaces tuberculated or stel-
lated. Dinm. of globe 1-30".

Carter, who accepts this species, de-

528

SYSTEMATIC UISTOEY OF THE INFUSOlilA.

scribes it in the following words, using
the quaint terms " daughters " and
" gi-and-daughters " for the "primary"
and " secondary " generations or gemmjB
of the parent globe of the Volvox : —
" AduU form. — Globular, slightly ovoid,
consisting of three generations or families
within one another ; containing generally
eight daugliters, in each of which there
are generally eight grand-daughters in-
distirtcfly visible. Daughters confined to
the posterior tliree-fourths of the sphe-
roid, the anterior fom-th being empty.
ProgTessing with the empty end for-
wai'ds. Daughters rotating (this marks
the adult form here also) in their cap-
sules respectively, which are fixed to the
internal periphery of the parent. Grand-
daughters small and indistinct, motion-
less, and fixed to tbe internal periphery
of the daughters respectively. Peripheral
cells conical andbiciliated,not uuiciliated
as figm-ed by Ehrenberg. 59-1880" long
and 54-1880" broad."

In his subsequent remarks, he makes
it the specific point of difference between

the primary gemmoe of this V. slellatiis
and V. Glohator, that those of tbe former
begin to undergo duplicative subdivision
almost immediately after they appear, or
" at the time when they do not exceed
three times the diameter of the peri-
pheral cells," or 1-2700", instead of "not
passing (as in V. Glohator) into small
cells until they have arrived at more
than the 1-300" in diameter." He also
alludes to differences betn^een these two
species in the foi-m of the spennatozoids
and the mode of fecundation. We ven-
ture to remark that if these latter par-
ticulars are suflticient to indicate specific
differences, it is not so with the size of
vegetable cells at which fission may
commence. The history of all the sim-
plest cellular organisms we know of
shows that the period of cell-life, and
therefore the dimensions of the ceUs at
which it occm's, stands in no constant
relation with the act of fission. The
size of a cell and the proclivity to fission
depend much on external conditions
affecting its ■vital acti-^dty.

The following genera are distinguished by Perty : —

Genus SYNAPHIA (Perty). — Corpuscles fromlO tol2, aggregated together
within a spherical gelatinous envelope, in mutual contact, so as to form a
compact mass. The coi-puscles, each furnished with a single filament, are
not spherical but angular and wedge- or pear-shaped, with the -wide end
turned towards the pheripheiy. In very exceptional specimens the gonidia
are somewhat separated from each other. Length of filament equal to, or
li the diameter of the corpuscle, and very fine. The relation between
Gonium and PecUastrwm has been noted by Cohn and other obseiwers ; but
that between this newly-constituted genus of Perty and the second-named
group is much more striking, whether the description given or the illustrative
figures be considered; indeed the impression forces itself upon \is, that
SynapJiia is simply a form of Pediastrum. This impression is moreover
strengthened by the fact mentioned by Perty, that the movement of the
organism, and the fijie filament, disappeai' as the organism advances in age
and dimensions.

Synaphia Diijardinii (Perty). — Cor-
puscles clear ^een to dark or blackish
gi-een, measuring within the enclosing
envelope 1-1300" to 1-360", more com-
monly from 1-720" to 1-480". Move-
ments torpid or tolerably quick, around
one or other axis, always oscillating.
The filaments are only visible when the
spherical colony is at rest. The radi-
ating grouping of the individual gonidia
is not completely sjinmetrical ; some-
times the spherical figure is exchanged

for an ellipsoid. The gelatinous envelope
varies in breadth, is clear and trans-
lucent, rarely having a red blush undei
the microscope, and, in large specimens,
frequently divided bv fine lines into
two or three bales, ^'hen dying, the
several corpuscles detach themselves, and
after death do not undergo diffluence,
but turn yellow and ultimately dissolve
away. Frequently a green granule is
visitlo internally, and a scarcely-dis-
cernible red point.

Genus HTllMIDIUM (XIX. 15) (Perty).— A chain of from 4 to 8, very
small rounded corpuscles of a pale green colour, surrounded by a gelatinous

Ol!' THE VIBBIONIA.

529

envelope. This genus appears to us very erroneously referred to the Volvociua ;
but the figures given are not sufficient to determine to what family they more
rightly belong.

HrRMiDiuM inane (xix. 15). — Cor-
puscles irregiilai-ly spherical, almost cup-
shaped, and probably fiu-nished each with
two filaments. Some very fine molecules,
one generally of a hai'k hue, perceptible
internally. The chain advances quickly
by revolving on its long axis ; gelatinous ;

common envelope inconspicuous. Length
of chain 1-360" ; size of individual cor-
puscles 1-1900". From its smallness, this
organism is difficult of observation, and
requires further investigation. Only in
small numbers, in some ponds in the
canton of Bern.

Wemeck characterized several new genera, which he referred to the Poly-
gastrica of Ehrenherg (Monatsb. der Berl. Akad. 1841, p. 377), two of which
are to be inserted in this family, as allies of Pandorina, and are very briefly
characterized under the names of Calia and Stephanoma : —

CALIA. — Monads imbedded in a gelatinous mass, aflixed to plants, and
not swimming freely about. Two species are known ; the characters not given.
This genus is very probably nothing more than one of the simple Algte.

STEPHANOMA=Paw?orMia with a single zone of corpuscles, which divide
like the cells of Gonium. One species obsei'ved exhibiting a circlet of sphe-
lodes imited to form a wreath or zone. This genus is probably the same as
Stephamsphcera (Cohn, A. N. H. 1852, p. 407).

Genus STEPHANOSPBLERA (Cohn) (XIX. 38-58).— A famHy of cells,
rotating and moving throughout life ; composed of eight green primordial
cells, each bearing two active cilia ; arranged at equal distances in a circle,
enclosed in a common hyaline globose vesicle, or common envelope ; pro-
pagated both by macrogonidia (originating from eightfold division of each of
the green cells), which bear two cilia, and axe congregated into eight octonary
families, and by very numerous smaller microgonidia (produced by multifold
division), revolving at first within the common vesicle by the action of four
cilia, and then escaping singly.

SxEPHANosPK^aiA pluvtalis, — Green,
cells globose, elliptical, or fiisifoiTO, often
running out into mucous rays at both
ends. Diameter of the cells = l-330th to
l-180th of a line (0-0065 to 0-012 mm.) ;
diameter of common vesicle = l-80th to

l-40th of a Ime (0-028 to 0-055 mm.).

Revives after desiccation. Inhabits
hollow stones filled with rain-water, in
company with Chlami/dococcus jibmalis :
Salzburg, Wemeck?'; Zamora, A. von
Frantzius ; Ilirschberg, Von Flotow.

Dr. StrethiU Wright has met with Stejjhanosphcera in Scotland.

FAMILY v.— VIBRIONIA (see p. 184).
(XVIII. 57-69.)

AccofiDiNo to Ehrenberg, the members of this family are distinctly or ap-
parently polj'gastric, but without a true alimentary canal; have neither
appendages nor lorica, and are incapable of changing the form of their body.
They are linked together in thread-like chains, formed by their imperfect
transverse self-division. Infonnation respecting the \'ibriouia is very im-
perfect ; this is attributable to the exceeding minuteness of the individual ani-
malcules which compose the chains. These last have never any determinate
length, or number of component corpuscles, and they are sometimes so short
as to be made up of not more than two or three individuals, which are only
distinguishable from 3Ionas Tcrmo and M. Orejmsculum by their union in
chains, and by their peculiar, though not easilv characterized movements
The motion of the chains is generally of a writhing character. In one g(>nus

2 M

530

SYSTEMATIC mSTOBY OF THE INFUSOEIA.

(Bacterium), a single vibratory filament is present. In this same genus the
individuals are strung more tightly together, so that the filifonn cluster, not
being able to exert the writhing movement seen in the true Vibrionia, moves
rigidly in a direct coiu'se. In Spirillum the articulations or lines of imperfect
fission are obHque ; hence increase in length by division engenders a spiral
chain.

The animals of this famUy, says Dujardin, "are the first Infusoria which
present themselves in all infusions, and those which from their extreme smaU-
ness and the imperfection of our means of observation must be considered the
most simple ; .... and it is only their more or less active movements which
lead to their being regarded as animals. I have been sometimes induced to
believe that a flageUiform filament, analogous to that of Monads, or rather a
spiral undulating one, exists, and that this is the cause of the peculiar mode
of locomotion. Is the Bacterium triloculare, described by Ehrenberg as having
a proboscis, a true Yibrio ?

" All that can be with certainty predicted respecting their organization is
that they are contractile, and propagate by spontaneous fission, often imperfect,
and hence giving rise to chains of greater or less length."

As stated in our general history of the family (p. 184), the present tendency
among naturalists is to refer Vibrionia to the vegetable kingdom. Cohn
assigns them a place in the family Mycophycese among the microscopic aquatic
Fungi. Perty retains them in his group Phytozoida, expressing at the same
time his conviction that they are of a vegetable nature. Indeed the only
reasons advanced by Ehrenberg in support of the animality of Vibrionia are,
that they are actively, and, to his apprehension, voluntai-ily moving beings,
and multiply by self-division, — reasons which, in the present state of know-
ledge, must be held worthless, A re-examination of all the enumerated
species, as Cohn remarks, is imperatively necessary before we can come to
any safe conclusions relative to the true structure and affinities of the
Vibrionia ; and this same able observer has himself set the example by con-
ducting such an examination of one species as to clearly indicate its physio-
logical characters and its relation to Palmella and Tetraspora among the
Algae, and more particularly to Sphcerotilus among Mycophyccae,

The Vibrionia are developed with extreme rapidity in all liquids containing
changed or decomposed organic substances, in animal fluids — the saliva, senun,
urine, &c. When colouring matter has been mingled vrith the water, its
imbibition by the corpuscles has never been observed.

This family is distributed by Ehrenberg as follows : —

Articulated tlu'cads (clusters) f Inflexible Bacterium.

straight, the transverse divisions-^

being rectangvdar [ Flexible, like a snake Vibrio.

Articulated threads spii'ally twisted
(like a bell-spring or cork-screw), _
the transverse divisions being

o'^lil^^ inflexible.

/Tlexiblo Spirochata.

I^with a cyUndrically-j g i^in^,,,.
extended spiral form. J

mth a compressed 1 gpirodiscus.
^ spiral form J

On this subdivision of the family Vibrionia, Cohn {Entw. p. 117) has ex-
pressed himself voiy strongly. Ho says, " An inextricable confusion prevails
when specific characteristics are attempted : we have the observations, good
and bad, of various authors, weak and strong amplification of tlie objects,
young and old conditions commingled witliout any critical endeavour to
distinguish between them." Feeling that there is no sufficient basis for it,
Cohn does not attempt a classification of the Vibrionia. The ilfojurs LiMola

OF THE VIBHIONIA.

531

(E.) or Bactemmi Tenno (Duj.) is, according to his well-conducted investiga-
tions, no other than the swarming stage of a microscopic aquatic fungus
belonging to the Mycophyceaj, of which he makes a new genus, named
Zooglcea : again, Spirochceta plkatilis is, in his opinion, an Alga of the genus
Spirulirui, and the stiff Yibrios allies at least of the Oscillariaja, of the genus
Beggiatoa; the shorter Vibrios md. Spirilla likewise resemble OsciUariaja and
Spinilina.

Should Cohn's opinions be confirmed, the Vibrionia, as a distinct family,
woiild be well nigh broken up. In fact, his views are generally acceded to ;
for Perty, Burnett, and others all point out their peculiar affinities with the
Oscillariae, and discover similar forms among the transitional phases of various
AlgiE, and, indeed, among the antheridial spores of higher plants. The
value of Spirodiscus as a genus is little insisted iipon by Ehrenberg, who
instituted it ; and in all probability it should be set aside, and Spirochceta also
be sacrificed with it. The only species of Spirodiscus named, Perty surmises,
might have been nothing more than the spore of a fungus. Dr. Burnett has
expressed himself as foUows to the same effect ; for he observes, " When we
come to organisms as minute as these, the distinguishing characteristics of
genera and species become too obscure and equivocal to have much value ; and
the best microscopists have arrived at the conclusion that such distinctions
are too refined and will not bear the test of experience.

" The genus Vibrio — ^the simplest — I regard as the first appearance of the
young Alga, existing then as the smallest cells, arranged in linear series.
The genera Spirillum and Bacterium, composed of larger forms, and of a finer
and more soUd structure, represent the more advanced forms ; and as all Algse,
as they advance in size, tend to consohdate into mycodermous forms, losing
much of their primitive cell-structure, so these two genera appear to have lost
their old beaded type. As for the two remaining genera, Spirochoita and
Spirodiscus, but little is positively known. They scarcely appear to belong
to the other forms of this family ; and as Ehrenberg himself has expressed a
doubt upon the subject, one may as well omit a further notice. Therefore,
in a structural point of view, the species of this family seem to be only Alga3
at different stages of growth."

Dujardin instituted only three genera of Vibrionia, viz. : 1. Bacterium —
straight, sUghtly flexible threads, more or less distinctly jointed, and slow in
their movements ; 2. Vihrio — either straight or flexuose, with a more or less
vivacious writhing movement ; 3. Spirillum — having the form of a corkscrew,
revolving on their long axis, oftentimes with great rapidity, but never straight.
Perty has made a more ambitious attempt to classify these minute organisms ;
of its utility, however, little can be said, for our acquaintance with them is too
imperfect to estabHsh satisfactoiily any distribution of them. To resume :
Perty makes a section of his heterogeneous group Phytozoida, which he calls
Lampozoidia, represented by the one family " Vibrionida." The " Lampo-
zoidia " aro defined as " colourless, or rarely blue, yellow, or red, never wrcen
organisms, without special organs, and with scarcely a trace of differentiation
of substance. Their motions, though seemingly vohmtaiy, are in fact only
automatic. They multiply by transverse fission, and in so doing produce chains
and fibres." Of the family Vibrionida, two varieties aro distinguishable ■—
A. Spirillina, in which the chain or fibre is spirally coiled ; B. Bacterina in
which it is contorted or straight. Spirillina contains two genera, Spirocliceta
and Spirillum ; whilst Bacterina is made up of fom-, viz. Vihrio, Bacterium

IMetallacter, and Sporonema. The new genera named will follow after our
account of those recognized by Elirenborg, and the notes on the others in
their proper places.
2 M 2

532

SYSTEMATIC HISTOET OF TITE INFUSOniA.

Genus BACTEEIUM. — Vibrionia distinguisbed by tbo coiiHiscles being
connected together in a tbread-like more or less rigid or inflexible cliain, and
by miiltiplying by transverse self-division at right angles to the chain.

The three species known are colourless, and extremely minute. Ehrenberg
remarks " that only one of the species has been satisfactorily determined
and that their organic relations are altogether so obscure, that our judgment
respecting them must imavoidably be left in a fluctuating state." In B.
triloculare a vibratory proboscis, a granular mass -within the body of the crea-
tui-e, and spontaneous division are discoverable. All the species enjoy an
active power of locomotion. Perty says that he is unacquainted with the
species of Bacterium enumerated by Ehrenberg.

A magnifying power below 500 diameters will not exhibit the divisions
or transverse lines between the individuals or links of the wand or chain.
Bacterium occui's around decomposed vegetable matter, on the surface of water
containing Chara, &c.

Bacterium triloculare. — Chain in
the form of short cylinders of from two
to five oval coi-puscles, and- generally
about three times as long as their dia-
meter ; ti-ansverse jimction-lines distinct.
Ehrenberg has observed not more than
five links together, nor less than two.
"By throwing," he adds, " a little colom--
ing matter into the water, an evident
vibration may be perceived near the an-
terior portion of the corpuscle or of the
chain ; and upon a veiy close inspection
a simple filiform, though short, proboscis
may be seen, which, in the larger speci-
mens, is one-third the length of the body,
and in the smaller, one-half." The motion
of this creature is ti-emrdous, or slowly
revolving upon its longitudinal axis.
In the water of bogs. Length of chain
1-4800" to 1-2304"; single coi-puscle

1-11520" (xvm. 57). Group 57 repre-
sents several of them ; two towards the
right are magnified 1000, the others 290
diameters.

B. Enchelys. — Chain composed of
somewhat indistinct, colomiess, oval
corpuscles imited in smaller cylinders
than the preceding; transverse lines
faintly marked. In river water. Length
of chain 1-2880".

B. Punctuin. — Chain cylindiical, com-
posed of indistinct, colomiess, globose
coi-puscles ; much smaller than the pre-
ceding species ; ti-ansverse lines faintly
marked. In water wherein bread has
been steeped. Length of chain 1-4032".

B. Catemda (D.). — Filiform, cylindri-
cal. Length of individuals 1-8600" to
1-6500" ; 3, 4, or 5 ai-e united together,
foiining a chain 1-1300" in leuorth.

Genus VIBEIO. — Characterized by the corpuscles being connected together,
through incomplete self-division, in filifonn flexible chains resembling in
miniature the figure and movements of a snake. Juuction-Unes at right
angles to chain.

Vibrio Lineola (Bacterium Termo,
Duj.) (xviii. 69). — Forms a minute
cylmdrical and slightly flexible wand,
roimded at both ends; separate cor-
puscles somewhat indistinct, of nearly
globular form, and colourless. Common
in vegetable infusions, especially around
tlie stalks of flowers in "lasses, and in
foul ponds. Length of wand, from
1-.3600" to 1-200". Thickness 1-3000".
Both Cohn and Perty join in tlie use of
Dujardin's name for this species, and in
representing Ehrenberg as in error in
identifying and fixing its character (see
genus Zooglcea).

V. tremulaus. — Wand short ; stouter,
yet more flexible, than the preceding:
avticulntions of an oblong form, not
distinct. In water emitting n disa-

gi-eeable odom\ Leng-th of wand 1-3600".

V. suhtilis. — Wand slender and elon-
gated ; colourless ; articulations distinct :
motion slightly vibrating, withoiit vary-
ing the dhect position of the articula-
tions. Length 1-450"; thiclmoss 1-24000".
Pertj' savs this species is only a variety
of F. (3tctnUacter) Bacillus.

v. Rugula {Vibrio Rugulo, M.) (sxm.
64). — ^^'and elongated ;" stouter than the
preceding; articidations distinct; and
colourless ; motion brisk and sei-pentine ;
common in infusions and foul water.
Length 1-580" : thicluiess 1-12000".

Y. prolifcr.—'SYnnA sliort, stout, and
colourless"; articulations distinct. Mo-
tion slow and (ortuous. In infusions
whore mildew is present. 1-1100".

\. Bacillus (Ur) = MetaUacter Banllus

OF THE VIBKIONIA.

533

(Perty). — Wand stout, elongated, and
transparent ; articulations distmct, or be-
come so when dried ; motion sei-peutine ;
form straight when quiescent (xvni. 62).
In vegetable infusions and fetid water-
Length 1-200" ; thiclniess 1-17200".

V. synxantliiis. — Wands (bacilli) very
fine and short, rather flexuose, rarely, of
more than five segments (individuals),

yellow and minute. Coi-puscles 1-70000"
to 1-52000". In decomposing co\y'8-
millc, in which it produces a yellow tint-
V. syncyanus. — Wands very slender
and short, somewhat flexuose, of seldom
more than five segments, very small, and
of a blue colonr. 1-78000" to 1-52000'/.
Also foimd in cow's-milk, in which it
produces a decided blue shade.

The following species are from Dujai'din's work: —

V. serpens (M.). — Body very lon^, fili-
fonn, imdulating, generally pui'suing a
rectilinear coiu'se, with fi-om ten to
fifteen bends in its length. 1-1050".

V. ambiguus. — Under this name, Du-
jardin describes a Vibrio with stiiF fili-
form joints like those of V. Bacillus, but
much larger (xtoi. 60). Four or five,
or even more, were articulated together;
owing to the large dimensions, each joint
could be seen composed of a resistant

tube, in which a glutinous substance was
more or less closely packed. Moreover,
a bifurcation at the exti'emity of a joint
was sometimes seen to occiu", giving rise
to two rows of branching chains, of more
or less length.

Such observations tend to render the
animality doubtful, not only of this
Vibrio, but also of the similar but smaller
V. Bacillus.

Genus SPIEOCHiETA. — Chains S]3iral, filiform and flexible, lengthening
by the imperfect or incomplete mode of self-division. The details of orga-
nisation are at present unlmown. Dujardin does not admit this as a genus
distinguishable from Spirillum; and Cohn is unable to discover any suf-
ficiently distinctive chai-acters between this and the acknowledged vegetable
genus SjnruUna. Spirochceta moves with an immense activity, sui'passing
what is observed in the recognized species of Spindina ; but this difference
is not sufficient to sepai-ate the two genericaUy. Spindina plicatilis is figiu'cd
(XVIII. 67, 68). Cohn moreover inclines to the opinion that Sj)irtdina,
Spirochceta, and Spirillum are members of one common group of organisms of
a vegetable nature. The distinctive feature between Spirillum and Spirulina
is the smaU number of corpuscles found united in the chains of the former
compared with the latter.

SpraocHiETA plicatilis ( Vibrio serpens, numerous and closely-an-anged coils ;

M.) (xviii. 63).— Coi'puscles very deli- colourless. At Tilbury Fort. Length

cate, nearly globular, connected together of chain 1-170" to 1-440" ; thickness

in a long, filiform, spiral chain, having 1-12000."

Genus SPIEILLUM.— Dcvclopes in the form of tortuous chains, or of
inflexible and cylindrical spirals. The incomplete self-division, which is
oblique in du-cction, produces the characteristic coiling of the chain. Motion
brisk and energetic.

Spinn^LUM tenue. — Spiral of three or
four coils, constituted of very slender,
sliglitly bent colourless fibres ; articu-
lations distinct. In vegetable infusions.
Length al)out 1-900"; thickness 1-1200".

S. Uiidula ( Vibrio Umlula, M.) (xviii.
59-01). — Spiral of one turn and a-lialf ;
coi-jiuscles short, stout, and nnich bent ;
articulations distinct ; colourless ; when
dry, the articulations arc more distinct.
In stagnant water liaviiig a mildew
scent. Length about l-loOO"; thickness

1-20000". This species, I'erty remarks,
frequently grows so as to fonn clusters
or masses which are motionless, and,
like all the rest of the Vibrionia, never
produces true vegetable fibres.

S. volutans {Vibrio Spirillum, M.). Of

three, four, or more coils; fibres very
tortuous, long, and stout; articulations
distinct ; colourless. In vegetable infu-
sions, liougth of spiral 1-2200" to
1-500" ; thickness I-I4400".

534

SYSTEMATIC HISTOET OF THE INFUSOHIA.

Porty adds the following species : —

S. rufum. — Has the figiu'e and size of
<S. Undula, hut is of a red colour. No
articulation discoverable. In pond-water
about Bern, which had been kept
several weeks. The claim of this to be
considered a distinct species is highly
doubtful ; for its only assumed chai-ac-
teristic, viz. its red colour, is of no
weight, being in the Phytozoa generally
a variable condition, due to chemico-
vital changes in the organisms, and
ephemeral in dm-ation.

S. (?) Bryozoon (Un^er) (xvn. 520-
531). — Coils consist of a tnick body.

with a delicate, wavy, hair-like proboscis.
These creatiu'es, found in the reproduc-
tive organs of plants, were called by their
discoverer, Dr. Unger of Gratz, spermatic
animalcules, and are described m detail
in the Regensburger Botan. Flora, 1834 ;
and also in the 18th vol. of the Nova
Acta Nat. Cur., Bonn, 1838. A con-
densed view of this subject is given by
Dr. Meyen in the Jahresherickt for 1838,
from which the appended translation is
made. The accompanying illustrations
(xvii. 520-531) were kindly supplied by
Dr. Unger for this work.

" The spermatic animalcules in Sphagnum consist, according to the earlier
observations of Unger, of a thick body, and a thin filiform tail ; when in motion,
this tail being anterior, he considers it analogous to the proboscis (filament)
of many of the Infusoria. No true active motion of the body itself has been
observed by Unger ; but he distinguishes between the mere locomotive and the
rotary movements of the whole animalcule. The simplest motion takes place
in a spiral direction ; and if the proboscis is contracted, the movement is
simply rotary. During the locomotion of the creature, which proceeds in a
spiral manner, Unger saw from one to three revolutions of the body in a second ;
and during rotation he noticed the point of the proboscis to be in a continual
state of tremor. Unger endeavoured to show that the spermatic animalcules
of the mosses are analogous to the spermatic animalcules of animal organisms,
although we find certain features in the former not seen in the latter, and
which may somewhat embarrass their classification, the chief of which ai"e
the steadiness of the spiral dii'ection of the proboscis, and their manner of
movement. Lately, Unger has found spermatic corpuscles in the antheridia
of Polytricimm juniperinum, P. commune, P. urnigerum, and P. alpcstrc, as
well as in Funaria hygrometrica, Bryum cuspidatum, B. punctatum, &c. In
PolytncJmm commune, the corpuscles are found in very smaU hexahedral
cells with rounded comers. Generally, whilst in the cells they are motion-
less ; in some, however, a tremulous motion of the thin proboscis was seen,
and in others, again, a rotatory motion, iuteii-upted at intervals. The dia-
meter of the delicate proboscis is 0-004 of an inch. In a few cor^juscles,
isolated from their cells, a trembling oscillating motion of the proboscis was
perceptible."

To these particulars may be added a remark of Dr. Unger, quoted in the
Ann. des Sciences Nat., which led to the introduction of the subject in this
work.

" The doubts," Unger says, " which remain concerning some of the organs
of the animalcules of mosses, further increase the uncertainty as to their
situation in the scale of beings. From aU cii-cumstances, I am inclined to
place them in the genus Spinllum of Ehrenbcrg, and to describe them under
the name of Spirillum Bryozoon."

Mr. Varley, in his article on Chara, in the 60th vol. of Tran^. Soc. Arts, has
the following observations on the same structures : —

" From these cells " [in the globule of the axil of the Chara] " grow out
numerous clusters of long vessels, possessing the most extraordinary features
yet observed. When these are first protruded from the globule, if not qmte
nuiture enough, their appearance is like dense or strongly -mai'kcd ringed

OF THE VIBEIONIA.

535

vessels, the divisions of which, or their contents, soon begin to appear irre-
gular After a while, these cui-ls within the divisions become agitated:

some shake or vibrate ; others revolve in their confined places ; and many-
come out, thus showing that they are spirals of two or three curls ; these,

with an agitated motion, swim about Now the field of view appears filled

with life : great numbers of these spirals are seen agitated and moving in aU
directions ; they all have a directHe force, one end going foremost, and never
the other ; many stray a great way out of the field : these, by getting clear
of each other, are the best to observe ; they do not quite keep their form as
a stiff spiral, but their foremost end seems to lash about, and to many are
seen attached almost invisible but very long fibres. These fibres were in
quick undidations, which ran in waves from the spiral to their farthest end.
It appears that these fibres cause many of the spirals to entangle together,
and thus bring them sooner to a state of rest ; therefore the separate ones
were best to observe."

Among the more recent observations on these motile fibres (from the anthers
of Chara vulgaris and Ch. hispida), are those of M. Thui'etin the Annates des
Sciences Naturelles, a translation of which will be found in the Annals of
Natural History , vol. vii., from which we extract the following paragraphs : —
" The portion of their body most apparent appeared like a spirally-rolled
thread, of three to five curves. They were slightly tinged with green, similar
to the nuclei ; and, like them, turned brown with iodine, their two extremities
becoming more or less coloured (according to the quantity of iodine employed)
than the rest of the body, thus indicating a difference of nature in these portions.
At a little distance behind one extremity proceed two bristles, or tentacula,
of excessive tenuity, which the animalcule incessantly agitates with great
rapidity. These are probably organs of locomotion, similar to the filiform
prolongation foimd in the Infusoria without cilia. Indeed, the part thus
famished with tentacula moves foremost, di-awing after it the rest of the
body, which turns about in the water, but always preserves its corkscrew
form. The incessant agitation of these tentacula, and their extreme tenuity,
rendered it impossible to observe them in the living animal ; recoui'se was
therefore had to the evaporation of the water, or to the application of a slight
tincture of iodine, when the animalcules ceased their motions, became con-
tracted, and their spiral unroUed, when the tentacula were rendered very
distinct, from their brown colom-. These tentacula were frequently observed
to be soldered together from one-half to one-third of theii- length upwards ;
but others were also noticed to be entu'cly separated down to theii' bases. A
swelling similar to that in the flexure of the body was perceived in their
curves.

"Ammonia arrested their motions, and contracted the body gradually into
a small oval mass, but did not produce the phenomenon of decomposition by
solution {dijjlmnce), so remarkable in the Infusoria. A very weak solution
of hydrocliloric acid in water violently contracted them into a shapeless mass."

In Plato XVII., figs. 520-522 represent the spermatozoa found in Foh/-
trichum commune, the first figiu'o exhibiting them enclosed in the cellules, and
the others, swimmmg freely. Figures 522-524 are taken from Marchantia
pohjmorplia. Figure 525 is from Sjjhagnum capilUfoVmm. AU the above
are magnified 1000 diameters. Figures 520-528 are from the Chara vuhjai-is,
and figiurcs 529-531 from Jungermannia pinguis, as figured in Mcyen's work
{Neues System der PJlanzen).

On this subject of vegetable spermatozoa, Schleiden, in his recent Avork on
the "Principles of Botany," remarks— "The doctrine of vegetable spermatozoa
is now, I hope, graduaUy dying away. The granules (generally starch), taken

536

SYSTEMATIC HISTOBY OF THE INFUSOHIA.

from spermatozoa, have indeed lost their life in Fritzscho's tinctui-c of iodine,
since their evidently purely physical molecular movement remained un-
destroycd.

" . . . . Fritzsche has completely settled the matter ; and every unprejudiced
observer may convince himself with ease of the completely imtenable nature
of the wonders formerly spun out, especially by Meyen. The confli-matoiy
observations of Niigoli on this point are also of great value."

Again, he says — " As to the mechanism of the motion, we know just as little
as we do of that of the moving cilia ; of the cause of motion, of the motive
power, just as much as of that of the contraction of the primitive muscular
fibre, of the motion of animal spermatic filaments, and of the vibratile cilia
on animal and vegetable cells ; that is to say, absolutely nothing."

Fm'ther, in reference to the motion of the so-called spermatozoa, Schleiden
observes — " There can be no question as to its not being a vital phenomenon,
because the motions continue even in the alcoholic tincture of iodine (an
absolute poison for all vegetable and animal life), of which one may readily
convince himself, and which Fritzsche has, with his weU-known accui-acy,
shown to be the case in a great number of plants." (Dr. Lankester's trans-
lation, pp. 99 and 359.) This assertion of Schleiden, that tincture of iodine
is an absolute poison to all animal and vegetable life, must be received with
reserve, since animalcular life has been known to exist in agents, such as
strong acids and mineral poisons, which, a lorion, would appear quite as
inimical to it as tincture of iodine ; and even minute animals — the Amri, of
far higher organization than the Polygastrica, have been stated to preserve
life in strong acetic acid.

Before dismissing this subject, it may be useful to append some observa-
tions made by Wagner and Leuckart, in their elaborate and original article
before-quoted.

Having stated that, up to the most recent period, the so-named spei-matozoa
of animals have been considered independent animal organisms, or parasitical
animals, and classed among the Infusoria, the authors proceed to say that
such assumption is perfectly irreconcileable with our present knowledge of
these bodies, derived principally from the discoveries of R. "Wagner, Von
Sicbold, and KolUker : — " With our existing means of scientific diagnosis it
can be proved that the formations in question are mere elementaiy consti-
tuents of the animal organization, like the ova — constituents equally as neces-
sary for the spermatic fluid as the blood-globules are for the blood. The re-
markable phenomena of the life of spermatozoa are quite analogous to those
phenomena of motion observable not only in animal formations, but also in
vegetable structures — as, for instance, in the spores of Algas and of the lower
species of Fungi, and in the so-termed Ft6n'ones which grow out into the fibres
of the Conferva called Hygrocrocis. Moreover, an unprejudiced observation wiU
prove that the spermatozoa are every^vhere void of a special organization, and
consist of an uniform homogeneous substance, which exhibits, when examined
by the microscope, a yellow amber-like glitter. The opinion of an intenial
organization of the developed animal elements was not a little supported by
the various remarkable phenomena of motion which were frequently perceived
in them. In former times, when people had no idea of the existence and
extent of the so-called automatic phenomena of motions which take place
without the intervention or influence of the nciTous system--wlicn notliing
wa.s known of the motion very similar to a voluntary one Avhich exists even
in plants — this movement was certainly calculated to place the independent
animal nature of the spermatozoa beyond a doubt. But it is diflercnt now.
We know that motion is not an exclusive attribute of animals, and that an

OF THE VIBKIONIA.

537

inference respecting the animal nature of the formations in question, however
similar the motion observed in them may be to that of animal organizations,
is a very imsafe and venturesome one.

" We know that certain elementary constituents, animal as well as vegeta-
ble, possess a power of movement, and that they retain it for some time after
having been separated from the organisms to which they belonged. We only
need here remind our readers of the so-called ciliated epithelium, the several
ceUs of which swim about in the fluid surrounding them, and have not un-
frequently, and that even quite recently, been considered independent animals ;
or, again, of the spores of the Algse, which actively move by the aid of a cUiated
investment, or of a single or manifold long whip-like fibre, until they eventually
become fixed and developo themselves into a new plant. Such spores as these
may be found described and illustrated in the well-known magnificent work
of Ehreuberg, classified as Infusoria, under the groups of Monadiua, Volvo-
cina, &c.

" Under such circumstances we may consider ourselves perfectly justified
in declaring eveiy attempt to prove the parasitic nature of the si^ermatozoa
by the characteristic of their peculiar motion, as futile and inadmissible."

Genus SPIEODISCUS (XVIII. 63).— Self-division imperfect and oblique,
producing elongated chains, or inflexible sj^irals, of a disc-like fig-ure. Its
organization is so little known that Ehrenberg considers the genus as by no
means satisfactorily detei-mined ; indeed there is little doubt that it is not a
member of the Vibrionia.

Spirodiscus fulmis. — A lenticular
spiral, of a yellowish brown colom-.
Ai'ticulation indistinct, xvm. 63 repre-

sents tliree spirals, magnified 200 dia-
meters. Amongst Confervae. Breadth
of spii-al 1-1200".

Genus ZOOGLCEA (Cohn). — CeUs (corpuscles) very minute, bacUliform,
hyaline, aggregated together in a hyaline muco-gelatinous, globose grape-
like, and subsequently membranaceous mass, from which they may detach
themselves, and swim away with a vacillating movement.

ZooGLOEA Termo. — Free, moveable
cells, straight, from 1-2000"' to 1-700'".
It is equivalent to Palmella infusiomim
('E.),Micraloa teres (vonFlotow), to some

described fonns of Ch-yptococcus, and to
Bacterium Termo (Duj.), the Vibrio
Lineola (E.) (x^^^. 69). (See Part I
•^.l&Ietseq.)

Genus METALLACTER (Perty). — Bacterium-]ikQ corpuscles, growing by
repeated imperfect division into stiff or slightly flexible fibres (chains), which,
under certain determinate conch tions, eventually lose th oil- power of movement
and grow into Rygrocrocis-]ike, tangled, fibrous masses, colourless or of a
greyish hue.

Mktallacteh Bacillus = Vibrio Ba-

cillus. — Articulation unobsei-vable, or
seen with much difficulty. Vibrio sub-
tilis (E.) and Bacterium Catenula (Duj.)

arc, m Forty's judgment, nothing more
than delicate and transpai-ent varieties
of tins same organism. In Switzerland
m foul pond-water, at all seasons.

Genus SPORONEMA (Perty) (XVIII. 65).-Very minute, cylindrical
unarticulated, hollow fibres, closed at one end (rarely at both) frcquentlv
enclosing two elliptical corpuscles (probably spores). J' i y

Movements tolerably quiclc, either end
toi-ward. Specmiens occur whore tlie
spores distend the fibre ; others contain

Sporonema (iracih (xvm. 05). —
Fibres from l-7()0'" to 1-80"' long, and
1-1000"', and under, broad, of extremolv

5alc-greenish tint. Often occurs with
letamctcr Bacillm, which it much re-
sembles ; yet is always non-articulate.

nono._ In the sednnont of pond-wnter
contammg Chara and Lcmnn, from
various bwiss localities.

538

SYSTEMATIC HISTOEY OF THE INFUSOllIA.

In Ehrenberg's system the family Clostcrina follows here, but in this edi-
tion it is transferred to the Desmidieaj, of which it constitutes an important
genus, (See Part I. p. 1 et seq.)

FAMILY VI.— ASTASI^A oe EUGLENiEA (see p. 188).

(XYIII. 35-56 ; XX. 15-21).

The members of this family are, according to Ehrenberg, characterized by
being deficient of a true alimentary canal and lorica, and by having a single
aperture and the power of changing their form at pleasure. Their organs
of locomotion consist of a tail in most cases, a single filament in three genera,
and a double one in a fourth. It is probable that filaments exist also in the
other two genera, Colacium and Distigma. The internal vesicles were pre-
sumed to be gastric sacs, although the usual test of their being so, viz. the
application of coloured food, failed in Ehrenberg's hands ; yet, he says, he
noticed some manifestations of a digestive power in the green and red cells of
Euglena viriclis. In Euglena there are, besides green ova (granules), a gland
(nucleus) and a contractile vesicle ; but Astasia, Distigma, and Colacium ex-
hibit only ova. Large red points are found in five genera. In Eugletxa
longicauda and E. amhlyophis, adds Ehrenberg, " the first indication of the
presence of nervous matter to be found in the polygastric Infusoria " is met
with in the form of a white glandular knot, situated below the eye.

The following table illustrates the characters of the genera of this family
as instituted by Ehrenberg : —

Eye wanting Astasia.

Vith oneP^^^'^S AmblyopMs.

f /Free ■ P'^o^oscis | rp^jj present Euglena.

With one eye \ \ With two proboscides Chlorogoniuni.

Attached by a pedicle Colacium.

^ With two eyes Distigma.

The family Euglensea (Eugleniens) of Dujardin in a great measure corre-
sponds with that of Astasiaea of Ehrenberg; but Dujardin prefers the term
Euglonaea, on account of the resemblance of the other name to that of a
family of Crustaceans, viz. the AstacioBa.

Dujardin looks upon the so-called eyes as insnfficicnt to afford generic
characters, which he would derive from the nature or apparent stracture of
the integument, and the number and mode of insertion of the filaments. On
these principles he establishes a genus Pohjsehnis, characterized by its many
filaments ; two genera, Zygosehnis and Iletcronema, by a pair- of filaments, in
the former of equal, in the latter of unequal size. The remiuning Euglcna\i,
which have but a single filament, can be but uncertainly defined : sucli are
the Euglencn, mostly coloured, and having a red eye-speck and a tail ,; the
Astasice without coloiu- and tail, but with a filament flexible thi-oughout, and
springing abrui)tly from a notch in the anterior extremity ; and the FeraiienKe
only differing from the Astasia} in ha^dng a filament rigid at the base, and
apparently a continuation of the tapeiing anterior extremity of the animalcule,
llie two last genera arc, however, but provisional.

Astasia3a is one of the families in the group of Phytozoidia of Perty, who
ignores the genera Amhhjophis and Distigma of Jihrenborg, adopts the Pcra-
nema and Zygosehnis of " Dujardin, and adds, as new genera, Eutrepiia and

Eye present

OF THE ASTASI-ffiA OB ETJGLENiEA.

639

Dinema. Again, Schneider (A. N. H. 1854, xiv. p. 327) would separate
CJilorogonium from the Astasiaja on account of its unchangeable form, and Mr.
Carter (A. N. H. 1856, xviii. p. 116, and 1859, iii. p. 15) would refer EuglencB
to the vegetable, and Astasice to the animal kingdom. The differences pre-
vailing among naturalists relative to the beings to be admitted into the family
Astasiffia indicate either that its characters are not laid down with suflacient
precision, or that it is not a natural group. The power to vary the figure
can be no adequate character ; for this is partaken by the gonidia of various
Algae in certain amoebiform stages of existence, and, on the other hand, is
absent in some species enumerated by Ehrenberg in the genus Euglena, as
weU as in Chlorogonium. The tapering or tail-like prolongation of one ex-
tremity, the existence of one, two, or more ciliary filaments, as also of a red
speck, are likewise features common to numerous zoospores. Even when
appeal is made to their internal organization and functions, nothing appears
whereon the definite characters of a natural family can be built. Eor, on the
one hand, the organization assigned them by Ehrenberg is now held to be
untenable, and, on the other, no harmony prevails respecting the internal
stiTicture as recorded by different observers of the various genera. Mr.
Carter, in the paper just quoted, states unhesitatingly that most of the
Astasice enumerated by Ehrenberg are animal forms, whUst the Euglence
are vegetable. He remarks that, " although no two Infusoria can be more
alike than Astasia limpida and Ehiglena when casually observed .... yet the
absence of chlorophyll and the presence of a stomachal cavity, &c. for the
digestion of crude food in the former, and the presence of chlorophyll and
absence of a stomachal cavity, as well as of all means of taking in crude food
for digestion, in the latter, are distinguishing characters which at once place
Astasia limpida on the animal, and Eiiglena on the vegetable side, respectively,
of the great organic kingdom ; yet both Ehrenberg andDujardin have classed
Astasia and Etiglena together."

If the organic difference between Astasice and Euglence be what Mr. Carter
asserts, his proposition to divide the Astasicea of Ehrenberg into two families,
viz. Astasiaea and Euglenaea, must be accepted.

The Astasiffia inhabit ponds, mostly occuriing on the surface, and frequently
tinge the water with their own colour when their multiplication has been
very rapid. When swimming, they present an elongated form, but when
fixed, often appear as round globules. From their beautiful coloiu", their
ever varying changes of fonn, and the rapidity of some of theii- \-ital acts,
they are most interesting and pretty objects under the microscope, and from
their common occurrence ai'e almost always at hand for the student. Many
are capable of progressing by alternately fixing and advancing the head and
tail after the manner of a leech, as wcU as by the usual process of sAvimmino-.

Genus ASTASIA (XVIII. 36, 48,49, 50).— Individuals free (not attached
by a pedicle), and furnished with a long or short tail, but no eye-specks. A.
2nisilla is the only species in which vacuoles have been clearly seen. ' Ova
(granules) are perceptible in A. haimatocles, and probably exist in tlie three
other species ; a locomotive organ in the form of a tliread-Uke proboscis exists
in A. pusilla. Perty unites this genus with Distiqma. The immense num-
bers m which these Infusoria are sometimes developed in a few days and the
blood-red colour they impart, have not unfrcqucntly been the cause of con
siderablo alarm and anxiety to persons rcsichng in the vicinity of nonds or
smaU lakes which have become blood-coloured by their swai-ming

Dujardin's genus Astasia is defined as colourless, obtuse or roimdcd iiosto-
riorly ; whilst those described by Ehrenberg are mosUy green or red and
provided witli a longer or shorter caudal prolongation.

540

STSTEUATIC lUSTOHY OF THE INFUSOIUA.

Astasia hcematoiks (xvm. 86, two
figs.). — Body fusiform or spindle-shaped
when extended; tail very short; body
green at first, afterwards of a blood-red
coloiu". The illustrations represent one
creatm-e extended, and another con-
tracted. Hampstead. 1-380". This spe-
cies is refen-ed by Dujardin and Carter to
the genus Euglena.

A. Jlavicam. — Extensible, cone-
shaped, approaching cylindrical, and
rounded at the foremost extremity. TaU
very short and blunt; granules of a
yellowish colom*. In yellow ditch-
water. Length about 1-430".

A, pusilla. — Extensible, cone-shaped,
swelling out and rounded at the fore
extremity, tail very short and pointed ;
colourless. Motor filaments above twice
the length of the body. Movements
slow; but rotation on the longitudinal
axis rapid. Several phases of Englena
viridis resemble this species in form,
molecidar an-angement of contents, size,
and motion, and are peculiar only on
account of their green colour and red
stigma. Ehreuberg remarks that they
are often so abundant that thousands,
perhaps millions, of these creatures are
sometunes contained in the hollow of a
watch-glass, and form a stratum on the
surface of the water. They might be
mistaken for the young of the A. jla-
vicam, but that the vesicles within them
are laro'er than those in that species,
which IS, moreover, without proboscis.
As soon as a little colouring matter was
thrown into the water, an evident cm-
rent was obsei-ved near the fore part of
the creature ; and by this means, in 1833,
the thread-like filament, which is about
half the length of the body, was fu-st
perceived. Sometimes the entire crea-
ture appears to glisten. Should this
species, upon closer inspection, be found
to be ciliated, it would lie rightly placed
among Peridinitea. 1-1440" to 1-500".
Tlie size of the vesicles remai-ked by
Ehrenberg is no distinctive character; and
Mr. Carter believes tliat both this species
and A. jlavicam either identical with
or very nearly allied to A. Umpida, and
therefore animal organisms, unlike the
EmilcncE, to which they have a general
resemblance.

A. (?) viridis. — Extensible ; of an
ovato-obloug fonn, distended a little at
the middle ; tail very short and pointed ;
green. Amongst Confervce. 1-1200"
to 1-900". This species and A. hwrna-
todcs ore, in Dujardin's opinion, members
of the genus Ein/lena, the only appre-

ciable difibrence between them being the
presence of a red stigma in this genus.
In this opinion Mr. Carter coincides.

A. nivalis (Vogt) (xvii. 532-533). —
Oval, extremities rounded, rarely pear-
shaped, colour deep reddish-brown, mo-
tion rapid. Foimd with Frotococcus ne-
bulosus in snow (Switzerland). 1-1500".
M. Vogt, in his accoimt of the Astasia
nivalis, describes it as invested with a
cai'apace (lorica), open only at the an-
terior exti-emity. This opening is fur-
nished with numerous small cilia ; and
here, doubtless, the mouth is situated,
the indication of which is given by an
orange-coloured tint, which is cleai'er
than that of the rest of the animal.
"The presence of a lorica and cUia
aifords a character which does not
allow this animalcule to be placed with
Astasia, as Shuttleworth has done ; on
the contrary, it ought to be placed in
the family Peridioijea (Ehi\), or else be
regarded .as the type of a new genus,
distingnished by the absence of a groove
in the lorica, and by the stifl' hau's of
Peridinium being replaced by soft cUia."
(On the Animalcules of the Red Snow,
Bill. Univ. de Geneve, 1841.) This pre-
simied species is, in all probability,
nothing more than an encysted cor-
puscle, probably a species of Chlamy-
dococcus.

A. Acus. — Hyaline, figure long-fusi-
form, acute at each end; filament the
length of the body. 1-650". Berlm.
Under the head Astasia, Perty enume-
rates the following species ; but, as he
malces no distinction between Astasia
and Distif/ma, the generic appellation is
not quite equivalent to that used by
Ehrenberg.

A. marf/aritifera (Smarda). — Remai'k-
able by its variability of form, or meta-
bolia, the contents appearing to be driven
from one part to anotlior, filling and dis-
tending one portion, whilst the other is
left empty and contracted. Hyaline
granides (germs?) very distinct. At
periods it loses its filaments, and with
them its powers of swimming, when it
adopts a crawling movemont. Two
clear spots occur near the ba^o of the
filament, which is once and a half to
twice the length of the body: these
spots were called eyes by Ehreubei^-.
who made them the distinctive feature
of a genus Distigina. In pond-water,
and even under ice, but not coinnioii.
A vnrietv, much elongated and slender,
has been called Astasia Seipentidus.

OF THE ASTASIiEA OK ETJOLENiEA.

541

The follo^ving species are described by Dujardin :-

pusilla and A.fiacicans with this species.
Mr. Carter {A. N. H. 1859, iii. p. 15) treats
this organism as an undoubtedly animal
foi-m, and describes it as having a
stomach or digestive cavity, into which
it receives food from without. Unlike
Euglena, which it outwardly resembles,
it contains no chlorophyll. He also con-
siders that it is the same being which
Ehrenberg has described and figured as
Trachelius trichophorus.

A. longifilis (Perty). — Hyaline, with
pale-green internal gramiles ; filament
at least three times longer than the
body : a lateral plait or fig-m-e is seen in
the anterior half. Form imchangeable.
Motion tolerably fast. 1-1000".

A. contorta (xvm. 49, 50).— Colom--
less, semi-ti-ansparent, containing pale-
yellow gi-anules ; cylindi'oid, enlarged in
the middle, obtuse at each end, and
marked with oblique stiite, giving rise
to a twisted appearance. 1-450". In
sea-water.

A. injiata. — Semi-ti'anspai'ent, dia-
phanous, contractile, ovoid, obliquely
but regulaiiy plaited or stiiated. 1-560".
In sea-water.

A. limpida (xvm. 48 a, h, c). — Dia-
phanous, smooth, very variable, fusiform,
more or less obtuse at each end, cleft
anteriorly, and often obliquely doubled
on itself or twisted. 1-650" to 1-530".
In ditch-water. Perty remarks that
Dujardin is wrong in identifying Astasia

Gemis AMBLYOPHIS (XVIII. 45).— Free, with a single eye-speck and
flabellum, but no tail. The flabeUum or filament serves as an organ of
locomotion, and is situated at the fore extremity, which, says Ehrenberg, is
cleft, so as to represent a two-lipped mouth, the filament being very readily
distinguished on the upper Hp. The colour of the animalcule is derived from
the closely compressed mass of green granules, which nearly fiUs the body.
Near the middle of the creatiire is a large, bright, globular, together with five
wand-like bodies, two of which are situated before, and three behind the
former ; these structures together were supposed to be male generative organs.
No contractile vesicle has been observed. Self-division is unknown. The
colom-ed speck is very highly developed. Tovrards the anterior part of the
body, and just behind the filament where the mass of granules commences,
there is a bright-red and somewhat lengthened spot (resembling, as to situ-
ation and colour, the eye of the Rotatoria and Entomostraca), in the clear
space beneath which is a mass of matter of a very peculiar description, of a
globular form, having, to Ehrenberg's apprehension, the appearance of a
nervous ganglion, and being most probably connected with the organ of
vision. This genus is not distinct from Euglena ; for the absence of the so-
caUed tail is insufficient to distinguish it, and, what is more, Perty has seen
Amblyojphis vindis proceed from Euglena viridis in the process of I'eproduction.

Amblyophis viridis (xvm. 45). — and sei-pentine, and by its evolutions

Large, elongated, cylindiical, distended might easily be mistaken for the Euqiena

or compressed, and abruptly roimded at Spiroc/yra, were that creature, like "this,

the posterior extremity ; gi-een, head tailless. Found with Euglenai, chiefly

colourless ; eye-speck large, bright red. in the spring. 1-210" to 1-140" (vide

The motion of this creature is sluggish p. 194).

Genus EUGLENA (XVIII. 37-44, 46, 51, 52, 54).— This beautiful genus
of the family Astasia;a is characterized by being furnished ynih. an eye a
single thread-like filament, and a tail, and by being free. The locomotive
filament is seen in nine species out of the eleven, and has a double appearance
in E. sanguinea ascribed to the condition of the animnlculo preparatory to
self-division. In Euglena hyalina, E.plmronectes, and E. loiigicauda vacuoles
arc generally \nsible ; but in the other species tlioy are obscured by the masses
of green granules which colour their bodies. Certain internal apnonrances
have been recognized, which Ehrcnlierg supposed to be of a male generative

542

SYSTEMATIC HTSTOEY OP THE INFUSOfilA.

nature, i. e. a nucleus. Longitudinal self- division has been observed in E.
Acus, and the commencement of it in E. sanguinea (XVIII. 37-39). Close to
the rod point a supposed nervous ganglion or eye-speck is visible in E. loiiyi-
cauda (XVIII. 44), such as is seen in Amhlyophis. The genus Eugletia of
Ehrenberg, saysDujardin, contains some species of a compressed leaf-like form,
and quite deficient of contractility, which require to be placed in the genus
Phacus of the family Thecamonadina,

EuGLENA sanguinea (Cei-cana viridis,
M.) (x\T3i. 37-39).— Extensible, of an
oblong-cylindrical or spindle-shaped
form, with head greatly rounded ; tail
short, conical, and somewhat pointed.
Flabellum longer than the body in its
extended condition. When yoimg, they
are green, but when full-gi'own, of a
blood-red colour; and specimens are
frequently foimd variegated red and
green. The motion of this multiform
animalcule is generally slow ; and it
sometimes revolves upon its longitudinal
axis in swimming. The thread-like fila-
ment, which is a prolongation of the
iipper lip, and rather longer than the
body, is so delicate as to require consi-
derable care in investigating it, and,
being retractile, wiU often elude obser-
vation. A little colom'ing matter in the
water will exhibit this organ in active
operation ; and it may be distinctly seen
in a single animalcule in a dried state,
upon a plate of clear glass. The double
appearance of the organ in this species
has been before noticed. Ehrenberg
conjectured that the miracle in Egypt,
recorded by the great lawgiver of the
Jews, of turning the water into blood,
might have been effected by the agency
of these creatm-es, or by the Astasia
luematodes. In stagnant water, often in
great abundance on the smface. 1-300"
to 1-210". This is in all probability a
mere variety of JE. virtdts ; the red
colour is not a specific distinction, but
only a sign of maturity.

E. hycuina. — Extensible in a spindle-
shaped manner; head attenuated, bhmtcd
at the extremity, and two-lipped; tail
short, and somewhat pointed; coloiu
transparent and whitish ; rare. 1-280".
Perty asserts that it is only a variety of
^. viridis.

E. deses {Enchelys dcscs,M..). — Extensi-
ble, cylindrical, abruptly rounded at the
head, and shghtly bi-lipped. Tail very
short and pointed ; colour green; motion
a winding and sluggish creeping, never
swimming. Filament very long and fine.
Amongst Lemnro. 1-240" to 1-760".

E. viridis {Cercaria viridis, ISI.) (xvni.
46). — Extensible in a spindle-shaped

manner; head attenuated and short.
Tail short, and cone-shaped, not cleft;
colour green, excepting the two ex-
tremities, which are colourless. The
double-pointed taU represented by Leeu-
wenhoek and others does not exist.
When the creatm-e is young, its eye-
speck is imperceptible or very pale,
and it may readily be mistaken for
Astasia viridis or Monas deses. When
dried on glass, the speck seldom retains
its colour more than a week; but the
filament may be well examined and pre-
served when so treated. Filament twice
the length of the body, which diflers
very much — ^between 1-600" and 1-140".
Perty affirms that E. hyalina is a mere
vaiiety of this species, and that Am-
hlyophis viridis (xvm. 45) is the same,
for he has witnessed the same individual
Euglena produce both Euglena and Am-
hlyophis, This obsei-ver has foimd E,
vitidis at an elevation of 9000 feet, on
the Alps. On the surface of ponds at
Hampstead and elsewhere, conmion.

E. Spirogyra (xvm. 52). — Extensible
and cylindiicnl ; very finely striated and
granulated. The head is a little tnm-
cated, and the hinder part attenuated
into a short pointed tail; coloirr a
brownish gi'een ; motion like E. deses.
Its colour vaiies from a beautifid gi-een
to yellow or brown. It always occurs
singly. E. oxyuris (SmardaO is not
specifically distinct. Amongst Confervas
and Bacillaria. 1-240" to 1-120".

E. Pyrum (xvin. 41, 42). — Obliquely
fluted : when distended, oval or pear-
shaped. The tail generally about the
length of the body, and pointed ; colour
gi'een. Found with many other species at
Hampstead, but not so frequently as the
other species. 1-1152" to 1-864".

E. pfmironecics (Cercm-ia pleiironccffs,
M.). — Comprcssea, ovate-orbicidar, or
in the fomi of an obovate leaf ; striated
longitudinally; colour gi-een; tail pomted,
one-third or one-fourth part the length
of the body, and colourless. In stngnant
water. 1-1152" to 1-480".

E./migicauda (xatcii. 44).— Mostly still,
compressed, elliptical, and leaf-like ; co-
lour gi-een ; tail the leugtli of the body,

OF THE ASTASIiEA OR EUGLENiEA .

543

awl-shaped and coloiuiess. Within this
creatiu-e may often be seen a yellowsh-
green mass of granules. The very deli-
cate vibrating thread-like filament has
its origin &om the more projecting side
of an indentation on the anterior edge of
the body, and is about two-thu-ds its
length. This creature has the power of
twisting its body into a spiral form, but
not of contracting it. It swims freely,
and mostly with a vibratory motion,
occasioned by the action of the filament.
In fi'esh-water amongst Confervse and
Bacillaria. 1-480" to 1-120".

E. triquetra. — Leaf-shaped, thi'ee-
sided, oval-keeled ; colom- green ; tail
shorter than the body, and colomless.
Amongst Lemnas. 1-580".

E. Acus {Vibrio Acus, M.). — Slender,
spindle-shaped, and straight ; head atte-
nuated, and a little tnmcated ; tail very
pointed ; body gTeen in the middle, and
colourless at the extremities. This is one
of the most beautiful animalcides seen
under the microscope ; its gi-aceful form
when swimming, its bright-red eye, the
curious forms it assimies when stationary,
and its remarkable appearance when im-
dergoing self-division, all combine to
render it worthy of observation. Fresh
and brackish water. 1-570" to 1-110".

E. rostrata. — Elongated and conical,
with the hinder part gradually attenu-
ated into a very short tail. Head slightly

bent, like a beak ; colour green. Amongst
Oscillatorioe and Bacillaria. Length
about 1-500".

E. Ovum. — Ovate, green, with a very
short hyaline caudal prolongation, and a
large, double, circular nucleus; 1-1560".
Berlin.

E. geniculata (D.). — Green, elongated,
cylindrical, flexible but not very con-
tractile ; movement slow ; tail tapering,
clear, and at an angle with the body —
hence the name. 1-208" to 170". This
large Euglena is remarkable by its elong-
ated form, by its diameter being nearly
equal to its length, without the bulging
of E. viridis, and by its articidated tail.

E. ohsmra {!>.). — Thick, oblong; dis-
tended and obtuse posteriorly; but the
form very variable ; clearer and of a red
tint anteriorly, eye-speck reddish-black ;
filament half as long again as the body.
1-870". This form Perty sm-mises to be
only a deeper-coloured specimen of E.

sangmnea,

which he often found of a

brown or blackish-red colour.

E. mucro7iata (Perty). — Of a beautiful
green coloiu', the anterior segment or
head frequently hyaline, with a clear-red
stig-ma; tail pointed and ti'ansparent.
Body oval, often longitudinally and
finely sti'iped. Filament overlooked.
Differs from E. gmiculata by the absence
of the angularly-set filament. 1-108" to
1-84".

Mr. Carter describes the following new species from tlie freshwater tanks
of Bombay : —

E. fusiformis. — Short, thick, fusifonn,
obtuse, of a rich green colour, provided
with along, delicate, single cilium, which
projects from a slightly bilabiate anterior
extremity ; a little behind which is the
eye-spot, attached to the contracting
vesicle. Nucleus central, situated be-
tween the ends of two elongated, refrac-
tive, nucleated cells, which extend round
the body equatorially. Tailless. Motion
during progi-ession oscillatoiy, and rotat-
ing on the longitudinal axis. Length
about 1-700", breadth about 1-1100".
Freshwater tanks in the island of
Bombay.

E. zonalis. — Short, thick, ovoid cylin-
drical, slightly narrowed anteriorly, of a
rich green colour ; provided with a long
delicate ciliimi, which projects from the
notch of a slightly bilabiate anterior ex-
tremity ; a little behind which is tlie eye-
spot, attached to the contracting vesicle.

Nucleus central, between the ends of two
wide, refractive, nucleated cells, which
extend round the body equatorially. Tail
adhesive or suctorial (?), short, about
one-sixth part of the length of the body.
Motion dm-ing progression oscillatory
and rotating, on the long axis of the body.
Length l-1100",breadth 1-1800". Fi-esh-
water tanks in the island of Bombay.

These two Euglence are remarkable for
having that refi'active cell or organ which
I have called the " glair-cell " equatorial,
instead of longitiidinal as in Eughna
Spirogpra, or smglo and in the anterior
lip as m Crumenula texta.

E. agilis. — Is a third species Mr. Carter
would distinguish ; but he has given no
details, except relative to its develop-
ment in the still form. 1-600". In the
brackish waters of the marshes of Bombav
{A. N. JL 1856, xviii. p. 246).

Genus CHLOROGONTUM (p. 195) (XVIII. 47; XX. 15-21).~As1mi(e

544

SYSTEMATIC HI8T0BY OF THE INPUSOIirA.

with a double filament. Are free and provided with an eye-speck, taU, and
double filament. The only known species is of a very beautiful green colour,
and has numerous transparent vesicles within it. A distinct, hyaline nucleus
is perceptible in the centre of the animalcule. Self-division of the contents
into four or more segments has been observed to take place, also propagation
by microgonidia. Schneider and Perty concur respecting the propriety of
detaching Chlorogonmm from the Astasiaja. Numerous dull-red specks are
scattered throughout its green contents, no one of which has the clearness
and distinctness of the stigma of Euglence. The primordial envelope, with its
enclosed green contents, varies in figure ; but not the external one, which is
rigid.

Chlobogonittm eiicJilorum (xvm.
47 ; XX. 15-21). — Spindle-shaped, very
pointed at both exti-emities ; tail short ;
colour sparkling gi'een. The eye-speck
is so delicate that it may be easily over-
looked ; but when the creatm-e is dried
upon a plate of very clear glass, both the
eye and the double filament are readily
seen, and it may be preserved as a per-
manent microscopic object, xvm. fig.
47 represents a cluster of six, each with
its double proboscis. In water-butts, on
ponds, &c. ; it forms the green matter of

Priestley. 1-110" to 1-280", exclusive
of the taU. It was in this species that
M. Weisse thought he had discovered a
form of propagation analogous to that by
ova, but in fact to reproduction by mi-
crogonidia (xx. 15-21). The yoimg
foiTUS so produced, especially in their
aggi-egate state before discharge, re-
semble Uvella Bodo; and M. Weisse
thinks Chlorogoniimi euchlonmi and
Glenomarum tingetis only other stages of
development of the same organism.

Genus COLACIUM. — Eye-speck or stigma single. PUament not detected
in this genus, although, as Ehrenberg remarks, there can be no doubt of its
existence, from the currents which are visible in coloiu'ed water near the
forepart of the body ; still, as these are rather feeble, it is probable that the
organ is but single. Numerous transparent vesicles are seen within the body.
The creatures are parasitical upon Entomostraca and Rotatoria, to which they
attach themselves by means of a pedicle or footstalk, which is single at fii-st.
but becomes ramified by the process of self- division.

CoLACiUM (P) vesieulosum. — Spindle-
shaped, oval, but variable ; pedicle very
short, and seldom ramified ; colom'
sparlding green, with distinct internal
vesicles. Ehrenberg says, " I have again
sought in vain for the red eye (May 23,
18-35), but cannot be satisfied of its non-
existence, ias it is undoubtedly present
in the other species, and investigation
is sometimes unproductive on account
of subordinate circumstances. I have
likewise failed in seeing very satis-
factorily the vibratory organ, notwith-
standing its action is evident enough."

Foimd upon Entomostraca. 1-S60".

C. stentorinum. — Fonu variable, but
somewhat cylindrical, prolonged anteri-
orly into a funnel-shaped process ; colour
beautiful green; vesicles indistinct; pedi-
cle often ramified. The eve-speck is at
one time distinct, at another scarcely
perceptible ; it diftei-s also in position so
widely that sometimes it is close to the
elongated neck, at others near the poste-
rior end. Perty simniscs it to bo alarval
condition of some other being, or merely
a sporozoid. Found upon Entomostraca
and Polyarthra Irigla. 1-1150".

Genus DISTIGMA.— ^s^asio; with two eye-specks. Locomotive organs
not hitherto discovered ; and the presumption is that they do not exist ; none
of the species cither synm. or produce perceptible currents in coloured water.
Movements creeping or crawling, much like those of eels ; form variable, like
that of Lacrymaria; and they approximate to Amctha in other respects,
besides the absence of a Ihibellum. At the foi-e ]iart of the body may be
seen tw(
other

in

tlie aoscnce oi a iiaueuum. jvi me loru jmix m un.- vwi^ • -

,'0 very delicate, blackisli -coloured spots, analogous to the oye-spocks
ir genera. Tlie Distigma> are sometimes confounded with Prolcvs

OF THE ASTASIiEA OE ETJGLEN^A.

545

diffluens of Muller. All the species are exquisite objects for a deep-powered
microscope — for instance, one magnifying 460 diameters. Perty unites this
genus with Astasia, as being indistinguishable from it by any sufficient charac-
teristics.

'DiSTiGMKtenax{Proteus,yL.'). — Larger
than either of the other species ; proteus-
like— at one time greatly distended, at
another as much constricted ; eye-speck
rather indistinct ; coloiu- transparent yel-
low. About LemnfE. 1-240". This spe-
cies Perty regards as merely a larger
variety of Astasia margaritifera, inca-
pable of the same extent of metaholia.

D. Proteus (Proteus^M.). — Smaller than
the preceding ; proteus-like — sometimes
greatly distended, at others constricted;
Blunted at both extremities ; eye-specks
distinct. Amongst ConfervEe. 1-580" to
1-400". This species, saj^s Pei-ty, appears
nothing else than a smaller specimen of
Astasia margaritifera which has lost, to

a greater or less extent, its filaments, and
therewith its power of swimming, whilst
it retains the remarkable peristaltic move-
ments in its internal substance.

D. viridis. — Smaller than either of
the other species; proteus-like some-
times greatly distended, at others con-
stricted ; filled with green granules ; eye-
specks distinct. Length not exceeding
1-570". D. viridis is, in Per ty's opinion, an
incomplete condition of Eiitreptia viridis.

D. planaria. — Small, linear ; proteus-
like, but capable of less distension or
constriction than the preceding ; pointed
at both exti-emities; colourless; eye-
specks distinct. Found by Ehrenberg
amongst Confervas in the Nile. 1-240".

Genus PEUANEMA (Duj.) (XXYI. 13).— Body of variable form, some-
times almost globular, at others distended posteriorly, and di-awn out in front,
or prolonged into a long tapering filament. Movement forwards slow and
uniform. The Peranemce are colourless, but contain in their diaphanous
substance granules and vacuoles. The lobes they send out in their frequent
and remarkable changes of form are, unlike those of the Amosbce, covered
with an integument. Found ia stagnant marsh -water, chiefly on the surface
of dead plants. I suspect Ehrenberg has described a species (P. protracta)
of this genus under the name of Trachelitis trichojyhorus.

ponds at Bern. 1-1625" to 1-1300". Perty

could not discover the plaits or folds,
and states that the filament is double
the length of the body. Movements
very active.

P. virescens. — The animalcule so named
occm-red in tlie water of the Seine, was
green, semi-fliud, and changed fonn most
rapidly, like ^xiAmocba. 1-8G0" to 1-520".
Requires further examination.

Genus ZYGOSELMIS (Duj.) (XXVL 12 a, 6).— Animal of variable form,
swimming by means of two equal flageUiform filaments, which are constantly
in agitation. Zygoselmis, says Dujardin, is distinguished from Disehms by
its contractility and its variability of foiTU ; but such a distinction is surely
insufficient.

Pekanhma protracta. — Oblong, soft,
dilated posteriorly, much extended an-
teriorly. 1-838" to 1-370". Its figure
undergoes changes by the movements of
its contents. A trace of a red stigma
often discoverable.

P. globidosa (xxvx. 13). — White or
pale-gi'een, nearly globular, more or less
extended anteriorly, with obUque plaits
on its surface. In the Seine, and in

Zygoselaus tiehidosa (xxvi. 12 a, b). —
Colourless, sometimes globidar, at others
top- or pear-shaped, with numerous con-
tained granules. 1-1300", with two fila-
ments of equal size and length. Un-
common; found with Lemna; the changes
of form proceed slowly.

Z. inaqualts (Perty). — Colomless, hya-
line; one filament rather stouter than

the other ; both proti-uded in fi-ont. Ca-
vity sometimes filled with cleai- green
corpuscles, which frequently assume op-
tically a red hue. Changes of figure
slow ; movements sluggish. Distin-
guished from Z. iiebulosa by the inequa-
lity of its filaments. 1-840".' The assigned
distinction between this and the other
species appears to us insufficient.

_ Genus HETERONEMA(Duj.) (XXVL ll)._Body of variable form, oblong
irregularly dilated postenoriy, having a fine flagelliform filament, and a second

2 N

546

SYSTEMATIC HISTOKY OF THE INFUSORIA.

thicker trailing one acting as a retractor. This genus, hy possessing the two
filaments of different characters and office, approaches the Heteromita and
Anisonema, from which, however, it is distinguished by its contractile, ob-
liquely striated integument.

Heteronema marina (xxvi. 11). — narrower in front, obliquely and closely
Body oblong, iiTegularly dilated behind, striated. Length 1-434". In sea-water.

Genus POLYSELMIS (Duj.) (XXVI. 7).— Animal oblong, of variable form,
swimming by means of several flagellifonn filaments which arise from its
anterior extremity. The single Infusorium I have found possessing these
characters resembled an oblong Euglena rounded at each end, with an anterior
longer moveable filament, sm-rounded by three or four veiy fine shorter ones.

PoLYSELMis viridis (xxvi. 7). — Elon-
gated, rounded at each end ; more or less
dilated and folded in the middle 5 green.

with a red eye-speck. 1-650". Found in
a glass of marsh-water containing Lemna,
which had been kept several months.

Genus EUTEEPTIA (Perty) (XYIII. 53-55).— Like CJilorogomum, Zygo-
selmis, and Dinema, has two fiilaments. It has besides the form of an Astasia,
but its figure is constantly varying as it swims, and it has a red stigma.

This and the following genus constructed by Perty are very imperfectly
characterized, and in our opinion have slight claim to generic independence.

EuTHEPTiA viridis (xvni. 53-55 ; xxx.
18-19). — Green, with hyaline corpuscles,
but sometimes quite coloiu-less. A va-
riety thick and roimded posterior, with
the outline of Amblyophis, only presented

a crawling movement, and not the power
of swimming. Length, when extended,
1-240". Among Lemnae. A variety, K
unifilis, has only a single flabeUiun and a
faintly marked stigma.

Genus DINEMA (Perty) (XIX. 17). — Filaments two ; one projected in
advance, the other trailed behind. Body small, saccular, veiy contractile, and
destitute of chlorophyll.

Dinema griseoluni (xrx. 17). — Body
fiUed with grey molecules. Movements
sluggish, and particidarly so the rotation
on its long axis. Filaments about equal in

dimensions. 1-250". Bern. In ponds, &c.

D. pusillum. — Colourless, with few in-
ternal gi-anules. Veiy conti'actile, and
changeable in figure.

FAMILY DINOBEYINA. I

(XXII. 42, 48, 49.) »

The animalcules of this family are distinctly, or to aU appearance, poly-
gastric, and ^ furnished vsdth only one aperture to the body; hence, Uke
polypes, they can have no tnie ahmentary canal. They are possessed of an
external case or sheath, and have the power at will of changing tlieir fomi,
but are without appendages, except one species of Dinobryon, which has a
simple filiform proboscis and a delicate red spot at the anterior portion of the
body. The nutritive apparatus is obscure and undefined. The lorica is of the
form of a little pitcher (urceolus), to the bottom of which the very contractile
Euglena-like creature is attached. Two genera only arc knoAvn.

Genus EPIPYXIS (XXII. 42).— The characteristics of this genus are
mostly of the negative kind ; it wants the eye, and is attached. The most
evident animal character possessed by the species is the funnel-shaped onfice
at its anterior extremity. The soft or pulpy body is lodged withm a dehcate
membranous (not siUcious) lorica, usually affixed by a pedicle or foot.

Stein presumes Ejpipyxis to be merely a younger condition of Dinobnjon,
with which it occiu-s frequently in company. Besides this, the peculiar ceu-
like nucleus occurs alike in EpipyiX-is and in Din. Sertulana.

OF THE PROTOZOA.

547

Epipyxis Utn'mlus (xxii. 42). — Small,
conical, and pitclier-liie, filled with yel-
lowish granules ; attached by a pedicle.

The figure represents a group of several
attached to a portion of Conferva.
1-640".

Genus DINOBETON (XXII. 48-49).— Distinguished from the preceding
genus by possessing an eye-speck and freedom of motion. The lorica also is
larger and looser around the body of the creatui-e. Reproduction takes place
by gemmae, which do not separate from the parent ; hence a shrubby, forked,
and polype-like cluster is produced.

DiNOBBYON Sertularia (xxn. 48, 49).
— Lorica (sheath) large, slightly excised
and dilated at the mouth, but constricted
above the base or the attached extremity.
This animalcule is readily overlooked, by
reason of its crystalline lorica, and often
nearly coloiu-less body ; by a patient ia-
vesti^ation, however, the little colony
may be perceived rolling along, and ad-
vancing in the field of view. Within
each lorica a pale-yellow aninialcide may
be noticed, in fonn somewhat resembling
the young of Chlorogonium or of Euglena
viridis. The creature is able to contract
itself into a roimded mass at the bottom
of its case, or it extends itself to the
mouth of the lorica, but not beyond it.
A red speck occurs at the anterior part
of the body, from which a single thread-
like filament is protruded beyond the
sheath. The vibrating filaments of the
several members of the colony propel it
through the water like so many paddles.
In bog-water. Length of animalcule

1-570", cluster 1-120". Stein in the
course of his researches met with a spe-
cimen of Dinohryon Sei'tularia which he
likens to a Euglentform being, living m
a crystalline goblet-like sheath, much
like that of Vaginicola crystallina or of
Cothurnia imherbis. The sheaths grouped
on a stem are only mechanically imited
together, and are under no circumstances
developed by progressive gemmation from
the hiadmost one, asEhrenberg supposed.
Each being has a cleai', homogeneous,
discoid nucleus near its base, containing a
centi'al nucleolus.

D. (?) sociale. — Small, enveloped in a
shell of a simply conical shape, truncated
at the mouth. Developed in the form of
a shrub-like polypary. In fresh water.
1-860", cluster 1-280".

D. gracile. — Less branching (fruti-
cose), lorica slightlj^ constricted at the
middle, aperture trimcated. Animalcule
1-2080".

OF THE GROUP PROTOZOA (p. 199).

In the arrangement pm-sued in the first part of this work the Protozoa foUow

the Phytozoa, and are primarily divided into two chief subsections viz.

Rhizopoda and CiUata. These wc shall treat as two groups of Infusoria
divisible into a few subgroups, and, commencing Avith the Rhizopoda, shall
treat systematically, first those beings properly called so, and afterwards, as
subgroups, the Actinophryina and the Acinetina. The Ciliata and their divi-
sions will follow next.

GROUP II.— RHIZOPODA (p. 201).
(Plates XXI.-XXIII.)

i This term and its synonym Pseudopoda are derived from the leading charac
tenstic of the class, viz. the variable processes or false feet which serve as their
locomotive organs. The former appellation is more in vogue, but its extent

2 N 2

548

SYSTEMATIC HISTOEY OF THE HTPTTSOBTA.

of signification is ill-defined. Some would apply it to the whole collection of
animalcules composed, as far as their organic material is concerned, of the
self-same simple homogeneous sarcode, whether this exist naked, as in the
Amoebaea, or whether enclosed mthin a simple single-chambered shell, as in
the Monothalamia, or in a many-chambered or compoimd one, a-s in the Poly-
thalamia or Foraminifera. Siebold extends to the Rhizopoda, as a class, this
wide signification. Others, and among them Ehrenberg, would so far limit
it as to assign to it only the naked Amoebaea and the monolocular Arcellina.
Indeed, the last-named aiithor holds the opinion of an actual difference in
organic nature between his presumed Polygastric Pseudopoda and the Pora-
minifera or Polysomatia. Dujardin adopted the peculiar course of rejecting
the Amoebaja from the Rhizopoda, which in his system included both mono-
locular and multilocular forms. In our general history of the Rhizopoda
(p. 201), we have used the term in its widest signification, to include naked
monolocular and multilocular beings ; but, in order to keep this systematic
portion of our work within moderate bounds, we shall here give only the
descriptive account of the Amoebaea and Arcellina. Were another reason
required than that assigned for this proceeding, a strong one might be found
in the fact of the approaching completion of an elaborate work on the Pora-
minifera by Professors "Williamson and Carpenter, who are so well known for
their extensive acquaintance with this class of organisms.

Families: — 1. Amoebsea ; 2. Monothalamia (Arcellina) j 3. Polytha-
lamia (Foraminifera) ; 4. Actinophryina j 5. Acinetina.

FAMILY I.— AMCEB^A oh MICEBIFA.

The Amoebsea present the simplest form of organic life, and are typically
represented by a microscopic particle of ' sarcode,' or muco-gelatinous organic
matter, possessing within itself the power of gro^\i;h, of assimilation of ex-
traneous substances, of movement by means of irregular and ever-changing
ofishoots from itself — " variable processes," — and capable of multipHcation by
the severance of portions of itself, and probably of development by iatemd
germs or gemmules. They present no definite, constant figure, although it is
possible to distinguish different Amoebaea by the more frequent outline they
exhibit, or by the length or figui-o of theu' pseudopodes. The general opinion
is that the sarcode of which they consist is naked and homogeneous ; but
Auerbach (see ante, p. 205) has advanced the statement that they are all en-
closed within an integument. A movement of graniiles is perceptible, espe-
cially along the margins of the variable processes. A nucleus with a nucleolus is
believed to be generally present ; vacuoles are almost always distinguishable ;
and one, two, or even more contractile vesicles have been seen in some speci-
mens. There seems evidence of the process of encysting taking place under
certain conditions. Amcebiform beings are not nccessaiily of an animal nature ;
for some have latterly been proved to occur ia the cycle of development of some
of the simplest plants. Ehrenberg described Amcebaja as polygastric ani-
malcides, having a mouth but no alimentaiy canal, and moving by variable
processes, produced from any part of the body indiflferently. He observed
vacuoles (digestive sacs) in aU, and self-diWsion in Ama;ba diffiwns. The
AmcebfEa are organically related to the ArccUina and Foraminifera, from
both of which groups they differ by being naked, or unenclosed in a shell
(see p. 234).

Only one genus is distinguishable, viz.

Genus AMOEBA, which is therefore represented by the description of the

OF THE AM(EBiEA OK AMCEBINA.

549

family. The following species, however, are distinguished, although it is hard
to define specific form in such variable creatures.

vacuoles, and some neai-ly opaque gi'a-
nnlar bodies, at the centre. 1-400'' to
1-300".

Amceba Princeps (xxi. 4). — Ooloiu-
pale yellow, processes numerous, of a
cylindrical outline, with thick, roimded
extremities. Its figure when in a passive
or non-reptant condition is globular ; but
this character is of no specific value, the
natural tendencj'^ of any similar semi-
fluid, mucous particle being, by the
force of cohesion, to assume such a fonn.
Amongst Naviculce and AlgiB in fi."esh
water. 1-140" to 1-70".

A. verrucosa. — Smaller than the last;
coloui'less ; processes globular, ovoid, of
a wart-like appearance. Motion sluggish,
like, indeed, all Amoeba. Never exceeds
1-240". Amongst aquatic plants.

A. diffluens. — Coloiu'less ; expands into
a filmy form and throws out processes
which are longer than those of A. verru-
cosa, and rather pointed at the ends.
This species is a very interesting object
under the microscope : at times it re-
sembles a turbid lump of jelly-looking
matter, at others a transparent gelati-
nous film, with nmnerous outstretched
processes slowly protruded at one part
and withdrawn into the general mass at
another, but so acted on as to sen^e to

firoduce a very slow onward movement,
ts movements may be compared in ap-
pearance to those which may be imagined
as exhibited by a many-footed animal
tied up in a sack. Usual size 1-300".
Common amongst LemnEB.

A. radiosa (xxu. 1-3). — Colourless;
smaller than A. diffluens ; processes nu-
merous, long, slender, pointed, disposed \a
a radiating manner. When contracted, it
resembles A. diffluens in its globose figm-e.
Colouring matter is readily taken into
its substance. In bog-water. 1-240".

A. longipes. — Very small ; processes
very long, one of them often four times
the length of the body ; acute and hya-
line, without expansions. 1-2500". CiLX-
haven, in the sea.

A. Rossclii (Duj.). — Diaphanous; pro-
cesses numerous, some very obtuse, others
digitate, and others also pointed or
jagged. 1-130". Large vacuoles occur
about the middle of the body, loolriug
like large globules.

A. marina (D.). — Filled with granules
at the centre ; diff'ers from A. diffluens
only in its dimensions and habitat, i. c.
the sea. 1-200".

A. Glcichenii (D.). — ^Varies from a glo-
bular to a very long-oval figure ; divitling
into two or three lobes on one side;

A. midtiloha (D.). — This may be but a
vai'iety of A. Gleichenii, but deseiwes
pointing out, as much fi-om the circum-
stance of its habitat as fi-om its form.
1-1300". It seems softer than other
species, and moves actively, emitting
fi'om its border in various directions ten
or twelve roimded lobes, which give it a
most irregular figure. It was found in
an infusion of meal which had been kept
nearly two months.

A. Limax (D.) (xxn. 4-6). — Diapha-
nous, roimded on each side, more or less
globose, and but slightly lobed; glides
along in a nearly straight line ; contains
very distinct granules, and a veiy clearly
marked vacuole. Foimd in Seine water
kept for eight months. It may be but a
more advanced degree of development
of the preceding, or of the following
species; its greater faransparency, how-
ever, and its semi-fluid consistence, seem
sufficiently distinctive. 1-260" to 1-800".
Auerbach suggests that this species is
only a young foi-m of A. Princeps.

A. Guttula (xxii. 6). — Diaphanous,
orbicular or ovoid ; glides in a straight
com'se, and contains very distinct gra-
nules. This is one of the most common
species, but may easily escape notice on
account of its gi'eat ti-ansparency, the
simplicity of its form, and the slowness
of its movements. In river- or marsh-
water, kept for some time, contaiuing
plants. 1-520" to 1-890".

A. lacej-ata (D.).— Symmetrical, ru-
gose, plaited, and granular, rather dia-
phanous, with broad expansions, looldng
membranous at the base, terminated by
several tapering toni points ; one or more
evident vacuoles. 1-2800" to 1-890". In
pond- water.

A. hrachiata (D.). — Globular ; semi-
transparent, porous and tubercular, with
foiu- to six very thin long and cyliu-
drical_ expansions, straight or flexuose,
sonuitimes bifid or branching. In animai
infusions. 1-190".

A. crassa (D.). — More or less rounded
thiclc ; contains numerous gramdes ; ex-
pansions roimded, numerous, not very
prominent. 1-880" to 1-520". In the
water of the Mediterranean.

A. ramosa (D.).— Globular or ovoid •
granules very numerous : expansions nu-
merous, of nearly equal size, rounded at

650

SYSTEMATIC HISTOUY OF THE INi'USOEIA.

the extremities, of the same length as
the body, and mostly branched.

Other varieties of these peculiar beings
are referred to, but not specially described,
by Dujardin ; for one, however, he pro-
poses the name of Amoeba inflata.

A. qiiadrilmeata (Carter). — 1-350".
Ml". Carter has given this name to a
supposed new species {A. N. H., 1856,
xviii. pp. 243, 248), of which he gives a
diagi'am, but no specific description.

A. latei-itia (Fresenius). — Rounded or
oval, or drawn out at one end and rounded
at the other. Processes thin, finely
pointed; points veiy numerous; coloui-
of a brick-red, becoming browner after
death. In water at Walldorf with *S^i-
rotcenia. 1-20 to 1-10 mUlim.

A. actinophora (Auerbach) (xxrt. 12-
18). — When without processes, its form
is more or less globular ; and even when
pseudopodes are protruded, the figure is
usually not much altered, those pro-
cesses being thin and spicular with
pointed ends (fig. 13), though they do
not exceed in length more than 1 i the
diameter of the body. This species is
remarkable for the number of crystalline
particles found in its interior, and for
the processes never being entered by the
granules of the interior of the body.
Auerbach believes that the Actino-
phrys viridis of Ehi'enberg is probably
no other than a large specimen of this
Amoeba. It is closely allied to A. bilim-
bosa, but is smaller, its surface smooth,
its processes radiating and simple, not
forked, its envelope thinner : it contains
the peculiar crystals, and has no starch-
globules as seen in the latter. 1-110"' to
1-70"'. In water at Breslau.

A. bilimbosa (Auerbach) (xxn. 7-11,
20-23). — Figure more or less globular
when processes absent or few ; pseudo-
podes vary, being either wide and laminar
with a spinous or dentate terminal mar-
gin, or elongated and tubular. 1-50"' to
1-35"'.

A. porrecta (Schultze) (xxi. 3). — Hy-
aline ; processes numerous from all sides
of the in-egularly-shaped mass, from
eight to ten times longer than the latter,
divergent like so many fibres, with in-
tercommunicating branches. Fissure
very changeable and rapidly so ; remark-
ably locomotive. The tine gi-anules seen
to circulate through the processes. In
fresh and salt water.

A. globularis (Schultze) (xxi. 2). —
Graniilar, delicate, yellowish-brown,
central portion surrounded by a hyaline
cortical lamina, from which the short,
stumpy processes are very slowly pro-
ti'Lided and withdrawn. Most of the
processes are also remarkable from their
rounded tnmcate ends being terminated
by a reti-actile spine. Ancona.

A. polypodia (Schultze). — Processes
numerous, long, slender, -mXh. rounded
or tnmcate exti-emities, and hyaline ;
movements tolerably active. Lagoon-
water, Venice.

A. Sclmltzii (xxi. 1). — ^A species indi-
cated but not named by Schultze; to
distinguish it, we have applied to it
that eminent natiu-alist's name. Central
portion gi-anulai' ; suiTounding lamina
hyaline ; no granules enter the interior.
Processes short, tuberculai-, with rounded
exti-emities. Possibly the same as A.
verrucosa (Ehr.). In long-kept water
from Ancona.

Swpplementary Genera, or Subfamily of AMffiBINA.

Gentis COEYCIA (Duj.). — An Amcebiform being, covered by a very expan-
sible, elastic, flexible membrane or sac, which becomes folded in differeiit
directions by the movements and contractions or expansions of the animalcule,
— the whole organism sometimes, after it has several times turned on itself,
looking like a folded piece of Unen. The membrane remains distinct after the
animalcule is torn by needles, and the sarcode particles evacuated. Tlie latter
contract themselves into little balls, and, by the property of vacuolation, become
hoUowed by Little cavities in larger or smaller numbers. The contents con-
sist, besides sarcode, of granules, vacuoles, and foreign particles ; the tivsi-
named move in cm-rents from one part to another. The expansions arc not
pushed forward, nor do they glide along the surface of reptation Bke those ot
ArceUina or of naked Amoeba: ; they proceed from various points of the gcner
mass or body, and seem to serve rather to change the centre of gravity than
io ivomish. a, poiyit d^appui. 8-100"' to 20-100"'. .

The name is suggested by the membranous envelope, whicli prcsen-es inc

OF THE AECELLIITA.

651

animalcules from being di-ied up during the alternations of drjTiess Avith
moisture they are exposed to by theu- habitat in mosses. They are procured
by lightly pressing the Jungermannite, moistened by the rains of November
or December, or after they have been preserved a little time in vrater.

This, as Dujardin remarks, is evidently a new genus, intermediate be-
tween the naked and the loricated Ehizopoda, and standing in a certain
relation with the NoctiluccB. {A. S. N., 1852, vol. xviii. p. 240.)

No species named.

Genus PAMPHAGUS (Bailey). — An Amcebiform being, covered by a deli-
cate elastic integument, which, although it presents astonishing changes of
form, and offers a certaia amoimt of resistance to internal and external pres-
8ui-e, yet admits of the animalcule transfixing itself upon any denser thin
portion of matter without any apparent damage (p. 220).

They connect, says their discoverer, " the genus Amceba with Difflugia,
agreeing with the fii-st in the soft body -without shell, but diffei'ing in having
true feelers or rhizopods confined to the anterior part of the body," or to the
region of the mouth, as in Difflugia. A specimen of Pamphagus, we may
remark, is equivalent to a Dijfflugia without a true shell and with no ex-
traneous matters to thicken and strengthen its covering. Dr. Bailey met
with these animalcules in a vivarium, into which " bits of boUed beans and
potatoes had occasionally been introduced as food for other animalcules,"
and numerous starch granules were found in their interior. He also repre-
sents it as having a mouth, and, being an adherent of Ehrenberg, as polygas-
tric ; but the mouth so described was the orifice of the sac through which
the pseudopodes were protnided, and therefore the homologue of the foramen
of monothalamous shells.

This genus is evidently very closely allied to Goryda (Duj.). The only
difference of moment is that in the latter the expansions of the sac proceed
from any part of the sui-face, whilst in Pamphagus its discoverer describes
them as given off only from one spot at the anterior end.

FAMILY II.— AECELLINA (Ehr.) (Pt. I. p. 201 et seq.)
(XXI. 6-17.)

Arrwebce invested with a single-chambered cell or lorica, having also but
one opening, mouth, or foramen. The animal substance or sarcodfe contained
within the shell is indistinguishable from that of the naked Amceba;, and is
not more organized. The form of the pseudopodes given off from around the
mouth of the shell are to some extent employed in defining species ; but the
size and conformation of the shell and of its opening arc of much more im-
portance systematically.

Ehrenberg instituted this family for aU one-chambered llhizopodous shells
which, in his belief, were of a silicious composition, and rejected from it
some similar shells which were of a calcareous character. This distinction
however, is based on erroneous notions (p. 219) ; and naturalists now concur
m bringing together all unilocular Ehizopoda into one group, under the name
of Monothalamia.

The Arcellina were represented by Ehrenberg as polygastric animals
with an alimentary canal, and enclosed by a lorica, through the sincle
opening of which they extended their variable processes. He also described
digestive sacs, but was unable to discover either their mode of renroduction
or their multiplication by fission or gemma).

Only four genera of ArceUina were emimorated by Ehrenberg; theii- chn
racters and mutual relations are shpwn in the following tabular view :--

652

SYSTEMATIC HISTOET OF THE INFU80KL4..

Changeable processes f Lorica spherical or tun-like Difflugia.

radiant, generally Lorica a flat spiral Spirillina.

numerous [ Lorica discoid or shield-shaped Arcclla.

Changeable processes broad and unbranched Cyphidium.

The genus Spirillina is a very exceptional form ; it has a spirally-coiled
shell, apparently porous throughout, hke one of the Foraminifera, and hke
them, too, a marine habitat. Its only affinity with the Ai-ceUina, according
to Ehrenberg's account, is the sUicious natui-e of the shell ; but even were
this established, it would not exclude it from the Foraminifera, among which
silicious testae are known. Of Cyphidium little infoi-mation exists ; and
Ehrenberg's account is by no means satisfactory. The same may be said of
the figures he gives of it.

Dujardin divides the " Ehizopodes," excluding the Amoebfea, into two sec-
tions, according to the form of the variable expansions. The first section cor-
responds to the family ArceUina of Ehrenberg, and comprehends those species
provided with short thick expansions, rounded at the extremity. Such are
the Diffiugice, j)ossessing a flexible membranous lorica, without visible tex-
ture, mostly of globular form, from the aperture of which the expansions
radiate : such, too, are the Arcellce, having a discoid lorica, flattened on the
side along which they move (the plane of reptation), where is a central
round opening, from which the expansions proceed, the latter lying thus be-
tween the shell and the surface along which it glides ; the lorica, moreover,
is brittle, and often reticulated, or areolated. The second section, much
larger, comprises beings of every variety of form, and having veiy munerous
filiform expansions, ending by very fine extremities. Of these varieties he
makes three tribes ; the first distinguished from the Difflugice only by the
slender character of the expansions, excej^t that in one genus, Trinema, the
opening is lateral ; the second, represented by the genus Euglypha, having a
lorica beset with tubercles, or areolae, disposed spirally ; and the third by the
genus Oromia, having a spherical membranous shell, and very long and
branching expansions.

The remainder of the " Rhizopodes," as described by Dujardin, are com-
prehended in the Polythalamia by other authors. Of these he constitutes two
tribes, — one represented by the single genus Miliola, which, like Gromia and
the examples of the first tribe, has but a single large opening in its
lorica for the escape of the expansions ; the other by several genera, aU
of which give off numerous filiform expansions fi-om many distinct pores
(foramina) of their shells, and hence called Foraminifera.

Siebold included the fii-st and second divisions of Dujardin's class Wiizo-
pocla in his group of ArceUina.

M. Schultze framed the division of the Monathalamia from the sfnioture
of the shells ; but he admitted amongst them the genus OrhuJina, which
possesses the very exceptional chai-actcr of having nimicrous pores to its
shell, instead of a single opening. The three families instituted were: —
1. Lagynida; 2. Orbulinida; 3. Comuspirida (see p. 241). The first-named
family corresponds most nearly to Ehrenberg's Ai-cellina, althoiigh it con-
tains several genera usually described in liistories of the Foraminifera, and
omitted by the Berlin natui-alist. The following are enumerated ■.—Arcflhi,
Difflugia,' Cypliidium, Trinema, Euglypha, Gromia, Lagynis, Ovulina (d Or-
bigny), Fissurina (Reuss), Squamidina, and the doubtful genera of Sclilum-
berger — Lecquereusia, Cyp>hoderia, Pseudodiffliigia, and Sj)henoderia . Ine
genera Lagynis and Sqtiamulina are two new ones formed by Schultze him-
seK. It will make this history more complete to introduce these new genera

OF THE ABCELLINA.

553

of Lagynida, as weU as the interesting Cornusjpira described by Schnltze. Of
Fissurina we have no details. ^
Dr. BaHey, of New York, adds another new genus to the Monothaiamia,

under the name of Cadium.

Genus DIFFLUGIA.— SheU of one chamber (luulocular) with a single
aperture, usuaUy of a more or less spherical or ovoid shape, but sometimes
more elongated and clavate, or pitcher-shaped ; thin, opaque, of a dark
oUve or brown colour, in general, when occupied by the living organism, but
when empty, hyahne ^d coloiu-less. The surface of the sheU is either smooth
or sculptured, and -occasionally armed with spine-like processes. In a lew
species, D. proteiformis, D. acuminata, and D. gigantea, the envelope does
not acquire even the usual homy consistence, but is soft, and becomes
strengthened by the adhesion of foreign pai-ticles of silex and other matters,
which give it a rough, irregular appearance. The aperture or foramen
varies in figure and size, and furnishes valuable specific distinctions. The
pseudopodes are characterized as being cylindrical, not much elongated, and
obtuse or rounded at the extremities.

D. areolata. — Lorica and foramen as
va. the preceding, but the spines defi-
cient.

D. detiticulata. — Ovate, oblong, smooth ;
foramen with twelve dentations.

D. Lagena. — Clavate, or of the form of
a bottle ; smooth, without reticulations ;
margin of opening entire.

D. lavigata. — Ovate, oblong, smooth ;
foramen -with eight dentations ; ap-
proaches D. denticidata.

L). striolata. — Ovate, oblong, delicately
striated longitudinally j foramen with a
dentated border.

D. Bructeri. — Ovate, surface rugose ;
the end presenting the aperture rather
attenuate but ti'imcate ; margin of aper-
ture entire. 1-1050". On moss.

D. cancellata. — Oblong, obtuse; sur-
face beset with imperfectly rounded cells,
5 to 6 in 1-2500" ; aperture narrow, en-
tire. 1-1040". On moss.

D. ciliata. — Ovate, sui'face areolar ;
each posterior areola furnished with a
cilium or cirrluis ; constricted towards
the foramen, which has 10 to 16 denti-
culations. 1-930". Common in Her-

DrFFLTJGiA proteifwmis. — Ovate, sub-
globose, covered by a coating of minute
grains of sand, and either of a deep ohve.
Black, or greenish colour. Processes
hyaline, from 1 to 10. 1-240". Among
OsciUatoriaB.

D. oUonga. — Oblong, ovate, or orbi-
cular, smooth, and of a brownish colom- ;
processes fewer and stouter than those
of the preceding species. Among Oscil-
latorise, &c. 1-200". Surface irregu-
larly reticidated.

D. acuminata. — Oblong and rough,
with minute grains of sand ; posteriorly
pointed ; processes hyaline. 1-70".

D. Enchelys (xxi. 19 «,/). — Oval ; co-
lomiess ; translucent and smooth, roimd-
ed dorsally; processes ti-ansparent,
slender and small ; apertm'e lateral. This
is the smallest species of the genus.
1-30"' 1-15"'. In stagnant water. Du-
jardin refers it to his genus 2'nnema.

D. Ampulla. — Oblong, club-shaped, ele-
gantly marked by an oblique series of
dots (puncta) ; hvaline ; foramen ovate.
1-680". AtSakhiu-g.

D. spiralis (Bailey). — Sub-globose, mi-
nutely gi-anulated: upper smface im-
equal, with a spiral line of two or three
turns. Variable processes numerous,
constantly changing position, hyaline.
1-080". Beriin and United States.
Frcsenius reraarlcs that some large spe-
cimens are met ^vith coated with coarse
particles, like D. proUdfurmis, instead
of the usual finely reticulate lines. It
attains, he says, in size to 1-7'".

D. acanthophora (xii. 64). — Ovate,
oblong, loosely areolated ; foramen den-
tated; armed posteriorly with three or
fom* spines (acidei).

cynia.

1). seminulum. — Shorter, ovate, brown,
surface with narrow and small areoLne ;
aperture wide, very fiuelv dcnticidated
or entire. 1-2500" "to 1-1^50". On moss
and stones.

T). coUaris. — Narrowed like a neck be-
hind the aperture ; straight, attenuate,
pyi-il'orm or sub-clavate ; surface irregu-
larly cellular ; cells small, but of equal
size, except about the nock, where they
are smaller; nperture entire. 1-840'"'.
About roots of trees.

654

SYSTEMATIC HISTOEY OF THE rNFXJSOElA.

D. Dryas. — Ovate ; aperture entire,
truncate ; sm-face marked with longitu-
dinal lines of ovate cells, which decrease
in size posteriorly. 1-1170", On roots
of trees.

D. oligodon. — Smooth, oblong, sub-
cylindrical; apertiu-e with eight strong
denticulations. 1-1000". This spacies
and the two following found in Kur-
distan.

D. reticulata. — Ovate, sm'face marked
hj a net- work of minute cells ; aperture
simple, large. In its interior are nu-
merous particles like aggregated buds;
the margin of the foramen is sometimes
dentate. 1-880".

D. squamata. — Ovate, with large loose
areolae, looking like scales (squamre) ;
aperture denticulate, truncate, contracted.
1-1450".

D. spirigera. — Pyriform, smooth ; neck
distinct, cylindrical, ti'uncate; orifice
large, entire; opposite end tui'gid; round-
ed. The surface presents foui* spiral lon-
gitudinal lines. 1-36"'. Bavarian Alps.

The first of the appended species is
from Duiardin, the others from Schlum-
berger (Ami. des Sciences Nat. 1845,
p. 254) :—

D. globulosa (xxi. 10). — Brown, glo-
bular, or ovoid, smooth. 1-260" to
1-105". Near Paris.

D. depressa. — Diaphanous, ovoid, de-
pressed, resistant ; iia surface divided by

slight fissures (lines) into numerous
small and irregular polygonal sections.
1-220". Aperture with an uneven mar-
gin. In springs in the Vosges.

D. gigantea. — Greyish brown, rough,
as if strewed with particles of sand,
ovoid, elongated, and contracted an-
teriorly. 1-325" to 3-325". It ap-
proaches D. protdformis, but differs in
its more elongated form, in being con-
tracted anteriorly and almost pynform,
sometimes depressed, and lastly in its
greater size : margin of aperture uneven.

D. tncuspis (Carter). — -Processes occu-

Eied by granules, gi-eenisb ; testa ovoid,
ttle incrusted ; its foramen tricuspid in
form, or of trefoil shape {A. N. H. 1856,
xviii. p. 247). Freseniua appeal's to have
met with this form, but considers it only
a variety of D. ohlonga. 1-320".

D. ? marina (Bailey). — Shell silici-
ous (?), ovoid or lagenoid, with a con-
tracted neck and circular aperture ; sur-
face divided by oblique lines into quadii-
lateral spaces. jV 1-1000", diam. 1+ of
1-1000".

A single specimen was fomid in sound-
ings taken from a depth of 2750 fathoms,
which had been cleaned with acids.
This resistance to acids induced Dr.
Bailey to consider the shell silicious,
but we now know that chitinous shells
are equally unaffected. The discoverer
doubted its being a Difflugia, on account
of its maiine habitat.

Genus SPIRILLINA. — Lorica tubiilar, silicious (?), rolled in a spiral
manner, like a Planorhis. ■ It is aUied to Diffiugia by its silicious lorica (for
acids have no action on the shell). This genus probably agrees with the
Spirulina of Bory de St. Vincent; but the latter name has been othenvise used
by Ehrenberg to designate a genus of Polythalamia.

SpiniLLiNA vivipara (xi. 37). — Shell
porous, convoluted as a circular, spiral,
horizontal tube, hyaline and smooth.
Young loricse may often be foimd con-
nected with it. In the sea — Vera Cruz,
Mexico.

The form of this species recalls that
of many undoubted Polythalamia, whilst
it has no fellow amongst the Infusoria.
Ehrenberg has likewise represented ap-

parent dots or pores on its surface, like
those through Avhich the filiform pro-
cesses of Polythalamia are protruded;
and the only reason implied in Ehren-
berg's account for reckoning it among tlie
Polygastrica is its silicious shell: it is,
however, most probably chitinous. It
^vill be noted that Ehrenberg is inclined
to believe it viviparous.

Genus ARCELLA (XXI. 7-9, 15).— Variable processes, numerous and
hyaline; single processes cleft into many, and expanded in a radiating
manner ; lorica flattened, sliicld-likc. The lorica varies mucli in structure m
the different species. Eor instance, in A. vuJyaris it exhibits regular and
dcUcate facets ; in A. dcntata the facets are large and crystalline ; in A. acu-
leata it is beset with spicida ; and in A. hyalina it is homogeneous and
clear. Vacuoles are seen filled with coloured vegetable substances ; and m

OF THE AHCELLINA.

555

A. vulgaris and other species a contractile vesicle has been perceived. The
processes are longer, as a rule, than those of Diffiugia, fibrous, and more
branched. The shells are very commonly compressed, and have a discoid
figure ; and in none are they soft and beset with extraneous particles, as in
Diffiugia, but are chitinous and elastic.

" The Arcellce (says Dujardin) seem to differ among themselves by the
intimate stnictm-e of their lorica, which sometimes appears membranous,
at others finely striated, reticular, or with granules disposed in spiral lines.
Some Arcellce have also spinous prolongations from the border of their lorica.
Pressure fi-actures their lorica like a brittle substance. The contained sub-
stance escapes thi-ough the cracks so formed, iu the form of contractile expan-
sions like those of Amoebce. I have seen one larger lobe almost separated,
as if about to become an iudependent being. M. Peltier has observed con-
tact to take place between the expansions of neighbouring Arcellce without
any union being effected, while the processes of the same Arcellce united and
became blended together.

" The lorica in young Arcellce is extremely diaphanous ; and granulations
or striae are to be seen only in those of larger size : hence it may happen, with
respect to some species, that they represent but different stages of existence
of the same animal."

tion ; one-half nearly occupied by the
large foramen. This is a very doubtful
Arcella, and contrary in form to the
character of mouothalamous cells. A
comparison of Ehrenberg's account with
his iigures leads us to believe this sup-
posed species to be no other than a young
Rotalia of two cells (xx. 41), or other
incomplete polythalamous shell.

A. ecor«!s.— Large; hemispherical, not
areolar ; apertm-e roiuid, large, placed to
one side ; entire.

A., lunata. — Subglobose, large ; with
a -wide semi-lunar opening, seated to one
side.

A. Nidus-pendidm. — Ovate-oblouo-
hyalme, loosely areolated; aperture ui
front, oblong, margin entire.

A._ m'!«s.— Hemispherical, depressed,
reddish, mmutely and elegantly ai-eolar:
aperture central, circular.

A. ? Gfo&«/«<5. _ Subglobose : with
oosely reticular lines, appearing gi-anu-
lar ; apertiu-e large, simple. l-7aO" On
moss at Berlin, Potadam, &c.

A gramdata.~0]AQug, hvaline. Has
tJie habitat and size of A. hyalina, with a
granular instead of a smooth sm-face.
1-940' . On moss in Hercynia, &c

A. caudicola.— Ovate, oblong, rounded
at each end, hyaline, very delicately
Jiispid, not areolar ; aperture anterior
round, large. 1-840". Habitat of A
Nidm-pc>ulul„s. In Venezuela, on roots
ot plants, such as ferns, &c.
A. Oke}m (Perty) (xxi. 15).

Abcella vidgaiis (xxi. 7, 8, 9). —
Lorica round and beU-shaped, with a
hemispherical or turgid back; smooth,
but with rows of minute granules ; colour
yellow or reddish-brown. Abundant
amongst Lemnte and aquatic plants.
1-570" to 1-240."

A. aculeata. — Yellowish, hemisperical,
though often mis-shapen, and spinous
throughout, or only around one-half of
the margin ; the shell is not readily de-
stroyed by heat, and is covered with
short spicula. 1-210".

A. dentata. — Membranous ; of a he-
mispherical or polygonal form ; margin
dentated; coloiu" yellow or green.
Amongst Confer\-£E. 1-570" to 1-240".

A. (r") hyalina. — Membranous, smooth,
elliptical or globular, smaller than the
preceding, thin and soft, colourless.
Found in d(5bris at the bottom of pond-
water, along with Cyphidium aureolmn,
&c. 1-1150 to 1-570". The sheU is
not quite symmetrical, one side being
more convex than the other. Aperture
sometimes in-egular. Elirenberg was not
certain that this species is not a Diffiugia.
It is indeed very liice many specimens of
D. Michel ys.

A. Americana. — Oblong ; aperture
small, round, not in the median line.

A. comtricta. — Ovate; slightly con-
tracted about the foramen, which is very
large and to one side.

A. dispheera. — Oblong, almost di-
vided into two by a centi-al coustric-

55G

GENEOALIIISTOEY OF THE INFtrSOJilA.

from it. The lorioa is combustible, and is something like a little die or
stamp, moimted upon a short stem. It is very in-egularly formed, having
protuberances which make it appear four-cornered. The organ of 'locomo-
tion is a broad gelatinous variable process with smooth edges, not unlike
Amoeba verrucosa. Vacuoles have not yet been observed ; modes of propaga-
tion unknown.

tion they might be seen to change their
places." Ehrenberg only once perceived
the locomotive organ of the animalcule,
situated imder one corner, — upon which
it appeared to rest, and that so fhmly that
six out of the eight protuberances of the
die-like lorica were visible at the same
time. In fig. 26 the gelatinous variable
process is seen projecting from beneath
the lorica. Fig. 27 is a young specimen.
1-570" to 1-430".

Cyphtdium aureolum (xxn. 24-27). —
Lorica cubical, with protuberances ; pro-
cess colourless. " In March, 1835," says
Ehrenberg, " I first observed himdreds of
these creatm-es in a glass of water which
had stood throughout the winter, in com-
pany with some specimens of the Mi-
d-astei-ias. Previously to discovering
these, the Amoeba verrucosa had been
abundantly generated, and afterwards
Arcella liyalina. The creatures were in-
active, although by attentive observa-

Genus TEUSTEMA (Buj.). — Shell membranous but resistant, diaphanous,
ovoid elongated, narrower in front, "with a large oblique oiifice placed late-
rally ; expansions fihform, as long as the shell, very thin, and but two or
three in number ; entirely retracted when others are to be pushed out from
another side. The animal is moved onward by theii- alternate protrusion and
contraction. This genus is accepted by Eresenius.

TniNEMA Adnm.= Difflugia Enehelys (Ehr.) (p. 553).

Genus ETJGLTPHA (Duj.). — SheU diaphanous, resistant, membranous,
elongated, ovoid, rounded at one end, terminated at the other by a very
large truncated oiifice, with a dentated margin ; its surface marked by emi-
nences or depressions, in regular obHque series ; expansions filiform, nume-
rous, simple.

Etjglypha tuberculata. — Lorica stri- E. alveolata (xxi. 11). — Lorica with
ated, with rounded tubercles. Termina- regular polygonal depressions in regular
tion of expansions extremely delicate, oblique (sphal) series, bearing spines at
1-295". Found in stagnant ponds. the upper or posterior end. 1-290".

Genus GROMIA (XXI. 12, 16) (Duj.). — Lorica smooth, yeUowish-brown,
membranous, soft, globular, with a small round opening, from which the very
long branching expansions proceed, tapering to very fine extremities. Found
in both salt and fresh water,

Gromia oviformis. — Globiilar, smooth,
aperture sorrounded by a short neck ; ex-
pansions very long, fibrous, branching,
slightly anastomotic, colourless or pale-
yellow, transparent; animal contents
of a yellow or reddish-bro^vn colour;
the processes hyaline, permeated by a
current of granules. Ehell 1-26" to
1-13".

G. Jluviatilis. — Globular, or ovoid,
without a neck ; expansions palmate and
anastomotic. 1-290" to 1-104".

G. hyalina (Schlumberger, A. S. N.,
1845, p. 254). — Globular or rather ovoid,
smooth, soft, diaphanous, colourless ;
foramen round, with a very short neck,
formed by a reflexion of tlie lorica ; ex-
pansions filiform, numerous, very fine,

branching and anastomotic. 1-865" to
1-520". In rivulets.

" Notwithstanding the absence of co-
lour in the sheU," says Schlumberger,
"I arrange this species in the genus
Gromia. In size it also differs from the
other two species. The lorica, being
transparent, admits to view some bluish
globiQes, and a large hyaline glandular
ovoid body, like that iii the interior of
other diaphanous Rhizopodes."

G. DiiJard{iniXSdnAt7.c).—She]l sphe-
rical, ovoid ; more constant in figure than
G. oviformis, colouriess or faint yellow,
with a short neck-likc elongation at the
foramen, or none ; animal content^ dark
sepia-browai ; processes hvnline, with no
moving granules. Dinm. 1-2"'. Ancona.

OF THE ABCEUJNA.

557

Genus LECQUEEEUSIA (Schlumberger).— SheU ovo-globular, or retort-
shaped, rather depressed, membranous, but resistant ; with a wide short
neck, and circular terminal aperture, giving passage to cylindi-ical thick and
obtuse expansions.

This genus approaches Difflugia (Duj.) in the character of its expansions;
but the very different form of the shell, and the position _ of the aperture,
sufficiently mark the distinction between the two. Its distinctness is re-
garded with doiibt by Schultze.

Lecquereusia jurassica. — Shell re-
sistant, diaphanous, grey, of a globular
figure, but rather depressed, with a short
wide neck. Length aoout 1-250" ; breadth
1-315".

This beautifid species is met with on

aquatic plants, in many of the lakes of
the Jm-a chain about Neuchatel. Itg
diaphanous lorica allows its interior soft
hyaline and granular body, strewn with
brown specks, to be seen.

Genus CYPHODERIA (Schlum.). — Lorica membranous, resistant, ovoid,
elongated anteriorly, where it is curved and constricted in the form of a
neck ; surface marked by prominent points in oblique rows ; apertui'e circular,
oblique ; expansions very long, filiform, very fine at the extremity, and simple
or branching.

The oblique disposition of the rows of points, the obliquity of the apertiu'e,
and the character of the expansions, bring this genus into affinity Avith Tri-
nema (Duj.) ; but the constriction, forming a neck, seems sufficiently distinc-
tive between the two. This genus, though admitted by Fresenius, is treated
as doubtful by Schultze.

Cyphoderia jnargaritacea. — Lorica
yellow; the surface is divided into mi-
nute facets, which appear like translucent
points or rows of pearls. Processes attain
twice the length of the shell, and are
simple or branched. Length 1-395";
breadth l-840"to 1-408". Common in the

water of the Vosges with vegetable d(5bris.
The fonn of the lorica varies ; at one time
the neck may be but inadimentary; at
another the posterior end, instead of
being wide and rounded, is conti-acted
suddenly to a truncated apex. Apertiu'e
crenulate.

Genus PSEUDO-DIEELUGIA (Schlum.). — SheU membranous, ovoid or
ovo-globulax, smooth or striped spirally, with a wide round opening, whence
proceed numerous long slender expansions, either simple or branching.

This genus is allied to Diffiur/ia by the form and character of its shell, but
differs from it in the nature of the expansions ; it is admitted as doubtful by
Schultze.

filiform, very long. Length 1-740" to
1-465"; breadth 1-890" to 1-740". Found
near Midhouse.

PsEUDO-DLFFLUGiA ffvacHts. — Shell
bluish bro-\vn, brittle ; surface as if beset
with minute grains of sand, of a more or
less elongated ovoid figm-e; expansions

Genus SPHENODERIA (Schlum.).— Shell diaphanous, colourless, resistant
globular, with a flattened wedge-shaped neck ; surface marked by poly<Tonai
depressions, disposed in regular oblique rows ; aperture terminal, compressed
almost linear. Expansions filiform, very long and attenuated. '

The form of the aperture and of the neck separates this genus from Trinema
and Euglypha, to which it is allied by the structure of its lorica. Schultze
treats it as a doubtful genus.

SpHENODEniA fcM<a.— Lorica as above slender and simple, or branchinir l-fi50"
descnbed, expansions few, very long, to 1-520".

Of all the Rhizopodes I have examined (says Schlumberger), this is the
slowest m its movements and ite expansions the most difficult to discover
I have found it on tufts of moss m marshy rivulets. '^^"vci.

558

SYSTEMATIC HISTORY OF THE INFUSOEIA.

A glandular body and hyaline globules are seen in the internal soft sub-
stance near the posterior end. In moving, the position of the shell may be
perpendicular, or oblique to the stu-face of reptation : the hexagonal depres-
sions are indistinct but large. The shell fractures along the lines of junction
between the hexagons.

Along with the preceding genera, Schultze, as before stated, includes in the
division Monothalamia the new genera Layynis, Squamulina, and Cornu-
spira.

Genus LAGrTNIS (Schultze). — Shell membranous, elastic, retort-shaped ;
body colourless, transparent ; foramen large, but the processes few, very fine,
occasionally branching.

It forms the type of the family Lagynida.

Lagynis haltica. — The ti-ansparent
contents rarely fill the shell, but leave a
space posteriorly, into which they send
processes which converge towards the
summit of the concavity of the posteiior,
roimded extremity. 0 05'". Baltic Sea.

The form of the shell approaches that
of Euglypha (?) curvata, described by
Perty, and foimd in an empty state by
him on the Simploa, at an altitude of
4000 to 5000 feet.

Genus SQUAMULINA (Schultze). — Shell calcareous, plano-convex, or
lenticular ; adherent by the plane surface ; cavity single, one large opening
on the convex side ; no pores.

Squamitlina Icmns. — In-egularly ch-
cular; much flattened; convex portion
thick and smooth, the flat portion veiy

thin and scarcely separable from the ob-

ject to which it adheres. The yellowish
animal protrudes numerous processes
fi'om the excentiic foramen. Largest
diam. 1-26"'. Sea-water, Ancona.

Genus COKNUSPIEA (Schultze). — Shell calcareous, spiral, like a Pla-
norbis shell ; solid or finely porous ; discoid ; symmetrical, i. e. with both sides
alike ; cavity single. One large foramen at the tennination of the spii-al.

CoRNUSPiBA planorhis. — Shell trans-
lucent, brown, without pores; six or
perhaps more turns of spiral seen. Mud
from the coast of Mozambique and
Trieste.

C. perforata. — Finely porous, hyaline,
colourless ; pores cii'cular, becoming gra-

dually larger towards the tennination of
the sphal ; as many as seven tm-ns seen.
On the coast of Mozambique.

D'OrbigTiy's OpcrcuUna inserta is pro-
bably the same foiTU. The SjnriUina de-
scribed by Ehrenberg is somewhat like,
but is probably onlj- a young Miliola.

Genus CADIUM (Bailey) (XXII. 19).— Shell silicious (chitinous?) ovoid;
elongated as a sort of neck, which is bent upwards and outwards, temiinated
by a circular foramen.

This genus was instituted by the late Dr. Bailey, of New York, to include
some empty Rhizopodous shells met -ndth in the soundings taken in the gulf-
stream. (Silliman's Joum. xxii. 1856.)

Cadium marinum (xxii. 19). — Shell
marked by numerous meridian lines, of

which about 12 are visible at once.
Length 2-1000"; diam. 1^-1000".

Sub-group ACTINOPHRYINA. (Part I. p. 243.)
(XXIII. 24-37.)

A 8ub-cl|iss of Rhizopoda having a more constant and definite form, and
furnished with long tapering retractile filaments or tentacles, which sei-ve
as prehensile organs, in the place of the usual variable processes of the class.

OF THE ACTINOPHKYINA.

659

Their movements are excessively slow, and sometimes inappreciable ; and the
tentacles appeal- not concerned in them : conjugation is of very frequent
occurrence.

The genera enumerated in this section are Actinophrys, Podophrya, Tri-
chodiscus, and Dendrosoma. The distinction between the two first-named
genera is denied by Stein, and probably with reason, for the stem of Podo-
phrya is not sufficiently characteristic {vide Part I. p. 243). Trichodiscus is
little known to observers, and probably is only a variety of Actinophrys ; and
Dendrosoma has hitherto received little attention ; its branched pedicle, how-
ever, gives it a generic importance.

Dujardin formed a very correct conception both of the organization and
affinities of the Actinophryina, which were coupled with Amoebsea and Khizo-
poda in his second order of Infusoria. He rejected the genera Podophrya
and Tnchodiscm, which he merged in the genus Actinophrys. Siebold veiy
strangely overlooked the true structui-e and affinities of Actinophrys, which
he placed with Enchelia, in company with the very dissimilar Prorodon,
among his " Stomatoda."

Perty has constituted Actinophryina a second section of Ciliata, and has
adopted the genera Actinophrys, Podophrya, and Acineta. Trichodiscus he
regards as only a compressed form of Actinophrys, and treats Dendrosoma
as an aggregated one, in which the individual beings are collected into
colonies.

Genus ACTINOPHRYS (XXIII. 28-32).— Body more or less spherical,
usually compressed or discoid, sometimes irregular in outline, owing to the
projection of superficial vacuoles. Tentacles tapering, terminated occasionally
by a rounded head {i.e. capitate), pretty uniformly distributed, their length
generally exceeding the diameter of the body ; retractile, and for a time lost
in the substance of the body, but reappearing at the same place and under
the same form. The tentacles serve for prehensile instruments, but not for
locomotion. Food is introduced within the body at any part, and not tkrough
a mouth ; and its excrementitious portion is in a similar manner discharged
from any part of the exterior. Internally are one or two contractile vesicles,
placed immediately beneath the surface, a micleus with a nucleolus ali-
mentary vacuoles, granules, and probably small nuclear cells. Reproduction
takes place by fission, and in Dendrosoma by gemmation. Germinal deve-
lopment is presumed, and conjugation is a frequent phenomenon.

The proboscis mentioned by Ehi-enberg appears to be a sort of expansion
of the sarcode of the body, homologous with a variable process, which enve-
lopes and then drags the prey into the general mass.

Ehrenberg believed he had discovered a mouth, anus, and polygastric
sti-ucture, and that he had succeeded in demonstrating this last by feeding
with coloured food. He likewise adopted Eichhom's statement— that the
tentacles acted as locomotive organs, by giving the animalcules the power to
crawl.

The specific distinctions hitherto attempted are rcnlly of little worth • even
the highest authorities are in doubt, and disagree among themselves respect-
ing the specific names of the animalcules they so elaborately describe - and
the revision of the several forms and varieties of Actinophrys is urgentlv re
quired before any satisfactory separation into species can be made We
append those forms which have been accounted specific by different authors.

Actinophrys 5'o/ (xxiii. 28, 31,32). spherical omonrlv or> . fi,„ * t. ^

660

SYSTEMATIC HISTOEY OP THE INFUSOEIA.

and taper to their extremities, and equal
tlie diameter of the body in length.
Found in the dust-like matter upon the
suiface of infusions, and among Confervse
and vai'ious aquatic plants. Stein asserts
that these habitats are those of A. Eich-
hornii, not of A. Sol, which does not oc-
ciu- as a free beuig. 1-110"' to 1-53."'

This species has been very mvieh con-
founded with ^. Eichliornii. KoUiker mis-
took this last for A. Sol ; and Claparede
wrote his description of A. Mchhornii, and
afterwards discovered it was A. Sol that
he had investigated. Indeed the brief
characters furnished by Ehrenberg are
quite inadequate to identify the species.

A. Eichliornii (xxni. 29). — Large,
white, globose; tentacles shorter than
the diameter of the body, and tapering.
The cortical and medullary layers are well
distinguished; the former contains nu-
merous vesicles. Tentacles contractile,
seen to bend themselves in the prehen-
sion of food, &c. Stein affirms that the
being which Ehrenberg described and
figm-ed under this name is no other than
A. Sol, that the tentacles are by no
means always shorter than the diameter
of the body, but often longer, and that
this circumstance of relative length can-
not be used iu the diag-nosis of the spe-
cies, but that the conical figm-e of the
tentacles is distinctive. Stein's views
on these specific details must be re-
ceived cum grano salis ; for the influence
of his Acinetiform hj'pothesis pervades
his systematic history of the beings of the
class under notice, and his figures of A.
Sol prove him to have been in error either
in the observation or in the interpreta-
tion of the organism ; for they indicate a
member of the Acinetina rather than of
the Actinophryina. Perty seems to think
the largest specimens of A. Sol constitute
A. Mchhornii (Ehr.).

A. oculata (Stein) (xxni. 24, 25). —
Round, more or less discoid, with several
concentric circles of vesicular spaces dis-
tributed over the sm-face of the animal-
cule, giving it an imdidated outline. The
tapering, pointed tentacles ai'ise from tlie
eminences of the sm'face, and are eqmil
in length to the diameter of the body,
except in small specimens, in which
they rather exceed it. The periphery
of the body is covered with a homo-
geneous, transparent, gelatinous, appa-
rently thick layer, within which the
large, vesicidar, non-contractile spaces,
filled with water, are found. Besides
this superficial layer, a cortical and a
modiUlary substance are clearly pro-

nounced. The particles of food do not
enter the medullary substance. The
finely granular nucleus is central, sur-
roimded by a ring of clear medullary
matter. Pressm-e, after the action of
acetic acid, -will sometimes detach it as a
free body, invested by a membrane, and
having within it an ill-defined granular
nucleolus. Diam. 1-38"' to 1-35"'.

A. viridis (Ehr.). — Spherical, greenish ;
rays numerous, shorter than the diameter
of the body. Diam. of body 1-620" to
1-280". Amongst Confervae.

A. difformis. — faegularly lobed, de-
pressed, and hyaline; rays variable in
length, some exceeding the diameter of
the body, which is from 1-570" to 1-280".
The animalcule thus described Stein ap-
prehends to be nothing more than several
youjig specimens of A. Eichhornii con-
joined (conjugated).

A. inarifia (Duj.). — ^Differs from ^. Sb^
in its habitat, and in the more marked
contractility of its rays. Amongst micro-
scopic Algse in the Mediten-anean. Pro-
bably a mere vai'iety of A. Sol.

The claim of A. viridis, A. difformis,
and A. marina to specific distinction is
extremelj' doubtful. The gi-een colour
of the first is immaterial, and the rela-
tive length of its rays to the body of no
specific importance. The irregularly-
lobed outline of A. difformis, again, is an
immaterial condition ; for the soft bodies
of true Actinophryina admit a changeable
outline, and the reception of food, more-
over, to a certain extent involves it.
Dujardin justly attributes no other value
to his species A. marina, than that it
may serve to indicate an Actinophrys
living in the sea.

A. pediccllata (Duy)=Podophri/a Jixa.

A. difjitata. — (Duj.).— Depressed; rays
flexible, thicker at the base, forming,
when contracted, short, thick, finger-
like processes. Diam. 1-750". In fresh
water containing mai-sh-plants. Its dis-
coid body would rather place it with
Trichodiscus.

A. c/ranata (Duj.) {Trichoda granatn,
M.).— Globular, opaque at its centre, sur-
rounded by rays of less length than its
own diameter.

A. Discus (Duj.) = T)-ichodisciis Sol

(Ehr.).

A. ovafa (Lachmann). A species
named by this naturalist in A. A. J£.
1857, xLx. p. 221. , ,

A. brericirrhis (Perty).— Of a dusky
yellowish gi-een colour, rarely colourless;
tentacles much sliorter than the diameter
of the body ; not capitate, but bristle-

OF XnE ACTINOPnRYINA,

561

like. Its outline is double, with a green
or red line. Length 1-600" to 1-500"-
Bern. Among Confer.vfe.

A. Stella (Perty) = Tn'chodisciis Sol. —
It is to be regretted that Perty, whilst

this organism to bo an
Actmophrys, should not have adopted
Dujardin's very appropriate name for it,
rather than encumber the student with
another.

Genus TRICHODISCUS. — Body depressed, with a single marginal row of
setaceous tentacles ; vibratile cilia and teeth absent ; no pedicle ; mouth
truncated (Ehi-.).

These Infusoria,, by their flat disciform shape, resemble Arcellce, but, un-
like the latter, are soft and illoricated, with stiff, bristle -like rays. A central
opening, and a large lateral gland (nucleus), have been recorded by Ehren-
berg, who likewise states that he has seen, though indistinctly, numerous
digestive cells, but neither the reception of coloured food, nor an anal orifice.

This accoimt is very unsatisfactory as a means of determining a genus.
The discoid figure is not a sufiicient distinction from the genus Actinophrys ;
and, on the other hand, the softness of the integument, compared with, the
lorica oi. Arcella, is not a generic distinction; for the so-called lorica of the
latter genus is in many instances only a flexible integument.

Cohn (Zeitschr. 1853, Band. iv. p. 262), after remarldng on certain Acti-
nophryean beings covered with adherent foreign particles of sand, Cyclo-
ieZfe-sheUs, »fec., and siu-mising that such beings were no other t\ian Diffiugice
engaged in the formation of a lorica, submits the opinion, in a foot-note, that
Trichodisci^s Sol (Eihx.) is a similar organism, because Ehrenberg describes its
tentacles as proceeding from the middle of the body, which is often partially
colom-ed with brownish coi-puscles.

Thichodiscus Sol. {Actinophrys Dis-
cus, J).). — Depressed, almost fiat, hyaline
or yellowish, with variable rays. The
motion of this species is very sluggish ;
it often remains for a long time inert.

Amongst Confervre.
rays, 1-430" to 1-210"

Diam., without

Pei-ty, as already seen, retains this spe-
cies Avith Actinophrys, with the name of
A. Stella.

Body
short

Genus PODOPHRYA (XXIII. 34-37).— The members of this genus differ
from Actinophrys only in being stalked. Stalk single, not branched. Eh-
renberg described them as EncheLia devoid of vibratile cilia and teeth, -with
Spherical bodies, covered with setaceous tentacles ; having a truncated (dii-ect)
mouth ; and in organization equivalent to Actinophrys, mth a stiff stalk.

mals, and therefore could not be retained.
Dr. Strethill Wright has since studied
these beings, and distinguished one as
Epihclota apicnlosa, and placed the other
two among Podophrya;. Mr. Alder {A.
N. H. 1851, vii. p. 427) recognized their
relation to Acinctce, and their aflinity
to Campanularian Zoophytes, between
which and Infusoria ho considered tliem
the most perfect link known.

P. fixa {Trichoda Jixa, M. Actino-
phrys imliccllnta, D.).— Body spherical
turbid, whitish, with a diaphanous pe-
dicle slightly excised at the oxtreniity.
The rays or tentacles are capitate at the
extremitv, and equal in length the dia-
meter of the body. Ehrenberg states
that tlie seizing or catching power of
tins animalcule is very interesting to ob-
.«orve. So soon n.s a quickly-vibrating

2 0

Podophhya ovata (Alder),
ovate, with a very slender and
stem ; tentacles capitate, retractile, in a
single row, less numeroiis than in JBphc-
lota apicidosa, and forming a naiTow disc.
Parasitic on Sertulariee.

P. pijriformis (Alder). — Body pear-
shaped, or rather campanulate, with a di-
stinct rim around tlie summit, and a sin-
gle circlet of delicate, capitate, retractile
tentacles; stem long and slender. Pa-
rasitic on Pahidicella, and, imlike the
preceding, an inhabitant of fresh water.

These two species were first described
by Mr. Alder, along witli Ephclotn apicn-
losa, and were described in the previous
edition of this work, under the name of
" Alderia." Lately, however, Mr. Alder
wrote to inform us that this name had
been applied to a diflerent class of ani-

562

SYSTEMATIC HISTOBY OF TEE rNPUSOKlA.

Trichoclina Grandinella approaclies to, and
comes in contact with, its tentacula, it
is immediately taken prisoner, ceases to
vibrate, and stretches out its cilia back-
wards. On the whole, this species re-
sembles Acineta; but Ehrenberg sup-
posed it to possess a discharging orifice,
though its situation is unknown. Found
among dust-like matter upon the surface

of pond- water, " and perhaps," says Ehr.,
" also in the sea." Diam. 1-430".

P. libera (Perty).— Stemless, spherical ;
colourless, or faint yellow; periphery
smooth ; tentacles hyaline, pointed in
greater or less number, many A'ery long,
sometimes very few present, many seen
curved. Diam. 1-330". In stale pond-
water.

Claparede and Lacbmann have recently {Ann. cl. Sc. Nat. 1857) distin-
guished a number of species of Podophrya, many of which would be accounted
Acinetce by Stein ; however, they have no capsule like members of that genus.
No characters are given. The following are noted: — 1. Podophrya Cy-
clopum, parasitic on Cyclops and Lemnae; 2. P. Carchesii, on Garchesium
polypinum ; 3. P. quadripartita, the same as the Acineta assigned by Stein
to Epistylis plicatilis ; 4. P. Pyrum, a large form, pear-shaped, found on
Lemna trmdca ; 5. P. cothurnata, the diademiform Acineta of Stein ; 6. P.
Ferrum-equinum, the Acineta of the same name of Ehr. ; 7. P. Lynghyei, the
Acineta Lynghyei (Ehr.) ; 8. P. , a marine form, with extremely dila-
table suckers.

Genus DENDEOSOMA (Ehr.). — This includes beings which resemble
Actinoplirys, supported on a branching pedicle. The base of the thick
pedicle or trunk is fixed ; and its divisions bear the animalcules at their ex-
tremities. In appearance, therefore, it resembles a microscopic Sertularian
polype.

The question may be raised, if this genus is not the same as Anthophysa
(p. 500), misinterpreted in structure ; and if the organisms terminating the
branches are not Uvellce instead of Actinophrydes.

Dendrosoma radians. — Corpuscles tentacula; disposed on a soft, smooth, and
(animalcules) conical, furnished with alternately branched stem. At Berlin.

Genus EPHELOTA (Wright). — Similar to Podophrya ; but the tentacles,
instead of being capitate, are pointed, and form a wreath or circlet. They
seem also to be either shghtly contractile or retractile, or only flexible.
Pedicle composed of a cortical matter or integument, and a medullary or
contained substance.

Ephelota apicidosa. — ^Body vase- or
cup-shaped, expanded at top and set
round with several circlets of numerous
pointed tentacles ; abruptly thickened to-
wards the base. The tentacles, which
are always in more than one row, enjoy
little motion, curve themselves forward
occasionally, and are slowly retracted at
times. Pedicle stout. Found parasitic
on Serttdaria ; by Dr. Wright on Corync.

It differs from^. coronata in having the
body wider than the stem, more cup-
shaped and elongated, and the tentacles
more irregxdar,soft, retractile, and unsup-
ported by the solid matter which occm-s
111 the interior of tliose of the species
named. It is especially distinguished by
the shape and structm-e of the stem,
which is of nearly equal diameter through-
out, and encloses a cortical substance

formed of circular fibres passing at ri^ht
angles to the fibres of the medulla, which
cortical fibres are absent in Tl. coronata.

E. coronata (Wright). — Body consists
of a short cylinder of densely granidar
sarcode, slightly enlarged above and be-
low, so as to resemble the circlet of a
cro\\Ti. It is sunnoimted by a circle of
thick, acuminate and radiating tentacles,
which ai'e capable of being slowly curved
inwards, but caimot be contracted. They
remain stiflly extended when the animal
is immersed in alcohol. The structure of
the tentacles, I believe, is xmique. Under
high microscopic power they are seen to
consist of a bimdlc or framework of fine
parallel rods of homy (P) texture, imbed-
ded in soft contractile sarcode. The more
central rods of the bimdle protrude con-
tinually beyond those exterior to them,

OF THE ACTINOPHEYINA.

563

so that the point of the tentacle is fonned
of only a veiy small number. In other
examples, each rod, imder a power of 800
diam., assumed a bearded structure.

"The animal secretes beneath itself,
or fi'om its base, a pedicle of diaphanous
and colourless substance, which increases
in length and breadth with the increasing
growth of the animal, until it assumes
the form of a glassy club, on the thick
upper extremity of which the animal
is seated. The whole of the pedicle
is covered by a gi'owth of scattered
hairs; but it may be doubted whether
these have any organic connexion with
it, and whether they do not belong to
one of those minute classes of Algse the
stmctm-e of which eludes microscopic
research. A longitudinal fibrous sti-uc-
ture is faintly seen in the axis of the
pedicle, but it gradually disappears to-

wards the periphery. After immersion
in spirit, this fibrous structure becomes
much more apparent. The action of the
spirit also causes a fine membrane to
separate from the sui'face of the pedicle,
which appears to be continued down-
wards from the body of the animal, and
is probably analogous to the membrane
which I have abeady shown to exist as
a lining and covering to the cell of Va-
ginicola valvata, and which secretes and
hides within itself the valve that closes
the cell of that curious animal " {JSdin.
Neio Phil. Journ. 1858, p. 7).

This species was twice seen by Dr.
Wright, "each time in large colonies,
situated within the mouth of shells in-
habited by the hermit-crab, where the
dense white bodies of the animalcules,
seated on their transpai-ent pedicles, form
sufiiciently remarkable objects."

Genus ZOOTEIREA (Wright) (XXXI. 14-15).— Body furnished with
numerous contractile acuminate rays (tentacula) ; elevated on a contractile
pedicle. Eays becoming thickened towards the point when not fully ex-
tended, but not capitate.

ZoOTEmEA religata (xxxi. 14^15). —
The body of the animalcule, when con-
tracted, consists of densely gi'anxdar sar-
code surrounded by a layer of more
transparent substance. This external
coat is capable of being prolonged into
innumerable exceedingly attenuated ten-
tacles or rays, fi'om eight to ten diameters
of the body in length, and resembling- in
structm-e those of Ephelota apiculosa. The

continuous with the external coat of the
body. 1 have several times seen this
animal, always in colonies. When seen
by oblique illumination, it has a very
striking appearance. The light reflected
from the rays has the appearance of two
cones issuing on opposite sides of the body,
and rotating in opposite directions with
every movement ot the lamp. Found on
shells dredged from deep water in the
Firth of Forth.

animalcule is elevcated on a long contrac
tile pedicle, which appears also to be

We are indebted to Dr. StrethiU Wright of Edinbui-gh for the knowledo'e
of this genus and species. Dr. Wright was so kind as to transmit the
account to us in manuscript, together with notes on Ephelota, the charaetei-s
of the following peculiar genus Corethria, and those of several additional
Infusoria.

Genus COEETHRIA (Wright) (XXXI. 5, 6).— The history of this genus is
thus described (in Uteris) by its discoverer, in the details of the structiu-o of the
only species yet found, viz. : — " CorethriaSertidarim consists of a body, or oblong
cushion-like mass of granular sarcode, furnished with a long club-shaped
appendage, which bears at its summit a thick brush of tentacles. The body
is generally homogeneous, although occasonaUy one or two large colls are
seen within it. The mop-like appendage is seen to contain two structures
both without gi-anules. The interior or meduUaiy portion is a transparent
and structureless cylinder, arising from a slight depression in the body of the
animal. The exterior stnicture, also transparent, is transversely wrinkled or
rugose. The tentacles are transparent, from eight to about forty in nximber
and have occasionaUy a slight waving motion : they appear to arise from the
mtemal lamina or core of the mop. A second kind of appendage is frequently
found attached to the body of Corethria, in the form of a long spindle-shaped

2 0 2

664

SYSTEMATIC HISTOUY OV THE rNFUSOKIA.

mass of granular sarcode, similar to the body, having a depression, perhaps an
orifice, at its distal end. This is either a parasite or a gemma, as it is some-
times found attached alone to the Sertidariu. It appears to multiply by
fission, as two are sometimes found attached together."

In another letter, Dr. Wright remarks that he has " doubts as to the Gre-
garina-Yike body being a part of the animal, as it is often absent," and he has
"seen it fixed to neighbouring bodies." Food is probably taken up by the
summit of the mop-like process, absorbed, and carried down to the body.

Dr. Wright has found this remarkable animalcule thi-ee successive yeara at
Granton, in great abiindance, though in a limited locality. It occurs at all
parts of the polypidom of the Sertuluria pumila, but chiefly in the angle
between the mouth of one cell and the lower part of the cell above, where
two or thi'ce sometimes nestle together.

Although unlike aU other animalcules in shape. Dr. Wright is induced by
its structure to place it near Actinophrys. Were it not for the cushion-like
body, the mop-headed process would be referable to Ephehta.

Subgroup ACINETINA. (Part I. p. 258.)

(Plates XXIII. 1-27 ; XXVI. 3-4 ; XXVH. 13-15, 18-20 ;
XXX. 3, 4, 8, 21-23.)

A subclass of Ehizopoda, very closely resembling Actinophryina, but covered
by an integument or capsule, through which the retractile tentacula or fila-
ments are protruded, and usually supported on a pedicle.

The Adnetce have been supposed to have no power of nourishing them-
selves by absorption of foreign matters from without, as do the Actinophryina ;
but this seems to be an error ; and Lachmann asserts them to be peculiarly
carnivorous animals, the prey being seized by the tentacula, which have
suctorial extremities.

The researches of Stein went to show that the members of this family were
nothing more than a developmental phase of Vorticellina ; but, although tliis
view has been accepted by a few naturalists, it has been pretty successfully
controverted by Lachmann, Claparede, and others, who have witnessed the
reproduction of Acineton from parent fonns.

The tentacles of Acinetina are not as a rule capitate ; many taper, others
are of nearly the same width throughout. They may be distributed pretty
generally over the body, or only along a certain margin, or, again, may be
collected into several bundles.

To represent the known specimens of Acinetiform beings, we shall describe
aU those varieties described by Stein ; for the tnith or error of liis hj-i)othesis
of transfoi-mation does not affect the value of liis descriptions of them as
distinguishable forms of organized beings. But before entering on the account
of these, we shall reproduce the species enumerated by Ehrcnbcrg imder the
head of Acineta.

Genus ACINETA. — Has a membranous lorica, a simple pedicle, and
nimiorous retractile, non-vibrating tentacida. Ehrenberg notes his dis-
covery of vesicles (stomach-cells) in A. Lipiffhyei and A. nii/siacina, and of a
nucleus in the latter and in yl. tuherosa. 'Seif-di^•ision not observed. Kepro-
duction by genus, noticed by Stein, Cicnkowsky, Lachnumn, and others.

Acineta Lynqhyd. — Splierical, pe- pnle-yollow coloured body, -v^nth its thick
dicle thick. It resembles a stalked Ac- cry.stiilline stalk, is similar to a retrnct<?d
tim/phnjs, while tho civculnr, rndintinp-, Voiilcrlla. On Strftifan'a nnd other

OP THE ACINETINA.

565

Polypes. This is called a rodophrya
by Lachnianu. Leng th, iucliidiug- stalk,
1-170" to 1-100".

A. tuberosa (Vorticclla tuberosa, M.)
(xxvi. 3-4). — Triangular, compressed;
dilated and truncate anteriorl)', with
three obtuse tubercles or homs, of which
the two lateral are more constant, and
furnished with tentacula. Pedicle simple
and slender. 1-210" to 1-100". Inmarsh-
and sea-water ; on Cerainiian diapJianiivi
(xxi. 3-4). See accoimt of Adnata of
Zoothamnium affine.

A. mystaeina (x. 205). — Subglobose,
obtusely homed, with two elongated
bimdles of tentacula; pedicle slender.
Upon Lcnma minor. 1-860" to 1-120".

A. Ferrum-equinum (xxni. 26, 27). —
Ovate, white, tentacula disposed at its
fi'ont; pedicle small, thick; a central
gland of a horse-shoe shape. 1-240". Ber-
lin. This Lachmann calls a Podophrya.

A. (?). — BrightweU desciibes an ani-
malcule with an oval sheath, of a dark
coloiu', opake and granulated, and having
a bimdle of diverging rays proceeding
fi'om each extremity, many of which, by
contraction or otherwise, have a globular
tip. They were not observed to move or
catch other animalcules. In fresh water
at Oulton, Norfolk.

A. patida. — A species mentioned by
Lachmann {A. S. N. 1857) as developing
embryos, and common on Algffi and
Zostera found on the coast of Norway.

A. Ciicidhis. — Another species named,
and not described, by the same natm'alist.
Foimd in the Fjord of Bergen.

A. cylindrica (Peiiy). — Colomless,
transparent, cylindi'ical, supported on a
short stem. 1-22"'.

Cothumia maritima. — Its presumed
Acineta bore a close resemblance to Ad-
nata tuberosa (Ehr.). It had a moderately
long, thin stalk, not dilated upwards ; and
the body was enclosed by a hyaline cap-
side, capped by a conical, roof-like por-
tion, fi'om which the inverted conical or
pyriform granular body was suspended,
more or less space intervening between
it and the canside. From each external
anterior angle proceeded a bundle of
gently-tapermg, fine, antl slightly capi-
tate tentacles, retractile and divergent.
Internally was a round contractile space
and an oval nucleus.

Epistylis brunchi(yphila. — The Adneta
assigned to it by Stein has usually a short,
slightly cuiTcd, still' and solid pedicle,
always much tliinner tlian tlio stem of
the JSpistylts itself. Figure pyriform ; two
bundles of bristly, non-capitate tentacida

given olF from its antenor end. The body
exhibits constant changes in outline by
the vermicular contractions of its tissue,
and likewise alters its relative position
with its stem. It likewise exhibits ti'ans-
itory folds, swellings, and inflations of
thesm-face. 1-240".

U. crassicolUs. — Stem of its Adneta
transversely striped, crystalline, mostly
straight, and generally like that of the
Epistylis itself, except in thickness, being
in this respect much thinner, save at its
expansion, supporting the body of the
Adneta. This last is of a rectangular
figure, with rounded angles, and often
inflated at the middle. Tentacula taper-
ing, capitate, always few in number —
fi-om two to foiu- at each of the foui*
angles, and always longer than the dia-
meter of the body. Length (maximum)
of body 1-30"', breadth 1-28"'. Foimd
on the Entomosti'aca.

E. plicatilis. — ^«Heto-pedicle solid,
longitudinally sti'iated, much narrower
than stem of the Epistylis, except at its
upward dilatation, where the body was
aflixed. Body pyriform or ovoid, com-
pressed ; in most specimens with a
smooth surface and no tentacula : when
the last were present they were small,
capitate, and few in nimiber, and col-
lected in fom' bundles, one on each lobu-
lar expansion of the then expanded Ad-
neta. Maxim, length 1-16"', width 1-20"'.

Opercidaria articulata (xxx. 3-4). —
Pedicle of Adneta rigid, solid, thin,
mostly cmwed, and shorter than the
body. After a certain height (about
the half) it suddenly and gi-eatly ex-
pands to its point of articulation with
the body._ It is striated longitudinally,
and hyaline. Body compressed, with 'a
circular outline, or discoid, ovoid, or py-
riform figm-e. Abruptly and widely trun-
cate at its base, where it is fixed on its
pedicle: surromided by an apparently
iirni and thick integmnent, without
apertm-e, and covered at slight intervals
by short, thick, tubular and undidating
tentacles. Maximum lenijth 1-20'" to
1-12"', width 1-14"' to 1-24"'.

0. berbcrina (xxiii. 17-20).— Stem of
Acincta very short, thick, solid, smooth
or transversely striped, usually con-
tracted in the centre and dilated at each
end. The stem supports a very large
flattened, discoid capside, witli a para-
bolic outline, and having a gently curved
anterior double margin enclosing" an open
space. Tlie margins are comparable to
a front and back lip : the walls of the
capsule thick, flexible, and livaline \

50(3

SYSTEMATIC HISTOKY 01' THE raFCSOlllA.

portion of the contained Acineta-hody
extends beyond the lips like a tongue.
This process contains from four to five
contractile spaces, variable both in posi-
tion and size, as well as changeable in
figui-e, from a circular to a dumb-bell
shape. The roimded anterior angles of
the process support numerous radiating
tubiuar tentacles, neither capitate nor
tapering, but reti'actile and capable of
bemg collected together in cylindrical
bimdles. The tentacles may be retracted
within the lips of the capsular opening ;
and when this happens, the anterior mar-
gin of the Acineta has a tiilobate cha-
racter ; and veiy fi-equently a transverse
fold makes its appearance behind the
middle of the body, and might easily be
mistaken for an indication of commenc-
ing ti'ansverse fission. Sometimes two
such folds are displayed. Maximum
length of capsule 1-14"', width across
the anterior labiate extremity 1-19"' ;
length of pedicle 1-125'".

In figure and other respects this Aci-
neta, remarks Stein, differs so mate-
rially from those of other Acinetina,
that, if these beings are to be considered
independent organisms, it would req[uire
the creation of a new genus.

0. lAchtensteinii (xxni. 22-23). — ^The
Acineta varies very much both in figure
and dimensions. All varieties have a
short, thick, solid stem, dilating upwards
to the body of the animal. When largest,
it equals half the length of the body,
but is at times so short that the body
1' seems as if sessile. The body is usually
strongly compressed laterally, and in
outline is a long or short oval, ovate,
pyrifoi-m, or circular, except that in all
cases it is nan-owed at its base to equal
in width that of the supporting pedicle.
In short-stalked smaller individuals, the
body is mostly so very shortened and
depressed, in its long axis, that the stem
is quite overlaid, and the entire being
has a reniform shape. A circular or oval
nucleus occurs in the interior, but no
contractile sac was discoverable. Maxi-
mum length 1-18'", width 1-24"', dia-
meter of smallest specimens 1-96"'.

Ophrydium versatile (xxx. 8). — Stein
(iocs not appear satisfied with regard to
the Acinetifomi being to be assigned to
this member of the VorticeUina (Ophr}'-
dina). Ho found many cystic oval or
ovoid bodies, with an iiTcgular central
nucleus and numerous chlorophyll-cor-
puscles in company with this Ophr i/dium ;
and along with these, which he concluded
to be encysted being-s, other saccular

orga,nisms, of like size and figure, con-
taining also a central nucleus and many
chlorophyll cells, and withal furnished
with a large number of tapering tubular,
mostly cm-ved or contorted, motionless
processes or tentacles, distributed over
the sm-face, recalling, in general appear-
ance, the " digitate Acineta."

Spirochona gemmipara (xxx. 21-24).
— Stein assigns to this peculiar member
of the VorticeUina a very extraordinary
Acineta, which he has named Dendro-
cometes paradoxus. The body is plano-
convex, circular, without pedicle, and
gives ofl" from its surface no tentacles of
any of the ordinary t}'pes, but one or
more large tubular processes, more or
less branched. There is so gi-eat an in-
constancy in the number, position, size,
and ramification of these processes (says
Stein), that two similar specimens are
scarcely to be foimd. The processes on
the same being differ also very much in
size and mode and degi-ee of branching.
Five is the prevalent number in the
most fully developed fonns; above six
are scarcely ever seen ; three or fom* axe
not imcommon ; a single one is seen only
in undeveloped examples. An entire ab-
sence of such appendages is not very
imcommon, the nuclear developments in
their interior sei"ving to identify them.
Neither theii- ti'unk-like process nor any
of its ramifications has the power of
lengthening or shortening itself; but the
whole process may undergo a cei-tain
amount of ciu'vature, and extend itself in
a rigid manner. Diameter of body 1-54"'
to 1-25';'.

Notwithstanding the very patent di-
versity in fonn and constitution. Stein
declares these tubular ramified processes
to be morphologically and physiologically
identical with ordinary tentacula.

Vaginicola crystaUina (xxra. 12-16).
— The Acineta attributed to this bein^
by Stein has a hyaline capsule, expanded
in front and narrowed posteriorly into a
sort of hoUow pedicle. The dilated upper
portion is infundibulifomi, urceolate, or
pyi'iform in figure, and is partiallv occu-
pied by the granular mass of the body of
the animalcule, enclosed in a membra-
nous sac of its owTi. The body is sus-
pended from the vaulted anterior surface
of the capside by an intermediate gela-
tinous layer, wliicli often appears pli-
cated. Its bidk varies extremely ; at
times it nearly occupies the whole cavity
of the capsule, except the prolonged
stem-like portion, which never contams
anv ; at others it forms only a small ball

or THE ACLNETINA. 567

at the anterior end, which is then con-
tracted upon it by being tlirown into a
few longitudinal "folds. The tentacles
proceed from the anterior siu-face of the
body and penetrate through certain fis-
sures in the capsule above, diverging
from the surface in a radiating manner.
They are long, capitate, slightly tapering
and retractile. The body contains a cir-
cular nucleus and a contractile vesicle.
Maximum dimensions of capsule 1-4"' in
height, 1-32'" in width. The minimum
1-24'" high, and 1-43"' wide.

Stein puts this Acineta forwai'd as one
of the best illustrations to be obtained of
the conversion of an encysted Vorticel-
lina into an Acineta. The Acineta he
identifies with the A. mystacina (Ehr.),
and portrays two modes of develop-
ment : one by a series of cHiated em-
bryos, enveloped each in its own capsule,
given off fi'om the surface by a sort of
gemmation — this process going on until
the whole animal mass is exhausted;
the other by the conversion of the whole
mass, simidtaneously, into several elon-
gated-oval gi-anular germs, covered by
a membrane, but not ciliated.

Vorticella microstoma. — Stein consi-
ders the Actinophrys Sol and Podophrya
fixa (Ehr.) to be the Acinetiform re-
presentatives of this species of Vorti-
cella. In our opinion, as before expressed,
and which we partake in common with
Cienkowski and others, the being de-
scribed by Stein imder the name Actino-
phrys is in fact an Acineta. It is repre-
sented as covered by a firm integimaent,
which frequently assumes the characters
of a cyst, becomes plicated around it,
and extended into a hollow pedicle,
giving it the appearance of Vodaphrya.
Moreover, foreign substances were never
seen to enter its interior, as happens
in the true Actinoplirys. The fm-ther
history of this Acineta has been sketched
in the chapter on development of Ciliata
(p. 360 et scq.).

V. nehdifera. — The Acineta in Stein's
estimation belonging to this species of
Vorticella is found upon Lemna. The
pedicle is much longer and the body
more contractile, and therefore more
changeable in figure, than the Acineta
found on the Cyclops. When at rest,
their figure is more or less compressed,
and ovate or pear-shaped, with a pro-
minent angle on each side of the anterior
margin, from which a bundle of radi-
ating retractile tentacles extends. Oval,
circular, and discoid forms ai'o not un-
common. The stem is clastic, ciu'ved,

and, as a ride, longer than the body it
supports, and is hollowed by a narrow
canal. It expands at its junction with
the body and then spreads over it, form-
ing an external sheath or capsule, except
in the region supporting the tentacles,
where it seems to be either absent or of
gi-eat tenuity. Beneath this is a special
covering of the Acineta body, entirely
investing it. Notwithstanding these co-
verings, the body is remarkable for its
contractility and the mutability of its
figm'e. It also enjoys a certain amount
ot movement on its pedicle, bending in
this and that direction with a peciiliar
jerking motion. The body contains an
oval nucleus, and from one to three con-
tractile spaces. It developes a ciliated
embryo. The length of the body is from
1-100"' to 1-20"', that of the stem not
above 1-10"'.

Zoothamniian affine. — The supposed
Acineta of this animalcule was found by
Stein on marine Crustacea — the Gam-
inarus marinus and Sphceroma sei'rata,
along with the Zootham^iium. It appears
identical with ^& Acineta tuber osa (Ehr.^.
It is compressed, campanidate, or pjTi-
form, and has each external anterior
angle lobate and surnioimted by a group
of tapering and radiant tentacida. An
intermediate prominence is also frequent,
but no tentacles spring fi-om it. The
body is distinctly enclosed by a hyaline
elastic capsule, which is extended down-
wards into a tubular pedicle, and by a
softer membrane immediately investing
it. The latter becomes especially pro-
noimced when, as fr-equently happens, it
is throwai into ti-ansverse folds in its
narrower or posterior half dm-ing the
more forcible contiactions of the Ijody.
Length from 1-63"' to 1-24"': maximum
of stem 1-18"'.

Carchesium pygmccum. — Stein lat-
terly refen-ed to this species an Acineta,
common on Cyclops, and which he at
first assigned to Epistylis digitaUs. The
stem is very short, often with diificulty
perceptible, but never wanting. The
body is generally pyi-iform and com-
pressed; its anterior end is roimded or
truncate, and slightly emarginato, and
supports at each of its angles a bimdlo
of tentacles. Frequently the tentacula
are not thus gi'ouped in "two masses, but
occupy the whole anterior margin and
the sides for a short distance — a circum-
stance met -with in smaller specimens
which liave a circular, oval, or reniform
fignre. The nucleus is oval and small.
No movements in the body are discerni-

668

SYSTEMATIC HISTOUY Ol? THE INFU80UIA.

ble, oud the leugtliening and shortening
of the tentacles is very slow. This
Acineta developes a ciliated embryo
which resembles the Halteria Grandi-
nella (Duj.). Maximum length 1-30"'.
Common size, diameter 1-50"' to 1-40"'.

Acineta diademiformis (xxm. 15-16).
— Stein describes a peculiar Acineta
found upon the roots of Lemna, under
the name of the diadem-like Acineta.
Its figiu'e is compressed, disciform,
ti-ansversely oval or reniform ; and it
is supported on its somewhat contracted
base by a short, thick, solid stalk, longi-
tudinally striated, and often marked by
a few transverse lines. The stem is
always so short that the body looks as
if sessile. The latter is enveloped by
a thick, sti'uctureless, smooth and hya-
line external membrane, and by a second
layer beneath, closely investing the ani-
mal mass. On the free margin of the
body, particularly in fi'ont, a number
of comparatively thick but fine-pointed
tentacles are disposed at slight distances
from one another. These, which are not
clearly capitate, consist of a delicate mem-
brane enclosing a finely granular matter,
and are prolongations from the special
membrane of the body; consequently
they have to perforate the outer enve-
lope ; and Stein leans to the opinion that
the latter is an excretion from the
fonner. Usually the tentacular pro-
cesses are very slowly retracted: how-
ever, when the Acineta is much distui'bed,
the shortening takes place much more
rapidly, and renders them tortuous. A
long band-like nucleus lies across the
centi-e ; and a number of transparent
vesicles are disposed at equal intervals
aroimd the border, like a row of peai'ls
around a diadem. At long intervals one
or another of these sacs is seen to vanish,
and after a time to reappear in the same

place, like true contractile vesicles. No
contractions of the body are observable ;
it remains stifl" and motionless. It pro-
duces a large ciliated embryo, which
lies ti'ansversely across it in "its special
sac. Maximum breadth 1-14"'; heijrht
1-20"', of stem 1-100"'.

The stift" solid stem and the remarkable
band-like nucleus indicate, says Stein,
its derivation from some large species
of Epistylis. It is the same organism as
the Acineta Ferrum-equinum, according
to Lachmann.

A. digitata (xxm. 21). — Under the
name of the fingered or digitate Acineta,
another variety of this class is charac-
terized by Stein, who failed to detect
the cUiated Infusorium to which, ac-
cording to his hypothesis, it should owe
its origin. It was found on some Ento-
mostraca, and had a stemless, patella-
shaped or transversely oval body, ad-
herent either by the whole surface in
apposition or by the central portion only.
Its upper side usually presented uTegular
depressions and small eminences, and was
very often divided into an anterior and
posterior half by an annular constriction.
From the entire upper sui-face, or only
from its anterior section when the central
constriction is present, a number of di-
vergent, very thick, finger-like tentacles
spring, apparently without order and
non-reti'actile. No contractions of the
body were witnessed ; but some change
of outline is possible. A naiTow, coiled
nucleus is brought into view by acetic
acid. The peculiar contractile vesicles
are wanting ; but fi'om two to three un-
changeable cleai- spaces of different sizes
exist. Along with these normal speci-
mens, others occmTed having a smooth
siu-face and no processes. Maximum
width 1-30- ' '

height 1-58"

and

Genus OPHEYODENDEON. — Noticed and named in Lachmann
Claparede's paper in the Ann. d. Sc. Nat. 1857. No description given.

It is said to be a very singidar animal, doubtfully referable to Acinetina,
found parasitic on Campanularia from the Norwegian coast. One species is
named.

OrHBYODENDKON abietinum. — Chai-acters imdescribed.

GROUP III.— CILIATA (p. 199 and p. 266).

The group of the ciliated Protozoa, according to the scheme adopted, are
resolved into two divisionis :— 1, moulhlcss (A.stonia) ; and 2, those having

01'' THE CILIATA. ASTOMA.

509

a mouth (Stomatoda). Of the former we have in the general histoiy de-
scribed two familes, viz. Opalinaea and PeridiniiEa ; and we shall fii-st pro-
ceed to give a systematic accoimt of their several recognized members, and
in so doing redistribute certain species and genera otherwise classed by
Ehrenberg, — for instance, several Opalince described among the Bursarice.
Again, in the systems of Dujardin and Perty, several mouthless genera are
enumerated which must find their place in the fii'st division of the Ciliata, as
adopted by us. Such are the Leucophryina of Dujardin generally, together
with a few Plcesconiens and Ervihens, and the Cobalina of Perty. The
Peridiniffia of Ehrenberg, again, include two genera, ChcBtotyphla and Ghai-
toglena, which should rightly find a place among Phytozoa ; but, to avoid
disturbing the classification employed, we have retained them in the same
family.

Among the Stomatoda are described, not only the families enumerated by
Ehrenberg (see p. 377), but also those constituted by Perty, Dujardin, and
others, — the place of their introduction being determined by the Ehrenbergian
group to which they appear to hold the greatest affinity.

We conunence the systematic accoTint of the Stomatoda with the ill- defined
and imperfectly observed family Cychdina, and take the other Ehrenbergian
families in the order shoAvn at p. 377. With the Vorticellina the Urceolarina
of Dujardin and the Vaginifera of Perty are conjoined, as weU. as several
genera newly instituted. The Ophrydina embrace additional genera ; and the
genu,s Enchelia, whilst it is, on the one hand, deprived of the very heterogeneous
organisms inti'oduced into it by Ehrenberg, viz. Actinophrys, Acineta, and Tri-
cJiocliscus, and which have already been treated as subfamilies of Rhizopoda,
it has, on the other, appended to it the families Tapinia, Apionidina, and
Holophryina of Perty, besides several genera named by this naturalist and
by Dujardin. The history of Biu'sarina, Decteria, and CinetochiUna (Perty),
is included in that of the TracheHna; and that of Paramecina (Duj.) and
Aphthonia (Perty) in the account of Kolpodea. The Oxytrichina embrace
the Keronina (Keroniens) of Dujardin ; lastly, the Euplotina comprehend the
Plcesconiens and Erviliens of the same writer.

Division A.— ASTOMA.

FAMILY I.— OPALIMA. (Part I. p. 267.)

(XXII. 46, 47 ; XXVI. 28, 29.)

Ciliated parasitic Protozoa, consisting of a more or less oval sac, which resem-
ble in fig-ui-e many Bursarke, and, although often presenting an anterior fold
or fossa, have no mouth. They contain, besides the usual molecular matters
a granular nucleus, and multiply by transverse fission. A globular contractile
vesicle is absent in all ; but in 0. Planariarmn and 0. unc'mata (of Schultze)
an elongated pulsating sac occurs, recalling in character the so-called dorsal
vessel of various higher animals ; and in others, instead of a contractile vesicle
numerous irregularly-disposed saccular spaces occur. The nucleus is not dis-
coverable in 0. Ranarum, wliilst in 0. branchiarum one of unusually large
volume is found. OpaUnce arc probably larvae of various vermes and' not
independent organisms.

Genus OPALINA. — The characters the same as those of the subclass It
wiU be seen, in the following specific descriptions, that many of the Opalma:
have been descnbcd by other systematic writers as members of genera of
Stomatoda, such as Bursar ia, Leucophrys, and Paramecium. Stein h-is dc
voted much attention to the Opalino! ; and we accept his determination of the

570

SYSTEMATIC HISTOKY OP TILE IKFTTSOHIA.

characters and distinctions of species, along with the names ho has assigned
them.

The genus Opalhia was constituted by Purkinje, and has been generally-
accepted. Dujardin introduced Oxmlina into his family Lcucophryina along
with Leucoj)hrys and Spathidium, and characterized that family as of a com-
pressed-oval or oblong figure, clothed with closely-arranged cilia in regidar
series, and apparently destitute of a mouth.

OpaI/INA Ranarum = Bursaria Rana-
rmn (E.). — ^The mouth described by
Ehrenberg in this species is merely a fold
of the surface, as may be proved by add-
ing a dilute solution of iodine, of alcohol,
or of acetic acid, which will cause the
animal to swell up and evenly distend
the entu-e surface. Stein could find no
micleus. This species is common in the
intestine and bladder of frogs. Perty
makes it to include besides Bursaria
jRanarutn (E.), also £. Entozoon, B.
Nucleus, and probably B. intestinalis.

0. Flanariarum (Siebold) = O. poly-
mm-plia (Schidtze). — The body has the
form of a long cylindrical sac, pointed and
wedge-shaped posteriorly, and expanded
in front as a remarkable semicircular
disc, by the central part of which it ad-
heres to the surface of the intestine it
occupies, the border being crowned with
a wreath of long cilia. 1 he actual point
of attachment appears destitute of cilia ;
butthe posteriorsm-face is thickly studded
vsdth shorter ones. The contents consist
of a homogeneous molecidar substance,
with numerous interspersed hyaline
spaces. A long pulsating vesicle (or,
from its length, a vessel) and a nucleus
are also seen vnthin the interior. The
pulsating vessel extends to the extreme
point of the body behind, just beneath
the integTuent, but not in union with it,
and terminates on the anterior side of
the semicircular process in front. Its
walls are structureless and transparent;
and by its alternate contractions and ex-
pansions it pushes forth the contained
water alternately from each end. The
position of the nucleus in the interior is
not constant ; it consists of a finely
granular mass containing some larger
granules, and is sharply defined. Fission
is transverse, the nucleus and contractile
vessel dividing consentaneously with the
body. Stein could not discover the
orifices at the end of the pulsating vessel
described by Schultze. Maximum size
1-3"' in length ; breadth 1-20"' ; length
of nucleus 1-25"'.

0. Lumbtici (Stein). — Is represented
by Lmcopliri/s striata and L. vodulata
(Diij.), the latter being an altered form

of the fonner, dependent on irregular
endosmosis of the water in which it is
placed. Transverse fission occui-s in all
sizes, which vary from 1-60"' to 1-14"'.
Parasitic in earth-wonns (lAimbfict).

0. armata (Stein) = 0. Lumbrici
(I)uj.). — Has an oval compressed figure
like the foregoiag, from which it difiers
by having a strong, homy, imcinate pro-
cess at the anterior extremity, on the
under sui-face of the body, and, extending
fi'om it, a fold of the sm-face. The other-
wise homogeneous and finely granular
nucleus is remarkable by exJiibiting a
greater or less number of solid oval
nuclei and elongated rods. Specimens
of this species are peculiar by their uni-
foiTuity of size, which somewhat exceeds
that of the largest 0. Lumbrici, being
from 1-12"' to 1-8"' : hence Stein pre-
sumes that O. armata is nothing more
than a fm-ther developed phase of 0.
Lumbrici, from which it diners only in
size and in the presence of the prehensile
apparatus. He sm-mises further that
this and other OpalincB may be members
in the chain of development of worms.

0. Anoclonta (Stein) = Leucoj)hrys
Anoclont(s(E.). — Mouthless, oval, tm-gid,
ti'ansparent ; ciliated equally throughout.
1-36"'. Parasitic in Anodonta and My-
tilus edulis.

0. branchiarum. — Is characterized by
its veiy large nucleus, which equals in
volume the half of the entire organism.
Its contour is also similai* ; and it might
be taken for an imprisoned animal.
Common in the ovisacs of Gammarits
Pulex.

0. Uneata (Schnitzel — Is without
uncini, and has, like the last, a very large
nucleus. lu Na'is littoralis (see Sch ultze's
work Beitriiye zur Katurqeschichtc der
TurbeUarien, Greifswald, 1851, p. 69).

0. Naidos (Duj.) (XXVI. 28, 29).--Is,
like the preceding, unfimiished with a
prehensile apparatus. Figure oval, or
very elongated and nearly cylindrical,
longitudinally aud ti-ausversely striated :
the fold extends from the anterior ex-
tremity ncariy to the middle. Numerous
clear spaces 'in the inferior, irregularly
distributed. 1-22"' to 1-11'". Parasitic

OF THE CILIATA. STOMATODA,

571

in Na'is (one of the Annelida) (xxi. 28,
29).

0. itncinata (Schultze). — Resembles
0. Plananarum in general oi-ganization ;
it has the sanie sort of pulsating vessel,
and a similar nucleus ; it multiplies by
transverse fission, and diilers from all
other known Ojmlince by having a pair
of strong, horny imcini at the anterior
extremity, one on each side of the median
line, giving it a bilateral character. Stein

supposes this armature replaces the usual
fringe of cilia, in the animals after having
attamed a certain age or stage. In the
interior of Planana Ulva, &c. 1-120".

0. Ti-Uonis (Perty). — Discoid, roimded
in front, with a loop-like depression;
colom-less. 1-336". Revolves on its
shorter axis. Parasitic in the intestine
of Triton cristatm (the crested Water-
newt). Is very like O. Ranarum, and
requires fm-ther examination.

O. Nucleus = Bm-saria Nucleus ; O. Entozoon = Bursaria Entozoon ; O. intestmalis
= Bursaria intcstinalis. These three presiuned species are nothing more than
different phases of growth and development of Opalina {Bursaria, Ehr.) Rmiaru7n.
We have, however, retained the briet notes of their characters as Bursaries given
by Ehrenberg.

FAMILY II.— COBALIl^A (Perty).

Animals parasitic ; either with or without a month ; most of them receive
only the jmces of other animals. Body mostly flattened, oval, elliptic, or
reniform, with numerous rows of very delicate cilia, and often with an un-
cinate variety on the under siu'face. An oral-looking depression or fold fur-
nished with stronger cilia commonly perceptible ; but several have no such
indication of a mouth. Only those living externally upon animals are capable
of receiving solid nourishment. In internal functions and in form they pre-
sent a general uniformity and agreement, and are equally peculiar ; they
occupy a lower position than free living forms similar to them ; their move-
ments are simply automatic in character.

a. With rows of cilia above, and uncini beneath.

Genus ALASTOR. — The type of this genus is the Kerona Polyporum
(Ehr.), and is called Alastor Polyporum.

b. With delicate cilia both above atul beneath. Receive only the juices of

other animals.

Genus PLAGIOTOMA(Duj.) {vide Family Tbachelina).
Plagiotoma Lumhiici ; Pl. Coticharum ; Px,. (?) difformis.

Genus LEUCOPHRYS (Duj.) {vide ante, p. 670, Opalina Lumbrici).
Leuccphbys striata.

Division B.— STOMATODA.

FAMILY I.— CYCLIDINA.
(X. 209-212).

lUoricated Polygastrica devoid of eye-specks and of true alimentary canal,
and having but one alimentary aperture, furnished ^yit]\ cilia or bristles, tho
various groupings and relations of which afford characters for tho disciiniina-
tion of the genera ; gastric ccUs (vacuoles) have been obsen^ed in two species
of Cyclidium. Locomotion is effected by the vibratilc cilia and a filament
proceeding from the anterior extremity.

The genera are distributed as follows : —

• Body compressed— cilia arranged in a single "1 ^ ,.

circle ° > Cyclidimn.

^ , , ^°'ly°""t^-<'i«a scattered all over Pantotriclnmi.

Body furnished witJi bristles ,

t-hrctomonas.

Body furnished with ciUa

572

SYSTEMATIC mSTOKY OP THE- INFUSOEIA,

This family has no corresponding one in the system of Dujardin. Some of
its members are represented in the family of the Enchelina as members of the
genera Acomia and Enchelys. The genus Cyclidium (Duj.) is included among
the Monadina of that author (p. 497), and includes beings furnished with a
filament, but destitute of mouth and cUia — characters not at aU analogous to
those given by Ehrenberg to his genus of this name.

Perty, moreover, has not retained this family in his system, although he
accepts the genus Cyclidium, which he refers to a family called " Tapinia,"
whei'e it is associated with Acomia (Duj.), with Leucophrys (Ehr.) or Triclioda
(Duj.), and with the following newly-instituted genera: viz. Acrojpisthium,
Bceonidium, Opisthiotricha, Siagontherium, and Megatriclia, — a set of terms not
recommending themselves by their euphony, and, we presume, not wanted in
a true systematic distribution to express distinct and independent fonns of
ciliated Protozoa. However, to render our resume complete, these presumed
new genera are appended to the family of Enchelia, to which several of their
species are referred by Ehrenberg.

The family Cyclidma (Ehr.) would, in all probability, disappear from a
revised system of classification. Thus Cyclidium appears to be only an em-
bryonic phase of other animalcules, and PantotricJmm and Chcetomonas are
not sufficiently characterized and examined by Ehrenberg to enable us with
certainty to recognize them, or to determine their affinity. Moreover, the
beings brought together under these genera are, some of them at least, very
doubtfully referable to them, and have been so casually examined that their
identification would be difficult. The ova and the polygastric organization
mentioned in Ehrenberg's account are matters only of hypothesis.

Genus CYCLIDIUM. — Body compressed discoid, provided with a simple
circular row of ciUa. In C. Glaucoma alimentary vacuoles are distinct. The
mouth is a rounded opening, situated upon the under surface of the body,
either close at the anterior extremity, or towards the centre. The organs of
locomotion consist, as in Keromi and Stylonychia, of a number of cilia-like
feet, situated on the margin of the abdomen. It has been thought that
longitiidinal lines, produced by rows of very delicate cilia, were present : if
so, and an anal opening be discovered, C. Glaucoma woiild rank Avith the
Oxytrichina. Fission transverse. Since Ehrenberg wrote these obsei"vations,
Lachmann has described not only a mouth, but also an anus on the ventral
surface near the jiosterior extremity. This statement, taken in connexion
with another, that some at least of the forms of Cyclidium are embryonic
stages of other animalcules, leaves this genus in the greatest uncertainty both
as to its independent existence and its systematic position.

Cyclidium Glaucoma (M.). — Oblong-

elliptic, abdomen fringed with cilia ;
delicate longitudinal stnce are observed
upon the back. In swinnning, it re-
sembles Gi/rinm, or Notonecta, a well-
known little black water-beetle (see
Mia-oscopic Cabinet, pi. 4). Sometimes
the movement is very quick ; at other
times the animalcules remain for a while
stationary, and then presently spring
with a curvetting motion to another
spot. Fonnorly this species was con-
founded with Glaucoma scintillans, but
is much smaller (x. 209 is a side view,
showing the cilia ; fig. 211 a dorsal view ;
and fig. 210 ii specimen undergoing trans-

verse self-division). They ai-e repre-
sented as fed -wath indigo. Abundant
in vegetable hifusions in the spring.
1-2880" to 1-1150".

Betwixt this species and Enchelys
nodulosa (Dili-) there is a complete
agreement. I'lie body, on a transverse
section, is triaugidar; hence it is (sa.'\-s
Perty) that Dujardin has described it as
sometimes assuming a triaugidar form.
Chlorophvll granules are occasionall\
seen internally. Stem identifies the
embryo of Chi'hdoit Cucullnhis witli this
species of Cycltdium, wliich lie would
tlierefore exehulo from llie category of
independent auiiiialcules. Intcrnally.tbis

OF TlIE CYCLIBINA.

573

oxcoUent observer also describes a cou-
tractile vesicle and a discoid nncleus ;
the former is the clear space mistaken
by Ehrenberg for a mouth. At the same
time he considers an oral apertm'e most
probably exists somewhere near the
middle of the organism, since he has
seen the entrance of solid particles into
the interior. Perty makes C. Glaucoma
synonymous also with Enchelys triquetra
(Ehr.), and probably with, the Para-
mecium Milium and Uyclicliicm Milium of
Miiller. In his system it is a member of
the family Tapinia, where it is conjoined
with some species of Leucophrys, with
Acomia (Duj.), and several newly-
created genera.

C. margantaceum. — Orbicular, ellip-
tical ; the posterior end slightly excised ;
tlie dorsal sm-face with distinct longi-
tudinal lines ; cilia not distinct. 1-1500"
to 1-1000".

This species is separated by Perty from
Glaucoma, and constitutes in his system
the representative of a genus he names
Cinetochilum, which, with Glaucoma,
forms the family Cinetochilina (vide

Glaucoma). The Gin. margaritaceum is
characterized as a short elliptical animal,
rather compressed and with its vibratile
flap on the posterior half, colourless and
transparent. Movements quick; rota-
tion on its axis rare. Cilia very short.
Fission transverse. 1-810" to 1-720".
Lachmann {A. N. H. xix. 216) appears
to approve of the systematic position
assigned by Perty to this being.

C. (?) planum. — Oblong-elliptic,
smooth; cilia but little marked. 1-2640".

C. (?) lentiforme. — Smaller than C.
planum, and has no distinct striae or cilia.
1-3180".

C. Arhorum. — Small, suborbicular,
slightly excised laterally; dorsum ru-
gose ; margin everywhere ciliated. Diam.
1-192"'. Marginal cilia used in the way
of feet; swims rapidly. Fission trans-
verse. On moss of ti-ees.

This animalcule is identified by Cohn
(Siebold's Zeitsch. 1851, p. 273) with the
embiyo developed by Loxodes {^Parame-
cium^ Bursaria. If this be the case, it
must be rejected from the list of inde-
pendent species.

Genus PANTOTEICHUM. — Body tiu'gid, covered with moveable cilia. In
P. Enchelys gastric ceUs (vacuoles) are distinctly visible. Granules, green or
yellow, occupy the interior. Ehrenberg says, " The absence of a double aU-
mentaiy aperture is not yet proved ; nor, on the other hand, is its existence."
Pantotrichum is not received by Perty as an independent genus, but is com-
prehended by him with. Lagenella and Ohcetoglena, under the common appel-
lation Chonemonas, and placed among the Thecamonadina.

Pantotrichum Enchelys. — Cylindii
cal, oblong, roimded at both ends ; hya-

line at extremities and tm'bid, the centre-
colour pale yellow, x. 212 is a cluster
of animalcules; those to the left are
more highlj' magnified than the others.
In swimming they revolve and glide
along in the direction of the longer axis
of the body. In infusions of raw flesh.
1-1150".

P. volvox (Leucophrya viridis, M.). —

In

Ovate, spherical, of a gi'een colom"
brackish water. 1-860".

P. Lagenella.—Ovnte, the ends equally
rounded, anterior ciHated portion pro-
duced in the fomi of a neck or beak.
Amongst Confervaj. 1-1080" to 1-570".

Schneider (A. N. H. 1854, p. 329) de-
scribes this species aa forming ai-ound
Itself a cyst, which completely retains
tJie flask-like form of the body, when the
animalcide enters on a state of rest.

Genus CBMETOMONAS.-— Motion slow, and leaping by means of the bristles
on the body, which arc not •vdbratilo. Internal organization very little known,
niey are parasites, living on the dead bodies of other Infusoria, and in infu-
sions of flesh or other animal matters. A vibration is seen at the mouth • but
whether it is produced by a filament or by cilia, is uncertain. In cl con-
stricta, transverse self-division is thought to have been seen.

Ch^tomonas Globulm. — Almost Termo, &c.; also in the dead fi-onds of

Closterium acerosum, as shown at x. 113.
1-2880".

C. co«si!r(ote. — Transparent, oblone
slightly constricted at the middle, and
having two setre or bristles. In dead
HydaUna smta. 1-5700".

spherical, of an ash-oolour, fm-nished
with setiB or bristles. It often has the
figure of 3Iona.i Guttula, but is larger;
sometimes two cluster together. In
bad-smelling infusions of animal matter
along with Pantotrichum Enchelys, Monns

674

SYSTEMATIC IIISTOBY OF THE INFTTSOHIA.

FAMILY II.— PERIDINUEA. (Part I. p. 271.)
(PI. X. 214-226 ; XII. 47 ; XXXI. 16-23.)

Infusoria without an alimentary canal, covered with a lorica, upon which ciUa
or setae are often arranged in the form of a zone or crown — hence the name.
The lorica has only one opening. Three out of the four genera have a fila-
ment besides the wreath of cUia around the middle of the body, or scattered
cilia or bristles. In only Peridinium Pulvisculus and P. cinctum have artificial
means succeeded in demonstrating the admission of food, the internal organi-
zation being greatly obscured by the mass of coloured opake granules, which
Ehrenberg called ova. A nucleus and a red stigma (eye, Ehr.) are discover-
able in some species.

The genera are disposed as follows : —

Lorica having stiff bristles or short spines — no transverse
furrowed zone

Lorica smooth or rough — a ciliated transverse zone pre-
sent

' no eye Chsetotyphla.

eye present Chaetoglena.

no eye Peridinium.

eye present Glenodinium.

Some of the presumed species have been found only in a fossil state in flint.
, Dujardin constitutes a family Peridiniens, agreeing in the main with that
of Ehrenberg, and thus narrates its characters: "Animals without known
internal organs ; enveloped in a regular, resistant, membranous lorica, which
sends off a long flagellifoi-m filament, and, in addition, has one or more furrows
beset with vibratile cHia."

The lorica would appear to have no opening ; for foreign bodies and colour-
ing matter are not seen to enter it. Several have their lorica prolonged into
hom-lilie processes ; and some exhibit a coloured point (eye-speck). They
are distinguished from Thecamonadina by the ciliated furrow or fuiTOWS.

Dujardin observes that " as the first two of Ehrenberg's genera are with-
out the furrow and vibratile cilia, and have only a filament as a locomotive
organ, they are evidently aldn to, and not separable from the Thecamonadina,
unless spines or asperities of the lorica are to be taken for cilia. Again, the
so-caUed eye-speck is not a sufficient generic distiaction between Peridinitm
and Glenodinium ; the former genus, moreover, should only include spherical
animalcules, whilst those concave on one side, and exhibiting horns, will
rightly form a distinct genus — Ceratium."

Perty coincides with Dujardin in detaching Clicetotyplda and CJmtoglena
from the Peridiniasa, and in imiting them with Thecamonadina. Cho'toghna
he merges with Pantotrichum and Lagenella in a genus which he names Chonc-
monas (p. 513). His Peridinisea comprehend three genera, viz. Ceratitm,
Glenodinium, and Peridinium: the first characterized by a ccUular lorica
prolonged into horns ; the second by a ccUular not-horned lorica ; and the
third by a structureless lorica. A reference to the figui-es of Chcctoglfna and
Chcetotyphla is sufficient to show that these two genera have no claim to be
ranged with Peridinium : the former, in particular, indicates in its stnicture
and general appearance a member of the Cryptomonadina ; and the latter , if
not a member of the same order, is certainly not one of the Peridinistia, but
probably the encysted state of some animalcule. The imperfect descriptions
attached to these genera, and the absence of sufficiently distinctive features
in their illustrations, renders their exact identification with similar known
forms a matter of difficulty, if not of impossibility. Again, the special differ-

OF THE PEiaDINIiKA.

675

ential character between Glenodinium and Peridiniwm, viz. the existence of a
red speck in the former, is worthless ; and were no other peculiarities discover-
able, the two genera should be merged into one. However, the elongation of
the lorica into hom-like processes supplies a differential character sufficient
at least to constitute two genera out of their several members. Ehrenberg' re-
cognized this indication of a division, and adopted it for his eyeless Peridiniaea,
makicig two sections: — 1, Peridiniwm proper; and 2, Ceratium, horned Peri-
dinia. Perty, we have seen, uses the same structural peculiarity as a generic
character, but, in addition, makes a third genus, marked by the absence of
sculpturing on its lorica. This basis we hold to be insufficient for a generic
distinction ; and the whole of the Peridiniaea proper appear to us reducible to
the two genera Peridinium and Ceratium; Olenodinium we would conse-
quently cancel. The rejection of Ehrenberg's views of internal organization,
and of two of the four genera he classed as Peridiniaea, renders a revised
description of this family necessary. In attempting this, we may state that
the Peridinieea are animalcules having an external, condensed, chitinous inte-
gument forming a lorica, Hned by a contractile membrane immediately invest-
ing the organic contents. No actual oral opening is satisfactorily made out ;
but in most species a deep fossa or fissure is found, from the bottom of which
a flabeUum extends, mostly twice or more than twice the length of the body.
Their figure is more or less globular or ovate ; and sometimes the lorica is ex-
tended into two or three long hom-like processes, giving the whole being a
very bizarre appearance. A deep furrow surrounds the body as a zone, and in
some species a vertical prolongation of it extends to one pole. These fui-rows
are richly ciliated ; yet the cilia do not appear confined to them, as Ehrenberg
supposed, but may, at least in one species, cover the entire sui-face. The
interior is occupied by masses of usually strongly- coloured brownish yellow, or
reddish or greenish brown, rendering the animalcules veiy opake. In some
species an oval nucleus has been seen ; and its presence is presumable in all.
A contractile vesicle has not yet been demonstrated. They multiply by
transverse, and it may be also by longitudinal fission. P. uherrimum has been
found in a quiescent condition ; and doubtless some mode of propagation exists ;
Perty endeavours to prove it is by internal germs. The zone-like ciliary
furrow may be adduced as the leading characteristic.

Genus CHl^TOTYPHLA. — Lorica silicious, hispid or spinous, destitute of
a transverse furrow or zone, and of stigma ; surface covered with little spines
and bristles, which appear stronger at the posterior portion of the body. The
lorica may be crushed by pressure, and the Httle creature within it be set at
liberty. In swimming it revolves upon the longitudinal axis, probably by
means of a dehcate filiform proboscis, or of cilia at its mouth ; no such organs,
however, have been seen. Of the internal organization, nothing positive is
known. One species has boon discovered in flint, and so closely resembles
Xanihidium, that it is often mistaken for it.

CiLSiTOTypHLA armata. — Ellipsoidal,
bro^vll, ends rounded; covered posteri-
orly with short spines, where there is a
circlet of black spots, as shown in the
end view, x. 215. The anterior cilia, or
fine bristles, are sometimes very indi-
stinct ; X. 214 is a variety in which they
are strong-ly marked. In clear water,
amongst (Jonfervie. 1-G20".

C. rts/9CT-a.— Brown, oblong, rounded at
both ends, and rough, with short bristles :
the httle spmes are scattered witliout
order at the posterior end. Foimd with
the preceding. 1-570".

C- (P) Pyrike. ~Oh\o\\g cvlindrical,
roimded at botli ends, and provided with
delicate elongated bristles, but no spines.
Fossil in flint, near Delitzsch. 1-1150"

Genus CHiETOGLENA.— Lorica silicious, destitute of a transverse

zone

576

SYSTEMATIC HISTORY OP THE INFUSOIIIA.

or furrow, but striped or covered with spines or stiff haii-s, and having an
eye-speck. The organ of locomotion is a simple flabellum. The interior
contains scattered transparent vesicles, and a brownish-green granular mass ;
a lai-ge bright spot or nucleus is also visible. Self-division not observed.

Chl^toglena volvodna. — Ovate, with
brownish-o-reen granules, and a red eye ;
between the lorica and the soft body a
beautiful red ring is visible in live spe-
cimens (x. 216, 218). Amongst Confer-

vaj at Hampstead and Hackney. 1-1150".

C. cauclata. — Hispid, ovate, with a
short tan ; granules green ; oceUus clear
red ; oral margin urceolate and dentate.
1-864". Berlin.

Genus PEEIDESTirM. — Lorica membranous, with a transverse ciliated
zone ; no eye. The locomotive organs are a filament and the zone of cilia.
In P. Pulvisculus and P. cinctum, indigo and carmine are received, and de-
monstrate the formation of vacuoles, which in P. acuminatum, P. fulvum,
and P. comutum are visible mthout having recoiu'se to coloured food. The
oral aperture is found in a hoUow near the centre, as in Bursaria. The
granules are generally of a brown or yeUowish-brown colom-, though some-
times green or even almost colourless. In P. Tripos and P. Fusus an
oval nucleus is visible. Self- division is longitudinal in P. Pulviscultis and
P. fuscum ; and, according to some observers, transverse in P. Fusus and
P. Tripos.

The structural peculiarities are sufficiently described in the chapter on
Peridiniaea (p. 271). The existence of a mouth and the entrance of food ai-e
still matters of doubt. A nucleus is probably present in all ; and the same
may be said of the flabellimi, which subsequent observers have distinctly
found in cases where it eluded the observation of Ehrenberg. " PossU Peri-
dinia," says Perty, " are not found in recent geological formations, but only
in the chalk beds of the secondary strata, in which they occm* with Xan-
tliidia (Ehr.) and Pyccidiculce."

a. Peridinia without Jwrns. — Peridinium:.

PEMDiNnrM cinctum ( VoHicella cincta,
M.). — Nearly globidar, or slightly three-
lobed and smooth, with a zone of cilia ;
not liuninous. It swims slowly, with a
vacillating and rolling motion. Amongst
Confervffi. 1-570."

Instead of the red zone noted by Ehren-
berg, there may be only a single speck,
or even it may be absent.

P. Pulvisculm. — Small, of a brown or
gi'eenish-yellow colour, and not hmii-
nous ; almost spherical, or slightly three-
lobed ; a fine filament 2^ lines longer
than the body may be observed ; nume-
rous vacuoles produced by feeding on in-
digo. Amongst Confervre, with Ch/amy-
domo7ins Pulvisculm. 1-2300" to 1-1 150".

Perty haa met with specimens having
a red speck.

P. ftcscum. — Is not luminous; oval,
slightly compressed and poLated ante-
riorly. 1-4.30" to 1-280".

P. Monas. — Very small, obtuse, with-
out horns ; remarkably social. Dinm.
1-1728". In the Baltic.

Perty suggest'* that this is merely a

yoimg stage of P. (Ceratiufti) comutum.

P. Planulum (Perty). — Bounded, broad,
rather compressed; the two segments
ec[ual. Colour bro^vn, usually a deep tint.
Under surface rather concave. 1-720" to
1-430". Its brown contents contract
after death mto a central lump. A red
speck is often seen in the posterior por-
tion. It is distinguished trom Glenodi-
nium cinctum by its gi-eater width and
deeper colour.

P. Coqnisculum (Perty). — Small ; seg-
ments very unequal, posterior one very
short and cleft. Granular contents
brownish -yellow, or red or green. An
alteration ' in figure has been seen to
ensue after death. 1-1120". Amongst
3Iarchantia 2)olymorp]ia.

P. monadicum (Perty). — Very small;
segments unequal, the posterior one
much smaller; with i-ed stigma in the
line of constriction, more seldom in the
hinder half. Molecules pale green. It
is the smallest known example in this
family. 1-1150". In a pond on Mount
St. Gotliard and at Rom.

OF THE PEKIDINIiEA.

577

P. tiberrhmm (AUnian). Nearly splie-
rical ; colour reddish-brown ; nucleus
well-defined, central. A secondary fiu--
row springs vertically from the annular
one, and terminates at the pole. A
stigma usually present at the polar ex-
tremity of the vertical fuiTOW. Swims

b. Pendinia with horns

P. (Ceratium) (?) pyrophoi-um. —
Ovate, spherical, with two little elevated
points at its anterior extremity. It is
very delicately areolate and granidai".
Fossil in the flints of the chalk fonna-
tion at Berlm. 1-570" to 1-480".

P. (CERATruM) (?) Delitiense. — Ovate,
spherical; with a little stiff point near
the middle laterally. Fossil in the flints
ofDelitzsch. 1-430" to 1-280". These
two supposed fossil Pendinia and the
Cluetotyphla (?) pyrit<e appear rather to
be sporongia of Algse.

P. (Ceratium) acuminatum. — Brown-
ish-yellow; ovate, spherical, slightly
three-lobed, and having a little pro-
cess at the posterior end. "I observed
this species," says Ehi-enberg, "in phos-
phorescent sea- water fi-om Kiel, and it is
verj' probable that the light proceeded
from this animalcule. It is the smallest
phosphorescent sea animalcule that is
known." 1-600" to 1-570".

P. (Ceratium) cornutmn (Bursaria
Ilirundinella, M. ; Ceratium Sii'undinella,
Duj. and Perty). — Greenish; not lumi-
nous; rhomboidal and rough, with one,
two, or three straight horn-like processes
in fi-ont, and a single one (often ciu'ved)
posteriorly. 1-280" to 1-140".

Perty asserts that Ehrenberg has re-
versed this animalcule in his accoimt
and illustrations, as he has likewise done
in other species of this genus ; for it is
the single horn which advances fore-
most, and indicates the anterior extre-
mity. The same author, moreover,
states that in the majority of speci-
mens one or more red specks are to be
found, generally in the posterior half,
near the middle line between the large
and small horns.

P. (Ceratium) Tripos ( Cercaria Tripos,
M.). — Yellow, brilliantly phosphores-
cent; urceolate, broadly concave, smooth,
and three-homed ; the two frontal horns
very long and recurved ; the third, or pos-
terior one, straight. Ehrenberg says,
" The power of this creature to evolve
light is placed beyond nU doubt, as I toolc
up nine phosphorescent drops, one after
the other, from the water, and I saw in
each nothing else besides a single animal-

actively by the aid of its flabeUum, and
of cilia generally disposed on the surface,
and not confined to the fiuTOWs as Ehr-
enberg represents. Occurs in a quies-
cent state. 1-1000" to 1-500". Ponds,
Phoenix Park, Dublin.

— Subgenus Ceratium.

cule of this species." It is rigid, and swims
with a vacillating rolling motion upon
the longitudinal axis. The length of the
horns is not constant, sometimes being
scarcely so long as the body, at other
times much longer, x. 219, "220, repre-
sent an under and side view. In the sea,
near Copenhagen andKiel. 1-140" ; with-
out the horns, 1-430".

P. (Ceratiutm) Michaelk. — Colour
yellow ; intensely phosphorescent. Lo-
rica ovate and smooth, with three short,
straight horns, as shown in fig. 221. A
flageUimi is not visible. In phosphores-
cent sea-water. 1-570". Named after
Dr. Michaelis, its discoverer.

P. (Ceratium) Fusus (x. 222, 223).—
Yellow, intensely phosphorescent; ovate,
oblong, and smooth. The two homs are
straight and extended in opposite direc-
tions, producing a fusiform tigTire. Ehr-
enberg states that he has seen the cilia
of the fun-owed zone, and the single fila-
ment when at rest ; also an opening or
mouth in the lorica, near the insertion
of the filament. With horns, 1-120" to
1-90".

P. (Ceratium) Furca. — Yellow, vei*y
phosphorescent ; urceolate, with three
horns ; two in front short, in the form of
a fork; one behind longer. In phos-
phorescent water, at Kiel. 1-120".

P. (Ceratium) dirergens. — Y^ellow;
cordate-ovate, smooth ; with two diver-
gent frontal acute spines, dentate at the
base ; posterior portion attenuated, look-
ing as if shortly homed. Diam. 1-576".
In the Baltic.

P. (Ceratium) macroceros. — Yellow ;
habit of P. Tripos, but more slender, and
-^vith longer homs, which are four times
the length of the body. 1-216". In
the Baltic.

P. Tridcns.— Y qWovt, with the habit
oiP._flavum, P. diver gem, and of P. Mi-
chaelis; surface granular, with three acute
frontal horns, and its posterior portion
attenuate. 1-576". In the Baltic.

P. (Ceratium) macroccras (Schrauk)
or C. longicorne (Perty) is mentioned by
Pertj', and does not appear quite equiva-
lent to C. macroceros, to which its name
is too much alike. It is the largest of

2 i>

578

SYSTEMATIC HISTOEY OF THE INFUSOBIA.

all the Peridinissa, and (says Perty) not
a variety of P. cornutum, as Ehrenberg
thought: the lorica is rather concave
belov?, and less bent than in that species.
Empty loricae are clearly areolate, and
the areoliB round. A red stigma is often
seen in the posterior half. The anterior
supports a single hom, and there are
three behind. 1-120" to 1-96."

P. areticum (Ehr.) resembles P. ma-
croceros, but is stronger, and has its
large horns all cui-ved and three or four
times longer than the body; surface
rough, with little raised puncta or spines.
Length of body, 1-48"', of entire being
1-18"'. It is phosphorescent, and found
at Kingston Bay, Newfoundland, with
P. Furca, P. Triclens, and P. clivei-gens.

P. longipes (Bailey). — Body triangular,
rough ; angles produced into very long-
ciliated processes, of which the two
frontal ones ai-e longest. Body crossed
obliquely by a ciliated groove (xxxi. 23).
St. George's Bank, New York.

P. deprcssuvi (Bailey). — Lorica ob-
liquely depressed, with one large conical
posterior process, and two smaller conical
fi-ontal processes; the latter separated
by a deep notch. Surface granular and
reticulated. Both this and the preceding
species, which were found together, were
doubtless furnished with a proboscis
when living, and, like other marine
species of this genus, were probably
phosphorescent. The form of P. depres-
sum is closely analogous to the embryo
of Nereis, whose curious changes were
studied by Lov^n (and refeiTed to in
Prof. Owen's Lectures on the Inverte-
brata, ed. 1843, p. 147). This account of
Nereis, and particularly the comparison
of Prof. Owen's figure with the Peridi-
nium depressum. (xxxi. 21, 22), led Dr.
Bailey to suspect that at least a portion
of the fonns now included in the genus
Peridinium might be imperfectly-deve-
loped or embryonic Annelida.

Gemis GLENODINIUM. — Peridinia with motile ciHa placed in a trans-
verse furrow or zone, and provided with an eye. The organization is much
the same, in other respects, as that of the preceding genus. In Q. cinctum a
flabellum is seen to emanate from the middle, and to vibrate like the wreath
of cilia. It is also probably present in the other species, though hitherto
unobserved. The lorica is combustible. Vacuoles and fine granules are
visible in aU. the species ; the former are veiy distinct in O. apiculatuin. The
red speck is in the form of an elongated or horseshoe-shaped spot, and
constitutes the essential character of the genus. Longitudinal self-division
has been observed only in O. cinctum.

Although this genus is rejected by Dujardin as iadistinguishable fi'om
Peridinium, yet Perty retains it, making its point of separation fi-om the
latter genus — which, by the way, he prefers to call Ceratium — consist in the
absence of horns to the lorica. The red speck he ignores, equally with Du-
jardin, as a distinctive character. In this way Pertj"'s Olemdinium= Peri-
dinium, without horns, of Ehr.

Glenodinium cinctum = Pmndinium
oculatum (Duj.). — Oval, or nearly sphe-
rical ; smooth ; stigma large, semi-lmiar,
and transverse. In fresh water, amongst
Oscillatoriae. 1-570", It is seen both
with and without a red speck.

G. tabidatum. — Oval; yellowish-green;
lorica gi'anular and reticidate with ele-
vated lines, but not spinous; truncate
and denticulate posteriorly, and bi den-
tate anteriorly. 1-570" to 1-430".

" The colour," says Perty, " is mostly
brown, especially in mature specimens,
and more rarely brownish-green or gi'een.
A red stigma is but rai-ely present.

G. (Peridinium') Alpinum (Perty). — The
sculpturing of the surface is indistinct ;
and very frequently there are, alternately,
colom'ed masses of granules and hyaline
spaces around the border of the lorica,

froducing a notched appearance. 1-430".
t is probably only an ^Upine variety of
G. tahdMum, in which the lorica has not
attained its perfect structure. On Mount
St. Gothard, and in Lake Lugano.

G. apicidatnm. — Oval ; yellowish-
green; lorica smooth, but vni\i hispid
fui-rows on the margin, as shown in
X. 226. The stigma is oblong, and ex-
tremities obtuse. Amongst Conferrae.
1-570" to 1-430".

OF THE VORTICELLrNA.

FAMILY III.— VORTICELLINA. (Part I., p. 277 et seq.)
(Plates XXVII., XXIX., XXX.)

Polygastriea with an alimentaxy canal, the extremities of which are distinct,
though they approximate in consequence of its curvatm-e (Anopisthia). They
have no lorica. A few are solitary ; but the majority are congregated on
pedicles, which often assume elegant ramose forms, Hke Httle trees, an ani-
malcule surmounting and terminating each branch or pedicle. These arbo-
rescent clusters are the result of imperfect self-division.

The animal organization of this family is very distinct. The entire sur-
face of Stentor is covered with vibratile cilia ; but in other genera they are
mostly disposed in the form of a wreath around the head. In some genera,
as in Vorticella, Oarchesium, and Opercularia, longitudinal and transverse
muscles are seen; the mouth and discharging opening, both lying in the
same lateral cavity, have been demonstrated in all. Self-division takes
place in aU the genera, but is least frequently obsei-ved in Zoothamnium :
when it is imperfect, not affecting the pedicle, it gives rise to branching
foi-ms. Gemmation is also frequent in most genera. From their great irrita-
bility when approached, may be presumed the existence of a system of sensa-
tion. Colouring matter is received by aU the species ; eye-specks are wanting.

This family affords (in form indeed rather than in stractiiral homologies) a
connecting link between the Ciliata (Polygastriea) and Rotatoria.

The following curious particulars are appended by Ehrenbei'g, who re-
garded them as indicative of an act of transformation : —

" The Vorticella developes a pedicle ; divides (casts its exuvia) ; developes
posterior cUia ; loosens itself from the pedicle, rambles about ; di'aws in
(after shedding a second exuvia) the posterior cilia, sheds them, and firmly
attaches itself, preparatory to putting forth another stalk. This cycle of
phaenomena is repeated again and again, and possesses high physiological
interest ; it is a returning circle of transformations — a return to an early
condition, similar to that of a butterfly, if it suddenly lost its wings and an-
tennse, and again became a caterpillar, in order once more to return to the
state of pupa and butterfly — or to that of an old man becoming a child, in
order to run again his course of life anew." (See Part I. p. 277 et seq., and
p. 586.)

The YorticeUina live for the most part in sweet water, fresh or marine,
attached to plants or shells, to Crustacea, to the larvfe of insects, &c. There
are, however, a few Vorticellce and Scyphidece produced in infusions, and even
in fetid ones.

This accoimt of the organization of YorticeUina from Ehrenberg requii-es
considerable alterations and corrections from the present state of our know-
ledge of these beings. In Part I. (p. 277), their organization has been largely
considered ; yet a few notes here may not be misplaced Any definition of the
charactei's of the group of genera comprehended in this family by Ehrenberg
would be unsatisfactory, inasmuch as some forms are included which have
no sufficient affinity. Ehrenberg represents the YorticeUina as having a
polygastric alimentary canal so curved that its two ends are conterminous.
Now the supposed storaaclis, as displayed by using coloured food, were merely
vacuoles ; and no continuous aUmontary canal penetrates the interior, as sup-
posed, but only a digestive tube or oesophagus of variable length, terminating
abruptly in the interior by an open mouth. The ciliary apparatus of the true
YorticeUina is more complex than appeared to Ehrenberg,— the head of the
animalcules being tenninated by a peristom or free edge, oftentimes thickened
and everted, beyond wluch a ciliated disc supported on a very retractile and

2 p 2

580

SYSTEMATIC HI8T0KY 01? THE INFDSOEIA.

highly sensitive pedicle can be protradcd. The portion of the ciliary spiral
outside the vestibuUim is not of equal length in all Vorticellina : in many,
e. g. Vorticella, Oarchesium, Zoothaninium, Scyphidia, Tncliodina, some species
of EpistyUs, &c., it describes scarcely more than one circuit round the disc,
whilst m Opercularia articulata and EpistyUs Jlavicam it runs round the disc
three times ; in other species intermediate lengths occur. The ciLLarj' wreath,
moreover, consists of a double row of cilia : those of the outer one are usually
somewhat shorter than those of the inner, and though inserted upon the
margin nearly in the same line as the others, yet they are set at a different
angle, and apparently far more strongly bent outwards. In the vestibulum
and oesophagus the cilia appear to stand in a single row. The peristom usually
bears no cUia. There is no sufficient proof of the existence of muscles of the
same type as those of the higher classes of animals. The contractile vesicle
is single and cii'cular ; the nucleus sometimes oval, but often elongated and
band-like. Besides fission and gemmation, true propagation by living germs
or embryos, developed in the coui'se of more or less complete transformations,
affords an additional means of perpetuating and extending the several species.
The genera are distributed as follows : —

Body without stalk

Tail absent

Body covered with cilia Stentor.

Body smooth, cilia anterior Trichodina.

Tail present TJrocentrum.

Body stalked — often
branched like a tree

Form of stalked
bodies similar "

f Stalk flexible, f^^P^^ Vorticella.

deflection spiral It, i j n ^. ■

•■ [ Branched Carchesium.

Stalk inflexible EpistyUs.

Bodies of ^if- 1 ^'^^^ Opercularia.

\^ ■■■ [ Stalk flexible, deflection spiral... Zoothanmium.

Of the several genera named and distinguished by Ehrenberg, two only
are accepted by Dujardin, viz. EpistyUs, with a rigid pedicle, and Vorticella,
with a contractile stalk, simple or branched. He places Carchesium with the
latter, maintaining that a generic character is not to be found in the simple
or branched condition of the stalk alone, when the bodies are similar. More-
over, he failed to meet with animalcules having the characters assigned to the
genera Opercularia and Zoothamnium by Ehrenberg. A third genus, imder
the name of Scyphidia, is established by him for the sessUe species ; whilst
a fourth, Vaginicola, comprises all those species invested with a membranous
sheath, and corresponds, in its constituent species, to the family Ophiydina
(Ehr.) after the exclusion of Ophrydium.

Perty makes a different distribution of the VorticeUina to that proposed
by Ehrenberg. Like Dujardin, he rejects the genera Stentor and Uroccntnm,
and transfers them to a family Urceolarina. On the other hand, he adds
Scyphidia of Dujardin to the true Vorticellina, and makes no mention of
Carchesium, Lachmann is another writer who rejects Urocentrinn from the
Vorticellina. Stein points out vai'ious defects in Ehrenberg's grouping of
Vorticellina ; and whilst he would, on the one hand, detach from it Stentor,
Trichodina, and TJrocentrum, he would, on the other, associate with it the
several sheathed genera which form the family Ophrydina, xiz. Ophryditnn,
Vaginicola, Tintinnus, and Cothumia. Apart from these clianges in the distri-
bution of admitted genera, he adds two new ones. Lagenophrys and Sjyirochona,
remai-king of the foi-racr, that, in its fi'cc condition, it constitutes a transi-

OF TKE VOBTICELIINA.

581

tional form between the radiated type of Vorticellina and the bUateral one of
Oxytrichina and Eiiplotina. Lastly, Lachraann states that Trichodina and
Urocenti-um are not Vorticellina, and makes Slentor the representative of a
new family, which he calls Stentoiinae. In this proposed new family he
includes besides Stentor, a new genus (Chcetospira), Spirostomum, and a
fourth genus which he has merely referred to without naming or de-
scribing it. In the above plans of classification there is this in common,
that the genera Stentor, Trichodina, and Urocentrum are excluded from
among the Vorticellina, an exclusion warranted by their difference of organ-
ization and general characters. At the same time we are of opinion that
the association of the Ophiydina with the VorticeUina is not correct in a
systematic point of view, the existence of external sheaths being a well-
marked and sufficiently distinctive character, although the homology in organ-
ization is otherwise, in every essential point, very close and striking. Pro-
bably Tricliodina and Uy-ocentrum should constitute an allied family or a
sub-fanuly of Vorticellina ; Stentor the type of a second family ; whilst the
remainder of Ehrenberg's group, viz. Vorticella, CarcJiesium, Epistylis, Oper-
cularia, and Zootliamnium, might be called the trae VorticeUma. The new
genus Spirochona, again, stands apart by so many peculiarities that it cannot
be included within either of the groups proposed, and must be regai'ded as
the (at present) sohtary type of a new family, having the internal organization
of Vorticellina, but destitute of their peculiar ciliated head. In fr-amrag his
generic and specific distinctions, Ehrenberg made use of characters of no real
value, — such, for instance, as the occiu'rence of similar and dissimilar bodies
(zooids) on branching stems otherwise alike, the height of the stem, the thick-
ness of its branches, and the dimensions of the attached animalcules.

The family Urceolarina (Duj.) is thus characterized: — " Animals variable
in form, changing from a trimipet- or a hemispherical to a globular form ;
ciliated throughout, with a fringe of much stronger cUia along the upper and
anterior margin of the body, continued as a spiral coil into the oral cavity,
which is on the same border. They present the ordinary swimming move-
ment, and can for a short time arrest their progress by fixing themselves by
their posterior extremity to external objects." " This family," observes
Dujardin, connects the VorticeUina with the Bursaiina, and includes the
genera Stentor, Urceolaria {Trichodina, Ehr.), Ophrydium, and Urocentnim."
The last-named genus is treated as very doubtful. As already seen, Perty
adopts this family Urceolarina, but mochfies it by rejecting Ophrydium, and
QiCldiii^ /S^tTOStoTytuTyt,

Genus STENTOK (XXVIII. 16, 17 ; XXIX. 8).— Animal without pedicle,
free, or attached by the posterior extremity of the body, wliich is conical
although it admits of very considerable modifications of form ; it is entii-ely
covered with cilia ; a wreath of larger ones sumounts the head. Ehi-enberg
considered the longitudinal striae along the body, and the cii-cular ones at the
anterior part, muscular fibres. The anterior cUiaiy wreath is coiled in a
spiral manner about the head ; in some species a row of longer cilia extends
from the mouth, in a fringe-like manner, to the middle of the body.' The
Stentors increase by self-division, which is either longituchnal or oblique
The nucleus is l)and-hke, moniliform, or round. The contractile vesicle is
large, round, and placed on a level with the ciliaiy wreath, close to the
oesophagus ; it gives off, above, an annular branch, which surroimds the head
of the ammalcule just beneath the fringe of cUia, and below, a straieht
branch extending to the posterior extremity of the animalcule (XXIX 7^
The anus may often be perceived for a considerable time both before "and
after the discharge of matters. It is situated on the back, close beneath the

682

SYSTEMATIC HI8T0EY OE THE INFUSOEIA,

ciliarj^ circle. The Stentors are among the largest of the Infusoria, and all
the species are visible to the unassisted sight. They are best examined
between the plates of a large live-box, a portion of the decayed stem or leaf
on which they are found being put in with them.

" It is," says M. Dujardin, " in the Stentors where we can view the several
supposed internal organs isolately, that new observations wiU make known
theu" real nature."

They are exclusively found in fresh standing water, or between plants
where the water is still. Some of them are colourless, others gi-een, black,
or clear blue.

This genus gives name to the family Stentorina proposed by Lachmann
and others, and, in the classification of Dujardin and Perty, is a member of
the family Urceolarina (p. 581).

Stentok Miilleri (xxvm. 16, 17). —
This is the " white funnel-like polpye "
discovered by Trembley ; it is large, the
crown or wreath of cilia intewupted, and
the lateral crest or fringe indistinct;
when outstretched it is trimipet-shaped,
but in its contracted state is ovoid ; and
dming division, or when the water
around it evaporates, a muco-gelatinous
mass is thrown out as an external cover-
ing. When several are swimming in a
glass vessel, they will gradually congre-
gate, and select some particular spot,
and then attach themselves, evincing, as
Ehrenberg imagined, not only a degi-ee of
sociality, but of mental activity. These
animalcules receive coloured food very
readily ; nucleus moniliform. Upon
Lemnse and other water-plants, even
under ice. Size, stretched out, 1-20" ;
conti-acted, 1-120".

Ehrenberg refeiTed to the exudation of
a mucilaginous coat as the prelude to the
death of the Stentor; but, as Cohn has
shown (Zeitschr. Band iii. p. 263), it
takes place in perfectly healthy and live-
ly animals, and is an instance of the
widely-pei-vading process of encysting.
This observer, indeed, tells us that, when
the conditions of existence become un-
favourable, animalcules previously at-
tached by their tapering posterior ex-
ti-emi^, as by a sucker resembling tliat
of a leech, n-ee themselves from their
capsular envelope and swim away, dis-
playing then a brush of cilia at the end
of the taU. The notion of a sentiment
of sociality and of mental activity, sm*-
mised by the Berlin microscopist, de-
mands the exercise of a powerfid imagi-
nation to realize it. Dr. Wright most
kindly notices, in a letter to us, that
Stentor Miillcn always secretes a gela-
tinous case into which it can retract.
As the zooids divide they form a gela-
tinous mass, which is attached to weeds |

and often to the suiface of the water,
from which 10 or 15 Stentors aggregated
together may sometimes be seen hanging
with then- heads downwai'ds. The ex-
ternal gelatinous sheath ia Stentor and
other VorticeUina and Ophrydina, Dr.
Wright proposes to caU the "coUeto-
derm," as the homologue of the gela-
tinous matter covering the polj-pidoms
of the Hydroidae.

S. Haseln (x. 233, 234). — In form,
size, and crest, this species resembles the
preceding, but is of a more distinct
yellowish-white colour. The nucleus is
long, ribbon-shaped, and not monilifonn ;
the contractile vesicle (seen at *) circidar.
Common in summer; upon decaying
plants, &c., in standing water. 1-140";
extended, 1-24"

The monilifonn iatestine represented
by Ehrenberg was very probably the chain
of vesicular dilatations of the presimied
vascidar system connected with the con-
ti-actUe vesicle, and which is largely de-
veloped in the Stentors, on one side of
the body, as a canal extending from a
circular sinus aroimd the head. Dujardin
regarded this species as simply a variety
of S. MiiUeri ; and there is no apprecia-
ble character truly distinctive between
them.

S. ccendeus (xxix. 8) resembles, exte-
riorly, the two preceding species ; but its
granules are blue, nucleus ai'ticulated and
chain-like (monilifonn). It is tnimpet-
shaped when extended, ovoid when con-
tracted; white or semi-transparent, ex-
cept when coloured by food. The lateral
crest and frontal wreath are continuous.
When kept in glass vessels, they often
fix themselves to the sides in clusters.
They ai-e best examined when placed in
a lai'ge live-box ; a magnifying power
of 100 diameters is sufficient Amongst
Vaucherire. 1-480".

Except its mucli smaller size, there

OF THE VOBTICliLLINA.

583

seems nothing to sufficiently distinguish
it from the preceding species; for the
bluish hue ot the gi-anules cannot be
admitted as a characteristic. Even the
diflerence in dimension is no satisfactory
indication of a distinct species ; for the
smaller animalcule may be but a younger
specimen of the larger.

S. polymoi-phtis (xxix. 7) resembles
the preceding in fonn. Granules of a
beautiful green colour; nucleus articu-
lated and chain-like; lateral crest in-
distinct; frontal wreath of cilia inter-
rupted. This species wUl not receive
indigo readily. Transverse self-division
obseiwed. Upon stones, decayed sticks,
and leaves, in standing water. 1-120" to
1-24".

Lachmann {A. N. H. 1857, xix. p.
225) seems to intimate that this species
is equivalent to S. Miilleri and S. Rceselii.
Both in this species and iu 'S'. ccsnileus
Eckhard has described reproduction by
internal germs or embi-yos. Between the
cilia, disposed in spiral series, single long
hairs, similar to those of many Turbel-
laria, are found, according to the testi-
mony of Lachmann.

S. iynms. — Less than the preceding;
gi-anules yell owish -green ; siu'face bright
yellow or vermilion ; nucleus spherical ;
lateral crest absent; frontal wreath of
cilia inten-upted. Found by Ehrenberg
upon the water-violet {Hottonia palus-
tris). 1-72".

S. nic/e)' {Vorticella nigra, M.). — Small,
of a dark brownish-yellow or blackish
colom- ; granules olive-coloured ; nucleus
spherical ; lateral crest absent ; frontal
wreath of cilia continuoiLS. This species
is often so abundant that it coloiu'S large
pools, in tm'fy hoUows, of a dark blackish
hue, resembling an infusion of coflPee.
The swimming movement of this species
is readily seen (as in the others) with
the naked eye. 1-96".

S. castaneus (Wright). — A species
named in a letter to us by Dr. Wright,
of which the only particulai's given ai'e
that it is of a dark chestnut coloui-, and
that it selects the tops of the stems of
Myriophyllimi as its home, and glues all
the young leaflets together with a ball
of jeUy, within which a crowd of zooids
is imbedded.

Genus TRICHODIlSrA.— VorticeUina destitute both of tail and pedicle,
distinguished from the preceding genus by the general surface of the body
being destitute of cilia. They possess a vibrating wreath of cilia anteriorly,
on one side of which is a simple, not spiral oral opening. They are mostly
disc-shaped or conical. T. Pediculus has the posterior end abraptly trun-
cated like the front, and also surrounded vdth a wreath of curved setee, which
it employs when crawling, in the manner of feet. In T. tentaculata there is a
kind of proboscis. Coloui-ed food is received by T. Pediculus and T. Grandinclla.
A kidney-shaped nucleus is seen in T. Pediculus. Many species live pai'asitic
on freshwater MoUusca, or Zoophytes ; but others have been found free in
sea-water.

This description by Ehrenberg conveys a very imperfect conception of the
real structure and appearance of Tncliodina. The follomng account and
figures from Stein will, however, supply its deficiencies : — " The genus Tricho-
dina consists of naked and highly contractile animalcules, subject to very con-
siderable variations of form in the direction of the long axis. Their usual
figure is that of a tinincated cone, much and suddenly distended posteriorly
and surmounted at their wider extremity by a wreath of cilia, which corre-
sponds with the posterior ciliary wi-eath in other VorticeUina. The other
abruptly tnmcate extremity is furnished witli an apparatus of liooks (XXIx'
15), whereby the animal can attach itself to other bodies. The mouth is
circular, and placed on one side of the body, at a greater or less distance from
the anterior extremity ; it is furnished with a special zone of cilia to aid in
the introduction of the abnientary particles." (It is, however, not circular
but a spu-al fnnge of ciUa, as Dujardin stated.) The genus Trichodina fEhr \
agrees m the mam with f/i-ceo7«r/a (l)uj.). v ^-^

Of the several species enumerated l)y Ehrenberg, Stein asserts that two
only arc admissible, that the other three are foreign to the genus, and very

SYSTEMATIC lUSTOUi: Oi' TiUi JLNFUSOHIA.

incompletely observed beings. Thus T. Qrandinella and T. vorcuc appear to
be merely the embryos, or otherwise the gemmae, of Vorticellina, whilst T.
tentaculata is imperfectly known, and will probably always remain a ques-
tionable organism. Further, this author would unite Tricliodina \\ith Uroeen-
trum into a subfamily of Vorticellina.

Lachraann {A.N.H. 1857, xix. p. 119) agrees with Stein in limiting the
genus to the two species T. Fediculus and T. Mitra, and in rejecting the
rest as not Vorticellina at all. According to him, Trichodina G-randinella and
T. vorax are rightly referable to Halter ia (Duj.).

Trichodina tentaculata (x. 227). —
Discoid, destitute of the wreath of cUia,
but with a fasciculus of vibratile cUia,

and a styliform proboscis. 1-280

T. Pediculus {Cyclidium Pediculm, M.)
= Urceolaria stellina (Duj.) (x. 228-230;
XXIX. 14, 15, 17). — Depressed, urceolate,
and discoid, with a wreath of vibratile
ciha anteriorly, and another of short
moveable imcinate cilia, or hooked setae,
posteriorly. Ehrenberg remarks, " I have
led this species many times with indigo,
and have seen numerous stomachs filled
with the blue matter. It always rims
upon the back, where there is a wreath
ot 24 to 28 mobile hooks (or uncinate
cilia), and has the mouth and vibrating
wreath of 48 to 64 cilia directed up-
wards." It appears to feed upon the
little granules oi the body of the Fresh-
water Polype {Hydra, ' Microscopic Ca-
bmet,' pi. vii.) (Figs. 228 and 229 are side
views, attached to a portion of a poh^e ;
fig. 230 is a top view). 1-570'' to 1-280".

T. Pediculus (xxix. 14-17) is described
in much detail by Stein (^Infusionsthierc,
p. 175). "It has," he writes, " a turbau-
shaped body ; the truncated conictal an-
terior segment is moi-phological with the
rotary organ of typical Vorticellina, and
is shorter than the very ventricose and
expanded posterior segment, fi-om which
it is separated by a deep anmdar con-
striction or furrow, occupied by a wi-eath
of vibratile cUia of less length than those
forming the posterior zone. The oral
aperture is seated in this furrow, the cilia
of which are active in impelling food
into the mouth. The posterior ciliaiy
zone is parallel with the one in front,
j ust desci-ibed, and occupies the posterior
surface of the hindmost segment of the
body, near to the line of attachment of
the circlet of imcini, as can be best seen
when the animal is dead. It is this zone
whicli principally serves for locomotion.
The anterior segment can be retracted,
and even vanish, by being taken up into
the posterior, when the figiu'c becomes
cylindrical, with abruptly truncate ends.
The posterior segment niso confrncts it-

self considerably, and in so doing pre-
sents several annular folds. The margin
of the truncated extremity, wliich is
muchsmallerthanasection inade through
the middle of the posterior segment, is
fringed by a fii-m cai'tilaginous or horny
ring, having both on its outer and inner
face a series of uncini, placed at equal
distances from each other, and some-
what constricted behind the origin of
each pau". The inner row of imcini he
in the same plane as the posterior sur-
face; but the external row are strongly
tiuned oufrn^ards and backwards. Besides
these is a structure not hitherto described,
consistiag of an annular, transparent,
elevated rim or collar, often of a slight
yellow colom', and of a homy aspect,
placed aroimd the outer margin of the
corneous ring, above the base of the
outer series of unciui. It is extremely
flexible, du-ected obliquely outwards, and
marked by very fine lines. The circlet
of hooks is at once dissolved by acetic
acid, whilst this structure remaias ; and,
on the other hand, the whole prehensile
apparatus disappears when the animal
is put into alcohol." The structure of
Tnchodina, as now unfolded by Stein,
was both imperfectly and erroneously
conceived by Ehrenberg.

The long diameter of the largest Tri-
chodina Pediculm Stein met with was
1-360"; the transverse diameter was
about the same. Small specimens oc-
ciu'rcd of only half the size, out complete
in all the details of organization.

T. voraa:. — Oblong, cylindrical, or
slightly conical ; anterior part convex,
and crowned with cilia ; the back rather
attenuated and smooth. 1-570".

This and the next species are, from
their dissimilarity to T. Pediculus, re-
mo^•ed bv Dujardin to another genus he
names Hnlferia—ihc two being equiva-
lent to HaltcriaGraiidinella, which again,
in Stein's opinion, is the embryo of an
Acinetiform phase of a VoHiceUa.

T. Grandim'Ua (M.).— Neariyspbencal ;
sharply attenuated posteriorly ; a wreath
of cilia stu-rounds the truncated fore pai't.

OF THE TOKTICELLHTA.

585

This species is liable to be mistaken, by
au inexperienced observer, for a free Vor-
ticella ; its true distinguishing chai-acter
appears to be its open weath of cilia.
1-1500" to 1-860".

T. 3ntra (Siebold) (xxix. 16).— An-
terior segment elongated, cylmdiical,
much longer than the slightly wider and
more discoid posterior segment, into
which it gradually expands. The outer-
most margin of the posterior segment
has a similar wi-eath of cilia to that of
T. Pediculiis ; but the prehensile appa-
ratus diSers in the two species. In T.

Mitr'a the undidating cartila^nous ring
is not ai-medwith hooks, but has only
the annular membrane, precisely like
that in the other species, except that
it is relatively smaller, less distinctly
striped, more colourless and transparent,
and therefore more readily overlooked.
Between the two segments is the deep
furrow in which the mouth is placed,
from which a row of cilia extends to-
wards each end at right angles to the
posterior ciliary zone, and is homologous
with the anterior wi-eath of cilia of T.
Pediculus.

Genus UROCENTRUM (X. 231, 232).— Free, with a taH-like style, but
no pedicle, and no ciha, except a wi-eath anteriorly ; oral aperture simple.
SeLf-division transverse. Ehrenberg thinks the eyes, which Miiller supposed
he had seen, were most probably the traces of cilia, which he appears to have
overlooked.

Ubocentrtjm Turbo (Cercaria Turbo,
M.) (x. 231, 232).— Hyahne, ovate, ti-i-
lateral, with a style, or setaceous tail,
one-third of its length. Ehrenberg says,
" The little tail is not a separable Vor-

ticella-stalk, but an ai'ticidated style on
the back — perhaps a foot." WithLemnae
and Confervse. Fig. 232 a dorsal, 231 a
side vieAV. 1-430" to 1-280".

Genus VOETICELLA (XXVII. 1-5).— Crowned with cilia anteriorly;
stalked when young, but at a later period, and also after self-division, sessile.
The shape of the zooids, when stalked, is similar ; the pedicle can be suddenly
deflected spirally, by means of the long muscle within it, but it is never
branched. At certaia periods a second wreath of cilia is produced at the
posterior part of the body. Not only, according to Ehrenberg, can numerous
stomach-ceUs be seen, but likewise the gradual passage of the food onwards,
in a twining sort of intestinal canal, though this is not easily observed, on
account of the periodical deflection of the pedicle. However, in the genera
Epistylis and Opercularia, whose pedicles are comparatively motionless, the
nutritive apparatus may be much more perfectly investigated. The mouth
and discharging orifice are separate, but lie in the same hollow, at the anterior
margin. The granules are variously coloui-ed, and constitute, in Ehi-enberg's
language, clusters of ova ; nucleus elongated, contractile bladder round. The
animalcules are andi'ogynous. The supposed increase by the growth of young
animalcules out of the pedicle (or of gcmmas), hke flowers on the stem of a
plant, has arisen from erroneous observation. When the animalcule loosens
itself from its pedicle or stalk — a circumstance which, says Ehrenberg, " takes
place at certain periods — the stalks die, or disappear, just like the shells of
crabs, or as the nails and bail-." The muscular fibre within the stem rcquii-es
stops, or an achromatic condenser, under the stage, to render it distinct.

The Vorticellce being of so considerable a size, and easily procurable, have
formed the subject of mimerous investigations into their organization • but
yet no obsei-vers have been able to coincide entirely with the %iews of
Elirenberg. Among the most recent researches are tliose of Prof. Stein
len fully put forward in the general history of these animals'
must refer (see p. 277 et seq.). Suffice it to say that the
winding intestinal canal, the distinct stomach-cells, the clusters of ova the
androgynous nature mentioned in the above account from Ehrenbere of thp
internal organization of VorikMm, have, not only in Stein's opinion but in

which have been
to which we

586

SYSTEMATIC HISTORY OF THE DrPUSOEIA.

that of nearly every other naturalist, no existence ; the appearances so inter-
preted are explicable in a different manner. Adopting the results of recent
discoveries, the following descriptive characters may be laid down.

Body bell-shaped (campanulate), supported on a highly contractile, un-
branched pedicle or stem, and surmounted at its wide upper extremity by a
dilated and somewhat everted margin, or " peristom." The wide anterior
extremity is closed by a " disc," fringed with cUia, which commence on one
side of a depression or fossa in the peristom, called the vestibulum, whence
they ascend to surround the disc, and after continxiing down its sides or
" stem," enter the mouth, and thence return to their starting point, thereby
completing a spii-al ciliary wreath, or rotary apparatus, which serves by its
vibrations to di'aw food inwards to the mouth, and, when the animal detaches
itself, as an organ of locomotion. The disc may be slightly elevated above
the peristom, but less so than in other tnie Vorticellina ; when so elevated,
the ciliary apparatus is said to be expanded. On the other hand, it may be
withdrawn under cover of the peristom, the ciha disappearing from ^iew ;
and Avhen more strongly contracted, the whole disc is so drawn within the
body that the entire appearance of the anterior extremity or head of the
animal is lost, its ciliary mechanism being so inverted that it appears in-
ternally like an irregular sigmoid cavity, in which the cilia may possibly be
distinguishable, whilst the peristom is itself completely closed in upon the
whole. In this state of complete contraction the Vorticella resembles a shut
ovoid sac. Except the head, the rest of a Vorticella is destitute of cilia.
The fossa lying between the sides of the ciliary disc and the peristom is the
vestibulum, into which both the oral and anal outlets open, within a very
short space of one another. The mouth opens below into a ciliated pharynx
or oesophagus, which is extended a considerable distance into the interior as
a digestive tube, terminating, it would appear, suddenly by an open end.
The food received at the mouth is transmitted thi-ough the oesophagus, and
is formed at its extremity, with the aid of water, into a globule or vacuole,
which is pushed onwards by the vis d tergo in a circular course towards the
anal outlet. Besides molecules and granules derived from food (vesicular
bodies composed of oily or other matters), there are always present in the
interior a round contractile vesicle and an elongated curved band-like nucleus,
often with several minute clear spaces or nucleoli. The vesicle is usually
placed near the lower end of the digestive tube, and the curved, horseslioe-
shaped nucleus lies across at the posterior third of the animalcule. Tlie
Vorticellce multiply by longitudinal self-division, and by the growth of gemmse
from their base, and propagate by the resolution of the nucleus, after encyst-
ing itself, into numerous Eu(jleiia-]ike or Monadiform beings, and, according
to Stein, by cUiated embryos through the medium of a previous convei-sion
into Acinetce. The new beings formed from fission or gemmation ai'c at fii'st
in a contracted condition, and on their detachment are found to be furnished
with a posterior circlet of cilia to seiwe as a means of locomotion until they
affix themselves and proceed to develope a pedicle, after which it disappcara,
and the ordinary ciliary wreath of the head unfolds itself. Indeed, even
when these processes of multiplication ai-e not in operation, a VorUcfUa
can detach itself and leave its stalk, or smm away with, its pedicle Avlicn
loosened from its hold.

The pedicle is remarkably contractile, drawing itself into a close coil with
extraordinary rapidity, and again uncoiling itself with equal quiclmcss, regu-
lating these movements by external conditions, as thougli possessing con-
sciousness and wUl. The pedicle is a hollow tube, contaijiing a thread or
band within it, to wliich its contractile power is due.

OF THE VOETICELLINA.

587

VoRTiCELL A nebuUfera ( V. nebuKfera et
V. ConcaUaria, M. ) . — Body campamilate ;
its base, to which the pedicle is affixed,
may be either conical or hemispheiical,
according to its state of expansion or
contraction ; the pedicle or stalk is about
five times the length of the body, and
can fonn as many as ten coUs. These
creatui'es usually congi-egate together, —
though each is independent of its neigh-
bour ; for on the approach of any foreign
body to one, it withdraws, by coiling up
its pedicle, while the others remain
sti'etched out in search of food. An am-
plification of 300 diameters is necessary
to exhibit the cilia. Dming longitudinal
self-division the body becomes broader :
gemmation takes place from one or other
side, close to the insertion of the pedicle.
Abundant, appearing like a white film,
on the stalks and roots of Lemnse and
other water-plants, even in winter under
ice. 1-570" to 1-280"-

This is one of the species of Vorticella
in which Stein believed he proved the
development of an Acineta from the
encysted animal, and also, under other
circumstances, the generation of a brood
of yoimg Monadiform beings or geinis.

V. citrina (M.). — More hemispherical
than the preceding, and the frontal mar-
gin more expanded. Upon Leninae,
rarely with the former species. 1-430"
to 1-210"; stalk 3 to 4 times that length.

Perty speaks of this species as having
a stilF stem, and apparently closely re-
lated to the genus Stentor. Dujardin
adopts this specific name for a Vorticella
defined as being very variable in form,
often campanulate, rarely conical, having
a wide projecting border, variously con-
torted or irregular.

V. microstoma (xxvn. 1-6). — ^Whitish
grey, ovate, naiTower at the ends ; frontal
margin not expanded or campanidate;
during contraction the animal is annu-
lated; multiplies by longitudinal and
transverse (?) self-division, and by gem-
mation. In stagnant water. 1-2.300" to
1-240"; stallc six times longer than the
bodv.

l^his species was the subject of the
minutest investigations by Stein, who
not only represented it as becoming
encysted, but also as being either trans-
formed into an Acineta or Actinophrys,
from which a ciliated embryo is deve-
loped, or as giving origin, -vvitliout such a
metamoi-phosis, to a multitude of germs.
He remarks on the immense range of size
seen among different examples of this
animalcule, viz. from 1-300" to 1-3600"

(xxvii. 5), the smallest equally with the
largest exhibiting the same structure.
The figm-e he describes as pear-shaped,
the anterior half contracted ; the ciliated
disc slightly everted, not campanulate;
rotary organ small, and elevated _ but
slightly above the peristom. He objects
to Dujardin's imion of this species with
V. convallaria, under the name of V. in-
fusionum, as erroneous, the two being
perfectly distinct beings.

V. Camijanula {VoHicella lunaris, M.)
(xxrx. 1). — Hemispherical, not annu-
lated, bell-shaped, with the frontal mar-
gin broad, ti-uncated, and not expanded.
Colour whitish-brown. This species ap-
pears like a thick bluish fihn upon
water-plants, and the single animalcules
are discoverable with the naked eye.
1-120"; stalk seven times longer than
the body.

Perty adopts MiUler's name V. lunaris
for a species which he considers equiva-
lent both to V. CatnpaniUa and V. patellina.

V. hamata. — Small, ovate, hyaline,
attenuate at both ends ; body obliquely
attached to the pedicle. 1-570".

V. chlorostigma (Vorticella fasciculata,
M.). — Green, ovate, conical, campanu-
late, and annulated ; frontal margin
(peristom) expanded. Often covers
grasses and rushes with a beautiful
green layer. 1-240"; stalk five times
the length of the body.

V. patellina (M.). — Hemispherical,
campanulate ; frontal portion very much
dilated ; its margin gi-eatly expanded, and
often turned backwards. 1-480"; stalk
about seven times the length of the body.

V. cotivallaria ( V. crateriformis, citnna,
geinella, globularia, hilaris, nasuta et trun-
catella ; Enchelys Fritillus ; Trichoda gy-
rinus, M.). — Ovate, conical, campanidate,
annulated; hyaline or whitish; frontal
portion dilated, its margin slightly ex-
anded. This appeai-s to have been the
rst infusorial animalcule discovered.
Leeuwenhoek, the discoverer, foimd it
in stagnant rain-water, at Delft, in April
1675. It occurs in considerable abun-
dance upon tlie surface of vegetable in-
fusions, with V. microstoma, from which
it is distinguished by its broad front,
which gives to it a bell-shaped or cam-
panulate appearance. Carus, in 1823
fancifully represented it as arising froni
spontaneous generation in oil, or from
an accidental mixture of oil colour and
spring-water. It has been described
under various names by diflferent natu-
ralists. 1-430" to 1-24" ; stalk six times
its length.

588

SYSTEMATIC HISXOUT OP THE INFUSOEIA.

This well-known animalcxile is usually
found attached to extraneous bodies in
water ; such as the leaves of duck-weed,
small aquatic shells, clusters of the ova,
or the larvEB of insects; an example of
the latter is shown in the Mici-osco])ic
lUustrutions, fig. 30, where it may be
considered as a parasite, or rather an
epiphyte. As, when fully developed,
it is mostly attached to some sta-
tionary object, it affords many facilities
to the microscopist for observation, and
forms a good object also for ascertaining
the defining power of his instrimient,
and his expertness in its management;
for much of the clearness in structure
will depend on the manner in which he
manages the illumination. If this be not
attended to, and the instrument has not
sufficient power and penetration, it vdll
exhibit only two cilia instead of a cir-
cular row; indeed this animalcide is
described and drawn in this manner by
the old authors, — an error which recent
improvements in the microscope have
demonstrated.

Y.picta. — Ovate, conical, campanulate ;
frontal portion dilated, and its margin
slightly expanded. The pedicle is very
slender, and curiously marked through-
Genus CAECHESIUM (XXX. 9).

out its length with red dots. 1-1150" to
1-570" ; stalk four to five times as long.

Perty treats V. lunaris, V. fasciculata,
and V. cirrata of Midler as distinct
species, instead of accepting them as
varieties of others named by Ehrenberg ;
but he fails to give the characteristics
necessary to then- establishment as such.
It is to be remarked, however, that V.
lunaris and V. fasciculata are, he is in-
clined to believe, merely varieties of the
same species.

Vorticella Amimlla (Midler) is treated
by Laclimann as the representative of a
new genus, as yet unnamed, belonging
to the Stentoiinse (A. N. H. 1857, xix.
p. 128).

V. infusionum (Duj.) is not equivalent
to V. microstoma and V. Cotwallaria, as he
represented it to be. He describes it as
commonly ovoid or nearly globular, trun-
cated at the head, with a slightly pro-
jecting border. The pedicle is very
fiexible, its sm-face striated obliquely.

V. ramosissima (Duj.) = Carcliesium
polypinum (Ehr.).

V. Arbuscula (Duj.) = Zoothamnium
Arhuscula (Ehr.).

V. kmaris (Duj.)= V. Campanula and
V. patellina (Ehr.).

Distinguished from the preceding

genus by the spirally flexible branched pedicle. The bodies (zooids) upon
the pedicle are all of the same form. The organization of this genus is not
so well known as that of Vorticella and Epistylis. There is a simple wreath
of cilia, which during quick vibration appears double ; and, as in Vorticella,
a posterior circlet is produced at certain periods ; within the pedicle a trans-
versely folded contractile band is observed dui-ing contraction. The mouth
is lateral. Internally ai'e whitish granules, and a contractile bladder ; but
the nucleus is indistinct. The growth of gemmae has been observed ; and
the zooids can detach themselves from the stalk, as in the case of Vorticella.

One of the best distinctive features between Carchesium and Zoothamnium,
is that the contractile band of the former is not continuous throughout the
pedicle and its branches as it is in the latter (see p. 293). This is noticed
both by Stein and Dr. Wright : the latter adds, " The di^-ision of the zooids
is more complete in Carchesium than in Zoothamnium. In the former, at
each division, one of the zooids produces a new muscle not connected with

that of the zooid from whicli it has se

Carchesium polyjnnum (Leeuwen-
hoek) {V. polypina, M. and Du].) (xxx.
9). — Conical, campanulate, white ; the
frontal portion broad, truncate, and its
margin e.xpanded ; pedicle branched in a
sub-umbellato manner. The axis matter
or supposed muscle of the pedicle, first
observed by Mr. Varley, is very distinct.
1-570" to 1-430".

jarated."

C. pi/gmeeum (Zoothamnium Parasita^
Stein).— "S^ery small, ovate, white, rather
dilated in front; pedicle branched in _8
bifid, rarely in a trifid manner. 1-2400' .
Berlin, dn Cyclops quadricornis.

C. spec(!rt6?7<?". — Conical, campanulate,
dilated m front ; branching in an obhque
conical pol^-pnry, attaining two luies m
height. Berlin.

Genus EPISTYLIS (XXVII. IG, 22, 23 ; XXX. 11).— Pcilicle rigid, cither
simple or branched ; all tlie zooids of the same figure ; or, in other words,

I

OP THE TORTICEUiINA.

589

they are Vorticellce or Carchesia wdtli a rigid hollow pedicle, without an
internal contractile band. The situation of the mouth and anal opening is
easily demonstrated by the employment of coloured food. In E. pUcatilis, says
Ehrenberg, the whole course of the alimentary canal can be seen. A con-
tractile sac and a short band-like nucleus are observable in many ; the latter,
however, is spherical in E. niUans. Longitudinal self-division and gemmation
frequently seen. The Epistylides are among the largest of the Yorticellina,
and are exclusively found in pui-e water, on aquatic plants or animals.

Stein's researches throw additional light on the stractui-e of Episiylis,
which-, he says, resembles generally that of Vorticella. The body has usually
an ovoid or almost spindle-shaped figivre, truncate in front, where a slightly
everted ciliated peristom, of a sphincter- or lip-like character surrounds it, and
gives to the whole being somewhat of a bell-shape. "Within the peristom is a
cUiary disc capable of being protruded or retracted at the pleasui'e of the
animal, and having on one side the oral aperture. This disc is the " rotary
organ " in Stein's description, and in Epistylis its pedicle or stem is always
short and thick. When retracted, the sphincter-hke peristom closes over the
rotary organ like a lid, and then the whole animal acquires a pear-shaped or
globular figure. When the contraction has proceeded to its utmost, the
peristom appears like a wedge-shaped or cylindrical process surmounting the
body. The mouth opens into a slightly coiLed, tapering tube, which ends
abruptly towards the centre of the body ; near its termination is a contractile
vesicle, and not far from the last an elongated band-like or reniform nucleus.
Epistylis multiplies in precisely the same manner as Vorticella, by fission
and gemmation. Stein believes he has traced a cycle of changes through
which it passes, between the encysted condition on the one hand, and the
development of a ciliated Trichoclina-]ii<.e embryo from an Acinetiform phase
of existence on the other. His observations tend to show that the embryonic
being developed from the Acineta of Epistylis anastatica is similar to Triclwclina
Grandinella (Ehr.), and probably identical with it. In E. nutans he satisfied
himself of the occiirrence of similar transformations, but felt less assured of
their occurrence in E. grandis, E. berheriformis, E. Barba, and E. pUcatilis.

The stem or pedicle is inflexible. No canal, as represented by Ehrenberg, is
usually discoverable ; but sometimes the stem is finely striated longitudinally,
and in older specimens has at varying distances ti'ansvei'se Hues or false joints.
Dujardin proposed to amalgamate the two genera Epistylis and Opercularia,
since he could distiug-uish no generic differences between them. In this pro-
posal, however, he was wrong, for, as Stein shows, there are sufficient di-
stinctive peculiarities to warrant their generic independence. (See description
of Opehctjlaeia.) The animals seated on its branches, by their mode of
articulation, enjoy considerable latitude of motion, and are also able in some
degree to shorten themselves by the annular segments of their base.

The stem is secreted by the animalcules it supports. When fission has taken
place, two beings are for a time seen seated at the extremity of the same
pedicle ; but soon each begins to produce from its attached base a new pedicle
for itself, and thus the original stem becomes branched, and this in a furcate
or dichotomous manner.

AH the members of the same little tree (polypidom) are of nearly equal
size. In the case of E. nutans, the largest noticed were l-20th of a' line in
length ; whilst in other polypidoms, whose stems and branches were propor
tionately thinner, examples were met with of very minute size (XXVII 22
2?); , smallest, no anterior cilia and no contained globules were

visible ; in larger ones, though only l-150th of a lino in length rXXVTI 2^^
.such were found. These latter fonns constitute Epistylis Botnjtis (Ehr ")

590

SYSTEMATIC HISTOllY OP THE INFUSOfilA.

Epistylis Galea. — Large, conical,
contractile by transverse folds; mouth
lateral and projecting; pedicle thick,
branched, and articulated. Upon Cei-a-
tophyUum. 1-120".

E. anastatica ( V. anastatica, cratatfjaria
et ringem, M.). — Oval, without folds;
frontal margin dilated and projecting;
pedicle dichotomous, smooth — or squa-
mous with foreign particles. The gra-
nides are white by reflected, and yel-
lowish by ti'ansmitted light ; the clear
vesicle is often to be seen, but not its
contraction; growth of gemmae im-
Imown ; sell-division longitudinal.
Upon Ceratophyllum and small aquatic
Mollusca and Entomostraca. 1-280";
height of little tree 1-140".

" E. anastatica" says Stein, " dilfers
from E. Digitalis, which it very closely re-
sembles, by the fonn of its body, which is
always fuonel-shaped and campanulate,
like that of E. plicatilis, only less elon-
gated, and by the branches of its stem
being outspread in a fan-like manner
and acquirmg a nearly equal height, or
an umbellate condition." He adds, " The
three species most nearly allied, viz. E.
anastatica, E. plicatilis, and E. Digitalis,
have, when studied at different ages, few
points of separation, except that furnished
by their habitats, — E. plicatilis living
upon the* shells of Mollusca ; E. anas-
tatica upon the roots of Lemna ; and E.
Digitalis upon Cyclops quadncornis."

E. plicatilis ( V. annularis et pyraria,
M.). — Conical and elongated, contractile
in annular folds ; fi-ontal margin dilated,
tmncated, and slightly projecting;
pedicle dichotomous, often corymbose,
smooth, or, when foreign bodies adhere,
of a scaly appearance. This species is
white to the naked eye, but somewhat
yellow beneath the microscope ; it is
very much like the preceding, is often
found with it, but is distinguished by
being larger, by its ring-like folds when
conti-acted, and by the tasselled or tufted
appearance of the cluster, 1-280" to
1-210".

The stem, says Stein, is solid and
longitudinallv striped. The nucleus is
reniform, and the contractile vesicle lies
within the substance of the large rotarj'
or^an. In old stems transverse lines or
joints appeal", at a distance fi'om one
another. The largest examples Stein
met with were 1-168" in length.

E. grandis. — Broadly campanulate,
stalk decumbent, slender, smooth j the
branches flexible and without articula-
tions, but much tuftod. This is noli only

the largest freshwater species of Epi-
stylis, but it also fonns the greatest
masses. Its proper colour is a blui.sh
white ; but it often appears of a yellow or
greenish hue, from the colour of its food.
Upon Ceratophyllum and Nymphaa,
often like a bluish-white slime, easily
broken up. In masses several feet long,
and two to three inches thick. 1-140" to
1-120".

E. fiavicans ( V. acinosa et heUis, M.).
— Large, broadly campanulate, and of
a yellow colour; pedicle smooth, its
branches coarctate. The branches are
dilated at the axillae. In this species the
alimentary canal is very evident. Size
(stretched out) 1-190" ; tree 1-9" high.

Although Stein represents the stem
in Epistylis to be, as a nile, solid, yet, in
a passing notice (p. 72) of E. fiavicans,
he remarks that the pedicle evidently
had a hollow central canal.

E. leucoa (Volvox Sphcet-ula, M.). —
Large, broadly campanulate ; pedicle
erect, smooth, and articulated; the
branches capitate or collected in a head.
These animalcules are convex anteriorly,
have distinct colourless gi'anules, a sim-
ple wreath of cilia, and a roimd mouth on
the mai-gin. The nucleus is bent in the
form of the letter S. 1-120"; tree 1-24".

E. Digitalis (V. Digitalis, ringens etin-
clina?is, M.). — Small, cylindrical, campa-
nulate; stem dichotomous, and finely
annulated. This well-marked form in-
fests the Cyclops quadricornis, which it
sometimes completely covei-s. In the
beautifid little tree this species forms by
its branching, the Notommata petromyzon
nestles just like a bird in a bush, and
fastens its eggs to its branches. Coloured
food is readily taken. 1-430" ; tree 1-20".

The figure is more like that of the
flower of the foxglove (Digitalis), as the
name implies, than bell-shaped ; for the
peristom is very little everted, and its
diameter not greater than the middle of
the body. The rotary organ protrudes
some distance, and lies very obliquely.
The nucleus is band-like, and curved m
a semicircle. The annulation of the
stem could not be seen by Stein, except,
as in \erymnnj Epistylides, near the junc-
tion or bifurcation of the branches, and
occasionally in very old specimens : in
these last it often has a rusty colour.

E. (?) mdans {Operctd'aria nutans,
Stein). — Ovate, attenuated at both
ends ; mouth two-lipped and prominent
The pedicle annulated (xxvir. 16, 22,
23). "This animalcule," says Ehren-
berg, "can push forth a bladder between

OF THE VOETICELLINA.

591

its lips, like (si pai-va licet componere
magnis) a camel can its palate". 1-430" ;
tree 1-24".

The process above alluded to by
Ehrenberg as protruded ti-om the head
of this animal is imdoubtedly the sort of
imder lip alluded to by Stein La his ac-
coimt of Opercularia (see next page).
This author, again, confirms Ehrenberg in
his doubt as to the position of this species,
and shows that it is an Operadaria.

'E.Botrytis. — Verysmall,ovate,crowned
with cUia. They resemble gi-apes upon
a simple hyaline pedicle. This species
together with E. Arahica and Carchesium
pi/fftneeuni are, in Stein's opinion, not
really distinct species, but different
phases of the same animalcule. 1-2400";
tree 1-240" (see p. 589, last line).

E. vegetans ( Volvox vegetans, M.). —
Very small, ovate, crowned with cilia
(?) ; disposed Ln clusters, like the pre-
ceding, upon a branched pedicle, of a
yellow colour. When the water con-
taining this species is coloured with
Ladigo, sti'ong currents are seen at the
front or head of each animalcide, evi-
dently caused by a vibratile organ ; but
whether this is a wi-eath of cilia or a
simple proboscis, is imdetermined ; if a
proboscis, this creature would belong to
the Monads, where it would form the
type of a new genus. In river-water.
1-3450" ; tree 1-140".

BrightweU says (^Fauna Infusoria of
Nm'folk, 1848) that the armed or oval ani-
malcules are fiu-nished with a long fila-
ment, that, when the water is shallow,
they detach themselves, and swim about
with a revolving motion. The organ of
motion he states to be a long filament
(proboscis) ; if so, the animal is not an
Epistylis. Stein ti-eats it also as a very
doubtfid Epistylis.

E. parasitica. — Small, conical, campa-
nulate, and solitary ; pedicle simple and
smooth. Upon Zoobotryon peUiicidiis.
1-570" ; with pedicle 1-120" to 1-24".

E. Arahica. — Small, oval, campanu-
late ; pedicle but little branched, smooth,
and hyaline. In the Red Sea. Size of
tree 1-140".

This species, as well as E. Botrytis and
Carchesium pygmemirn, are adduced by
Stein as insufficiently marked, and re-
ferred by him to the young and incom-
plete forms of other species.

E. Barha. — Ovate, oblong, white ;
branches dichotomous; longitudinally and
regularly .striated. On larva? of insects.

E. herberiformis = Operriihtria hrrhe-
rina (Stein) (xxix. 4).— Oblong, .tub-

cylindrical, white ; stem dichotomous,
articulated, and striated, its divisions
dilated at their apices. Parasitic, Berlin.

This is not, as Stein shows, a species
of Epistylis, but of Ope)-cularia, imder
which we shall introduce it with the de-
scriptive account this able writer supplies.

E. euchlora. — Oblong, rather expanded
in front, with gi-een ova ; stem dichoto-
mous. 1-13" in height, smooth. Para-
sitic on Planorbis cornea, Berlin.

E. pavonina. — Very large, hebnet-
shaped, elongated Ln front; stem very
high, dichotomous, striated, and hence,
by decomposing light, displays many
hues. Often 1-3" in height. Berlin.

E. crassicoUis (Stein) (xxx. 11). —
Stem of considerable height, acutely and
dichotomously branched so that the seve-
ral zooids it supports are brought nearly
on the same level (corymbose). Branches
smooth, transparent, straight, and of
equal thickness. In some specimens
transverse lines or joints occm-; and the
stem is frequently dilated at the point
of divergence of its branches. Animal-
cides ovate, conti-acted posteriorly, and
also ia a slighter degree anteriorly. The
anmilated, hoop-like peristom sunnounts
the body, having a rather smaller dia-
meter. The rotai-y disc is convex, but
rises only slightly above the peristom.
The oesophagus and its iateltine-like
continuation curve backward almost to
the posterior extremity of the body.
The conti-actile space lies close to the
lower end of the stem of the rotary
organ ; the nucleus is horseshoe-shaped.
Contents white, frequently with specks
of red. Largest specimens 1-240" in
length, and 1-480" in width. Occurs on
the bristles ,of the hind feet and of the
jaws of Entomostraca.

E. branchiophila (Pei-ty). — Spherical,
with a tnmcate base ; colom- grey. Stem
and branches colom-less and smooth.
1-3G0"; length of polypidom 1-90". The
animalcules aa-e sparse in reference to the
dimensions of the stem : the latter often
rugose at its junction with the animal it
supports. When the stem contracts it
does so only on one side, and not com-
pletely across. Both this description
and the figures ^iven in illustration by
Perty are, a.s Stein observes, insuflicient
to characterize the species. The latter
writer retains the name, however, for an
Epistylis having a relatively thick stem
of moderate height, repeatedly forked'
finely striated and somewliat curved. Of
tlio two branches resulting from a bifur-
cation, one attains a much greater length

592

SYSTEMATIC HISTORY OP THB INFUSORIA.

than the other ; hence the appearance of
a main stem and a subsidiary branch.
The zooids terminating the ramifica-
tions are pear-shaped, the width nearly
equalling the length, and almost glo-
bular when the peristom is contracted.
They are of a greyish hue. The rounded,
lip-like, ciliated poristom is of less dia-
meter than the widest pai-t of the body ;

and its entire space is occupied by the
rotary organ, which is only a little ele-
vated above it when extended. The
nucleus is elongated and vermicular.
The average lengtli of the body is 1-360"
to 1-280"; and the width 1-456" to
1-330". Gemmation may be frequently
seen, the buds gi-owing fi'om the fore
part of the body behind the peristom.

Genus OPEECULAEIA (XXIX. 4 ; XXX. 1, 2, 27).— Branched pedicle,
stiff and rigid, supporting dissimilar corpuscles (zooids). The anamalcules
have two lips ; the superior one, supported by a muscle, is somewhat like a
lid (operculum), which is a characteristic. Oj)ercularia = Epistylis with dis-
similar corpuscles. The organs of locomotion consist of a wreath of cilia,
and a long muscle within the body ; this raises or depresses the frontal region,
in the form of an upper lip. Pood is taken into, and its effete portions dis-
charged from the large vestibulum situated in front and rather to one side,
and to and from which the alimentary canal is seen mnning. Self-division
and the separation of the zooids from the stalk may be frequently observed.
The large dissimilar bodies occur singly beneath the animalcules, more espe-
cially in the axillae of the branches ; some are very large and egg-shaped,
with hairs at their point, and only a small, round, non-vibratile opening.
Ehrenberg observes that such are most probably parasitic bodies. In aU
probabiUtj, however, they are encysted corpuscles.

The following characters, contrasted with those of Epistylis, are given by
Stein. The peristom is, in Opercularia, merely a single border, neither
ciliated, tliickened, nor everted in a campanulate manner. The body, there-
fore, is elongated, ovoid, constantly narrowed anteriorly, and simply truncated.
The opening of the peristom, which also forms that of the mouth, extends as
a wide and deep cavity (the vestibulum) to the oesophagus, which is prolonged
far into the body as a narrow digestive tube. A distinction between this last
canal and the oesophagus is indicated by a group of three or foiu- strong cilia
placed at its commencement. The rotary organ spiTngs fi'om the wide oral
cavity, on one side, by a nari'ow point, which is the apex of its trumpet-
shaped figure. The base of this long conical sac is formed by its ciliated disc,
which is thrust much above the peristom when extended, but can be drawn
down upon it and close it : the whole organ is very moveable. The older
observers looked upon the rotary organ as a valve or lid ; and Ehi-enberg
supposed it to have a long retractile muscle which could close it upon the
mouth. However, no muscle exists mthin the pedicle of the organ ; for this is
a hollow sac filled with the same substance as the general cavity of the body,
and in dii-ect communication wdth it. The pedicle of the ciliaiy disc is longer
and more moveable than that of Vorticella and Epistijlis. The genus Opercu-
laria is further distinguished by the presence of a delicate membranous, trans-
parent process which stands out from the throat like an internally fixed collar,
and is elevated above the peristom, forming a sort of under lip to the rotary
organ. Whether this is ciliated, or only a -^dbrating membrane. Stein remains in
doubt. It is the same stracture as is referred to by Ehrenberg in his note on
Epistylis ? (Opercularia) nutans as a protnisile bladder-like process (see p. 590).

Opercularia articulata (F. Opei-cu-
laria, M.) (xxx. 1) occurs as a little
shrub, 1-6" to 1-4" high, white and
dichotomous ; carmine and indigo readdy
taken ; and lihrenberg states he saw as

many as fort5'-four stomach-cells filled,
resembling a girdle in the middle of the
body. The stallc is very delicAtely
striated in a longitudinal direction, and
shows, at its ramifications, a transverse

OF xnE vou

line, or joint. Upon Dijtiscus marginalis.
1-480".

Stein creates several additional species
of Ojyercularia, and has entered into many
details respecting the structure of 0. ur-
ticulata (xxx. 1, 2). According to him,
the body is spindle-shaped or ovate-elon-
gate, and ti'uncate before and behind.
The periston!, which is continuous witli
the body, forms a simple terminal edge,
sometimes quite smooth, at others plaited
longitudinally. Similar plaits often occiu'
at its posterior half, when the animalcule
contracts iteelf. The disc of the rotary
organ has three circlets of cilia, is eon-
tractile and changeable in fomi. The
oral ca'vdty behind the margin of the
peristom is very Avide and deep, ex-
panded as a capacious sac, from one
corner of which, posteriorly, the digestive
tube proceeds. It is lined internallj' by a
delicate hyaline membrane, which pro-
jects beyond the peristom lilte an upright
collar. At the base of the body is a dense
collection of granules, apparently of a
fatty character. The nucleus is horse-
shoe-shaped, and a round conti'actile
space lies near to the digestive tube at
its commencement. There is a pecu-
liar glandular-looking body on each side
of the oral cavity at the anterior part of
the body, the natm-e of which is not de-
termined. When in a state of contrac-
tion the animal is thrown into annular
folds, the rotary organ completely re-
tracted, and the peristom closed over it
in a sphincter-like manner, the whole
body assuming a spindle-shaped fomi,
or, when contracted to the utmost, a
pyriform or orbicidar figiu-e. Reproduc-
tion takes place by gemmation ; but fission
has not been observed : Stein believes in
the transformation of the animals into
Acinetee, and the development from
these of ciliated germs (xxx. 3, 4).

The length of the body of the largest
specimens, when extended, is 1-96" ;
and the gi-eatest width, at the middle,
1-216". The stem is very variously
branched, and is less rigid and more
flexible than in other species. The
transverae lines or false joints are not
characteristic, and the longitudinal stria-
tion is not always observahle.

0. berberifia (Stein^ (xxix. 4) = JE^t-
stylis berberifonnis (Ehr.). — Animalcules
outstretched elongated, cylindrical,
slightly contracted before and behind :
about 2| times longer than broad, with-
out reckoning the extruded rotary organ.
No separable peristom exists at tlie ante-
rior truncated extremity {i.e. in technical

ITICELLINA. 593

phrase, it is obsolete); rotary organ
comparatively shortly stalked, its disc
having a single whorl of cilia. Oral
cavity capacious, as in 0. articulata ; its
membranous lining imdidating, and seen
with difficulty. An anal opening ap-
pears at the base of the oral cavity, not
tar from the orifice of the oesophagus.
Even when expanded, the body is sur-
rounded by thickly-placed anniilar folds,
which become inucli more sti-ongly pro-
nounced when it contracts itself. The
surface of the body is covered by a very
firm, transparent, structureless mem-
brane, which can be isolated for exa-
mination without any special prepara-
tion, and is often left behind after death
cas a distinct sheath or skeleton. Multi-
plication by gemmation has not been
observed; but fission is common. The
largest specimens were 1-190" in length,
and 1-570" in width.

The fomi of the stem is very variable,
for two similar specimens are scarcely
to be found ; yet in all, the animalcules
ai-e supported at different heights, on
stems vai'ying in length, and therefore
not corymbose. The stem, likewise, has
not the stiff, regular construction of
most OpercularicB and Epuitylides, but is
generally ciu'ved outwards, and has at
variable distances transverse lines or
joints ; the exti-emity supporting the
animalcide is expanded. It is through-
out solid, colom-less, and diaphanous,
and if at all striated longitudinally, is so
in _ a very faint manner. On aquatic
animals. Stein believes he has dis-
covered its Acineta (xxiii. 17, 20).

0. Lichtensteinii. — Body stout, short,
barrel-like, the length not being double
the widtli ; except in sparingly-branched
stems, the opposite ends are" little con-
tracted. The rotary organ is but slightly
elevated above the peristom ; its stem is
short, thick, and almost cylindrical, little
exceeded in width by the disc surmount-
ing it, which has but a single circlet of
cilia. The inenibranous process within
the oral cavity rises above the peristom,
is notched, thrown into longitudinal folds,
and, to all appearance, ciliated. The
nucleus is always short and oval or
round; its position varies; the con-
tractile space is circidar, in proximity
to tlie beginning of the digestive tube
or the resophagug. The heap of fatty
coi-puscles near the base is present, aa
m many rigid-stem Vorticellina. The
niaxinmm length is 1-190"; and the
width l-.-lOO". It dilVors from O. arti-
cuhda (xxx. 1, 2) by its round nucleus,

594

SYSTEMATIC HISTOET OF THE INFUSOEIA.

and from O. bei-beiina ^xxix. 4), which
it closely resembles in its general orga-
nization, by its leng-tli and width bemg
much nearer equal, and by its not being
bent backwards on the stem when con-
tracted. Stein describes its Acineta and
the ciliated embryo resulting from it.
The stem is subject to gi'eat varieties ;
but these all agree in the stem expanding
from its base in a more or less marked
manner, in the branches being all of equal
length, and, in consequence, the zooids
elevated at different heights. The stems
of the oldest generations are low, and
have but few animalcules upon them,
which are seated on short, cm-ved, and
enoi-mously thick branches, such as are
seen in no other Opercularice. The
whole smface of the stem is covered with
nimierous, closely-placed, shallow and
deep transverse folds or constrictions,
which give it a knotty appearance ; it is
also longitudinally striated. In younger
generations the stems are more densely
branched ; but the branches are not ex-
traordinarily thickened, being as slender
as those of the larger gi-oups of O. arti-
ciilata, and, like these, have only here and
there transverse mai'kings, — for instance,
at the angles of the branches. They are
also longitudinally striped, and differ
further from O. hcrherina by their ex-
pansion upwards towards the base of
the supei-posed animalcule. On aquatic
Crastacea and MoUusca.

0. stenostoma (Stein). — Body pyii-
form, widest in front of the middle lino,
rounded anteriorly, with a very narrow
peristom, and behind the middle strongly
contracted, so as to assume the appear-
ance of a pedicle. The disc of the rotaiy
organ is very nari'ow across, fringed with
a single row of cilia; the membranous
process from the oral cavity rises only so
much above the peristom as to form a
narrow annular ridge. Nucleus long and

Genus ZOOTHAMNIUM (XII. 67, 68, 69).— Comprehends Vorticellina
with a spirally flexible branched pedicle haA^ng an internal muscle. Tlic
stalked corpuscles are of different shapes ; a wreath of cilia suiTOunds the
frontal region. The mouth simple and lateral. Numerous round stomacli-
cells (vacuoles) can be demonstrated by artificial feedings. Self-division has
been observed.

The more accurate examination of Stein supplies additional details, and
corrects those above, as given by I^hrenborg. The so-caUcd frontal region is
the peristom of Stein, which presents a rounded tumid border, but no cilia ;
for these organs form a fringe around a ciliary disc -nathin the circumference
of the peristom, which can be protruded beyond, or retracted within it. tn
short, Zoothamnimn, like other VorticclUna, ha.s a " rotary organ," which, by
the whirling of its cilia, diaws inward to the mouth, situated on one side of

horseshoe-shaped ; contractile space cir-
cidar, placed near the commencement of
the oesophagus. Stem braiiclied dichoto-
mously,uut short, whence the individual
animalcules (not more than 4-G in num-
ber) are in near apposition. 1-000" ;
length of stem 1-3C0". The stiff stem is
small relatively to the body, striated
longitudinally, and obscm'ely wiiukled
transversely. On aquatic MoUusca.

0. jnicrostoma (Stein) (xxx. 37). —
Very similar to the last-named species.
Like this, it forms a lowly-branched stem
bearing few animalcules. The branches
are comparatively thin, and mostly
marked by thickly-set annular constric-
tions, rendering it more or less crooked
and Imotty. Some stems, however, are
quite smooth, and also without trace of
longitudinal striae. The animals, when
extended, are pear-shaped, and have a
consti'iction behind the middle, and in
front a very naiTow peristom. Eotarj'
organ with a short stem and a narrow
disc; on the opposite side of the oral
cavity is a tongue-like membranous pro-
cess. The oral ca^•ity is comparatively
naiTow; the digestive tiibe short, the
contractile vesicle lies near its upper
end, .and the cm-ved, hook-like nucleus
behind the rotary organ. In contraction
the animal retains its pvi'ifonn figm-e,
and is thrown into annular folds poste-
riorly. Wlien more sta'ongly contracted,
it becomes oval. Greatest length 1-280" ;
width 1-460". On the feet of Crustacea.

0. mttans (Stein) = Epistylis nutans
(Ehr.) ; but tlie description by Ehren-
berg requires to be modified by the dis-
coveries of Stein, to render it correct and
characteristic. The two-lipped moutli
is a misapprehension of the rotary organ
and membranous process of the oral
ca-sdty, and the retractile palate is equi-
valent to the rotary organ of Stein.

OF THE VORTICELLINA.

595

it, a current of water, together witli the nutritive particles it may contain.
Within are a ciu-ved semicii-cular band-like nucleus, a contractile vesicle, the
so-called stomach-sacs or vacuoles, and niimcrous granules and molecules.
The mouth opens into a wide oesophagus, which extends backwards towards
the centre of the body, where it terminates abniptly. The stem essentially
ditfers from that of Carchesium in its central canal being continuous through-
out ; but the distinction drawn between the two genera by Ehrenberg, from
the presence of dissimilar corpuscles (animalcules) being found in Zootham-
niiim, and not in Carchesium, is worthless, as that cu'cumstance is indicative
of nothing more than a certain condition of development. The oldest portion
of the stem in this genus often becomes solid and rigid, and thereby re-
sembles that of Epistylis, for which it might he mistaken (see p. 293). Dr.
Wright observes that the primary (parent) zooid of a polypary does not begin
to develope the contractile band in its pedicle until this has attained a con-
siderable length ; hence, for the time, this primary zooid is an Epistylis by
the stracture of its stalk.

ZooTHAMNiTJir Arhuscula (Vorticella
racemosa, M. and Duj.) (xn. 67, 68, 69)
has the branches in racemes or irre-
gular umbels ; coi-puscles (zooids) white,
campaniilate ; pedicle very thick. These
beautiful little trees resemble plumes of
feathers. They have the characters of
Carchesium and Opercularia as respects
the presence of globular bodies in the
axilljB of the branches, but are at once
distinguished by the strength of the
latter. Found upon Ceratopliyllum and
other freshwater plants, and also in sea-
water ; visible to the naked eye. It con-
tracts itself on its very elastic pedicle on
every alann. It lives but a short time
when removed from its native place
(Brightwell, p. 344). Size 1-430" ; tree
1-4", stalk one-fom'th the thickness of
the body.

Z. niveum {Z. plumosum, Wright). —
Main stem zigzag ; branches short, alter-
nate, almost verticillate, given off fi'om
each angle of stem ; zooids oblong, cam-
pamdate, white, clustered at the ends of
the branches, which are filiform, the
lower ones often deserted, while the
upper bear clusters of club-shaped little
bodies roimded anteriorly. Summit of
main stem and branches curved back-
wards lilce an ostrich-feather ; hence the
name plumosum, proposed by Dr. Wright.
1-210".

Z. (iffine (Stein). — Stem dichotomous ;
branches attaining a nearly equal eleva-
tion. The primary stem varies in length
as well as the lateral ramifications ; lience
the arborescent polypidom varies con-
siderably in its general aspect, being at
one time loose and diffiise, at others com-
pact and dense. Wlien extended, the

ti'ansparent branches are smooth, but
dm'ing conti-action are thrown into ti-ans-
verse folds, and acquire a relative in-
crease of thickness. The canal is con-
tinuous throughout, except at the base of
attachment in specimens of some age,
where the stem is solid; in its interior
is the axis-matter, — i. e., in Ehrenberg's
language, the muscle moving the stem.
The aninialcides borne on the exti-emi-
ties of the branches are oval, somewhat
conti-acted behind, and tinmcate in front,
where they ai-e sui-moimted by a thick
tumid peristom of rather less diameter
than that of the body. The rotary organ
is strikingly naiTower, and protrudes
little beyond the peristom : in the com-se
both of the extension and reti-action of
the rotary disc a fold is produced, which
gives the appearance of a double peri-
stom. A wide oesophagus and digestive
tube opens from the mouth ; and near its
postenor extremity is the contractile
vesicle. The nucleus resembles a short
semicircular band, and lies across the
body. The relative thickness of the stem
IS a remarkable character of this species
being one-half tliat of the animalcules it
supports. Usual length of animals 1-380"
to 1-270" ; widtli 1-650" to 1-570". On
Entomostraca, &c.

Z. Parasita (Stein).— Tree-like polv-
pary, veiy small, supporting few animal-
cules: the latter agi-ee in figm-e with
those of Z. Arhuscula. Stein believes it
identical with Carchesium pygmmmx,
iUir., the latter being an incompletelv-
deve oped form. On Entomostraca and
small aquatic Cmstacea.

We are ind(.bted to Dr. W^right for a
notice oi tlie toUowing species :—

2 q2

59G

SYsiTEllATIC HISTOBY OF XH£ INFUSOBIA.

Z. dichotomuin. — Stem very regularly
dicliotoinous; pedicles long; zooids cylin-

drical, resembling fruit of the Rosacaniita.
Z. plumomm (Wright) =Z nkeum.

Gonus SCYPHIDIA (Duj.). — Sessile, cup-shaped, tapering at the base,,
covered with a reticulated integument.

This genus is received both by Perty and Lachmann. The former notices
tlu'ee species, of which one, viz. 8c.j)atula, is new, the two others being Sc.
ringem and Sc. pyriformis. Lachmann, on the contrary, although admitting
the genus, rejects the species of Dujardin and Perty, " as they have a shoit
stem, and appear to be only particular states of pedunculate Vorticellina, in
which the stem has not attained its usual length ; but on the other hand," he
continues, " two other beings must be refeiTsd to it, both of which attach
themselves to the naked parts of small freshwater moUusca, and never fonn
a stem, but which were often observed by me in process of division, and are
easily distinguished from other forms which are, Hke them, attached at first,
by theii' posteriorly- truncated form, and a projecting pad at the mai'gin of
the hinder end."

ScYPHTDiA ruffosa.—Ohlong, marked
with distant oblique deep strife, looking
like fuiTows. 1-565". In pond-water,
amongst vegetable debris. To this genus
Diijardin would also attach the Vorticella
rinffetis and V. inclinans of Miiller, and
possibly also the V. pyriformis of the
same author, imder which name Eln-en-
berg has described a variety of V. conval-
laria.

Sc. pyriformis. — Grey, hyaline ; with
no pedicle, or an extremely short one ;
constantly contracting itself. Uncom-
mon ; on Cyclops, &c. Length, in-
cluding stem, 1-720" to 1-600". Is
closely allied to Sc. rinfiens.

Sc. (Perty). — Widelycampami-

late ; of a bluish-gi'ey colour ; stem half
the length of the hoA.j. Length, with
stem, 1-360". Uncommon, with Pota-
moyeton.

Vorticella hamata (Ehr.) is probably
another species, and identical with V. in-
clinans, which Dujardin niuubers among
the Scyphidia.

Sc. limacina (Lachmann) = Vorticella
limacina (Midi.) (xxix. 3). — Body nearly
cylindrical, taperin^ a Uttle at each end,
and annulated ; penstom naiTow and not
turned backwards; cihary disc naiTow,
and furnished with a projecting umbi-
licus in the middle ; the posterior trim-
cated surface provided with a thick pad-
like mai-gin. 1-240" to 1-360". Lives
on small species of Planorbis.

Sc. Physarum (Lachmami) is longer
and more uuifonnlv cylindiicid than the
preceding, the peristoni longer and often
turned backwards (everted), and the
hinder mai'gin thinner and shorter.
Lives on the naked parts of species of
Physa.

Genus URCEOLARIA (Lamark and Duj.). — Body not cUiatcd throughout,
contractile, varying in shape from hemispherical or discoid to globulai- ; sur-
rounded by a plane margin fringed with a row of strong cQia planted
obliquely, which make^ a spiral turn inwards at the oral aperture, which is
also situated on the margin.

Vorticellina of different kinds have been mistaken for examples of this
genus, and Ehrenberg has placed sonic of its members among the Tnchodin(v :
indeed the type of Urceolaria is the Trklioclina Pedimhis of Elu'cnberg.

Many species of this genus are parasitic on freshwater Mollusca and Zoo-
phytes ; but MiiUer mentions some found by him in sea- water.

There appear no sufficient grounds for instituting this genus when that
of Trichodina is admitted, as it is by natiu-aUsts generally.

VncF.oi.A-RiA steUina=Trichodina Pe- the border of the disc ciliated. In

dicuhis (Elir.). sea-water. ITnconimon. Eln-enbcrg has

U. discina= Vorticella discina (M.). — treated this fonn as identical ^yith

Dcscribed by Midler as orbicular, hoi- r/ior/Z/wPrf/eW/Zw, but , n.'' Dujardin thinks,

lowed out above, convex beneath . . . ; erroneously. However, it is impo.=i.«ible

OF THE VORTrCELLINA.

697

nccuvately to decide -what the being
whicli ^liillor mot with is, ftom the ac-
count he has left us.

U. liinacina. — Sessile, cjliudi'ical, dia-
phanous ; orifice ti-uncated, with 2 or 4
indistinct cilia (according to Miiller), or,
as we may presume, with a circlet of
cilia aroxmd the margin of the wider ex-
tremity, and a collection of cilia at the
naiTOwer base, by which the animal at-
taches itself. Pai-asitic on the tentacles
of BuUa and Planorbis.

U. Buf(irdinn= Vorticella huisata and
V. utriculata (Miill.).— Capsular or utri-
cular in shape, bellied posteriorly, cili-
ated on the anterior margin. Miiller
distinguished this being under two fonns,
one of which he described as having a
projecting papiUa at the centre of the
anterior surface, capable of elongating it-
self. In sea- water.

These species of Miiller appear to us
too indistinct to insist on as independent
forms.

Genus CH^TOSPIEA (Lachmann) (XXXIX. 5, 6).— The sm-face gene-
rally covered with cilia, like the genus Stentor, from which it is distin-
guished by having that part of the parenchyma of the body which bears
the crliaiy spii-al and the anus (which in aU the Stentorinte lies on the dorsal
surface of the body, close under the cOiary spiral, and not in a common pit
with the mouth) di-awn out into a thin process. This process is narrow
and baciUar ; the series of cilia commences at its fifee extremity, and only
forms a spiral when in action by the rolling-up of the lamina. The process
bears the anus. The animalcules inhabit a sheath or tube, of a mucilaginous
or even horny density. " It is possible that the free-swimming Stichotricha
secunda of Perty, which he arranges with the Oxytrichinae, is allied to Chce-
tospira ; his figure, however, is very inexact, and might perhaps represent a
Loxodes or Amphileptus Fasdola ; and, as he does not desciibe the position of
the anus, which he never figures, any more than the contractile vesicle and
the_ nucleus, I do not ventiu'e to place his Stichotricha with the Stentorinas.
If it should tui'n out that it belongs to that family, it must be placed beside
the analogous sheath-inhabiting Chcestospira, as a genus not inhabiting a
sheath."

Ch^tospiea Mullen (xxix. 5, 6). —
Slender. The first cilia of the series upon
the process are somewhat, but not re-
markably lono;er and stronger than the
rest; when rolled up, the ciliated bacillar
process fomis more than one tm'n of a
spiral. Sheath flask-shaped and horny.
Hitherto found only in the open cells of
torn leaves of Lemna trisculca, growing
in fi'esh water near Berlin.

Ch. inucicola. — Enclosing tube mucous
in consistence; animalcule sliorter and
more compressed; the roUed-up cUiaiy
process does not foim a complete turn of
a spiral ; the first cilia ai-e considerably
larger than the rest, the first one espe-
cially being nearly tsvice as long as most
of the others.

Genus CCENO^IORPHA (Perty) (XXVIII. 27-30).— Small, hyaline, of a
bell-like or hemispherical figiu'e, concave at its truncated base, which has an
irregularly notched margin, and a tail-like process depending from it at its
centre. Ilim of the bell fmnished with long cilia. Except in the absence of
tlie long tentacula, those beings, according to Pcrty's figures, have a general
resemblance to minute campanulato Medusa: ; or, otherwise, they may be
likened to miniature parasols with fringed edges and a short handle.

Perty has placed this genus in his family Urceolurina, which is equivalent
to that called Stcntorina by Lachmann. Uut, to our mind, much doubt must
attach to this assigned position, for not only is there a very great departure
from the general form of every genus of VorticelUna, as Perty himself could
not fail to remark ; but, from his figures, no characteristic, no intemal organ
ization appears to establish the organic afiinities of those curious beings

598

8YSTBMAX1C HISTOKY OF TUK INl'USOHIA.

CcENOMonPHA Medusula (xxvm. 27-
30). — Colourless, transparent, with a
small number of intemal vesicles and
molecules. Length, together with the

tail, 1-240" to 1-190". It swims actively
and rotates on itself, undergoing various
changes in outline. Some specimens ex-
hibit folds of the surface.

Genns SPIROCHONA (Stein) (XXX. 17-20, 27, 28).— Body naked, but
having a firm corneous integument ; attached perpendicularly by its base,
and quite motionless ; of an elongated, flask-like shape, ^vith an anterior,
spirally-convoluted, funnel-like head or peristom. Posteriorly it narrows to
a small base, whereby it is fixed either immediately or mediately by a verj'
short pedicle. The infundibiiliform spiral peristom surmounts a constricted
portion or neck. The spiral lamina forming the peristom terminates abruptly
below, so as to leave a cleft, which conducts to the mouth ; its upper portion
is rolled around the longitudinal axis of the peristom, and produces a soHd
central pivot. The innermost turn of the lamina constitutes a funnel, which
siu'mounts the whole peristom, and with the next coil forms what Stein calls
the " spiral funnel," whilst the lowest and widest spiral represents the true
peristom, homologous with the ciliary spiral or peristom of Vorticella. The
latter is richly covered with cUia, which extend in less number to the second
coil. Internally, a digestive tube is seen to extend a considerable distance
from the month, having a contractile vesicle placed near its termination. A
large nucleus is seated near the middle of the animal, having a clear central
space or nucleolus. Pission has not been witnessed ; but gemmae are fre-
quently produced, which, under certain circumstances, become encysted, and,
as Stein believes, undergo an Acinetiform metamorphosis (XXX. 21-28).
216" ; breadth of largest 1-600".

wide lamuia, and has, besides, a series of
stiff fibrous processes fringing it on one
side. The internal face of the funnel is
lined with cUia below. Pound on Ento-
mosti'aca in brackish water near Am-
sterdam by M. Scheuten; they are at-
tached to the long feathery bristles of
the post-abdominal feet, and not to tho
ova-capsules, like S. gemmipara.

Length 1-750" to 1

^vmoc^oy^x gemmipara (xxx. 17-20).
— The above description applies spe-
cially to this form. Found on the ova-
capsides of Gammanis and other Ento-
mostraca, in fresh water.

Sp. Schmtenii (xxx. 27, 28) agrees
with the foregoing in size and figure ;
but the peristom is more simple, consist-
ing of little more than a single coil of a

PAMILY lY.— OPHRYDINA (VAGINIFERA).
(XXYII. 10-15 ; XXYIII. 18-20, 23 ; XXX. 29-55.)

Loricated polygastric animalcules, solitary or aggregate, possessing a distinct
alimentary canal, a separate moiith and discharguig orifice, wliich approxi-
mate and terminate in the same spot. In organization it resembles the
faniUy YorticeUina ; in fact, continues Elirenberg, it includes tnie VorticeU<B
or Stentors, enclosed in a gelatinous, membranous, combustible lorica. Bo-
sides the usual frontal -wreath of cilia, there is in Ophrydium a second wreath
placed posteriorly ; and Tintinnus has an elastic muscular stalk or tail. Al-
though, as Ehrenberg tells us, the polygastric organs of nutrition can be
demonstrated in all tlie tribe by using coloiu-ed food, it is only in Ophrijdnm
that an alimentary canal has been distinctly seen. Longitudinal division of
the body takes place within the lorica, which continues unaffected. In
Ophrydhvin transverse division has been doubtfulty afiirmed.

The genera are disposed as foUows : —

OF THE OPKEYDINA.

599

Forming Monad-clustors, through incomplete self-division of tlie lorica Ophrydiuin.

( Body furnished with an elastic pedicle attached \ r^^^t^^^-^,
to lorica J

Animalcules solitary, no
self-divisiou of the lorica

[ Lorica stalkless Vagijiicola.

Body stalkless \

{ Lorica stalked Cothumia.

Of the genera composing this family, Ophrydium is arranged by Dujardin
with the Urceolai-ina, and Vaginicola with the Vorticellina. Thia author
writes —

" The so-called lorica of Ophrydia (Duj., or Ophrydium) is an amorphous
gelatinous investment, unHke that of Vaginicola, which is a tnily resistant
enveloping membrane. The individual beings in the gelatinous ball of
Ophrydia are elongated, cylindrical, or fusiform, and capable of varying their
figiu'e."

Fui-ther, Dujardia includes Tintinnus and Oorthurnia in the genus Va-
ginicola.

Steia enumerates Tintinnus among the genera of Ehi-enberg's Ophrydina,
but oflFers no account of it. Ho rejects the distinction, as does Dujardin,
between Vaginicola and Cothumia, and would transfer the whole of this
family, so reduced, to VorticeUina, with which its members have the greatest
similarity in organization. Perty adopts the the title Ophrydina, but com-
prehends under it only the single genus Ophrydium. Lachmann rejects
Tintinnm from the list.

The characters laid down by Ehrenberg, of this family, are very unsatis-
factory. Its members cannot be said to be lori'cated in the same way aa
Colepina or Euplotina ; for in these the lorica consists of a thickened, closely-
adherent integument, whilst in Ophrydina the structure so called is a loose
sheath, open at one extremity, which may in some be seen gradually excreted
from and built up around the animalcule, which last, moreover, has a distinct
integument of its own. In the Ophrydina, therefore, it is rightly caUed a-
sheath, case, or tube. Ophrydium, indeed, is exceptional; for, though it
secretes a large quantity of muco-gelatinous substance, it never biulds this
up aroimd it into a sheath, but merely sends into it a long, tapeiing, fibrous
prolongation from its posterior extremity to secure a firm hold, whilst its
body projects freely from the mass (see Part I. p. 282). Moreover, it is
this genus only that is aggregated, all the rest being solitary. These pecu-
liarities may be held to justify Perty in erecting tliis genus into a family.

The presence of numerous stomachs and of a distinct ahmentary canal, it
need only be said, are details of organization required by the hypothesis of
Ehrenberg, and supposed in some instances to bo demonstrated by feeding
with coloui-ing matters.

As Ehrenberg rightly intimates, Ophrydina may be briefly defined as Vor-
ticellina living in a sheath, instead of being supported on a pedicle. From
this general definition Ophrydium is necessarily excluded as an exceptional
form ; and it becomes, therefore, a matter of regret that a family should be
named from a genus in no sort its tnio type. Perty has invented the name
" Vaginifera " for a family containing the two genera Vaginicola and Co-
thumia ; and it is certainly preferable to Ophrydina, whether Ophrydium be
comprehended in it or not.

Genus OPHRYDIUM (XXX. 5, 6).— Lorica gelatinous ; animals clustered
m consequence of perfect self-division of the body, but imperfect of the
lonca. This circumstance gives rise to very peciiliar external appearances •

uoo

SYSTEMATIC HISTORY OF THE INFUSOllIA.

for each body very frequently divides itself, the two poi-tions separating
entirely, — the gelatinous lorica forming only a separating wall. In this manner
thousands and millions of connected animal-cells are quickly formed, appear-
ing as gelatinous globular masses or balls.

It is a misapprehension, on the part of Ehrcnberg, of the actual phajno-
mena, when he states that the large gelatinous ball formed by the multipli-
cation of Oplirydia is the result of imperfect fission of the lorica ; for, as we
have pointed out, the animalcules have no lorica or sheath in the sense
Ehrenberg intended, but are merely attached by a sort of non-contractile
stalk penetrating far in the interior, upon the surface of the gelatinous mass.
When fuUy contracted, indeed, it is drawn down upon and slightly presses
into the soft mass, raising this as a rim around it ; consequently it is also an
error to say that the mass is composed of numberless little ceUi, seeing that
nothing Like a cell is constructed around the animalcules. Stein found within
the interior of the gelatinous mass numerous intertwining and twisted fibres,
wliich he concluded were vegetable parasites, probably of the family Lepto-
mitse. Agardh and other botanists have described the gelatinous balls of
Oplirydium as a species of Nostochineae, under the name of Nostoc pruni-
forme ; but this is a great mistake, for no cellular or proper vegetable stinie-
ture is present.

Stein has added to the vaginated VorticelUna, or the Ophrydina, the genus
Lagenophrys ; and Dr. Wright {Edin, New Phil. Journ. 1858) the interesting
genus Lagotia.

becomes oval or globulai-. Fission is
only longitudinal ; when an Ophrydium
quits its hold after fission, it swims away
by means of a temporai'ily developed
posterior wi-eath of ciha, just like a Vor-
ticella. It is found encysted, and. Stein
believes, in an Acinetiform phase (xxx.
7, 8). Vividly gi'een, and associated in
smooth and globulai" clusters or masses,
which vai'y m size from a pea to a ball
five inches in diameter ; they are either
free or attached. Ehrenberg states that,
in May 1837, he saw hundreds of clusters
as large as the fist, which, by the evolu-
tion of gas, were at inten'als elevated to
the surface, and driven bv the wind to
the edge oi the water, tn sea- water:
also found by Briglitwoll in fresh water,
and in a small turf-pit, upon tendrils of
roots of marsh-plants, and the stalks of
the white water-lily. Length of single
animalciUe .stretched out, 1-120" to
1-90".

OPHBYDruM versatile {Trichoda inqiii-
lina et Vorticella versatilis, M.) (xxm. 5,
6). — Body fusiform, tapering to a fine
extremity from behind the middle, and
anterior to it contracted into a cylin-
drical neck, supporting a funnel-shaped
head sunnounted by an annular periston!
with a ciliated rotary disc. The mouth
opens into a naiTow and long ciliated
oesophagus. The contractile vesicle is
seated near its end ; the nucleus is long,
narrow, and twisted. The external sur-
face is thrown into close annidar folds ;
and usually three longitudinal plaits ex-
tend from the posterior end as far as the
middle of the body, which disappear
when the body contracts. A subjacent
cortical lamina is evident, and, imbedded
^^^thin this, numerous chlorophyll utri-
cles, giving the animal a vivid green
colom". When contracted, the body as-
sumes the fonii of a long-necked ilask,
and even the nucleus shortens itself.
In more complete contraction the figure

Genus TINTINNUS. — Ophrj'dina which possess divisibility of the body,
but not of the iii'ceolate lorica ; the body is attached to the interior of thi'
.sheath by a flexible pedicle (somewhat similar to the clapper of a bell) ; the
mouth seiwes both as a receiving and discharging orifice ; stomach-ceUs and
traces of a yellowish ova-cluster are more or less visible ; self-di^^sion was
known to Midler.

Tintinnus, as before noted, is a genus not admitted by Dujardin ; Perty
likewise ignores it ; and Lachmann {A. N. JL 1857, p. 119) feels the necessity
of excluding it from Vorticellina (using this tenn in a wider sense, so as to

OF THE OPHRYDINA.

001

include Ophiydina), since it is ciliated all round, and differs greatly from them
in the form of its alimentaiy apparatus. Moreover, a species inhabiting a
gelatinous sheath occurs in the freshwater ponds in the Thiergarten at Berlin.

drical, hyaline, indistinctly annidar ; ra-
ther attenuate and truncate posteriorly.
1-440". In the Baltic.

T. Campanula. — Hyaline; sheath widely
campanidate, dilated in front, pointed
behind. 1-290". In North Sea and
Baltic.

T. denticulutus. — Sheath cylindrical,
hyaliife, sculptm-ed with oblique rows of
dots, front margin acutely dentate ; pos-
terior extremity pointed.. 1-220". In
the North Sea.

TiNTDTOUS inqmlinus. — Hyaline or
yellowish ; lorica cylindi'ical, glass-like,
bell-shaped. 1-670", with stalk 1-240".
Li sea- water, on Algse.

'^L.subidatus (Vorticella vaffinata,M..'). —
Hyaline ; slieath conical, with a posterior
subulate elongation. Ehreuberg observes
that, if this elongation of the lorica were
called a stalk, we shoidd require a new
generic name for the animalcide. Length
of lorica 1-90".

T. Cothurnia. — Hyaline ; sheath cylin-

Genus VAGINICOLA (XXYII. 10, 11 ; XXVIII. 18, 19).— Neither the
body nor the lorica stalked ; a wreath of cilia surrounds the tnincated front
portion, witliin which is the oiifice or mouth. The polygastric apparatus,
the passage of the food onwards, its return, and the exit of the refuse near
the mouth, and coloured ova-granules, are mentioned by Ehrenberg. In-
crease by longitudinal self-division of the body (not of the lorica) has been
seen in aU the species.

To the above accoimt must be added, according to Stein's observations,
that the body of Vaginicola has in front a peristom, from out of which a
" rotary apparatus " protrudes, consisting of a ciliated disc, supported on a
stout stem or pedicle, just like that of Vorticella. A mouth opens on one
.side of the disc, and leads into an oesophagus ; but no polygastric structure, as
surmised by Ehrenberg, is visible, although munerous aUmontaiy vacuoles
are usually present. Ova-granules, again, are merely hypothetical, and, as
in other Infusoria, where mentioned by Ehrenberg, represent particles of
various kinds, but mostly coloured granules. In a new species noted by
Dr. Wright, the tubular sheath has a peculiar structiu-e in the form of a
valve, which closes over the animalcule when it retreats to the bottom of its
case (XXVIII. 18, 19).

In all the particulars of internal organization, Vaginicola resembles Vorti-
cella. Propagation by fission and gemmation is very distinct ; by the former
process more common (XXVII. 10, 11). The develoi)ment of the bud takes
place from the base of the parent, and within its sheath. The youno- beino-
produced by either process, is furnished, as in Vorticella, with a posterior
wreath of cilia, whilst it is endowed with free locomotion (XXVII. 11). It
frequently happens, as represented in the last-quoted figiu-e, that the youno-
being assumes on its formation a contracted ovoid form, with its frontal wreath
retracted. Upon the appearance of the posterior whorl of cilia, and aided by
its movements, the animal loosens itself, escapes from the parent-case and
swims freely away, elongating itself, it may be, if previously contracted', and
assuming finally all the chai-actcrs of a perfect Vac/inicola, by developino-
arovmd it its own special sheatli. '

On the other hand, the contracted individual may become actually encased
Avithin its integument (in other words, encysted), and, as Stein believes
may thereupon assume all the characters of an Acineta, and eventually give
birth to a ciUatcd embryo (XXVII. 11-15). This metamorphosis, however
IS not generally accepted. The specific characters in this genus are for the
most part deduced from the figure and dimensions of the external sheath or
lonca (Ehr.). and must, therefore, as Stein points out. be admitted with much

002 SYSTEMATIC HISTOIIT OP THE INFUSOMA.

reservation ; for this envelope changes greatly in figure, in size, and structure,
according to the age and the different vital conditions under wliich the animal
lives. Stein met with one example in which a short pedicle attached the
Vaginicola crijstallina to the bottom of its sheath : indeed he does not admit
Cothurnia and Vaginicola to be genoricaUy distinct ; for the stems supporting
the sheatli of the former are, he says, not generally longer than those belong-
ing to young VaginicolcB. In this point therefore he agrees with Dujardin.

We have observed how close the resemblance is between Vorticella and
Vaginicola ; on the other hand, the points of separation are found in the
absence of a pedicle in the latter, which is fixed to the bottom of a sheath by
its posterior extremity, its anterior remaining fi-ee, and its whole body
capable of extension or retraction within the orifice of its case. Lastly, the
figm-e of the body is much more elongated in Vaginicola than ia Vorticella.

Vaginicola crystalKna {Vorticella
ste7itorea et Triclwda ingenita, M.) (xxvil.
10, 11). — Sheath crystalline, sti-aight,
pitcher-shaped, slightly contracted near
the open end ; gi'auules green. Length
of lorica 1-210". Upon Lemna, &c.

V. tincta. — Sheath brownish-yellow,
urceolate, and nearly C3dindrical; body
hyaline. Length of lorica 1-280". Upon
Zygnenui decimum.

V. decumbens. — Sheath brownish yel-
low, oval and compressed, decumbent on
one side, which is flattened; the body
hyaline. Length of lorica 1-280".

Steia con-ects this description by
stating that the oval plano-convex sheath
has not a simple crescentic openiog,
but is conti-acted so as to form a short
tubidar neck, or projecting process, with
a transversely oval or renirorm mouth.
It has consequently the closest resem-
blance to the sheath of Lagenoplmjs Am-
pulla ; but its orifice is rigid, and not con-
tractile as in the lattei', and, further,
the animalcule is not afiixed to its mar-
gin, but to the bottom. On Lemna,
ZA/(/)iema, &c.

'v. valvata (Wright) (xxvni. 18, 19).
— Distinguislied from V. crystallina by
the remarkable valve existing in its case
or sheath — which closes, in an inclined
position, over the animal when it retreats
to the bottom of its case ; by the body
being colourless, without the green glo-
bules seen in V. crystallina ; and by being
<an inhabitant of sea-water instead of
fresh. Plentiful on zoophytes and sea-
weeds.

V. vaginata. — Under the name Vorti-
cella vaginata, Miillor described a Vagi-
nicola found in the Baltic, having a deli-
cate pedicle as long as the body, which
is supported by it, at the upper end of a
sheath six times longer than itself, into
the orifice of which it can with difficulty
enter.

V. pedzmculata (Eichwald). — Body
attached to the bottom of the sheath by
a short stem. This presumed species is
actually nothing more than a variety of
V. crystallina, as Stein has shown.

V. Ampidla. — Midler described this as
larger tlian most animalcxdes, as dwelling
in a bottle-shaped sheath, as very con-
tractile, grey, and soft, and as occupying
variouspositions within the case. Found
in the Baltic, and, by Mr. Bi-ightwell, at
Lowestoft. Dr. Wright (JEdin. Phil. Journ.
1858, p. 5) says it has a bilobed ciliated
organ, and so far resembles Lagotia.

y.ovata (Duj.). — Body of a lengthened
ovoid figure, placed in an m-ceolate case.
Length of body 1-1000", of case 1-550".
Apparently distinct from V, crystallina.
On Zygnema in pond-water.

V. ? (Brightwell) (xu. 70).—

Body double, of a green colour. Pro-
bably undescribed. On duck-weed and
other small aquatic plants. It is doubt-
frd whether this bemg is other than a
Vaginicola in process of spontaneous
fission.

V. gra)idis (Perty). — Sheath cylindri-
cal. Animals with a circular ciliated
opening. Length of tube 1-108", of the
extended animal 1-84". Stein considers
this species a mere variety of V, cry-
stallina ; but besides difiering from it in
size, it does so also in the figure of its
slieath, which is not rounded below, but
abruptly truncate, and not uairower
above, but rather wider. Aniinnlcides
hyaline, often filled with sporozoids and
chlorophyll granules; when rontract^jd
it does not occupy more tlian a third of
the tubular sheath. Among water-plants.
Uncommon.

The figure of this species presented by
Perty is verj' rude, conveying not the
slightest conception of the details of
extenial stnicturc or of internal organ-
ization.

OF THE ornRYDrNA.

603

Gemis COTHURNIA (XXX. 12-16).— Lorica (sheath) urccolate, and sup-
ported on a rigid pedicle. A wreath of ciHa is placed upon the flat frontal
region:; and the mouth, with the anal opening, lies on one side, within the
vestibiiliun. The body is conti-actile, and can withckaw itself within the
stiff sheath ; fission longitudinal.

It is unnecessary to enlarge on the structural details of this genus, inas-
much as they are in all particulars like those of Vaginicola, from which it is
separated only by its sheath being stalked.

aspect. The two angles in front are ex-
tended upwards and outwards, but at the
same time curved iiiwai'ds at their ex-
tremities as two horns. The walls of
the sheath aa-e at first soft, colomless,
and hyaline, but subsequently become

CoTHUBNiA imberhis (Vorticella folli-
culata, M.). — Pedicle mostly bent and
much shoi-ter than the sheath, which
has, when old, a yellowish colour.
Sheath tubular, nan-owed anteriorly,
without an everted margin. Even when
outsti-etched, the animal extends little
beyond the mouth of the sheath; its
periston! is scarcely appreciably thick-
ened, and not everted at all; it is evi-
dently ciliated. The disc of the simple
rotary organ is level on its surface, and
scarcely rises above the sheath. Diges-
tive tube long and narrow, extends be-
yond the centre of the body, and near
its commencement has fi'om 3 to 4 long
cUia. Near to it, on one side, is a round
conti-actile vesicle, and on the other a
short, band-like nucleus, almost straight
or slightly reniform in figure. Longi-
tudinal fission fi-equently obser^-ed, and
sufficiently often the process of gemma-
tion at the base. Length of sheath 1-288"
to 1-240".

Ehi-enberg remarks, " This animalcide
had often swallowed green Monads, and
yet accepted indigo. Trichodina vorax
is the enemy of this species." Upon
Cyclops quadrtconiis. Length of sheath
1-280".

C. maritima. — Pedicle much shorter
than the hyaline sheath; body hyaline
and whitish. Length of sheath 1-570".

C. maritima is very closelj' allied to
Vuf/inicola crystalUna : not the least dif-
ference between the animals themselves
is perceptible, and the figure of the
sheath is the same, — the only essential
difference being that in the Cothurnia
the sheath is supported on a thin, solid
stem, 1-48" to 1-3(3" in diameter and
of a length equal to its own.

C. Ilavnicmis. — Pedicle much longer
than the hyaline sheath ; body whitish.
Length without stalk 1-280".

C. Sivhohlii (Stein) (xxx. 13, 14).—
Sheath stalked ; stalk short, thick, colour-
less, transversely and deeply m-inkled,
and thickened at its junction with tlie
sheath. The last is campauulnte, strongly
compressed in front, dilated and bellied
out posteriorly, especially on the dorsal

yellow and leatheiy, and at last of a
more or less deep insty brown colour,
and of a corneous consistence. The
colomiess and, with reference to the
sheath, small contained animal is cylin-
diicai in figure, contracted behind, and
very similar to that of Vaginicola crystal-
Una. Its periston! forms an annular
thick border, and is beset with few cilia.
The digestive tube, which extends to
nearly the cent!'e of the body, has close
to it the contractile vesicle, and a little
further behind, the thick, shoi-t band-like
and semicircular nucleus, \'isible without
the !ise of cheniical reagents. Multipli-
cation takes place by longitudmal fission.
Length of largest sheaths 1-190". On
the limbs and other parts of Entomos-
traca ; verj^ abundantly.

0. Astaci (Stein) (xxx. 15). — Sheath
supported on a short, w!-inkled, thick
pedicle; having itself a tubular figure,
rather contracted at the middle, and its
border widened and everted, whilst its
posteiior half is shghtly venti-icose and
roimded at its extremity. Its consist-
ence is leathery or horny when old ; it
is transparent and of a pale yellow colom-,
but never a rusty brown. ^Tien fidly
outstretched, the animal prot!-udes a con-
siderable distance beyond the mouth of
the sheatli, differing in this respect, as
well as by its thiclc ann!ilar periston! and
Its cylindrical outline, from Cothurnia
imhcrbis. The digestive tube attains the
middle of the animal, is very naiTow,
and has both tiie contractile vesicle
and the short band-like nucleus placed
near its tennination. Fission is longi-
tudinal. °

Old specimens attain a height of
1-288", and a width of l-(!00". Also
found on Eutomostraca. It is very closely
nllied to C. ivihcrbis ; but, besides the
ditlerences noted between the animal-
cules, the stem of the latter is relatively

604

SYSTEMATIC HISTOllY OF THE TNFUSOEIA.

thinner, the posterior extremity of the
slieath pointed, and the anterior con-
tracted.

C. curva (Stein) (xxx. 12) resembles
generally a contorted specimen of C.
Astaci; but old specimens have rusty-
red-coloiu-ed sheaths. The pedicle of
the sheath is always cm-ved ; the anterior
third of the sheath is bent outwards, and
the posterior half ventricose, particularly
on the dorsal surface. The bending to
one side causes the mouth of the sheath
to be oblique. The contained animal-
cule agrees generally with that of the
two preceding species. Length of sheath
1-360". Upon the ova-lappets of Ento-
mostraca.

Stein doubts the independence of this
.species; for, besides being imperfectly
observed by Ehrenberg, it is exceptional

in the animalcule not being fixed at the

bottom of the sheath.

C. Piq^a (Eicliwald).

C. perlepicla (Bailey;. — Apex of sheath
attenuated, slightly cun-ed ; surface en-
tirely covered with spirally decussating
rows of hexagonal cells ; oiifice crenulate.
Contained animal unkno\vn. St. George's
Bank and New Haven Harbour, New
York.

C. Fhscularia (Perty). — Hyaline ; the
cilia of frontal segment collected in two
gi'oups, recalling thereby the aspect of
the ciliary apparatus of a Floscularia.
Sheath of the same form as that of C. im-
herbis. The animal lives much in a con-
ti'acted state within its sheath, and ex-
tends itself A'ery slowly : on the contrary,
the act of contraction is rapid. 1-260".
Among Callitnclue.

Genus LAGENOPHEYS (Stein) (XXX, 29-36).— Sheathed Vorticellina,
differing especially from Cothurnia and Vaginicola by the zooids being at-
tached to the cii'cumference of the mouth of the sheath, and freely dependent
from it, instead of being affixed to the bottom as in those genei'a. The
.sheath itself is without pedicle, and adheres to foreign bodies by one side, as
does that of Vaginicola decumbens : this side is flattened, and may be referred
to as the abdominal surface. The opposite side, or the back, is strongly
vaulted. The mouth of the sheath is very much naiTowed, and furnished with
a prominent, flexible, double lip, which can be closed when the contained ani-
malcule contracts itself. This last is closely adherent by its peristom within
the margin of the orifice of the sheath, and has generally the same figui-e
as the sheath, but not the same dimensions ; hence it lies loosely within it.
The mouth of the sheath and the peristom are of equal diameter ; and through
them a long stalked rotary organ projects, terminated by a circular ciliary
disc. When the animal contracts, the rotary apparatus is withdi'aAvn, the
peristom closes like a sphincter, and the two-lipped mouth of the sheath by
its closure completes the secmity of the whole being. Eeproduction takes
place by oblique fission and by gemmation.

of sheath is 1-380" ; the greatest width

Lagenophhys vaginicola (xxx. 29-
.36). — Sheath elongated cordate ; in the
centre of its broader and truncate end is
the circular orifice, having two semi-
circular, prominent, valvular processes,
which collapse together when the con-
tained animalcule contracts itself. The
contracted posterior extremity has a veiy
thick wall. Tlie enclosed animal is o\ ate,
and adherent by its naiTOw peristom to
the orifice of the sheath, and leaves a
large interspace posteriori)^ between itself
and the enclosing wall of its sheath, ex-
cept when it retracts itself. The 3'oung
formed by gemmation, as well as the
products of fission, can escape only when
the parent being loosens its attachment
from the aperture of the shnnth, and so
funiLslies an outlet. The medium longth

1-040". On Cyclopsina staplu/lim.

L. Ampulla. — Sheath resembles a
plano-convex circiUai" lens, except in
having an anterior projecting everted
rim around the oral onfice. The ani-
malcule has the same figure as the
sheath, and an internal organization like
that of tlie preceding species. Biametor
from 1-480" to l-.'300". On aquatic
animals, Entomostrnca, and the like.

L. Nassa.—\er\ similar in figure luid
size to L. Ampulla, but has a different
profile or lateral outline. The sheath,
although nearly spherical, is plano-
convex, somewhat truncate m front, and
emarginate on the "PPer surface, ns is
best scf-n in profile. The mouth of the
shrath is prolonged as a cylindricnl, two-

0¥ lOE ENCHELIA.

605

lipped process, capable of beino^ retracted, occurs ou Gammarus and other aq^uatic
Is more rare than L. Ampulla,o\xt, like it, animals.

Genus LAGOTIA (Wright) (XXVIII. 20-23 ; XXXI. 7, 8).— Sheath or
case retort-shaped, with a cylindi-ical neck, plain or annulated ; colom-less,
yellowish, or dark green ; body long, cylindi-ical, attached by its posterior
end to the bottom of the case, terminated anteriorly by a forked (fiu'cate)
head, or two long, flattened ciliated processes, between which is the opening
of the oral cavity, which extends backward into the body as a tapering
oesophagus, ciliated on its fi'ee surface. The green colour of the body in
L. vii'idis is not due to dispersed globules, but to a staining of the sarcode
itself. Longitudinal fission has not been seen ; but development by a free
ciliated embryo, very unlike the parent, has been observed in L. producta.

Lagotia vmdis (xxviii. 20-23). —
Case resembles a flask or amphora lying
on its side, ha'ving the neck bent more
or less shai-ply upwards, and dilated into
a trumpet-shaped mouth. Its colour is
dark sea-green, in the larger specimens
nearly opake. Animalcule green, cylin-
drical; its ciliated organ, when seen in
front and erect (f. 23), appears like a
naiTow horseshoe ; whilst from the side
(f. 21) the anterior extremity of the ani-
malcide bears a resemblance to the head
and ears of a hare — a Ulceness increased
by the wagging movements of the long
processes. In young specimens the lobes
of the fui'cate process are blunt and
short, and the ciliary band, along which
the cilia are aiTanged, is placed at a little
distance from their margin (f. 20), instead
of being close to it (f. 22). Plentiful on
marine shells and AJg£e, Firth of Forth
and TjTiemouth. Embryonic develop-
ment has been detected by Ur. Wright
in this species.

L. hyalina. — Colomiess ; lobes of cili-
ated organ wider and blimter than those
of X. viridis ; cell biuied in the substance
of the shell of Alcyonidium hirsutiim, and
therefore not seen. Granton and Queens-
ferry.

L. atro-purpurea. — Colour of animal
that of a mixture of ink and water. Cell
yellowish-brown. Probably a variety in
colour of L. viridis, with which it was
foimd.

L. producta (xxxi. 7-13) (Dr. Wright
in lit). — Neck of sheath exceeding!}^ pro-
longed, anmdated ; sheath of a pale yel-
low-brown colour. Ajiimalcide (zooid)
two or three times the length of the-
sheath, attenuated ; ciliated lobes erect,
divergent, and reciuTed at tips; colour
of zooid deep blackish gTeen.

Dr. Wright observed the development
in this species of ciliated embryos, which,
after passing through the stages seen in
figs. 9 and 11 (xxxi.), and canymg ou
an active existence as free ciliated ani-
malcules, form an attachment to some
surface and proceed to develope a sheath
and the characteristic ciliary lobes. The
ti'ansforniation from ciliated embryos to
Laf/otics ti'anspired in the course' of a
night, — the sheath even, during that
time, being completed with its rings. The
above fact constitutes an interesting ad-
dition to tlie illustrations of embiyonic
development among Ciliata, quoted in
the section on that subject (p. 353).

FAMILY v.— ENCHELIA.
Animalcules having a distinct alimentary canal, ynth. an oral and an anal
orifice at the opposite ends of the body ; without lorica. Locomotion eftected
by \ibratile cUia in all the genera except three, viz. Actinojphrys, Tricho-
discus, and Podoiihrya, in which it is performed by slow-moving feelei-s (ten-
tacles). In aU but those exceptional genera, organs of nutrition have been
demonstrated by the employment of coloured food ; but only in one has the
entire course of an alimentary canal been traced, though in most its tnnsit
through the body is indicated by its discliargc through the posterior outlet
Ehrenberg states that the polygastric stnictm-c is to be soon in all the genor'v
except the Arabian genus Disoma. A nucleus and vesicle are generally present
Complete self- division, both longitudinal and transverse, has been observed •
but not gemmation. The most curious animalcides among them arc llio
double-bochcd Dmma and the tecth-bcaring Prorodon.

SYSTEMATIC H18T0BY OS THE INFU80HIA.

The genera are distributed as follows : —

^Vibratile f Body simple
ciUa at the I
Direct mouth ... | Body double

trimcated ^ . ,rj-

Enchelys.

Disoma.

03 .

tute of vi--| not vibra-'

bratile tile

cilia Stalked

Eays at the edge Trichodiscus.

Podophrya.

Oblique
truncated
mouth
1^ (with lip)

No neck

With neck

Trichoda.

Lacrymaria.

Surface of "
body with
vibratile
\^ cilia

Oblique truncated mouth, with lip
Du-ect truncated mouth, no lip . . .

Leucophrys.
Holopluya.

Teeth present.

Prorodon.

In the arrangement of Dujardin, and iinder his fourth order — comprehend-
ing " ciliated Infusoria without a contractile integument, and with or without
a mouth " — a family having a similar name, EncheUna (Enchelyens, so-
called after a genus Enchelys) is instituted. But, most imfortunately for
science, this family and this genus, with respect to the animalcules they
include, in no way correspond with the similarly-named family and genus
of Ehrenberg. This is remarked by Dujardin himself ; and he adds, with
reference to the genus Enchelys (Ehr.), that, in the whole coiu'se of his ob-
servations, he never met Avith any Infusoria bearing the characters attributed
by Ehrenberg to that genus, and he is led to conclude that the beings intended
are Paramecia with a terminal mouth, or else Bursar ice imperfectly examined,
and the cilia of the surface overlooked.

The family Enchelina is thus briefly characterized by Dujardin : — " Animals
partially or entirely covered with ciHa, dispersed over the sui-face ii'regularly ;
mouth wanting."

The family Cyclidina (Ehr.) seems, indeed, much more neai'ly allied to the
Enchelys of Dujardin ; but its characters, as given by Ehrenberg, ai-e not
sufficiently definite to attempt an identification.

Stein severely blames Dujardin for the transposition of generic names he
has been guilty of in the case of this genus and Cyclidium ; for, as he justly
observes, it is a proceeding productive of confusion and error. The Enchelys
yioclulosa, he adds, is the Cyclidium Glaucoma (Ehr.), and scarcely distin-
guishable from E. triquetra (Duj.). Acomia Ovidum seems nothing else than
Cyclidium Glaucoma, and Uronema marina another closcly-aUied form, and,
like Glaucoma itself, the embryo of some other animalcule. The three
remaining species of Enchelys enumerated by the French writer, viz. E. cor-
riiyata, E. suhangidata, and E. ovata, are so imperfectly obsei-ved as to be
worthless, and their union in the same genus Avith Glaucoma quite unwar-
rantable.

Yet, if Dujardin has proceeded vciy incautiously in rejecting the En-
chclia of Ehrenberg and in redistributing its genera, no apologist of the
Berlin naturalist ^v-ould contend that it shoidd be loft as it is; for every
pci-son having any acquaintance Avith the beings brought together a.s En-
chclia will be stnick with their heterogeneous chaructcra. Actinophrys,

OF THE ENCHELIA.

607

TncJiocUscus, and Podophrya belong evidently to a iy^o of bcmgs altogether
different from the ciliated animalcules included in the family ; and we have
consequently treated them as an entirely separate group from the ciliated
Protozoa in our general histoiy, and have hkewise, in the present portion
of the work, given theii- systematic descriptions apart. The genus Disoma
is a very doubtful member of this family, and is even marked as such by
Ehrenberg, who had very imperfectly examined it.

The family Enchelia does not enter into the system of Perty, who disperses
its members among different families according to his appreciation of their
several affinities. Among the rest, his family " Tapkda" includes some species
of Leucophrys of Ehrenberg and the genus Acomia of Dujardin, along with
several newly-constructed genera, the account of which wlU be annexed to
this present group.

The Eanuly " Tapinia " is thus characterized : —

" CUia scattered at large, or collected in groups,- but not arranged in rows.
Animals mostly very small. Mouth not apparent, but its presence revealed
by the admission of food." This group includes the genera Acrojpisthium,
Acomia, Tnclioda (Duj.), Leucophrys (Ehr. ?), Gyclidhcm, Bceonidium, Opis-
thiotriclia, Siagontlicr'mm, and Megatricha.

Another alhed family, called " Apionidina," contains a species of Leuco-
phrys (Ehr.). Perty assigns it the following characters : — " Family Apioni-
dina : Body small, soft, thicker at one end than the other ; ciha in longi-
tudinal rows ; mouth, where visible, situated at the anterior end." The genera
comprised are Ptyccidium, Colohid'mm, and Apionidium. The first-named
genus has, as its type, the Leiicophrys pyriformis (Ehr.) ; but the other two
axe advanced as new genera, foimded on newly-observed beings.

Both in this family (Apionidina) and in that of Tapinia, several supposed
new genera are established by Perty, which, to render our compendium com-
plete, we are bound to notice and describe, although we regret to record such
a midtitude of genera and names, as we feel highly doubtful of their claim to
consideration as independent beings.

Genus ENCHELYS (XXVIII. 64, 72, 73).— Vibratile cilia upon sui-fiice
wanting ; mouth terminal, truncated (direct, not oblique), devoid of teeth ;
suiTOunded by a Avreath of ciha. An asophag-us is not seen except during
the passage of food. An anus is found in all, and in E. Farcimen a contractile
bladder. Self-division is transverse and complete.

Dujardin defines his genus Enclielys as having a cylindrical, oblong, or ovoid
body, covered with erect uniform ciha, ii-regularly disposed.

Cohn (Sicbold's Zeitschr. 1851, B. iii. p. 273) treats this genus as sjTiony-
mous with Enclielys (Duj.), and believes that several of its assigned species
are not independent animalcules, but embryos of Loxodes, Oxxjtricha, and
allied genera.

Enchklys Pupa (M.) (xxviii. 72, 73).
— Tiu'gid, club-shaped, attenuated an-
teriorly ; filled -with gi-eenish vesicles, or
only with molecules; neither a nucleus
nor a vesicle could bo found by Ehren-
berg. Ehrenberg has figured (in his
large work of 18:58) the presumed form
of the polygnatric nutritive system of
this species separately, stating it to be
remarkably distinct. ' Oouimon in stag-
nant bog-water. 1-140".

E. Farcimen (E. Farcimm et Vibrio in-
tcstinum, M.) (xxviir. G4, n-A;).— Smaller,

more cylincbical and slender than tho
preceding ; granides whitish. These
creatiu-es prey on other animalcules
nearly as large a.s tliemselvos, which
they devour entire; this will account
for the variety of fonus which they
assume, and which require an observer
to be very watchful and cautious before
ho can pronounce on the identity of a
species. Ehrenberg, by patient obser-
vation, saw one indi\ idual undergo a
great variety of forms in the act of
swallowing a young Kolpuda CucuUus •

G03

SYSTEMATIC HISTOEY OF THE INFUSORIA.

illustrated in fig. 64, a-k. In stagnant
water. 1-430".

E. infuscata. — Oval or splierical ;
whitish ; mouth not prominent, encircled
by a brownish liug. When fed with
indigo, numerous vacuoles become filled.
In bog-water. 1-280" to 1-240".

E. nvhulosa (M.). — Ovate, hyaline;

mouth projecting. This species receive.'?
camiine and indigo vei-y readilv. 1-230"
to 1-570".

E. nodulosa (Tin].) = Cyclidiuni Glau-
coma (Ehr.). E. Iri^uetra (Duj.j is a
mere accidental vanety of the same
animalcule.

Geuus DISOMA (?). — Body double, destitute of cilia ; oral extremity
truncated (direct) ; mouth ciliated, devoid of teeth. AVithin the bodies
numerous little vesicular cells (stomachs) are observed, and the discharge of
excrement may be seen to take place at the posterior extremity of each body.

As already noticed, tliis is a very imperfectly-examined and doubtful
genus. The being described may be interpreted as one undergoing longitu-
dinal fission ; but there is no one character given, adequate to determine to
what family of animalcules it would be referable.

UisoMA vacillans consists of two
clavate and filiform corpuscles, hj'aline,
and attenuated at the anterior extremity.
Ehrenberg remarks, " Both bodies fre-
quently swam parallel beside each other,
and tm-ned on their long axis, moving

onwards quickly, though in a vacillating
manner ; sometimes both bodies gaped
widely apart fi'om each other, but never
so widely as to form a sti-aight line.
1-380". On Mount Sinai, Ai-abia.

Genus TRICHODA. — Body devoid (?) of liaii-s or ciHa; without a con-
striction or neck ; mouth obliquely truncated, destitute of teeth, but pro-
vided Avith vibratile cilia, and a lip. Coloui'ed food is received ; the anal
orifice is at the posterior extremity. The oblique direction of the mouth
gives rise to a very characteristic uppcr-lip-like projection. In T. Pyrum
only has self-division been observed. All the species are colouiiess.

In the system of Dujardin there is both a family Tricliodina and a genus
Trichoda. Speaking of the relations between them and the genus Trichoda
of Ehrenberg, he observes : " M. Ehrenberg has placed in his famUy Enchelia
a genus Trichoda, which in part corresponds with ours ; and he has, besides,
dispersed among Leucophrys, Enchelys, Traclielius, Loxodes, &c., many Infu-
soria which we have brought together in this family (viz. Trichodina) ; but,
unlike him, we are unable to see theii- digestive organs."

The Trichodina are soft, variable, flexible animalcules, ciliated, and have
either an evident mouth, or one indicated by a vaiying arrangement of longer
cilia. Dujardin would have it understood that this family is only pro-visional ;
to comprise a tribe of animals intermediate in organization between the
Enchelina — the most simple of ciliated — and the Keronina, which conduct to
the highest forms of infusorial life, having defined mouths, and an armature
of styles, hooks, &c. The genera included by Dujardin in this fiimUy arc
Tricfioda, Trachelnis, Acineria, Pelecida, and Dilejo 'tus ; the last two having a
higher grade of organization. The first-named is thus described : —

Genus Trichoda (Diij.). — Ovoid-oblong, or i)yriform, rather flexible ante-
riorly, with a row of cilia dii-octed backwards, and appearing to indicate the
presence of a mouth. Their smface does not appear reticulated, or ciliated in
rows, as it is in Acomia and Enchelys. The Trichoda are chiefly found in
putrid infusions and in stale marsh-water.

Trichoda ptira (Knipoda Pynim, s\o\\s\ ns\inl\y \k\\\x CycUditnu Glaucoma.
jM.). — Oblong, cliib-shnped, attenu- 1-720".

fitfd anteriorly; mouth Jiitordl ; vncu- Tliis species clo.«(-ly i-osombles Zrw"-
oles small. Common in vegetable infu- phrys pyn'fonin-i, which is somewhat

OP TKE ENCUELIA.

609

larger and ciliated througliout. How-
ever, the reality of T. pitra as a species
is very doubtful, — tlie small size of the
vacuoles, the featiu-e most relied on by
Ehrenberg as distinctive, being in reality
riot af all so, but prone to gi-eat varia-
tions, determined by sm-roimding cii'-
cimistances. It swims slowly, revolving
as it proceeds.

T. Nasamomum. — Cylindrical, exti'e-
mities equally obtuse, mouth large, and
elongated laterally. 1-288".

T. ovata. — Ovate, tm-gid, attenuated
anteriorly; mouth small and lateral.
1-480".

T. (?) JEthiopica. — Oblong, attenuated
posteriorly ; imder side flat ; mouth
large. 1-600".

T. Asiatica. — Oval, oblong, cylindrical,
roimded at both ends ; mouth small.
1-860".

This species, together with the three
immediately preceding, must be regarded
as doubtful ; for they were merely casually
examined by theii" discoverer whilst tra-
velling, and when, as we must suppose,

he had neither the means of comparing
the beinofs with others akin to them,
nor very favourable opportunities, in the
rough accommodation of desert tra-
velling, for careful microscopic examina-
tion,

T. Pi/mm (Kolpoda Pi/rum, M.). —
Ovate, turgid, acute anteriorly. Amongst
Oonfervse on Mount Sinai. 1-1200".

A species with this name is also men-
tioned by Dujardin an = -Kolpoda Pyrum ?
(Miiller). It is thus described : — " Body
ovoid, oblong, narrowed anteriorly, or
pyrifomi ; thicker in one direction than
m the other;" and he goes on to say
that this is the same being as the Leu-
cophrys carnium (Ehr.).

T. angulata (Duj.). — Oblong, obliquely
and regularly plaited or angular, often
with one or more superficial vacuoles.
1-900".

T. Lynceus. — The animalcule described
under this name is (says Cienkowsky)
probably no other than the young phase
of various OxytrichcB and Stylomjchm
(Siebold, Zeits'ch. 1855, vol. vi. p. 301).

Genus LACRYMAEIA (XXIV. 274, 275).— Body with a long narrow
neck, slightly enlarged near the termination, where is situated the ciliated and
lateral (lipped) mouth, destitute of teeth. Body not ciliated. Locomotion is
performed by means of the neck, the distensible body, and the oral cilia. The
proboscis-like lip is very short, sometimes distinctly articulated, and projects
but little beyond the oral orifice. Colom-ed food is received by L. Proteus,
and its discharge may be seen to take place from the posterior extremity in
one species ; in another, green granules (ova) are present.

The genus Lacrymaria of Dujardin agrees maialy with that just defined ;
but the French author differs entu-ely fi-om Ehrenberg, by stating that the
LacrymancB are distinctly ciliated on their surface, and that the cilia are
disposed in regular series among the reticulations of the integument.

Dujardin, in his notes on Lacrymaria, has some very jnst observations on
the relation between this genus and the Phial'ma and Traclielocerca (Ehr.).
He says, the species of Lacrymaria, which Ehrenberg noticed to be generally
not ciliated on the body, have been classed by him according to the relative
position of the mouth and anus, — some among theEnchelia, others, asPhiaUna,
among the TracheUa, and others again in the genus Trachelocerca, the type
of his family Ophryocercina. On this plan, Lacrymaria has the body without
cilia, prolonged into a naiTow neck, terminated by an obliquely truncate and
ciliated mouth, at the opposite extremity to which is tlie anus ; Phialina
similar, except that the neck, instead of being tenninated by a simple enlarge-
ment, is notched on one side, and the mouth therefore lateral ; and Trache-
locerca, which he himself cfills " tailed Lacymaria;," have a terminal mouth
and an anus on one side in advance of a conical caudiform prolongation of the
body. These distinctions are not borne out by more critical invosli'mtions
and at mo.st are insufficient to establish generic characters, and still more
those of higlier gi-oups or families. As the result of these considerations
Dujardin has comprehended all the .species distributed in the throe o-^nora
named in one, viz. Lacrymaria, which he places among the Parainecinu

2 R

610

SYSTEMATIC niSTOEY OF THE nTFXTSOTlIA.

The doubt expressed conceming the existence of a mouth as described by
Ehrenberg, has been removed by later observations.

The variabihty of form of which the Lacrymarice are capable was noticed by
Baker and other old observers, and suggested the appellation Proteus, originally
bestowed on them. Perty has made use of this peculiarity to constitute a
section of Ciliated Protozoa, which he has named " Metaboliea." Besides
Lacrymaria, it includes Traclielocerca, these two genera being combined into
a family, " Ophryocercina." His genus Traclielocerca, however, is not equi-
valent to the one so named by Ehrenberg, since it also comprises the species
of Phialina eniunerated by that author. This employment of a recognized
systematic term with a wider signification than that originally given to it,
cannot be commended ; and, as Perty makes no attempt to define the differ-
ential characters between the two genera as understood by himself, we regard
his family Ophryocercina as imsatisfactory. The Phialina; he considere only
young or contracted examples of one or other genus. (See PmAirtiA and
Tkachelocebca.)

Lacbymaeia Pi'oteus {Trichoda Pro-
teus, M.) (xxrv. 274, 275).— Oblong, tm--
gid, with delicate ti-ansverse folds. Colom-
varies from grey to green. The neck is
capable of considerable extension. It
resembles Trachelocerca Olor; but its
posterior extremity is roimded, and has
at its centre the discharging orifice. Re-
productive organs unknown. Amongst
Lemnse. Size stretched out 1-140".

L. Gxdta. — Body smooth and nearly
spherical, with a very long neck. Perty
discovered a tongue-like process above
the mouth in some examples. Among
Confervse. Size 1-1150" j including
neck, 1-210".

L. rugosa. — Neai'ly globular, and
wrinkled ; the neck of medium length ;
granules green. In swimming, it often
revolves on its long axisj neither cilia

nor an enlargement is observable near
the mouth. 1-570"; including neck,
1-288".

L. versatilis (Duj.) (^Trichoda versatUis,
M.). — Fusifonn ; neck reti-actUe, ciliated
beneath, shorter than in L. Proteus, which
it is fui'ther unlike by having the body
pointed posteriorly, and by living in sea-
water.

Pei-ty declares this is not an independ-
ent species, but only the immature form
of Trachelocerca Olor (Ehr.).

L. tornatilis. — Neck reti'actile, some-
times disappearing entii-ely, presenting
then only the cilia crowning its extre-
mity.

L. farcta. — ^Flask-shaped, with a short
neck. In ditch-water about Paris.
1-260".

Genus LEUCOPHEYS (XXIV. 276, 277, 278, 279, 280).— Covered with
vibratile cilia ; mouth obhque, terminal, without teeth. From the obliquity
of the mouth, there is the appearance of an upper hp. Tlie cUia which cover
the body are short and disposed in rows ; those aroimd the mouth are longer,
and produce very powerful cun'ents. In smmming, aU the species revolve
upon the longer axis. A serpentine alimentary canal, with more than fifty
grape-hko stomach-cells (XXIV. 276), terminating at the opposite extremity
to the mouth, is described by Elu-cnberg ; in some, one or two globular nuclei
and a contractile vesicle are seen. Self-division transverse and longitudinal.

LeucopJirys forms, in the system of Dujardin, vrith 82:>athidium and Ojmlina,
the family " Leucophryens," characterized by having " an oval or oblong de-
pressed body, covered with cilia densely but regularly disposed ; mouth not
evident ; foreign solid particles are not to be found in the vacuoles ; hence
probably these animals hve only by absorption. Most of them are parasitic
Avithin Annehda and Batrachia, and soon perish in pm-e water, like Helmin-
thoid (tape) womis." Dujardin says, " It is to the genus Biirsaria that Ehren-
berg has transferred most of the true Leucoplirj-ens, in conjunction with
other Infusoria having a very distinct mouth." (See OpALiNiEA, p. 569.)

Dujardin's characters of LeiicojpJirys are : — " Body depressed, oval or oblong.

Olf THE ENCHELIA.

611

equally rounded at the two ends, covered by long, very numerous, vibratile
cilia, in parallel rows ; no mouth. I," says Dujardin, " have restiicted the
term to animalcules parasitic within Lumbrici, but ought probably to include
the form met -with by Ehrenberg ia the Anoclontce."

This genus requires further examination, and may probably be cancelled
by the transfer of its members to other groups. It is certain that several of
its enumerated species are mouthless, and that some belong to the Opalinaea ;
and Dujardin clearly pui-sued a veiy right course in detaching it from the
heterogeneous class Enchelia, and ia briaging it into relation with Opalina.
Perty has followed a similar plan, and instituted a family of parasitic animal-
cules under the name of Cobalina, comprehending besides Leucophrijs (repre-
sented by only one species, L. striata) Opalina, Plagiotoma, and Alasior.
Like Dujardin, also, he transfers L. patula to Bursana ; treats L. Spathula
as identical with Spathidium hyalinum (Duj.), but places it in a family
Holophryina, along with Holophrya and Enchelys (i. e. as represented by
E. Farcimen and E. Pupa). Neither Ehrenberg's descriptions nor figmres
are sufficient to identify L. sanguinea either with Bursaria or Opalina ; its
colour lends no aid, siuce it is doubtless accidental. L. pyriformis and L.
carnium are doubtful members, and the rest named are petty clearly Opalinaea.
L. carnium is treated by Dujardin as identical with Trichoda carnium.

Leucophbys patula ( Trichoda patula,
M.) (xxrv. 276, 277) {Bursaria patula,
Duj.). — Oval, campanidate, tiu'gid;
sometimes quite pellucid, at others
M'hitish ; mouth ample and gaping ;
vacuoles are very large, and fill them-
selves with food m an in'egulai- maimer.
When (says Ehrenberg) the animalcide
is qxiiet, the passage of the food onwards
is seen in the serpentine canal, to which
the stomachs are attached like berries ;
even the stalk or short commimicating
tube is visible when they receive or dis-
charge colom-ed food. The longitudinal
rows of cilia are very niunerous in full-
grown specimens. The granules are
white by incident light, brownish by
transmitted. In the middle of the body
is a small globidar nucleus. Both in
fresh- and sea-water. 1-280" to 1-96".

L. Spathula {= Enchelys Siiathula,
M.) (xxiv. 278). — Lanceolate, com-
pressed, whitish ; mouth narrow, situated
at its anterior extremity, which is ob-
liquely tnmcated and membrane-like.
Amongst Lemnse. 1-140". Vide Spa-
THiDixrai hyalinum, p. 612.

L. sanyuinca {Trichoda striata, M.)
(xxiv. 279, 280).— Cylindrical, rounded
at both extremities, and of the colour of
blood. Elirenberg remarked within it
two bright contractile romid bladders,
and that on self-division one was present
in each part. 1-144".

\j. pyriformis {Kolpoda Pyrum, M.). —

Ovate, whitish, rather more acute ante-
riorly; vacuoles large. 1-570" to 1-280".

Dujai'din considers that this species
shoidd rightly be transfeiTed to Glaucoma
or Kolpoda.

L. carnium (Kolpoda Pyrum, M.). —
Oval, oblong, acute anteriorly, and of a
whitish colom"; vacuoles narrow. In
putrescent animal water, and the di'ain-
age of manm-e. 1-1440" to 1-430". It
= Trichoda Pyrum (Perty).

Perty suggests that Enchelys nodulosa
is referable also to this species.

L. (?) Anodonta {Leiccophra Jluida,
M.). — Oval, tm-gid, and ti-ansparent ;
roimded at both extremities. In Siberia
and at Copenhagen. 1-430". Most pro-
bably it is an Opalina.

L. striata (Duj.). — Oblong, mai-ked by
thu-ty-five longitudinal granidar strise.
1-325" to 1-200". In the Lumbrici
(worms) of gardens.

This is the only species of Leucophrys
retained by Perty. On the other hand.
Stein (p. 184) asserts that it is an Opa-
lina, a mouthless animalcule, and there-
fore rightly excluded fi-om Enchelia.

L. twdulafa (Duj.). — Oblong, regularly
ciliated ; wthout distinct str'm, buthav-
m<j;t\vo series of vacuoles. In Lumbrici.

The last three supposed species are,
says Stein (Lifus. p. 184), Opalina;, and
the last two should bo imited as one
which may be named 0. Lumbnci. (Seo
family Opalin.t3a, p. 569.)

Genus SPATHIDITJM (Duj.) (XXVI. 27).— Oblong; thicker and
rounded behind; thinner, expanded, and tnmcated in front.

2 It 2

G12

SYSTEMATIC HISTOKY OF THE INFTTSOttlA.

This genus is admitted by Perty, who places it in the family " Holopl
bnt, unlike Dujardin, believes it to possess a mouth.

SPATHiDruM hyalinum (xxvi. 27). —
Oblong, lanceolate, hyaline ; thin and
almost membranous anteriorly, and ter-
minated by an oblique margin, along
which some small black nodules may be
seen. In pond-water, near Paris. The
Enchelys Spathula of Miiller woidd seem
to be the same species; but the Leu-
cophnjs Spathula (Ehr.) differs from it
in having a row of ciUa on the ante-
rior margin, with strife on each side,

and in receiving indigo in its stomach-
sacs.

Pei-ty, however, treats them as identi-
cal. Indeed, the marks of distinction
Dujardin would draw are certainly in-
sullicient to establish a specific differ-
ence ; since the absence or presence of a
row of cilia may readily be unobseiTed,
and the reception or non-reception of
indigo is very much a matter of manipu-
lation.

Genus HOLOPHEYA (XXIV. 281).— Ovoid, oblong, or even cylindi-ical ;
covered with vibratile cilia ; mouth anterior, directly tnmcated or terminal,
and without lip or teeth. In two species the mouth and anus have been seen.
Cilia disposed in longitudinal rows. In H. Ovum green granules and a posterior
contractile vesicle are observable ; self-division appears to be transverse in
H. discolor.

In the system of Perty, Holophrya gives name to a family " Holophr^-ina,"
defined as having " an anterior mouth, a posterior anus, and the surface
covered with cilia in longitudinal rows." It includes the genera HoJoplwya,
some species of Enchelys and Spatliiclium (Duj.), Leucoplirys (E.). The two
species of Enchelys mentioned are E. Farcimen and E. Pujpa ; the Leucophrys
is the L. Spathula (Ehr.).

Holophrya is closely allied to Prorodon ; indeed its independence is very
doubtful ; for the only distinctive character between the two genera put for-
ward is, that the " dental cylinder " is absent in the former ; but this is a
structural peculiarity not always very obvious to the eye, liable to be over-
looked, and of secondary histological importance.

Holophrya and the following genus, Prorodon, are included in Dujardin's
family Parameciaa.

HoLOPHBYA Ovimi (Lmcophra hursata,
M.) (xxrv. 281). — Ovate, somewhat
cylindrical, extremities subti'imcate ;
gramdes green. Amongst LemnEE and
Confei-v£e. 1-570" to 1-210".

H. discolor (^Trichoda horrida, M.). —
"V^Tiite, ovate, conical, subacute at the
posterior extremity ; cilia long and
scattered. Amongst Confeiwos. 1-240".

This species Stein has noticed in
the encysted condition, suiTounded by
a thick-walled cyst. Cohn, moreover,

foimd the previous species, H. Oriim, in
the same condition. Instead of being
white, it is often coloured green by
chlorophyll.

H. Uoieps {Leucophra globuUfera, M.).
— Oblong, cylindrical; rounded at both
exti-emities ; whitish. 1-430" to 1-280".

H. hrumica (Duj.). — Brown, changing
from a cylindrical to a globular form
when filled with food, and also then
altering in colour.

Genus PRORODON (XXIV. 282 ; XXVIII. 8).— Is distinguished by the
directly truncated mouth, and a cii-clct or cylinder of internal teeth. Body
covered with vibratile cilia. Digestive cells, an oral, and an anal outlet have
been demonsti-ated by coloured food. A long band-like nucleus, contractile
sac, and granules are seen in P. niveus.

In the system of Perty, Prorodon constitutes a member of the family
Decteria, in company with Chihdon, Nassula, Uahrodon, and Cyclogramma.
Habrodon is annexed to this present family ; but Cycloyramma will be foimd
placed among the Trachelina, along mth Chilodon and Nasstda.

OF THE ENCHELIA.

613

PnoRODON niveus. — Lar^^e, elliptical,
aud compressed ; coloiu* white ; circlet of
teeth compressed (teste Ehr.), as shown
sepai-ate in xxiv. 283. Smaller examples
have fewer teeth than the lai'ge. Cilia
very fine. It is found encysted. Amongst
Confervse in turf-pools. 1-72". Conn
intimates (Zeifschr. 1853, iv. p. 271) that
this species and the next are merely
vaiieties of the same being.

P. teres (xxiv.282; xxvnt. 8). — Ovate,
cylindrical, white ; cu-clet of teeth cylin-
diical. Ehrenberg counted twenty sup-
posed teeth ; and when the cylinder was
broken, forty-five. Revolves, in swim-
ming, upon the long axis. 1-140". It
has been seen in the encysted state, and

to undergo fission when in that condition.

P. viriclis. — Large, elliptic, compressed,
gi'een, with a neai'ly cylindi-ical crown of
teeth. 1-120". Berlin.

In all probability this gi-een-coloui'ed
organism is a mere variety of the pre-
ceding, from which it offers no distinc-
tive featm'es. In Prorodon, as in Chi-
lodon, fission occurs in encj'sted beings.

P. vorax (Pei-ty). — Hyaline, seldom
green ; dental apparatus faintly marked.
Integument covered with wart-like ele-
vations in rings. Movements tolerably
rapid; oftentimes oscillating. Anus
placed at posterior exti-emity. 1-240"
to 1-84". It chiefly difl'ers from P. niveus
by its faintly-marked dental apparatus.

We have yet to append some genera (whose aflinity is with the foregoing)
described by Dujardin, viz. Acomia, Gastrochceta, Alyscum, and Uronema, —
and which, with the genus Enchelys, constitute his family Enchelyens
(Enchelina).

Acomia and Gastrochceta are only ciliated partially — the former at one
end, the latter along a longitudinal fiuTow on the under surface. Enchelys,
Alyscum, and Uronema are ciliated throughout, — the first having but one
form of cilia ; the second, cilia together with some long, contractile, trailing
filaments ; and the last, ciha with a single, straight and long posterior
filament.

Genus ACOMIA (D.).(XXYI. 16, 17).— Oval or ii-regular, oblong, colour-
less or cloudy, formed of a homogeneous glutinous substance containing
unequal-sized granules, and cUiated at one end. No mouth.

Perty remarks that there is an absence of definite characters between
this genus and the Enchelys (Duj.), and that the species of Acomia requii-e
fiu'ther study.

Acomia CijcUdium (xxvi. 16 a, b). —
Oval, oblong, depressed, containing large
gi-anules and some vacuoles ; transverse
fissiou. In external fonn approaches
Cylidinm (Ehr.). Marine. 1-650".

A. vitrea (xxvi. 17 a, b). — Ovoid, hya-
line, but rendered cloudy by granules in
its posterior half; anteriorborderciliated;
division longitudinal. 1-1250". In fetid
water.

A. ovalis. — Difl'ers from tlic preceding
by the granidos occupying the anterior
half, and by its lengtli, 1-808". In fetid
marsh-water.

The difteronco in position of the gra-
nules is valueless n.s a .speciKc distinction
between this and the previous species,
and should bo rojocted.

A. Ovidum. — Ovoid, presenting a no-
dular or granular portion, wliicli .sponis
to conlrnct itself within Mu; interior
of a (liai)lianous envelope. I {.evolves in
moving, like a Doxocorrns. I -.'500".

ytein (Lifus. p. 1:!7) declare.'s that

it is undistinguishable from Cyclidium
Glaucoma (Ehr.).

A. (?) Vorticella.—Ovo\^, nearly glo-
bular, colom-less, cloudy; ciliated "in its
anterior half; cilia curved backwards.
Revolves on its axis in progressing for-
wards. 1-1000". In sea-water.

A. (?) costata. — Ovoid-oblong, nar-
rower in front ; apparently enclosed by a
tliiclf membrane, or consistent layer;
nodular ; nodules often arranged in rows
as ribs. Division transverse. 1-G50" to
1-500". In sea-water, among jMo-s;.

A. varians. — Oblong, cylindrical ;
truncated and angular in front ; dilated
and compressed, by tiu-ns, in dilierent
parts of its length, and consequently
alternately rounded and constricted be-
hind, so a.sto terminate bv a pointed tail.
Revolves on its axis. 1-1000" to 1-460".

A. injlatn.—0\a\, tapering antcriovlv.
beset everywhere witli vei-y fine cilia-
colourless, or occupied with' green, gi-oy'
or brown granides. Movement rapid'

614

SYSTEMATIC HISXOEY 03? THE INFUSOBIA.

revolvinpf. Cilia often appear longer in
front. Found by Dujardin and Perty in
decomposing marsli-water.

A. cava (Perty). — Oval, slightly irre-

gular; convex above, flat beneath, or
rather concave. Thickly ciliated all
over. 1-G70". Amongst Lemnaj.

Genus HABEODON (Perty). — Body subcylindrical, rather bent ; thickened
posteriorly, and mostly tmncate in front. Mouth anterior, with a very deli-
cate dental apparatus. Anus posterior. Cilia in longitudinal rows.

This genus, created by Perty, is placed by him in juxtaposition with Pro-
rodon, with which and Chilodon, Nassula, and a new genus, Cydograrnma,
it constitutes a fanuly called Decteria.

Habbodon mrvatus = Enchelys Pupa
(?) (Miill.). — Colom* usually grey or pale
gTeen, vdth numeroiis molecules and
vesicles ; anteriorly it is hyaline, and

posteriorly it presents a round clear
space (an anxisP). Movements slow.
1-390" to 1-132". In springs, with
CJiara, &c., Bern.

Genus ACROPISTHIUM (Perty) (XXYni. 61).
rior flap, or roimded oflf ; pointed behind.

-Circular, with an ante-

AcROPiSTHiuM miitahile. — Hyaline,
with darker vesicles and molecules.
Movements very rapid, revolving. Cilia
cover the entire smi'ace, very fine, usually

more perceptible anteriorly. The figure
varies much. Mouth in front (?). 1-360"
to 1-320". Uncommon.

Genus B^ONIDITJM (Perty) (XXYIII. 52-54).— SmaU, subcylindrical;
cilia at anterior end large ; movement sluggish.

B^ONinruM remigans. — Usually pris-
matic and roimded; often rather
wi'inkled; hyaline, but nearly always
filled with green corpuscles. Cilia
generally distributed ; the large anterior
ones simulate pedal organs in their

movement. A slight depression some-
times perceptible on one side, in the
position of the mouth. Fission trans-
verse. 1-840" to 1-660"
Charge, but rare, in Switzerland

Amongst

Genus OPISTHIOTRICHA (Party) (XXYIII. 55-57).— Small, elongated-
cylindrical or pyriform ; cilia distributed over the body, veiy fine, some of
those on the posterior extremity lai'ge, ciliary action sluggish.

Opisthiothicha temm (xx'^Tit. 55-
57). — Colom-less or slightly green, with
delicate vesicles and molecules in the
interior. Swims very rapidlj^, revolv-
ing at the same time on its long axis.

Large posterior cilia from two to three
in young specimens, five to six in old.
1-900" to 1-440". In marsh- or bog-
water. Bern, &c.

Genus SIAGONTHERIUM (Perty) (XXYIII. 62, 63).— Yery smaU, ex-
tended anteriorly, thickened posteriorly ; with a long stiff biistle extended
backwards on one side of the anterior extremity.

delicate, with internal molecules and
vesicles. Scarce in pools, licrn, with
Hysi/hmm ^iluviak'. 1-900" to 1-760".

SiAGONTHEBTCM tctiue. — Seen .on the
wider side, elongated ovate; anterior
prolongation directed forwards from the
smaller subcylindrical half. Extremely

Genus MEGATRICHA (Perty) (XXYIII. 58-60).— Yciy smaU, clothed
with long, scattered and slowly-moving cilia. Body cntii-c, or divided incom-
pletely into two unequal portions. " These are the most deKcate and simple
of aU the Ciliata."

this species. 1-1440". Un-

MEGATniciiA intcjfra. — Undivided,
colourless, with long, delicate cilia.
Very possibly Ch<rAomonas Ghhulus be-

longs to
common.

M. partita (xx^^II. 68-GO).-

-Dividcd

OF THE ENCnELIA,

616

into a smaller, rather pointed, anterior
section, and a wider posterior one ; co-
lourless. Extremely delicate; often
composed, like many Monads, of only
five molecides. Movements of cilia

slugg-isli. Swimming often interrupted
suddenly by a jerk in another direction.
Fission longitudinal. 1-1560" to 1-1320".
Rai'e, among decomposing Oonfervse.

Genus PTYXIDIUM (Perty) (XXYIII. 40-42).
with several folds. Cilia equal, very flue.

-Ovate, pointed ia front.

Ptyxidium Ovulum = Leucophrys pyri-
formis (Ehr.). Kolpoda Pyrum (Miill.),
which Ehi'enberg cites as synonymous,

is more probably an Acomia. Perty dis-
covered no food in the interior.

Genus COLOBIDIUM (Perty) (XXVIII. 45).— When mature, ovate ; in
earlier condition, truncate posteriorly — frequently emarginate, — rounded an-
teriorly. Cilia ia longitudinal rows, those iu front longer ; their movements
slow.

Qo'LOBJDTXm.pelluciclum. — ^Very trans-
parent, colourless or clear gi'een ; move-
ments rapid, always rotating. " The
longer cilia in fifont often moved in a

foot-like manner." 1-1900" to 1-600".
In tm-f-hollows among Confei'vae. Bern.
Acomia Vorticella (Duj.) is probably only
a variety of this species.

Genus APIONIDIUM (Perty) (XXVIII. 48, 49).— Bounded ; thicker in
front than behind ; rows of cUia few in number.

Apionidium modestum. — Hyaline,
with colom'ed (green or brown) food-par-
ticles. Rows of cilia from seven to nine ;

cilia very fine. A round clear space
usually visible posteriorly. Rare. 1-260"
to 1-240".

Genus GASTROCH^TA (Duj.) (XXYI. 18).— Body oval, convex on one
side, and hoUowed by a longitudinal furrow on the other ; cUia seated in the
furrow, chiefly at the two ends.

Gastboch^ta Jissa (xxvi. 18). — Semitransparent, oval, truncate ia front.
1-408". In the water of the Seine.

Genus ALYSCUM (Duj.) (XXVI. 20). — Body ovoid-oblong ii-regular,
surrounded by radiating cUia, and having, besides, a lateral bundle of Ion"'
retractile cUia, by means of which it leaps briskly from place to place.

The single species much resembles Enclielys nodulosa {Paramecmm Milium
or PantotricJmm Enchelys, Ehr.) from wliich it is distiagiiished by its retractile
filaments.

Alyscum srt?<aH-s (xxvi. 20). — Colour- almost in^nisible longitudinal fuiTows.
less, obloiig, rounded at the ends, rather 1-1300" to 1130". In infusions and iri
concave along the side bearing the re- the Seine,
tractile filaments, and marked by some

Genus UROKEMA (Duj.) (XXVI. 25).— Body long, narrower in front,
rather ciuT^ed; surrounded by radiatiag cilia, and beariug a long straight
ciUixm behind. °

UnoNEMA marina (xxvi. 25). — Co-
lourless, semi-transparent, nodular, elon-
gated; contracted in front; slightly
curved, with from four to five slightly-
marked longitudinal striae. 1-595". In
the MediteiTanean.

Stein considers this form, as in the
instance of Cyclidium Glaucoma, to be
merely an embryo of an Infusorium, and
not an independent species.

016

SYSTEMATIC HISTORY OF THE INFUSORIA.

FAMILY VI.— COLEPINA.
(XXIV. 284, 285).

Loricatecl animalcules having the mouth and anus placed at the opposite
extremities of the body. The lorica is of the form of a small cask, composed
either of minute plates placed in a row, or of little rings between which
cUia are situated ; anteiiorly it is truncated, smooth or toothed, and poste-
riorly terminated by three to live little points ; mouth cihated. The diges-
tive vacuoles in these creatures are readily filled with coloui-ed food, which is
ejected posteriorly. Complete transverse self-division has been observed.
A distinguishing character of the Ciliated Protozoa is their asymmetrical
figure ; but the genus Coleps is an exception to the general rule.

In the act of fission a new formation of tissue appears to take place along
the future line of separation, thinner and softer in consistence than the
original covering.

Genus COLEPS (XXIV. 284-286).
racteristics are identical with those of

Coleps hirtus (^Cercaria hirta, M.)
(XXIV. 284-286).— Body white, oval, with
trmicated ends; lorica apparently com-
posed of small polygonal plates, between
which the cilia are both transversely
and longitudinally arranged. Anteriorly
there are nineteen pointed processes, and
posteriorly three. Movements very brisk ;
so that it IS difficult to examine the lorica
while the animal is living ; but when it
is dried, or pressed between glasses, the
complex structure of the former is
rendered visible. Amongst Confervee.
1-570" to 1-430." _

Although described by Ehrenberg as
colom-less or white, this is no specific
character ; for it may frequently be co-
loured green by chlorophyll, or tinted
with intermediate shades between yel-
low, gi'een, and brown, according to the
food taken and its changes by digestion.

C. viridis. — Green, oval, and ciliated;
lorica terminating in three points.
Amongst Confervte. 1-960" to 1-570".

Except in the matter of colom*, no
distinction fi'om the preceding is noted ;
its specific independence may therefore
be fairly questioned.

— This being the only genus, its cha-
its family,

C. elongatus. — Cylindi'ical, elongated;
lorica white, and terminating in three
points ; self-division transverse. 1-570"
to 1-430".

Between this form and C. hirtus Perty
has seen every intermediate figiure, and
therefore regards it as a mere vaiietj-,
and not a species. The colom-, it hai'dly
needs be stated, is in no way chai-acter-
istic.

C. amphacanthm. — Ovate, shorter. Lo-
rica, unlike that of the other species, com-
posed of rings ; the anterior part crowned
with unequal teeth, the posterior having
three sti'ong spines. Found in Spiro-
stomuvi virens. 1-280".

C. incurvus. — Oblong, nearly cjdiu-
diical, and slightly cm'ved; lorica ter-
minating in five points. Amongst Cou-
fei-vfe. 1-430".

C. inennis (Perty). — Lorica costate,
not granidar ; no spinous points at pos-
terior end, or very feeble ones. Green
coi-puscles occm- internally. The dis-
tinctness of the ribs varies, as well as the
length and thickness of the body. Mo-
tions like those of C. hirttts. 1-GOO".
Fresh water.

FAMILY VII.— TRxVCHELINA.

(XXIV., XXVIIL, XXIX.)

This extensive family includes those animalcules which have two distinct
alimentary orifices- the receiving one lateral, the dischai-ging one terminal.
Tljoy have no lorica ; but all the genera, except Phialina, are covered with
vibrating cilia, generally disposed in longitudinal rows, those near the
mouth being the longest. TraclieUus has no neck ; but the frontal portion of
the body is prolonged in the form of a long trunk-like Hp; in Lo.x-odc^ and.
Chilodon it is like a luitchct-shapcd broad lip. In Glaucoma there is a

OF Tin: TKACHELINA.

617

tremulous flap to the mouth, iind in Chilodon and Nassula a cylinder oi rod-
like teeth, which sometimes projects in advance of the mouth. Bursaria and
Nassala have a thick frontal protuberance. The reception and discharge of
coloured matter can be seen in all the genera. In Nassula the violet-coloured
specks (bile) are worthy of notice. In Spirostomum the mouth is spiral. A
nucleus and one or more contractile vesicles occur in. aU. the genera. Com-
plete transverse and longitudinal self-division is frequent and complete.

The genera ai'e disposed as follows : —

(

No trernu

lous

, mouth-
's n

_a flap.

Brow con-
tinuoua
with the ''
body.

with a C lip long, proboscis-like Trachelius.

brow-hie ■

upper lip [ lip broad, hatchet-shaped. . .Loxodes.

^brow-Uke prominent back Bursaria.

^Mouth spiral Spirostomum.

^Brow interrupted iu a peg-like manner Phialiiia.

( Mouth having a tremulous flap Glaucoma.

.a "a r A brow-like prominent upper lip Chilodon.

"S m ■!

H ^ [ A brow-like prominent back Nassula.

This family is not recognized by Dujardin, who rejects the supposed affini-
ties of its genera as unnatural ; and indeed it must be owned that the Tra-
cheUna, as understood by Ehrenberg, represent a heterogeneous collection
rather than a natural group. Bursaria includes some mouthless Opalince.
Spirostomum evidently takes its place next to Stentor ; and Chilodon and
Nassula are removed in several important details of organization from Tra-
chelius and Phialina.

Perty retains in his classification a family Traclielina, and places in it the
genera Trachelius, Harmodirus,Amphileptus, Loxophyllum, Dileptus, Pelecida,
and Loxodes, — adopting, however, the characters assigned by Dujardin in
preference to those given by Ehrenberg. The brief character of Trachelina
recorded is — " Body elongated anteriorly into a neck-like process, or pro-
truding a proboscis curved on one side."

We have retained in the preceding description of TracheHna, adopted from
Ehrenberg, several notes of structui-al peculiarities which subsequent re-
searches show to be erroneous. That the mouth is lateral and the anus ter-
minal ia aU the members of the family is not the case. Thus, in Cfiilodon the
discharging oiifice is on one side, near the posterior extremity. Lachmann
(A. N. H. 1857, xix. p. 216) speaks of the buccal orifice of Glaucoma as
produced into two flaps. The teeth (so called) in Nassida, Chilodon, &c.
have no real claim to that designation ; for they are no more than folds or
thickenings of the oesophagus (see Part I. p. 311). The violet- coloiu-cd spots,
imagined by Ehrenberg to be vesicles, are merely accidental specks of colour
derived from the food (sec p. 312, and notes on Nassula elcgam).

Chilodon and Nassula have been proved to propagate by living embryos
after a pre\-ious cncysting-stago ; and in all probability most of the other
genera do so likewise. Nassula ambi;/iia (Stein) has been seen in the same
encysted condition as Chilodon ; and only the last stage, that of the intern-il
development of a ciliated embryo, to complete the cycle as in Chilodon has
escaped observation. '

618

SYSTEMATIC HISTOEY OF THE INFUSOHIA.

Genus TEACHELIUS (XXIV. 287-290).— Body ciliated ; mouth simple,
destitute of teeth, is seated on one side at the base of the very much elon-
gated upper lip or proboscis. Ciha are absent in three species. In four
species coloured food has been received, and in three the discharging orifice
detected. It has also a coUapsed oesophagus, visible only during the pas.sago
of food. Two species increase by transverse self-division.

This genus forms a member of the family "Trichodiens" (Trichodina)
(Duj.), along with Trichoda and genera named Acineria, Pelecida, and
Dilejotus.

The account he gives of the animals differs much from the foregoing. Ac-
cording to it, Trachelius is destitute of a contractile or reticulated integu-
ment, and is composed of a muco-gelatinous substance (sarcode) containing
granules, which are oftentimes agglomerated in the form of nodules, disposed
ia rows. The ajjparent oviposition ia T. Ovum and T. Meleagris was nothing
more than the breaking up of part of the animalcule by " diffluence," and
the supposed ova only particles of " sarcode."

" The cilia at the anterior extremity are larger than those on the rest
of the body. Posteriorly a large vacuole is often to be seen. There is no
distinct mouth."

The last statement is contradicted by recent investigations, which prove
that the animalcules belonging to this family have a mouth, and some of
them, at least, an anus.

Tbachelius Anas (^Trichoda Anas et
Index, M.)(xxiv. 287-289).— White, cla-
vate, and cylindrical; proboscis thick,
obtuse, not half the length of body;
mouth situated close to the base of the
proboscis. In exposed infusions, and
freshwater swamps, amongst Confei-vse.
The interior often contains green (chlo-
rophyll) vesicles. 1-280" to 1-120".

T. vorax. — Clavate-ovate, tm'gid, co-
loiu' white; proboscis thick, obtuse,
shorter than half the body ; mouth situ-
ated near the middle of the body, and
not at the base of the proboscis. Amongst
Confei-v£e. 1-120".

T. Meleagris. — Compressed, lanceolate,
often curved in the form of the letter S ;
proboscis thick, obtuse, shoiter than half
the body. 1-96" to 1-60".

Ehrenberg described in this species a
red-colom'ed fluid which he called bUe,
and a row of ten to twelve vesicles along
the back, which he concluded to be sto-
mach-cells filled with red gastric juice. It
is now, however, admitted that these cells
are really conti'actlle, and fonn a vasculai'
chain. The nucleus is oval, witli a cen-
tral constriction. Dujardin adopted this
species as one fonn" of a new genus,
Ijoxophyllmn, hereafter described in the
family Colpodoa.

T. Lamella {Kolpoda lamella, M.)
(xxvi. 24 fl^ b). — Depressed, laminar,
elongated, linear-lanceolate, often tnm-
cated anteriorly and rounded ; margin
ciliated (Dujardin says, only in front).

Ehrenberg considers this form may be no
other than the young condition of A)n-
phileptus Fasciola ; and Perty would add,
of Spathidium hrjalimim. In sea-water.
1-900" to 1-200".

T, Anaticula. — White, small, ovate,
pyrifoim, attenuated and diaphanous an-
teriorly. Dujardm believes he has seen
several of these animalcules become by
simple contact agglutinated together, —
a circumstance which would indicate the
absence of a ti'ue integument. Amongst
Confervfe. 1-570" to 1-280".

T. (?) trichophorus ( Vibrio strictiis, M.)
— Cylindi'ical, changeable, often clavate ;

Sroboscis capitate, of the form of a very
elicate whip. 1-1200" to 1-430".
T. (?) globulifer. — Spherical, hyaline,
with a very delicate whip-like acute pro-
boscis. Ainongst Confervaj. 1-200".

T. Ovum (xxrv. 290). — Lai'ge, ovate,
wide or campanulate anteriorly; pro-
boscis short, in the form of a be.ok ; con-
tractile vesicles numerous. " In no in-
fusorial animalcule," says Ehrenberg, " is
the alimentary canal so easily seen as in
this ; the large mouth and contractile
vesicle, lying over the lower part of the
alimentary canal, are equallv evident;
numerous small digestive cells and ova-
gi'aniUes appeal' in everj- part." It is in
this species that Lieberkiihn and Lach-
mann have latterly described the exist-
ence of an ai'borescent, ramified digestive
canal, quite distinct from (he clear round
spaces in the parenchyma of tlie body,

OF THE TEACHELINA.

619

wliich some have supposed to he sto-
machs. In stagnant bog-water. 1-72."
It has been foimd encysted. (Vide Part I.
p. 309).

T. (?) laticeps. — Flattened, eUiptical;
anterior part (head) membranous, vai'i-
able and wide, with a notch from which
proceeds a flagelliform proboscis almost
double the length of the body. 1-912".
In North Sea.

T. dendrophilus. — Ovate, subacute at
each end; proboscis very fine, acute,
double the leng-th of the body. 1-288"' ;
with filament, 1-96'" to 1-72"'. Has the
habit of a Monad, but the motion of T.
trichophorus, than which it is very much
smaller. On tree-mosses.

T. strictus (Duj.). — Filiform, extremi-
ties rather pointed; the cilia visible
onlyinfr'ont. 1-400". Amongst Lemnte ;
seen also by Perty in Switzerland.

T. teres. — Filiform, cylindi'ical, obtuse
anteriorly, pointed and tapering behind ;
ciliated only in the anterior margin.
1-170". In stagnant sea-water.

T. Falx. — Long, depressed, lanceolate

or sigmoid ; variable ; narrower and
rather curved anteriorly in a sickle-like
form; cUiated generally, 1-420". In
pond-water.

T. noduliferus (Perty). — Very slender,
naiTOwed anteriorly, but terminated
abruptly by a rounded end; colomless,
but with difiused chlorophyll- vesicles at
times, and gi-anules. Cilia scarcely vi-
sible, except near the head, where they
are rather larger. Movements slow. The
elongated neck-like portion devoid of
molecules. 1-570" to 1-120" (Bern).

T. apiculatus. — Slender, tapering an-
teriorly, its end being obtuse. Colour-
less, with diffused vesicles and molecules.
Cilia very delicate. Movements rapid,
like those of Traclielocerca. 1-144".

T. pusillus. — Considerably elongated;
rather flattened; colomless; with a round
opening at its naiTower anterior ex-
tremity. Movements tolerably quick,
with slow revolutions on its axis.

Perty intimates it to be the same
species as TracJielius trichophorus (Ehr.)
and the Peranema protractum (Duj.).

Genus LOXODES (XXIV. 291-293).— Body ciHated throughout, mouth
simple, devoid of teeth ; upper lip continuous and broad, hatchet-shaped ;
locomotive cilia longer near the mouth. The contractile vesicle is round ;
the nucleus oval or ovoid. In L. Bursaria an oval nucleus and two contrac-
tile globular vesicles have been seen. Self-division transverse.

Dujardin's characters of Loxodes axe — " Body fiat, membranous, or with an
apparently membranous lorica, flexible but not contractile, expanded at the
centre of its superior or dorsal sm-face, often concave on the under siu-face ;
contour iiTegularly oval, sinuous and obliquely prolonged anteriorly ; fiumished
with very fine cilia, confined to its anterior margin. In general characters "
he adds, " Loxodes approaches nearest to Trachelius (family Trichodina) ; but
the signs of an integument are so clear as to sever it from that genus and
family." The Loxodes described by the French author are almost all of them
distributed by Ehrenberg among other genera and families ; and hence there
is unfortimately none but the slightest relation between the similarly-named
genus of the two writers. Thus the Loxodes Rostrum of Ehrenbero- is the
representative of a genus Pelecida, of the family Trichodina, in the system of
Dujardin, and bears the name of Pelecida liostrum. In this position it is
brought into close relation with the genera Trichoda and Trachelius (Ehr.)
and with two others, named by Dujardin Acineria and Dileptus. ' '

The last-mentioned genus comprises Infusoria placed by Ehrenberg with
Amphileptus, in describing which we shall take the opportunity to give the
characters of Dileptus, whilst Acineria and Pelecida will be included among
the appended genera at the end of the present family, TrachcUna,

Loxodes Bostrum (Kolpoda Rostnim,
M., Pelecida Rostrum, D.) (xxrv. 291-
203). — Body compressed, white, lanceo-
late, slightly curved in the form of an S,
in consoquenco of the lip being a little
unciuated. Ehrenberg states that ho has

very often seen large Naviculfp. and Sipi-
edres withm this creature, although it
would not feed on coloured food. The
ciha are very delicate, (xxiv. 291 an
animalcule which has fed upon Bacil-
lana ; xxiv. 292, another, creeping along

620

SYSTEMATIC HISTOKY OF THE INFUbOKIA.

Confervffi ; and xxv. 293, a specimen
imdorgoiiig- transverse self-division.)
Aaiiongst Conferva}. 1-144" to 1-36".

L. Oithara (Trichoda aurantia, M.). —
Triangular and compressed ; anteriorly
dilated and obliquely truncated, but
pointed at the posterior exti-emity. Co-
\om white. 1-430" to 1-210".

1j. Bursaria. — Oblong; anteriorly ob-
liquely ti'uucated and depressed ; poste-
riorly hemispherical. The mouth is placed
near the centre of the ventral surface, at
the bottom of a deep funnel-like fossa
(vestibidvmi), the upper border of which
is longer, broader, rather concave, and
truncate, and constitutes the "upper
lip" of Ehrenberg. A long oesophagus
extends far mto the interior from the
mouth. In bogs. 1-280".

This, Focke and Stein show, is not a
species of Loxocles, but of Paramecium,
and therefore rightly named P. Bursaria
(which see, p. 635). It was this species
which was so elaborately examined by
Cohn, especially vnth regard to its repro-
duction. Yoimg specimens are coloiuless;
but matiu-e beings have numerous chlo-
rophyll-coi'puscles diffused in their cor-
tical laminte. There are two round con-
tractile spaces, which by pressiu-e assume
a stellate appearance similar to those of
P. Aurelia. The rotation of the contents
may be demonstrated in this species ; and
Cohn, Focke, and Stein have witnessed
its reproduction by a living germ or em-
bryo. In figure it is verj' like Chilodon
Cucidhdus, but has the oral fossa (vesti-
bule) and cilia of Paramecium.

L. ;9/icrt<«M. — Elliptical, depressed,
convex on the back, and sliglitly plicated ;
the lip imcinate. On Confervae. 1-430".

The species of Loxodes mentioned by
Dujardin are L. CucuUulus = Cldlodon
Cucullus (Ehr.) ; and L. Cucullio = (?)
Kolpoda Cucullio (M.), placed by Ehren-
berg among the Kolpodea.

L. reticulatiis. — Oval ; more slender,
sinuous, and flexible anteriorly; surface
granular. In long-kept marsh-water.

This species is, in Stein's opinion, a
mere accidental variety of CJiilodonCucul-
lidus, determined by the bulk of food
received.

L. jnannus. — Depressed, oval, almost
renifoim; with internal fine gi'anides,
and a row of puncta near both the ante-
rior and posterior margins. 1-350". Li
salt water.

L. detitatus. — Similar to L. CucuUidujs,
but having a bimdle of bristles about the
mouth, as in Cliilodon, from which it
differs by the lorica (cuirass) and by the
absence of cilia on the surface.

The distinction of this species and L.
Cucullidus as independent. Stein rightly
criticizes as an eiTor on the part of Du-
jardin, and shows(J«/iM. p. 131)thatboth
of them are only accidental varieties of
Cliilodon CucuUulus, — Loxodes CucuUulus
being nothing more than small specimens
in which the esophagus is indistict, and
L. dentatus examples in which this organ
is very evident.

L. breris (Perty). — Short, rounded,
with a hyaline proboscis. 1-500". Bern,
in rainwater-ponds.

Genus BURSARrA (XXIV. 294-296).— Surface ciUated thi'oughout ; an-
terior part convex ; mouth not terminal, fringed ■nath stronger cilia, tliough
simple, toothless, and devoid of tremulous flap. The cilia are distinctly seen
in coloured water, and arc generally disposed in rows ; those aroimd the
mouth are longer than the others. Tlie nutritive system (says Elii'enbcrg)
consists of an alimentary canal, curved forwards ; it is fui-nished with diges-
tive cells resembling little purses, which are attached to it by short stalks.
The mouth is large, situated, as in Lcucophrys, obliquely at the anterior ex-
tremity, so that a brow, as it were, either projects over it or else forms the
end. The contractile vesicle is sometimes doubled ; the nucleus oval or
ovoid. The anus is placed at the posterior extremity. Self-division, longi-
tudinal or transverse, has been observed in five species.

Dujardin has the following remaxks on this genus : — " Ehrenberg, whilst
admitting a genus Bursaria, separates from it several true species, and
places some of them in his gonus Lcucophrys, others in his family Koljiodca ;
whilst the closely allied genera Kondijlostoma and riayiotoma are confounded
with other families — the former with O.vi/trlcJia, the latter witii ParamffluDi.
Moreover, the obliquity of the mouth in Bursaria is not a sufficient distinc-
tion between that genus and Lcucophnjs : and, whilst assigning a large mouth

OF THE TTlACnELINA.

621

to the Bursarice, he includes among them several species in winch the
existence of a mouth is, to say the least, doubtfu]."

The genus Bursaria is taken as the representative of a distinct family, both
by Dujardin and by Pcrty. The former, who names it " Bursaiina," insti-
tutes five genera, viz. Flmjiotoma, Ophryoglena, Bursaria, Spirostomxim, and
Condylostoma. The latter adopts the same name, and ranges the family in
his s(3ction Monima, comprehending Ciliata which, although very contrac-
tile, and clothed by a soft integument, always retain their form. The genera
included among the Bursarina by Perty are Lembadion and Bursaria, — the
former a new genus established by himself to receive two species which he
does not find indicated by Ehrenberg. Dujardin defines the Bursarina as
" animals possessing a highly contractile body, very vaiiable in form, mostly
oval, ovoid, or oblong ; ciliated throughout, and ha^dng a large mouth sur-
mounted by a band or sm-rounded by a spirally cmwed row of cilia."

The genus Bursaria is closely allied to Paramecium, from which it is
chiefly distinguished by the row of larger, longer cilia about the mouth, ex-
tending along the deep fossa in which that oiifice is contained. In Para-
mecium the cilia are everywhere of the same size.

Several of the Bursarioi enumerated by Ehrenberg have been shown to be
Opalince, and to be destitute of a mouth. These species are B. Ranarum,
B. Entozoon, B. intestinalis, and B. Nucleus, all which are fiu'ther remarkable
in being parasitic in Batrachia. The B. cordiformis is also a parasite of the
intestine of the frog, and, although a doubtful member of the genus, has the
sanction of Stein to the generic position accorded it.

a. Sub-genus Bttesakia. — The inferior (not anterior) lip reaching to the

frontal margin.

BuHSARiA truncatella (M.). The trun-
cated Bursaria. — Lai'ge, visible to the
naked eye ; white, ovate, tm'gid, trun-
cated and broadly excavated in fi'ont,
where there is a simple row of cUia. In
some specimens, Ehrenberg saw half-di-
gested Eotifera and large quantities of
vegetable matter in the nutritive cells,
and was able, as he thought, hy means of
caiToine given as food, to ti-ace an ali-
mentary canal through the gi'eater part
of its com'se. In each vacuole the tood
appears suiToimded by a clear fluid, which
Ehrenberg calls bile. A large bright
vesicle is seen below the mouth and
somewhat to the left of it, on which side
is also a large curved but not articidated
nucleus, reaching to the brow or frontal
region. In ditches and ponds, amongst
rotten beech-leaves. 1-48" to 1-3G".

B. Vorticella (xxiv. 294). —White;
large, nearly spherical, and turgid ; an-
teriorly truncated and widely excavated,
with a double row of cilia. Found with
CJikimi/domonas Pulvisculus and Gonium
pectorale, which are sometimes seen
within it, aa in xxiv. 294. 1-108".

B. vorax. — Large, oblonf?, rounded at
the ends ; mouth ample, being one-third
the length of the body, and toiiching the
summit of the frontal region. This spe-

cies has gi-eat resemblance to Urostyla
grandis and Stylojiychia lanceolata, when
their claws and styles are withdrawn.
In muddy water in summer. 1-140" to
1-108".

B. (Ojmlina) Entozoon. — Large, cylin-
drical, turgid, nearly equally rounded at
both extremities ; mouth small, near the
frontal apex. Foimd, with the following,
in the rectum of Rana tcmporaria (the
Frog), in summer and winter.

Perty represents this as a mere variety
of B. Ranarum. He also ti-eats B. Nucl-em
and probably B. intestinalis as other \a-
rieties of the same being, and therefore
Opalina:.

B. (Opalina?) intestinalis (Vibrio Ver-
miculus, M.).— Slender, cylindrical, at-
tenuated posterioriy ; moiitli small, situ-
ated below the frontal apex. In this
species, as well as in others, Ehrenboro-
has seen transverse self-division. Found
with the preceding. 1-240" to 1-120".
It is probably an Opalina.

B. (?) cordiformi.'i. — llcmfonn, front
depressed, mouth slightly curved in a
spiral maimer; colour white. 1-210"

This species Stein aflirms to be a true
Bursaria ; but Perty makes it an Opa-
lina,—a view countenanced by its para-
.sitic nature. *

622

SYSTEMATIC IHSTOBT OF THE IXFUSOEIA.

B. lateintia (Tfichoda ignita, M.). —
Compressed, ovato-triangular, with the
front sharply crested, of a brick-red

b. rEONTONiA. — Anterior part of the

and is

B. vernalis (Leucoph-a m7'cscetis,M.). —
Oval, tiu-gid, rounded at the ends, and
attenuated posteriorly. The mouth has
a wi'sath of stilf^ short bristles, resembling-
teeth ; niunerous digestive vacuoles ai-e
often filled with lai'ge Oscillatorife, Na-
viciUoe, &c. (and contain a reddish bile,
Ehr.). The progressive digestion of the
OsciUatorias is interesting to follow : —
they are at first elastic and rigid, and of
a beautiful blue-green colour", then di-
stinctly lax, flexible, and bright gi-een,
becoming aftei-wai'ds yellowish green,
and resolved into separate segments,
which at length turn yellow. Amongst
Oscillatorite in spring. 1-144" to 1-120".

B. Icucas (xxrv. 295 ; xxx. 1). — Ob-
long, cylindrical; extremities nearly equi-
convex (bile colomless). This creatm-e
has a contractile bladder, with a cmious
lagged margin near- the long open mouth.
With Oscillatoriee, and on the sm-face of
water. 1-144".

B. Pupa (xxiv. 296). — ^White, ovate-
oblong, rather acute posteriorly ; mouth
inferior, and near the fi-ontal apex (see
f 296). 1-280". In chalybeate water,
Germany.

B. yiava. — Ovate-oblong, often acute
at the posterior exti-emity; the mouth
occm-s in the flat concavity immediately
behind the round brow. In bog-water.
1-140" to 1-96".

" This species," says Perty, " difiers
much, both in its flgure and its narrower
oral fissure, from true Bitrsarice, and
ranges better with Panophrys." Dujar-
din, again, considers B. Jtava, B. leucas,
and B. vernalis to be merely three va-
rieties of his Panophrys farcta.

B. (Opalina) Nucleus. — Small, white,
ovate, attenuated anteriorlj"^; exti-emities
convex. In Pana temporaria and R. es-
culenta. 1-240". Vide notes on B. En-
tozoon.

B. (^Opalina) Panarum. — Ovate-lenti-
cular and compressed, subacute ante-
riorly; thebacic and bellycarinated ; often
truncated posteriorly; mouth inferior,
near the frontal apex. 1-210" to 1-72".

The mouth here described has been

hocly (brow) projects heijond the mouth,
convex.

diligently sought for by Stein and others;
but they can find nothmg more than a
fold of the surface, with no orifice in it,
as shown by reagents. This species is
therefore a member of the mouthless
group Opalinsea (vide subclass Opali-
N^A, p. 269, and Pis. xxn. 46, 47 ; xxvi.
28, 29^.

B. (?) aurantiaea. — Ovate-oblong, an-
teriorly obtuse, posterior^ acute ; it has
an ash-colom-ed spot near the mouth.
Amongst OsciUatoriae. 1-280".

B. arborum. — Oblong, compressed;
very finely ciliated; endsroimded; mouth
situated in the anterior third of the body,
reaching its frontal exti'emity; a wreath
of larger cilia extending ai'ound and
backwards from the mouth. Length
1-40"', double the breadth; vacuoles
numerous, and two globulai' nuclei seen.
On moss of trees.

B. triquetra. — Ovate-lenticular; very
finely ciliated ; dorsum flat; venter tm-gid
and slightly keeled, hence an imperfect
triquetral figui'e of the animal ; anterior
exti'emity subtruncate ; oral fissm-e long,
extending from the fi'ontal end, filno;ed
with a row of strong cilia extending
backwards; nuclei two, smaU; vesicle
lai'ge, contractile, simple, near the pos-
terior extremity. Swims slowly. 1-36"'.
On moss of ti'ees.

B. Blattarum (Stein). — Is very like
B. cordiformis, but more compressed;
rounded in fi'ont, where there is a very
opaque, shai-ply-defined, coarse-granular,
and posterior to it the ti-ansverse oval
nucleus. In intestine of Blatta.

B. patula (Duj. and Pert^')=ie(/co-
phrys jjatula (Ehr.) ; Bitrsaria vircns
(Pertj') = Spirostomum virens (Ehr.) ;
and Bitrsaria spingera,

B. Loxodes {Vei'ty) = Loxode^ Bursaria
(Ehr.). — Under no circumstances can
this species (says Pei-tA') be reckoned with
Loxodes (Ehr.), or witli Pclccida (Duj.).

B. Lumbrici (Stein) = Phyiotoma Lum-
brici (Duj.) = Paramecium co7)i2)rcssiim
(Ehr.) is a Bursaria, not a Parame-
cium, having a row of longer cilia about
the mouth and venti*al surface.

Genus SPIEOSTOMUM (XXIV. 296*-298).— Body elongated, or ribbon-
shaped, flexible nnd ciliated, the frontal region continuous; mouth lateral,
spiral-sliaped, devoid of teeth, but witli a tremulous flap. Tlie locomotive

OF THE TEACHELUTA.

623

cilia are disposed in rows ; those at the moutli arc longer, and form, as in
Stentor, a spii-al weath aronnd it ; in >S. amhigmvm the brow and wreath are
remarkably long. Vacuoles, to the number of ninety, have been seen filled
with colom-ed food, and the discharge of the latter observed. The anus is
placed at the posterior extremity. [A band-Kke thick gland (nucleus) is seen in
S. virens, and a bead-hke one in other species.] The former likewise possesses
a largo contractile vesicle, and gi'een granules ; ia 8. ambiguum the granules
are white. Self-division has not been observed, but Ehrenberg presumes that
it takes place transversely.

The band-lilce or moniliform gland mentioned by Ehrenberg ls in fact a
pulsating vessel extending almost the entii-e length of the animalcule. The
genus does not belong to TracheUna, but to a family represented by Stentor,
which Lachmann and others would estabhsh with the name of Stentorina.
Perty transfers Spirostomum to Urceolaiina, in which family it is united with
Stentor, Camomor^pha, and Urocentrmi. (See remarks on Vojbticellina,
p. 579.)

SprROSTomiM virens {Bursaria spiri-
g&ra, D.) (xxrv. 296*). — Ovate-elongate,
depressed ; ti-uncated anteriorly, and
roimded posterioriy. The back is arched,
and the imder side flat. The green gra-
nules are sometimes absent (f. 296*).
1-120" ; ova 1-6000".

S. amhiguum (LeucopJm/s llb-ichoda]
amhigua, M.;) (xxrv. 297, 298.)— White,
cyhndiical, nlifonn, flexible ; obtuse an-
teriorly, ti'imcated posteriorly ; an elon-
gated frontal region or brow extends be-
yond the mouth. The long vibrating
cilia in front often appear like a pro-
boscis, and were mistaken for such by
Miiller. The structm-e of this creatm'e
is remai'kable, especially the mouth,
which is only one-fifth from the tail ;
thus the fr'ontal region or brow is very
long, and the alimentaiy canal (adds
Ehr.), first inflected forwards, retm-ns

along the body. From the mouth to the
anterior or top of the brow rims a long
ciliated furrow (xxiv. 297 and 298). In
swimming, they extend themseh-es, and
are readily perceived by the naked eye.
In ditches, among decaying oak-leaves
and rotten wood. 1-12".

Both Dujardin and Perty consider this
animalcide to be the same as that other-
wise described by Ehrenberg as Ui'o-
leptus Filum.

S. semper virescens (Perty). — Body
roimd, filled with gi-een gramdes ; tail
broad, flat, and colomless. Ciha at
anterior extremity, clearly seen. The
green colour was probably due to the
food. 1-96". Among Lemuse, but only
once. 'It is allied to Kondylostoma
(Duj.), which difiers from it by its
marine habitat.

Genus PHIALINA (XXIV. 299).— The frontal ciHated portion is sepa-
rated from the non-ciliated body by a constriction or neck ; mouth lateral
devoid of teeth. The motion of these creatiu-es is due to the powerftii
wreath of cilia over the mouth. Ehrenberg says, cilia may possibly be
present upon the surface of the body, since Midler described them in Trichoda
mellitea. A contractile vesicle (perhaps two) is situated posteriorly. Self-
division probably transverse.

Dujardin rejects this genus ; and, in Perty's opinion, the animalcules it
includes are no other than more contracted and younger specimens of Tra
chelocerca Unguifera or of Lacrymaria. Amongst them are specimens Avith
an evident terminal flap or tongue, and others with incompletely developed
necks. Theu- movements are rapid. (See notes on Lacrymauia p 609 )

Phialxna vernncularis (TricJioda ver-
miciilaris, M.).— Ovate, attenuated an-
teriorly ; neck very short ; colour wliito,
With LemnfB. 1-240".

P. viridis (xxiv. 299).— Bottled-shaped,
anteriorpartacute,the posterior gi-ndually

attenuated; neck very sliort. 1-280"
There is notliing di.stiiictive in the
assigned characters of this species; the
slight diflerence in form may arise from
tlio varying amount of contraction. The
gi-eeu colour is valueless.

624

SYSTEMATIC HISTORY OF THE INFUSOttlA.

Gemis GLAUCOMA (XXIV. 300-302 ; XXVIII. 4-7).— Body oval, com-
pressed, covered witli cilia ; mouth provided with a tremulous flap, but no
teeth. Ehrenhorg described the reception and discharge of food, 'and tlie
presence of digestive vacuoles, and therefore saw, in these, indications of the
existence of an alimentary canal. The large mouth, with its vibratoiy valves,
is situated on the inferior side, in advance of the middle. The anus is situated
on the ventral surface, near the posterior extremity, or at the extremity
itself. The internal organs are a large ovate gland, a star-like contractile
sac, and granules. Self-division transverse or longitiidinal.

Olmicoma is comprised by Dujardin among his Paramecina. Perty con-
structs a family out of this genus, along -with Cinetochilum (vide Cyclidium,
p. 572), which he designates Cinetochilina, and characterizes as animalcules
having a mouth on the upper side, surmounted by a vibrating valve (hke a
tremulous eyelid). Cilia disposed in longitudinal rows. It will be noticed
that the mouth is described to be on the upper side instead of the under, as
stated by Ehrenberg, with whom we agree.

The anus is on the ventral siu-face, near the posterior extremity. Lachmann
describes two flaps to the mouth, but Perty says the second is simply an
expansion of the margin of the mouth.

Glaucoma scintillam ( CyclidkimBulla,
M.) (xxviii. 4-7). — Elliptical or ovate,
colourless, sliolitly depressed; vacuoles
large. The vibrating flap appears to be
semi-oval or reniform and smooth, and
to have a stiff margin. The cilia are
seen by emplojdng colour or by pressing

or di'yuig the animalcules (xxiv. 300-
302). In natiu'al and artificial infusions.
1-280".

G. viridis (Duj.). — Green, oval, short;
mouth large, situated nearer the centre
thau to the anterior margin. 1-860" to
1-520". lu rain-water butts.

Genus CHILODON (XXIV. 303-309 ; XXIX. 48-59).— Body irregularly
oval, flattened, regularly ciliated : fi-ontal region produced in the form of a
broad membranous lip, on one side, resembling a beak ; the mouth, situated
at its base, and therefore lateral, is furnished with a tubular fascicle of teeth.
A round nucleus, one or more conti'actile vesicles, and transverse and longi-
tudinal self-division have been observed.

This genus along with Nassula, Prorodon, and two newly-instituted genera.
Cychgramma and Habrodon, are grouped together in the system of Perty,
as a family styled " Decteria," which is thus characterized: — "Mouth besot
with a circlet of fine bristles. In the first three genera the mouth is lateral ;
in the remaining two, anterior."

Stein makes Chilodon distinct from Nassula, by its body being compressed,
having a distinct upper and under surface, and a lip-like process above the
mouth.

Chilodon Cuctdlulus {^Knlpoda Cuculliis,
M.) (xxrv. 30.3-507; xxix. 48-59).—
Body depressed, oblong or ovate, rounded
at the ends ; frontal region advancing on
the right aide. [Ehrenberg states ho has
often seen the straight alimentary canal,
with its grape-lUte cells, filled witli
large Navicula;.] Contractile vesicles
from two to tliree ; nucleus largo, oval
near the centre. Tlie circlet of toclh
was stated by Ehrenberg to consist of
little hard wand-lilto bodies, wliich the
creature could sopnvnto so as to ndniit
into its mouth large living bodies, and

afterwards conti-act or close upon them
(xxiv. 308, 309). The anus is at one
side of the posterior extremity. In
swimming, or creeping upon tlie surfnce
of Conferva;, the mouth is turned under
or below. Its motion is gliding; and it
does not revolve in swimming. "When
the water is coloured, tlie cilia may be
ea.«ily perceived, and their disposition
wlion it is dried up. (Figs. 305 and 306
exhibit longitudiii.al, .nnd .307 transverse
self-division.) Tn fresh and salt water.
1-11.50" to 1-140'.
Tliis speeies hum received a clcse in-

OF TITE THACHEIilNA.

625

vesti^ation by Stein. The circlet of t^eth
(bacUlar apparatus, Lachmann) is con-
structed of uo actually separate portions
or teeth, as Ehrenber^ supposed, but is
nothing more than a thickened oesopha-
gus with denser rugae, or folds, of a chi-
tinous composition. From its lower end
a digestive tube extends to neaiiy the
centre of the body.

C. imcinatus. — Depressed, oblong,
roimded at the ends. The right side of
the anterior part is produced, so as to
appear like a hook or beak. In vegetable
infusions. 1-430".

This being is, in Stein's opinion, a
mere variety of C. Ciicullulus : the bulging-
out of the side has a somewhat hook-like
process ; but this ia a mere accidental re-
sidt following the process of longitudinal
self-division (J^i/Ms. p. 130). It has been
seen to encyst itself.

C. aureus. — Ovate-conical, txirgid, of
a golden yellow colom- ; dilated and ob-
tusely rostrated anteriorly, attenuated
posteriorly. 1-140".

C. ornatiis. — Ovate subcylindrical, of
a golden yellow colom*, equally rounded
at both ends, slightly befiked; it has a
bright \-iolet spot. 1-180".

The violet spot spoken of has no di-
stinctive peculiarity ; it is not a normal
coloured gastric fluid, but only a collec-
tion of gi'anules, the same as in Nassula
elegam.

This species, together with the fore-
going C. aureus and the Nassula aurea,
are so very similar, that Stein doubts
their independent natm'e, and is more dis-
posed to regard them as developmental
phases of the same being.

0. depressus (Perty). — Irregular, with-
out a beak, and roimded at both ends ;
compressed; almost colourless. Trans-
parent, with greyish contents. Upper and
under surfaces equally flat. Tooth-cylin-
der very evident. Switzerland. 1-120".

Stein states that the body is bilateral,
presenting a distinct right and left side,
an upper (dorsal) convex and a lower
(ventral) flat sm-face. The anterior end
is much flattened and transparent; and
bemg ciu'ved towards the left side, gives
the whole being a somewhat reniform
figm'e. The depression on this side is
always in advance of the middle of the
bodj', just as m. Paramecium Colpoda and
Colpoda Cucullidus. The anterior, ciu-ved
transparent end sunnounts the body like
a crescentic process, is furnished with
longer cilia than elsewhere, and may not
inaptly be called the lip. Vibratile cilia
cover the body in regidar rows, but in
very young specimens ai'e invisible ex-
cept on the lip. The oval nucleus is
hoUowed by a cavity, within which is a
nucleolus. Longitudinal and transverse
fission takes place in individuals of all
sizes. The former advances fi'om the
posterior exti'emitj' ; the oesophageal
(dental) cylinder is not divided, but is
produced de novo in the newly produced
segment: this segment, when first de-
tached, is the Cliilodon uncinatm (Ehr.).
Cliilodon Cucullulus encysts itself : a soft
gelatinous matter is first thrown out
aroimd it, which hardens into the cyst-
wall ; dua'ing this process the superficial
cilia and the oesophageal cylinder disap-
pear, and at length an oval cj'^st, with a
large nucleus, and two to three contractile
spaces alone appear. Gradually a cili-
ated embryo is developed from the
nucleus, resembling in external charac-
ters a CycUdium Glamoma. The embrvo
escapes from the parent animal; and
cysts are sometimes foimd containing
the pai-ent and its oftspring side bv side
within it. The development of enibrvos
may go on imtil the nucleus is expended.
The size of the germ is detennmed by
that of its pareixt.

Genas NASSULA (XXIV. 310, 311 ; XXVIIL 2, 3, 11-15). — Covered
vnih. ciHa ; ovoid or oblong ; turgid and prominent in front, but without the
expansion or beak on one side ; mouth lateral, provided with a circlet of teeth
in the form of a wheel {nassa). Numerous vacuoles are seen, and in two
species, as Ehrenberg states, the discharging orifice. The violet- coloured
granular spots noticed in Cliilodon omatus occur also in the species of Nassula
and are likewise met with in Bursaria vernalis, TracheUus Meleanris AmpU
leptus margaritifer, A. Melem/ris, and A. longicolUs. " Tliey resemble " savs
Ehrenbcrg " the vesicular glands around the stomachs of the Rotatoria and
are probably of a glandular nature, analogous to biliary glands, and concerned
m the process of digestion " The nucleus is large, oval or splxerical ; auTtWe
are one or more contractile vesicles. Only transverse self-division has been

2 s

626

SYSTEMATIC UISTORY OF THK INFUSOniA.

observed. They are found in stagnant water, especially where Confervce and
OscillatorifE are present.

The violet-coloured supposed digestive glands or cells are, in the opinion
of others, simply vesicles coloured by the Oscillatoria on which the animal-
cules feed (p. 312).

This genus and the preceding, Chilodon, are very closely aUied. Stein
finds the best distinctions between the two in the rounded body with the ex-
tremities obtuse and rounded off, in the case of Nassula, and in the flattened,
compressed body, with decided ventral and dorsal surfaces and with a lip-like
process, in Chilodon.

NASStTLA elegans (xxl^^ 310, 311;
xxvm. 11-15). — Cylindi'ical or oval,
slightly attenuated in front, exti'emities
very obtuse. It is white or greenish,
spotted with violet vesicles. Vacuoles,
containing Chlamidomonads or other
food, may often be observed ; and fi-om
fifteen to twenty rows of cilia may be
seen on one aspect. The animalcule
swhns backward and forwai'd, tm'ning
upon its longitudinal axis. The mouth
is easily perceived by the cmrents when
indigo is mixed with the water : it has
a circlet containing twenty-six little
wands or teeth, which can voluntarily
diverge or converge anteriorly. Four
roimd contTactUe vesicles, placed in a
row, occm' on the dorsal sm-face, and
doubtless represent fom- expansions of a
continuous contractile vessel along that
region. The violet vesicles mentioned
are only accidental (i. e. not necessary)
collections of pigment matter, derived
fi'oni the food (see p. 312). When self-
division ensues, the large central nucleus
divides (xxiv. 310, 311; the latter is a
young one). With Lemnse and Con-
fervEe. 1-140" to 1-120". Nassula ele-
gans is thus characterized by Cohn : —
Elongate with roimded extremities;
oesophagus funnel-shaped; no cylinder
of teeth present as in N. ornata. Con-
tractile vesicles two; nucleus elliptic,
with nucleolus lodged in a fossa at one
end. A large mass of violet granules on
under sm-face posteriorly. It resembles
but is smaller than Paramecimn Aurelia,
and has a similar cuticle. With Bursaria
truncatella and Ophryoglena atra. It is
smaller than N. ornata. Its changes of
form are remarkable ; often dependent
on swallowed joints of Oscillatoricc. Cilia
very closely di.sposed.

N. oniata (iV. viridis?, D.) (xxvin.
65-71). — Ovate or globular, depressed, |

of a brownish-green colom-, variegated
with niunerous violet vesicles. The
posterior part of the body has a small
excavation. Ehrenberg says, there are
from six to eight gi-oups of vesicles,
forming a wide circle roimd the mouth,
filled with a violet-coloured juice, which
is discharged with the excreta, and ap-
pears like drops of oil, but soon mixes
with and colours the water. It swims
rapidly, rotating also on itself, but this
only slowly. Among swimming clusters
of Oscillatorim. 1-96" ; ova 1-4800". It
has been seen in an encysted state.

N. aurea. — Ovate-oblong, nearly cylin-
drical, very obtuse at the extremities.
Its colour varies from golden yeUow to
a dai-k brown. 1-120".

Stein hints it as probable that this
species and N. viridis (Duj.), Chilodon
aureus, and CJi. ornatus are merely dif-
ferent stages of the same animal.

N. ambigua (Stein) (xxvra. 2, 3). —
Rounded, short oval ; extremities equally
rounded. Entire sinfnce covered bv cilia
in longitudinal rows. The wedge-shaped
oral opening sm-moimts a very wide pha-
rynx (tooth-cylinder, Ehr.) which may
be easily isolated. The contractile vesicle
acquires a stellate figiu-e during its con-
tractions and dilatations, like that of
Cliilodon ornatus. The contents are ori-
ginally colourless, but become tinted
green, blue, and red successively, during
the process of digestion of the Oscillatoria
it feeds upon. It occm-s encysted, in
a transparent, resistant, globular cvst.
Length 1-240" ; width 1-420". "

N. concinna (Perty). — Ovate, hyaline,
transpai-ent ; covered evcrnvhcre with
fine granules having an annular an-ange-
ment. Dental appai-atus particularly de-
licate, more evident when dried. Cilia
very tine ; movements sluggish ; anal
opening at posterior extremity. 1-216".

Genus LIOSIPHON (Ehr.).— Turgid ; cUiated throughout ; frontal ex-
tremity advanced beyond the mouth, and not auriculate. Mouth opens into
a tubular membranous pliarynx. provided with a cj-liudor of tooth.

OF THE TKACHELINA.

627

This is a new genus instituted by Ehrenberg. Its essential distinction from
Nassiila is not pointed out, the only one indicated being the prolongation of
the frontal region beyond the oral apertui-e.

Liosi?HON-S'</-o>«yjM.— Obtuse, ovate; I pharynx of a clavate outline. 1-36"'.
of a variegated green coloiu- ; tube of | With Oscillatori<x.

The genera named by Dujardin, having a near affinity with Bursaria, are
Plagiotoma, Kondylostoma, Opalina, and Panophrys. Two others, Adneria
and Pelecida (Duj.), ai-e described as allies of Trachelius.

Genus OPALINA. — Abeady described in the Astomatous family Opalinaea
(vide p. 569).

Genus PLAGIOTOMA (Duj.). — Body very flat or lamellar, very flexible,
ii-regularly oval ; sinuous or emarginate on one side, and sometimes angular
behind ; covered with cilia in regular rows ; mouth lateral, near the middle,
at the bottom of the depression, with a row of strong and very numerous cilia
in advance of it on its anterior margin, having a eomb-like aspect.

Plagiotoma Lumbrici = Paramecium
compressum (Ehr.). — Stein shows this to
be a true Bursaria (see p. 622).

P. concharum (Perty) = Leucophrys
AnondonUe (Ekr.). — This and the fore-
going are, in Stein's opinion, Opalince
(see p. 570).

P. (?) difformis. — ^IiTegulai-, thick, and

of a yellowish gi'ey colom* fi'om contained
molecules. Owing to its want of trans-
parency, tlie fine sLort cilia are visible
only around the periphery. Motion ex-
tremely languid, oscillating and revolv-
ing. 1-260". In the mterior of Ano-
donta Cellensis.

Genus KONDYLOSTOMA (Duj.).— Body more or less elongated, cyHn-
diical or fusiform, rather crescentic, with obtuse and flattened ends ; mouth
very large, bordered by very strong cUia, and placed on one side near the
anterior extremity ; surface obliquely striated and ciliated. It swallows its
food, consisting of other animalcules or of vegetable debris, rather after the
manner of Planarice than of Paramecina ; for it does not draw it in by the
action of its ciha in producing a vortex. It lives only in smooth and pure
sea- water among Algas, &c.

KoNDYi/OSTOMA patens. — Body white, modified in figure by the bulk of food
or coloured by the food received ; at times swallowed,
vemiform, at others fusifoi-m, and often

Genus PANOPHRTS (Diij.) (XXYI. 33).— Ciliated throughout; oval,
depressed, contractile ; becoming ovoid, or even globular, dining contraction •
surface marked by straight or oblique ciliated striae, crossing one another •
mouth lateral. Dujardin writes — " Being desirous of characterizing Bur-
saria by the row of large cilia, en moustache, which lead to the mouth I have
thought it right to establish a new genus for certain Bursaria} of Ehrenberg,
which are devoid of this character, and whose mouth is surrounded by only
ordinary cilia." Unlike the Paramecia, they have no anterior oblique fold
or fossa, and are able to contract themselves into a ball. They diffbr fi-om
Holophrya by their lateral mouth. They live eitlicr in fresh smooth water
or in sea- water among plants. '

In Perty's system it constitutes a member of the family Paramecina • and
this IS its tine position, if the cilia are thi-oughout of equal length Indeed
the characters assumed to be distinctive of it from Paramecium api^car to us
inconclusive A lateral fold or vestibulum leading to the mouth is not entii-elv
wanting, although less developed than in most Paramecia ; and as to their

2 s 2

628

SYSTEMATIC HISTOEY OF THE INFUSOMA.

greater contractile power, this really-
proper generic character.

Panophbys Clirysalis (xx^t:. 33). —
Ovoid, oblong, depressed, mouth accom-
panied by an enlargement, and placed
near the front exti-emity. 1-145" In
sea-water.

P. ruhra (?). — Reniform, covered with
fine cQia, and provided with a lateral
mouth near the fi'ont extremity. 1-370"
to 1-325". In sea-water. Only pro-
visionally named.

V.farcta. — Ovoid, oblong, filled with
particles of a green reddish-yellow hue,
or of various mingled colours; mouth
lateral, placed between the centre and the
anterior third of the body. Its outline
is very changeable, its movements rapid.
The colour is seldom gi-een. 1-145" to
1-95". In marsh-water among plants.
I think it is the animalcule described
\inder three names by Ehrenberg, -vvl.
Bursaria vernalis, B. leucas, andB.Jlava,
find is probably the same as Leucophra
virescens of Miiller.

Although Pei-ty acquiesces in the be-
lief that the yellow-coloured specimens
of this species are the Bursaria fiava
(Ehr.), yet he thinks Dujardin wrong
in claiming B. leucas and B. vernalis as
varieties.

P. conspicua (Perty). — Large ; cylin-
drical, scarcely smaller behind than in
front ; mouth roimd. Coloured by food
dark green. Swims, revolving at the
same time with moderate speed. 1-95".
In peaty ponds with Lemnse.

P. sorchda (Perty). — Cylindrical, more
or less elongated ; colom- dark, earthy-
brown. Mouth small. Cilia coveiing the
body, fine. The position of the internal
molecules varies even dui-ing examina-
tion, and the figure with them. 1-180"
to 1-96". Among Char£e.

P. griseola (Perty) (xxviii. 31). —
Broad, distended ; gi'ey, but ti-ansparent,
with a fine reticulate appearance ; mar-
ginal concentric stria). Sometimes occu-
pie(J with chlorophyll-granides, when |

is questionable, and, if true, is not a

it much resembles Ophryoglena griseo-
virens. The mouth appears like an
elliptic fold in a shallow fossa in the
anterior half. It swims and turns on
itself with much activity. Transverse
fission obsei-ved. 1-300" to 1-108".
Among decaying plants.

P. zonalis (Perty). — Elongated, ovate-
cylindrical ; hyaline, with a central zone
of dark molecules. Exti-emities equally
wide, and rounded. Fissure of the mouth
beset with stronger cilia. Movements
rather sluggish. Body ciliated through-
out. 1-168".

This scarcely seems a true Panophrys ;
for the oral cilia are said to be larger
than those on the body, conti-ary to
Dujardin's characters of the genus.
Moreover its chief peculiarity, viz. the
zone of darker gi'anules, is an insufficient
specific feature ; and when we ai"e told
by Perty that he has oiily once seen a
small specimen, this supposed species has
few clauns to notice.

P. paramecioides (Pei-ty). — Cylindi-i-
cal, slightly curved, its posterior end
somewhat thicker than the anterior;
colourless ; rows of cilia very numerous
and fijie. Its molecular structui-e re-
sembles that of Paramecium Aurelia.
Movements energetic, twisting. The
mouth is placed m a shallow fossa on
one side of the body. 1-168". An un-
common fonn in Switzerland.

There is scarcely anything in the above
description which is not compatible vnili
the belief that the animalcule in ques-
tion is either a Bursaria or a Paratnca'um.
JNIoreover, reference to Perty's figm-es
lends no aid to the detenniuation of the
question ; and we must confess our in-
ability to find, in his illustrations of the
genns Panophrys, any sufficieutlv detailed
particulars to enable us to distinguish
either of the species named as members
of it from probable representatives of
allied genera.

Genus BLEPHARISMA (Perty) (XXVIII. 33, 34).— Body compressed,
lancet-shaped, with a pointed posterior extremity, whence a deep fossa ex-
tends as far as the middle, fringed with longer and straightcr cilia than cover
the rest of the body. The internal molecules are disposed in longitudinal
rows, over which the veiy fine and inconspicuous ciUa are arranged.

Blepharisma hyaliiium (xxA^rI. 33, older specimens are broader. jNIovements

34). — Colourless, except when occupied varied and tolerably rapid. Sometimes

by swallowed chlorophyll-particles. Body a few Inrge and noii-vibratile filaments

thin, flexible, and chiuigeable in fonn*; nppoar to issue from the oral fossa.

OF TIIE TBACnELINA.

629

Among Confervte and Lemnaj ; not corn-

specimens paler.
1-210" to 1-144".

Fission transverse.
At Bern, with the

uion.

B. persictimm = Trichoda striata (?) j preceding- ; rare.
(Miill.).— Colour reddish-yellow; yoimg

Genus ACIT^EEIA (Duj.) (XXVI. 21 a, ?;).— Body oblong, depressed, or
lanceolate, with a row of cilia extending forwards on one side, which is curved
like a sabre. Distinguished fi-om Trachelius by the disposition of the row of
cilia and the eurvatui-e forwards. As in Trachelius, the examples of this
genus seem destitute of a mouth, and in this respect they especially differ
from those of Pelecida.

AcrNEEiA incurvata (xx'st:. 21 a, b). —
Conti-actile, oblong, compressed, almost
lamellar, roimd or obtuse behind, con-
tracted and cm-ved in fi-ont; a row of
cilia nms along the convex edge; and
there ai-e five or six granular stripes,
and one or more variable vacuoles.
1-590". In the Mediterranean. It ap-

pears to be without a reticulated and
contractUe integument.

A. acuta. — Diaphanous, with granules
dispersed in its interior; oblong, com-
pressed, pointed at its two ends ; or
lanceolate, with one side more convex
in front and fringed with cilia. 1-580".
In pond-water.

Genus PELECIDA (Duj.). — Body flexible, contractile, oblong, compressed,
rounded behind, cuiwed in the form of an axe in front, ciliated thi'oughout,
and furnished with a mouth either visible or indicated by the various objects
met with in the interior of the animals.

The animalcule assumed as the type of this genus is the Loxodes Rostrum
of Ehrenberg. It is stated to differ from the Paramecina by the absence of

Perty introduces it into his system.

to fom* longitudinal folds. Colom-less.
1-320" to 1-210". Bern. In ponds, &c.

a contractile integument

Pelecida Rostrum (Duj.) = Loxodes
Rostru7n (Ehr.).

P. costata (Perty). — SmaU ; with two

the

Genus LEMBADION (Perty) (XXVIII. 50, 51).— Body oval, rather ven-
tricose; with one more or less deep and wide furrow running nearly the
entire length of the ventral sm-faee. About twenty rows of cUia on the dorsal
aspect ; on the margin of the furrows, and at the posterior extremity, are
longer cilia.

Internally from two to eight translucent large round vesicles are visible.
In Perty's classification this genus is a member of the family Biu-sarina
(see p. 621).

Lembadion 'bidUnum= Bursaria hid-
lina (Midi.) (xx^^^. 50, 51). — Hyaline,
filled with veiy delicate molecules ; tlie
spherical and often very large internal
vesicles difl'er much, both in number and
position. A proboscis-like process occurs
at the anterior extremity. Movement
tolerably quick, often gyrating. Trans-
verse fission ha-s been observed. 1-240"
to 1-190". In spring-water. Bern, Lu-
gano, &c. Ehrenberg has eiToneously
cited the Bursaria hullina (Schranlc),

present
as his

which is identical with
species, as. the same
Glaucoma scintillam.

_L. (?) duriusculum. — Colom-less, ellip-
soidal, with a keel or ridge along its
upper siu-face ; the under surface some-
what concave. It appears tolerably stiff
and firm in consistence; the cilia aro
very fini ' "
1

n-y fine, and ita movements "sluo-<rish
■720" to 1-G20". The position o! this
animalcule m this genus is doubtfiU.-

Gcnus HARMODIRUS (Perty).— Body globular, having a moveable elon-
gated lip or proboscis anteriorly.

It is a member of the TrachoUna (Perty), and is represented as being in
part equivalent to Ampluhptm (Duj.) and to TrachcUus\mx.).

630

SYSTEMATIC HISTOEY OF THE INFTTSOHIA.

Hahmodibds Ovum. — The proboscis
is not so much a process of the substance
of the body, as lite a jointed finger or
segment ; it has a jerking movement in
one direction, yet it appeal's frequently
stretched as a stiff process from one side.
Cilia extremely fine; thirty rows have
been coimted on one side ; they are most
evident near the proboscis. Diasti'ophy

may be frequently witnessed. 1-180" to
1-36". In fresh and bog water, with
Lemnte. This species is doubtless the
same as Trachelitis Ovum (Ehr.) and Am-
phileplus Ovum (Duj.) ; and Ave do not
conceive the necessity of elevating it to
the ranl£ of a genus on account of the
slight diflerential character of the pro-
boscis, as Perty has done.

Genus CINETOCHILUM (Perty) (XXVIII. 35).— SmaU, short, elliptical,
somewhat compressed ; vibratile flap on the posterior half.

CxNETOCHiLUM margaritaceum= Cyclidium margaritaceum (Ehr.) (see p. 673).

Genus CTCLOGEAMMA (Perty) (XXVIII. 36,37).— Body smaU, having
the form of Paramecium ; with concentric striae on the margin, and a lateral
depression near the fore part, where a mouth, with an obscure but pecuMai-
apparatus of from fom- to seven bristles, is apparent. It is a member of a
family called Decteria (see p. 624).

Ctclogramma ruhem.—Colova yel-
low, seldom green, or reddish-white.
Mostly rather compressed; rai-ely sub-
cylindrical. Cilia very fine, with the
exception of those on the margin, which

are aiTanged in circular rows. Move-
ment commonly sluggish. The dental
apparatus is evident in some examples,
but undiscoverable in others. 1-480" to
1-300". Ponds, Bern.

FAMILY VIII.— OPHEYOCEECINA.

Polygastria without lorica ; alimentary canal with two distinct oiifices, of
which only the anal one is terminal. Although their motion is rapid, cilia
are perceived near the mouth only, though they probably cover the body ;
the long neck assists in swimming, and indeed is sufficient alone. Granules
(ova?) are seen in aU the species, and a contractile vesicle in T. biceps.
Self-division probable, but not observed.

No such family as Opliryocercina enters into the system of Dujardin, the
animalcules composing it being all referred to the genus Lacrymaria (see
p. 609) ; and consequently that of Trachelocerca is merged in the same.

On the other hand, Perty retaius this family name, but, unlike Ehrenberg,
comprehends in it both Trachelocerca and Lacrymaria : moreover he assigns
to Trachelocerca a wider generic signification, so that it includes also Fhialina
(Ehr.). Again, this family is the representative of one of his tkrce chief
sections of Ciliata, viz. Metabolica, thus defined: — " Animalcules very con-
tractile, Tindergoing protean changes of figiu-e by the expansions and con-
tractions of the body. Cilia scai'ccly visible upon tlic body, but clearly seen
on its neck-Uke process." Lachmann describes the oesophagus in this family
to be collapsed, or iavisible, except duiing the passage of food.

Genus TEACHELOCERCA.— Chai-acters as above.

Thachelocekca Olor { Vihno Proteus,
Cygnus et Olor, M.; Lacrt/marin Olor,
D.; (xxiv. 317, 318, 319).— Spindle-
shaped ; neck vciy long and flexible,
tenninated by a dilated and ciliated
mouth. The surface is beautifully reti-
culate in this and the following species.
This crealure creepp nt the bottom of

the vessel containing it, and twines
itself gracefully about Confervas, or the
roots of I>enuire, but swims awkwardly.
It elongates and contracts its nock at
pleasure, and is altogether an interesting
object for the microscope. Greatest
length 1-3C". It has been found en-
cysted.

OF THE ASriDISCINA AND KOLPODEA.

631

T. virtdis (Lacnjmaria viridis, D.). —
Spindle-shaped, neck simple, very mo-
bile, long, and dilated at the mouth,
Avhich has a ciliated lip. Amongst
LemniB. Length 1-120" ; contracted
1-380".

Perty changes the specific name to
" linffuifera," and has the very good
reason for so doing that the green colour
is no distinction, because it is often
changed to brown, and, besides vai'ious
intermediate tints, is at times greyish or
colom-less. Unlike T. Olor, the neck is
surmounted by a moveable flap or pro-

cess, styled a tongue, fringed with di-
stinct cilia. Perty speaks of specimens
1-72" in length.

T. biceps. — Spindle-shaped, white ;
neck long, forked, each segment with a
mouth. 1-190".

This can have no claim as a species,
since it is evidently nothing more than
an animalcule in the act of longitudinal
fission, not far advanced.

T. Saffifta= Vibrio Sagitta (M.). — Fu-
sifoiTO, white ; neck very long ; head ter-
minal, opaque. 1-120". North Sea and
Baltic.

FAMILY IX.— ASPIDISCINA.
(XXV. 321-323.)

Distinguished from the preceding family by the presence of a lorica. The
alimentary canal has two orifices, of which the discharging one only is terminal.
The lorica is firm, very transjoarent, and combustible, somewhat resembling
the shell (carapace) which covers the back of a tortoise ; it projects anteriorly
a little beyond the body. Long flexible bristle-Ulie organs attached to the
abdomen enable the animalcules to cKmb, while the delicate cilia near the
mouth serve both as swimming and purveying organs. Numeroxis vacuoles
have been fUled with coloured food by Ehrenberg, who has also seen the
discharge of matter posteriorly. An oval nucleus and a contractile vesicle
occur in both species. Miiller observed self-division, but mistook it for
copulation. They are not developed in large masses.

Genus ASPIDISCA. — Characters as above.

AspiDiscA lynceus (Triclioda lynceus,
M.). — Lorica nearly cu'cular, truncated
at the posterior end, and formed into a
hook or beak in front. Mouth furnished
with very delicate cilia ; five or six
bristles (styles) are affixed posteriorly,
and from five to eight hooks anteriorly,
whereby a resemblance to Euplotes and
Stylonychia is established. A contractile
vesicle, near the mouth, and twenty
vacuoles have been seen. When burnt
upon platiua no traces remain. Gene-
rally swims or creeps with its back

imdemeath. Amongst Lemnas and Con-
fervte. 1-1000" to 1-576".

Stein asserts that it is an eiTor to
detach this species from Euplotes, vnth
which it has the closest affinity, and to
elevate it to the rank of a familv in
immediate contiguity with Colpo'dea,
with which it has no natui-al relation.

A. denticulata. — Lorica nearly circular,
under side ti-uncated and denticidated,
flat ; back ai-ched. The micini are ^dsible
only when climbing. 1-7G".

FAMILY X.— KOLPODEA or COLPODEA.
(XXIV. 312-316; XXV. 325-335; XXVI. 23, 32, 33; XXVIII 24-26
31, 33, 34 ; XXIX. 19, 20, 25-47.)
Animalcules ciliated througliout ; the cilia disposed in longitudinal series
and either of uniform length throughout, or of larger growth at particular
parts, especially about the mouth. Both mouth and anus demonstrable
always lateral, sometimes situated on the same side, at others on onnosite
sides of the body. ^ ^

Except AmpMeptus and Urohpim, the other genera have botli the mouth
and anus on the ventral sui-face. In the former genus Laclimann likewise
describes the oesophag-us to be coUapsed, except during tho passage of food
when It presents tlie appearance of a canal. In all other genera of Kolpodoa

032

SYSTEMATIC HISTOKY OF THE INFUSOEIA,

the oesophagus is distinct, of considerable length, and ciliated, but not thick-
ened at any portion so as to produce the appearance of a dental cylinder " or
bacillar apparatus." Coloured food received by all the species. Contractile
vesicles one or two in number, and in Paramecium of a stellate figiu-e.
Nucleus iisually rounded, oval or reniform. A red spot, eye-speck or stigma,
is common ia Ophryoglena. Propagation takes place by fission, which may
be either transverse or longitudinal ; by the production of single living em-
biyos (at least this occurs in Paramecium and Colpoda) ; and, in Perty and
Carter's opinion, by numerous germs oi' internal ova. The encysting-process
has also been seen in aU the genera except Uroleptus. The integument of
Kolpodea is reticulated, presenting a beautiful diamond-pattern, and ha^'ing
a cilium seated in the centre of each lozenge.

The Kolpodea are highly-organized Cniata, although inferior in this respect
to the VorticeUina. The single circumstance of the limitation of the ciha to
the head in the latter family is of itself, according to a well-recognized law
of animal life, an intimation of a higher grade of organization.

The genera are disposed as follows : —

Eye absent.

' Short protruding tongue. | absent posteriorly, Kolpoda.

1 present everywhere Paramecium.

No tongue

r With tail and proboscis Amphileptus.

[ With tail, no proboscis Uroleptus.

Eye present Ophryoglena.

This family corresponds generally with that of the Parameciens or Para-
mecina (Duj.), thus defined: — Body soft, flexible, variable in form, but
mostly oblong and more or less flattened ; provided with a loose, reticulated
integTiment, upon which niimerous vibratile cilia ai-e disposed in regular
series. Mouth present. The genera included are : — Lacrymaria, Pleuronema,
Glaucoma, Kolpoda, Paramecium, Amphileptus, Loxophyllum, Chilodon,
Panophrys, Nassida, Holophrya, and Prorodon.

Dujardin observes that Lacrymaria and Pleuronema should probably be
placed in a distinct family, since the mouth is rather presumed than demon-
strated in them. This is, however, a reason which, in the i)resent day, would
not be held valid, as the evidence of a mouth is equally strong in them as in
others of the genera enumerated.

Perty also has constructed a family Paramecina, containing the genera
Ophryoglena, Panophrys, Paramecium, Blcpharisma, and Colpoda, and briefly
characterized as having the body covered with longitudinal rows of ciha, and
a lateral mouth often within a fissure. Lastly, Mr. Carter has instituted a
now genus, named Otostoma, referable to this family, being a close ally to
Paramecium.

Genus KOLPODA or COLPODA. — Body ovoid, sometimes reniform ; a little
tongue-like member (a tuft of cUia) inserted in the oral cavity ; ciliated in
front and partly beneath ; eye-speck wanting. The mouth, posterior termi-
nation of the alimentaiy canal, and numerous gastric cells may be demon-
strated by coloiu-ed food ; the two orifices ai-e both on the ventral surface.
"Ova," adds Elirenberg, " occm- in delicate strings, forming a sort of network ;
and their extrusion has been seen in one species. A roimd contractile vesicle
is observable in two species, and two such in another. A large round or
oval gland (nucleus) is found in the centre of the body." Self-division both

OF XnE KOIPODEA.

G33

transverse and longitudinal. Theii- motion is not active, the locomotive cilia

being few. ,7-77

Dujardin, speaking of tHs genus, says, " Among Ehrenberg s AoZ^iorfce
which should possess a short tongue, and be ciliated only on the ventral
siu-face, but one species, K. Cucullus, is with certainty numbered ; the K. Ben,
and K. Cucullio have been referred to the genus Loxodes, where, iadeed, we still
leave them. However, Ehi-enberg places among the Paramecia, under the
appellation of F. Kolpoda, some large animalciaes, ciliated thi-oughout, Avhich
we regai-d as only more developed forms of Kolpoda Cucidliis.'"

Stein expresses himself on these views thus {Infus. p. 131) : — " Under the
name of Colpoda fttcitZZifsDujardin has described theParamecmm Coljooda,Ehi.,
appearing either to be unacquainted with the true Colpoda, or to have looked
upon it as an undeveloped state of Paramecium Colpoda" The distinctive
characters between these two animalcules and CJiilodon Cucidlulus are thus laid
down : — All these three forms are similar in oiithne, ChUodon Cucidlulus and
Colpoda Cucullus being really in most respects undistinguishahle. Paramecium
Colpoda is devoid of the peculiar hp, but has, on the other hand, an expanded
anterior extremity (brow), lying over and above the obhque infundibulum, on
one side of the body, leading to the mouth. CJiilodon CucuUulus displays, by
the action of chemical reagents, about the middle of its ventral surface its
special form of pharynx or oesophagus : it is, besides, cihated aU over ; but this
is a criterion determinable with difficulty, particularly in young specimens.
In Colpoda Cucullus the mouth is quite simple, and placed in the lateral de-
pression ; the distribution of the ciha is always pai"tial, chiefly hmited to the
lip. In Paramecium Colpoda the mouth (oral aperture) lies at the bottom of
a deep longitudinal fold (fissiu-e) on one side of the body, is bounded by two
very motUe hps, and conducts into a short, thin, walled, cihated oesophagus ;
the nucleus is oval, large, homogeneous, and finely granular ; and the body ia
very evidently ciliated all over.

Kolpoda Cucullus (j\r.)(xxv. 324-327;
xxrx. 35-47). — Turgid, slightly com-
pressed; kidney-shaped. The concavity
m which the oral apertiu-e is situated is
occupied by a process called by Ehren-
berg a "tongiie," but which Stein has
shown to be a bundle of longer cilia.
The cilia are not distributed over the
whole sm-face, but limited to the convex
svu&ce of the anterior half, augmenting
in size as they approach its elongated and
expanded, wide lip-like or frontal pro-
cess above the oral fossa, and to a ndge
extending downwards and bacltwards
from that fossa. The graniiles in the
interior are frequently so numerous as
to render it opaque ; they also give it a
grey colom*. The single contractile ve-
sicle is seated close to the posterior
extremity ; the nucleus is a circular disc
containing a nucleolus, and nearly cen-
tral in position. This animalcule has
not been seen to undergo fission whilst
in the free state ; the process, however,
goes on after it has encysted itself, with
various modifications in the results (see
Part I. p. 350). Ehrenberg having
adopted the notion that the breaJdng up

of a portion of the animalcule was an
act of oviposition, thought to fiuther
establish it by remarking the presence
of numerous Monadiform beings about
it, which he concluded were developed
from the supposed ova, as the first phase
of futm'e Colpoda. Such an interpreta-
tion has no evidence to support it, and
is rejected by Stein, (xxv. 324, the
nomial fonn ; fig. 325 represents the
animalcide, as Ehrenberg conceived, de-
positing its ova in a net-like mass, or,
as others would intei-pret it, in process
of diflluence; and figs. 326, 327, young
animalcules, which resemble Tr'ichoda
piirifor^nis.) Common in vegetable in-
fusions. 1-1800" to 1-280".

K. (?) Ren. — Ovate, cyliudiical, Idd-
ney-shapcd, and roimded at the ends.
In river-water. 1-288".

K. (?) Cuadlio{U.)=Loxodcs Cucullw,
(Icrty).— Compressed, plane, elliptical,
slightly sinuated anteriorly. Ehrenberg
remarks that neither cilia nor tongue-
like member was observable by bim
and that its generic situation is' there-
fore uncertain. Perty, however, has
noticed such n process. 1-900".

634 SySXKMATIC HISTOHY of the INFUgOBlA,

K. Luganensis (Perty). — Large, broad,
slightly convex on one side. Oral in-
fundibiilum deep. Eows of cilia un-

usually numerous. Movements slow;
internal corpuscles green. l-l;30". It
is probably a Kolpodu.

Genus PARAMECIUM (XXV. 329-332 ; XXIX. 25-34).— Body oblong,
compressed, ciliated on all sides ; mouth lateral, with a tongue-like process ;
no visual point. The cilia are disposed in longitudinal series ; those near the
mouth are sometimes longer than the others, and are alone subservient to
locomotion, except in two doubtful species. In P. Chrysalis the long oral cilia
are remarkable. The digestive cells, Ehrenberg proceeds to say, ai-e numerous,
amoimting to more than a hundred, and are an-anged in a beny-Kke manner
along the curved alimentary canal : in five sj^ecies they have been demon-
strated by artificial means, in a sixth by its usual green food. The ova in
two species are seen as a granular mass. In all, except one species, male
organs are visible. The curious star-like contractile vesicles in the larger
species are highly interesting, when physiologically considered, as are also the
little black bodies seen in P. Aurelia. In four species complete self-division,
transverse and longitudinal, has been obsei-ved alternately. This genus gives
name to a family Parameciens or Pai'amecLua in the systems of Dujardin and
Perty.

Stein makes the uniformity in length and thickness of the cilia a character-
istic of Paramecium, which distinguishes it both from Loxodes and Bursaria,
which have larger and stronger cilia about the mouth than cover the rest of
the body (see p. 285). Ehrenberg's statement that those about the mouth
are longer than the rest requii-es coiTection ; and the instance (P. Chrysalis)
cited radicates only that this species is not a Paramecium. Other par-
ticulars requiring revision are, that Paramecia have numerous stomachs dis-
posed as offsets upon a curved alimentary tube ; that the granular mass in
the interior consists of ova. The male organs referred to are the nucleus and
contractile vesicle or vesicles. In P. Aurelia and P. Bursaria Lachmann
states that the anus may be frequently recognized, in the form of a small pit
on the surface of the animals, even for a considerable time before and after
an excretion.

In our remarks on Pai^ophhts we have expressed a doubt as to the inde-
pendent position of that genus apart fi'om Paramecium.

Paeamecium Aitrelia (INI) (xxv. 329-
332). — Club-shaped, cylindiical, slightly
attenuated anteriorly. An oblique longi-
tudinal fold borders upon the very much
receding mouth. Ehrenberg states tliat
he has seen small dark crystalline bodies
abimdant in the frontal region, which,
he conceives, are indications of the pre-
sence of nervous matter, as such cry-
stalline bodies often accompany it. These
creatures appear to him also to have the
sense of taste, since in the same group
some individuals prefer one kind of food
and others another. This may be ob-
served by mixing blue and red colours
together, when some will feed upon the
fonner, others upon the latter, as indi-
cated by tlie colour of the digestive
cells : in some tlie cells have a violet
hue. After being fed with colour, they
may be dried upon glass or mien, and

thus presen-ed. According to the hypo-
thesis of Ehrenberg, the rays of the star-
like vesicle ai'e spennatic Aucts, through
which the fluid is forced upon the ova
in the vicinity bv the constantly repeated
acts of conti-action of the vesicle. The
ducts are long, and enter the ovarium at
many points (see p. 312 ct scq.). The
expiilsion of ova ha^ fi-equontly been ob-
served. The colour of these animalcides,
when bearing ova, is white by rellected
light, and yellow by transmitted : hence
the names '" gold and silver little fishes,"
so often applied to them by Joblot and
others ; those devoid of ova are coloiu'-
less. The cilia arc best seen when the
water is coloured ; there ai-e from 26 to
52 longitudinal rows along each side of
the body, according to Ehrenberg, wlio
savs that in some rows he counted from
(50 to 70 cilia, making 3(540 organs of

01^ THE KOLPODEA.

635

locomotion, and that each cilium is placed
upon a sort of little knob or articidated
biu" e (see p. 285). (Fig. 329, a dried spe-
cimen ; fig. 330, a creature feeding upon
indigo, the particles of which around
indicate the cun-ents produced by the
cilia ; fig. 332, an ideal view, to show
the structure of the nuti-itive organs as
stated by Ehrenberg ; fig. 331, a young
specimen, of the normal shape.) Abun-
dant in vegetable infusions, and increases
so rapidly in stagTiant waters that some
have referred theu" marvellous abxmdance
to spontaneous generation from elemen-
tary primitive matter. 1-120" to 1-96".

P. caudatum. — Spindle-shaped; obtuse
anteriorly, attenuated posteriorly. Not
in infusions, but in ponds, amongst
decayed sedge-leaves and Confervas.
1-120".

P. Clirysalis (M..) = Pleieronema eras-
sum (Duj.) (xx^t:. 23). — Oblong and
cylindrical, equally rounded at both
ends ; cilia about the mouth very long.
This species, like P. Aurelia, is often
developed in such vast myiiads that the
water has a millry hue, the masses as-
cending or descending in the fluid : this
appearance may be produced by slightly
shaking the water. In infusions and in
salt water. 1-240" to 1-190".

If the uniform length of the cilia be
admitted a generic character of Para-
median, this species, which has several
very long bristly cilia proceeding from
the oral fissure, must be excluded. Both
Dujardin and Perty have proposed this,
and made Paramecium Clirysalis the re-
presentative of a genus styled " Pleuro-
nema."

It is usually fiUed with greyish mole-
cules and vesicles, and rai-ely coloured
with chlorophyll. Fission longitudinal.
The long fibres from the lateral oral
fissures are from two to twelve in num-
ber, and, though frequently shorter, are
at times equal to or even much longer
than the body, and sei-ve to vary its
movements by their activitj'.

P. Kolpoda (Kolporla Ren, M. ; K. Cu-
cuUus, D.). — Ovate, slightly compressed ;
ends obtu.'^e, tl)o anterior attenuated and
slightly bont like a hoolc. Found espe-
cially in infusions of JJrtira dioica (the
stinging nettle). Perty is disposed to
believe this form to be an earlier stage
of P. Aurelia. 1-240".

P. (?) Sinaiticum. — Elliptical, com-
pressed, the back and under side cari-
nated (keeled); frontal cilia indistinct.
Amongst Confervte, in a brook on Mount
Sinai. 1-288".

P. (?) ovafum. — Ovate, turgid; an-
teriorly attenuated and rounded. In
stagnant river-water. 1-288".

P. compressum (Bni-saria Lumbrici,
Stein). — Elliptical or reniform, com-
pressed. An oblique wreath of long
cilia reaches to the middle, where the
mouth, with its slight tongue-like pro-
cess, is situated. Found in the river-
mussel {Mya), and in the intestine of
the earthworm {Liunhricus). 1-240" to
1-210".

Dujardin takes this species as the type
of a newly-formed genus, " Plagiotoma,"
characterized especially by its com-
pressed lamellar figure, and by its pai-a-
sitic habitat. Its cilia are described as
disposed in longitudinal rows over the
siu'face (vide ante, p. 627).

We agree with Stein that there is no
good reason for framing the genus Pla-
giotoma, as Dujardin has done, on the
characters of this animalcule. If it have
no mouth it should take its place among
the Opalince; and it is to be remarked
that though Dujardin clearly saw a deep
fold or fissm-e — a feature of Opalina: — he
could not succeed in artificially feeding
the animal with coloured food. At all
events, it has certainly no right to a place
among Paramecia, since the crest of
longer cilia about the mouth-like fossa
refers it (supposing it to have a mouth)
to the Bursari(B.

P. Milium (Cyclidium 3IiUum, M.). —
Small, oblong, trilateral; rounded equally
at both ends. In coloured water the
body is seen vibrating. 1-1150".

P. Bm 'saria = Loxodes Bursaria (Elir.)
(xxix. 25-34). — It is not a Loxodcs, since
all its cilia are equal and similar, Ehr-
enberg being in error respecting the ex-
istence of a larger sort in the infimdi-
bulum leading to the mouth.

P. versidnm (Mu\ler) = Bursaria vcr-
nalis (?) (Ehr.).— Perty revives this .spe-
cies ; but Lachmann {A. N. 11. 1857, xix.
215) thinks it unnecessary to do so, " as
there is scarcely any certainty in the
synonymy previous to l^hreubcrg; and
we .shoidd never again introduce an older
specific name for an Ini'usoriuni if it has
a name given to it by Ehrenberg, oven
when it is not improliablo he may have
overlooked an older nnnu\"

b. rar. Alpina (Perty). — Smaller,
plaited, stouter and more cylindrical
than P. rer.mtum.

P. fp-isoolian (Perty). — Little trans-
parent, b(!ing filled with gr6^^ah mole-
cules ; border very delicate. IVine to ten
longitudinal plaits on the surface. Move-

G3G

SYSTEJIAIIC niSTOHY OF TUE rNlfUSOEIA.

ment sudden, frequently oscillating'.

P. aureolu?n. — Transparent, peach-
coloiu-ed or golden yellow ; plaits strong.
Movements sluggish. 1-430".

P. leiicas=Bursaria leucas? (Ehr.). —
On one side a horn-like process, and on
the other a pair of eminences project.
Movements slow.

P. stomioptycha (E.). — Oblong, ob-
tusely ovate, turgid ; oral apertm-e large,

reniform, cilia long; body marked by
cn-cular folds ; lip with peculiar appen-
dages; vesicles two, stellate; nucleus
elongated, cylindrical. Moutli occupies
the anterior third of the body, sur-
moimted, however, by its obtuse frontal
end; cilia dense, in longitudinal rows;
vacuoles numerous; colour yellowish-
white ; nucleus above one-third of the
entire length, which varies fi-om 1-24"'
to 1-15"'.

Genus AMPHILEPTUS. — Tongue-like process and eye-speck absent ; but
the body is furnished with a proboscis and taU, and is elongated fusiform or
lanceolate. Cilia numerous, disposed in longitudinal series : in one species
cilia are not visible ; but in this the flexible attenuated extremities of the body
serve their office as locomotive organs. In some the tail (foot) and proboscis
(brow) are rudimentary. Numerous vacuoles filled with food may be fre-
quently seen ; the mouth and anus are usually distinguishable. A. marga-
ritifer has a pale rose-red fluid. A contractile vesicle and a nucleus are
found ; the latter is globidar or moniliform. Self-division occui-s both
transversely and longitudinally, or transversely only.

Speaking of Ehrenberg's distribution of this genus, Dujardin remarks —
" This- author, whilst assuming the presence of proboscis and taO. (as a cha-
racteristic), yet refers to the genus animalcules without tail, and dilated and
rounded posteriorly ; and on the other hand, whilst intent on seeking a
distinctive character for his different families in the position of the anus,
which he attributes to all his Enterodelous Infusoi-ia, he has left in his genus
Traclielius several species which to us appear to belong to Amjphileptus, and
has himself several times transferred some species from one genus to the
other." The AmpMleptus Anser is taken by Dujardin as the type of a genus
termed Dilej)tus, and A. Meleagris of one termed Loxopliyllwn. AmpMleptus is
the name of a genus comprehended by Pei-ty in his fandly Trachelina, which
appears generally equivalent to that bearing the same name in Ehrenberg's
system ; but it contains besides, Traclielius vorax. Cohn remaks that it is
imperfectly distinguished by Ehrenberg from Traclielius.

The Amphilepti are commonly found in the limpid water of marshes or
brooks, among aquatic plants.

Amphtleptus Anser ( Vibrio Anser et
Cygnus, M. = Dileptiis, D.) (xxiv. 312,
3i3). — Turgid, spindle-shaped; pro-
boscis obtuse, same length as body ; tail
short and acute. The neck-like pro-
boscis is in reality a brow or upper lip,
the mouth being at the base. Ehrenberg
thinks he has seen the anal opening upon
the dorsal surface, near the tail. 'The
motion of the body is slow, but that of
the proboscis more active. It is very
often coloured green with cliloropliyll,
received as food. Amongst dead sedge-
leaves, &c. 1-120".

A. mnrf/ariitfc?: — White, slender,
spindle-siiaped ; proboscis acute, equals
the length of the Dody ; tail short. Tlio
most striking features ai'e tlio swollen
margin of the mouth, and necldacc-like

series of vesicles disposed along the
body. It feeds iipon gi'een Monads, like
the preceding species in Ehrenberg's
iigiu'es. Cilia are not shown. Amongst
colonies of VorticeU<e, &c. 1-72". This
species is the countei-part of the pre-
ceding; and the distinction found by
Ehrenberg in the nccklace-lUve vesicles
has no value as such, since these vary
botli in number and position according
to the abundance of food and other
external circumstances.

A. moniligcr, — Tm'gid, ample, white ;
proboscis and taU short. It has a
necklace-like collection of rose-coloim>d
vesicles. Amongst duck-weed. 1-96"
to 1-72".

A. viridis.—TmgiA, spindle-shaped,
green; proboscis and tail short and

OF THE KOLPODEA.

637

Amongst Lemnse.

1-120"

transparent
to 1-9G".

A. Fasciola ( Vibrio Anas, Fasciola, et
intermedius, Paramecium Fasciola, M.)
(xxiY. 314-316 ; xxix. 19, 20).— White,
depressed, linear, lanceolate, convex
above, flat beneath. When viewed from
above, fi-om ten to twelve longitudinal
rows of delicate cilia may be seen, and
in the middle of the body two round
nuclei, and behind them a conti'actile
vesicle (xxiv. 314, 315, 316). In infri-
sions, in marshy ponds, &c. Perty states
that he has found it at an elevation of
5000 feet on the Alps, and also beneath
the ice. Cohn has watched its power of
encysting itself. (Siebold's Zeitschr. 1854,
V. p. 430). 1-720" to 1-144".

A. Meleagins (Kolpoda, M. ; Loxaphyl-
lum Meleagris, D.). — Laa'ge, compressed,
membranous, broadly lanceolate in
shape, with the crest of the back denti-
culated. The colour of this interesting
animalcule is white. On the under side
there is a more or less distinct row of
eight to ten bright colom'less spots.
These spots are, however, in no constant

number, as Ehrenberg supposed ; for they
are nothing more than coloured-food
vacuoles, which sometimes completely
fill the animalcule. With LemnjE.
1-72". (See notes on Nassula, p. 625.)

A. longicollis {Kolpoda ochrca, Triclioda
Felis, M.'). — DUated ; turgid posteriorly ;
attenuated and elongated anteriorly, lilce
a sword. Amongst Lemnee. 1-120" to
1-96".

A. (?) papillosus, — Depressed, lanceo-
late, fr'inged with papiUfe ; tail and pro-
boscis smooth. Amongst Oonfervee.
1-600" to 1-430".

A. Sphagni. — Depressed, lineai' or
linear-lanceolate ; proboscis trimcate
and keeled ; tail acute ; fringed v\ath
cilia on one side ; green corpuscles oc-
cupy the centre, leaving the extremities
of the body colomless or hyaline. 1-48"
to 1-12". Proboscis is one-fourth the
length of the body. Nucleus ovate;
cUia disposed spirally. Vacuoles some-
times enclose Bacillaria. Ovules (?)
large. Approaches A. Fasciola in general
chai'acters. On submerged Sphagnum,

Genus UEOLEPTUS (XXY. 333).— Furnished with a tail; eye-speck,
tongue-like process, and proboscis absent. Locomotion effected by the ciHa,
which cover the body, and are, in tlu'ee species, evidently disposed in rows.
Numerous vacuoles and a mouth have been demonstrated by colom-ed food ;
but a discharging orifice has not been satisfactorily determined. Green-
coloured granules are evident in two species, but no nucleus or vesicle.

This genus of Ehrenberg (says M. Dujardin), judging from the figm-es of
most of its species, should be in part united with Oxytncha. Thus Uroleptus
Pisds seems identical with Oxytriclia caudata (Duj.) ; U. Musculus (Ehr.) is,
in figui-e, an Oxytriclia ; whilst U. (?) Lamella is probably a Trachelius, and U.
Filum is rather allied to Spirostomum ambiguum. If these views be con'ect
Uroleptus should be erased from the list of genera. Three species counted in
this genus by Ehrenberg are rejected from it by Perty, and allied with Oayy-
tricha, — yiz. U. Musculus, U. Pisds, and U. Lamella.

Uroleptus Piscis {Trichoda Piscis,
M.). — Green ; in iigm-e like an elongated
top, gradually attenuated posteriorly,
forming a thick tail, covered with cilia,
those at the mouth largest. Found, in
Febi-uary and March, amongst the
floccose brown coat upon dead sedge-
leaves, along with Chlamydomonas and
Cryptomonas. Ilampstead ponds. 1-288"
to 1-44".

Perty doubts if there is any real di-
stinction between this animalcule and
the Oxytriclia caudata (Ehr.).

U. Musculus (Trichoda Musculus, M.)
(xxv. 333).— White, cylindrical, pear-
shaped, thickened posteriorly, where it
abmptly tenninates in a tail. The

and

movement rolling. It is inactive
rigid. With Oscillatories. 1-220".

U. /Jos;jes. — Greenish, ovate-oblono>
and turbinate in shape ; obliquely trun-
cated and excavated anteriorly; poste-
riorly terminated by a stylifonn acute
tail. In frog- and snail-spawn. 1-240".

U. (?) Lamella. — Transparent, linear-
lanceolate, depressed, flat, very thin In
infusions. 1-220".

U. Filian (Enchelys caudata, M.). —
White, filiform, cylindrical; rounded
anteriorly ; attenuated posterioriy, form-
ing a straight long tail. It is considered
a bpirostomum by Dujardin and Perty
(ivc/e ante, p. 623). Iii stagnant sprin/-
wnter, Sec. 1-48". ^

638

SYSTEMATIC HISTOET OF THE HTFUSOBIA.

Genus OPHEYOGLENA (XXV. 334, 335).— Ovoid, ciliated, with an eye-
speck anteriorly. Locomotion effected by the numerous regular longitudinal
rows of cilia. Some of the numerous digestive vacuoles are often filled with
Naviculce. The' mouth is situated in a fossa beneath the brow on one side ;
and the anal orifice lies upon the dorsal surface, at the base of the little tail.
A large central nucleus and one or more contractile vesicles are found ; trans-
verse and longitudinal self- division have been observed. A large red or black
stig ma is always present on the frontal region. These Infusoria are found in
stagnant fresh water, but not in infusions.

As Dujardin rightly remarks, this genus differs from Kolpoda only by
having a stigma or eye-speck ; however, he prefers to place it among Bur-
sarina, because the mouth is situated at the extremity of a row of cUia. In
this transposition of Ojjhryoglena, Perty does not agree, seeing that it has a
narrow mouth, and the closest affinity with Panoplirys, mth which, therefore,
he replaces it, along with Paramecium, &c., in the family Paramecina. We
are disposed to question its claim to a generic position ; for the coloured speck
is worthless as a distinctive character.

Ophbyoglena atra (Leucophra Ma-
milla, M.). — Blackish, ovoid, compressed,
acute posteriorly. A black stigma is
situated anteriorly near the dorsal mar-
gin. The mouth is at the bottom of a
funnel-shaped cavitj', commencing im-
mediately Beueath the brow ; within this
cavity Ehrenberg thinks he has lately
seen an oval bright gland. The colour-
less cilia appear like silver fringe on the
dusky animalcule, especiallv those in
front. In tm-f-hollows. 1-180".

0. aaiimi7iata (xxv.334,335). — ^Brown,
ovate, and compressed ; tail short and
acute ; stigma red. The brow projects
beyond the mouth abo\it the length of
the body, or, in other words, is situated
about the middle. In tiu:f-hoUows.
1-180".

0. flavicans. — Yellow, tm-gid, ovate,
attenuated and rounded posteriorly;
stigma red, irregailar in shape ; the cilia
near the mouth longer than in the pre-
ceding species ; Ehrenberg coimted from
twelve to sixteen rows at one view. In
turf-hollows. 1-144".

Nothing like a lens can be seen vnthin
the eye-speck ; but close to it there is an
hour-glass-shaped body, transparent and
apparently sti-uctureless. Its position
seems fixed, but it may be detached by
diffiucnce of the animnlcide,whenitswell8
up in the smTOimding water and often ex-
hibits a central cavity. Its presence is not

necessarily associated with the coloured
stigma : ih OphryogUna atra it is ab-
sent ; and whilst Bursaiia possesses this
organ, it has no coloured speck. In
other Infusoria having stigmata, such aa
Euglenaea, Peridinisea, &c., no such organ
is discoverable in connexion with them
(MuUer's Archiv, 1856/ p. 21). Stem
advances, as a distinctive character be-
tween Opli. fiavicans and Bursaria Jlaca,
the difference subsistmg in respect of the
nucleolus.

0. ffriseovirens (Pei-tj-). — Elliptical,
with more or less unequal sides ; usually
more pointed behind, and roimded in
front, where a red or dark pigment-speck
is visible. Hyaline, and when sti-ongly
magnified reticulai- ; but fi-equeutly con-
tains grey or green, and in rare cases
brown molecides. The marginal ciha
very distinct. Oral fossa in anterior
half. Movements quick and revolving.
1-300" to 1-180". In ponds, Bern.

0. Fa)iophrys (Perty). — Large, oval
when seen on the wider side ; pointed
end posterior ; colour greyish yellow ;
without pigment-speck. "NXHien seen on
the narrow side, the marginal cilia appear
in concenti'ic curved lines, whilst on
the broad side the cilia are close together
and apparently irregidai". Movements
slow. Usually swims on one of its wider
sides, and but" seldom revolves. Mouth
wide. 1-144". Uncommon.

Genus DILEPTUS (Duj.) (XXVI. 26).— This genus belongs to the family
" Trichodina " {ante, p. 608), and is thus defined :— Animal -wdth a fusiform
body, much elongated anteriorly, like long neck, with a mouth seated at the
base of the prolongation ; vibratile cilia cover the surface, and are of larger
size in front and near the mouth.

Ehrenberg has arranged Dihptiis with the Paramecina, although, unlike

OF THE OXYTRICnrNA.

639

the latter, destitute of a contractile reticulated integument. The type of this
genus is the Am;pUleptus Anser of Ehrenberg ; and the A. margaritifer (Ehr.)
is also referable to it.

leaf. In river-water. 1-175" to 1-130".

Party remarks that this organism can-
not be a species of Dileptus.

Deleptus Folium (Duj.) (xx^a. 26).
— Very flexible ; lanceolate, contracted
in front, with nodidar reticulated and
irregular sti-ipes, like the veins of a

Genus LOXOPHYLLUM (Duj.) (XXVI. 32).— Very depressed, lamellar,
oblique, very flexible ; sinuous or undulated along the borders ; mouth lateral ;
cUia in wide parallel rows.

Ehrenberg has comprehended Loxophyllum with Amphileptiis. Perty
makes the separation.

phyllum, as weU as the Kolpoda ochrea
of Mtiller, which Ehrenberg states to

L0XOPHTI.LTTM Meleagtis, the type of
the genus =Amphileptus Meleagris (Ehr. ) .

The Trachelius Meleagris (Ehr.) pro-
bably represents also another Loxo-

agi-ee with his AmpMleptm Imgicollis.

Genus PLEUEONEMA (Duj. and Perty) (XXVI. 23), represented by
tlic Paramecium Chrysalis (Ehr.), is thus defined by Dujardin : — "Body oval,
oblong, depressed ; having one large lateral orifice, from which a tuft of long,
floating and contractile filaments issues." It has nothing in common with
Paramecium, he adds, besides its oblong figure ; whilst the bundle of long
filaments has no analogy, except in the genus Alyscum. However, he places
it in his family Parameciens, whilst Perty introduces it as the sole represen-
tative of a family " Aphthonia," characterized as having, besides locomotive
cilia, other longer ones or filaments.

Pletjronjdma crassum- = Paramecium
Clm/salis (Ehr.). — Ovoid, much elon-
gated, rather depressed; with obtuse
ends ; tmely striated. Lateral orifice at

the anterior fourth of the body, with
long filaments, some proceedmg from
the border, others from the posterior ex-
tremity. 1-120". In the Mediterranean.

Genus OTOSTOMA {Q?ivteT,A.N.H. 1856, xvii. 117) (XXVIII. 24-20).—
Body ovoid, of a light brown colour, covered with longitudinal lines of cilia.
Mouth ear-shajied, in a depression situated about the junction of the anterior
with the middle third of the infusorium ; buccal cavity broad, short, curved
downwards, and a little upon itself outwards, plicated longitudinally in
parallel lines. Anus terminal ; gland or nucleus long, fusiform, situated
between the buccal ca-\dty and the contracting vesicles, wliich are double
and connected with a set of vessels something like those of Paramecium
Aurelia.

" It is," adds Mr. Carter, " a Paramecium closely allied to Nassula and
from the likeness of the oral oiificc to the human car, I propose for it the
name of ' Otostoma.' " Its cysts have been discovered on Nitella, and give
exit to monadiform beings approaching the parent Otostoma in form.

FAMILY XI.— OXYTRICHINA.

(XXV. 336-344; XXVIII. 43-47.)

Possess two separate alimentaiy orifices, neither of them situated at the
extremities, and are not encased by a dense integument (lorica). Tlicir loco-
motive organs are various, consisting of setaj, \ibratile cilia, and nou-vibratile
styles or uncini, variously situated, and render the creatures active. (Poly-
gastric cells, disposed upon an alimentary tube, were represented by Ehren"

640

SYSTEMATIC niSTOET OF THE INfUSOMA.

berg, except in Ceratidium.) A curved line of strong cilia leads towards the
mouth, which is situated about the median line at the posterior third of the
body, and opens into a ciliated oesophagus. The anus is behind the mouth,
on the same ventral siuface, near its margin. Complete trausverse and longi-
tudinal self-division is observed. The process of encysting may be presumed
general; in Urostyla Cohn has seen the ulterior development of a cihatcd
embryo.

Cilia and setae, no styles or uncini . . .

Brow without horns Oxytricha.

Brow with horns Ceratidium.

(With uncini, no styles Kerona.
With styles, no uncini Urostyla.
With styles and unciui Stylonychia.

This family is generally similar to the Keronina of Dujardin, — a famUy
of animalcules, according to this observer, much lower in the scale than
many in the families previously described, such as Kolpoda, Paramecium,
Coleps, &c.

" Processes in the form of styles or hooks characterize both the ' Keroniens '
and the 'Ploesconiens ; ' but the latter have a shield (lorica), whilst the former
are soft and have no sign of an integument. Of the ' Keroniens ' the Oxy-
tricha have neither horns nor hooks, but only eirrhi or sti'aight processes,
apparently rigid ; another genus, ' Haltena,' has large cin-hi like the pre-
ceding, but differs considerably in its mode of Hfe and its movements.

" The Urostyla of Ehrenberg, with styles only, and no hooks (uncini), we
unite with Oxytricha; and his Stylonychia, provided with both stjdes and
hooks, with Kerona ; another genus described under the name of Ceratidium,
horned anteriorly, but wanting both styles and hooks, seems to be only altered
or mutilated Keronce. On the other hand, Halteria appears to be included
by Ehrenberg among true Urceolaria, in his genus Trlchodina, although it
possesses none of the characters. The Keroniens are found in stagnant water,
fresh and salt." Perty has established a family Oxj-trichina, which, besides
containing two new genera, styled Mitophora and Stichotricha, excludes Cera-
tidium and Stylonychia, referring the species of the latter genus to Kerona.
After these exclusions and additions, Perty's Oxytrichina include Oxytricha,
Urostyla, Kerona, Mitophora, and Stichotricha.

Genus OXYTEICHA (XXV. 336, 337; XXIX. 21-24).— Styles, uncini,
and horns wanting. The body is soft, flexible, oval or oblong, more or less
flattened, and provided with cilia and setas. Their movements are foi-wards
and backwards, often by impulse, — creeping, smmniing, and climbing. In
all the species, digestive vacuoles are evident ; in five, (ova-like) granules ; in
four, a nucleus ; and in five, roimd contractile vesicles. Transverse and longi-
tudinal division is observed in 0. Lepus and 0. Fellio)iella ; longitudinal only
in 0. Cicada, and perhaps in 0. Pidlaster. The Trichoda Nasamomum and
T. uEthiopica (Ehr.) and Urostyla belong, in Dujardin's opinion, to Oxytricha,
and Oxytricha Cicada (Ehr.) to the Flcesconieus.

Whilst admitting a genus Oxytricha, Perty makes two di^^sions of it, the
one corresponding generally to Uroleptus (Ehr.), and the second to Oxytricha
(Ehr.). The differential characters given are: — a. Elongated posteriorly,
embracing most Urolepti (Ehr.) ; h. Eounded posteriorly, equivalent to O.ry-
tricha (Ehr.). Under the first division the species enumerated are 0. cmidata.
0. Piscis, 0. Muscidus, 0. amhigua, and 0. Lamella; imder the second,

OF THE OXYTRICHINA .

64*1

0. i>roteusa, 0. Pellionella, 0. rjihba, 0. QaUina, 0. Pullaster, 0. Lepiis ?, 0.
pUtystoma, 0. decumcma, and 0. fusca.

OxYTHiCHA rubra (Trichoda Piscis et
T. patens, M.). — Of a brick-red colour ;
linear in shape, plane on the imder side,
and_ equally rounded at the ends; pos-
terior end provided with sette. In sea-
water. 1-140".

0. PelUonella {Trichoda Pdliomlla, M.)
(xxEX. 21-24). — White, smooth ; slightly
depressed, equally roimded at both ends,
often broader in the middle; head not
sepai-ate ; mouth ciliated ; tail provided
■with setfB. Each animalcide has two
oval nuclei, and between them a single
round vesicle. When self-division com-
mences, four glands are developed ; and
then the vesicle divides. Elirenberg
counted ten cilia anteriorly, and four or
five setae posteriorly ; the anal outlet is
at the base of the setse. In infusions,
and throughout Switzerland in swampy
ponds along the snow-line of the Alps
(Pertv). Auerbach has seen it encyst
itself (Siebold's Zeitschr. 1854, v. p. 430).
1-720" to 1-280".

Cienkowsky simnises this species, 0.
ffibba, Stylonychia pustidata, and S. lan-
ceolata to be one and the same animal-
cxde in different stages of gi'owth and
under diflerent circumstances in respect
of food, &c. This notion is favoiu'ed, he
says, by the fact that the animalcule
which escapes from an encysted S. lan-
ceolata is exactly like >S'. 2}itstiddta.

0. caudata. — Smooth, white ; linear-
lanceolate in shape, rounded anteriorly,
attenuated posteriorly in the form of a
tail, which is provided with setse. Mouth
evident. In fresh and sea- water. 1-576"
to 1-84". (See Stylonychia pustulata.)

0.platystoina-=0. eurystoma. — White,

ovato-oblong, imder aide flat, with mar-
ginal setae ; mouth large and ciliated. It
swims with a revolving and vacillating
motion, and often upon the back. It
creeps upon water-plants, in standing
bog- water. 1-240".

0. qibha {Trichoda gihha et fcsta, M.)
(xxv! 336, 337). — White, lanceolate,
ends obtuse, middle enlarged, under side
flat, and ftmiished with tsvo series of
setae, and a lai'ge round mouth. This
species resembles 0. Pellionella, but is
distinguished by its setae, the two or
three contractile vesicles, and the nu-
cleus. This creature is active, and nms
nimbly along aquatic plants in fresh and
brackish water. (Fig- 336 an under
view, fig. 337 a side view.) 1-240". _ It
is not equivalent to the O. c/ihha (Duj.).

0. Pullaster { Trichoda Pullaster, Kerona
Pullaster, M.). — WTiitish, lanceolate,
ends obtuse, ventral surface naked at the
middle; the head, indicated by a con-
striction, is haiiy, like the tail. The
mouth naiTow. In water-butts, streams,
and infusions. 1-430". This form and
O. Lepus Perty believes to be mere va-
rieties of O. PelUonella.

0. Cicada {Trichoda Cicada, M.). —
Ovate, or almost hemispherical, back
fuiTowed and notched, under smface
flat. Upon the surface of stagnant
water. 1-1440" to 1-860".

0. Lepus. — Whitish, elliptical, smooth,
flat; ciliated anteriorly; provided -with
setfe posteriorly ; the mouth and dis-
charging orifices not distinct; and the
nucleus unobseiwed. In standing water,
1-540" to 1-96".

The following additional species are given by Dujardin

_0. iyicrassata. — Ovoid, long, coloiuless,
.fiinged posteriorly ^\dth rigid setae. Not
so long as 0. Pellionella, and, unlike it,
marine. In the MediteiTanean. 1-350".

0. Linyiia. — DiaphaTious, flattened,
flexible, elongated, rounded at each end ;
without setae or apparent cilia poste-
riorly; granules of surface in nearly
regular row.s. In ditch-water with Con-
fervac. 1-212".

0. aH?6)[(7«<«.— Colourless, oval, oblong
depressed in the middle, concave on one
side ; margin tumid ; vnth. very strono'
locomotive cilia on the concave surface,
and with rigid sette behind. In sca-
water. 1-350".

0. radians. — Discoid, red, surroiuided
by long radiating setaa. In salt or brack-
ish water. 1-520".

Perty hiings forward the following as new species, belonging to true Oxy-
tricha, charactciized by severally having a round posterior extremity : "

0. protcusa (Perty).— Very long, and longer than bvond. It i.s sometimes
subcylindrical ; nme to twelve times actually four-sided, with wide upper and

2 r

642

SYSTEMATIC JIISTOEY OP THE DTFUSOBIA.

under surfaces. Mouth a rather curved
and ciliated fissure. Cilia very fine,
those of the upper surface the more di-
stinct, although faint. Small specimens
are colom-less and transparent ; but larger
ones have dark gi-ey molecides or chloro-
phyll within. Movements tolerably ac-
tive. Perty once thought this species
and Trachelius strictus (Duj.) to be young
individuals of Sjiirostomimi, but he subse-
quently found examples 1-84" in leng th.

O. gallina (Perty) = TricJioda gallina
(?) (INIiiUer). — Anterior portion hyaline,
tiat, with lai'ge cilia; molecules grey.
Only once seen.

0. decumana (Perty). — Outline rather
irregidar; rather smaller in fi-ont than

behmd, broadest in the middle; ends
rounded ; upper sm-face slightly convex,
lower tiat. Mouth wide. It differs in
size from O. platystoma and in its out-
line both from that species and O. fmca.
In length it equals Uroshjla yrandis, but
is much broader. Bern, in ponds. 1-96".

0. fusca. — NaiTOw, elhptical, upper
surface convex, lower concave. Oral
orifice wide. Colour usuallv yeUo^vish
or blackish-brown. Lives m stagnant
and moiddy water. Cilia in front and
about the mouth sti-ongest ; but no uncini
occm- there. UrosUjla grandis differs
fi'om it by the uncini on its border.
1-160" to 1-84".

Genus CERATIDIUM (XXV. 338, 339).— CiHated, with horns on the
frontal region, but no styles or uncini. Little of their organization is known ;
and therefore their systematic position is uncertain. A power of not less
than 350 diameters is required to examine these creatui'es.

CERATrDiuM cuneatiim (xxv. 338,
339). — Body triangidar; front ti-uncated,
as also the two homs ; upper side smooth.
Ehrenberg found this whitish animaleide
in 1820, amongst Confervse, but had not

lately seen it. Dujardin believes it to
have been a mutilated Oxytricha. It
vibrates, rims, and climbs quickly.
1-430".

Genus KEROFA (XXV. 340, 341).— Cilia and uncini present, but no
styles. Body soft, flexible, oval, flattened, and eUiated, with claws (uncini),
and perhaps setae, on the under surface. Vacuoles numerous ; the oral (and
probably the anal) apertm'e is upon the ventral surface. One or more con-
tractile vesicles and a nucleus have been seen ; but self-division has not
been observed.

This genus, instituted by Midler, was at first adopted by Ehrenberg with
little modification ; but subsequently he transposed almost all its species to
his genus Stylonychia, on account of their possessing styles as well as uncini.
This can scarcely be considered a sufficient reason for the constraction of a
new genus; and accordingly Dujardin rejects StyhnycMa, and thus restores
the genus Kerona nearly to its original importance. As already noted, ho
lil^ewise adopts Kerona as the representative of his family Keronina. Perty
coincides with the French naturalist, and rejects both Ceratklhim and Stylo-
nychia, treating the species of the latter as examples of Kerona. He remarks
that Ehrenberg has very needlessly changed the name Kerona, given by Miiller,"
for that of Stylonychia.

The Keron'ai, thus understood, differ from O.vytricha only in the form of
their cuThi or processes, the base of which is commonly dilated in the form
of a transparent globe, and moveable withal, ^foreover they are equally
voracious, are abundant in stagnant water and infusions, and capable of
being much varied in form.

Kerona polyporum. — Whitish, de-
pressed, elliptical, and renifomi ; a series
of cilia suiToiuids the frontal region, ex-
tended from beneath the mouth. Ehren-
berg counted above forty vacuoles, many
of them filled with browniish (half-

digested gi-eeu) Monad.s. (xxv. 340 is
a back view, and 341 a side view,
climbing.) Parasitic on Hydra ndgan's
(Microscopic Cabinet, p. 7). Animals
infested with them die. 1-144".
This species is the iy^c of a genus named

OF THE OXYTEICIIINA.

643

Alastor in Perty's system, detached from
other CUiata hy reason of its parasitic
habits, and placed with Flag iototn a (Duj.)
and Ojxdina in a family named Cobaliua.

K. pmtulata (T)\x.y^ = Stylonychia pm-
tulata.

K. Sistno (Duj.) = jSX. Histrio.
K. Mytilm (Duj.) = /Sf. Mytilus.
K. Silurus (J)\i].) = St. Silurus.
K. lanceolata = SL lanceolata.

K. Cahitium (Miill.), K. Jimhriata
(Miill.), and Trichoda foveata and Tr,
Cumehis (i\Iiill.), are probabty, according
to Dujardin and Perty, mere varieties of
K. pustidata.

K. Pullaster (Miill.) is cited by Ehren-
berg as = Oxytricha Pullaster, but, as
Dujardin thinks, is only an imperfectly-
examined or a deformed specimen of
St. pmtulata.

Genus UEOSTYLA (XXV. 342).— Cilia and styles present, uncini want-
ing ; the cilia are thicldy disposed in numerous rows, and are longer near
the mouth. On the ventral sm-face, at the posterior end, is a small cleft,
provided with non-vibratile setse. Internally are numerous vacuoles, which
may be filled with particles of colour ; a nucleus, a contractile vesicle, and
delicate granules. Transverse self-division has been obsex'ved.

Uhostyla (jratidis (xxv. 342). — produced by the vibration of the cilia

White, semicylindrical, roimded at the
ends ; slightly enlarged anteriorly, hence
club-shaped ; styles short ; mouth large,
one-fomiih to one-third the length of the
body. It has long cilia on both sides ; the
discharging orifice has fi-om five to eight
little styles on the left side only ; sto-
mach-juice colourless. The young ani-
malcules are flatter than the old ones,
(xxv. 342, an under view with glands,
vesicle, and the cells tilled with Bacil-
laria and coloured matter. Cuxi'ents

about the mouth are also indicated in
the di'awing.) On slimy dead sedge-
leaves. 1-144" to 1-96". Perty doubts
the independent specific character of this
form, and woidd rather consider it a
variety of Oxytricha fiisca, or more pro-
bably of O. platystoma in a further deve-
loped state ; for Ehi-enberg admits that
the imcini at the posterior extremity are
small ; and if so, they can scarcely be
characteristic.

Genus STYLONTCHIA (XXV. 343, 344 ; XXVIII. 10, 74-76 ; XXIX.
18). — Ciliated, and armed with styles and uncini vaiiously disposed.

In one species Ehrenberg thought he had traced the coui'se of the alimen-
tary canal with its numerous digestive cells ; in the others, he found, coloured
food was received. Transverse and longitudinal self-di\ision occurs in two
species; transverse only in a third. In 8. pustidata, the formation of
gemmae is said to occur. Perty remarks that Ehrenberg, without any siiffi-
cient reason, has transferred many of the Kerona: of Miiller to Stylonycliia.
The granules and molecules are numerous, and often in heaps ; one or two
nuclei and a contractile vesicle are generally visible.

_ Stylonychia Mytdm ( Trichoda 3Iy-
tilus, Kerona Mytilus, M. and Perty)
(xxviii. 10). — White, flat, oblong,
slightly consti'icted in the middle, ob-
liquely dilated anteriorly in the fonn of
a mussel. The extremities are so trans-
parent that thcv give it the appearance
of being covered with a shield; but they
are soft, flexible, and ciliated. Dujardin
observes that the integumentary appen-
dages are very long, consisting of a row
of strong cilia in front, a series of uncini
and numerous styles behind. The line
of cilia leading to the mouth does not
reach the centre of the body. Its extre-
mities are so thin and flexible that they
yield before obstacles in their move-
ments, like the Plasaconia Patella. It

differs little from & {K.) ]msfulata, ex-
cept in size aud the strength of its super-
ficial proce.sses. The middle of the body
is sometimes filled with delicate white
granidos. (^ften, however, as Perty men-
tions, the animalcule is coloured green
with chlorophyll received in its food.
This animalcule generally has a peculiai*'
thrusting, forward-and-back movement'
but can climb, run, and swim nimbly'
usually with the back undermost. Ehr-
enberg found that a single animalcule
lived nine days : during the first twenty-
four hours it was developed by transverse
self-division into three animals; these
in twenty-four hours more formed two
each, in the same mnnuer; so that, by
self-division only (witliout ova), these

2t2

644

SYSTKMATIC HISTOai OP THE INFUSOHIA.

animalcules increase tliree- or fom-fold
in twenty-four hours, and may thus pro-
duce a million from a single animalcule
in ten days. An abundant supply of food
favours self-division. In infusions and
amongst Oscilltdoriee, Sic, in stagnant
marsh-water. 1-240" to 1-96".

S. pustulata (Trichoda Acarus, M. ; Ke-
rona pustulata, Duj.). — White, turbid,
elliptical or oval compressed, attenuated
at both ends, and having a band of un-
cini at the middle of the belly. Ehren-
berg has seen transverse and longitudinal
division, and the growth of gemmEe. In
infusions and stagnant marsh-water.
1-144". This species has been seen in the
encysted state by Stein and Schneider
(xxrx. 18). The white colom- is no cha-
racteristic, since it is frequently gTeen
from food received. Schneider (A. N. H.
2 ser. xiv. p. 328) observes that after
exclusion from their cysts thej' present
a remarkable resemblance to Oxytriclia
caiidata ; the posterior extremity in par-
ticidar is always bent round in the man-
ner represented by Ehrenberg. Pineau
calls this animalcule, in his history of a
transformation of Vorticella, by mistake
an Oxytriclia (see Ann. d. Sc. Nat. 1848,
ix.). Cienkowsky, however, regards both
this species and St. lanceolatu as phases of
existence of the same being as Oxytriclia
Pcllmiella and O. gihha.

S. Siluiiis {Trichoda Silums, Kerona Si-

lurm, M., Duj., and Pertv).— Small, white,
of the fomi of a mus.sel; cilia and unciui
rather long. In fresh water. 1-280".

S. appendicidata. — Elliptical, white,
small, and Hat ; cilia and styles long ; the
setfE disposed obliquely in fascicles. In
fresh water. 1-280".

S. Histrio {Paramecium Histrio, Ke-
rona Histrio, M. and Pei-tj'). — Elliptical,
white; middle slightly 'turgid, tei-mi-
nated anteriorly by a cluster of uncini ;
no sette. Ehrenberg states that the ab-
sence of the three posterior sets in this
and the following species is remarkable,
inasmuch as the others possess them.
Fission ti'ansverse. Amongst Confervse.
Dujardin is inclined to regard this as a
mere variety of S. {Kerona) pustulata.

S. lanceolata. (—Kerona lanceohfa,
Duj. and Pert^O (xxv. 34ii, 344).— Pale
greenish ; lanceolate in shape, extremities
equally obtuse, imder side flat ; it has a
cluster of uncini near the mouth, but no
styles. Ehrenberg saw in one specimen
a simple conti-actile vesicle on the left
side, below the mouth, and near it a
large oval gland. Green Monads and
Bacillaria maj' be seen in this voracious
animal, surrounded with colomdess sto-
mach-juice, (xxv. 343 represents an
under view, and 344 a side A-iew.j
Amongst Confervas. 1-144" to 1-120".
(See note on St. jntstulata.) Eucj'sted
state observed (xxvm. 74r-76).

Genus HALTEEIA (Duj.) (XXVI. 31).— Body nearly globular or turbi-
nate, surrounded by long, very fine, retractile cilia, which adhere to the glass,
and by their sudden contraction enable the animal to change its place briskly,
as if by leaping ; a row of veiy strong oblique cilia occupies the circum-
ference.

The type of tliis genus is Halteria Grandinella (XXVI. 31 a, b, c), called
by Ehrenberg Tricliodina, and placed by him ia the family Vorticclliua,
along with "species totally different. Dujardin, however, more correctly
refers them to the family caUed Keronina (see p. 640).

Genus MITOPHOEA (Perty) (XXVIII. 46, 47).— Body small, thicker
behind, having on one side a row of large cilia, and posteriorly a filament of
nearly the length of the body, and either with a simple or a slightly nodose
extremity.

MrroPiiOBA duhia (xxrai. 40, 47).— , the other. Movement sluggish, revolv-
Hyaline ; sometimes filled with green j ing. It lias some resemblance to Tri-
corouscles; with the characteristic vovf \choda pr<vccps {l<il.). 1-450".
of larger cilia along one side, and few on i

Genus STICHOTRICHA (XXVII. 43, 44).— Lancet-shaped, cylindrical,
elongated anteriorly and fiat ; mouth at this portion ; on one side an obhque
row of cilia.

STiCHOTnicuA scciimln (xxviii. 4-3, | molecules or chlorophyll-prains ; j^.vjin-
44) —Hynliue ; usually filled with grey i cb'ical or rather comprossod, roumU-d or

OF TD-K EUl'LOTlNA.

645

truncate behind. Cilia ou ventral sur-
face short, longer before and behind;
it swims rather actively, revolving at the

same time ; sometimes it crawls.
1-180".

1-240"

FAMILY XII.— EUPLOTINA ob EUPLOTA.

(XXY. 345-353 ; XXVI. 22, 30).

Loricated ; alimentary canal with two separate orifices, neither of which
is terminal. Organs of locomotion highly developed, similar to those of the
preceding family.

This family bears a general resemblance to the genus Asellm among the
highly- developed Entomostraca. Organs subservient to nutrition are di-
stinctly seen in thi'ee genera ; and one is remarkable by having a cylinder of
wand-like teeth, and a beautiful rose-coloiu'ed digestive juice. Eke that seen in
Nassula. Granules and a nucleus are found in two, and a contractile vesicle
in three species ; self- division, transverse and longitudinal, has been ob-
served in one ; but gemmtB are not produced. One form is green, the others
are colourless or whitish. This family comprises the following genera : —

With cilia
no styles.

Teeth
absent

' Tfiftf.lT f ^^^^ distinguished from the body Discocephalus.

Head not distinguished from the body Himantophorus.

^ Teeth present Chlamidodon.

With cilia, claws, and styles Euplotes.

This family Euplotina corresponds in part with that of the Ploesconiens
of Dujardin, which includes animalcules of an oval or reniform dejjressed
figiu'e, not contractile, but only slightly flexible, and invested with an appa-
rent shield (lorica), which, however, undergoes difflucuce like the softer
parts. Mouth furnished with vibratile ciha, and often also with cii'rhi, in
the form of styles or moveable hooks . They swim by means of the vibratile
ciha, or crawl by the aid of the other appendages.

The Ploesconiens are distributed into five genera : — Ploesconia and Chlami-
dodon, with a visible mouth, the latter also having teeth ; Diophrys and Coc-
cudina, without visible mouth: in the former the cirrhi or processes are grouped
at the two ends, in the latter they cover the under surface ; Loxodes has only
vibratile cilia.

The animalcules of the genus Ploesconia seem for the most part identical
with the Eujolotes of Ehrenberg ; but, as the identification is in some cases
uncertain, and as several new species are described by Dujardin, we shall
subjoin Plcesconia, as an appended genus, along with Diophryi^ and Coccudina.

Perty adopts the family Euplota, which he prefers to call Euplotina, and
also comprehends in it the Aspidiscina (Ehr.) and the Ploesconiens (Duj.).
Its genera are — Euplotes, Ilimantophoriis, Coccudina (Duj.), and Aspidisca.

Genus DISCOCEPHALUS (XXV. 345, 346).— Styles and teeth wanting,
but uncini present ; the head is also distingiushable from the body. The
organization is unknown, only the non-vibratile imcinated locomotive organs
having been specially observed, the characteristic species having been only
casually examined by Ehrenberg during his travels in the East The genu.s
therefore, must be hold a doubtful member of this family. ^ '

646

aySTEMATIC HTSTOET OF THE INFUSOIIIA.

DiscocEPHALUs rotatoHus (xxv. 345,
346). — Transparent; head smaller than
the body ; mouth rounded at both ends.

(xxv. 345 is an under-, and xxv. 346 a
side-view.) In the Ked Sea. 1-380".

Genus HIMANTOPHORUS (XXV. 347, 348).— Distinguished by the
absence of styles and teeth, by having numerous uncini, and by the head
not being distinct from the body. The long bent hooks, generally in pairs,
appear lilte a broad band upon the under side, and serve as organs of loco-
motion ; near them is a row of cilia extending from the mouth to the middle
of the body. The mouth, discharging orifice, and numerous vacuoles are
distinct. At the posterior margin is a large contractile vesicle ; between the
row of cilia and margin on the right is a series of glandular (?) spots. Self-
division has not been observed.

HiMANTOPHOBtrs Cluiron (M.) (xxv.
347, 348). — Transparent, flat, elliptical,
anteriorly slightly truncated obliquely ;
cUia short, uncini short and slender. The
mouth commences anteriorly, at the
lower angle of the triangular bright spot ;

but the true oesophageal opening appears ] amongst decayed leaves. 1
to be within the curved lorica, at the

end of the dorsal row of cilia ; the anal
opening is near the base of the last
cluster of four to six comb-like uncini,
which supply the place of styles, (xxv.
347 is a side-, and xxv. 348 an under-
view.) In stagnant water and ponds,

^ 180".

Genus CHLAMIDODON" (XXV. 349).— Ciliated mouth, provided with
teeth ; styles and uncini absent ; an oval transparent lorica or shield covers
the back, and projects around it; a margin of ciUa suiTOunds the body; they
are longer near the brow; short climbing setae probably exist posteriorly
between the cilia. There are distinct vacuoles, as also vesicles containing a
beautiful rose-colom-ed fluid ; the mouth has a hollow cylinder of wand-Hke
teeth. Internally are minute green granules and a large, oval, bright central
nucleus . . Self- division unknown .

Chlamidodon Ji/ie?nos?/M6' (xxv. 349).
— Flat, elliptical, sometimes dilated an-
teriorly, as shown at xxv. 349. It is of
a clear green or hyaline hue, with biil-
liant rose-coloiued vesicles; delicate
longitudinal lines are seen upon the sur-

face of the animalcule, and appear to be
situated on the lorica. Ehrenbei^ counted
sixteen wand-like teeth, disposed cylin-
di'ically. The movement is qiuck and
powerful, as in JEupIotes. With Zostcra
and Scytosiphon. 1-670".

Genus EUPLOTES (XXV. 350-353).— Locomotive organs highly deve-
loped and various, in the form of cilia, styles, and uncini, but teeth wanting.
Digestive vacuoles have been filled in four species with coloured food ; the
termination of the alimentary canal is indicated in one species by the dis-
charge, in the rest by the projection of the little shield ; the digestive juice
is colourless ; oval or round simple nuclei occur in three ; a single contractile
vesicle exists in five, and in a sixth two such. Self-di^^sion, transverse and
longitudinal, has been observed in one species, and transverse only in two or
fom- others. (See general remarks, p. 645 ; and Pl(esconia, p. 647.)

Perty makes the remark that some of the assumed species of Euplotes may
bo modifications of the same being, due to pressure between the glasses
during examination, since the so-called lorica is only relatively liaixJ. The
lorica has the form of a carapace or shield, covering only one surface, lca^-ing
the under one free. " The styles, which are trailed along, ai-e," says Lach-
mann, " split uj) at the apex into as many as eight parts in many species.—
e. f/. in E. Patella, in which, too, one stj'lo bears a number of small lateral
branches."

OF THE EUPLOTINA.

647

. EuPLOTES Patella. — Lorica large,
neai'ly circular, sliglitly truncated ante-
riorly ; mai'gin transpai-ent, broad ; back
elevated, gibboiis, and covered with a
few delicate smooth stiias. The mouth
is ciliated on each side ; the oesophagus
is near the side, below the middle line,
the discharging orifice behind the base
of the styles. With Lemme. 1-280".

E. Char 071 {Trichoda Charon, M.)
(XXV. 350-353). — ^Lorica small, ovate-
elliptical, slightly truncated anteriorly,
and having granulai' striae on the back ;
twenty to forty cilia were counted by
Ehrenberg, but no setae; a conti-actile
vesicle and one or more nuclei have been
seen. In standing water and infusions.
Schneider has seen it in the encysted
condition. 1-280".

E. striatus. — Oblong, elliptical, slightly
truncated anteriorly, micini only upon
the posterior part of the body; fom'
smooth striae upon the back. Fission
longitudinal. In sea-water, but, accord-
ing to Perty, also in freshwater ponds,
&c. 1-240."

E. appendiculatus. — Ovate-oblong, ends
rounded, provided vsdth oblique styles
and four straight setae upon the posterior

?art of the body. In fi-esh and sea water.
-240".

This, says Stein, is the Ploesconia lon-
giremis of Dujardin.

E. tnmcatus. — Oblong, with smooth
striae ; unequally truncated, and notched
anteriorly. It has setjB and numerous
uncini. The styles are straight. In sea-
water. 1-240".

Both this and the preceding, Perty be-
lieves to be phases of development of
E. Charon and striatus.

E. monostylus. — Elliptical, ends round-
ed, no sti'ise. It has a single style, like
a tail, but no imcini. In sea-water.
1-400".

E. amleatus. — Oblong, nearly square,
ends rounded; it has two crests upon
the back, one bearing a little spine in the
middle. In sea- and pond-water. 1-430".

E. turritus. — Smooth, neaily circular ;
it has a long erect spine on the centre of
the back. 1-600" to 1-4^0".

E. Cimex (^Trichoda Cimex, M.). — Ob-
long elliptical, and smooth, provided
with cilia, styles, and uncini. In sea-
water, and, says Perty, in fi'esh pond-
water. .1-430".

E. viridis. — Large (ample), oblong,
ti'uncate in front, with a central obtuse
tooth, dorsum flat; granides green.
1-480". Berlin.

E. affinis (Perty) = Ploesco?iia affinis
(Duj.).

E. suhrotundus (Perty) = Ploasconia
suhrotunda (Duj.).

Genus PLQ^SCONIA (Duj.). — Body oval, more or less flattened, enclosed
by an apparent lorica, marked by longitudinal ribs, furnished mostly on one
of its plane surfaces with scattered, fleshy, thick processes m tlie foz-m of
stiff hail's, or of non-vibratile hooks, yet moveable and serving the piu-pose
of feet ; on the other surface, with a row of vibratUe cUia regularly placed,
and becoming finer as they recede from the anterior towards the posterior
end, where the mouth is situated, and in the direction of which they vibrate.

" In my opinion," adds Dujardin, " a Plcesconia, notwithstanding its ap-
parent complexity of structure, is yet an animal as simply organized as those
previously considered — having a simple, fleshy, homogeneous substance, which
assumes during life a rather complex form, but loses it at the moment of
death, having no membrane or fibre to sustain it. The cilia or cirrhi, thouo-h
of varied form, are still of the same nature, and, I should say, of nearly the
same consistence. They have a moutli also, but no anus ; vacuoles arc formed
at the bottom of the mouth, as a result of an impulsive force produced by the
vibratilc cilia on the surrounding liquid, or they may be hoUowod out in any
part beneath the surface ; lastly, disseminated through tlie mass ai*e granules
varying in kind, and which I cannot admit as determinate organs nor as ova."

We much doubt the necessity of creating this new genus, since all or
nearly all, the species referable to it might be arranged with Eimlotes Stein
treats Ploesconia as sjTionymous with Euplotes (Ehr.), but would retain the
former term to designate a new genus represented l)y PI. Scutum (Dui )
species, indeed, which is marked by the French naturalist as a doubtfiil
member.

648

SYSTEMATIC HISTOKY OF THE INFUSOlilA.

It will be observed that Dujardin denies, as usual, the existence of an
anus ; this aperture is, however, generally stated to be found on the ventral
surface, near the posterior extremity.

Plcesconia Patella= Euplotes Patella
(Ehr.).

P. Vannus. — Depressed, oblong, oval;
very transparent, smooth, without striiB,
5 to 8 anterior hooks ; and 7 to 8 straight
styles behind. In sea-water. 1-218".

P. (?) Scutum. — Larger than the pre-
ceding, with the band of vibratile cilia
extending fm-ther backwards, and the
posterior styles inflected and sinuous.

" This species," says Stein (p. 158),
" differs fi'om the other Euplotes both in
having prehensile cilia (uncini) not onl}'
on the ventral smface, at the poste-
rior portion of the body, but also on the
dorsal sm-face, and in many other pecu-
liarities."

P. balteata. — Oval, rather nari'ower in
front, diaphanous, with 5 stiiaj (ribs) ;
the band of cilia extending five-sixths
the length of the body; stjdes few, feeble.
In sea- water ; no hooks, as m P. Vannus.
1-325".

P. Cithara. — Oval, with ten regidarly
disposed well-marked ribs; the row of
cilia semicircidar, extending two-thirds
its length ; styles not long, and almost
confined to the posterior extremity.
In stagnant sea-water. 1-290" to 1-275".

P. crassa. — Oval, oblong; thick, but
diaphanous, with some faint signs of ribs ;
the band of cilia little cui-ved, and ex-
tending one-half the length; 6 to 8 curved

styles at anterior, and 5 to 7 straight
ones at posterior extremity. With the
preceding, in sea-water. 1-362".

P. Clmron. — In-egularly oval, truncate
in front, naiTower behind, vdth well-
marked in-egular ribs; stjdes long, not
curved. Differs much from Euplotes
Charon (Ehr.).

P. affinis. — Differs from P. Charon, by
its habitat being in fresh water, and by
having its anterior portion naiTOwer,
whilst its posterior is more rounded and
less plaited.

P (?) suhrotunda. — 0\al, thick, gi'a-
nular within ; no distinct ribs ; truncated
and fissiu-ed in front; styles long, thin at
each end. In infusions. 1-535" to
1-475".

Perty found it imder the ice in a pond
near the Hospice of St. Bernard, and sug-
gests it to be no more than a variet}^ of
P. qffinis -with indistinct ribs (sti-ise).

P. (?) radiosa. — Longer than the pre-
ceding, 1-520" to 1-395", with long styles
radiating fi-om each extremity. In river-
water.

P. longiremis. — Very depressed, irre-
gularly oval, dilated on the side support-
ing the cilia, where it is more transpa-
rent, with 3 to 4 slightly prominent large
ribs ; styles numerous, verv long and
flexible. In sea-water. 1-400" to 1-306".

P. aculeata = Eiiplotes aculeatm (Ehi.).

Genus DIOPHEYS (Duj.) (XXVI. 22 a, 6).— Body discoid, irregular,
thick ; concave on one side, convex on the other ; with long styles grouped
at each end; no mouth.

DioPHBYs marina (xxvi. 22 a, b^. —
Oval, ^^nth. a longitudinal excavation;
teinninated in front by 5 great \'ibratile

cilia, and bebiud by 4 to 5 very long g^eni-
cidate styles. In sea-water. 1-580".

Genus COCCUDHSTA (Duj.) (XXVI. 30 «, 6,c). — Body oval, depressed
or nearly discoid, often rather sinuous on the margin ; convex, pitted or
granvUar, and glabrous above ; concave below, with %dbratile cUia, and styles
or hooks, serving as feet ; withoixt mouth.

Intermediate between Loxodes and Plcesconia, having the appendages of
the latter, and the general figure of the former. Ehrenberg has left tlio
Coccudince kno-\ATi to him dispersed among the species of O.vytriclia and
Euplotes. Aspidisca should probably be referred to this genus.

CoccuDiNA costata. — Oval, obliquely vibratile. In marsh-water and swampy

contracted, and sinuous in front ; convex ponds. 1-905".

and furrowed beneath, where from 5 to 6 C. cra.<isa. — Oval ; larger and appa-

very prominent tubercular ribs are found, rently truncated behind ; contracted and

supporting longcilia; niipciulngpsgroupecl ."(inuous in front; convex above, with

at each end; the anterior tliinner and Iceblv-markcd ribs : anterior appendages

OF THE ROTATOniA.

649

iu the form of hooks; posterior, of
sti-aight styles. 1-20". Marine, among'
corallines.

C. pohjpoda (xx^^. 30 a, b, c).— Oval,
sinuous in front ; convex above, and
marked with from 7 to 8 naiTOw ribs;
tlat below, and fmnished with numerous
long and flexible stjdes. In stag-nant
sea-water.

C. Cicada. — Oval, very convex above,
gi'anular, -without costffi ; margin round-
ed ; concave beneath, and there provided
with long and flexible styles. Appears
the same as the Trichoda Cicada of Miiller,
but not as its supposed synonym Oxij-

tricha Cicada (Ehr.), which is like the
Coccndina costata rather than C. Cicada.
1-812".

C. ( ?) Cimex = Stijlonych ia Cimex(Eh.v. ) .

C. reticidata. — A name pro^asionally
applied to an animalcide foimd in the
Seine, having a granular and reticulated
surface, and large styles at each end.
1-578".

0. crijstallina (Perty). — Hyaline, vdth.
from 6 to 7 long costse on the dorsum,
and very short cilia. Outline roimd. The
costiB are less elevated than in C. costata.
Wet moss and turf on the Alps. 1-900"
to 1-600".

OF THE GROUP ROTATORIA (p. 392).

(Plates XXXII.-XL., and part of XXY.)

Those animalcules which are included in the great division Rotatoria are
either destitute of a nervoiis system, or have merely an isolated ganglion
near the head, representing the brain, with a few nervous threads proceeding
fi'om it to the body. They have no pulsating heart, nor true blood-vessels in
which the blood circulates. The fluid apparently representing the blood
occupies the cavity of the body and bathes the external surfaces of the various
viscera, as in the lower Crustacea. The alimentary canal is tubular, variously
constricted at intervals, often divided into segments, each of which appears to
perform special functions. One segment, near the upper extremity of the
canal, is provided with a pair of moveable appendages, between which all the
food swallowed has to pass, and which may be regarded as teeth or jaws,
probably analogous to the gastric teeth of Crustaceans. In many species
there are ctecal prolongations of the stomach ; whilst the walls of the"organ ai-e
thick and cellular, having a glandular aspect. The alimentary canal is, with
some remarkable exceptions, furnished with an orifice at each extremity, or
mouth and anus, — the latter usually opening into a cavity termed the cloaca
or common outlet for the intestine, the oviduct, and the (so-called) water-
vascidar canals. The interior of the canal is vainously supplied with cilia
which arc in constant motion. The ca3cal and celhilar appendages are sup-
posed to be glandular ; but their functions, as well as relations to the liver
and other chylopoetic organs of higher animals, are doubtful.

The character and instruments of the respiratory functions in the Rotatoria
arc alike doubtful, but most probably they are performed by the water vas-
culai- canals. These ai-e two slender tubes (XXXVI. 6 e,_r/) springing from
the cloaca near the anal outlet, and proceeding upwards on each side of the
intestine towards the head, where they branch, and sometimes the two
anastomose, at others probably terminate in cuh-de-sac. These canals com-
mence at a pulsating organ (XXXVI. (3 v ; XL. 5), common to both, and
connected with the cloaca. In various parts of their course they are' fiu-
nishcd with pyriform appendages (XXXVI. 6 a) (tags) varying in number
from two to eight on each side. In the interior of each tag is a sino-lc
large cilium, which exhibits an incessant motion, resembling the flickcrinjr

650

SYSTEMATIC HI8T0EY OF THE IN FUSOHI A .

flame of a candle, and which most probably promotes the circulation of the
water contained in the canals. This water is apparently received from the
cloaca into the pulsating appendage, and from it transmitted to the various
parts of the tubular system, — a fact especially confirmed by Cohn's obsei-va-
tions on Brachionus militaris. Hence these water-vascular canals, with
theii- vibratile appendages, appear designed to convey streams of fresh water
to the interior of the animal, and thus, by exosmosis, aerate the fluid filling
the body of the animal, — the latter being continually di-iven to and fro during
the active muscular movements by which the creature alters its contour.

The Eotatoria are provided with a reproductive apparatus, the female
organs being remarkably large and conspicuous (XXXVI. 4/). In the
majority of species the latter is the only portion that has hitherto been dis-
covered ; but in several, male organs have been found on separate indivi-
duals, indicating the bisexual nature of the class — at least demonstrating
the dioecious character of some of the species, a feature which wiU probably
be found to characterize the entire family. The ovary consists of a very thin
bag of stractui-eless membrane (XXXVI. 4/), distended with clear fluid full
of granular molecules, amongst which are some cellular nuclei. The latter
successively attract around them portions of the granular fluid, thus forming
ova. In several species two distinct kinds of ova are produced by the same
individual, one being a true generative product, the other a modified ex-
ample of gemmiparous generation, and its gxowth independent of any sexual
process. The ovary communicates with the cloaca by means of a narrow but
dilatable oviduct. In examples of male animals that have been discovered,
there is a remarkable absence of all viscera, except the organs of reproduction
(XXXVI. 7, 8). Whether all the Rotatoria are dioecious, or whether some
are hermaphi-odite, the male organs having hitherto escaped detection, re-
mains to be ascertained.

The bodies of the Rotatoria, unlike those of the Polygastric Infusoria, re-
tain a determinate form, never developing external gemmae, nor dividing by
spontaneous division. Even on emerging from the egg, they possess all the
essential features of the matured animal (XXXVII. 16), neither passing through
a larval state nor being subject to metamorphosis like Crustaceans and Insects.
In the young animal some of the organs, especially the ciliated disks and
other external appendages, are imperfectly developed, but they undergo little
subsequent changes beyond an increase of size and definitiveness. Some
organs, as the red eye-spot, often disappear as the animal progi-esses to ma-
turity. The anterior extremities of the Rotatoria are furnished ydth. various
arrangements of the disks or bulbs supporting numerous cUia (XXXVI.
1 a and 4 a). These combine to form the rotatory organs, so designated from
the wheel-lilvc aspect which they present when fully expanded and with the
cilia in motion. Though destitute of true articulated limbs, some species (e.g. of
Melicerta) have appendages not unlike the palpi of Crustaceans and Insects, and
which are probably tactile (XXXVI. 18 ; XXXVII. 17 d). Many forms are
provided with a prolongation of the posterior part of the body, which is often
pointed (XXXVIII. 1), and with the articulations slipping into one another
like the joints of a telescope. This organ is sometimes furnished \dt\\ a
terminal disk (XXXVII. 17 b), and is used like the tail of the leech, as an
organ of attachment. In other cases the disk is wanting, and its place sup-
plied by one or two digital appendages (XXXVI, 4 employed as anchors ;
whilst, in swimming, tlic entire organ appeal's to become a rudder, regulating
the direction in which the animal moves.

The entire animal is invested by a thin pellucid membrane, which, from
its extreme tenuity and triinsparency, readily allows the exumination of the

OF THE EOTATORIA.

651

internal organs whilst the creatui-e is alive and the viscera fulfilling their
functions, — a circumstance that has even made these creatiu-es the favoui-ites
of the microscopic observer.

Modes of Observing the Kotatokia. — The magnifying powers most useful
in the examination of the Rotatoria ai'e those varying from 200 to 400 linear.
For watching theii- general habits, an object-glass of a half-inch focus,
which Avith an eye-piece giving a power of about 70, is ample ; but for ex-
aminiag their internal organization, one of about 300, having an object-glass
of fi-om one-third to one-sLxth of an iuch, is the most useful ; for the special
examination of more minute structui-al details, still higher powers are occa-
sionally, but not frequently, needed. We have already remai-ked that, from
the transparency of their bodies, the Rotatoria can be watched with much
ease, their iaternal organs being distinctly visible; and, as these latter are
often equally transparent with the general integument, their contents, and
the fimctions they perform, can be investigated with little difficulty. When
their general habits are subjects of investigation, it is obvious they must be
allowed much of the freedom enjoyed in their nattiral condition. Por this
piu-pose they may be introduced into a small phial of thin white glass with
a long narrow strip of similar material in its interior ; the latter being so
fixed as to be nearer one side of the phial than the other. A blade of grass
or one or two stalks of hay may now be introduced between the strip of glass
and the proximate side of the bottle ; these will attract the animalcules and
bring them within the range of the magnifying power. If the phial be now
filled with water containing the Rotatoria, they will soon find their way to
the vegetable matter, especially if the bottle stands for awhile in the sun,
with the side to which the plant is affixed turned to the light. The whole
may now be placed under the microscope and readily examined through the
lower magnifying powers. To some extent, the same object may be more
readUy attained by merely transferring small fragments of the half-decayed
vegetation floating in the water containing the animalcules, along with a
drop or two of the water itself, to a glass shde, covering it over with a piece
of thin microscopic glass. But in this case the movements of the creatiu-es
are less free, especially if they happen to be of the larger lands, such as the
Floscularice. These are often chary of emerging from their protecting cases
unless the coast be clear of all impediments. But the freedom of motion, so
important to the accui'ate observation of their habits, wholly prevents the
examination of their internal structure. Their perpetual gyration renders it
impossible to trace either the forms or relative position of the viscera ; con-
sequently they miLst be controlled. This may partly be accomplished by
introducing them between the glasses already recommended without the
intervention of any vegetable or other foreign substance. In this case care
must be taken to adjust the relations between the size of the thin glass
covering and that of the di'op of water. If the former be large and the latter
small, the chances are in favour of the animalcules being crushed. If these
conditions are reversed, their motions will not be sufficiently restrained
neither can tlie water bo preserved fi'om disturbance and vibration. Hence
care in hitting the medium of these conditions is essential. The smaller the
drop of water the thinner will be the fluid flhn when the protecting glass is
placed upon it, and the more effectually will the vagrant habits of the
creatures be controlled. Sometimes it becomes iiecessary to inpturc the
animals by further compression, even whilst under examination. The difti
cidty is to accomiilish this without forcing them out of the field of the instra-
ment. It may be accompliwhcd by means of a common sewing needle fitted
into a handle, by which pressure may be uppUcd gently but firmly to the

652

SYSTEMATIC HISTOKY OF THE INFUSOKIA.

thin glass. But this object can be still better attained by means of one of
the compressoria provided by opticians : the pressure being effected with a
fine screw, the movement can be regulated with the utmost nicety. Thus
the animal can be merely fixed ia its position, whilst its vital functions pro-
ceed without interruption. On increasing the pressure, we obtain increased
transparency by reducing the thiclcness of the animal ; and on can-jnng the
motion stiU further, we can ruptm-e the integument, when the viscera become
detached and discharged through the fissure. Thus their minute organization
can be more acciu-ately ascertained than when retained in situ. In some
cases the forms of the various viscera can be readUy ascertained from the
different hues which characterize them, but in the majoritj' of Rotatoria this
guide fails us. Consequently obsei-vers have long adopted a plan of feeding
the animals with brightly-coloured pigments, such as carmine and indigo,
which many of the creatures consume with avidity : a very small quantity of
the colour should be rabbed up with a Little water, as if for artistic purposes.
If the live-box be used in examining the creatures, with the water contain-
ing the animalcules a little of this colour must be mixed prior to the cover
being placed upon them. But when a common glass sUde is employed, it
generally suffices to dip a camel's-hair pencil into the diluted pigment and
apply it to the edge of the thin glass. The colour usually flows between the
glasses, and diffuses itself through the water sufficiently to answer every
purpose. Two objects are now attained. The minute coloirred particles are
thi'own into active motion by the ciliary movements of the trochal wreaths,
beautifully demonstrating the force and dii-ection of the aqueous vortices set
up by the animalcule ; and by noting the direction taken by such of the
particles as are swallowed, the position of the mouth and oesophageal canal
can be traced. These particles usually accumulate in the stomach, distend-
ing its parietes ; and as the bright coloiu" of the pigment contrasts strongly
with the transparent walls of the viscus, its size, form, and position, as well
as the structure of its walls, can be readily made out. By prolonging the
observation, the same agent enables us to ascertaia the direction of the
iutestine, anus, and cloaca, — since, when the stomach becomes inconveniently
full, the creature usually everts the cloaca, brings the anal orifice into contact
with the surrounding fluid, and suddenly empties the stomach or bowel of its
contents.

There arc practical disadvantages attending the use of carmine and indigo,
some of which Mr. White appears to have overcome by substituting the red
pigment which lines the coi-nea of the eye of the common house-fly (Microsc.
Journ. ii. p. 282). By means of a finely-pointed knife, or sharjj-cdged needle,
the large cornea can easily be detached fi'om the head of the insect ; whilst
a small, stiff camel-hair, or (stUl better) a small sable pencil suffices to wash
the pigment out of the internal concavity of the detached cornea.

It is occasionally desirable to examine the animals by reflected instead of
transmitted light, in order that their true coloiu's maj' be exhibited, as
Mr. Gosse has pointed out in the instance of PhUodina citrina.

Localities foe Rotatouia. — These are exceedingly divcreified, varying
from the wide ocean to the dried-up sediment of the water-spout. There
are few circumstances under which water exists, in which Rotatoria may not
be found, though they dislike it when its contents are imdergoing decom-
position. Consequently, though they occiu- in all vegetable infusions, they
are only to be found when the first stage of decomposition lias passed away,
and they usually disappear again when the water becomes putrid and offen-
sive. After the Monadina, Faramecia, and other smaller Infusoria have run
their course, and in large measiu-c disappeared, the Kottitoria occupy thorr

OF TUB aOTATORIA.

653

places, — a circumstance that has led some observers to suggest the probability
of some of these lower forms being the larval states of the higher ones— a
view now known to be erroneous.

Some species, especially the Rotifer vulgaris, are common wherever water
has remained for a little time ^vithout distui-bance, in cisterns, depressions
in the gutters of houses, saucers of flower-pots, and similar situations. A
few forms have been found in the interiors of vegetable cells. Thus Rotifer
vulgaris occurs in the leaf-cells of Sphagnum, and in the clavate branches of
Vaucheria, feeding upon the contained chlorophyll. Notommata parasitica
and N. petromyzon, found within the spheres of Volvox glohator, in lilce
manner consume the little masses of green protoplasm ; whilst Notommata
Werneckii, like the Rotifer, occurs in the cells of Vaucheria.

They often abound in the damp moss from the neighboiu'hood of bogs,
streams, and waterfalls. But, besides these special situations, some of them
are to be found in almost every ditch and pond in which Lemnae, Confervae,
and other decaying masses of vegetation abound. Sometimes they play round
the plants with iacessant action, pushing their slender bodies into eveiy
recess in which food may hu'k, then bacldng out again as cleverly as any of
theii" larger aquatic companions can do with fin and tail, — now anchoiing
themselves to some projecting point by means of their flexible pseudopodia,
drawing in theii' trochal disks with apparent alarm if any other creatiu'e
brashes past their resting place with unmannerly rudeness ; then, forgetting
their fears, they again evolve their ciliated wheels, loosen from their anchor-
age, and launch away into the clear stream, displaying the varied modes of
progression so characteristic of difierent species. But it is only some of
the forms which indulge these vagrant habits. The higher forms, such as
Limnias, Melicerta, Floscularia, Lacinularia, and Stephanoceros, are quiet
stay-at-home matrons, at least after sowing the wild oats of their youthful
days. For a short time only after leaving the ovum do they roam wild and
free. They soon settle down, attaching themselves by their false feet to some
fixed resting place, where they spend the rest of their lives in sober tran-
quillity. These home-birds must be sought for amongst the stems and leaflets
of Ceratophyllum, Ohara, and the water Ranunculus, more frequently occui'ring
in the clearer streams and ponds than do many of their smaller allies.

Unlike the Monadina and other lower Infusoria, the Rotatoria rarely occur
in such profiLsion as to coloiu- the water. It is occasionally rendered tiu'bid
and milky by Brachionus Palea, which, in such cases, occurs in vast profusion.
Brachionus urceolaris and B. rubens sometimes present the same conditions.
Typhlina viridis, foimd by Ehrenberg in Egypt, coloured the water green.
Lacinulana forms small transparent gelatinous masses. Limnias annulatus
occasionally studs the leaves of water-plants in such number as visibly to
clothe them in russet broAvn ; and groups of ComcliUus Volvo.v appear in
small clusters, adherent by the extremities of their pseudopocUa, like a group
of tadpoles dipped in coloiu'less jeUy, from which they can protrude their
heads or retract them at will; but sociality does not usually characterize
the Rotatoria as it docs Eagle.na and similar forms. It is only when the
parasitic species have taken possession of some remarkably favourable
locality that they so abound as to affect the aspect of the plants on which
they dwell, and thus force themselves on the attention of the observer
Usually they must be sought for in a systematic way, without anv extemai
indications whether a pool will prove productive or bai-ren. Wc have how-
ever, rarely been disappointed on examining the green and foul-lookin<^
drainage from the manure heap in the farm- yard. Amidst its swarms of
Euglenm we have usually found a rich supply of Rotatoria. The tme micro

654

SYSTEMATIC HISTORT OF THE INFUSORIA.

scopist must not be afraid of soiling his hands, or have a weakness for kid
gloves. Some few Rotatoria assume the habits of Entozoa. Alberiia ver-
micularis was found by Dujardin in the abdominal ca-sitics of the earthworm
and in the intestine of Limacina ; whilst Alhertia crystallina was discovered
by Schultze in the intestine of Nais littorulis.

Capture of Eotatoeia. — The modes of capturing the Rotatoria must vary
with the species sought, as will be evident from the remarks made in the
preceding section. The simplest mode of obtaining the majority of the foims
is to coUect a quantity of Confervfe, Lemnae, or the half-decaying masses of
the different pond-weeds, filling the vessel with water from the pool in which
plants were growing. We have usually found the shallow margins of the
pond most productive. On reaching home, the vegetable mass must be well
stirred up in the water, in order to detach the animalcules from the plants to
which they cling ; and, before they have time to re-attach themselves, the
water must be poured off into another vessel, thi'ough a piece of muslin or
very fine net. All the coarse material is thus got rid of, nothing passing
through the strainer but water rendered turbid by fine particles of half-
decayed vegetation suspended in it. But along with these vegetable atoms
the Rotatoria will also pass into the receiving vessel, which must be allowed
to stand for a while, allowing the sediment to sink to the bottom, where
it will be followed by the animalcules which find nutriment in the half-
decayed mass. A small portion of this sediment may now be taken up by
means of a narrow glass tube, one end of which must be introduced to the
bottom of the vessel, whilst the opposite one is closed by the finger or thumb.
On removing the latter, the sediment rushes up into the tube ; and if the
upper end of the tube be again closed as before, the contained material can be
transferred to the live-box or the glass slide. If the tube be held for a few
moments in a vertical position, the upper part being still closed with the
finger, the vegetable matter and its accompanying animalcules will sink to
the lowest part of the water ; consequently the fii'st di'op escaping from the
lower end of the tube will usually be richer than those that follow. If the
drop be received upon a glass slide, it must be covered over with a piece of
thin glass, when it is ready for the microscope, and, unless the pond has been
uncommonly barren, the instrument 'ndll reveal a rich harvest of Algae, Con-
fervEe, Desmidieae, Diatoms, and Polygastrica ; whilst amongst aU these the
Rotatoria wiH be found sailing from point to point, exploring all the recesses
between the vegetable fragments, — now quiescent, as if contemplating the
contents of the larder, then, as if dissatisfied with the prospect, sailing away
to some more promising pasture. But when a tempting nook presents itself,
this restless locomotion ceases, and they attach themselves to some fixed point
either by means of a disk-Hke foot or by using its terminal joints as an anchor,
— their trochal disks being for the time dra-mi in, and comfortably lodged in
the anterior part of the body. Its position being fiiirly secured, the animalcule
evolves its wheels, at first slowly, but soon increasing theu- speed. A violent
commotion amongst the atoms abounding in the water soon indicates the pro-
duction of a miniature whirlpool, which biings a continuous sti-eam of edible
matter within the reach of the hungry traveller. But, though hiuigry, he is
a dainty gentleman, and chooses to select liis fare. The bulk of what is
drawn towards him by the vortex he has created, not suiting his taste, is
suffered to flow by, in a continuous stream, like that left by the rocket in its
flight. But everything is not thus allowed to pass : the teeth-like jaws of
the animalcule are constantly plaj-ing against each other with desperate
energy, whilst sudden jerka and contractions indicate that the animalcule has
made a capture ; and though it is not always eti-sy to see his prey pass do^vn

OF THE ROTATOKIA.

655

his giillet, the gradual expansion of his stomach proves that he is not labour-
ing in vain. The Monads find to theii- cost that he is a real Triton amongst
the minnows.

Another mode of capturing similar forms is by employing a small net, of
veiy fine muslin fii-mly fastened to a ferruled hoop of brass or iron, a few
inches in circumference, and capable of being fitted to a walking-stick or
fishing-rod. It has been recommended that the exterior of this hoop should
be grooved, so that nets of various degrees of fineness can readily be employed
— these being attached merely by means of an elastic ring of vulcanized
indian-rubber, di-awn over them and fitting into the metallic groove. By
means of a net of this character, the central and deeper parts of a pond can
be searched, as, if the gauze be sufficiently fine, the net will retain the larger
Eotifera, whilst the water passes freely thi'ough it. After making a succes-
sion of sweeps through the pond, the net may be everted into a receiver con-
taining clear water, and with a little manipulation the animalcules adhering
to it may be washed into the vessel. By means of the same net the fluid
may be concentrated until at length the rich products of an home's fishing
may be carried home in an oimce phial. But the muslin must be very fine,
or the richest of the game will escape. When the large and exquisitely
beautiful Floscularian Botatoria are the objects of search, a different method
must be followed. It is but occasionally that they can be met with ; conse-
quently the student must be prepared to give time and labour before he
succeeds in discovering these lovely objects ; but they are weU worth the
price. As before observed, Melieerta, Stephanoceros, and similar forms ai'e
found attached to the slender stems and subdivided leaves of Ceratophyl-
lum, Myriopliyllum, Ranunculus aquatilis, the Charce, and similar plants.
The method of search which we have found the most successful has been to
carry with us to the field a narrow phial of clear white glass or a chemist's
test-tube, into which portions of such plants as a pond may contain may be
introduced along with a little clean water. The unaided eye, when experi-
enced, soon ascertains the presence or absence of the objects sought for ; but
the search may be further facilitated by means of a pocket-lens of low
magnifying power. If, after selecting several fragments drawn fi-om different
parts of a pond, these do not reveal traces of some of the Flosculaiians, it is
probable they do not exist there, and we may proceed to some new fishing-
groimd ; but if an isolated individual be detected, every clump of aquatic
vegetation in the pond should be carefully searched ; for, as is the case with
Volvox and many other microscopic organisms, there will be found in some
part of the water a colony where Malthusianism has no place, and to M'hich
the isolated individual fii'st found bears the same relation as the trappers and
backwoodsmen of the west do to the swarming communities of Boston and
New York.

One remarkable circumstance must be borne in mind by the animalcule-
hunter. If he happens to remember a pond where some rare species
abounded last year, let him not again turn thither in search of it as the
chances will not be in his favour. These creatures rarely exist in the same
water during two successive years. The reasons for this are not easily ascer-
tainable. The remark is equally applicable to Volvox and the Desmidieie
The search -sviU be most productive if prosecuted on new ground. It may be
remarked that the Floscidariun Botatoria are usually discovered accidontallv
rather than by predetermined search. Respecting the marine Rotatoria but
little IS kno^v^l. The class appears to have but few representatives in salt
water, contrasted wth tlieir abundance elsewhere. Nevertheless some mav
occasionaUy be observed whUst examining corallines and seaweeds under

656

SYSTEMATIC HISTORY OP THE INFU80KXA.

the microscope, aroimd which objects they play after the fashion of their
freshwater allies. In the ocean we have few or no countei-parts of the
stagnant pools found on land ; those dark holes on rocky coasts, the homes of
the Actinice and the seaweeds, which would otherwise represent ponds and
ditches, are too constantly distm-bed by the tidal wave to admit of the accu-
mulations of decaying vegetation so favoui'able to the existence of the fresh-
water species.

Classification. — The exact place which the Rotatoria should occupy in
the zoological scale is as yet undetermined, since discordant opinions are
entertained on the subject by some of our most eminent naturalists, as ynR
be seen by a recurrence to Part I. of this work (p. 392). The question can
be decided only by a careful study of their development as compared with that
of other animals. Most inferior creatures are the permanent representatives
of conditions which are merely transitional in the advance from the ovum to
matuiity of some higher form, — the former beings obviously occupying a posi-
tion subordinate to the latter, inasmuch as they never advance beyond a state
which only occiu's in the higher animal in its immatui-e and imi^erfect con-
dition. The Myriapod and the "Worm, with theu- strongly-marked vegetative
repetitions of parts, obviously find a temporary representative in the crawling
caterpillar, but not in the fully-formed winged insect of which the caterpillar
is but the rudimentary larva. Consequently the Worm and the Myiiapod
must alike be placed below the Insect, if we arrange animal forms in a hnear
series according to their development. Supposing this method of ascertaining
the true zoological position of any class of animals to be correct, the question
naturally arises, what larval states of other animals are most closely repre-
sented by the permanent forms of the Rotifera ? It is clear that the Rotifera
have little affinity with the Polygastric Infusoria ; for, though the family of
VorticeUina amongst the latter animals seems to constitute a sort of inos-
culating hnk, the afiinity of the Vorticellce. to the Rotatoria appeal's to be
rather one of resemblance than of relationship. The histoiy of the Vorticellce,
as worked out by Professor Stein, reveals morphological changes wholly dis-
similar from what occui's in the Rotatoria, amongst which the eneysting-
process, so characteristic of the Vorticellce, has no place. This process is
obviously one of the phenomena of development by gemmation which is most
prevalent amongst the lower animal forms, and becomes less frequent as we
ascend, until, amongst the higher classes, it never occurs. In ascertaining the
relation of the Rotatoria to the Vorticellce, it is neccssaiy to inquire how far
this reproduction by gemmation, as distinct from sexual reproduction, has
any existence amongst the former animals ; and this is precisely the question
which we are as yet unable to answer. It has been suggested that, of the
two forms of eggs known to be produced by some Rotatoria, one group con-
sists merely of buds encased in a shell, whilst the others are the trac sexual
products ; but such eminent observers as Professor Huxley and Dr. Colm ai-e
at issue as to which of the two kinds of ova are to be respectively regarded
as true eggs or as gemmro. Dr. Cohn contends that the bodies ordinarily
regarded as eggs are merely gemmas thrown off from the organ believed to
be an ovary, without any fertilization by a male animal, — thus accoiuiting
for the extraordinary profusion in which these eggs are developed, whilst so
many obsei-vers have been baffled in their attempts to discover spennatozoa
or any male organization. The mode of development which Professor Huxley
observed in the ova of Lacinularia, and Professor Williamson in those of
Melicerta, are not incompatible with the idea of theu- being gemma3, and
the ovary a gemmiferous stolon. Sujiposing all this to be true, we have,
in the formation of llieso slielled goinmio. an analogue to the development of

OF XJELE liOTATOUIA.

657

the Vorticella-hwdia from the Aoinetal condition of the Vorticellce ; but the
encysting of the entire body of tlie latter animal, and especially its resolution
into a multitude of geramules, finds no parallel amongst the liotifera ; hence
we cannot regard the two classes of animals as having any close afSnity to
one another.

Professor Owen removes the Rotatoria from the Cuvierian group of Radiata
and places them amongst the Articulata, in close alliance vsdth the Crustacea.
This idea is a plausible one, and has several supporters. But here we are
met by the fact that all the Crustacea, not excluding the Cii'ripeds and the
Entomostraca, pass through a lai-val condition, resembling which, notwith-
standing the assertion of Leydig, nothing has hitherto been observed amongst
the Rotatoria ; whilst the latter cannot be regarded as having any resemblance
to the larval conditions of these higher Crustaceans in any stage of their
history. Professor Huxley's suggestion, that they are the peimanent repre-
sentatives of the larval forms of his group of Annuloida (including the Echi-
noidea, Annelida, Trematoda, and Nematoidea), appears to have many facts
in its favour, since it connects them with the articulate division of animals
without raising them to the level of true Cnistaceans. Burmeister and Leydig
hold similar views to those of Owen respecting the close relation existing
between the Rotatoria and the Crustacea. Leydig dwells especially upon
their external figure, the frequently hardened lorica, the existence in their
bodies of striped muscular fibre, their nervous system, the anatomical and
physiological phenomena of their sexual Hfe, and, lastly, the supposed fact
that the young, at its liberation from the ovum, has not the form of the
adult animal, and consequently must imdergo a metamorphosis. These argu-
ments, when examined closely, afford feeble support to Ley dig's opinion.
External form is an unsafe criterion of zoological position. Were it ti-ust-
worthy, it would biing the Rotatoria nearer to the cilio-brachiate polypes
than to the Crustacea. The hardened lorica is nothing more than a modified
exo-skeleton, which is as fully developed in the Echinoderms as in the
Crustaceans ; whUst in the majority of the Lerneadae (the section of Crus-
taceans to which Rotatoria bear the closest affinity) this hardened integument
I is wanting. The existence of striped muscular fibre proves nothing, since
Mr. Busk long ago discovered this structure in some of the Acalephag. The
nervous system of the Rotatoria is as yet so imperfectly understood that little
reliance can at present be placed upon our knowledge of it ; besides which, as
Professor Huxley has pointed out, a similar condition to that of the supposed
nervous system of Rotatoria exists in Turbellaria ; and, lastly, the pheno-
mena of sexual life amongst the Rotatoria are as httle iindcrstood as is their
nervous system. The few instances in which male animals have been found,
present some resemblance to the phenomena seen amongst the Lemeadas ;
but the subject is equally involved in obscurity in each of the two classes of
sreatures, whilst Leydig's assertion, that the young Rotifera undergo meta-
norphosis, appears entirely erroneous. The only facts positively determined
Jidicate that nothing of the kind takes places amongst them, whilst all the
crustaceans, including the Lcrncadce, undergo repeated moults before reachino-
naturity, °
We forbear enlarging on this question of the zoological position of the
lotatoria, as it has already been discussed in much detail in the first part of
his work (p. 468 et seq.).

The most philosophical mode of subdividing the Rotatoria into families
» almost as undetermined as their zoological affinities. Ehrenberg, who
5d the way in this work of classification, based his primary "roups
pon the number of divisions and form of the ciliated trochal wrcatir, subl

2u '

668

SYSTEMATIC HI3T0UY OK TUK INFUSOttlA.

dividing each division according as the animals composing it were loricated
or illoricated.

The following table represents his classification : —

With a simple continuous
vrrcath of cilia (Mono- -

trocha).

Margin of ciliated wreath
entire (Holotrocha) ...

Illoricated ... Ichthydina.
Loricated CEcistina.

Margin of cUiated wreath f Illoricated . . . Megalotrochjea.
lobed or notched (Schi- \

zotrocha) [ Loricated Floscularisea.

With a compound or di-
vided vsreath of cilia -
(Sorotrocha)

' With the ciliated wreath [ Illoricated ... Hydatinsea.
divided into several <

series (Polytrocha) | Loricated Euclilanidota.

With the ciliated wreath f Illoricated . . . PhUodingea.
divided into two series-!
^ (Zygotrocha) [ Loricated Brachionasa.

N.B. This classification is given more at length at p. 478.

Siebold adopts the classification of Ehrenberg for the Rotatoria, omitting a
few genera. Dujardin, on the contraiy, regards the principles employed by
the great Prussian microscopist in framing his division of these animals as
faulty and uncertaiu ; consequently he puts forth a classification of his own,
substituting the name of Systolides for the better known one of Rotatoria.
He admits four primary divisions of the class, vi^;. —

1. Those Rotatoria which live fixed to some foreign body by their posterior
extremity.

2. Those which employ but one means of locomotion, using their vibratile
cilia as instruments, and being always swimmers.

3. Those which exhibit two modes of progression, viz. SAvimming and
crawling, after the manner of leeches.

4. Those which creep by nncini, and are destitute of vibratile cUia.

The first of these groups includes only his Flosculariens and AEelicertiens.
The second contains by far the largest niunber, and is subdivided into two
secondary groups, in one of which the animals have an integument whoUy
flexible, whilst in the other they have some part of it soUd, constituting a
lorica or shield. The third section contains only his family of Rotifera,
closely corresponding with Ehrenberg's family of Philodinjea ; whilst the last
comprehends the Tardigrada. These ciuioiis animals are now known to have
no affinity with the Rotatoria, but belong to the Ai-achnida, or class of spiders.
Indeed, at the time of pubUshing Ids book, Dujardin expressed doubts as to
the propriety of uniting them with the Rotatoria.

Leydig i}roposes a new classification of the Rotatoria, or as he terms them,
in accordance with his views respecting their nature, Cilio-crustacea, which
he arranges " according to theii- forms — whether they are cj-lindiico-conical,
sacciform, or compressed, together with which, as further chai-actera, the
condition, presence, or absence of the foot may be employed."

He adopts three primaiy divisions : —

A. Figm-e between clavatc and cylindrical.

B. „ sacciform.

C. „ compressed.

OF THE liOTATOKIA.

659

These he again subdivides as follows : —

^1. With elongated, transversely-ringed, attached foot.

2. "With elongated, jointed foot, retractile, like a telescope.

3. With elongated, jointed, non-retractile foot.
A.<( 4. With short foot and long pedal forceps.

5. With short foot and pedal forceps wlaich are of equal length with, or
somewhat shorter or longer than the foot.

6. Without foot.

B.

1. Foot short.

2. Foot absent.

f-n .14! i,j jfl- Witb a foot.

^ I a. Depressed fi-om above downwards | ^ ^^^^ ^^^^^^^

[ b. Laterally compressed.

It will be seen that the classifications of Ehrenberg, Dujardin, and Leydig
agree in one feature : they axe more or less artificial, being based upon
pecuharities of external form and habit rather than upon internal organiza-
tion. The subdivision of the trochal wreath varies in its extent with the
age of the animal, the depth of its sulci increasing with the approach of
maturity ; consequently the defectiveness of Ehi'enberg's system becomes at
once obvious. No such changes as we have just referred to affect the internal
viscera, except in a minute degree ; consequently the latter alone, when
thoroughly understood, can fiuTiish the true materials for a philosophical
classification. But unfortunately we do not as yet possess such a number of
accurate observations as admit of our an-anging the various species on this
higher basis. For example, the Rotatoria are either monoecious or dioecious :
a few have been demonstrated to belong to the latter class ; but of the vast
majority we are unable to say which of these two featm-es characteiizes
them. The behef in their monoecious natui-e has until recently been general ;
but the possibility of their being aU dioecious now suggests itself. Should
fiiture observations establish the fact of some Rotatoria being monoecious
and others dioecious, the distinction will be one of paramount importance
as a basis of classification. But of the internal organization of the vast
majority of these animals we unfortunately know little or nothing. A
very small number even of the higher forms have been submitted to rigid
(md accurate scrutiny; consequently the want of material for a natui-al
dassification, based on anatomical and physiological data, compels us to fall
back upon such as are artificial. (See Part I. p. 477 for additional remarks
on classification.)

The relative value of the three systems of Ehrenberg, Dujardin, and Leydig
will be a disputed question. Where the purpose to be accomplished is merely
the provision of an index (and artificial systems can be little more), the clas-
sification in which the distinctions are most readily recognized will best fulfil
its purpose. On these grounds we think there is little room for choice be-
tween those of Ehrenberg and Dujardin. The two primaiy sections of the
great Prussian naturalist are easily recognized, his four piincipal subdivisions
almost equally so ; and the ultimate division of each group into a loricated
and an illoricated series not only facilitates the investigations of the young
student, but is an element in Dujardin's system, who, by adopting it, re-

» ^cognizes its value. At first sight Leydig's classification would appear to
approach nearer to a natural system than either of the others enumerated ;
but close examination docs not confirm this impression, since, in order to
arrange the objects in their respective groups, such genera as Diglena, Fitr-
2 TT 2

660

SYSTEMATIC HISTOET OF THE INFTJSOHIA.

cularia, and Notommata have required to be subdivided, part being thrown
into one subdivision and part into another. Objects which present such close
resemblance as to be capable of arrangement in one generic group can scarcely
be so diverse as to justify their separation iato different famihes. The de-
tachment of the fifth section from the fom-th, merely because its individuals
are furnished with short pedal forceps, would furnish a precedent for classi-
fying birds and quadrupeds according as they have long tails or short ones.
These reasons have led us to retain the classification of Ehrenberg for the
present, since the advantages afforded by the two newer systems do not seem
sufiiciently great to justify our abandoning the general plan followed in the
previous editions of this work. At the same time we are fully ahve to its
imperfections, both in its piinciples and detaUs. Leydig's objection to Ehren-
berg's employment of the term lorica is a substantial one, since it is stretching
the term beyond what is admissible, to apply it to the delicate investing
membranes of Floscularia and Stephanoccros, or to the gelatinous envelope of
Conochilus. Consequently, though for reasons already advanced we retain
the subdivisions of the Prussian microscopist, we extend his definitions of his
third series of groups : instead of defining them as" loricated," and "iUoricated,"
we would describe them as "loricated, or usually provided with a hai-d
investing layer," and " illoricated, or unprovided with a hardened investing
layer."

Leydig's objection, that such animals as Ehrenberg indicates by the tenns
Polytrocha and Zygotrocha have no existence, is ill founded. There is no
question that the ciliated lobes of the head are divisible and distinct in a
large number of species ; and being so, they become as good characteristics of
families as do Leydig's long or short pincers to the foot.

FAMILY I.— ICHTHYDINA.

Rotatoria with a single continuous rotary or'gan, not cut or lobed at the
margin ; destitute of lorica or indurated integument. In Ptygura and Gh -
nophora the wheel-like organ is in the fonn of a circle, and is an instnmient
of locomotion. In the other genera it is long eUiptical, and on the ventral
surface. Ohcetonotus and Ichthydmm have each a forked foot-like process,
and the rest of the genera a simple one. A long simple alimentaiy canal,
with a long oesophagus, apparently without teeth, occui-s in duetonotus and
Ichihydium. Glenopliora has a short oesophagus, with two single teeth ; and
Ptygura an elongated stomach and three teeth. Glands are seen only in
Chcetonottis and Ptygura. No caeca exist in any of the genera. The male
reproductive organs, not hitherto discovered ; those of the female consist, in
Ptygura and Ichthydlum, of a large ovaiium containing one or more developed
ova. The two red eyes seen in Glenophora are supposed by some to indicate
the existence of a nervous system as yet undiscovered.

Ehrenberg's classification of tliis family -will be found in p. 478 of the
General Histoiy. It is probably the weakest which Ehrenberg has esta-
blished, being admitted neither by Dujardin nor Leydig. Dujardin does not
recognize the genus Glenophora, neither does Siebold, whilst Leydig rejects
both it and Ptygura, regarding them as immature foi-ms of some other
species. Ptygura especially, the latter writer suggests, may be the young
Mdicerta ringens ; but this idea Professor Williamson's observations have
shown to be erroneous ; consequently the genus must be retained until its
immature condition is bettor established than at present. Dujardin coni-
proliends Ptygura in his family of Meliccrtiens, whilst he rejects Ichihydium

OF THE ICHTHYDINA.

661

nnd Chcetonotus from amongst the Rotatoria, believing them to be Polygastric
Infusoria, — a conclusion with which we are sti-ongly disposed to agree.

Genus PTYGUEA. — Eyes and hair absent ; foot simple, truncated, cylin-
drical. Body campanulate, oblong. Rotaiy organ simple, and nearly circular.
Numerous tooth-like bodies, adhering to the bulb of the oesoi^hagus, two
glands, a small narrow oesophagus, an elongated stomach, and a subglobular
rectum constitute the apparatus of nutrition. An ovarium and a contractile
vesicle have been observed, but no visual organs.

This genus is comprehended in the family MeHcertiens of Dujardin, along
with Lacinularia, Tuhicolaria, and Melicerta, and is made to include the
species distributed by Ehi-enberg in the several genera Ptygura, (Ecistes, and
Conochilm ; for Dujardin states that the individuals of these three genera
present no fui-ther ditference than is seen in the gelatinous envelope, which
siuToimds the two last, forming in (Ecistes a distinct tube for each individual,
whilst it includes the individuals of Conochilus in a common globidar mass,
and is absent in Ptygura. The same author would name (Ecistes crystallinus
" Ptygura crystallina," and the Volvox conocliila " Ptygura Volvox."

Ptyguba Melicerta. — Transparent ;
body cylindrical, club-shaped, tiu'gid an-
teriorly, with two little curved horns at
the mouth, and a single short tube at
tlie neck (?). The tail-like foot always
remains transversely folded (wrinkled),
as seen in xxv. 354, which represents

the imder side. When swimming, a ring-
like simple vibratile organ is thrust out,
with a lateral notch. The two jaw-like
parts of the oesophageal bulb have nu-
merous teeth, as represented at xxv. 355.
1-140".

Genus DASYDTTES (Gosse). — Eyes absent ; body furnished with bristle-
like hairs ; tail simple, truncate.

This genus, according to Ehrenberg's description of Ichthydina, must follow
after Ptygura.

Dasydytes goniothrix. — Hairs long, pencil of long hairs at each angle of the
each hair bent with an abrupt angle ; j^osterior extremity of the body ; head
neck constricted. 1-146". Found at turnished with two club-shaped organs
Leamington. resembling antennae. 1-170".

D. antenniger. — Hair short, downy; a

Genus ICHTHYDIUM.— Tail cleft or forked, foot-Uke ; no eyes or hair ;
currents at the mouth and along the ventral side indicate the existence of a
vibratile organ, which not only serves for swimming but likewise for creeping.
A long oesophagus, a thick simple conical alimentary canal, and sometimes a
large single ovum, comprise our knowledge of their organization. It is pro-
bable that a cylinder of little wand-lilvc teeth exists (see Part I. p. 380).

ICHTHYBiUM Podura ( Cercaria Podura,
M.). — Straight, oblong, often slightly
constricted anteriorly, where it is tiu'gict,
and sometimes three-lobed. It is colour-
less or whitish, hut during repletion
sometimes appears yellowish ; the ven-
tral surface is flat and ciliated, tlie dorsal

arched and smooth. The large dark
ovarium has been seen by Eln-enberg.
It seldom swims, but mostly creeps,
xxv. 356 exhibits a fuU-growni animal-
cule (ventral side). Among Gonfervsa
and Oscillatoriaj. 1-440" to 1-140".

Genus CHiETONOTUS. — Dorsal siu-face covered with hairs ; tail forked ;
eyes absent. Locomotion is performed by means of a double row of cilia upon
the ventral surface, forming a band-like rotary organ. The nutritive organs
consist of a tubular mouth, probably provided with a cylinder of teeth, a long
thin oesophagus, and n long conical stomach (trachelogastricum), upon whoso

G62

SYSTEMATIC HISTORY OP THE INFUSORIA.

upper thick end (in the largo species) two semiglobular glands are seen ; at
certain periods from one to three large ova are formed posteriorly, but the
ovarium in which they are developed has not been directly observed ; male
reproductive organs unlcnown. They are sluggish in theii- movements, except
in creeping; they rarely swim. (See Part I. p. 380 et seq.)

CiLffiTONOTUS maximus (xxxi. 29, 30).
— Elongated, slightly constricted ante-
riorly, turgid and obtusely three-lobed ;
hairs upon the back short and equal.
From his latest observations, Ehrenberg
states the mouth to possess teeth, of
which he has counted more than eight;
he once saw the exclusion of ova imme-
diately over the foot-like tail. It creeps
but slowly. 1-216" to 1-120". (See
p. 3810

C. Larus {Trichoda Acarus, Anas et
Lanes, M.). — Elongated, slightly con-
stricted anteriorly, where it is turgid and
obtusely tiiangular; the posterior hair
on the dorsal surface is longest. Ehren-

As before stated, Dujardin places this genus, together with Ichthydium,
among the Infusoria (Polygastrica, Elir.), but in a subclass of them, called
symmetrical, along with Coleps and a doubtful genus named Planariola.
These genera are distinguished by him from all other Infusoria in having a
symmetrical figure.

One species of GJicetonotus described by Dujardin is probably new, although
it may be, as he remarks, but the O. maximus of Ehi'enberg.

The following are its characters : —

berg has seen only one large ovum ; he
states that the bodies of those bearing
ova were thick posteriorly, though, under
other circiunstances, the head ishroadest.
It appears to have eight teeth. The dor-
sal hairs, which are arranged in longi-
tudinal rows, destroy the transparency
of the body. xxv. 357 is a dorsal, and
358 a side view. Ova one-third the
length of the body. In muddy water.
1-720".

C. hrevis. — Ovato-oblong, slightly con-
stricted near the turgid front; dorsal
hairs few, the postenor longest ; ova
smaU. 1-340".

0. squamatus. — Elongate, naiTowed at
its anterior third, but expanded in its
posterior half. 1-130" to 1-135". Co-
vered with short hairs, which are dilated

in a scale-like form towai'd the base, and
regularly imbricated. In long-kept sea-
water brought from Toulouse.

Genus SACCULUS (Gosse) (XL. 17, 18).— One eye, frontal ; body desti-
tute of hail-, and without a foot ; rotary organ a simple wreath ; alimentary
canal very large ; jaws set far foi-ward, apparently consisting of two delicate
unequal mallei and a slender incus ; very evanescent ; eggs attached behind
after deposition.

This genus comes nearest to Olenopliora, but, unlike the latter, has but
one eye. Forty's genus Ascomorpha appears identical with Sacculus.

family, according to Ehrenberg's system ;
but the mode of cni-r^-ing its eg»s indi-
cates an affinity with the Brachionjea.

Saccitlus viriclis. — Pear-shaped ; flat-
tened ventraUy, the anterior end the
narrower ; head conical-pointed, sur-
rounded by a wreath of long cilia ; di-
gestive canal occupying nearly the whole
body, and always filled vnth a substance
of a rich green hue in masses. 1-150".
This curious animal, found in consider-
able number in a little pool on Hanip-
stead Heath, must be placed in this

Genus GLENOPHORA (XXV. 359).— Eyes two, placed anterioriy ; rotary
organ frontal, circular ; tail bifid, truncated. The alimcntaiy canal is short,
thick, and conicfil ; it sometimes contains green matter. The two protruding
forceps-like bodies in the middle of the rotary oi-gan may, says lihrenberg,

The Ascomorpha (jemanica of Leydig is
identical with the above species.

Mr. Gosse has ascertnined that this
species is dioecious, xi.. 17 represents
a newly-bom male, and 18 a female with
ova attached.

OF THE (ECI8TINA.

663

be considered teeth ; glands .are indicated by knot-like tiu-bid bodies. The
eyes are sharply circumscribed, and situated at the frontal region. Dujardin
and Leydig believe this genus to be based on young animals, and as such
unsatisfactory.

Glenophoba Trochus. — Ovato-coni-
cal, tnmcated and turgid anteriorly, at-
tenuated posteriorly, with, a false foot;
the eyes ai-e blackisn. It swims quickly,
like a D-ichoda or free VoHicella. The

genera Monolabis and Microcodon have
similar forms, (xxv. 359, 360 represent
two animalcules, the latter having the
stomach fiUed with a green substance.)
1-570".

FAMILY II.— (ECISTINA.

Eotatoria with a single rotary organ, entire at the margin, and an ex-
ternal gelatinous envelope. This family contains only two genera, which
possess a more developed internal organization than any hitherto described.
They are further provided, accordiug to Ehrenberg, with loeomotive organs,
internal muscular bands, a tail-hke foot without terminal piucers ; nutritive
organs, among which is a crashing apparatus consisting of teeth in rows ;
two pancreatic glands, and red visual or eye-spots. In Conochilus alone he
thinks he observed ganglia with nervous fibrillse, male organs, vessels, and
two filiform tremulous organs or gills.

This description is of course modified by the views Ehi'enberg entertains
respecting the various organs contained in the bodies of these animals. We
have no evidence that the glands are panci-eatic ; the " male oi'gans " are
the water-vascular canals of other writers, of which the tremulous organs or
giUs are external appendages ; the " vessels " are muscular bands ; and the
nervous fibrillse and ganglia have a more than doubtful existence.

External envelope . . .

f Special for each animalcule CEcistea.

[ Compound, or common to many animalcules Conochilua.

Both the (Ecistes and Conochilus are included by Leydig in his fii'st division
of Eotatorial animals.

Genus (ECISTES (XXV. 361-364).— Characterized by each animalcule
having a separate lorica. The two eyes, situated anteriorly, become elFaced
as age advances. Ciliary wi-eath simple and frontal ; the long taU-like foot
has internal longitudinal muscles. Alimentary canal simple, tubular, con-
tracted ; stomach elongated; teeth attached in rows to two jaws situated in
the pharyngeal bulb, and two glands, compose the apparatus of nutrition.
The visual organs are red when the animalcule is yoimg, and colourless in
old age. The ovarium has only a single ovum. The envelope is a viscid,
gelatinous, cylindrical sheath (urceolus), into which the animalcule can
entirely withdraw itself, or which it may quit when a new one is desirable.
The attachment to the bottom of the lorica is by the under surface of the end
of the foot-like tail.

QjIcistes crydallimis. — Lorica hya- and on giving the egg a gentle pressure

line, viscid, floccose ; body ciystalline. it hurst, and the free young animal

The structure it is diflicidt to see. Each came forth (xxv. 361, a full-gi'own ani-

jaw has three distinct teeth. The do- malculo in the act of unfolding itself •

velopment of the young from tlie egg 302, auother with its rotary organ ex-
is interesting to observe : Elu-enbcrg panded). Their sluiaths are incvusted

saw within the shell two dark points and vvitliin may be seen a number of
(eyes) near the already developed jaws ; 1 eggs (363, 364 represent them attached

SYPTKMATIC HISTORY OF THE INFUSORIA.

to the pectinated leaves of the water-
violet, as they appear under a shallow

pocket mapTiifie
1-36" ; without,

71

Lonrth, witli tail,
140" ; lorica 1-70".

Genus CONOCHILUS (XXV. 3G5-370).— Animalcules social, having con-
glomerate and contiguous envelopes ; each has two permanent eyes. Only
one species is Imown; its description, therefore, will include that of the

genus.

CoNOCHiLTJS Volvox. — The compound
masses white ; envelope gelatinous, hya-
line, consisting of from ten to forty ani-
malcules united so as to form a sphere,
which revolves in swimming, like the
Volvox. The frontal region of the ani-
malcule is broad, truncated, and sur-
rounded with a wreath of cilia, inter-
rupted at the mouth, which is lateral.
On the frontal plane arise four thick
conical papillre, often fiunished with an
articulated bristle, especially the two
anterior, as seen in xxv. 365, 366, and
368. The oesophagus is short and nar-
row; its head, or bulb, has jaws, with
teeth and four muscles; it lies imme-
diately within the mouth. The stomach
and I'ectiun are oval. Two spherical
glands are observed near the cesophagais,
and posteriorly an ovarium, often con-
taining a large ovum, which is expelled
near the base of the tail. The ovate or
shortly-cylindrical body temiinates in a
long, thin, and sti-ong cylindrical foot-
like tail, the end having a suction-disc.
The gelatinous envelope is only percep-
tible in coloured water, except when
infested vdth green parasitical Monads ;
the animalcules can completely ^\^thdraw
themselves within it, their tails becom-

ing thickened and bent. (In the group,
xxv. 366-368, the lorica is not shown.)
There are no anterior mascles, but three
pairs of posterior ones, which disappear
near the rotary organ ; there are also a
back and two lateral paii-s. Several
transverse bands appear connected with
two anterior, lateral, longitudinal ones,
which, Ehrenberg states, must aiise from
a network near the head, as in Hydatiyia.
These are probably muscular. He has
also seen two spu-al bands, situated pos-
teriorly. Two beautiful red visual organs
lie immediately beneath the wi-eath of
cilia, and behind them little oval bodies,
which he regarded as nervous ganglia,
but doubtless eiToneously. In the foot-
like tail are two large wedge-shaped
glands, probably male organs. These
creatm'es will feed upon caimine and
indigo, but are mostly filled with a
golden-coloured food. (xxv. 370 repre-
sents a cluster of animalcules magmfied
about ten diameters, of which figs. 365-
368 represent a poi-tion highly mag-
nified; the first is an under view, the
two next dorsal ■s'iews, and the last a
side view. xxv. 369 shows the jaws,
teeth, and part of the pharyngeal bulb
separate.) Size 1-60" ; sphere 1-9".

FAMILY III.— MEGALOTROCMA.

No envelope or lorica. Rotary organ, which is also that of locomotion,
simple, incised or flexuose at the margin. Distant muscular bands visible,
by means of which the shape of the body can be modified. In Megalotrocha
the alimentary canal is provided \vit\i two jaws, a stomach, two cjeca, and
two glandular appendages. In Microcodon there are two single-toothed jaws,
and a simple canal, mthout distinct stomach or cffica. Tlio ovarium in both
genera develope a few large ova, each of which in Megalotrocha, Ehrenberg
affirms, after expression, is retained in connexion with the body by means of
a thread. "Water-vascular canals, with tremulous tugs, exist in Majaloirocha ;
red eye-spots in both genera indicate a nervous system ; and in MegalotrocJui
a radiating body, supposed to be a cerebral ganglion and to form dark glan-
dular (?) spheres, are seen in the neighbourhood of the mouth.

Ehrcnberg's divisions of the family are given at p. 478 of the General
History.

The genera contained in this family arc undescribcd by Dujardin and
Lcydig, whilst Siebold only recognizes 3Iegalotrochn. Ciipliovautcs, instituted
by Ehrenberg upon two animalcidos found" in water from the Baltic, Dujardm

OT THE FLOSCULAKI.TSA,

GGo

considers is a doubtful member of the Eotatorial class ; and Leydig suggests
that it is probably a lai-va of some cephalous mollusk. In the propriety of
excluding it from amongst the Eotatoria we fuUy concm\ Dujardin and
Leydig also transfer Microcodon to another family, regarding its caudal process
as being a free articulate foot rather than a contractile attached peduncle.
Its affinities are unquestionably with Fiircularia, Notommata, and Hydatimi,
rather than with Megalotroclia.

Ehi-enberg's description of the ovum of Megalotrocha alho-fiavicans con-
tains some grave errors. He describes the embryo as developing within the
germinal vesicle, and gi'owing at the expense of the surrounding yelk, as is
the case with a vertebrate ovum. This is so contrary to what occurs in
other Rotifera, in which the entii-e yelk is directly transmitted into the
embryo, that, merely reasoning from analogy, we should be led to reject it.
But KoUiker has shown that the embryo of Megalotrocha is developed in the
same way as those of other Rotifera.

Genus MICROCODOlSr. — Eye single ; wreath of cilia simple, bent in the
middle so as to resemble the figure 8 lying transversely ; alimentary canal
thick and straight, without a stomach ; no oesophageal tube, but a sort of
pharyngeal bulb and a couple of single -toothed jaws ; also a tui-gid ovarium.
Immediately behind the rotary apparatus is a small red visual organ ; and at
the frontal region, beside it, is a reddish knot whose function is unknown.

MiCHOCODON Clancs. — Campanulate,
pedicled, the stj'liform foot-like tail as
long as the body ; in the middle of the
brow ai-e two bundles of stifl' bristles ;
two pincer-like points, evidently teeth,
project out of the middle of the rotaiy

organ, and are in connexion with the
reddish jaws, (xxxrr. 371 is a back, and
fig. 372 a left side view.) 1-280".

Perty thinks that the so-caUed eye
consists of two red stripes, beneath which
a ribbed body is faintly discernible.

Genus MEGALOTROCHA. — Eyes two, sometimes becoming effaced by
age ; rotary organ has two lappets. The nutritive system consists of a
stomach, caecum, rectum, and oesophageal head, having two jaws, with teeth,
and two glands ; reproductive organs, a short Imottcd ovarium, with a few
ova ; muscles, three pair anterior, two pau- posterior, longitudinal ; two con-
tractile muscles for the rotary organ, and four oesophageal ; eyes frontal, of
a red colour when young ; four circiilar transverse muscular- bands are also
seen. The nature of four opaque white spherical bodies at the base of the
rotary organ is unknown.

Megalothocha alho-Jlaviccms (Vor-
ticella socialis, M.). — White and free
when yoimg ; yellowish, and attached in
radiatmg clusters when old. Ehrenberg
states he has often perceived the red
eyes within the unbroken egg ; and the
iaws, as if in the act of chewing, move
laterally and horizontally against each
other. Two ova are rarely produced at
one time ; the egg, when expelled from
the body, remains attached to it by a
thread ; and the pai-ent has often four

or five tlius attached, and in process
of further development, (xxxu. 374-
376 represent different specimens ; 377
merely the teeth and jaws sepai-ate.)
I Upon water-plants. Size of single ani-
malcule 1-36" ; of the spheres 1-6"
(xxni. 1).

M. velata (Qosse).— Animals separate •
disc partially enveloped in a cleft, gra-
nulai- integument ; eggs not attached to
the parent after deposition. 1-55".

FAMILY IV.— FLOSCULARIJSA.
Rotatoria surrounded by a case or envelope, and piovidcd w ith a sindo
rotary organ, flcxuose at its margin and lobcd or divided, ha^•iug from two to

666

SYSTEMATIC IU8T0EY OF THE lUyDSOHIA.

six clefts. In some genera the cilia of this organ are quiescent at intervals,
not vibrating continuously ; the alimentary canal is complex, usually divided
transversely into several segments, and with various external appendages,
believed to be glandular, the proventricular segment, gizzard, or pharyngeal
bulb furnished with teeth. Lacinularia has a mouth, oasophagus, pharyngeal
bulb with teeth, a stomach constricted iato three segments, and a short
intestine ; the lower stomach clothed internally with a veiy long cilia.
Melicerta has a similar arrangement, but with only two unequal segments in
the stomach, both of which are cUiated interiorly. Two water-vascular
canals arise from a contractile sac opening into the cloaca, and pass upwards,
one on each side of the alimentary canal to the head, where, in Lacinularia,
they ramify into a network ; along their course they have appended to them
small tags or sacs, each containing a large vibratile cUium. These have been
seen in Lacinularia, Melicerta, and StepJianoceros. In Lacinularia, Limnias,
and Melicerta, a small lobate mass exists near the mouth, believed by Huxley
to be a cerebral ganglion. Leydig assigns nervous functions to smaU bodies
distributed through Lacinularia ; but these appear to be merely the small
stellate masses of viscid protoplasm described by Williamson in Melicerta,
and Leydig in Stephanoceros. Eyes exist in aU the genera, except Tubico-
laria, at some stage of life. In Melicerta and Lacinularia they disappear as
the animal approaches adult life. Gosse says that the same is usually the
case in Floscularia, but that he has occasionally met with adult specimens in
which eyes were present. Some species (if not aU) have well-marked fasciculi
of voluntary muscular fibre, especially running parallel to the long axis of
the body, which their contraction shortens. Male reproductive organs hitherto
unobserved. Female organs an ovisac composed of thin transparent mem-
brane, distended with granular protoplasm, in which are distributed cells or
germinal vesicles, each containing a nucleus or germinal spot. In Melicerta
this ovarium communicates with the cloaca by means of an oviduct. Some
species produce two classes of eggs, one being probably the true ovum, the
other an encased gemma or bud. Several species retain the eggs within the
envelope of the parent until the yoimg are hatched ; others set them free at
an early stage of embryonic development.

Ehrenberg's arrangement of the genera of this family will be found at
p. 478 of the General Histoiy.

Eyes present Tubicolaria.

One eye present (when young) Stephanojfros.

/ /Envelope of the single animal- 1 Limnias.

cules distinct or separated... J Cephalosiphon.

Two eyes
present
(when
young),

Rotary organ two -parted _
when full-gi'own

Envelope of tlie single animal- "1 j^gj,j„ui„
cules conglomerated J

Rotary organ four-parted when fall grown Melicerta.

\ Rotai7 organ five- to six-parted when full-gi-own Floscularia.

Dujardin has a family of " Flosculariens," which, however, differs much
from that of Ehi-enberg, both in its distinctive characters and in the species
assigned to it. The French naturalist includes only two genera, viz. Flos-
cularia and Stephanoceros. Contrary to Ehrenberg's assertion, these two
genera are stated by Dujardin to bo destitute of a rotary organ, and indeed
of vibratile cilia, and are described as having a campanulate, contractile

OF THE FLOSCULARIiEA.

667

body, tapering towards the base so as to form a long pedicle, by which they
affix themselves to solid bodies. Theii- mouths are furnished with homy jaws.
Speaking of their affinities, he remarks, " The Plosculariens, like the Meli-
certiens, also have a certain affinity in form with the Yorticelliens and the
Stentors, and also with the Campanularue among polypes. They live in the
same way, fixed to water-plants by the pedicle of their campanulate body, the
margin of which presents five or six lobes, terminated by appendages or cilia,
-without, however, any indication of a vibratile movement. At the bottom of
this wide opening is situated the mouth, provided with jaws attached to a
muscular bulb, less frequent and regular in its movements than the other
Rotatoria. In Floscularia the jaws are simple, and the lobes of the (anterior)
margin short, but with long radiating ciHa ; whUst in Stephanoceros the jaws
are compoimd, and the marginal lobes very long and covered with short
cilia." Dujardin states further, that the gelatinous case of Floscularia may
disappear, and therefore cannot be used as a generic distinction, either in the
case of that genus or indeed of the other genera included in Ehrenberg's
family of the same name. Entertainiag this opinion of the differences of the
gelatinous envelope being accidental, not constant, Dujardin rejects the genus
Linmias as not distinct from Lacinularia, whilst he denies that the latter is
generically distinct from Megalotrocha — a conclusion in which Huxley is dis-
posed to agree with the French naturalist. Of the remaining genera of
Ehrenberg's family Eloscularisea, viz. Tubicolaria, Lacinularia, and Melicerta,
to which he adds Ptygura, already described, Dujardin constitutes a family
which he terms Melicertiens. In some of these objections there is force.
Floscularia and Stephanoceros undoubtedly differ from the remaining genera
in the form assumed by cUiated appendages supposed to represent the trochal
disk of Melicerta and Lacinularia. Gosse states that in Floscularia rotation
is accomphshed, not by the tufts of long setae, but by ciha set on the inner
surface of the disk, which cause the currents to converge to the mouth of the
animal ; hence, if the setigerous bulbs of Floscularia and the cUiated arms of
Stephanoceros are not the homologues of the true trochal disks of Melicerta,
the propriety of Ehrenberg's definitions is seriously impaired. But we see
no reason for rejecting this homology in the case of Stephanoceros merely
because the motion of the verticUlate cilia is periodic and interrupted instead
of continuous : and if Mr. Gosse is correct in his conception respecting Floscu-
laria, it is equally entitled to its present place ; for whilst, on the one hand
it is not essential to a trochal disk that its moving ciha should be arranged at
its margin, on the other, these cOia do not exclude the possibihty of other
appendages, such as the pencils of setae in Floscularia, being attached to the
same organ, though such appendages may have no homologues amongst the
other Floscularian genera.

Dujardin's objection respecting the gelatinous case of Floscularirt is probably
based on error. Mr. Gosse has shown that in some cases it is so thin that it
might easily be overlooked, without great care being taken to discover it.

Leydig of course rejects Ehrenberg's family of Flosciilaiia, arranging the
animals composing it in his first group, along with (Ecistes and Conochilus
with which they have unquestionably a vciy close affinity.

The creatures composing this family are undoubtedly among the most
interesting and beautiful of Infusorial animals. Their developed organiza-
tion, and singular habits, render them objects of the highest interest both
to the naturaUst and the physiologist; whilst their exquisitely beautiful
contour and the magnificent phenomena presented by the trochal cUia when
in active rotation, never fail to impress even the most careless of observers
with a sense of wonder and delight.

GGS

SYSTEMATIC HISTOKY OF THE INFUSOEIA.

Genus TUBICOLARIA (XXXII. 379-382). — Figure clavate, with a
transparent gelatinous case. Rotary organ deeply fissured on the abdominal
aspect, and less strongly on the dorsal side, by which it is divided into two
lappets, each of which is again partially subdivided into two. Ciliary wreath
double, with a space between the rows. Mouth opening directly into the
oesophageal bulb, in front of which is a smaU vesicular organ filled with pale-
reddish matter. Stomach long, with thick ceUular walLs and four glandular
organs sui-rounding its upper extremitj^. Intestine thin and clear, curving
slightly forward towards the anus. Two water-vascular canals extend along
the body, apparently forming a network at the head, and beaiing a couple of
vibratUe tags. No contractile vesicle observed at their cloacal extremity.
Foot, by means of which it adheres to foreign bodies, terminated by a bundle
of ciUa. Two tentacles extend from the abdominal siuface, a little below
the mouth ; each has a clear fibrous-looMng tract along its centre, and is
terminated by a bundle of setae. Embryo with the gelatinous sheath colour-
less, but acquiring consistency and a yellowish hue with advancing age. There
is a small concretionaiy mass, apparently surrounded by a sac, aflirmed by
some to be luinary, in the body of the embryo.

TuBicoLABiA Nqjas. — The jaws have
four teeth ; and the tactile tubes are hairy
anteriorly. This animal is described fiilly
in the account of the genus ; and xxxn.
378-382 will illusti-ate it. 381 represents
the animals of natiu'al size, as foimd at-
tached to the roots of Lemna polyrrhiza,

with those of the following genviB ; fig.
379 represents an animalcule within its
case, the rotary organ withdrawn ; fig.
380, another extended, and without its
lorica; fig. 382, the oesophagus, with the
jaws and teeth separate. 1-36".

Genus STEPHANOCEROS (XXXII. 383; XXXVII. 1-4). — Eigiue
clavate, with five long arms at its anterior extremity, siuTOimded by verticils
of cilia. Sheath without parallel sides and with strong pai-aUel folds or
curves ; either crystalline without any foreign admixture, or sometimes over-
spread with small linear bodies like small dead Vibrios or Microglcnce. It
apparently is not tubular, but a solid gelatinous mass envelopes the animal
as high up as the base of the rotary arms. Acetic acid renders it white, and
nitric acid renders its outline more clear. Beneath the cuticle is a granular
layer containing nucleated ceUs. The cilia of the arms appear planted in a
granular stratum external to the cuticle, from which they are detached in
bundles when subjected to slight pressure. A deep transverse fold of the
integument exists at the base of the rotary organ, and contraction throws the
peduncle into coiresponding folds. Between the skin and the viscera are
numerous branching corpuscles resembling ceUs of connective tissue. Tliese
cells con'cspond with what were described by Professor "Williamson in Meli-
certa ringens. They look like small globules of ductile protoplasm, and closely
resemble the ductile bands seen in Noctiluca miliaris. It is not impossible
that these may reaUy bo some unchanged remains of the protoplasm of the
ovum, which they closely resemble. Pour long muscles, contained in sarco-
lemmata or sheaths, proceed from the foot anteriorly, brandling dichotomously.
Alimentary canal composed of a funnel-lilie oral cavity, opening into a still
wider proventricidus having an intermediate septum and four long bristles
with hooked extremities, then a globular maxillary bulb, conducting to a
special stomach, which terminates in a short intestine. The oral ca^^ty is
lined with fine cilia ; and the provcntriculus consists of two membranes, not
in close contact, but with a narrow intermediate space. The maxillary teeth,
the lining of tiie maxillary bidbs, and the oesophageal bristles resist the
action of liquor potassac, indicating a chilinous composition. The walls of the

OF THE PLOSCULARIiEA.

0G9

stomach have a thick layer of large cells filled with yellow granules or fat-
corpuscles. Intestine transparent and ciliated internally. A contractile sac
connected with the cloaca, fi-om which spring two broad water-vascular
canals, which are lost anteriorly in fi'ont of a fatty mass sui-rounding the
proventriculus. Ovarium developing but few ova at a time; these, when
discharged from the ovary, are still seen to be enclosed in a membranous
oviduct, extending from the ovary to the cloaca. No male organ hitherto
discovered.

Immediately above the proventriculus is a large collection of hyaline
vesicles, which evidently open extemaUy by a short duct. A dark granular
vesicle appears at the posterior end of the body of the embryo, as in Tubico-
laria fmAMelicerta, — supposed by some authors, but without sufiicient reason,
to be a urinary concretion. Two eye-specks at the opposite extremity of the
embryo. Two vibratile spaces also appear simultaneously, the one in front
of the other. The vibratile action is active within the anterior one, whilst
within the other a few long cilia undulate slowly.

When the embryo is first distinguishable, and separable from the egg, it
has a vermiform figure, and is about 124 millimetres in length. The head,
supporting the eyes, is separated from the body by a constriction ; its margin
is furnished with numerous ciha, the whole being retractile. Within the
body and behind the head are several longitudinal stripes of a doubtful
natui'e ; and still more posteriorly is a clear space with some long cilia in
action, which may represent the alimentary cavity ; the maxillary jaws ai-e
perceptible, and the posterior extremity fui-nished with some cilia. On one
occasion Leydig met with another form of embryo, which retained the vermi-
form aspect in its body and foot, but with the former elongated, and termi-
nated by four arms. Two eye-specks present, and a proboscis in fi-ont, with
two extended tubular processes terminated by cUia. Extremity of the foot
devoid of cUia. The maxillae were fiiUy developed ; and, near the sac with
the dark granular concretions, ciHary vibration was discernible. Leydig
thinks that the dark granules of the sac escape into the cloaca, and regards
them as urinaiy concretions accumidated in the extremity of the intestine.
Cohn rejects the idea that they so escape ; and we believe him to be correct
on this point. The granules are affected by potash, but not by acetic acid.

Stephanoceros Eichhornii (xxxn.
383; xxxvn. 1-4). — The case transpa-
rent, like glass; rotaiy organ with five

lobes or arms, each furnished with fifteen
verticUs of cilia ; these arms act occasion-
ally as prehensile instruments. As the
eggs are detained in tiie case irntU the
youngare hatched, Ehrenberg erroneously
considers this creature viviparous. In

xxxn. 383, the eyeand tags are visible, and
over the latter what Ehrenberg calls gan-
glia. The case is discerned wth difficulty,
from its very transpai-ent natm-e, unless
indigo is mixed with the water. 1-36".

S. glacialis. — Only one specimen seen
without its stem. " The five arms not
fm-nished with ciliary whorls, but with
single bristles. 1-14"'.

The internal organization of Stephanoceros is well illustrated in XXXVII. 1 :
h is the pharyngeal bulb, resting upon a provcntricidus or crop c, belo\\-
which is the maxiUary bulb d, containing the jaws ; c is the stomach, with
its large cells ; wliilst / is the intestine, terminating at the cloaca ; g is the
ovary containing ova ; k indicates delicate longitudinal muscles, extending
down the peduncle; and tt the water-vascular canals with their vibratile
tags.

In fig. 2 the detached ovary is represented, consisting, as is usual amono-st
the Rotatoria, of a dehcate membranous sac, /, prolonged into an oviduct
The contained ova are seen in difForont stages of development. At a is the
stroma or granular mass, with its germs ; h is an oymm in the first stao-e of

670

SYSTEMATIC HISTORY OF THE INFUSORIA.

fission ; at c the ovum has undergone several repetitions of the yelk-division ;
and at d is an ovum in which the contoiu- of the embryo is visible. The two
eye-spots seen at d ; and the so-caUed dark urinary concretion, seen also in
embryonic Melicertce and others, at k. The real natui-e of this last object,
which is seen only in the embryonic state of these animals, is yet doubtful.
Fig. 3 represents a very young StepJianoceros a little after its liberation
from the ovum ; and fig. 4 another immediately after its liberation from its
shell. The dorsal aspect of the jaws of the maxillary bulb, according to
Mr. Gosse, is represented in XL. 27, and the oblique aspect of the incas in
XL. 28.

Genus LIMNIAS (XXXII. 388-392; XXXVI. 2). —Eyes two; case
(urceolus) solitary ; rotary organ two-lobed when fuUy grown, being then
constricted in the middle ; alimentary canal simple, terminating at the base
of the foot or tail ; stomach, two jaws with teeth, and two glands also
present. The ova are deposited within the case, where they are developed ;
neither male organs nor water-vascular canals discovered ; two visual organs
indicate sensation : these in the young animalcules are red, and are even
visible within the ovum ; but in old age the colour disappears, and hence
they are not seen. In the middle of the rotary organ, when expanded, are
seen four large globules, which Ehrenberg erroneously considers nervous
ganglia, or brain.

LiMNiAS Ceratophylli (xxxn. 388-392 ;
XXX.VI. 2). — Case white at first, after-
wards brown or blackish; smooth, but,
being viscid, often covered with exti'a-
neous particles ; its connexion with the
animalcide is a volxmtary act of the
latter; the two red eyes and the jaws
may be observed in the ova when de-
veloped; by giving the latter a gentle
pressm-e the shell bursts, xxxn. 389
exhibits an animalcule just emerged from
the egg, 392 ; 391 a young specimen,
with a rotary organ nearly circular, and
two eyes ; 390 a full-grown specimen,
without its case, fed on indigo — the

jaws (each of which has three strong
teeth), the ova, and the ti-aces of lon-
gitudinal muscles are seen, the wheel
is folded up ; 388 another, within its
case, having the lobed rotary organ ex-
panded, (xxxvi. 2. is more magnified.)
Found upon hornwort {CeratophyUiim)
and other aquatic plants. Length about
1-20" ; case 1-40".

Ij. annulatus (BaUey). — The case is
ribbed and semitranspai'ent, and is com-
posed of a linear series of lings. Found
in a ditch at Witlin^ham, near Norwich,
on duck weed (Brightwell) ; and by Dr.
Bailey near New York, U.S.

Genus CEPHALOSIPHON. — Eotary organ bilobed ; eyes two ; sheath
single ; two frontal horns, including the siphon.

Cephalosiphon Limnias. — Sheath membranous, anmdate. 1-6"' to 1-5"'. On
Ceratophyllum. Berlin, July.

Genus LACINULAKIA (XXXVII. 19-25). — Eyes two (in the young
state) ; the cases (urceoli) conglomerate, or grovra together ; rotary organ
two-lobed when full-grown, but nearly cii'cular when young: this oi^n is
the chief instrument of locomotion. Band-like longitudinal muscles exist
within the body. Pharyngeal bulb large, wath two jaws, and teeth in rows ;
oesophagus short, narrow ; stomach elongated, transversely constricted, and
with caecal (?) appendages ; short. The ovarium is situate about the middle
of the body, and opens, along ^vith the intestine and the contractile sac of
the water-vascular canals, into the cascum. Visual organs exist in the young
state ; red in the developed oviun, but becoming dai-ker as they advance to
maturity. Globular bodies support the oesophagus on each side ; and below
the mouth is a small organ, supposed to be the brain.

OP THE FLOSCTTLARIJEA.

671

Lacinulabia socialis ( Vorticella so-
cialis et Jiosculosa, M.) (xxxvii. 19).—
Envelope gelatinous, transparent, in
which are implanted numerous indivi-
dual animals, that have imitedly tlu-owu
out the gelatinous secretion in which
the}' are imbedded. Body elongated, co-
nical peduncle (xxxvn. 19 k) truncated
and foiming at its posterior exti-emity
a sucker, attaching the animal to the
foreign object supporting the entire
group. Trochal disc at the anterior ex-
tremity of the body, into which it is
di'awn vrhen at rest (xxxvn. 19 a), but
expanding into a horseshoe-shape, with
a double row of cUia round its margin.
Mouth in the notch of the trochal disk.
Pharynx leading to a pharyngeal bulb
(19 b), in which the jaws are planted.
These are not stirrup-shaped, as described
by Ehrenberg, but composed of four
pieces (xxxvn. 20). (Esophagus passing
through the bulb reaches the first sto-
mach (19 c), into which two cellulai"
appendages, regarded by Ehi-enberg as
pancreatic, open. Below this is a second
dUation {l%d), furnished with several
short cellular caeca, and still lower a
third, more globular segment (19 e),
also furnished with external cellular
caeca, and clothed internally with long
cilia. From this a short intestine, ac-
cording to Huxley, turns upwards and
outwards, terminating in a cleft of the
integument on the same side as the
mouth. This " intestine " is probably
the cloaca of other writers. Two water-
vascular canals (19 1) arise, one on each
side of the intestine (cloaca), and ascend
on opposite sides of the body towards
the head. They divide opposite the pha-
rjTigeal bulb, each into three branches,
one of these uniting with its feUow, the
others terminating as caeca ; within these
are distributed five pairs of long vibratile
cilia. Vacuolar thickenings of the in-
tegument exist in several parts of the
body. A small ciliated sac is located
below the mouth, and still lower is a
small organ believed by Prof. Huxley to
be the cerebral ganglion. Two eye-spots
occur on the ti'ochal disc of tlie young
animal (xxxvii. 11), but they disappear
in the adult. No male reproductive
organ hitherto discovered. Prof. Hux-
ley's description of the female organs,
and the development of the ova, is as
follows : — " The ovary consists of a pnlo,
slightly granular ma,ss, of a transversely
elongated form (19 A^, and somewhat
bent round the intestine ; it is enclosed
iu a delicate transparent membrane,

which is hardly visible in the unaltered
state, but becomes very obvious by the
action of acetic acid, which contracts
the substance of the ovary and throws
the membrane into shai-p folds."

Pale clear spaces (xxxvn. 7), which
sometimes seem to be limited by a distinct
membrane, are scattered through the
substance of the ovary; and in each of
these a pale circular nucleus is contained.
The nucleus is more or less opaque, but
usually contains from one to three clear
spots. These are the germinal vesicles
and spots of the future ova. Acetic acid,
in contracting the pale substance, gi'oups
it roimd these vesicles, without, how-
ever, breaking it up into separate masses.
It renders the nuclei more evident.

The ova are developed thus : — One of
the vesicles increases in size ; and reddish
elementary gi'anules appear in the ho-
mogeneous substance aroimd it. This
accumulation increases imtil the ovum
stands out from the siu'face of the ovary,
but invested by its membrane, which, as
the o\Tim becomes separated, takes the
place of a vitelline membrane.

In the meanwhile the gemiinal ve-
sicle has increased in size ; and its nu-
cleus is no longer visible. In the ovum
it appears as a clear space ; isolated by
crushing the ovum, it is a ti"ansparent,
colom-less vesicle. The perfect ova are
oval, about 1-10" in diameter, and are
exti'uded by the parent into the gela-
tinous connecting substance, where they
undergo their development.

The changes that take place after ex-
trusion, or even to some extent vdthin
the parent, are — 1, the disappearance of
the genninal vesicle (as Huxley judged
from one or two ova in which he could find
none) ; 2, the total division of the yelk (as
described by Kolliker iu Megaldtrocha),
until the embryo is a mere mass of cells
(xxxvn. 5, 6, 8, 9), from which the va-
rious organs of the fojtus are developed.

The youngest fostuses are about 1-70"
in length. The head abruptly trun-
cated (xxxvn. 10), and separated bv a
constriction from the body. A sudden
narrowing separates the other extremity
of the body from tlie pedimcle, which is
exceedingly short, and provided with a
ciliated cavity (a sort of sucker) at its
extremity. The head is nearly circular
seen from above, and presents a centi-ai
protuberance, in which the eye-spots are
situated. The margins of this protu-
berance arc provided with long cilia
which will become the upper circlet of
cilia in the adult. In young Laemdanr^

672

SYSTEMATIC niSTORY OK THE INFUSORIA.

1-80" in length, the head has become
triangular (xxxvii. 11), and thus it gra-
dually takes on the perfect form. The
young had previously crept about in the
gelatinous investment ot the parents ;
they now begin to "swarm," imiting
together by their caudal extremities, and
are readily pressed out as fi-ee-s^vimming
colonies, resembling in this state the
genus Conochilus (Huxley). But, besides
the ova whose development is thus de-
scribed. Professor Hiixley observed a
second class, to which he refers as fol-
lows:— "In a fully-grown Lacinularia
which has produced ova, the ovary, or a
large portion of it, begins to assume a
blackish tint (xxxvii. 22) ; the cells,
with their nuclei, undergo no change,
but a deposit of strongly refracting ele-
mentary granules takes place in the pale
connecting substance. Every transition
may be traced, from the deep black por-
tions to unaltered spots of the ovarium ;
and pressure always renders the cells
with their nuclei visible amongst the
gi'anules. The investing membrane of the
ovary becomes separated fe'om the dark
mass, so as to leave a space ; and the outer
surface of the mass invests itself ^vith
a thick reddish membrane (xxxvii. 24),

which is rough, elastic, and reticulated
from the presence of many minute aper-
tures. This membrane is soluble in both
hot nitric acid and caustic potass. The
nuclei and cells, or rather the clear spaces
indicating them, are still visible upon
ressure, and may be readily seen by
ursting the outer coat. By degrees the
ephippial ovum becomes lighter, imtil at
last its coloiu- is reddish-brown, like that
of ordinary ova ; but its contents are now
seen to be divided into two masses, hemi-
spherical from mutual contact (f. 21). If
this body be now cmshed, it will be found
that an inner sti'uctureless membrane
exists within the first-stated membrane,
and sends a partition inwards at the line
of demarcation of the two masses. The
contents are precisely the same as before,
viz. nuclei and elementary gi-anules. I
was unable to ti-ace the development of
these ephippial ova any fm-ther."

Professor Huxley thus indicates his
belief in the existence of two classes of
ova in Lacinularia, one of which he
thinks probably requires sexual fecunda-
tion, whilst the others do not. Cohn
believes that the bodies usually temied
ova by Huxley and others are not so,
but internal gemmje.

Genus MELICERTA (XXXII. 386, 387 ; XXXVI. 1 ; XXXVn. 12-18)-
— With a case or envelope ; solitary ; rotary organ simple, with four lobes
when expanded ; free longitudinal muscles for the contractions of the body ;
alimentary canal divided into segments, in one of wliich (the phaiyngeal
bulb) are complex jaws ; mouth situate at the bottom of the cleft between
the two larger lobes of the rotary organ ; the orifice of the cloaca near the
junction of the long peduncle mth the body. Male generative organization
unknown; believed by Mr. Gosse to be dioecious. Female organs a lai'ge
ovaiy filled with granular protoplasm and germinal vesicles, as in the pre-
ceding genus, but with a distinct oviduct opening into the cloaca. Two
water-vascular canals, ai-ising from a contractile vesicle, ascend towards the
head. Two tactUe appendages, with setigerous extremities, on each side the
head. Two eye-spots in the young animal. Nervous system imcertaui.

Melicebta ringem, — Case (xxxvi.
1 (/) conical, gi-anulated, resembling a
liouey-comb, of a brownish-red colour;
it is composed of small lenticular bodies,
secreted and deposited by tlie animalcide ;
these are agglutinated by a pecidiar
viscid matter, afterwards hardened in
the water. Into this tube the soft cry-
stalline or whitish animalcule can with-
draw itself; and when its flower-liite
wheel-work (1«) is expanded, tlie vibra-
tile cilia appear to run along the margin of
this organ ; but, in fact, each single ci'lium
only tunis itself upon its base, their agg re-
gate motion causing a little whirlpool in

the water, directed towards the mouth,
which is situated in the middle of the two
large leaflets of the rotary oi^an; the eye^
in the young animal ai'e placed near the
two other bent leaflets, which, according
to Ehrenberg, are analogous to a cleft
upper lip of the dorsal surface : the dis-
charging orifice is on the same side; and
therefore the dorsal tnU-like portion be-
comes a ventral member or foot, (xxxii.
.380, an animalcule within its case, ha\-ing
the rotary organ contracted : fig. 387, with
the trochal disc fully expanded : the case
is given in outline only, in order to
show the internal structure.) On Leumffi

OF THE PLOSCXTLAEIiEA.

673

and otter aquatic plants. Length 1-12" ;
aise 1-24" ; egg 1-150".

The pellets forming the case were
thought by Ehrenher"- and others to be
deposited from the cloacal orifice; but,
from the carefid researches of Mr. Glosse,
this appears to be an eiTor (Trans.
Microsc. Soc. 1851, vol. iii. part. ii. p. 62).
That observer points out the existence
of a special rotating organ of a cup-like
figiu'e (xxx^^. 1 c) (the disc seen above),
seated immediately above the projecting
tube. This organ he saw fill and empty
itself " many times in succession, imtU
a goodly array of dark pellets were laid "
down in'egularly, the animal effecting
their distribution by bending its head
downward, so as to bring this cup and
the margin of its sheath into apposition.
" After a certain munber were deposited
in one pai-t, the animal would suddenly
turn itself round in its case and deposit
some in another part. It took fi'om two
and a half to three and a half minutes to
make and deposit a pellet." Coloiu-ed
particles in the water " are hiuled round
the margin of the ciliated disc, until they
pass off in fi-ont through the great sinus
between the large petals ; " and the atoms,
if few, "glide along the facial smface,
following the iiTegularities of the out-
line with great precision, dash roimd the
projecting chin, and lodge themselves
one after another in the little cup-like
receptacle beneath," in which again they
are whirled round with gi'eat rapidity,
and prepared into pellets for the building
up of the case of the animal.

The internal organization of this ani-
mal haa been investigated by Professor
Williamson. Like Lacinulana, the tro-
chal disc is double at its mai'gin, with
two rows of rotaiy cilia, the currents
created by which are directed to the
mouth and pass off by the ciliated "chin"
— a small additional lobe above the cili-
ated cup of Mr. Gosse. On each side of
the trochal head are two hoUow pro-
cesses or " calcars " — the respiratory
tubes of Ehrenberg, but which are pro-
ba,bly tactile (xxxvii. 17 d). These ter-
minate externally in a deltoid body (13),
from which projects a pencil of straight
setae. Along the interior of this tube is
a delicate muscidar band, by which the
! Setigerous extremity can be dra-svni back-
Wards into the tube (14), and the setre
thus be removed out of danger. The
alimentary canal much resembles that of
Zacinuluria. There is a narrow ceso-
agus conducting downwards to the
arpigeal bulb (figs. 17 c and 23), in

which are implanted the peculiar jaws :
these are complex (f 26), consisting of
equilateral sets of nimierous transverse
bars, those of each set connected at their
peripheral extremities by an arcuate lon-
gitudinal one, and at their inner extre-
mities by a double broad longitudinal
one prolonged upwai'ds into a long nar-
row handle or process which meets its
fellow of the opposite side at a kind of
hinge-like joint. These jaws work upon
one another with a crushing motion by
means of the above joint, — the upper part
of the alimentary canal, and consequently
the food swallowed, passing between
them. Below the phai-joigeal bulb is an
oblong stomach, with cellular parietes
and kned with cilia. A constriction
separates this fi-om a lower and more
spherical portion (17 ff), also cellular
and lined with still longer cUia. This
opens into a long cloaca (17 k), which
tm-ns suddenlj' upwards to its temiinal
outlet (17 /). The interior of the body
contains numerous free muscidar bands.
These are especially distinct in the pe-
dimcle, along the entire length of which
several of them nm, which shorten
the body in its axial line. Each fasci-
culus consists of ti'ansversely striped or
voluntary miiscidai' fibre, and is enclosed
in a sarcolemna or membranous sheath
(18). Diffused through the body of the
animal, but specially distinct at the up-
per part of the pedrmcle, ai-e numerous
small masses of viscid granular proto-
plasmic substance, which send slender
prolongations to each other and to the
suiTounding parts, reminding the ob-
sei-ver of the pseudopodia of the Rhi-
zopods and the internal threads of
NoctUuca.

The water-vascular system consists of
two canals arising from a small p3Tifonii
contractile vesicle below the stomach,
and appai'ently with the cloaca. One
ascencis on each side of the alimentary
canal towards the head, where they
branch. Vibratilo tags ai-e connected
with them.

Professor Williamson describes the
ovaiy as " a liollow sac (xxxvii. 23 k),
consisting of a very thin pellucid mem-
brane. It is filled A\dth a viscid granular
protoplasm of a light grey colour, in
which are distributed from twentj' to
thirtv nuclei, each iiaving a diameter of
from" 1-1200" to 1-lGOO". Each nucleus
contains a largo nucleolus, var^ing in
diameter from 1-1600" to 1-3500". In
its noiTual state the gi-anular protoplasm
is of a unifonn gi-ey colour, ilowiug

674

SYSTKJIATIC niSTOEY OF TITE INFUSORIA.

freely out of the ovary when the latter
is ruptured. The nuclei situated nearest
the centre of the ovary appear to be
successively selected for development.
One of these nearest the siu-face attracts
aroimd itself a small portion of the gra-
nular protoplasm, detaching it from the
remaining contents of the organ, though
in close contact with them. The portion
thus specially isolated gi-adually enlarges,
assuming at the same time a darker hue,
whilst, from its central position, it par-
tially divides the upper from the lower
half of the remaining ovarian protoplasm.
At the same time the central nucleus
sometimes undergoes some slight en-
lai'gement, and its nucleolus appears to
become absorbed. The position of this
nucleus in the centre of the ovum is
now indicated by an ill-defined trans-
parent spot ; but on bursting the proto-
plasmic inass, it is seen to be a small
spherical cell about 1-1000" in diameter,
having very thin pellucid walls and
scarcely any visible cell-contents. When
the ovum thus segmented from the ova-
rian protoplasm has attained its full size
(xxxvii. 17 o), it becomes invested by a
thin shell, which is apparently a secre-
tion from its own surface."

" The ovum being now ready for ex-

J>ulsion, it is slowly forced down to' the
ower part of the ovaiy, the stomachs
being drawn upwards and to one side in
order to make way for it. Yielding to
the pressure produced by the successive
contractions of the body, the ovum
sweeps round the inferior border of the
lower stomach, and, passing through the
dilated oviduct, enters the cloaca. The
latter canals become entirely everted, as
is the case when the excrements are dis-
charged ; and by a sudden contraction
the ovum is expelled."

Professor Williamson minutely de-
scribes the conversion of the yelk into
an embryo — the successive segmenta-
tions of the nucleus and surrounding
yelk, imtil the whole becomes a cellular
mass, as in Lacimilaria. The first visible
evidence of life is the production of a
few moving cilia, especially near the
future head, followed first by traces of
the dental apparatus, then by the de-
velopment 01 the various organs, in-
cludmg the two eye-spots, soon after
which the young animal escapes from
its shell.

" Almost immediately after its escape

from the egg, the young Melicerta
stretches itself out, and, everting the
anterior part of its body, unfolds several
small projecting mamillse (xxxvxr. 16),
covered -\vith large cilia, bv means of
which it floats freely away. The ciliated
mamillse at this stage of* growth are not
unlike those seen in Notommatu clavu-
lata, but they soon enlarge and become
developed into the flabellifonn wheel-
organs of the matured animal." In this
stage all the organs of the perfect animal
are present, shoNving that the creature
passes through no larval forai, and that it
is not identical with the Plygura, as Ehr-
enberg and others have thought. After
swimming about some time, a dai-k-
brown spot disappears from the posterior
part of the body, followed by the eye-
specks, when, the same writer adds, " the
animal attaches itself by the tail to some
fixed support, anddevelopes from the skin
of the posterior portion of its body a thin
hyaline cylinder, the dilated extremity
of which is attached to the supporting
object. This structui-e has already been
noticed by Dr. Mantell (^TJwughts on Ani-
malcules), though I have never seen it
so largely developed as is represented in
his figiu-es. The young animal, having
chosen a pemianent resting-place, com-
mences the formation of its singular
investing case. I have verified Dr. Man-
tell's accoimt of the position occupied
by the fii-st-foimed spheres. They are
arranged in a ling roimd the middle of
the body (xxxra. 15), and are for some
time unattached to the leaf or stem
which supports the animal. They appear
to have some internal connexion with
the thin membranous cylinder. At first
new additions are made to both extre-
mities of the enlarging ring; but the
jerking constrictions of the animal at
length force the caudal end of the cylin-
der down upon the leaf, to which it
becomes secm-ely cemented by the same
viscous secretion as causes the little
spheres to cohere." "When the ova are
discharged from the cloaca, they succes-
sively fall into the cavity of the tessel-
lated' case, where they undergo develop-
ment. I have often* found as many as
foiu- in one case in various stages of
progress. It is whilst the eggs ai'e thus
protected that the young anmials burst
their shells, swimming out at the fi"ee
extremity of the c^e as soon as they
ai'e liberated."

Genus FLOSCULARIA (XXXII. 384, 385 ; and woodcuts).— These crea-
tures possess when young two eye-spots. Several lobes .surround the head.

OF rniC I'LOSCULAHl.'KA.

ch surmounted by a pencil of long sette. These lobes arc regarded by
hrenberg as the rotary organ ; but, according to Gosse, the upper surface
of the central disc fulfils the rotatory functions. Body fuinished with a
long peduncle, by which, the animal is fixed, and the whole surrounded by
a thin diaphanous case resembling that seen in the very young Melicerta.
From its ti-ansparency this can often be detected only by colouring the
water with some pigment. Alimentary canal simple, conical. Reproductive
system resembling that of Lacinularia. Ova deposited within the case.
When viewed from above, the head of the animal resembles an Acineta.

Floscxtlahia prohoscidea. — Case cy-
lindrical, hyaline, gelatinous. Setigerous
lobes six, with short cUia surrounding a
ciliated flexible proboscis, which appears
to have an opening at its extremity.
Dujardin thinks this proboscis may be
nothing more than one of the ciliated
lobes advanced towards the centi'e. Body
ovate, with a long styliform peduncle
attached to the base of the case ; when
extended, the body and part of the foot
are protruded. Foimd upon the leaves
of Hottonia palustris. Length when ex-
tended 1-18" ; case 1-36".

F. ornata {Cercaria, M.) (xxxxt. 384,
385). — Case or envelope hyaline; very
thin at its upper extremity ; thicker, and
often with foreign bodies entangled in
it inferiorly. It ia sometimes very slug-
gish, but at others moves with consider-
able activity, often conti'acting itself very
quickly within its case. The setigerous
lobes, according to Gosse, are not the
true rotatory organs: "yet," he says,
" there is a rotatory organ — the par-
ticles of floating matter revolving in a
perpendicular oval within the mouth of
the disc. Hence I conclude that the
rotatory cilia are set on the inner sm-face
of the disc." He further adds : "When
the pencil of united tufts is in process
of expansion the hau's have a wavy,
quivering sort of motion, but when ex-
panded they remain perfectly motionless.
The two red ej^es seen in the young
animal ordinarily disappear in the adult ;
but Mr. Gosse has occasionally mef with
such specimens in which they were still
plainly visible. He has observed the
body "to be lined with a yellowish
vascular membrane, which does not ox-
snd up to the petals, but teiminates at
he neck with a free, very mobile edge,
Orming an in-cgular opening, the out-
ine of which is constantly changing by

the contraction and expansion of the
membrane. The opacity of this lining
renders it difiicult to resolve the viscera."
"Ehrenberg speaks of an oesophageal
head above the jaws; but I can see
nothing of the kind, and am inclined to
think he msij have mistaken the ever-
contracting opening of the lining mem-
brane for one." These animals are very
fond of Chlamidomonas ; and when swal-
lowing large bodies, such as NavimlcB,
they conti-act the entire body. Ehr-
enberg has numbered as many as five
ova retained within the diaphanous case
at the same time. Gosse once coimted
nine. These, as is also the case in Meli-
certa, are generally in different stages
of development, — in some the per-
fectly-formed embryo being distinctly
visible, its movements and its two red
eyes being very manifest. With a mo-
derate pressiu-e' Ehrenberg burst the shell,
which, according to Gosse, is calcareous :
the young animal crawled out with a
slight vibratory motion ; the cUia were
short and not very distinct. In the
mature animal the pedimcle is truncate
at its extremity. Upon Ceratophyllum
and similar plants. 1-108". In xl. 25
the dorsal aspect of the jaws is repre-
sented, and in 26 their frontal aspect.

Dr. Dobie writes (A.JV.JI. Oct. 1849) :
" Ehrenberg regards the Floscularia de-
scribed and figm-ed by M. Peltier, as
identical with his F. ornata. Both Du-
jai-din and Peltier foimd the rotary organ
five-lobed in the species observed in
France; so we must either hold with
Pritchard that F. ornata has sometimes
five, at others six lobes, or consider the
five-lobed species a variety of F. ornata.

My friend Mr. Hallet writes me that

he finds F. ornata with a six-lobed ro-
tary organ and no process."

The two next species and accompanying remarks are taken from a nanpr
y Dr. W. M. Dobie (A. N. H. Oct. 1849).

F. campanulata. — Case diaphanous, fringed with very long cilia : bodv nvnfn
tary organ with five flattened lobes, witliout proboscis ; tfil long, an^ termi '

2x2

676

SYSTEMATIC HISXOET

OF THE INFTJSOEIA.

nating abruptly in a transparent fila-
ment, spread out in a kind of sucker
at the point of attaeliment. Length
1-50" when extended. Egg with two red
eye-spots; contained in a large ovary.
Foimd near Chester, on Ceratophylliim
and Coufei-vae.

F. cornuta. — Case short, diaphanous,
not very distinct ; rotaiy organ furnished

with five rounded lobes, surrounded by
extremely long and delicate cilia : a short,
narrow, non-ciliated, flexible process
(comu) is attached to the outside of one
of the lobes. Egg with two red eye-
spots ; young animal -nnth ^abratile cilia
on the head, and rapidly locomotive.
Length 1-40" when extended. In same
locality as the preceding (see woodcuts).

Floscularia cornuta, Dobie.

The lobes of the rotary organ of F.
cnniiiia vesemblo veiy much those pf
F. ovnftta, but only five exist, while" in
Ihe otlior there are .lix. According to
Ehronberg the F. campamilatn is gre-
garious, whilst F. cnnnita is solitary ; the
fomior is also stronger and is more active
than the latter.

Levdio- has described a Flosnilam
under tlie name of F. appcfnMa
(Zcitaclmft fiir icissoisrhaftmc Zooloffir.
Julv 1854).' Mr.Gosse, however, believes
this to be identical with the J^. conwl"
of Dr. Dobio.

OP Tn-E HTDATINiEA.

677

FAMILY v.— HYDATIN^A.

Illoricatcd Rotifera, having the ciliated wreath divided into several lobes
or subdivisions.

In many of the genera distinct striated muscles of the voluntary type exist,
effecting the various movements and altering the form of the body. The
nutritive system usually consists of a simple conical alimentary canal without
a distinctly separated stomach (Coelogastrica) ; but a pyloric constriction exists
in Eijdatina, some Notommatce, and other forms. Notommata clavulata and
Diglena laciisti-is have special c£eca appended to their stomachs. Variously
modified cellulai- appendages, supposed to be glandular, exist in all the genera.
The ovaiium is mostly ovate and only evolves a few ova at a time. In
Notommata Mynneleo, N, clavulata, and Diglena lacustris it is very long. In
all it communicates with the cloaca, by an oviduct of varying length. The
ova vary considerably, and belong to two distinct types, respectively termed
the summer and winter ova. The former have a smooth shell, and are gene-
rally regarded as mere unimpregnated gemmas, like those of Aphides amongst
insects. The latter are hard, and often spinous, in which form M. Tarpin
regards them as constituting the genera Bursella and Eii,tlirinella (?) amongst
plants. It is amongst the members of this group that many of the interesting
researches of Dalrymple and others have been made, demonstrating the exist-
ence of dioecious animals. Amongst the Rotifera the male animals ot Hydatina
and Asplanchna are distinct from the females. They are generally character-
ized by their smaller size and by the absence of digestive organs — indicating
a brief existence, dming which the vis vita; derived from the ovum suffices to
sustain the animals in fulfiling their several functions. According to Cohn,
this absence of an alimentary canal in the males does not characterize the
male of Notommata parasitica (XXXIX. 8) ; but this is so exceptional to
all other alhed discoveries as to suggest a doubt of its correctness : at
the same time, we have scai-cely crossed the threshold of this inquiry, and
want the materials for general conclusions. Water -vascular canals, variously
modified, exist in most of the Hydatinaea. The frequent association of the
red "eye-spots" vsdth a subjacent organ, supposed to be a cerebral ganglion,
suggests sensational fimctions ; but no true nerves occur.

Some species of Syncliaita are said to evolve light and contribute to the
phosphorescence of the sea. Hydatina scnta, Diglena catellina, and Triarthra
arc sometimes so numerous as to render the pools in which they reside milliy
and turbid.

Ehrenberg's classification of this family is given at p. 478, Section Soro-
trocha, Division Polytrocha.

The first genus (ENTEROPLEA), established to receive E. hyalina, has
been shown by Leydig to have no existence, as the above animalcule proves
to be the male of Hydatina senta.

Genus HYDATINA (XXXII. 394 ; XL. 1, 2).— Eyes absent. The female
has two jaws, consisting of several teeth and a forked foot. Locomotion is
effected by the compound wheel organ and the pincer-liko foot, acted upon
by complex internal muscles. In Hydatina scnta the sexes are distinct the
Enteroplea hyalina being the male form.

Hydatina setita ( Vnrticella senta, M.)
(xxxii. .394 ; XL. 1).— Body of tlio female
conical, hvalino ; rotary or^'an coiiHisting
of a simple extenial wroatii of cilia sur-
rounding the truncate anterior extremity
of the body, and enclosing at the back

part of the head an interrupted row of
tufts of cilia supported on small hemi-
spherical projections,— the cilia of the
latter broader and longer than those of
the extenial row. Within these is a
tlurd unmternipted line of cilia. Neck

678

SYSTEJIATIC HISTOUY

OF THE INFTJSOniA.

constricted and thrown into folds or
wrinkles by transverse filamentous
muscles, hung like hoops within the
integument, to which Cohu believes
them attached only by a few interrupted
points. These muscles were regarded by
Ehrenberg as vessels. The contractile
influence of these and similar muscles
occupying the lower parts of the body is
antagonized, according to Lej'dig, by the
elasticity of the cuticle, but according to
Cohn by the pressure of the compressed
fluids of the body. Longitudinal con-
traction of the body eflected by nume-
rous muscles proceeding from the head
backwards to the centre of both sides of
the body and thence to the foot. Ehren-
berg counted nine, which number Cohn
regards as correct. The latter observed
vacuoles and what appeared to be nuclei
in the substance of the muscles, but no
transverse strise. Two bodies at the base
of the toes Ehrenberg regarded as muscles
moving those organs ; but Cohn believes
them to be glandular, secreting an ad-
hesive fluid by which the creatiu'e at-
taches itself to other bodies.

Digestive canal consisting of an oral
orifice (xl. la), buccal cavity, pharyn-
geal bulb (1 c), oesophagus (1 cZ), stomach
(1 e), intestine terminated by a cloacal
orifice at 1 /, and gastric glands. The
buccal cavity a short passage from the
mouth (1 «) (located on one side of the
head) to the pharjTix (Ic), which is large;
and, according to Cohn, a muscular mass
invests the jaws, which are complex
and not easily intei-preted, but consist of
several parallel teeth (xxxvm. 34) ar-
ranged in two sets and attached to a
complicated p^Tiform organ: respecting
the details of their form, authors differ.
A constricted passage (] d) conducts from
the phar^Tix to the stomach (1 e), which
is large and oblong ; its walls are saccu-
lated, or expanded into numerous lateral
pouches or pockets opening into the
cavity of the stomach, the whole lined
by delicate cilia (xl. 4). A naiTow
pylorus separates this organ from a short
conical intestine, the narrow extremity
of which teiTiiinatcs at the cloaca (1/),
opening near the posterior extremity of
the body on tlie opposite side to that on
which the mouth is situated ; two large
pyrifonn bodies, supposed to be glnii-
tlular, are suspended iiy nnrrow peduncles
on each side of tlie phar^nix.

Connected with the cloaca is a large
contractile vesicle (1 r/), from which
ascend two water-vascular canals (1 »),
convoluted nt intervals and givinp off

small twigs which support tremulous
tags (xl. 5). Ovarium a large pvrifonn
sac (1 h), connected with the cloa<;a by
a narrow oviduct; it consists of a thin
membrane distended by a granular fluid,
in which are seen numerous gei-miual
spots. A small body, supposed to be a
cerebral ganglion (Ik), is situated on
one side of the oesophagus, and is con-
nected with a small setigeroiLS groove on
one side of the neck by what Cohn be-
lieves to be nerves. Male : The JEkte-
roplea hydatina (xxxn. 393 ; xl. 2) of
Ehrenberg has been demonstrated by
recent researches to be the male of Hy-
datina senta. Like that of manv other
species it has no visible digestive cavity :
in general fomi it closely resembles the
female, but is much smaller. Its repro-
ductive organs consist of a retractile
penis (XL. 6 a), enclosed in a fold of the
cuticle ((5 d), the opening of which cor-
responds with that of the cloaca in the
female ; the base of the penis is sur-
roimded by a gland (6 6), above which
is the large oblong testicle containing
spermatozoa, by the side of which, at ita
lower part, are two small vesicles (6 c),
connected with the penis, and filled vrith
numerous large gi-anules. xl. 3 repre-
sents an immatui-e ovum of Hydatiria
senta, and fig. 7 the detached sperma-
tozoa from the male animal.

In most cases the female fixes itself to
a spot by its foot, and lays several eggs
upon the same place, one after another,
by sudden contractions ; sometimes,
when it is going to lay more eg^, it
returns to the original spot. In eleven
hours after the eggs were laid, vibration
of the anterior cilia was observed, by
Ehrenberg, within them ; and in twenty-
four hours the young escaped from the
shell. Many of the ova are said to have
a double shell, and leave a bright space
between the two at one of the exti-erai-
ties; similai" ova are found in other Rota-
toria, ha^^ng different shapes. In these
double-shelled ova the young are slowly
d(!veloped. Ehrenberg names them ''last-
ing eggs, or winter eggs." xxxii. 394
represent^i an animal com pletelv unfolded,
seen from the ventral surface. I'he arrows
in the alimentary canal indicate a de-
cussating or circulating movement of its
contents, produced by delicate internal
cilia, and must not be mistaken for the
motion of Monads.

II. hrachydactyla. — CyVminQfii, trun-
cated antcriorlv, and suddenly attenu-
ated at tlie base of the foot ; claws short-
On HoUom'a, Sec. 1-144".

OF THE HYDATINjEA.

679

Dujardiu would include in the genus Hydatina several Rotatoria distributed
by Ehi-enberg among other genera. He says : " Notwithstanding the presence
of a red eye-speck, we must consider as Hydatinae — 1. Notommata tuba ;
2. iV. hrachionus ; 3. N. tripus ; 4. If. clavulata," and, though doubtfully, N.
saccigera, for this species in form resembles a true Furcularia. " The Syn-
chcetce (Ehr.), characterized by their stiff setae or styles, are true Hydatinse
from their conical or campanulate form, if their jaws are really pectinated ;

but if not, they will constitute a genus apart The Distemma mcuximum,

represented by Ehxenberg with pectinated jaws, and placed as doubtful by
him in the genus Distemma, characterized by a double eye-speck, appears to
be a tnie Hydatina."

Genus PLEUROTROCHA (XXXII. 395, 396).— These have no eyes, but
possess a single tooth in each jaw, and a fui'cate foot. The rotary organ con-
sists, not of a simple wreath of ciHa, but of cilia distributed in bundles near
each other, the bundles being planted in muscular cases. In P. gibba there are
two muscles for moving the foot ; and in aU the species the globular oesophageal
head has four, acting upon two single-toothed jaws (fig. 396) ; oesophagus
short ; aHmentary canal simple, conical, having anteriorly two spherical glands.
The anus is at the base of the foot, upon the dorsal surface. The ovary is
globular. In P. leptura a contractile vesicle is seen. Organs of sensation
are not satisfactorily known, and the nervous loop in the neck of the Hydatina
appears wanting. This genus is not admitted by Dujardin.

Pletteotrocha gibha. — Tmncated
anteriorly, enlarging from the fi-ont to-
wards the base of the foot, where it is
suddenly attenuated, the toes, or claws,
short and turgid ; near the mouth is a
beak-like projection, forming an imder
Hp. xxxn. 395 is a right side view;
396 the teeth and oesophageal head dis-
sected out. Foimd with Hydatina bra-
chydactyla. 1-216".

P. constn'cta. — Elongated, conical,
head separated by a stricture ; front ob-
lique; toes sti-aight and slender. This

animalcide is very active and powerful.
Upon Ceratajihyllum. 1-144".

P. Iqjtura. — Body turgid in centi'e,front
oblique ; foot slender ; toes thin, slightly
cm-ved. Amongst Confervae. 1-144".

P. renalis (Ehr.). — Elongate, slightly
constricted in front, toes short, frontal
portion rather oblique, truncate, pan-
creatic glands kidney-shaped (renifomi).
1-240". Berlin.

P. truncata (Gosse). — Subcylindrical;
truncate behind above the toot ; toes
short, straight, slender. 1-175".

Genus PURCULARIA (XXXIII. 397, 398).— Frontal eye single ; foot
forked. Rotary organ compound. Longitudinal muscles exist in F. gibba,
and foot-muscles in three species. The a3sophagus is very short, its head has
two jaws, single-toothed (Monogomphia) in two species, but not in the others ;
alimentary canal simple (Coelogastrica), conical, with two ear-Uko glands ;
ovary distinct, except in F. gibba, which has only a contractile vesicle.
Vessels, respiratoiy tubes, gills, &c., are not recognizable. The eye in
F. Beinhardtii is placed upon a brain-like mass.

Dujardin has the following remarks on the genus Furcularia : — " The
genus Furcularia, one of the most numerous, undoubtedly requires to be
.divided after new observations, but not according to the nnraber and dis-
position of the red points, as has been done by Ehrenberg. This author has
indeed distributed some Systolides, which appear to us to have the closest
relations in form and mode of living, into eight genera " (viz. Pleurotrocha,
Furcularia, Notommata, Scaridium, Dighna, Distemma, Eosphorus, and
Thcorus) ; « but many of these are purely nominal, and require a rigid
revision.

" The following iirc Ihc principal species to be classed with certainty among

680

SYSTEMATIC HISTOUr OP THE INFtrSOEIA.

the FurculuncB-.—i. F. furcata=Dkjlena caudata (Ehr.), DhjUaa capitata,
and Furmlaria gracilis ; 2. F. marina, of the same size and form as the
preceding, but mai'ine, and distinguished further by the styles of its tail,
which are tmce as short, and by its three-toothed but acute jaws, resembling
a hook ; 3. F. fonnpata, placed by Ehrenberg among the Diglence ; 4. F.
grandis=Diglena grandis (Ehr.) ; 5. F. forficida, with which must also be
associated Distemma forjicula ; 6. F. canicula, which Ehrenberg with doubt
refers to Diglena ? aurita ; 7. F. najas, to which belong the various Systo-
lides, more or less like Uydatina in their club-shaped form and articulated
tan, such as Notommata petroniyzon, N. najas, N. gibba, and probably also
Eospliora najas, E. digitata, and E. elongata (Ehr.). We moreover refer
provisionally to the genus Farcularia several other Systolides considerably
dissimilar La form, some being very long, with two very long styles, of which
Ehrenberg makes his Notommata longiseta, and N. cequalis, and his genus
Scaridium; whilst others have an ovoid, thick body, rounded posteriorly,
truncate in front, and with a short oblique taU, which Ehrenberg calls
Notommata myrmeleo and N. syrinx.

" AU these Furcidarice, except F. marina, to which F. ReinJiardtii of Ehren-
berg must probably be added, have been found in fresh water ; but it is most
likely the number of those living in the sea are much more nimierous ; and I
have indeed myself met with three or foui- distinct species, which I have
from want of time not yet described."

Fuhculahia gibha. — Oblong, slightly
compressed, imder side flat, back convex,
toes forked, long (styliform), equal to
half the bodj' ; the eye is placed upon a
nervous ganglion over the mouth, clearly
indicating the dorsal siu'face; the OA^a-
riimi has generally one large and ripe
o'vaim. The movement of this animfil-
cule is somewhat sIoav. Found in
green water, and amongst Confervse.
1-69".

F. Reinhardtii. — Fusifonn, truncated
in front ; foot elongated, C3'lindrical, and
shortly furcate at the end ; a slight
stricture divides the body and head,
xxxiii. 397 represents an animal ex-
tended, and 398 another, conti'acted ;
the former is a side (right), the latter a
back view. Parasitic upon Ifonopyxis

(Sertidarid) geniculata, in sea-water.
1-120".

F. Forficida. — Cylindrical, obtusely
pointed in front, roimded and dentated
at the base, on the upper side ; the toes
ver}' long ; the rotary organ .appears to
have two frontal clusters of cilia near
the eye, and a wheel-like bimdle on
each side. 1-144".

F. gracilis. — Slender, cylindrical, sud-
denly attenuated at the ba^e of the
furcate foot ; toes straight, long, but
shorter tlian half the body. The rotary
organ appears disposed on six muscular
masses.

F. ccBca (Gosse). — Cylindrical ; eye
wanting, or not discernible ; toes slender,
obtuse. Length, including toes, 1-135".
Leamington.

Genus MONOCERCA (XXXIII. 399-417).— Eye single, seated upon a
ganglionic mass, cci-vical ; foot simple, styliform, resembling a taU. In two
species the vibratilc cilia ai-e distributed into about six bundles, their band-hke
longitudinal muscles and those of the foot producing locomotion ; the sides
of the oesophageal head are unequal, as also the two jaws, which have one or
two teeth ; the oesophageal tube is cui-ved and long, and the simple alimentary
canal conical, with two ear-like glands anteriorly. An ovary and a con-
tractile vesicle are evident. In two species a tube projects from the frontal

MoNOCEUCA Hatiiis {Trichoda liattus,
M. ; Ralttdiis carinatiis, Duj.). — Ovate,
obong, tnincated antciiorly, and uii-
iirmod ; foot styliform, the length of the
bodv. This creature SAvims slowly, in n

stiff manner; when stationnrv it throws
the styliform foot baclnvai-ds and for-
wards. The ovary has a reddish coloiir ;
behind it lies a roundish contractile
vesicle. The foot has a short base, with

Ol'' THE IIYDATIN.TJA.

681

a cordate iuteinal muscle, and four un-
equal bristles. Amongst Confervse, &c.
1-120".

3Iastii/ocerca carinata is regarded by
Perty aud Dujai'din as identical with
Monocerca Rattiis. Dujardin identifies
vAth this an animal he discovered and
figured (xxxvm. 22), measuring 0'147
millim., or with its tail 0-29 millim.

M. bicornis. — Ovate, oblong, ti-imcated
in front, armed with two spines; foot
styliforai, a little shorter than the body ;
the oblique oesophageal head exhibits
delicate transverse corrugations ; it has
a bent and a sti-aight jaw, with probably
three teeth in each, (xxxin. 399, an
animal seen on its right side ; 417 an-
other, contracted, and having its rat-
like tail bent.) 1-72".

M. (?) i-ak/a ( Vorticella valga, M.). —
Small, almost cubical, with distinct head,
an elevation on the back, and a conical
foot imequally forked ; the rotaiy organ,

dm-iiig contraction, shows four muscular
sheaths; and the distinct red eye is placed
upon a less distinct ganglion ; the oeso-
phageal head is not evident. 1-288".

M. hnichyura (Gosse). — Form that of
M. Rattus, but the foot short (one-fourth
of total length), slightly cui-ved, and
horizontally flattened ; a large ejQ in the
occiput, and another small one in the
breast. Length, including foot, 1-135".

M. Porcellus. — Thick and plimip ; foot
short, much cui^ed and bent imder the
body, dilated, flattened liorizontally, and
cariying a smaller spine beneath it as in
a sheath ; front and chin each ai-med
with a short shai-p spine. Length, in-
cluding foot, 1-110".

M. stylata. — Short, iii-egularly oval ;
foot a nearly straight spine, less than
one-third of total length ; eye large, red,
set like a wart on the back of the occi-
pital sac ; forehead conical, pointed.
Length, including foot, 1-170".

Genus NOTOMMATA (XXXIII. 416-421; XXXVI. 3-6; XXXVII.
27-32 ; XXXVIII. 26 ; XXXIX. 8, 9).— These have, according to Elirenberg,
a single eye upon the neck, and a bisulcate foot, resembling a forked tail.
The rotary organ compound, its cilia forming bundles on the frontal region.
Eight of the larger species have numerous muscles. Of Ehrenberg's species
eighteen or nineteen have two jaws, each furnished with a single tooth ; in
eight the jaws have many teeth. The oesophagus is mostly short, with a
simple wide conical aUmentary canal (Coelogastrica) ; in N. tuba only is there
a stomach-like diArision, with a constriction (Gasterodela) ; and in N. Myr-
meleo, N. Syrinx, and iV. clavulatci there is also a stomach-like enlarged
place, but no constriction (Gasterodela) : cascal appendages are observed only
in N. clavulata. The two ear-like anterior appendages of the alimentary
canal, regarded by Ehrenberg as pancreatic glands, exist in twenty-foxu-
species. N. Syrinx alone was observed by Ehi-enberg to contain fully-
developed ova. The water-vascular system is represented in ten species by
delicate tubes, with flexible and tremulous gills ; only three of the smaller
species have giUs. In N. Myrmeleo and N. Syrinx a broad vascirlar network
is distinct about the head. A prominent tactile tube in the neck is present
in four or five species ; in some others an opening alone is seen. The visual
point is red, except in N. Felis, where it is colourless ; a ganglion is placed
beneath the eye in twenty-six species. In N. Copeus and N. cenfrura the
brain (?) is threc-lobed, and placed over the oesophageal head ; in the rest it
consists of one or more nei-vous ganglia, situated amongst the ciliary muscles
of the frontal region. This genus is especially remarkable for the parasitical
habits of its members. They live upon other Rotatoria, upon the Poly"-astric
Infusoiia, and even -«dthin the globular masses of Volvox Glohator ; but "
says Ehrenberg, " not like a cuckoo's egg in a hedgesparrow's nest, but like
the bear and the bce-hivc, or a bird's nest in a wasp's nest." '

Dujardin has the following criticisms on this genus : — '< Five of the si)ccics
appear to be Ilydatince ; nine others, more or less distinct, ore, in our opinion
Furcularice ; three others Plciyioynathi ; some arc imperfectly knoM-n • -iiKi
only SIX, at most, offer sufficiently precise characters to retain the namo
Notommata. Such are, 1. iV. cojiem, 2. ccntrura, 3. N. brachyota 4 i\r

682

SYSTEMATIC HISTOKY OF THE INFUSORIA.

collaris, 5. N. aurita, and 6. N. ansata." To these species must be added
a seventh, called by Ehrenberg Oycloylena Lupus, and an eighth, which we
distinguish as Notommata vermicularis.

All the best observers agree that the genus Notommata requires division,
being a very defective one, and containing the elements of several genera •
but all the species now composing it must be subjected to a very careful and
individual examination before such a division can be made. Until this is
accomplished we retain the genus as adopted by Ehrenberg, observing that
the analysis of Ehrenberg's \'iews respecting it, as given in a preceding page,
win ultimately require many modifications. Some species have already been
carefully investigated by Gosse, Perty, and Leydig.

a. Subgenus Labibodon.

Notommata Myrmeleo, — ^Bodj' large,
bell-shaped; foot short, lateral; teeth
curved in a circular forceps-like manner
(xxxm. 420). There are two varieties :
in the one (var. a), a long thin oesopha-
gus, a globidar thick stomach, and a long
reciuni constitute the alimentary organs.
Ehrenberg, by pressm-e, made an ani-
malcule, whose dark stomach nearly
filled the body, disgorge two large spe-
cimens of Lynceus minutus (described
and figiu-ed in the 3£icroscopic Cabinet) ;
the animalcide afterwards vibrated away
in a lively manner. Five transverse mus-
cular bauds and fom- longitudinal ones
(a pair uniting to each of the first two
transverse ones) represent a muscular
system in this variety. In the other
(var. 6), a distinct muscvdar network is
seen at the head, but only fom' ti-ans-
verse bands and two longitudinal ones
going to the first. The red eye is much
larger in this variety, (xxxiii. 418, a
side view of the variety b : to exhibit its
organization, a small Crustacean is shown
within its stomach. Fig. 420, the man-
ducatory organs separated ; fig. 419, the
upper part of an animalcide, var. a, show-
ing the smaller eye, rotary organs, teeth,
and network.) Found in clear water, in
turf-hollows. 1-40".

Notommata 3£yrmcleo, var. mnlticeps,
according to Leydig, presents the follow-
ing features : — Tiie foot, which on a pro-
file view appears given off from a lateral
surface, projects from the abdominal
one. The rotary or^an not consisting
of separate portions, but forming a con-
tinuous wreath, which descends towards
the mouth, fonning an apparGut fissure.
On the free surface are four unsyninie-
trical lobes bearing larger setifbnn cilia.
Cuticle soft and thin, slightly acted on
by acid, whicli rendei-s it dearer ; sub-
jacent layer gi-anular and lioniogeneous.
Mnxillnrv Imnd very large. n<]soplingus
long.tliiu, folded longituliiially. Stoinncli

— One tooth in each jaw.

round, with cUiated cells : no rectum
beyond the stomach, Ehrenberg being
in eiTor on this point; debris rejected
by the mouth. A resphatory canal pro-
ceeds from each side the conti-actde sac
towards the head, being much convo-
luted and enveloped with ceU-like cor-
puscles ; a second smaller pau* follows
a similai" course, joining the larger
near the maxillarj' bulb. The smaller
have not granulai* walls, but support
numerous tags, which are absent fi'om
the larger canals. Two bauds proceed
backwards fi'om the cerebral ganglion to
a couple of fossfe on the dorsal surface,
furnished -with a bundle of setae. Eye-
speck dark -red or black. Ovary present-
ing two homs, fonning an organ like a
horseshoe, the oviduct opening at the
base of the tail. Winter ova spherical,
bristly, with a light cortical layer con-
taining clear vesicles.

N. Syrinx. — Large, beU-shaped: lateral
foot scarcely visible ; teeth curved and
bifid at the points. This species is very
similar to the former, and only distin-
guished from it by its small foot and
by the spaces within the cilia-cluster
(inouth) being convex, not concave.
Foimd in a turf-pool. 1-40".

N. kyptopus. — ^Bell-shaped, nearly glo-
bular, rather large; foot slightly pro-
minent at the middle, teeth small ; vibra-
tilo organ composed of four or five
muscular bundles ; oesophagus verv short.
1-72".

N. parasite (xxxix. 9). — Smiill, oval ;
foot short, teeth small ; rotary apparatus
three or four lobes ; 03sophagoal head
gloljose; oesophagus short; alimentaiT
caiuil stout, sunple, usually filled with
green matter. This curious auinmlciUe
lives in the globes of Volrox Glohator,
where it deposits its eggs, wliich are
therein hatched; and when of proper
ape, the creatures eat their way out
through the hollow sphere. Siunnier

01'' THE HYDATIN^A.

683

ova large, smooth ; winter ova spinous.
1-40".

According to Cohn, the male of this
species (xxxix. 8) is a small Rotifer
1-20"' in length. Body short and sac-
culai" ; two short toes, usually retracted ;
head distinguished by a slight excava-
tion, and with an ear-like lappet on
either side ; rotaiy organ furnished with
some stout imcini, in addition to the
fine cilia; phai-ynx cylindrical, contain-
ing two scalpel-like teeth, which can be
extended beyond the mouth; stomach
separated from the intestine by a con-
stiiction. A contractile vesicle above the
foot, but water-canals scarcely visible.
A cerebral ganglion, resembling a long
sac, within the head, and bearing a red
speck at its anterior extremity. Males
and females usually existing in the same
Volvox. We have considerable doubts
respecting the coiTsctness of the above
accoimt, since it diiiers so widely from
what has elsewhere been observed
amongst such male animals as have
hitherto been discovered amongst the
Rotifera. The absence of a complete
alimentary canal has hitherto character-
ized all male Rotifera. (The female is
represented after Cohn in xxxix. 9.)

N. petromyzon. — Elongated, attenu-
ated at both ends; mouth and rotary
organ lateral. Ehrenberg says, in May
1835 he found one in a Volvox Glohator,
whose gemmiferous masses it eats like
N. parasitica. The eggs are often de-
posited on Episiylis. 1-180" to 1-144".

N. lacimdata (^Voi-ticella atiriculata et
arcinulata, M.). — Small, conical, trun-
cated and slightly lobed in front ; teeth
extended, often bicuspid. Alimentaiy
canal, according to I^eydig, clearly sepa-
rable into a gi'eenish yellow stomach
and a clear intestine. This species is
very active. Found with Chlamidovionas
Pidvisculits in clear water, also in water-
tubs. 1-280".

1^ . forcipata. — Small, elongated; toes
long, and often crossed ; eye very large.
The vibratile organ appears sometimes
like a simple wreath. Amongst Lemnic.
Very common in Switzerland, according
to Perty, but with a small red eye-speck
instead of a large pale one, as described
by Ehrenberg. 1-180".

N. collaris. — Elongated, large, gradu-
ally attenuated at botli ends ; neck tur-
gid; toes short. It sAvims slowly, the
vibratile organ being small in comparison
with the body. 1-48".

N. Weriicckii — Elongated, gradually
attenuated at both ends; toes short, ft

has two setffi near the mouth. This
animalcule resembles N. collaris, but is
smaller, and lives in the club-like ex-
crescences of Vauchcria as an entophyte.
1-90".

N. Najas. — Conical, cylindrical, stout,
truncated in front ; no auricles. It re-
sembles Hydatina senta and Eosphora
Najas ; it is distinguished from the first
by its ceiwical eye, from the latter by the
want of fi-ontal eyes. Amongst Lemnte.
1-120".

N. aurita (xxxvi. 3-6). — Described by
Mr. Gosse as cylindrical, but frequently
pyriform. Head obliquely trimcate, belly
nearly sti-aight, posterior extremity pro-
duced into a retractile foot (xxxvi. 4 li)
with two pointed toes, which organ,
being anterior to the cloaca, is not a
tail. An oval mark on each side of
the head, from which the animal can
suddenly project a semiglobular lobe
by evohition of the integument (xxxvi.
4 a), each lobe fi-inged with cilia, fonn-
ing a locomotive organ; fringe of cilia
extending across the fi'ont of the face
as far as the constriction of the neck.
MaxiUaiy bulb or gizzard (4 b) large,
oval, nearer the ventral than the dorsal
side, having imbedded within it a pair
of complex jaws (xxx-^t:. 6 *). A duct
leads from the maxillary bulb to the
continuation of the alimentary canal,
which is wide, subcylindrical, tapering
towards the anus, not divided by any
constriction, but at once stomach and
intestine ; walls thick, probably cellular.
Cloaca between the projecting point
(xxxAa. 3) and the foot. Ovary large,
occupying the ventral region; some-
times long and clear, containing trans-
parent globules (4 /), at others gra-
nulated (xxxvi. 3). A large developed
egg (4o) often occupying a gi'eat por-
tion of the abdominal cavity. Eggs largo,
covered with short flexible spines. IMale
unknown. Water-vascular system con-
sisting of two sets of tortuous vessels,
commencing at the cloaca, (6 a) and
terminating at the head, and bearing
tremulous tnga. Parnllel with the oeso-
^ihageal bidb, but nearer the dorsal sur-
face, is a large lobulated subglobose
mass of dense matter (4 q), white by
reflected light, but opaque and hence
appearing black by transmitted light
occupynig the bottom of a deep cylin-
drical snc. A tube runs through the
centre of this sac towards the rotarv
organ, "on which it opens, or at Ica-st
impinges" (Eeydig). As this opaquo
I nifiss supports the eye-spot, Gosse re-

684

SYSTEMATIC HISTORY OF THE INFUSOttlA.

gards it as cerebral. Muscular system
complex (xxxvi. 5, 6). Six or seven
muscles are circular and ti-ansverse
(6 1) ; others, arranged longitudinally
(pl), are attached to various internal
viscera and to the integimient. Some go
to the occipital sac, others to the gizzard
and to the foot, effecting various motions
in all these organs. Gosse observes, " It
commonly keeps the ear-like lobes con-
cealed whilst crawling, but will often
suddenly protrade them, and in the same
instant shoot off through the water with
considerable rapidity and with a smooth
gliding motion, partially revolving on
the longitudinal axis as it proceeds."

Leydig observes that the alimentary
canal consists of two portions — stomach
and intestine. 1-70". Amongst Con-
fervcB, &c. ; also beneath ice. (xxxvi.
3-7.)

N. gihha. — ^Back swollen, front ti'un-
cated, not amicled, no cerebral sacculi
below the eye ; toes short ; the vibratile
organs compound. In old exposed in-
fusions. 1-200".

N. ansata ( Vorticella aiirita, M.). —
Tm'gid in the middle, suddenly ti-im-
cated at both ends ; the front aiuicled,
no cerebral saccidi below the eye ; toes

b. Subgenus Ctenodon'

N. elavulata. — Bell-shaped : foot coni-
cal, very short; pancreatic glands of a
club-shape. This creatm-e presents great
facility for obsendng its internal struc-
■ ture ; but the limits of this work preclude
details. Mr. Gosse kindly informs us
that he has distinctly seen in it a nor-
mal intestine terminating in the cloaca.
1-96".

N. Tuha. — Conical, tnunpet-shaped,
dilated anteriorly ; foot fiu'cate and
acute. It resemoles, in form, Stmitor
Mullen, but is more active. 1-120".

N. Bracldonus. — Dilated, nearly square,
depressed, foot slender, eggs pendidous.
This creature appears to have a shell,
but Dr. E. says it has not. Elirenberg
described his N. granulans as depositing
its eggs upon N. Bmchionus, whence he
concluded that the former, like the
cuckoo, left its young to be reared by
another creature. He found that some of
the eggs on the dorsal surface of N. Bra-
chioniis produced N. (/rannlans. Leydig
solves the mystery by aflirming that the
latter species is the male of tlie former,
the animal in this case being bisexual,
not hermaphrodite. 1-00".

'is. tripus. — Oval, subti'uncated, and
slightly auricloil in front. Dark red eye-

thick. In bog- water, amongst Conferva;.
1-120".

N. dedpietis. — Cylindrical, not au-
ricled; toes short; the ovarimn often
contains four large eggs. Perty thinks
this is only the yomig of some other
species. 1-180".

N. (?) Felis. — Small, slender ; one bom
in front ; eye colom-less ; back attenu-
ated posteriorly, and forked. 1-240".

N. (?) Tigris (Trigoda Tigris, M.)
(xxxiu. 421).— Cylindrical, cm-ved, foot
half the length of the body ; toes very
long, and cm-ved do^vnwards; it has a
little hom in front ; the eye is large and
red. Perty has found manj-^ examples
without the red eye. Amongst Oscil-
latorife. 1-72".

N. longiseta {Vorticella longiseta, M.).
— Cylindrical, truncated anteriorly ; toes
styHform, unequal, and two to four times
longer than the body. It is active, and
frequently leaps, being assisted by its
long claws, which resemble tails. Fig.
421 is a frdl-grown specimen. Entire
length 1-60".

N. cequalis {VoHicella longiseta, M.).
— Cyliudi'ical, obtuse in front ; toes sty-
liform, equal the length of the bodv.
1-120".

, — Jaws many -toothed.

speck with three chalky masses, giving
the organ a trilobed appearance. Foot
apparently trifid, but not really so, the
central lobe being only the pi-olouged
back of the .mimal. 1-200".

N. saccigcra. — Elongated, cylindrical,
attenuated posteriorly ; fork short. It
has a cmious internal pouch beneath the
eye, with a gi'oup of rounded vesicles
in front of the stomach, recalling, as
Perty observes, the pretended agglome-
ration of eyes in Theorus.

N. Copeus. — Large, attenuated at both
ends; tail small and indm-ated. This
cmious creature has a long bristle on
each side of its body ; and on each side
of the head a stout process, called by
Elirenberg an aiuicle, tringed with vibra-
tile cilia at its ends, and, like the sefee,
standing out at right angles to the bodv;
a thick gelatinous substance covers the
body; the back terminates in a some-
what hard point, which is a Ituc tail,
between which and the foot the dis-
charging opening is situated. hen
creeping, the large vibralile arms are
withdiwvn, but it vibrates ^^•ith the
frontal cilia and ])roboscis. rxxxin. 416
renrescnts the creature extended.) 1-3G".

N. ccnirura (xxxvin. 26).— Body liu-gc,

OF THE HYDATINiEA.

685

attenuated at both ends. Usually sui--
rounded by a broad gelatinous sheath,
either hyaline or filled with small aci-
cular bodies. According to Ehrenherg,
ill this sheath vegetate threads of Hy-
drocrocis ; but these could not be found
by Leydig. Sheath wanting in young
specimens. Cuticle thick, soluble in
caustic potass. Behind the middle of
the body, on each side, is a small conical
eminence (xxxvm. 266), surmoimtedby
a bunch of long setae. Rotary organ pe-
culiar, differing from Ehrenberg's repre-
sentation. Anterior cUiated exti'emity
small compared with the size of the
animal ; venti-al portion (fig. 26 d) pro-
longed in the form of a half canal or
gi'oove, constituting a kind of mider lip.
At the base of this is the mouth, com-
municating with the maxillaiy bulb and
oesophagus, and opening into a stomach
with walls composed of large cells (fig.
26/), beyond which is a restriction
separating it from the rectum (fig. 26 </).
Three sac-like organs (fig. 26 1, c) on the
hinder border of the brain (fig. 26 k) :
the centre one composed of clear vesicles
(fig. 26 c), the outer two apparently
sometimes continuous with the cerebral
ganglion. They are gi-anidar, nucleated,
and apparent with some inorganic mat-
ter, which is white by reflected and dark
by ti-ansmitted light. Ovary (fig. 26 o)
transversal ; Peiiy saw only winter ova
in it. (xxxvn. 25 exhibits a small por-
tion of the ovary in which an ovum is
fomiing, — a being the germinal spot, b a
clear space smi'ounding it, and e the
yelk-substance, xxxvni. 11. represents
a small portion of the water-vascular
canal with its tags, and fig. 12 the ter-
mination of a tag with its contained
cilium.)

N. brachyota. — Small, slightly attenu-
ated towards the ends ; no tail, auricles
very small ; it has two dark spots near
the eye ; foot forked. 1-120".

N. Pleurotrocha. — Slender, cylindrical,
not auricled : foot with very shoii; toes ;

eye obscm-e, ovate, large ; jaw with one
tooth. 1-144". Berlin, Has the foim
of Pleurotrocha.

N. vermicularis (Duj.^. — Vermifomi,
veiy contractile ; of variable form, with
a kidney-shaped red speck (xxxvm. 33),
in which is partly imbedded a white
ti-ansparent globide. 1-118". Foimd in
the Seine.

N. tardigrada (Leydig) would be re-
ferable to the genus Lindia (Duj.), had
not its author made the absence of cilia
from the head a generic character. Fi-
gm-e veimiform, roimded in fi-ont, pro-
longed behind into a short biimcinate
foot. Mouth a long fissiu'e on the under
side of the head, which is clothed with
short and delicate cilia, the only part of
the head so fiu-nished. Maxillaiy bulb
capable of being protruded. Dental ap-
paratus recalling to mind that o^ Echinus.
(Esophagus long, resembling that of iV.
eentrura. Stomach long, yellow, with-
out cilia on the free smfaces of its
parietal cells. Intestine short and cleai',
opening at the base of the foot on the
abdominal sm-face. Contractile sac -vi-
sible, giving off ti'aces of two water-
canals, but without vibratile tags. Above
the maxillary bulb the " sacculus cere-
bralis " of Ehrenherg, white by reflected
and black by ti-ansmitted light, and
soluble in liquor potasses.

N. roseola (Perty). — Body of a pale
rosy red, elongated, rounded in front.
Rotary organ foi-ming a cylindrical pro-
cess on each side of the head. Cohn
suggests that the animal may be identical
with his Lindia torulosa.
_ N. onisciformis (Pei-tj'). — Body broad
like an Oniscus, with a round lappet on
each side of the head. Jaws sti-ong,
many-toothed; tail flat, rather long.
Entire anterior extremity capable of
being reti-acted. An ear-like lappet on
each side of the head, between which
are seen the vibratile cilia. No alimen-
tary canal seen beyond tlio maxillary
bulb. Amongst Confervse and Chai-iB,"

Genus SYNCHyETA (XXXIII. 422).— Eye single, comcal ; rotary organ
of six to ten lobes, and anned with from two to four styles ; foot furcate
The strong stylos, or bristles, arc situated between the clusters of cilia and
probably act as tactile organs ; the body is vciy short, broad anteriorly, and
tapers to a point posteriorly, or is conical. Internal longitudinal muscles
exist in all the species ; those of the foot arc seen in throe species : the oeso-
phageal head is large, with singlc-toothcd jaws ; but in t\vo species only is the
whole chcwng apparatus distinctly seen. The thin oesophagus is lono- in two
species, short m the rest; it leads to a simple, ^vide, conical alimontai-A^
canal, which has two roundish, or, in one species, conical pancreatic glands

686

SYSTEMATIC HISTORY 01' THU INFUSOHTA.

The ovary is rolled up like a ball ; contractile vesicles exist in three and
glands in two species ; transverse bands (foui- to ten) are visible in two
species, and probably a respiratory tube in 8. pectinata and S. tremula, a
tremulous gill being also present in the former. The principal nervous matter
is a knotty mass sm-rounding the head of the oesophagus ; and in the middle
of it is a large, roundish, red eye. In S. pectinata three pair of ganglia and
strong nerves are also said to be seen ; but this is doubtful. Abdominal fluid
of a reddish-yellow colom-. (Por remarks on the genus, see Hydatina, p. 677.)

SvNCH^TA pectinata. — Short, conical,
with two styles and two crest-like horns
anteriorly. " Are these horns," asks

Ehrenberg, " respii'atory tubes, as in
Polyarthra, and in AnurcBa ?" The live-
liness and unifoi-m transparency of this
animalcule render it difficult to distin-
guish its various organs. The styles
arise from the muscle of the (Esophageal
head, andappear as if belonging to simple-
toothed jaws. Eye blue. Egg-yelk con-
taining heaps of red fat-globules, (xxxtn.
422, a dorsal view showing its organiza-
tion.) Amongst Confervas. 1-120".

S. Baltica.— Ovate ; rotary clusters
and styles, four each ; crest single, sessile.
This creature is supposed to occasion
phosphorescent light in the ocean. In
two samples of water received by Ehren-
berg at Berlin, from Eael, the luminous
property existed; but this species, though
present, did not evolve any light. Mi-
chaelis, however, has noticed the produc-

tion of light from this Synchceta, as did
Baker a century ago. Ehrenberg thinks
it takes place only when developmg ova.
1-100".

S. ohlongu. — Oblong, with six rotary
clusters, and four styles ; crest sessile and
single. Distinguished fi-om the follow-
ing by the form of the pancreatic glands.
Amongst Confeiwae in spring. Length
about 1-100".

S. tremula (Voi-ticella tremula, M.). —
Body ta-uly conical, with six rotary clus-
ters, fom* styles ; crest none ; gi'anules of
yelk dark colom-ed. Length about 1-160".
Mr. Gosse thinks this may be a dioecious
species.

S. mordax (Gosse). — Body conical,
subventricose; toes minute; auricles large,
pendent ; principal styles foui-, the larger
(or lateral) pair sometimes branched ; eye
rather small, brUliaut ; two pairs of pro-
trusile snapping jaws. 1-72".

Genus SCARIDIUM (XXXIII. 423).— Eye ceiwical, single, flat, lenticular,
the compound rotary organ armed in front with an uncinus or hooked bristle ;
foot forked, very long, and adapted for leaping or springing — hence the name.
(Esophageal head oblique, with unequal, double-pointed (single) teeth to the
jaws ; oesophagus short, narrow, opening into a simple, wide, conical alimen-
tary canal ; supposed glands spherical, two. Posteriorly, above the intestine,
are a ball-like ovary and a contractile vesicle. The foot has two club-shaped
muscles ; and its apparent articulations are very remai-kable. A central gan-
glion exists between the rotary lobes. Muscles mth transverse stri«. Shell
of the ovum (winter ovum ?) clothed at both ends with scattered haii-s.

ScAHiDiuM longicauda {Trichoda longi-
cauda, M.). — Foot twice as long as the
body, toes half as long as the foot ; the
animal springs or leaps quickly, by a
rapid movement of the foot ; it does not
appear to have a lorica, and is distin-
guished from all other Rotatoria by the
length and bending-in of the foot, which,
aa also the body, is covered with a stiff

skin. Behind the eye is a transverse
fold in the neck, where the head draws
itself into the body ; the foot has also a
transverse fold when it bends, (xxxin.
423, the animalcide extended, right side ;
fig. 424 the (Esophageal head, with un-
equal jaws, &c., extended by pressure.)
Amongst OscillatoriiB. Entire length of

thebody 1-72"

without the foot, 1

-216".

Genus POLYARTHRA (XXXIII. 400-402 ; XXXVIII. 30).— Eye single,
cervical ; foot absent ; provided with ciiri, or pectoral fins. The rotary organ
consists of four bundles of cilia, inserted in as many muscular sheatlis ; they
sometimes appear like the double rotary organ of a Brachionus. The form
of the body resembles Anuro'a ; but it is soft, and the rotary organ double.

01'' THE HYDATIN.EA.

687

Laterally there are two lougitudiual dorsal muscles ; the frontal region has
little horns, provided with bristles ; and upon the breast are six strong stj'les,
or barbs, forming two clusters, which move in a fin-like manner. The oeso-
phageal head has two single-toothed jaws ; oesophagus short ; alimentary
canS with a stomach-like division, produced by a constriction; supposed
pancreatic glands, two. An ovaiy exists in both species, and in one of them
a contractile vesicle ; a large fi-ontal ganglion and a round red eye indicate
the system of sensation.

The preceding genera of this family, together with two peculiar to himself,
viz. Placjiognatha and Linclia, form, in the system of Dujardin, the family
Flosculaiiens ; but the genus Polyarthra and a few others in this family of
Ehi'enberg belong to the Brachioniens of that author.

Trom the remarks of the French naturalist, it is to be inferred that he
regards the distinction between Polyarthra and Triarthra as insufEcient.

FoLY Anrym A 2}lati/2}tera (xxxviii. 30,
also XXXIII. 400-402 & 425). — Ciliaiy
■RTeath, according to Perty, not as de-
scribed by Ehrenberg and Dujardin, but
continuous and sjonmetrical, with two
eminences crowded by setse, besides
which are several long stj'lifoi-m cilia.
Near the posterior end of the body are
two fosssB with imsymmetricallyaiTaoged
setae extending from them. AJimentaiy
canal consisting of a conical oesophageal
bulb, stomach, and intestine. Stomach-
cells ciliated ; contractile sac present,
but no water-vascular system seen ; lon-
gitudinal muscles striated; abdominal
fluid yellowish-red ; ovary somewhat bi-
comate ; yelk of ovum with large reddish

fat-globules. No winter ova seen. Em-
bryo -svith bluish spots. Ova adhering to
the exterior of the bodj'' ; only one seen
at a time (Ley dig). It swims quickly,
and often leaps, like the water-flea : this
last motion is produced by the fins or
pinnee, the former by the vibratile organs.
(Figs. 400, 401, & 425 represent the P.
Trigla of authors; but Leydighas decided
that it is identical with P. platyptera.
Fig. 425 the under side while the ani-
malcule is swimming, with the pinnte
depressed ; fig. 400 a dorsal view while
leaping or springing ; and flg. 401 a side
\d_ew, right.) This creature is infested
with Colacimn. Amongst Confei-vte
1-140".

Genus DIGLENA (?). — Eyes two, frontal ; foot forked. Excepting the
foot and rotary organ, they have no external prominent organ, though some
protrude the teeth in a pincer-like manner. The oesophageal bulb has single-
toothed jaws ; the oesophagus is very short, except in D. lacustris ; aHmentaiy
canal conical, simple, in six, and constricted in two species. In aU two
glands are present, which in D. lacustris are long cylindi'ical and two-
homed ; in the rest they are spherical. The ovary in D. Iacust7-is is band-
like, in the others globose. Contractile vesicles are observed in four species.
No species is viviparous ; none carry their egg hanging to them ; transverse
muscular bands are seen in three, and in one a vascular network at the head •
tremulous tags arc found in three species, in two of which they appear as if
attached to the water- vascular-canal glands. The cerebral ganglion is more
especially developed in D. lacustris, but is indicated in all the species by the
coloured eyes.

DiGLENA lacustris. — Stout, oval, cry-
stalline ; the front straightly truncated ;
foot suddenly attenuated, in length one-
fourth of the body ; the toes one-third
the length of the foot. The transparency
of this animalcule is often a great hin-
drance to the discrimination of its internal
organs, though they are very large ; the
superficial skin is delicately shngreened.
(xxxiii. 403 a side view, left, of this in-

teresting animalcule, with a Lynceus—
see Microscopic Cabinet, pi. vii.— in its
stomach ; its curious internal organiza-
tion is clearly depicted. Often found in
gi-een-colouvod water.) 1-70".

p. ffrfvidw.— Long, slender, and cylin-
drical, obliquely truncated anteriorly
toes straight, longer than the stout foot'
1 he forked central sacculus, neax the
head, is remarkable, (xxxni. 404 an ex-

688

SYSTEMATIC HISTORY OF THE INFUSOKIA.

tended animalcule, right side ; xxxiii.
405 another, conti'aeted, with the jaws
pushed out.) 1-120" to 1-72".

D. forcipata ( Vorticella vermicularis,
Cercaria forcipata et E. vei-inicidnris, M.)
(xL. 24). — Cylindrical, slender, obliquely
truncated anteriorly ; toes decui-ved, and
longer than the stout foot. 1-110".

D. (?) aurita ( Vorticella Canicula, M.).
— Cylindi'ical, slender ; front straightly
ti'imcated, aui-icled ; foot suddenly con-
stiicted, toes small. The ti'emulous organ
observed by Corti was merely the vibra-
tile lining membrane of the anterior por-
tion of the alimentary canal. Amongst
Confei-vse. 1-160".

D. catellina (Cercaria catellina, Vorti-
cella Larva, M.). — Oblong, short, ends
ti'imcated ; foot short, and inferior. The
small size of this animalcule is unfavour-
its internal organiza-
at all seasons of the
year in open water, and in infusions
covered with a green pellicle, which is

able for observing
tion. It is found

often fiUed with its

these, when

rapidly developed by genial weatlier,
cause a miUcy turbidity in the wa<^er
1-360".

D. conura. — Ovate-oblong, straightly
ti'uncated in front, and gradually attenu-
ated to a conical foot. Amongst Oscilla-
toriiB. 1-144".

B.capitata. — Oblong, conical, obliquely
ti'uncated and dilated in front ; toes long,
without apparent base, or foot. FeeSs
upon Clilajnydomonas and Navicula.
1-300".

D. caudata (Vorticella f areata, M.). —
Elongated, conical, obliquely truncated
anteriorly, but not dUated : foot distinct,
short ; toes long. In gi-een water. 1-200".

D. {?) birapltis (Gosse). — Oblong, the
head and abdomen gently swelling ; toes

long, slender.

sti'aight,

and perfectly

even in thickness ; eyes placed close to-
gether, fi'on tally ; jaws protmsile; alimen-
tary canal very large, projecting behind
and above the gizzard, alwaj^s filled with
gi-een matter. Length, including toes,
1-110".

Genus TEIAETHRA (XXXIII. 406-408).— Eyes two, frontal; foot
simple, styliform ; breast-fins two. Beside the rotary organ, internal band-
like muscles are observed, and two bristles, or fins, which as.sist in leaping,
as in Polyarthra. The oesophageal bulb has two double-toothed jaws, as in
Rotifer ; the oesophagus is long in one species, short in the other ; alimentary
canal simple, conical or constricted, with two spherical glands. An ovary
and contractile vesicles are seen ; the eggs, when expelled, remain attached
by threads. The nervous system is indicated by the two red eyes, placed
upon ganglia. Both species often produce a milky, tui-bid appearance in the
water, when developed in masses. A tliird species is now added.

T. lotiffiseta (TricJioda, M.). — Eyes
distant ; the cirri or beards, and the foot,
are nearly three times the length of the
body. This species is distinguished from
the following one by the gi'eater length
of cirri ; by larger eyes, fm-ther removed
from each other ; by a distinct stomach,
with a constriction separating it from
the long portion of the alimentary canal ;
and, lastly, by_ its long oesophageal tube.
It is readily distinguished By its leaping
movement whilst swimming, (xxxin.
408, a youn^ animal emerging from the
egg, the cim or styles being, as yet, soft ;
407, back view of a yoimg specimen — it
shows the great separation of the eyes and
the styles, in the position they occupy

Genus RATTULUS (XXXIII. 409).— Eyes two, frontal; foot simple,
styliform ; no cin-i or beard. The organization at present discovered com-
prehends several undefined rotary muscles, an oesophageal head, ^vithout di-
stinct teeth or oesophageal tube, a simple conical alimentaiy canal, with two
round glands, an ovary, and the eyes.

when the animal is swimming ; 400 a side
(right) \aew of a full-grown specimen —
the styles ai'e advanced, prepai-atoiy to
leaping.) Found with Hydatina sentn
and Brachionus urceolaris. Length, with-
out cin-hi, 1-140".

T. mystacina (^Brachionus passus, M.). —
Eyes close together; two anterior cirri,
or bristles ; foot neaiiy double the length
of the body; jaws very soft. 1-216".
Ill water-tuDs.

T. hreviscta (Gosse). — Cylindrical ;
pectoral and caudal spines each about
one-fiftli of total length, and very slender.
Length, including foot, 1-186". Leaming-
ton.

OP THE HTDATIN-EA.

689

This genus (Itattulus, or Entulus) was established by Lamarck ; but the.
auimals included iu it by him were referred by Ehrenberg to two genera,
Mastlgocerca and Monocerca, and the tenn Rattulus conferred upon an animal
placed among Cercariis, and called by Miiller Trichoda lunaris. " The 3Ias-
ticjocerca carinata (Ehi\)," observes i)ujardin, " is described as loricated, and
enters into the family Euchlanidota ; and Monocerca Battus, without lorica, is
placed among the Hydatineea; but the beings described under these two
appellations represent but a single species, Batulus .... The Monocerca
bicoi-nis of Ehrenberg would seem to be a distinct species, by reason of the
horns with which it is armed in front."

Rattulus lunaris (Trichoda lunaris,
M.). — Small ; eyes remote from the
frontal mai'gin ; foot decm-ved, hmate.
No teeth are seen (xxxin. gi-oup 409).

In turfy pools. 1-288".

R. carinatm (Duj.) (xxxvni. 22) =
Monocerca Rattxis.

Genus DISTEMMA. — Eyes two, cervical ; foot forked ; rotary organ com-
pound. The oesophageal head supports, in three species, jaws, with two teeth
each ; in one species with more than two ; oesophagus short ; alimentary
canal simple, conical, with two spherical glands. An ovary, and in. D. (?)
marinum glands and a contractile vesicle are seen. No satisfactory details
of a water-vascular system are ascertained ; the eyes are red, except in one
species, in which they are colourless, and in all, except D. marinum, they are
situated behind the head of the oesophagus ; in that one they are anterior,
but below the rotary organ. The eggs are never attached to the parent, nor
axe they developed in large masses.

DiSTEjiMA Forjicula. — Cylindi'ico-
conical ; eyes red ; toes thick, recm-ved
and dentate at the base. The eyes are
placed at the end of a long cylindrical
nervous ganglion ; the rotary organ con-
.sists of four parts, xxxm. 411 is a side
(left) view, and fig. 410 shows the jaws
extended for seizing preJ^ Perty be-
lieves this to be identical with Furcu-
iaria Forjicula, having but a single eye.
1-120".

D. setigcj-um. — Ovato-oblong ; eyes

red ; toes setaceous and decurved.
1-216".

D. (?) marinum. — Ovato-conical ; eyes
red, close together ; foot long ; toes thick,
the length of the foot ; jaws many-
toothed. In sea-water. 1-144".

D. (?) forcipatum. — Ovato-oblong ;
eyes colourless ; foot short, with stout
toes. If the two colom-less vesicles ai-e
not eyes, it must be placed in the genus
Pleurotrocha. 1-288".

Genus TRIOPHTHALMUS (XXXIII. 412-414).— Eyes three, cervical,
sessile, in a row ; foot forked ; rotary organ compound. It has a large oeso-
phageal head, with two (single-toothed?) jaws, a long thin oesophagus, a
globose stomach-Hke protuberance, with two oval glands, and a thin intes-
' tine ; two muscles move the foot. Several small tags seen in T. dorsalis.

Triophthalmtjs dorsalis. — ^Body cry-
stalline, turgid ; central eye largest ; foot
suddenly attenuated, its length Imlf tliat
of the body. This species, in fonn, re-
sembles Notommata ansata, but in size

N. Myrmeleo. (xxxiii. 412, dorsal side of
an animalcule extended as it appears
when swimming and vibrating ; fig. 413
one in the act of unfolding itselt, and
fig. 414 another contracted.) 1-40".

Genus EOSPHORA (XXXIII. 415). — Eyes, according to Ehrenberg,
sessile, three — two frontal, one cervical ; foot forked. The rotary organ is
composed of numerous muscular portions. An cesophageul head, provided
with two single-toothed jaws, a short oesophagus, a simple conical alimentary
canal, with two ovate glands anteriorly, an ovary, somewhat extended and
a contractile vesicle, are also discoverable. Transverse bands are observable

2 T

690

STSTEMATIC HISTOEY OV THE INFUSOETA.

in two species, and tags in the third. Beside the three red-coloured eyes, a
cerebral ganglion is seen. Distinctly striated longitudinal muscles are seen
in aU.

According to Loydig, what Ehrenherg has regarded as two frontal eyes
have no claim to the name. Should this statement be confii-med, it would
become necessary to unite Eosphora with Notommata.

EosPHOEA Nqjas. — Conical, ti-anspa-
rent, not aimcled ; toes much shorter
than the foot, (xxxui. 415, an animalcule
fed upon indigo.) Amongst Confervse.
1-12".

E. cliyitata. — Conical, hyaline, not au-

ricled; toes a third the length of the
foot. Amongst Confervas. 1-96".

E. elomjata. — Elongated, almost fusi-
form, not auricled, front tinmcated ; toes
short. 1-72".

Genus OTOGLENA. — Eyes three, one being sessile and cervical, the others
pedicled and frontal ; foot furcated. This large animalcule, the sole repre-
sentative of this genus, has considerable resemblance to Notommata Myrmeleo
or N. clavulata. Eour lateral longitudinal muscles, six moving the rotary
organ, and two muscles of the foot are present ; a toothless, and apparently
jawless, (Esophageal canal leads to a somewhat thickened stomach, ending in
a very thin intestinal canal. An ovary and contractile vesicles are observed.
A vascular network at the neck represents a water-vascular system. An oval
cerebral ganglion, with two dark appendages, and a red eye, together with
two little horn-like or aiuicular frontal protuberances bearing two visual
points, represent the nervous system. This genus has not been figured.

Otoglbna papulosa. — Bell-shaped, with Volvox Glohator and Notommata
turgid, scabrous with papillse. Found Mxjrmeleo. 1-96".

Genus CYCLOGENA (XXXTY. 425, 426).— Eyes numerous (more than
three), conglomerate at the neck ; foot fiu'cate. The vibratile organ is com-
pound, and, with the internal muscles of the foot, serves for locomotion. The
oesophageal head has two single-toothed (perhaps thi-ee-toothed) jaws; oeso-
phagus very short; alimentary canal conical, simple, with two roundish
glands. An ovary and a contractile vesicle are also present. Transverse
circxilar muscles, and six pair of tremulous organs attached to the water-
vascular canals, exist. A purse-shaped dark (colourless) body in the neck,
connected by a narrow process to a large frontal ganglion, containing fi-om
six to twelve red points, of which the anterior one is most marked, possibly
indicates a system of sensation.

Cyclogena Lupus {Cercaria Liipus,

side view.) 1-120".

C. (?) eUtgans. — Ovate, not aiu-icled;
foot inferior ; toes long. 1-190".

M.). — Ovato-oblong, or conical, not
auricled ; foot terminal, and short,
(xxxiv. 425* a back view, 426 a

Genus THEORUS (XXXIV. 427-429). —Eyes numerous (more than
three), disposed in two groups at the neck ; foot furcate. A compoimd rotarj-
organ, together with two muscles of the foot, an oesophageal head, with two
one-toothed jaws, a short oesophagus, a simple conical aliinentaiy canal, with
two glands, a ball-like ovarium, and a double group of colomicss cervica
eyes, are the details of the organization at present known. _ The frontal
uncinus, or hook, is perhaps a rcspiratoiy tube. Perty doubts if Elu'enberg
is correct in his interpretation of the supposed agglomeration of the eyes m
Theorus.

Theouus vernali-i. —Toes small; no I creature is active and vehement, like that
frontal uncinus. The movement of this I of an animal of prey, (xxxiv. 42/, a back

OF THT! HYI)ATINJ3A.

691

Tiew of this animalcule extended, with
six colourless eyes in each gi-oup ; 428, a
specimen with four eyes ; 429, body con-
tracted, but jaws extended.) Amongst
Oscillatoriae. 1-140".

T. uncinatus. — Toes long, a frontal
uncinus, or hook, present. Six \-isual
points have been seen by Ehrenberg.
Amongst Oscillatorios. 1-240''

The two next genera mentioned are from Mr. Gosse, who, however, adduces
the latter one as a doubtful member of the present family.

Genus ASPLANCHNA (Gosse, A. N. H. 1850, vol. vi.) (XII. 65, 66 ;
yxx\nr 7-9 ; XXXVII. 27-32).— Eotatorial Hydatinaea destitute of foot,
intestine and anus, but possessing eyes (ocelli) and jaws ; sexes disjoined.

This new genus embraces the Eotatorial animal which Mr. Brightwell
introduced to notice as " a supposed new species of Notommata " {Fauna
Infusoria, Norfolk, 1849), and iu which he first detected the existence
of male animals distinct in organization and character from the female.
It was soon perceived that the new forms represented by Mr. Bright-
well could not belong to the genus Notommata of Ehrenberg; and the
discovery of other similar beings has led to the creation of this genus
Asjplanchna.

AsPLANCHNA BrigMwelKL — Jaws
(mandibles) one-toothed ; eye single ;
stomach oval, longitudinal; vesicle lobed,
larger ; tremidous corpuscles (gills, Ehr.)
affixed to a long filament; ovary two-
homed. Length about 1-24". (xn. 65.
66.) Males with jaws, phaiynx, and
stomach absent ; body ti-uncate. Length
about 1-40". Found at Norwich, Lea-
mington, Hampstead Heath, &c.

]\fr. BiightweU's accoimt is embraced
in the following extracts : —

" It (the female) is furnished with an
ovisac, in which the yovmg may be clearly
detected, and from which they are ex-
pelled through the sides of the animal.
Some of the young appear to differ in
form &om the others, and there appear
to be two kinds of ova, — one, and that
by far the greater number, ti-ansparent,
and hatched in the body of the parent ;
the other, more opaque, perhaps remain-
ing unhatched, or deposited till vivified
Under favourable circumstances in some
ensuing season. Shoidd this, on further
investigation, turn out to be the case,
we shall have, among the Rotifera, the
same mode of pre.servmg the ova during
the winter as is found in some of the
Entomostraca, the Daplmice for instance."

" These [the males] arc smaller than
the females, and have a pyiiform sac
below, from which there is an opening,
and which is filled with spennatozoa ;
tod they have neither jaws, nor gullet,
flor stomach ; and it would seem they
are designed, as is the case with the
males of some insects, to continue the
liftce and then to perish .... I have lately

repeatedly seen the male in connexion
with the female. He attaches himself
to her side by his sperm-tube, and re-
mains attached fi-om twenty to seventy
seconds."

For a more complete description of
these very interesting forms we may
refer the reader to the elaborate details
and figures of their organization, by Mr.
Daliymple, in the Philosophical Tram-
actions for 1849, and to Part I. p. 453
et seq. of this volume.

Notommata Anr/lica of Leydig appears
to be only Gosse's Asplanchna Bright-
welUi.

A.priodonta (Gosse). — Females : Jaws
serrated ; eyes three ; stomach hemi-
spherical, transverse; vesicle spherical,
smaller ; tremulous bodies attached to a
twisted and plicate filament ; ovary sub-
globose (xxxvi. 9 ; xxxvm. 28). I^ength
about 1-48". Males : Body acute (xxxvi.
7,8). 1-110". Found in the Serpentine
river. (Figs. 10, 11 exhibit the jaws of
the female detached.)

A. Sieboldii (Notommata Sieboldii, Ley-
dig) (xxxra. 27-32).— Females closely
resemble those of Leydig's N. Anglica
but the males differ -wadely. Female
carapanulate, no foot ; anterior extre-
mity widened ; ciliary wreath inter-
rupted by a fissure at the juouth, into
which the fine cilia descend ; two large
lobes (32 g) on the rotary organ, crowded
by setre, with two similar smaller ones •
between these, on each side, is a fossa
^vith long motionless sctre. l\Iouth open-
ing into an angular maxillary bulb
Jaws (xxxvn. 31) wth one furcate piece
2 Y 2

692

SYSTEMATIC HISTORY 01' THE INFUSOEIA.

hooked at tlie end ; on tlie inside is an
aculeate process and a ridge to wliich
strong striated muscles, worlring tlie
jaws, are attached. QEsophagus long,
its lower end highly muscidar; two
spherical glands open into the roimd
yellowish-brown stomach (32 b) ; intes-
tine absent. Walls of the contractile
vesicle (32 e), which open into the
cloaca, with a muscular network. Two
water-vascidar canals on each side, one
with gramdar walls, the other wider and
with about fifty tags (31 & 32). Cere-
bral ganglion laid across the maxillary
bulb, with a dark-red or black speck
above and behind it in the median
line. Cells of the ganglion, according
to Leydig, fusiform, and prolonged into
nervous cords. A neiTe is said to pro-
ceed from each side to the setigerous
fossa of the rotary organ, where it swells
out like a ganglion ; another nei-ve, from
its posterior surface, divides to supply the
smaller eminences on the rotary organ ;
and another pair fi'om the same sui'-
face supply the smaller eminences : but
we thinli these supposed nerves require
re-examination. Ovary horseshoe-shaped
(32 c). Male and female yoimg never si-
multaneously generated within the same

parent. Winter eggs (xxxvn. 27, 28)
spherical, usually one or two, never more
than three; yelk yello^vish-red, invested
by a thin membrane, which in turn is
sun-ounded by a thick granular tuber-
culated shell, the latter rendered pale
by potash, which partly obliterates the
tubercles. On keeping specimens in pure
water_ without nourishment, all the eggs
deposited were winter ova. Males difier
in figure (fig. 29) from females: clavate,
with four conical arms ; the two anterior
ones (29 a) the smallest. When swim-
ming, which it does on its back, these
arms are shortened. Rotary, muscular,
and nei-vous structures as in the females.
Pyrifoi-m testicle (29 c) next the con-
ti-actile sac,_ filled with spermatozoa,
amongst which are round vesicles, nu-
cleated fusiform bodies (30 b, c), curved,
nucleated, sickle-shaped objects (30 a),
and stiff, sharply-defined rod-like bodies
(30/). Duct on the abdominal siu-face
at the end of the body, and suiToimded
by_ what look like accessory glands.
Alimentai-y canal absent ; the rudimen-
tary digestive organs represented by an
irregular heap of cells behind the pos-
terior anus. Yoimg males bom alive.

Genus TAPHROCAMPA (Gosse). — Eotary organ wanting, body fusiform,
annulose ; tail forked ; gizzard oval ; mallei incui-ved, shorter than the incus,
which, is also incurved.

Taphbocampa atmulosa. — Occipital
mass opaque, white ; alimentary canal
simple, wide, cylindrical j points of tail
short, conical. 1-110".

This species is evidently allied to M.
Dujardin's Lindia torulosa, but differs
from it in the stmcture of the dental
apparatus, and of the digestive canal.

It seems to connect the genus Chato-
notus with the Hydatiufean genera No-
tommata and Furcularia ; for it has the
jaws of these larAdform Rotifera, and
the glandidar occipital mass found ui
some of them, with the form, simple
digestive canal, and manners of Chato-
notus. Found at Leamington.

We will append here two genera of the family Purculariens of Dujardin,
which that naturalist has created cither to embrace new species or to dispose
of those described by Ehrenberg which Dujardin cannot include with other
of his genera. Likewise, before commencing with the next family (Euchla-
nidota of Ehrenberg), we shall take the opportunity to detail the chai-acters
of a family discovered and named by Dujardin, viz. Albertiens.

Genus PLAGIOGNATHA (Duj.).— Body oblong, curved and convex on
one side, or cornet-shaped and obliquely truncate in front ; terminated pos-
teriorly by a more or less distinct tail, bearing two styles. Jaws with parallel
branches turned the same way, and recm-vcd towards the ciliated margin Avith
a straight central stem (fulcrum), veiy long and enlarged at its base ; eye-
specks one or two. We propose this as a genus of Furculariens.

Although possessing a curved figure, Avith a characteristic form of jaws,
Ehrenberg has distributed them in his genera Noiommata, Dighna, and

OF THE EUCnLANIDOTA.

693

Bistemivn, according to the number and disposition of their red points, and
w-ithout consideration of the chai-acters we employ.

Plagiognatha Felis. — The species
we regard as the type of this genus is
the P. Felis, called by Miiller Vorticella
Felis, but not answerable to the Notarn-
mata Felis of Ehrenberg. Its two styles
are one-fom"th of its entire length, and
are cim^ed backwards ; the back is con-
vex, abruptly trimcate behind. 1-118".

Pl. lacinulata has been classed by
Ehrenberg among the Notommatce. A
variety of this species with two eye-
specks may be refeiTed to the Distemma
setigera (Ehi\).

One must also regai'd as distinct spe-
cies oi Plagiognatha the Notommata Tigris
and the Diglena catellina of Ehrenberg.
The Diglena lacustris of the same author
also coiTesponds in form ; but its jaws
are not sufficiently described to deter-
mine its position ; whilst his Notommata
hyptopus, represented with one-toothed
jaws, analogous to those of our Furcu-
laria, appears the same as a Systolide
known to us, evidently possessing the
jaws of a Plagiognatlia.

Genus LINDIA (Duj.) (XXXIX. 1-3).— Body oblong, almost vennicular,
ai-ticulated by means of shallow transverse folds, roimded in front ; protrudes,
Avhen swimming, two small clavate organs (3 n), clothed with radiating cilia
at their extremities, and forming a retractile rotary organ on each side.
Jaws (fig. 2) composed of three pincer-like teeth. Eye-speck single, in front
of a blackish calcareous (?) sac. Two short conical toes at the posterior
extremity.

LiNDiA torulosa (Duj.). — Body red-
dish. Length 1-6'", Perty; 1-7"', Du-
jardia ; 1-8"', Cohn. Cohn, whose
amended characters of the genus we
have given above, thinks that Notom-
mata roseola may be identical ^vith this
species: the latter differs from Notom-
mata tardigrada, which it much re-
sembles, in the presence of the club-like

rotary organ. Om- author also contends,
in opposition to Dujardin, that the oeso-
phagus is ciliated. It is not, however,
quite certain that they refer to the same
animal. It is distinct from Notommata
vermicularis, which it resembles. Cohn
thiaks the genua Litidia shoidd be located
amongst PhUodinffia.

PAMILY OP THE ALBEETINA (ALBEETIENS).

Body cylindrical, vermiform, round in front, with an oblique opening, from
which a ciliated organ protnides itself, almost larger than the body ; termi-
nated posteriorly by a short conical tail. J aws in the form of hooks, simple,
or with one tooth each.

This family comprises but one genus, and one species, Albertia vermicularis
(XXXYIII. 35, 36), which is found parasitic in the intestine of Lumbrici
and snails. 1-79" to 1-47"-

The ova with their embryos are seen in its interior, in various stages of
development.

The ciliated apparatus, in advance of the mouth, is suiTounded by an
appendage in the shape of a spur (calcar).

FAMILY VI.— EUCHLANIDOTA.

• This family comprehends such Rotatoria as have a compound rotary oro-an
with more than two subdivisions, and whoso bodies are enclosed, in a hardened
lorica. The latter is very variable in fonn. Ehrenberg has remarked that it
sometimes resembles the hard carapaces of tortoises, at others the shells of
crabs. In the former case the lorica is open at the extremities ; and in the
latter, Ehrenberg supposed it to be open inferiorly in Euclilatm ; but this is

694

STSTEMATIC HISTOEY OP THE HfFUSOHIA.

denied by Cohn, whose testimony is to be relied upon. The animal contained
witliin this lorica presents the typical features of the Eotatorian class, just as
some minute Crustaceans (Entomostraca), though enclosed between bivalved
cases, retain the internal organization of their more conspicuous and shel-
less allies. The Euchlanidota are provided with the various Eotatorian
appendages — these exist as seta3, uncini, spurs, or tactile organs ; and all are
provided with the characteristic tail or foot terminating in one or two digits,
this organ being largely employed in locomotion, either as a rudder or as an
anchor. The hardened tegument forming the lorica is variously prolonged
into spines and other appendages. Sometimes these are most developed
anteriorly, at others posteriorly, whilst in Stephanops a broad expansion of
the fi'ont of the lorica is developed into a curious crystalline hood. The sur-
faces of the lorica likewise are variously sculptured and ornamented.

The eye-speck, to which Ehrenberg has attached such importance in his
subdivision of this family, possesses, as Dujardin has pointed out, less value
as a basis of classification than the Prussian observer supposed ; but if the
observations of Leydig prove correct, the organ acquires additional interest
from the discovery of a refracting body in the eyes of EvManis unisetata and
Stephanops lamellaris. Shoiild these observations be confirmed, they will do
much to remove all doubt respecting the visual character of these organs, —
doubts which are naturally suggested by the improbability of visual organs
being given to the embryo encased in the egg, whilst the matured, active,
bustling animalcule becomes deprived of them when its life seems to render
their presence most necessary. The exact nattu-e of the internal organization
of most of the Euchlanidota is yet uncertain, and requires further study;
but each fonn, when minutely examined, is found to approximate more closely
to the Eotatorian type. Thus, whilst all are provided with a muscular system,
Cohn has demonstrated that in EucManis the fibres are of the striped or
voluntary type. The same observer has also shown that Eiwhlanis dilatata
is bisexual, the males resembling those of Hyclatina and Asplanchna in being
unsupplied with an alimentary canal. These are approximations towards a
general reduction of the whole class to a common type of organization of a
higher character than was formerly thought to exist amongst Rotifera, but
at the same time very difi'erent to what was originally attributed to them by
Ehrenberg. The genus Lepaclella developes itself occasionally in such myriads,
in stagnant water, as to give a whitish tiu'bidity to it.

' Ehrenberg's arrangement of the genera is given at p. 478. Dujardin
inclades most of the genera in his family Brachioniens.

Genus LEPADELLA (XXXIV. 430-433). — Eyes absent; foot furcate.
Several trochal muscles ai-e seen, and foot ones in two species. The jaws of
the oesophageal head are single-toothed in L. ovalis and L. emarginata ; in
L. Salpina triple-toothed. The oesophagus is very short in all ; the alimen-
tary canal below is constricted, except in L. Saljyina, in which it is simple.
The ovaiy is globular in all ; in L. Salpina probably a cerebral ganglion (no
eye) exists. L. ovalis is sometimes developed in mp-iads in stagnant Avater.

Dujardin has the following criticisms on the genus Lcpadclla :— " Wishmg
to derive his generic characters too exclusively from the eye-specks, Ehren-
berg has separated all those having such specks into several genera : consti-
tuting of those Avith two eye-points the genera Stephanops and Meiopidia,
and of those with four red specks the genus SqmmeUa. But we are con-
vinced that these red points may be present or absent in the same species at .
different periods of development. We beUevo, for instance, that the LepadelM '
ovalis and S(q->ha)W2->s mtidais (Ehr.) are but a single species ; LepadeUa -

I

OF THE EUCHLANIDOTA.

ey5

Patella with or without red dots ; so also the Metopidia Lepaclella and Sqiui-
mella bractea are the same, and what we name Lepaclella rotunclata. More-
over the Squamella oblonga and Metopidia acuminata are two distinct species
of Lepadella."

' Lepadella ovdlis (Brachiomcs ovalis,
M.). — Lorica depressed, oval, not emar-
ginate, attenuated anteriorly, the ends
truncated. The alimentaiy canal of this
animalcide is generally filled with a yel-
lowish substance, except when it feeds
upon coloiu'less Monads, (xxxiv. 430, a
back view; 431, a side (right) view of a
young specimen ; 432, the lorica ; 433, the
oesophageal head.) 1-240".

L. emarginata (Brachionm Spatella et
ovalis, M.). — Lorica dej^ressed, oval,
broad anteriorly, extremities emargi-
nate. Amongst Confei-vee. Length,
without foot, 1-576".

L. (?) Salpina. — Lorica oblong, pris-
matic, obtusely triangidai', back crested,
denticulated. Amongst Confervse. Length
of lorica 1-200".

Genus DIPLAX (Gosse). — Eesembles Salpina ; but the eye is wanting,
and the lorica (which, as in that genus, is cleft down the back) is destitute
of spines both in fi'ont and rear ; foot and toes long and slender. It forms a
connecting link between Salpina and Dinocharis. The name, signifying
double, alludes to the gaping lorica, which forms two parallel plates.

In accordance with the tabular disposition of the family, this genus foUows
next after Lepadella.

DrPLAX compressa. — Form of lorica
(■viewed laterally) nearly a parallelo-
gram, greatly compressed. Lorica 1-176".

D. trigona. — Lorica three-sided, a sec-

tion forming a nearly eqiulateral ti-iangle,
smface delicately punctm-ed or stippled ;
toes long and slender. Lorica 1-160".
Leaming-ton.

Genus MONOSTTLA (XXXIY. 434-437). — Eye single, cervical; foot
simple, styliform ; lorica (testula) depressed, ovate. Numerous muscles have
been noted in two species — the oesophageal head has four- muscles ; in one
species the jaws are single-toothed, in the other two-toothed, (Esophagus
very short ; stomach constricted (Gasterodela), with two glands. The ovaiy
is globular ; an ovum, with the vesicle of the germ vrithin it, was seen in two
species. No male organs, vessels, or respiratory tubes, are seen. Owing to
the almost constant vibration of the foot-like tail, it is difficult to observe the
true form of its termination, the motion producing an optical deception ;
hence it appears double, though in reality it is single.

MoNOSTYLA cornuta (^D'ichocla cor-
nuta, M.). — Lorica hyaline, unai-med,
and truncated anteriorly. Amongst
Charge and Confervae. 1-250".

M. quadridentata. — Lorica yellowish,
anteriorly deeply dentated, resembling
four lioms. It is generally of a yellow
leather colom*, but Ehrenberg ha-s seen
it colom-less. (xxxrv. 434 & 435, ventral
aspect; in the latter the animal is ex-
tended beyond its lorica, which happens
when the rotary cilia are in motion.
Pig. 436, a side view; 437, the jaws
and teeth separated.) In floccose matter

about Confervae and the leaves of water-
plants. 1-120".

M. (?) lunaris. — Lorica hyaline, flex-
ible, admitting the retraction of the
head, anteriorly crescent-shaped. 1-144".
Colour grey, usually so dark that no
internal organs are distinguishable. Eyes
red ; jaws Ini-ge, two-toothed; eggs few.

M. Bulla (Gosse). — Body ovate, in-
flated, the back very gibbous; lorica
plicated on each side, with a deep fiir-
roAV ; the occipital and mental deeply
incised. Colour yellowish-broNvn. Leno-th
of lorica 1-175". °

Genus MASTIGOCERCA (XXXIV. 438-440).— Dujardin and Perty be-
lieve this to be identical with Monocerca.

^ Genus EUCHLANIS (XXXIV. 441-440 ; XXXVIII. .5,18 : XXXIX. 4, 5,
7). — Lorica resembling a tortoisc-shoU ; according to Cohn not slit infciioi-ly^

696 SYiSXEMATIC HISTOHY OF THE INi'L'SOUIA.

as described by Ehrenberg. Dorsal and ventral plates united along the sides,
forming an acute ridge, leaving a fissni-e, posteriorly, for the foot. Dorsal plate
the largest. Frontal portion of the animal retractile within the lorica ; deeply
cleft on its ventral aspect, with the oral orifice at the bottom of the cleft.
Expanded anteriorly into lappets supporting hooked bristles. On either side
is a conical process terminated by a long stiff seta. QLsophagus capacious ;
jaws resembling those of Hyclatina and Bracldonus. Stomach thick and
rounded, with two small spherical glands. Intestine pyriform, ending in a
cloaca at the posterior border of the ventral plate ; both ciliated. Contractile
vesicle opening into the cloaca, sending up on each side a coiled water- vessel
with about four vibratile tags. Longitudinal muscles strong, striated. A large
trapezoid cellulo-granular organ in the head, with a red speck near its front
extremity, and on each side a long, finely granular saccular appendage. TaU
with three telescope segments, ending in two long knife-like toes.

Dujardin does not admit the genus Monostyla, but places its three species
in the present one — Etichlanis.

EuCHLANis(?) triquetra (xxxvm. 5 a).
— Lorica very large, trilateral, with a
dorsal crest ; sette on foot, none. This
species is verj' diaphanous ; and " there-
fore," remarks Ehrenberg, "I was never
able to see the line of division on the
ventral smface of the lorica. The rela-
tionship of the fibres of the lateral
muscles is physiologically and anatomi-
cally interesting : they form three bun-
dles, on each side, and show as distinct
corrugations as do the muscles of larger
animals." (xxxiv. 443, a fore-shortened
view ; 442, a left side view, showing
the dorsal crest of the lorica : at the
base of the foot an external empty fold
of the skin is visible. Eig. 441, the ven-
tral smface, showing an opening for the
foot, but no division of the lorica ;
444, the teeth and jaws separated.) In
turf-pools. Length 1-48"; ovum 1-192".
(XXXVHI. 5.)

E. (?) Ilornemanni. — Lorica thin,
short, cup-shaped, truncate in front, the
anterior part of the body soft (pliant)
and elongated. This creatm*e appeal's
able to di'aw within the lorica Doth
foot and head. Sometimes longitudinal
muscles are apparent. 1-432" to 1-240".

E. Luna ( Cercana Luna, M.). — Lorica
cup-shaped, the front excised m a lunate
maimer, toes with claws. The single-
toothed jaw, the constriction of the ali-
mentary canal, and the claws distinguisli
it from the other species. Amongst
Ceratoph/llum and ConfeiwEe. 1-144".
According to Perty, specimens occur of
a rosy red colour.

E. macrura. — Lorica large, ovate, de-
pressed; bristles at the bn.se of the foot;
toes lonff, sLyliform. This species is di- ;
stincruished from the following one bv i
its stronger and longer toes. " Lately, ' I

says Ehrenberg, " I saw the division of
the lorica along the venti-al surface."
Each jaw has five teeth; and there are
two soft maxUlaiy appendages, each with
two teeth. Amongst Confei-vse in clear
water. Length, without foot, 1-96".
Perty states that the stomach and in-
testines are sometimes red.

E. dilatata {Brachwmts, M.). — Lorica
broad, depressed, folded on the under
side ; foot without setae ; toes long.
This animalcule, when it emerges from
the egg, has a very soft lorica, and re-
sembles Notommata. Cohn states that
the males of E. dilatata are like the '
female, only smaller and more slender,
as well as more ti-ausparent from the
absence of mouth, oesophageal bulb, and
intestine. The testis of the male occupies
the centi'e of the body, and is a lancet-
like elongated sac (xxxix. 5 h), extend-
ino- from the cloaca to the cerebral
ganglion, and filled with rod-lilve sper- •
matozoa. At its posterior extremity it
is in connexion with a reuiform body
smToimding and opening into the penis.
The latter has a tluck wall and a ciliated
canal protruding as far as the first seg-
ment of the tail {?>pc). Length of
lorica 1-8"' to 1-20"' (figs. 4, 5, 7).

E. Lyuccus. — Lorica ovate, tui^id,
deeply fiuted ; two little horns project
anteriorly, (xxxiv. 445, a back view ;
and 44G, "a side view) ; the lorica is open
along the middle of the imder side.
Length of lorica 1-216".

E. dejlexa (Gosse).— Body semioval ;
ventral surface of the lorica diA-ided lon-
gitudinally, and the edges of the fissure
bent out at right angles ; foot fumished
with two pairs of bristles ; toes spindle-
sliaped. Lorica 1-80".

E. pyriformis.—OxitlmQ (viewed dor- •

OF THE ETJCHLANIDOTA.

697

sally) nearly oval, with a slight con-
striction in the middle; lorica divided
longitudinally along the ventral siu-face,
the gape -\A-idening anteriorly; toes pa-
rallel, edged ; eye minute. Lorica 1-62".

E. Hipposideros. — Nearly oval in out-
line ; the ventral side flat ; the dorsal
greatly arched, and ridged down the
middle; lorica formed of two distinct
plates ; the dorsal plate enveloping the
tack and half down the sides ; the ven-
ti-al sepai-ated from it hy a wide space,
and hollowed in the middle, so as to
present the figure of a narrow horseshoe,
whose points are forwards; foot armed
with one pau* of bristles. Lorica 1-110".

E. emarginata (Eichwald). — Distin-
guished from H. Luna by a projection at
the end of each tail-flap.

E. bicarinata (Pei-ty). — Body elon-
gated. Dorsum of lorica with two
parallel keels, rounded behind. Tail
long, with two terminal pincers; body
wide in the middle, contracted towards
each end. Middle joint of the tail very
long ; toe-segment very short. Eye
blackish-red. It is aUied to E. Weissii
of Eichwald, but distinguished by its
long figm-e and long setae of tail. 1-6'".
Perty believes that this species connects
Euchlanis with Salpina. Leydig regards
it as a Salpina.

E. unisetata (Leydig.) — Size of E. di-
latata. It has a single long bristle located
on the dorsal surface of the foot-articu-
lation ; and, according to Leydig, the eye
has a refi-acting lens (xxxvm. 18).

Genus SALPIKA (XXXIV. 447-453).— Eye single, cervical ; foot fui'cate j
lorica prismatic, with bulging sides, closed below, and term.inated by spiae-
Hke processes or teeth. " The lorica," says Ehrenberg, " resembles a tkree-
sided little casket, with arched sides, flat below, and having, anteriorly and
posteriorly, at the truncated extremities, little points." The animalcule can
entirely withdi'aw itself withia the lorica. AU the species have an elevated
ridge upon the back, which in some appears to be double. A compound
rotary organ, two short anterior lateral, and two foot muscles are seen in
S. mucronata. An oesophageal head, with three- or four-toothed jaws, a
short oesophagus, and a simple conical alimentary canal exist in aU the
species ; in five the conical intestine has two spherical glands. The ovary
is distract. A spur or tube is observed at the neck in three species ; the red
eye ia connexion with a cerebral gangHon is always present. They do not
increase in. large masses.

Salpina muci-onata (Brachionus mti-
cronatm, M.). — Lorica very minutely sca-
brous, anteriorly with foiu-, and poste-
riorly with three horns, generally sti-aight
flnd of equal length. The lonca, when
the creature is young, is soft and bent,
but soon hardens, and produces horns.
The spur, or tactile tube, in the neck,
ierminates in a little bristle, as seen in
XXXIV. 450. In some specimens, Ehr-
enberg says, the lorica appears as if
punctate or stippled. (447, 448, full-
grcwTi .specimens, with tlie head with-
drawn ; the latter figure is a back view,
the foiTuer nn under one ; 449, a side
view, head extended; 451, an egg just
deposited on Lcmna ; 452, an egg with
the young vibrating ; 450, tlie young
one just escaped from the shell ; 453,
the teeth separately.) Length of lorica
J-144". ^ ^ ^

S. apinigera. — Lorica with four IVonlnl
and three posterior liorus ; the posterior
dorsal one longest, and a little recurved.

Among Ceratophylla. Length of lorica
1-140" (xxxvin. 23, 24).

S. ventralis. — Lorica stippled, homs
two in front, three behind, the dorsal
one short and decurved. According to
Perty, a faint lens seen in the eye.
Amongst ConfervaB, &c. 1-120".

S. redunca. — Lorica smooth, horns tvfo
in fr-ont, three behind ; two of the latter
(the mider ones) hooked, the dorsal crest
bifid and gaping ; teeth four to each jaw.
Amongst Conferva). 1-200".

S. brevispina. — Lorica milky and tur-
bid, but appearing bright; scabrous,
horns two (small) in front, and three
behind, short dorsal crest not gaping;
respiratory tube uulmowu. Amongst
Ceratophijlh. 1-144".

S. bicarinata. — Lorica smooth, homs
fovu- in front, three behind, short ; neither
lateral muscles nor respiratory tubes
known. 1-216".

S. spinigera, ,S. ventralis, S. redunca
and 6'. bicarinata are probably sliglulv

698

SYSTEMATIC HISTOET OP THE ETFTTSOEU.

variaLle forma of one aucl the same
auimal.

S. mutica (Party). — Lorica toothless
both in front and behind, truncate pos-

teriorly with obtuse angles. Transparent.
Eye red. Tail-flaps extend to the root
of the tail.

Genus DINOCHAEIS (XXXIY. 454-456). — Eye single, cervical; foot
furcate ; lorica closed below, with a sharp lateral margin, but unarmed at
both ends. The compound rotary organ has five or six muscles, and in. two
species the foot two. An oesophageal bulb, with single-toothed jaws, is found,
except in D. tetractis, which Ehrenberg thinks has four teeth ; oesophagus
very short, alimentary canal constricted ; two oval glands exist in D. Focillum
and D. tetractis. An ovary is seen in all, and a contractile vesicle at the
base of the foot in B. Focillum. Traces of a water-vascular system are
perhaps to be seen m D. Pocillum, though even here it is doubtful, for the
apparently tremulous organ just behind the oesophagus may be only a tre-
mulous condition of an internal fold of the stomach. The only evidences of a
nervous system are the eye and the long ganglion which supports it.

DiNOCHAEis Pocillum (Trichoda Po-
cillum, M.). — Lorica nearly cylindrical,
with a slight dorsal ridge; two long
spines at the base of the foot, toes three,
(xxxrv. 454, 455 represent this creature
in different positions ; and 456 the (Eso-
phageal bulb.) Amongst Ceratophylla,
&c. 1-120';.

D. tetractis. — Lorica acute, triangular ;

horns two, at the base of the foot ; toes
two. This species has longer toes than
the others ; and the body is compai-atively
shorter. With Lemnte and Ceratophylla.
1-120".

D. pauper. — Lorica acute, triangular ;
homs two, at the base of the the foot,
scarcely perceptible ; toes two, short.

1-120": ^ ^ '

Genus MONUEA (XXXIV. 457-459;.— Eyes two, frontal; foot simple,
styUform. The lorica is somewhat compressed and open upon the ventral
surface : anteriorly is a hook-like process, which can be withdrawn. In one
species, the vibrattle organ has four to six muscular bulbs; in both, an
oesophageal bulb, with two-toothed jaws, a very short oesophagus, and a
simple alimentary canal with two spherical glands are observed ; an ova-
rium, with a single large ovum, has been seen. The eyes are red, moveable,
and seated upon nervous masses. The species ai-e not only difficult to di-
stinguish from each other, but also fi'om the genus Colurus, — the toes of the
latter appearing single until pressiu-e is used.

MoNUBA Colurus. — Loiica oval, ob-
tuse, obliquely tnmcated posteriorly,
eyes near to each other. Lorica 1-280".
iSiberian specimens 1-400".

M. dulcis. — Lorica ovate, anteriorly
acute, posteriorly obliquely trimcate ;

eyes distant from each other; the ali-
mentary canal is often filled with green
matter. They increase rapidly in glass
vessels, (xxxiv. 467-459 represent tliree
views of this animal.) Amongst Con-
fervse. Length of lorica 1-288".

Tlie two species of Monura are refeiTed by Dujardin to Colurus, or, to
adopt his appellation, to Colurella.

Genus COLUEUS (XXXIV. 460-462).— They have two frontal eyes, a
fui-cate foot, and a compressed or cylindiical lorica. The lorica is said to be
open upon the under side (sciitellum) ; a compound rotary organ is present in
aU, over which projects a retractile frontal hook ; an oesoi^hageal bulb with
two jaws, in two species with two or thi'ee teeth ; the cesopliagus very short ;
two species havo a constricted stomach (Gasterodela), the others have a simple
alimentary canal (Coelogastrica), all with glands. The two red frontal eyes
arc delicate ; in C. uncinatus and C. bicusjndatus thoy have escaped obscrva-

OF THE ETJCHLANIDOTA.

699

tion ; all have peculiar vesicles at the back. They resemble- ifonitm. Toot
fui'cate.

CoLUBXis (?) uncinatus (JSrachiomts
uncinatus, M.). — Lorica ovate, com-
pressed ; posterior aud bi-pointed toes,
very short ; at the middle of the back is
generally a circlet of vesicles, which at
one time Ehrenberg considered eyes, but
which he now regards as vesicles of oU,
as they aa-e seen in all the species, and
abundantly in the Cyclopida. In fi-esh
and sea water. 1-430" to 1-288".

C. (?) bicuspidatus. — Lorica ovate,
compressed ; the two points posterior,
strong J toes short. 1-288".

0. cauclatus. — Lorica ovate, com-
pressed, posterior points distinct ; toes
longer than the foot. The shell re-
sembles C. uncinatus, but the toes ai'e
much longer. In fi'esh and sea water.
Lorica 1-288".

C. deflexm. — ^Lorica ovate, compressed ;
the shell is more roimded, and very
ti-ansparent. (xxxiv. 460-462 represent
back, under, and side views ; the former
shows the vesicles.) In the clear water
of a peaty moor. 1-240".

Gemis METOPIDIA (XXXIV. 463-465).— Eyes two, frontal ; foot fur-
cate ; lorica depressed or prismatic ; the frontal portion naked or uncinate,
not provided with a hood ; indeed they may be regarded as Lepadellce with
two red frontal eyes ; the lorica, which is oval and semicircular or crescentic
in front, appears to be closed on the under side (testula). In two species the
rotai-y organ has from three to four muscles ; and in one species two foot
muscles are observed. Two species have a frontal hook, like Colurus. The
oesophageal bulb in one species has two, in another four, but in the third no
distinct teeth ; a short oesophagus and two spherical glands are present in
aU. Two species have a distinct constricted stomach (Gasterodela). An ovary
is present ; and M. triptera has a contractile vesicle. Eye, according to Leydig,
with a lens.

Metopidia ZepadcUa. — Lorica de-
pressed, nearly flat, broadly ovate, ex-
cised in a lunate manner in front,
rounded posteriorly ; toes somewhat
longer than foot. This species resembles
in form Lepadella ovalis (xxxiv. 430-
433) and Sqiiamella Bractea ; but the
former has two-toothed jaws and no
e^es ; the latter, four eyes and indi-
stinctly-toothed jaws, (xxxrv. 463^65,
back, under, and side views, the first
and last having the rotary organs ex-
tended and in motion^ 1-240".

M. acuminata. — Lorica depressed,
nearly flat, oval in shape ; anteriorly
slightly excised, posteriorly pointed.
This species resembles Colurus; but in
that genus the eyes are very close to-
gether, and the lorica open beneath.

Amongst Oscillatori£B. 1-240".

M. triptera. — Lorica oval, triangidar,
back crested : a section would resemble
xxxrv. 443. Amongst Confen^te. 1-200".

M. solida (Gosse). — Much resembles
M. Lepadella, but is considerably lai'ger ;
lorica circulai-, brilliantly transpai'ent ; a
slight pimctation siuroimds the edge,
like that on a coin. Lorica 1-150".

M. oa;ysto-wfl.— Resembles M. triptera,
but the dorsal keel is much higher and
thmner; the anterior two-thirds of the
ventral surface form a prominent ridge,
terminating abruptly like the breast-
bone of a bu-d ; and the posterior portion
is hollowed out remailcably. Viewed
laterally, the outline of the back is very
gibbous behiud. Lorica 1-175".

Genus STEPHANOPS (XXXIV. 466, 467; XL. 8-10). — Eyes two,
frontal ; foot fui'cate ; lorica depressed or prismatic, the front expanding
into a hood or transparent shield. The lorica, in two species, has thorn-like
processes posteriorly. In one species a longitudinal muscle is observed on
each side (anteriorly), two muscles for moving the foot, and from three to five
belonging to the compound rotary organ. The oesoplmgoal bulb has single-
toothed jaws, and a short oesophagus. In one species the alimentary canal
IS constricted, in the others it is simple ; two species have glands ; an ovary

700

SYSTEMATIC HISTOET OF THE nTFTTSOaiA.

exists in all ; a contractile vesicle in two. The red eyes are situated on each
side, near the frontal head in two species ; in one they are yet unknown.

The hood remains extended, even when the creatui-e withdraws within its
sheU (XL. 8-10).

Stephanops lamellaris {Brachionus
Iatnellans,M.). — Lorica with three spines
posteriorly. The rapid movement and
transparency of this animalcule renders
its organization difficult to observe. A
process extends upwards from the oral
opening and diverges into two filamen-
tous appendages. Leydig affirms that the
eye has a distinct hemispherical lens,
and that the alimentary canal is divisible
into maxillary bulb, stomach, and intes-
tine. The two latter ciliated. Also a
contractile vesicle present, (xxxrv. 466,
467, different -sdews vsdth the crystalline

hood or diadem. This hood is often
much larger tlian is represented in Ehr-
enberg's figm-es.) Amongst Confervse.
Length of lorica about 1-300".

S. (?) muticus (xL. 8-10). — Lorica
unanned posteriorly, entire. Two eyes,
red. Head and tail larger in proportion
to the trunk than represented oy Ehren-
berg. 1-144".

S. cirratiis (Srachiontis cirratus, M.).
— Lorica with two spines posteriorly.
This species has a contractile vesicle.
1-240".

Genus SQU AMELIA (XXXIV. 468, 469). — Eyes four, frontal ; foot
furcate. The lorica is closed (testula) ; the rotary organ consists of five or
six muscular bulbs. In one species the oesophageal bulb has jaws, with two
or three teeth each; its tube in one is short, in the other long and bent
like the letter S. Both have a bij^ai-tite intestine (Gasterodela), with small
glands ; also an ovary and contractile vesicle. The eyes are disposed iu pairs
on each side the brow.

SQtrAMELLAJ5racfca (BrachionusSrac-
tea, M.). — Lorica depressed, broadly
ovate. It is very ti'ansparent ; the toes
thick and short, not evident. Length of
lorica 1-144".

S. oblonga. — Lorica depressed, either
elliptical or ovato-oblong, hyaline ; toes

long and slender; eyes lai-ger than in
the foregoing species, (xxxiv. 468, 469
represent back and side views of this
animalcule.) In gi-een-colom-ed water,
with ChlamydomonasPulviscidus. Length
of lorica 1-280".

Genus KOTOGONIA (Perty). — Body covered by a lorica which dilates
posteriorly; posterior margin occupied by two pointed processes on each
side, the shorter one being dii-ected backwards and the larger one outwards.
Two eyes widely separated, on the outer margius of the anterior extremitj-.
Jaws curved, strong, with two or three teeth. Caudal setsB strong and
bristle-like.

NoTOGONiA JEh-enhergii. — Slightly tail, 1-14'". Motions rather brisk, re-
ventricose, gi-ey. Rotary organ com- senibling those of Brachionus. jVmongst
posed of a single row of cilia; eyes very Confervse.
small, pale red. Length, includuig the

FAMILY VII.— PHILODIN^A.

This family comprehends Rotatoria devoid of lorica, but possessing two
simple rotary organs, resembling wheels. The body of most species is worm-
like, or spindle-shaped (fusiform). Tortious of the body can be thnist in
and out, like the tubes of a telescope ; tliis is effected by a sort of false jomt,
caused by a peculiar insertion of the muscles. In all the species the foot is
furcate ; and in CalUdina, Rotifer, Actimu-us, and Philodina it is provided
with soft processes, neai- the false joints, resembling horns in shape, as m
the genus Binocharis (fig. 455). Muscles arc seen in the genera just named.

OF THE PHILODINJEA.

701

The nutritive apparatus consists of an cesophageal bulb, with two jaws ; in
thi-ee of Ehi-enberg's genera these are double-toothed (Zygogomphia) ; in two
the teeth are in rows (Lochogomphia). In the four principal genera the ali-
mentary canal is filiform ; it is fui-nished with a bladder- like expansion at its
commencement (Trachelocystea), and surrounded by a turbid cellular or glan-
dular mass. In one genus the alimentary canal is conical (Coelogastrica), in
the two African genera its character is unlcnown. In four genera the intes-
tine has glands ; in a like number an ovary and g:lands are present ; a con^
tractile vesicle exists only in Eotifer and PliihcUna, which, together with
Actinurus, are also sometimes viviparous. In Rotifer ani PhilocUna, portions
of a muscular system are visible, in the form of from nine to twelve trans-
verse bands ; the same genera, as also Actinurus and Monolabis, have spur-
like tactile tubes. In thirteen species red eyes are present; and beneath
these organs, only what is supposed to be nervous matter is apparent.

Por Ehrenberg's arrangement of the genera, see General History, p. 479.

" The characters employed," says Dujardin, " by M. Ehrenberg, for the
distinction of his genera of PhUodinsea, have certainly too slight a constancy
to be admitted ; that author has himself seen the red specks, which he calls
eyes, vary in number and position in his Kotifers. As to the appendages of
the taU (toes), they are not always alike visible, although actually present,
because the animal does not extend them except at certain moments ; the
central terminal appendage — that by which the Rotifers affix themselves to
sohd bodies — is itself of greater or less length, but always present. We
therefore think that but two genera can be rightly established : one, Callidina,
characterized by the feeble development of its ciliated rotary organ, and by
entirely wanting red specks; the other. Rotifer, with two or several red
points placed more or less near the exterior extremity, and, what is of more
importance, with very highly developed rotary organs."

" The genera Hyclrias and Typhlina are foimded on imperfect observations
made by the author dm-ing his journey in Egypt ; and the genus Monolabis
ought to be placed elsewhere."

The family Philodinaea thus formed is arranged parallel with Brachionaea,
as though the absence of a lorica were the only difference between them.

So far as Dujardin accepts of the same species, his family Rotifera and that
of Philodinaea of Ehrenberg correspond.

The amazing persistence of vitality in the Rotifer vulgaris gives a great
interest to this family, as also the oeciuTcnce of some of its members
within the cells of aquatic plants. Dr. Mon-en's observations probably ex-
plain some of the latter occurrences ; but it is a question whether recent
discoveries in vegetable physiology may not further explain the existence
of these animals witliin closed vegetable sacs. Por instance, the origin of
some cells by the vacuolation of a soft penetrable protoplasm suggests tho
possibility that tho Rotifera may deposit their eggs within the soft, half-
organized protoplasm ; and in the process of vacuolation some of these ova
might readily find their way into the vacuoles about to be converted into
cells, the latter change being completed before the embryonic animalcule
escaped from its ovum ; and when it did so emerge, the completion of tho
vegetable process would cause the animal to find itself imprisoned within tho
Walk of a vegetable cell.

Genus CALLIDINA (XXXIV. 470-473).— Distinguished by possessing a
proboscis, and a foot furnished with processes resembling horns, and by tho
absence of eyes. The vibratile or rotary organ, is double, not pedicled, and
w surmounted by a thicldy ciliated proboscis. The furcate foot has' two

SYSTEMATIC HISTOET OT Tin5 INPUSOEIA.

elongcated toes, foiir little horns or processes, and six points. Muscles for
moving the foot are also visible. The oesophageal bulb has two jaws, with
numerous delicate teeth. The filiform alimentary canal has a bkdde'r-hke
expansion posteriorly, but is not provided with glands : it is surrounded by a
granular and cellular mass, whose function is unknown ; Ehrenberg thinks
it connected with reproduction. An ovarium, with single large ova, is seen,
A little spur-like process projects from the neck. No indication of a nervous
system is observable.

Callidina elegans. — Spindle-shaped,
crystalline ; rotary organs, or wheels,
small, (xxxrv. 470-472 ; 473, the eggs.)
In bog- water and infusions of oak -bark.
1-72".

C. rediviva (Ehr.). — Fusiform, dif-
fusely gi'anular or else fleshy ; with red,
distinct ova, and strong rotary organs.
1-60" to 1-48" ; ova 1-576". Berlin ; in
the sediment of water-spouts of houses.

0. cornuta. — On each side of the head
a short horn-like process. Maxillary
bulb much wider behind than in C. ele-
gans. Ciliary motion unusually sti'ong

in the oesophagus. Swims in rather an
eel-like manner. C. constricta (Duj.), so
named on account of the contracted form
of its rotary apparatus. Its jaws pre-
sent a row of closely-set parallel teeth,
1-52".

C. bidem (Gosse). — Body spindle-
shaped, jaws furnished with two distinct
teeth. 1-45". Perhaps this is no other
than C. elegans, the jaws of which Ehr-
enberg describes as having many delicate
teeth. I have, however, examined nu-
merous specimens, and have always found
them distinctly two-toothed.

Genus HYDEIAS (XXXV. 474).— -It is devoid of eyes, proboscis, and the
little horn-like processes at the foot ; the two small rotary organs, or wheels,
are supported on pedicles or arms.

An oesophageal head, and an ovary, with a large ovum, have been seen by
Ehrenberg. The form is like a naked Pterodina. This genus is constructed
for an Afiican Rotatorian imperfectly observed.

Hydrias cormgera. — Ovate, hyaline;
foot attenuated, resembling a fui'cate
tail. XXXV. 474 represents an animal-
cule extended. With OsciUatoriae, in

standing water from a small spring at
Siva, in the Oasis of Jupiter Ammon.
1-190".

near Cairo in Eg}'pt, in such numbers as
to colom" the water green. 1-720".

Genus TYPHLINA (XXXY. 475).— Like the last, is an African form.
Devoid of eyes, proboscis, and horn-Uke processes at the base of the foot ;
but its little wheels are sessile. It resembles a very small Rotifer, without
frontal proboscis or eyes.

Typhlina viridis. — Body oblongo-
conical, small (xxxv. 475). Foimd by
Drs. Hemprich and Ehrenberg in a pool

Genus ROTIFER (XXXV. 476-480 ; XXXVIII. 1-3).— Body fusiform.
Able to retract and protrude its little foot with its appended boms. Eyes
two, placed upon the frontal proboscis ; foot provided with little horn-hke
(corniculate) processes, and two toes bisulcate at their apices. A double
rotary organ, furnished with muscles, is seen in aU the species ; also longi-
tudinal and foot muscles in tlu-ee of them ; a furcate foot and liom-hke pro-
cesses in four species ; in B. citrinus the pincer-like portions of the foot
appear to be tri-pointed ; in 11. en/thra;us they seemed to be di-awn in.
In four species a muscular oesophageal bulb, with jaws, each two-toothed, is
seen; in three species the alimentary canal is filiform, ynth a vesicular
expansion at the extremity, but no oesophageal tube ; it is moreover sur-
rounded by a cellular glandulose turbid mass ; another species has a corneal,
tubular aUmentary canal, without the surroimding mass or expansion at the

OP THE rniLODrN-JEA.

703

end ; the four European species have two spherical alimentary glands, and
an ovaiy, with a few lai-ge ova ; occasionally these species are viviparous.
In thi-ee of them a contractile vesicle is present. In B. macrurus, near the
alimentaiy canal are two glands. In three species from nine to twelve
parallel transverse musculai- bands have been observed ; and besides these,
in the four Eiu-opean species, styhform tubes emanate from the neck, which
in one species are cUiated anteriorly. Two red frontal eyes are met with ia
the four Eui'opean forms, and beneath them, in B. vulgaris, two ganglia.

creature attach itself by the foot, and
the rotary apparatus be in motion, a
sti'ong cm-rent or vortex is produced on
each side the wheels, resembling two
spirals in the water, which bring the
nutritive particles to the mouth, from
which some are chosen and the rest flow

RoTrFER vulgaris ( VoHicella rotatoria,
M.) (xxxv. 476-480). — Body fusiform,
white, gi'adually attenuated towards the
foot ; eyes roimd. This creature, which
was discovered by Leeuwenhoek, was
described and illustrated in the Mici'o-
scopic Cabinet some years ago, prior ^to
the appearance of Ehrenberg's observa-
tions. " It has the power of contracting
or extending the length of the body in
the following remarkable manner: —
When the creatm-e is about to shorten
itself, ti-ansverse folds or joiuts are ob-
servable, which do not appear to be con-
fined in number or situation ; the in-
teguments, when a joint is produced,
are drawn ■vsdthin the parts above, and
slide out like the tubes of a telescope,
when the joiats disappear. It is this
power that enables it to assume the
form of a sphere, the head and tail being
drawn within the body." Anteriorly it
has a proboscis-like process, with a cili-
ated exti'emity, and a soft hook, near
which are two dark red points. The body
terminates posteriorly in a moderately
long tail-like foot, having six processes
disposed in pairs; two wreaths of cilia (the
wheels), volimtarily moveable, are placed
upon short thick arms (pedicled), which
can be di'awn in and out at pleasm-e ;
these wreaths serve for swimming and
purveying, the food approaching the
mouth through the cuiTents produced in
the water by the cilia. On the dorsal
surface is a stylifonn horn {speculum
collare, M.), at the end of which Leydig
detected retractile cilia. Duiing vibra-
tion the neck has a circular fold, which
appears on each margin in a front view
liite a lateral style. Foiu" longitudinal
muscles, two anterior and two posterior,
are seen ; laterally also two, club-shaped,
for moving the foot, and two belonging
to the rotary organ. Sometimes, says
Ehrenberg, four anterior longitudinal
muscles and a dorsal and ventral muscle
appear to be present. It has two lands of
locomotion, — one by alternately attach-
ing the mouth and foot, and, as it were,
stepping along ; the other by swimming,
through the rotary apparatus. If the

away. In order to observe this action with
efiect, finely-divided caimine or indigo
must be mixed in the water. The oral
apertm-e is placed just beneath the hook-
Hke proboscis, from whence it continues
backwards as a long extensible tube, as
far as the oesophageal head, which has
foui* muscles and two striated jaws with
double teeth (Zygogomphia). From this
point a filifoim intestinal canal extends
posteriorly, fonning an oval expansion
neai- its tennination at the anus, at the
base of the taiL-like foot. A thick glan-
dular cellular mass, often yellowish or
greenish, sm-roimds the alimentary canal;
its use is unknown : anteriorly are two
biliary glands. The propagative system
is very interesting : the ovary is a glo-
bose glandulai' mass ; in it four or five
ova sometimes so completely develope
themselves that the yoimg creep out of
their envelopes, extend themselves, and
put their wheels in motion while -«-ithin
the ovary ; they sometimes occupy two-
thirds the length of the parent. In the
ovum the yoimg are coiled up in a spiral
manner. A contractile vesicle exists, and
eleven or twelve parallel transverse bands,
probably muscular. The two red frontal
eyes, with a ganglion beneath them, in-
dicate a nervous system. These eyes are
cells filled -svith a gi-anidar pigment, and
sonietinies separate abnonnafly into se-
veral ; Leydig affirms that they contain
a refracting body. (xxxv. 476, a full-
grown animal extended, and supposed
to be attached to a fixed bodj' — the
cm-rents about the troclial disc as dis-
played when indigo is put in the water ;
477, an under view, the wheels with-
drawu, and body contracted ; 478, an
extended Rotifer, wheels withdrawn •
479, 480, upper portions more highly
magnified, after submission to different
degi-ees of pressure between the plates

704

SYSTEMATIC HISTOHT OP TIIE INFUSOMA.

of a compressor. In xxxv. 476-478, ova
are seen ; some are developed, and their
eyes and oesophageal bulb visible. The
ti-ansverse muscles, and the tube pro-
jecting from the neck, are seen in the
engravings.^ Found in fresh and sea-
water, in infrisions, on the flocculent
matters of water-plants, and even within
the cells of some, e. g. of Sphagnum and
Vaiicheria, &c. (See Pai't I. p. 466.)
1-50" to 1-24".

R. (?) citrinus. — Fusiform, lower part
gi'adually attenuated into a footj its
horn-like processes elongated : eyes
round and, according to Leydig, con-
taining a refracting body ; cervical tube
toothed. The extremities are transpa-
rent, the middle of the body of a citron
colom- ; it often exhibits longitudinal
folds, and is then less ti-ansparent.
Amongst Oscillatoriffi. 1-24".

R. (?) erythreeus. — Small, oblong,
suddenly attenuated into a long foot.
1-240".

R. macrurus (Vorticella macrura, M.).
— Transparent, ovato-oblong, suddenly
attenuated into a long foot ; this is di-
stinguished from Actinurus by its small
toes, horn-like processes, and suddenly-
attenuated body. The stj'le, or antennal
tube, is ciliated in a star-like manner.
The wheels are prominent. A long
stomach is succeeded hy a short intes-
tine ; on each side is a convoluted water-
Vascular canal, but without vibratile
tags. Eyes either two, hemispherical,
abruptly trimcate anteriorly, red, and
with a refracting medium, or elongated
posteriorly, becoming divided into seve-

ral rows of linear points, without re-
fracting media. It is altogether a choice
subject for the microscope. In boo-irv
water. 1-350".

R. tardus. — Hyaline, fusiform, gra-
dually attenuated to the foot, and having
deep strictures in the form of square
false articulations or joints ; eyes ob-
long. It resembles internally R. vidqaris.
1-80".

Of the several species of Rotifer, and
of the following one of Acti?iurus, de-
scribed by Ehrenberg, M. Dujardin con-
fesses his inability to discover the specific
diiferences, although he admits diversity
of habitat, and of resistance to the pro-
cess of desiccation. He, however, be-
lieves he has discovered a Rotifer spe-
cifically distinct from any variety of
Rotifer- vulgaris ; this he would desig-
nate

R. infiatus (xxxvm. 1-3). — It is less
slender than R. vulgaris, its rotary organs
of less size, and its red speclss seated
veiy near the jaws. 1-58". In water
or wet moss.

Of this species Dujardin infers that
Ehrenberg has consti'ucted at least four
others, according to the rose or yellow
colom' it presents, the form of the eyes,
and the length of the caudal appendages,
viz. Philodina eryophthalma, P. i-oseola,
P. citrina, P. macrostyla. At the same
time he would regai'd P. coUaris, P. me-
galotrocha, and P. aculeata as distinct
forms of Rotifera.

R. ?nacroceros (Gosse). — Wheels large ;
antennal process (the respiratory tube,
Ehr.) very long and mobile. 1-100".

Genus ACTINURUS (XXXV. 481-484).— Eyes two, frontal ; foot fur-
nished with two little hom-Hke processes, and three toes. In other respects
the organization resembles Rotifer vulgaris.

AcTiNUBUS Ncptunius ( Vorticella ro- \ the case when crawling ; the antenna is
tatoria, M.). — White, fusiform, ^'adually | then seen, terminated by a single delicate
attenuated into a long foot, having three hair-like point ; 482, contracted, head
equal toes exceeding the horn-like pro- I partially withdrawn ; 484, the upper part,
cesses in length. The action of the jaws when the wheels are extended and in
in the oesophageal head is often distinctly J action; 483, the oesophagus and jaws,
seen. (xxxv. 481, an animal extended, [ separated and extended under pressure.)
with the wheels withdrawn, which is , 1-36" to 1-18".

Genus MONOLABIS (XXXV. 485, 486).— Eyes two, frontal red ; foot
with two toes, but no horn-like processes. They are pro\-ided Avith muscles
for moving the double rotary apparatus, two for moving the foot, and four
belonging to the ojsophagcal biilb and jaws, which last are furnished Avith
double teeth, or teeth in rows. A very short oesophageal tube and a simple
conical alimentary canal are seen in both species ; one of them lias two
wphci-ical glands ; an ovarium is seen in both, but in neither have fully-

OF THE PHILODIKiliA.

705

In one species, a tactile tube

different views from the under side.)
1-120".

M. gracilis. — Has a more slender body
than the last, and two teeth in each jaw,
but no tube or spui-. Length about 1-200".

developed ova or male organs been obseiTed
is present.

MoNOLABis conica. — Stout, provided
with a tactile tube, or spur, and three
teeth in each jaw. Between the rotary
organs the brow can project ajid resemble
a proboscis, (xxxv. 485, 486 represent

Genus PHILODINA (XXXY. 487-490; XXXYin. 4).— Eyes two,
cervical, foot with horn-like processes. All the species possess two vibratile
or wheel organs upon the breast, and five of them have a frontal ciliated
proboscis. Longitudinal muscles are distinct in one species, and two for
moving the foot in six. The oesophageal bulb has four muscles ; its jaws are
two-toothed in foiu- species, three-toothed in two species ; but in one species
the oesophageal bulb has not been satisfactorily seen. The alimentary canal
is filiform, with a posterior enlargement in six species ; in one it appears to
have pouches or pockets. The glandular or cellular mass smTounding the
filiform part of the canal sometimes becomes distinctly coloured when the
creature eats coloured food, and therefore seems connected with the nutritive
system, and is probably a convolution of caecal appendages. Biliary (?) glands
are found in six species. The ovary developes eggs, which are usually extruded
before the young are hatched. Three species possess a contractile vesicle ; one,
vibratile tags. A tube, in some cases ciliated, is always present at the neck.
Transverse bands are seen only in P. erythrojphtJialma. Eyes are found in
aU the species, and nervous ganglia connected with them in P. erythroph-
thalma : sometimes the eyes are very pale ; hence a solitary specimen may be
mistaken for a Calliclina. XXXVIII, 14 is a diagi-am of the head of PJiilo-
dina as viewed in front, and fig 15 of the same viewed laterally.

PHLLonrNA erythrophthalma (xxxvxn.
4). — ^White and smooth ; eyes roimd ;
hom-like processes of the foot short ;
jaws two-toothed. Found abimdantly
during the spring and summer in water-
tubs and amongst Confervae. In glass
vessels it increases rapidly ; and, if sup-
plied occasionally with two or three stems
of hay, the breed may be preserved for
years. It is often met with in vegetable
infusions of different kinds, 1-120" to
1-48".

P. roseola. — ^Body smooth ; eyes oval,
hom-like processes of the foot short.
"I have observed," says Ehrenberg, "that
this animalcule, when kept in glasses,
deposits its eggs in heaps, and the parent
remains a long time with the young ones

J produced from them, forming a sort of
amily or colony, which circiunstauce wo
are not to be hmdered from ascribing to
a sense of company or family, though the
pride of man may laugh at it." (xxxv.
490 represents one with the wheels ex-
tended.) 1-72" to 1-48".

P. collaris. — Body smooth, hyaline, or
white, eyes round ; a prominent annulus
or collar sun-ounds the neck. It is
especially characterized bv the extent of
the alimentary canal, and crecal appen-

dages attached to it ; so that, when the
animalcule is fed upon indigo, it appears
polygastric. 1-120".

P. macrostyla.— White and smooth,
with oblong eyes ; it has three teeth in
each jaw ; hom-like processes of the base
of the foot long. Found amongst Oscil-
latorise. 1-70".

P. cj^nwa.— Smooth, citron-coloured
in the middle ; exti-emities white ; eyes
variable in foim; hom-like processes
slightly elongated. Found amongst Os-
cillatorisB. 1-70".

P. aculeata. — White, provided with
soft spines eyes roimd. The tactile tube
(antenna) is thickened anteriorlv in a
globose manner; the jaws hay a each three
teeth, (xxxv. 487, 488 represent this
animalcule ; and 489 the jaws and teeth
separate.) 1-70".

P. megalotrocha.— White ; body smooth
and short ; wheels large ; the proboscis
bet^veen them long; eyes oval ; jaws two-
toothed. Two straight sette at the end
of the tail. 1-216" to 1-108".

P. hirsuta. — Of a pale yellow co-
lour, and covered with a short down •
eyes oblong; foot prolonged by dorsai
spmea ; viviparous. Lensrth 1-72" • nf
egg 1-480". Berlin. ^

2 z

706

SYSTEMATIC HISTOEY 03? THE nTFUSOEIA.

FAMILY VIII.— BRACHIOMA.

The concluding family of the Eotatoria, BRAcraoNiEA, is distinguished by-
its members having two rotary organs and a lorica.

The lorica is open at the extremities, Hke a tortoise's carapace. The rotary
apparatus is often apparently composed of five parts, three central and two
lateral ; of which the latter alone belong actually to it, the othera being only
ciliated frontal portions, which during the vibration of the trochal disc remain
stiffly extended as feelers. Besides these appendages, the disc presents in
most, perhaps in all the species, two setse, as is seen also in Synclusta. The
genera Noteus and Bracliionus have a forked foot, Anurcea is destitute of
feet ; and Ptet'oclina has a suctorial disc at the end of the foot, but no toes.
AU the genera have jaws, with teeth attached to an oesophageal head, having
four muscles. In Pteroclina the jaws are partly two-toothed and the teeth ra
a line {zygogompliia, hcliogompliia), in the other genera they are many- toothed
(volygomphia). In Notem and Pteroclina, the alimentary canal is constricted,
forming stomachs (gasterodela) ; in the rest it is partly simple (ctelogastriea),
partly with stomachs. Glands have been observed in aU the genera, as also
an ovary and contractile vesicle. Many species of Anurcea, BracMonus, and
Noteus, carry their eggs attached to them, after expulsion. In aU the genera,
except Pteroclina, internal tremulous tags attached to the water-vascular
Canals have been obseiwed. A nervous system is supposed to be indicated by
the presence of red visual points in all, except Noteits, which, however,
possesses what is believed to be a cerebral ganglion.

Some of the Brachionsea may become so numerous as to render the water
inilky and turbid.

Ehrenberg's classification of this family is given at p. 479.

It was amongst the Brachionsea that some of the most interesting of recent
investigations were first made by Perty, Cohn, and Leydig. Thus, striped or
voluntaiy muscles have been noticed in Bracliionus militaris by Cohu, and in
Pteroclina by Leydig ; whilst, in the latter case, the same distinguished
observer alleges that he finds a refracting body in the eye simUar to what he
had detected in Euchlanis and Stephanops. In Bracliionus urceolaris and
militaris, again, Perty and Cohn have established the existence of dioecious
sexuality amongst the Eotatoria — the male animal, as in the previously de-
scribed dioecious forms, being devoid of an alimentary canal ; and to this list
Mr. Gosse has since added B. Pala, B. rubens, B. ampliiceras, B. angularis,
B. Dorcas, and B. Mulleri. Its raritj-, and the compai-atively short period of
time diuing which, according to Perty, the male animalcule of Brachiomts
urceolaris exists, probably explain why these creatures have been so long over-
looked. Cohn observed that the contractions and expansions of the contrac-
tile sac at the base of the water- vascular canals of BracMonus militfiris were •
accompanied by a corresponding motion in their watery contents. At each i
contraction, or systole, a stream was expelled into the cloaca, communicating :
with the water in which the creatm-e lived, whilst an opposite movement :
attended the expansion or diastole of the sac. These facts strongly corro- -
borate the supposition that the water- vascular canals are the tnie resjiii-atory >
organs of the Rotifera, corresponding with the remarkable analogous organs >
arising from the cloaca of the Holothuria; amongst the radiated animals ; the
pure oxygenated water being thus cai-ried to the fluid distending the body,
whicli fi'ilfils the functions of the blood in higlicr animals, and affording an .
example of tho " Plilobenterism" of the Froncli naturahst Quatrefagcs.

In Bracliionus militaris,^ Cohn lia.s also pointed out the existence of tliree

OF THE BEACHION.KA.

707

distinct classes of eggs — viz. -ndntcr, summer, and male ova — all diiFering in
their form and aspect.

Genus NOTEUS (XXXV. 491-494; XXXVIII. 25).— Eyes absent; foot
farcate {Brachioni wanting eyes). The two-wheeled trochal disc has between
its portions a three-lobed ciliated brow, but has no long bristle-like feelers ; it
possesses (as also does the furcate foot) distinct muscles. The lorica has spines
both anteriorly and posteriorly ; an oesophageal head with jaws having many
teeth {polygomphia), a constricted alimentary canal or stomach {gasteroclela)
with two large glands, an ovarium, and a contractile vesicle are to be recog-
nized. There is also a trace of tremulous tags, a short and thick water-
vascular tube, and a large central ganglion, lying between the muscles of the
vibratory organs. Dujardin considers the absence of eyes insufficient to
constitute this a genus apart fi'om Brachiomis.

NoTEUS quadriconiis (xxxv. 491-494 ;
xxxvni. 25). — Lorica suborbicular, de-
pressed, rough and m-ceolated, with four
spines anteriorly and two posteriorly.
Kotary organ simple, with a deep oral
fossa; three lobes on its free surface.
Alimentaiy canal as in Brachionus, A
contractile sac on the right of the cloaca
giving off two canals, each bearing three

ti-emulous tags ; a short and obscm-e
siphon between the large spines on the
fi'ont of the body. This animalcule is
large, very transparent, and of a whitish
colom\ (xxxv. 491-493 represent dorsal,
ventral, and side views ; and 494 the
jaws separate, and under pressm-e.)
Found amongst decaj^ed sedge-leaves
and OscillatoriBe. 1-120" to 1-72".

Genus (XXXV. 495-498). — BrachionEea with a single cervical

eye, but no foot (Brctchioni without feet). In seven species the lorica has
four longitudinal rows of facettes upon the back ; in three it is smooth ; in
thirteen species it is spinous anteriorly, and in seven posteriorly also. A.
hiremis has a moveable spine on each side : of one species, only the empty
sheU has been seen ; in the rest the muscles of the rotary organ, but not the
longitudinal muscles of the body, have been observed. Jaws and teeth are
seen in nine species. Alimentary canal constricted {gasteroclela) in four ;
simple and conical (ccelogastrica) in nine. Two glands are placed at the
commencement of the ahiientary canal ; an ovary is seen in twelve species,
but a contractile vesicle only in one of the larger and smooth species, in which
also four tremulous tags are found. In thi-ee species siphons emanate from
the neck. The eye-speck, which is always present, is supposed to indicate
the existence of a nervous system. In A. squamula, A. curvicornis, A. hiremis,
A. striata, and A. foliacea, what is thought to be nervous matter is seen below
it. Eight species have their eggs attached to them after they are expelled.
I They swim freely, though not very quickly. This genus has the name of
I. Anourella, given to it by Bory St.-Vincent, and retained by Dujardin.

a. Species jjosteriorly devoid of spines and pedicle.

AmjuJEA (?) quadridentata. — Lorica
oblong, with four horns anteriorly, its
postenor end obtuse, back tessellated.
1-21G" without the horns.

A. Squamula (Brachionus Squaimtla,
' M.). — Smooth, obtusely square, with six
horns in front, obtuse behind, (xxxv.
! 495-497 represent diflerent views of this
animalcule, the two latter with an egg
attached.) 1-240".

A..falcata. — Oblong ; with six spines
anteriorly, the two central of which arc

curved outwai'ds, like sickles. Surface
of the lorica not ridged, but rough ; pos-
terior extremity obtuse. 1-144".
_ A. curvicornis. — Nearly square, with
six frontal horns, the two middle ones
larger and curved outwai-ds and do^vn-
wards. Dorsal sm-face tessellated; its
large, red, round eye is seated upon a
large nervous ganglion ; the oesopliagcal
bidb has three-toothed jaws. This ani-
malcule also can-ies the eegs attached
1-21G".

2z2

708

SYSTEMATIC HI8T0ET OP THE INPtJSOaTA.

A. biremis. — Linear and elongated,
with four horns anteriorly; back very
smooth, and having two lateral spines,
like oars. The oesophageal head has
three-toothed jaws. In phosphorescent
sea-water. 1-144".

A. striata {Brachionus striatm, M.). —
Linear and elongated, with six horns in
front, and fom- on the abdominal surface
of the loricaj the back with twelve longi-

tudinal flutings or rays, and obtuse at
the end. This species is very change-
able in fonn, owing to the membranous
lorica yielding to the contmction of the
body: hence it is sometimes long, at
others short, sometimes um-shaped, bell-
shaped, and even almost disc-shaped ;
the first, however, seems to be the normal
fonn. In fresh and salt water. 1-130".

b. Spinous or attenuated joosteriorly.

A. inermis. — Lorica oblong, attenuated
and truncated posteriorly ; no spines an-
teriorly ; back furnished with faint longi-
tudinal rays. In peat-water. Length
when extended, 1-144".

A. acuminata. — Lorica oblong, attenu-
ated and tnmcated at the posterior extre-
mity, ha-\dng anteriorly six sharp-pointed
horns or spines, twelve longitudinal rays
on the tiack. Amongst Conferrae.
Length about 1-120".

A. foliaeea. — Lorica oblong, six spines
anteriorly, posteriorly tenninating in a
spine ; dorsal and ventral sui-faces longi-
tudinally stiiated ; frontal region rough.
It has four-toothed jaws, and a central
ganglion below the eye. 1-180".

A. stipitata (Brachionus, M.). — Lorica
nearly square, or triangular; anteriorly
six spines ; posterior pointed lilce a
pedicle ; the back tessellated, (xxxv.
498 represents a dorsal view, with the
wheels extended.) Length about 1-200".

A. Testudo. — Lorica square, having
anteriorly six straight spines, aU of
nearly the same leng-th, and posteriorly
a short one at each comer. The upper
and imder surfaces are rough, the foi-mer
tessellated like Notetis, Length about
1-200".

A. serrulata. — Lorica ovate, square,
with six unequal spines anteriorly, the
two middle ones long and curved ; it has
two short spines at the posteiior angles,
which are sometimes scarcely apparent.
The surfaces are rough, and the dorsal
also tessellated, like the preceding species.
Independently of the two wheels, the
brow has three cylindrical ciliated pro-
cesses, which are truncate at their extre-
mities. 1-216".

A. aculeata (^Brachionus quadratus,
M.). — Lorica square, with six spines an-
teriorly, the two middle longest ; at the
posterior angles ai'e two long and equal
spiaes ; back rough and tessellated, under
side smooth. At the brow, between the
two wheels, is a single ciliated frontal
process ; a little tactile organ is situated
in front of the eye. Length 1-144" ;
including the spines, 1-96".

A. valga. — Lorica nearly square, with
six spines anteriorly, the two middle
ones the longest ; at each posterior angle
is a spine of unequal length ; dorsal and
ventral surfaces rough, the former tessel-
lated. The jaws ai-e five-toothed, the
red eye oval, its longer axis transverse.
Length, without the spines, 1-210".

The following species are given by Mr. Gosse (Ann. Nat. Hist. 1851, vol. viii.).

A..Jlssa (Gosse). — Lorica smooth, hya-
line, swollen at the sides and at the
hack; flatfish on the belly, truncate in
front, without any spines, attenuated
and truncate posteriorly. There is a
deep fold running down each side, or
else the ventral plate is distinct from the
dorsal ; the ventral is also cleft through
its medial line; eye very large, pale.
1-220".

A. tecta nearly agrees in form with
A. curvicornis; but the posterior extre-
mity is rather more pointed, and the
tessellations are dillereut, being larger,
and arranged on each side of a medial
dorsal ridge, which gives to the back
the form of a vaulted roof. 1-200".

A. brcvispina nearly agrees with A.
acideata ; but the posterior spines are very
short, the fi-ontal spines are much less
curved forwards, the surface is not
punctated, and it is colourless. 1-146".

A. cochkaris. — Lorica spoon-shaped,
with six spines in front, the medial pair
cm-ving strongly forwai-ds ; posterior ex-
tremity attenuated into a long slender
spine, 'inclined forwards; baclt ridged
and tessellated, as in A. tecin.

A. heptodon = Ascomoi~pha Helvetica,
Perty. — Lorica of equal width, con-
ti-acted posteriorly, and tenninated by an
upturned tooth in the middle line, in
front are four teeth above and two below.
1-12". This species, founded on onec

OF THE BfiACHIONiEA.

individual example, resembles A.foliacea,
but is less Hat, more cubical, and possesses

the pecidiar upturned tooth in the median
line, (xxxviii. 0.)

Genus BEACHIOlSrUS. — Brachionsea which have a single cervical eye and
a furcate foot. Figure compressed. Lorica closed at the sides ; open at the
extremities like a tortoise-shell. Anterior and posterior margins usually
dentate ; siuface either smooth or rough and tuberculated, the tubercles on
the abdominal surface arranged in fouz- lines diverging posteriorly. The
cuticle, which, according to Leydig, rests on a molecular layer, resists
liquor potassse. The frontal processes or teeth are dentate on their inner
edge. Animal able to withdraw itself within the lorica. Rotary organ
simple, and, though often looking as if lobed, presenting an unbroken border,
except when it is indented by descending to the mouth, whence this bilobed
aspect ; a median lobe and two lateral ones arise from its free surface. On
its right and left side are some eminences siu-mounted by long bristles, in
addition to a long bristle projecting backwards from each lateral margin of
the rotaiy organ. A granular mass, the supposed cerebral ganglion, supports
the eye-speck, which is extended backwards into two points. A siphon, or
tactile tube, terminated by a bunch of sette, projects from between the an-
terior median teeth of the lorica. Two brown vesicles in front of the large
muscular oesophageal bulb, in which are the toothed jaws ; a short oesopha-
gus ; and a stomach, the latter composed of coloured ceUs, ciliated on their
free sm-face. In front of the stomach two pedunculate glands. Intestine
clear and ciliated. Contractile vesicle on the right of the cloaca, with two
water-vascular canals proceeding from it to the neck, where they form a
plexus and bear two tags. Ovary beneath the stomach. Eggs, according to
Perty, of three sorts, viz. winter ova, summer ova, and ova bearing male
embryos. Ova attached to the exterior of the animal. B. Pala, B. urceolaris,
and B. rubens sometimes increase in such quantities as to render the water
milky and turbid. Several species are infested with Vorticella, Epistylis,
and other parasites, which attach themselves to their shells. Like Asplanchna,
Euchlanis, and others, the genus Brachionus has acquii-ed great additional
interest from the discovery amongst some of its species of the distinct sepa-
paration of the sexes. The male BracMoni present a different form to that
of the female, resembKng, in this respect, Asplanchna Sieboldii rather than
A. Bnghtwellii and Hydatina senta, in which the difference of external con-
tours is mainly one of size. The multiplying discoveries of separate sexes
amongst the Eotifera, combined with the manifest absence of male organs
in the numerous individuals provided with ovaries, renders it increasingly
probable that all the Eotifera wiU finally be demonstrated to be bisexual or
dioeceous.

Brachionus Pala. — Lorica smooth,
■with four spines in front, and two obtuse
ones near the opening for the foot. Toes
of the foot apparently bifid. This crea-
ture swims m a perpendicular position,
the brow being directed upwards. Eacli

taw has five teeth ; the alimentary canal
leing constricted, forms a stomach.
Length l-,30" : lorica only 1-48" (xxxix.
14, f5). ' .

B. amjjhiceros. — Has a smooth lorica,
with four spines, in fi-ont and poste-
riorly ; four sharp posterior teeth are
characteristic. 1-72 .

B. urceolaris (Brachiontts urceolaris,
M.).— Whitish ; lorica smooth, with six
very short spines in front; posterior ex-
tremity rounded ; lorica slightly granu-
lated ; its points arc shorter and less
shai-p than in the following species •
delicate longitudinal ridi^es proceed from'
the spines j the jaws have each five
tooth.

The males of Brachionus urceolaris,
according to Perty, are developed from
smaller ova than the females, these eggs
being also adherent to the parent in
greater numbers. They are very spho-

710

SYSTEMATIC HISTOBY

OF TILE INFTJSOEIA.

rical, reacliing 1-50"' in len^h and 1-67"'
in diameter. Their shell is more deli-
cate and the contents clearer and more
transparent, as well as of a pale yellowish
hue instead of the duslrv grey of the
female ova. The former likewise contain
fewer gi-anules. The development by
fission similar in both. When the egg
is mature, it continues to be pale and
transparent. The red eye-speck exhibits
itself ; but the maxillary apparatus, seen
in the female ovum, is wantmg. On the
other hand, two or three heaps of dark
gi-anules occur, not seen ru the females.
The embryo escapes from the ovum
by a transverse ruptm-e, and is then
seen to have a different contom' from
the female. It is but one-third the
size of the latter, being, when extended,
but 1-27"' to 1-22"' long, and from
1-60"' to 1-55"' broad. It is destitute
of a firm lorica ; short, cylindrical ; pro-
longed anteriorly into a short head,
separated by a constriction fe-om the
trunk ; prolonged posteriorly into a short
tubular foot about one-fifth the length
of the body. Head crowned by a flat-
tened disc, with a wide expanding mar-
gin, clothed with long vibrating cilia
and a few non-vibratile bristles. Cilia
moving with extraordinary velocity, pre-
venting many being seen at once ; but a
little strychnine added to the water
checks their action and facilitates theu-
observation. No mouth is present; hence
the ciliaiy wreath is not twined inwards
at the oral fissiu'e ; the alimentary appa-
ratus is wholly wanting. A large pyi'i-
form vesicular testicle, 1-100"' in length,
occupies the middle of the body ; it is
filled with small dark moving spenna-
tozoa. The wall of the testicle is vei-y
thick, and elongated at its upper extre-
mity into a thick cylindrical band, which
is attached to the cephalic disc. Pos-
teriorly the testicle is striated longitu-
dinally, and is perforated by an aperture
opening into a wide spermatic duct con-
ducting to the penis. The latter organ
is a short tube usually laid free on the
foot and nearly extending to its extre-
mity ; its internal canal and outer mar-
pin equally fm-nished with vibratile cilia.
The foot is transversely wrinkled, and
ends in two small toes. Near the root
of the penis are two club-shaped glands
which pour their secretion into its canal ;
near these is also a contractile vesicle
with two wator-cannls and tlicir ap-
endod tags. Several spherical ocll-liKe
odies occur near the licnd, — the larger
of these, the supposed cerebral ganglion,

supporting the eye-spot. Two or three
vesicles of uncertain character, filled
with dark gi-anules, rest on the testicle
near its lower end. The males are much
rarer than the females, and are not seen
after the end of May. In fresh and
brackish waters. Length of females
from 1-96" to 1-72". (xxxix. 10-20;
XL. 20-23.)

B. ruhms (B. urceolark, M.). — Lorica
smooth, with six sharp spines in front,
posteriorly rounded; the body is red,
1-50". Dujardin supposes this to be a
variety of B. urceolmts. Leydig recog-
nizes its distinctness, (xxxvm. 7.)

B. Miilleri (Miillei-^s Bradnomis). —
Lorica smooth, with six obtuse spines in
. fi'ont, two short ones behind, resembling
papillfe. This species is somewhat larger
than B. urceolm-is, and has peculiarly-
shaped fi'ontal spines. The margin of
the chin (brow) is smoothly truncate,
with three faint indentations. The lorica
is veiy ti-ansparent. 1-60". According
to Mr. Gosse, the B. hq)tatoimis found in
sea-water is identical with this species.
(XXXIX. 13.)

B. brevispt7itis. — Lorica smooth, having
six acute imequal spines in fi-out, and
fom' stout spines posteriorly, the two
inner ones short ; two sexual glands and
a conti'actile vesicle ai-e present. In
slow nmning clear water, with Con-
ferva?. 1-65".

B. BaJceri (M.). — Lorica rough, its
middle tessellated on the dorsal smface ;
six unequal acute teeth anteriorly, two
elongated (lateral and dorsal) spines
posteriorly, and short ones at the sheath
of the foot. The lorica is covered with
delicate granules ; those upon the middle
of the venti-al siuface are arranged in
pai-aUel but somewhat cm^ed lines.
1-220" to 1-60". (xxxvm. 8, 9, 10-17;
XL. 16.)

"The following interesting observa-
tions as to the development of this spe-
cies have been communicated to me by ft
friend, an accurate and diligent observ-er
of natm-e : — About two o'clock B. Ba-
licri was observed with one egg placed
externally between the two posterior
spines of the shell, and another small
egg in the left side of the animal, which
increased much in size in the course of
the day. At nine in the evening a
motion' was perceived in the extenor
egg like that of the muscular oesophagii's
of the parent; and about this time the
internal egg was protruded and iilaccd
by tlie side of the other, being longer
than it. At eleven the young Brachiontu

or THOS UUACHIONiliA.

7ii

burst with a bound from the egg in
which the motion was perceived, and
athxed itself by its tail to the lunette.
At first it had the appearance of an
oblong ball ; by degrees the anterior part
spread, and the wheel processes were
developed. Soon after, the posterior shell-
processes were visible in a semilimar
shape, with the points nearly touching
each other, which gTadually expanded.
The shell of the egg remained attached
to the pai'ent in the same position, quite
transparent, with a longitudinal split
through the whole length." (Brightwell,
op. cit.)

B. poly acanthus (M.). — Lorica smooth,
ha^ang anteriorly fom* long dorsal teeth
or spines, six short ones at the margin
of the chin ^ventral), and posteriorly
five dorsal spmes, the two external or
lateral ones veiy long. xxxv. 499-501
represent dorsal, side, and under views
of this animal, — the first having the
wheels extended, and the side view
showing the siphon or so-called respi-
ratory tube and an ovum attached.
Length, without spines, 1-110". xxxvni.
14, 15 represent diagrams of the head.

B. militaris, — Lorica with smface
divided into twelVe regular pentagonal
facettes, according to Cohn ; its anterior
border with several spinous processes;
and posteriorly is a deep median ex-
cavation with a cm-ved horn on each
side. The spines, 10 in nimiber (not 12
as affii-med by Ehi-enberg), viz. 2 lateral,
4 abdominal, and 4 dorsal, the latter the
largest ; head larger than that of JB. 7ir-
ceolaris, expanded in a funnel-shaped
manner, surroimded by a circlet of cUia ;
its eversion is checked by the stiff' spines
of the lorica. Foot smaller and shorter
than in B. urceolaris. Oesophageal bulb
quadrangular. On each spine forming
tlie outer posterior angle of the lorica is
a circular pit with well-defined nwgin ;
from this proceeds a bimch of short
bristles. Muscles of foot and head stiiped
transversely. Contractile sac very largo,
occupying two-thirds of the abdominal
cavity on the right side of the animal ;
it consists of two chambers, the ovate
posterior one being the larger, their con-
tractions being alternate ; the posterior
one opens into the cloaca by a short
duct. On mingling coloured matter with

the water, Cohn observed that on each
sj'stole or contraction a stream escaped
from the sac, through the cloacal open-
ing, and that on the diastole this move-
ment was reversed, indicating a respi-
ratoi-y action, (xxxrx. 21, 22 represent
the abdominal and dorsal surfaces of the
female.) The ova are of three sorts : —
1. Winter ova, 1-21'" long, 1-33"' wide,
elliptic, with thick, leathery, opaque
waUs, the yelk not occupying the poles
(xxxrs. 23) ; 2. Ordinary or simimer ova,
of similar dimensions, but vnth thin
transparent walls ; 3. Male ova, only
1-34"' long and 1-42"' broad (xxxrx.
24). Shell thin. Yelk subdividing in
the usual way, and developing an em-
bryo provided with a red eye, and two
dark specks, but no maxillary organs.
Cohn saw only one specimen freed fi'om
the egg, and that imperfectly. It ap-
peared similar to the male of B. ur-
ceolaris.

B. Oon (Gosse). — Lorica ovate, the
back swelling with a imifoi-m curve, by
which it is distinguished fi'om B. Pala,
which is ti'uncate or slightly clavate
posteriorly ; anterior spines fom*, straight,
wide at the base, and pointed ; the occi-
pital pail- taller than the lateral. Lorica
1-125".

B. Dorcas. — Lorica ovate or sub-coni-
cal ; occipital edge with fom- long slender
spines, the middle pair cmwing foi-wards,
and bent first from, and then towai'da
each other, like the homs of an antelope 5
mental edge imdidated, with a notch in
the centre. Lorica 1-60". (xl. 11 re-
presents a newly-bom female, and fig. 12
a newly-bom male.)

B. anrjularis. — Lorica in the female
hexagonal-oval in the dorsal aspect ; occi-
pital edge with two small teeth, divided
by a roimded notch (in some specimens
there ai-e obsolete traces of a lateral
pair) ; mental edge slightly undidated,
sometimes with two low points, divided
by a notch like the occiput, but still
more faintly; posterior exti-cmity with
two short, blunt, well-marked processes.
The general suriiice is roughened with
angular ridges, and is sometimes sub-
opaque and brown. Lorica 1-200". This
cmious species has relations with Koteus
and witli Pterodina. (xi,. 19 represents
a mule of this species. )

Genus PTERODINA. — The winged Rotatoria include sucli Rracliioncca as
have two frontal eyes and a simple styliform foot projecting from the middle
of the body. All the sjiccies have a siuootli, flat, and soft lorica, like a tor-
toiac-ehcll, with curved margins ; as also a more or less double rotajy appa-

712

SYSTEMATIC HISTOKY OF THE INFUSOKIA.

ratus, and a simple foot with a suction-disc and sometimes a birnch of cilia
at its extremity. P. elliptica has a hairy process projecting between the two
lobes of the rotary organ, and P. Patina has a rounded prominence in a similar
position on the dorsal surface. Muscles, often transversely striated, occur in
aU the species, as also a constricted alimentary canal with glandular appen-
dages and an ovarium. Some have a contractile vesicle and a water- vascular
system.

Ptebodina Patina (Brachionus Pa-
tina, M.). — Figure roimd, or oval com-

{)ressed. Lorica membranous, crystal-
ine, somewhat scabrous near its broad
mai'gin, and slightly excavated anteriorly
between the two lobes of the rotary
organ. The latter not double, as de-
scribed by Ehrenberg, but with an an-
terior and posterior depression, from the
latter of which extends a single rounded
process. Cilia in two rows, prolonged
to the oesophageal bidb. Stomach ciliated
internally, widely expanded posteriorly.
Short intestine also ciliated, and termi-
nating at the base of the foot. Two
pyriform glands in front of the stomach.
Two red specks opposite the margin of
the rotary organ ; theu' red pigment has
a sharp spherical figure ; according to
Leydig, an obvious refracting body pro-
jects from the anterior convex edge of
each. Two large longitiidinal muscles.
On each side of the stomach a water-
vascidar canal, but without either tags
or contractile sac. Ovary horseshoe-
shaped. Free extremity of the foot with
a bundle of setae.

This animal was noticed by Perty to
have the peculiarity of assiuning an ap-
parently lifeless state for half an horn* or

an hour at a time, lying in one spot,
often on the sm-face of the water, with
no other sign of life than that afforded by
movements of the oesophageal cilia, and
occasionally of the jaws.

This species is veiy delicate and tran-
sparent. XXXV. 502 represents a side
view, and 503, 504 under views, — ^the
latter having the wheels extended, the
fonner having them withdrawn, and the
anterior margin bent in, so that the eyes
appear near the middle of the lonca.
The internal organization is further
shown in xxxvm. 29. Found in sum-
mer among Lemnee and Ceratophylla.
Length about 1-120",

P. elliptica. — Lorica membranous, el-
liptical, with a narrow, smooth margin,
fi'ont entire (not excised). The two
wheels imited by a brow furnished with
setse. Eyes distant.' Amongst Con-
fei-vffi. 1-120" to 1-108".

P. clypeata {Bracliionus clypeatm, M.).
— Lorica membranous, oblong, narrow,
smooth at the mai'gin ; there is a frontal
portion, or brow, connecting the two
wheels, but no sette. The eyes approxi-
mate, (xxxv. 505 a dorsal view, with
the wheels extended.) In sea-water.
Length 1-120" j the sheH 1-144".

The next genus, Pompholyx, instituted by Mr. Gosse, is considered by him
to be a member of this family.

Genus POMPHOLYX (Gosse, A. N. H. 1851, vol. viii.). — Two frontal
eyes ; foot wanting ; rotary organ double in the rear, entire in front ; eggs
attached behind after deposition. The name alludes to the resemblance of
the lorica to a round flat smelling-bottle.

to a central blunt point; mental ridge
with two rounded lobes, divided by a
centi'al notch. Lorica 1-300".

Pompholyx complanata. — Lorica
much depressed, nearly circular, with
the lateral edges rounded ; anteriorly
truncate ; occipital edge gi'aduaUy rising

Of the ensuing genera, established by Ehrenberg, we have only met with
the description of species ; of one, indeed, with only a sketch of its relations.

Genus LARELLA (Elir.).— The foUo-ning species of this new genus, the
characters of which we have not met with, is named by Ehrenberg.

Lahella KscM. — Body with equal eyes. Length 1-190" to 1-280". Berlin,
setre, and three long fine hairs placed on Wcrneck has also seen this species,
each side the mouth, with two frontal

OF THE TAHBIGEADA.

713

Genus TETRASIPHON (Ehf.).— We have not met with the detail of the
generic characters, but they may be gathered from the description of the
follomng species : —

Tethasiphon Hijdrocora. — Very dentate, with the oblique rotary organ

large, hyaline, with two prominent tu- of Fleurotrocha. Foot with slender, long

bular occipital organs, and other two and acute toes; eye occipital. Length

neai- the termination of the back; pan- 1-36" and upwai'ds. Berlin,
creatic glands fom*, globose; jaws bi-

Genus DIPODINA. — Characters uriknown.

DiPonrNA Artiscon (Ehr.) (Mentioned
in Reports of Zoology, Ray Society). —
Approaches Notommata, but differs by a

particular constriction of its tarsal nip-
pers (toes). Found by Ehrenberg at
vVismar, on the Baltic.

The genus Poltchjetus (XXXYIII. 31, 32) of Perty is supposed by Leydig
to be a Crustacean. Cyphonatttes is also regarded by the same observer as
dubious ; whilst, as we have already observed, he regards Ptygura and Oleno-
phora as undeveloped forms of other species.

OF THE GROUP TARDIGRADA.

The creatures thus named are introduced here as a group, inasmuch as they
cannot be included amongst the Rotatoria. Some remarks on theii- organiza-
tion wUl be found in Part I. (p. 482) of this work ; and here I shall introduce
farther particulars, chiefly derived from the first edition of this work (1834),
p. 182, and from Dujardin's Hist, des Infusoires, p. 661. They have oblong
bodies, contracted into a ball; furnished with four pairs of short feet or
mammilliform processes, each terminated by simple or double hooked claws •
mouth very narrow, siphon-shaped ; with an internal maxillary apparatus
composed of two lateral moveable pieces, and of a strong musciilar oesophageal
bulb, furnished with hom-Hke dental articulated processes.

The Tardigrada stand on the one side between the Rotatoria (Systolides
Ihtj.) and the Helminthidse, and on the other between the Annelida and
Arachnida.

These creatures are usually found attached to aquatic plants which float
upon still water. I first obtained them from ponds in the Regent's Pai-k
By placing some water with the plants in a common white hand-basin and
shaking the vegetation, they are detached and ftdl to the bottom of the basin
from whence they are readily taken. They are generally met with, in com-
pany with the larger Itinds of Rotatoria, in moss. They are vciy sluggish in
their movements, and arc commonly known under the name of " little water-
bears." Under the polarizing microscope the manducatory apparatus exhibits
the same appearance as horn. They are capable of resuscitation after bein^
dried. They vary in length from 1-20" to 1-50". ^

M. Doyke, in an elaborate Memoir in the ' Annales des Sciences ' has
divided the Tardigrada into four genera : — '

Genus EMYDIUM.— Body oval, anterior part narrow, and terminating in
a pointed mouth, near to wliich, on each side, are flesh-like papilla. Feet

714 SYSTEMATIC niSTOBY OF THE INFUSOmA.

armed with four distinct claws ; colom* reddish. Found among moss (Bryum)
(Kgs. 1, 2.)

Genus MACROBIOTTJS. — Body more cylindrical ; obtuse anteriorly ; no
setoe ; each foot furnished with two claws, round with the preceding ; also
in rivulets. (See fig. 6.)

Genus TARDIGRADA. — Body stout, oblong ; mouth not so sharply pointed,
Pound in stagnant water, on aquatic plants, and on the Hyimum Jluitans.
(See figs. 3, 4, 6.)

Genus MIL!N1SSIUM. — Characters unknown.

For further particulars consult the General History, at p. 482 of this work.

TAEDIGEADA, OE XITTLE WATEE-BEAES.

Fig. 1. Emydium, magnified 130 diameters. Fig. 2. Head of the same, magnified 300
times. Figs. 3, 4. Tardigrada, mngm&&di\Q>0 times. Fig. .'5. Head of same, magnified
300 times. Fig. 6. Mouth apparatus of Macrobiotus, gi-eatly magnified.

OP XHB DESMIDIEJE.

715

OF THE GEOUP BACILLARIA.

Sub-group DESMIDIE^ ok DESMIDIACE^.

(Page 1, Plates I., II., III., XVI.)

[Class Alg^, Order Chlorospermece, Family Desmidiacece of Botanists.]

Cells of two symmetrical valves, devoid of silex, mostly figured, their junc-
tion marked by a pale interruption of the endochrome, frequently also by a
constriction ; increasing by the formation of two new half-cells, which become
interposed between the older, so that the two newly-produced cells consist
each of a new and an old half-cell ; the transverse division complete or incom-
plete, the cells thus either free or forming a filament ; endochi'ome green,
occasionally converted into ciliated zoospores (in the single known instance,
escaping by an aperture at the apex of one or more specially formed lateral
tubes) ; reproduction by conjugation of the contents of two distinct cells, and
the formation of sporangia, the contents of which, in after-development, be-
come segmented into a definite number of individualized portions, the last
generation of which are set free by the bursting or solution of the containing
membrane, and become the first fronds of a new vegetative cycle.

"We believe the foregoing diagnosis will apply to and include aU the species
which we look upon as imdoubtedly belonging to this family, and which are
introduced into this work. The claims of the genera Cylindrocystis and
Mesotaenium, as true members of the Desmidiaceae, not appeai-ing, so far as
we can judge, to be satisfactorily established, they are omitted.

The wonderful variety of form and beautiful symmetrical diversity of out-
line of the members of this family have been dilated on at length in the
General Histoiy. It seems to us, with regard to the mode of cell-division
in the true species of this family, that, normally, the preliminary step in the
process is the separation of the ceU-contents and the formation of a septum
at the central suture, the two halves of the contents becoming thus indi-
vidualized, whereupon ensues the growth and extension of the primordial
utricle and contents, concurrently with the production of the intermediate
cell- wall ultimately to form the two new segments, and either complete sepa-
ration taking place, or the cells remaining united in more or less brittle
filaments.

Many of the species, probably aU, seem to be liable to an abnormal mode
of growth, resulting from the incomplete carrying out of this process, when
the new growth foi-ms an intermediate, frequently misshapen structure, pro-
ducing with the original segments but one uniutcii-uptcd cavity, — tliis ii-regu-
larity seeming to be primarily due to the omission of the formation of the
septimi on the recommencement of the vegetative growth (III, 61, G2) : vide
Mrs. H. Thomas, J. M. Sci. vol. iii. pi. 6. figs. 17 & 18 ; also M. do Brebisson,
Liste, ifec. pi. 1, fig. 15 ; and Mr. W. Archer, Proc. Nat. Hist. Soc. Dub. 1859*
vol. ii, pi. 1. figs. 9-15.) An inspection of several of the latter figures will'
however, show that the intervening stnicture, in the first iustance (from the
foregoing cause, as wo imagine) rendered abnormal, is not always absolutelj^
shapeless or irregular in its form, but sometimes, its axis of growth striking
off at right angles to that of tlic older segments, assumes the form and often
the size of an entire frond. Sometimes, indeed, not only is the axis of growth

716

8TSTEMATIC HISTOEY OF THE INFU80BIA.

at right angles to that of the original segments, but its plane of expaasion is
at right angles to their plane. In each of these latter cases the entire ab-
normal specimen, therefore, forms a cross, — the interior here, of course, as
well as in those cases where the intervening growth does not assume any
definite outline, making but one uninterrupted cavity (III. 61), The omission
of the formation of a septum, however, can only be looked on as the primaiy
cause of the aberration, the curious change in the direction of the new growth
not necessarily following, as the figures, pi. 1. f. 9-11 (loc. cit.) seem to
prove (III. 62).

The assertion that zoospores occur in this family is based upon the observa-
tions made by Mr. W. Archer on Dociclium Ehrenbergii (Ralfs), and recorded
and figured in Proceedings Nat. Hist. Soc. Dublin, February 1860 ; also Nat.
Hist. Review, July 1860. These observations, though unfortunately and
unavoidably not so fuU in their details as the interest of the case would lead
us to wish for, seem to warrant the assumption that the species of this family
may be occasionally propagated by zoospores, predicating of the family that
which seems to hold m the species in question {Dociclium Elirenbergii). Pedi-
astreae are of course not taken into accoimt. Briefly, the phenomenon alluded
to is as follows (III. 46, 47) : — From beneath the base of one of the segments,
either one, two, or three (the latter rarely) lateral tubercle -hke projections
are formed, originating not from any portion of the segment itself, but from
an extension thereto produced between the inflated base and the sutural line.
When more than one is formed, they are usually opposite, but sometimes side by
side. A gradual elongation of the projection (or projections) then takes i)lace,
the endochrome in the immediate neighbourhood becoming finely granulai-,
and filling what has now become an elongate lateral tube (or tubes) like the
finger to a glove, the remainder of the endochrome being as yet not much
altered, and the terminal clear space with the active granules being still in situ.
The endochrome within the lateral tube and in its immediate neighbourhood
now becomes segmented into a number of definitely bounded individualized
portions, which presently one by one emerge through the opened apex of the
lateral tube, and become associated together in an external cluster. The
remaining endochrome now becomes di-awn into bands, turns brown, and
speedily dies. The cluster of gonidia at the apex of the lateral tube now
appear to have become encysted each within its own special coat ; and the
green contents can be seen twisting backwards and forwards within the eon-
fining membrane. After a time the contents emerge each from its cyst, by
rupturing it, and slowly swim away as pyriform or ovate ciliated bodies, —
as we apprehend, veritable zoospores. The author was entirely unacquainted
with their after-history ; but they resemble so much, in their appearance,
growth, and mode of escape from the parent-cell, the similar bodies in Cla-
dophora, &c., which are indubitable zoospores, that we imagine there can be
little question as to the nature and function of the bodies occurring in Doci-
dium. It will be noticed that this phenomenon is altogether distinct from,
and we believe in no way to be confounded with, that of the active molecular
movement of the ultimate granular particles of the endochrome alluded to at
pages 10 and 19 of the General History, — a circumstance which, indeed, some-
times accompanied the special one here described, in Mr. Archer's specimens,
but sometimes did not, and which is one of verj^ general occurrence imder
other circimistances and in other cases, and has probably given rise to the
assumption, often made in our English books, that zoospores occur
Desmidiacea3. Nor is the production of zoospores here briefly descnbcd to
be in any way confounded with the development of the parasitic plant Pi/thiMi
entophytum (Pringshcim), nor of any species of Chytridium (Braun). The

OF THE DESMIDIEiE.

717

former, indeed, is sometimes met with in various Desmidians, such as CIos-
tmnum Lunula, &c., as well as other Algae. For a figure of this curious
parasitic growth attacking E'mnosp/icera viridis (de ^Bxy) {^ChlorosphcBra
Oliveri, Henfi-ey, the former name having, we are inclined to think, the
priority), vide ' Micrographic Dictionary,' 2nd ed. pi. xlv. fig. 8. There can
be httle or no doubt that some such parasite as that alluded to attacking
a species of Closterium has given rise to Ehi-enberg's genus Polysolenia,
admitted indeed into the Desmidiacese by Kiitzing, but which we here cannot
but exclude.

The act of conjugation and formation of sporangia is not uncommonly to
be met with in several species. The after-development of the sporangium
seems to have been but very rarely witnessed; and the statement made ia the
diagnosis is founded on the account given by M. Hofmeister (Z. c), an extract
from which is given at page 17 ; also on the very similar- account given by
M. de Bary, ' Untersuchungen iiber die Familie der Conjugaten : ' vide pi. 6,
showing the development of the sporangium of Cosmarium Botrytis (III. 48-
54), and of C. Meneghimi (III. 55-60), the number of sister-cells formed
within the sporangium being fewer than in the instances cited by M. Hof-
meister. But although, in the cases cited by M. de Bary, the ceUs resulting
from the segmentation and individualization of the contents of the sporangium
are eventually of a Cosmariiun-shape, it is, however, not until the young
fronds commence self- division in the ordinaiy way, that the first-formed
young segments whoUy assume the special characteristics of the species (III.
52, 53, 54 & 58, 59, 60).

The nearest affinities of this family seem undoubtedly to be, on the one
hand with the Diatomaeeae (with which fanuly, indeed, they were long
associated), and on the other with the Zygnemacese (Conjugatse) ; while to
the PalmeUaceae they also approach through the genus Penium, connected
with CyUndrocystis and Mesotaenium = Palmogloea (Kg.).

It will be at once seen that the following arrangement of the species is for
the most part based on that laid down in Ealfs's ' British Desmidieae,' 1848,
in addition to which the following works have been consulted :— Kiitzing's
' Species Algarum,' 1849 ; Nageli's ' EinzeUiger Algen,' 1849 ; Bailey's
(Smithsonian Contributions to Knowledge) ' Microscopical Observations made
in South Carohna, &c.', 1850 ; Brebisson's ' Liste des Desmidie'es observees
en Basse Normandic,' 1856 ; de Bary (op. cit.), 1858 ; Papers in ' Nat. Hist.
Eeview,' by Rev. R. V. Dixon and by Mr. Archer, 1858-60. The first and
second of a series of papers by Dr. G. C. Wallich, F.L.S., descriptive of some
beautiful and interesting species of Desmidiaceae collected by him in Bengal,
had just made their appearance (' Annals Nat. Hist.' March and Api-U, I860)
when we were obliged to go to press. It has seemed to us more advisable to
OTTiit any description of those species than to introduce a few only without
having it in our power to do so with the whole. In indicating the soiu-ces
whence we have been able to derive information as to foreign species, it is
our pleasing duty to acknowledge the generous and courteous assistance of
M. de Brebisson in aff"ording by letter the requisite information which that
distinguished and experienced observer has so largely at his disposal, and
without which our own acquaintance with the Continental forms not kno-\vn
in this country would have been far more circumscribed.

The following genera included in this family by Kiitzing in ' Species
Algarum ' are here excluded, as we conceive either that they are not truly
Desmidian, or the unnecessaiy splitting up of older genera : —

Trochiscia, excluded ; Tetraedi-on, excluded ; Pithiscus = Cosmarium pyra-
midatum (Breb.); Stauroceras = Closterium, in part; Polysolenia {E.j = a.

718

SYSTEMATIC mSTOEY OP THE INFUSOMA.

Closteritim attacked by a parasitic growth (?) ; Microthcca, excluded ; Poly-
edi-ium, excluded ; Zygoxanthium = Xanthidium, in part; Phycasti-um, Aste-
roxanthium, Stephanoxanthiumj=Staurastruni ; Grammatonema, a diatom'
Bambusina = Didymoprium Borreri ; Isthmosira = Sphajrozosma ; Eucampia',
a diatom; GemineUa, excluded; Eaphidium = Ankistrodesmus ; Oocardium^
excluded. '

The other genera included by Kiitzing are placed here as a distinct group,
Pediastreae. '

Didymocladon (JRalfs) seems not distinguished from certain Staurastra by
characteristics sufficient to separate it from them ; we have therefore united
them, in which we follow Brebisson.

As to the new or altered genera proposed by Nageli and de Baiy, founded
rather on the mode of disposition of the endochrome than on the external form,
although we do not venture to deny its probably great importance, yet it
seems to us that the characters relied on are in many instances not sufficiently
constant for the purpose, as well as that several of the known Desmidian
species could not be satisfactorily or indubitably referred to the particular
genus to which, judging from analogy, they ought to belong ; neither, indeed,
does it seem, so far as we can judge, that those writers are themselves satisfied
as to the proper place of certain species, nor does the system, as yet, appear
quite without the disadvantage of disassociating kindred forms. We believe
we are fortified in the opinion we here endeavour to express by that of M. de
Brebisson. The genera Cylindrocystis and Mesotsenium are here omitted from
this family, as theu- claims to admission scarcely seem as yet indubitable ;
moreover, there seems to us little certainty as to the limitation of the species
hitherto described by Kiitzing and others.

If we have omitted some of the species described by the various authore
before cited, it is fi-om a conviction that, when either not satisfied as to their
absolute distinctness, or unfui-nished with what we could look upon as suffi-
ciently exact details, it was the safest course we could pursue, — as it seemed
to us better to leave out a few species, than to insert them with a description
which, owing most likely to our own want of perception, might prove insuf-
ficient or inaccurate. On the other hand, some may think we have admitted
too many species, and that certain of the forms hereafter described may be
but " varieties " of whichever may be assumed as the typical specific form ;
but in this conclusion we cannot coincide, as we are disposed to believe that
the species hereafter described (with possibly, indeed, a few rare exceptions)
are quite distinct, and, at least so far as British or Irish species are concerned,
are always perfectly distinguishable.

An ingenious method of succinctly expressing by means of symbols the ex-
ternal characteristic forms of the genera Tetrachastrum, Micrasterias, and
Euastrum, was propounded in a paper by Rev. R. V. Dixon, read to Nat. Hist.
Soc. Dub., 3rd June, 1859. We append his own explanation, as the best that
could be given : —

" The typical mode of division [in the genera above named] (as exempUfied
m Emstinim pinnatum, E. oblongiim, &c.) appears to bo into three portions or
subdivisiom, — the first, next the line of separation of the segments, extend-
ing across the frond, and embracing the two basal lobes ; the second including
the median lobes ; and the third, the extreme or end lobe. Tliis last, or tliird
subdivision, is the most constant. The two former are frequently represented
by a mere sinuosity or shallow indentation where the tlurd is distinctly deve-
loped ; but we never find the first 8ubdi^dsion distinct, and the second and
third imperfectly separated. The whole three, indeed, may bo merely marked
by slight sinuosities, as in Emstnim cuneatum ; but if any one is separated, it

OP THE DESMIDIEiE.

719

is the thii'd. And this, I may observe, is the order of development of the sub-
divisions in the growing segment of the typical Micrasterias : the new seg-
ment is fii-st hemispherical; the third subdivision is then developed; and
afterwards the first and second are separated.

" For the purposes of description these three subdivisions might be denoted
by the letters a, h, c, and their partial or complete development marked as
foUows : — ^When the subdivisions are distinctly separated, their symbols might
be separated by commas, thus, a, 6, c ; when any two or more are merely
marked by a sinuosity, they may be represented thus, a'^b ; and if there is
no trace of sepai-ation, thus, ah ; and if, at the same time, the direction of the
lines separating the subdivisions wei'e noted, the full description as regards
the divisions of the segments would be given. Thus — [See page 721.]

CONSPECTUS OF THE GENEEA.

P o

.2 .2

S °

s
%

/Joints manv times /t-,., , , .
' longer than '
broad ; neither
constricted nor ■
with lateral teeth
or projections.

tached

Filament attached.,

/Filament cylindri-
cal or subcylin-
drical

Jointa mostly
broader than
long, seldom
slightly longer
than broad; more
or less con-
stricted, or with
lateral teeth or
angles, or other-
wise figured.... i.

^Joints not con-
stricted . . .

Joints more or
loss deeply
constricted .

^Endochrome arranged

in spiral bands

Endochrome a simple
central longitudinal
contracted band , . .
r Endochrome a single
•j longitudinal flatten-

[ ed band

''Joints constricted or
with a projecting an-
nular rim at one or

■\ both ends

Joints with a bidentate
process or angle at

opposite sides

Filament 3-4-angu-
lar ; joints having
the external margin
plane or sHghtly cre-
nated, united to each
other by projections
springing from the
outer portion of each
extremity, thus pro-
ducing intervening
I central foramina . . .
( Filament 3-4-angu-
lar or compressed ;
joints either closely
united by a thick-
ened border for their
entire end-margin,
or by projections
producing interven-
ing central foramina,

as in last

Filament compressed ;
joints unitecl to each
other by minute tu-
bercles or gland-
like processes

Filament compressed
or 3-angular ; joints
without intermedi-
ate tubercles or pro-
oesses

Genicularia.
gonatoztgon.
Leptocystinema.

Hyalotheca.

DiDYMOPRIUM.

Aptoqonum.

Desmidium.

Sph.erozosma.

Spondylosium.

720

SYSTEMATIC HISTOBY OF THE IWFUaOHIA.

'' Fronds deeply con-
stricted ; seg-
ments more or
less deeply lobed,
or if merely im-
dulate or taper-
ing, the ends
acutely notched..

Frond often as
broad as long,
rarely, if ever, as
much as three
times longer than
broad. Sporan-
gia mostly orbi-
cular and spi-
nous, rarely orbi-
cular or quadrate
and naked

Fronds distinctly,
mostly deeply,
constricted ; seg-
ments mostly en-
tire, or if some-
what undulate,
the ends not
notched

Segments 3-lobed, lateral
lobes attenuated, their
apices entire or bifid. . . TETnACHASTHCM.

Segments 3-5-lobed, la-
teral lobes expanded,
incised, their external
margins dentate or
rarely sinuate Micrastrrias.

Segments 3-5-lobed, or
sometimes only late-
rally emarginat« or si-
nuate, undulate or
tapering ; lateral lobes
rounded, entire, or si-
nuately emarginate ;
end-lobe mostly cen-
trally emarginate or
concave, the segments
with variously disposed
inflated circular promi-
nences (the two latter
characters never simul-
taneously absent*) . . . Euastrum.

Segments not lobed, en-
tire, mostly rounded,
rarely undulate at the
margin, ends never
emarginate, sometimes
with ar solitary central
inflated prominence on
each front surface ;
without spines or pro-
cesses

Segments compressed,
entire, spinous, with a
central circular, cylin-
drical, or conical pro-
jection on both iront
surfaces

Segments compressed, en-
tire, either with two or
with four acute teeth
or simple or geminate
subulate spines placed
on the external angles
or prominences, with-
out a central projec-
tion Arthrodesmus.

Segments in e. v. angular
or radiate Staurastrum.

COSMARIUM.

Xanthidium.

Frond mostly many
times, rarely less
than three times,
longer than
broad. Sporangia
smooth {Penium,
annulahtm and
Spirotania mm-
cicola are some-
times not more
than twice as
long as broad) ... \

f Frond dis-
tinctly con- _
stricted at
the middle.

Segments in- f Ends trilobed.
flatcd at the ]

base y Ends truncate.

Segments not
inflated at

the base . . . Ends notched.
^ Frond cun-ed or arcuate,

not constricted

Frond straight, ends
truncate or rounded,
scarcely or not at all

constricted

Frond straight or nearly
so, endochrome spi-
rally twisted

« Euaatnm creuatinn (Kg.) is perhaps an exception.

Frond either not at
all constricted, or
with a slight and _
gradual attenua- '
tion towards the
middle

Triplockras.
docidicm.

Tktmkmorcs.

CliOSTERIVM.

Pknium.
Spirot.knia.

OF THE DESMIDIE^.

72i

[Prouisionally included.^
Cells elongate, attenuated, entii-e, aggregated into faggot-like bundles... Ankistrouksjius.
Cells rounded, compressed, deeply constricted, stipitate Cosmooladium.

" Euastrum cuneatum would be represented by a'^b^c.
Euastrum pinnatum, „ „ ct, b, c, parallel.

Euastrum oUongum, „ „ a, b, c, siibradial.

Micrasterias denticulata, „ „ a, b, c, radial.

EuaMmm pectinatum, „ a'^b, c, parallel.

Tetracbastrum „ „ ab, c, parallel."

Tbe foUowing contractions are employed, whicb may require explanation : —
f. v., front view ; s. v., side view ; e. v., end view ; tr. v., transverse view ;
e. f., empty frond; L., length, B., breadth, of fr'ond. The measurements are
expressed in so many fractions of inch by the use of two acute marks, thus,
L. 1-598"= length of frond 5-^th of an inch. In most of the foreign species
we are without the data to give measurements. G.B., Great Britain ; I., Ire-
land ; r., France ; G., Germany ; U.S.A., United States of America, refer-
ring to the record of the occiirrence of the species in those countries. It is
beheved that even this rough attempt at an indication of the distribution of
these organisms may not be altogether without its use. Doubtless many occur,
and perhaps different forms, in other countries of Europe ; and information
is much wanted in this respect as to other parts of the world.

Where a species occurs under another name in the works above cited, we
have, as far as possible, given the synonym, but should it occui' there under
the same name, it is not repeated.

The characters piinted in italics are such as immediately distinguish each
species from its nearest allies, and, the genus being known, are probably
those which should be first consulted ; but it is always requisite to perase the
whole of the characters applicable to each species and genus, with a view to
render the identification accurate.

A. Plant an elongated jointed filament. Sporangia orbicular, smooth.
1. Joints many times longer than broad.

Genus GENICULARIA (De Bary).— Filament cylindrical • joiats elongate,
cylindrical, without a constriction or inflation, ends tnmcate ; endochrome
arranged in two or three spiral bands upon the ceU-waU, sometimes irregular.
Joints previous to conjugation disunited, and bent during the process ; spo-
rangium placed between the empty conjugated joints.

Genictjlaria spirotcenia (De Bary). rangium orbicular, smooth, placed be-

- Joints ten or twenty times as long tween the conjugating joints, whicli are

I as broad, very slightly enlarged towards bent into a knee-shape, with which it

their ends, on the outer surface rough remains for some time in connexion,

with minute scattered gi-amdes. Spo- " B. 1-1.S0"'-1-100.""' (in. 3.) G.

Genus GONATOZYGON (De Bary).— FUament cylindrical ; joints elon-
gate, slender, cylindrical or narrow-frisiform, without a constriction or in-
flation, ends ti-uncate ; endochrome a single, central, longitudinal, undidatory,
contracted band. Joints previous to conjugation disunited, and during the
I process bent into a knee shape ; sporangium as last.

GoNATozvooN Ralfsii (De Bnry). — what dilated, ten to twenty times aa
'Jomts cylindrical wiiii the ends some- long as broad, rough on the surface with

3 a

722

SYSTEMATIC HISTOKY OP THE DTFUSOHIA.

minierous minute scattered graniiles;
endochrome sometimes bifid at the ex-
tremities, usually with a pale space at
the centre, and with a longitudinal me-
dian series of lighter-coloui'ed dense cor-
puscles. Sporangixim same as preceding
species, (in. 1,2.) L. 1-100" ; B. 1-2.350".
Docidium aspenim (Ralfs) ; Leptocysti-
nema aqyerum (Archer). G.B., I., F., G.
G. Brebissonii (De B.). — Joints nar-

row-fusiform, suhcapitate at ends, loosely
united, often single, rough on the surface
Avith minute scattered granules; endo-
chrome usually with a pale space at the
centi-e, and a median series of coi-puscles.
Sporangium as preceding. JDocidhim
asperu7n (Br6b.) ; Lop. Portti (Archer).
L. 1-200" to 1-105"; B. 1-3500". I.,
F., G. /3 much smaller, and joints
varying in length.

Genus LEPTOCYSTINEMA (Archer).— Filament attached, cylindrical;
joints elongate, cylindrical, slender, linear, without a constriction or inflation,
ends truncate ; endochrome a longitudinal flattened hand. (No e\T.dent gela-
tinous sheath.)

A genus under the above name was founded by Mr. W. Ai'cher (Nat. Hist.
Eev. vol. V. p. 250) for tbe reception of the single species now here included,
as well as tbe two species of Gonatozygon (De B.), not being, however, then
aware that De Bary bad previously established the latter genus in ' Hedwigia.'
However, as the reproductive condition of Lcp. Kinaliani (Ai-cher) is yet
unknown, we deem it more advisable to allow that species to remain under
its original name, and, for tbe present at least, to retain tbe genus, distin-
guishing it here from Gonatozygon by tbe filaments being attached (a singular
circumstance in Desmidiacese), and tbe endochrome a flattened band. The
species is very distinct indeed from tbe two preceding.

Leptocystinema Kinahani (Archer).
— Filament 2 to 3 inches long, often
brealdng up into separate joints; joints
20 to 40 times as long as broad, linear,
smooth ; endochrome in its broader dia-
meter filling the entire width of the
joint — in the narrower, not more than
one-thu'd, occupying the centre of the
joint, and at the centi'al pale space

cm-ved towards the cell-wall, and hav-
ing imbedded within it a longitudinal
median series of globular, light-coloured,
dense coi-puscles (one occupying the
centre of the pale space), retracted at
each end of the joint, leaving a clear
space in which are active gramdes.
Sporangiiun unknown. L. 1-200" to
1-50"; B. 1-1900". (m. 4.) I.

2. Joints mostly broader than long, very seldom slightly longer than broad.

Genus HYALOTHECA (Ehr.).— Filament cylindrical, very gelatinous;
joints having either a slight constriction, which produces a crenate appearance,
or a grooved rim at one or both ends, which forms a bifid projection at each
side ; end view circular ; endochrome radiate.

H. mucosa (Ekr.). — Filament scarcely
fragile, mucous sheath very broad ; joints
about as broad as long, not constricted,
but having at one of the ends a minuU
bidentate projection "on each margin, the

Hyatotheca dtssiliens (Br6b.). — Fila-
ment fragile, crenate ; joints usually
broader than long, tvith a shaUoto groove
round each, dividing the endochrome
into two portions. Sporangium globidar,
smooth, placed within the persistent
connecting tube fonned by the mutual
fusion of a fresh extension ft'om, and
produced between, the sides opposed to
eacli other of the conjugating pairs of
joints, the filament hai^mg previously
oroken up into single joints, (n. 32 & 35).
L. 1-2105" to 1-1351"; B. 1-1308" to
1-833". = Conferva dissih'ens (Smith),
Olo'opriutn dissih'ens (Berk., lla.ss.), Ili/a-
lothern mucosa (Kg.). G.B., I., F., G.,
U.S.A.

adjoining end of the next joint bemg
similar, these projections bein^ produced
bv an aimidai- grooved rim. L. 1-12.50"
to 1-G60"; B. 1-1250" to 1-1111"-
= Conferva 7H?fcosa(Mert.,Hook.,Han-.),
G/aoih ium 7nucosnin (Hass.), H. Jtaifsu
(Kg.). G.B., I., F.

H. P dubia (Kg.).— Filament without a
mucous sheath (?); joints rather broader
than long, vrith two puncta near each
margin. G.

OF THE DESMIDIEiE.

723

Genus DIDYMOPRIUM (Kg,).— Filament gelatinous, cylindrical, regu-
larly twisted ; joints with a bidentate process or angle at each side ; end view
circular, or broadly elliptic, with two opposite projections formed by the
angles; endochrome radiate.

DrDYMOPRiuMG'ret77Zw(K.g.). — Sheath
distinct; joints broader than long, tcith
a thickened border at their junction ; angles
bidentate; teeth angular ; transverse view
broadly elliptic. Sporangium orbicular,
formed within one of the two conju-
gating joints, the endochrome passmg
over from one by a narrow connecting
tube produced between the otherwise
but little altered broken-up single joints.
L. 1-464"; B. 1-4:7 0".=Desmidimn cij-
lindricuni (aiict.), Arthrodesmus ? cyl.
(Ehr.), Desmidium co^npressum (Corda),
D. Grevillii (De B.). G.B., I., F., G.,
Prussia, U.S.A.

Genus APTOGONUM (Ralfs). — Filament ^'k-angular ; joints not con-
stricted, plane or crenated at the lateral margins, united only at the outer
portions of each of their end margins by mutual projections, thus producing
intervening central oval foramina.

D. Botreri (Ealfs). — Joints inflated,
barrel-shaped, longer than broad, without
a thickened border at their junction ; angles
bicrenate, crenatures rounded; transverse
vieio circular. Sporangium elliptic, formed
within the (for some time) persistent
extensions from the conjugating joints,
which do not previously break up into
single joints, but couple, still imited in
the filament, in a confused or zigzag
manner, some of the joints remaining
unchanged, (ii. 38, 39.) L. 1-939" ;
B. 1-1030". = JSambusina Hrebissonii
(Kg., Breb.). G.B., I., F., G., U.S.A.

Aptogontjm Baileyi (Ealfs). — Joints
in f. V. quadrangular, about as broad as
long, their lateral margins plane; fora-

mina broadly oval ; in e. v. triangular,
angles somewhat rounded, (m. 5, e.v. 6.)
U.S.A.

Genus DESMIDIUM (Ag.). — Filament ^-A-angular or compressed, regu-
larly twisted ; joints bidentate or bicrenate at the angles or lateral margins,
and either closely united throughout the whole of their end margins by a
thickened border, or only at the outer portion of each by mutual projections,
and thus producing intervening central oval foramina.

G.B., I., F., G., Italy, Sweden, U.S.A.

D. quadrangidatum (Ralfs). — Filament
quadrangidar, varying in breadth fi-om
its twisting, having two longitudinal
waved lines ; joints in f. v. broader than
long, with ttvo someiohat roimded cre-
natures on each lateral margin, imited by
the whole of their end margins ; e. v.
quadrangidar ; endochrome foiu'-rayed.
(n. 37, 40.) L. 1-1244"; B. 1-603" to
1-455". = Z). quadrannulare (Kg.). G.B.,
F.,G., U.S.A. '

D. ttndtdatum (Corda). — Filament tri-
angular; joints in f. v. vfiih. a slight
central notch at each side, and/o«r broad
crenatures at each lateral margin, united
by the whole of their end niai'gius.

D. didymum (Corda). — Filament tri-
angidar ; joints in f. v. bidentate, broader
than long, united by the whole of their
end margins; e. v. triangular; angles
acutely bifid. = Desmidium bijithim
(Menegh,). G., Italy.

DESMinnisi aptogonum (Br6b.). —
Joints in f. v. qiiadi'angidar, broader
than long, with two rounded crenature.s
on each lateral mai'gin, imited at the
outer portion only of each end margin
by mutual projections, thus producing
intervening central oval foramina. G.B.,
F., G., U.S.A. a. Filament triangular,
regularly twisted, crenatures rounded.
L. 1-1490" ; B. 1-1000". (m. 7, e. v. 8.)
/3, filament compressed, crenatiues shal-
lower, andslightly angular. L. 1-1295"; B.
1-925". =Aptogonu7n Desmidium (Ralfs).

D. Swartzii (Ag.). — Filament trian-
gular, equal, with a single longitudinal
waved dark line formed by the third
angle ; joints in front view somewhat
quadrangular, broader than long, with
two slightly angular crenatures on each
lateral margin, united at the whole of
their end margins by a thickened border ;
end view triangular ; endochrome three-
rayed. L. 1-2000" to 1-1666" ; B. 1-633".

Genus SFHiEROZOSMA (Corda).— FUament compressed; joints deeply
divided on each side, thus forming two segments, and giving a pinnatifid

3 A 2

724

SYSTEMATIC niSTOIlT OF THE INFUSOKIA.

appearance to the filament, united to each other by minute tubercles or gland
lihe processes.

SpHiEiiozosMA vertehratiim (Ralfs)

Joints as long as broad, constriction deep,
acute ; segments reniform, gland-like
processes oblique, solitary at the centre of
each margin. A gelatinous sheath evi-
dent. Sporangium spherical, smooth,
placed between the empty segments, the
filament previously to conjugation break-
ing up into single joints. L. 1-1429";
B. 1-909" to 1-666". (i. 1^-17. ) = Sph.
elegans (Corda, Hass.), Odontella imi-
dentata (Ehr.), Isthmia vertebrata
(Menegh.), Isthmosira vert. (Kg.). G.B.,
L, F., G., Italy, U.S.A.

S. excavatum (Ealfs). — Joints longer
than broad, subquadi'ate, very minute;
constriction a deep roimded sinus on
both sides, and two sessile gland-like pro-
cesses on each margin at their junction;

Genus SPONDYLOSIUM (Breb.)-
joints deeply divided on each side, thus
pinnatifid appearance to the filament,
processes.

ST?om)Yr^osivusto7natomorj)hum (Br.).
— Joints about one-third broader than
long, constriction deep, segments reni-
form, ends broadly rounded; no sheath.
=Isthmia stomatomorpha (Menegh.). F.

S. ptdchrmn (Bail. sp.). — Joints twice
as broad as long, constriction not deep,
acute, segments elliptic ; junction margins
sti'aight, forming short connecting bands ;
gelatinous sheath wide. = Sphcerozosma
pulchrum (Bail.). U.S.A.

S. pulchellum (Archer). — Filament
minute, fragile ; joints about as broad as
long, sharply incised; segments laterally
inflated at the base, thus giving a pouting
appearance to the joint, narrotoing to
the ends, which are straight, with square
angles ; endochrome containing in each
segment a single, centi-al, lighter-
coloiu-ed, globular coi-puscle. No evi-
dent gelatinous sheath. L. 1-2330";

angles sometimes with three very minute
teeth ; no evident gelatinous sheath-
Sporangium elliptic, placed between the
empty joints, the filament previously
brealdng up. L. 1-2575"; B. 1-30.50".
= Isthmosira excavata (Kg.). G.B., I.,
F., U.S.A.

S.flliforme (Ehr.). — Joints about as
long as broad; constriction acute; seg-
ments elliptic, and imited by doubk
slender processes which include a quadrate
foramen between each pair. = Isthmosira
flUforjnis (Kg.). G.

S. lamelliferum (Corda). — Joints about
one-third broader than long, constriction
deep, slightly rounded within ; segments
incurved, reniform ; connecting processes
" flattened," coloiu-less ; a gelatinous
sheath. G.

-Filament compressed or ^-angular ;
forming two segments, and giving a
and luithout intermediate tubercles or

B. 1-2330". (m. 10.) I.

S. depressum (Breb.). — Joints some-
what broader than long, subquadrate,
constriction a rounded sinus, angles
roimded, ends sti-aight, fmiiished at end
margin on upper sm"face with three
immded protuberances; "no sheath."
(ra. 9.) F.

S. serratum (Bailey, sp.). — Joints
broader than long, constriction a tiian-
gular notch; segments forming lateral
tiiangular acute jirojections, thus giving
a serrated outline to the filament ; junc-
tion margins straight. = Sph<srozostm
se)')'atum (Bail.). U.S.A.

S. seccdens (De BaiT, sp.).— Filament
very fi-agile, joints as iong as broad, con-
striction a shallow rounded sinus ; seg-
ments subelliptic, ends concave : no gela-
tinous sheath. L. 1-287"'. = i^/i(Prozosma
secedens (De Bary). G.

B. Fronds simple, free, Giving to complete transverse division.
1. Fronds distinctly constricted at the middle, never as much as three times
longer than broad. Sporangia mostly spherical and spinous or tubercu-
lated, or veiy rarely spherical or quadrate and naked.

Genus TETRACHASTRUM (Dixon). — Frond compressed, deeply con-
stricted into two 3-lobed segments ; lateral lobes projecting honzontaUy, or
sometimes divergent, broadest at their base and simply attenuated outwards;
end lobe laterally expanded into a honzonfal attenuated projection on eaen
side, subtending the lateral lobes ; centi-al constriction a gradually widening
incision {ab, c, vide supn\).

OP THJE DESMIDIE^.

725

* Extremities of lobes entire, mucronate
or acute.

TETBACHASTnuM arcuatiim (Bailey,
sp.). — Fi'ond rather broader than long,

f)innatifid, quadrangular ; lateral lobes
ong, slender, arcuate, tapering, clivergeiit
from those of the opposite segment, their
extremities acute ; terminal lobe naiTow,
produced, its lateral projections abrupthj
transverse, slender, attenuated, acute ;
ends slightly concave at the centi-e.
= Micrastenas arcuata (Bail.). U.S.A.

T. expansum (Bailey, sp.). — Frond
about as broad as long, somewhat stel-
late ; lateral lobes long, slender, straight,
conical, divergent fi-om those of the op-
posite segment; their exti-emities acute ;
terminal lobe narrow, produced, its la-
teral proj ections someivliat diver-gent, short,
quickly tapering, acute; ends concave.
= Micr. expansa (Bail.'). U.S.A.

T. mum-onatum (Dixon). — Frond
longer than broad, subeUiptic; lateral
lobes very broad, sti-aight on the margin
fonning the baae of the segment, tm-gid
on the upper margin, then- extremities
rounded, fm-nished on the mai'gin with
one, tioo, or thr'ee minute mucro-like spines,
one always at the exti-emity or basal
angle of the segment, others, when pre-
sent, irregularly placed on the upper
margin ; tenninal lobe short, very broad,
its lateral projections short, stout,
quickly tapermg, somewhat inciu'ved at
extremities, which are mucronate ; ends
rounded, with a very shallow inconspi-
cuous centi'al concavity; tr. v. broadly
elliptic; e. f. pimctate. L. 1-167"; B.
1-235". I.

2 * Extremities of the lobes bidentate.

T. oscitans (Dixon). — Fi'ond about as
broad as long, pinnatifid; lateral lobes
separated from the tenninal by a roimded
sinus, hoyizontal, conical, their extremities
bidentate ; end lobe short, broad, its
lateral projections short, conical, usually
bidentate, narrower and shorter than the
lateral lobes ; ends convex at the centre ;
tr. V. fusiform, e. f. punctate. L. 1-250" ;
B. 1-211". (II. 28, 2Q).=:Euastrum
holoci/stis (Kg.) ; Holocystis oscitans
(Hass.) ; Micrastcrias oscitans (Ealfs).
G.B., i, F., U.S.A.

T. Atnericanum (nobis). — Frond
broader than long, suborbicular, pinna-
tifid; lateral lobes separated from tlie
terminal by a deep acute incision, ^P}"^'
zontal, conical, tapering, their extremities
bidentate ; end lobe short, its lateral pro-
j ections long, tapming, bidentate at their
extremities, as 6roa(Z and long as the lateral
lobes ; ends broadly rounded. = Micras-
tcrias incisa (Kiitz.), Bailey, in 'ISIicr.
Obs. in S. Carolina,' &c., but surely not
that species ; we ai-e therefore obliged to
place it here under another specific
name.

T. pinnatifidum (Dixon). — Frond ra-
ther broader than long, plane, pinnatifid ;
lateral lobes separated from the terminal
by an equal subacute incision, ti'iangular,
subconical, horizontal, their extremities
bidentate ; end lobe short, its lateral
projections ti'ansverse, sho7-t, bidentate
at the extremities, ends straight (colour
pale). L. 1-440"; B. l-m2". = Micras-
tcrias pinnatijida (Ralfs, Br^b.) ; Euas-
trum pinnatvfidum (Kg.). G.B., F., G.,

T. didymacanthum (Nag. sp.). — Frond
about as broad as long, pinnatifid ; late-
ral lobes separated from the tenninal by
a wide rounded sinus, theii' lower margin
convex, in apposition with those of the
opposite segment for a portion of their
length, then slightly divergent, their
upper margin nearly straight, horizontal,
their extremities bidentate ; end lobe
long, united to the basal portion by a
narrow neck, its lateral projections short,
their extremities bidentate, ends slightly
convex. L. 1-40'" ; B. 1-40"'. = Euas-
trum didymacanthum (Nag.). G.

T. quadratum (Bail. sp.). — Fi'ond
broader than long, pinnatifid, quadran-
gulai-; lateral lobes separated from the
tenninal by a wide rounded sinus, same-
what injlated at their base, elongate,
slightly divergent fi-om those of the
opposite segment, their produced extre-
mities slender, bidentate; end lobe nar-
row, produced, its lateral projections
transverse, elongate, slender, bidentate
at the extremities; ends with a slight
centi'al concavity. = Mic. quadrata (Bau. ).
U.S.A.

Genus MICRASTERIAS (Ag.). — Frond mostly lenticular, as long as or
slightly longer than broad, deeply constricted into two lobed segments ; seg-
ments usually somiorbiciilar, 5- or sometimes 3-lobed ; lobes incised or
divided, mostly radiant, narroiver at the base and widening xijinvards, their
ultimate subdivisions spreadinr/, dentate or minutely sinned, or rarely only
sinuate at the outer margin ; central coiistrictiou usually linear.

726

SYSTEMATIC HI8T0EY OF XITE INFUSOBIA.

* The subdivisions o f the lobes spreading/
in a plane at right atiffles to that of the
frond, (a, b, c.)

MiCHASTERiAS muricata (Ealfe). —
Fi'ond quadrangular; segments sub-5-
lobed, looes opposite ; basal lobes tripar-
tite, middle lobes bipartite ; end lobe
exserted and laterally divergent, its
lateral extensions bipartite ; all the sub-
divisions of all the lobes divergent and
disposed in a pilane at right angles to the
plane of the frond, their extremities ter-
minating in thi-ee or foui* projecting

Soints; the intervals between the lobes
eep rounded sinuations ; ends straight,
entiXQ. =Euastrum muricatum CBaLlev).
U.S.A. ^

2 * Ttie subdivisions of the lobes spreading
in the same plane as the frond.

t Frond subelliptic ; segments 3- or sub-
6-lobed, lobes spreading, the intervals
between the lobes being wide ; lateral
lobes bipartite, their subdivisions di-
vergent, end lobe exserted and laterally
divergent, (a^b, c.)

M. Baileyi (Ralfs). — Frond granulated
all over ; segments 3-lobed ; lateral lobes
deeply bipartite, subdivisions slender,
their extremities bidentate, the lower
subdivisions horizontal, approximate to
those of the opposite segment, the upper
divergent; end lobe narrow below, ex-
serted, transversely expanded, its lateral
extremities truncate; ends concave.
U.S.A.

M. ringens (Bailey). — Frond some-
what coarsely granidated at the margin ;
segments 3-lobed ; lateral lobes some-
what broadly bipartite, stout, divergent
from those of the opposite segment,
their subdivisions having the extremities
obscm'ely bidentate; end lobe naiTow
below, exserted, transversely expanded,
its lateral extremities obtuse ; ends con-
cave. U.S.A.

M. fiircata (Ag.). — Frond smooth ;
segments sub-5-lobed ; basal and middle
lobes bifid, then- subdivisions slender,
linear, divergent, and J'orked at the apex,
bifurcation usually incurved; end lobe
exserted, with a rounded sinus between
the considerably produced divergent ex-
tensions fi'om the angles, which are ulti-
mately forked, their bifm-cations in-
curved. L. 1-1.35"; B. 1-156". = M.
radiata (ITass.), M. 3Icliten3is ^ gracilis
(Kg.). G.B., U.S.A.

M. Crux-Mclitensis (Ralfs). — Frond
smooth; segments sub-5-lobed; bnsaJ

and middle lobes bifid, subdivisions
short, stout, and bidentate at the apex •
end lobe exserted, with a rounded sinus
between the produced divergent exten-
sions from the angles, which are ulti-
mately bidentate. L. 1-20G" ; B. 1-221".
(i. 22). = Euastrum Crux-Melitetms
(Ehr.) ; 31. Melitensis (Meneffh.). G B
F., G., Italy, U.S.A. ^ ^ •

2t Frond angular-eUiptic, subquadrate
or suborbicular ; segments 3-lobed;
lobes spreading, the intervals between
the lobes being usually wide ; lateral
lobes either bipai'tite and inciso-den-
tate or tiimcate on outer margin ;
end lobe mostly exserted, divergent.
(oT^b, e.)

M. Americana (Ralfe). — ^Frond angu-
lar elliptic, more or less punctate ; seg-
ments 3-lobed; lateral lobes broad,
cuneate, their margins concave, inciso-
serrate; end lobe broad, cuneate, and
exserted, bipartite at the angles, the
subdivisions naiTow, and minutely den-
tate at the extremities ; end concave.
L. 1-204"; B. 1-254". (u. 44, bad).=
Euastrum America}iu7n (Ehr.). G. B.,
I., F., U.S.A. /3, margins waved rather
than dentate.

M. foliacea (Bailey). — Frond sub-
quadrate, smooth ; segments 3-lobed j
lateral lobes deeply bipai-tite, inciso-
dentate, their mai'gins extending to an
equal distance from the middle line of
the fi'ond, with a short rounded tooth-
like projection next the end lobe ; end lobe
narrotc, somewhat dilated above, angles
emarginate ; ends concave. U.S.A.

M. incisa (Kg.). — Fi'ond about as
broad as long, suborbiculai* ; lateral lobes
horizontal, sides pai'allel, abruptly trun-
cate, with a tooth at each angle ; end lobe
short, veiy broadly cuneate, entire, ite
angles acute. = Euastrum Crux-Mclitensis
(Ehr.). G., F., U.S.A. ?

M. decemdeiitatum (Nag.Y — Frond
about as broad as long, suoorbicular ;
segments 3-lobed; lateral lobes hori-
zontal, side subpai'aUel, obscurely bipar-
tite, their subdivisions acutely bidentate;
end lobe broadly cimeate, entire, angles
acute; ends rounded. L. 1-55"'; B.
155"'. = 31. Ncodamensis (Braun) ; M.
Itzigsohnii (Brdb.). F., G.

3t Frond cu'cular; semuents 5-lobed;
lobes approximate, the inten als be-
tween the lobes being linear or very
deep and acute incisions : ba^al and
middle lobes dichotomously divided

OP THE LESMIDIEiE.

727

or deeply incised; end lobe naiTow,
seldom and but very slightly exserted.
(a, b, c.)

M. Torreyi (Bail.). — Frond smooth;
segments 5-lobed ; basal lobes bifid,
middle lobes trifid, the subdivisions
nearest the opposite segments and those
nearest the terminal lobe bidmtate at the
apex ; the intei-mediate three terminat-
ing in acute points ; all somewhat iiiflated
and tapering ; tenninal lobe narrow, not
exserted, spreading at the angles into
divergent tapering points j endS slightly
emarginate. U.S.A.

M. denticulata (Breb.). — Frond orbicu-
lai', smooth ; segments 5-lobed; basal and
middle lobes twice dichotomous; ulti-
mate subdivisions truncato- emarginate,
with rounded angles; end lobe simply
thrice emarginate. Sporangiimi orbicu-
lai", beset with scattered stout elongate
spines, at first simple and obtuse, after-
wards forked or trifid, their divisions
finally again branched and recui-ved. L.
1-113", B. 1-138". (n. 22, sporangium).
=EuastrumIlota (Ehi.^ m T^&ni,. G.B.,
I., F., G., Italy, U.S.A. /3, ends broader,
slightly hirsute at the terminal margin
(BaUey).

M. rotata (Ralfs). — Fi'ond orbicular,
smooth ; segments 5-lobed ; basal lobes
twice, middle lobes thrice dichotomous ;
ultimate subdivisions acutely bidentate;
end lobe very slightly exserted, its
angles very slightly produced, bidentate,
ends emarginate. In ti-ansverse view is
seen an inflated protuberance just over
the central isthmus, which may possibly
exist in other species of Micrasterias.
L. 1-91", B. 1-104". (I. 20.) = Eicastrum
Rota (Ehr.jNag.) in part ; Eutomia rotata
(Harvey). G.B., I., F., G., Italy, U.S.A.

M. Jimbriata (Ralfs). — Frond orbicu-
lar, smooth ; segments 5-lobed ; basal
lobes twice, middle lobes generally thrice
dichotomous ; ultimate subdivisions ob-
tusely emarginate, each furnished with
two curved acute spines ; end lobo some-
what exserted, the angles slightly pro-
duced and roimded, and each furnished
with two or three minute spines ; ends
concave. L. 1-108", B. 1-119". =^Mrts-
trum Rota (Ehx.) in part. G. B., U. S. A.

M. apiculata (Menegh.). — Frond orbi-
cular, hispid all over ivith scattered spines ;
segments 5-lobed ; basal and middle lobes
once or twice incised, their external mar-
gin tootlied, ultimate subdivisions fiu--
lushed with two acute spines ; end lobe
narrow, spinous on external mai;gin.=
Eimtrum aculcatum (Ehr,). G., F.

M. radiosa (Ag.). — Frond orbicular,
smooth ; segments 5-lobed ; basal lobes
twice, middle lobes generally thrice di-
chotomous, ultimate subdivisions htflaied,
attenuate towards the end, bidentate ; end-
lobe emarginate, its angles dentate, (i.
21.) L. 1-138"; B. '[-im".=Euastrum
Sol (Ehr.). G. B., I., F., U. S. A.

M.. papillifei-a (Breb.). — ^Frond orbicu-
lar, having the principal sinuses bordered
by a row of minute granules, otherwise
smooth ; segments 5-lobed ; basal and
middle lobes twice dichotomous, their
ultimate shallow subdivisions teiininated
by two, sotnetitnes three, gland-like teeth ;
end-lobe emarginate, its angles dentate.
Sporangium as in M. denticidata, but con-
siderably smaUer. L. l-221"-l-205" ;
B.l-238"-l-211". (i, 18, spor. 19). G.B.,
I., F., U.S.A.

4t Frond orbicular; segments 5-lobed;
lobes approximate, the intervals be-
tween the lobes shallow narrow inci-
sions ; the lateral lobes dentate, crenate,
or slightly sinuate; end lobe broad, not
exserted. (a'~^b, c.)

M. quadragies-cuspidata (Ralfs). —
Frond hispid all over with scattered minute
hair-like spines ; segments 5-lobed ; basal
and middle lobes slightly bipartite, their
subdivisions bidentate; end lobe very
broad, cuneate, trimcate, its angles biden-
tate. = Cosmarium quadragies-cuspidatum
(Corda). G.

M. truncata (Breb.). — Frond orbicular,
smooth; segments 5-lobed; basal and
middle lobes obscui-ely bipartite, extre-
mities bidentate ; end lobe very broadly
cuneate, bidentate at the angles, and with
a slight centi-al concavity. L. 1-240" ; B.
1-250". = Cosmarium tnmcatmn (Corda) ;
Euastrum Rota (Ehr.) in pai-t ; M. scmi-
radiata (KgJ; Euastrum semiradiatum
(Nag.). G.B., I., G., F., U.S.A.

M. crenata (Brt5b.).— Frond orbicidar,
smooth; segments 5-lobed; basal and
middle lobes usually crenate, or sinuate ;
end-lobe very broadly cimeate, rounded
at the ends, entire. L. 1-244" : B. 1-263"
G. B., I., U. S. A.

5t Fi'ond oblong, elliptic; segments 5-
lobed ; lobes approximate or spreading,
intervals between the lobes linear or
somewhat sinuous, all tlio lobes similar
at the exti'emitics, the end lobe tho
broadest, (a, b, c.)

M. Jenneri (Ralfs). — Frond oblong,
minutely granulated; segments 5-lobod;
basal, middle, and end lobes cuneate]

728

SYSTEMATIC HISTOBT OF THE INFUSOIITA.

obsciu'ely bipartite, and their subdivisions
emarf/inate, or with merely a slight central
concavity ; angles rounded ; end-lobe at
externalmargin considerably tbebroadest.
L. 1-147"; B. 1-209". G.B., 1. a(Ralf8),
grannies like mere jpuncta, lobes slightly
bipartite, subdivisions emai'ginate. ^

(■Ralfs), granules larger, giving a dentate
appearance to the margin, otherwise as a.
y (Archer), granules giving a rough ap-
pearance to the margin, lobes slightly
concave, margins rounded, not bipartite,
without emarginate subdivisions.

Genus EUASTRUM (Ehx.). — Frond longer than broad, compressed ; deeply
constricted into two lobed or sinuated segments ; segments usually pyramidal,
6- or 3-lobed or merely sinuous, possessing variously disposed circular inflated
protuberances (very rarely absent) ; lateral lobes opposite, very rarely radiant,
rounded or' sinuated at the extremities ; end lobes acutely incised or emarginate
at the centre, rarely only concave ; central constriction linear. (The inflated
protuberances and the emarginate ends rarely (if ever ?) simultaneously
absent.)

* Segments deeply lobed; separating si-
nuses directed inwards and doicnwards ;
the end lobe cuneate and partly included
within the notch formed by the projection
of the lateral hoes.

Etjasthxim verrucosum (Ehr.). — Frond
somewhat longer than broad, rough all
over with conic granules ; segments 3-
lobed, somewhat divergent, all the lobes
broad, cuneate, with a veiy broad shallow
external sinus {ab, c).
" Empty frond : f.v. segments with one
large cu'cular basal inflation on surface,
one smaller on each side, and two others
on the end lobe ; s. v. segments inflated at
the base, narrowed into a short neck, end
dilated vnth a central sinus ; e. v. oblong,
with three inflations at each side, one at
each end, end lobe having 4 divergent
lobelets. L. 1-267"; B. 1-270". Cos-
marium verrucosum (Menegh.), papu-
losum (Kg.). G.B., I., G., F., Italy,
U.S.A.

E. oblongum (Ralfs). — Fi-ond rather
more than twice as long as broad, smooth,
oblong ; segments b-lobed ; lobes nearly
equal, cimeate ; lateral lobes, or the basal
only, with a broad, shallow, marginal
concavity, all theu- angles rounded, ter-
minal notch linear (a, b, c).

Empty fi-ond : f. v. seg. pimctate, with
three large inflations on sui-face near the
base, two others above and two on ter-
minal lobe ; tr. v. three times as lon^ aa
broad, with three subdistant marginal
inflations at each side, and one at each
end, in /3 broader in proportion, more
elliptic, and inflations close ; e. v. end
lobe notched at opposite external mar-
gins. Sporanpum orbicidar, beset with
numerous conical tubercles. L. 1-156" ;
B. 1-282". {m.W.) = Echinella oblongn
(Grev.); EuastrumPectenCEhx.); Cosma-

rium sinuosum (Corda) ; Eutomia oblmga
(Hai-v.). G.B., I., F.,G., Italy, U.S.A. 0
smaller, naiTower, middle lobes rounded,
without any marginal concavity.

E. crassum (Kg.). — Frond about twice
as long as broad, SMftjwarfrj'/aiera/, smooth;
segments 3-lobed ; basal lobes very broad,
with a very broad, shallow marginal sinus,
in which there is sometimes a slight in-
termediate rounded projection; end lobe
cuneate, rounded, teimmal notch linear.
(ab, c.)

Empty frond : f. v. punctate, segments
with thi'ee inflations below and two
above ; tr. v. two or thi-ee times longer
than broad, with three lobes or inflations
at each side and one at each end ; e. v.
end lobe sinuate at opposite external
margins. L. 1-193"-1-132" ; B. 1-263".
=E. Pelta (Hass.). G. B., I., F., G.,
U. S. A. /3 smaller, margins of latei*al
lobes more concave, sinuations between
the lateral and end lobes more closed,
the latter more included.

E. cornutum (Kg.). — Fi'ond abouttwice
as lon^ as broad: segments 3-lobed, some-
what mflated at base, outer upper angles
of basal portion prolonged into a process-
like projection directed upwai'ds ; end
lobe iaciuded, its notch broad, concave.

Empty fi'ond punctate, {ab, c.) G.

2 * Segments sinuously lobed, or f^tpen'ug:
end lobe cxserted attd tinit^d to the basal
portion by a distinct neck.

t End lobe with a linear or acute notch.

Kpinnatum (Ralfs). — Frond oblong,
about twice as long as broad ; segments
6-lobed in a pinnatifid manner, basal
lobes slightly emarginate, middle snialler,
rounded, entire, end lobe e.\serted, di-

OF THE DESMIDIEJE.

729

lated, its notch linear ; the tippei' margin
of the lobes horizontal, (fl, b, c.)

Empty frond: f. v. segments piinc-
tate, usually with two large inflations
near the base, four smaller between,
three others above, and two on end lobe ;
s. V. central consti-iction deep, segments
inflated at the base, then contracted,
again inflated, and again contracted be-
neath the dilated terminal lobe ; tr. t.
with foiu- lobes or inflations on each side,
and one at each end ; e. v. end lobe with
a deep sinus at opposite external mar-
gins, concave at the sides, so as to produce
torn' divergent lobelets. L. 1-188" ; B.
1_4.54". G.B.

E. humerosum (Ralfs). — Frond about
twice as long as broad; segments sub-
5-lobed ; basal lobes slightly emarginate ;
middle lobes narrow, directed upioards,
resembling processes ; end lobe with a
short neck, partly included between the
middle lobes, dilated, its notch linear.
{a, b, c.)

Empty frond minutely pimctate ; f. v.
segments with three inflations at base,
two above and two on end lobe ; ti". v.
elliptic, with three inflations on each
side and one at each end. L. 1-225" ;
B. 1-382". G.B., I., F.

E. affine (Ealfs). — Frond about twice
as long as broad ; segments 3-lobed ; basal
lobes slightly emarginate, having inter-
mediate between them and the end lobe
on each side a tubercle representing mid-
dle lobes, the upper margin of which is
horizontal; end lobe exserted, dilated,
its notch linear, (ab, c.)

Empty frond : f. v. minutely punctate ;
the segments with foiu* tasal mflations,
two above and two on end lobe ; tr. v.
elliptic, with fom* inflations on each side
and one at each end ; e. v. end lobe emar-
ginate at opposite external margins, pro-
ducing four shallow lobelets. L. 1-230" ;
B. 1-458". G.B., I., F., U.S.A.

E. ampidlaceum (Ralfs). — Frond rather
more than one-half longer than broad ;
segments obscurely 3-lobed, shoit, with
broad in/lated base ; basal lobes not emar-
ginate, having on each upper side a small
intermediate tubercle between each and
the end lobe ; end-lobe exserted and di-
lated, its notch linear, (ab, c.) Empty
frond minutely punctate ; f. v. inflations
indistinct or confluent ; s. v. narrow el-
liptic, with several inflated protuber-
ances, ends scarcely dilated, rounded ;
tr. V. with four inflations at sides and
one at each end. L. 1-274" : B. 1-394".
0.n., I., F., U.S.A.

E. insignc (Hass.).— Frond rather more

than twice as long as broad ; segments
inflated at base, sides entire, without late-
ral tubercles, and tapm-ing into a lo7ig
slender neck ; end lobe dilated, its notch
linear, {ab, c.)

Empty fi'ond minutely punctate ; f. v.
segments with two inflations at the base ;
s. V. narrower, gi-adually tapering to the
end, which is considerably dilated ; pro-
jections roimded, with a sinus between;
tr. V. siibquadrate, slightly concave at
sides, with a rounded lobe at the centre
of each end ; e. v. end lobe with a siniis
at opposite external margins, angles thus
protruded into four divergent roimded
lobelets. L. 1-232" ; B. 1-416". (m. 12.)
G.B., L, U.S.A.

E. Didelta (Ralfs). — Frond rather more
than twice as long as broad ; segments
pyramidal, inflated at the base and again at
the middle, end scarcely dilated, rounded,
its notch linear. {oT^b, c.)

Empty fi'ond pimctate ; f. v. segments
with several inflations in lines and two
at the end ; tr. v. eZfo}j<»c with four infla-
tions at each side aiid 07ie at each end :
e. V. end lobe entire at margin. Sporan-
gium orbicular, with subulate spines.
(1. 23, 24, tr. V. 25.) L. 1-185"; B. 1-357".
= CosmanMwi-Dt(?eZte(Menegh.), E. binale
(Kg.). G.B., I., F., Italy, U.S.A.

E. ansatum (Ehr.). — Fi'ond about twice
as long as broad; segments inflated at
the base, tapering tipwards loithout sinua-
tions into a neck, end tiot dilated, roimded,
its notch linear, (ab, c.)

Empty frond punctate; f.v. segments
turgid on the siu-face, at the middle tvith-
out circular inflations ; tr. v. elliptic, tcith
a single large iiflation at each side ; e. v.
end lobe entire at the margin, its divisions
circular. L. 1-315"; 'B.1-QU".=E. binale
(Kg.), Cosmarium ansatum (Ke;.). G.B.,
I., P., G., Italy, U.S.A.

E. circulare (Hass.). — Fi'ond about
twice as long as broad, tapering ujnvards
into a necJc, end not dilated, its notch an
acute incision, (ab, c.)

Empty frond : segments with flve basal
inflations, four in a half circle round the
fifth, and two others "at the extremity.
= Cosmarium circular e(K.^XE. cirndare
var. Ilassallii (^v&h.). G.B., F., U.S.a!

E. sinuosum (Lcnonnand). — Frond
about twice as long as broad, segments
3-lobed, basal portion emarginate at the
sides ; end lobe somewhat' dUated, its
notch linear, (ab, c.)

Empty frond punctate ; segments with
flve basal inflations and two others at cr-
tremity ; tr. v. elliptic, with three infla-
tions at each side and one at each end.

730

SYSTEMATIC HI8T0EY OP THE INFtrSOKIA.

L. 1-825" ; B. 1-549". = E. circidare 0
(Rfs.), JS. circidare, var. Falasiensis
(Brdb.). G.B., F.

E. Jenneri (nobis). — Frond scarcely
twice as long as broad; segments 3-lobed,
basal portion subquadrate, emarginate at
the sides ; end lobe somewbat dilated, its
notcb linear, (ab, c.)

Empty frond pimctate, segments with
several small iiiflations arranged in alter-
nate lines. =E. circidare y (Ralfs), E. cir-
cidare, var. Ralfsii (Brt5b.). G.13., F.

]Mi'. Ralfs imites this and the two pre-
ceding as three varieties of E. cirmlare
(Ilass,). They seem, however, to be
quite as distinct as any other species de-
scribed, not only in external outline, but
also in the distiibution of the superficial
inflations.

2 1 End lobe straight or concave without
a central notch.

E. pectinatum (Br^b.). — ^Frond rather
more than twice as long as broad ; seg-
ments 3-lobed, basal portion subquadri-
lateral; lateral lobes horizontal, deeply
emai'ginate, end lobe much dilated,
straight or slightly concave at ends, angles
entire or emarginate. (ab, c.) Emptyfrond
punctate ; f. v. segments with, three in-
flations near the base ; tr. v. elliptic with
three inflations at each side and two at
each end ; e. v. end lobe with two minute
lobelets at each end, and two near them
at each side. Sporangium orbicidar, beset
with conical tubercles, (n. 10 & 30.)
L. 1-362" ; B. 1-558". G.B., I., F.

E. gemmatum (Kg., Br^b.). — Frond
scarcely twice as long as broad ; segments
8-lobed, lateral lobes horizontal, deeply
emarginate, the protuberatices minutely
granulate; end lobe dilated, its dilata-
tions inclined upwards, and minutely
granulate ; ends with a deep rounded emar-
gination. {ab, c.) Empty frond slightly
punctate; f. v. segments with three

franulate inflations near the base ; tr. v.
roadly elliptic, with three gi-anulate in-
flations at each side and one at each
end; e. v. end lobe cruciform, lobe-
lets rounded, granulate. L. 1-443" ;
B. 1-641". = Euastrum (Eucosmitim)
Hassallianum (Niig.). G.B., I., F.,
Prussia.

8 * Fr-oml without a distitict terminal lobe,
frequaitly having a process or acute
angle at corners of terminal portion,

E. rostratum (Ralfs). — Frond scarcely
twice as long as broad^ oblong ; segments
with their basal portion deeply emargi-
nate at the sides, connected by a broad

neck with the terminal portion; ends
protuberant, angular, acutely emarginate
at the centre, and having at each side
a horizontal subacute projection, (ab, c.)
Sporangium orbicular, spinous; spines
conical, attenuated. L. 1-050" to 1-580" :
B. 1-1000" to 1-714". (l 26.) G.B.,
I., F., U.S.A.

E. pulchellum (Br6b.). — Frond rather
more than one-third longer than broad,
oblong ; segments with the basal portion
twice or thrice acutely dentate at each in-
flated basal angle, and connected by a
broad neck with the tenninal portion ;
ends straight, acutely emarginate at the
centre, angles acutely mucronate; e.f.
bearing at the centre of each segment a
sitigle inflated proTnvnetice bordered by an
annular series of granules (in s.v. trun-
cate), and a few scattered granides near
the projecting paiis. (ab, c.) F.

E. elegans (Breb. , Kg. ) . — Frond minute,
scarcely twice as long as broad, oblong ;
segments with theu' basal portion emar-
ginate at the sides, connected by a broad
neck with the terminal poi-tion; ends
protube)-ant, rounded, acutely emarginate
at the centi'e, pouting ; s.v. with an infla-
tion at the base of the segments, sides
concave, ends rounded, (ab, c.) Sporan-
gium orbiculai", spinous. = E. bidentatum
(Nag.). G.B., I., F., G., U.S.A._ a, neck
somewhat constricted, end portion bear-
ing on each side an acute horizontal
spme-like projection. L. 1-888" to
1-445" ; B. 1-1441" to 1-714". ^, seg-
ments sinuated, neck not constiicted and
without spines. L. 1-421"; B. 1-654".
y, neck not constiicted, lateral projec-
tions beaiing minute spines directed ob-
liquely outwards. = E. spinosmn (Ilass.).
L. 1-884" ; B. 1-1388".

E. crenatum (Kg.). — Frond very
minute, about twice as long as broad,
segments pyi'amidal, tlieir lateral margin
crenate, ends broad, truncate, entire.
(ab,c.) F., G.

E. binak (Ralfs). — Frond verj' minute,
scarcely twice as lon^ as broad, oblong;
segments with theii' basal portion either
entire or bicrenate at the sides, slightly
contracted beneath the ends ; ends di-
lated, not protuberant beyond the angles,
its central notch acute, broad ; tr.v. with
two lateral inflations, ends trinicate,
angles rounded, (abc.') L. 1-15*0" to
1-1428"; B. 1-2400" to 1-1400". (in. 13.)
= HetcrocarpcUa binalis (Turp.), Om-
marium binale (Menoghini), E. SalfsH
(Kff.), E. lobuJatian (Bitsb.)? E. duhum
(ml). G.B., I., F., U.S;A. |8, frond
ratlier laiger, rough, with a few scattered

OF THE DESMIDIEiE.

731

granules ; margins of segments crenate ;
acute angles of end portion slightly
horizontally prolonged, its notch_ small,
rounded (probably a distinct species).

E. cuneatum (Jenner). — ^Frond large,
rather more than twice as long as broad ;
segments pyi-amidal, broadest at base and
naiTowing upwards, not lohed, the sides
almost straight; ends trimcate, central
notch linear. (oT^b'^c.) Empty frond

without inflated protuberances. L.
1-208" ; B. 1-420". G.B., I.

E. pelta (K^g.). — Frond about twice as
long as broad, oblong ; segments quadrate,
each lateral margin with a small rounded
protuberance or iiiflatioti at the hose,
another larger near the upper end, and
another somewhat larger still at the upper
angle; ends straight, not notched, (ab, c.)
= Cosmarium Pelta (Oorda). G.

Genus COSMAEIUM (Corda). — Frond more or less constricted; segments
undivided, usually rounded, sometimes slightly sinuated, or rarely slightly
contracted, somewhat extended and truncate at the ends, never notched,
neither provided with spines nor processes ; e.v. elliptic, and sometimes each
side with a lateral opposite inflation, or circular.

* Frond compressed ; central constnction
a deep, usually linear, incision ; e.v.
compressed, either elliptic or subcruci-
form, owing to the projectio7i at each
side of a protuberance or iit/lation.

t Margins of segments entire, neither
crenate nor granulate.

CosMAKiUM sublobatum (Br6b. sp). —
Fi'ond scarcely twice as long as broad,
oblong; constriction linear, segments
subquadrate, somewhat wider at the base,
lateral and end margins slightly concave,
smooth, ti-ansverse view cruciform. L.
1-523" ; B. 1-646". = Euastrum ? sublo-
batum (Br6b.). G.B., I., R, U.S.A.

C. pusillum (Br6b. sp.). — Frond very
minute, slightly broader than long, con-
striction acute, segments angulato-tra-
pezoid, slightly naiTowing upwards,
smooth, angles roimded, ends slightly
concave. = Euastrum 2ncsilhim(B}:6h7). F.

C. quadratum (Ralfs). — Frond about
twice as long as broad, constriction deep,
linear ; segments quadrate, slightly pro-
tuberant on each side at the base, with
rounded angles at the ends, smooth ; e.v.
compressed. L. 1-510"; B. 1-952".
G.B., F.

C. Cucumis (Corda). — Frond about
twice as long as broad ; constriction
deep, linear ; segments as broad as long,
with the basal angles rounded, bj-oadly
rounded at ends, smooth ; e.v. elliptic.
L. 1-.362" to 1-257"; B. 1-568" to 1-502".
—Euastrum inteqerrimumCEk]:.). G.B.,
I., F., G., Italy, tJ.S.A.

C. Ralfsii (Breb.). — Fi-ond large,
slightly longer than broad, orbicular,
constnction deep, linear ; segments se7m-
orhicular, rounded at basal angles,
smooth ; e.v. eUiptico-lanceolate ; endo-
chrome radiate. L. 1-227"; B. 1-270".
= C. Cucumis (l-Iass.). G.B., I., F.

C. rupestre (Nag. sp.). — ^Fi-ond rather
more than twice as long as broad, con-
striction not deep but linear ; segments
broadly oval, turgid, sides and ends
broadly rounded, smooth ; e.f. punctate,
puncta scattered. = Euastrum riqiestre
(Nag.). G. _

C. pyramidatum (Br^b.). — Frond
scarcely twice as long as broad, suboval ;
constriction deep, linear ; segments pjTa-
midal, rounded at basal angles, somewhat
truncate at the ends, punctate ; e.v.
broadly elliptic. Sporangium orbicular,
tuberculated. L. 1-471" to 1-264" ; B.
1-759" to 1-374". (ill. 14, e.v. 15.) = Pj-
thiscus angulosus (Kg.). G.B.,I.,F.,tJ.S.A.

C. lagenarium (Corda). — Frond about
twice as long as broad, subeUiptic ; seg-
ments triangular, pyramidal, punctate;
basal angles broadly rounded, sides some-
what concave, tapering, ends broadly
roimded. = C. ansatum (Kg.). G.

C. tinctum (Ralfs). — Frond very
rninute, about as long as broad, constric-
tion producing an acute notch at each
side; segments elliptic, about twice as
broad as long, smooth ; e.v. narrow
elliptic. Empty fi-ond somewhat reddish.
Sporangium quadrate, smooth, with an
empty segment of the conjugated fronds
permanently attached to each comer.
L. 1-2325" ; B. 1-2500". G.B., I.

C. bioculatum (Breb.). — Fi-ond minute,
about as long as broad; constriction
deep, producing a gaping notch at each
side ; segments about twice as broad aa
long, elliptic, smooth ; s.v. compressed ;
e.v. elliptic. Sjwrangium orbicular, with
conical spines. L. 1-1416" ; B. 1-1773"
G.B., I., F., U.S.A.

C. deprcssum TBailey). — Fi-ond de-
pressed, broader tlian long, constriction
a deep, nan-ow, acute notch ; segments
about twice as broad as long, angulur at

732

SYSTEMATIC HISTOEY OF THE INFUBOniA.

base, broadly rounded at ends, smooth.
U.S.A.

C. granatitm (Br^b.). — Frond minute,
somewhat longer than broad; consti'ic-
tion linear ; segments broader than long,
rapidly tapering, truncate-triangular,
smooth; s.v. compressed; e.v. elliptic.
L. 1-1234"; B. 1-1602". G.B., L, F.
• C. polygonum (Nfig. sp.). — ^Fi-ond mi-
nute, about one-third longer than broad,
constriction shallow, linear; segments
hexagonal, sometimes pimctate, lateral
margins and ends straight; e.v. elliptic
with a broad i-ounded inflatioyi at each
side. = Euastrum polygonum (Nfig. ) . G.

C. Phaseolus (Breb.). — Frond in f.v.
about as long as broad, constriction deep,
linear; segments reniform, smooth; e.v.
elliptic, with a slitfht conical projection at
each side. L. 1-787"; B. 1-833".=^.
depressum (Nag.) ? G.B., I., F.

0. Papilio (Menegh.^. — "Segments
smooth, triangidar, with rectangular
apex, sides very slightly sinuato-rmdu-
late, lateral angles produced, acute ; e.v.
linear with a lobe at middle of each side."
Euastrum ? Pajiilio (Kg.). G., Italy.

2t Margins of segments crenate or
slightly imdulate, sm-face not granu-
late.

C. Meneghinii (Bv4h.). — Frond very
minute, rather longer than broad, con-
striction linear; segments subquadi'ate,
bicrenate at the sides and ends, smooth;
e.v. elliptic. L. 1-853'' to 1-735"; B.
1-1250" to 1-1176". = C. bioculatum
(Menegh.), Euastrum bioculatum (Kg.),
E. angulosum (Breb.), E. crenidatum
(Nag.). G.B., I., F., G., Italy, U.S.A.

C. crenatum (Ralfs). — Frond minute,
not quite twice as long as broad, con-
striction linear; segments obsoletely
quadrate, crenate at the margin, flattened
at ends, surface punctate; e.v. elliptic.
Sporangivmi orbicular, spinous; spmes
very short and stout, swollen at base,
ancl divided at the apex. L. 1-474" ;
B. 1-67 8". = Euastrum? sinuosum (Kg.).
G.B., I., F.

C. tmdulatum (Corda).— Frond rather
larger than last, slightly longer than
broad, constriction linear; segments
semiorbiailar, etids and sides broadly
rounded, crenate or minutely imdulate
at margin; e.v. elliptic. Sporangiimi
orbicular, spinous ; spmes elongate, slen-
der, swollen at the base and divided at
the apex. L. 1-416"; T$. 1-571". (ii.
3.3, spor. 34). = Eimstrum crcnu/atum, c
(Nag.) P G.B., I., F., U.S.A.

0. NcBgelianum (Br6b.). — Frond in f.v.
slightly longer than broad, constriction
deep, hnear ; se^ents broad at the base,
rapidly narrowing upwards, sides with
several minute sinuations, ends broadly
truncate, straight or very slightly undu-
late, obscm'ely pimctate ; e. v. elliptic,
sometimes somewhat inflated at the
sides. =Euasti-U77i (Cosmariuni) crenatufn
(Nag.). F.,G.

C. tetragonum (Nag. sp.). — Frond in
f.v. about twice as long as broad, oblong,
constriction linear; segments subquad-
rate, somewhat naiTowing from the base,
sides and end each -wath three slight
sinuations, those of the ends rather
smaller, in each half one large central
granule ; s.v. segments oval, rounded,
constriction shallow. — Euastrum tetra-
gonum (Nag.). I., G.

C. venustuni (Br6b. sp.). — Frond some-
what longer than broad, constriction
deep, linear ; segments slightly narrowed
upwards, with two somewhat deep sinua-
tions at the sides, ends broad, truncate,
slightly concave at the centre. = Euastrum
venustum (Breb.). F.

3t Fronds rough on the sm-face, with
pearly gi-anules, which give a denticu-
late appearance to the margin.

C. tetraophthalmum (Kg., Br(5b.). —
Frond about a third longer than broad,
constriction deep, linear; segments /bj-wi-
ing nearly two-thirds of a circle, rough on
the sm-face with shoH and broad scattered
pearly granides, giving a crenate appear-
ance to the margin : e.v. broadly elliptic.
Sporangium orbicular, spinous ; spines
swollen at base, finelv branched. L.
1-232"; B. 1-1326". "G.B., I., G., F.

0. Brebissonii (Menegh.). — Frond
somewhat longer than broad, constric-
tion deep, linear; segments semiorbictdarf
rough all over with somewhat elongate-
conical scattered pearly aranules ; e. v.
elliptic. L. 1-285"; B. 1-460". = C. mar-
garitiferum (I^g.) ? G.B., I., F., G.

C. conspersum (Ralfs). — ^Frond about
a third longer than broad, constriction
deep, linear; segments quadrilateral-,
angles roimded, rough nil over with de-
pressed gi-anides aiTauged in lines ; e.v.
elliptic. L. 1-162"; B. 1-357". = C.
Brdbissonii (Menegh.) ? G.B., F.

C. Ungenanum (Niig.).— Frond large,
rather longer than broad, constnction
deep, lineal- ; segments much inflated at
tlie base, angl<'S and sides rounded, nar-
rowing upwards, ends broadly truncate,
rougli at the margin, with n few large

OF THE DESMIDIEiE.

733

rounded pearly granules placed in Imes,
the disc punctate ; e. v. broadly elliptic,
the large pearly granules confined to the
rounded extremities, regularly disposed in
a few evident lines, the intermediate
central space punctate. "L. 1-37"'; B.
1-'^"'.'" = Euastrum (Cosmanum) Un-
gerianum (Nag.). G.

C. ovale (Ealfs). — Frond very large,
elliptic, neai'ly twice as long as broad,
constriction very deep, lineai" ; segments
somewhat broader than long, somewhat
triangular, rounded at ends, rough near
the margin, with a hand of large pearly
gramdes, producing a dentate appear-
ance, the disc punctate; e. v. elliptic.
L. 1-139" ; B. 1-240". G.B., R, U.S.A.

C. prcemoi-sum (Brdb.). — Frond rather
longer than broad, constriction deep,
linear ; segments h-oadly reniform, sides
roimded, ends somewhat truncate, rough
"^\'ith pearly granules, an anmdar series
of ichich,more elevated than the rest, forms
a ridge at the end hounding a circular
depression ; e. v. elliptic. F.

C. margaritiferum (Menegh.). — Frond
about as long as broad, constriction deep,
linear; segments reniform or semiorbi-
cidar, rough all over with round and
scattered pearly granules; e. v. elliptic.
Sporangiimi orbicular, spinous ; spines
branched at apex. L. 1-566" to 1-306" ;
B. 1-694" to 1-416". (i. l.)=Ursinella
margaritifei'a (Turpin), JEicastj^cm mar-
garitiferum (Ehr., Nag.), C. punctulatum
(Bret.) ? G.B., I., F., G., Italy, U.S.A.,
Mexico.

C. PoHianum (Archer). — Frond about
one-third longer than broad, constriction
deep, wide, somewhat round below, isth-
mus foi-ming a short neck; segments ellip-
tic, rough all over with minute scattered
pearly tjranules ; e. v. elliptic. L. 1-600" ;
B. 1-930". I.

C. latum (Br^b.). — Frond large, about
as broad as long, constriction deep, sub-
linear; segments reniform, rough with
rounded pearly granules arranged in
someiohat curved transverse lines; e.v. ? F.

C. notahile (Br6b.). — Frond about one-
third longer than broad, constriction
somewliat dee^, acute ; segments slightly
longer than brond, broadest at the base,
gradually 7iarroiving upwards, sides con-
vex, ends tnmcate, rotcgh all over with
broad pearly granules, giving a crenate
appearance to the margin (endochrome
in bands) ; e. v. oval, turgid. Sporan-
gium orbicidar, besot with nimierous
short .stout spines, inflated at the base,
and deeply divided at the apex. F., G.

C. amnenum (Br^b.). — Frond twice as

long as broad, sides parallel, ends i-ounded,
constiiction deep, linear; segments rough
with o'owded obtuse papiUa-like pearly
gramdes ; s. v. much compressed, about
thrice as long as broad ; e. v. elliptic.
L. 1-568" ; B. 1-1141". G.B., F., U.S.A.

0. Botrytis (Menegh.). — Frond rather
longer than broad, consti'iction deep,
linear ; segments twice as broad as long,
broadest at base, narrotving ujnvards, sides
rather rounded, ends truncate, rough all
over with scattered rounded pearly gra-
nules ; e. V. broadly elliptic. Sporangium
orbicular, spinous; spines elongate and
slightly divided at the apex. L. 1-469"
to 1-327"; B. 1-625" to 1-419". = 2re!:e-
rocarpella Hotrytis (Bory), C. deltoides
(Corda), Euastrum Botrytis (Ehr., Kg.,
Nag.), E. angulosum (Ehr.). G.B., I.,
G., F., Italy, "U.S.A.

C protractuni(^'?i^. sp.). — Frond about
as broad as long, constriction deep, linear ;
segments twice as broad as long, infiated
and broadest at the base, rapidly tapering
into a someiohat evident neck, sides very
concave, ends abruptly ti'imcate, rough all
over vsdth scattered pearly granules ;
e. V. broadly elliptic, slightly injlated at
the middle, and gi-adually sloping to the
rounded ends. L. 1-55"' to 1-33"'. =
Euastrum protractum (Nag.). G.

C. gemmife)-um (Breb. in lit. c. ic).

Frond in 1. v. about as long as broad,
consti-iction deep, sublinear; segments
broadest at the base, gi-aduaUy nai-rowino-
upwards, sides convex, ends truncate,
rough all over with peai-ly gramdes,
somewhat arranged in radiating lines,
each segment furnished at the middle,
on both surfaces, with a rounded protu-
berance bordered with granules ; e. v.
broadly elliptic, with the central trun-
cate protuberance on each side. F.

C. Tunnnii (Br6b.).— Frond about as
long as broad, constiiction deep, linear ;
segments twice as broad as long, some-
what ti'iangular, much injlated and
broadly rounded at the base, raindly at-
tenuated, sides concave, ends truncate
rough all over with scattered pearly
granules, and with a central gi-aiuilated
protuberance ; e. v. narrow-elliptic, Avith
the central broad truncate protuberance
on each side. = Heterocarpella Didelta
(Tm-piu), C. Dideltn (Kg.). F., G.

C. biretum (Bri^b.). — Fi-ond in f. v.
about as long as broad, constriction deep"
linear; segments quadrilateral or sub-
hexagonal, narrowest at the base and
dilated upwards, convex or somewhat
truncate at ends, rough all over with
small granules arranged somewhat in

734

SYSTEMATIC HI8T0BY OF THE INFUSOMA.

lines ; e. v. with a rounded lobe on each
side and rounded at ends. L. 1-333" ;
B. 1-372". G.B., F, Var. triquetrum
(Br^b.) : e.v. with three rounded angles,
sides deeply sinuous !

0. Broomei (Thwaites). — Frond in
f. T. aboiit as long as broad, constriction
deep, linear ; segnrents quadrilateral, ends
straight, angles rounded, rough all over
with ininute granules ; e. v. twice aa long
as broad, slightly inflated at the middle
and rounded at the ends. Sporangium
orbicular, smooth. L. 1-500"; B. 1-540".
(1.7.) G.B., F., U.S.A.

C. ccelatum (Ralfs). — Fi'ond in f. v.
about as long as broad, suborbicular, con-
striction deep, linear; segments semior-
bicular, with six broad crenatures at mar-
gin, rough at margin with scattered
pearly graniiles, and at the centre with
granides somewhat concentncally ar-
ranged; e. V. twice as long as broad,
with a broad inflation at each side. L.
1-921" to 1-581"; B. 1-1024" to 1-608".
(n. 26.) G.B., I., F.

C. ornaticm (Ralfs). — Frond in f. t.
about as long as broad, constriction deep,
linear; segments semiorbicular or sub-
renifomi, with a central truncate pro-
jection at the etids produced by the con-
tinuation of a central inflation, rough
towards the margins and on the inflation
with pearly granules ; e. v. with a rounded
lobe 071 each side. Sporangium orbicular,
spinous ; spines elongated, dUated at the
base, and slightly divided at the extre-
mity. L. 1-613"; B. about the same.
G.B., F., U.S.A.

C. Sportella (Br^b.). — Frond about as
long as broad, constiiction deep, linear ;
segments renifonn, with a central trun-
cate projection at the ends, its angles
slightly dilated and denticulate, rough all
over with scattered pearly granules. F.

C. Corbula (Breb.). — jFrond about aa
long as broad, constriction deep, linear ;
segments subreniform, a central truncate
projectio7i at the ends with its angles
slightly dilated and minutely denticulate;
furnished at the centre of each segment
with a circular protuberance bordered with
gramdes, and rough thereon and towards
the marqins with scattered pearly gra-
nules. F.

C. co7nmissurale(B\-&o.). — Frond small,
in f. V. one-third broader than long ;
constriction very deep, roimded ; seg-
ments narrow-reniform, with a central
somewhat truncate projection, produced by
the continuation of the central inflation,
rough on the injlation and on the extre-
mities with somewhat large pearly gra-

nules ; e. V. tliree times longer than
broad, constricted between tlie central in-
flation and the rounded extremities. Spo-
rangium as in C. omatum. L. 1-923" •
B. 1-663" to 1-609". G., B., F. /3
acutum (Br(Sb.), angles sharper.

0. cristatum (Ralfs). — Frond in f. v.
as long as broad, orbicular, constriction
deep, linear ; segments semiorbicular,
margined by a series of obtuse papilla-
like pearly granules, and having at the
centre of each a circular granulate infla-
tion ; e. V. linear, truncate at ends, with
a slight centi-al inflation at each side.
L. 1-700"; B. 1-653". G.B., F.

C. pluviale (Brdb. in lit. c. ic). — Frond
about one-third longer than broad ; con-
striction a shallow wide notch ; segments
subovate, gradually tapering, ends round-
ed, or broadly rotundato-truncate, 7-migh
all over vnth minute granules ; e. v.
elliptic. F.

2* Frond not compressed; central con-
striction rarely a deep, never a linear,
incisimi, but merely the result of the form
of the contracted bases of the segments ;
e.v. circular, or, very rarely, compressed.

t Frond rough with pearly granules,
which give a denticulate appearance
to the outline.

C. Colpopelta (BriJb. in lit. c. specimine).
— Frond rather more than twice as long
as broad ; constriction a shallow contrac-
tion ; segments somewhat widening up-
wai'ds from the base, oval, sides and ends
broadly rounded, very minutely granulate,
gi'anules scattered ; e.v. cii'cular. F.

C. cylindricum (Ralfs). — Frond minute,
in f. v., about twice as long as broad ;
segments subquadi'ate, narrower at the
junction and gradually widening upicards,
ends truncate, rough all over with pearly
granvdes somewhat arrartqed in lines;
e. V. circulai-. L. 1-588" ;' B. 1-1060".
(m. 16, e.v. 17. )=Pcniu?n Ealfsii (K^.)-
G.B., L, F.

C. striolatum (Nag. sp.).— Frond in f.v.
about twice as long as broad, eUiptic;
constiiction a shallow rounded sinus;
segments with sides and ends broadly
rounded, pearly gi-anules arranged in lines
and giving the margin a crcnate appear-
ance, cxce)->t at the central sinus, whch «
smooth. L. 1-16"'; B. l-S3-". = I>y-
sphinctiuni striolatum (i^'d^.). 0.

C. o>-6!«<;rti:«;» (Ralfs).— Frond minute,
in f. v., twice as long as broad ; constnc-
tion deep; segments .'spherical, rough all
over, except at the neck-like contrac-
tion, with pearlv granules ; e. v. circular.

OF THE DESMlDIEiE.

735

Sporang-ium orbicular, spinous; spines
short, stout, conical. L. 1-498" to 1-454" ;
B. 1-750". =Peniimi orhiculatum (Kg.).
G.B., F.

2 1 Frond smooth.

C. moniliforme (Ralfa). — Fi'ond mi-
nute, in f. V. twice as long as broad ;
constiiction deep ; segments spherical,
smooth; e. V. circidai". L. 1-617"; B.
1-1131". = Tessarthronia mmnlifonnis
(Turp.), Tessarthra moniliformis (Ehr.).
G.B., I., F., G.

C. connatum (Br^b.). — Frond large,
in f. V. about one-balf longer than broad ;
constriction shallow ; segments about two-
thirds of a circle, coaiselj punctate, and
with a distinct, sometimes striated, boi--
der; e.v. circidar. L. 1-285;'; B. 1-1155".
= Dysphinctium Meneghinianum (Nag.).
G.B., F., U.S.A.

C. Cucurhita (Br^b.). — Frond in f. v.
about twice as long as broad ; constric-
tion a shallow gi'oove; segments sid)-
cylindrical, or somewhat oval, with
rounded ends ; e. v. circidar ; e. f. punc-
tate, the puncta scattered. L. 1-586" ;
B. 1-1155". =Peniumclandestinmn (Kg.).
G.B., I., F., G.

C. Palangula (Br6b.). — Frond in f. v.
about two and a half times as long as
broad ; constriction a shallow gi'oove ;
segments cylindrical ; ends obtuse ; e. v.
circidar ; e. f. minutely punctate, the
pimcta arranged in transverse lines. F.

C. ? cniciferum (De Bary). — Frond
minute, in f. v. about twice as long as
broad ; constiiction an extremely shallow
groove ; segments subcylindrical ; ends
broadly rounded ; endochrome composed
of four broad plates cutting each other at
right angles ; e. v. circular, endochrome
cruciform ; e. f. not punctate. L. 1-143"';
B. 1-287"'. G.

C. TJiwaitesii (Ralfs). — Frond in f. v.
two or three times longer than broad;
constriction a very shallow groove ; seg-
ments subcylindrical, with rounded ends ;

endochrome scattered ; e. v. circular, or
very slightly compressed; e.f. not punctate,
or puncta veiy indistinct. L. 1-357";
B. 1-801". = Penium crassiusculum (Be
Bary) ? G.B., F., G., U.S.A.

C. curium (Br6b.). — Frond in f. v.
rather more than twice as long as broad ;
constriction very shallow; segments at-
tenuated and rounded at ends ; endochrome
in fillets ; e. v. circular, endochrome ra-
diate. L. 1-465" ; B. 1-1064". = Penium
curtum (Breb., Kg.), Dysphinctium Rege-
lianum (Niig.) ? G.B., F., G.

C. attenuatum (Br6b.). — Frond in f. v.
fiisifoi-m, three, or sometimes four, times
longer than broad ; constiiction very
shallow; segments conical, rapidly at-
tenuated, ends angular, obtuse ; e. v. cir-
cular ; e. f. punctate. L. 1-420" ; B.
1-1099" to 1-1068". G.B., F.

0. parvulum (Brdb.). — ^Frond minute,
in f. V. ovato-eUiptic, about one and a
half times longer than broad ; central
constriction a very shallow groove ; seg-
ments tapering, ends broadly rotundato-
truncate ; e. f. not punctate. F.

C. turgidum (Br6b.). — Frond veiy
large, in f. v. oval, turgid, rather more
than twice as long as broad ; constriction
a shallow sinus ; segments somewhat
tapering, broadly rounded; e. v. circidar;
e. f. punctate. L. 1-126"; B. 1-249".
= Pleurotcenium turgidum (De Baiy).
G.B., F., G.

0. De Baryi (nobis). — Frond in f. v.
about twice as long as broad ; constric-
tion a wide shalloio notch ; segments
cylindrical, with broadly rounded ends ;
endochrome an-anged in parietal indented
bands ; e. v. circular ; e. f. minutely punc-
tate or pimcta absent. = Pleurotcenium
Cosmarioides (De Baiy). G.

With gi-eat deference, we place the
above species here, as described by
M. de Bary, coinciding with M. de Bt6-
bisson in thinking the disposition of the
endochrome not sufficiently constant to
form the genus Pleurotoenium.

Genua XAOTHIDIUM (Ehr.). — Frond deeply constricted ; segments
broader than long, compressed, entire, sjpinous, having a circular, cylindrical
or conical projection on both surfaces near the centre, wluch is tuberculated or
dentate, or entire ; end view elliptic.

nated by three or four diverging points ;
central projections cylindrical, "truncate,
the border dentate; e. {. punctate. "Spo-
rangium large, orbicular, with depressed
tubercles ; perhaps immature " (Ralfs)
L. 1-180"; B. 1-270". (i. 27, 28.) =
Zi/goxanfhinm Echinus (Kcr.). G.B.. I
F.,G., U.S.A. ^ ' ■'

* Spines divided at the apex.

Xanthidium armatum (Br6b.). —
Frond large, in f. v. twice as long as
broad ; constriction deep, linear ; seg-
ments broadest at the base ; ends rounded
or .somewhat truncate ; spines in pairs,
principally marginal, short, stout, termi-

736

SYSTEMATIC HISTOSY OF THE Effl-USOBIA,

X. (?) Artiscon (Ehr.).— Fi-ond in f. v.
about as long as broad ; constriction
forming a wide notch ; segments narrowed
at the base, with broadly rounded ends ;
spines numerous, restricted to the outer
margin, scattered, elom/ate, stout, termi-
nated by three or fom* diverging points.
= Asterozanthium Arctiscott (Kg.). G.

2 * Seines subulate.

X. aculeatiim (Ehr.). — Fi-ond in f. v.
broader than long ; constriction deep,
linear ; segTiients somewhat reniform ;
spines subulate, short, scattered, chiefly
marginal ; central protuberance cylin-
diical, tnmcate, border minutely dentate.
L. (not including spines) 1-380" ; B.
1-1347" to 1-393". = Zygoxanthium
acideatum (Kg.). G.B., I., F., Italy, G.

X. Brebisso')iii (Ralfs). — Frond in f. v.
broader than long; constriction deep,
acute, not liaear; segments subelliptic,
sometimes irregular ; spines subulate,
geminate, marginal ; centi-al protuberance
cylindrical, truncate, border minutely
dentate. L. (not including spines') 1-416";
B. 1-408" to 1-365". = X. bisenarium
(Ehr.), Zygoxanthium aculeatum (Kg.).
j3, segments broader and more irregular,
spines somewhat iri'egular and unequal.
G.B., L, F., G., U.S.A.

X.. fasciadatum (Ehr.). — Frond about
as long as broad ; constriction deep,
linear; segments somewhat reniform or
subhexagonal, twice as broad as long ;
spines slender, subulate, geminate, mar-
guial, in four or six pairs ; centi'al pro-
tuberance short, conical, somewhat tnm-
cate. a, segts. with four pairs of spines.
= X. antilopceum (Breb.), X. polygonum
(Hass., Breb.). L. (not including spines)

1-454" to 1-350"; B. 482" to 408". 0,
segts. with six pairs of spines. =X fasci-
culatum, var. polygonum (Ehr.), X. fas-
ciculatum (Hass., Br6b.). L 1-481" •
B. 1-516". G.B., I., F., G., Italy, U.S.a!

X. cristatum (Br6b.). — Frond rather
longer than broad; constriction deep,
linear ; segments subreniform, or truncate
at ends ; spiaes sti-aight or curved, subu-
late, marginal, one at each side, at the
base of the seytnetit, solitary, the otliers
geminate, in four pau's; central protu-
berance short, conical, a, segts. reni-
foiin, spines scarcely cm-ved. L. (not
including spines) 1-357"; B. 1-499".
(n. 18 & 23.) jS, segments truncate at
ends, spines uncinate. L. 1-469"; B.
1-625". G.B., I., F., U.S.A.

X. Smithii (Ai-cher). — ^Frond minute,
in f. V. about as long as broad ; constiic-
tion Ja wide notch ; segments twice 33
broad as long, trapezoid, lower margin
somewhat convex, sides nan-owing up-
wards and sti-aight, ends broad and
straight, angles rounded, each of the four
angles presenting a pair of somewhat
divergent, short, minute, acute spines ; s. v.
constiictiou shallow, obtiise ; segments
with rounded sides, ends ti'vmcate, each
upper angle furnished with a ininute qnne,
beneath each of ichich, about half way
down, there occurs another similar spine,
all the spines somewhat divergent ; e. v.
subelliptic, or broadly fusiform, ends
blunt, rounded, furnished with three mi-
nute spines, none on the sides; central
protuberance a minute tubercle, apparent
always in this view, but in s. v. some-
times hidden by the projecting centi-al
spines. L. 1-1166" ; B. 1-1272". G.B.

Genus AKTHRODESMUS (Ehi-.).— Frond deeply constricted ; segments
compressed, either with four prominent angles and a single or geminate sjiine,
or a tooth, at each angle, or having one spine or acute tooth only, on eacli side,
at each upper or outer extremity ; without a central projection ; e. v. elliptic
or fusiform.

* Segments with four prominent angles
and a simple or geminate spine, or an
acute tooth, at each angle.

AuTHiiODESMtrs octocomis (Ehr.,
Hass., Brdb.). — Frond smooth, mmute,
about as long as broad; constriction a
wide notch ; segments much compressed,
trapezoid, each angle terminated by one
or two straight, subulate, acute spines, the
intervals between the angles concave.
«, spine solitarv nt each angle. L.
1-1351"; B. 1-1538". (1.30.) /3 larger.

spines geminate at each angle. L.
1-1020" ; B. 1-906". (i. 29.) = Micra-
sterias octocornis (Menegh., Kg.), Xan-
thidium octocome (Ehr., Ralfs). G.B.,
I., F., G., Italy, U.S.A.

A. bifldus (Bi-db.). — Fi-ond .smooth,
very miimte, about as broad n.« long:
segments someichat arcuate, inner margin
convex, outer concave, extremities diver-
gent, emarginate, each angle tertmiiattng
m an acute tooth ; e. v. compressed, fusi-
form, with a short acnte .opine or tooth
nt each end. F.

OP THE BESMIDIE^.

737

2 * Se(/me)its with a sint/lv acute tooth or
spine at each side.

A. minutus (Kg.). — Fi'ond veiy mi-
nute, smooth, two or three times longer
than hroad ; constriction a minute acute
notch ; segments narroio, lateral tnargins
parallel, ends roimdly concave, angles
slightly produced into minute spmes
directed upwai'ds. F., G.

A. Pittacium (Breb. sp.). — Fi'ond mi-
nute, smooth, two or tlu'ee times longer
than broad ; constriction a minute acute
notch : segments very slightly infiated at
the base, sides curved, end margin rotmdly
concave, angles acute. = Euastrutn Pit-
tacium (Brt5b.). F.

A. Incus (Hass.). — Fi'ond minute,
smooth, as long as or longer than broad ;
constriction a deep notch or sinus ; seg-
ments with inner margin turgid, outer
truncate, spines subulate, acute. Sporan-

gium orbicular, spinous ; spines subidate.
G.B,, I., F., G., U.S.A. a, segments
somewhat semiorbicular, connected by
a distinct neck, spines diverging. L.
1-1100" to 1-1660"; B. 1-1960" to
1-1420". )3, segments gibbous near the
base, spines parallel or converging, (m.
36.) L. 1-833" ; B. 1-1116".

A. suhulatus (Kg.). — Frond minute,
smooth, about as long as broad; con-
striction a wide acute-angled notch ;
segments broadly fusiform, spines hori-
zontal, straight, slender, subulate; ends
convex. G., U.S.A.

A. convei-gens (Ehr.). — Frond smooth,
broader than long; constriction deep,
acute ; segments elliptic, each having Its
lateral spines curved towards those of the
other; ends convex. L. 1-1539" to 1-598" ;
B. 1-1477" to 1-584:". = Stawastrum con-
vergens (Menegh.), Eiiastrum converqens
(Niig.). G.B., I., F., G., U.S.A.

Genus STAURASTRUM (Meyen). — Frond more or less deeply constricted
at the middle ; segments broader tban long, often provided with spines or
processes ; end view angular or radiate, or circular luitli a lohato-racliate
margin, or very rarely compressed with a process at each extremity.

* Segtnents in f. v. with each of the oppo-
site lateral extremities furnished with a
mucro or a simple subulate acute awn
or spine, which in e. v. terminates the
angles, and without others intermediate.

t Segments smooth, angles in e. v.
inflated, sides concave.

Staxirastiium clejectum (Brdb.). — Seg-
ments in f. V. lunate or elliptic, smooth,
mucrones or awns directed upwards, pa-
rallel or convergent ; e. v. with three or
four angles, angles infiated, mammillate,
tenninated by a mucro or awn, sides
concave at the centre. Sporangium or-
bicular, at first covered with minute hau-
like spines, aftei'\vards beset with stout
subulate spines, and placed between the
deciduous empty fronds. L. 1-833" ; B.
1-757".= Goniocystis (Trigonocystis) mu-
cronata (Hass.). a, segments externally
limate, awns directed outwards ; /3, seg-
ments elliptic, awns parallel ; y, awns
converging. G.B., I., F., U.S.A.

S. apiculatum (Br^b.). — Segments ' in
f._ V. somewhat tm-binate, smooth, oppo-
site lateral extremities roimded, external
margin straight, furnished at each side on
the upper outer margin near the lateral
extremities imth a simple, .short, subulate,
acute spine directed upwards ; o. v. with
three angles, angles inliatcd, mammillate,
terminated by a short acute spine, sides

concave. Sporangium orbicidar, beset
with conical spines, enlai'ged at the base
and obtuse at the apex. F.

S. Dickiei (Ralfs). — Segments in f. v.
subelliptic, turgid, smooth ; spines short,
curved, acute, converging with those of
the opposite segment; e. v. with three
angles, angles infiated, rounded, tenni-
nated by a spine, sides concave at the
centi-e. L. 1-855" ; B. 1-929". G.B.,I.,F.

S. brevisjnna (Br6h.). — Segments in f.v.
elliptic or somewhat reniform, t;ery tur-
gid, smooth ; mucrones minute, inconspi-
cuous; e. V. with three angles, angles
inflated, broadly roimded, tenninated by
an inconspicuous mucro, sides concave at
theceuti-e. L. 1-502" ; B. 1-510". G.B.,
I., F.

S. cuspidatum (Br^b.). — Segments in
f. V. fusiform, or truncate on outer mar-
gin, connected by a long narrow band,
smooth ; awns subulate, straight, acute,
parallel or somewhat converging ; e. \.
with three or four angles, angles inflated,
mammillate, terminated by an awn, sides
concave at the centre. Sporangium or-
bicular, covered all over by the enlarged
bases of the few spines, which are ulti-
mately much attenuated and acute. L
1-883" ; B. 1-1000". (i. 31-;U.) = Phyc-
astrum cuspidatum (Kg.), P. spinidosum
(Niig.). G.B., I., F.,G., Italy.

S. aristifcrum (Ralfs). — Segments
3 B

738

SYSTEMATIC HISTOnV OF THE INFUSOUrA.

smooth, iu f. v. prolonged at each lateral
extremity into a mamniillate projection,
which is terminated by a subulate, acute,
straight awn, the awns divergent ; e. v.
with three or four angles; angles inflated,
mammillate, terminated by an awn, sides
deeply concave at the centre. L. 1-657";
B. 1-1064". G.B., F., U.S.A.

2 1 Segments smooth, angles in e. v. not
inflated, sides straight, or nearly so.

S. O'Mearii (Archer). — Segments
smooth, in f. v. somewhat cuneiform,
gradually widening u/pwards, outer margin
truncate, awns acute, divergent ; e. v. with
thi'ee or fom* acute angles terminated by
an awn, sides straight. Sporangiiun orbi-
cular, spinous; spines subulate, acute,
xiltimately somewhat inflated at the base.
a, e. V. with ,fom' angles, awns compa-
ratively short. L. 1-1866"; B. 1-2500".
/3, e. V. with three angles, awns longer.
L. 1-1750" ; B. 1-2300". I.

S. minus (Kg.). — Segments smooth,
very minute, in e. v. with Jive angles, each
terminated by a ve)-y minute acute spine ;
sides straight. G.

S. glah-um (Kg.). — Segments smooth,
in £ V. cimeate, ends concave or sti-aight,
spines slender, mucro-like; e. v. with three
mucronate angles, sides concave. I., G.

Sf Segments rough with minute
graniUes.

S. Iu7iatum (Ralfs). — Segments in £ v.
externally lunate, the inner margins con-
vex, the outer somewhat tmncate, and
rough with minute granules; spines subu-
late, acute, curved, obliquely directed out-
wa7-ds and upwards ; e. v. with three in-
flated rounded angles, terminated by a
spine, sides concave at the centre. L.
1-856" ; B. 1-686". G.B.

S. granulosum (Ralfs). — Segments in
f. V. broadly fusiform, granidate, lateral
extremities pointed, mucronate; e. v. with
three subacute mucronate angles, sides
convex. =Desmidium granulosum (Ehr.),
S. acuturn (Br^b.). F., G.

2 * Segments in f v. with each of the op-
posite lateral extremities f urnished with
a mucro or a simple subidate s^yiiic,
which in end view terminates the angles,
and is accompanied by othci's interme-
diate of a similar character.

S. pungens (Br4b.). — Segments in £ y.
externally lunate, the inner mai-gin
curved, tho outer truncate, smooth ; the
lateral marginal spines subulate, curved,
directed obbquely outwards and uj)wards,

with six other spines on the outer margin,
also directed outwards ; e. v. with three
angles, each terminated by a spine, and
with two others at its base on tlie upper
surface, and divergent at opposite sidles,
sides nearly sti-aight or slie-htlv convex-
G.B., F., U.S.A. ^

S. cristatum (Nag. sp.).— Segments in
£ V. broadly elliptic, inner margia some-
what more tm-gid than the outer, sub-
mammillate at each side, terminated by a
mucro or short sjnne, and possessing on the
outer margin a few otliers directed totcards
the angles : e.v. with three subacute mu-
cronate angles ; sides convex, with an in-
wardly curved, submargmal, single series
of short mucro-like spines directed to-
wards the angles, sometimes wanting
near the middle. L. 1-540" ; B. 1-543".
= Phycastrum (Pachy actinium') cristatum
^ag.), Staurastmm riitidum (Archer).

3 * Segments with each of the opposite
lateral extremities furnished with a bifid
or forhed spine, its subdivisions subulaf.e,
acute, in e. v. terminating the angles,
and a2Jpearing as a inucro-like spine,
with or without intermediate spines.
S. Avicula (Breb.). — Segments in £ v.
triangular or cuneate, ends truncate,
smooth, with a single forked spine on
each side ; e. v. with three inflated angles,
the bifid spine appearing as a mucro, sides
concave. L. 1-967"; B. 1-948". (m. 18;
e.v. 19.) G.B., F.

S. denticulatum (Nag. sp.). — Segments
in £ V. subelliptic, inner mai-giu some-
what more tiu-gid than the outer, botli
undulate or toothed in a scolloped maimer,
with an unequally forked or geminate
spine on each side, the upper longer than
the loicer, the lateral projections haritig a
series of transverse rows of minute gra-
?iules ; e. v. with three subacute angles.
the spine appearing as a mucro, sides
slightly concave at the centre, the mar-
gin toothed as mentioned before. "L.
1-70"'; thiclmess \-^"' =Phycasti-um
denticulatum (Nag.). G.

S. armigerum (Brilb.).— Segments m
£ V. turgid on inner margin, outer trun-
cate, smooth, with a forked s}nnc on each
side, and a few simple or forked, someUnm
minute, spines disposed at equal tntervals
between, on the outer margin : e. v. with
three angles, the bifid spine appearing as
a mucro, and the intermediate spines
projecting on each side. Sporangium or-
bicular, spines numerous, elongate, sub-
linear, forked at the apex. = S. .'ijnnosutn
(Ralfs). G.B., I., F.

OF THE DESMIDIEiE.

739

S. monticulosimi (BriSb.). — Segments
in f. V. broadly elliptic, smooth, with a
forked spme on each side, and at the end
six stout conical projections directed up-
wards, each terminated by an acute spine ;

e. V. -with three or foiu- acute angles, sides
concave, the terminal jxrojections extend-
ing on each side, conjluent at their bases,
from beneath which a minute, subidate,
spine-like projection arises between them
and each angle. L. 1-500" ; B. 1-700".
= Stephanoxanthiu7)i monticulosum (Kg.).
Ct.B., I., F.

S. Ehrenbergianum. — The longitudinal
outline of the segments oblic[uely oval,
the inner margin convex, diverging, the
outer mai'gin very convex and broadly
truncate at the ends ; the sides in e. v.
slightly imdulate, membrane smooth,
having at each angle a large spine, di-
vided to the middle, consisting of two
legs, and on the terminal sm'face three
pairs of such spines, and between each
of them and the angles a pair of smaller
simpler spines. = Phycastrmn Ehrenber-
gianum (Nag.). "L. 1-66"' 5 thiclmess
1-70"'." We have not seen a drawing
of the above species, and give the above
description foUowing as nearly as pos-
sible Nageli's own words, inserting it
here as most probably its most fitting
place.

4* Segments with numerous simple acute
spines, in f. v. no one in particular ter-
7ninating the opposite latm'al extremities;
e, V, angles entire, rounded, the spines

I scattered.

S. hirsutum (Br^b.). — Segments in f.v.
semiorbictdar, separated by a linear con-
itriction, covered tcith very minute, very
numerous, close-set hair-like spines ; e. v.
with three broadly roimded angles, the
spines evenly and numerously scattered ;
sides slightly convex. Sporangium or-
bicular, beset with short spines, branched
at the apex. L. 1-676" to 1-408"} B.
1-8.33" to l-QQQ".=Xanthidium hirsutum
(Ehr., KgA Gonioeystis (Trigonoci/stis)
muricata (flass.). G.B., I., F., U.S.A.

S. pilosum (Niig. sp.). — Segments in

f. v. obliquely elliptic, slightly divergent,
the outer margin more turgid than the
inner; e. v. %vith three roiuided, angles,

ides concave ; scattered all over, except a
Mnall space at the centre, with extremely
fine hair-like spines, minutely capitate at
their extremities; surface between the
spines smooth. "L. 1-55"' ; thickness
1-06"'. Phycasinim pilosum (Hi dg.). M.

de Brebisson is disposed to doubt the
accm'acy of Nageli's drawing (Einzell.
Alg. 8 A. fig. 4), the spines are indeed
so very cuiious.

S. Jirebissonii (nobis). — Segments in
f. V. ovato-lanceolate, the lateral extre-
mities roimded and fiu'uished thereon
with numerous short, close-set, hair-like
spines, otherwise smooth ; e. v. with three
broadly roimded angles, the spines con-
jined to the extremities, sides concave. =
S.|?i7osw7?z (Br6b.). F. We are obliged
to alter the specific name of this species,
— pilosum having been employed by Na-
geli before for the preceding species.

S. erosum (Br^b). — Segments in f. v.
elliptic, the lateral extremities furnished
with numerous extremely short acute
spines, sometimes inconspicuous, siu-
face granulated all over ; e. v. with three
broadly roimded angles, the spines con-
fined to the angles, sides concave. F.

S. echinatum (Br^b.). — Segments in
f. V. elliptic, fm-nished vnth 'mwierous
spines, sotneivhat broad at their base, ex-
ceedingly acute, chiefly confined to the outer
margin ; e. v. vrith three angles ; angles
and sides broadly rounded, bordered all
round by the spines. F.

S. telifm-um (Ralfs). — Segments in f. v.
elliptic or subreniform, ftirnished with a
few scattered, elongate, subulate, acute
spines ; e. v. with tlu-ee broadly roimded
angles, the spines scattered, chiefly con-
fined to the extremities, suiface between
the spines smooth, sides concave. Spo-
rangium orbicular, beset with numerous
elongate linear spines, forked at the apex.
L. 1-597"; B. 1-643". (m. 20, e. v. 21.)
G.B., I., F. ^ ' J

S. Hystrix (Ralfs). — Segments in
f. V. subquadrate, extremities somewhat
roimded, end margin nearly straight, fur-
nished with a few scattered, subulate,
acute spines, chiefly confined to the late-
ral extremities ; e. v. with throe or four
broadly rounded angles, the spines scat-
tered, cliiefiy confined to the extremities,
sides concave. L. 1-1075" to 1-1020" :
B. 1-1165" to 1-954". G.B.

5 * Segments toith numerous short, trun-
cate, emarginate, scattered spines, prin-
cipally co7ftned to the margins; e.v.
angles rounded ; if angles spinous, no
S2)ine in particular conspicuously larger
than the others tenninating the anqles,

S. spongiosum (Br^b.). — Segments in
f.v. scmiorbicular, furnished with scat-
tered short, stotit, forked spines, the
spines at the lower basal angle of each
3n 2

470

SySTEMATrC niSTOllY OF TETE rNFUSORIA.

rather larger than the others ; c.v. with
three somewhat rounded angles, sides
convex, and bordered all round with the
spines. L. 1-50G" to 1-418" ; B. 1-523"
to 1-476". (m. 22, e. v. 23.) = Desmidium
ramosum (Ehr.), Asteroxanthium ramo-
sum (Kg-.), Phycastrum Griffithdanum
(Nag.). G.B., i., R, G., U.S.A.

S. scabrum (Br^b.). — Seg-ments in f.v.
subelliptic or broadly fusiform, very
rough or denticulate at the margin ; e.v.
with three rounded denticulate angles,
sides straight, bordered by minute, short,
truncate emaryinate spines. F.

S. asperum (Br6b.). — Segments in f.v.
broadly elliptic, very rough, with very
minute, short, tnmcate or forked spines
chiefly confined to the outer margin;

e. v. with three rounded angles, sides
straight. Sporangium orbicular, beset
Avitli munerous elongate spines, twice
branched at the apex. L. 1-555": B.
1-615". G.B., I., F.

6 * Segments without spines , e.v. angles
rounded.

t Frond smooth.

S. muticum (Breb.). — Segments in f.v.
elliptic, smooth, without spines ; e.v. with
three or fom* broadly rounded angles, sides
concave. Sporangium beset with nume-
rous elongate somewhat stout spines,
forked at the apex. L. 1-674": B.
1-686". = S. trilobum (Menegh.), Phyc-
astrum muticum (Kg.), P. deprcssum
(Niig.). G.B., I., F., Italy, U.S.A.

S. orbiculare (Ralfs). — Segments in

f. V. semiorbicular, smooth, without
spines ; e. v. with three broadly rounded
angles, sides slightly concave. L.
1-1037"; B. 1-110)6". = Desmidium orbi-
adure (Ehr.), Phycastrum orbiculare
(Kg.), Goniocystis (Trigonocystis) orbi-
cidaris (Hass.). G.B., L, F., G., Italy,
U.S.A.

S. coarctatmn (Br^b.). — Segments ob-
long, lateral extremities rounded, inner
margin convex, outer somewhat concave at
the centre (inversely reuiform), smooth ;
e.v. with three inflated roimded angles,
sides concave. l'.

^.pygmcBum (Brdb.). — Segments in f.v.
cuneiform, outer margin slightly convex,
smooth ; e.v. with three blunt angles,
sides slightly convex. Sporangium orbi-
cular, " beset with protuberances bearing
each two bifurcate spines at their sum-
mits." F., G.

2t Segments having the projecting por-
tions surrounded by annular ti-ansverse

lines (rows of puncta or minute gi-a-
nules f ).

S. striolatum (Niig. gp.). — Segments
in f. V. reniform, divergent, ends concave,
each of the lateral portions crossed by
about Jive ti-ansverse lines (annular rows
of closely set puncta or minute gra-
nules?); e.v. with three rounded angle.«,
sides concave, each of the projections
crossed as before by about five ti-ansverse
lines, the central poi-tiou smooth. L.
1-100". = Phycastrum striolatum (Naff.").
G.

3t Fronds rou^h superficially with scat-
tered granules. (Sometimes S. tri-
corne might be thought almost to come
in here ; but the exti-emities in that
species are more prolonged into di-
stinct processes, usually colomles?,
and mostly divided at the apex. Here,
also, might S. asperum and S. scabrum
seem to fall in ; but they are provided
with very short and truncate spines on
some part of theii" mai'gin.)

S. muricatum (Breb.). — Segments s?/&-
elliptic, the outer mai'gin more turoid
than the inner, rough all over with
scattered conic granules; e.v. with three
angles, both angles and sides broadly
rounded. L. 1-409"; B. '^-4:7 4:". = Des-
midium ujnculosum (Ehr.), Xanthidium '
deltoiderim (Corda), Phycastrum apicnlo- ■
sum (Kg.), P. muricatum (Kg.), Gonio- i
cr/.'itis {Trigonocystis) muricata, jS (Hass.).
G.B., F., G., Italy. ' i

S. ininctulatum (Br6b.). — Segments in .
£v. elJiptic, equal, rough with scattered ■
puncia-like granules ; e.v. with tliree ;
broadly roimdcd angles, sides concave, i .
L. 1-704" ; B. 1-881". G B., I., F.

S. rugxdosum (Brdb.). — Segments in
f.v. broadly elliptic, equal, rough rcith
scattered granides, giving a denticulate
ap2)ea}-ance to the margin, cspcciaUy at
the opposite lateral cxtreniitles ; e.v. with ,>
three broadly rounded denticulate" angles,
sides straight or nearly so. F.

S. pik'olatum (BitSfi.).— Segments in
f.v. quadrate, the basal angles rounded
and rough with minute granules, sidp«
with a 'broad shallow sinus, the upper
margin terminating in three conspicuous,
large, rounded, conical, very slightly di-
vergent projections, whicli are rough with
minute granules ; e.v. with three rounded
angles, sides entire. F.

S. Capitulum (Brdb.).— Segments in
f.v. quadrate, sides with a rounded sinus
at the middle, the basal and upper angle?
cronated, rounded, upper margin .itraiyht \

i

01" THE DESMIDIEiE.

741

e. v. witli three broadly rounded crenated
angles, sides nearly straight, each with a
slight shalloto depression or constriction at
the middk. F.

S. alternans (Brdb.). — Segments in f. v.
elliptic or oblong, two or thi-ee times
as broad as long, separated by a wide
sinus, twisted, unequal ; rough with very
minute pearly granules ; e.v. with three
obtuse and rounded^ angles, forming short
not colom'less rays, alternating with
those of the other segment, sides con-
cave. L. 1-1037" ; B.l-llOG". (n.16,17.)
= Goniocystis (IVigonocgstis) hexaceros
(Hass.), 'S. dispar (Breb.) ? G.B., I.,
F., U.S.A.

S. dilutatum (Ehi'.). — Segments in

f. V. fusiform, their lateral extremities
obtuse, equal, rough with puncta-like
pearly gi-anules; e.v. with four rotun-
dato-trnncate angles, foiming short,
broad, not colomless rays, sides concave.
L. 1-1201"; B.l-l^l". = Phycastrum di-
latatmn (Kg.), Goniocystis (Staurastruni)
dilatata (Hass.). G.B., I., F., G., Italy,
U.S.A. .

S. crenatutn (Bailey). — Segments in
f.v. fan-shaped in outline, separated by a
wide 7-ounded sitius, inner margin concave,
smooth, outer semicircular, crenate ; e.v.
with thi'ee rotundato-ti'micate crenate
angles, sides concave, smooth. U.S.A.

7* Segments with or without spines; in
f. V. with spines (if any) few and scat-
tered ; in e. v. angles emarginate or
bi/id, or truncate and the extremities
plane and quadrangular.

S. bijidam (Ralfs). — Segments in f.v.
. . . . ; in e. V. with three acutely bifid or
emarginate angles, the teeth acute ; sides
concave. = Desmidium bifidum (Ehi'.),
Phycastmm bifidum (Kg.), nec Gonio-
cystis (S.) bifida (Hass.). F., G.

S. quadrangidare (Brt^b.). — Segments
in f.v. subquadrate, with a few short
bifid or tooth-like spines spreading laterally,
othemise smooth ; e.v. with fom- trun-
cate and onarqinate angles; sides concave.
L. 1-1157"; B. 1-1163". (m. 24, e.v. 25.)
ft angles in e.v. broader, with/o«/- teeth
at the extremity, and ttvo minute teeth on
ujrper side (Br4b.). G.B., F.

S.Cerberus (Bailey). — Segments in f.v.
truncato-oblong, smooth; the .opposite
lateral extremities abruptly truncate, ex-
ternally plane and quadrangular, the an-
gles drawn out into ncutG ^nnc-like ex-
tensions or teeth, two prf)jecting upwards
and two downwards ; o.v. witli tliroe
abruptly truncate angles, extremities as

in f.v. plane and quadrangulai', the teeth
at the angles divergent. U.S.A.

8* Segments toithoiit spines; in f.v. and
e.v. the angles terminated by either a
conspicuous rounded nipple-like projec-
tion, or an enlarged rounded knob, or
an elongate capitate p7'ocess.

S. tumidum (Brdb.). — Segments in f.v'
ellijitic, turgid, smooth ; their margin
striated, and their opposite lateral ex-
tremities furnished with a rounded con-
spicuous nipple-like projection ; e.v. with
three or four angles, the nipple-like pro-
jection tenninating the angles, sides
convex ; e. f. pimctate ; gelatinous in-
vestment very evident. L. 1-200" ; B.
1-250". = <S'. orbicidare (INIenegh.), Phyc-
astrum tumidum (Kg.). G.B., I., F.

S. glohdatum (Br6b.). — Segments in
f.v. fusiform, capitate; e.v. with thi'ee
angles, each enlarged into a roimded
granulated knob, sides nearly straight,
(m. 26, e.v. 27.) F.

S. bacillare (Breb.). — Segments in f.v.
somewhat arcuate, eachdivergent from the
opposite segment, somewhat attenuated,
finally capitate, smooth; e.v. with from
three to five capitate rays. =Phycast?-um
bacillare (Kg.). F.

9* Segments in f.v. with the opposite
lateral extremities each tapa'ing into a
single more or less elongate colourless
2}rocess divided at the apex, which in
e. V. terminates the angles, ivith or toith-
out intermediate simple or truncate
spi?ies.

t Segments smooth.
S. brachiatum (Ralfs). — Segments in
f.v. smooth, nai-row below, widening up-
wards, ends truncate, the lateral extre-
mities each produced itito a smooth, elon-
gate, straight, tapering, divergent process,
bifid or trifid at the apex ;' e.v. tri- or
quadriradiato, sides concave. L. 1-1111";
B. 1-1785". = Goniocystis (S.) bifida
^it^s.)^Phycaistruni Ralfsii (Kg. ). G.B.,

2t Segments rough vni]\ superficial
granides, those on the processes ar-
ranged in transverse linos. {S. poly-
morphum has sometimes a few iucou-
spicuous scattered spines.)

S. tricorne (Br^b.). — Segments in f.v.
somewhat fusiform, often twisted, rough
with minute pnncta-lilve granules, taper-
ing at each side into a short usually co-
lourless process, blunt, or divided at the
apex ; e.v. tri- or quadriradiato, processes

742

SYSTEMATIC HISTOKY OP THE INFUBOUIA.

isliort, usually colourless, sides somewliat
concave. Sporangium orbicular, beset
with spines ultimately branched at the
apex. L. 1-1275" to 1-972" ; B. 1-948"
to 1-697". =Desmidium hexaceros (Ehr.).
Phycastrum tricorne (Kg.), P. trilohatiim
;Kg.) ? P. hexaceros (Kg.) ?, P. Balfsii

Nfig.), P. creniilatum (Nag. in part).

>.B., I., F., G., U.S.A.

S. cyrtocerum (Br4b.). — Segments in
f. V. suhcimeate, gi'adually widening up-
wards, truncate at the end margin,
rough with minute granules, the lateral
processes incurved, divided at the apex ;

e. v. triradiate, processes short, cm'ved,
sides slightly concave. L. 1-800" ; B.
1-500". = Phycastrum cyrtocerum (Kg.).
G.B., I., F., U.S.A.

S. injlexum (Breb.). — Segments in f.v.
broadly elliptic, inner and outer margin
turgid, rough with minute gi'amdes,
lateral processes incurved, short, divided
at the apex; e.v. tri- or quadi'iradiate,
processes short, sides concave. F.

S. brachycerum (Br^b.). — Segments in

f. v. ovato-lunate, inner margin turgid,
outer equally rounded, rough all over with
minute gi'anules, and on the outer mar-
gin ver-y rough with minute, acute, short,
almost spine-like granules ; lateral pro-
cesses incurved, divided at the apex ;
e. V. triradiate, processes short, straight,
sides somewhat concave. F.

S. polymorphum (Breb.). — Segments
in f.v. broadly elliptic or almost circular,
rouo;h with minute granules (sometimes
with a few minute scattered spines),
processes short, stout, tipped by three or
four divergent spines; e.v. with three,
four, five, or six angles, each produced
into a short stout process. Sporangium
orbicvdar, beset with elongate spines,
forked or branched at the apex. L.
1-1000" ; B. 1-1157". (n. 20, 21, 24, 25,
&31.) G.B., I., F., U.S.A.

S. gracile (Ralfs). — Segments in f.v.
triangular, ends truncate, rough with
minute gi-anules, tapering at each side
into elongate, straight, slender, horizontal
processes, terminated by three or foiu'
minute spines ; e.v. triradiate, processes
straight, sides concave. L. 1-773" to
1-539" ; B. 1-348" to 1-372". (ra. 28,
e.v. 29.) = Goniocystis (Ti-igonocystisj
gracilis (Hass.), Phycastrum gracile
(Kg.). G.B.,I.,F.

S. paradoxum (Meyen). — Seg-ments
in f.v. gradually tvidcning ujnvards, the
cuds truncaU;, rough vAtii minute gra-
nules, processes straiglit, elongate, slcu-
dov, divergent, ti'ifid at the apex ; e.v.
tri- or quadriradiate, processes straight,

sides straight or very slightly concave.
L. 1-941" ; B. 1-1165". = Phycastrum
paradoxum (Kg.), Goniocystis (S.) para-
doxum (Ilass.). G.B., I., F., G., Italv.
U.S.A. ' y > 3,

3t Segments fiu-nished with variously
disposed spines, which are either sim-
ple, or short and notched at the apex.

^.proboscideum (Br^b.). — Segments in
f.v. broadly cuneiform, ends somewhat
convex, rough unth very minute, sJtort,
truncate spines, chiefly confined to the
outer margin, processes short, thick, trifid
at the apex ; e. v. triradiate ; processes
short, stout, sides concave. L. 1-555" ;
B. 1-500". =-S'. (Ralfe, Br^b.).

G.B., I., F.

S. controversum (BrSb.). — Segments in
£v. elliptic or broadly fusiform, some-
times irregular, fm-nished with scattered,
it-regular, simple or notched spijies ; pro-
cesses short, generally curved, spinulose,
terminated by minute spines ; e. v. tii-
radiate, the processes twisted or curved.
Sporangium orbicular, spinous ; spines
t'svice branched. L. 1-972" ; B. 1-886".
Goniocystis (D'igonocystis ?) aculeatum
(Hass.). G.B., I., F.

S. acideatum (INIenegh.). — Segments
in f.v. broadly fusiform, furnished with
thickly scattm-ed simple or notched spines ;
processes elongate, spimdose, straight, ter-
minated by minute spines; e.v. 3-5-
radiate, the processes straight, sides con-
cave. L. 1-666" ; B. 1-500". = Desmidium
aculeatum (Eh.), Phycastrum aculeatum
(Kg.), Goniocystis {Trigonocgstis) acuka-
tum (Hass.). G.B., I., F, G., Italy.

S. vestitum (Ralfs). — Segments in f.r.
fusiform, outer margin bordered by mimiie
emarginate spines ; processes elongate^
rough, terminated by minute spines;
e.v. trkadiate, the processes elongate
straight, sides concave, furnished at ike
middle toith a pair of conspicuous slender
forked spines, sometimes accompanied by
a few others shorter either simple or
notched. L. 1-625" ; B. 1-384". Cin. 30,

e. V. 31.) G.B., I., F.

S. oxi/acantha (Archer).— Segments m

f. v. broadly fusifortn, rough wdh mitude
gramdes, Airnished on the outer margin
tvith six subulate: acute dqiresscd spines
(fom- of which are apparent in this new);
processes elongate, mcuned, the granides
thereon aiTanged in transverse lines, ter-
minated by three or four minute spines;
0. v. ti-iracliate, the processes elongate
straight, sides somewhat concave, end
furnished at the tnidd/e u-iih a pair of
very slender extremely acute suhdatc

OF THE DESMIDIE.E.

743

spines pro] ectiiig to each side. L. 1-770 ' ;
B. 1-680''' to 1-636". I.

10* Seffwetiis in f.v. with the opposite
lateral extremities ter7ninating in one
or two elongate colourless processes
mostly divided at the apex ; and in e.v.
either tapering into a single process at
each angle, and furnished tcith others
between or above of a similar character
definite in number, or the angles fur-
nished tvith two short processes side by
side and unaccompanied by others.

t Segments at end view with the addi-
tional processes more than one for each
angle, and placed on the margin or
upper sm-face, and diverging laterally.

S. furcatum (Br^b.). — Segments
smooth, in f.v. broadly elliptic, furnished
at each opposite lateral exti'emity with a
colourless bifid process, and with six
others similar and divergent on external
margin (io\ix only of which ai'e usually
visible); e.v. with three acute angles,
each tapering into a terminal process,
and each bearing two others on the upper
surface, placed to each side, and project-
ing laterally. L. 1-860"; B. 1-900".=
Xanthidium furcatum (Ehr.), Astej'o-
xanthium furcatum (Kg.), -d. bisenariutn
(Kg.).? 'G.B.,L,F.

S. senaritim (Ehr.). — Segments
smooth, in e.v. with tkree angles, each
tenniuating in a short process tipped by
minute spines, and having six other short
forked processes on the margins, two at
each side and projecting laterally, and
six others on the uppe^- surface, confluent
at their bases, divergent at their exti'e-
mities, and forked ; sides sti-aight. (rt. 7.)
= Stephanoxanthium senarium (Kg.).
U.S.A.

S. eustephamim (Ehr.). — Segments
granidate, in e.v. with thi-ee angles, each
terminating in a short process tipped by
minute spines, icithuut lateral processes,
but with six others confluent at their
bases on the upper sm'face, divergent and
forked, (n. 3.) =Stephanoxanthiuni euste-
phanum (Kg.). U.S.A.

S. Ehrenbergii (Corda). — " Corpuscles

Ear paire, vus de c6ti5, ovales ; vus d'en
aut, triangulairos, munis de six ap-

Sendices terminaiix et lat<)raux, et de
eux autres appendices centraux, qui
Bont com-ts, blancs, en fom'chette, niais a

Sointes divergeutes " (Corda, ' Obs.
licr. des Animalcules de Cai-lsbad,'
1840). In Corda's figure the f. v. is
somewhat like that of S. furcatum. The
segments are broadly fuslfonn, the pro-

cesses ai'e all very short and stout, and
the bifiu'cations very divergent (fonned
indeed somewhat like the tail of a Jish).
=Xa7ithidium Uhrenbergii (Corda, /. c).

S. artimlatum (Corda). — " Coi-puscles
ovales, par pau-e, munis aux deux bouts
d'un appendice a deux cellules, qui se
divise encore en fonne de fourchette, et
lateralement en deux appendices plus
longs a quati'e cellules, et una pointe en
fom-chette. Sur les deux c6t<5s plats, se
ti'ouvent deux protuberances trans-
versales, egalement pom-vues de deux
allongements cellulaii'es en fourchette "
(Corda, I. c). In Corda's figures the seg-
ments in f.v. are elliptic, the processes
stout, elongate, transversely striated (by
rows of granules?), bifui'cate, the bifui'ca-
tionsreciu'ved. =J5r. articulatum (Corda).
Neither of the figm-es of the foregoing is
explanatory ; both, however, seem to be
distinct species.

2t Segments with the additional pro-
cesses one for each angle, and placed
on the upper surface immediately
above those terminating the angles.

S. fu7-cigerum (Breb.). — Segments in
f. V. twice as broad as long, separated by
a deep constriction, 7'ough with pearly
granules, terminating at each side in two
elongate, stout processes, bifid at the apex,
placed one above the other, the inferior
horizontal, the superior directed ob-
liquely outwards and divergent, both
having the granules thereon in ti-ans-
verse lines ; e. v. with tkree or four
angles, each extremity tei-minating in a
process and having the other immedi-
ately above it on the upper siuface, sides
concave at the centi-e. L. 1-333"; B.
1-357" inch processes, (m. 32, e.v. 33.)
= DidymocladonfurcigerusCRaih'), Astc
roxanthium furcigerum (Kg.), Xanthi-
dium coronatum (Ehr.) ?, A. coronatum
(Kg.)? G.R, I., E., U.S.A.

S. longispinum (Bail. sp.). — Segments
in f. V. triangular, truncate on outer mar-
gin, smooth, tenninating at each side in
two much elongated stout processes, sub-
acute at the apex, placed one above tho
other, divergent ; e. v. with three angles,
each extremity tenuinated by a process
and having the other immediately above
it on the upper surface, side straight. =
Didymocladon longiqnnum (Bailev")
US'. A.

3t Segments with frvvo processes from
each angle placed .side by side.
S. tare (Ralfs). — Segmonta in f. v. ex-
ternally lunate or somewhat cwicate, with

744

SYSTEMATIC niSTOIlY OF THE INFUSOEIA.

the ends somewhat protuberant, smooth,
terminatmg at each side in a pair of
short stout processes placed side by side
(one onlyof which, however,is apparent),
dii-ected upwards and divergent, forked
at the apex ; e. v. with three or four
angles, each terminated hy the pair of
short processes separated by a rounded
sinus, sides deeply concave." L. 1-1220" ;
B. 1-2127". G.B., F.

11 * Segments in f. v. with each opposite
lateral extremity ter minating in a colour-
less process, cither short, rounded, and
dentate, or elongate and entire at the
end; e.v. circular, margined loith from
Jive to seve7i processes, or compressed,
and loith hut two processes. (S. poly-
morphum sometimes has five rays, and
the e. V. a^jpears almost circular, but the
extremities o f the processes are not entire
hut tipped with minute spines.)

t End view circular.

S. sexcostatum (Br^b.). — Segments in
f. V. suborbicular, furnished on each side
with a short, broad, truncate, dentate pro-
cess, and with slight crenate elevations
on the outer margin ; e. v. circtdar, bor-
dm-ed by Jive or six short, rounded, den-
tate, colourless m.arginal rays. L. 1-661" ;
B. 1-833" to 1-694". = Goniocystis (Pen-
tasterias) Jenneri (Hass.), Stephanoxan-
thium sexcostatum (Kg.). G.B., 1., F.

S. margaritaceum (Menegh). — Seg-
ments in £ V. gradually widening up-
wards, rough vdth pearly gi'anides, outer
margin convex, produced at each side
into a colourless, more or less attenuate
shm't process, having the granules in
transverse lines, blunt and entire at the

apex ; o. v. circular, bordered by from
five to seven short, narrow, obtuse, co-
lourless, granulate marginal rays. L
1-1176"; B. 1-1000" incl. processes',
(m. 34, e.v. 35.) = Pentasterias marga-
ritacea(Ehv.),Phycastrum margaritaceum
(Kg.), Goniocystis (Pent.) margaritacea
(Hass.), Phycastrum rotundatum CKs.').
G.B., I., F., G., U.S.A.

S. Arachne (Ralfs). — Segments in f. v.
suborbicular, rough with minute gra-
nules, lower margin turgid, outer convex,
tapei-ing at each side into an elongate,
slender, incurved process having the gi"a-
nules thereon in ti-ansverse lines, etitire
at the apex ; e. v. cu-culai", bordered by
five slender, linear, colourless margimd
rays. L. 1-1020"; B. 1-652" incl. pro-
cesses. = Goniocystis (Pentasterias) arach-
nis (Hass.), Phycastmm Ai-achne (Kg.),
P. radiattim (Kg.) ?. G.B., F.

2 1 End view compressed.

S. tetracerum (Ealfe). — Segments in
f. V. gradually widening upwards, rough
with minute gi-anules, outer margin
tiimcate or concave, tapering at each
lateral extremity into an elongated, very
slender, colourless process, having the
granules thereon m transverse lines,
entire at the apex and divergent ; e. v.
much com2)ressed, tcith a process at each
extremity. L. 1-2703"; B. 1-1785". =
S. paradoxum (Ehr.), Goniocystis (S. ?)
paradoxnm (Hass.), Phycastrum para-
doxum (Kg.). G.B., I., F., G., U.S.A.

[S. enorme (Ralfe) is omitted, this
plant having been, as we think, shown
by De Baiy (op. cit.) to be a Poly-
edrium.]

2, Fronds distinctly, faintly, or not at all constricted at the middle, very
rarely less than three times, mostly many tiAes longer than broad.
Sporangia smooth, and either spherical, elliptic, quadrate, or cmcifonn.

Genus TKIPLOCERAS (Bailey). — Frond very elongate, straight, coustricied
at the middle; segments with mimeroiis whorls of knot-like projections, ends
three-lobed, lobes hidentate. Endochrome with a tenninal roimded clear space,
in which are active granules.

Triplocebas verticillatum (Bailey).
— Frond stout, sutiu-e prominent, seg-
ments about eight or ten times longer
than broad, with numerous whorls of
prominent, broad, truncate, emarginafe
projections, (iii. 37.) = Bocidium verti-
cillatum (Ralfs). U.S.A.

T. gracile (Bailey^. — Frond rather
slender, sutm'e prominent, segments tea
or twelve times longer than broad, with
niunerous wliorls of prominent, some-
what triangular, roundly blunt projec-
tions. = Bocidium vcrticiUatum (Ralfe).
U.S.A.

Genus DOCIDIUM (Brcb.). — Frond very elongate, straight, constricted at
the middle ; segments with an inflation at the base (very rarely not so), often

OF THK DESMIDIEJi.

745

with others above, or with whorls of knot-like projections, ends abruptly
truncate. Endochrome with a terminal rounded clear space at each end, in
which are active granules.

DociBiuM vcrrucosum (Bailey). —
Frond rather stout, sutiu-e forming a
rim; segments five or six times longer
than broad, with nmnm-ous small equal
undulations due to so many whorls of
small tubercle-like prominences; ends
entire. U.S.A.

D. nodosum (Bailey), — Frond stotit,
sutiue forming a rim ; segments three or
fom- times as long as broad, with fotcr
proininent injlated nodes, including the
basal, which is somewhat the largest,
and which are due to so many whorls of
knot-like prominences or large tubercles;
ends entire; e. v. crenate. U.S.A.

D. coronatum (Breb.). — Frond stout,
sutme forming a thickened projecting
rim ; segments four to six times as long
as broad, tapenng, regularly inflated up-
wards fi'om the base, so as to produce
an undulated margin, the basal inflation
the most prominent, the others less so,
and wanting towards the ends ; ends
bordered hy prominent tubmxles, projecting
all round ; e. v. circular, bordered by the
tubercles ; e. f. coarsely punctate. F.

D. undulatum (Bailey). — Frond slender,
suture foiming a minute lim, segments
eight to ten times as long as broad,
tcith six or eight sinuations at regular in-
tervals, produciag as many inflations
besides the basal, which is not larger
than the others ; ends and bases cre7iate.
U.S.A.

D. EIirenbe^-gii(R^s). — Frond slender,
linear; sutiu-e foiTning a very shai-ply-
defined rim; segments eight to twelve
times longer than broad, basal injlation
having another smaller one above it, sides
otherwise sti-aight, jjara^fc/; ends a'etiate,
owing to a number of emarginations
from the edge of the tinmcate extremi-
ties, from three to five of the crena-
tiu-es being usually visible ; e. f. punc-
tate, or rough with minute gi-anules.
Sporangium suborbicidar or elliptic, or
slightly angular, smootli, placed between
the deciduous empty fronds. Ciliated
zoospores fonned by segmentation of the
cell-contents, and their emission eftected
through the opened apex of each of one,
two, or three specially-formed lateral
tubes arising from beneath the base of
one of the segments (vide si/prtl, p. 710 ;
HI. 46, 47). L.1-71" to 1-59"; B. 1-1111"
to l-OGl". (II. 8 & U.)=Pl^urotcemum
Ehrenhcrghii (Dc Barv). G.B., I., R, O.,
U.S.A. > > y >

D. clavatuvi (Kg.). — Frond slender,
sutm-e scarcely prominent, segments
eight or ten times as long as broad,
slightly clavate near the ends, and ulti-
mately someivhat attenuated, basal infla-
tion sometimes solitary, sometimes hav-
ing another slight one above it; ends
entire; e. f. punctate. L. 1-65" ; B. 1-813".
(ii. 9.) = Pleurotamium clavatum (De
Bary). G.B., I., F., G.. U.S.A.

D. nodidosum (Breb.). — Frond vm-y
stout, the thickened sutiu-e fonuing a
projecting rim ; segments foiu- to six
times as long as broad, scarcely atte-
nuated, regularly injlated at intervals so
as to produce an imdulated margin, the
basal inflation the most prominent, the
others as they approach the ends less so,
where they are indistinct or wanting ;
ends etitire ; e. f. coarsely punctate. L.
1-50"; B. 1-428". =Z). crenulatum (Ehr.),
Pleurotcenium nodidosum (De Barv).
G.B., I., F., G., U.S.A.

D. truncatum (Breb.). — Frond stout,
the thickened sutui-e forming a rim ; seg-
ments three or four times longer than
broad, tapering, basal inflation solitary,
sides otherwise gradually airved ; ends en-
tire ; e. f. ^mictsitQ.= Pleurotcenium trun-
catum (Niig., De B.). L. 1-81" to 1-72" ;
B. 1-527" to 1-429". G.B., I., F., G.

D. constrictum (Bailey). — Frond stout,
suture not prominent ; segments five or
six times longer than broad, not at-
tenuated, with four distinct equidistant
sinuations producing fom' equal gently
curving prominences besides the basal
inflation; ends entire. U.S.A.

D. Bacidiim (Brt^b.). —Frond slender,
suture not prominent; seo-ments very
inany times longer than broad, basal
inflation vei-y conspicuous, solitary, sides
othm-wise straight, veiy nearly parallel,
large granules of the endochrome in a
single series ; ends entire ; o. f. 'natliout
puncta. L. 1-111" ; B. 1-1937". (ui. 38.)
= Pletirotamium Bactdum (De Barv")
G.B., F., G., U.S.A.

D. minutum (Ralfs). — Fi-ond slender,
suture not prominent ; segments four to
six times longer than broad, somewhat
tapering, injlation obsolete, sides straight,
ends entire ; e. f. without punctn. ' L
1-212"; B. 1-1582". = Pemum Rdfsi'i
(DeBary). G.B., I., F., G., U.S.A.

D. hirsutum (Bailey). — Frond ratlier
slender, suture not prominent, segments
four to six times ns long ns broad,

746

SYSTEMATIC HISTOET OF THE INFtrsOllIA.

not tapering, tti/lation obsolete, ends en-
tire, surface all over minutely spi^ious, or
hirsute. U.S.A.

Kiitzing (Sp. Alg.) describes one or

two other species of Docidium; but the
characters given seem hardly distinctive,
and appear sometimes more lilte generic
characters re-stated.

Genus TETMEMOEUS (Ealfe).— Frond elongate, straight, cjUndrical or
fusiform, constricted at the middle ; segments more or less tapering, not in-
flated at the base, ends with an acute incision, the subdivisions rounded,
otherwise qiiite entire.

Tetmemobus Brebissonii (Ralfs). —
Frond about five or six times longer
than broad ; iti f, v. with parallel sides,
the constriction a very shallow groove ;
in s. V. fusiform, the constriction very
slightly deeper ; endochrome with a lon-
gitudinal series of light-coloured large
granules ; e. f. punctate, the puncta in
hngitudinal rows. L. 1-142" ; B. 1-704';.
(ii. 12 & 13.) = Closterium Brebissonii
(Menegh.), Penium monile (Kg-), P- stri-
ato-punctatum (Kg.) ? G.B., I., F., G.,
Italy, U.S.A. ^, turgidus, larger, stouter,

constriction deeper, y, (De Bary),

smaller than either, otherwise externally
similar, endochrome in longitudinal
fillets.

T. Icevis (Ealfs). — Frond smaller than
last, scarcely one-half its length, about
three or fom* times as long as broad;
in f. V. somewhat tapering, the constiic-
tion a shallow depression j in s. v. fusi-
form; end sometimes vrith a hyaline
lip-like projection extending beyond the
notch ; e. f. punctate, puncta faint but
evident, scattered. Sporangium smooth,
in f. V. at first quadi'ate, afterwards

broadly elliptic ; in s. v. compressed,
enclosed in a central cell placed between
the ultimately deciduous empty fronds.
L. 1-374" to 1-336"; B. 1-1244" to
1-1073". = Penium (Tetmcmorus) Bre-
bissonii (Kg.). G.B., I, F., G.

T. minutus (De Bai-y). — Frond minute,
shorter than T. Icevis, about thi-ee times
longer than broad, fusiform, the con-
striction a very shallow groove ; e. f.
without puncta. L. 1-41"'; B. 1-118"'. G.

T. granulatus (Ralfs). — Fi'ond some-
what longer than T. Brebissonii, about
five or six times longer than broad ; in
both f. V. atid s. v. fusiform, the constric-
tion a very shallow gi'oove, ends tcith a
hyaline lip-like projectioti extending be-
yond the notch ; endochrome with a
longitudinal series of lai-ge granules;
e. f. punctate, the puncta scattered, ex-
cept near the constriction, where they
are disposed in two transverse rows.
Sporangium orbicular, smooth, mai^in
finely striated, placed between the de-
ciduous empty fronds. L. 1-130"; B.
1-649". =Pe«mwi (T.) qranidatus (Kg.).
G.B., I., F., G., Italy, U.S.A.

Genus CLOSTEEIUM (Nitzsch). — Frond elongate, attenuate, more or less
Innately curved or arcuate, entire, not constricted at the middle, the junction
of the segments marked by a pale transverse band. Endochrome often
arranged in longitudinal fillets, and at each extremity having a terminal clear
space, in -which are active granules ; e. f. smooth, or with longitudinal strias,
never granulate.

The subdivisions of this genus cannot always be rigidly adhered to, as
certain species might sometimes seem to agree almost as well with anotlier
division as with that in which they are placed.

* Frond scarcely tapering, the curvature
very slight, gradual and equal; loioer
margin nearly straight or slightly con-
cave; ends truncate or broadly rounded;
e.f. tcith or without longitudinal strice.

Closterium didymotocum (Corda). —
Frond stout, six to ten times lono^er than
broad, nearly straight, very slightly tapcr-
inr/ to the extremities, upper margin
slightly convex, lower nearly straight or
very slightly concave, sometimes slightly

inclined upwards at the end ; ettds trun-
cate, reddish ; large granides in a single
series ; e. f. reddish, especially near the
ends, stri(e faint ; central suture evident,
sometimes accomp.anied by tvvo others
dividmg the fi-ond into four portions.
L. 1-65"; B. 1-813". (ui. 39.) G.B., I.,
F., G. a, three transverse sutm-es; ft
one. = C. subrectum (Kg.), C. Bailcyanum
(Brt5b.).

C. obtusum (13rdb.). —Frond minute,
four to ton times as long as brond,

OF THE DESMrDIEiB.

747

nearly sti-aiglit, cylindrical, not tapering,
upper and lower margin equally and but
very slightly curved, ends obtusely rounded ;
lai-ge gi-aniiles, in a single series ; e. f.
smooth. F.

C. Amblyonema (Ehr.). — Frond stout,
very long, twenty to twenty-five times
as long as broad, slightly curved, scarcely
tapering, upper and lower margins equally
and but gently cm-ved ; ends broadly
rounded; e. f. smooth. U.S.A.

2 * Frond tapering, having the curvature
slight ; hioer margin straight or very
slightly concave, and slightly inclined
upwards towards the rounded or sub-
acute ends; e.f. with or witJwut lon-
gitudinal stria.

C. Lumda (Ehr.). — Fi'ond large, stout,
five or six times as long as broad, semj-
lunate, upper margin very convex, lower
ttearly straight, somewhat inclined ttpwards
towards the obtuse broadly rounded ends ;
endochrome with the large granules
numerous, scattered, fillets several, di-
stinct ; e. f. colourless, without mark-
ings, central suture not evident. L.
1-62"; B. 1-330". = Vibrio Lumda
(Miiller), Hacillaria Lunula (Schi-ank),
Lunidijia mdgaris (Bory). G.B., F., I.,
G., Italy, U.'SA., Mexico.

C. acerosum (Ehr.). — Frond slender,
six to fifteen times as long as broad,
linear-lanceolate, gi'adually tapering,
upper margin slightly convex, the lower
nearly straight, slightly inclined upwards
at the conical ends ; large gi'anules in a
single central longitudinal series ; fillets
several, distinct ; e. f. colomiess, very
faintly striated, central sutiu'e evident.
L. 1-70" to 1-58" ; B. 1-1103" to 1-510".
Sporangium orbicidar, smooth, placed
between the dehiscing deciduous empty
fronds. = Vibrio acei-osus (Schi'ank).
G.B., I., F., G., U.S.A., Mexico.

C. lanceolatum (Kg.). — Frond stouter
than C. acerosum, six to ten times longer
than broad, semilanccolate, gradually ta-
pering ; upper margin convex, lower
nearly straight, inclined upwards to-
wards thp tapering subacute ends ; large
gi-anules in a single centi-al series ; fillets
several, distinct ; e. f. colourless, usually
without marlrings, sometimes faintly
striated, central suture evident. L.
1-64"; B. 1-453". = Cymbella HopkirM,
(Moore). G.B., I., R, G., U.S.A.
_ C. turgidian (Ehr.). — Frond stout,
eight to twelve times as long as broad,
semtlanceokite, slightly tapering, more
curved than either of the preceding,

upper mai'gin convex, tvith a depression
near each extremity, lower margin con-
cave, inclined upwards towards the
rounded ends ; large gi-anules, in a single
longitudinal series ; fillets several ; e. f.
reddish, longitudinal strice close, distinct,
central sutm-e evident. L. 1-39" ; B.
1-370". (m. 40.) = C. decussatum (Kg.) ?
G.B., I., F., G., U.S.A.

G. prcelongum (Br6b.). — Frond very
slender, extoemely long, thirty-five to
forty times as long aa broad, slightly
cm-ved, ve7-y gradually tapering; upper
margin slightly convex, with a depres-
sion near each extremity ; lower concave,
inclined upwards towards the rounded
ends ; large gi-anules in a single series ;
e. £ colourless, loithout markings. F.

C. quadrangulare (Corda). — Frond
very slender, twenty-five to thii-ty times
aa long as broad, slightly curved, gra-
dually tapering, quadrangular, except at
the extremities, one of the angles forming
a prominent longitudinal median line ;
upper margin equally convex, lower con-
cave, very slightly inclined upwards at the
blimt ends ; e. f. colourless, smooth. G.

3 * Frond tapering, the loicer margin
co7icave, often with a central inftation,
and inclined downwards towards tlie
rounded or subacute ends; e.f. without
markings.

t Frond slender, curvature very slight.

C. strigosum (Br^b.). — Frond slender,
twelve or fifteen times as long as broad,
nearly straight, but someiohat curved down-
wards towards the attenuated extremities :
upper margin slightly convex, lower
concave with a gentle central inflation;
ends acute; lar^e OTanules in a sino-le
series ; e. f. colom-less, without strfa3.
Sporangium orbicular, smooth, placed
between the shortly deciduous empty
fronds, which conjugate soon after divi-
sion, so that two of the empty segments
are considerably shorter than the other
two. F.

C. macilenttim (Br^b.). — Frond very
slender, sublinear, twenty-five or thirty
times as long as broa^, slightly and
very gi-adually ciu-ved, somewhat taper-
ing ; upper margin slightly convex, lower
slightly concave; ends somewhat hlimt-
largo granules, in a single series ; e. I
colourless, witliout strias. Spornngiiini
orbicular, placed between the for some
time persistent empty frond.s, wliicli
conjugate, as in last, soon after divi-
sion. F.

748

SYSTEMATIC HISTOliY OP THE INFUSORIA.

0. graeilo (Brdb.). — Frond very
slender, about twenty-five to thirty
times as long as broad, linear, nearly
sti'aight, except at the exti-emities, which
are curved dotvnwarch; sides parallel,
ends obtuse; endochrome arranged in a
zigzag or mbspiral mamier ; e. f. toithout
stri<B. I., F. This species resembles C.
juncidum, a, in form, but differs in the
arrangement of the endochrome and in
the absence of striae.

2 1 Frond crescent-shaped, curvatm-e
considerable.

C. EJirenhergii (Menegh.). — Frond
large, stout, about five or six times as long
as broad, lunately cui-ved, extremities
tapemig; upper margin very convex,
lower concave icith a conspicuous central
iti/lation ; ends broadly roimded ; large
gi-anules, numerous, scattered; fillets se-
veral ; e. f. coloiu'less, without striae,
central sutiu-e not evident. Sporangia
orbicxilar, smooth, placed between the
but slightly connected empty conjugated
fronds, the endochi'ome dming the pro-
cess of conjugation emerging fi-om the
opened apex of a short conical extension
from eacli imder side of each younger
segment (or shorter cone) of each pair of
recently divided fronds, the conjugating
fronds being produced immediately pre-
viously by the self-division of a pair of
old fr'onds — two sporangia being thus the
idtimate produce of the two original
fronds. L. 1-68" ; B. 1-400". (xvi. 10,
11, 12, 13, 14.) = Lunulina monilifera
(Bory), C. Lunula (Ehr., Hass.). (j.B.;
I., F., G., U.S.A.

C. moniliferum (Ehr.). — Frond smaller
than the last, stout, live or six times
as long as broad, Imiately cm-ved, exti-e-
mities tapering, upper margin convex,
lower concave with a central in^ation,
ends roimded; large grunuleSjCOJisjncuous,
in a single longitudinal series ; e. f. colour-
less, without atvise, suture not evident.
L. 1-75" to 1-60" ; B. 1-510" to 1-466".
G.B., I., F., G., Italy, U.S.A.

C. ohtusangtdum (Corda). — Frond
stout, crescent-shaped, four or five times
as long as broad, rapidly attenuated,
"quadrangular" (six angles P) ; upper
margin very convex, lower concave toith-
out a central inilation ; ends narrowly
rounded ; e. f. coloiuless, without mai'k-
ings.

C. Jtnneri (Ralfs). — Frond small, di-
stance between the extremities six or
seven times the breadth, crescent-shaped,
much cm-ved, gradually tapering (some-

times with an obscure central constric-
tion) ; upper margin very convex, lower
very concave without a central inflation ;
ends obtuse, rounded ; large gi-anules, in
a single series ; e. f. colourless, Avithout
striae. L. 1-281"; B. 1-1730". G.B., I.,
F., U.S.A. _

C. Leibleinii (Kg.). — Frond somewhat
stout, distance between the extremities
six or eight times the breadth, crescent-
shaped, much cmred, rapidly attenuated;
upper margin very convex, lower very
concave, oftmi with a slight central infla-
tion ; ends subacute ; large granide.s, in a
single series ; fillets few or indistinct ;
e. f. somewhat sti'aw-colom-ed, without
striae ; suture evident. Sporangium orbi-
cidai-. L. 1-291" to 1-165" ; B. 1-1632"
to 1-582". (II. 1 & 5.) G.B., I., F., G.,
Italy, U.S.A. j3 more slender, scarcely
inflated on the lower margin.

0. Diance (Ehr.). — Frond slender,
crescent-sbaped,six or eight times as long
as broad, much cmwed, rapidly attenu-
ated ; upper margin very convex, lower
very concave without a central iiiflation ;
e7ids subacute loith a very slight emargi-
nation at the upper outer extremity ; large
granides, in a single series ; e. f. some-
what sti'aw-colom-ed or faintly reddish,
without striae, sutm-e evident. L. 1-143" ;
B. 1-1275". = C. ruficeiK (Ehr.), C. arcu-
atum (Breb.) ?, C. Venus (Kg.) ?, C. acu-
minatutn (Kg.) ?. G.B., I., F., G., Italv,
U.S.A.

C. incurvum (Breb.). — Frond minute,
somewhat stout, crescent-shaped, very
much cm-ved, rapidly attenuated, ends
very acute ; e. f. without stiiae. F.

4* Fronds gradually tapering, curvature
often gradual, lower margin concave,
inclined doicnwards at the rotumlato-
trnncate or sometimes subacute ends;
e.f. striated.

C. ina;quale (Ehr.). — Frond minute,
semiluuate, attenuated; upper manrin
very convex, lower concave; extrcmifii.'i
unequal, conic, i-ery acute ; large granides,
scattered ; e. f. prominently striated. G.

0. costainm (Corda). — Frond stout,
about five or six times as long as broad,
hmatoly curved, attenuated ; upper mar-
gin convex, equally arched, lower con-
cave; emh obtuse, rounded; large gi-aiiules,
iu a single series ; e. f. reddish, stria' fito
(about six), conspiaious ; suture evident
Sporaiigium orbicular, smooth, placed
between the deciduous empty fronds.
L. 1-75"; B. 1-384". = C. iurgidulum
(Kg.). G.B., I., F., G.

li

OF THE DESMIDIEJE.

749

C. striolatum (Elir.).— Frond from six
to ten times as long as broad, limately
curved, attenuated ; upper margin con-
vex, sliffhth/ depressed at the centre, lower
concave; ends I'eri/ obtuse, roimded;
lai'ge granules, in a single series ; e. f.
reddish, especially near the ends, striea
very numerous, crowded, transverse su-
tures tcsuaUi/ three. Sporangiimi orbi-
cular, smooth, placed between the de-
hiscing deciduous empty fronds. L. 1-80"
to 1-68" ; B. 1-625" to 1-535". (n. 2 & 6.)
= a regulare (Breb.) ?. G.B., I., F., G.,
Italy, U.S.A.

C. intermedinm (Ralfs). — Frond slen-
der, twelve to fifteen times as long as
broad, slightly ciu-ved, very gently taper-
ing; upper margin convex, gradually
arched, lower slightly concave ; ends ob-
tuse, roimded ; large granules, in a single
series; e. f. pale sti-aw- coloured, strife
distinct, numerous, but not a'owded; ti-ans-
verse sutures usually more than three.
L. l-77"-l-54" ; B. 1-1073". G.B., I., F.

C. angustatum (Kg.). — Frond slender,
ten to twenty times as long as broad,
sublinear, slightly cm'ved, scarcely atte-
7iuated; upper margin convex, gradually
arched, lower concave; ends truncate,
slightly rotmded ; large granules, in a
single series ; e. f. pale reddish, especially
near the ends, striae few (about four), very
distinct, transvei'se sutures usually three.
L. 1-60" ; B. 1-1142". G.B., I., F., G.

Cjuncidum (Ralfs). — Frond very slen-
der, from about fifteen to even thirty-
five times as long as broad, linear,
straight except toioards the extremities,
which arc somewhat curved downwards,
ends obtuse ; e. f. nearly colourless, strim
not numerous, faint, transverse sutures
usually three. Sporangium orbicular,
smooth, placed between the dehiscing
deciduoiis empty fronds. G.B., I., F.
^, fi'ond stouter, less elongated.

C. uncinatum (Kg.). — Frond slender,
tapering to a subacute point, suddenly
curved dotomvards; e. f., the body with
sti-ice fine and close, absent at the extre-
mities.

C. lineatum (Ehr.). — Frond slender,
elongate, from about eighteen or twenty
to twenty-five times as long as broad,
gen% cm-ved, very gradually attenuated ;
xipper margin unequally con-vex, being
most curved near the ends, lower concave
or somewhat protuberant at the centre ;
sides sommchat parallel for a j^iortion of
their length ; the extremities gradually ta-
pering, shinier, curved dowmwards, ends
obtuse ; large granules, in a single series ;
e. f. reddish, strice numerous, distinct, one

or more transverse lines at the central su-
ture. Sporangia double, rounded, smooth,
in close approximation, their opposed sur-
faces fiatteuod, placed between the de-
hiscing, shortly-deciduous empty fronds,
and each foi-med by the mutual conjuga-
tion of the contents of the adjacent op-
posite segments. L. 1-48"; B. 1-909".
(ra. 41, 42.) G.B., I., F., G., Mexico.
/3, stria3 spiral ; y, stria3 very faint, except
at the centre of the fi-ond (Breb.).

0. decorum (BriSb.). — Frond about
twelve to twenty times as long as broad,
taperiiig from the centre, gradually cui'ved;
upper margin equally convex, lower
margin concave; extremities attenuated,
slender, obtuse ; large granules, in a single
series ; e. f. colourless, striae numerous. F.

5 * Frond gradually curved, tapering, sud-
denly contracted at the end into a coni-
cal point.

0. attenuatum (Ehr.). — Frond eight to
twelve times as long as broad, gently
ciu'ved, gradually attenuated; upper mar-
gin slightly convex, lower concave ; ex-
tremities suddenly contracted into an obtuse
conical point ; large granules, in a single
series ; e. f. reddish, with numerous close
strias, central sutm-e evident. L. 1-67";
B. 1-669". (ni. 43.) G.B., I., F., G.

6 * Frond ventricose or narrow-lanceolate,
rapidly tapering into a distinct beak.
{SiW}-a}igia cruciform.)

C. Ealfsii (Br(5b.). — Frond stout, six
to nine times as long as broad ; the tipper
7nargin slightly convex, the loiver concave,
but ventricose at themiddle\ each exta-emity
tapering into a narrow, slender, reddish
beak, shorter than the body, slightly cun-cd
downwards, ends obtuse ; large granules,
conspicuous, ia a single series ; e. f. red-
dish, especially near the ends, strire nu-
merous, close, and distinct, central suture
accomimnied by several transverse lines
L. 1-79" ; B. 1-526". G.B., F.

C. rostratum (Ehr.). — Frond fi-om
about ten to fifteen times as long as
broad, lanceolate ; U2)per and lower margins
nearly cqiiaUy convex; each cxtroniit-J-
taperiiig into a narrow, setaceous, nenrl'y
colourless boalc, nearly equal in length to
the body, cm-ved downwards, ends ottiise-
large gmnules, in a single series; e. f!
colourless or somewhat straw-coloured"
striffl numerous, close; suture solttart/.
Sporangium somewhat cmcifonn, iW
sides concave, its extensions trun'cate'^
attached to tlio empty conjugated fronds*
(III. 44.) L. 1-69'^;' B.l 1680'. C.cau-

750

SYSTEMATIC mSTOBT OF THE nTFUSOIllA.

datum (Corda), Staurocei'as Acus (Kg.).
G.B., L, R, G., Italy.

C. elegans (Br(5b.). — Frond very slen-
der (twenty-live to thirty times as long
as broad), narrow-lanceolate, upper and
lower margins nearly equally convex,
each extremity tapering into a long, slen-
der, setaceous, colom-less beak, about as
long as the body, ultimately curved down-
wards, ends acute; lai'ge granules, in a
single series ; e. f. without strice. F.

C. setaceum (Ehr.). — Fi'oud very slen-
der, from about twenty to twenty-five
times as long as broad, narrow-lanceo-
late; upper and loiver margins nearly
equally and but slightly convex ; each ex-
tremity tapering into a very long, slen-
der, setaceous, colourless beak, longer
than the body, ultimately curved down-
wards, ends obtuse ; e. f. coloiu'less, strice
close, faint, central sutiu'e solitary. Spo-
rangium cruciform, similar to the last. L.
1-116"; B. 1-2381". = Stauroceras subu-
latum (KgO> ^- intermedium (Kg.), C.
Kiitzingii (Breb.). G.B., I., F., G., Italy,
U.S.A.

C. pronum (Br6b.). — Frond very slen-
der (thirty to thu-ty-five times as long-
as broad), nearly sti'aight ; upper and
lower margin scarcely injlated, nearly
equally though very slightly convex ; very
gradually attenuated at each extremity
into a long, slender, setaceous, coloiuless
beak, ultimately somewhat cm-ved down-
veards, ends slightly enlarged and rounded;
e. f. colourless, without strice. F.

7* Frond minute, tapering, curvature
very slight, neither inflated nor rostrate.
(^Sporangia cruciform.')

C. Comw (Ehr.). — Frond minute, from

five to eight times as long as broad,
slender, slightly cm-vcd, attenuated, ends
blunt; endochrome not reaching to the
extremities ; large granules, indistinct, in
a single series ; e. f. colourless, without
sti'iiB. Sporangium in f. v. somewhat
crucifonn or quadrate, with the angles
produced and rounded, in s. v. elliptic,
attached to the conjugating fronds. L.
1-140" ; B. 1-3709". = C. tenue (Kg.).
G.B., F., I , G., Italy. /3, frond more tur-
gid. L. 1-226" ; B. 1-2142". G.B., I., F.

C. acutum (Br^b.), — Frond somewhat
larger than the last, about fi-om six to
twenty times as long as broad, slender,
narrow-lanceolate, slightly cm-ved, gra-
dually attenuated, ends acute ; e. f. co-
lomless, without striae. Sporangium
similar to last. L. 1-177" ; B. 1-2550".
G.B., I., F., G. a six to twelve times
as long as broad, ends subacute. ^ ten
to twenty times as long as broad, ends
very acute. = Stauroceras subulutum
(Kg.)?, C. subulatum (Br6b.) ?, C. te/ier-
rimum, (Kg.) ?

C. Grrijffithii (Bevk.). — Frond minute,
scat'cely curved, acicular, very acute,
smooth. = a subtile (Br6b.) ? G.B., I., F.

8 * Frond crescent-shaped, stout, extre-
tnities furnished with a single acute
spine.

C. cuspidatum (Bailey). — Frond stout,
crescent-shaped, scarcely tapeiing, much
curved, ends rounded, furnished with a
single subtdate acute spine ; e. f. without
striae. U.S.A. We are disposed to think
this plant may not be a tine Desmidieau,
but belong to the genus Ophiocytium
(Nag.), though placed in Closteriimi by
Bailey.

Genus PENIUM (Breb.). — Frond elongate, straight, cylindrical, elliptic,
or lanceolate, either not at all constricted or but very slightly narrowed at th
middle, entire. Endochrome with or -wdthout a terminal clear space, con-
taining active granules.

* Empty frond granulate, genei'ally
reddish.

Penitjm margaritacetim (Br^b.). —
Frond six to ten times as long as broad,
fusiform or cylindrical, with rotundato-
tnuicato ends, rough with pearly gi-anules
arranged in longitudinal lijies. Endo-
chrome at each end, sometimes with a
more or less distinct tenninal cavity mth
active granules. Sporangium orbicular,
smooth. = Clostcrium marqaritaccum
(Ehr.). G.B., I., F.,G. a, frond fusifonn,
gradually constricted at tlio middle,

granules distinct. L. 1-156" ; B. 1-961".
(n. 14.) /3, frond linear, scarcely con-
tracted at the middle, granules distinct.
y, frond linear, not contracted at the
middle, gramdes appearing like puncta,
L. 1-169" ; B. 1-1515". (n. 15.)

P. Cylindrus (BriSb.).— Frond minute,
red, three or four times as long as
broad, cylindrical, not contracted at the
.middle, ends rotundato-truncate, rough
•\vith minute, closely scattered, pearlv
granules; e. f. red. L. 1-492"; B. 1760 .
= aosterium Cyl{ndrus(Ehr.), Dysphvic-
tium Cylimlrits(Nii^.). G.B., I., F-,

OP THE DESMIDIEiE.

751

P. anmtlatum (Nag. sp.).— Fi-ond mi-
nute, scarcely twice as lo7ig as broad,
ajlindrical or suhelliidic, sides and ends
broadly rounded, rough with minute gra-
nules arranged in transverse lines, which
give a minutely denticulate appearance
to the mai'gin, except at a vei-y naiTOW
central annular space, where they are
absent, thus imparting a somewhat con-
stricted appeai'ance ; e.v. circular, margin
minutely gi'anulate. = Dys])hinctiuin an-
nulatum (Nag.). I., G.

2* Empty frond smooth, colourless.

P. Digitus (Breb.). — Frond large, stout,
smooth, three or four times as long as
bfoad, elliptic - oblong, sides and ends
broadly rounded ; endocliroine in obscure
and undulated fillets, interrtipted only by
the pale central transverse band, and hav-
ing no clear space at the extremities.
L. 1-81"; B. 1-299". = Clostmium Digitus
(Ehr.), Penium oblongum (De Bary)?
G.B., I., F., G., U.S.A.

P. lamellosu7n (Breb.). — Frond large,
stout, smooth, about four times as long
as broad, gradually contracted at the
middle, and tapering to the extremities,
ends somewhat truncate ; endochrome in
obscure and undidated fillets, in transverse
view radiate, its i-ays divided, and hav-
ing no clear space at the extremities.
R, G.

P. Nagelii (Breb. in litt.). — Frond
large, stout, smooth, about four times
longer than broad, oblong, not contracted
at Hie middle, gradually tapering to each
extremity, sides nearly straight, ends
broadly truncate; endochrome aiTanged
in interrupted divided planes radiating
from the central axis, in f. v. being in-
dented somewhat in a pinnatifid manner,
the rays touching the cell wall, some-

times divided, and somewhat dilated
thereat, in transverse view radiate. =
Closterium {Netrium) Digitus (Nag.).
I., G.

P. interruptum (Br6b.). — Frond large,
stout, smooth, three or four times as long
as broad, cylindrical, sides parallel, ex-
tremities conical, and 7-ounded at the ends ;
endochi'ome disposed in straight, strongly
marked filets, interrupted by three trans-
verse pale bands, having a roimded, well-
defined clear space near the ends, in
which are active granules. L. 1-116" ;
B. 1-571". (m. 45.) G.B., I., F., G.,
U.S.A.

P. closterioides (Ralfs). — Frond rather
large, about six times as long as broad,
smooth, fusiform or lanceolate, ends
broadly rounded ; endochrome in distinct
longitiidiaal fillets, interrupted only by
the centi'al transverse pale band, xcith a
single longitudinal sei'ies of large granules,
and a roimded clear space close to the
ends, in which are active granules. L.
1-92" ; B. 1-590". G.B., I., F., U.S.A.

P. Navicula (Br^b.). — Frond minute,
about three or foiu* times as long as
broad, smooth, fusiform, ends bluntly
pointed; endochrome sometimes in fil-
lets, sometimes scattered, interrapted
only by the transverse central pale band,
with one or two large granules in each
half, and a rounded clear space at the
eiids, in which are active granules. L.
1-420"; B. l-760".=V.£&-g{tm(AvcheT).
I., F.

P. truncatum (Br^b.). — Frond minute,
two to fom- times as long as broad,
cylindrical, smooth, ends truncate. Spo-
rangirmi orbicular, smooth, placed be-
tween the dehiscinq, deciduous evwty
fronds. L. 1-969" to 1-555"; B. 1-2212"
"to 1-2100". G.B.,I.,F.

Genus SPIROTjENIA (Breb.). — Frond elongate, straight, cylindrical, or
fusiform, entire, not constricted at the middle, ends rounded or acute ; endo-
chrome spiral. (Gelatinous investment very appai'ent ; cell-division oblique ;
fructification unknown, therefore the position of this genus uncertain.)

single, broad, smoothly-defined, widely-
wound spiral band, its revolutions very
few (one or two). L. 1-142"' to 1-71"'":
"B. 1-287"'. =Palmogla;a endospira (Kg.),
CylindrocystK endospira Gt Endospira

* Endochrome a single spiral band.

SpmoTiENiA condensata (Bv6h.). —
Frond cylindrical, five to ten times
as long as broad, ends rovmded ; en-
dochrome a single, broad, closely-wound
spiral band, its revolutions numerous. L.
1-208" ; B. 1-1048". (u. 4.) G.B., I.,
F.,G., U.S.A.

S. muscicola (De Bary). — Frond cylin-
drical, two to four times a.s long as
broad, ends rounded ; endochrome a

truncorum (Brdb., Kg^. F., G.

S. erythrocephala (Itzigsohn, Braun).
Yvo-aA fusiform, five or six times aa long
as broad, ends acute ; endochrome a
single, rather narrow 8].iiral band, its
revolutions few. = *S minuta (Thurot.
Brt5b.). F., G. '

762

SYSTEMATIC niSTOBY OF THE INFUSOBIA.

2 * Endochrome in several spiral bands.

S. obscura (Ralfs). — Frond cylindi'ical
or fusiform, five to eight times longer
than broad, extremities attenuated, ends
blunt ; endochrome in sevm-al slender spi-

ral hands, their revolutions two or three,
sometimes scattered, leaving a clear space
at each extremity, in which there is
sometimes a free granule. L. 1-247" to
1-226" ; B. 1-1020" to 1-907". G B
I.,F.

C. Gells stipitate.

Genus COSMOCLADIUM (Breb.).
constricted at the middle, stipitate.

CosMOCLADiinvi pidchellum (Br^b.). —
Stipes dendi'oid, dichotomously branched,
hyaline, vsdth a slight intennediate thick-
ening between the cells ; cells terminal
and axiUary, green, segments elliptico-
renifoi-m, smooth (m. 63). F.

We here provisionally place this re-

— Cells rounded, compressed, deeply

markable plant, discovered by M. de
Br^bisson, not knowing as yet anything
as to its mode of growth or development.
The cells, if detached from the stipes,
would scarcely be distinguishable from
those of Cosmarium hiocuUdwn.

D. Cells aggregated into families, forming fasciculi or faggot-Wce bundles.

Genus ANKISTEODESMUS (Corda).— Cells minute, smooth, elongated,
attenuated, aggregated into families forming fasciculi or faggot-like bundles,
each family resulting from the self-division of a single cell, which commences
hy the formation of a somewhat oblique septum at the middle, eventually
rendered more and more oblique from the young cells gro-ndng alongside one
another longitudinally until they each attain the length of the original parent-
cell, the process being again and again repeated by each till the aggregated
family consists of at most thirty-two cells, the family finally again breaking
up into single cells, No other propagation known ; the position of the genus
is therefore doubtful.

Ajjkistrodesmus falcatus (Ralfe). —
Cells very slender, arcuate (rarely straight
or sigmoid), gradually attenuated, ends
acute. L. 1-550"; B. 1-7353". (i.35,36.)
= Wiaphidium fasciculatum (Kg., Nag.).
G.B., I., F., G., Italy.

A. convolutus (Corda). — Cells much
curved, crescent-shaped, somewhat ra-
pidly attenuated, ends subacute. =
phidiuni mimdiim (Nag.). I., F., G.
We have met with a plant (gathered
near Dublin) which we now (tliough
doubtfully) refer to this species, in which
we noticed self-division of the cells, in
an at first oblique, finally longitudinal
manner, very much the same as that
described by Niigeli {Einzell. Akj.) for the
preceding species, and introduced into
the generic character. The colls in our

plant are not quite so much curved as in
Nageli's drawing of this species, and are
rather more acute at the extremities :
we have not noticed the faseicidi to be
composed of more than 8 cells, frequently
of 2 or 4 ; and while so combined the cells
all look in the same direction, the con-
cave sm-face of the one being applied to
the convex surface of its neiglibour.

A. contortus (Thiu-et). — Cells slender,
arcuate or sigmoid, somewhat gently in-
flated at the centi'e, ends drawn out long
and very fine. F.

l^Scenodesmm duplex (Ralfs) is placed
in this genus by Kiitzintr and Niiffeli
under the name of Rhaphidium ; tliat
plant may, however, be the cell of an
/Vnkistrodesmus undergoing division.]

SubfaniHy PEDIASTRE^ (page 24).

Wo shall not attempt to give anything but a very prorisional diagnosis of
the genera here included under the above title (which have long been asso-
ciated with the Desmidiaccffi, and chiefly for that reason finding a place in
the present work), a.s, so far as we can judge, it is not yet dotorminod whether
they should remain united with the ralmellacca;, to wliich they have been

OF THE PEDIASTREjE.

753

referred by IS'agoli, or, with some few other Algte, form a distinct group near
Pahnellacese, and perhaps Volvocinete. Tliey camiot, we think, continue
to be considered as belonging to the Desmidiacese, For the pui'poses of the
present work, however, as they are introduced, we shall just radicate that
the genera here described under the above head agree in the folio-wing
characters : —

Cells combined into a definitely formed frond or family, often either ex-
tei-nally notched or attenuated, sometimes spinous, not undergoing complete
self-fission in the same dii-ection into two perfect cells, but propagating by
the repeated segmentation of the contents of the old cells into a definite
number of portions or " gonidia," which are either stiU or for a time motile,
and which are either arranged according to the typical plan within the parent-
ceU, and by its bursting set free as a new frond or family, or become so
arranged without the parent-ceU, but still involved in its inner membrane,
the whole having emerged by a transverse fissure.

We are disposed to think that here Hydrodictyon should come ; for though
in this plant the development of the active gonidia is simultaneous, not
successional, as in Pediastrium, Pringsheim aUudes to the gonidia in Coelas-
trum sphcericum (which indeed are still) as either the one or the other.
Cruciagenia quadrata QiLQYven)=Staurogenia quaclrata (Kg.), seems to pro-
pagate by complete self-fission, and, gonidia not being described, we believe
cannot belong here. As to Sphaerodesmus (Nag.) information is wanting.

Genus SCEISTODESMUS (Meyen). — Frond or family composed of from two
to eight oblong fusiform or elliptic cells, connected into a single or double
continuous row ; propagating by means of the repeated segmentation, in
parallel planes in one or two directions, of each of the cell-contents into one
or more brood families (not motile), set free by the biu'sting of the parent-
ceU wall. (Niig.)

ScENODESMTJS quadvicauda (Ralfs). —
Cells in a single row ; oblong, rounded at
their ends ; external cells (sometimes
more turgid than the others) furnished
at each extremity with an elongate, often
curved, acute spine or bristle, sometimes
with another from the centre of the
outer margui. L. 1-1121"; B. 1-2631".
(i. 40, 41, 4S.) = Achnanthes quadricauda
(Tui-p.), Arthrodesmits quadricaudutu^
(Ehr.), Scenedesmtis caudatiis (Corda,
Kg.), S. quadricaudatus (Ilass.). G.B.,
I., F., G., U.S.A. jS, central cells fm--
nished at one of their ends with an
elongate, acute, curved spine or bristle,
each half of tlio frond being so furnished
at opposite sides, sometimes the central
cells being also fvurnished at their other
ends %vitn a very short, minute spine.
= S. Niigelii (Breb.). (i. 42.)

S. dispar (l^rdb.). — Cells two or four,
akrniatinr/, oblong, blunt at the ends ;
wlien four the central cells at one end at
oppoxite sides of the frond fiuTiished with
a short acute mucro-like dejected spine,
each spine directed inwards ; when eitlier
two or four, the external cells witli a
similar spine at both cuds; when four,

that spine at the same side of the frond
witli that belonging to the central cells
also du-ected inwards, the other directed
outwards. F.

S. antennatus (Br^b.). — Cells in a
single or double row ; fusiform, or semi-
lunate, ends cuspidate, and each terminated
by a minute orbicular globule. F.

S. dimorphus (Kg.). — Cells in a single
row ; narrow, attenuated, and pointed at
the ends; the central in apposition the
most of their length, the outer externally
lunate. L. 1-1020" to 1-90(5"; B.1-81(X)".
= Achnanthes diminpha (Turp.), S. pec-
tinntus (Meyen), Arthrodesmits pectinatus
(Ehr.). G.B., I., F., G.

S. acutus (Meyen). — Cells in alter-
nating rows; the central fusiform, in
aptposition only at their middk; the. outer
sometimes externally lunate. L. ]-l()G3"
to 1-1000"; B. 1-G250" to 1-0181". =
Arthrodesmus (Ehr.), S. acid us et

obliquus (Ralfs). G.B., I., F., G., Italy.

S. obtusus (Meyen). — Cells in one or
two rows, all ovate or obloni/, ends
rounded. L. 1-2331" to 1-1901"; B
1-4090" to 1-3C23". (i. 37, 38, 39 i
G.B., I., F., G., U.S.A. '

3o

754

SYSTEMATIC niSTORY OV XIIE INFUSOBTA.

S. duplex (Ralfs). — Cells two, slender,
tapering, sigmoid, acute, placed .side hy
side for about half their lcngth. = Rhapht-
dium duplex (I^g.), uec S. motiiliformis

{duplex) (Kg.). G.B., G. This plant
possibly represents a cell of an Ankis-
trodcsmua duiing division.

Genus PEDIASTRTJM (Meyen). — Frond or family plane, circular, elliptic,
or irregular, composed of several cells (a multiple of foiu-), foming by their
union a flattened star-like group, generally arranged in more or less con-
centric circular series, marginal cells externally bipartite or entire ; propa-
gating by " macrogonidia," which, arc subglobose, formed by repeated binary
division of the endochrome of each of the parent-cells of the old frond, 2, 4,
8, 16, 32, or 64 (even 128) in number, and making theii* exit by a transvei-se
fissure from the parent-ceU, involved in its inner membrane, within which
for a time they actively move, presently settling down and arranging them-
selves into a new frond; microgonidia " produced in the same manner, but
shortly rupturing the confining membrane and s^vimming freely away, their
fate unknown (Braun).

* Lohes of the outer cells two, deeply
emarginate or truncate.

Pediastbum Tetras (RaUs). — Frond
very minute ; cells four, their interstices
forming a cross, their outer margin bi-
lobed, angles acute. L. 1-2941" ; B.
1-2272", (n. 27.) = Micrasterias Tetras
(Ehr.), P. biradiatum {Tetras) (Kg.).
G.B., I., F., G., U.S.A.

P. lieptactis (Menegh.). — Frond minute;
cells eight {seven disposed in a single series
round a central one), bUobed, angidar.
L. 1-2900"; B. 1-2500". = Mia-asterias
heptactis (Ehr.), JEuastruin hexagonum
(Corda), P. simplex (Hass.), P. bira-
diatum {heptactis) (Kg.). G.B., I., F.,
G., U.S.A.

P. biradiatum (Menegh.). — Inner cells
subquadiilateral, with a linear notch, the
outer quadrilateral or somewhat cuneate,
approximate for tlwir entire length, ex-
ternally deeply bipartite, their incisions
naiTOW, the subdivisions trimcate or
truncato - emarginate. L. 1-1200" to
1-2550" ; B. 1-1754" to 1-2040". = Mi-
crasterias Rotula (Ehr.), P. biradiatum
{Rotula) (Kg.). Tnis with the two pre-
ceding may possibly make but one ti'ue
species, P. Ehrenberr/ii (Braun.). (i, 62.)
G.B., I., F., G., U.S.A.

P. Rotula (Ehr. emend. Braxm). —
Inner cells with a wide notch, and sepa-
rated by wide lacimas, the outer subqua-
drilateral, approxit)iate only at their bases,
which are nearly square, externally deeply
bipartite, their incisions broad, the sub-
divisions naiTow, iuciso-dcntate. F., G.

P. caiidatum (Braun). — Inner cells

fientagonal or hexagonal, -with a deep
inear notch, the outer quadrangular,
externally deeply bipai-tite, the subdivi-

sions ti'imcate, very slightly concave at
the centre, and furnished at the angles with
a vei-y minute, short, bristle-like spine.
= P. Rotida (Nag.). G.

2 * Lobes of the outer cells two, entire,
attenuated.

P. Selencea (Kg.). — Cells crescent-
shaped, ai'ranged in one or more circles
roimd one or two centi-al ones, connecting
medium coloured. = P. elegans (Hass.),
P. lunare (Hass.). G.B., F., G.

P. gracile (Braim). — Frond minute,
of foiu" or six cells (four external, with
or without two centi-al cells) ; marginal
cells deeply bipartite ; subdivisions orate,
tapering to a point. L. 1-1020" ; B.
l-\Q'd2".= Micrasterias Coromda (Ehr.),
P. Napoleojiis (Hass., Menegh., Kg., nec
Ralfs), P. sitnplex (Ralfs). G.B., F., G.

P. 2)ertusum (Kg.). — Cells arranged
in circles roimd one or two central ones ;
inner cells quadi-angidar, sides concave
and leaving anguhr vacant intervals ; the
outer cells tcith square bases, externally
triangularly notched, the subdivisions ta-
pering to an acute point. L. 1-22QQ" ;
13. 1-3268". = Micrasterias Boryana
(Ehr.), P. tricyclium (Hass.), P. emargi-
natum {pertusum) (Kg.). G.B., I., F., G.

P. granidatum (Kg.). — Cells eight,
rough with minute granules, six cells
aiTanged round two central, the inner
subquadrate, the outer havmg two taper-
ing lobes. L. 1-2000"; B. 1-1850".

G.B., I., F., G.

P. iN'"rt;)ofco;ii:s (Menegh.).— Cells eight,

six arranired roimd two central, the inner

hexactis (Haas.). G.B., G,

OF THE PEDIASTRE^.

755

p. Boryanum (Menegh.). — Cells ar-
ranged in one or more circles round one
or two central ; the inner vaiiable, gene-
rally concave at one side, the outer taper-
ing into two long subulate points, the notch
narrow. L. 1-2083" to 1-1633"; B.
1-2733" to 1-2222". (i. 59, 60, 61, 68,
69, microgonidia.) = Micrasterias Bory-
ana (Ehi-.), P. suhulifertim (Kg.), P- cru-
ciatum (Kg.). G.B., I., F., G., U.S.A.

P. ellipticum (Hass.). — Cells varying
in nimiber and an-angement ; outer cells
suddenly contracted into two short, cylin-
drical, obtuse processes. L. 1-1754" to
1-906" ; B. 1-1515" to 1-1020". )3, pro-
cesses of the lobes ti-uncato-emarginate.
= Micrasterias elliptica (Ehr.), P. vagum
(Kg.), P. comtrictum (Hass., Kg.), P. bi-
dentulatum (Braim). G.B., I., G., U.S.A.

P. anc/ulosum (Menegh.). — Cells ar-
ranged in one or more cu'cles round one
central, the inner cells roundly angidar,
the outer obliquely truncate, emarginate,
the subdivisions not tapering into rays.
L. 1-2732" ; B. 1-1942". = Micrasterias
angidosa (Ehr.). G.B., F., G.

3 * Outer cells with only one attenuated
lobe (Monactinus).

P. simplex (Meyen). — Cells eight, in a
single series suiToundlng a central vacant
interval, narrow-ovate or lanceolate, very
gradually tapering, acuminate, approxi-
mate only at their \)?LaQS.= Monactinus
simplex (Kg.), M. simplex et acutangulus

(Corda), M. octonarius (Bail.) P F., G.,
U.S.A. There seems to us to be some
doubt as to the absolute distinctness of
this and P. gracile (Braun), as it is pos-
sible the four deeply bipartite external
cells of the latter may nave been mis-
talfen for eight simply attenuated cells
as described for P. simplex (Meyen).

P. duodenarium (Bailey, sp.). — Inner
cells/oMr, somewhat triangular, enclosing
a central, quadrate vacant interval, and
fom- broadly lanceolate vacant intervals
between them and the outer series, to
which they are imited by their tenninal
angles ; outer ceUs twelve, subovate,
truncate below, much attenuated, acu-
minate. = Monactinus duodenarius (Bail.).
U.S.A.

P. ovatum (Braim). — Cells ovate, ter-
minating in a long, acute point, granu-
late, an-anged in two series, inner three,
outer ten. =Astcrodictyon ovatum (Ehr.),
Monactinus ovatus (Kg.). G.

P. Triangulum (Braim). — Cells trian-
gular, smooth, an-anged in three series,
the centre vacant. Astei-odictyon Trian-
gulum (Ehr.) = Monactinus Triangulum
(Kg.). G.

4* Outer cells not lobcd (Anomopedium).

P. integrum (Nag.). — ^Frond irregidai-,
cells rounded or bluntly angular ; outer
cells not emarginate, generally possessing
externally two short mucix)-like spines
(I. 46, 47, 48). G.

Genus CCELASTRUM (JTag.). — Frond or family hollow, globular or sub-
cubical, composed of polygonal (or spherical) cells united in one layer into a
hollow clathrate net-liJce family, the cells di'awn out on the exterior into one
or more lobes, or simply spherical ; propagating by tlic segmentation of tlie
ceU-contents into a definite number of portions which become arranged into
a hollow young frond resembling the parent, ultimately set free bj'^ the
bursting of the parent-cell.

CcELASTEUM si^hccricum (Nag.). —
Fronds spherical or oval ; cells hex-
agonal, drawn out externally into a
burnt cone, interstices 6-6-angidar. (i.
49, 50, 51.) G.

G.cubicum (Niig.). — Fi-ond subcubical,

cells hexagonal, drawn out externally
into two snort truncate projections, in-
terstices quadrangular, (r. 54, 55.) G.

C. microporus (Niig.). — Frond globu-
lar, ceUs exactly spherical, interstices
minute. G.

Genus SORASTRUM(Kg.). — Frond or family solid, globular, composed of
cuneiform or cordate cells, somewhat compressed and umtcd into glolndar
families, their narrow ends meeting in the centre and outwardly emarginate
or divided. Propagation unknown.

SoRASTRUM spinulosum (Niig.). — Ex-
ternal margins of the cells dilated,
slightly emarginate, the rounded angles
furnished each with two minute/ acute,

subidate spines, (i. 5G, 57, 58.) G.

S. echinatum (Kg.). — External mar-
gins of the cells deciply bifid, the sub-
divisions subulate. G,

3c2

756

SYSTEMATIC HISTOHY 01? THE XlTFTTSOinA.

Sub-group DIATOMEiE or DIATOMACE^E.
(Page 31, Plates IV. to XVII. and part of II.)

[For reference to the species figiu-ed in this work, see Index of Diatomaceae

illustrated.]

Fetjsttjxes or cells, either simple or pseiido-uniceUular by complete separa-
tion, or united in tablets or filaments, furnished with a sculptured siliceous
coat in three portions, a median one (connecting zone) and two lateral ones
(valves) imited by distinct sutures ; internal substance yeUowish-bro-mi
(rarely olive-brown) ; reproduction by conjugation and subsequent foi-mation
of sporangia.

The general history of the Diatomaceae has been so fuUy treated of in the
first part of this work (p. 31) that it is here only necessary to explain some
terms used in the descriptions.

The Diatomacea3 differ, in several respects, so widely from acknowledged
Algae, that in our opinion they may be regai'ded rather as an order related to
the Algae than as a family belonging to them.

The siliceous covering is composed of three portions. The centi'al one is
sometimes called "connecting membrane" and "cingulum;" we, however,
prefer Professor Amott's term, " connecting zone," as less Hkely to mislead.
The lateral or jxmction surfaces correspond to the septa of a Conferva, and are
called valves.

The late Professor Smith considered the central portion \messential and
produced only preparatory to self-fission. We, on the contrary, regard it as
of great importance, and quite unkno'mi in the true Algte. It is conspicuous
in the conjugating and, consequently, matiu'e frustules ; and we think the con-
clusion illogical that it has no systematic value because obscure in newly-
formed frustules. It is evidently essential in Diatoms with flat valves, since
otherwise there could be no cavity to contain internal matter.

We use the term " front view " to denote that position of the frustule
Avhen the connecting zone is fully presented to the eye, and " side view "
when the centre of the valve is in a similar position. When we speak of tlie
" valve," unaccompanied by a qualifying epithet, it must be understood as
identical with " side view."

"Longitudinal" means in the direction of the connecting zone, and
" transverse " in the opposite direction uniting the valves. When so applied
to the frustule of a Diatom, these terms acqiiii-e a meaning exactly the reverse
of that in which they are used when applied to the joint of a Conferva and
the frond in the Desmidieaj. For example, the frustule in some Diatoms .and
the frond in Closterium are both described as longitudinally lunate, wliilst
they are really extended in opposite directions : unless the change in the
meaning of the terms be remembered, an idea of similaiity will be convoyed
which is altogether erroneous.

The valves are sciilptui-ed, cellulose, or striated ; the apparent absence of
striae in some instances may be accounted for by their extreme delicacy
placing them beyond tho reach of oiu- instruments, since the greater the
penetration of the object-glass, and the more perfect the illimiination, the
greater is the number of species found to possess them. Wlien, therefore, we
use the terms " smot^th " and " veiy smooth " in dcfuiitions taken from foreign
works, they must be understood to mean only that the striaj were too fine to
be ascertained by the microscope of tho dcscriber.

OF THE BIATOMACEiB.

757

The word "transverse" is, for the sake of brevity, omitted before strias in
the definitions, but, unless tlie contrary be expressed, it must always be
understood.

When the frustules are lunate or curved, the convex margin is called the
dorsum and the opposite the venter.

We have not mentioned the Sporangia in the generic and specific descrip-
tions, because the examples recorded are too few, and that condition is too
seldom met with to be practically useful. With respect to the general
history of the Diatomacea3, the importance of Mr. Thwaites's discoveries can
scarcely be overrated (see p. 61). We consider it, however, desirable to point
out, that whilst the similarity of their conjugating process to that of the
Desmidieae affords a powerful argimient in support of the vegetable nature of
the Diatomacece, the widely different characters of their sporangia, not merely
in form but in subsequent changes, furnish irresistible evidence of the pro-
priety of separating the Desmidieae fi-om the Diatomaceae. The resemblance
of the reproductive bodies in the latter to the parent frustules, and their con-
tinuous growth and increase by self-division, is so unlike what we find in
the sporangia of the Desmidieae and Conjugatae, as to appear more like an
" alternation of generations " than examples of true sporangia.

The first attempt at a scientific arrangement of the Diatomaceae was by
C. A. Agardh in the ' Conspectus Criticus Diatomacearum.' He distributed
them into three families — Cymbelleae, Styllarieae, and Fragilariece, according
to the form of their frustules. He considered that in each family the frus-
tules might be free, stipitate, imited into a filament, or enclosed in a fi-ond.
This system was greatly extended and improved by Professor Kiitzing ; and, as
we believe his arrangement (p. 101) is the best and most natiu-al yet pro-
posed, we have used it in this work, admitting, however, some judicious
alterations proposed by Meneghini and others. It is true we do not meet
with examples of the four conditions in each family ; but they may faii-ly be
anticipated to occur, and their absence regarded as lacunae likely to be filled
up by future discoveries. We have thus brought together nearly allied genera ;
for it is often difficult to distinguish a Eimotia from a Himantidium, a Tri-
ceratium from an Amphitetras, a Cymbella from a detached Cocconema, and
an escaped fnistule of CoUetonema fi'om a Navicula. The arrangements of
Ehrenberg and Smith we regard as far inferior, — separating, as they do, such
nearly allied forms. Indeed the fame of those eminent obsei-vers must
depend on their intimate knowledge of genera and species, and on their
definitions being superior to those of their predecessors, and not on their
primary divisions. We feel persuaded that, but for liis lamented death.
Professor Smith would have been led by increased acquaintance with the
Diatomacea3 to modify his views in that respect in a future edition of his
valuable and beautiful work on the British Diatomaceae.

ANALYSIS OF THE FAMILIES OF DIATOMACE^.

A.

Valves with central nodulo and median longitudinal lino B.

„ with umbilicus or pscudo-nodulo and radiant lines or

cellules 12

,, witJiout a central nodulo 2

Frustules in side view limato or arcuato 3

« „ with symmelriod margins Q

Valves dissimilar Stkiatki.le.e,

M similar .|

Valves cellulose,' without transverse strirc Akoulifbh.e.

I, not cellulose fi

758

SYSTEMATIC niSTOKY OF THE 1NFTJ80HIA.

' Valves with pervious costce or stria; Eunotib*.

a longitudinal line or keel ■'. Sukiuelle^.

Prustules cuneate in the front viev^ j

„ not cuneate in the front view n

' Frustules free ; valves with alas Sueirella.

„ attached or united in filaments ; valves witliout alis ... 8

Valves dotted, dots not forming strias Eucampia.

„ not dotted, or the dots arranged in transverse lines 9

Frustules radiating from a common centre; valves obovate or

clavate 10

,, not radiant; valves with symmetrical ends....^ FeagilaeiejE.

Frustules in front view with longitudinal vittte LicMOPUOEEiE.

„ „ without longitudinal vitta (costse per-
vious) MEEIDIEiB.

Connecting zone (annulate) vrith imperfect internal septa Steiatelle.e.

„ ,, vrithout internal septa 12

Lateral view witli 3, or more, angles or lobes Asgvliferm.

„ ,, circular 17

„ ,, neither angular nor circular 13

Valves not conspicuous in front view, wliich is mostlj longer

than broad 14

„ compressed, inflated, conspicuous in front view, which is

mostly broader than long 15

Valves with a longitudinal line Sueieellej:.

,, without a longitudinal line FRACiLAEiEiE.

' Valves iu front view, rectangular, with transverse capitate vittae . TEBPSiNOfe.E.

„ ,, with produced angles, processes, or spines 16

/ Valves cellulose, symmetrical BroDULpmE^.

„ not cellulose, mostly dissimilar Ch.etoceee*.

I' Frustules saddle-shaped : valves mostly with longitudinal blank

17. ] space Campylodiscus.

[ ,, not saddle-shaped ; central blank space (if any) orbicular 18

I Valves cellulose 19

\ „ not cellulose Melosise.e.

I Frustules simple ; lateral view more conspicuous than front 20

10.-^ „ either united into filaments or front view broader than

I lateral Melosire*.

2y r Valves furnished with projecting processes Eupodisce^.

■ [ „ without processes, but sometimes with minute teeth Coscinodisces.

B.

' Only one valve vrith a central nodule 22

Both valves with central nodules 23

' Frustules adnate, not genuflexed Cocconeide^.

„ not adnate (often stipitate), genuflexed Achnasthk*.

Frustules cuneate in front view ; valves usually with dissunilar

ends GoMPHONKMM.

,, not cimeate ; valves with symmetrical ends 24

' Median line rib-like and distinct ; nodules distinct 25

,, notrib-Uke; nodules mostly obscure 2

' Side view limate ; nodule mostly excentric 26

„ not lunate (rarely Innately curved) ; nodule central ... Navicule.e.

Valves vejitricose, striaj not decussating Cymbellke.

,, not ventricosc, stria; decussating Toxosidea.

10.
11.
12.

13.

14.
15.
16.

18

21.
22.

23.

24.
25.

26.

C.

Individuals of one piece, with radiating spines Actikisckk.

Families.
* Valves without a central nodule.
Eunoticic. Meridieas. Licmophorcro. Fragilariea;. Synedrea*. SurirelloA\ Stria-
tellca;. Torpsinoiiro. Biddnlphio£P. AnguUferca;. Eupodiscca?. Coscinodiscero. Melosircsf.
Clinitoccrcuj.

2 * / ''ahrs with a median line and a central nodule.
Coccont'idcce. Achnanthcio. Cynibellctc. Qoinphoncmooj. Navicidcw.

Actiniscew.

OF THE EXn^OTIEiE.

759

FAMILY I.— EUNOTIE^.

Frustules free or adnate, in lateral view lunate or arcuate, with transverse
stria) or costal, uot intornipted by a central nodule or longitudinal line. The
essential characters of this group are the lunate form of the frustules in the
lateral view, and the strioe being continuous across the valve, and not inter-
i-upted by a longitudinal line. It is easily distinguished, except from some
species of Synedra, which, however, are Knear-cm-ved rather than lunate,
and usually have an evident though faint longitudinal line. Ampliipleura
infiexa, which m form more nearly resembles Eimotia, has a longitudinal
line passing down the middle of the lateral valves. The Eunotieas have one
siu-face of their connecting zone flat or concave and the opposite one convex,
the convexity being usually greater than the conca^ity. The lateral portions
or valves are either flat or convex ; in the former case they do not appear in
the front view, and the fnistule appears quadrilateral ; in the latter, on a
front view, they have an oval form. like most Diatomacese, the connecting
zone has two pimcta at each end.

Genus EPITHEMIA (K.). — Frustules Innately curved in lateral vieAV, and
furnished with transverse internal ribs (canals, Sm.) ; usually adnate by the
flat or concave surface of the connecting zone, and not by one of the lateral
valves, like Cocconeis. The lateral view has strongly-marked transverse lines,
which Mr. Smith, in his beautiful work ' The British Diatomaceas,' calls
canalieuli. We consider them internal ribs ; in fragments it is by no means
difficult to see them, as they give a dentate appearance to the margin ; their
form is somewhat triangular, but we are unable to detect any internal cavity
or canals. Mr. Smith, however, may have used microscopes of larger angular
aperture and higher magnifying powers than we employed. Besides these
ribs, the valves have transverse striae or punctated lines. The adnate frus-
tules and strongly-marked ribs distinguish Epithemia from Eunotia and
Himantidium. In the front view the ends of the ribs frequently produce a
beautiful beaded appearance. These beads form two longitudinal lines, and
are more or less remote from 1)he margins, according to the convexity of the
lateral valves. They ai-e frequently more numerous on one side than on the
other, and arc not all equidistant, even in the same series.

* Front fiew gibbous at the centre,
costce fine.

EpiTHEraA gibha (E., K.). — Front view
elongated, linear, inflated at the centre
and ends. I03. p. .33, t. 4. f. 22. = Na-
vicitla (/ibha, E Inf. p. 184 j Eunotia
ffibba, EA & M, many figures. Fresh
water. Common. Ebrenberg gives about
100 habitats in Europe, Asia, Australia,
Africa, and America, (xji. 27.) Strias 3G
in -001"; costBe 15 in -001".— Distin-
guished by its elongated frustules, fine
strife, and dilated ends; but, from its
nearly straight side-view, its proper genus
may be overlooked.

_ E. ventricom (K.).— Front view ellip-
tic, oblong, with gibbous middle; valves
arcuate, with gibbous dorsum and atte-
nuated, acute, somewliat inciM'V(>d ends ;
striaj fine. KB. p. 35, t. .30. f. 9 ; SBD.

i. pi. 1. f. 14. Fresh and brackish water.
Europe.

E. angulata (Perty). — Dorsum tm-gid,
sloping to the obtuse ends ; venter con-
cave at the centre, strije about 12 in
1-1200". Rab Diat. p. 18, t. 1. f. 18. =
Eunotia Jastrabtmsis, EM. pi. 8. 1. f . 3 ?
Switzerland. Fossil. Hungary. Ac-
cording to tlio figures, the frustules
are gibbous or rhomboid in the front
view.

2* Front vieto with viarginal bead-like
dots formed by the capitate ends of the
costal ( = Cystopleura, Br^b.).
E. Argus (E., K.). — Front view rect-
angular, witli conspicuous ocelli termi-
nating tiio stalk-liko costas, and having
distinct striic interposed brhvoon th(>ni
Ki;. p. 35, t. 20. f. 55. = Eimotia Ar,,us,
EA. p. 125, & M. 1. 15 A. f. 50. liurope,

7G0

SYSTEMATIC HISTORY OF THE INFUSOBIA,

Asin, Australia, and America, (xv. 11 .)
Valve lunately curved. Sporangial frus-
tides with somewhat augidar dorsum.
A common species, easily recognized by
the distinct marginal striaa intei-posed
between the rather distant, conspicuous
bead-like ocelli.

E. alpestris (K.). — Front view rectan-
gular or subcimeate, with conspicuous
marginal ocelli and interposed striiB ;
valves narrow, arcuate, with the rounded
apices scarcely a little recm-ved. KB.
p. 34, t. 5. f. 10. = -B. ostrantina, Rab Diat.
p. 19, t. 1. f. 29? France, England,
(xiii. 8.) We are unable to distinguish
this species from E. Argus ; for we believe
that the subcimeate front view is an
accidental variation, and iu specimens
from M. de Brebissou we find that cha-
racter by no me.'ms constant. Striaj are
interposed between the ocelli, as in JS.
Aryus, and are nearly, if not quite, as
distant as iu that species ; and we doubt
whether recurs-ed extremities of the
valves are not sometimes foimd in both.

E. reticulata (Niig.). — Front view rect-
angular, margins with stronger capi-
tate and intermediate finer ones ; valves
slightly cm-ved, the obtuse ends some-
wliat attenuated ; stria; strong, 3 to 5 in
1-1200"; the interstices regularlj' reticu-
lated, veined, margins finely transversely
striated. KSA. p. 889. Switzerland.

E. luiif/icornis (E., S.). — Front view
subreclangidar, with conspicuous mar-
ginal ocelli and striic, as in E. Argus ;
valves elongated, cm-ved, with obtuse
ends and slightly angular dorsum.
SBD. pi. ;}0. f. 247. = Hunotia longi-
cornis, EM., several figures. Europe,
Asia, and America, (xv. 6-9). Costte
strong, altei'natiug with striated spaces.
I'crhaps a sporangial state of JE. Argus.

E. uccUatu (E., K.). — Front view" bar-
rel-shaped, with conspicuous marginal
ocelli and interposed strire ; valves lu-
nately curved, with roimded apices. KB.
p. 34, t. 29. f.-57 ; SBD. pi. 1. f. 6. =Eu-
■iiolia ocellata, E. Fresh water. Em'ope
and America. Fossil. Greece.

E. Eugcnice (S.). — Front view inflated,
with truncate extremities ; valves lunate,
with straight, tnmcatc extremities ;
costic distinct, 8 in -001"; ocelli con-
spicuous ; striaj 32 in -OOl". S Au.
.fan. 1857, p. 7, pi. 1. f. 1. Fresh water.
i>iarritz, France. The nearest allies of
this species arc E. prohoncidca and E.
Soirx. ft may be distinguished from
tho (irsl by ils distinct ocelli, and from
the second by its conspicuous costic and
their arcola-like interspaces. S.

E. cowii!«(E.).— Small; valves cm-vcd,
with regularly convex dorsum and
rounded ends ; striaj strong and gi-a-
nidar. = Eurwtia comta, EA. 1840, & M.
pi. 6. 2. f. 17 e,/. Fossil. Greece. We
are not certain whether this and the next
species are coi-rectly placed iu the ocel-
lated section.

E. llellenica (E.). — Valves long,
curved, with regularly convex doreum
and rounded ends ; costa? strong, 4 in
1-1200", having very delicate striie in-
tervening between them. =iEunotia Hel-
lenica, EA. 1840, & M. pi. 6. 2. f, 17 «, b.
Fossil. Greece.

3 * CostcB not capitate.

E. constricta (Br6b.). — Front \aew
elliptical, slightly constricted at the
middle ; valve semiluuate, with 8 distinct
costae in -001". SBD. vol. i. p. 14, pi.
30. f. 248. Brackish water. France and
England. Sti-ia3 30 in -001". S.

E. margaritifera (Rab.). — Front view
baiTel-shaped, with trimcate ends and
striated margins ; valves with three dor-
sal undidations and rounded ends ; costse
4 to 5 iu 1-1200"; bordered by pimcta,
Rab Diat. p. 17, pi. 1. f. 32. Persia.

E. Musculus (K.). — Front view sub-
orbicular ; valves lunate, with verj' con-
vex dorsum, concave venter, and taper-
ing acute apices ; costre distinct. KB.
p. 33, t. 30. f. 6 ; SBD. pi. 1. f. 10. =
Eunotia SpJicerula, EM. pi. 8. 1. f. 6?
Brackish water. Em-ope, Asia, Africa,
and America, (xm. 18.) Strice 40 in
•001". S.

E. rupcstris (S.). — Front view elliptic
or elliptic-lanceolate ; valves semilan-
ceolate, tapering to the subacute apices ;
costae distinct ; stiire faint, 40 iu "001".
SBD. vol. i. p. 14, pi. 1. f. 12. E. gibhc-
ruln, KB. t. 30. f. 3 ; KA. p. 3. - E.
West(rmanni, SBD. vol. i. p. 14, pi. 1.
f. 11. Fi-esh or bi-ackish water. Europe
and America.

E. ijuiiiqut'cosfata (Rab.). — "\^alve semi-
lanceolate, with obtuse ends, and five
somewhat converging costre. Rab Dial-,
p. 18, t. 1. f. 35. Germany.

E. Jlyiidmani (S.).— Front view veu-
tricose with truncate ends ; vah es stout,
lunately curved, with rounded apices;
striro mouilifonn, 10 iu -001" ; cost* in-
conspicuous. SBD. vol. i. p. 12, pi. 1. f. 1.
= Eunotia Luna, EM. pi. 15 A. f. 68.
Britain. Large; valve not recmved.

J-:. IVcstvnnaimi {Vu, K.).— Fi'ont view
elliptic; vdves .«cmilunate, with turgid,
convex doi-suui gradually altenuated to
the rather obtuse not in-ominent apices ;

OF THE ETTNOTIEiE.

761

striaj scarcely converging, 7 or 8 in
1-1200". KlS. p. 23, t. 30. f. 4. = Exi-
notia Westennaimi, E Inf. p. 190, & M,
many figures. Em-ope, Asia, and Ame-
rica, (iv. 2 ; rs. 157.) In Ehrenberg's
figures tbo frustules are large, the stout
valves have the obtuse apices somewhat
produced and recui-ved, and the inter-
stices of the costee fm-nislied with dotted
lines.

E. (jihberula (E.). — Front view elliptic,
■with slightly produced apices; valves
with gibbous dorsmn, slightly concave
venter, and attenuated, recurved apices ;
strife converging, 33 in -Q^l" .=Eunotia
gibberula, EA. p. 125, & M, nimieroiis
figiu-es. = E. Sorex, KSA. p. 1 ; SBD.
vol. i. p. 13, pi. 1. f. 9. Fresh or braclrish
water. Common. Eiu-ope, Asia, Aus-
tralia, Africa, and America. Costse in-
conspicuous.

E. Saxonica (K.). — Minute ; fi'ont view
rectangidar ; valves Innately cm'ved, at-
tenuated, with obtuse not recm-ved ends ;
strife sub converging, 6 to 7 in 1-1200".
KB. p. 35, t. 5. f. 15. Italy and Ger-
many. 1-840".

E. Textricula (E., K.). — Valve lineai',
limately cui-ved, Avith rounded ends ;
costse stout, distant; interspaces Avith
series of longitudinal strire. KB. p. 35,
t. 29, f. 53. = Eunotia Textricula, EA.
p. 126, & M, several figm-es. Em-ope,
jVsia, Australia, Africa, and America.
Small ; ends not recurved.

E. Zcim (E., K.). — Front view sub-
linear ; vah es senulimate, with convex
dorsum, straight venter, and very obtuse,
slightly prominent apices; costaj con-
vergent, 5 to 7 in -OOl". KB. p. 34,
t. 30. f. 5; SBD. pi. 1. f. 4. = Eunotia
Zebra, E. Em-ope, Asia, Africa, and
America. StriiB 33 in -001". S.

E. zehriita (E., K.). — Elongated ; valves
with evenly convex dorsum, gradually
decun-ent into the obtuse, constricted
apices; interspaces dotted. KB. p. 34.
= Eunotia zebrina, EA. p. 126, Sc M,
several figures. Asia, Austxalia, Ame-
rica, and Europe.

E.<Mr(7M/«(E.,K.J. — Tiargo ; front view
linear or slightly dilated at the middle ;
valves ciirviid, with the slightly convex
dorsum gradually attenuated to the trun-
cate apices, wliich are neither prominent
nor recui-ved ; striic diverging, 8 or 9 in
1-1200". KB. p. 34, t. 5. f.U.=Eunotia
twjiida, E Inf. t. 14. f. 5. Europe, Asia,
anil America, (iv. 1; ix. 169-161.)

E. i/ranulfila {E., K.). — J>argc : front
view linear or linear-oblong; valves
slender, slightly arcuate, witli obtuse,

recurved apices; stiise moniliform; costaj
distinct. KB. p. 35, t. 5. f. 20. E. Faba,
KB. p. 36, t. 5. f. 21. = Eunotia (/rami-
lata, E Inf. p. 191, t. 21. f. 20 = Epithc-
mia turyida, SBD. vol. i. pi. 1. f. 2. Eu-
rope, Asia, Africa, and America,

E. Vertagus (K.). — Large ; fi-ont view
snblinear, gradually dilated at the mid-
dle; valves slender, ai'cuate, with rounded,
refiexed apices ; costte converging, 10 in
1-1200" ; strife punctate. KB. p. 36,
t. 30. f . 2 = ^. granidata, SBD. vol. i.
t. 1. f. 3. Fresh water. Europe. Re-
sembles the last, but the valves aa-e far
more slender.

E. Librile (E., K.). — Large ; front view
rectangular ; valves arcuate, with con-
cave venter, dorsum evenly convex at
the middle, suddenly decreasing towai'ds
the obtuse, slightly revolute apices ; in-
terspaces between the costae dotted.
KB. p. 35, t. 29. f. 45. = Eunotia Librile,
E Amer. p. 126, t. 3. 1. f. 38. Asia,
Afiica, and America, (xu. 24, 25.)

E. Porcellus (K.). — Large ; fi-ont view
lineal', seven times as long as broad;
valves with convex dorsum, concave
venter, and truncate refiexed ends ;
striae converging, 11 in 1-1200". KB.
p. 34, t. 5. f. 18, 19. Fossil. San Fiore.
(xm. 12.) 1-240" to 1-216".

E. proboscidea (K.). — Small ; front
view rectangular with obtuse angles ;
valves with gibbous dorsum, slightly
concave venter, and constricted, obtaise,
remarkably recm-ved ends ; costte con-
spicuous, converging. KB. p. 35, t. 5.
f. 13 ; SBD. vol. i. p. 13, pi. 1. f. 8?
Fossil, Liineburg ; Britain ; recent, Jer-
sey. _ CostfB 5 or 6in 1-1200". British
specimens have the fi-ont view inflated,
and therefore may be distinct.

E. ? marina (Donkin). — Dorsal view
rectangidar, with longitudinal scries of
puncta on the connecting zone; valves
linear, slightly arcuate, with produced
rostrate apices; costfo conspicuous; in-
terspaces punctated. Donkin, TMS.
vol. vi. p. 29, pi. 3. f. 14. Marine. Eng-
land. A largo and beautifid Diatom,
whose genus is somewhat imccrtain. It
agrees wi(li Amphora in having the lon-
gitudinal rows of puncta confiued to the
dorsal surface, whilst in the form of its
valves it resembles some species of
Nitzschia. Costao and striixj 11 in -001".
Donkin,

Doubtful and insufficiently known species.

E. Electra .= Eunotia Elcctra, EM.
pi. 37. 3. f. 3. Fossil. Prussia. Vnlvo
somiorbicular, with strong, rntliant stnx.

762

SYSTEMATIC HI8T0B.Y 01? THE INFUSOEIA.

E. Idndigii (Rab.). — Minute ; front
view orbicular ; costiB 6 to 7. Ilab Diat.
p. 19, pi. 1. f. 20. Bogota.

E. Sancti Antotiii = Eimotia Sancti
Antonii, EM. pi. 34. 5. f. 7, &c. Ame-
rica. Fi-ont view rectangular, vsdth
conspicuous marginal capitate stri.ie;
valves obtusely lanceolate, straight, with
sti'ong transverse costae. Probably a
Denticula.

E. Beatorttni=Eunotia Beatorum, EM.
pi. 34. 5. f. 8. America. Front view
rectangailai', with marginal gland-like
puncta. According to Ehrenberg, this
species is allied to E. Sancti Antonii.

E. Lunula = Eimotia Zninula, EM.
pi. 33. 7. f. 9, & pi. 33. 14. f. 8. Ehren-
berg's figm'es diifer considerably. The
first is slightly arcuate, elongated, with
obtuse, slightly recm-ved endsj the se-
cond is smaller, lunate, rapidly tapering
to the obtuse ends. Both have radiant
costse without intermediate dotted lines.

E. mesolepta = Eunotia mtsolcpta, EM.
pi. 9. 1. f. 26. Fossil. France. Valves
elongated, slightly curved, with attenu-
ated middle, and conic ends ; costa3 alter-
nating with dotted striae.

E. niesogongyla= Eunotia mesogongyla,

EM. pi. 9. 1. f. 27. Fossil. France.
Valves linear, elongated, slightly curved,
with gibbous middle, and rounded ends ;
costas alternating with dotted strias.

E. P Faha (E., K.).— Valves semioval,
shghtly arcuate, with obtuse, verj' slightly
recm-ved apices, and 9 moniliform stria)
in 1-1200".= Eunotia Faha, EM. Seve-
ral figures. Ehrenberg's figm-e seems to
us rather to represent a Emiotia than an
Epithemia.

E. ? cingulata (E., K.). — Small, smooth,
with convex dorsum and tumid connect-
ing zone. KB. p. 36. = Eunotia ? cin-
gulata, EA. p. 126, t. 2. 6. f. 34. North
America. Ajrin to E. gibherula, E.

E. Cocconema = Eunotia Cocc&nema,
EM. pi. 34. 7. f. 1. Canton. Valve
stout, semUimate, with regularly convex
dorsum, straight venter and rounded
ends, strong costse, fine intennediate
striae, and a longitudinal blank line.

E. Cistula = Eunotia Cisttda, EM.

f)l. 8. 1. f. 5, &c. Asia. Front view ob-
ong or elliptic, with costate margins ;
valves stout, limate, with obtuse ends,
strong, radiating costae, and a blank
longitudinal line.

Genus EUNOTIA (E.). — Frustules free, in front view quadrangular, in
lateral view lunate, or arcuate, and striated. In form, Eimotia is allied to
Epithemia ; but the lateral surfaces of the fi'ustules are merely striated, and
want the conspicuous costse of that genus. The superior mai-gin is usually
undulated, — an appearance caused by transverse depressions. The frustules
are not aduate, and in the front view do not appear beaked.

We believe that the species in this genus, as in several others, have been
founded upon insufficient characters, and that those forms which differ only
in the undulations should, as Professor BaUey suggests, be regarded as
varieties. As this work, however, is intended to include aU generally
admitted species, we are content to indicate our opinion, the correctness of
which must be determined by future observations. Kiitzing and Mencghini
describe the transverse section as trapezoidal, and regard it as an important
generic character ; but we agree with Professor Smith in doubting tlie occur-
rence of such a form. Several species of Eunotia have been found by Bailey
and Br^bisson united into short bands ; and unless the generic charactera of
Eunotia and Himantidium can be strengthened, it Mall become necessary to
reunite these genera. The dorsal elevations in Eunotia and Himantidium
appear, in the front view, transverse dai-ker bands.

rica. Akin to E. nodosa, but with in-
flated and straidit apices. E.

E. vcntralis (E.). — Valves elongated,
linear, curved, -with tumid, roxmded
apices, and gibbous venter. EA. p. I2G,
& M, several figm-es. Europe, Asia,
Africa, and Aniorica,

E. Luna (75.).— Volvos linonr, lunatoly
curved, with simply convex dor.<nni,
cibbous venter, aiid obtuse ai>iecs.

* Dorsal margin of valves not dentate.

Eunotia nodosa (E.). — Valves slightly
arcuate, with inflated centre and refloxed
obtuse apices. ERBA. 1840, p. 15, & M.
pi. 15 B. 3. f. 25. Asia and America.
I^ough Mourno deposit.

E. Forniirn (E.). — Valvos linear, with
inflated centre and ends. EA. p. 126,
& M. pi. 8. 4. f. 18. Australia and Ame-

OF TIDE EtTNOTIEiE.

763

ERBA. 1845, p. 77, & M. pi. 83. 12. f. 13.
Fossil. Oregon.

E. Sima (E.). — Valves lineai-, slightly
ciirved, with rather concave venter ;
doi-sum suddenly sloping dowa to the
produced, acute, reflexed apices. ER
BA. 1845, p. 77, & M. pi. 33. 12. f. 16.
Fossil. Oregon.

E. biceps (E.). — Valves lineai', curved,
with dilated, slightly revolute, broadly
rounded ends. EA. p. 125, & M. pi. 5.2.
f. 36. Europe and America. Some at
least of Ehi'enberg's figiu'es in the ' Mi-
crogeologie' belong to Syneclrajlexuosa.

E. Alpina (K.) = Himantidium Hal-
cj/melke (Pevty). — Valves with turgid
convex dorsiun, slightly produced sub-
ti'uncate apices, and very fine ti'ansverse
striae. KB. p. 36, t. 3. f. 10. Switzer-
land.

E. ineisa (Greg.). — Valves arcuate,
slender, with obtuse or subacute apices,
and subterminal notches or depressions
on the ventral margin ; strias fine, 44 in
•001". Greg MJ. vol. ii. p. 96, pi. 4.
f. 4. Lapland, Scotland.

E. Plectrum, EM. pi. 6. 2. f. 15.
Fossil. Sweden. Valve semilunate, con-
stricted beneath the capitate apices ;
venter straight ; dorsum evenly convex.

E. Hemicyclus (E.^. — Small; valves
linear, curved, semicircidar, with obtuse
apices and distinct transverse striae. =
Si/nedra Hemicijclus, ERBA. 1840, &
M. t. 16. = E. Falx, Greg MT. vol. ii.
p. 105 ; MJ. vol. iii. pi. 4. f. 1. FossU.
Sweden,

2 * Valves with two dorsal and three
ventral undulations.

E. Crocodihis (E.). — Valves elongated,
slightly curved, with two dorsal and
three ventral undulations; apices pro-
duced, subacute, reflexed. ERBA. 1845,
p. 77 ; M. pi. 34. 5 a. f. 4. Afiica and
America.

E. Tapacumae, EM, pi. 34. 5 a. f. 5.
America. Valve with two dorsal and
three ventral undulations separated by
deep sinuses; apices abniptly produced
into a short bealf. E. Tapacumae seems
to differ from E. Crocodikts in its stouter
form, deeper sinuses, and more abruptly
produced apices.

3 * Valves with dentate or crenato
dorsum.

E. C'amclua (E.). — Valves striated,
small; dorsum with two apprnxiniato
rounded elevations, sloping to the atte-
nuated, produced, obtuse apices. EA.

p. 125, t. 2. 1. f. 1, Asia, Afi-ica, and
America.

E. bidentula (S.). — Valves faintly stri-
ated, with two prominent, acute or
rounded dorsal ridges, very straight
ventral margin, and obtuse, produced
apices. SBD. vol. ii. p. 83. E. Camelus,
Grev ANH. 2nd series, vol. xv. pi. 9. f. 1,
Britain. Differs from E. Camelus in its
straight venti-al margin.

E. Sella (E.). — Valve dilated ; ventral
margin straight; dorsum with two central
ridges, from which it passes with a re-
gulai' convexity to the acute apices.
EA. p. 126, t. 2. 1. f. 7. America.

E. Zygodon (E.). — Valves linear ; dor-
sum with two approximate ridges, from
which it passes bj a cm-vatiu-e to the
rounded apices. EA. p. 127, t. 2. 1. f. 6.
America.

~Ei. declivis (E.). — Valves with plane
venter ; dorsum convex, with two ndges
which slope to the acute apices. EA,
p. 125, t. 2. 1. f. 3. America.

E. itnp-essa, EM. pi. 2. 2. f. 30, &c.
America. Small, stnated; valves nar-
row, linear, with two slight dorsal im-
didations and obtuse ends. Perhaps a
bicrenate state of E. tridentida.

E. bactriana, EM. pi. 16. 1. figs. 29,
30, & pi. 16. 2. f. 19. TossU. Sweden.
This seems a distinct species, with linear,
nearly straight valves, and two remote,
minute dorsal teeth.

E. diodon (E.). — Valves stout, with
two rounded dorsal lidges and broadly
rounded ends; striae distinct, radiant.
E Inf. p. 192, t. 21. £ 23; SBD. pi. 2.
f. 17. Recent and fossil. Em-ope, Asia,
Africa, and America. — This and the thir-
teen following species of Ehreuberg we
regard as mere vaiieties, which difl'cr only
in the number of their dorsal elevations.
The species may be called E. robusta :
its valves are stout, semilimate, with
concave venter, broadly rounded ends,
turgid convex dorsimi furnished with
conspicuous, roimded, diverging ridges,
and the striae ai-e strongly marked and
highly radiant ; as, however, the valves
increase in length, according to the in-
creased number of dorsal ridges each ia
comparatively more slender than its pre-
decessor, and the ridges ai-e smaller and
resemble crenations.

E. triodon (E.). — Has three dorsal
ridges; otherwise resembles E. diodon
Eluf p.192; SBD. pi. 2. f. 18. Recent
nud fossil. Europe, Asia, Africa, and
America, (iv. 4; ix. 164.)

E. tctraodon, E., Sm., K., Rnb. ; E
pcntodon, E., K. ; E. Diadcma (0 crc-

'64

SYSTEMATIC HISTOHY OP TITE DTFUSOHIA.

nations), E., K., Sm. ; E. heptodon,
E., K. J JE. octodun, E., K. ; JE. cnnaodon,
E., K. 5 E. decaodon, E., K. ; E. hen-
decaodon, E., K. ; E. dodecaodon, E., K. ;
E. serndata (13 crenations), E., K. ; E.
prionotis (14 crenations), E,, K. ; E.
polyodon (all forms with more than 20
crenations), E., K. Fossil and recent.
Europe and America. — Br^b., Rab., and
Kiitz. place E, tetraodon in Himanti-
dium because the frustides are occa-
sionally united into short tablets. We
are unable to concm' with them.

F^.Elephas(F..). — ^Valves stout, cui-ved,
with three dorsal teeth and broadly
rounded ends. EA. p. 126, 1. 1. 4. f. 5.
Brazil.

E. dizyga (E.). — Valves stiiated (?),
semilunate ; dorsum with four teeth, ap-
proximate at the middle. EA. p. 126,
t. 2. 1. f. 8. Cayenne.

E. Corona (Rab.). — ^Valves nearly as
broad as long; ; dorsimi tm'gid, with five
ridges ; venter shorter, and separated
from dorsmn by a constriction. Rab
Diat. p. 17, 1. 1. f. 36. Italy. Strife di-
stinct, radiant,

E. tridenttda (E.). — Small ; valves
finely striated, cm-ved, naiTOw-linear,
with three slight dorsal crenations, and
obtuse reciu-ved apices. EA. p. 126,
t. 2. 1. f. 14 ; Grev Annals, 2nd series,
XV. pi. 9. f. 2. Eiu'ope, Asia, Afi'ica,
and America. — We would imite this with
the foUowing thirteen species imder the
name of E. Ehrenbergii. The valves are
linear, cui'ved, with small dorsal teeth
or crenations, and become larger and
longer in proportion to the number of
their teeth. The striae are less radiant
than in E. robiista, and the dorsum less
turgid.

E. quaternaria, EA. ; E. quinaria
(xu. 39), EA. ; E. senaria, E. septeiia,
EA. = E. septmaria, EM. ; E. octonaria,
E. nonaiia, E. dmaria, E. widttuiria, E.
TeiTa (12 crenations), E. tridenaria,
E. qualtiordmaria, E. quindenaria, E.
bioctonaria. Recent and fossil. Eu-
rope, Asia, Afiica, and America. Ehr.,
Kiitz.

E. sccdaris (E., K.). — Dorsum with 17
dorsal teeth. EM. pi. 17. 1. f. 44. Fossil.
Finland, In this and the two following
species Ehrenberg probably included
forms belonging to E. robusta and E.
Ehrmbcrgii.

E. icosodon (E., K.). — Valves striated,
linear, curved, with 20 dorsal teetli.
ERRA. 1845, p. 77 ; Microg. pi. 33. 10.
f. 3. Fossil, America.

E. polyodon (E.) resembles E. icoso-

don, but has more than 20 dorsal teeth.
E. I. c. p. 77} Microg. pi. 17. 1. f. 46.
Fossil. Finland.

Doubtful and insufficiently known Species.

E. triglyphis (E.) = E. triodon, Ralfe,
Annals, vol. xiii. pi. 14, f, 3 ? Afiica and
America, Sussex ?

E. tetraglyphis (E.). Asia, Africa, and
America.

E. pentaglpphis, EM, pi, 16, 2, f, 22,
& pi, 17, 1. f 32, Europe, Asia, and
America, Valves minute, linear, with
five dorsal, approximate teeth, {tv. 3.)

E. hexaglyphis, EM. pi. 16. 1. f, 34,
& pi, 16, 2, f, 24, Em-ope and Asia.
Resembles E. pentaglyphis, but has six
dorsal teeth.

The above foi-ms ai-e probably only
varieties. They seem to differ from E.
Ehrenbergii in more minute size, obso-
lete or indistinct striae, and approximate
teeth.

E. Amphidia-anon (E.). — Valve qua-
di-angular, straight, transversely stiiated,
with constricted middle and emargiuate
ends. ERBA. 1845, p. 77; Microg.
t, 33, 12, f. 14, Fossil, Oregon.

E. brevicornis (E.). — Oblong, dilated
with suddenly acutely rosti-ate ends ;
venter slightly concave at the middle ;
dorsum slightly convex, nearly smooth
(veiy finely striated.?). ERBA. 1845,
p. 363. Marine. Jsiii&. = A. Nitzschia?

E. Cret<B (E.). — Valves striated, nai'-
row-lanceolate, acute, very gi-adually at-
tenuated at each end. ERBA. 1844,
p. 81 ; EM. pi. 22. f 55, 56. Cocconema
Cretce, E. Fossil. Sicily,

E, Pileus (E,). — Small, stiiated, sub-
quadrate ; venter wider than dorsum,
the latter slightly fuiTowed ; ends ob-
tuse, rather prolonged, EM. pi. 39. 3.
f. 42. Siberia, Afiica, and America.

E. Gangetica, EM. pi. 35 a. 9. f. 2.
India. Fragments lai^e, striated, with
straight venter, convex doi-smn, and
broadly tinmcato apices, which are
sli^itly produced doi-sallv-

E Amtralis ; E. c<sluia ; E. Cygnus ;
E, Paradoxa ; E. serpentina, Australia,
Ehr. ; E.Phrygia; E.kpida; E.Mosis:
E. rostrata ; E. UraJensis : E. apiculata ;
E. Sibcrica ; E. borealis ; E. Lcptostoma :
E. umbih'cata, Asia, Ehr, ; E. siibtdis ;
E, curva : E. carinata, Mnoa, Ehr. ; E.
Araucanice; E. cdulis, America, Ehr.;
E. Jamtarii, Brazil, Ehr. ; E. Guianmsis;
E. Di mrrarrt': E. Ponwrom; E. Savami<r:
E. synrdrn, (iuiana, Ehr. ; E. Columbi,
Columbia, Ehr,

OF THE ETTNOTrEiE.

765

Genus AMPHICA.MPA (E.).— Frustulcs in lateral view Innately curved,
having pervious transverse stria) and denticulated margins. Ampliicampa is
closely allied to Eunotia and Himantidium, but differs in having teeth on
both margins.

Amphicasipa mirahilis (E.).— Valvea EM. pi. 33. 7. f. 2. = A. Eruca, EM.
linear, with rounded ends ; dorsum mth pi. 33. 7. f. 1. Mexico, (jv, 5.)
six or seven teeth, and venter with five.

Genus HIMAN'TrDIUM (E.).— Fmstules united into filaments or tables ;
lateral view arcuate or lunate, transversely striated. If all the species in
Himantidium formed ribbon-like filaments, there would be no difiiciilty in
distinguishing it from Eunotia ; but this is not the case, and Kiitzioig has
weU said, " It must be noticed that in many species of Himantidium the
individuals are not always united into a band, and therefore the generic
character is veiy variable and stands on a weak foundation." Professor
Smith obseiwes that " there is no mark to distinguish the valves of the two
genera unless it be in the character of the stria3, which in Eunotia are
radiate and in Himantidium parallel." If the striae were indeed always
radiate in the one genus and parallel in the other, a valuable diagnostic
mark would be furnished; but, unfortimately, the convergent striae occur
only in those species of Eunotia which have a strongly convex upper margin.
In the front view Himantidium resembles the EragUarieae, but in that family
the lateral view is not arcuate.

* Dorsum simple.

Htmantidium pectinale (DUlwyn, K.).
— Friistules imited in long filaments;
valves linear, arcuate, with flattened
dorsum suddenly sloping to the obtuse
apices, and slightly concave venter ;
sti-iaj 27 in •001". EJ3. t. 16; SBD.
p. 12, pi. 32. f. 280. = H. minus, KB.
p. 39, t. 16. f. 10 ; H. stricium, Eab
Diat. t. 1. f. 1 C ; Fragilaria pectinalis,
Lyngb. ; Fragilaria grandis, E Inf. in
part ; Eunotia depressa, EA. p. 126.
Eui'ope, Asia, Africa, and America.

H. Soleirolii (K.). — Valves lunate, with
evenly convex dorsum, concave venter,
and rovmded ends; striaj 30 in -001".
KB. p. 39, t. 16. f. 9 ; SBD. vol. ii. p.
13, pi. .3.3. f. 282. = Himantidium Fdba,
EM. t. 1. 2. f. 3 ; Eunotia Faba, E. in
part F Europe and Africa, (xxv. 13.)
It might have been preferable to have
adopted Ehrenberg's name for this spe-
cies, since it is evident that the H.
Soleirolii of Kiitzing was intended to
include all forms with internal siliceous
cells, and his figures of the valves belong
to another species.

H. paralldum (E.). — Valves lineai',
strongly striated, cm-ved, with simply
rounded ends. EM. pi. 14. f. 58. = Eu-
notia parallela, EA. p. 126. Eiu-opo,
Asm, Africa, and America.

H. monodon (E.). — Frustules large.

few together ; valves arcuate, with some-
what gibbous dorsiun, and obtuse, slightly
produced apices ; striae 34 in -001". EA.
p. 129, t. 4. = Eunotia monodon, EM,
many figm-es. SBD. vol. i. pi. 2. f. 16.
Common. Em'ope, Asia, Australia, A&ica,
and America, (xv. 16, 17.)

H. prceruptum (E.). — Valves striated,
elongated ; dorsum very convex, with a
notch-Uke depression near the dilated
trimcated apices. = Eunotia prcerupta,
EA. p. 126, & M, several figures. Asia,
Austi-alia, and America. According
to Ehrenberg's figiu-es, its valves scarcely
differ from those of H. monodon,
except by their more tiimcate apices,
and can scarcely be placed in another
genus.

'cus(E ). — Valves linear, arcuate ;
dorsum sinuated towards the rounded
dilated apices. EllBA. 1840, p. 17, &
M, many figxxvoa. = Eunotia Arai-s, EM.
Europe, Asia, Australia, Africa, and
America. /3, oxti-emities gradually taper-
ing, — J£. attenuatum, Rab Diat. n. 19.
t.l. £10. Germany. ^ '

H. pracilc (!].).— Volvos slender, nar-
row-lmear, slightly arcuate, ^^^th obtuse,
somewhat recurved extremities. E\
]3. 129, t. 2 ; SBD. vol. ii. p. 14, pi. .33!
t. 285. = Eunotia uncinata, EA. p 1''6
& M. pi. 15 B. f 23. Europe, Asia^
Austraba, Africa, and America. Habit
of //. Argus, but more slender, E. Stria)
27 in •001", S.

766

SYSTEMATIC mSTOIlT OF THE INFDSOlllA.

H. majm (S.). — Valves linear, arcuate,
with roimded, subcapitato extremities :
sti-i£G 27 iu -001". SBD. vol. ii. p. 14^
pi. 3.3. f. 286. Britain. Difiers little
from n. gracile, save in its greater size
and elevated dorsum, and is probably a
sporangia! form of it or some other
species, S. It scarcely differs from some
of Ehrenberg's figiu-es of S. parallelu7n,
except in its more inflated ends.

H. exigtium (BrtSb.). — Valves slender,
narrow-linear, arcuate, with obtuse re-
cm'ved extremities, and 42 very delicate
striaB in -001". KSA. p. 8. Eunotia
gracilis, SBD. vol. i. p. 16, pi. 30. f. 249.
Europe.

H. Veneris (K.). — Valves smooth,
plano-convex, with acute apices. KB.
p. 39, t. 30. f. 7. Eunotia Icevis, EM.
pi. 39. 3. f. 41. Trinidad.

2 * Valves with crenate or toothed
dorsum.

H. hidens (E.). — ^Valves with plane or
slightly concave venter, biundulated
dorsum, and dilated, truncate apices.
EA. p. 9, & M, several figm-es. = Eu-
notia bidens, EA. p. 125, & M. pi. 2. 1.
f. 2 ; Eunotia bigibba, KSA. p. 6? Eu-
rope, Asia, and America. The dorsum
has a notch-like depression near each
end.

H. Guianense (E.). — ^Valves dilated at
the middle, with two dorsal imdulations,
and tapering, slightly reflexed ends.
EA. p. 129, t. 2. 1. f. 4. Cayenne,
(xn. 54.)

H. Papilio (E.). — ^Valves subquadi'ate,
with a much dilated bicrenate dorsum,
constricted near the obtuse apices. EA.
p. 129, t. 2. 1. f. 2. Asia and America,
(xn. 45, 49-52.)

H. U7idulatum (S.). — Valves linear,
with gibbous venter, three or more
slight dorsal imdulations, and obtuse,
somewhat recurved apices. SBD. vol.
ii. p. 12, pi. 33. f. 281. Europe. Distin-
guished from the other British species
by its gibbous venter.

H. dentimlatum (Brdb.).— -Valves very-
narrow, arcuate, with denticulated dor-
sum and slightly recurved apices.
KSA, p. 10. France. Dorsum mai--

gined with minute teeth, constricted
near the rounded apices.

II. triodoH (Perty). — Valves smooth,
with concave venter, convex triundu-
lated dorsum, and broadly rounded ends.
Perty, Lif. p. 198, t. 17. f. 5. Switzer-
land. Very lilte Eunotia diodon ; but
strife have never been observed. Frus-
tules mostly cleai' as crystal. Perty.

II. ternarium, EM. pi. 34. 6 a. f. 5.
Florida. Valves arcuate, with slightly
concave venter, three dorsal undulations,
and obtuse apices.

H. qtiaternariwn (E.). — Valves nar-
row, very finely striated ; dorsum a little
convex, deeply fom'-toothed ; venter
slightly concave, with attenuated and
recurved apices. ERBA. 1852, p. 235.
California. Joints of the chain 4 to 7,
three times as broad as long, E.

II. quinariimi (E.). — Valves as in H.
quaternarium, but with five dorsal teeth.
E. I. c. p. 535. California, Asia, and
Africa. Joints of the chain 14, five times
as broad as long. The fr'ustules of IT.
quaternai-iimi and S. quinarium are very
similar to those of Eunotia quaternaria
and E. quinaria, but are distinguished
by fonning chains and by the attenuated
ends of the valves, E.

Doubtful Species.

H. carinatum, EM. pi. 34. 6 a. f. 6.
Florida. Frustules rectangular, smooth,
with a transverse median band.

H. ? mariiium (S.). — Filaments tena-
cious ; valves costate, slightly and regu-
larly arcuate, with acute apices ; costas
10 in -001". S Annals, Jan. 1857, p. 10,
pi. 2. f. 14. Marine. France. Distin-
guished by its maiine habitat and costate
valves.

Species knoton to i/s only by name :
probably several of them arc merely
concatenated states of Eunotia and
Epithemia.

H. Australia, E., Austi-alia ; S. Ca-
melus, E., Asia ; H. Textricula, E., Asia ;
H.Zebra,'E., Asia; H. ventralc, E.,Asia;
H. amphioxys, E., Asia ; //. nmbilicatum,
E., ±\sm ; H. JEthiopicum, E., *\sia ; JL
Falklandii, E., FaUdand Islands.

FAMILY II.— MERIDIEiE.

Frustiilos prismatic, attenuated at the base, attaclied, at least when young,
to a gelatinous cusliion ; in front view cimeate, in lateral vieAV clavate or
obovatc, with peiwious transverse costaa or stria;. Kiitzing places the Meridica3
between the Eunotieas and Fragilariesc ; and Mcnegliini would unite them

OF THE MEKIDIEiE,

767

with the latter, for lio " does not consider tho cuneate form of the frastules
of any vahic in an organological point of view," because of the occasional
occurrences of such frastules in Diatoma and other genera of the jFragilarieae.
In the latter family, however, the cuneate frastules, when present, are in
general interposed between those of the normal shape, and the lateral siu-faces
have not dissimilar extremities. Klitzing observes that " tho forms of this
family have very great similarity to those of Gomphonema, with which they
may be the more easily confounded when the individuals occur singly ; but
they are essentially distinguished from that genus by not having a central
nodule in the secondary sides, and by their uninterrupted transverse striae.
Moreover, this family is much more closely united to the genus Odontidium,
from which it is distinguished solely by the form of the secondary sides,
which are not symmetrical at both ends." We, however, consider its affinity
with the Licmophoreae stLU more evident. The Meridiese, Licmophoreas, and
Gomphonemeas " form a group [the Styllariese of Agardh] distinguished by
the triangular form of the frustiiles, which have their smaller ends dii-ected
towards a common centre. The frastules in this group have a central and
two lateral portions, as in Diatoma and Fragilaria, in which genera cuneate
frastules are also occasionally met with. But in the Fragilarieae, when two
or more cuneate frustules are united, the alternate frastules have their
smaller ends in opposite directions, and hence their filaments are linear ;
whilst they are attached, if at all, only by the basal frastule. In this group,
on the contrary, as the smaller ends are in the same dii-ection, they point to
a common centre, and when stipitate, each frustule is attached to the stipes "
(Ralfs). The frustules in the Meridieae have two puncta at the broader end,
and sometimes other two, but more obscure, at the smaller end ; they want,
however, the sutural or fracture-like longitudinal lines which (^ve present in
the Licmophoreae.

Genus MEEIDION (Leibl., Ag.). — Frastules cuneate, united in a spiral
filament ; transverse costae of lateral siu-faces pervious. " The species vary
according to the cii'cumstances of development, as well with respect to size
as to other relations. The individuals are met with both singly among other
Algae and also in masses. At times examples are found which are always
composed of only few individuals ; others again consist of individuals united
in greater number ; but generally the longer spiral ribands are rare." (Kiitz.)
Professor Kiitzing formed a new genus (Eumeridion) for the reception of
M. constrictum ; but his reasons have been considered inadmissible by De
Brebisson, Meneghini, and Smith. Meridion is remarkable for the frequent
occurrence within its frastules of an obovate silicious cell, wliich is usually,
but not invariably, divided into two symmetrical portions by a longitudinal
suture ; the lateral margins of the inner cell, as well as the sutiu-al line, are
crenulate like those of tho original frastule. The different aspect presented
by specimens in this condition has induced some observers to describe them
as a distinct species. Whilst we agree with Professor Smith that the modi-
fication is insufficient to warrant such a separation, we cannot coincide with
him in regarding it even as a variety, since frustules with these internal cells
are indiscriminately mixed with ordinaiy frastules in the same filament. So
common, indeed, is this occurrence, prior to tho termination of individual life,
that wo have long been convinced that it is tho normal mode of termination
m this genus.

= 31. vernale, E. ; M. Ziiickmi (with iu-
tonial cells), KB.; B. curvatiwi, K.
Frustules slightly arcuate. Commofi,

MERiniON circularc (Grov., Ag.). —
Frustules in lateral view clavato oi
obovate. SBD. vol. ii. p. 6, pi. 83. f. 277,

768

STSTEM-ATIC HISTORY OF THE rNFUSOSIA.

fonniug n mucous brown stratum on
leaves, stones, &c., in shallow waters.
/3, France, (ix. 177, 178; xiii. 21, 31.
Zinckeni.') In both the primary and in-
ternal cells the lateral margins have a
beaded appearance, produced by the
ends of the lateral costte.

M. constrictum (Ralfs). — Lateral valves
constricted beneath the apex, otherwise
as in ilf, circulare, SBD. vol. ii. pi. 32.
f. 278. = Eumeridion constrictum, KSA.
p. 11, Common. Europe. Internal cells
as in 31. circulare. We have received
very perfect specimens from Mr. Okeden,
gathered in Wales.

Doubtful %)ecies.
M. ? pmiduriforme (E.). — Lateral
valves constricted near the ends, the

capitate extremity acuminated. E Infus.
pi. 10. f. 3. 1-4,30". Form tliat of Gom-
plionenia acuminatum.

M. ? ovatum (Ag.). — Frustules ovate,
combined into a cellulose lamina. KSA.
p. 10. Sweden.

M. P coccocampyla, EM. pi. 14. f. 79.
Berlin. Perhaps a bad figure of one of
the preceding species ^vith internal
cells.

M. mai-iman (Greg.). — Front view
sublinear, with coai'se marginal puncta ;
valves clavate, -with IG coarse marginal
stinse in -OOl", and a blank longitudinal
median line. Greg D Clyde, p. 25, pi. 2.
f. 41. Marine. Scotland. Frustules
two to four together. Certainly not a
true species of this genus, as its costaj
are not pendous.

Gemis ONCOSPHEKIA (E.). — Erustules quadrangular, cimeate, not con-
catenate ; valves without an umbilicus, and also destitute of lateral apeitiu-es ;
and internal septa equal, but their apices unequal on account of thcii- cuneate
and uncinate form. Oncospbenia^ approach nearest to Podospheniae by the
absence of pedicels in the latter, but are peculiar in their uncinate fonn.
We are unacquainted with this genus, and ignorant of the reasons which
induced Professor Kiitzing to place it among the Meridiese.

Oncosphenia Ca7-pathica (E.). — La- nules 11. Probably a distorted state

teral valves cuneate, laxly striated ; one of some other species similar to the

end tm'gid, roimded, straight, the other vai'iety of Diatoma eloiit/atmn figured by

attenuated and imcinate. KSA. p. 11. Professor Smith in BU. pi. 60. f. 311.
Cai-pathian Moimtains. 1-792" : pin-

FAMILY III.— LTCMOPHOREJE.

Frustules cuneate, longitudinally bivittate, attached or stipitate, solitary
or united in a fan-like manner ; lateral siu-faces striated or smooth, but not
costate. The frustules in the front view are cuneate, and have, like the
generality of the DiatomaceaD, two puncta at each end, the upper ones, how-
ever, being most conspicuous. Most frequently two longitudinal suture-like
Unes, corresponding to the puncta, are more strongly mai-ked in the Licmo-
phoresG than in most other families ; these Kiitzing calls " vittffi," and has
formed a tribe which from them he calls "Diatomete \ittata3." The vittaj,
however, are not peculiar to this tribe ; for, as Meneghini justly remarks,
" they are merely the same longitudinal lines which run along the primary
surfaces of almost all the Diatomaceaj" (MeD. p. 4G2). Professor Smith
describes them as " modifications in the outline of the valve, whicli in Podo-
sphenia is slightly inflected at its larger extremity, causing, on a front riew,
the appearance of notches at the spot where the valves miitc with the con-
necting membrane (central portion) and the foramina exist. Tlie apparent
prolongation of tliis notch to the lower extremity of the frustule is notliing
more than tho valvular suture which is seen in all the Diatomaceaj " (SBD.
vol. i. p. 82).

The cuneate shape of the frustules in the front view, and the dissmnlar
ends of the lateral surfaces, distinguish the Licmophorcaj from Syncdra, tlio
specica of which often resemble them in habit.

OF THE LICM0PH0KE.T5.

769

Genus PODOSPHENIA (E.).— Frastiiles affixed, in front view cimeatc,
in lateral view clavatc, stipes none or obsolete. PodosiAenia is identical with
StyUaria (Ag.). Its sessile fr-ustules distingTiish it from the rest of the
Licmophorete, and the absence of transverse costae from the MeridieJB. " This
genus represents in the LicmophoreaB the genus SpheneUa of the Gompho-
nemea) ; for, like that, it is distinguished from other genera of the same family
by the more or less complete absence of the stipes. The obovate-lanceolate
figure of the secondary surfaces is precisely that of the SpheneUiB and of the
Gomphonemeas in general. The cuneate form of the primary surfaces is, in
Podosphenia, always more dilated at the summit and acute at the base, so
that they resemble a triangle more than a trapezium." (M I. c. p. 462.)

Podosphenia (7rac27is(E.). — Fmstules
narrow cuneate, elongated, with some-
what acute base; lateral view clavate,
smooth or with very obscure striaB. KB.
t. 9. f. 10. 1. Em-ope. (x. 186.) /3. minor
1-250" to 1-110".

P. tettuis (K.). — Linear cuneate, elon-
gated, very slender, with acute base ;
lateral view naiTow-clavate. KB. t. 30.
f. 51. Norway.

P. nana (E.). — Small, smooth, naiTOw
linear cuneate; lateral view clavate with-
out Imes. EM. pl. 11. f. 18, 19. Fossil.
Bilin, Bohemia. 1-2-300" to 1-1720".

P. dehilis (K.). — Smooth, naiTowly
cuneate, rather acute at the base, sub-
flabeUate. KB. t. 8. f. 7. Em-ope.
1-1.380".

P. tergestina (K.). — Cimeate tiian-
gular, geminate or temate, conjoiaed in
a fiabellate manner, base rather acute.
ItB. t. 8. f. 13. Trieste. 1-1440".

P. hyalina (K.). — Very hyaline, cu-
neate, with approximate vittas and sub-
acute base; lateral view obovate pyri-
form. liB. 1. 10. f. 2. 0. racemosa, K.,
obsoletely stipitate, 1. 10. f. 3. Em-ope.
1-570" to 1-480".

P. cimeata (Lyngb., Ag.). — Broadly
cuneate with rather acute base; lateral
view clavate or obovate, with obscm-e
strise. =8tyllaria cimeata, Ag. ; Poclosphe-

Genus EHIPIDOPHOEA (K.). — Prustulos stipitate, in front view cuneate,
in lateral view obovato-lanceolate ("Avith a mcchan longitudinal Unc," S.).
" We encounter the same difficulty in distinguishing llhipidophora from
Podosphenia that is experienced when practically applying the generic
distinction established between SpheneUa and Gomphoncma and in all other
similar cases (C'ymbolla and Cocconcma, &c.) ; these difier only in the stipes,
which is very variable in length and not always entirely waJiting in the tii-st
of these two genera.

" The large size of some among the species enumerated by Kiitzing permits
us to observe clearly the conformation of the shield. Lot us suppose a
cylindrical articulation of. Melcsira, and so compress it unequally on one of
its sides, and in the direction of both pairs of opposite surfaces, that the
resulting form shall be cuneate, and the two incomplete diaphragms formed
by the internal prominence of the longitiulinal canals shall extend like these

3 D

nia abhreviata, E. ; P. Lim/hjei, SBD,
Eui-ope. (xin. 13 b.) 1-240". Strise 46
in -001", S. Broader and shorter than
P. f/racilis.

P. Jurgemii (Ag., K.). — Broadly cu-
neate vdth. ti-uncate base; lateral view
clavate, with obscm-e striae. SBD. i.
p. 83, pl. 25. f. 228. Em-ope. 1-432".
StriiB 48 in -001", S.

P. ovata (S.). — Cuneate with rounded
angles ; lateral view obovate, tapering
into an acute base; strise moniliform.
SBD. i. p. 83, pl. 24. f. 226. Shoreham
harbour. Striaj 24 in -001". -0033" to
•0042", S.

P. llhrenhergii (K..'). — Large, broadly
cuneate; lateral view tapering at both
ends and with distinct moniliform trans-
verse striae. SBD. pl. 24. f. 225. Eu-
rope, (w. 7 ; xin. 14.) 1-140". Strife
27 in -001", S.

Doubtful Species.
P. Pupula, EM. Several figm-es. Ehr-
enberg's figm-es have a clavate lateral
valve with pei-vious ti-ansverse costre and
Avith or without a consti-iction. All pro-
bably belong to Meridion circidnre and
M. constrictum. He gives about twenty
stations for this species in ditierent parts
of the globe, — ^none marine.*

770

SYSTEMATIC HISTORY OF TDK INFUSOKIA.

and lose themselves towards the pointed extremity which forms the base •
such is the stnictiu'e of Podosphcnia and Rhipidophora. Viewed on one
side, that is, on the lateral surfaces, they present an obovate arch, marked
on the periphery of the surfaces themselves. The margin of this arch is
thickened by the presence of the canal, which, seen in front, presents in the
cm-ve its biightness ^ndth an appearance of perforation." (Meneg I.e. p. 463.)
Professor Smith says that " a close examination of the fiiLstules shows us
that the distinct and even moniliform striae so conspicuous in Podosphenia
are almost wholly wanting in our native species of Ehipidophora." The
strife in the former genus, however, are not always detected vrith facility,
since Meneghini remarks that " of the nine species described and figured by
Kiitzing, only one (P. Ehrenhergii) presents transverse striae on the secondary
sm-faces." Careful observation of the species of Ehipidophora in a growing
state will probably prove that several of them have been constituted upon
insufficient grounds. It is to be feared, indeed, that characters taken from
the comparative length and stoutness of the stipes, its simple and branched
condition, and even the shorter or longer form of the wedge-shaped frustules
in the front view, are more or less fallacious. We believe that at least some
of the species are at first fiu-nished with a short, tliick, simple stipes, bearing
the associated frustules at its apex, and that by the process of growth the
frustules become longer in proportion to their breadth, and lose their flabel-
late aiTangement by the subsequent elongation and dichotomous division of
the stipes.

E,. Dalmatiea (K.). — Flabellate in a
radiating mamier; ft-ustules obloug eu-
neate ; stipes short, rather stout, at length
subramose, tubular. KB. t. 9. f. 7.
Europe. 1-540". Lateral ^dew nan'ow-
clavate with very obscm-e striae.

E. abhreviata (Ag., K.). — Subflabel-
late ; finistules broadly cuneate with acute
base ; stipes rather thick, at length
branched. KB. t. 9. f. 1-t = Licmophora
abhreviata, Ag. Eiu'ope. 1-540". " Ee-
sembles It. paradoxa, but is distinguished
by its gi-een colom" when dried." (Ag.)

E. j)aradoxa (Lyugb., K.). — Frustules
short ; broadly cuneate, somewhat acute
at the base ; stipes slender, filiform, di-
chotomous ; lateral ^dew elavate. SBD.
i. p. 84, pi. 25. f. 231 = Gomphoncma
pqi-adoxiim, Ag. 1-540" to 1-480". Co-
lom-ing matter didl ohve. The frustiile,
especially in dried specimens, often has
its angles so much rounded <is to become
obovate, — a cliaracter, however, not
peculiar to this species, (iv. 8.)

E. tiiicta (Ag.). — Fi'ustides elongated,
naiTOw cuneate, vnth. somewhat acute
base ; stipes elongated, subdichotomous,
slender. = Gom. tindum, A Consp D.
p. 35 ; R. clonfiata, KB. t. 10. f. 6.
1-310". ColourinfT matter didl olive.
According to Agnrdli, it differs fi'oni R.
}mradoxn in it^s greener colour and longer
and more slender frustules. He also
states that it resembles smaller states
of Licmophora fl<ihi'Uata. but is shorter

Ehipidophoea crystallina (K.). —
Shortly stalked, flabellate ; frustides
shortly cimeate, rather broad, obtuse at
the base. KB. t. 9. f. 10. 5. German
Sea. 1-1200" to 1-1300"

E. CEdipus(K.). — Very shortly stalked,
subflabellate ; finstules oblong cimeate,
truncate at the base; stipes hemisphe-
rical. KB. t. 18. f. 5. 5, 7. Europe.
1-600" to 1-480".

E. Anglica (K.). — Shortly stalked,
flabeUate ; fi-ustules turgid, cimeate with
truncate base and obtuse tenninal angles ;
stipes rather long, simple, thick. KB.
t. 27. f. 5. 2, 4. Eiu-ope. 1-600".

E. Australis (K.). — Flabellate; frus-
tides naiTowly cuneate with truncate
base ; stipes simple, thick. KB. t. 9.
f. 5. Trieste. 1-540".

E. horealis (K.). — Flabellate ; frus-
tules large, oblong cimeate with slightly
obtuse base ; stipes simple, rather stout.
KB. t. 9. f. 6. Heligoland. 1-310".

E. Niibecida (K.). — Frustules hyaline,
broadly cuneate, somewhat acute at the
baae, scattered, subsolitai-y or fasciculate,
lateral and terminal ; stipes filifomi,
elongated, subramose. KB. t. 8. f. 16.
Europe, (xiii. 17.) 1-720" to 1-600".

E. tcnella (K.). — Minute ; frustules
smaU, broadlv cuneate, conjoined in an
imperfectly uabeUate niamicr, acute at
the base ; stipes slender, very finely
branched. IU3. t. 11. f. 3. Europe.
(xiii. 15.) 1-1080" to 1-9G0".

OF THE LICJlOPnOllEiE.

771

and more lax, and without radiant frus-
tules.

K. ocennica (K.). — Fnistules oblong
cuneate, dense ; stipes elongated, slender,
subdichotomous. IvB. t. 10. f. 4. At-
lantic. i3 flabellate. 1-390". Internal
matter fulvous.

R. superba (K.). — Frustules geminate
or solitary, oblong cuneate, slightly acute
at their base ; stipes long, filifonn, di-
chotomous, secondary branches lateral,
.short. KB. t. 10. f. 7. Europe. 1-310".
Elegant, slender, large ; internal matter
golden-yellow, globose, broadly distri-
buted.

R. graiidis (K.)- — Frustides broadly
cimeate, large ; stipes very long, fili-
form, dichotomous. KB. 1. 11. f. 1. /3.
arachnoidea (K.). — Frustules caducous,

mostly lateral. Venice. Earge, its in-
! ternai matter granular, globose, olive.
1-120".

R. MeneffJiiniana (K.). — Large; frus-
tules geminate, oblong cuneate, with
rather broad apices ; stipes much elon-
gated, filiform, dichotomous. KB. t. 11.
f. 2. Venice, (xm. 19.) 1-288". In-
ternal matter scattered, globose, olive-
brown.

R. Craticula (INIont.).— Shortly stalked,
subflabeUate, dilated at the base, cra-
ticuliform ; frustules two to six, lanceo-
late or oblong-lanceolate, with trimcate
apex, and obtuse, scarcely attenuated
base. Montague, A d Sci Nat. 1850,
p. 308. Cayenne, 1-650" to 1-450".
iStipes slender.

Genus LICMOPHORA (A.). — Frustules flabelliform, stipitate, in front
view narrow-cuncate, laterally clavate ; stipes thick, iiTeguIarly branched.
Licmophora is nearly identical with EchineUa of Ekrenberg. " The frus-
tules of the present genus differ in no essential respect from those of Rhipi-
dophora. They are, it is true, longer and narrower, and probably less fii'mly
silicious ; but none of these circumstances seem to be of generic importance.
The separation of the genera must therefore rest upon the fan-like arrange-
ment of the frustules upon the summit of an incrassate and irregularly
dichotomous pedicel which occurs in Licmophora." (S I. c. vol. i. p. 85.)

Meneghini, however, says that " the resemblance of this to the preceding
genus is only apparent. But a true affinity connects Licmophora to Synedi'a,

from which it differs only in its cuneate frustules The vittaj in

Licmophora are not to be compared with those in Rhipidophora. They are
nothing more than the usual longitudinal canals projecting into the canty,
by which the apparent perforations or sections of theii- cavities appear very
near the margin of the summit. The distribution of the internal coloui'ed
substance is different from that in the two preceding genera, and greatly
resembles that of Synedi'a." (M I. c. p. 464.)

LiCMOPHOBA splendida (Grev.). —
"Frustules nearly linear, frequent^ at-
tenuate and rounded at the upper extre-
mity; in lateral view attenuate towards
the upper end." SB. i. p. 85, pi. 32.
t2SS. = L. JlabeUata, K. ; lichinclla splen-
dida, E. Eiu-ope. Differs from the next
species by its lono^er and naiTower frus-
tules, many of which are scattered and
lateral.

h. flabelkita (Grev., Ag.). — Frustides
cuneate, truncate; in lateral view very
narrow clavate. S. pi. 32. f. 233. =Z. ra-
diam, K. ; L. arf/mitencens, Ag. ; Echinclla
flabdlata, E. Common. (iv. 9. ; x.
191-193.)

" I have given, in accordance with the
authority of my predecessors, two spocica
of this genus ; 'but I am far from satisfied
that they are tmly distinct, and I am

disposed to believe that a wider com-
parison of specimens will necessitate
their union." (SB. i. p. 85.) Being imable
to deteniiine tlie synonyms of Agardh,
Ehrenberg,andKiitzing,we have thought
it better to foUow Professor Smith than
to risk increasing the confusion which
exists. The Licmophora arc/cutescens,
Ag., is remarkable for its silvery lustre
when dried ; but we caunot detect any
valid diagnostic difference. Both species
are remarkable for the large and Deau-
tiful fnn-like clusters of frustules termi-
nating their branches; other frustules
are lateral nnd scattered.

L. Mem'.ffkiniana (K.). — Frustules
slender, very long, linear cimeate, ter-
minal ones radiant, lateral ones scat-
tered ; stipes elongated, subdivided.
KSA. p. 113. Adriatic Sea. Length
3 1) 2

772

SYSTEMATIC IIISTOEY OV THE INFUSOETA.

of fnistule 1-84" to 1-72". The charac-
ters given are insufficient to distinguish
this species from L. splcndida.

L. divisa (K.). — Frustules elongate
cimeate, subsolitary or geminate (not

flabellate), acute at the base; stipes
short, weak, subdivided. KSA, p. 114.
Adriatic Sea. (xin. 10.) Length of
frustule 1-240" to 1-180".

Genus CLIMACOSPHENIA (Ehr.). — Frustules in front view cuneate,
with moniliform longitudinal vittse, laterally obovate-lanceolate, divided into
chambers by transverse septa. Marine. This genera resembles Podosphenia,
except in having the peculiar transverse septa. " The two (first) species
contained in this genus have nothing in common except the momlifoi-m vittiE.
But in what these really consist we cannot ascertain from the figures. In
the fii'st Kiitziug does not dcHneate the lateral surfaces, and fr-om the figure
any one would say that he had drawn a Synedra. The second, again,
resembles a Podosphenia." (Meneg Z. c. p. 465.)'

Cllmacosphenia Australis (K.). —
Very shortly stalked, with smooth mar-
gins. KB. t. 10. f. 8. On Alg£e. New
Holland and Southern Afi'ica.

C. moniligera (E.). — Frustules trans-
versely striated on the margin; septa
10 to 11 in number. KB. t. 29. f. 80.
Cuba, Mexico, (xi. 45, 46.)

C. elongata (B.). — Lateral view elon-
gated clavate, the intercostal sjjaces with
obsolete transverse strife ; stipes long,
branched. BO. 1853, p. 8, pi. 1. f. 10,
11. Florida. Professor Bailey relies

on the " elongated-clavate form of the
frustules and their excessively minute
striations, to distinguish this species
from those previously described by Ehr-
enberg and Kiitzing. The striae can be
made out without much difficulty near
the edges ; but to trace them completely
across the middle regions of the valve
requu'es excellent lenses and careful
management of the light." (BaUey.)
Frustules in fan-shaped groups, nari'ow,
linear-cuneate, with conspicuous moni-
liform longitudinal vittae.

Genus PODOCTSTIS (K. & BaU.)=EUPHTLLODIUM (Sh.).— Frustules
stipitate, cuneate in front view with obsciu-e vittte ; valves with transvei-se
costse, moniliform striae, and longitudinal median line. Podocystis differs
from Surirella not only in its stipitate frustules, but in its monilifonn strife
and absence of alas ; and from Rhaphoneis by its cuneate frustules. We
have placed it with the Licmophoreae because of its resemblance to Podo-
sphenia, notwithstanding its obscure vittae and strong transverse costiE.
Marine.

Podocystis Adriatica (K.). — ^Valves
ovate, with 11 or 12 striro in 1-1200",
stipes very short. = Surirella (Podocystis)
Adriatica, KB. p. 62, t. 7. f. 8 ; P. Ame-
ricana, BMO. pi. 11. f. 38 ; SD. ii. p. 101 :

EuphyUodiwn spathuMum, Shadb. MT.
ii. p. 11, pi. 4. f. 4; Doryphora? elcgans,
Roper, MJ. ii. p. 284. f.3." Europe, Afi-ica,
and Ajiierica. (rv. 10.)

Genus SCEPTRONELS (E.).— Frustules simple, affi.xed, cuneate, com-
pressed, styhform ; in the lateral view with monilifonn transverse striaj,
interrupted by a median longitudinal suture. Mtuine. Sceptroncis has the
habit of a nonconcatcnatc Meridion and of a Gomphonoma ■without the
central nodule of the lateral valves.

ScEPTnoNEis Caducms (E.). — Frus-
tules bacillar, long, shsnder, inflated at
contre and upper end, and tapering below.
BAJ. xlviii. pi. 4. f. 11. Fossil, Ama-
rica ; recent, fecotland. The lateral view,
the only one we have seen, is naiTow,
somewhat clavate, constricted beneath

the head, which is rounded at i<s apex.
Transvei-se stria) with pear-liko gra-
nules. Length 1-02", exceeding the
width about 18 times. Professor Gre-
govv gathered a fragment of this species
in Scotland, (iv. 11.)

OV THE FIUG1LA1UEJ3.

773

FAMILY IV.— FllAGILARlE^.

Frustulcs straiglit, free, or affixed by one angle of the busal frustulcs, in
front view linear, in latertil view compressed, and striated or smooth, with a
central nodule ; striae or costae ijervious. " The members of this family are
aUied in the genus Denticula to Suru-eUa and Navicula ; in the genera Odon-
tidium and Fragilaria to Himantichum, Diadesmis, and the Meridieae, and in
Diatoma to Grammatophora and Tabellaria." (Kiitzing.) " The character by
which these genera are collected together iato one family is the conformity of
the two primaiy sm-faces ; nor do I know how the genns Meridion is excluded
even by the minutest characters." Kiitzing, indeed, " cites the affinities with
Himantidium among Eunotieae, with Diadesmis among the Naviculae, and
with the various genera of Striatellese. The relation appears to us rather
one of analogy than of aflBjiity, being the polyparifonn association of many
individuals." (Meneghini.) Under MeridiesE we state the reasons which
induce us to dissent from Meneghini's opinion respecting the position of
Meridion. The striae and costte are usually continuous across the valve ; and,
indeed, Kiitzing makes their perviousness a distinctive character, separating
the Fragilaiieas from the Surirelleae. We regard Meridion as far more nearly
aUied to some genera belonging to the latter family than to the genera
mentioned by Meneghini.

Genus DENTICULA (K.). — Free, soHtary, or binately conjoined, rarely
more ; valves with pervious costae, which appear in front view Uke marginal
pimeta. Fresh water. Denticula differs from Odontidium in not forming a
filament, and also, according to Professor Smith, in having conspicuous strias,
which are wanting or obscure in Odontidium, and fi-om Fragilaria by its
strongly marked costae, which Kiitzing regards as always pervious.

elliptic, with 12 to 13 fine striae in
1-1200". Nfig. in KSA. p. 889. =
D. injlata, SBD. ii. p. 20, pi. 34. f. 294.
Em'ope.

D. acuta (Rab.). — Front view mostly
ciiAeate ; valves slender lanceolate, -nath
6 or 7 costae in 1-1200". Rab Diat.
p. 33, 1. 1. f. 8. Persia.

D. lauta (Bail.). — Front view lineai',
with gland-like marginal puncta ; valves
linear lanceolate, with obtuse ends and
distant costre, which terminate in mai--
ginal bead-like dots. BMO. p. 9, f. 1. 2.
Fossil. Suisun Bay, California.

D. ocellata (S.). — Front view linear,
truncate, with conspicuous foramina-
like marginal puncta ; valves linear
elliptic, vnih. 10 costre in -001". SBD
ii. p. 20. St. Abb's Head. The frus-
tules in the front view closely resemble
small specimens of BpitJicmia Arqus.
The extremities of tlie costae or can'ali-
cidi appear ns circidar foramina on the
f. v., and the costa3 on the side view
also give an ocellated appearance to
the vidve, S.

Denticula tenuis (K.). — Front view
linear -with pimctated margin ; valves
naiTow lanceolate, with 10 or 11 trans-
verse costae in 1-1200". KB. p. 43, 1. 17.
f. 8. Em-ope. 1-1080".

J).fri(/ida (K.). — Front view linear,
with finely striated margins; valves li-
near' lanceolate, ^vith 11 or 12 costis in
1-1200". KB. p. 43, 1. 17. f. 7. Em-ope.
Smaller than D. tenuis. 1-1200".

D. thermalis (K.). — ^Front view oblong
or ti-apezoid, with beautifully pmictated
margins ; valves lanceolate, with 7 or 8
costae in 1-1200". KB. p. 43, 1. 17. f. 6.
Italy. 1-660".

D. eleyans (K.). — Front view linear
oblong, vnth. obtuse angles and glnnd-
Uko marginal puncta ; valves lanceolate,
with 6 costae in 1-1200". 103. p. 43,
1. 17. f. 5. Germany. (lu. 4.) 1-660".

_D. ohtusa (K.). — Front view linear,
with striated margins ; valves lanceolate,
with obtuse ends, and 11 costae in
1-1200". KB. p. 43, 1. 17. f. 14; SBD.
1. p. 19, pi. .34. f. 292. Em-ope. 1-336".

D. crassula (Niigeli). — Front view
oblong, with punctated margins ; valves

Genus PLAGIOGIIAMMA (Grov.) (Hkterompuala, E.). — Frustulcs qua-
flrangidar, united into a short fascia ; valves with two or more strong, pcrAdoiis

774

SYSTEMATIC HISTOUY OF THE INl'USOEIA.

transverse costae, and moniliforin, generally interrupted striaj. Marine.
Plagiogramma is a well-marked genus, identical, we believe, Avith Heterom-
phala of Ehrenberg. "We have adopted the present name, notwithstanding
the prior claim of Ehrenberg's, because it is not only better defined, but the
latter was founded upon imperfect knowledge, when the lateral view, which
Ls so important, had not been observed. In the front view the terminal
puncta are very conspicuous and notch-like, so that the ends appear slightly
three-lobed, and the termination of the costJB and striae are conspicuous along
the lateral margins. The valves are always furnished -svitli two central
transverse costte, and frequently with others. In addition to the costte there
are moniliform striaj, — the former pervious, the latter, except in one species,
interrupted by a median line. We give Dr. GreviUe's arrangement of the
species, but must express a doubt whether the number of costae is not variable
in the same species.

* Valves with two centrical cost<s.

Plagiogramma Grefforiamim (Grev.).
— ^Fi'ont view with slightly convex mar-
gins ; valves lanceolate oblong, obtuse ;
costae two; striae peiTious, 18 in -001".
Grev. MJ. vii. p. 208, pi. 10. f. 1, 2. =
Denticula staiwopJiora, Greg Diat. of
Clyde, p. 24, pi. 2. f. 37. Scotland.

P. Jamaicense (Grev.). — Front view
with straight mai'gins ; striae continued
almost to the angles, 16 in -001" ; costae
two. Grev I. c. p. 208, pi. 10. f. 3. Ja-
maica. The striae can scarcely be termed
strictly monilifor-m, but rather monili-
form costas. Grev.

P. ? tessellatum (Grev.). — Valves
broadly lanceolate, obtuse; striae inter-
rupted, composed of large subquadrate
granules, 8 iu -001"; costae two. Grev
I. c. p. 208, 1. 10. f. 7. Californian guairo.

P. interruptum (Greg.). — Front view
with slightly convex margins ; costaj
two ; striae obsolete ? = Denticula inter-
rupta, Greg Diat. of Clyde, p. 22, pi. 2.
f. 30. Scotland. Side view unknown.

2 * Valves tvith two centrical costce and
one near each end.

P. ornatum (Greg.). — Front view with
convex margins, constricted beneath the
dilated ends ; costai four ; striae obsolete ?
= Denticida ornata, Greg Diat. of Clyde,
p. 22, pi. 2. f 32. Scotland. Side view
imlmown.

V.pulchelhmi (Grev.). — Valve linear
oblong; costae four; striae robust, con-
spicuously moniliform, interrupted, 11
in -OOl". Grev I. c. p. 209, pi. 10. f 4-6.
Call fornian guano ; Jamaica ; New Pro-
vidence.

P. inceqnale (Grev.). — Front view with
straight sides ; costao four, the terminal
ones in front view longer tlian the cen-
trical, and inflected at their apices ; striae

moniliform, 16 in -OOl". Grev I. c. p. 210,
pi. 10. f. 10. Jamaica and New Provi-
dence. Side view imlmown.

P. pi/fftn(Fum(Gve-v.). — Minute; valves
narrow oblong; costae four; stiias moni-
liform, intermpted, 21 in -001". Grev
I. c. p. 211, pi. 10. f 11. Distinguished
for its minute size, its shape, and the
small number of strife, althoug'h re-
latively closer. Grev.

P. Ch-evillii (Ralfs). — Striae in front
view broad, monilifonn, costate, 8 or 9
in -001"; costas four; connecting zone
with longitudinal rows of dots. =P. onia-
tmn, Grev I. c. p. 209, pi. 10. f 9. Cali-
fornian guano. Side view unknown.
The strife are very pecidiar, broad, at
first sight resembling costas. Grev.

P. validiim (Grev.). — Valve linear,
slightly dilated in the middle, rounded
at the ends; costae four; stii;ie mter-
rupted, conspicuouslv moniliform, 12 in
•001". Grev I. c. p. 209, pi. 10. f. 8. Cali-
fomian guano. Front view unknown.

P. ohesiim (Grev.). — Minute valves,
broadly dilated at the midtUe and roimded
at the ends ; costae four ; striae 11 in
•001". Grev /. c. p. 211, pi. 10. f. 12, 13.
New Providence. The inflated appear-
ance of the vah es and the small number
of strioB render this a well-marked spe-
cies, Grev.

P. h/ratum (Grev.). — Valves con-
stricted at the middle, then dilated and
narrowly lyriforni, linear, and roxuulod
at the extremities ; costa^ four : strijc 18
in -001". Grev I. c. p. 211, pi.' 10. f 14.
New Providence.

3 * Valves with more than four cost<P.

P. Californicum (Grev.). — Valves li-
near, with roundea ends ; costaj more
than fom-; stria; 18 in -001". Grev /. r.
p. 211, pi. 10. f. 15-17. Cflbfornian
guano.

OF THE FlUGILABIE-E.,

775

Doubtful or insufficiently hiotvn
Species.

P. kevis (Greg.). — Front view with
slightly but shai"ply dilated ends and a
minute prominence in the middle of each
margin ; costaa two?, sti'ias delicate, about
48 iu •Qbl". = Denticula Icsvis, Greg Diat.

of Clyde, p. 22, pi. 2. f. 33. Scotland.
Side view unknown.

P. Himantidium (E.). — Front view
eight times as long as broad, with the
rounded apices slightly 3-lobed, costse
two ?, margin striated. = Heteromphala
Hiniantidiunif'ER'BA.. 1858, p. 13. ^gean
Sea. Side view unknown.

Genus ODONTIDIUM (K.). — Fnisttiles united into a filament; lateral
view linear elliptic or cruciform, with, pervious costae. " The Odontidia ai'e
merely a filiform series of Denticulae." (Menegh.) Like Denticula, this genus
is distinguished from FragUaria by its strongly-marked costse, which appear
in the fi'ont view like marginal puncta. The filaments are usually extremely
fragile, and when broken up the frustules scarcely differ from those of
Denticula. Smith says, " It must be acknowledged that there is little to
separate these genera ; and I should be disposed to unite the two, were there
not in the general habit of the hving frustule characters which enable the

observer to assign them to their respective genera It may be left to

future observers to consider whether they may not without inconvenience be
united."

Odontidium mesodon (K.). — Has
shorter and subquadrate frustules, with
from two to four ti'ansverse costse. The
last character, however, is so inconstant
that, although Professor Smith adopted
it in his definition, almost every frustide
in his figm'es has a gi-eater nimiber. 0.
glaciale often has trapezoid frustules and
5 or 6 costee, whilst O. turc/idulum is in-
temiediate between those forms and the
noiinal fioistides in length and number
of costee.

0. hyemale (Lyngb., K.). — Front view
with bead-like marginal puncta ; valves
elliptic-oblong or elliptic-lanceolate, ob-
tuse, with conspicuous costae. KB. p. 44,
1. 17. f. 4; SBD. pi. 34. f. 289; Frayi-
laria hyemalis, Lyngb. t. 63 ; F. con-
fervoides, GBF. ii. p. 403 ; F. striata,
EA. p. 127; Odontidium turyidulum, KB.
t. 17. f. 2 ; F. turyidulum, E Inf. ; Odon-
tidium (jlacialc, ItB. ; 0. mesodon, KB.
t. 17. £ 3 ; SBD. ii. p. 16. Common.
Europe, Asia, Australia, and America,
(xiii. 24, 25.) Odontidium hyemale is
easily distinguished from other filamen-
tous Diatoms by its exceeding fragility,
minute tei-minal pimcta, gland-like mar-
ginal ones, and the conspicuous costa3 of
the valves. The fmstulos vary much
in length and in the number of their
costiB ; and several species have, we be-
lieve, eiToneously been constituted upon
these characters. Wo do not hesitate
to unite ihv.m, confinncd in our opinion
by ^ the doubts expressed respecting
their distinctness by the late Professor
Snnth.

0. Boyotanum (Rab.). — Very small ;
valves oblong, with rounded ends, and
fr'om 2 to 4 very broad transverse costiB.
Eab Diat. p. 34, t. 2. f. 8. Bogota. Ap-
parently a state of O. hyemale.

0. capitatum (Rab.). — Fom* to six
times as long as broad; valves lanceo-
late, constricted beneath the capitate
apices ; costte 6 or 7 in 1-1200". Rab
Diat. p. 34, 1. 10. f. 17. = 0. chamocepha-
lum, Rab D. p. 34, t. 10. f. 16 ; Fragi-
laria? cupitata, EB. 1853, p. 527; Microg.
pi. 35 A. 12. f. 2 ; F? leptocephala, E I c.
p. 527 ; Microg. pi. 35 a. 12. f. 3. Em-ope,
Persia, and Anierica.

0. nodulosum (E., K.). — Frustules
narrow linear, twelve times as long as
broad; valves nai-row linear, nodulose,
consti-icted beneath the capitate ends;
sti-ifB 18 in 1-200". KSA. p. 13. = F-a-
yilaria nodulosa, EB. 1844, p. 267. Km--
distan.

O.pinnatum (E.,K.).— Frustules three
to_ six times longer than broad ; valves
with roimded, not attenuated, ends,
and 25 strong striiB in 1-1200". KSA.
p. 13. = Frayilaria pinnata, EB. 1844,
p. 202 ; Microg. t. 35 a. 22. f. 8. Ant-
arctic Sea.

0. minimum (Nag.). — Vei7 small;
valves trapezoid, with acute a'pices and
very faint, nearly obsolete transverse
striiB ; front view quadrate, with margi-
nal puncta. KSA. p. 880.= O. Salishur-
gense, Rab D. p. 38, t. 2. f. 7. Em-ope.

0. rotiindatum (E., K.). — Frustules
often nine limes aa long as loroad ;
valves linear, with rounded ends, and

776

SYSTEMATIC HISTORY OF THE INFUSORIA.

20 Stout costffi in 1-1200". KSA. p. 13.
= Fraqilaria rotunduta, EB. 1844, p. 202 ;
EM. pi. 1. 1. f. 1. Fossil. PhUippiue
Islands.

0. jnniicilu7n (E., K.). — Fmstules three
to six times as long as broad; A'alves
lineal', with rounded ends, and 15 stout
costaj in 1-1200". KSA. p. 13. = Fra-
giluria pinnata, EA. p. 127 ; Microg.
many figm-es. Australia, Africa, aud
America. Akin to O. striatum and 0.
Syriacum, E.

0. striolatii?n(E.,'K,). — ^Frustules three
to six times as long as broad; valves
linear, constricted beneath the obtuse
capitate ends; sti-ia3 about 18 in 1-1200".
KSA. p. 13. = Fruf/ilaria striolatu, EINI.
t. 28. f. 58. Em-ope and Australia. Ehr-
enberg's iigures in the 'Microgeologie'
have the ends slightly attenuated, aoid
not capitate.

O. Syriacum (E., K.). — ^Frustules eight
times as long as broad ; valves with 10
strife in 1-1200". KSA. p. 13. = Fra-
gilaria Syriaca, EB. 1840, p. 16. Sjnia.

0. ? polyedrum (E. K.). — Frustules
oblong, angular (sexangidar ?) ; three
times as long as broad ; strias very
fine. KSA. p. 14. = Frayilaria polyedra,
EB. 1845, p. 77. Fossil. America.
1-900".

0. am2)Mceros (E., K.). — Valves tm-gid
at the middle, with elongated, linear,
truncate ends and pervious striae. KSA.
p. 13. = Fragilana amjjhiceros, EB.

1844, p. 82 ; Microg. t. 18. f. 77. Vir-
ginia.

0. granulatum (E., K.). — With the
habit of O. anyyhiceros, but smaller;
valves with attenuated ends and granu-
lated fascise in striae. KSA. p. 13. =
Fragilana gramdata, EB. 184^ p. 202.
Antarctic Sea.

0.? <?/fOJs(E.,K.).— Frustules striated,
short, gibbous at the middle, constricted
at the obtuse ends, aud resembling the
figure of an acorn ^vith its calyx ; sti-iae
2 or 3 in 1-1200". KSA. p. U. = Fra-
(/ilaria Glans, E Inf. p. 185. Fossil.
Fmlaud. 1-1150" to 1-570".

0. ano7)ialum (S.). — Filament tena-
cious ; valves linear, suddeidy constricted
towards the rounded extremities ; costae
four to twelve. SBD. ii. p. 16, pi. 61.
f. 376. Alpine situations. Em'ope. Front
view with punctate or denticulate mai-
gins. Internal cells, similar to those met
with in INIeridion and Himantidium, ai-e
frequent in this species.

O. anceps (E.). — Small ; valves linear-
oblong, constricted beneath the subcapi-
tate apices. — - Fraqilaria anceps, EA.
p. 127 ; F. Pteridium, EM. pi. 34. 5 b.
f. 10 ? North America.

0. Cretce = Frayilaria Cretcn, EM.
pi. 53. 17. f. 9 ; F.p'aradoxa, EM. pi. 33.
15. f. 13 ? Australia, Europe, and Afi-ica.
Valves linear-oblong, with roimded ends
and pervious ti-ansverse costaj.

Gemis FEAGILAKIA (Lyngb., K.). — Frustules linear, united into a fila-
ment; lateral valves smootli or faintly striated, Hnear-lanceolate or fusiform.
Fragilaria differs from Odontidium in the absence of costas ; and the stria?,
which are probably present in all the species, are so obscure that Kiitzing
makes their absence one of the generic characters. Diadesmis may be distiu-
guished from Fragilaria by the presence of a central nodule in the lateral
valves. Professor Smith justly regrets that in the subdivision of Fragilaria
sufficient regard has not been j^aid to the signification of the generic name.
We consider that it would have been fai- better to have retained the name
for Fragilaria hyemalis, Lyngb, (= Odontidium, K.), so remarkable for its
fragility.

FnAGrLAniA capucina (Desm.). — Fi'ont
view naiTow linear, "with obsolete or ob-
scure terminal puucta; valves lanceolate ;
stiiie obscure. KB. p. 45, 1. 16. f 3. =
F. pcctinalis, Lyngb. t. 63 ; Ag Consp
Diat. p. 62 ; F. tmiuis, Ag Consp Diat.
p. 63 ; F. Rhahdosoma, diophthalma, mul-
tipunctata, bipunctata, anqusta, scalaris,
and Jissa, E Inf. F. srpe's, EM. t. 38. 1.
f. 8. Conuuon, but generally in .imall
quantities and mixed with other Diatoms.
Eiu'ope, Asia, Austrnlia, Africa, and

America, (ix. 173, 174.) A very vari-
able species. The frustules are so much
compressed that it is difficult to obtain
a good view of the viilves ; but it may
usually be recognized in the front A iew
hj its obsolete tenninal puncta. A^'lien
dried, it has a silvery lustre. Filaments
elongated.

F. amia (E.). — Valves linear, with
acutely cuueate apices ; str'ix wanting or
obscure ; front view linear. E Meteoii).
t. 2. f. 10; Microg. many figures. = i'^. «i-

OF THE PlUGIlAEXEiE.

777

piicina, SBD. pi. 85. f. 29G. Europe,
Asia, Afi'ica, and America. 1-1152";
six times longer than broad.

F. corriigittu (K.). — Minute ; frustules
geminate, coiTugated at each end ; valves
acutely lanceolate. KB. p. 45, 1. 16. f. 5.
Gei-many. 1-1440".

F. pusilla (K.). — Glassy ; frustnles
rectangular, quadi-ate, or lineai", imited
in very short fascias ; valves naiTOW
linear, ' smooth. KSA. p. 14. Maiine.
France.

F. Bacillum (E.). — Valves smooth,
linear with roimded ends, five or six
times as long as broad. EB. 1844 ;
Microg. pi. 21. f. 30 & pi. 35. 16. f. 11.
Fossil. Oran and Virginia. 1-720".

F. glabra (E.). — Linear, smooth, with
attenuated obtuse apices. EA. p. 127.
Guiana. May be a variety of F. bi-
ceps, E.

F. Catena (E.). — Twice as long as
broad ; valves oblong, smooth. EB.
1840, p. 16. = F. turgens, EM. several
figm-ea? Eiuope, A&ica, and Mexico.
1-1152".

F. virescens (Ralfs). — Valves tm'gid
lanceolate, suddenly conti-acted towards
the obtuse ends ; sti'ise 44 in -001", very
faint. Ealfs, Ann. xii. ; SBD. ii. p. 22,
pi. 35. f. 297. — Diatoma virescens, HBA.
F. pectinalis, E. Streams. Eiu-ope. Fila-
ments elongated, lurid-green; frustxdes
rather broad, with distinct terminal
pimcta, frequently irregularly adhering
by theii' angles lilie a Diatom. Easily
recognized by its gi'eenish hue when
gTOwing.

F. Venter (EM. several figm-es). —
Minute ; valves smooth, twice as long-
as broad, oblong lanceolate, with con-
tracted, produced, obtuse ends.

F. mesotyla (E.). — Bacillar with tvu'-
gid centre, obtuse ends, and transverse
gi-anular strire. Asia. 1-480". Resembles
Stauromns granuluta, but wants the lon-
gitudinal band and crucial umbilicus, E.

F. Icevis (E.). — Resembles OdonticUum
amphiceros, but is without the dotted
striiB. EA. p. 127. Virginia.

F. biceps (E.). — Valves linear oblong,
suddenly constricted at the ends into
minute bealcs ; striae wanting or obscure.
EA. p. 127; Microg. several figures.

=F. gibha, EM. pi. 33. 17. f. 9 ? Ame-
rica and Europe.

F. binodis (E.). — Parasitic, mostly
simple ; valves rostrate, sometimes con-
stricted, sometimes infiatedat the middle;
striiB wanting or obsciu-e. EA. p. 127 ;
Microg. pi. 5. 2. f. 26. = Odontidium ? 7;a-
rasiticiim, SBD. ii. p. 19, pi. 60. f. 375.
Em-ope and America. ^ inflated, with-
out a central constriction. S I. c. p. 375.
Frustnles rarely cohering, and scarcely
silicious. S.

F. constricta (E.). — Frustnles fre-
quently cohering by theii' angles ; valves
rostrate, subacute, in general slightly
constricted, sometimes inflated at the
middle ; sti-iae faint, 42 in -001". EA.
p. 127 ; Microg. several figm-es. = F.
undata, SBD. ii. p. 24, pi. 60. f. 377.
/3, valves turgid at the middle, S. Eu-
rope, Asia, Australia, and America.

F. Entomon (E.). — Valves elongated,
smooth, strongly constricted at the
middle, with rostrate ends. EA. p. 127;
Microg. pi. 5. 3. f. 52. North America.

F. binalis, EM. pi. 14. f. 52. Germany,
and Mamitiiis. Valves smooth, con-
stricted at the middle, and rounded at
the ends.

Doubtful and undesciibed Species from,
FJirenberg.
F. ? Tessella, EM. pi. 20. 2. f. 29.
Broadly and sharply lanceolate without
marlriugs.

F. ? Synedra, EM. pi. 39. 3. f. 60, 61.
Frustnles united, cui-ved; venter gibbous
at centre.

F. ? Mesogongyla, EB. 1856, p. 333,
f. 48. Africa. Valves with minute in-
flated middle, and slender acute rostrate
ends.

F. oxyrhambus, EB. 1856, p. 333,
f. 44, Africa; F. Trachea, Australia; F.
seminuda, fossil, Georgia; F. vcntralis,
Anatolia ; F. Himalayce, India ; F. ?
Stylus, yEgina ; F. ? Siylidium, yEgina ;
F.? undulatum, Asia;" F. Cni.r, Asia;
F. Tcenia, Africa; F. amphihpta, Africa;
i^'. irt//it'W«, Australia; F. amphicejyhaUi,
Asia ; F. vcniricosa, Africa ; J^. frus-
tulia, America; F. Eunotia, Africa; 7''
thermalis, America; F. australis, Ame-
rica; F. Pomerooni, America.

Genus GRAMMONEMA (Ag.). — Frustulcs similar to those of Fragilaria.
but scarcely sUicious, and tmitcd into flexible, higlily mucous filaments.
" Grammonoma in appearance comes very near to Fragilaria ; but its liabit is
so very different that I urn inclined, witli Agnrdh, to keep thorn distinct. In
Fragilaria the iilauients do not adhere well to ])aper, tlie frustnles are silicious
and may be subjected to a red heat without any other alleratioii than the

778

SYSTEMATIC HISTOBY OF THE INFUSOliTA.

destruction of tlio colouring matter, and at each end are two, more or less

distinct, pellucid puncta In Grammonema there is scarcely any silica,

and the filaments arc not fragile, but highly mucous, adhering firmly to paper
or glass, and when dried appearing hkc a mere stain ; the application of nitric
acid or of a red heat destroys theii- form, and I can perceive no puncta at the
ends of the frustules." Ealfs, Ehrenberg, and Kiitzing place this genus with
the DesmidiciB because of the absence of silica ; and Meneghini says, " I think
this conclusion right. It is a time Desmidiean, for it has no sUicious shield ;
and it is to be observed that, however perfectly it may resemble the Fragi-
lariete in form, it wants the longitudinal canals and terminal perforations of
the primary surfaces."

Grammonema Jurc/ensii (Ag.). —
Valves oblong lanceolate, slightly con-
stricted at the obtuse ends. Ag CD.
p. 63. =Fra(/ilana Jiirgcnsii, KSD. p. 59 ;
Conferva striatula, Jm-g. ; Fragilaria
striatula, Lyngb Uyd Dan. p. 183, t. 63 ;
SBD. ii. pi. 23. f. 298 ; Grummatonema
striatulum, KSA. p. 187; Arthrodesinus
striatnlus, ERBA. 1840; Fragilaria au-

rea, CiBrm. in Hook B Fl. ii. p. 403.

/3. diatomoides, filaments tui'ning greenish
when dried, = Fragilaria diatomoides,
Grev., Hook B Fl. p. 403. On marine
Algse. Spring, Europe, (xv. 24, 25.)
Grammonema Jurgensii is easily distin-
guished from every species of Fragilaria
by its marine habitat and flexible, highly
mucous filaments.

Genus DIATOMA (Dec). — Frustules quadrangular, partially separating,
and cohering by the angles (generally by the alternate ones) into a zigzag
chain. Diatoma is distinguished from Fragilaria and Odontidium by the con-
nexion of the frustules at their angles in a zigzag chain. Some species of
Fragilaria, indeed, have a few fnistules similarly adhering ; but this is a con-
stant character in Diatoma, whilst the greater number of their fi-ustules wiU
present the usual appearance of a Fragilaria. Meneghini says, " For my part,
I think it would bo much more natiu'al to place the smooth species {D. pec-
tinale, D. vitreum, and D. hyalinum) in Fragilaria ; those striated with cUij^tic-
lanceolate surfaces (D. vulgare, D. mesodon, D. tenue, and D. mesoleptum) in
Odontidium. There would remaiu as distinctly generic the species which
have capitate extremities on theii' lateral sui-faces. These unions would be
justified on both sides ; for whilst the Odontidia have fonns little difierent
from Diatoma, Diatomata are Httle different fi'om Fragilaria."

* StncB obsolete.

Diatoma hyalinmn (1^.). — Frustides
elongated, very hyaline; valves lineai'
lanceolate, with rather obtuse apices ;
striffi obsolete. KB. p. 47, t. 17. f. 20 ;
SBD. ii. pi. 41. f. 312. Marine. Em-ope.
(IV. 16.)

D. minimum (Ealfs). — Fiiistides mi-
nute, very hyaline; valves about twice
as long OS broad, oblong with rmmdcd
ends ; striaj obsolete. Ralfs, T Bot Soc.
2nded. p. 20; SBD. ii. p. 41, pi. 41. f. 313.
= D.vitreu7n,KB.-^A1. Manne. Europe.

D. pecti7iale (Nitz., K.). — Frustides at
first forming a fascia, afterwards zigzag ;
valves acutely lanceolate ; stiire obsolete.
KB. p. 47, t.'l7. f. \\. = Bacillaria pccii-
nalis, Nitz ; li. acrinfa, Plolcmm, jlttccu-
losa, E Inf. Fresh water. Egypt, En-
rope, England.

2 * Strioi (costce) evident.

D. vulgare (Bory). — Valves spindle-
shaped, suddenly contracted at the ob-
tuse ends ; costje pervious, conspicuou.-!,
about 18 m -001". I^B. 1. 17. f. 15 ; SBD.
p. 39, pi. 40. f. 309 ; Bacillaria vulgaris,
E Inf. p. 197 ; Diatoma tcmic, Grev.,
H13 Fl. p. 406 ; D. focculosnm, Ag CD.
p. 53. Europe, Asia, Africa, and Ame-
rica. Frustules three or four times as lon^
as broad. Tbis .species is distinguisbea
by the gi-eater breadth and convexity of
its fi'ustides, and by the conspicuous
marginol pimcta of the front view,
(n'. 13; IX. 168.)

D. mesodon (li.). — "\'ah e?> ventncose
lanceolate, with three to five h-nnsvoi-sc
.sIrijE at the middle. KB. p. 47, 1. 17.
f. 13. fi. ciinculum. fnu-^tidcs cuncnto.
KB. 1.17. f. 12. = BaciUaria cuncata, E

OF THE FRAGILAHIEiE.

779

Inf. t. 15. f. 6 ; Diatoma cuneatum, Kab
D. t. 2. f. 4. Germany, (ix. 170.) Pro-
bably a state of D. vul</are.

B. tenuc (Ag.). — Valves lanceolate,
^^dth from 9 to 12 distinct striae in
1-1200". Ag CD. p. 52 ; KB. p. 48, t. 9.
f. 10. = Bacillaria pectinahs, Eluf. p. 198,
1. 15. f. 4. Europe arid Asia. A protean
species ; the friistules are sometimes qua-
drate, sometimes linear, and sometimes
cuneate.

D. mesoleptum (K.). — Frustides slightly
attenuated at the middle ; valves lanceo-
late, with from 10 to 12 strifB in 1-1200".
KB. p. 48, t._17. f. 16. Europe. 1-650".
We fear it is scarcely distinct from D.
tenue.

D. Elirenhergii (K.). — ^Front view at-
tenuated at the middle; valves linear
lanceolate, contracted beneath the sub-
capitate apices; costse 11 in 1-1200".

KB. p. 48, 1. 17. f. 17 ; SA. 1857, xix j). 10,
pi. 1. f. 13. = Bacillaria clongata, E Inf.
p. 198, t. 15. f. 5. Europe, (ix. 169.)
The inflation in the centre of the valve
separates this species from ID. grande,
which is moreover a lai-ger form with
coarser striis, S. (rv. 15.)

D. grande (S.). — Valve linear, con-
stricted beneath the capitate apices ;
costa3 24 in '001". SBD. ii. p. 39, pi. 40.
f. 310. = Bacillana australis, EM. pi. 35.
A 2. f 3. Britain, Africa, and South
America.

Y). elongatum (Ag.). —Valves linea,r,
with inflated, capitate apices ; costse 7 in
1-1200". KB. p. 18, t. 17. f. 18 ; SBD.
ii. p. 40, pi. 40. f. 311. = Biatoma gracil-
limum, Niig., KSA. p. 889. Eiu'ope.
Frout view slender, attenuated at the
middle, (iv. 14; ix. 119.)

Gemis ASTEEIONELLA (Hass.). — " Frustules linear, inflated towards
one or both extremities ; adhering by their adjacent angles into a star-like
filament" (SBD. ii. p. 81). The frustules in this genus exactly resemble
those of the capitate species of Diatoma, but are few in number ; and being
connected by the adjacent angles, the fi-ee extremities diverge in a stellate
manner. We first observed a single specimen amongst some freshwater Algae
gathered near Dublin by Mr. D. Moore, and afterwards obtained it plentifully
for two successive years in a pool near Dolgelly, when avc considered it a
species of Diatoma nearly allied to D. tenue. Subsequently we received a
larger fonn from Professor Dickie, gathered near Aberdeen. The Scottish
form had the fi-ee end trancated, and is probably the one described by
Professor Smith as A. Balfsii.

AsTERiONELLA fonnosa (Hass.). —
Front view somewhat more enlarged at
the base than at the sunmait. -0024" to
•0031". SBD. ii. p. 81. Fresh water.
Britain, (iv. 17.)

A. Bleakeleyii (S.). — Frustules linear,
enlarged at the base. -0022". SBD. ii.
p. 82. Mai-iue. England.

Balfsii (S.). — Fmstules in fi-ont
view exactly linear ; valve attenuated at
one end, constricted towards the other,
which is rounded and capitate; striaj
obscm-e. SBD. ii. p. 81. = Diatoma stel-
lare, BO. p. 39. Fresh water. Em-ope
and America, (iv. 18.)

Genus NITZSCHIA (Hass., Smith).—" Frustules free, elongated, com-
pressed ; valves lineai', keeled, -with one or more longitudinal lines of puncta ;
keel frecjuently eccentric. . . . This genus embraces a large number of species,
differing in form and size, but all agreeing in a few general characters. The
most important of these is the keeled form of the valves and the remarkable
inequality, in many of the species, between the portions of the valve lying on
either side of this prominency. This inequality (or, in other words, this
eccentricity) of the keel distinguishes Nitzschia from Aniphiprora, in which the
keel is also present ; while the presence of a, keel and its accompanying line
or lines of puncta, together with the absence of any form of stipes, separate
the present ft'(wft the genus Synech-a." Professor Smith, whose generic cha-
racter and remarks we have (pioted, has brought together forms from several
genera, and thus has not only pointed out tlie remarkable character which is
common to them all, but also relieved those genera of members which ill

780

SYSTEMATIC HTSTOKY OF THE INFUSOlilA.

agreed mth theii- definitions. It is, however, probable that his characters
may rather belong to a family than to a single genus, his sections forming
genera. The sigmoid forms were placed by Ehrenberg in Navicula, and by
Kiitzing, in his earlier work {Kiesel. Bacil.), in Synedra. Subsequently, how-
ever, in his 'Species Algarum,' Kiitzing removed them from Synedi-a, and,' under
his old name of Sigmatella, placed them with the PragilarieEE because they are
not affixed and have pervious transverse striae.

* Minute : front view strait ; valves ar-
cuate tvith a row of dots on the ventral
margin.

NiTzscHiA amjjhioxys (E.). — Valve
linear lanceolate, arcuate, with convex
dorsmn, concave ventei-, and attenuated,
subrostrate, acute apices; striae 30 iu
•001", terminating in dots at the ventral
margin. SBD. i. p. 40, pi. 13. f. 105.
z=Eunotia am])hioxys, EA. p. 125. Fresh
water, very common. Ehrenberg gives
upwards of 200 habitats in Eiu-ope, Asia,
Australia, Afiica, and America.

N. vivax (S.). — Valve linear lan-
ceolate, arcuate, with rostrate apices ;
striae distinct, 30 in -001 ", terminat-
ing in marginal dots. SBD. i. p. 41,
pi. 31. f. 267. Fresh or brackish water.
England.

N. jMrvula (S.). — Valve with central
constriction, obscm-e puncta, and pro-
duced apices ; strife faint, 70 in -001".
SBD. i. p. 41, pi. 13. f. 106. Maiine.
Sussex,

N. minutissijna (S.). — Valve linear,
with distinct puncta and prominent
acute apices ; strife obscm'e, 72 in -001".
SBD. i. p. 41, pi. 13. f. 107. Fresh
water. Beachy Head.

'N.Diancs (E.). — Valve linear, arcuate,
with convex dorsum, concave venter, and
produced slightly reflexed apices ; strife
13 in 1-1200", temiinatmg in dots on
the ventral margin. = Eunotia Diana,
ERBA. 1840, p. 14; Microg. pi. 35 a.
2. f. 9. Fresh water. Europe, Asia,
Africa, and America.

N. aniphilepta (E.). — Valve linear,
arcuate, with convex, smooth dorsimi,
slightly concave, striated ventral margin,
and acute, gradually attenuated, slightly
reflexed apices. = Eunotia amphik'pta,
ERBA. 1845, p. 363; Microg. pi. 34. 8.
f. 4. Japan and China.

N. vir(/ata (Roper). — Valve linear
lanceolate, slightly arcuate, with pro-
duced, slightly recurved, obtuse apices ;
strife distinct, 26 in -001", dilated at in-
tervals into ridges on tlie ventral margin.
Roper .IMS. vi. p. 23, pi. 3. f. 6. Ma-
rine. Tenby. IHIliirs irom N. amphi-
oxys and N. vivax by the striie being

dilated into bands instead of terminating
iu pimcta. Roper.

2 * Frustides constricted at the middk.

N. constricta (K.). — Front view ob-
long, slightly constricted at the middle
and tapering towards the somewhat
trimcate ends ; keel very ecceuti-ic ; striae
obscm-e, 60 in -001". = Synedra con-
stricta, KB. p. 64, t. 3. t 70 ; Nitzschia
dubia, SBD. i. p. 41, f. 112. Marine.
Europe.

N. Entomon (E.). — Elongate, thick,
striate, oblong with constricted middle
and obtusely cuneate ends. = Synedra
Entommi, EM. pi. 34. 2. f. 5. Em-ope,
Asia, Austraha, Africa, and America.

N. plana (S.). — Front view linear
lanceolate, wth attenuated middle and
acutely cuneate ends ; valves acutely
linear lanceolate, with a single row of
puncta and 56 obscm-e stiiae in -001.
SBD. i. p. 42, pi. 15. f. 114. Brackish
water. Europe.

N. Briyhtwellii (Kitten). — Valves
broad linear-oblong, with obtiise, shortly
attenuated ends, slightly constiicted
middle and interruptedly stiiate margin ;
sm-face imder a low power gi-anular,
under a higher, punctato-striate ; stiia3
transverse, 25 to 30 in -001". Brackish
water. SieiTa Leone. Kitton in lit.
(jui. 7.)

N. latestriata (BiiSb.). — Front view
large, broad linear-oblong, with a central
constiiction and bi'oadl}' rounded ends ;
vfdves uai'row lanceolate, with a central
keel, double row of pimcta and 56 di-
stinct strife in 001". = Ainphiprora late-
striata, Br^b. in KSA. p. 93; A7tec/«"rt
bilobata, SBD. i. p. 42, pi. 15. f. 113.
Marine. Europe.

N. pandariformis (Greg.). — Broad
linear-oblong, with constricted middle,
acuminata ends, and punctuated nuir-
gins ; sti-ife fine, about 48 in -001", traus-
A'crse and oblique. GDC. p. 57, pi. 6.
f. 102. Maiine. Scotland. Tliere is a
faint indication of a double keel in tlic
middle of the valve. The .striarion is
similar to that of Tryblionelia con.strieta ;
but the present fonii is larger, and di-
stinguished by marginal puucla ; still it

OF THE FBAGILAEIE.T!.

781

resembles a Tryblionella about as much
as it does a Ni'tzschia, Greg.

3 * Front view sir/moid (Sigmatella,
Kiitz.).

N. sigmoidca (Nitzsch, S.). — Front
view elongated, broadly liuear, sigmoid
with truncate ends and marginal puncta ;
valves narrow linear-lanceolate, with
tapeiing ends and a single longitudinal
seiies of puncta ; sti'ife 85 in •001". SBD.
i. p. 38, pi. 13. f. lQL = Ncmcida sig-
moidea, EI. t. 13. f. 15 ; Synedra sig-
moidea, KB. p. 67 ; Sigmatella Nitzschia,
KSA. p. 18 ; Nitzschia elongatu, Hassall,
B iUg. p. 435. Fresh water. Em"ope.
(ex. l48.) Lai'ge, vsdth elegantly pimc-
tate margins. The strife in this Diatom
are sometimes strong and easily seen,
while others in the same slide set at
defiance every method of illumination to
bring them out. IMi*. Sollitt, of Hull,
says, " The sti'ise vary from 65 in the
•001" up to a degTee of fineness which
no lenses that we now have will show."

N. Brebissonii (Kiitz., S.). — Front view
broadly linear, sigmoid with ti'imcate
ends and marginal pxmcta ; valves linear,
with attenuated, obtuse apices ; strijB 27
in •OOl". SBD. i. p. 38, pi. 31. f. 266.
= Synedra Armoricayia, KB. t. 4. f. 34 ;
Sigmatella Brebissonii, KSA. p. 18.
France, England. Resembles N. sig-
moidea, but is much broader in propor-
tion to its length, the puncta are more
conspicuous, and the lateral view is more
linear. According to Professor Ai-nott,
this species is not the Sigmatella Bre-
bissonii of Kiitzing, the latter being a
mere variety of N. sigmoidea, whilst
Smith's species is distinct and a brackish-
water species.

N. macilenta (Greg.). — Front view
elongated, linear, sigmoid, truncate ;
valves linear lanceolate, with acute api-
ces ; keel with a single row of subremote
pimcta ; strire very obscure. Grev MJ.
vii. p. 83, pi. 6. f. 8, 9. Marine. Scot-
land. Allied to N. sigmoidea, but de-
cidedly less sigmoid. The side view
very naiTow ; puncta separated from each
other by in-ep^ular intervals, and fewer
(8 in •001") than in N. sigmoidca, Gre-
ville.

N. Sigma (K., S.). — Front view sig-
nioid, linear lanceolate, gTaduaUy taper-
ing t o the truncated apices ; keel of valves
with a double row of puncta. SBD. i.
P- 39, pi. 13. f. 108. = Si/nedra Sigma, IvB.
P- 07, t. .30. f. 14. 'Marine.' Europe,
SLnu) .'jO in -001", S. (iv. 20.)

N . Sigmatella (Greg. ) . —Front v iow si g-

moid, linear lanceolate, gradually taper-
ing to the obtuse apices ; valves tlinear,
acute, with obscure strine. Greg MJ. iii.
p. 4, f. 2. = iV; carmda, SBD. ii. p. 39.
Fresh water. Eiu'ope. Distinguished
from N. Sigma by its far more delicate
sti'iae and freshwater habitat. Professor
Kiitzing describes the Navicula curmda
as straight in the fi'ont and sigmoid in
the lateral view ; it is therefore probably
a Plem-osigma, and not this species, aa
supposed by Smith.

N. vermicidaris (K.). — Front view sig-
moid, slender, liuear or slightly dilated
at the middle; strise dhscm:e. = St/nedi-a
vermicidaris, KB. t. 4, f. 35 ; Sigmatella
vermicularis, KSA. p. 18. Fresh water.
Europe.

N. Tergestina (K.). — Front view sig-
moid, linear, tiiincate; valves naiTow
linear, with suddenly contracted, pi'o-
duced apices. = Synedra Tergestina, KB.
p. 66, t. 4. f. 33; Sigmatella Tergestina,
Eab D. p. 56. Europe. 11 strife in
1-1200", Rab.

N. Italica (Rab.). — Front view broad-
ly linear, slightly sigmoid, truncate;
valves sigmoid, with attenuated rounded
ends, and 9 stiise in 1-1200". = Sir/matella
Italica, Rab D. p. 56, t. 4. f. 12. Italy.
_ N. obtusa (S.). — Front view sigmoid,
linear, with rounded apices ; valves linear,
obtuse, with a double series of pimcta ;
sti^iaj 56 in -001". SBD. i. p. 39, pi. 13.
f. 109. Brackish water. Sussex.

N. Smithii. — Front view broadly
linear, sigmoid, tnmcate, with conspi-
cuous marguial capitate sti-ite havino-
smaller puncta intei'posed between them";
valves distinctly striate. =i\''7fcsc/(irt spec-
tabilis, SBD. i. p. 39, pi. 14. f. 116. Ma-
rine. Britain. Keel neai-ly centi-al,
pimcta in foui- rows. Sm.

4 * Front view lunatcly curved.
_ N. arcaata (Greg.). — Front view
linear arcuate, with roimded ends ; valves
lanceolate, obtuse; pimcta about 20 in
•001". Grev. MJ. vii. p. 82, pi. 6. f. 4-7.
Marine. Scotland.

5* Frustides straight in both views, not
constricted at the middle.
t Front view linear.

l^. scalaris (E., Sm.).— Large; front
view broadly linear, witli dilated truncate
ends and broadly striated margins, the
stria) alternately longer and shorter •
valves linear With shortly attenuated'
obtuse ends. SI5D. i. p. 39, pi. 14. f. 115'
= Synedra scalaris, EA. p. 137, t, 2 2

782

SYSTEMATIC HISTOEY OF THE INFUSORIA.

f. 18. Braclcish water. Europe, Asia,
Australia, and America, (rv. 21.)

N. spectabiUs (E.). — Large ; front view
broadly linear, with truncated cuneate
apices; valves witli rounded ends. =
Synedra spectabiUs, EA. and M, several
figiu'es. Europe, Asia, Australia, Africa,
and America. The valves are figured as
elongated, narrow linear, with suddenly
attenu.ited, obtuse, reflected apices, and
a row of pimcta on one margin.

N. insignis (Greg.). — Front view
broadly linear, with roimded ends and
conspicuous marginal pimcta and strise ;
valves linear lanceolate, straight or
slightly sigmoid, with subcentral keel
and 30 distinct striae in -001". Greg.
MT. V. pi. 1. f. 46. Marine. Scotland.
Distinguished from N. sicpnoidea and N.
Brebissonii by its straight front view ;
and fi-om N. scalaris by its finer markings,
more slender form, and nondilated ends.
Greg.

In. gigantea (E.). — Very large, linear,
with suddenly rounded ends ; valves
with attenuate subacute apices ; surface
finely striated in the intervals of the -^in-
Tm\.ea. = Synedra gigantea, EKBA. 1841,
p. 22 ; Synedra Lihyca, KSA. p. 48.
Oasis of Jupiter Amnion, 1-60".

N. linearis (Ag., S.). — Front view
linear, with roimded or trimcate apices
and nearly central keel ; puncta m a
single row; striae obscure. SBD. i. p.
39, pi. 13 & pi. 38. f 110.= Frustidia line-
aris, Ag. Fresh water. Europe.

'N.Palea (K., S.). — Front \-iew linear ;
valves narrow, lanceolate, acute. SBD.
ii. p. 89.= Synedra Palea, KB. p. 63, t. 4.
f. 2 ; Synedra Fusidimn, KB. p. 64, t. 30.
f. 33 ; Synedra fiisidioides, Rab D. p. 53,
t. 4. f. 47. Eiu'ope. Frustules minute.

N. tenuis (S.). — Front \'iew linear,
ti'imcate ; valves naiTow, lanceolate,
acute ; striaj obsciu*e. SBD. i. p. 40, pi.
13. f. 111. Fresh water. England.

2t Exti-emities, in front view, with a
hyaline wing or expansion on each side.

N. spathulata (Bri5b.). — Front view
lanceolate, with the trimcate ends dilated

on each side ; valves lanceolate acute,
with a single row of puncta. SBD i
p. 40, pi. 31. f. 268. Marine. France
and England.

N. distans (Greg.). — Front view broad,
sublinear, with distant iiregularly dis-
posed marginal puncta ; apices truncate
with a slight hyaline expansion on each
side. GDC. p. 58, pi. 6. f 103. Marine.
Scotland. Valves lanceolate, with acute
apices and central keel.
_ N. hyalina (Greg.).— Front view sub-
linear, -nath small, regular marginal
pimcta ; valves naiTow linear, -nath con-
tracted, produced apices and centi-al keel.
GDC. p. 58, pi. 6. f 104. Marine. Scot-
land. Keel apparently double ; but per-
haps one is seen through the very hyaline
valve. Greg.

3 t Front view lanceolate.

N. angularis (S.). — ^Front view rhom-
boid-lanceolate, tiimcate ; valves lanceo-
late, with central keel ; pimcta in a single
series and longitudinal lines. SBD. i. p.
40, pi. 13. i. 117. Maiine. Sussex.
This and the following species ought
perhaps to be placed in Ceratoneis.

N. lanceolata (S.). — Fi'ont view broadly
lanceolate, acute ; valves lanceolate, ros-
trate, acute, with eccentric keel and
longitudinal lines. SBD. p. 40, pi. 14.
f. 118. Marine. Sussex.

Doiditfid or insiifficiently described Species.

N. valens (E.). — Yevy large, broadly
Ihiear, finely stiiated, with ti-imcate ends.
= Synedra valens, EA. t. 3. 2. f. 6. Fresh
water, (xn. 44.) Mexico and United
States.

N. curmda (K.). — Elongated, curved;
front view slightly attenuated towards
the truncate apices ; valves acuminated,
subacute, sometimes ■with a longitudinal
pimctate line. = Syticdra curvula, KB.
p. 65, t. 15. f. 2. Fresh water. Prussia,
1-240".

N. Ehrcnberqii = Synedra amphihpta,
EM. pp. 34-5,"f. 11. Cape Verd. Elon-
gated, straight, linear, with striated mar-
gins and acutely cuneate apices.

Gcnns CERATONEIS (Ehr.).— Frustules as in Nitzschia, but with long
rostrate ends, and usually mth a more or less e^ddent central pseudo-nodulc.
Professor Smith, after excluding some of its species, made Ceratoneis a sec-
tion of Nitzschia, and perhaps Avas justified in so doing ; but as the forms
included in it are remarkable for their filiform beaks, and tliere is some
appearance of a central nodule, wc have retained the genus, at least for the
present. Some of the species resemble the Closteria in form, and have been
referred to as showing an affinity between the Diatoniacca? and the Desnii-
diere. The resemblance, however, is merelj- superficial, and, instead of showing

OP THE SURIRELLEiE.

783

an affinity, rather proves it does not
place across the lunate frond, or in the
it occurs in the opposite direction.

Cehatoneis longissima (Br4b.^. —
Valves lanceolate, with very long straight
slender a'mis, a subcentral keel, a single
row of puncta, and obscm-e strias. KSA.
p. 891. = Nitzschia hirostrata, SBD.
i. p. 42, pi. 14. i. 119. Marine. Fi-ance,
England. Front view straight, with
lanceolate middle, and long, lineai',
ti'uncated beaks, (iv. 22.)

C. Closteriurn (E.). — Front view arcu-
ate, with lanceolate middle, and long,
filiform, incui-ved awns ; valves faintly
striated, with central keel and a single
row of puncta. Ehr. leb. Kreidethierchen.
t. 4. f. 7. = Nitzschia Closteriuin, SBD.
i. p. 42, pi. 15. f 120. Europe, (xu. 59.)

C. rerersa (Sm.). — Front view lanceo-
late, with long beaks, the extremities
of which are bent in opposite du'ec-
tions ; puncta obsolete ; stiire obscui'e,
48 in •001". = Nitzschia reversa,
SBD. i. p. 4.3, pi. 15. f 121. Brackish
water. Eiu'ope.

C. spiralis (K.). — Lanceolate, with
long, flat, spirally-twisted beaks. KB. p.
104, t. 4. f 38. Marine. Europe, (xm. 9.)

C. suhulata (Br6b.). — Lanceolate su-
bidate, very slender, smooth, gradually
tapering into slender beaks, which are
sometimes straight, sometimes curved or
sigmoid. KSA. p. 89. Marine. France.

exist. In the Closteria, division takes
shortest diameter, whilst in this gemi.s

0. acicularis (K.). — Front view naiTOw
linear ; valves lanceolate, with straight,
slender beak ; striae obscure. = Synedra
aciculaiis, KB. p. 63, t. 4. f 3 ; Nitzschia
acicularis, SBD. p. 43, pi. 15. f 122. Fresh
water. Em-ope.

C. gracilis (Breb.). — Elongated, vei-y
slender, liueai', with rather obtuse
straight, curved, or sigmoid beaks ; stiioe
obsciu'e. KSA. p. 89. = Nitzschia Tmnia,
SBD. p. 43, pi. 15. f 123. Fresh or brack-
ish water. Em-ope.

Doubtful Species.

C. Ci-et<B (E.). — Smooth, navicular,
very slightly constricted at the middle,
with acute, straight, not much produced
apices. ERBA. 1844 ; Microg. pi. 22.
f. 61. Fossil. Sicily. The figiu-e shows
a distinct median line and nodide.

C. laminaris (E.). — Broadly lanceolate,
with striated margins and short rostrate
apices. EA. t. 3. 7. £ 24. Asia and
America. Valve with median line and
centi-al nodide.

C. Linea. = Synedra Linea, EM. pi. 18.
f. 78. Fossil. Virginia. Lanceolate, with
punctated margins, and naiTOw-linear,
rostrate ends.

C. rhotnboides (E.). — India.

Genus AMPHIPLEURA (Kiitz.). — Fmstules simple, elongated; valves
with longitudinal ridges. An iU-defined genus, the species of which ditFer
considerably in their appearance.

Amphiplehra pellucida (K.). — ^Frus-
tules slender, hyaline ; valves narrow
lanceolate, with rather obtuse apices.
KB. p. 103, t. 3. f 32 ; SBD. pi. 15. f. 127.
= Navicula pellucida, Ehr Inf. t. 13 ;
Aulacocystis pellucida, Hass Algae, p. 427,
pi. 102. {. 8. Fresh water. Europe.
(IV. .30, IX. 140 & XIII. 1.) 1-300" to
1-140". Frustides often connected in
flat, longitudinal band-like series by a
mucous covering.

A. Danica (K.). — Lanceolate, obtuse
or truncated, smooth. KB. p. 103, t. 30.
f 38. Marine. Em'ope. 1-390".

A. rigida (K.). — Elongated, linear
lanceolate, with truncate ends; front view

straight; valves slightly sigmoid. KB.
. 104, t. 4. f 30. =Amp]iipleura siqmoidea,
BD. i. p. 45, pi. 15. {. 128. "Marine.
Europe, (xiu. 2.) It forms brown
stain-like patches on marine rocks, and
scarcely changes colour when gathered.

A. inflexa (Breb.).— Valves linear, lu-
nately cui-ved, slightly attenuated, some-
what constricted beneath the rounded
apices. KSA. p. 88. Marine, (iv. 31.)
France and Britain. 1-430" to 1-.330".
Strire close, usually very indistinct. In
mode of growth .and colour it resembles
A. rigida, but changes to a green colour
as soon as gathered.

FAMILY v.— SURIRELLEiE.

Fmstules prismatic or snbdisciform ; stria3 of the lateral siufaces either
interrupted by a longitudinal line or radiate. The SurirellefE comprise by no

784

SYSTEMATIC HISTOBY OF IKE INFUSORIA.

means a satisfactory group, and we believe that Synedra and the other genera
with, wand-like frustules should be removed from this family, whether they
be united to the Fragilarica) or retained together as a distinct family ; but the
object of this work is rather to present an epitome of what has already been
done than to introduce any extensive alterations. " The genus Campylo-
discus is near to the Melosii-eae, but the disk is not circular but elliptical.
Siuirella and the free frustules of Synedra are related to the Naviculeaa, but
they want the middle clearly- defined nodule in the secondaiy sides. BacU-
laria is closely allied to the FragUarieaj, especially to Diatoma ; but the strise
of the frustule are interrupted in the middle, while in Diatoma they ai-e

pervious Comparing together the genera Campylodiscus, SurireUa, BacU-

laria, Synedra, it is easily perceived that the last two only deviate from the
Fragilarieaj by the character of interrupted strias ; and the fii'st two, deviating
sensibly in the succession of species from the circular shape of the lateral
surfaces, or of the transverse section, establish a transition between the
Melosireae, and the group formed of these two genera, along with the Pra-
gilariese and the Meridieas. Hence it is impossible to estabhsh an organo-
graphical character that shall embrace the entire family and strictly represent
its type." (Meneg.)

Genus BACILLxiPtIA (Gmel.). — Prustules linear, straight, united into a
short band, moving on each other by a sliding motion without separation ;
valves having a longitudinal punctated keel. The elongated wand-like frus-
tules distinguish this from all other genera, except some species of Diatoma
and Synedra. It differs from the former by the frustules not forming zigzag
chains, and from the latter by its band-like filaments. " The principal organo-
graphical character that distinguishes Bacillaria fi-om the PragUarieae is the
same that allies it to a different group of the family, viz. the interi-uption of
the transverse striae in the median line of the secondary surfaces, to which is
added the parallelism of the primary surfaces." (Menegh.)

late, hyaline ; striae obsolete. DonMn,

* Frustules united into a short band.

BACiLLAniA paradoxa (Gmel.). —
Valves linear lanceolate, E Inf. p. 195 ;
SBD. pi. 32. f. 279. Ditches in salt
marshes. Em-ope. (iv. 18 ; ix. 166,
167.)

2 * Frusttdcs bundled.
B. cursoria (Donldn). — Valves lanceo-

TMS. Yi. p. 16, pi. 3. f. 12. Maiine.
England, (rv. 19.)

B. socialis (Greg.). — "N'alves lanceolate,
with fine, but distinct, transverse striae.
= Nitzschia socialis, Greg. TMS. v. p. 8,
pl. 1. f. 45. Marine. Scotland. Frustules
m groups, strios 30 to 36 in -001, Greg.

Genus HOMCEOCLADIA (Ag.). — Frustules baciUar, Nitzschoid, within
subular, submembranaceous, branched filaments. The fi-ustulcs are usually
fasciculated ; and their structm-e, which is that of the genus Nitzschia, sepa-
rates the present from the other frondose genera (Sm.). When dried, tlio
filaments become opako, and usually acquii-e a metaUic lustre.

IIoMCEOCLADiA Marticma (Ag.).— j H. .^H<7;!ca (Ag.). — Frond ti-ichoto-
Frond umbellately branched, menibrana- mous below, dichotoraous above, opake

ccous, rugose, opalcewheu thiod; frustules
crowded, linear, elongated, obtuse. Ag.
CD. p. 25; KB. p. 110, t. 30. f. 8^.=H.
Aiiyhca, Ilalfs, Annals, xvi. pl. 3. f. 1.
Marino. Em-ope. (rv. 2, 3; xiv. 47-49.)
Fronds much branched, fiaccid when re-
cent, and of a davit olive-colour, with a
metallic lustre and transversely wrinkled

when dry, scarcely rugose ; frustides very
long, linear, obtuse. Ag CD. p. 25 ; KB.
t. 30. f. 82. France and England. Does
not adhere to paper. We are unable to
determine from the fragments we have
examined whether this is tridy distinct
from H. Martiana.

II. Arbusmla (K.).— Very much and

when dried. ' ' umbellately branched, upper branches

OF THE STTEIRELLEiE.

785

fosciculai", capillary, spuriously jointed ;
frustules lineai', elongated, obtuse,
smooth. IG3. p. Ill, t. 22. f. 11. Ma-
rine. Venice. 1-7".

H. dilatata (K.). — Mucli branched, se-
taceous, branches fastigiate, incrassated
above, clavate ; fasciculi closely conti-
guous ; fi'ustules linear, elongated, acicu-
lar, obtuse. KB. p. Ill, t. 23. f. 1. Ma-
rine. Adriatic. 1-12".

H. moniliformis (Kiitz.). — Capillary ;
branches slender, elongated, moniliform ;
fasciculi of frustules remote ; frustules
veiy long linear, obtuse. KB. p. 110,
t. 22. f. 10. Adi-iatic. (xiv. 45, 46.)

H. j)umila (Ag., K.). — L-regularly di-
vided into equal, obsoletely-articulated,
capillary branches ; frustules short linear,
with roimded ends. KB. p. 110, t. 22.
f 9. = Schizonema pumilum, Ag CD. p. 16.
Adriatic, (xiv. 37, 38.)

H. penicillata (Kiitz.). — Fastigiately
branched ; branches divaricate, fasti-

giately divided ; tei-minal ramuli white,
in pencils; primary tube tliick, gelati-
nous cartilagmous ; frustules densely ag-
gregated, slender, linear acicular, very
naiTow. KSA. p. 97. France.

H. luhrica (Me., K.). — Gelatinous,
green, setaceous, for the most part di-
vided at the apex; frustules fascicu-
late, densely aggi'egated, linear. KSA.
p. 98. = Schizonema lubricum, Menegh.
Adriatic.

H.Jiliformis (S.). — Frond simple ; fas-
cicles oi" 3 or 4 frustules ; front view
linear-lanceolate, obtuse ; valves linear
lanceolate, subacute. SBD. ii. p. 80, pi.
55. f. 348. Brackish and fresh water.
England, (iv. 25.)

H. sigmoidea (S.). — Frond simple;
fi'ustules irregularly fasciculated in bun-
dles of about 6 ; front view sigmoid ;
valves linear, with attenuated ends. SBD.
ii. p. 81, pi. 55. f. 349. Brackish water.
Britain, (iv. 26.)

Genus SYN'EDRA (Ehr.). — Erustiiles elongated, wand-like, attached by
the lower end, lateral surfaces equal to or less than the front view, traversed
by a smooth median longitudinal line. The true species of Synedra are
distinguished from all other genera by their wand-like form and attachment
by one end. They are usually either fasciculated or fixed to a distinct stipes
ia a fan-Kke manner. " As to the organographical considerations which can
be instituted in this genus, they reduce themselves to the single one of length
predominating over breadth and the eminently bacOIary form derived from it.
Thus Kiitzing observed of the opposite characters of Synedra and SurireUa,
that the lateral surfaces exceeded in one the primary surfaces in the other."
Several of the species at present placed in this genus may prove, when better
known, to belong to Nitzschia.

* Minute ; attachment slight ; strice
indistinct or obsolete,

Synedra quadrangula (K.). — Very
minute, in one view narrowly linear, in
the other broad quadi-angular. KB. p.
63, t. 3. f. 23. Marine. Norway.

S. Atomus (K., Niig). — Very minute, in
one view elliptic with rounded apices,
in the other linear truncate. KSA. p.
'^0. = Amphora Atomus, KB. t. 30. f. 70;
Synedra minutissima, ^ pelliculosa, K.
(according to M. de Br^bisson). Fresh
water. Europe.

_ S.peipimlla (K.).— Very minute; front
view very narrow linear ; valves lanceo-
late, contracted near the obtuse apices.
KB. p. 6.3, t. 3. f. 31. Venice.

S. Biasolettiana (K.). — Very minute ;
front view very narrow linear, arcuate ;
valves lanceolate, obtuse. KB. p. 63, t.
3, f. 22. Fresh water. Trieste.

S. pusiUa (K.).— Minute ; front view

broadly linear; valves oblong-elliptic,
with somewhat rounded apices. KB
p. 63, t. 3. f. 29. Carlsbad. 1-1800".

S. angustata (K.). Front view very
narrow linear; valves broader, oblono-,
with attenuated, rather obtuse apices,
KB. p. 64, t. 4. f. 1, 3. Hot springs.
Italy. 1-720". ^ ^

S. virginalis (K.). — Front view linear,
ti'uncate, with attenuated centre ; valves
lanceolate. KB. p. 64, t. 3. f. 16. Genoa
1-600".

S. ventricosa (Rab.). — Front view nai*-
row linear; valves ventiicose, witli short
produced, bealc-like apices. Rab D. p. 52*
t. 4. f. 36. Apennines. '

2 * Frusttdcs in lateral view arcuate.

B.lunaris (E.). — Valves uaiTow, linear
arcuate, slightly attenuated, obtuse-
stnn3 faint, 36 in -001". EI. t 17 f 4 !
SBD. i. p. 69, pi. 1 1. f 82. Fresli water'
Common. Europe, Asia, and America.

3 K

786

SYSTEMATIC HISTOES OF THE INFUSORIA.

(x. 185.) Fnistules affixed, often aggre-
gated.

S. falcata (K.). — Valves arcuate, linear,
with obtuse apices, faint striaj, undulated
Tenter. KSA. p. 43. Pai-is.

S. hilunaris (E.). — Valves linear,
curved, bilunate, obtuse, attached, more
attenuated at base ; striae obsciu'e. EL
1. 17. f. 5. Fresh water. Europe. Valves
bent inwards at the middle, so as to be-
come bilunate.

S. lo7i(/issima(^m.'). — Valve much elon-
gated, slightly and gradually attenuated,
with capitate apices ; strife 28 in •001".
SBD. i. p. 72, pi. 12. f. 95. Botanic Gar-
den, Belfast. Is this distinct from S.
biceps ?

S. 6ecep*(K.). — Much elongated; valves
very slender, gi'aduaUy attenuated, with
capitate apices and distinct ti-ansverse
striae. KB. p. 66, t. 14. f. 18. Fresh
water. Em-ope. 1-100" to 1-60". Front
view linear, with striated margins, some-
times dilated at the ends.

S. alpina (Nag.). — Slender, faintly
striated ; front view straight, linear ;
valves arcuate, very naiTow lanceolate,
with produced capitate apices. KSA.
p. 43. Switzerland. 1-600" to 1-336".

S. suharcuata (Nfig.).— Small ; front
view straight, linear, valves slightly ar-
cuate, with produced capitate apices.
1-2400" to 1-1200". Switzerland. Like
S. alpina, but only half the size. Rab.

S._^ea:i<os« (Breb.). — Frontview broadly
linear; valves linear, cm'ved, sometimes
flexuose, vdth capitate apices and very
fine transverse sti'iae. = Eunotia Jlexuosa,
KSA. p. 6; iS. hictps, SBD. i. pi. 11. f. 83.
Fresh water. France, England. /3, valves
two or three times flexed. Diflers from
S. biceps in having linear, not tapering
valves.

S. pacliyccphala (K.). — Front view
slender, linear ; valves linear, slightly
arcuate, with claviform apices and indi-
stinct striae. = Hunoiia pacliyccphala,
KSA. p. 6. Fresh water. Em-ope.

S. arcuata (Niig.). — Smooth ; front
view sti-aight, linear, -with truncate ends;
valves linear, arcuate, with roimdod
apices. KSA. p. 890. Switzerland.

S. f/ibbosa (R.). — Front view linear;
valves arcuate, tapering to the slightly
constricted recm-ved apices ; venter con-
cave, gibbous at tho middle. = Nhvicula
Arms, EI. p. 182 ; Ci/mbella Arcus, IIBA.
p. 420 ; Ceratoncis Arcus, KB. p. 104,
t. 0. f. 10; Hiimdia Arenas, SBD. i. p. 15,
>1. 2. f. 15. Fresli water. Europe. The
rustnles are affixed, as in other species
of Synedra.

t
fr

S. hamata (S.). — Valves linear or
linear-lanceolate, -with suddeidy con-
stricted, produced, incmved apices ; striaj
marginal, 30 in -001". SBD. i. n 73 nl
30. £ 264. Fresh water. Sussex. ' "

3 * Valves straight, with a circular, defi-

nite central pseudo-nodule.

S. pulchella (Ralfs, KUtz.). — Frustules
in fan-shaped clusters on a compressed-
dichotomous stipes; valves lanceolate,
obtuse, with a median umbilicus. KB
p. 68, t. 29. f 87; SBD. i. p. 70, f. 84.=
Ctenophora pidchella, Breb., Synedra
Vertebra, Greg. MJ. iii. pi. 4. £ 22. Ponds
and slow streams. England and France.
Stria3 33 in -001", Sm.

S. oninutissitna (K.). — ^Very minute ;
front view narrow linear- ; valves lanceo-
late, rather obtuse; striae 36 in -001".
KB. p. 63, t. 3. £ 30; SBD. pL 11. £ 87.
Fresh water. Em-ope.

S. gracilis (K.). — Fi-ustides affixed,
scattered ; valves lanceolate, acute, with
a median pseudo-nodide. KB. p. 64, 1. 15.
£ 8 ; SBD. i. p. 70, pi. 11. £ 85. Marine.
Europe. Stnae obscure, 39 in -001", Sm.

S. Smithii (R.). — Fmstules irregularly
affixed; valves lanceolate, acute, with
36 very faint sti-iae in -001." = Si/nedra
acicularis, SBD. i. p. 70, pi. 11." £ 86.
Brackish water. England.

4 * Valves with very long awn-like beaks

(Toxarium) ; nodule obsolete.

S. undulata (Bailey). — Valves slender,
lanceolate at the middle, tapering into
very long, linear, undulated awns, with
clavate apices. SBD. ii. p. 97 ; Greg.DC.
p. 59, pi. 6. £ 107. = Toxarium undidafum,
Bailey, MO. p. 15, figs. 24, 25. JMarine.
America and Em-ope. Front view linear,
broader ; valves arcuate or straight, with
24 monilifonn striae in -001".

S. Hennedyana (Greg.). — F^ustides as
in S. undulata, but the awns not undu-
late. GDC. p. 60, pi. 6. £ 108. Marine.
Scotland.

5 * Frustules affixed, aggregated or scat-
. tcrcd ; pseudo-nodule obscure or in-

dtjinitc.

S. jmrvula (K.). — Front view linear,
truncate ; valves broad lanceolate, acute.
KB. p. 64, t. 30. £32. Fresh vratoT. Ger-
many and France. 1-1200". Sometimes
free, sometimes attached and densely
aggregated in a radiant manner.

S. subtilis (K.). — Slender, radiant |
valves naiTow linear-lanocolafe, very
acute. KB. p. 64, 1. 14. £ 2a.=Naricula

OF Tin5 STTRIEELLEiE.

787

Acus, E Inf. p. 176, 1. 13. f. 4. (ix. 147.)

Germany and Fi-ance.

S. dtssipata (K.). — Slender, affixed,
radiant ; front view narrow linear, trim-
cate; valves narrow lanceolate, acute.
KB. p. 64, t. 14. f. 3. = »S'. fasciculata,
EI. t. 17. f. 3. Fresh water. Europe,
Australia, and Asia.

S.famelica (K.). — Delicate, irregularly
aggregated, very narrow linear, tiaincate
in lateral view, front view rather acute.
KB. p. 64, t. 14. f. 8. 1. Fresh water.
Germany. Is a somewhat larger form of
S. dissipata, Rah.

S. radians (Ti.). — Delicate, densely
aggregated, radiant ; front view very nar-
row linear, truncate ; valves nan'ow lan-
ceolate, rather obtuse. KB. p. 64, t. 14.
f. 7. Eiu'ope. 1-600". A minute species.

S. tenuissima (K.). — Very slender,
elongated; fi'ont view exactly linear,
ti'uncate ; valves acicidar, acute. KB.
p. 64, t. 14. f. 6. Stagnant waters.
Germany and France. 1-180".

S. tenuis (K.). — Slender, elongated;
front view exactly linear, truncate ;
valves narrow lanceolate, with some-
what obtuse apices. KB. p. 65, t. 14.
f. 12. Fresh water. Gennany and
France. 1-168".

S. Acula (K.). — Slender, elongated,
lanceolate, in front view truncate, in
lateral view very acute. KB. p. 65, 1. 14.
f. 20. Fresh water. Dalmatia and
France. 1-72".

S. Imvis (E.). — Slightly and irregularly
affixed ; front view slightly attenuated,
timncate; valves more attenuated, ob-
tuse. EA. t. 2. 6. f. 2. Marine. Europe
and America. 1-130".

S. gracillima (Rab.). — Front view
elongated, very naiTow linear ; valves
linear, acicidar, acute. Rab D. p. 53,
t. 4. f. 20 d, e. Dresden.

S. salina (S.). — Valves lanceolate,
gi'aduaUy tapering towards the somewliat
obtuse apices ; strife distinct, 32 in -001".
SBD. i. p. 71, pi. 11. f. 88. Marine.
England.

o. apicidata (Rab.). — Veiy slender ;
valves linear, acicidar, with shortly
tapering apices, faintly striated. Rab D.
p. 56, t. 5. f. 20 a, b, c. Dresden.

_ S, amphicephala (K.). — Slender ; front
view linear, tiiincate; valves narrow
lanceolate, tapering, with capitate apices.
KB. p. 64, t. 3. f. 12. Fresh water.
Germany. 1-360".

B.fontinalis(S.). — Frustides scattered;
valves linear-lanceolate or elliptic-lan-
ceolate, with produced, subcapitate
apices; nodule indefinite; strife 27 in

•001", Sm ANH. 1857, p. 9, pi. 1. f. 9.

Fresh water. Pyi-enees.

S. ffibba (E.). — Smooth, fasciculated,
elongated, narrow linear ; valves broadly
tumid at the middle, with gradually
attenuated, obtuse apices, EA. p. 137.
United States.

S. delicatisshna (S.). — Valves elon-
gated, very narrow, gTadually taperino;
to the subacute apices ; striae 27 in -001' .
SBD. i. p. 72, pi. 12. f. 94. Pseudo-nodule
indefinite.

S. tenera (S.). — Fi'ustules clustered ;
valve nearly linear or attenuated towards
the slightly inflated apices ; nodule inde-
finite ; strife 60 in -001". SBD. ii. p. 98.
Fresh water. Britain. In outline not
imlilie S. delicatissima, but far smaller
and with more delicate stiise, Sm.

S. lanceolata (K.). — Front view nar-
row linear, with slightly dilated apices ;
valves lanceolate, distinctly striated, with
a blank, rhomboid median space. KB.
p. 66, t. 30. f. 31. America. 1-600" to
1-310".

S. debilis (K.). — Minute; fi-ont view
slightly attenuated, truncate, with obso-
letely sti-iated margins; valves lanceo-
late, with produced apices. KB. p. 65,
t. 3. f. 45. = 8. porrecta, Rab D. p. 55,
pi. 4. f. 27. Stagnant waters. Europe,
common.

S. mesolepta (K.). — Delicate; front
view dilated at the ends ; valves lan-
ceolate, ciuwed or slightly sigmoid.
KB. p. 66, t. 30. f. 30, America.
1-lQQP.

S. 7iotata (K.).— Small, with obsoletely
striated margins ; fi-ont -sdew quadran-
gular; valves elliptic-oblong, with ob-
tuse ends. liB. p. 65, t. 3. £ 33. Stao--
nant waters. Eiu'ope. 1-650". °

_S. Martcmiana (K.). — Small, di-
stinctly striated ; front view linear, ti-im-
cate; valves rather broader, lanceolate,
subacute. 103. p. 65, t. 3. f. 9. Marine.
Europe.

S. VauchericB (K.). — Minute; front
view linear, truncate ; valves linear-
lanceolate with somewhat produced
ends, indefinite pseudo-nodule, and 30
marginal strife m -001". KI3. p 65
t. 14. f. 4; SBD. i. p. 73, pi. 11. ^f. Qa
Fresh water, especifilly on species of
Vaucheria. Europe.

S. cpqualis (K.). — Front %-iow dilated
at tlie ends ; valves linear, with roiuided
apices, indefinite pseudo-nodule, and 24
stria3 in -001". KB. p. 00, t. 14. f. 14 =
.S". obtusa, SBD. i. p. 71, pi. 11. f. 92.
Stagnant wfitcrs, Europe. 1-140",

S. invcsticns (S.). — Valves linear
3 E 2

788

SYSTEMATIC HISTOEy

or THE INFTJSOHIA.

sliglitly attenuated towards the rounded
apices, nodide obsolete; strias 26 in
•001". SBD. ii. p. 98. Marine. Scot-
land.

S. acuta (E.). — Fi'ont view exactly
linear, truncate ; valves linear, striated,
suddenly acuminated near the apices.
EA. 1. 1. 2. f. 22. America, Asia, Au-
stralia, and Africa. 1-144".

S. Oxyrhynchus (Ii.). — Front view
lineal' ; valves linear, narrower, suddenly
contracted into a beak at the ends. KB.
p. 66, t. 14. f. 9-11, Germany. Di-
stinguished from 8. acuta by its con-
stricted ends.

S. vitrea (K.). — Front view with di-
lated apices ; valves linear, with sud-
denly attenuated, obtuse ends. KB.
p. 66, t. 14. f. 17. France. Distin-
guished from 8. Oxyrhynchus only by its
dilated ends in the front view, Rab.

S. amphirhynchus (E.). — Large ; front
view linear, not dilated at the ends;
valves contracted into obtuse beaks.
EA. t. 3. 1. f. 25. Fresh water. Eu-
rope, Africa, and America. 1-120" to
1-96". No large, median, smooth space.

S. prcemorsa (E.). — Frontview broadly
lineal-, with truncated, cimeate apices ;
valves linear, with rotmded cimeate ends.
EA. t. 3. 6. f. 11. Mexico.

S. deformis (S.). — Valves lineai* or
linear-eUiptical, suddenly constricted
towards the produced and often distorted
exti'emities ; nodule obsolete; striae 36
in -001". SBD. ii. p. 98. Fresh water.
Sussex.

S. Ulna (E.). — Front view exactlj'
linear ; valves linear, slightly attenuated
near the obtuse apices. E Inf. 1. 17. f. 1 ;
SBD. i. p. 71, pi. 11. f. 90. Fresh water.
Europe, Asia, Australia, Africa, and
America, (x. 184.) 1-280" to 1-100".
Sti-i^ 24 in -001", Sm.

S. spkndens (K.). — Large, elongated;
front view with dilated truncate ends ;
valves lanceolate, obtuse. KB. p. 66,
t. 14. f. 1Q.=8. radians, SBD. i. p. 71,
in part. Fresh water. Europe, Asia,
and Africa. 1-72". Differs from -S.
U/na merely in its dilated apices, Rab.

S. Danica (K.). — Slender ; front view
with dilated, tmncate ends ; valves lan-
ceolate with sliglitly clavato apices.
KJ3. p. 06, t. 14. f. 13. ' Stagnant waters.
Europe. 1-140". Is only a more slen-
der form of 8. splcndms, Rab.

S. mesocampa (Br^b.). — Size and form
of 8. Ulna, but in tlio lateral view Hexed
at the middle. KSA. p. 44. France.

S. capitnla (E.). — Valves linear, with
the extremities dilated into a triangidar

head ; strioe 23 in -001". E Inf. t 21
f. 28 ; SBD. i. p. 72, pi. 12. f. 93. Fresh
water. Europe, Asia, Africa, and Ame-
rica, (iv. 29; X. 185.) Veiv large; lenijth
1-120" to 1-40". b ' b

S. lonyiceps (E.). — Very large, in form
approaching very near to 8. cupitata, but
with stylifomi, produced apices. ERBA.
1845. Fresh water. America, 1-12"
to 1-144",

6 * Frustules attached by a distinct, mostly
pm-sistent, stipes ; pseudo-nodule obsolete
or itidefinite,

t Frustules in fan-shaped clusters on a
short, mostly simple, stipes.

S. Acus ^iitz.). — Slender, smooth;
front view slightly attenuated, truncate ;
valves very naiTow lanceolate, acicular.
KB. p. 68, 1. 15. f. 7. Hamburgh. 1-960".

S.fatniliaris (K.). — Smooth, distinctly
tabellate and flabeUately disrupted ;
fi'ont view slightly attenuated near the
truncate ends ; valves lanceolate, acute.
KB. p. 68, t. 15. f. 12. France. 1-320".

S. pai-va (K.). — Minute, smooth, nar-
row lineal', ti-imcate ; valves narrow lan-
ceolate. KE. p. 67, t. 15. f. 9. Marine.
Italy. 1-960".

S. socialis (Rab.). — ^Front view linear,
with ti'uncated, cuneate ends; valves
lanceolate, distinctly sti'iated. Rab D.
p. 56, t. 4. f. 22. r^-esh water. Italy.

S. Gallionii (E.). — Frustules lai^e, on
a thick, convex stipes ; valves lanceo-
late ; stiise 36 in -001", interrupted by a
median line. E Inf. t. 17. f. 2 ; SBD.
i. p. 74, pi. 30. f. 265. Marine. Europe,
Asia, Africa, and America, (xn. 34, 36.)
1-120" to 1-100".

S. fasciculata (Ag., K.). — Frustules ta-
bulate, on a thick, liemispherical stipes :
front view linear, with subattenuate,
ti'uncate apices ; valves lanceolate. IvB.
p. 68, t. 15. f. 5.=D{afotna fascicid^tum,
Ag CD. p. 51. Marine. Common.

S. tabiaata (Ag., K.). — Frustules large,
on a thick, abbreviated stipes; front
view broadly linear, ta'uncate ; valves
lanceolate, with subcapitate apices ; striae
mai'ginal, 27 in -001". IvB. p. 68, t. 15.
f. 10; SBD. pi. 12. f. 96. = Diafotm
tabulatum, Ag CD. p. 50. Maiine.
Em'ope.

S. a^nis (K.). — ^Frustides subtabulate,
on a hemispherical stipes: front view
slender, linear, witli subattenuate trun-
cate apices; valves lanceolate, acute,
with 32 marginal stnee in -001". KB.
p. 08, t. 15. f. 6, 11; SBD. i. p. 73.
Marine. Em'ope. 1-320". Fruslides ^

OF THE STJRIRELLE^.

789

united iu flabellate or radiating bundles,
Sm.

S. barbatuJa (K.). — Minute, tabulate ;
front %dew linear, ti-uncate, with a ter-
minal mucous appendage; valves elliptic-
lanceolate. KB. p. 68, t. 15. £ 10. 4.
Marine. Em-ope. 1-960".

S. tmncata (Grev.). — Fmstides united
in tablets, obscm'ely stipitate; front
view Imear, trimcate ; valves lanceolate,
obtuse. = lyiatoma and Exilaria truncata,
Grev. ; JEbcilaria fasciculata, Hass. ;
Synedra faseicukita, SBD. i. p. 73, pi. 11.
f. 100. Fresh water, Europe. Striae
40 in -001", Sm.

S. Arcus (K.). — FiTistides flabellate,
attached to a cushion-like stipes ; front
view curved ; valves lanceolate, with 30
marginal strige in -001. KB. p. 68, t. 30.
f. 50 ; SBD. i. p. 73, f. 98. (iv. 27.)
Marine. Em-ope and America.

2 1 Frustides on an elongated, often
branched, stipes.

S. Elirenbergii (K.). — Frastules at-
tenuated near the obtuse apices, tenninal
on a long, linear stipes. KB. p. 69, 1. 11.
f. 6. Fresh water. Berlin.

S. Saxonica (K.). — Stipes a little elon-
gated; fi'iistules slender; fi-ont view
linear, truncate ; valves nan-ow lanceo-
late. KB. p. 68, t. 15. f. 14. Salt Lake
at Mansfeld. 1-330".

S. fulffens (Grev., S.). — Fi'ustides ter-
minal on a thick, branched stipes, ge-
minate linear, trimcate ; valves linear,
inflated at centre and ends ; striae 36 in
•001". SBD. i. p. 74, pi. 12. f. 103.=
Exilaria fulyem, Grev. ; Licmopliora
fidgens, KB. 1. 13. f. 5. Marine. Europe
and America.

S. crystallitia (Ag., K.). — Frustules
very large, on a thickish abbreviated
stipes; valves linear, inflated at centre
and apices ; striae distinct, 26 in -001".
KB. p. 69, t. 16. f. 1 ; SBD. pi. 12. f. 101.
= Diatoma crystallina, Ag. Marine.
Europe. 1-60" to 1-48".

S. superba (K.). — Stipes somewhat
elongated; valves stout, linear-lanceo-
late, with rounded ends ; striae very di-
stinct, 27 in -001". KB. p. 69, t. 15.
f. 13. SBD. i. p. 74, pi. 12. f. 102.
Marine. Europe.

S. Dalmatica (K.). — Stipes somewhat

elongated and branched ; fr-ustules large,
linear, slightly and gi-adually attenu-
ated at the subtruncato ends. KB.
p. 69, t. 12. f. 2. Marine. Adi-iatic Sea.
Frustides terminal on the branches.
1-240".

S. robusta, n. s. — Frustules linear ;
valves elliptical, ends rounded. Striae
20 in -001", intermpted by three equi-
distant longitudmal lines. -0120" to
•0175''. Algae, Corsica, (vm. 3.)

S. gigantea (Lobarz.).— Frustules very
long, delicate, somewhat twisted, linear,
trimcate ; valves very narrow, with di-
lated, obovate apices. Lobarzewsky,
Linnffia, 1840, p. 276, t. 6 ; KSA. p. 48.
Marine. Dalmatia.

7 * Frustules connected in tablets, at
length separating, and adhering by
alternate angles, as in Diatoma.

S. rumpens (Kiitz.). — Tablets affixed ;
fi'ustules very naiTow linear, with tumid
obtuse apices, adhering by alternate
angles. KB. p. 69, 1. 16. £. 6. Brackish
water. GeiTnan coast.

Doubtful species from Ehrenberg.

S. aitstralis. — Linear, striated, with
attenuated, obtuse apices in both views.
ERBA. 1840; Microg. pi. 1. 1. f. 3. In
siliceous schist fi-om the Philippine
Islands. 1-432".

S. paleacea. — Veiy narrow, smooth,
with subacute apices. EM. pi. 1. 1. f. 1.
With the last. 1-480".

S. incurva. — Linear, very naiTow,
flexuose, smooth, roimd, or ec[uaUy
quadi-angular. ERBA. 1844, p. 272.
Bermuda. 1-288". Perhaps a Spongo-
lithis.

S. rostrata (EM. pi. 9. 1. f.4, and pi. 14.
f. 44). — Fossil. France and Gennany.
Valves elongated, slender, linear, with
conti'acted, conic apices, and transverse
sti-iae.

S. elegans, Asia ; S. striata, Asia ;
S. lineata, Asia ; /S, subulata, Africa ;
S. curvata, America.

S. doliolus (Wallich). — Frustules
linear; valve subarcuatc, pseudo-nodule
absent. Striao 30 iu -001". -0020" to
•0050". SalpiX). Indian Ocean, Atlantic.
Wallich, TMS. viii. p. 48, pi. 2. f. 20.

Genus DESMOGONIUM (Ehr.).— We are imacquainted with tlic characters
of this genus ; Ehrcnbcrg's figures of it seem to show a relation to Synedra,
the tablets (aot single frustules) being attached to each other by a connecting
substance, end to end — an arrangement which simulates a filament.

790

SKSTEMATIO HISTOHY OF THE INFUSOKIA.

Desmogonium Ouianense. — EM. t. 34.
5 A. f. 3. Apimrently not very nncom-
niou, since JEhrenberg- gives about 50
habitats in Asia, Africa, and America.

(xv. 13.) Frustules not etipitate; valves
without lougitudinal ridges, mostly
broader than the front view.

Genus DIMEREGEAMMA (N., G.). — Fnistules quadrangular, two or more
together; valves scarcely broader than front view, having the transverse
costte or strife interrupted by a smooth, longitudinal median line. The frus-
tules are united as iu Denticula or Odontidium, from which genera it is
distingmshed by the longitudinal median line. The structure is probably
the same as in Staurosira (E.), the description of which, however, is altogether
inapplicable to many of the species here assembled.

DiMEREGBAMMA minof (Greg.). —
Front view with convex striated margins,
constricted beneath the conic angles ;
valves narrow lanceolate, with fi-oni 18
to 20 strong costfe in ■001". =Denticida
minor, GDC. p. 23, pi. 2. f. 35. Marine.
Scotland.

D. capitatum (Greg.). — Front view
with convex, obscm-ely striated margins,
constricted beneath the dilated roundish
apices. =Dentieidata capitata, Greg I. c.
p. 22, pi. 2. f. 31. Marine. Scotland.
Is larger than Z). nanum, with rounded
apices. Side view imknown.

D. nanum (Greg.). — Front view Avith
convex margins, constricted beneath the
conic angles ; valves broad, obtusely
rhomboid, with rather fine strise. =i)e?j-
ticula nana, Greg I. c. p. 23, pi. 2. f. 34.
Marine. Scotland, (iv. 33.)

D. distans (Greg.). — Front view con-
stricted beneath the conic angles j valves
broad, rhombic-lanceolate, with strong,
short marginal costte, and a lanceolate,
blank median a-pace. = Dentimla distans,
Greg I. c. p. 23, pi. 2. f. 36. Marine.
Scotland. Is larger than D. minor, and
its valves broader, (iv. 34.)

D. Rhombus = Fragilana ? Hhomhus,
EM. pi. 8. 1. f. 16. Fossil. Hungary.
Valves broadly rhomboid, with marginal
costjB, and a smooth median space.

D. fulvum (Greg.). — Front view elon-

fated, with striated margins, constricted
eneath the dilated apices ; valves nar-
row lanceolate, with dilated, subcapi-
tate apices; striaj monihfonn, nearly
reaching the centre. — Denticula fidva,
GDO. p. 24, pi. 2. f. 38. Marine. Scot-
land.

D. mnrinum (Greg.). — Front view
elongated, linear, with striated mai'gins
and slightly produced angles; valves
linear, Avith gibbous middle, obtusely
conic apices, and about 10 coarsely
nionilifonn stri.ne in "OOl". = Denticula
marina, Greg i. c. p. 24, pi. 2. f. 39.
Marine. Scotland.

D. midahile (Sm.). — ^Filaments elon-
gated ; valves oblong or lanceolate, with
20 marginal costse in -001". = Odontidium
midahile, ^BD. ii. p. 17, pi. 34. f. 290;
Fragilaria amphioxys, EM. pi. 39. 3.
f. 53. Fresh water. Em-ope.

D. Leptoceros (E.). — ^Valves rhomboid-
linear, with longly attenuated, acute,
straight ends, finely striated margins,
and a smooth median space. = Fragilaria
Leptocei-os, ERBA. 1844, p. 82 ; Odonti-
dium Leptoceros, KSA. p. 13. North
America.

D. sinuatum (Thwaites). — Front view
linear, tnmcate ; valves rhomboid-lan-
ceolate, with slightly imdulated margins ;
strife delicate, 52 in -001" ; costse inter-
rupted, 10 in -001". = Dentictda sinuata,
SBD. ii. p. 21, pi. 34. f. 295. Fresh
water. Britain, (rs'. 12.)

D. Tabellaria (Sm.). — FUaments fra-
gile ; valves with constricted or inflated
middle, rostrate apices, and 36 delicate
costse in -001". = Odontidium Tabellaria,
SBD. ii. p. 17, t. 34. f. 291. a, valves
inflated at the imidie, = Staurosira con-
struens, Eh.? /3, valves constricted at
the middle, (iv. 35.)

D. birostris (E.). — Very minute; valves
lanceolate, suddenly rostitite, acute ;
striiB interrupted by a median Une.=
Fragilariabirostris, ERBA. 1844, p. 342;
Microg. pi. 38 a. 2. f. 8. Fossil. Ger-
many. 1-3120". Has nearly the cha-
racters of a Staurosira, Eh.

D. informe (S.).— Valves elliptical,
with an* iiTCgular inflation at the centre,
tmd hence subcruciform ; costa3 18 in
•001." = Odontidium informe, S Annals,
1857, p. 10, pi. 1. f. 12. Fresh water.
France.

D. Ilarrisotiii (Sm.). — Fru.stules fre-
quently adhering by t^eir angles; valves
cruciform, with rounded lobes ; cost®
distinct, 13 in -001". = Odontidium ?
Harri,son{i, SBD. ii. p. 18, pi. 60. f. 373.
Fresh water. Hull. The valve,'' m form
resemble tliose of a small Teti-acyclus,

0¥ THE SURIRELLEiE.

791

but have interrupted costae ; the front
view, too, is very dili'erent. (xvin. 6.)

D. 2»'»»(ttu7n (E.). — Valve cruciform,
■with angular lobes ; costse as in D. Ilar-
riso)ui.=Staiirosira pinnata, EM. t. 5. 2.
f. 24 ; Odontidium Harrisonii, /3, Roper,
MJ. ii. p. 6, f. 6. Em-ope and America.
(vjii. 4.)

D. speciosum (Brightwell). — Valve
subcruciform or rhomboidal ; angles
rounded, naked ; costte short, distinct, 16
on each side. = Odontidium speciosum,
Brightwell, JMS. vii. p. 180, pi. 9. f. 8.

Doubtful sjKcies.

D. Surirella = Fraqilaria Surirella,
EM. pi. 39. 3. f. 54. " Frustules large,
broadly linear, with rounded ends and
marginal costte.

D. Baldjickii (Brightwell). — Valve
ovately rhomboidal ; costae about 20 on
each side, distinct, reaching nearly to
the ends, but leaving a linear open space
down the centre, in a clay or earthy
deposit from Baldjick, INIr. Nomian.=
Odontidium Baldjickii, BrighfrsveU, I. c.
p. 180, pi. 9. f. 10.

Genus STAUEOSIEA (Eh.).—" The form of this genus is that of qua-
drangular Fragilarice ; it is distinguished fi-om the much larger forms of the
allied genus Amphitetras by the absence of (pseudo-) openings at the four
angles." — EEBA. 1843, p. 45. The above is the only notice of this genus we
have met with, the resemblance to Amphitetras is evidently very slight.
From Ehrenberg's figui'es, Staurosira seems to contaia forms allied to Odon-
tidium and FragUaria, which have the valve so inflated at the centre as to
appear 4-lobed. This character, however, is uncertain, since Professor Smith
shows that the same species has the valve sometimes inflated, and sometimes
constricted at the middle.

SxAtTROSiEA construens (E.). — Very
small, smooth ; valves spindle-shaped,
with the produced angles somewh.it un-
equal. EM, several figm'es. Asia,
Africa, and America, (xv. 5.) 1-600".
Compare with Dimeregramma Tdbel-
lai'ia.

S. amphilepta (E.). — Minute, smooth,
two of the produced angles larger and
more slender than the others.

S. trujomjyla, Asia; S. Epidendriwm,
ChOi ; S. Mexicana, Mexico ; S. trica-
rinata, Mexico. — These species (Ehren-
berg's) are known to us only by name.

Genus EHAPHONHIS (E.). — Frustules simple, free or shortly stipitate :
front view narrow linear ; valves much broader, with transverse dotted strite
and a median longitudinal Hue. Marine. Ehaphoneis differs from Cocconeis
and Navicula by the absence of a central nodule. The fimstule has no aljE ;
its striae are usually distinctly moniliform and divergent, and its median line
more conspicuous than in TryblioneUa. "We have not thought it desirable to
separate Doryphora ; for it is doubtful whether Kiitzing's only species is even
specifically distinct from some forms still retained by ham in this genus.

Rhaphoneis Amphiceros (Ehr.). —
Valves lanceolate, about three times
as long as broad, with produced, styli-
fonn apices, and fine, dotted transverse
striae. ERBA. 1844, p. 87 ; M. t. 18. f.
82. = Cocconeis Amphiceros, E. 1840 ;
T)oryi)hora Amphiceros, KJ3. p. 74 ; SBD.
i. pi. 24. f. 224. Marine. Europe and
America, (xiv. 21.) 1-576". Striae 18
to 20 in 1-1200". Ends suddenly con-
tracted and prolonged into a beak.

R. Fusus (*E.).— Valves slender, linear-
lanceolate, usually fom- times as long as
broad, ^vith styliiorm apices, and 17 or
18 fine, transverse, gi-anulated strias in
1-1200". ERBA. 1844, p. 87. Fossil.
Virgmia. 1-720". Strongly akin in habit
to Fruf/ilaria Amphiceros, )mt differs by
its median suture.

R. Lqitoceros (E.). — Valves long
lanceolate, quadi-angular, rhomboid, three
times as long as broad, with long styli-
form apices and fine, granulated trans-
verse sti-iae. ERBA. 1844, p. 87.=i2.
Orer/onica, EM. pi. 18. f. 83. Fossil.
America. 1-720". Striae generally 18
in 1-1200". Has the habit of Ii. A i>ij}hi-
ceros, but with much longer bealcs.

R. f/emmifcra (E.).— Large; valves
elongated lanceolate, with lon^ gi-adually
attenuated apices, usually three times
as long as broad ; striae strongly granu-
lated, 10 in 1-1200". ERBA. 1844, p. 87.
Fossil. Maryland. 1-300".

R. pretiosa (E.). — Lai-ge ; valves
broadly lanceolate, rhomboid, generally
twice as long as broad ; apices gradually
attenuated into benks; striic stout, gnvmi-

792

SYSTEMATIC HI8T0ET OF THE INFTJSOEIA.

lar, like series of pearls. ERBA. 1844,
p. 87. Fossil. Maryland. 1-480". Strife
11 in 1-1200",

R. Rhombus (E.). — Small ; valves
broadly lanceolate, rhomboid, sometimes
suborbicular, scarcely longer than broad,
with short rostrate apices and fine gra-
nulated striae. ERBA. 1844, p. 87 ; M.
pi. 33. 13. f. 19. Cuxhaven, Virginia.
1-1152" to 1-864". Sti-i£e 20 to 21 in
1-1200".

R. scalaris (E.). — Valves slender,
acutely lanceolate, fiu-nished with a
double series of stria3 and window-like
crystalline spaces. ERBA. 1844, p. 271.
Fossil. Bermuda deposit. Diameter
1-960". Strii-e 9 in 1-1200".

R. angusta (E.). — Valves elongate
lanceolate, with obtuse apices, 24 strias
ill 1-1200", and no median smooth space.
ERBA. 1844, p. 364. India.

R. lanceolata (E.). — ^Valves rhomboid-
lanceolate with obtuse apices, 21 striae
in 1-200", and a linear-lanceolate median
smooth space. ERBA. 1844, p. 364;
M. pi. 34. 7. f. 13. India, China, and
Japan.

R. Indica (E.). — Valves elliptic-
lanceolate with obtuse apices, 15 striae
in 1-1200", and a linear-lanceolate
median space. ERBA. 1844, p. 365.
India and Japan.

R. fasdnluta (E.), — Large ; valves
elliptic-lanceolate, twice as long as broad,
with strong, finely granulated striae in
transverse fasciae. ERBA. 1844, p. 204:
M. pi. 35 A. 22. f. 16. Antarctic Sea.
Ehrenberg's figure represents the valve as
elliptic, with transverse band-like series
of short longitudinal striae, alternating
with smooth spaces, and inteiTupted by
a •smooth longitudinal median line.
(? Lower valve of a Cocconeis.)

R. Smtellum (E.). — Valves elliptic,
longer than broad, with 12 or 13 stout,
crenidated striaj in 1-1200". ERBA.
1844, p. 204 ; M. pi. 35 a. 1. f. 5. Ant-
arctic Sea. 1-864". (? Lower valve of
a Cocconeis.)

R. fasciata (E.). — Microg. pi. 35 a. 9.
f. 8. India. Valve elliptic, with broadly
rounded ends, a median line, transverse
fasciae of longitudinal lines alternating
with smooth ti'ansverse bands, and two
series of marginal stiiae. (? Lower valve
of a Cocconeis.)

Species (Eh.) known to us only by name.

R. setacea, Sandwich Islands ; R.
Entomon, Asia Minor; R. rhomboides,
Ganges ; R. Gangetica, Ganges ; R.
Icevis, India ; R. A fncana, South Africa ;
R. Digitus, Demerara.

Genus TEYBLIONELLA (S.). — " Frustules simple, free, eUiptical or
Unear ; valves plain ; alse submarginal or obsolete, canaliculi inconspicuous,
parallel." — Smith. Tryblionella is another genus separated fi-om Surirella
by Professor Smith, who says that it " differs from Campylodiscus ia the more
elongated form of its frustules and the absence of the bend in its valves ; the
canaliculi are also more minute, and parallel rather than radiating. It agrees
with Surirella in the presence of alee ; but these arise fi-om the disk." Mr.
Roper considers that Tryblionella is distinguished fi-om Surirella by its fine
(often obsolete), parallel transverse strife ; whereas the latter is fui-nished with
canaliculi or costaj, which are more or less divei'gent.

Tryblionhlla circiimsuta (B.). —
Lateral view elliptic-oblong, with a faint,
longitudinal median line (indistinct or
obsolete), parallel transverse striae, and
marginal gland-like dots; alae very
8\\ctYt. = Surirella cii-cmnsJita, Bailey, MO.
pi. 2. f. 36 ; T. Scutellum, SBD. i. p. 35,
pi. 10. f. 74. Marine. America, Britain.
Professor Bailey describes it as having
a minutely granulate sm-face, and a
scarcely perceptible median constriction.

T. gracdis ( S.). — Front view linear, with
attenuate extremities and truncate apices;
lateral view linear-acuminate ; costro

Sarallel, e.xtending to median line ; alae
istinct. SBD. i. p. 35, pi. 10. f. 76. Fresh
and brackish water.s. Lewes, (iv. 36.) I

T. navicidaris (Br<5b.). — Front view
oblong, with trimcate, slightly winged
ends; lateral view eUiptic-aciuuinate ;
costae distinct, mai-ginal ; aire con-
spicuous. = Surirdla navictdaris, BnSb. in
KSA. p. 36 ; T. marginata, SBD. i.
p. 35, pi. 10. f. 76. Fresh and brackish
waters. Fi-nnce ; Eugland.

T. acuminata (S.). — Lateral •N-iew
linear, with attenuated ends and delicate,
interrupted transverse striaj; alas obso-
lete ; canaliculi obscure. SBD. i. p. 36,
pi. 10. f. 77. Marine and brackish
waters. Britain. -0012" to -0021".
Striic 31 in -001". (iv. 37.)

T. angustnta (S.).— RescmblcsT. acttmi-
nata ; liut its stria) are continuous. SBD.

OF THE SUEIRELLEiE.

793

p. 36, pi. 80. f. 262. Fresh water. England.
•0021" to -0040". Striaj 36 in -OOl".

T. levidemis (S.). — Lateral view linear,
with subacute exti-emities ; costse very
distinct, parallel, extending to the cen-
tral line. SBD. ii. p. 89. Brackish
water. Cork City ParK.

T. punctata (S.). — Lateral view ellip-
tic, with acuminate ends and parallel,
transverse, moniliform strise ; canaliculi
obsolete. SBD. i. p. 36, pi. 30. f. 261.
Marine. Sussex.

T. comtricta (Greg.). — Lateral view

panduriform, with apiculate ends and
numerous, delicate, diagonal, punctated
striae; costa obsolete. Greg, in MJ.
iii. pi. 4. f. 13. Marine. Britain. " Its
foi-m is that of Cyinatopleura Soka, but
it is very much smaller.". — Greg.

T. apiculata (Greg.). — Narrow, linear,
slightly consti'icted in the middle, vdth
apiculate extremities and about 45 fine
but distinct, ta-ansverse, dotted striae in
■001". Greg, in MJ. v. p. 79, pi. 1. f.
43. Scotland. -0015" to -0017". Keel
often strongly marked.

Genus CYMATOPLEURA (S.).— Frustules free, in front view linear, with
undulated margins ; laterally broader, and marked with transverse bars.
Aquatic. This genus, instituted by Smith, is very distinct, and may be
recognized by the lateral surfaces projecting in the front view in an undu-
lated manner, the central portion being separated from the undulations by a
marginal row of dots. The lateral view is usually very much broader than
the front, which often renders it difficult to obtaia a satisfactory sight of the
latter. The lateral siufaces, however, sufficiently identify the genus, as the
broad, transverse, shade-Kke bands or bars which correspond with the undu-
lations are characteristic. The striae are generally obscure or obsolete, and
the median longitudinal line is less evident than in Surirella ; the margia
is usually furnished with conspicuous gland-like dots. " The undulations of
the valves separate Cymatopleui-a from TiyblioneUa and SurireUa ; the absence
of alae and canaliculi are fui'ther characters which leave no room for hesita-
tion as to its distinctness." (Smith.)

Cymatoplktjra Solea (Br(§b., S.). —
Frustule elongate; laterally pandmi-
form, with more or less attenuated ends,
sometimes apiculated ; stiiae delicate, 8
in 1-1200". SBD. i. p. 36, f. 78. = Surirella
Solea, Breb. in KSA. p. 34 ; S. Librile,
E. ; Sphinctocystis librilis, Hass BA.
p. 102, 3. Var. /3, ends apiculated, = C.
apiculata, S. I. c. p. 37, f. 79. Common,
Asia, Africa, America, Europe, (rx. 155 ;
XVI. 9.) Frustules, in both views, many
times as long as broad ; undulations six.
The ends, in the lateral view are always
attenuated ; but their apices vary, and are
sometimes obtuse, sometimes apicidate ;
and therefore we concm* with M. de Brt5-
bisson in uniting C. apiculata. Smith,
with this species.

C. hcterocyma (Niigeli). — Lateral
yiewpanduriform, with 16 marginal striie
m 1-1200" ; front view broadly linear,
twice undulately twisted, with six mar-
ginal folds. = Surirella heteroa/ma, KSA.
p. 889. Switzerland. 1-240".

C. elliptica (Brdb., S.). — Lateral view
elliptic, with three to five transverse bars ;
ends, in general, sliglitly attenuated.
SBD. p. 37, pi. 10. f. m. = Surirella oo-
plmna, E. (according to Kiitzing) ; S.
imdulata, EM. ; S. undata, EM. ; S. pli-

cata, EM. pi. 15 a. f. 50, 51?; S.
Kiltzitu/ii, Perty, Diat. p. 201, t. 17. f. 2.
Aquatic. Asia, Africa, America, Europe,
(rx. 149 ; xvi. 7, 8.) Professor Kiitzmg
describes the fruatides as ovate ; but we
have always found them elliptic. Un-
dulations three to five; lateral sm-faces
obscurely striated and furnished with
marginal gland-like dots. We have re-
fen-ed the Surirella plicata, E., to this
species, because of its habitat, although
its figure in the ' Microgeologie' agrees
better with that of C. Hibcrnica.

C. Hiheniica (S.). — Lateral view
broadly elliptic, with, produced ends ;
striae obscure. SBD. i. p. 37, pi. 10. f.
81. Ireland, France. Undulations about
three; length 1-.370" to 1-220" ; breadth
two-thirds the length.

C. Rec/ula (EX — Lateral view linear,
witli cuueate ends and six transverse bars.
= Surirella Rcx/ula, KB. t. 28. f. 30. ; C.
parallela. Smith, BD. pi. 30. f. 263.
Mexico, France, England. Habit and
size of C. S)lea, but not panduriform ;
pinnules 10 in 1-1200", nearly obsolete.

C. Ovum (Niigeli). — Lateral view
broadly oval, with 8 marginal strijc in
1-1200"; front view broadly liuear,
straight; margin with five ' marginal

794

SYSTEMATIC HISTOUY OF THE INFUSOEIA.

folds. = Sunralla Ootcm, Nfigeli in KSA.
p. 889. Switzerland. 1-360" to 1-280".

The characters given are insufficient to
distinguish it from C. elUptica.

Genus SURIEELLA (Tm-p., E., S.). — Frustules simple, free; margin
striated; lateral surfaces broader than. the front view, with a smooth median
longitudinal line ; " margins produced into alaj, canaUculi distinct, usually
parallel" (Smith). SuiireUa thus limited by Professor Smith becomes a much
more natural genus than it was constituted by preceding authors : he says,
" It is well distinguished from TryblioneUa by the prominency of its alaj, the
distinctness of its canaliculi, and the usually cuneate form of its frustules ;
with no other is it at all likely to be confounded."

few, reaching tlie median line, central
ones divergent. SBD. pi. 9. f. 67. Aquatic.
Australia, Asia, Afiica, America, Britain.
(XII. 19, 20.) Costaj 7 in 1-1200".
1-288". The central cost^e are usually
more distant, leaving a ti'ansverse smooth
space bisected by the median line.
Smaller than S. hiseriata ; its costse fewer
and more divergent.

S. megaloptera, EM. pi. 33. 1. f. 17.
Egypt. The figm-e resembles that of
S. Craticula ; but the costiB are all paral-
lel, and the median line, as well as cost®,
are inten-upted at the centi-e by a broad,
ti'ansverse band.

S. hiseriata (Breb.). — ^Front view qua-
di'ilateral, vsith conspicuous alas ; lateral
view oblong-lanceolate, with broad costre,
which usually reach the median line.
SBD. i. p. 30, pi. 8. f. 57. hifrom, E.
Common, (xvi. 20-26.) Diliers from
S. splendida by its parallel sides in front
view. Its angles are roimded, and the aloe
enclose an oblong space; its costte ai"e
conspicuous in both -saews. 1-210" to
1-100". Sti-ifB ^ in 1-1200".

S. decora (E.). — Large, linear-lanceo-
late, with equal, attenuated ends and
fom- or five marginal costas in 1-200".
EM. pi. 5. 3. f 23. America, Ireland.
Ehrenberg's figures are oblong lanceo-
late, one of them constricted.

S. rcjlexa (E.). — Lanceolate, with
nearly equal, slightly refiexed, subacute
ends, a distinct median suture, and strong,
short striae, in the middle throe or foiu*
in 1-1152". EM. pi. 33. IL f. 13. FossU.
Connecticut.

S. leptoptera (E.). — Lanceolate, with
nearly equal, acute ends, a distinct, di-
lated median sutm-e, and dense trans-
verse strias, which in the middle are
6 in 1-1152". KSA. p. 36. FossU.

* Frustides panduriform,

SuBLRELLA coHstricta (E.). — Large,
oblong, in lateral view pandm-iform, with
a median line and intramarginal crena-
tions. EM. pi. 14. f. 37. Denticula con-
stricta, KB. t. 3. f. 62 ?. Aquatic. Berlin,
(xm. 3.) Ehrenberg's figure in the 'Mi-
crogeologie' seems a ti-ue species of this
genus; and difierent as is that of Denticula
constricta in Kiitzing's work, yet, as it was
copied from a figm-e given by Ehrenberg
in an earlier work, the ditferences are pro-
bably due to the imperfect representation.

S. Smithii (K.). — Front view broadly
linear, with trimcate ends and rounded
angles; lateral view pandmiform, with
attenuated ends ; costse delicate, reach-
ing the median line, which is often in-
flated. = S. cotistricta, SBD. i. p. 31, pi, 8.
f. 59. Brackish water. England. Alse
conspicuous, enclosing an oblong space.
1-300". The shape, in fi'ont view, re-
sembles that of S. hiseriata, but the costre
are much finer.

S. Antarctica, EM. pi. 35 a. 2. f. 20.
Antarctic Sea. We have seen no de-
scription of this species. Ehrenberg's
figure shows the lateral view panduri-
fonn, with roimded ends and strongly
marked strice, which nearly reach the
median line.

S. clidy77ia (K.). — Oblong, with ti-un-
cate ends, constricted middle and punc-
tated margins. KB. p. 60, t. 3. f. 67.
Submarine waters. Isle of Wangeroog.
1-000". This appears to us a doubtful
species of Surirella ; for Kiitzing's figm-e
seems to represent a frustulo constricted
in the front view, as it shows a lineai-
median portion truncated at its ends.

S. panduriformis (Rab.). — Resembles
S. didyma, but is stouter, and its mar-
ginal dots appear stalked. Rab. p. 29,
t.3. f.9. Italy.

2 ♦ Lateral vieto lanceolate or ohlonp, with
its ends usually equally attenuated.

S. Craticula (E.). — Lanceolate; costse

m

Oregon. A specimen 1-466" long pre-
sented 21 striae.

S. Oregonica (E.). — Spathulate, with
unequal, subacute cuds, a distinct, di-
lated median suture, and strong striae,
which in the luiddle are four or five in

OF THE StTBIEELLEiE.

795

1-1152". EM. pi. 38. 12. f. 27. Fossil.
Oregon. A speciaien 1-336" long pre-
sented 19 striiB. Ehrenberg's figiu-e is
elliptic-lanceolate, with a median line
dilated at the centre into a large oval
fomi ; the stiia3 short and externally ter-
minating in gland-like dots.

S. turgida (S.). — EUiptic-lanceolate,
with tapering, sometimes contracted
ends and obtuse apices ; costse few (4 in
•001"), conspicuous, separated by a me-
dian lanceolate space. SBD. i. p. 31,
pi. 8. f. bQ. = S. Calcdotnca, EM. pi. 15 a.
t. 47 ? Aquatic. Ireland. Distinguished
by its ventiicose centre.

S. oblonga (E.). — Oblong-lanceolate,
with obtuse ends, near the margin si-
nuoso-dentate. KSA. p. 35. Aquatic.
Afi-ica; America; Mom-ne deposit, Ire-
land. Ehrenberg's figiu'es in the 'Micro-
geologie' differ very much in form, but
all have the costce confined to the
margin.

S. Breuteltana (Rab.). — Linear-elliptic,
with rovmded ends, five transverse costae
on each side, connected at inner ends by
an imdidated line, and leaving a longi-
tudinal median space with waved mar-
gins. Eab D. p. 29. t. 3. f.l3. Aquatic.
St. Kitts.

S. crenidata (E.). — Small, eUiptic-lan-
ceolate, with crenulate margins, subacute,
nearly equal ends, and a distinct median
line ; eleven crenules in 1-1152", extend-
ing into striae, which do not reach the
centre. EM. pi. 33. f. 23. Fossil, United
States. D. 1080".

S. mia-ocm-a (E.). — Minute, oblong-
lanceolate, with somewhat acute apices,
and marked near the margin with ten
delicate dentations in 1-1200". EA.
p. 136, t. 2. 1. f. 34; KB. t. 29. f. 15.
Asia, Afi-ica, America.

S. lepida (E.). — Slender, linear-lan-
ceolate, one end obtuse, the other a little
more attenuated and subacute ; striae nine
or ten in 1-1152"; the median lino di-
stinctly flexuose. ERBA. 1844, p. 272 ;
KSA. p. .36. Kui-distan. 1-7G8".

S. tenella (K.). — Oblong-lanceolate,
with rounded, obtuse apices, and five,
rather lax ti-ansverse stria) in 1-1200" ;
front view oblong, almost rectangular,
with obtuse angles. KSA. p. 37. Aquatic.
Prussia.

S. obtmangida (Rab.). — Small, lan-
ceolate, with cuneato, attenuated, obtuse
ends, and six short costa) in 1-1200";
front view oblong, broadlv rounded. Rab.
P- 29, pi. .3. f. 27. Aquatic. Germany.

S. Aniphinxi/s (S.). — Elliptic-lanceo-
late, with subacute extremities, and nine

costffi in -001" ; front view linear. SBD.
ii. p. 88. Haverfordwest.

S. angusta (K.).— Minute, linear, with
cuneate ends, rather obtuse apices, and
11 costse in 1-1200" ; alse obsolete ; fi-ont
view lineal', truncate. KB. t. 30. f. 52 ;
SBD. pi. 31. f. 260. Aquatic. Eui-ope ;
Lewes.

S. apiculata (S.). — "EUiptical, ovate,
smaller extremity produced into a linear,
truncate apiculum; costse 15 in •OOl"."
SBD. ii. p. 88. Aquatic. England.
Length of frustide -0008" to -0012". " A
close aUy, if not a vai-iety, of S. angusta."

S. linearis (S.). — Minute, linear, with
cimeate ends, distinct transverse costse,
and a narrow median line. SBD. i. pi. 8.
f. 58=". = S. acuminata (Br(5b. MS.).
Aquatic. England, France. Var. /§,
slightly constricted at the middle, S.
p. 8. f. 58='". In the front view this
species resembles a small form of S.
hiseriata.

3* Lateral view with one end broadly
rounded, the othe)' smaller (ovate or
ovate-oblong) ; front view usually cu-
neate.

S, robusta (E.). — Large, elongated;
ovate-oblong, with two stout costse
(which do not reach the centre) in
1-1200". EM. pi. 15 A. f. 43. -S-. nobilis,
SBD. pi. 8. f. 63. Aquatic. Fossil. Fin-
land; Britain. 1-216" to 1-120". Di-
stinguished by its large size, elono-ated,
slightly tapering foi-m, and large mtra-
marginal crenations.

S. procera, EM. pi. 14. f. 33. Berlin.
The figure represents a large species,
slightly broader at one end, with large
intramarginal crenations as in S. robusta,
but the sti'ong transverse costas are sepa-
rated only by a naiTow median band.

S. splendida (E., K.). — Front view
cuneate, with romided angles and pro-
lono^ed costse ; lateral view ovate-oblong
with conspicuous, diverging costffi which
reach the median line ; also distinct.
EM. t. 15 a. f. 44; SBD. i. pi. 8. f. 62.
Aquatic. Common, both living and fossil,
(ix. 150-152.) Var. /3. linearis, smaller,
lateral view narrow, slightly tapering, =
S. linearis, SBD. i. pi. 8. f. 58 a. 1-210"
to 1-100". As tlie front view has rounded
angles, it is not unlike the lateral one in
outline, but the ends are broader. Two
or three times as long as broad.

S. te^iera (Greg.). — Narrow linear-
oblong, Avith one end more tapering than
the other; costio distinct, reaching the
median line. Greg MJ. iv. p. 10, pi. 1.
f. 38. Scotland. It is smaller than S.

796

SYSTEMATIC niSTOBY OF THE CSTUSOBIA.

sphndida, and its aire are less conspi-
cuous; but it resembles that species in
form, and we doubt whether it be
distinct.

S. striatula (Turp.). — Fi'ont view broad
cuneate, with rounded angles and short
costiB ; lateral view ovate, wth distant,
curved costse, which reach the median
line; aire smaU. SBD. i. pi. 9. f. G4.
Common. Resembles S. sple)idida, but
is shorter in proportion to its breadth.
In the front view the central portion is
broader, the ends more ti'uncate, the
costaj shorter, and the alse less conspi-
cuous. Lateral view faintly striated;
sh-ise 8 to 13 in 1-1200".

S. limosa (Bai. MS. ?). — Broadly ovate
acimiinate, faintly punctato-striate ; ca-
naliculi short and mdistinct, not reach-
ing more than 1-6" across the valve ;
length -0073", breadth -0035" ; stiiai in-
distinct, 22 in -001. New Zealand, Hud-
son River, New York, Thames mud.
Bri JMS. vii. p. 179, pi. 9. f. 5.

S. hrevis (E.). — Short ; form and size
of S. striatula, but with 16 finer sti-iae in
1-1200". ERBA. 1844, p. 272 ; KSA.
p. 39. Km-distan. 1-912".

S. Testudo (E.). — Lar^e, ovate, obtuse,
with 12 slender striae in its length, which
is 1-288". E I.e. 1840, p. 24; KSA.
p. 39. Marine.

S. Gemma (E.). — Fi'ont view narrow
cuneate ; lateral view broader, ovate-
elliptic, faintly striated between the de-
licate, unequally distant costte, which
reach the median line ; alse inconspi-
cuous. KB. t. 7. f. 9 ; SBD. i. pi. 9. f. 65.
Common in marine marshes, (xii. 2-4.)
Distinguished from S. striatula by its
much finer costse and less conspicuous
alcB, which in the lateral view generally
coincide with the margins. Sometimes
nearly elliptic. We have rarely seen it
so narrow as Professor Smith's figui-e
represents it.

S. Imwiata (E.). — Elongated, smooth,
with subequal, obtuse ends, a distinct
median suture, and two longitudinal
lateral lines. KSA. p. 36; EM. t. 33. 14.
f. 24. Fossil. United States, 1-168".
Ehrenberg's figure in the 'Microgeologie'
is ovate, with a median line, lax intra-
marginal crenations, and very sliort

COStfO.

S. Chiatimahnsi'i, EM. pi. 33. 6. f. 7.
America. Figure broadly ovate, with
both ends much rounded, and minute
intramarginal crenations, without me-
dian line or costfe.

S. ifhlhyoci-jihala (Rab.). — Lnrgp,
ovate-oblong, with rounded ends, three

broad, flexuose costaa in 1-1200" and a
broad linear median band. Rab D. p. 30,
pi. 10, Supp. f. G. Italy. The figure
shows the costte cm-ved, except the
middle one, which is broader and
straight.

S. cordata (E.). — Ovate-subcordate,
with four lax striai in 1-1152", conti-
guous in the median line. ERBA. 1846,
p. 272 ; KSA. p. 39. Fossil. Georgia.

S. prcetexta (E.). — Long ovate, more
than twice as long as broad, \rith five
rather lax stria3 in 1-1252", towards the
middle broadly interrupted and not con-
tiguous in the median line, hence form-
ing four series with a broad linear me-
dian space and two smooth lateral ones.
Maritime. Lidia. ERBA. 1845, p. 365 ;
KSA. p. 38.

S. eughjpta(E.). — Small, ovate-oblong,
with seven striae in 1-1200", which do
not reach the centi-e ; front view cuneate,
with rounded angles at larger end. EA.
p. 136, t. 3. 5. f. 2. 4; KB. t. 28. f. 27.
Asia, Africa, America.

S. uninervis (E.). — SmaU, ovate, half
as long again as broad; costae reticu-
lated at the margin, contiguous at the
slender median line, 7 in 1-1152". KSA.
p. 38. Maritime. India, Africa.

S. Folium (E.). — Ovate, turgid and
obtuse, slightly compressed, with 24 fine
striae in 1-1150". Fossil. Barbadoes.
1-540".

S. Crumma (Brt5b.). — Small, orbicular
ovate, with 7 or 8 evident marginal
striae in 1-1200". KSA. p. 38. Aquatic.
France, Britain. Its suborbicular form
in lateral view distinguishes it from
every other species except S. Bright-
tcellii.

S. BrightwelUi (S.). — Small, suborbi-
cular, with one end subacute ; costse
distinct, marginal, 10 in -001"; alai in-
conspicuous. SBD. i. p. 33, pi. 9. f. 69.
Britain. According to Professor Smith,
this species is distinguished from & Cni-
mena by its coarser and more prominent
costae and distinct sti-ite ; S. Urumena is
also smaller and more orbicular.

S. oralis (Br(5b.). — Small, ovate-elliptic,
with 8 marginal costae in 1-1200", and
one end more attenuated than the otlier ;
alaj inconspicuous. KSA. p. 33 ; SBD.
pi. 9. f. 68. Aquatic. France, Britain.
Front view oblong-cuneate, truncate.
1-360" to 1-280". Margin vnt\i very
short, teoth-like costaj. The lai-ger end
in lateral view is leA" rotuidod than in
the allied .species.

S. orata (is..). — Minute ovale, or ovnfe-
ellipdc, with 7 to 9 delicate, very short,

OV THE SUEIEELLE-ffi.

797

mai'^nal costae in 1-1200"; alee incon-
spicuous. KB. pi. 7. f. 1-4 ; SBD. pi. 9.
f. 70. Em-ope, America. Front view
broadly cuneate, truncate. 1-1200" to
1-560."

S. minuta (Br6b.). — Minute, ovate-
elliptic, with inconspicuous alae and 14
niai-ginal costae in -OOl". SBD. i. p. 34,
pi. 9. f. 73. France, England. -0005" to
•0009". Kiitzing unites this fonn with
S. ovata; but M. de Br6bisson informs
us that he is able to distinguish the two
species when in situ at the fii-st glance ;
that the stratum of this species is black
and very mobile, whilst that of S. ovata
is brown, and adheres more firmly to
the son.

S. salina (S.). — Minute, ovate-oblong,
vrith numerous minute marginal costae
and obsolete alae. SBD. i. p. 34, pi. 9.
f. 71. Marine or brackish waters. Eng-
land. Fi'ont view wedge-shaped.

S. suhsalsa (S.). — Minute, ovate-lan-
ceolate, with 8 distinct costae and 30
striae in 1-1200" ; alae conspicuous. SBD.
i. p. 34, pi. 31. f. 259. =S. pygmcBu, EM.
pi. 35 A 8. f. 4 ? Fresh or brackish
waters. England.

S. pinnata (S.j. — Minute, narrow,
ovate-oblong or somewhat clavate, with
large, subdistant marginal costae ; alae
obsolete. SBD. i. p. 34, pi. 9. f. 72.
Aquatic. Lewes. Front view narrow
cuneate.

4 * Lateral view with broadly rounded,
rarely unequal, ends.

S. Lamella (E.). — Large, narrow
elliptic, with nearly equal, broadly
rounded ends; intramarginal striae and
granulose median area ; fi'ont view nai'-
row linear, tnmcated. EM. pi. 15 a.
£ 49. Lough Moume deposit. 1-216"
to 1-180". Ehrenberg's Hgure has no
median line.

S.itosoma(E.). — Narrow elliptic, with
broadly roimded. ends, a narrow margin
of tine strias, and a smooth median area
with a median longitudinal line. EM.
pi. 33. 14. f. 25. Maritime. India. Three
times as long as broad.

S. Patella (K.). — Elliptic-oblong, with
equal, roimded ends, ancl four or five mar-
^nal striae in 1-1200". I03. t. 7. f. 5.
Fossil at Franzensbad.

S. Peruviana (E.). — Large, elliptic-
oblong, with equal, rounded ends, and
about l2 very short, obsolete, marginal
costae in 1-1200". KB. t. 29. f. 72. Peru.

S. amphiamhlya, EM. pi. 14. f. 34.
Berlin. The figure shows a large elliptic
form with equal, rounded ends, intra-

marginal crenations, and strong, parallel,
transverse costae, which do not quite
reach the median line.

S. Mississipica, EM. pi. 36 A. 8. f. 5.
America. Ehrenberg's figure is large,
eillptic-oblong,with equal, xounded ends,
and parallel transverse costae, separated
by a nan'ow linear, longitudinal median
band.

5 * Lateral view with rounded ends ; costce
with dilated outer portion, and median
space finely striated.

S. fastuosa (E.). — Elliptic, with
roimded ends, rather distant costa3, in-
flated towards the margin, and a trans-
versely striated, lanceolate median space.
Greg M J. iii. p. 30, pi. 4. f. 41. Maiine.
Common. Europe, Asia, Afiica, Ame-
rica. Distinguished from all the pre-
ceding species by its inflated costae re-
sembling stalked flowers, and by the
striated median space, which is veiy
variable in breadth. Diflers much in
size, and is sometimes nearly orbicular ;
we have never seen it o-\'ate, as described
by Professor Smith.

S. lata (S.). — Large, broadlj^ linear-
elliptic or somewhat panduriform, with
broadly rounded ends, a ti-ansversely
striated median area, and distant costae
externally dilated. SBD. i. p. 31, pi. 9,
f. 61. = Campylodiscus jjroductus, John-
ston. Marine. Notimcommon. England.
Differs fi-om S. fastuosa in its form, and
usually in its larger size ; but the mark-
ings are similar in both. As Professor
Gregory finds Intel-mediate states, they
may be, as he supposes, mere varieties.

S. eximia (Grev.). — Linear-oblong
with roimded ends, about 18 delicate
costae on each side, reaching the naiTow
Imear-lanceolate, transversely striated
median space. Grev MJ. v. p. 10, pi. 8.
f. 6. Marine. West Indies. This ex-
tremely delicate and hyaline Diatom,
Dr. Greville informs us, approaches S.
lata in fonn, slight consti-icrion, and a
striated central space, but difiers in every
other respect. The costae equidistant,
and as fine aa those oi S. Gemma; alje
naiTow, but conspicuous.

Bouhtfid or undescnbcd Species.

S. ? Cocconeis, EM. pi. 35 a. 8. f 3
Marine. India, Africa. This species'
according to the tigure, is small, elliptic
Avith obtuse ends, and pai-nllel transverse
costae separated by a smooth, narrow-
lanceolate median space.

S. Jennvri (Hassall). — Front view
linear, with roimded ends, and distant.

798

SYSTEMATIC lUSTOaT OF THE INFUSOKIA.

short, teeth-like mai'ginal costse. Haas.
Br. Algffi, p. 439, pi. 102. f. 15. Aquatic.
Sussex. Dr. Ilassall describes it as a
very distinct species, having no relation
with S. biseriata.

S. ambigua. (K.). — Broadly oblong,
with truncated ends, and 4 straight, ob-
solete, rather broad ti'ansverse striae in
1-1200". KB. t. 5. f. 17. Stagnant waters,
Switzerland. 1-264". Kiitzing's figure
apparently represents the front view, and
is broadly linear, with obsciu'e transverse
costiB, leaving a naiTow median portion.

S. IcBvis (K.). — Cylindrical, elliptic-
lanceolate, somewhat obtuse, very smooth
and hyaline. KSA. p. 36. Marine. France.
1-1080".

S. attenuata (TS'ag.). — Smooth, lineai'-
lanceolate, with gradually attenuated
apices. KSA. p. 889. Switzerland.
1-240". Perhaps a Tiyblionella ?

S. ? ornata (K.). — Elongate, pestle-
shaped, tnmcate at each end, with obtiise
angles, longitudinally dividuate, and or-
namented with minute pimcta disposed
in decussating lines. KB. t. 3. f. 54.
Marine. Genoa. Lengthl-280"; breadth
1-960". Kiitzing's figiu-e is linear-oblong
with trimcate ends, and seems to repre-
sent the front view, in which the striated
lateral portions approach so closely at
the centre that the smooth median por-
tion is visible only near the ends. Sm-ely
this is not a Siurirella ?

S. ? Amphtbola (E.). — Broadly linear,
with cuneate, subacute ends, and 15 stria3
in 1-200"; front view with obtuse ends.
ERBA. 1854, p. 271. Kurdistan. 1-324".
Has the general form of Tryblionella
Rec/ula. Ehrenberg remarks that he is
not sure to what genus this belongs ; he
has sometimes fancied there was an um-
bilicus, as in Pinnularia, bvit its equal
ti'ansverse strias on each side render its
form singular.

S. Simla (E.). — Smooth, broadly na-
vicidar, with subacute ends and longi-
tudinal marginal lines. EM. pi. 22. f. 58.
Fossil. Sicily. 1-528".

S. liolepta (E.).— Stvliform, four times
as long as broad, with obtuse ends and
no median line ; the narrow margin finely
striated. KSA. p. 36. Maritime. India.
1-360".

S. ? linea (E.). — Bacillar, stout, one
side cuneate at each end, the other
rounded, finely transversely striated
throughout. ERBA. 1843, p. 271. Ne-
therlands. 1-240".

S. Stylus (E.). — Large, styliform and
narrow, quadrangular; one end more
obtuse than the other, but neither acute ;
costa 54 in 1-144". ERBA. 1843, p. 271.
Near Weimar. 1-144".

S. rhopala, EM. pi. 33. 1. f. 19. Egypt.
Ehrenberg's figm-es show the front view
large, longly cuneate with rounded ends,
and numerous fine ti-ansvei-se strife at
each side, separated by a nan'ow smooth
median portion with two puncta at each
end.

S. aspera (E.). — Large, with four or
five loosely disposed costse in 1-1152",
-with rough crests. KSA. p. 39. Volcanic
earth, Hochsimmer on the Rhine. This
species, named from a fragment, Ehren-
berg states is perhaps a Campylodiscus.

S. Australis (E.). — A fragment of a
linear species with six, straight ti'ans-
verse strife in 1-1200". Africa. Another
species constituted by Ehrenberg's ob-
jectionable practice of naming isolated
fragments.

S.? lamprophylla(E.), S. UraIensts(Fi.'),
Ural Moimtains; S. Sibirica (E.), Sibe-
ria; /S ? cMrr;/?a (E.), India, Mexico ; S.
Stella (E.), Maritime : India, Africa ; S.
Nicobarica (E.), Nicobar ; S. co7)ipta (E.),
Egj'pt ; S. Zamheze (E.), River Zambeze ;
S. Platalea (E.), Senegal; S. Cqfra (E.),
S. Capensis (E.), S. clathrata (E.), Cape
of Good Hope; S. Falkkndica (E.), S.
Mehdnens{s(k.),S. Insular II lu (E.), Falk-
land Islands; S. Araucania (E.), Arau-
cania; S. am^Mceiitra (E.), <S. holosticha
(E.), S. irnecta (E.), S. Icptotera (E.),
8. Pohjodon (E.), Mexico.

Genus CAMPYLODISCUS (E., Men.).— Valves equidistant, frustules soU-
tary, disciform; disk tortuous or saddle-shaped, rotiuidato-elliptic, costate,
costfB mostly radiate. Campylodiscus has the lateral surfaces still more
developed than they arc in the Mclosireoc, whilst the central or intei-stitial
portion is reduced to a narrow ring, — a cu'cumstanco which renders it very
difficult to obtain a satisfactory front ^aew. In these respects it approaches
tlic Coscinodisceaj. Kiitzing referred to Surirclla several species now placed
in this genus. Meneghini suggested their removal to Campylodiscus, in these
terms — <' Ono really is at a loss to find the motive that could induce Kiitzing
to separate this gcnericaUy from Campylodiscus ; " and Professor Smith has,

OF THE STTBIHELLEiE.

799

wo consider judiciously, adopted that suggestion. " The species included
under this genus may all be recognized by the characteristic bend or con-
tortion of their surfaces." — Sm. Cocconcis differs in its small size and cen-
tral nodule.

* Disc circular, or nearly so, with a single
series of marginal costce.

t Costae aR radiant, forming a marginal
circle.

Camptxodiscus Horologium (Wil-
liamson).— Disc neai'ly flat, with a mar-
ginal circle of numerous (about 50) equal,
radiating cost£e, having a circle of close,
very short and fine striae at its inner, and
another at its outer edge, and enclosing
a large, central, orbiculai", smooth space.
SBD. pi. 6. f. 51. Marine. Scotland.
The costae are propoi-tionally shorter in
this large species than in most others,
and occupy about one-third of the radius.

0. limbatus (Breb.). — Disc with a mar-
ginal circle of short costae, continued by
an inner fainter circle of monilifonn lines,
gradually lost in an indefinite, smooth
central space. BD. p. 12. f 1 ; GDC. p. 32,
pi. 3. f 55. Marine. France, Scotland.
" Distinguished from C. Horologium by
its finer costse and gTanulated disc,"
Breb. " Costse broad, transversely sili-
cate, so as to appear on close inspection
almost moniliform. Within this mar-
ginal band is another fainter band, which
looks abnost like the reflection in a mir-
ror of the first, except that the bars are
more dhectly moniliform," Greg. This
species might be placed with almost equal
propriety in the section with double series
of costse.

C. imperialis (Grev.). — Costse 3 in
•001", forming a magnificent band, ac-
companied at base by short bifid seg-
ments ; central area broadly elliptical,
furnished with narrow, ti'ansverse, mo-
niliform striae, inteiTupted by a median
blank line. Gr TMS. viii. p. 30, pi. 1.
f. 3. New Providence. In general ap-
earance resembles C. limhatus, Br(5b.
ut differs materially from that Diatom
on a closer examination. Grev.

C. Kittonianus (Gr.). — Costae elon-
gated, transversely striated for two-thirds
of their length. Gr TMS. viii. p. .32,
^1. 1. f 7. West Indies. Central space
tiimished with a median bar, as in C. 7io-
tatus, only less conspicuous, Grev.

_C. ntcllatus (Gr.). — Valve orbicular,
■with a naiTow marginal Imud of close,
short costne, an inner circle of dotted
lines, and a central space marlced with
irregular radiating lines. Gr M.T. vii.

p. 157, pi. 7. f. 3. Califomian guano.
Costffi 10 m -OOl".

C. radiosus (E.). — Disc subcircidar,
small, with smooth or obscurely punctate
centre, and border of about seventy
closely-set, radiating costae. KSA. t. 28.
f. 12. Fossil. Vera Cruz. Upper Pe-
nivian guano. We have noticed a Cam-
pylodiscus in Bolivian guano, and sup-
posed it to be this species. The costae
are niunerous, radiating, and imequal,
enclosing a quadrilateral, obsoletely
pimctate central space, divided by a
median hyaline line, and having at its
angles 3-4 converging costae.

C. vulcanius (E.). — Disc large, sub-
orbicidai", flexuose, vsath about 42 mar-
ginal rays, and smooth centre. KSA.
p. 33. Pei-u.

C. hicruciatiis (Greg.). — Disc circular,
with a square median space occupied by
crossed striae, and prolonged to margin
by fom' pairs of tapeiing, transversely
striate processes in a crucial manner, each
interval with foiu* sti-ong radiant costae.
Greg MT. v. p. 78, pi. 1. i. 42. Marine.
Glenshira, Scotland. A veiy peculiar
species, but difiicult to describe. The
square centi-e is lattice-lOce, and itself
obsciu-ely subdivided into smaller qua-
drate portions ; from it proceed to the
margin, in a crucial manner, foiu- pairs
of conical prolongations; the intervals
between the pairs are occupied by strouo-
rays, which, together with the striated
prolongations, are connected within the
margin in a scolloped manner.

2 1 Disc more or less evidently divided
into lateral portions by a median line
or band ; costae imperfectly radiant.
C. Jliberuicus (E.). — Disc tortuous,
with numerous (30 to 40) continuous,
impei-fectly-radiant costa3, enclosing an
irregularly shaped, minutely punctated
central space. EM. pi. 15 a. f. 9. = C. cos-
tatus, SBD. i. pi. 6. £52. Aquatic. Britain.
(xv. 38.) The costaj are loosely disposed
(4 in 1-1152"), slightly rough ■from mi-
nute gTanules, and extend in length about
iialf the radius. Their radiant an-ange-
ment is somewhat imperfect, from tlio
convergence of two or more at eacli end.
Mr. Norman lias gathered this species
very pure neai- Hull.

C. iVonwis (E.). — Disc suborbicular,

800

SYSTEMATIC HISTOKY OP THE INFUSOfilA.

tortuous, gradually smooth in the cen-
tre ; costae numerous, continuous, their
crest acute. KSA. p. 33. Aquatic.
Asia; Salzberg. Fossil at San Fiore.
Rays 7 in 1-1152". D. 432".

C. Kutzingii^Q.). — Disc saddle-shaped,
broadly margined, marked with about
50 transverse, continuous, cm'ved sulci.
B. in Proc. Acad. Phil. 1853. Philippine
Islands.

C. Ralfsii (S.). — Disc small, subcir-
cular, bent; costae transverse, reaching
the median line. SBD. i. p. 30, pi. 30.
f. 257. Marine. Britain. The costae of
one side ai"e divided from those of the
other by a longitudinal median line.

C. Normanicus (Gr.). — Costae 3 to 4 in
•001", imperfectly radiant, passing across
a linear-oblong central depression to the
narrow median blank line. Gr TMS.
viii. p. 29, pi. 1. f. 1. West Indies.

C. notatus (Gr.). — Costae numerous,
about 12 in -001", in length more than
half the radius ; central space oval, with
a median thick bar dilated at each end.
Gr TMS. viii. p. 31, pi. 1. f. 4. Shell-
cleanings. Distiaguished by the mark-
ings of the centre, which Mr. Norman
aptly compai'es to the figure of a dumb-
bell, Gr.

C. deconts (BrSb.). — Disccircular, bent,
with a simple series of long, arcuate costae,
and a smooth, narrow-lanceolate median
space. BDC. p. 13. f. 2. = C. Ralfsii?
GDC. p. 30, pi. 3. f. 52. Marine. France,
Britain. " This species is very elegant.
Its costae are, with the exception of
one or two centi-al, aU cui-ved towai-ds
the ends," Breb. The following re-
marlcs are from Dr. Gregory's paper : —
" I have referred it to C. Ralfsii, S., al-
though it is much larger than the form
figui'ed by him, and although there are
other differences. Thus in C. Ralfsii the
canaliculi reach the median line, and the
row of heads or expansions lie some di-
stance from the margin. But these dif-
ferences cannot be regarded as specific."

C. annularis (Greg.). — Disc suborbicu-
lar ; costae very numerous (160 or more)
and imequal, imperfectly radiant, form-
ing a simple marginal band, and divided
into two sets by prolongations of the
large, oval central smooth space. GDC.

&30, t. 3. f. 53, Loch Fine, Scotland,
amed from the angular bending back
of the valves. The costae are longest at
the middle of each side; aiul, as in C.
dccorus, all except the central ones are
curved, with the concavity towards the
ends, and become also gi-adually smaller
on approaching them. " A true median

line is visible, but is very delicate

The surface of the valve, both above and
below — that is, near both ends of the
median line — is suddenly bent back, so
as to form an angle with the rest of the
valve. On the surface thus bent, short
lines appear between the costae," Greg.
Distinguished from C. decorus by its more
nimierous costae, oval central space, and
extensions of the latter separating the
costas into two sets.

C. Hodgscmii (S.). — Disc subcircular,
bent, with a marginal series of very nu-
merous (100 or upwards) imperfectly-
radiating costae ; the central space with
transverse rows of dots divided bj a
naiTow median smooth line. SBD. i. p.
29, pi. 6. f. 53. Marine. Britain. "The
smooth median line is formed by a ridge
and two continuous furrows passing
across the valve," Smith. The costae
neao." the ends converge. Mr. Roper finds
the dots vary greatly in number, distinct-
ness, and arrangement, especially in the
larger specimens, and on this accoimt
considers C. eximius not distinct from it.

C. condnmis (Grev.). — Costae 5 in
•001", radiant, forming a narrow mar-
ginal band ; central ai'ea oval, fm-nished
with numerous ti'ansverse momlifomi
striae, iuteiTupted by a median blank line.
= C. mar(p,natiis, Johnst. inMJ. viii. p. 13,
pi. 1. f. 11; GrTMS. viii. p. 8,f 2. SheU-
scrapings. New Providence. Califomian
guano.

C. eximim (Greg.). — Disc subcircular,
bent ; costae strong, very numerous (often
150), rather short, in a single mai^inal
subradiating circle, enclosing a large hya-
line space, furnished -with scattered gra-
nules and a median line. GDC. p. 31,
pi. 3. f 54. Marine. Loch Fine, Scot-
land. The costae of C. cxitnitis, like those
of C. Hodgsonii, are rendered imperfectly
radiant by the couvei-gence of those near
the end of the median line or raphe.
C. eximius diftei-s from that species in its
less conspicuous and scattered gi-anules,
invisible except when highly magnified.
Mr. Roper, however, may be right in re-
garding it as a vaiiety of C. Sodgsonti,
suice Professor Gregory himself states
that tlie gi-anides " in some instances
show faint traces of a linoai- arrangement
close to the mai-ginal band."

2 * Disc circular or stibcircidfrr, tciih a
doid»le concodric scries of cost^a.
C. centralis (Greg.).— Disc with about
forty, equal radiating costflj, leaving a
small umbilical space ; the costae conti-
nuous, but divided into two series by a

OF THE SXJEIRELLEJE.

801

shade-like band, the inner series fainter.
GDC. p. 30, pi. 3. f. 51. Marine. Loch
Fine, Scotland. Professor Gregorj' snp-
poses that the appearance of a line which
divides the costa is caused by a ridge.

C. fenestratns (Grev.). — Disc circular,
with marginal radiating costte divided
by a line into two series, the inner one
fainter and enclosing a central space
occupied by foui* lattice-like scvdptures
formed by three or four bars crossino'
each other at right angles. Grev. in MJ.
V. p. 9, pi. 3. f. 4. Marine. West Indies.
The continiious costse are divided, as in
C. centralis, hy a line into two concentric
series. A species distinguished by the
" four remarkable sculptiu'es, exactly re-
sembling square windows in miniature,
the bars sharp and slender, and the panes
actuaUv appearing as if they transmitted
light,"'Gr.

C. Ecclesianus (Grev.). — Disc subcir-
cidar, with a border of two concentric
series of very short, radiating costae, or
narrow-oblong cellules ; central space
with two rows of transverse broad bars,
separated by a median line, from each
end of which proceeds a semicircle of fine
sti-ife. Gr. I. c. p. 10, pi. 3. f. 5. Marine.
West Indies. "Similar in size to the
last, but somewhat more contorted, so
that when one portion of the valve is in
focus, the details of the remaining por-
tion are less visible. The valve is con-
cave ; the central portion, occupied by the
two rows of bars, is nearly flat ; but on
each side of the rows, and at then- termi-
nation, the disc is inflated, the lateral
inflations being unsculptured, the ter-
minal ones striated," Grev.

C. hicostatus (S.). — Disc suborbicular,
saddle-shaped, with from twenty to fort}'
unequal radiating costse, interrupted so
as to form two concentric series, enclos-
ing an oblong, .smooth central space.
Ro. in MT. ii.'pl. 6. f. 4; SBD. ii. p. 88.
Thames ; Norfollc. Diam. about 1-384".
Co.st.'E distinct, their leno^th, at sides,
about half the radius, at the ends much
shorter. Inner series less distinct.

C. Clypeus (E.). — Disc suborbicular ;
rays immerous (40 to 100), radiating,
partinllv intemipted, and fomiing two
incomplete concentric series ; the large
punctated central space divided by a
median smooth line. EM. pi. 10. 1. f. 1 ;
SBD. ii. p. 88. In fresh and brackish
■waters ; also fossil. Asia, Africa, Ame-
rica, Em-opo, England. Original draw-
ings of this elegant species are given in
XVII. .516, 518. Diam. 1-570" to 1-216".
tostre punctated, continuous at the ends,

but inteiTupted at the sides, where they
form two series. In the centi-al space
are two oblong sculptm-ed portions, sepa-
rated by the smooth median line.

C. Remora (E.). — Disc suborbicular,
tortuous, with interrupted rays and a
smooth centre. KSA. p. 33. Marine.
Baltic. D. 480".

C. marginatus (E.). — Disc small, in
the middle smooth, subscabrous, fur-
nished in the margin with a double
series of cellules, the external fine, the
inner larger, evident, closed at the oppo-
site ends, open and radiated in the mid-
dle. KSA. p. 33. Maritime. King's
Island, India, Ceylon.

Cfastuosa (E.). — Disc suborbicular,
cm-ved ; costse subdistant, continuous,
divided into two concentric series, the
outer inflated, inner shorter, stalk-like,
enclosing a finely and transversely stii-
ated central space. KSA. p. 33. = C.
Tliureti, BDC. pi. 1. f. 41 ; C. simulans,
Grev MJ. v. pi. 1, f. 41. Marine. Asia,
France, England. Cfastuosa is easily di-
stinguished from every preceding species,
except C. marginatus, by its finely striate
central space and the peculiar appearance
of its costsB, which are divided by a line
into two parts, compared by Professor
Gregory to a lotus-flower on a stalk. Pro-
fessors Kiitzing and Gregory note its re-
semblance to Surirella fastuosa ; we be-
lieve it, however, quite distinct, as, in
addition to its circular and bent fonn, the
central striae are finer and more nimierous.
C. fastuosa varies considerably in size,
and in the compai-ative breadth of the
centi-ai_ portion, which is sometimes a
mere line, at others lanceolate, or even
oval. The costa3 are either inteiTupted
by the prolongation of the central por-
tion to the mai-gin, or continued all
round.

C. amhiguits (Gr.). — Disc suborbicu-
lar ; costse distant, reaching nearly to the
centre, partially interrupted at the mid-
dle ; in the centre an oblong depression,
within which is a short, linear-elliptical
blanlc line. Jamaica, Port Natal. Qv
MT. viii. p. 31, pi. 1. f. 5.= C. Mm, Sh
MT. ii. pi. 1. f. 13.

0. parvulus (S.). — Disc subcircular,
minute; costne few (about twelve), in
length about two-thirds of radius; central
space obscurely striated. SBD. i. p 30,
pi. 6. f. 56. England, (xv. 22, 23.) We
have found this form generally accom-
panying C. fastuosa. Like that species,
it is sometimes oblong, and probably is
only a small vai-iety. It is usually much
bent, and is tlie smallest species

3f

802

SYSTEMATIC HISTOltY OF THE INFUSORIA.

3 * Disc siibdrcular, ivith radiatinfi series

of gratmles or perforation-like dots.
Coronia (Hhr.).

C. Echcneis (E.). — Disc bent, with uu-
merovis irregulai'ly radiating series of
conspicuous dots, tecomiug- fewer and
more scattered near the centi-e. KSA.
p. 34. = a Arf/us, BMO. pi. 2. f. 24, 25 ;
C. cribrosm, SBD. pi. 7. f. 55. Marine.
America, Europe, England. Diam. 1-288".
The costiB are nearly obsolete, and con-
fined to the margin. We refer C. Argus
to this species npon the authority of om-
lamented friend the late Professor Bailey.

C. diplostictus (Norman). — Disc with
conspicuous marginal, moniliform, radi-
ating liues, alternate ones shorter, and a
large, subelliptic, central blank space.
GrevTMS. \dii. p. 31, pi. 1. f. 6. Australia.
The cellules of the striae are linear-ob-
long, and, being marked longitudinally
by a faint line, appear doubled.

C. heliophilus (E.). — Disc small, sub-
orbicular, including in the broad and
smooth median area a quadrate series of
grannies, similar series of gi'aniiles being
radiately disposed in the broad margin,
and in a double concentric order; the
external rays simple, the inner ones
binaiy. KSA. p. 33. Maritime. India,
China. The proper ari'angement of this
and the next species is doubtful.

C. Indicus (E.). — Disc large, with a
siibquadrate, smooth, median area, and a
very broad margin formed of fine and
dense radiating series of granules in a
double concenti'ic order. KSA. p. 33.
Maritime. King's Island, India.

Var. ^. Concentric rays continuous.
Var. y. Concentric rays interrupted.

4 * Disc sicbcircular, with a narrate, me-
dian, pervious, smooth band, and trans-
verse lateral stria.

C. ? striatus (E.). — Disc with two series
of about 13 transverse strife on each side
of the median line. EA. iii. pi. 7. f. 13 ;
KB. pi. 28. f. 11 ; Bri MJ. vii. p. 79, pi. 9.
f. 4. Fossil. Vera Cruz.

5 * Frustules in lateral view not circular.

C. Surirella (E.). — Disc large, flexuose>
oblong; the middle broad and smooth,
the margin narrower, -with radiating
stria3. KSA. p. 33. Aquatic. Spain.

C. ovatus. — Disc curved, large, ovate,
obtuse, with nine very broad pinna in
\-'27Q". = Surirella Clypeus, E. Marine.
Baltic. 1-276".

C. Elirenbergii. — Disc flexuose, small,
ovato - elliptic ; ends equally rounded ;
margin striated, with from 10 to 12 costse
in \-l2<X)". = Surirella C'ampylodiscus, E.
Aquatic. Itah', Mexico, (xv. is. 12, 13,
22 & 23.)

C. spiralis (K., S.). — Spirally twisted,
with a dotted margin ; laterally elliptic,
with about 60 nearly pai-allel costse ; cen-
tre of disc minutely punctate. SBD. i.
p. 29, pi. 7, f. 54. Aquatic. Europe,
England, (iv. 39.) C. spiralis differs from
C. Hibernicus in its elliptic and twisted,
not saddle-shaped fi'ustule. We doubt
if it be distinct from C.flexitosa.

G.Jlexuosa (E.). — Disc large, flexuose;
costse 4 or 5 in 1-1200". = SurircJlu Jlex-
uosa, E. KB. t. 28. f. 25. Aquatic.
Africa, South America, Mexico, IVance.
(XV. f. 11.)

C. elegans (E.). — ^Large, very broad,
with sul)acute ends, and very finely-
punctate sxwiace. — Surirella ekqans, E.
KB. t. 28. f. 23. Aquaric. Germany,
Mexico. Costfe 4 in 1-1200". Known
only by fragments.

C.Mi/odon (E.). — Small, rather curved,
laterally elongated, naiTOw, with one end
rounded (the other unknown), with
small, closely-set costfe, giving the mar-
gin a toothed appearance. = SurireUa
Myodon, E. KB. t. 28. f. 24. Mexico,
Japan, Africa. Costce 6 or 7 in 1-1200".
Known only fi-om fi-agments.

C. Zo»alts (Ph.). — Disc large, greatly
deflected ; " radii svmmetrical to two
axes ; concentric sti'iation may be de-
tected, and some appeai'ance of puncta-
tion on the outer edge." Found in cre-
taceous, marly deposits. Bridlington,
Yorkshire. Prof J. Phillips, 1845.

Genus CALODISCUS (Rab.).— Discoid ; disc subcircular, with numerous
(often 64) ray-liko bands, each connected at the broad, striated rim with its
neighbours, and forming tooth-likc straps ; centre not striated, clouded, with
a lighter transverse one-branched zone. The umbilical zone is probably non-
essential, and we doubt whctlicr this genus be distinct from Campylodiscus.

Calodiscus .mpcrbus (Rab.). — Disc
largo, flat, with a distinct closely .''triated
rim, and equal radiating costos enclosing

n lai-gish clouded umbilical space. Bab.
D. p. 12. t. 3. Aquatic. Itflly. (nil. 56.)

OF Tnii STRIATELLEiE.

803

FAMILY VI.— STEIATELLEiE.

Filaments comi)resscd ; the central portion of the frustiile furnished -with
incomplete longitudinal septa, which appear Like stria3 or costae. The Stria-
tellea3 form a very distinct group, distinguished from every other by having
parallel longitudinal strife or costaj on the central or connecting portion of the
frustule. "The appearance of longitudinal strife is in fact produced by
siliceous plates arising internally from the margins of the filament, and ex-
tending towards but not reaching the centre. The interior is thus divided
into chambers, opening into a central space. When viewed laterally, this
central space resembles a canal, especially as the inner edge of each plate has
a concave outline " (Ralfs, ANH. xiii.). The strife and septa are frequently
conterminal ; in some genera this appearance is constant, and then the striae
are said to be interrupted. We believe, however, that the striae are really
continuous, although always more strongly marked where they coincide with
the septa, and, on the other hand, very indistinct, especially in a young state,
when they are merely formed by an internal rib. Prof. Smith adds the
following explanation : — " The valves (lateral surfaces) are similar in chai-acter
to those of the other Diatomaceae, and are formed during self-division in the
same manner ; but, instead of the usual repetition of the process of valve-
formation, we are here presented mth a subsequent intervalvular development
which, not confined to the exterior of the frustule, projects a plate of silex
into its interior, forming a septum or partition extending towai'ds, but not
reaching, the centre of the cell, and appearing as a compressed rim or annulus
of silex, whose outer or larger circumference foUows the exterior outline of
the frustule, and whose inner edge bounds the free space which serves as a
channel of communication between the chambers into which the cell is thus
divided. This process is either simultaneous, and the frustule definite, or
successive, and the frustule indefinite. In the fii'st case the annuli of silex
are formed diuing the production of the valves in the progress of seK-division,
and on every repetition of such production; while in the second case the
formation of the annuli is continued after the production of the valves, and
is repeated an uncertain number of times before the recurrence of a new
valve-production " (BD. ii. p. 32).

Kiitzing divides this group into StriateUeae and TabeUarieae, but we agree
with Meneghini in thinking this division unadvisable. "Any one," says the
latter, " examining these beings with diligence, will entirely convince himself
that the distinction of the two orders is altogether insufficient. No TabeUaria
has a central nodule in the secondary siu-faces at aU to be compared with
that of the Diatomeae constituting his order Stomaticoe in his fij-st tribe. I
firmly believe that TabeUarieae and StriateUeae ought to constitute one famUy,
since the diaphragms, which are considered characteristic of the second ex-
clusively, are not wanting in the first " (M. I. c. p. 475).

Genus STRIATELLA (Ag., K.).— FUamcnt of few fmstules ; stipes long ;
frustules longitudinaUy striated, lateraUy lanceolate, with a median Uno ;
septa short, inner ones longest. Marine. The long stipes and absence of
transverse striae on the central portion best distinguish this genus.

Stria tell a unipunctatn (Lyngb. , Ag. ) .
— Fmstules hyaline, subquadrate, with
numerous fine, parallel, continuous lines ;
stipes longer than the frustule. SBD.

p. 37, pi. .30. f. .307. Not uncommon
m the autumn on Zosteraand the smaller

Algaj. Filaments minute, pale yellowish-
browm, glass-like, and glittering, usually
composed of few frustules. The septn
aro very short. Tho internal colouring
matter is generally collected into a
roundish central mn-ta. (iv. 40.)

3 F 2

804

SYSTEMATIC HISTORY OF THE INFUSORIA.

Genns TESSELLA (Ehr.). — Frustulos broadly tabulate, not concatenate,
densely striated longitudinally ; striiE alternate, interrupted in the middle ;
stipes none ? " It is impossible to judge of the value of the characters that
distinguish it from Striatella and Hyalosira whilst we do not know the
organic importance or the true stnicture of the striae " (M. I. c. p. 46G).

Tessella mternipta (E.). — ^Frustules
in front view subquadrate. 1-750".

KB. t. 18. f. 4. Mixed with SlriateUa
unipunctata, but less abundant, (viii. 5. )

Genus HYALOSIRA (K.). — Pilameuts stipitate ; frustules quadi-ate, septa
alternate, interrupted in the middle, and united by very fine lines. "At
first I was afraid that I was led by want of skill in observing, to beheve that
I could see in the two longer species of this genus a continuation of the vittae
from one margin to the other, instead of theii' being interrupted and alternat-
ing as they are figured and described by Kiitzing. Continiung my observations,
I succeeded at last in fijiding one individual exhibiting to my sight the alter-
nations described ; hence I became convinced that the latter condition is not
merely inconstant, but even the least frequent. The secondary surfaces are
elliptico-acute " (M. I. c. 466).

HYAiiOsmA minutissima (I^.). —
Shortly stipitate, concatenate ; frustules
very minute, partially separating in a
zigzag manner. 1-5700". KB. t. 18.
£ 3. 2. MediteiTanean Sea.

H. delicatula (K.). — Shortly stipitate,
concatenate ; frastules minute, quadi-ate,
partially separating in a zigzag manner.
1-2640". KB. t. 18. f. 111. 1. France ;
Adriatic Sea. (iv. 42.)

H. rectangula (K.). — Shortly stipitate,
subconcateuate, frustules subquadrate,
rectangular. 1-1380". KB. 1. 18. f. 3. 3.
Adriatic Sea (xiv. 23). Fmstules larger
than in the preceding species.

H. ohtusanc/ula (K.). — Longly stipi-
tate, ribbon-like or subconcatenate; frus-
tules quadrate, with obtuse angles.
1-1440". Adiiatic Sea. (xiv. 29.) Frus-

tules larger thau in the first two species.

H. punctata (Bailey). — Frustules large,
united in long chains, rectangular, siib-
quadrate, ti'ausversely and uninter-
ruptedly vittate, alternate vittaj granu-
late in the middle of the fi'ustule, the
others funiished with a series of con-
spicuous pimcta. 1853. Tahiti.

H. Beswickii (^oroifm, MSS.). — Septa
continued across the filament as cuiTed
inteiTupted costre; valves oblong, with
sti'ongly inflated centre and roimded
ends ; strife coarse, 30 in '001". New
Zealand. On Algre from Joseph Bes-
wick, Esq. Fnistides quadrate ; valves
sometimes with subcapitate apices. [We
are indebted to Mv. Nonnan for the de-
scription of this species.]

Genus IIHABDONEMA (K.). — Filaments elongated, shortly stipitate;
longitudinal striae uninterrupted, connected by series of transverse striaj ;
lateral surfaces having transverse striae and a median longitudinal line. From
the comparatively large size of the fiiistules in llhabdonema, greater faeihty
is afforded for examining their structm-e. The longitudinal strias or ribs
(annuli, Sra.) are continuous, parallel, mostly equidistant, and connected by
a series of transverse stria), so that, in fact, the structure has a latticed
appearance.

Rhabdonema minutum (K.). — Septa
marginal, alternate ; lateral valves ob-
long or spindle-shaped, inflated at the
middle, transversely striated throughout.
SBD. ii. p. 35, pi. 38. f. 306. = TvsseUa
Catena, Ralfs, c. xii. (not E.). Eiu-ope.
1-1200". Snmllor than R. arouttiim, from
which it diilcrs iu the inflated or gibbous
centre of its lateral valve.s. (iv. 41.)

R. arcuatum (LATigb., K.). — Septn
raai'ginal, opposite ; lateral valves oblong
or linear-elliptic, the ti-nnsverse striffi
absent near tlieir ends. SBD. ii. p. 34,
pi. 38. f. 306. = StriateUa armato, Ag.,
E. ; TcsscUa Catena, E. Common, (x.
203, 204.) Diiloi-s from R. minutum
m the form of its lateral valves, and by
the ab.sence of stria; near the ends : llie

OF THE SXiUATELLEJS.

805

series of striaj in the front view are also
moi-e conspicuous. Lengtli of fi-ustule
1-570" to 1-200".

R. Adriaticum (K.). — Frustules ^^ath
foiu- series of septa (two mai'ginal and
two median, tlie latter shortest at one
lateral margin, and graduall}' longer as
they approach the other). SBD. ii. p. 35.
pi. 38. f. 305. Common, especially from
deep water. On Algse, which are sold
as " Corsican moss." (xin. 27.) 1-480"
to 1-168". Easily distinguished by the
median series of septa, which, more con-
spicuous than the mai'ginal ones, are
usually more or less cm-ved or oblique,
and do not coincide with the ribs, but
cross the series of stria3 ; they also gra-
duall}" increase in length from one lateral
mai'giu to the other, leaving a funnel-

shaped median space.

R. Crozieri (E.). — Lateral valves
turgid ; apices obtuse, shortly attenu-
ated; tlie perforated dissepiments (or
spm'ious joints) sti-iated, varying in
number. = Striatella Crozieri, ERBA.
1853, p. 529. Assistance Bay. Strife
18 in 1-1152", (IV. 43.)

Species known to its only by name.

R. miriflcum (S.). — "A magnificent
species, with filaments occasionally reach-
ing -0086" in -width, and with alternate
and cribrose septa. Septa with several
(3 to 12) irregular perforations." SBD.
ii. p. 35. Mam-itiiis and Ceylon. Arnott,
JMS. vi. p. 92 ; Brightw. JMS. vii. pi. 9.
f 11. (vm. 12.)

Genus STYLOBIBLIUM (E.).— Frustules cylindrical, multivalved, not
concatenated, valves in a simple straight series, like the leaves of a closed
book, with a large median canal, entire (not perforated) at the ends ; sculp-
tured ; tube smooth. Fossil. Stylobiblium approaches nearest to Biblarium
and Tetracyclus ; but the fi'ustules in the lateral view are orbicular — a cha-
racter not met with in the other genera of this family. The species are
fossil, and occur only iu a fragmentary state.

STTLonrBLiUM Clypeus (E.). — Lateral
view with fr-om 15 to 20 short, radiant
marginal lines, and 3 or 4 pendous, trans-
verse mediim ones, fi'ustules in the front
^iew with about 34 laminre or aunidi.
EM. pi. 33. 12. f. 28, 22. = Biblarium
Clypeus, E. Oregon and Siberia. Dia-
meter 1-792". (IV. 45.)

S.clivisum (E.). — Disc large, its centre
-\vith about 10 transverse parallel lines,
not reaching the margin, and separated
into two series by a Imear longitudinal

blank band. EM. pi. 33. 12. f. 30.
Oregon. Diameter 1-600".

S. eccentricum (E.). — Disc with 5 to 7
eccentric, pei-vious, cm-ved lines. EM.
pl.^33. 12. f. 31. Oregon. Diameter
1-760". A fragment of a cylinder con-
tained 9 annidi. The costte in Ehren-
ber^'s figure resemble those of Teti-a-
cyclus, the median one straight, and
those, above and below curved towards
the margin in opposite dii'ections to each
other.

Genus BIBLARIUM (E.). — Frustules compressed, lamcUiform, with in-
ternal septa ; lateral view with transverse uninterr\iptcd costte, but without
median inflation. FossU. AU the species are fossil, and, although described
by Ehrenberg as simple, were probably filamentous in a recent state. The
forms with inflated centre we concur with Professor Smith in romo\ang to
Tetracyclus, and indeed only retain the genus because wc arc unable to
ascertain at present the proper situation of the other species noticed here.

Biblarium cowi/)ress(»«(E.). — Lateral
view elliptic-oblong, with obtuse ends
and lax, parallel transverse costas. EM.
pi. 33. 12. f. 1. Oregon. 1-648".
Costte 5 to 7 in 1-1152". Septa 28 in
each frustule.

B. clliplicum (E.). — Lateral view ellip-
tic, with broadly roimded ends, and 5 to
8 parallel trann verso striio in 1-1152".
E^[. t. 33. 12. f. 2. Siberia and Oregon.
1-1080". Dillers from Ii, votnprcumm

only in its more elliptic lateral valves.

13. Lamina (E.). — Lateral valves
broadly linear, with rounded ends,
slightly constricted middle, and 7 to 8
parallel transverse striaj in 1-1152"
bM. pi. 33. 12. f. 4. Oregon. Ehren-
berg's figure shows little or no constric-
tion.

B. lim>are (E.).— Latend valves nar-
rowly linear, with rounded or subacud-
emls, and 4 to 8 parallel transverse siria>.

806

SYSTEMATIC HI8T0EY OF THE INFtJSOJBlA.

iu 1-1152". EM. pi. 33. 12. f. 6. Siberia
and Oregon. Ehreuberg'.s figures scarcely
difler fi'om those of B. Lamina, except
in being narrower.

B. Lancea (E.). — Lateral valves lan-
ceolate, witb subacute apices, and 3 to 8
parallel ti-ansverse striae in 1-1152". EM.
t. 33. 12. f. 5. Oregon. Twenty-seven
septa in each frustule. 1-336".

B. Castellum (E.). — Lateral view of
central portion elliptic, with obtuse ends,
and four marginfil undulations. EM.
t. 33. 2. f. 1. Siberia. 1-900". Lateral
valves unlmown. (iv. 44.)

B. ? (jibhum fE.). — Frustules smooth.
baciUar ; 2 to 4 together, -svith straight
centre; lateral view gibbous at the

middle.
1-1152"
family.

KSA. p. 117. Kurdistan.
A doubtful member of this

Species known to us only by name.

B. Chilense (Eh. Chili.).— " Related to
B. co7npressmn," EM. p. 301.

B. constrictum (E.). — Fossil. North
Asia.

Genus GOMPHOGEAMMA (Braun). — Filaments compressed, continuous,
of few frustules ; septa clavate, alternate, nearly equal ; lateral valves elliptic,
fui-nished with straight transverse costa3. Aquatic. Gomphogramma agrees
with Tetracyclus in its freshwater habitat and in the strong transverse costa3
of its lateral valves, but differs (as we believe, essentially) by its clavate septa,
which are not continued as costae across the central canal. We are not suf-
ficiently acquainted with the structure of Biblaiium to decide what may be
its relation to that gemis ; but it is not improbable that further investigation
may require their union. Professor Smith thus contrasts Gomphogramma
with Tetracyclus : — " In Tetracyclus the valve is cruciform, and the costae
arched ; in Gomphogramma the valve is elliptic, and the costae direct ; but
these seem rather to belong to specific than generic characters, and the pro-
priety of uniting these genera hardly admits of a question " (ANH. Januaiy
1857).

GoMPHOGnAMMA rupestre (Braun). —
Frustules subquadrate, with fi'om one to
three septa on each side and gland-like
dots along the junction-margins. Braim
in Rab D. pi. 33. t. 9. Freiburg; Pyi-e-
nees. This seems to be a mountainous
species, and most probably its detection

would reward a seai'ch in om* alpine
districts. In its clavate septa it some-
what resembles Tei-psinoe, but the re-
semblance is merely superficial ; for the
septa in that genus are ti-ansverse, and
in this longitudinal ; consequently they
belong to diilerent gi'oups.

Genus TETRACYCLITS (Ealfs).— Filaments free, elongated, inflated at
the centre, striated ; stritB continued across the inflated centre ; septa equal ;
lateral surfaces costate. Aquatic. The inflated centre and strongly costale
lateral surfaces sirfficicntly characterize this genus. " The genus Biblarium,
constituted by Ehrenberg in 1845, appears to difi'er from the present merely
in the solitary character of its frustules ; and this character ai'ises from the
fossil natiirc of the gatherings from which Ehrenberg derived his specimens.
I feel assured that aU the species are filamentous in a li-snng state, and that
the greater number of them are casual varieties of Tetracyclus lacustris "
(SBD. ii. p. 37).

Tktracyclus lacustris (Ralfs). — La-
teral view with the inflations and ends
rounded. SBD. ii. p. 38, pi. 39. f. 308.
= Striatclla Thiencmanni, EA. p. 136;
Biblarium Stella ; B. Glans and B. spc-
ciositm, EM. pi. 33 ; B. striiniosi/ni, EM.
pi. 33. 2. f. 13. Recent, Britain and
Iceland ; fossil, Oregon and Siberia,
(xi. 24, 26.^. The median inflation seems
variable; it is soniclinio.<< sn nnicli de-

veloped as to fonn a crucial figure re-
sembling the quaferfoil of a Gothic win-
dow, but sometimes merely a slight
swelling, as in Biblarium speciosum (E.).

T. emarffinatus (E., S.). — Inflations
deeplv notched, othei-wise like T. lacus-
tris, SBD. ii. p. S8. = Bib/ariatn cmarqi-
natum, EM. pi. 33. 2. f. 6. Recent, Britain :
fossil, Siberia and Mexico.

T. ckffans — Inllations acufc. =

OV THE SIBIATliLLEiE.

807

Biblarium elegans, EM. t. 33. 2. f. 4.
Fossil. Siberia, Ehreuberg's figure of
this species differs from T. Ithombus
merely in its more developed inflation.

T. Rhomhus (E.). — Lateral view rbom-
boid, with subacute angles. = Biblarium
Ithombus, EM. pi. 33. FossU. Siberia

and Oregon.

T. ? Crux (E.). — Lateral view cruci-
form, with transverse parallel stria> and
a median sutuve. = B{blaru0n Crux, EM.
pi. 33. 2. f. 3. Siberia. StriiB 18 in
1-1152". A doubtful member of this
genus.

Genus TABELLAEIA (E.). — Frustules quadi-angular, united into a fila-
ment, at length partially separating and forming a zigzag chain ; septa equal,
straight ; lateral surfaces inflated at ends and middle. Aquatic. Tabellaria
differs from the other genera of this family by having thi'ee inflations of the
lateral surfaces.

Tabellahia flocculosa (Roth, K.). —
Joints subquadrate, with from 8 to 7
attenuate septa from each margin ; la-
teral view with three neaily equal infla-
tions; the intennediate poi-tions lineai-.
SBD. ii. p. 45, pi. 43. f. 316. =Bacillaria
tabellaris, EI. p. lW. = Navicula trinodis
in part, E. = Tabellaria vulgaiHs, E. Com-
mon, (xm. 29.) Best distinguished
from T.fenestrata by its less elongated
frustules and more numerous septa,
which usually alternate with those fr-om
the other margin. We believe, however,
that each complete septimi has an oppo-
site one which is generally rudimentary,
though sometimes more developed and
conspicuous. 1-860" to 1-480".

T. ventricosa (K.'). — Frustules as in
T. Jlocculosa, but the central inflation of
the lateral view much larger than the
terminal ones. KB. t. 30. f. 74. = T. bi-
ceps, EM. several figm-es. (xm. 26.)
Common. 1-960". Professor Smith
unites this to T. Jlocculosa, and, as we
believe, justly, since intennediate forms
are not imcommon.

T. Gastrum (E.). — Very small ; lateral
view with a subglobose median inflation
and somewhat narrower capitate apices.
KSA. p. 119. Fossil. Labrador.

T. robusta (E.). — Thick, three times
as long as broad, with broad gibbous
centre and large subacute terminal
eapitida. EM. pi. 33. f. 15. Fossil.
America. 1-8G4", Probably another
variety of T. Jlocculosa.

T. amjiMlepta, EM. pi. 3. 4. £32. Fossil.
Boston. Ehi-enberg's figure shows the
lateral view with inflated centi'e, as iu
T. Jlocculosa ; but the exti'emities are not
dilated.

T. nodosa (E.). — Small, slender, no-
dose ; nodules five, the median one rather
largest, those adjoining oblong. EM.
sevei'al figiu'es. Siberia. Lough Mom-ne
deposit, &c. Ehreuberg's figm-es are
elongated, Avith fom- consti-ictions, and
consequently five inflations, of which the
median and terminal are suborbicular
and the intermediate oblong. " Akin to
Grammatophora undulata " (E.).

T. fenestrata (Lyng., K.). — Front view
linear, with two opposite septa from each
end ; lateral view with three nearly equal
inflations and linear connecting portions.
KB. t. 17. f. 22. = Tabellaria trinodis,
EM. many figiu-es. Common. 1-600"
to 1-280".

Species dotcbtful, or knoicn to us only by
name.

T. amphicephala (E.). — Very small,
with strongly inflated centre and capi-
tate apices. KSA. p. 119. Fossil. San
Fiore. 1-1728". Scarcely distinct fi-om
T. ventricosa.

T. j}latysto77ia (E.), Sandmch Islands ;
T. rhabdosoma (E.), Asia ; T. pinmdaria
(E.), Asia; T. clavata (E.), Northern
Asia; T. undulata (E.), Northeni Asia;
T. curocephala (E.), Persia; T. Semen
(E.), India; T. BadUum (R).

Genus GRAMMATOPHORA (E.).— Frustiiles forming a filament, at length
partially separating and becoming a zigzag chain ; septa in pairs, opposite,
generally curved; lateral view oblong-lanceolate, not inflated. Gramma-
tophora is easily distinguished from till the other genera by its stria) having
commonly a curve outwards near the base ; and when this curve is wanting
it may be known from Tabellaria by the absence of inflation. Although
Kiitzing dcsci'ibcs several species of this genus as smooth, yet wo believe tluit
all the species arc striated ; and notwithstanding we have admitted {his

SOS

SYSTEMATIC HI8T0KY OF THE rNrUSOKIA.

character into some of the definitions, we use it merely to indicate that the
striae are more distinct and more easily detected.

* Lateral view ohlong or lanceolate,
sometimes slightly constricted beneath
the apices.

t Septa straight or funnel-shaped.

Gbammatophora stricta (E.). —
Large, with straight, parallel septa ;
lateral view lanceolate. KB. t. 29. i. 76.
Asia, Afiica, America.

G.jtarallela, EM. pi. 21. f. 26. We
know not how this form difi'ers from
G. stricta, except that the figTU'es of the
lateral valves exhibit more roxmded
apices.

G. Tabellaria, EM. pi. 18. t 89, 90.
Fossil. Virginia. In Ehrenherg's figures
the front view has the septa slightly
cm-ved and dilated inwards (fimnel-
shaped) ; lateral view lanceolate, with a
large central canal.

2 1 Septa ■with a semicircular curve near
the marginal ends ; otherwise sti-aight.

G. marina (Lyng., K.). — Septa with
a single cm'vatiu-e ; lateral view linear-
oblong, gradually tapering into the ob-
tuse apices. KB. t. 17. f. 2i. = Diatoma
teeniceforme, D. marinum (Lyng.), and
D. latriincularium (Ag.), I), brachy-
yonium (Carni.), Hacillaria Cleopatra
(E.)., B. Adriatica and B. Meneghina
(Lobarzewsky), Grammatophora oce-
anica. Everywhere. Common, often
forming long chains, (rv. 47 ; xi. 52, 53.)
The synonyms are adopted from Kiitzing,
and probably some of them belong to
other species. The fi'ustules are of very
variable length, sometimes nearly square,
sometimes many times longer than broad.
Connecting hinge slender.

G. tropica (K.). — Large, with striated
margin; septa with a smgle cm'vatm-c;
lateral view linear, with rounded apices.
KB. t. 30. f. 71. Cape of Good Hope.
1-600" to 1-156". Connecting hinge
tumid.

G. gibba (E.). — Large, striated; septa
cm'ved at outer end, otherwise straight ;
lateral view linear, with slightly in-
Hated centre and rounded ends. KB.
t. 29. f 77. Cuba. (xi. 48, 49.)

G. Mexicana (E.), — Large ; septa with
a single curvature ; lateral view con-
stricted beneath the rounded apices. KB.
t. 18. f. 1-0. Em-ope, America. Con-
necting hinge tumid.

G. gibber ulu (K.). — Margin striated ;
septa once curved ; lateral view lanceo-

late, vsdth tumid centre and obtuse apices,
KB. t. 30. f.8L Naples. 1-450". Con-
necting hinge slender. Diflers from G.
Mexicana in its distinctly striated mar-
gin and more lanceolate lateral view.

G. macilenta (S.). — Frustules often
cmved; septa as in G. marina; lateral
valve linear, slightly inflated at centre
and extremities ; striaj 60 in -001". SBD.
ii. p. 43, pi. 61. f. 382. Britain ; Levant.
" The front view in this species is always
naiTower in propoi-tion to its length than
in G. marina. The striae are also far
more nimierous ; and the frustule, espe-
cially in the lai'ger specimens, shows a
decided tendency to assume a cm-ved
form."

3 1 Septa limately curved, both ends
hooked inwards.

G. hamulifcra (K.). — Small, subqua-
drate; septa cm'ved thi-oughout, with
their concavities towards each other.
KB. t. 17. f. 23. Common, especiaUy
from deep water, (xni. 22.) 1-2400"
to 1-960". Distinguished by its small
quadrate frustules and unifoimly curved
septa. It is possible, however, that it
may be the immatm-e state of one of the
following species.

4t Septa undidate, inner ends incurved.

G. angulosa (E.). — Septa hooked in-
wards, at inner end and neai- the margin
of fr'ustule with angular curve inwards.
KB. t. 30. f. 79. Atlantic and Pacific
Oceans. Perhaps a variety of G. Afri-
cana.

G. Africana (E.). — Septa with three
mididations, the inner ends uicurved ;
lateral view lanceolate, obtuse. EM.
pi. 19. £ 34. Fossil, Oran ; recent, not
unconuuon. 1-2300" to 1-480".

G. Islandica (E.). — Septa with three
undulations, curved at the centre ; lateral
view navicular, striated. KSA. p. 121.
Iceland.

G. serpentina (E.). — Large, -wnth stri-
ated margin; septa with several undu-
lations and incurved inner ends ; lateral
valves linear, with attemiated ends and
obtuse apices; connecting hinge thick.
SBU. ii. p. 4;3, pi. 42. f. 315. = G. Mcdi-
terranca (E.), according to Kiitzing. Not
uncommon m sheltered bays. Kemark-
ablc for its serpentine septa, the number
of rur\ os seeming to vary according to
the Icngtli of the frustule; and we fear

OF THE STllTATELLE^.

809

that some of the allied species are not
really distinct from it. Professor Smith
informs us that, iu this species, Mr. West
finds the dots disposed in quincimx, and
the lines consequent!}' oblique, (iv. 48.)

G. aii/juina (K.). — Large, smooth ;
septa serpentine, with the interior end
hooked inwards. KB. t. 17. f. 25. At-
lantic and Antai'ctic Oceans. 1-650" to
1-360". We see not how this diflers
from 6. serpentina, as we believe that no
species iu this genus is really smooth.

2* Lateral view with four constrictions.
G. unchdata (E.). — Lateral view linear,
with fom* constrictions and rounded
ends ; septa in front view imdulated.

KB. t. 29. f. 68. Fossil, Greece ; recent,
America. 1-860".

3* Lateral view lunate.

G. arcuata, EM. pi. 35 a. 23. f 11, 12.
Assistance Bay. The figures represent
the front \aew with imdulated septa,
and the lateral one lunate, with ti'ans-
verse lines and a central canal.

G. curvata, EM. pi. 35 A. 22. f. 13.
Antai'ctic Ocean. The figure shows the
lateral view, like that of G. arcuata ; but
its central canal is smaller, and there are
no transverse lines.

G. suhtilissima. — Striae fine. A good
test for high powers.

Genus GEPHYKIA (Amott). — Frustules attached ; front view witli sub-
lamellate, finely striated connecting zone, destitute of sej)ta ; valves arcuate,
dissimilar, with transverse costse interrupted by a longitudinal line. Marine.
"We place Gephyiia with the Striatelleae because of its resemblance to
Eupleuria; but the absence of septa renders its proper position somewhat
doubtful. The lower valve differs from the upper one in having a smooth
circular space at eacb end. The strongly arched valves and absence of septa
distinguish it from Eupleuria. It differs from Acbnanthes by having no
central nodule.

Gephyria incurvata (Ar.). — CostEB of
valve about 7 in -001" ; connecting zone
with stout longitudinal costse. Ai- MJ.
viii. p. 2Q.=Euj}lewia incurvata, ArMJ.
vi. p. 90 ; Achnanthes costata, Johnstone,
MJ. viii. p. 20, pi. 1. f. 14. South African
and Patagonian guano.

G. media (Ar.). — ^Valves obtuse, with
11 costie in -001". Ai- MJ. viii. p. 20.
Achnanthes anffiistata, Johnstone, MJ.
viii. p. 20, pi. 1. f. 13. Californian guano.

G. Telfairice (Ax.). — Valves with
acute cimeate ends, and 15 costfe in
•001". ArMJ. viii. p. 20. Mauritius.

Genus EtJPLEUEIA (Amott). — Frustules united mto short, attached
filaments ; front view annulate, indefinite, with short septa and beaded
margins ; valves dissimilar, costate ; costne interrupted by a longitudinal lino
those of lower valve fewer and central. Marine. Eupleuria difiers from
Rhabdonema by its dissimilar valves, the transverse costte of the lower one
being confined to the middle — a character conspicuous even in the front view,
since the ends of the costae are there seen as mai-ginal bead-like dots. The
valves have some resemblance to those of Achnanthes, but have no central
nodule or stauros.

_ Eupleuria pulchvlla (Ar.). — Front
view with stout longitudinal costiB con-
nected by ti-ansverse bars, very short
septa, and punctated lateral margins.
Ai- TMS. vi. p. 89. New Zealand and
Australia. The frustules, in tiie front
view, have the ceUidate structure of
Pihabdonema ; but the septa are so abbre-
viated as to seem mere marginal dots,
and the puncta on the ventral margin
are confined to the middle. Annuli clofse,
numerous; valves usually turgid at the
middle and rapidly tapering to tlie obtuse
apices (subovate)J but sometimes linear-

oblong. In the lower valve the costm
and lonmtudiual lino are present only at
the middle portion, and leave a large
hyaline blank space at each end. Strije
between the costaa, and oblique.

E. ocellatn (Ar.). — R-ont view with
longitudinal linos, fine transverse strife,
and costate lateral margins ; costie of
ventTal margin longer, confined to the
middle, and divergent. ArTMS. vi. p. 9.
New Zealand. In E. occUata the frustules
are niore hyaline than iu E. pidchella,
and the longitudinal costie lefcis conspi-
cuous, and uot connected by transverse

8i0

SYSTEMATIC HISTOfiY OF THE INFUaOBIA.

boi's. The most evident distinction,
however, is the chivato or capitate lines
of the dorsal and venti'al margins, those
of the latter being longer, fewer, and

divergent. The septa seem to be rudi-
mentary, as in tlie preceding species.
Valves obloug-linear, sonietijncs cm-ved,
with roimded ends.

Genus ENTOPYLA (Ehr.). — Erastiiles prismatic, compressed, multivalved ;
valves contiguous, in a straight, simple series, like the leaves of a book ;
internal ones traversed by a large median opening ; outer ones transversely
striated, unequal, one entire (not perforated), the other furnished with a largo
pore at each end. Marine. Entopyla, by its curved form, approaches
Achnanthes ; by its tabulate figure it is more akin to Tessella ; but it comes
nearer to Biblarium than to any other. Although, in deference to the opinion
of Professor Arnott, we have kept Eupleuria distinct from this genus, we
doubt the propriety of doing so. From Ehrenberg's comparison of Entopyla
with Tessella and Biblarium, and beaiing in mind Ms peculiar views, it is
evident that the " internal valves " are the "annuli" of Smith, and the "per-
forations of the ventral valve" the blank spaces at each end. Since the
opening in the internal valves is stated to be so large as to leave only a thin
margin, the septa must be rudimentary. Both Entopyla and Eupleiu-ia seem
therefore to differ from Khabdonema in their dissimilar valves and rudimen-
tary septa, nor are we able to find any character in Ehrenberg's description
which enables us to distinguish Entopyla from Eupleuria.

Entopyla Australis (Ehr.). — Leaves
(annuli) about IG ; transverse costte of
outer ones (or valves) 32 to more than
40 in number, divided by a median

flexuose Ime. ERBA, 1848, p. 42. =
Surirella Australis, Elii'. 1843. Pata-
gonian guano.

Genus DIATOMELLA (Grev.). — Erustules quadrangular, forming at first
a piano- compressed filament, at length separating ; vittae two, interrupted
in the middle and at each end.=Disiphonia, E. Aquatic. Professor Smith
doubtfully referred to Grammatophora the Diatom for which this genus was
constituted ; but we consider the differences pointed out by Dr. Greville as
sufficient, independently of its aquatic habitat, to separate it from that genus.
In Grammatophora the septa are formed in the central or connecting portion,
arise from the margins of the filament, and are interrupted in the middle. In
Diatomella they appear to us to arise from a thickened rib connecting the
lateral and central portions, and form imperfect diaphi-agms with three_ open-
ings— one central, the others marginal. We have included Diatomella in this
family, but, although Professor Smith states that its fi'ustiiles are annulate
and nearest in structure to Grammatophora, we are not sure it is rightly
placed here ; for two puncta exist at each end of the fnistulc, as in the
EragUariese.

Diatomella Balfouriana (Gr.). — La-
teral view linear or oblong, with rounded
ends and 45 fine striae in -001." GANIL
8. 2. XV. pi. 9. fs. 10-13. = 6r;-flmwirt<o-
phora P Balfuuriana, SBD. ii. p. 43, pi.
61. f. 383.'=Disiphonia Australis, EM.

pi. 35 a. f. 7. South Africa, South Ame-
rica, Scotland. Front view ciuadrangidar,
with a smooth central portion, separated
from the transversely- striated lateral
valves by the vittaj. (iv. 51, 52.)

FAMILY VII.— MELOSIRE^. •

Fmstules disciform, cylindrical, or globose, simple or united into a filament ;
lateral surfaces flat or convex, cii-cular, smooth or with radiatmg stnac, less
frequently cclluloso, granulate or punctate ; front view with the central por-
tion usiuilly either obsolete or divided by one or two central furrows. '• ioi-

01? THE MELOSlREili.

811

the most part the CoscinodisceEe are related to tliis family, with which they
have been liitherto united by Ehrcnberg ; but I have separated them because
the shell of the Coscinodiscefe often has divergently arranged bands and a
cellulose formation, which is wanting in the Melosireoe. Moreover the forms
of the genus Melosira have in life so great similarity to the true simple Con-
fervee, that they may easily be conlbunded even by practical Algologists.
The heating of a specimen upon mica, however, distinguishes them so cer-
tainly that we can never be in doubt " (Kiitzing). The line of demarkation
between the Melosirese and CoscinodisceEe is by no means well established ;
generally, discoid forms with cellulose structure belong to the latter, and fila-
mentous or smooth species to the former. This family, however, contains
some distinctly cellulose species ; but they are distinguished by their inflated
or vaulted segments and the absence of a central portion.

We have removed some genera Kiitzing had placed here, as we consider
Mr. Brightwell has proved that they are more akin to Chaetoceros.

Genus CYCLOTELLA (Kiitz.). — Frustxiles disciform, simple or binately
conjoined ; central portion ring-like ; valves plane or slightly convex.
Aquatic and marine. =Discoplea, Ehi'. CycloteUa differs from Melosira in
not forming a filament. The recent species, according to Kiitzing, are either
adnate or enclosed in a shapeless gelatinous substance. Some of the species
approach closely in character to Coscinodiscus. "We retain Kiitzing's name
because it has the claim of priority.

Ctclotella o^m-culata (K.). — Valves
depressed in the centre; stiite obscure,
very short ; front view with roimded
angles. SBD. i. p. 28, pi. 5. f. 48. Fresh
water. Europe. This species is involved
in gi'eat confusion, and we confess om*
inability to reduce it. We have adopted
Professor Smith's views, though with
much hesitation. Kiitzing describes the
margin as punctated; and his figiu'es,

though varying much in size, of

the
margin

umbilical portion, show the
closely and irregidarly pimctate, whilst
Smith describes them as striated. Kiit-
zing refers here the Discoplea Ki'dzingii
(E.) ; but that form, according to the
figures in the ' Microgeologie,' is larger,
with radiating strise reaching to the
centre of the disc. (v. 53.)

C. rectatiffula (Breh.). — Similar to C.
operculata ; but the fi'ustides in the fi'ont
view have acute angles. Rah D. p. 11.
France. By Kiitzing made a variety of
C. operculata, by Smith of C. Kiitzingi-
ana, (v. 54.)

C. Scotica (K.). — Frustules adnate;
disc plane, very smooth. KB. t. i. i. 2,
3. = C. Ligmtica, K. I. c. t. 1. f 4. On
marine algiE. Scotland, &c. We unite
C. Ligustica to this species, since Kiitzing
makes no distinction except size, which
in the Uiatomaceas is too variable to be
made the only specific diflcrencc. D.
l-nOO" to 1-510". (xiv. 17.)

C. maxima (K.).— Frustules largo, ad-
nate ; disc ncnriy plane, punctated. K. I.e.

1. 1. i. 5. On Algae in the Pacific. Diam.
1-300" to 1-126". Puncta scattered.

C. Coscinodiscus (E., K.). — Disc small,
irregadarly but densely and finely granu-
late, margin smooth. = Disco^jlea Cosci-
nodiscus, EM. pi. 33. 10. f. 1, 2. Fossil.
United States. Habit of Coscinodiscus
miitor, rather tm-gid on the sides. D.
1-1728".

C. Mammilla (E., K.). — Disc smooth,
umbonate in the centi-e ; sutm-e in front
view timiid, produced at the margins. =
Discoplea Mammilla, EM. pi. 38. 22.
f. 1-3. Fossil. Patagonia. The suture
between the valves is ridge-like, and
consequently projects at the margins.
Rim of disc striate. Diam. 1-1728".

C. timbilicata (E.). — Disc smooth, ynih
a central smooth umbo. = Discoplea um-
hilicata, EM. pi. 35 u. b. f. 9. From
Atlantic doe_p soundings. Elircnbero-
describes this species as smooth, but
figures it ^vith a punctated centre.

0. Americana (E., K.).— Frustules in
front view tm-gid, \vith a transverse, tri-
carinated ring ; disc punctate in the
centi-e. KSA. p. 19. United States.
Diam. 1-660".

C. physoplea (E., K.).— Disc smooth,
except a circlet of large vesicidar-lookino-
granules round the centre. = Discoplea
phg.wpka, EM. pi. 33. 17. f 8. Fossil.
Virginia. Diam. 1-1152''.

C. comta (E., K.).— Disc with a circlet
of small strife near tlio margin, and a
crowded central mass of gramilos. = 7),s_

812

SYSTEMATIC HISTOUY 01? THE INFUSOKIA.

coplea conita, EM. pi. 38. 1b. Asia,
AJi'ica, i&c. Front view tumid at the
sides. Although this species is said to
have a granulated ujnbilicus, none of
Ehrenherg's figui-es exhibit this cha-
racter.

C. dendrochcBi-a (E.). — Disc smooth,
except a circlet of short rays. = Discoplea
dendrochcera, E. On trunks of trees.
Venezuela. Frustules small, timiid in
front view, Diam. of disc 1-1920" ; cen-
ti-al circlet with about ten rays. Habit
of C. comta.

C. atmospherica (E.). — Disc with a
central, rather turgid umbilicus, from
whichradiate numerousstriae. = Discoplea
atmospherica, EM. pi. 39. 1. f. 17. In
atmospheric dust. Diam. 1-1008".

C. Sinensis (E.). — Disc with a central,
rather tui-gid, gi'anular umbilicus, from
which radiate numerous striae ; the stiise
separated from the umbilicus by a border.
= Discoplea Sinensis, EM. pi. 39. l.f. 16.
Atmospheric dust. China, &c. Diam.
1-864". Eays much closer than in C.
atmosplierica, and smooth, not rough as
in that species. In front view linear,
with striated margins, (xv. 4.)

C. Atlantica (E.). — Disc with a central,
somewhat granular umbilicus, from which
proceed numerous radiating \\a.ea.= Dis-
coplea Atlmitica, EM. pi. 39. 3. f. 29.
Atmospheric dust. Atlantic. Smaller
than the last, and its umbilicus not cir-
cumscribed by a rim ; but we doubt
whether this and the two preceding spe-
cies are sufficiently distinct, (xv. 3.)

C. Oregonica (^.~). = Discoplea Oreqo-
nica, EM. pi. 37. 2. f. 3. Oregon. Eh-
renherg's figm'e represents a small disc
with a central punctated umbilicus, from
which proceed numerous rays. Front
view linear, with marginal stoise. Does
this differ from C. Sinensis ?

C. venusla (E.). — Disc with gi-anulated
umbilicus and numerous smooth rays.=
Discoplea venusta, ERBA. 1852, p. 634.
Alive. California. Akin to C. atmo-
spherica ; frustules with the stellate habit
of Actinocyclus. Ehreuberg observed
three specimens. In one the umbilicus
wa.s nearly equal to a fourth part of the
diameter of tJie disc, and the entire sur-
face very nearly smooth ; in another the
surface Avas distinctly granulated, and
the imibilicus, having its margin oblite-
rated, was scarcely evident,

C. Aslreea (E., K.). — Disc with a large
punctated centre and denselv-ra^'cd mar-
gin. KS A. p. 19. = a ItofidniKB: t. 2. f. 4 ;
SRI), pi. 5. f. r^O? Kurdistan; Ireland.
Diam. 1-G.'5G". ll has the habit audsize of

Melosira varians, but is not concatenate.
C. Rotula is a marine species.

C. Peruana (E., K.).— Disc wnWi very
fine rays, reachiu<r to the centre. = Dw'-
coplea peruana, EM. pi. 38 a. 14. f. 6. In
pimiice from Areqiupa and Santiago,
Peru. Resembles C. Astrcea. Diam.
1-600". The thickness of the frustule
equals half its length. Although the rays
are described as reaching the centi-e, the
figiu'es show an umbilical space,

C. oligactis (E.). = Discoplea ? oKgactis,
EM. pi. 35 A. 9. £ 1. Ganges. Ehren-
herg's figm-e shows a small disc, with
striated rim and irregidar umbilical
space, from which proceed a few irregu-
lar rays.

C. Grceca (E.). — Disc plane, inter-
ruptedly striated in a radiate manner. =
Discojjlea Grceca, E. = Coscinodisciis Grce-
cus, KSA. p. 125 ; EM. pi. 6. 2. f. 1. FossU
in Greece. Diam. 1-864".

C. antiqua (S.). — Valves convexj striae
broad, not reaching the margin. Diam.
•0009" to -0013". SBD. i. p. 28, pi. 5. f.
42. Lough Mom-ne and reterhead de-
posits, &c.

C. picta (E., K.). — Disc plane, broadly
granulated in the middle, its margin
densely radiated ; rays very slender, ele-
gantly mixed with paii'S of stouter ones.
KSA. p. 20. African coast. Disc some-
times large.

C. Rota (E., K.). — Disc large, with
numerous (52) equal rays, not reaching
to the centre ; surface papillose ; papiUai
vmequal, smallest between the rays,
largest at the CQntve. = Discoplea Rota,
EM. pi. 35 A. 22. f. 6. Southern Ocean.
Diam. 1-192". This and the next species
are distinguished from the rest by having
papillae or granules in the intervals of
the rays.

C. Rotula (E., K.). — Resembles C.
Rota, but is smaller, its ravs fewer ui
number (20), and its papillce equal. =
Discoplea Rotula, EM. pi. 35 a. 22. f. 7,
Southern Ocean. Diam. 1-696". As in
C. Rota, the rays extend from the margin
towai'ds, but do not reach the centre.

C. denticulata (E., K.). — Disc marked
with straight, parallel, gramdated lines,
and its margin denticulate. KSA. p. 20.
Bermuda. Diam. 1-672". In the character
of its margin it resembles Mehsira sul-
cata, but in the arrangement of its gra-
nules it approaches Coscinodiscus lineatus,

C. undulata (E., K.).— Disc with radiat-
ing lines of very minute granules, and an
undulated m.argin. = 7);".sc«;j/w undulato.
EM. pi. m. 18. f. 3. Bermuda. Diaui.
1-576". Marginal tiexuies about fifteen.

OP THE MELOSIEEiE.

813

C. stylonim (Br.). — ^Viilve with styli-
form rays diverging from the centre, and
ending near the margin with a large
circular head; centi-e in-egularly punc-
tate. Sierra Leone. Br TMS. viii. p. 96,
pi. 6. f. 16.

C. ? radiata (Br.). — Valve with simple,
strongly marked radii, reaching nearly to
the centre ; centi-e smooth ; in fi'ont view
the ends of the radii appear as pimcta.
West Indies, Monterey. Br. I. c. p. 96,
pi. 6. f. 11. As many as ten frustules

have heon found in imion; this may,
therefore, belong to Melosira.

C. punctata (S.). — Frustules with nn-
didations ; valves delicately pimctate or
cellulate ; ceUides radiate. Diam. -0008"
to -0015". Fresh water. England. SBD.
ii. p. 87. (vm. 13.)

0. DaUasiana (S.). — Valves with mar-
ginal costae ; centre cellulate ; cellules
in-egular. Length of costse -0002"; Diam.
of valve -022". Brackish water,
land. SBD. ii. p. 87.

Eng-

Genus ACTHSTOGOlSnUM (Ehr.).— Frustules suborbicular, many-angled ;
disc smooth, with radiating Hnes. Actinogonimn, lilie Liostephania, differs
from the rest in. being smooth.

AcTrNOGONiTiM: septenarium, EM. pi.
36. f. 39. Barbadoes. Rays (7) di-sid-
ing the disc into compartments, separated
from the margin by a regulaiiy-undu-

lated border. Between the centre and
border is a cii-clet of verj' short lines, frv\'0
in each compartment, (v. 55.)

Genus LIOSTEPHANIA (Ehr.). — Frustules simple, orbicular; disc smooth,
but with a crown of rays encircling a large smooth central space or umbi-
licus. Liostephania is distinguished by its disc being smooth, and having a
circlet of strife, which strise do not reach the margm.

Liostephania Rotula (E.). — Disc
having fi'om six to foiu'teen simple rays.
EM. pi. 36. i. 40. Barbadoes. (v. 57.)

L. comta (E.). — Disc with from six to
thirteen rays, connected exteriorly by a
circlet of pimcta. EM. pi. 36. i. 41.
Bai'badoes. This species differs from

the preceding one in the presence of
puncta.

L. magnijica (E.). — Disc with its rays
alternating inward.s with pairs of very
short strife, and connected exteriorly by
a circlet of puncta. EM. pi. 36. i. 42.
Barbadoes. (v. 56.)

Genus DICTTOLAMPRA (Ehr.).— Frustules orbicular, not concatenate ;
disc without an umbilicus, but having a circular cellular centre, with radiat-
ing strise, which alternate with other stria) from the niai'gin.

Dictyolampra differs from the other genera of this family by its disc being
cellulose only ta the centre, and indeed it probably ought, together with Lio-
stephania and Actinogonium, to form a distinct family ; but, haviuo- seen
no specimens, we are unable to decide on their proper position.

DicTYOLAMPHA Stella (EM. pi. 36. f
38). Barbadoes. The only species. In
the centre is a large, circular, loosely cel-
lulose umbiUcus, with numerous (about

20) short radiating lines, which alternate
with similar ones directed inwards fi-om
the margin ; between the latter are inter-
posed very short marginal strire. (v. 58.)

Genus MASTOGONIA (Ehr.).— Frustules simple (unequally), bivalved;
valves not cellulose, in lateral view circular, unarmed, with linos radiating
from a stellate or angular umbilicus. These forms, which wore ■formciiv
placed in Pyxidicula, may be recognized by their unequal and angular valves
radiating veins, and noncellular surface. The definitions of the species in this
genus are unsatisfactory, depending almost entirely on the number of rays
a character which we regard as very variable.

Mastooonia Cmx (E.). — Valves
large, one with foiu-, the other mth seven
radiating lines ; apex not truncated. EM.

Diam. 1-396'

nl.33. 18. f. 8. Bermuda,
mbilicus stellate.
M. qumaria (E.).— Valves large, one

814

SYSTEMATIC HISTOKY OF THE INFffSOKIA.

with five radiating; linos, the other un-
known ; apex not truncate. KSA. p. 25.
Bermuda. Diam. 1-480". Scarcely
more than a variety of the preceding
species.

M. Rota (E.). — Valves lar^e, one with
six, the other with seven radiating lines ;
apices entire. KSA. p. 25. Bermuda.
Diam. 1-360". Probably another variety
oiM. Crux.

M. sexangiila (E.). — Valves thin, one
with six radiating lines, the other un-
Imown; apex broadly ti'imcate, with a
hexagonal area. EM. pi. 33. 17. f. 12.
Virginia. Diam. 1-1632". Resembles a
truncated six-sided cone. All the above
species are very smooth and crystal-
Ime.

M. heptagona (E.). — One valve with

seven, the other with nine rays; apex
truncated. Bai AJS. xlviii. pi. 4. f. 12.
Bermuda. Diam. 1-840".

M. Oculus-Chmnceleotitis (E.^. — One
valve having eight radiating lines and
ti'imcate apex, the other lmkno^vn. KSA.
p. 25. = Pyxidicula Oculus- Chamceleontis.
Maryland." Diam. 1-1152".

M. Actinoptychus (E.). — One valve with
9, the other with 13 flexuose radiating
lines ; apices broadly ti'uncate. = Pyxi-
dicula ? Actinoptychis, EM. pi. 18. f. 19.
Virginia. This species seems distinct in
its nexuose rays and the undulated mar-
gin of its umbilicus, (v. 59.)

M. Discoplea (E.). — Valves small,
conic, with 18 to 20 rays ; apices smooth,
tiiincate. KSA. p. 25. In Patagonian
pumice. Diam. 1-1152".

Genus STEPHANOGOMA (Ehr.).— Valves as in Mastogonia, but their
truncated apices have spinous angles.

Distinguished by the rays being prolonged into spines, and forming a fringe
round the umbilicus.

Stephanogonia qtiadrangula (E.). —
Valves thin, smooth, with truncated
apices, one having fom-, the other six
ray-lUce angles and spines. KSA. p. 26.
Bermuda.

S. pohjgona (E.). — Valve with central
portion smooth and much elevated, united

to the margin by an indefinite number of
rays, the spaces between which are some-
times faintly pimctate ; the umbilicus
sometimes surrounded with spines. Vu--
ginia and Bennuda deposits. EM. pi. 33.
18. f. 10; Br JMS. viii. p. 97, pi. 5.
f. 8. (v. 57.)

Genus CLADOGEAMMA (Ehx.). — The characters of this genus are un-
known to us.

CiiADOGnAMMA Califomicum (E.). —
Valve orbicular, not cellulose, marked
with flexuose lines radiating from the

centre, and in'egularly forked or divided
near the margin, dalifomia. EM. pi.
33. 13. f. 1**. (vm. 11.)

Genus HYALODISCUS (Ehr.). — Frustules simple, disciform ; disc smooth,
flat, its umbilical portion or centre separated by a distract suture.

Kiitzing unites this genus with Cyclotella; but its comparatively large
hyaline disc, with a centre distinguished by an evident sutm-e, and usually
somewhat coloured, is perhaps suflicient to justify its removal. Its flat disc
will distinguish it from Podosii'a.

HYALODiscu8Pato(70MJCt<s(E.). — Disc
large, very smooth, its margin separated
fi-om the large centre by a slightly
gi'ooved but not denticulate suture ;
iunction-line in fi-ont view very tumid.
EM. pi. .38. 22. f. 10, 11. In pumice
from Patagonia. Diam. 1-432".

H. Iccvis (E.). — Disc large, smooth, its
central portion separated by a fi-acture-
like suture. EM. pi. .33. 15."f. 17. Cyclo-
frl/n Iceri.s,Knty.. Virginia. Diam. 1-456".
Allied to Cyclotella physoplca. The su-
ture between the valves i,s not tumid,

and the central portion of the disc is
smaller, and hence more distant from
the rim, than in H. Patagomciis.

H. stvlligcr (Bai.). — Disc with a broad
margin covered with distinct rectilinear
rows of dots, arranged in groups so as
to produce a stellate appearance. BO.
vii. Abundant. St. Augustine, Florida.
" The markings in this species are quite
distinct; and the .stellate appearance,
resembling that shown by Coscinodiscus
siiUilis, will at once distinguish it from
all other species," B.

OF THE MELOSIEEiE.

815

H. subtilis (Bai.). — " Disc mai-lced like
tlie engine-turned back of a -watch, with
lines of exceeding delicacy, only visible
by the Mghest niao-nifiers and careful
illumination ; umbilical portion more
coai-selv gramdated and in size little less

than one-third of the diameter of the disc,"
B. I. c. pi. 1. f. 12. Halifax, Nova Scotia.
" H. IcBvis dillers by having a wider mar-
gin and much coarser markings. This
species forms an admirable test-object,"
B. (v. 60.)

Genus LYSICYCLIA (Ehr.).— The characters of this genus are unlmown
to us. From Ehrenberg's figui-es it appears closely related to Hyalodiscus,
the disc having a central, circular umbilicus, and a broad border separable at
the suture, as in that genus.

LYSICYCLIA Vogelii, ERBA. 1856, p. 333, f. 29. Central Africa, (vin. 39.)

Genus PODODISCUS (Kiitz.).— Erustnles as in Podosira, but affixed hj a.
lateral stipes. Marine. We think that the lateral position of its stipes is
scarcely sufficient to separate Pododiscus from Podosira.

PoDODiscus Jamaiceiisis (Kiitz.). —
Fi'ustides simple, concatenate, smooth ;
stipes elongated, delicate. KSA. p. 26,

pi. 16. f. 28. On Enteromorpha ramulosa,
Jamaica. Diam. 1-840". (xui. 28.)

Genus PODOSIRA (Ehr.). — Prustules united into short filaments, having
a distinct central stipes ; interstitial portion obsolete ; valve convex. Marine.

In Podosira the lateral valves are vaulted, and the central portion is at
fir.st a mere connecting ridge between them. This ridge, however, becomes
gradually broader, and then double; afterwards an intermediate growth
separates the halves of the frustule, which meanwhile do not increase in size ;
and at last, when the intermediate space equals the diameter of the original
fnistule, two new fnistules are formed by the addition of a hemisphere on
the inside of each of the separated portions. The outer sUicious covering
still remaining, the fnistules are connected in pairs, and appear Kke two
globules within a joint. The valves usually have a central, coloured umbi-
licus— an appearance which Professor Smith attributes, in our opinion errone-
ously, to an absence of silex at that point.

PoDOSrRA Mo7itagnei (Kiitz.). — Frus-
tides subspherical, dotted ; connecting
sheath with parallel annular series of
minute strifE. SBD. ii. pi. 49. f. 326.
=P. Adriatica, Me. on Diat. ; Melosira
glohifera, Ra ANII. xii. Britain, France,
&c. ■ (v. 61.)

V.IIormoides (Kiitz.). — Frustides oval,
united into short moniliform filaments ;
connecting sheath obscm'ely punctate ;
lateral view with umbilicus but no rays.
SBD. pi. 49. f. 327. = P. mimmuloides, E.
(ii. 45.) Atlantic, Britain, &c. Di-
stinguished from the preceding species
by its more depressed valves.

P. macidnta (S.). — Disc with a lai'ge
central umbilicus, which is bordered by
an h-regidar, fracture-like sutui-e, from
which radiate outwards several shadow-
like bands ; sm-face punctated. SBD. ii.
p. 54, pi. 49. f. 328. Common in deep
water, guano, &c. Britain. It may be
identical with Craspedodiscm Stella, E.

P. compressd, West. (viii. 34.)

P. Imns (Greg.). — Fi'ustules trans-
parent, glassy, with very delicate oblique
striiB and scattered puncta ; connecting
zone distinctly striated ; disc without a
distinct mnbilicus. Grev MJ. vii. p. 85,
pi. 6. f. 15-17. Scotland.

Genus MELOSIRA (Ag.). — Frustules cylindrical, discoid, or globose, con-
nected into cylindrical conferva-like filaments, one or two lines passino-
rovmd each frustule near the conti'o.=Gallionella, Ehr. Maritime and aquatic!
This genus is easily distinguished from the other genera of the Diatomacea;
except Pododiscus, with which the species in its first section closely correspond
in character. The filaments arc remarkable for their conferva-like appear-
imcc, but, may bo known by thoir brown colour and very fragile nature. The

816

SYSTEMATIC HISTOEY OF THE INFUSOEIA.

species are numerous, and sometimes differ very slightly ; we fear indeed that
several of them have been constituted upon insufficient grounds. Attempts,
more or less successful, have been made to remove some species, and to form
witli them new genera. We have used these divisions as sections, partly
because we are unable to find at present differential characters sufficient to
justify a more complete separation, and partly because we cannot decide
absolutely on the proper position of several species. The following are the
sections we have adopted : —

* Lysigonium. — Joints globose or elliptic, with a ring-like keel round each
valve. In this section the fiiistules resemble in form those of the two pre-
ceding genera, but are distinguished by their carinated valves. The sutui-e
is a ridge between the valves.

2 * Gallionella. — Joints cylindrical or suborbicular, with a single median
furrow, and more or less rounded ends, generally binately connected ; valves
not carinated. The filaments are more or less interrapted at their margins,
and the jimction-surfaces are not denticiilated.

3* Aidacosira. — Joints cylindrical, bisulcate, with more or less rounded
extremities. The genus Aulacosira was proposed by Mi-. Thwaites for
" those species characterized by the absence in the frustule of an evident
central Hue indicating the place of subsequent fissiparous division, but each
frustule having two somewhat distant sulci or fossulas passing round it." "We
have found the sulci constant ; but Professor Smith believes " the characters
have no real existence, and owe their apparent presence in the species Mr.
Thwaites adopted as his type, viz. Melosira crenulata, Kiitz., only to accident,
or observation under imperfect illumination. A careful study of the specimens
from Aberdeen, upon which Mr. Thwaites himself founded his remarks, and
of gatherings from various other localities, has failed to satisfy " him " that any
essential differences exist between this species and other Orthosirae."

4 * Orthosira. — Joints exactly cylindrical, marked by a centi-al line, con-
nected into an uninterrupted cylindrical filament; internal cavity often
spherical or subspherical (Thwaites). Orthosira contains " those species
the frustules of which are not at all convex at the extremities, and which
therefore form, by their close conta(it, an uninterrupted cylindrical filament "
(Thwaites). Professor Smith distributes the species of Melosira under two
genera, Melosira and Orthosira, which he thus defines. Melosira : " Fila-
ments cylindrical, of numerous finistules, attached or free ; frustules spherical
or subcylindrical, more or less convex at the junction-sm-faces." Orthosira :
" Filaments cylindiical, of numerous frastules, continuous, attached or free ;
frustules and valves cylindrical ; junction- surfaces plain, line of junction
usually spinous or denticulated." We regret that in the present state of oiu*
knowledge we cannot adopt Orthosira as a substantive genus. Its jimction-
margins, indeed, are usually denticulate or spinous, a character we do not find
in Melosira as defined by Professor Smith ; but this character is not considered
essential. In our opinion, too, there is greater affinity between " Melosira
distans" and " Orthosira orichalcea " than between the latter and " Orthosira
stdcata." Mclosii'a is of peculiar interest, as it affords the most frequent
examples of that form of reproduction in which the valves of a frustule sepa-
rate, and a sporangium is formed between them, unattended by conjugation.

* Frustules encircled with median and
lateral ridges. Lysigonium.

Mf.losira nnnimuloides (Dillwjii,
Af?.). — Frustidcs spherical, very finely
punctured ; valves carinated. SBP. ii.

n. 56, pi. 49. f. S29.=3r. discigcra, Ag.
Marine and brackish waters. Europe,
America, (v. G4. xi. 14.) Diani. 1-1700"
to 1-860". Frustules globular, miited
in pairs, forming a nioniliform filament ;
each divided into hemispheres by a cen-

OP THE MELOSIRE-^!.

817

tral ridge and crossed by faiuter lines at
each end. Professor Kiitzing describes
it as of a golden colour when di'y ; oui'
specimens are greenish. Sporangial frus-
tides larger, concatenated, originating
horn tlie tenniual frnstide only. Ac-
cording to Kiitzing, the frustules in this
species ai-e ternately, and in the next bi-
nately conjoined ; this does not coincide
vnth oui' experience. The only species
likely to be confounded with it is the
following.

M. salina (K.). — Smaller; valves of
the binate frustules achi'omatic, smooth ;
keels very fine. KB. p. 52, pi. 3. f 4. =
Gallionella nummuloides, El. p. 167.
/3. concatenaia, more distinctly stipitate ;
frustules concatenated by a distinct isth-
mus, KB. pi. 3. f. 5. Brackish waters.
Europe. Ihis species differs from 31.
nummuloides by its less conspicuous
keels and more distinct stipes. Pro-
fessor Smith imites them ; for " forms
aberrant in these respects are so fre-
quently intermixed with the ordinary
frustides that "he " cannot regard such
peculiarities as of specific importance."

M. Westii (S.). — Frustules sub-
globular ; valves conical, with trimcated
apices and a sutui'al and median sili-
cious ring. SBD. ii. p. 59, pi. 52. f. 333.
Stomach of Pecten, coast of Sussex.
This species seems distinct in the
sti'ongly marked centi-al and lateral
ridges.

2 * Joints binately or ternately conjoined ;
valves tmth rounded ends, neithcT cari-
nated nor denticulated. Gallionella.

M. moniliformis (Miill., Ag.). — Joints
rather longer than broad, finely pimc-
tated, binately conjoined, with rounded
ends. KB. pi. 3, I 2. = M. £orre>-i, Gr. ;
Gallionella moniliformis, E. Common in
brackish and marine waters. Diam.
1-800". Kiitzing describes this species
as having ternately conjoined feaistules
concatenated by a distinct i.stlniius.
Sporangial frustules larger, concatenated,
and, according to Professor Smith, origi-
nating only in the tei-minal frustules of
the filament, (v. 71.)

M. lineata (Dillwyn, Ag.). — Joints
cylindrical, smooth, binately conjoined,
with rounded ends ; pairs closely ndnato.
KB. p. 53, pi. 3. f. 1= Gallionella lineata,
E. Marine. Europe. A single filament
sometimes consists of from 1200 to 4000
frustules, forming a chain 2 or 3 inches
m length. Length of joint 1-1400" to
1-430".

M. duhia (Kiitz,). — Smaller; articu-

lations depressed, spheroidal, smooth.
KB. p. 53, pi. 3. f. 6. Maiine, near Cux-
haven. Diam. 1-1200".

M. Jur<fensii (Ag.). — Slender; joints
smooth, elongated, with two slight con-
strictions beneath the silicious sheath ;
juuction-siu'faces convex, hemispherical,
closely concatenate. liB. p. 54, pi. 2.
f. W. = M.subJlexilis, SBD. pi. 51, f. .331.
Brackish waters. Europe. l)iam. 1-800"
to 1-1200". There is only one sutiu-al
line, having usually on each side of it a
slight constriction. As in M. vaiians,
the inflated joints are interstitial, and
closely united to the parent fi-ustule.
M. Jurgensii differs from M. subflexilis
in its maruie habitat and more closely
connected joints ; but we find it difficult
always to discriminate them. The joints
are more uniform than in M. varians,
usually longer in proportion to their
breadth, and with more-rounded ends,
especially in the new-formed valves,
(v. 63.)

M. sub/lexilis(K.). — Frustides cylindri-
cal, smooth, binately conjoined, yoimger
ones elongated, adult shorter, depressed
ends slightlv convex ; paii-s imited by a
short isthmus. KB. p. 53, pi. 2. f 13.
Rividets. Europe. Diam. 1-560". Re-
sembles 3f. varians with the binate frus-
tules connected by short interstitial pro-
cesses. Professor Smith thinks this
species identical with Conferva lineata,
Ddl. Sporangial frustides' as in 3f. mo-
niliformis.

M. varians (Ag.). — Joints cylindrical,
ii-regulaiiy binately conjoined; ends fiat
with, rounded angles," closely adnate ;
disc with very delicate, radiating mar-
ginal strire. SBD. pi. 51. f 332= GaUio-
nella varians, Ehr. Fresh water ; every-
where common. /3. aqualis, all the joints
quadrate ; 31. aqualis, Ag. This species
varies much, botli in size and longtli of
joints; the margins of the filament are
more or less interrupted ; but tlie ge-
minate arrangement of tlio frustules is
often very obscure ; the valves, although,
as in most otlier Diatoms, they are really
dotted, appear smooth unless mngni(i(>d.
The sporangial cells are inflated and in-
terstitial; Professor Smith describes
them as at first globular, but afterwards
dividing (as in the preceding .species) and
becoming cylindrical, whilst Kabenhorst
gives a completely different account of
them. The latter snys " that on forma-
tion of the inflated cell, its grnindes, jit
first irregularly formed, become oblongo-
ovate. Motion talccs place as in ordinary
zoospores. The cell opens, the granules

818

SYSTEMATIC HISTOEY OP TITE INFUSOEIA.

stream forth, and two elongated cilia
become visible at their hyaline smaller
end. Their movement lasts for a very-
short period; they settle down, and
quickly equal or siu'pass in size the
mother-cell." If this description be cor-
rect, it wiU add an important fact in sup-
port of their vegetable nature. Professor
Smith malces the following diagnostic
remarks upon this species : — " The only
species with which this form can be con-
foimded is M. stthflexilis ; but 31. varimis
has the extremities of its fi-ustules closely
applied and partially truncate ; those of
M. subflexilis are often more or less
separated by a mucous cushion, and di-
stinctly convex. . . , M. subjlexilis, when
in abimdance, appears as a dark-gi-een
iridescent mass. M. varians alwaj's pre-
sents a rich golden-yellow or chestnut
to the eye. The geminate aiTangement
of the fi-ustules is conspicuous in M. sub-
jlexilis, and indistinct in M. varians."
SBD. ii. p. 58. The fossU frustules of
this species constitute the greater part
of the eai'thy deposits of white powder
used in polishing silver plate, (rv. 32 ;
IX.* 131; XV. 32.)

3 * F)~usttcles cylindrical, hisulcate, icith
7'oundcd junction-margins.

M. distans (E., K.). — Slender; joints
cylindrical, smooth or indistinctly pimc-
tated, with two distant, delicate, ring-
lilce fiuTows, all closely connected ; disc
plane. KB. p. 54, pi. 2. f. 12. Fresh
water. Em'ope, Asia, Australia, Africa,
and America. Fossil, Bilin, &c. Diam.
1-3456" to 1-864". Joints once to twice
aa long as broad.

M.nit-alis (S.). — .Joints subcj'lindi'ical ;
valves subhemispherical, distmctly cel-
lulate ; exti'emities more or less ti'imcate ;
disc dotted. SBD. ii. p. 58, pi. 53. f.
336. = Coscinodiscus minor, SBD. i. p. 23,
pi. 3. f. 36. Fresh water in Alpine di-
stricts. Britain. According to Professor
Smith, this form hardly differs from
M. distans, except in the greater di-
stinctness of the cellules, and may not
be distinct.

M. m-ichalcea (Mertens, K.). — Slender;
joints obscurely punctated, mostly longer
than broad, closely binately conjoined,
with slightly crenidate ends and two
median fim'ows ; disc plane. 1G3. p. 54,
t. 2. f. 14. = Gallionclla auricludcea, Ehr
Inf. Fresh water. Common. Europe,
Asia, Africa, and America, Yoimgcr
joints two or three times as long as
broad ; older ones shorter. This species
differs from 31, Italica merely in its

more obscure crenations and apparently
smooth disc; and periiaps Professor
Smith rightly united them. Its Hat and
closely connected ends distinguish it
from 31. varians. (v. 65 ; toi. 83.)

M. Italica (E., K.). — Slender; joints
cylindrical, longer than broad, with den-
ticulated ends and two median furrows ;
disc with striated border. KB. p. 55,
pi. 2. f. 6. = Gallionclla Italica, Ehr. ; G.
crenata, EM. many figures; G. crenu-
lata, EA. pi. 2. 1. f. 14 ; 3felosira ori-
chalcca, Ralfs, Annals, xii ; Aulacosira
crenulata, Thwaites; Orthosira orichakea,
SBD. ii. p. 61, pi. 53. f. 337. Fresh
water. Em'ope, Asia, Austi-alia, Afiica,
and America, (xi. 29, xv. 33.) /3. Binde-
rana, Kiitz., more slender; joints foiu*
to eight times as long as broad, often
inflated; disc striated, KB. pi. 2. f. 1.
Hambm-gh. Mr. Thwaites describes the
sporangium as orbicular, -with its axis of
elongation at right angles to that of the
fi'ustide fi'om which it originated; but
Professor Smith's experience did not en-
able him fully to conffrm Mi-. Thwaites's
observations.

M. coarctata (E.). — Joints smooth. Its
habit is that of 31. varians, but its disc
is not stiiated. EA. pi. 3. 5. f. 9. Mexico,
(xi. 20 & 27.) Kiitziag imites this fonn
with M. orichalcea.

M. Hoseana (Rab.). — Joints longer
than broad, with two broad conslTictions
and dentated tnmcate jimctiou-margins:
disc with radiating stiia3 and thi-ee or
more central dots. Eab D. p. 13, t. 10.
= Orthosira sjnnosa, SBD. ii. p. 61, pi.
61. f. 386. Europe. Caves, in moss, on
ti'ees, &c. ; probably common. Much as
they differ in appearance, the late Pro-
fessor Gregory considered that he had
ti'aced the Liparogyra spiralis into this
species; and certainly the two foniis
are almost invariably found together.
(V. 67.)

M. l(Evis (E.) = Gallionclla leevis, EM.
pis. 9, 14 & 33. Ehrenberg gives up-
wards of fifty habitats in Austi-alin, Asi.i,
Afiica, and America. His figures of this
species differ considerably from each
other, and, in the absence of description,
render it difficult to form any idea of the
specific characters. Elu'euterg (I. c. p.
118) says it is allied to Stephanodisciis
JEjndendron, and we strongly suspect
that both these forms ought to be milted
to 31. Hoseana.

M. pileata (E., K.). — Joints shorter
than broad, smooth, with two finely

Simctated, ^vidcly separated sutures,
unction-portions convex, smooth, often

OF THE MEL0SIRE.T3.

819

narrower than the intermediate portion
(cino^uhim) ; hence the hat-like form.
KSA. p. 31.= Gnllionvlla pileata, ERBA.
184i; M. pi. 35 a. 21. f. 11. Autai'ctic
Sea. Diam. 1-648".

4 * Joints cylindrical, connected into an
uninterrupted Jilammt ; internal cavity
often spherical or suhspherical.

M. arenaria (Moore^. — Filaments
stout, cmn-ed ; joints cylmcbical, mostly
shorter than broad, closely united with
denticulated jimction-niargins and a line
of puncta on each side of suture ; disc
with radiating strife and pimctated
centre. Raits, ANH. xii. pi. 9. £ 4. =
Orthosira arenaria, SBD. ii. p. 59, pi. 52.

334; Gallionella biseriata, EM. pi. 15
A, f. 5-7. Fi'esh water. Europe. Easily
recognized by its great size. (vui. 17.)

M. undulata (E., K.). — Stout ; joints
onger than broad, constricted within the
sheath, hence imdulate ; disc slightly
convex, very finely radiated. KSA. p. 29.
= Gallionella undulata, EM.pl. 11, f. 2, 3.
Em-ope and Afiica. Professor Smith
refers this foi-m to 31. arenaria.

M. punctigera. = Gallionella 2}unctigera,
EM. pi. 12. f. 9. Fossil. Germany.
Ehrenberg's figTire represents a large
species, perhaps not distinct from M.
arenaria. Joints within a common
sheath, in one figure shorter, in another
longer than broad, constricted on each
side of the sutiu-e, and ha"\ang a series of
dots along the junction-margins. Disc
with numerous radiating dotted lines
and a smooth umbilicus.

M. Sol (E., K.). — Joints coin-like,
five times shorter than broad ; disc plane,
large, strongly and broadly radiated, with
a smooth imibilicus and narrow smooth
rim. KSA. p. 31.= Gallionella Sol, EM.
pi. 35 A. 22. f. 12. /Antarctic Sea. Rays
84 ; suture of valves single. Diam.
1-336". This species rivals M. arenaria
in size, and somewhtit resembles it in
appearance, but is marine.

M. Oculus (E., K.).— Habit of M. Sol,
but larger, witli equal and stouter ravs.
KSA. p. 31. ERBA. 1844, p. 202. Ant-
arctic Sea. Rays 07. Diam. 1-240".
Probably a state of M. Sol.

M. Ti/mpanum (E., K.). — Disc veiy
broad, -with a smooth centre and a nar-
row, finely striated jnargin. KSA. p. 31 ;
ERBA. 1844, p. 202. Antarctic Sea.

M. calligera (E., K.). — .Joints small,
smooth, having the habit of M. distans,
but with a single median .suture and an
enclosed, double, pTanidar mass (as in
M. undulata). KSA. p. 31. = Gallionella

calligera, ERBA. 1845 j EM. pi. 12. f. 9
7c, I. Fossil in pumice. Island of Ascen-
sion. Diam. 1-1728".

M. sctdpta (E., K.). — Joints not so
long as broad, densely sti'iated, and ele-
gantly sculptm-ed with horizontal punc-
tated lines ; sutm-e a narrow smooth
band ; disc with radiating punctated
lines. KSA. 31. = Gallionella sculpta,
EM. pi. 33. 12. f. 20, 21. Fossil. Ore-
gon. Diam. 1-960". Frustules oval.

M. Camjri/losira. = Gallionella Cani-
pylosira, EM. pi. 35 a. 13 b. f. 1-3.
Elbe. Resembles M. sculpta, but smaller.
.Toints suborbicidar, within an uninter-
rupted sheath, with horizontal dotted
lines on each side of a narrow, smooth
sutural interspace ; disc with marginal
radiating lines.

M. Calif ornica (E.). — ■ Joints broader
than long, densely and strongly striated
with horizontal punctated lines ; sutural
interval smooth, not distinct. = Gallio-
nella Calif ornica, ERBA. 1852, p. 534.
Fresh water. California. Very much
akin to the fossil M. sculpta, and both
forms closely approach M. granulata.
Frequently the granidated, dome-shaped
terminal discs are foimd dispersed
amongst the truncated joints. Perhaps
therefore this form, with M. Horologiuni,
should be referred to the peculiar" genus
Sphasrotermia.

M. Horologium = Gallionella vel
Sphceroterniia Horologium, EM. pi. 33,
2. f. 17. Fossil. Sibei-ia. We have
seen no description of this species, or of
Ehrenberg's ^enus, Sphterotermia. Frus-
tide with horizontal strite inteiTupted by
the smooth sutural band; disc with a
large, definite, smooth umbilicus and
distant radiating striae, terminating at
inner ends in a circlet of glaud-liko dots
(tubercles ?). (v. 62.)

M. arctica (Dickie). — Joints globose
or oval, smooth, the median sutui-al line
generally single, but duplex in subcu-
taneous divisu)n, with a smooth band
inteqiosed. = fti/Z/o/irZ/rt arctica, ERBA.
1853, p. 528 ; EM. pi, 35 a. f. 1, 2. Mel-
ville and Kingston ]}ays. In Ehrenberg's
figures the frustules are within a common
continuous sheath, and marked with hori-
zontal .series ot'puncta,

M. sulcata (E., K.). — Joints shorter
than broad, with a smooth median fur-
row and pinna-lilvo cellules on each
side ; disc fimiished ^vith radiating striro,
which do not reach the centre. KB. p.
55, pi. 2. f. 7. = GollioniMa sulcata, lihr. ;
Orthosira marina, SBD. ii. p. 59, pi. 53,
f, 338. Marino. Frequent, both recent

0 2

820

SYSTKMATIC HISIOUY

OF THE INFTJSOBIA,

and fossil, (ix. 131 and xi. 26.) This
species, which varies considerably in
size, is well marked by its short, slightly
angadar joints, and its transverse sculp-
ture-like marks on each side of the su-
ture. Margin of disc often denticidate.
Diam. 1-860" to 1-600".

M. coronata (E., K.). — M, sulcata in
habit; joints cylindrical, stri?ited; disc
smooth, slightly convex, with a crenated
margin and a circlet of pearl-like giva-
nules within. KSA. p. 31. = GaUionella
coronata, EM. pi. 38. 22. f. 5. Marine.
Asia, Africa, Patagonia. Diam. 1-864".
It differs fi'om M. sulcata only in the
more distinct crenations of the disc and
the circlet of dots.

M. plana (E., K.).— Habit of M. sul-
cata ; but disc plane, smooth, and neither
radiated nor granular. KSA. p. 31.=
GaUionella plana, ERBA. 1845. Fossil.
Patagonia. D. 1-1152". This fomi may
possibly be M. sulcata, with its markings
desti'oyed by igneous action.

M. Hctrurica (K.). — Small; joints
cylindrical, smooth, twice as long as
broad, with finely denticulated junction-
margins; disc convex, marked with
dotted rays. KB. p. 55, pi. 2. f. 6. Fossil.
San Fiore. Diam. 1-3600" to 1-800".

M. granulata (E.). — Joints longer than
broad, with horizontal punctated lines
on each side of the median suture, and
denticulated junction-margins ; disc with
a series of marginal pimcta. — GaUionella
(/ranulata, EA. p. 12.3; M. raanv figures ;
'G. tenerrima, EM. pi. 39. f. 50; OrtJio-
sira punctata, SBD. ii. p. 62, pi. 53. f.
339. Fresh water. Ehrenbcrg gives
upwards of 50 habitats in Europe, Asia,
and America.

M. (3. maxima. Disc with 31 mar-
ginal denticulations, and sti'ongly akin
to 31. sulcata.

M. MarcMca (E.). — Resembles 3f.
f/ramilatn ; but the dotted lines are pa-
rallel to the suture, and not horizontal. =
GaUionella Marchica,'EM. several figures;
G. procera, EM. pi. 15 a. f 1. Fresh
water. Europe, Asia, Africa, and Ame-
rica.

M. clccussata (E.). — Resembles M.
ffi-anulatn ; but the dotted lines are dia-
gonal and decussating. = GaUionella dc-
cussattt, EM. several figures. Fresh
water. Asia, Africa, and Ameiica.
Kiitzing includes, perhaps correctly, M.
Murehica and M. (/ranulata mider this
species.

M. lirata (E., K.).— Has the habit of
M. r/ranulutu, but witli more conspi-
cuous lines, disposed like the strings of

a lyre. KSA. p. 31.= GaUionella lirata,
EM. pi. 2. 3. f. 33. Fossil. America.

M. spiralis (E.,K.).— Filaments cm-ved
and spiral ; joints small, oblique, longer
than broad, or equal, loosely punctated
in transverse series. KSA. p. 31. = 6'«/-
liotiella spiralis, EM. pi. 33. 13. f. 3.
Fossil. Oregon. Diam. 1-2304".

M. Americana (Kiitz.). — Frustules in-
cluded in a jointed cylindrical tube,
separated by dissepiments of the tube,
elliptic, with striated margins and a
median fmi'ow ; disc with radiating
stiise, convex. KJ3. pi. 30. f. m.= Oi-tho-
sira Americana. Diam. 1-660". Appa-
rently furnished with internal silicious
cells.

M. Dicliieii (Thwaites, K.). — Joints
mostly longer than broad, smooth or ob-
scurely punctated, except by conspicuous
dots bordering the sutm-e ; disc obscm-ely
punctate ; sporangia ? fusifoiin. KSA.
p. 889. = Orthosira Dickieii, Thwaites,
ANH. 2nd series, i. pi. 12; SBD. ii.
p. 60, pi. 52. f. 335. Fresh .water. Cave
near Aberdeen, (xv. 29.) " The fila-
ments of this beautiful species consist
generally each of fi'om two to four frus-
tules, which are hyaline and perfectly
smooth ; centi-al cavity filled with dark
red-brown endochrome ; sporangium
fusiform, marked with numerous annidar
constrictions, whose formation is pro-
gressive, and which go on increasing
imtil the sporangium is fuUy developed
(xv. 296. 29 B. a filament, the termmal
cells of which have each commenced to
develope a sporangium ; and f. 29 c. a
mature sporangium). This foi-mation
thus occurs : at the commencement of
the formation of a sporangium, the endo-
chrome, at the same time that it with-
draws from the end of the frastide, pro-
duces at its centi-e an additional ring of
ceU-niembrane ; and, this process con-
tmumg to take place at certain intervals,
each new ring ot cell-membrane exceed-
ing in diameter those previously formed,
produces at length the structure repre-
sented in f 29 c ; or it may be a more
coiTcct explanation of the process to say
that an entire now cell-membrane has
been developed by the young sporangiimi
at the time each new ring lias been
fonned, and that thus have originated
the several chambers into whicli tiie ends
of the sporangium are divided; fissi-
parous division subsequently t^ikesnlace,
and sporangial frustules are developed
fi-om each half, as showni in f. 29 D."
Professor Smith doubted whether the
fusifonn bodies are sporangia, as " this

OP TITE MELOSIEE^TS.

821

mode of development, iu the fonnntion
of sporangia, stands alone and imsiip-
ported — a serious difRenlty in the way
of admitting Mr. Thwaites's conclu-
sions." For this and other reasons, he
was disposed to refer the process to the
development of internal cells, as in Meri-
dion, Himantidium, Odontidium, and
Achnanthes, and recorded his impression
that the process was not connected with
the sporangia.

M. tenuis (K.). — Very slender; joints
cylindrical, smooth, longer than broad,
closely connected, produced at their
jimction. KB. p. 54, pi. 2. f. 2. In the
polishing powder of Luneberg. Diam.
1-5760".

M. Garganica (Rab.). — Very slender ;
joints two or three times as lono; as
broad, with stout, protuberant, mdi-
stinctly dentate junctions; disc flat,
punctated on the periphery. Rab D. p.
14, t 2. f. 8. Italy. After burning, it
reminds one of M. tenuis.

Doithtful and imperfectly described
Species,

M. Dozyana (Van den Bosch). — Joints
cylindiical, finely pimctated; length
equal to or a little longer than the
breadth. KSA. p. 29. Stagnant water.
Holland. Diam. 1-1152" to 1-770".

M. circidaris. = G(dlionella circidaris,
EM. pi. 35 A. 9. f. 3. Asia and America.
Filaments slender, ciu'ved ; joints broader
than long, closely connected, smooth,
with a single sutural line.

M. Gallica. = Gallionella Gallica, EM.
pi. 9. 2. f. 2. Fossil. France, The
frustule has one diameter twice as long
as the other, and no suture or sti'ise.

M. hcdophila = Gallionella halophila,
EM. pi. 37. 5. f. 1. Europe. Fi-ustules
minute, smooth.

M. tccniata= Gallionella 'tcsniata, EM.
pi. 39. 3. f. Go. Atmospheric dust. The
ngiu:e shows a single subquadrate fins-
tme, without any distinguishing cha-
racter.

M. trachealis = Gallionella trachealis,
EM. pi. 8. 2. f. 18. Ilungaiy. Ehreu-
berg's figure is too imperfect to bo in-
telligible.

M. laminaris = Gallionella laminaris,
EM. pi. 39. 3. f. 64. Asia. The imper-
fect hgm-e shows striated junction-mar-
gins.

M. Scala = Gallionella Scahi, EM. pi.
8. 1. f. 24. Hungary. Tlio iiguro re-
rcsents a slender continuous filiunent,
ivided into smooth quadrate joints.
M. ? mcsodon = Gallionella ? mcsodon

(Fragilana mesodan?), EM. pi. 11. f. 16.
Bohemia. Filament slender, conti-
nuous, with smooth subquadrate joints,
having two puncta at each outer margin,
as in Fi-agilaria.

M. ochracea. = Gallionella femiyinea
(Ralfs). — Slender, oval, convex at both
ends ; smooth. In many, perhaps in all
chalybeate waters, and also iu peat-
water, which contains a small proportion
of iron, this is to be found ; it is of the
colour of iron-mst, and in mineral
springs, in which it abounds, is often
taken for precipitated oxide of iron. It
covers everything under water, but
forms so delicate and floccose a mass,
that the least motion dissipates it. In
the spring of the year, this mass is com-
posed of very delicate pale-yellow glo-
bules, which can be easily separated
from each other. They unite together
in rows, like short chains, and produce
an irregular gelatinous felt or floccose
substance. About siunmer, or in autimm,
they become developed into more evi-
dently articulated and stiff threads, of a
somewhat lai^er diameter, but still form
a complicated mass or web, and, either
from adhering to each other or to deli-
cate Confervte, appear branched ; in the
yoimg condition, when examined under
shallow ma^itiers, they resemble gela-
tine ; but with a power of 300 diameters,
the flexible granules are discoverable,
and, with dexterous management, the
little chains forming the felt or floccose
web can be made out. In sunmier, on
the other hand, its sti'ucture can be ob-
served much more easily and distinctly.
Early iu spring, the colom- is that of a
pale yeUow ochre ; but in siunmer, tliat
of an intense rusty red. Diam. 1-1200".

According to tiitzbg, this is not a
species of Gallionella, but a Conferva ;
it has no true silicious lorica, as have
true Diatomeos ; and the coating of oxide
of iron is not an essential element, but
merely an incrustation, such as will form
on well-known Confervie placed under
like circmnstances, i. c. in water holdino-
salts of iron in solution, whicli are sub-
sequently precipitated by exposure to
the air, and converted into tlie rod oxide

The same author dill'ers from l^hreu-
borg as to tlie part pla^yed by the so-
called Gallionella ferrifr/i'nca in the pro-
duction of tlie oxiclo of iron in chalybeate
waters, of bog-iron ore, of clay-iron ochre,
&c. For, lie observes, in iiiaiiy springs
ricli in iron no such orgniiisni "is found
althougli other Conferviu may be ]n'osont
— Conferva!, however, not pcculiai- to

822

SYSTKMiTIC UlSTOllY OF TUG INPUSOHIA.

sucli habitiitS; but common iu springs
and ponds generally.

Ml'. KaKs {op. cit. p. 852), however,
in part supports Ehrenherg, declaring
that, though identical with Conferva
ochrucea (DiUwj'n), yet " Ehrenherg is
no douht coiTect in placing the plant in
this genus, as the filaments are sUicious
and cylindrical."

Niigeli describes and figures a species
which he refers to the genus Gallionella ;
but it is a doubtful member. His de-
scription, however, especially that of the
self-division, induces us to give it nearly
in his own words, with his name (Ray
Society, 1846, p. 219).

M. Niu/eli (E,.). — Shortly cylindiical ;
diam. •0i4"' to -027";. Marine. Naples.

"Both the terminal surfaces of the
cylinder are flattened ; so that, when seen
sideways, it appears rectangular, with
the angles roimded ofi". It is composed
of one simple cell, whose membrane is
covered by a siliceous plate; and its
cavity contains chlorophyll-gTanules,
which lie upon the membrane in two
cii-cular bands, (xv. 26-28.) Each of
these bands occupies one of the obtuse
angles of the cylinder, and appears annu-
lar from above, rectilinear from the side.

" In developing, the relative length of
the cylinder increasing, a septum divides
it into halves (xv. 28 c), which when
complete, the latter separate as two di-
stinct beings. The nascent chlorophyll-
granides are either spread equally over
the surface, or more frequently arranged
in radii from the nucleus in the centre ;
they lie in the course of the currents
streaming from the nucleus. Compared
with a cell of Conferva, or of Spii'ogyi'a,
all three agTee in the forming of a septum,

in the similarity of their contents, and iu
the depositions of extra-cellular sub-
stance. But Gallionella diflers from
both, by the production of an individual
from every cell, also by the chloropliyll
forming two lateral band.s, and the sili-
ceous extra-cellidar substance an inter-
mediate one.

" So far as my investigations go,
Gallionella, which, according to Ehren-
herg, possesses a bivalved or multivalved
shield, agi'ees with the above-described
plant in all essential particulars. The
lines, for instance, whic-h would intimate
a division of the shell into two or more
pieces, are the septa by which the ceU-
division is efl'ected. As in the filiform
AlgSB, these walls at first appear as deli-
cate lines ; then, by an increase of thick-
ness, seem two clearly defined lines ; and
at last present themselves as two lamellae,
separated by an intermediate thfrd line.
The perforations which Ehrenherg de-
scribed, I look upon as nothing more
than intercellular spaces, formed be-
tween the two new-foiTued cells and the
parent cell. These so-called perforations
ai'e only visible, therefore, on the two
lateral borders where the wall abuts
upon the membrane. The Confei-void
Algae exhibit a simUai' appeai-anee."

Gallionella (?) Novcb HollandicB (Ehr.),
Avon EiA'er, Austi'alia ; G. gibba (Ehr.),
fossil, Georgia; G. punctata (Ehr.),
Western Asia; G. tincta (Ehr.), Ural
Moimtaius ; G. gemmata (Ehr.), Siberia;
G. lineolata (Ehr.), fossil. North Asia;
G. unclata (Ehr.), llinialaya Mountains ;
G. curvata (Ehr.), India; G. vaginatu
(Ehr.), India; G. Nilotica (Ehr.), River
Nile, are species known to ua only by
name.

Genus ARTHROGYRA (Ehr.). — The characters of this genus are unknown
to us ; but, judging from Ehrenberg's figures of the species, it seems to have
been constituted for the reception of those forms of Melosii-a which, like M.
Dichieii, produce horizontal, elongated, tapering internal bodies or sporangia.

AnTHnoGYnA Gmtimalensis, EM. pi. A. semilmaris, EM. pi. 33. 6. f. 2.
33. 6. f. 1. Fem-earth. Guatemala.— Guatemala.— Filament jointed, cm-ved,
Filament straight, jointed, with crenated with crenate mai-gins, and semilunate
margin, and straight, fusitbi-m internal internal body,
body.

Genus DISCOSIRA (Rab,). — Fnistules united into a short filament, with
a thick mucous covering ; in lateral view circular, having a uniformly pimc-
tatc centre, a border of numerous (24 to 33) slightly cuiTcd, oblique, ray-
like lines, and a marginal crown of teeth (50 to 64).

UiscosrRA sulcata (Rab.). — Frustidos I rows, which correspond to (he teolh of
in front view with deep transverse fm'- | the lateral sm*face. JRabD. p. 12, t. 3. In

OP THE MELOSrUEJE.

823

a lag'oon at Maiifrcdonia, east coast ol" I lato, but requires the highest mag-uify-
italy. Each tooth is minutely denticu- | iug powers to ascertain it. (v. G8.)

Genus LirAROGYRA (Ehr.).— Fnistiilcs simple, cylindrical, each having
an internal spiral filiform band or crest.

The habit of this genus closely resembles that of Spirogyra, a non-sihcious
genus of Algoe.

LrPAiiOGYRA denclroteres (E.). —
Frustiiles smooth, crystalliue, three or
four times as long- as broad, with an
internal spiral band ; margin of disc
denticulated. Rah D. p. 12. =L. spiralis,
EM. pi. 34. 5a. f. 1, 3. On tiimlfs of
ti'ees. Venezuela. Tliirteen spirals in
1-360". (v. 72.)

L. circidaris (E.). — Frustule with 13
aunidar tmns of intei'nal line in 1-360".

Rab. I. c. p. 12. With the preceding, and
in Brazil. Ehrenberg says he is not
satisfied whether the preceding are di-
stinct species, or merely varieties. Each
has a smooth disc, with three central
apiculi.

L. scalmis, EM. pi. 34. 5 a. f. 2. South
America. Ehrenberg's figm-e represents
the frustule in frout view as divided by
cross bars in a ladder-like manner.

Genus POROCYCLIA(Ehr.). — Resembles Lipai'ogyra, but is without spii-es,
has interior circular rings, and the margin of its disc-like ends a cii'clet of
deep impressions. "We doubt whether this genus is suflSLciently distinct from
Liparogyra.

PoBOCYCLiA denclrophiJa (E.). —
Frustules smooth, with 9 annular lines ;
disc with 12 mai'ginal depressions.

radiating series of puncta, and 5 central
apiculi. RabD. p. 12. On trunks of
trees. Veneziiela. L. 1-320" j w. 1-560",

Genus STEPHAJS'OSIRA (E.).— 'Frustules united into a short filament ;
disk with radiating series of miaute puncta, and a marginal crown of teeth.
In form this genus resembles Stephanodiscus, but differs from it, and becomes
allied to Melosii-a by its imperfect spontaneous division, and consequent con-
catenation. In Melosira, however, the circlet of spines is wanting. "We are
unacquainted with this genus ; and its characters scarcely suffice to distinguish
it from Orthosu-a. All the known species are found on trees.

Stephanosira Epidendron (E.). —
Front view with punctated transverse
lines and ftuTOw. Rab D. p. 14. On ti'ees.
Venezuela and Brazil. Larger diameter
1-432"; smaller 1-4.320".

S. Hamadnjas (E.). — In front view
smooth, but with jimction-margins stri-
ated; disc having marginal radiating
puncta, and its centi'e a few scattered
dots. Rab. /. c. p. 14. On trees with the

preceding species. Diameter 1-720".

S. Huropcsa (E.). — Frustules often
broader than long, smooth, but with very
faintly striated jimction-margins. Rab.
/. c. p. 14. Among mosses on trees at
Berlm. Much smaller than the preced-
ing. Chain foniied of three to fom- frus-
tides, each 1-2304" to 1-1152" in depth ;
rarely 1-1200" in width.

Genus STEPHANODISCUS (E.).— Disc with radiating series of puncti-
form granules, and furnished with a crown of erect marginal teeth. Aquatic.
Stcphanodisci approximate in character to Cyclotclla, but differ from them
by the circlet of teeth. They also approach closely to the non- cellulose
Coscinodisccaj, and seem to have as good a claim to rank with that family as
with the Melosireae. Stephanodiscus differs from Odontodiscus in the same
manner a,s Peristophania docs fi-om Systcphauia, and ia oiu" opinion might,
without inconvenience, be united to it.

STEi'iiANoniscuH Berolinemis (E,).
—Small, tliscoid ; disc plane, finely radi-
ated, and furnished with acute marginal

teeth (often 32) on each side. KSA.
p. 21. Alive, Bcriin. Diam. 1-1152". In-
ternal granular substance brown, lobed,

824

SYSTEMATIC HISTOIIY OF THE INFUSOEIA.

S. Mjypliacus, EM. pi. 33. 1. f. IG.
Egj'pt. Ehreuljerg's ligiire ropresents
the disc with scries of puncta radiating
from the centre, without a distinct um-
bilicus, the teeth nimierous, subulate,
and erect, (v. 69.)

S. Sinensis, EM. pi. 34. 7. f. 7. Canton.
Ehreuberg's figure shows the puncta
arranged as in S. jEgy2Jtiunis, but the rim
striated, and the teeth nodule-like and
intra-raarginal.

S. Bramaputra, EM. pi. 35 a. f. 9, 10.

Ganges. Puncta as in the foregoing
species, the rim furnished with short
triangidar teeth.

S. Niagara: (E.). — Frastules small;
disc with numerous (often 64) series of
punctiibnu granules radiating from a
large gi-anidated umbilicus, and as many
acute marginal teeth as rays. EM.
pi. 35 A_. 7._ L 21, 22. Niagara. This
species is distinguished by its gi'anulated
umbilicus.

Genus PERISTEPHANIA (Ehr.).— Frustulcs simple, discoid; disc with
decussating parallel series of gTanules, aiid numerous marginal teeth. Mari-
time. " The characters of this genus so weU agree with Stephanodiscus that
perhaps we might more correctly refer the deep-sea form to that genus. But
as the hitherto known Stephanodisci are all liuviatile, and the maritime form
in the order of its cellules very nearly approaches the purely maritime Gosd-
nodiscus lineatus, I have prefeiTed not mixing liuviatile Stephanodisci -with
a doubtful maritime form. Perhaps the flow in deep water may have com-
mingled a flnviatile form with the maritime ones. Should, therefore, a similar
form be hereafter found in any liver, this generic name must be cancelled, and
the form placed in Stephanodiscus " (EllBA. 1854, p. 236). As we consider
habitat altogether inadmissible as a generic distinction, we would distinguish
Stephanodiscus and Peristephania by the radiating granules of the foiTuer,
and their parallel arrangement in the latter genus. We should prefer to
unite this genus with Systcphania, which differs only in having in ti-a- mar-
ginal teeth. Perhaps even Coscinodiscus lineatus might be included, thus
making the parallel arrangement of the granules the essential character.

Peristephania Eutycha (E.). —
Habit of Coscinodiscus lineatus; niargin
of the disc armed with nimierous erect,
crowded teeth. EM. pi. 35 b. 4. f. 14.
Deep soundings of the Atlantic, (v. 73.)

P. lineata (E.). — Resembles P.

Eutycha, but its teeth ai"e fewer and more
distant. EM. pL 33. 13. f. 22. Califomiaii
deposit and guauo.

In both species the teeth are miuutc

aud triangulai".

Genus PYXIDICULA (Ehr.). — Frustules simple or binately conjoined,
free or adnate, bivalvcd ; central portion obsolete ; valves veiy convex. lu
Pyxidicida the frustulc forms a bivalved box, and differs from CycloteUa in its
vaulted valves and the absence of an interstitial portion. The same characters
distinguish it from aU the Coscinodisceac. As fii'st constituted by Ehrenberg,
Pyxidicida contained very heterogeneous forms ; by the fonnation, however,
of Mastogonia, Stephanogonia, Steiilianopyxis, and Xanthiopj-xis as distinct
genci'a, this defect has been in a great measiu'c removed ; but wc believe it
still includes some doubtful species. Dictyopyxis was separated by Ehren-
berg, first as a subgenus and afterwards as a genus, for those forms character-
ized by the cellulose stnicture of the valves, leaving in the original genus the
smooth and punctated species. Wc have thought it more desii-able to regard
Dictyopyxis as a subgenus only, nntU. some of the species arc more fully
known.

* Frustules smooth or minutely punctate.
Pyxidicula.

rvxinicui.A ojiercnlnln (E.). — Frus-
tulcs small, orbicular, hyaline, punctated.

EM. pi. 16. 1. f. 46. = P. minor, KSA.
p. 21. Fossil, Sweden ; recent, Asia, Eng-
land P Dinni. 1-1440" to 1-570". Valves
joined by a distinct suture. Kiitzing
rcfei-3 P. operculata (E.) to C3Tlotella.

OF TUE MELOSIEEiE.

825

V.Adridlica (Kiilz.). — Adnate, sessile, |
of middle size ; valves convex, nearly
henii.splierical, very smooth. KB. t. 21.
f. 8. Adriatic, (xiii. 33.) Diam. 1-000".

P. ? prcctexta (E.). — Valves o-eminate,
slightly hispid, neither celliuose nor
radiated, hut bordered by a raised limb ;
midtUe tlat. KSA. p. 22. Fossil. Greece.
Diam. 1-1152".

P. P urccolaris (E.). — Valves geminate,
imequal, m-ceolate (the one more convex,
elongated, the other shorter), each vpith
a plane, raised limb ; cellules none, but
about ten smooth rays in the longer, and
eiglit apiculate ones in the shorter valve.
= Dictyapyxis urceolaris, EM. pi. 18. f. 3.
Fossil. Virginia, Diam. 1-1728".

P. lonya (E.). — Oblong, two and a
half times as long as broad, cylindrical,
with roimded ends ; suture longitudinal.
KSA. p. 22. Fossil. Virginia. L. 1-1080".

2* Frustuhs cellulose. Dictyopyxis (H.).

P. cruciata (E.). — Frastules oblong,
with rounded ends ; cellules laro'e, ar-
ranged in parallel lines; rim distinct.
EM. pi. 18. f. 2. = Coscinodiscus cruciatus,
KSA. p. 125.

^.Helleniea, smallev= Dictyopyxis Hel-
lenica, EM. pi. 19. f. 13. Fossil. America.
Guano, &c. Frequently the disk has
some series of its cellides more conspi-
cuous and forming a cross. Valves cam-
p.anulate.

P. Cylindrm (E.). — Cylindiical, with
rounded ends, three times as long aa
broad ; valves with obscure rows of cel-
lides. EM. pi. 33. 13. f. 8. Fossil. Mary-
laud. Diam. 1-960". Valves campanu-
late, separated by a suture.

P. Lens (E.). — Frustules laterally de-
pressed, lenticular, cellidose; valves in
front view semielliptic. EM. pi. 18. f. 5.
Fossil. Virginia. Diam. 1-036". The
trustide is oval in the front \-iew, the
suture forming tlie gi'eatest diameter.

P. areolula (E.). — Valves with a
heptagonal, areolate, punctated centre,
and seven lateral punctated areola).
KSA. p. 22. North America. D. 1-960".

P. yemmiftra (E.). — Valves turgid,
crystalline, not bordered, furnished with
lax scries of crystalline nodules, fifteen
of wliich very nearly reach the smooth
centre. KSA. p. 22. Fossil. Maryland.
Diam. 1-792".

P. compressa (IBail.).— Frustules'ellip-
tic, bi\ alve ; vfdvos separated by a plane
passing through the longer axis, sliglitly
convex, and with transverse rows of dots.
Be. ii. p. 40, f. 13, 14. Florida.

P. dentata (E.).— Fnistulcs having the

convex margin furnished with (irregular)
slightly prominent little teeth ; cellules
rather large, 6 in 1-1200". KSA. p. 22.
Antarctic Ocean. Diam. 1-840".

P. P limhata (E.). — Frustules oblong-,
with a central lieel ; valves showing in
front a central cellidar surface, and 32
to 40 radiating lines; border not cel-
lulose. = Steplianopyxis limbata, EM.
pi. 18. f. 7. Fossil. Maryland. D. 1-792".
Ehrenberg's figm-e is oval, and has a
broad, distantly striated, but not cellu-
lose rim, and in its centz-e scattered gi'a-
niiles.

P. cristatci (E.). — Frustules with gemi-
nate, lenticular valves, which are close
together, not winged, with a somewhat
prominent margin like a thin suture;
cellules of disc in rows. = Stephanopyxis
cristata, EM. pi. 18. f. 6. Fossil. Vii--
giuia. Diam. 1-816". Ehrenberg's figiu-e
somewhat resembles that of P. limbata ;
but the cellules of the oval valve are
crowded, and the striated rim is nar-r
rower.

Obscure or doubtful S^jecies.

P. Ndyelii (Kiitz.). — Smooth, one side
orbicidar, girt with a membranous wing-
like ring ; the other side oval, one mar-
giu more convex, nmbonate in the mid-
dle. KSA. p. 889. Switzerland.

P. Actinocyclus (E.). — Frustules with
two flattened, finely cellulai- and ele-
gantly radiated valves; rays 30 to 40,
straight and dense, EM. pi. 18, f. 19.
= Cyclotella Actinocyclus, KSA. p. 20.
Fossil. America. Diam. 1-720". Ehreu-
bei;g figui-es only the lateral view, which
in its radiating series of dots resembles a
Coscinodiscus,

P, Scarabccus (E.). — Oblong, with
imequal valves ; when viewed laterally,
recalling the figure of the Scarabfeiis.
= Dictyopyxis Scarabccus, E, Fossil.
Vii-ginia, Diam. 1-648". Cellules 14 iu
1-1150".

P. major (Kiitz.). — Frustules large,
elliptic, regidarly punctated. KP. t. 1.
f. 25. North America ; France. Diam.
1-420". Probably a state of P. cruciata.

P. ylobata. - Wo insert under this
name certain spherical bodies of a dia-
meter varying from 1-240" to 1-1150"
discovered in 1830 by Elirenborg iu
flints near Berlin, and considered by hiiu
to belong to the silicious Diatomacoiu.
Kiliziiig has oxaniined these bodies,
wiiich occur along with silicious spicida
of sponges and snecies of Xantliidium
and Peridinium, but docs not consider
them Pyxidicala2. Tlic section of pebble

826

SYSTEMATIC HISTOHY OF THE INFCSOHIA.

contaiuiiig these specimens, from wliicli
Mr. Bauer's drawings (x^ste. 606-509)
-were made, was found on Brighton
beach. The figures are magnified 100
diameters.

P. prisca, EM. pi. 37. 7. f. 5. This
species is found in uints, and is probably

the same as the preceding.

P. (/ifjas, EM. pi. 33. 13. f. 18. Fossil.
California. The figure shows a large
orbicular disc, vnt\\ distant scattered
dots, and no sutm-e.

P. decussata (E.). — Found in the chalk
marl of ^gina.

Gemis STEPHANOPYXIS (Ebi-.).— Frustules simple or united into short
filaments, in front view orbicular or oblong, composed of two ceUuloso valves,
each having a crown of teeth, spines, or membrane ; central portion obsolete ;
lateral view cii'cular. " This group includes those Pyxidieulaj which have
turgid forms -with a cellular surface, bearing in the middle of the valves a
crown of small teeth, prickles, or a membrane " (Bailey). The fossil species
appear simple ; but as recent specimens forming short filaments have been
obtained by the Eev. R. Cresswell and Mr. Norman, probably the othere aLso
were oidginally so formed, but, as the crowns prevent the close union of the
fi'ustules, they become more easily disconnected. The valves agree in their
turgid form, rounded ends, and cellulose structures with Pyxidicula ; but their
coronets will easily distinguish them.

SxEPHANOPyxis Diadema (E.). —
Valves hemispherical, with parallel,
straight rows of cellules ; centre of disc
depressed, with a circlet of niunerous
teeth (20 to 30). = Pyxidicula Diadema,
KSA. p. 21. Fossil. Virginia; guano.
Diam. 1-576". "We have seen two frus-
tules connected.

S. Turris. — Frustides cylindrical, cel-
lulose, ends depressed at the centre and
fiu'nished with a crown of spines or pro-
cesses, which are truncate or clavate at
their apices ; areolaB hexagonal, 7 in
•OOV' .= CresswelliaTurris,(jY&Y. in GDC.

p. 64, pi. 6. f. 109. In stomach of Ascidia.
Teignmouth, HuU, &c. Fossil in guano.
We regret being imable to accept the
genus Cresswellia, as we believe all the
species of Stephanopyxis, when recent,
have the frustules connected by their
coronets : S. Diadema, a species closely
allied to the present, we have foimd so
imited in specimens from guano. This
character has probably escaped detection
only because in all filamentous forms the
fossil frustides are usually separated.
The coronets of mmierous non-attenuated
spines distinguish this species, (v. 74.)

S. apiculata (E.). — Frustules oblong
or subcylindrical, end broadly rounded ;
ceUides not crowded, arranged in longi-
tudinal rows ; centre of disc Avith a few

Genus XANTHIOPYXIS (Ehr.).— Valves turgid, continuous, entire, non-
ceUulosc, hispid, setose, or winged. = Pj^dcUcula oUm. Fossil. " These forms
arc Pyxidicula Avith bristles, seta3, or wings. They have the habit of Aau-
thidium and Chajtotyphla, but arc bivalved and silicious." The true affimty
of this genus is doubtful : we have seen no species which is circular m the
lateral new, and consequently consider them misplaced in the Mclosirca; :

elongated spines, EM. pi. 19. 13. f. 6.
America, Em'ope, guano, &c.

S. appendiciduta (E.). — Frustules in
fi'ont view subglobose, coarsely and
closely cellidose ; segments with rounded
ends, each with an exceutiic, short, hom-
lilce process. EM. pi. 18. f. 4. Fossil.
Vu-ginia. Diam. 1-624". Processes trun-
cate, not central; cellules forming a
crenated mai'gin.

S. turgida (Grev.). — Front view cylin-
drical-oblong; junction-mai'gins subtrun-
cate, with roimded angles and a crown
of elongated spines with dilated apices ;
areola3 11 in -OOl. = Crcsstccllia turqida,
Grev M J. vii. p. 165, pi. 8. f. 14. Cali-
fomian guano. This species is neaily
related to S. Turris, but differs in the
larger, more ti'uly cylindrical and trun-
cate fi-ustides, and in the considerably
smaller areolation, Grev.

S. ferox (Grev.).— Front view oblong ;
valves subglobose, canipamdate, hispid,
with a crown of elongated spines and a
thin, hyaline, prominent sutm-e ; ai-eolaj
large, 5 in -001". = Cresswellia? ferox,
GrevMJ. vii. p. 166, pi. 8. f. 15, 16. Ca-
hforuian guano. The valves are ex-
panded at thcu- junction so as to_ form
a sutm-al keel, as in some species of
Pyxidicula. (v. 75.)

OF THE COSCINODISCEiE.

827

but, from oiu- iusufliciont acquaintance wth them, we are unaLlc to decide on
their proper position, and have not attempted their removal. Are they aldn.
to Goniotheciiim ?

Xanthiopyxis f/Iobosa (E.). — Frus-
tules subglobose, hispid, with short sette.
= Pyxidiciila (jluhosa, KSA. p. 23. Fossil.
Bermuda. Diam. 1-552".

X. obluiu/a (E.). — Frustides oblono-,
equally and broadly roimded at each end,
densely hispid, with short setiB, which
are sometimes joined by a membrane.
EM. pi. 33. 17. f. 17. = Pyxidici.da(K.).
Fossil. Virginia. L. 1-552". (v. 76.)

X. constricta (E.). — ^Frustules oblong,
constiicted at the middle, and broadly
rounded at each end, hispid, with short
seta9, which are often jomed by mem-
brane. =P(/a;iV/iCM/a co«s<ncto, KSA. p. 23.
Fossil. Bei-muda. L. 1-384". Diflers
fi'om X. ohlonga by its consti'iction.

X. hirsuta (E.). — Frustides bivalved,
subglobose, not cellulose, rouoh with
simple and obsoletely forked hau's. =
Pi/xidimla ? hirsttta, ERBA. 1845. Fos-
sil. Maryland. Diam. 1-115". Habit

of Xanthidium, but silicious.

X. urceolaris (E.). — Valve urceolate,
with the summit bristly ; mai-gin revo-
lute. EM. pi. 33. 16. f. 14. Fossil. Vir-
ginia. Diam. 1-1560". "I [EhrenbergJ
have oulj' met with single valves. In
form they resemble Stephanogonia, but
are not angular."

X. alata (E.). — Frustides smooth, ob-
long, each end equally and broadly
rounded ; margin of the valves bordered
by a lacerated or deeply dentate, not
setose membrane. = Pyxidiciila alata,
KSA. p. 23. Fossil. Bei-muda. D. 1-552"-

Doubtful Diatom.
X. aculeata (E.)=Pi/xidimla acnleata.
The fio-ure in Microg. pi. 18. f. 124 shows
a globidar spinous body, resembling
some sporangia of the Desmidiese. Eh-
renberg himself regards this as a veiy
doubtfid Diatom.

Genus INSILELLA (Ehr.). — Frustules simple, equally bivalved, cylindrical
(fusiform), with a turgid ring interposed in the middle between the valves.
Marine. Resembles a cjlindi'ical Biddulphia.

InsH/ELLA ^/7"jcana (E.). — Frustides | others decreasing at each end, oblong;
fusifoi-m, smooth, four times constricted ; each apex acuminated. KSA. p. 32.
the middle joint lai'gest, subglobose j the Mouth of the river Zambese, Afi'ica.

FAMILY VIII.— C0SCIN0DISCEJ3.

Frustules disciform, mostly simple ; lateral valves or discs flat or convex,
ccUuIose, areolate or granulate, without processes, but sometimes fiu-nislied
with spines or teeth ; connecting zone ring-like and generally smooth. The
Coscinodisceae are closely allied to the Melosirea;, — a fact noticed by Kiitzing
liimseLf, although in liis arrangement the families are widely separated. The
distinction between them is by no means satisfactoiy ; according to Kiitzing,
it consists in the cellulose or ai'eolated structiu-e of the Coscinodisceas. But
whilst on the one hand we find in the Melosirese some species of Pyxidicula
and Stephanopyxis with ceUiilose valves, on the other hand, in tliis family
some species are merely granulate or punctate. Practically, however, the
proper situation of the species can generally be determined witliout much
diificulty. In the CoscinodLsccas the finstules never form filaments, the con-
necting zone Is always present, narrow and ring-lilce, and the lateral valves
are never so convex as to be hemispherical or campanulate ; so that the disk
is almost always in the field, it being difficult to obtain a good front view.
Most of the fonns included in this family are marine, and many ai'o remark-
able for their exceeding beauty.

Genus C'OSCINODISCUS (Elir.).— Fni.stulc.s simple, discoid; disc cellular
or dotted, without processes, defined border, internal septa, or division into
radiating compartments. " The only essential character that distinguishes

828

SYSTEMATIC mSTORY OF THE IKFUSORIA.

this genus from Cyclotclla is the aroolation of the scconclary surfaces"
(Mcncg.). " This genus finds its nearest allies in the Melosiroaj, whose
genera, from their filamentous character, stand widely apart. "Were the
frustivles of Coscinodiscus eccentricus, for example, permanently coherent after
self- division, it would be difiicult to separate them, in a generic point of
view, from those of Orthosira nivalis, which have the same cellular structure,
or from those of Melosira auriclialcea or M. sulcata, which are furnished
with a projecting fringe of silex, the homologue of the spinous processes in
C. eccentricus" (Smith, BD. i. p. 23). Coscinodiscus is easily distinguished
from most genera in this family by a disk not divided into compartments.
In the greater number of species the cellules have a radiating arrangement,
and become smaller near the margin ; the former character, however, is fre-
quently obscure, and is best seen by as low a magnifying power as will suffice
to determine the ceUular or dotted structure.

* Disc tcith a few central larger {gene-
rally oblong^ cellules, stellately arranged,
and forming an umbilical rosette {rim
striated).

t Disc large, and its cellules distinct.

Coscinodiscus centralis (E.). — Cel-
lides minute, nearly equal, in crowded
radiating series; umbilical rosette of a
few oblong- ceUiiles round a cu'cular one.
EM. pi. 18. f. 39 ; GDC. p. 28, pi. 3. f. 50.
Fossil. Virginia and Sicily. A large
species with striated rim,

C. omphalanthus (E.). — CeUides in
radiating series, marginal ones smaller,

7 to 8 in 1-1200", middle ones larger,
6 in 1-1200" ; umbilical rosette of 7 or

8 large oblong cellules. KSA. p. 125.
Bermuda deposit. Disc large. D. 1-96".
Mr. BrightweU finds it difficult to distin-
guish this species from the following,
and considers then' specific characters
vmsatisfactory.

C. Oculus Iridis (E.). — Cellides hex-
agonal, in radiating series, smaller at
tlie margin and near the umbilical rosette,
which IS formed of from 5 to 9 large
oblong cellules. EM. pi. 18. f. 42. Fossil
and recent. America, Em'ope, Milford
Haven, &c. This large species, when
dry, is marked with colom'ed rings, — ^^au
effect apparently due to the peculiar
arrangement of its cellules. It diflbrs
from C. centralis in its larger cclhdes,
and from C. asteromphalus by tlio absence
of a veil. "This species, "both in the
recent and fossil specimens,^ often ac-
quires a size not much inferior to that
of C. (/if/as " (Bailey).

" C. 'borealis (Ball.). — Disc having at
its depressed cenlTo a conspicuoiLs sinr,
formccl of about G large cellules. The
rest of the surface covered with inter-
niptcdly radiant lines of prominent hex-

agonal cellules, which increase regularly
from near the centi-e to the convex
margin." B. in Amer. Jom-n. of Science
and Arts, 1856. Sea of Kamschatka.
" This resembles C. Oculus Iridis ; but
the cellules formuig the star are more
roimded, and the other cellules ai"e
larger " (Bailey).

0. asteromphalus (E.). — CeUides in
radiating series, smaller towards the
margin ; umbilical rosette distinct ; sm*-
face appearing as if covered by a very
finely punctated veil. EM. pi. 18. f. 45.
Fossil. America. Cellules large, rather
tumid. C. asteromp)halus differs from the
other species with stellate mnbUicus by
its minutely punctated cellules.

2 1 Disc with cellules obscure, and re-
qumng the higher magnifying powers
to discern them.

C. coiichmm (Sm.). — Disc lai^e, with
radiating series of minute puncta, and
an umbilical iii-egular rosette of larger
celhdes, divided into compartments by
radiating lines, which temimate at tbe
margin in minute spines, (v. 89.) SBD.
ii. p. 85; Roper, MJ. vi. p. 20, pi. 3. f.l2.
Eiu'ope. Valves convex. Li some spe-
cimens the markings are very inconspi-
cuous, and difficult to detect; in others,
as m the specimens from Hull, more
evident.

C. stellaris (Roper). — Disc extremely
liyalinc, with very fine, inconspicuous
radiating series of puncta, and a few
larger, stellately nrr.angod umbilical cel-
lules, (y. 83.) ' RoMJ. vi. p. 21, pi. 3.
f. 3. Caldy, rombrokeshire. Wlien
mounted in balsam, the disc is so hya-
line, and the puncta so difficult to detect,
that it is liable to be regarded as a
detached ring. Dry valves brownish,
without niai-giual spines.

OF THE COSCINODISCEiE.

829

2 * Disc with a central hyaline umbilicus,
which often resembles a perforation.
(77ie species are comnionh/ smaller than
those of the j)recc(lin(/ section.)

C. actinochilus (E.). — Granules in close
lines, radiating fi-om the distinct punc-
tated luubilicus, separated fi'om the mai"-
giu by a border of pimcta arranged in
close, short, radiating lines. EM.
pi. 35 A. 21. f. 5. Antarctic Sea. The
radiating series of granules are close,
but distinct.

C. (E.). — Granules equal, ar-

ranged in distinct series, radiating from
the smooth umbilicus, and separated from
the margin by a border of minute pmicta.
EM. pi. 35 a. 21. f. 7. Antai-ctic Sea.
Somewhat resembles C. actinochilus, but
has fewer rays, the marginal pimcta are
more obscxu'e, and the umbilicus is
smooth.

C. (jemmifei- (E.). — Disk with con-
spicuous granules, ai-ranged in lax and
elegantly radiating lines fix)m a smooth
mnbiliciis; border minutely pimctated.
EM. pi. 35 A. 22. f. 8. Antarctic Sea.
Beraiuda deposit. The rays are fewer
and more distant than in the two pre-
ceding species ; but all agi'ee in having
well-marked granules, distinct rays, and
minute submarginal puncta. Diam.
1-456". Very like Pi/xicHcula gemmifera,
but lai'ger and more depressed.

C. apiculatiis (E.). — Cellules rather
prominent, apiculate, rendeiing the sm-
face rough, subequfil, radiating, 10 in
1-1200"; umbilicus smooth. EM.pl. 18.
f. 43. America. Diam. 1-324". Has
a general resemblance to Pyxidicula
gemmifera.

C ptrforatm (E.). — Cellules minute,
arranged in close, radiating series ; um-
bilicus smooth, resembling a perforation ;
margin finely rayed. EM. pi. 18. f. 40.
America. Diam. 1-348". Difiers from
C. fimbriutus by its umbilicus.

C. disciger (E.). — Difiers from C. per-
foratus by its iiTCgularly circular, not
smooth, and larger umbilicus, and by its
very minute and dense punctiform cel-
lides. KSA. p. 123. "Virginia. Diam.
1-480". Cellules about 30'in 1-1200".

C. Apollinis (E.). — Disc with nume-
rous series of very dense, equal, puncti-
form granules, radiating from a small
umbilicus. EM. pi. 35 a. 22. i. 4. Ant-
arctic Sea. It differs from C. Lunce by
the greater number and denseness of its
rays, wliich, liowever, althougli nume-
rous, are distinct. Diam. 1-432". 17
gi'anulos in 1-1200".

C. cingtdatus (E.). — Disc_ with_ very
dense, punctiform granules, indistinctly
radiating from a small clear umbilicus ;
margin with an annular band capable of
being detached. EM. pi. 35 a. 21. f. 6.
Fossil. America, Antarctic Sea. 2G gra-
nules in 1-1200". Diam. 1-552". Eesem-
bles C. Apollinis, but its granules are
denser and less distinctly radiating.

3* No umbilical vacancy ; disc ivith a
striated border distinct from the rim.

C. fimbriatus (E.). — Cellules small,
subequal, obsoletely radiating, near the
margin smaller and aiTanged in radi-
ating lines resembling strias. E. I. c.
pi. 22. f. 2. Fossil. Sicily.

C. marginatus (E.). — Cellules in curved
lines; marginal ones smaller and ar-
ranged in radiating lines resembling
stria3. E. I. c. pi. 18. f. 44. Eecent and
fossil. America, Cuxhaven. Cellules 9
or 10 in 1-1200".

C. limbatus (E.). — Central cellules
largest, not radiating, outer ones small-
est, crowded, arranged in radiating lines
resembling strife. E. I. c. pi. 20. 1. f. 29.
Fossil, Greece. Diam. 1-576". The
largest 7 in 1-1200".

C. striatus (K.). — Cellules irregularly
crowded in the middle ; margin of disc
with radiating stria3. KB. t. 1. f. 8.
Cuxhaven. Diam. 1-456".

4 * Disc with radiating so'ies of cellules ;
no distinct umbilicus, nor striated border
distinct from the lim,

C. gigas (E.). — Disc very large ; cel-
lules large, hexagonal, radiating, largest
at the margin, decreasing towards the
centre. EM. pi. 18. f. 34. Virginia ;
Maryland ; alive, Cuxhaven. The largest
species of the genus, and well character-
ized by its large hexagonal cellules gra-
dually decreasing in size from the margin
to the centre. Rim striated.

_C. cxcavatus (Grev. MS.). — Dislc large,
\vith hexagonal cellules decreasing in
size toM'ards tlie centre, which has tlirec
conspicuous depressions alternating witli
the same number of elevations. Pisca-
taway deposit. Tlie disc in this species
is, from its lar"-o size, visible to tlic
naked eye, and, lilco C. gigas, it appears
ring-lilce, the smaller central cells being
then invisible. There is no distinct um-
bilicus; but the central portion, including
the elevations and depressions, is thinner
and is rarely found perfect. Thi; cellules
of the depressions appear smaller and
more radiant than the otliers. (viu. 26.)

830

SYSTEMATIC HISTOH"? OP THE INFUSOHIA.

C. ci'ossus (Ball.). — Disc without a
contra! star, covered ■with inten'uptedly
radiant lines of large, prominent, hex-
agonal collides with circular pores ; cel-
lules somewhat larger near the margin.

B. Amer. Journ. Science, 185G. Alive,
Sea of Kamtschatka ; fossil, Monterey.

C. in'ofunclus (E.). — Cellules of disc
subequal, near the margin smaller and
in-egidarly radiating. ERBA. 1854 ; EM.
pi. 35 B. f. 8. Atlantic.

C. raclicdus (E.). — Cellules rather
large, arranged in radiating lines (EM.
pi. 21. f. 1; SBD. pi. 3. f. 37), smaller
near the margin, (xi. 39, 40.) Common,
both recent and fossil. Diam. 1-8G0" to
1-240''. The radiating aiTangement is
sometimes obscure.

C. Sol (WaUich). — Disc as in C. o-adi-
atus, but suiTounded by a broad, hyaline,
membranous border, which is divided
into compai'tments by numerous radiating
lines. WaUich, TMS. viii. pi. 2. f. 1, 2.
From Salpa3, Bay of Bengal, and Indian
Ocean. On subjecting the frustule to
acids, the membranous ring is at first
simply detached, and after a while dis-
solved (WaUich).

0. Argus (E.). — CeUules large, some-
what smaller at the centre and margin ;
the radiating arrangement often inter-
rupted. EM. pi. 21. f. 2. Recent, Cux-
haven ; fossil, Oran and Sicily. May be
a variety of C. radiatiis, from which, how-
ever, Mr. BrightweU considers it suffi-
ciently distinct. He finds the celliUes
in that species always radiant, whilst
in the present they have no definite
ai-rangement.

C. radiolatits (E.). — Granules puncti-
fonn, equal, radiating. E. /. c. pi. 18.
f. 36. Fossil, Virginia. Differs from

C. Apollinis by the absence of an imi-
bUicus. 18 ceUules in 1-1200".

C. subtilis (E.). — Granules punctifonu,
smaU, equal, radiating. E. c. pi. 18.
f. 35. America. SimUar to C. radioJatus,
but with 24 ceUides in 1-1200".

C. Nornianni (Greg.).-^Disc yvith. ra-
diating series of faint areolaj an-anged
in fasciculi of about 0 rows each ; areolns
equal, except near the margin, where
they are smaller; rim smooth. Grev
MJ. vii. p. 81, pi. 0. f. 3. In stomach of
Ascidians. Hull. Arcoho about 24 in
•001". No distinct umbilicus. Differs
from C. snUilis by hnvin"' only half as
many lines in each fasciculus (Grev.).

C. pimclatits (E.). — Cellules piuicti-
fonn, radiating, loosely disposed at the
centre, very densely crowded at the
margin, and forming a broad, yellowish-

white border. EM. pi. 18. f. 41 ; KSA.
. 124. Virginia. Cellules at centre,

4 to 26 in 1-1200". Diam. 1-348".
Ehrenberg gives a figure of an oval
variety of this species, pi. 18. f. 40.

C. tenellus (E.). — Cellules veiy small,
equal, radiating. EB. 1854. Atlantic.
17 or 18 ceUules in 1-1200", The cha-
racters given are insufficient to distin-
guish this species from C. radiolatus and
C. suhtilis.

C. granulatus (E.). — Disc small, with
dense series of very smaU ceUules, caus-
ing a gi'amUar appearance ; gramiles 18
to 21 in 1-1152". KSA. p. 122. FossU.
Virginia. Diam. 1-552".

C. umhonatus (Greg.). — Disc densely
ceUidate, ha\'ing a broad, nearly flat
marginal zone, the central portion being
nearly or quite hemispherical ; ceUules
generally radiant, small and irregular in
outline. Diam. -0045". Lamlash Bav.
GD. p. 28, pi. 2. f. 48.

5 * CeUules not radiating ; no distinct

umbilicns or striated border.

t CeUiUes arranged in more or less
perfect concentric circles.

C. Patina (E.). — Disc lai-ge, with
moderate-sized ceUules, disposed in
concentric circles and becoming smaUer
towards the margin. KB. p. 1. f. 15.
Fossil, Greece; alive, Cuxhaven. The
^ young and ^dgorous specimens of live
indi\idual3 are completely filled yd\h
yeUow gi-aniUes, whUst tie older ones
have an in-egidar yellow granular mass
within them. Diam. 1-860" to 1-240".

C. isoporus (E.). — Disc coai-sely cel-
lular; ceUules close, aiTauged in con-
centric circles. EM. pi. 33. 17. f. 3.
Disc of moderate size. Ehrenberg"s
figm'o bears some resemblance to C. con-
camis, but has concentiic ceUules, and no
distinct rim.

C. velatus (E. ). — CeUules lai^e, nn-
gidar, rather distant, armnged somewhat
concentrically; the disc punctated, ap-
pearing as if covered vritli a veU. E. /. c.
pi. 18. f. 37. Virgmia, Diam. 1-492 ".

2 1 Cellules in pai'aHel or curved lines.

C. lineatm (E.). — Cellules sniaU, cir-
cidar, arranged in straight, pamllel lines.
KB. pi. 1. f. 10. Fossil, Sicily and Ame-
rica ; alive, CiLxhaven. Common. The
cells in this species form paraUel lines in
whatever direction tliey may be viewed.
In large and well-preserved fossU speci-
mens as many as twenty-five openings
(? spines) wore seen near the circum-

OF THE COSCINODISCE.E.

831

fcreuce. Within tlie live forms some-
times numerous yellow vesicles are seen,
as in Gallionella. Diameter of fossil
1-1150" to 1-480" ; living, 1-1150" to
1-860".

C. eccentricus (E.). — Cellules small,
disposed in excentric cuiTcd lines, KB.
pi. 1. f. 9. Common, both recent and
fossU. D. 1-860 to 1-430 '.

3t CeUules in no detenninate arrange-
ment.

C. concavus (E.). — Each valve very
concave, the two opposite conjoined,
fonning an entire, very convex body ;
cellides coarse, equal, not radiating.
EM. pi. 18. f. 38; GDC. pi. 2. f. 47.
Virginia. Cellules 4 in 1-1200". An
Afiican variety has twice as many. =
Melosira crihrosa, Sm ANH. xix. p. 11,
pi. 2. f. 15.

C. lieteroporus (E.). — Cellules hex-
agonal, smaller at the margin and centre,
intermediate ones largest, imequal. KA.
p. 123. Bei-muda deposit. D. 1-360".
This species may be recognized by the
smaller marginal and centi'al ceUides and
the very unequal intennediate ones.

C. minutus (Kiitz.). — Disc nearly
smooth, margin with punctated rays.
D. 1-1416". KB. 1. 1. f. 14. Cuxhaven.

C. minor (E.). — Margin smooth ; disc
iiTegularly and densely cellidoso-pimc-
tate. Fossil, Sicily and Virginia ; alive,
Em'ope and America. E. I. c. Not C.
minor of SBD.

C. Jiavicans (E.). — Disc small, with
very fine non-radiating cellules, yellow
by transmitted, but white by reflected
light. KSA. p. 122. Peru and St. Do-
mingo.

C. labijrinthm (Eoper). — Disc di^dded

by dotted lines into lai-ge, irregular, hex-
agonal, minutely dotted spaces ; puncta
15 in -001". Ko MJ. vi. p. 21, pi. 3. f. 2.

Pembrokeshire. This species has some-
what the aspect, under a low power, of
a finely marked specimen of C. eccen-
tricus, but difiers in the absence of a
spinous margiu, and in the large and
irregidarly shaped hexagonal spaces
without any clearly defined margin (Ro.).

Doubtful or imperfectly known Species.
C. cinctus (K.). — E,im with inter-
rupted radiating strijB; cellules of disc
crowded in the centre, the others scat-
tered, remote. KSA. p. 122. C. Patina,

B. Ajner. Jour, of Science and Arts,
1842, pi. 2. f. 13. Alive, Cuxhaven ;
fossil, Virginia. Diam. 1-324". Ehren-
berg refers the Virginian specimens to

C. minor.

C. ovalis (Ro.). — Valves oval, brown-
ish in balsam, with finely-dotted radi-
ating lines and no distinct umbilicus,
Ro MJ, vi, p. 22, pi. 3. f. 4. Pembroke-
shire. Markings very delicate and in-
conspicuous, (v. 78.)

C. punctulatus (Greg.). — Disc marked
with very fine and obscm-e lines, the
whole sm-face sparsely pimctate. Lam-
lash Bay. GD. p. 28, pi. 2. f. 46.

C. nitidus (Greg.). — Disc marked with
distant and irregularly radiant gTanides,
larger towai'ds the centre ; margin striate,
strias about IG iu '001". Lamlash Bav.
Greg. I. c. p. 27, pi. 2. f. 45. (vin. 18.)'

C. cervmus (Bri.). — Disc minutely
prmctate, pimcta scattered ; centre con-
vex. Diam. '0004" to ■008o".=IIi/nlo-
discus cervimis, Bri Jj\IS. viii. p. 95, pi. 5.
f. 9. Arctic regions.

Genus ENDICTYA (Elir.). — Fnistules disciform, simple or forming short
filaments, closely ceUuiose, in front view with a middle fm-row, having ou
each side crowded parallel series of cellules. Kiitzing places its only species in
Coscinodiscus ; but we think that it is much more nearly allied to Orthosira.

times the collides of tlic disc are almost
concentric in their arrangement, 7 in
1-1152". Diam. 1-528". This fonn is
probably identical -with Coscinodiscus
concavus and Melosira cribrosa.

Endictya oceanica (E.). — Disc with
close cellides and a dentate rim. (v. 70.)
EM. pi. 35 A. 18. f. 6, 7. = Orthosira oce-
anica, Bri JMS. viii. p. 90, pi. 6. f. 16.
Common in Peruvian guano. Some-
Genus CllASPEDODISCUS (Ehr.). — Fnistules simple, disciform; disc
cellulose, without strife or septa, but having a broad, well-defined, tumid
border of a different stnictm-e from the centre. Craapedodiscus has the habit
of Coscinodiscus, with which Kiitzing united it. It differs from Coscinodiscus
limhatus, and similar forms, by its margin, wliicli docs not form a mere riui
but a broad border of a different structiu-o, separated from tlie centre by a
distinct furrow or well-defined line.

832

SYSTEMATIC HISTORY OP THE INFtTSOBIA.

Craspedodiscus elegans (E.), — Bor-
der with obliquely quadrate cellules ;
disc witli a central rosette of live or six
obloug ones, the others being circular
and somewhat radiating, (xi. 38.) EM.

})1. 33. 18. f. 2. = Coscitiodisciis eler/ans,
iSA. p. 12G. Bermuda deposit. Frus-
tides large, with an elegantly marked
border, the diameter of which is much
less than that of the centre. This species
differs from the rest in its central rosette
and diagonally marlced border.

C. Coscinodiscus (E.). — Border broad,
but of less diameter than the centre ;
cellides of border large, close ; those of
centre minute or pimcta-like, and scat-
tered, (v. 80.) EM. pi. 35. 16. f. 8. =
Pijxidicula Coscinodiscus, EB. 1844 ; Cos-
cinodiscus Pyxidicula, KSA. p. 126 ; Br
JMS.viii.p.95,pl.5. f.4. Fossil. United
States.

C. microdiscus (E.). — Border very
broad, its diameter gxeater than that of
the centre ; cellvdes of border large, close;
those of centi-e minute, scattered. E. /. c.
pi. 33. 17. f. 4. Fossil. United States.

Resembles C. Coscinodiscioi, from wliich
it diliers in its proportionally smaller
centre.

Doubtful Species.

CP SteUa, EM. pi. 35b, b. 4. f. 11.
Ehrenberg's figm'e represents a sniootli
disc with a Melosu-a-like umbilicus, from
which radiate irregularly placed lines.

C. ? Franklini, EM. pi. 35 a. 23. f. 6.
= Hyalodisciis suhtilis.

C. marginatus (Bri.). — Disc with hya-
line mai'gin, ha-ving about 20 i-ays ; re-
mainder of the valve minutely pimctale.
Diam. -0037". Barbadoes deposit. I3r
JMS. viii. p. 95, pi. 5. f. 7.

C. seinijilanus (Bii.). — Margin very
broad, faintly radiate and pmictate. One
half of central part of the A alve smooth,
the remainder with 4 or 5 radii. Diam.
•0024" to -0035". Barbadoes deposit.
Br. I. c. p. 95, pi. 5. f. 12.

C. coronatus (Bri.). — Only fmgments
of this form have hitherto been foimd,
and consequently no satisfactory specific
character can be given. Br. I. c. p. 95. f. U.

Genus ODONTODISCUS (Ehr.).— Frastules simple, orbicular ; disc with-
out nodiile or septa, but with dotted rays and erect teeth. Odontodiscus
differs from Coscinodiscus and Aetinocyclus by ha"\Tng its disc furnished witli
teeth, of which the others are destitute. The dots are radiate, not parallel,
as in Systephania.

Odontodiscus Sinca (E.). — Teeth
submarginal, numerous (48) ; granides
in radiating series. KA. p. 129. Fossil.
Virginia. Granides 19 in 1-1152".

O. Uranus (E. ). — Disc with numerous
(32) radiating series of gi-anides and
marginal teeth. KSA. p. 129. Fossil. Vir-
ginia, O. Uranus has marginal teeth aud
fewer radiating series of granules than
O. Spica ; but we doubt whether they be
really distinct species.

0. eccentricus (E.). — Disc with its
granides aiTanged in eccentric, ciu'ved,
indistinctly radiating rows ; teeth nu-

merous, marginal, (v. 90.) EM. pi 35 a.
18. f. 11. = Coscinodiscus eccentricus, SD.
i. p. 23, pi. 3. f. 38. ? Fossil. Guano, &c.
Granules about 20 in 1-1152". 1). 1-864".
This species differs fi-om Coscinodiscus
only in having teeth, and may be merely
that state of the latter which is described
and figm-ed by Professor Smitli as spinous.
We, however, have generally faded to
detect the spines in the Coscinodiscus
eccentricus, although fhey ai'e obvious
enough in the Odontodiscus, which is
usually much smaller. On tliose accounts
we cannot decide that thev are identical.

Genus SYSTEPHANIA (Ehr.), — Frustulos orbicular ; disc cellulose,
neither radiate nor septate, with an external circlet of sjiincs or an erect
membrane on the disc, not on the margin ; cellules in parallel rows, " The
genus has the habit of Coscinodiscus Uneaius, but Avith lateral crowns, which,
in the young state, unite two uidividuals " (Bailey). Tlie spines ai"c subulate,
and appear not unlilcc the peristome of a rao.ss.

Systkptiania (iculeata (E.). — Disc
loosely cellulose ; cellules distinct, spines
erect, not crowded, few (12 lo 15), placed
on llic disc near the margin. KA. p. 126.
Bernmda. Cellules 8 in 1-1152". Diam.
1-324". This species is distinguished

by its fewer spines and more conspicuous
cellules.

S. Corona (E.). — Disc densely cellu-
lose ; spines erect, muncrous (40 to 50),
closely set, placed on the margin. EM.
pi. 33. 15, r. 22. Beiinuda, \'irginia.

OV THE COSCINODISCEiE.

833

CeUides 12 in 1-1152". Diam. 1-348".
The spines are far more numerous and the
cellules less distinct than in S. cwuleata.

S. Diaclema (E.). — Disc densely cellu-
lose ; spines numerous, marginal, in-
cm'ved, conjoined at their exti-emities

by a membrane. EM. pi. 33. 18. f. 11.
Bermuda. Cellules 14 in 1-1152". Diam.
1-864". Much smaller than the two
preceding species. All have a variable
mmiber of teeth.

Genus STMBOLOPHORA (Ehr.). — Prustules orbicular, not concatenate;
disc with striae or dotted lines, radiating from a solid angular centre. Sym-
bolophora differs from Actinocyclus in haviag an angular or stellate hyaline
centre.

Ehrenberg has placed in this genus forms which agree only in their hyaline
angular umbUicus; and the species with radiating series of dots scarcely
differ jfrom Coscinodiscus.

Symbolophoha Trinitatis (E.). — Disc
having a triangular crystalline imibilicus
with a crenated margin, from which
radiate six fascicles of very fine lines
diverging towards the margin. EB.
1844, p. 88. (xi. 36.) Fossil. Maryland.
We believe no one except Ehrenberg
has observed this species, for which the
genus was constituted ; and it has been
suggested that his figm'e may represent
what he eiToneously supposed to be the
original form (as shown by a fragment)
of Triceratium Marylandica ; but in this
opinion we cannot concur, because in
several instances where Ehrenberg has
founded species on mere fragments he
has figm-ed the fragments as he observed

them, without attempting a restoration
of theii' supposed entire figm-e.

S. acutaiigula (E.). — Resembles the
preceding in size and habit, but has the
angles of its umbilicus acute. EB. 1845,
p. 81. Fossil. Virginia.

S. ? 3Iicrotrias (E.). — Disc turgid,
with a stellate umbilicus, fi-om which
radiate series of pimcta. Antarctic Ocean.
Umbilicus triradiate = S. Blicrotrias, E.
I. c. 1844, p. 205 ; EM. pi. 35 a. 21. f. 16.
Umbilicus cruciate or fom-rayed = S.
Tetras, E. /. c. Umbilicus five-rayed = /SI
Pentas, EM. pi. 35 a. 22. f. 19. Umbilicus
six-rayed = S. Hexas, E. I. c. This species
differs from a Coscinodiscus only in the
presence of the stellate umbUicus.

-Characters unknown to us.

Genus HETEROSTEPHAMA (Ehr.).-

8 or 10 marginal teeth or minute pro-
cesses, and no umbilicus. Front view
with miuute, erect, marginal teeth.

Hetekostephania Rothit, EM. pi.
35 A. 13 B. f. 4, 5. (v. 86.) _ Elbe. Disc
with radiating series of minute puncta.

Genus HALIOISTTX (Ehr.).— Erustules orbicidar, not concatenate; disc
rayed ; number of rays definite, not starting from the umbUicus ; no internal
septa. It resembles Actinocyclus, except ia its umbilicus not being radiate ;
or, iu other words, its central ocellus is wanting. In like manner Cosciuo-
discus differs from Symbolophora in its non-radiate umbilicus, which is a
simple void space.

Halionyx senarius (E.). — Surface of
disc with six rays ; each compartment
is marked by parallel lines, which de-
crease by equal gradations on either side
of a radiating median line ; loosely and
widely cellulose ; umbilicus entire, punc-
tated. KA. p. 130. Antarctic Ocean.
Diam. 1-720". Approaches Actinoptychus
undidatiis.

H. undenarms (E.). — Disc with eleven
or twelve rays ; umbilicus large, punc-
tated, not radiant, (v. 82.) EM. pi 35 a.
21. f. 12. = ^. duodenariiis, E. olim. Ant-
arctic Ocean. Diam. 1-576". Ehrenbero-'s
figure shows the disc with a granulated
centre, from which proceed radiating
series of puncta and eleven darker or
shade-like rays.

Genus ACTINOCYCLUS (Ehr.).— Fnistules simple, disciform ; disc mi-
nutely and densely punctated or cellulose, generally divided by radiating sino-le
or double dotted lines, and having a small circular hyaline intramarginal
pseudo-nodule. We consider Actinocyclus, as limited by Ehrenberg, a wel'l-

3 u

834

SYSTEMATIC IIISTOEY OF THE INFUSORIA.

A. Ehrenbergii, but by Ehrenberg re-
garded as distinct species. Most of them
may be obtained from Icbaboe guano.
We imite them all in this species: —
A. temarius, 3 rays ; A. ^uaternarius, 4 ;
A. quinarius, 5 ; A. biternarius, 6 ; A.

no-

9 ; A. denarius, 10 ; A. undena-

septenarius, 7 ; A. octonarius, 8 ; A
nariiis.
rim, 11 ;

marked genus. Its confusion has arisen from Professor Kiitzing's retention
in it of some species of Actinoptychus, and the application of its name
by Professor Smith to the latter genus. The disc is not undulated; and
the rays, which are often very indistinct, are dotted or interrupted, not
continuous lines. Erom the minute size and close arrangement of the puncta,
the frustules, when mounted in Canada balsam, never appear hyahne, but of
a brownish or, more frequently, of a beautiful purplish colour. The disc is
furnished with an intramarginal pseudo-nodule, which simulates an orifice.
Ehrenberg in this, as in other genera of Diatomacese, distinguished his species
solely by the number of their rays ; but we cannot retain them, as we con-
sider species foimded on such characters altogether unscientific and erroneous.
In general, names once bestowed ought to be retained, even when somewhat
inappropriate or defective, because less iajury is done by their retention than
by burdening the science with synonyms ; still we beheve it far better to
bestow a new name when, as in this genus, numerous species are reduced to
one to which the original names would be inappHcable,

AcTrNOCYCLTJS moniliformis (to.. sp.). —
Disc divided into compartments by three
or more rays, formed of single series of
dots, in a moniliform arrangement. = ^1.
ter-narius, EM. pi. 22. f. 9. Eossil. Europe,
Africa, and America. This species in-
cludes most of Ehrenberg's figm-es of
Actinocycli from the deposits of Greece,
Oran, Sicily, and Virginia (pis. 18, 19, 21
& 22). We have seen no specimens ; but
in Ehrenberg's figm-es the single monili-
foim rays difier so greatly fr-om what we
find in the following species that we
must consider them distinct, although
Ehrenberg, in consequence of his regard-
ing the number of the rays as the essen-
tial character, has mixed up its forms
with tliose of the folio wing species imder
the same names.

A. Ehrenherfjii (n. sp.). — Disc gene-
rally iridescent, closely punctated, so as
under a low power to appear waved,
di'^dded by regidar equidistant rays
foiTned of interrupted double lines, which
terminate at the margin in minute teeth.
Common, both recent and fossil. Very
fine in Icbaboe guano. Under this name
we include all Ehrenberg's species
rays composed of double lines. The rim
is naiTow, but generallj^ distinct ; pseudo-
nodule minute. In fluid, A. Ehnmhernii
is colourless ; but when moimted in bal-
sam, it, like the next species, varies with
difl'erent shades of brown, green, blue,

EuiT)le, and red. The rays are formed
y lines composed of linear or subulate
hyaline spaces, which, more frequently
than in A. Rcdfsii, are in pairs, though
sometimes alternate ; they are often in-
distinct, especially in smaller specimens.
Tliis species is best recognized by the
waved appearance of its puncta.

We subjoin a list of forms included in

A. hisenarius, 12 ; A. tredena-
riiis, 13; A. hiseptenarins, 14; A. quin-
denarius, 15 ; A. bioctonariiis, 16 ; A.
septemdenarius, 17 ; A. binonarius, 18 ;
A. novemdenarius, l9 ; A. vicenarius, 20 ;
A. Luna, 21 : A. Ceres, 22 ; A. Jmw, 23 ;
A. Jupiter, 24 ; A. Mars, 25 ; A. Mer-
curius, 26 ; A. Pallas, 27 ; A. Satiirnus,
28; A. Terra, 29; A. Venus, 30; A.
Vesta, 31 ; A. Uranus, 32 ; A. Achar-
neus, 33 ; A. Aldebaran, 34 ; A. Antares,
35 ; A. Aquila, 36 ; A. Arcfurus, 37 ; A.
Bot-el-gose, 38 ; A. Canopus, 39 ; A. Ca-
pella, 40 ; A. Fom-el-hot, 41 ; A. Lyra,
42 ; A. Procyon, 43 ; A. Rcgulus, 44 ; A.
Riyl, 45 ; A. Siritts, 46 ; A. Sol, 47 ; A.
A. Spica, 48; A. StcUa pohris, 49; A.
Ninus, 60; A. Alexander, 51; A. Ptolc-
mceus, 52 ; A. Davidcs, 53 ; A. Numa,
54 ; A. Crasus, 55 ; A. Dux, 56 ; A. Rex,
57 ; A. Imperator, 58 ; A. Plutus, 59 ;
A. Proserpina, 60; A. abundans, 61; A.
luxuriosus, 62 ; A. pi-odiyus, 63 ; A. for-
tunatus, 04 ; A. locuples, 65 ; A. opiparus,
06; A. jveiiosus, 07; A. polyadis, 68;
A. magnificus, 69 ; A. Zoroaster, 70 ; A.
Solon, 7l ; A. Clcobulus, 72 ; A. Chilo,
73; A. Pitiacus, 74; A. Thales, 75; A.
Bias, 76 ; A. Periandcr, 77 ; A. Soa-ates,
78; A. Salomon, 79; A. Homcrus, 80;
A. Hcsiodus, 81; A. Tyrtmts, 82; A.
Anacreon, 83; A. Sappho, 84; A. Pin-
darus, 85 ; A. ^ichylus, 86 ; A. Sophocles,
87; A. Euripides, '88: A. Virqihus, 89;
A. fforafius, 90; A. Tvbekain, 91 ; A.

OF THE COSCINODISCEJE.

835

DcBdalus, 92 ; A. CaUimachus, 93 ; A.
Phidias, 94 ; A. Praxiteles, 95 ; A. Pi/r-
goteles, 96 ; A. ApeUes, 97 j A. Zeiixis,
98; A. Orpheus, 99; A. Apollo, 100;
A. Adamas, 101 ; A. Achates, 102 ; A.
Amethystus, 103 ; A. Astrolites, 104 ;
A. Beryllus, 105 ; A. Carbunculiis, 106 ;
A. Chrysolithus, 107 ; ^. Hyacinthus,
108 ; ^. laspis, 109 ; ^. lasponyx, 110 ;
^. Leucochrysus, 111; ^. Omphus, 112;
-<4. Onyx, 113; ^. Opalus, 114; ^. ^Sa-
phirics, 113 ; Sarda, 116 ; Sardonyx,
117; Smaragdus, 118; Topazius,
119; ^. Panheiios, 120.

A. Ralfsii (Sin.). — Disc iridescent,
with close radiating series of punctiform
gi-auules, interrupted by numerous subu-
late hyaline spaces, which are crowded
in the centre and more distant near the
margin, where they form irregular rays of
double broken lines ; marginal teeth and
pseudo-nodule as in A. Ekrenbergii. =
Eupodiscus Ralfsii, SBD. ii. p. 86. British
coast, (v. 84.) /3. sparsus (Grreg. in lit,),

franules in loose series, without angular
lanks, the principal rays alone reaching
the umbilicus, =Eupodiscus sparsus, Greg
TMS. y. p. 81, pi. 1. f. 47 : Scotland.
" The lines of cellules diminish in num-
ber at distinct intervals fi'om the margin
towards the centre of the valve, giving
a zoned appearance when seen under a
low power " (SBD.). A. Ralfsii differs
from A. Ehreniergii in the radiated ar-
rangement of its granules, the far gi-eater
mmiber of hyaline spaces, and the more
irregular distribution of the rays, in
which also the blank spaces in the asso-
ciated lines are usually alternate. The
following remarks on the var. sparsus
are condensed from Professor Gregory's
papers : — Piincipal rays eqiudistant,
lormed of large dots not closely set;
between the principal rays, the inner
ends of which leave a small central um-
bilicus, occur shorter series parallel to
each other, the middle one longest, the
others progressively decreasing in length
on each side, and the shortest adjacent
to the principal rays, which they approach
at an angle. Professor Gregoiy finds the
same arrangement in A. Ralfsii; but in
that foiin the dots are large and very
close. In A. Ralfsii the colour varies
■with different shades of pui-ple, blue,
green, and yellow, and sometimes brown
or buff. At Professor Gregory's sug-
gestion, we reduce A. quirsus to the rank
of a variety, as he finds the species to
vary much m the size of the granules, in
their closeness, and in colour.
K. fulnm (Sm.).— "Cellular structure

indistinct, radiate; colour of dry valve
taway." = Eupodiscus fulous, SBD. i.
p. 24, pi. 4. f. 40. Britain. Rays obscui-e.
We doubt whether this species be distinct
from A. Ehrenbergii, many specimens of
which have very indistinct rays.

A. crassus (Sm.). — Disc somewhat
opaque, purplish when dry ; granules in
radiating series ; pseudo-nodide as in A.
Ralfsii; margin smooth. = Eupiodiscus
crassus, SBD. i. p. 24, pi. 4. f. 41. Britain.
Ml". T. West believes this species to be
an immature state of A. Ralfsii.

Douhtfd Species.

A. Panheiios (E.). — Very large; disc
with 120 very fine rays. KSA. p. 128.
Cuxhaven. Diam. 1-180".

* Disc generally coloured, furnished with
radiating series of puncta.

A. interpunctatus (Bri.). — Disc with
an indefinite number of double rays
running fi-om the centre to near the cir-
cumference ; the rays composed of short,
broken lines; the spaces between the
rays are minutely pimctate. California,
New Zealand, West Indies. = Actino-
ptychus interpunctatus, Bri JMS. viii.
p. 94, pi. 6. f 17.

A. subtilis (Greg.). — Disc very hyaline,
with numerous very fine inconspicuous
radiating dotted lines, a circidar punc-
tated umbilicus, and rather distant mar-
ginal teeth.. = Eupodiscus subtilis, GDC.
p. 29, pi. 3. £ 50. Forming brown patches
on sides of rocks. Ilfi-acombe, Plymouth.
This species is easily distinguished by
its hyaline appeai'ance in balsam. The
pseudo-nodule is minute, radiatmg lines
indistinct, and the umbilicus is furnished
vsdth scattered dots surrounded by a
dotted circle. Frustules sometimes con-
tained in an indefinite mucous stratum.

2 * D/i/c with hexagonal cellules, which
are not in radiating lines.

A. tcssellatus (Eo.). — Cellides of disc
distinct, hexagonal, with a minute no-
dule at each angle, not radiant. = i;(/^o-
discus tessellatus, Ro JMS. vi. p. 19, pi. 3.
f 1. Pembrokeshire, IIuU, Norfolk.'
Guano. This species is placed in Acti-
nocyclus because of its solitary intramar-
ginal pseudo-nodule ; but in its structure
it differs so much from tlie other species
of that genus, that it might bo separated
from it. The reticulated disc and ab-
sence of rays distinguish it. In balsam
it is nearly colourless.

3 H 2

836

SYSTEMATIC HISTOUT OF TUT. rNFUSORIA.

Genus ASTEEOLAMPRA (Ehr.).— Frustiiles simple, disciform ; disc orbi-
eixlar, with marginal areolatcd or punctated compartments, separated by
smooth rays Avhieh proceed from a hyaline central area; central area divided
by lines, which radiate from the umbilicus to the apex of each compartment ;
compartments and rays symmetrical. Maiine. The disc in this beautiful
genus is generally colourless, and when mounted in balsam is far from con-
spicuous, notwithstanding its comparatively large size. The marginal com-
partments are usually conical, and from the apex of each a line or rib proceeds
to the umbilicus. The hyaline central area seems to originate from the dilated
inner ends of the rays, and its lines to be produced by theii- junction. Aste-
rolampra is distinguished from Asteromphalus by the compartments being
similar and equidistant ; on which account the rays are equal, the lines all
radiant, and the umbilicus central.

* Umhilical lines straight.

AsTEROLAMPBA Manjlandica (E.). —
Umbilical lines simple, straight; areo-
lated compartments conical or semicir-
cular. EB. 1844, p. 76, f. 10; Wallich,
TM. viii. p. 47, pi. 2. f. 13, 14; GrevTM.
viii. p. 108, pi. 3. f. 1-4. = A. septenaria.
Johns. SUl. Jouru. 2nd ser. xiii. p. 33 ;
A. impar, Sh TM. ii. pi. 1. f. 14 ; A. pe-
lagica, EB. 1854, p. 238. Eossil, Vir-
ginia : Monterey stone, guano. Recent,
India, &c. (xi. 33.) Rays 6 to 14. The
disc varies greatly, not only in the num-
ber of rays, but in the elongated or de-
pressed form of the compartments, pro-
ducing a coiTesponding variation in the
size of the central area.

A. Rotula (Grev.). — Resembles A.
Marylandica, but the areolated compart-
ments have subtruncate apices ; lunbUi-
cal lines straight. GrevTM. viii. p. Ill,

})1. 3. f. 5. Monterey stone. Umbilical
ines simple or dividing in a forked man-
ner, close to the central point.

A. variabiUs (Grev.). — Compartments

with cuneate apices ; imibilical lines
straight, mostly imited in tn-o.s or threes
near the centi-al point. Grev TM. viii.
p. Ill, pi. 3. f. 6-8. Monterev stone.
Rays 6 to 11.

A. Grevillii (Wallich, Grev.). — Com-
partments conical, with truncated apices ;
umbilical lines straight, variously united.
= Astm-omphalm Grevillii, Wall TM. viii.
p. 47, pi. 2. f. 15 ; Asterolampra GreviUii,
Grev TM. viii. p. 113, pi. 4. f. 21. Eossil,
Virginia and Monterey stone ; recent,
Indian Ocean. This species approaches
Asteromphalus in the appearance of the
centi-al area, but its marginal compart-
ments and alternating rays are symme-
trical. Rays niunerous, 13 to 17.

2 * Umbilical lines angularly bent.

A. Brebissoniana (Grev.). — Ai-eolated
compartments tiiuicated ; umbilical lines
with an angular bend in the middle.
Grev TM. viii. p. 114, pi. 3. f. 9. Mon-
terey stone. Umbilical lines simple or
united, close to the central point.

Genus ASTEROMPHALUS (Ehi-.).— Frustules simple, disciform ; disc as in
Asterolampra, but ^ith two of the punctated compartments approximate, and
the interposed ray narrower than the others. Maiine. Asteromphalus differs
from Asterolampra in having two compartments closer together. The Hncs
connecting these with the umbilicus do not radiate like the rest ; and the
enclosed hyaline ray consequently differs in form fi-om the others, and is
termed the median or basal raj'.

Buchii, EB. 1844, p. 200; A. HumboMtii,
E. I. c. p. 200 : EM. pi. 35 a. 21. f. 3 ; A.
Cuvicrii, EB. 1844, p. 200; EM. pi. 36 a.
21. f. 1. Antarctic Ocean, (x. Si) Rays
6 to 9. We consider that forms differing
only in the number of tlieir rays are not
really distinct, and have consequently
united Ehreuberg's species quoted above.

A. Dalhsianm (Grev.). — Areolated
compartments, Avith trimcflte apices ; me-
dian lines canipanulate. = Asterolampra

* Umbilical lines radiating from a central
point, tivo of them approximated. As-
teromphalus.

t Umbilical lines straight or ciu'ved.

Asteromphalus Hookcrii (E.). —
Punctated compartments, conical or
rounded at the apex ; umbilical lines
straight, the median ones parallel. EB.
1844, p. 200 ; EM. pi. 35 a. 21. f. 2. =A.

OF THE C0SCIN0DISCEJ5.

837

Dallasianu, Grev TM. viii. p. 115, pi. 4.
f. 10. Bermuda, Tripoli.

A. WuUichimius TGrev.). — Areolated
compartments, witn tnmcate apices ;
mnbilical lines straight. = Asterolampra
Wallichiana, Grev TM. viii. p. 115, pi. 4.
f. 11. Bermuda, Tripoli. " The umbilical
portion of each ray is so wide next the
areolated segments, that it may be com-
pared to a short-bladed trowel, while
the linear part represents the handle "
(Grev.). According to Dr. Greville's
idgure, this species difters from Astero-
lampra only bj' its median ray being
narrower than the rest.

2 1 Umbilical lines with an angular
bend.

A. Beaumontii (E.). — Compartments
with roiuided apices ; imibifical lines
with an angular bend ; median ones
straight, parallel. EB. 1844, p. 200, f. 5 ;
Grev TINL viii. p. 115. Antarctic Ocean.

A. Dartcinii (E.). — Compartments
with rounded or subtruncate apices ;
imibnical lines with an angular bend;
median ones bent or cm-ved. ERBA.
1844, p. 200, f. 1.= Asterolampra Dar-
tcinii, Grrev TM. viii. p. 116, pi. 4. f. 12,
13 ; Asteromphalus Rossii, ERBA. p. 200,
f. 2; EM. pi. 35 a. 21. f. 4. Antarctic
Ocean, Monterey stone, (v. 86.)

2* Disc suhcircular, rays unequal; um-
bilical lines radiating from tJie top and
sides of the median ones, which lattei'
puss beyond and enclose the central
point. Spatangidium.

t Umbilical lines not bent.

A.. Jlabellatus (Br4b., Grev.). — Punc-
tated compartments, conic ; umbilical
lines sti-aight or slightly cui-ved, radi-
ating from apex and sides of the median
cues. GrevMJ. vii. p. 160, pi. 7. f. 4, 5.=
Spatangidium Jlabellatum, BriSb.Bull. Soc.
Ijinn. de Nonnand. iii. pi. 3. f . 3 ; Aste-
rolampraJlabellata, GrevTM. viii. p. 116 ;
Spatangidium peltatum, Breb. I. c. pi. 3.
f. 4. Peruvian and Californian guanos.
Rays 10 or 11 ; median one clavate ;
areolation of compartments very minute.

A. Ililtonianus (Grev.). — Punctated
compartmente narroAvly conic ; umbilical
lines radiating from apex and sides of
median lines, the two lower pair sud-
denly deflexed. =^s<e/-o/ow/}/Y{ Ililtoni-
ana, GrevTM. viii. p. 117, pi. 4. f. 15.
Algoa Bay guano, Indian Ocean. Rays
10 to 19, slender; umbilical lines simple
or forked ; areolation very minute. It is

a very transpai'ent species, and easily
overloolced, Grev.

A. Arachne (Brdb.). — Disc broadly
ovate ; hyaline area small and excentri-
cal; areolated compartments, very un-
equal ; umbilical lines straight, short ;
dilated head of median ray truncate. =
Spatangidium Arachne, Breb. Bull. Soc.
Linn, de Nonnand. iii. pi. 3. f. 1 ; Aste-
rolampra Arachne, Grev TM. viii. p. 123 ;
Asteromphalus malletis, Wall TM. viii.
p. 47, pi. 2. f. 11 ; JExcentron cancroides.
Rails in lit. (v. 66.) Peruvian guano,
Indian Ocean. Distinguished by its mal-
leiform median ray. Compartments with
large areolation ; umbilical lines less con-
spicuous than in the other species. Rays
usually 5, sometimes 7 ; median and
adjacent ones straight, the anterior pair
cm-ved. When there are only five rays,
this species differs greatly in appearance
from the rest by ha'vdng the anterior
mai'gin of the head of the median ray in
direct contact with the anterior com-
partment; but when the rays are 7 in
nimiber, the hyaline dilated portions of
the anterior pair intei-pose between these
pai'ts, as in the other species.

2 1 Umbilical lines with an angular
bend.

A. elegans (Grev.). — Punctated com-
partments, conic, more than half the
radius ; umbilical lines with an angular
bend, radiating fi-om apex and sides of
the median ones, usually simple, but
sometimes two or three united. Grev
MJ. vii. p. 7, pi. 7. f. 6. = Asterolampra
elegans, M.J. viii. p. 118, pi. 4. f. 16. Ca-
lifornian guano, Indian Ocean, (v. 87.)
Areolation exti-emely minute ; rays 13 to
29, gracefully slender.

A. imbricatus (Wall.). — Areolated
compartments, conic, less than half the
radius; rays numerous, robust; angular
bends of umbilical lines forming unitedly
an oblong-elliptical figm-e. Wall TM'.
viii. p. 46, pi. 2. f. 9. = Asterolampra tm-
bricata, Grev MJ. viii. p. 119, pi. 4. f. 17.
Indian Ocean, Natal. Areolation con-
siderably larger tlian in A. ekgans, its
nearest ally, Grev.

A. Brodkei (Bail.).— Disc almost cir-
cular ; areolation conspicuous ; compart-
nients truncated ; angular bend of um-
bilical lines near the outer end ; umbilical
portion of median ray constricted be-
neath the rounded inner end, then dilated.
Bail. Sill. Journ. 2ser. xxii. p. 2, pi. 1. f. l!
= Asterolampra Brookri, Grev MJ. viii
p. 110, pi. 4. f. 18. Soundings, Kanit-
schalka, Atlantic, (v. 70.) Tlie imibi-

838

SYSTEMATIC HISTOHY OF THE rNFUSOEIA.

lical lines radiate from the upper half
of the median ones, and are sometimes
divided. The angular bend is nearer the
outer end than in any other species ; and
at each angle is a minute spine-like pro-
cess, Grev.

_A. Roper ianus (Grev.). — Disc circular,
with its hj'aline area centrical ; areolated
compaa'tments, truncate, almost equal ;
umbilical liaes radiant from rounded
end of median ones ; median lines pass-
ing roimd the central point in a semi-
circle, then conti-acted, and lastly widely
expanded. = Asterolampra Roperiana,
Grev M J. viii. p. 120, pi. 4. f 14. Indian
Ocean. Rays 7, robust ; areolation rather
large, Grev.

A. SJiadboltianus (Grev.). — Areolated
compartments, truncate ; umbilical lines
radiant fi'om the pyriform median ones,
with the bend about the middle ; rays
not reaching the margin. =^s<ero/«wj;jra
Shadboltiana, Grev MJ. viii. p. 121, pi. 4.
f. 19. Indian Ocean. " Rays 7, robust ;
areolation rather large. Its nearest ally
is perhaps A. Brookei, from which it is
separated by the very different median
lines and by the angidar bend being
more in their middle" (Grev.). Dr.
Greville suspects that in this species, as
in A. Roperianus, A. Jieptactis, and A.
Arachne, the number of rays may be
more constant than is generally the case
in the group.

A. heptactis (Breb.). — Areolated com-
partments, trimcate ; rays broad, linear,
terminating in a lunate marginal fold,
and bordered by a row of larger areolae.
= Spatan(/idium heptactis, Br^b. BuU. Soc.
Linn, de Normand. iii. p. 3. f. 2 ; Aste-
rolampra heptactis, Grev TM. viii. p. 122 ;
SpatangidiumRalfsianum, TM. vii. p. 161,
pi. 7. f. 7, 8. Peruvian and Californian
guanos, Atlantic soundings. Rays 7,
straight or slightty ciu-ved, the median
one in a broad shallow gi'oove, the linear
portion faintly prolonged through the
dUated portion to spurs from the bends
of the adjacent lunoilical lines. Areo-
lation of compartments, conspicuous ;
disc subcircular. (vm. 21.)

Doubtful or imperfectly described
Species.

A. ccntraster ("Johnston). — Disc orbi-
cular ; areolated compartments with

roimded apices and bordered by a series
of larger areolae ; umbilical lines straight,
radiating from top and sides of median
ones ; rays teiminating at the margin in
nodules. Johnston, MJ. viii. p. 12, pi. 1,
f 10. Elide guano, (vm. 14.) Rays
11. Dr. J ohnston's figure diii'ers from
every known species by having the ravs
continued, as Dr. Greville remarks, like
distinct bars or the ribs of an umbrella,
from the central point to the margin.
We believe, however, that this structure
is similar to what is met with in several
other species of Asterolampra and As-
teromphalus (see especially GreviHe's
figures of Asterolampra variabilis, A.
Wallichiana, A. Roperiana, and A. hep-
tactis), but more strongly mai-ked, and
probably exaggerated in the figure.

A. stellatits (Grev.). = Asterolampra
stellata, Grev TM. viii. p. 124, pi. 4. i. 20.
Indian Ocean. It is allied to A. Hilto-
nianm and A. flabeJlatus. The lowest
pair of lunbUical lines are curved down-
wards, as in the former species. The
median lines are parallel. The valve,
at a first glance, is most conspicuous fur
the large size of the hyaline area and the
rapidly attenuated rays ; but this may
prove to be a worthless distinction.

A. Sarcophagus (Wall.). — Valve ob-
long, with inflated middle ; median ray
plane and continuous with the anterior
ray ; umbilical lines straight ; areolation
very lai-ge. WaUich, TM. viii. p. 47, pi. 2.
f. 12.= Asterolampra Sarcophagus, Grev
TM. viii. p. 124. Indian Ocean. " The
broadest portion of this species is always
towai'ds the extremity opposite to the
median ray, thus giving the valve a some-
whatpyi'iformor sai'cophagus-like shape''
(Wallich). " The foi-m of the valve is
so exti-eme a deviation from the other-
wise more or less orbicular shape of the
entire series, that an impression almost
forces itself upon the mind tliat it is
simply a malformation. It is most nearly
related to A. Arachne ; for if we remove
the tenninal rav (which in many species
may be either aljsent or pi*esent), the five
remaining rays would occupy the relative
position which they hold in that species,
as well as in the same direction, one pnir
pointing upwards, the other pair down-
wards. In both species the ai-eolation is
lar-ge" (Grev.).

Gcmis ASTEEODISCUS (Johnson). — Frustulcs sijnplc, disciform; disc
divided into punctated compartments, winch do not reach the centre, by Iiyalino
smooth rays ; compartments connected to the umbilicus by an equal number
of radiating lines, two united half way, the rest distinct. Fossil. (Johnson,

OF THE COSClNOBXSCEiE .

839

in Silliman's Amer. Joum. 1852.) " The proximate genera, Asterolampra
and Asteromphdus, ai-e readily distinguished. In the former, all the connect-
ing lines are symmetrical; in the latter, two are parallel;" whilst in this
genus one Hne divides half-way from the centre and proceeds to two of the
compartments, the smooth ray between which is smaller than the others, but
not parallel as in Asteromphalus.

AsTERODiscus Johnsonii. — Kays and A. nonarius. — Marginal rays and um-

umbilical divisions from five to nine, bilical divisions nine.

Bermuda earth. This includes the fol- " Front view bi-convex ; compart-

lowing species of .Johnson : — ments elegantly marked with minute

A. quinarius. — Marginal rays and um- dots, an-anged in excentric cmwes "

bilical divisions five. (Johnson).

A. settarius. — Marginal rays and um-
bilical divisions six.

Genus ACTIKOPTYCHUS (Ehr.).— Frustules disciform, cellulose; disc
divided into equal triangular compartments by lines or internal septa (E.).
= Actinocyclus, Smith, not Ehr. The circular disc is cellulose, and divided
into triangular portions by LLues (" internal septa," E.) radiating from its
centre. The alternate portions are usually more distinct, owing to the undu-
lated form of the frustules, which causes them alternately to be nearer to or
more remote from the eye. The apparent septa distinguish it from Actino-
cyclus, and the absence of spines from Heliopelta and Omphalopelta. We
have not the slightest doubt that Ehrenberg has properly separated Actiuo-
cyclus from Actiuoptychus. Professor Smith himself practically admits this,
by placing the groups in different genera, although he has not retained the
names as affixed by their author. If, however, the validity of their separa-
tion be admitted, the founder of these genera has surely an undoubted right
to retain the original name for whichever group he thinlts fit. Professor
Smith seems to have erred by choosing as the type of Actiuocyclus, not one
of Ehrenberg's species, but a form placed in that genus by Professor Kiitzing,
though really belonging to Actiuoptychus.

AcTiNOPTYCHUS tevnarius (E.). —
Disc with 3 or 5 radiating lines, with-
out a distinct umbilicus ; compartments
even. KE. pi. 1. f 19. =A. quinarius, E.
Fossil. Virginia. The rays proceed
directly to its centre, without leaving an
umbilical space.

A. undulutus (liiitz.). — Disc with its
compartments alternately prominent and
cellulose and depressed and punctate;
umbilicus indistmct or indefinite. =
Actiuocyclus undulutus, KB. pi. 1. f. 24 ;
Actinoptychus bitcrnarius, EM. pi. 18.
f. 20 ; A. biternatus, EM. pi. 35 a. 10. f. 1.
(v. 88.) America. Guano, &c. Com-
partments six or more.

A. velatus (E.). — Compartments six,
loosely cellulose ; surface apparently
covered by a thin punctated membrane.
KSA. p. 1.30. Virginia. Wo are luiac-
quainted with tliis species, but think it
may probably be a state of A. uudidatus,
the valves of which frequently consist
of two dissimilar plates, one having the
usual character, the other being triradiate

and minutely pimctate, and which has
been described as a new species by Mr.
Roper in TM. vi. p. 23 {Actinocyclus tri-
radiatm), who first observed it detached
from the true valve. He and others
have since foimd the plates in situ.

A. senarius (E.). — Compartments (6
or more) alternately prominent, all
loosely cellulose ; umbilicus angular,
definite ; rim striated. EM. various
plates. = Actinocyclus undulatus, SB. i.
pi. 5. f. 43. (ix'. 132.) Common, both
recent and fossil. ]\lr. Tuiren West re-
gards A., senarius and Onijihalopelta areo-
lata ns identical. The presence of mar-
ginal spines in the latter seems indeed
the only essential distinction ; and we
have generally succeeded in detecting
spines, more or loss distinct, exactly
such as Professor Smith has represented
in one of the figures of his Actinocyclus
tindulntus. The determination of species
in Actiuoptychus is very difficult. Tho
number of the compartments, gonerallv
relied upon, we consider imesseutial, anS

840

SYSTEMATIC HISTOfiY OF THE INFU80UIA,,

we would separate, into two species all
tliose forms in which the compartments,
iri'espective of their number, are di-
stinctly cellulose without any particular
arrangement of their cellules. A. unclu-
latus would thus include all those having
a Vague or indefinite umbilicus, and A.
senarius those in which the umbilicus is
separated from the cellulose compart-
ments by a well-defined margin.

A. splendens (Shadbolt). — Compart-
ments (12 to 20) obscm-ely ceUidose,
each with a median line, which termi-
nates in a clavate intramarginal nodule
or tooth ; imibilicus hyaline, definite. =
Actmophcsma splendetls, Sh TM. ii. p. 16 ;
Acti7ioptychus sedenarius, E., E,o TM. ii,

t). 74, pi. 6. £ 2. Common. Guano, Eng-
and. In this species the alternate de-
pressions of the compartments ai'e often
very slight ; and the compartments being
striated, fi-equently appear irregidar, and
are coimted with difiicultj'. The species
nevertheless has so peculiar an aspect,
that, once lmo^vn, it is easily recognized.
The rays are most distinct where they
radiate fi-om the hyaline umbilicus, at
which part they sometimes appear thick-
ened. In some specimens the nodides
are confined to the alternate compart-
ments.

A. elegans (n. sp.). — Disk divided into
compartments by lines radiating from a
stellate, hyaline umbilicus ; compart-
ments pimctated, and each bisected by
a monihform row of gi'anules. =A. octo-
denarius, EM. pi. 21> f 21. Gran. Ehren-
berg has figiu'ed more than one form as
his A. octodenarius ; the compartments in
his figTire of this species are 9, and each
is bisected by a monilifonn ray.

A. trilingidatiis(Bn.). — Valves divided
by 6 altematelj^ elevated segments. I'he
elevated portions gi-adually I'ise from the
circumference to near the centi'e, where
they are rounded off; each alternate one
has a submarginal row of dots or tnm-
cated processes. Sm-face delicately punc-
tato-sti-iate. -0035" to '0073". West
Indies. Bri M.T. viii. p. 93, pi. 5. f. 2.

A. spinosm (Bri.). — Valves with 6 seg-
ments, alternately slightly elevated; mai'-

gin occasionally spinous ; each segment
with 1 or 2 processes ; mnbilicus smooth,
surface of the valve punctate. Monterey
earth (or deposit). Bri MJ. viii. p. 94,
pl.G. f.l5. ^

A. dives (E.). — Disc divided into
numerous (about 50) naiTow compart-
ments by lines radiating from a large,
indefinite, punctated umbilicus, each
compartment having a single series of
granules. EM. pi. 19. f. 12. =Discaplea
dives, E. ; Cyclotella dives, KA. p. 20.
Fossil. Mgina,.

Doubtful Species.

A. qiiaternarius (E.). — Disc di^dded
into 4 compartments ay as many radi-
ating lines. KIA. p. 130. Vii-ginia.
Diam. 1-552". A state of A. ternarius ?

A. ? hexajyterm (E.). — Disc with 6,
thick, solid and conical rays ; margin
thick, imdidated, denticulate internally.
KA.p.l31. Fossil. Vera Cruz. (xi. 31.)
A very doubtfid Diatom.

A. octmaritts (E.). — Disc divided into
8" compartments by as many radiating
lines. Guano, &c. A state of A. senarius.

A. denarius (E.). — Disc with 10 com-
pai-tments and 10 radiating lines. EM.
pi. 18. f. 23. Cuxhaven and Virginia.
We believe this species is founded on
certain forms of A. senarius and A.
splendens.

A. duodenarius (E.). — Disc divided by
radiating lines into 12 compai-tments,
which are alternately darker; in the
centi'e of each compartment runs a nar-
row line, teiTuiuating at the margin in a
minute pseudo-nodide, so that as many
as 24 rays may be coimted. Keceut and
Fossil. Em-ope, America. KA. p. 131.
= Seliopelta Phaethon, MJ. viii. p. 13 ?
A state of A. splendens ?

The following species of Ehrenbei^
are distinguished by the nmnber of rays
only :—

A. quatuordenarius, 14 rays =^4. sjilen-
detis ; A. viccnarius, 20 rays ; A. Ceres,
22 rays ; A. Jupiter, 24 rnvs (xi. 28).
The three last are probably states of
A. qyhndens.

Genus HELIOPELTA (Ehr.). — Frustules disciform, undulated disc cellu-
lose, -with external rays and internal septa, a striated margin, many erect
submarginal teeth, and an angular centre. As in Actinoptychus, the fi-ustule
is undulated, and the disc divided into cuneate compartments or rays, which
appear alternately more distinct ; " but, in addition, they have near the
margin a row of lateral sjjines, soraewliat like the processes of Eupodiscus,
but far more numerous, wliich proliably connect tlie frustules together in the

OF THE COSCINODISCEiE.

841

young state. Ehrenberg has dedicated the diflferent species of this genus to
persons distinguished in the history of microscopic research " (Bailey). As
the species differ only in the number of compartments, they are probably not
truly distinct.

Heliopelta J!fe<(V (E.). — Disc having
loosely cellulose, elevated, radiating com-
pai'tnients, alternating with depressed
ones marked with line decussating lines ;
border a rather broad striated rim. Ber-
muda deposit, (xi. 35.) Compartments
6; umbilicus stellate. Diam. 1-372".
Has the habit of Actinoptychus velatus.
= H. Metii, EB. 1844, p. 268. Com-
pai'tments 8 ; imibilical star teti-agonal.
Diam. 1-204".

H. Leeuwenhoekiii^M.. pi. 33. 18. f. 5.).
— Compartments 10 ; mnbilical star pen-

tagonal. Diam. 1-156".

H. Euleri (EM. pi. 33. 18. f. QX —
Compartments 12; umbilical star hex-
agonal. Diam. 1-156".

H. Selliqum-ii (EB. 1844, p. 268.). —
There are usually 3 teeth opposite each
elevated compartment, and 2 opposite
each depressed one ; but sometimes, es-
pecially m the larger specimens, the teeth
are more mmierous, whilst in the smaller
ones they ai-e occasionally 1 less in each
compartment.

Genus OMPHALOPELTA (Ehr.).— Erastules simple, disciform ; disc ceUu-
lose or punctate, divided by imperfect septa into cuneate rays ; centre hyaline ;
spines, one to each compartment. " This genus has the habit of Actinoptychus
and Heliopelta, but differs from the former in the presence of lateral spiues,
and from the latter iu the small number of these processes. The species of
these thi-ee genera often closely agree in theii- form as well as in the number
of their radii and cells ; but the character of the spines will always distinguish
them" (Bailey). " All the species of Omphalopelta resemble Actynoptyclius
senarhis" (Kg.).

Heliopelta differs from this genus in having two or more spines instead of
one to each compartment,— a difference we regard as more suitable for specific
than generic distiuction ; and we believe that a better knowledge of these
forms will prove the propriety of uniting them.

Omphalopelta cellulosa (E.). — Ra-
diating compartments 6, cellulose, al-
ternately timiid and depresed, stellato-
punctate; rays but slightly prominent;
rim broad, striated. KA. p. 183. Fossil.
Bei-muda, Virginia. Diam. 1-192". This
species greatly resembles the 6-rayed
foiTu of Heliopelta Metii, in which the
compartments have sometimes only 1

and 2 spines alternately ; and indeed we
are not certain that they are even speci-
fically distinct.

0. areolata (E.). — Compartments 6,
aU loosely and obscurely cellulose,
scarcely or but slightly depressed; rays
distinct; rim broad, radiate. EM. pi. .35 a.

18. f. 12. = Actinocyclus areolattis, Bri MJ.
viii. p. 93, pi. 5. l 1. Fossil. Bermuda,
guano, (vm. 15.)

0. versicolor (E.). — Compartments 6,
a,Il granulated in very fine decussating
lines, which cause a play of colours from
tawny to red ; the strong rays and hex-
agonal crystalline umbilicus very conspi-
cuous ; i-im naiTow, radiant. KA. p. 133.
FossU. Bermuda. Diam. sometimes
1-252", but mostly less.

0. punctata (E.). — Radiating compart-
ments 0, aU loosely punctated, 3 alter-
nate ones slightly elevated ; rim naiTow,
not distinctly radiant; spiues obsolete.
K/V, p. 133. Fossil. Bermuda.

Genus ARACHNOIDISCUS (Deane). — Finistules disciform ; disc \vith a
central hyaline nodule or umbilicus, and numerous radiating linos connected
by concentric lines or series of gemmaccous granules. =Hemiptychus (E.).
The disc has been compared to a spider's web ; hence the name. Alternating
with the long radiate fines are one to three short marginal ones, the central
one of these being also longer than the other two when tkrec are present.
Professor Bailoy informs us that Aracluioidiscus has been adopted instead of
Hemiptychus because the latter name liad previou.sIy been used in ento-
mology.

842

SYSTEMATIC .HISTOEY OF THE INFUSOllIA.

AnACHNOroiscus ornatus (E.). — Disc
having its radiating lines connected hy
concentric ones. = Hemiptychus ornatus,
EB. 1848, p. 7 ; Arachnoidiscus ornatus,
EB. 1849, p. 64 ; Ar TM. vi. p. 16 ;
A. Japonicus, Shadbolt; A. Nicoharicus,
EM. pi. 36. f. 35 (according to Arnott).
Africa, West Coast of America, Nicobar
Islands, (xv. 18-21.) In deference to the
opinion of Prof. Arnott, we have imited
A, Nicoharicus to this species ; but it is
desirable to examine specimens from the
original stations. Ehrenberg describes
all the radiating lines in his A. ornatus as
eq[ual ; but he figm-es A. Nicobancus with
two sets of shorter, marginal, interme-
diate ones. Om" specimens, in this re-
spect, agTee with A. Nicoharicus, but
have aroimd the umbilicus a circlet of
close, short, radiant, oblong lines, which
are wanting in Elu-enberg's figure. The
gramdes, too, are apparently larger in
our specimens. The lines connecting the
radiating ones often anastomose.

A. JEhrenhergii (Bailey). — Disc with
numerous, moniliform, concentric circles
of large pearly gramdes, the circle next
the umbilicus formed of short lines 5
radiating lines with two series of shorter
ones between. Ehrenherqii, EB.1849,
p. 64 ; SD. i. p. 26, pi. 31. f. 256. Recent,
Coast of Oregon and California; fossil,
Monterey and California. A. Ehren-
berffii is easily distinguished from A.

ornatus by the absence of concentric
lines. It is more hyaline, and the gra-
nules far larger and more conspicuous.
All the circles are compact, and, except
the two inner ones, have the gi-anules
slightly quadrate, and their relative di-
stances somewhat irregular. The second-
ary rays are sometimes half the length
of the principal ones ; the third series is
simply marginal.

A. Indicus, EM. pi. 36. f 34. India.
We have seen neither specimen nor de-
scription of this species. Ehrenberg's
figm-e represents the disc with numerous,
concentric, moniliform circles of pearly
granules. The gTanules are distant in
the first and third from the umbilical
space ; in all the others they are dense.
Professor Ai-nott (perhaps rightly) unites
A. Indicus to A. Elirenhergii; but we
have thought proper to keep them sepa-
rate for the present, in order to direct
more attention to them, because Ehren-
berg's figm-e of A. Indicus differs in some
respects from A. Ehrenhergii. In this
species there is no liaear series round
the umbilicus, the third circle has distant
granules, all the gramdes are orbicular,
there is only one series of shorter rays
intei-posed between the long ones, and
these are connected by an undulated
line, giving the inner margin of the rim
a scolloped appearance. In all these
respects it difiers from A. Ekrenbergii.

Genus PERITHTRA (Ehr.). — Characters imkiiowii to us. According to
Ehrenberg's figures, it seems to differ from Heterostephania by its larger
tubercles.

rather broad, smooth rim, and no umbi-
licus. (-VTII. 19.)

Pebithyha denaria, EM. pi. 35 a. 9.
f. 5. = Coscinodiscus radiatiis, var., Wal-
Uch, TMS. viii. pi. 2. f. 22 ? Ganges.
Disc with radiating series of minute
puncta, ten intramarginal tubercles, a

P. quaternaria, EM. pi. 35 a. 9. f. 6.
Ganges. A variety of the preceding,
with only foui- tubercles.

FAMILY IX.— EUPODISCEiE.

Frustules simple, free, discifoi-m ; lateral surfaces furnished witli processes.
The Eupodiscca3 may be regarded as connecting the Coscinodiscea) Avith the
Biddulphiece. They agree with the former in their discoid frustules and with
the latter iu having processes on the lateral sm-faces. These processes, how-
ever, must not be confounded M^th the spines or teeth wliich occur in some
of the Coscinodisccoe. It is sometimes diiRcult to decide whether the discs
really have processes or only pseudo-nodules, since, from their circular out-
lino and hyaline texture, free from celhdes, both these appear like oiifices
unless seen in profile, and perhaps Actinocyclus would be more correctly
placed in this famUy than with the Coscinodisceoe.

Genus EUPODISCUS (Ehr.).— rnistidcs discifonn ; disc eclhilose or gra-
nulate, funii.shed witli siibmarginal circular prominences. =Tripodiscus. Tctra-

OF THE EUPODISCEiE.

843

podiscus, Pentapodisciis (E.), Podiscus (BaU.). The ceUular structure is
usually less evident in this genus than in Coscinodiscus. We have removed
to Actinocyclus thi'eo species originally placed here by Professor Smith, who
himself admits that they probably belong to that genus, " as the process in all
is rather a pseudo-nodule than a projection from the surface of the valve,"

E. Rogm-sii (Bail., E.^. — "Fi-ustules
large, liaving 3 to 7 hyaline lateral pro-
cesses placed on an elevated circle,
within which the disc is slightly con-

EuPODisCTJS Ai-gus (E.). — Disc with
three or more processes, subremote from
the margin ; cellules somewhat stellate,
intervals pimctated. SD. i. p. 24, pi. 4.
f. 39. = E. Americanus, EB. 1844 ; E.
quaternarius, E. quinarius, E. Gei-ma-
nicus, KA. p. 134. (vi. 2 : xi. 41, 42.)
Recent in marine and brackish water,
Europe, America ; fossil. United States.
This species is easily recognized by its
irregular cellules and intei-vening pimcta,
which give to the disc a clouded appeai--
ance, very unlike the lasual transparency
of DiatomacefB. The processes vary from
3 to 5 in niunber. "The star-shaped
cells appear when seen by duect light
to be placed in the centre of small bosses
or protuberances, in which respect it dif-
fers from aU other Diatomacese that I
am acquainted with. E.o MJ. ii. p. 73.

E. monstruosus (E.). — Disc with 4 pro-
cesses on one side. E. /. c. p. 81. Baltic.
Distinguished by the unsymmetrical dis-
position of its processes. It is probably
an accidental variety of E. Argus.

cave, and outside of which the sm-face
is part of the fi'ustiun of a cone. = Po-
discus Rogersil, BAJ. xlvi. pi. 3. f 1, 2 ;
Eupodiscus Rogersii, E. I. c. ; E. Bailey ii,
E. I. c. Recent and fossil. United
States. In this species the processes
are close to the rim. Tlie whole surface
is beautifully pimctate. ... As this spe-
cies is the lai'gest and most beautiful of
the fossil Infusoria occurring in the strata
of which Professor W. B. Rogers made
the discovery, I have selected it as pe-
culiarly appropriate to bear his name "
(Ban. I. c).

E. rad'taizM (Bail.). — Disc plane, areo-
lation hexagonal, with 4 (or more) sub-
marginal processes. " Resembles Cosci-
nodiscus radiatus in size and reticulation,"
BC. Bri MJ. viii. p. 95, pi, 5. f. 10,
America,

Genus AULACODISCUS (Ehr,). — Frustides disciform ; disc granulated, and
furnished with intramarginal, shortly tubular processes, each connected with
the centre by a distinct furrow, or by a radiant series of more conspicuous
granules, Aulacodisci are Eupodisci furnished with bands radiating from the
centre and connected with the tubercles situated just within the margin, and
having the surface of their valves granulate, and not ceUular. Professor
Kiitzing makes this genus a section of Eupodiscus.

* Disc huUate beneath the processes,

AnLACODiscus Petersii (E.). — Disc
nearly colom-less, having a small, per-
foration-like umbilicus, a large kite-
shaped inflation, rough with minute
points, beneath each process, and minute
granules aiTan^ed in lines. EB. 1845,
p. 361. = Etpodiscus Petersii, KSA. p. 135 ;
E. cruciger, Sh TM. ii. pi. 1. f. 12. South
Africa, both recent and in guano ; Aus-
tralia and New Zealand. Disc large,
with 3 to 5 orbicular processes, funiishcd
with a central nipple and situated on
the outer margin of the inflations. The
granules are minute, and arranged in
lines, some radiant and bisecting the
intervals between the processes, the rest
oblique and decussating. Raised points
are present on the inflations and less
conspicuously along the connecting fur-

rows and about the imibilicus; margin
finely sti-iated. In order to observe the
disc properly, it is necessai-y, on accomrt
of its xmevenness, to vai-y the focus.
Specimens from New Zealand have the
granules and markings more distinct,
and the inflations smaller, less definite,
and fm-ther from the margin.

A./orMiosi<s(iVi'nott,MS.). — Disc lurid,
having an irregular peiforation-like um-
bilicus, a large cuneate inflation beneath
each process, and radiating series of con-
spicuous poai'ly granules. = A. Bright-
wellii, Ralfs, MS. ; A. Bolivicnsis, Br6b.
MS. In upper Peruvian or San Filipe
guano. A. formosus agrees with A.
Petersii in having an inflation bencatli
each process, but difl'er.s in most other
respects. From A. margariiaceus and
A. Comberi, wliich it more nearly r(!-
sembles in the nppeai-ance and arrange-

844

SYSTEMATIC DISTOKY

OF THE INFUSORIA.

ment of its granules, it is easily known
by its inflations. Disc large, smoke- or
lead-coloured, with a narrow, distinct,
finely striated rim; inflations remote
from the margin, and having a bright
oint at the outer edge, placed at the
ase of an elongated, clavate, not very
conspicuous process.

2 * Disc not bullate beneath the processes.

A. seabed- (Ralfs, n. sp.). — Disc with
oblong submarginal processes, crowded
radiating series of mmute granules, and
scattered raised points. Peruvian guano.
Processes 3 to 5, connected by indistinct

frooves with the ver^' minute umbilicus.
Q the front view this species resembles
a Cerataulus, its lateral portions being
turgid, and, in addition to the processes,
rough with minute apiculi; connecting
zone marked by faint longitudinal lines.

A. Kittoni (Arnott, MS.). — Disc hya-
line, with 3 to 8 submarginal crescent-
looking processes, connected by radiant
rows of minute granules, with an umbi-
lical rosette of oblong cellules. Recent,
New Zealand and Monterey Baj' ; fossil,
Montere^y stone. An elegant species,
distinguished by its somewhat mammi-
form processes, which, being directed out-
wards, appear lunate. Granules pmicti-
form, proceeding from umbilicus to
processes in pencil-like rays ; intei-val
between the processes bisected by similar
pencils, but less conspicuous, and with-
out furrows ; the rest of the granules in
oblique lines, as in A. Petersii.

A. t7c»/«wsowM(Amott,MS.). — Disc pale,
with a circulai", perforation-like umbili-
cus, and crowded radiating series of gra-
nules becoming more numerous as they
proceed outwards, so as to appear forked ;
processes within the margin, roundish,
small. Algoa Bay guano. The rays,
near the margin, become more numerous,
with smaller granules, so as to look like
strisB; sometimes the processes appear
within a faint circle. A. Johnsonii some-
what resembles A. Kittoni, but is less
hyaline, with more conspicuous gra-
nides, and processes more distant from
the margin.

A. Crux (E.). — Disc with close, radi-
ating, forked series of large pearly gra-
nules, which are crowded at the centre,
leaving no blank space ; processes some-
what distant from the margin. = Crux,
EB. 1844, p. 7G ; EM. t. 18. f. 47 ; Eu-
podiscus Crux, KA. p. 135. Fossil. Vir-
ginia. We are indebted to Professor
Arnott for correcting the en'or we had
fallen into, of confounding it witli A.

Kittoni. In general appearance it agrees
with A. Comberi and A. niurgaritaceus ;
but the processes are more remote from
the margin, and the connecting fuiTows
obscure ; it differs essentially from most
other species in having large gi-anules
at the centre of its disc, instead of a
blank space ; margin striated.

A. murgaritaceus (llaLfs, n. sp.). — Disc
pale, with oblong submarginal processes,
an irregular, perforation-like umbilicus,
numerous, close, monilifonu, radiating
series of large, pearly granules, and in-
conspicuous connecting fuiTows. Patos
or Californian guano. = A. Crux, EM.
pi. 35 A. 16. £ 2. Disc large, with from
3 to 10 rather small processes ; umbilicus
usually irregular, hyaline, looking as if
denuded of granules, sometimes very
minute and suiToimded by a circlet of
larger grauides. Two simple series of
equal granules lead to each process, be-
neath which, by a slight sepai-ation, they
leave a triangular hyaline space ; the
other series are dichotomously divided,
and near the margin theh' granules be-
come smaller, or even pimctiform, and
resemble strioB.

A. Co??i6erj (Ai'nott, MS.). — Discliu-id ;
granules large, UTegulai-ty scattered roimd
the UTegular peii'oration-like umbilicus,
the rest arranged in crowded, forked,
radiating lines; processes oblong, sub-
marginaJ, Avith conspicuous connecting
furrows. San Filipe guano. Processes
2 to 6. A. Comberi in character ap-
proaches closely to A. inargaritaceiis ; its
gi'anules, however, ai-e smaller and more
irregular' near the umbilicus, and the
fiuTows leading from the processes are
much more conspicuous; but the most
obvious distinction of this species is its
lurid appearance.

A. Bcevurice (Johnson, MS.). — Disc
smoke-colom-ed, with an ii-regmar blank
umbilicus, rather distant radiating lines
of large peai'ly granules, striated mar-
gin, and (3 or 4) roundish submarginal
processes. New Zealand. Of this beau-
tiful species we have seen only one spe-
cimen. The disc is small, apparently
nearlv iiat, with very distinct granules,
9 or 10 in -001", on a dark ground ; two
series leading to each process, wider
apart and more parallel than the rest
(VI. 5.)

A. Browncii (Norman, MS.). — Disc
coloured, with a minute umbilicus, close
radiating series of gi-anulos, and two or
tliree roundish iutranini-ginal processes.
Shell-cleanings, Cnlifoniia and else-
where in the Pacific. Fossil, Monteivy

OF THT! EFPODISCTI.'E.

845

stone. Disc small mider a low power,
bluish, with a darker, bro\vnish border.
The gi-anules, which, according- to Mr.
Norman, are about 17 in •001", are so
regidarly an-anged as to form concentric
circles as well as radiating series. A.
Browneii agi'ees in colour with A. Ore-
gamis, but in the arrangement of its
granules more resembles A. Beeverice.
From the foimer it differs in the regular
radiant arrangement of its granides,
smaller size, fewer processes, and much
flatter surface. From A. Beeverics it is
distinguished by its coloiu' and closer
granules.

A. Oregamis (Bailey). — Disc coloured,
with circular perforation-like umbUicxis,
convex centre, flattened border, short
cylindrical slightly emarginate marginal
processes, and series of minute crowded
granules. Bail. Proc. Acad. Philadelphia,
1853 ; Grev MJ. vii. p. 156, pi. 7. f. 2.
California, both recent and fossil ; Mon-
terey stone,, Puget's Sound. This very

distinct species is easily recognized by
its colom-ed disc and cylindi'ical emar-
ginate processes, which are fi'om 6 to 27
in number, and close to the margin.
Under a low power its minute gi-anules
appear an-anged in waved or oblique
lines, but imperfectly radiant under
higher powers, (vi. 4.)

A. ^!<fc/te?- (Norman, MS.). — Disc large,
colom-ed, with from 7 to 16 marginal
processes ; central gi'anules iiTCgadarly
scattered or crowded, the others in di-
stinct, close, radiant rows. Fossil. Mon-
terey stone. A. pulcher agrees with A.
Browneii in its colom-ed, slightly and
uniformly convex disc and radiant ar-
rangement of granides. It differs from
that species by its much larger size and
more numerous processes. The most
remarkable featm-e of this species is its
granulose centi-e, in which respect, as
well as in its radiant granules, it differs
from A. Oregamis. Granules 12 in -001".
(vni. 28.)

Genus AULISCUS (Ehr., Bail.).—" Fnistules cylindi-ical or discoid ; lateral
surfaces undulated, having two circular, flattened, mastoid, imperforate pro-
cesses--at some distance from the margin; umbilicus (generally present)
smooth, circular, surrounded by a plumose arrangement of dots and Lines •
sides smooth" (BC. 1854.).

" The projections on one valve are usually on a line at right angles to that
on which those of the opposite valve are placed " (B.). Kiitziag unites Auliscus
mth Coscinodiscus ; but it seems more nearly allied to Eupodiscus.

the margin towards the centre, but
leaving a well-defined central, four-
lobed or cruciform figm-e, with waved
Knes radiating in four sets from the
umbilicus. BC. pi. 1. f. 3, 4. In sand
from West Indian sponge, and in souud-
mgs from Mobile Bay. Umbilicus di-
stmct, smooth, the lines proceeding fi-om
it towards the processes in couvergmtr
cm-ves, the others vai-iously flexed imd
anastomosing.

* Disc ivith a conspicuous circular
icmbilicus.

AxTLiscus pruinosics (B.). — "Disc with
four sets of curved and sparsely punc-
tate lines, two diverging fi-om the large
.smooth umbilicus, while the other two
converge round the large processes."
BC. 1854, pi. 1. f. 5-8. Recent. United
States, (vi. 1.) " Frustules large, discoid
or cylindrical ; edges bevelled, central

{lortion in fi-ont view smooth or with
ongitudinal parallel lines " (B.). We
have seen fnistides of this species with
3 processes.

A. punctatus (B.). — Frustules like
those of A. pruitiosus, but their lines so
crowded and closely punctate that the
plumose arrangement is scarcely visible.
BC. pi. 1. f. 9. United States. " This
may prove a variety of the preceding;
but the sparsely punctate siu-Iace of the
one and the closely punctate surface of
the other appear to offer a sufficient
distinction between them" (B.).

A. calaius (B.). — Disc with unequal,
strongly marked lines proceeding from

2 * U^nhilicus wanting or obsolete.

A. sculptus (Smith). — Disc with un-
equal, strongly marked short lines, rndi-
atnig inwards from the margin and
leaving a well-defined central, four-
lobed space, marked with four sets of
fainter lines radiating from the centre.
=Eupod{scusiscMlptus,Q']i\).\.'n\ 4 f 42*
Bri MJ. vni. p. 94, pi. 5. f. 3. England"
(VI. .^.) 1 his species resembles A. co!-
latus, but has no umbilicus. We have not
seen tlie striaj of the central quatrefoil so
stronglv marked ns in Professor Smitli's
figiu-e, but jdways much fainter than the

846

SYSTEMATIC niSTORT OF THE INFITSOUIA.

marginal ones; indeed sometimes they
are very indistinct.

A. Americanus (E.). — Disc with
strongly marked lines, radiating inwards
from the margin and leaving an irregular
central space destitute of lines. EM.
pi. 33. 14. f. 2. United States. The
large processes, as well as the centi-al
space, are without the radiating lines of
A. sculptus ; but we think it probable
that Ehrenberg's figm-e was taken from
a specimen of that species in which
those markings were more than usually
inconspicuous.

A. cylindricus (E.). — Frustules cylin-
drical, with a plane orbicular disc on
each side, having a rim and a central
area marked by various radiating lines ;
processes resembling oblique openings.

A. ovalis (Arnott, MS.). — Disc oval,
with two opposite, nan'ow, hispid ele-
vations midway between the roundish
perforation-like apices of the processes ;
cm-ved lines punctate, rather faint ; um-
bilicus obsolete. Algoa Bay and Peru-

vian gnanos. Communicated by Mr.
Kitton. This species is distinguished
by its oval disc and hispid elevations.
The truncated processes do not in general
correspond exactly with the longer dia-
meter of the valve, but are placed a little
on one side in opposite directions, in
which respect, as well as in the presence
of hair-like spines, it approaches Cera-
taulus.

Doubtful Species,

A. polystigmus (E.). — Eadiating series
of cellules converging in two lateral
obsolete whorls, which appear perforated
(processes?). Cellules 14 in 1-1200".
Diam. 1-360".= Coscinodiscus polysiigina,
KA. p. 124. North Sea.

A.? ffiffas (E.). — Margin of sides tu-
mid, looldng as if perforated, sculptured
by elegant rows of dotted, imperfectly
radiant lines. EM. pi. 19. f. QS.= Cos-
cinodiscus Aulisms, KA. p. 126. Fossil.
vEgina. Ehrenberg's figure represents
a mere fragment.

FAMILY X.— BIDDULPHIEiE.

Frustules cellulose, compressed ; lateral valves entering into the front view,
and usually more or less produced, at one or both angles, into processes. The
Biddulphieae are remarkable for the great development of the lateral valves of
the frustule, which are so convex or inflated as always to enter largely into
the front view, causing the central zone to appear like a band between them.
The mode of growth in this family is very interesting. Instead of simple
elongation and subsequent division of the central zone by means of internal
septa, new central and inner lateral valves are formed within the elongated
original one, which, until niptm-ed, retains the frustules in pairs. The central
zone is at first very narrow and merely a broad line, but it increases greatly
in breadth until the new frustules axe fully formed.

Genus CEEATAULUS (Ehr.). — Frustules with turgid lateral valves, each
valve with two tubular processes alternating with the same number of horn-
like spines ; lateral view orbicular or broadly oval. Cerataulus seems, in some
measure, to connect the Biddulphiea3 with the Eupodiscca3, since, in a lateral
view, it approaches the latter in the circular form of some of its species ; the
front view, however, is similar to the other genera of this family : the fi-us-
tules are binately conjoined by an external punctated sheath, and their pro-
cesses are definite in number. Ehrenberg describes the fmstules as simple,
by complete fission ; but Professor Bailey finds them concatenate. Cerataulus
is characterized by having stout horn-Hke spines, which are not situated on
protuberances between the two processes, but alternate Avith them, and form
part of the same circle.

CEUATAtTLUS tun/l'dus (E.). Pl'O-

cesses short, broad, and truncate ; lateral
valves broadly elliptic, with a submar-
ginol band of apiculi. EB. 1843, p. 270.
BiddulpJiia turyida, SBD. ii. p. 50, pi. 62.

f. 384; Ro TMS.
Europe, ^Vmerica.

vii. p. 17, pi. 2. f. 23.

Professor Bailey thus
describes this species : — " Fi-ustules glo-
bular or slightly compressed, with two
large prominences at each end, cohering

OF THE BIDDITLPHrEiE.

847

by alternate angles, fonning zigzng
chains. Between the two processes, and
in a plane at right angles to that con-
taining them, are placed two long horn-
like processes. Two frustides are often
connected by an external decussately
punctate cell, as in Isthmia and Bid-
dulphia." The processes do not exactly
con-espond with the angles, but ai-e situ-
ated a little to the side in opposite di-
rections. This species, beautifidly figured
in Professor Smith's excellent work, is
easily recognized by its broad, truncated
processes, (vi. 8.)

C. Smithii { Ra.). — Valves in front view
turgid ; processes conic, alternating with
subidate horn-like spines ; lateral valves
orbicular; cellules Abstract. =EupocUsciis
radiatus?, SBD. i. p. 24, pi. 30. f. 255
(not Bailey) ; Biclclulphia radiata, Ro
TMS. vii. p. 19, pi. 2. f. 27-29. Thames.
The orbicidar form and differently shaped
processes distinguish this species from
the preceding. The cellules are not
radiant ; and as Professor Smith's name
was bestowed in error, and is liable to
mislead, we have thought it advisable to
change it.

C. Icevis (E.). — Frustules large, qua-
di'angular, with short, broad, trimcate
processes and sti-aight intermediate mar-
gin ; valves suborbicidar, obscurely punc-
tate, with two minute, opposite, subme-
dian spines. =Biddulphia Icevis, EB. 1843,
p. 122 ; Ro MJ. vii. p. 18, pi. 2. f. 24-26 ;

Odontella poli/morpha, KB. 1844, pi. 29.
f. 90 ; Isthmia polymorpha, Montague.
Shores of North and South America,
(VI. 7.)

C. thermalis (Me.). — Large, jomts cy-
lindi'ical, angularly concatenated by a
lateral isthmion ; lateral valves very
smooth. = Melosira (^Pleurosira) thermalis,
Menegh. ' On the Animal Nature of
Diat.,' p. 391. Warm springs of Eugania.
Length of frustides very variable. Kiitz-
ing refers this to the preceding species,
— a decision from which INIeneghini dis-
sents. The following extracts are takea
fi-om the work of the latter : — " Kiitzing
says, ' Your Melosira (Bleurosira) ther-
malis is in no respects ditFerent fi-om the
Odontella polymorpha. I have compared
yom' specimen with that of Montague.
There are even foimd the delicate points
upon the shield, as in the other, which I
have inadvertently omitted in my figure.
Your specimen is certainly an Odontella,
although the articidations are cylindri-
cal.' " On this opinion Meneghini makes
the following comments: — "Although
I have had an opportunity of examining
fragments only of Montague's Isthmia
polymorpha, I am positive in treating
the matter dififerently. It is admirably
figured by Kiitzing ; the articulations are
not cylindrical, and, though obtuse and
slightly prominent, the lateral processes
are very evident." For other distinctions
between them, see the work quoted, p. 483.

Geniis BIDDULPHIA (Gray). — Frustules compressed, quadrilateral,
cohering by their alternate angles, and thus forming a zigzag chain ; angles
equal, elongated into tooth-like projections ; spines none, or confined to the
intermediate rounded projections ; lateral valves constricted laterally at their
base. Great difference of opinion exists as to the proper arrangement of the
forms here associated, whether they should be included in a single genxis or
not. Ehrenberg and Kiitzing distribute them in two genera ; but although,
their genera appear identical, yet their definitions differ so much as to make
the agreement in fact merely nominal. Professor Smith unites Cerataiilus and
Zygoceros, as weU as Odontella, to Biddulphia, whilst Professor Bailey, whose
opportunities of studying this family have been so ample, admits the propriety
of conjoining Biddulphia and Odontella, but is not prepared to add Zygoceros.
Brebisson, who first conjoined Biddulphia and Odontella, subsequently recoo--
nized both genera. Ehrenberg and Kiitzing concur in describing Biddulplaa
and Odontella (Denticella, E.) as concatenate, and Zygoceros and Heniiaulus
as simple. Ehrenberg distinguishes Biddulphia from OdonteUa by the ab-
sence of spines, which are present in the latter. Kiitzing, on the other hand
characterizes OdonteUa as smooth (not ccUiUose, though often punctate or
granulate), without internal septa, and Biddulphia as regularly punctato-
ceUulose, with internal septa. Smith fiuds spines in the typical species of
Biddulphia ; and Bailey considers the presence or absence of spines an unim-
portant accident, "We retain our former opinion, that we cannot exclude any

848

SYSTEMATIC niSTOHY OF THE INFUSORIA.

species from Biddulphia merely on account of the absence of costsc, without
violating natural affinity, and dividing Isthmia also. In IJiddulphia, Kiitzing
forms his species solely from the number of lateral costae and consequent
divisions (chambers) ; his species, however, have been generally rejected ; and
we think that, like similar characters in Actinoptychus and other genera, such
distinctions are essentially erroneous.

* Valves with undulating margins and
tramvm'se costce or depressions.

Biddulphia pulchella (Gray). — Frus-
tules distinctly reticxilated ; valves with
obtuse processes, and from one to five
smaller intermediate projections sepa-
rated by costas extending to the suture.
SD. ii. p. 48, f. 321. B. irilocularis, Kutz.
(with two costse) ; £. quinquelocularis,
Kiitz. (with four costse) ; B. septemlocu-
laris, Kiitz. (with five costae) ; Denticella
Biddulphia, E. (central projection ai-med
with spines) ; B. australis, Montague ;
B. elongata, Montague (with broad cen-
tral portion), (ii. 46 to 50.) The di-
stinctive character of this species is the
costse or imperfect septa which separate
the projections. Lateral valves oval, with
imdidated margins and a large pseudo-
opening at each end. In the yoimg state
there is only one rib, and no interme-
diate projection.

B. Regina (Sm.). — Valves with three
median elevations, the central one
largest, unai-med ; processes little ex-
ceeding the median elevation in length,
papillate, rounded ; cellules of elevation
distinct, those of valves and central zone
minute. SD. ii. p. 50, pi. 46. f. 323 ;
Ro TMS. vii. p. 8. Dredged off the
Island of Skye. Professor Bailey refers
this species to B. tridentata, and Pro-
fessor Wniiamson, according to Pro-
fessor Smith, to B. Tuomej/i. We have
seen no specimen, but trust to the well-
known accuracy of Professor Smith's
figures for its distinctness in the form
and comparative shortness of its pro-
cesses.

B. tridentata (E.). — Lateral valves
dotted, having elongated, obtuse pro-
cesses, and one to tlu'ee unequal inter-
mediate projections; constrictions ap-
proaching the suture. EM. pi. 19. i. 21.
= Denticella tridentata, E. (central pro-
tuberance aiTned) ; Denticella Tridens, E.
Fossil. America. Professor Bailey re-
fers B. Regina, Sm., to this species, but,
judging from the descriptions and figures,
they seem to us distinct. In this species
the processes arc more slender, longer
than the intermediate projections, and
mostly constricted bencntjii the apex.

Mr. Roper unites this species to B.
Tuomeyi, and is probably right in bo
doing.

B. obtusa(K.). — Frustulesvery smooth,
short, with turgid, obtuse, short horns,
and a very short intennediate process. =
Odontella obtusa, KA. p. 136. Heligo-
land, (xin. 30 to 32 a!)

B. suhaqua (K.). — Frustides oblong,
very smooth; horns minute, withoutinter-
mediate '^ro]&ciiona.= Odontella siibcequa,
KB. pi. 18. 8. f. 4, 5. Heligoland. Pro-
fessor Smith is probably right in regard-
ing the last two as states of B. aurita.

B. Icevis (E.).— Has the habit of B.
aurita, but its valves are smooth and
tridenta,te. = Denticella Icevis, EM. pi. 33.
15. £ 6. Antai-ctic Sea. Diam. 432",
Ehrenberg's figm-e of this species but
slightly resembles B. aurita: the horn-
like processes are elongated, slender, and
awl-shaped, and not the least inflated at
the base ; the intermediate margin also
is convex, and not elevated into a central
projection.

B. Tuomeyi (B.). — Valves having ob-
tuse homs with swollen bases, between
which are fi'om one to three shorter,
roimded projections, the middle one
largest, and often bearings two spines. =
Zygoceros Tuomeyi, BAJ. xlvi. pi. 3.
f. 3 to 9. Fossil. America, Patos guano.
(vT. 10.) The central zone is narrow-
linear, and slightly projects at each end ;
lateral valves covered with shagreen-like
asperities, which are most evident on the
projections; processes ^enerallj' con-
sti-icted. At the base ot each swelling
is a short, linear, hyaline line which re-
sembles a perforation, but which we be-
lieve is really a smooth elevation.

B. polymera (E.). — Lateral valves
granulated, veiy broad and short ; angles
elongated into conical processes ; inter-
mediate projections several (about nine),
rounded, the centi-al one lai^est. —Denti-
celh? poh/mera, E., BAJ. xhnii. pi. 4.
f. 20 ; OdonteU^t ? polymera, K. : B.
Tuomeyi, Ro TMS. vii". p. 8. Fossil,
I3ermiida. The lateral valves are so
short that the consti-ictions between the
lobes reach nearlv to the base. This
species is remarkable for the great num-
ber of intermediate projections, of which

OF THE BIDDULPHIE^,

849

the central one is the largest, the others
decreasing regularly on each side, two of
them aimed. Mr. lioper unites this form,
probably correctly, with B. Tuomeyi.

2 * Valves Iwiceolate or elliptical, without
undulated margins (Odontella, Ag.).

B. aurita (Lyngb., Br^b.). — Frustules
finely pimctated ; angles prolonged into
slender conical horns, with an interme-
diate projection, which is usually fm--
nished with a few spines ; valves elliptic-
lanceolate. SBD. li. p. 49, pi. 45. f. 319.
= Odontella aurita, Ag., K. ; Denticella
aurita, E. ; Denticella gracilis, E. Ame-
rica, Africa, Europe.

B. Itoperiana (Grev.). — ^Valve elliptical
oval, with central elevation, which in
front view is depressed or sometimes
bilobed, punctate, unanned ; angular pro-
cesses scai'cely produced, obtuse, largely
inflated at base ; connecting zone with
rows of minute granules, parallel with
suture of the valve. Grev JMS. vii.
p. 163, pi. 8. f. 11-13. Seaweed, Mon-
terey ; Californian guano. " This species
appears to be removed from B. aurita and
its vaiieties by the absence of spines, and
the very depressed, often two-lobed cen-
tral elevation of the valve " (Grev.).

B. longicruris (Grev.). — ^Valve in front
view with central elevation, bearing a
very long spine ; angular processes very
much produced, awl-shaped ; surface
minutely gi-anulate. Grev JMS. vii.
p. 163, pi. 8. f. 10. Californian guano ;
Sierra Leone.

B. turgida (E.). — Lateral portions in
front view scabrous, with produced,
conical, obtuse angles, and two distant,
long, intemiediate spines; valves elliptic-
lanceolate. = Denticella turgida, EB.
1840, p. 207; Odontella turgida, KB.
t. 18. f. 89 ; Biddidphia granulata, Ro
TMS. vii. p. 13, pi. 1: f. 10, 11. Atlantic.
Britain. Processes large, inflated at
base, slightly recurved ; spines generally
slightly Dent at the middle ; valves rough
with minute apiculi.

B. reticulata (Ro.). — Valves hirsute,
with large hexagonal reticulations ;
processes obtuse, subconic, inflated and
gibbous at the base. Ro TMS. vii. p. 14,
pi. 2. I 14-17. Ceylon, Natal, New
'iealand. Valves elliptic; connecting
zone having rows of rather conspicuous
dots.

B. Indica (E., Ro.). — Valves hirsute,
with slender, elongated, subcapitate pro-
cesses, and a long awl-shaped spine
near each process. Ro TMS. vii. p. 16,

pl.2.f.20-22.=:DeM!!/ce& Indica, ERBA.
1846, p. 362. Natal, (vi. 12.) Valves
lanceolate, with the pseudo-apertures at
right angles to the length of the valve,
Roper.

B. tu?nida (E., Ro.). — Valves broadly
elliptic, with very fine radiating dots,
and two or three submarginal spines ;
in front view globose, with tapering
obtuse processes. Ro TMS. vii. p. 15,
pi. 2. t. 18, 19. = Denticella twnida,
ERBA. 1844, p. 266 ; Odontella twnida,
KSA. p. 137. Bermuda ; Californian
guano.

B. Macdonaldii (Norman, MS.). —
Frastides finely striated, with very short,
nearly obsolete processes; valves with
transverse sti-ise mterrupted by a median
line. Shark's Bay, Australia, (vm. 23.)
Valves minutely dotted between the
striae ; frustules somewhat twisted. For
the description of this species we are
indebted to G. Norman, Esq.

Doubtful or imperfectly known Species,

B. ? ireiiis (E.). — Small, laterally lan-
ceolato-rhomboid, smooth, tripartite
with two septa; lateral portions also
three-lobed ; lobes small, subequal ;
pseudo-openings obsolete. KA. p. 138.
Portugal.

B. ? gigas (E.). — Large, very turgid
at the centre, rough, without distinct
granules, laterally five-jointed, having a
large, oblong (pseudo-j opening at each
attenuated apex. KSA. p. 138. FossU.
Bermuda. l)iam. 1-144.

B. ? lunata (E.). — Valve three-lobed,
smooth, slightly ciu-ved, lunate, with
subacute horns. EM. pi. 18. f. 53. Fossil.
Virginia. Diam. 1-864".

B. ? ursina (E.). — Lai-ge, turgid, not
cellulose ; sides hirsute, not constricted,
middle part smooth. KSA. p. 138,
fragment. Antarctic re^ons. Diam.
1-192". Remarkable for its hairiness.

B. ? ampldcephala (E.). — Smooth, nar-
row, wand-like, concatenate, constricted
beneath each apex ; hence each end capi-
tate, rounded. = Odontella? amphiccjihala,
E. KSA. p. 137. Moutli of the Tagus.
Lidividual frustules resemble those of
Navicula dicephala in habit.

B. P Fragilaria = Denticella ? EM.
pi. 21. f. 31. Algiers. Perhaps a frag-
ment of Eucyrtidmm lineatum.

B. ? Cirrhus (E.).— In Barbadoes earth.
We have seen neither description nor
figure of this species.

3 I

850

SYSTEMATIC HTSTOKY OF THE INFUSOEIA.

Genus PORPEIA (Bailey, MS.)- — Prustules simple (?), compressed, each
valve with two short obtuse processes, and two internal curved plates which
do not extend to the central portion. We give this genus in deference to the
opinion of our highly esteemed correspondent the late Professor Bailey, hut
doubt whether it is sufficiently distinct from Biddulphia. In Porpeia the
septa appear like costa3 incurved at their inner ends.

Porpeia quadricqis (Bai. MS.). — Pro-
cesses with pimctated rounded ends, the
intermediate margins slightly convex;
lateral view naiTow, with two constric-
tions, and rounded ends. Gulf-stream,
(vi. 6.) From di-awiags by Professor

Bailey. "At first sight this species
suggests a relation to Grammatophora ;
but the curved plates run at right angles
to their position in that genus ({. e. not
larallel to the division of the fi-ustules,
ut perpendicular to it)." — B. in lit.

Genus ZYGOCEROS (Ehr.). — Erustules free, compressed, not concatenated ;
each valve with two (apparently) perforated horn-lilve processes. Although
we have retained this genus, yet we think it is very probable that a better
knowledge of its species will justify Professor Smith in uniting it with
Biddulphia, from which it differs only in its simple frustules.

I

Zygocehos Rhombus (E.). — Frustides
tiu-gid, with a smooth or faintly punc-
tated central portion; lateral valve rhom-
boid with roimded angles, its surface
having very fine gramdated striae. =
Biddulphia Rhomhus, SBD. ii. p. 49,
il. 45. f. 320; Ro TMS. vii. p. 11, pi. 1.
4. America, Europe, England. /3, valves
with one or more median spines, = -Dew-
ticella Rhombus, E. ; Odontella Rhombus,
K. Lai-ge ; sti-ice 24 to 26 in 1-1150".
Diam. 1-720". "Spines submarginal,
awl-shaped, abbreviated " (Sm.).

Z. radiatus (B.). — Frustules large,
tiu'gid; lateral valve rhomboid, with
rounded angles and radiating series of
gramdes. BSC. vii. Z. Balmna, EM.
pi. 35. A. 23. f. 17 ; Bri JMS. vii. p. 181,
pi. 9. f. 15. Nova Scotia. "Akin in
habit to Z. Surirella, but lai'ger than
Z. Rhombus. Central zone punctated "
(Ehr.).

Z. Surirella (E.). — Frustules small;
lateral valve lanceolate, with constricted
obtuse apices ; surface with transverse
granular lines, intennpted by a median
longitudinal band. Ro TMS. ii. pi. 6.
f. 11, 12. Alive. Europe. Thames.
(XI. 50, 51.) Diam. 1-720". Central por-
tion smooth, grauides of valves more di-
stinct than m Z. Rhombus. Distin-
guished by the smooth longitudinal line
m a lateral view.

Z. Bipons (E.). — Frustides laterally
lanceolate, with acute ends, and two
smooth median constrictions; granules
delicate, not radiant. KSA. p. 139.
Borauula deposit. Diam. 1-384". Angles
with small hovTis. May be Imown by
having, in the lateral view, two trans-
\ lines.

Z. stiligcr (E.). — Frustules laxly cellu-
lose ; valves with double median con-
striction of the side; angles produced
into long, acute, stUifonn horns. KSA.

?. 139. Fossil. Bei-muda deposit. Diam.
-1152". " Z. stilifjei' may be a species of
Hemiaidus ; but the constiictions resem-
ble those of Biddulphia, save that they
want the wide apertures of the horns "
(Ehr.).

Z. australis (E.). — Frustules smooth ;
horns obsolete; lateral valve tingid-
lanceolate, with conspicuous pseudo-
openings. KSA. p. 139. Antai'ctic Sea,
Diam. 1-480".

Z. ? Circimis (B.). — Fmstules minutely
and decussatelj^ pimctate ; lateral valves
foiTuing truncated cones without pro-
cesses, but each having two long, seti-
form, bent spines ; lateral view elliptic
BC. vii. pi. 1. £ 19, 20. FossU. Vir-
ginia. Characterized by the conic out-
line of the lateral valves, and the absence
of processes.

Z. Navicula, EM. pi. 19. f. 22. Fossil.
Greece. Lateral valve oblong, -wnth
transverse rows of dots, a transverse
smooth median band, and a pseudo-
opening at each end.

Z. paradoxus (E.). — Smooth, laterally
liuear-oblong with rounded ends. EM.
pi. 22. f. 54. = Surirella paradoxa, EM.
Caltanisetta, Sicilv. 1-576".

Z. Simlus (E.Y — Smooth, linear;
laterallv rhomboid, with obtuse ends.
EM. pi 22. f. 53. = Surirelia rhomboidea,
EM. Fossil. Sicily. 1-744".

Z. 3Iobili('usis (B.). — Frustules qua-
di-angular, thin, delicately punctate;
valves A\nth slender, tapering latei-al
procoisses, and two sliglit iutenuediate (

OF THE BIDBTTirHlEiE.

861

projections armed with one or two very
long filiform spines. BC. 1859. =jBid-
dulphia Jiailei/ii, SBD. ii. p. 50, pi. 62.
f. 322 ; Ro TMS. vii. p. 12, ]j1. 1. f. 5-9.
America. In stomach of Ascidise. Hull,
Teignmouth. (vi. 11.) Fa-ustules fra-
gile, yellowish. A well-marked species ;

there is no central projection of the valves,
but two slight elevations, fui-nished with
one or more bristles, and dividing the
mai-gin into three neaily equal portions.
The elevations appear situated between
the processes, but are really placed on
opposite sides.

Genus HEMIAULUS (Ehr.). — Fnistules compressed, subquadrate ; fission
perfect, hence not concatenate ; valves without lateral constrictions, each with
two processes— that of the one side (apparently ?) open, the other closed. The
genus has the habit of Biddulphia, but is devoid of the lateral constrictions.
It has the form of a Pandean pipe. As the valves are not constricted, the
basal angles are rectangular, and the outer maxgius of the processes (which
are generally attenuated, narrow, and elongated) are straight.

Hemiaulus antarcticus (E.). — Frus-
tides strongly gi'anular ; lateral processes
elongated, of one valve truncate, of the
other elongated ; a short median rounded
projection between the processes. EM.
pi. 35. A. 22. f. 15. Antarctic Sea. (xi. 54.)
Diam. 1-1152". Granules in parallel
rows.

H. Polycystinonim (E.). — Angles ex-
tended into very long, naiTow, linear,
hom-like processes, which ai'e attenuated
at the exti'emity, and, as well as the base,
cellulose. EM. pi. 36. f. 43. Barbadoes
deposit. Between the processes are from

one to three slight projections ; lateral
view oval, bordered, having transverse
bars corresponding in number to the de-
pressions.

H. ? Atistralis (E.). — Valves sti'ongly
o^-anulate ; lateral processes roimded,
mtermediate one obsolete. KSA. p. 139.
Antarctic Sea.

H. ? CaUformcus (E.). — Valve granu-
late, having a subquadrate base ; angles
extended into linear processes without
Intel-mediate projections. EM. pi. 33. 13.
f. 15. In Califomian tiipoli.

Genus ISTHMIA (Ag.). — Frustules compressed, trapezoidal, cellulose,
attached, cohering by short neck-like processes, so as to resemble irregularly
branched filaments. Frustules always more or less oblique, the lower angle
of each prolonged into a process by which it coheres to the one beneath, and
which in the basal fmstule forms the stipes by which the filament is attached.
The fi'ustules are tui'gid, and the reticulations of the central portion smaller
than those of the sides.

IsTHMA enervis (E.). — ^Lateral valves
with large, somewhat quadrate cellules
arranged in transverse parallel lines.
= Conferva ohliquata, EB. t. 1869 ; I.
obUquata, Ag. ; /. nervosa, KSA. p. 135 ;
E Inf. p. 209, pi. 16. f. 6 ; SBD. ii. p. 52,
pi. 48. Europe, America, Cape of Good
Hope, &c. (x. 183.) The lateral por-
tions are separated from the central one
by rather broad lines, produced by the
junction and inflection of the margins,
and which form internally projecting
plates or rims. The cellules Dordering
the sutiu-es are somewhat larger than
the other cellules of the central portion,
but less remarkably so than in the next
species.

I. nervosa (K.). — Lateral portions with
parallel transverse costre, having two or
more series of hexagonal cellules in each
mtervnl. = Diatoma obliquatum, Lyng. ;

I. ohliquata, E. ; I. nervosa, KA. 135 ;
SD. ii. p. 52, pi. 47. Northern shores of
Europe and America. This is usually a
more northern species than /. enervis.
The cellules are smaller, except a series
of large conical ones bordering the imier
side of the sutures, and the frustules are
generally not so wide in proportion to
their length; but the most evident di-
stinction is the division of the lateral
portions into compartments by the costre,
which often anastomose.

I. minima (Ilarv. & B.). — Central por-
tion very finely decussately pxmctated ;
lateral portions granulated bv large
coUules. Proc. of Acad, of Phil. Kio
de .Taneiro and Sooloo Sea.

Imperfectly known,

I.? Africana (E.). — Large flat frag-
ments resembling the central portions of
3 I 2

852

SYSTEMATIC HISTOBY 01' TUB INfUSOKlA.

Istlimia, niai'ked by ti-ansverse rows of | ERBA. 1844, p. 83. Diameter of largest
very minute cellules. Oraii, Afiica. | fragment 1-216".

GcnuB HYDEOSERA (Wallich). — Prastules quadi-ate, united into fila-
ments, and furnished witli conspicuous horizontal bands or septa; valves
cellulose, compressed, or triangular, with internal septa, and, on one side only,
with minute, aperture-like appendages. Marine. Filaments elongated,
attached, compressed, or prismatic. Joints rectangailar, connected at the
angles by mucous cushions, and marked by bands passing across the valves
and connecting zone. In the lateral view the ends or angles are separated
by septa. Hydrosera seems allied on the one hand to the Terpsinoeae, and on
the other to the Biddulphieae and Angulifereas.

Hydhoseba compressa (Wallich). —
Filaments compressed; valve oblong,
divided into three inflated compartments
by two ti-ansverse septa. Wallich, MJ.
vi. p. 252, pi. 13. f. 7-11. East Indies.
Side view with blanlc angles, occasionally
furnished with a few minute spines.
(VI. 8.)

H. triqudra (Wallich). — Filaments

triqiietrous ; valves triangular, with the
subcircular centre di\-ided from the ob-
tuse, somewhat produced angles by
septa. WaUich ]\IJ. y\. p. 251, pi. 13.
f. 1-6. East Indies. Front Adew vsdth
fom- ti-ansverse bands ; valves -with im-
didated sides, reticidated, except at the
angles, which ai-e furnished with a few
extremely minute spines (vi. 13.)

FAMILY XI.— ANGULIFERE^.

Frustules cellulose or granulate ; in lateral view angular. This family is
closely aUicd to Biddulphieae (and in some manner connected with the Cosci-
nodiscese and Eupodisceae). As in that family, the lateral portions are seen, in
the front view, having the central portion like a band between them. Hence,
in order to determine their proper family, it is frequently necessaiy to see
them laterally. The angles, however, in the front view are usually less
elongated, and the intervening margin less lobed in the Anguliferese than in
the Biddulphieae.

Genus EUODIA, n. g. (Bailey, MS.). — Frustules cellulose or granulate ;
in lateral view lunate. Euodia agrees with the Eunotieae in the shape of its
fnistules, which can scarcely be called angular ; yet, notwithstanding that
resemblance in form, its punctate or granulate sui-face induces us to i^lace
it' here.

Euodia (/ihha (Bai. MS.). — Frustules
in lateral ' view semiliuiate, the ends
somewhat conical, the lower margin
gibbose ; surface with radiating scries of
minute granules. Recent. Gulf Stream,
(viii. 22.) From a drawing by Pro-
fessor Bailey. The upper margin is veiy
convex, the lower one less so. A con-
traction near the obtuse cuds makes
them appear somewhat produced and
conical. Professor Bailey represents the
cross section as cuneatc. Gomothecium
unaulis, EM. t. 33. 18. f. 4, greatly re-

sembles this species, and may be iden-
tical. The upper margin, however, is
represented as more convex, the ends less
produced, and the granules lai^er and
less umnerous.

E. P Brif/hfwdUi. — Frustules seniilu-
nate, ends scarcely produced, lower
margin concave ; granules somewhat
concenti'ic. = Tnccrattnm scmicircuhre,
Bri MJ. i. p. 252, pi. 4. f. 21. Berumda
earth. T. oUmum, EM. pi. 18. f. 49,
may probably be referred to this species.

Genus ITEMIDISCUS (WaUich).— Frustules free ; valves cellulose, arcuate,
with a ventral marginal nodxdo; ccUuJation hexagonal, radiate. Marine.
Wo doubt whether Homidiscus bo distinct from Euodia, since tlio only di-

OF THU ANGTJLrPEBEiE.

853

stinction scorns to be the marginal nodule of the former, — a character perhajis
overlooked by Professor Bailey.

ELemidiscus cuneiformis (Wallich). —
Valves semiluuate ; venter ^vitli a mar-
ginal row of puncta, and slightly gibbous
at the middle. Wallich, TMS. \iii.

p. 42, pi. 2. f. 3, 4. Bay of Bengal and
Indian Ocean. Cellulation distinct,
largest at the centre. Connecting zone
broadest at the dorsmn. (vi. 14.)

Genus TEICEEATIUM (Ehr.).— Prustules cellulose, free, simple ; in lateral
view triangular (rarely with four- or five angles). This genus has been well
illustrated by Mi-. BrightweU in his excellent monographs published in the
* JoiuTial of Microscopical Science ; ' so that the species can be distinguished
without much difficulty. His discovery, in more than one species, of frustules
with foiu' or even with five angles, shows that in this, as in several other cases,
the number of parts do not afford good generic distinctions. We were inclined
to place greater reliance upon theii- complete fission ; but Professor Bailey in-
formed us that he had met with catenate specimens. Mr. BrightweU, indeed,
says that " the projection of a connecting membrane (central portion) beyond
the suture of the valve, which is one of the characters of the genus Amphi-
tetras, is not seen in the square forms of Triceratiimi ; " but we greatly doubt
the validity of this distinction. " One of the difficulties attending the study
of this genus, and the determination, especially in the fossil forms, of the
species, arises from the difficulty of obtaining perfect fnistules, and examining
them in their front aspect. The imperfect frustules pi'esent only the end or
triangular wall, from which alone no perfectly satisfactory specific character
can be obtained " (Br.).

The descriptions, unless otherwise specified, apply to the lateral view of
the fnistules, and are drawn up, with few exceptions, from Mr. Brightwell's
monographs.

* Lateral surfaces spinous.

TniCBRATrcnM spinosum (B.), — Sides
nearly straight j angles prolonged into
horn-like processes ; granules minute ;
spuies numerous ; front view constricted
beneath the processes. Silliman's Jour-
nal of Science, xlvi. pi. 3. f. 2. = T. seti-
genirn, BC. 1854, pi. 1. f.24 ; T. armatum,
Ko MJ. ii. p. 283 ; T. tridactyhim, Bri
MJ. i. p. 248, pi. 4. f. 3. Fossil, Ame-
rica; recent, England, Florida, (vi.
19.) A variable species ; its numerous
seines and somewhat triradiate form best
distinguish it. Larger spines are often
interspersed among the smaller ones.

T. compactimi (Bri. MS.). — Spinous;
front view constricted beneath the some-
what inflated processes ; centi'al portion
bordered by a series of large cellides. =
T. armatum, ^, Bri MJ. iv. p. 274, pi. 17.
f. 11. Recent. Austi'alia. Smaller than
T. spinosum, but like it in form, having
a spiue on the middle of each side. In
the fifont view it is very different.

T. coniferum (Bri.). — " Sides hrcgii-
Inrly concave ; angles drawn out into an
extended cone with a short, stout horn
near each; centre of frustule convex,

with three setfe." Bri MJ. iv. p. 274,
t. 17. f. 6. Shell cleanings. The mani-
millate angles, giving the sides a waved
appearance, mark the species. The gra-
nules are not radiant.

T. contortum (Sh.). — Angles prolonged
into cm-ved horn-like processes; spines
in three radiate double rows, terminating
near each angle with a long bristle. Sh
TMS.ii.p.l5, pi. l.f.7. Recent. Natal.
(vi. 18.) Well distinguished by its con-
torted angles. Sides straight. '

T. orbiculatum (Sh.). — Sides convex;
angles obtuse, each with a circular
pseudo-nodide accompanied by a spiue ;
granules minute, radiating. Sh TMS. ii.
p. 15, pi. 1. f. G. Natal. The front view
shows the narroAv central portion marked
like the lateral portions, which are large,
not constricted, and terminated by three
truncated cones. Mr. BrightweU" enter-
tains no doubt as to the identity of his
specimens with Mr, Shadbolt's species ;
yet the latter's figure has no spines, and
he describes " the margin being so in-
flated as to cause the triangular outline
to approach that of tiic circle."

'I\ 3Lin//<iu(lirn)ii (l$ri.). — Sides ut-iuly
straight, with rounded angles, without

854

SYSTEMATIC HISTOHY

or TKE INFtrSORIA,

pseudo-nodules ; gi'anules minute, radi-
ating- from an angular umbilicus ; spines
few, marginal. Bri MJ. iv. p. 275, pi. 17.
f. 17. Mai-yland deposit. There is at
each angle a short spine, and sometimes
another at the middle of each margin.
Professor Bailey regards this species as
identical -with T. Amblyoceros ; but we
cannot believe that Ehrenberg would
have omitted so remarkable a character
as the angular umbilicus, nor are both
species found in the same deposit. We
have already given our reasons for doubt-
ing the correctness of the supposition
that Ehrenberg founded his Symholo-
phora Trinitatis upon this species.

T. annulatum (Wallich). — Valve mi-
nute, with slightly produced roimded
angles and concave sides ; sm-face marked
with concentric rings, and a ray proceed-
ing from the centre towards eacli angle.
Ganges. "Wallich, MJ. -^d. p. 249, pi. 12.
f. 15. Valves covered with minute
puncta, aggregated into concentric rings.

2* Lateral surfaces with radiating
vein-like lines.

T. racliatmn (Bri.). — Sides straight;
angles obtuse ; radiating lines most evi-
dent at centi-e and margin; granules
minute, radiating. Br. I. c. p. 275, pi. 17.
f. 14. Barbadoes deposit. Frustules
large, without horn-like processes.

T. marginatum (Br.). — Valves with
a triangidar centi'e, which is surrounded
by a broad border divided into compart-
ments by short transverse lines. Br MJ.
iv. p. 275, pi. 17. f. 13. FossH. Sides
sti-aight, angles with double pseudo-
nodides ; gi-anules of centre minute,
radiating, those of compartments larger
and scattered.

T. venostim (Br.). — Sides concave ;
angles rounded, sm-face dotted, and
marked by three radiating pinnated lines
or veins, (^t:. 17.) Br MJ. v. p. 274,
pi. 17. f. 5. Barbadoes deposit. A very
beautiful and distinct species.

T. tahellarium (Br.). — Mai'gin indented
in foliaceous curvatures ; granules nume-
rous near the margin, elsewhere in

Satclies ; angles vnt\\ small horns. Br
I J. iv. p. 275, pi. 17. f. 15. Honduras.
This species is well distin^iislied by its
scolloped margin. It is doubtfid wlie-
ther it is properly placed in tliis section.

T. vnridbile (Br.). — Surface ^vith a
transverse line below each angle, and
some iiTegular radiating vems ; granules
scattered, indistinct at the nndes. Br
^I.T. iv. p. 275, pi. 17. f. 10. Peruvian

guano. Resembles T. alternans, but is
larger and generally distorted ; the angles
are conical. Mr. Brightwell figures a
quadi-angular form of this species.

T. truncatum (Br.). — Angles elongated
into broadly truncate amis, centre di-
vided into gi-amdated compartments by
radiating vein-like lines. Br MJ. iv.
p. 274, pi. 17. f. 4. Barbadoes earth.
Frustules triradiate.

3* Lateral surfaces with transverse lines
separating the angles from the liexagonal
centre.

T. hrachiatum (Br.). — Triradiate ; an-
gles elongated into tnmcate arms, and
separated from centre by transverse lines.
Br MJ. iv. p. 274, pi. 17. f. 3. Barbadoes
earth. Distinguished by its angles pro-
longed into rays. It resembles T. trun-
catum in form, but is smaller, and has no
radiating veins.

T. alternans (Bai.). — Sides straight,
angles obtuse, granulated like tlie hexa-
gonal centre. SBD. i. p. 26, pi. 5. f. 45.
Common, recent and fossil. England,
United States guano, (vi. 21.) Front
view quadi'ate, not constricted ; the
angles not prolonged into processes.

T. tristilcum (Bai. MS.). — Sides very
concave ; angles broadly rounded, sepa-
rated from centre by transverse lines;
granules crowded and very minute at
angles, elsewhere few, large, and scat-
tered, (vm. 27.) From a drawing by
Professor Bailey. Gulf-sti-eam shells,
W. Indies. This species may be kno\\Ti
by its distant granides.

T. castellatum (W^est). — Sides of the
frustule deepljf concave ; angles forming
segments of circles. Valves with con-
cave sides and roimded angles, fonning
dome-shaped eminences; sm-face punc-
tate, with a single row of larger puncta
along the opposed mai'gins. West, TMS.
■viii. p. 148, pi. 7. f. 3. Barbadoes deposit,
(vin. 29.)

T. Johnsoni (Ralfs, n.s.). — Valves with
roimded angles and concave sides, sur-
face with scattered granules, and a large

granidated space at the angles, separated
y a transverse smooth band ; mardn
witli a few short lines. Barbadoes de-
posit. Johnson. ^'^alves large, \vith
conspicuous granides, which are few at
the centre, and more numerous near the
margin ; each side \x\t\i a few short striiB
lilce those figured by Mr. Brightwell in
T. tahelhirium, but the margin itself is
not undulated.

T. umbilicatum (Ridfs, n.s.). —Valves

or THE ANGULaJi'iilUiiK.

b56

with broadly rounded angles and deeply
sinuated sides, triaugidai" smooth um-
bilicus, radiant series of close granides,
and a large punctate space at each an-
gle. Barbadoes deposit. Johnson. This
large and beautiful species is distin-
giushed by the sinuated sides and tri-
ano^idai- umbilicus of the valves. Gra-
nules conspicuous and dense, appearing
both radiant and concenti-ic. The large
angles ai-e separated by indistinct trans-
verse lines, and appear smooth or granu-
lated according as they are more or less
in focus, and they have a central roimd
spot (probably a process) and sti'iated
margin. This species differs from T.
castellatum in a distinctly radiant ar-
rangement of the granides and a smooth
umbilicus.

T. mef/asto7num (E.). — Sides straight;
angles obtuse, with pseudo-nodules, and
sepai'ated by transverse lines from the
hexagonal centre. EM. pi. 35. In guano.
Small,.somewhat resembling T.i26'<icMZ«<m,
but dift'ering in its pseudo-nodides and
hexagonal centre.

4* Sides in lateral view (jihboiis or un-
dulate (cim/les without pseudo-nodules;
cellules minute).

T. undulatum (E.). — Sides slightly
convex, undulated ; granides minute,
radiating. Br MJ. i. p. 250, pi. 4. f. 13 ;
ERBA. 1840, p. 273. Fossil. Bermuda
and Virginian deposits.

T. Bri(/Uwellii (West). — Sides of
valves undulate, slightly convex, or
straight; granules minute, radiating
from the centre, from vsrhich proceeds a
spine of considerable length ; margin of
valve closely set with short spines. = T.
undulatum, Br MJ. vi. p. 154, pi. 8.
f. 1-5, 8 ; West, TMS. viii. p. 149, pi. 7.
f. 6. Var. /3 with 4 angles. In Noctilucfe.
England. The discovery of this and the
follomng species in a living state has
explained the appearance of the central
pseudo-nodide, .which has proved to be
the remains of a long horn or spine.

T. intricatum (West). — Sides of valves
undulate ; angle acute and slightly pro-
duced ; centre tumid ; granules in hues,
radiating from the centre, scarcely dis-
cernible ; pseudo-nodule apparent. = T.
striolatum V, SBD. i. p. 27, pi. 5. f. 46 ; T.
undulatum, Bri. I. c. ; West, TMS. viii.
p. 148, pi. 7. f. 5. This species in its
living state forms short filaments united
in a distant series.

'r. utriolutum (E.). — Sides convex,
slightly undulated; angles attenuated,
ending in minute papillte. KB, t. 18.

f. 10. = T. membranaceum, Br M J. i. pi. 4.
f. 15. Thames mud, Cuxhaven. Walls
of the frustide extremely delicate, dotted
over with very minute cellules.

T. Parmula (Br.). — Sides gibbous,
with produced mammiform angles ; sur-
face minutely pimctated. Br MJ. iv.
p. 275, pi. 17. f. 2. Natal. Var. ^ with
4 angles. West, TMS. viii. p. 147, pi. 7.
f. 1. FiTistides minute, in outline re-
sembling a shield.

T. Americana. — Sides convex, slightly
imdulated ; angles rounded ; cellides
minute. = T. Amhlyoceros ?, Br M J. i.
p. 250, pi. 4. f. 14. Fossil. Richmond,
Virginia. The rounded angles without
appendages distinguish this species fi'om
the others in this section.

T. marf/aritaceum (Ralfs, n. s.). —
Valves with roimded angles, and straight
or slightly convex sides ; surface with
conspicuous pearly granules, which are
scattered at a triradiate centi-al space,
and aiTanged in radiating lines at the
margin. Barbadoes deposit. Johnson.
The valve is bordered by a row of larger
granides ; and oTily a narrow inconspicu-
ous tenninal portion of the angles appears
smooth.

T. gibbosum (Harv. & Bail.). — "Almost
inflato-globose, the sides very convex,
angles prominent ; smface marked as in
T. concavum." Small. Proc. of Acad,
of Nat. Sci. Philadelphia, 1853. Tahiti,

5* Frustules not spinous, sulcate, veined,
nor undidate.

t Cellules large, hexagonal.

_T. Faviis (E.). — Sides straight or
slightly convex; angles obtuse, \vith
horn-like processes; surface reticidated
with large hexagonal cellules, (xi. 43,
44.)= T. me(iasto7num,lix'^U. i. pl.4. f.7?;
T. Jimbriatum, Wallich MJ. vi. p. 247,
pi. 12. f. 4-9. Recent and fossil, not
uncommon. Diani. 1-200" to 1-150".
Front view ^vith the central jiortion mi-
nutely pimctated, the lateral portions
scarcely constricted beneath the short
stout processes. Mr. Brightwell figures
a quadrilateral form of this species with
concave sides.

T. serratum (Wallich). — Valves (qua-
drilateral) furnished with a horn-like
process at each angle, and from 4 to 6
elongated scattered spines, with furcate
apices ; sides or plates of connecting zone
joined by dovetailed margins. Wallich
MJ. vi. p. 243. pi. 12. f. 1-3. St. Helena!
Connecting zone ii-s well as valves marked
with a delicate but well-detuied lioxa-

856

SYSTEMATIC HISTOKY

OF THE DfFUSOBlA.

gonal areolation. This species is re-
niai'kable cliiefly for the peculiar stmc-
tuvc of its conuecting zone, the plates
having their communicating margins
serrated so as to fit into each other.

T. grande (Br.). — Sides convex ;
angles attenuated, obtuse; hexagonal
cellules numerous. Diam. 1-100". Br
MJ. i. p. 249, pi. 4. f. 8. T. orientale,
Harv. & Bail. I. c. Indian Seas, Min-
danao. " The largest and stoutest spe-
cies of this genus " (Br.). The descrip-
tions do not suffice to distinguish this
species from large specimens of T. Faints.

T. mtiricaturn (Br.). — Sides sti'aight ;
angles ending in a stout hom-like pro-
cess ; cellules large, hexagonal. Br M J. i.
p. 249, pi. 4. i. 5. From the cleanings of
shells. A minute species, distinguished
by its pointed angles. Front view nearly
square, with the central portion smooth,
and the lateral ones tui'gid between the
prominent processes.

T. ocellatimi (E.). — Sides slightly con-
cave ; angles attenuated, obtuse ; cellules
imequal, large, hexagonal in the centre,
gradually becoming smaller at the sides,
m no distinct order. KSA. p. 141.
Mouth of River Tenasserim, India.

2t Lateral surfaces with three pseudo-
nuclei, not situated at the angles.

T. sculptii7n (Sh.). — Sides sti-aight;
angles prolonged into conical points;
granules scattered ; siuface with three
circular pseudo-nuclei, one opposite the
middle of each side. Sh MT. ii. pi. 1.
f. 4. Natal. In form this species some-
what resembles T. acutum; but its pseudo-
nuclei are eminently chai-acteristic.

8t Frustules triradiate, with very
concave sides.

T. Soleiioceros (E.). — Triradiate, with
deeply concave sides; angles prolonged
into long, linear, obtuse arms; ceUides
radiating. Br MJ. i. p. 248, pi. 4. f 1.
Bermuda earth, (vi. 15.) This species
differs from every other by its longlineaa-
rays, which have neither pseudo-nodules
nor processes.

T. Pileus (E.). — Somewhat triradiate,
with very concave sides ; angles tapering,
obtuse, with pseudo-nodules ; celhiles
minute, radiating. EM. pi. 19. f. 18. = T.
brcwhiolatuni, Br MJ. i. pi. 4. f. 2. Fossil,
Greece ; recent, New Zealand. Mr.
Brightwell refers his T. brachiolatum to
the next species.

T. Pileohis (E.). — Somewhat trira-
diate, with very concave sides ; nnglcf j

produced, obtuse, with pseudo-nodules ;
cellules small, scattered. EM. pi. 35 a.
21. f 17. = r. obtumm, Br MJ. iy.
p. 251, pi. 4. f 20. Antarctic Ocean.
Kesembles T. Pileus in form, but is
smaller, and its cellules are scattered.

4t Frustules not triradiate; angles with
pseudo-nodules, or minutely punc-
tated.

T. concamim (Harv. & Bail.). — Sides
very concave ; angles rounded, minutely
pmictated ; cellules of centi'e arranged
m simple and forked radiating lines.
H. & B., Trans, of Acad, of Philadelphia,
1853. Tahiti.

T. Wallichii (Ralfs). — Valves with
minute radiate areolation, a row of mar-
ginal puncta, and a minute horn-like
process at each angle. = T. punctatum,
Wallich, TMS. ^dii. p. 48, pi. 2. t 21.
India, Atlantic.

T. arctiaim (Bri.). — Valves with
slightly convex or straight sides ; areo-
lations small, but distinct, radiating in
lines from the centre, and becoming mi-
nute at the angles, which are rounded
and slightly inflate d.= T. Wilkesii, var,
/3, with 4 angles ; Amphitetras Wllkesii,
Bri MJ. i. p. 250, pi. 4. f 11; Ro TMS.
viii. p. 58. Beechey Island, Ai'ctic
Regions; Buret's Sound, Vancouver's
Island ; and Monteiy stone. The speci-
mens obtained from Vancouver's Island
have proved that Triceratium has been
erroneously considered a free foim, and
that its proper position is with Amphi-
teti'as and Biddulphia; the specimens
alluded to show it attached to Zoo-
phytes, and the frustules connected at
the angles by a short stipes or cushion,
exactly like Amphitetras.

T. Montereyii (Br.). — Sides concave ;
angles roimded, with pseudo-nodides ;
cellides minute, largest in the centre,
which is much inflated. Br M.!. i. p. 251,
pi. 4. i. 8. Fossil. Monterey Bay. This
species is easily distinguished from T.
arctictim by its central boss and larger
cellules.

T. punctatum (Br.). — Sides straight ;
cellules large, pimcta-like, scattered,
smaller at the rounded angles. BrMJ.
iv. p. 275, pi. 17. f. 18. Arctic Regions.
(VI. 20.)

5t Angles without pseudo-nodules.

T. forvwstim (Br.). — Sides slightly
conca\ e ; angles obtuse, wnthout pseudo-
nodules ; ceUides verv minute, somewhat
radiating. Br MJ. i." p. 250, pi. 4. f. 10.
Shell cleanings from //7>;w/>iM maculatus.

OF Tire ANGULITEHEiE.

857

Mr. Briglitwell finds this species varying,
with foui' and five angles. The front
view is quadi-ate, not constricted, the
angles produced into conical processes,
between which the margin is nearly
sbraight.

T. condecorum (E.). — Sides straight
or slightly convex, with obtuse angles ;
cellules very minute, diverging in curved
series. Br MJ. i. p. 250, pi. 4. f. 12.
Fossil. Bermuda.

T. obtimim (E.). — Sides very convex;
angles rounded, mthout pseudo-nodules ;
cellules circulai", scattered. EM. pi. 18.
f. 48, 49. Virginia.

T. Amblyoceros (E.). — Sides concave ;
angles broadly rounded, without pseudo-
nodules ; cellules minute, somewhat
radiating. EM. pi. 18. f. 51. Virginia.
This species has more rounded angles
and smaller cellules than T. ohtimim.

T. Reticulum (E.). — Sides straight;
angles subacute, without pseudo-nodules ;
ceUides minute, numerous. EM. pi. 18.
f. 50. Fossil, America; recent fi'om
ehell-cleaniags. Front view with a nar-
row, smooth central zone; lateral sm--
faces not constricted beneath the slightly
prominent angles.

T. acutum (E.). — Sides nearly sti-aight;
angles elongated into points ; cellules not
radiating. Br MJ. i. p. 251, pi. 4. f. 16.
Bermuda. T. acutum is somewhat tri-
radiate from its acuminated angles.

Doubtful or itisufficiently known Species.

T. scitulum (Br.). — "A small species,
but varying in size. On some of the
frustules I have reckoned, on an end
view, about 45 cells only ; sides very
slightly convex; angles open. Diam.
1-350"." Br MJ. i. p. 250, pi. 4. f. 9.
Indian Ocean. Varies with foui- sides.
Except in its smaller size, we see not how
this species differs from T. Favus.

T. Africanum (E.). — Sides convex ;
angles rounded; cellules large, in radi-
ating series. EM. pi. 35 b. 19. f, 1,
Recent. West Africa. In form resem-
bles T. obtusiim.

T. com2)tum (E.). — Sides straight, and
having a marginal fringe ; angles pro-

I longed into short, stout spines ; ceUules
large, hexagonal. Ro MX ii. p. 283, f. 2.
England. "The cellular markings are
as large as in T. Favus, and I am rather
doubtful whether it may not be a young
form of that species ; but the length of
the processes, and fringe-like row of cells
at the margin, appear to give it a di-
stinctive character" (Roper).

T. crassum (Sh.). — " Much smaller
than T. contortum. Is characterized by
the reticulations being coarse and in-e-
gidar in form, and the horns very large
as compared with the size of the valve."
Sh. in TMS. ii. p. 15. Natal.

T. hyalinum (Br.). — " Small, ti-ans-
parent, siuface with very minute dots or
cellules ; sides regular and straight."
Br M J. iv. p. 275, pi. 17. f 16. Barbadoes.
= T. Heticulum.

T. arcuaium. — Sh TMS. ii. pi. 1. f. 5.
Natal. The figm-e resembles tnat of T.
Pileus, but without pseudo-nodules. It
is probably, however, the same.

r. exiguum (Sm.). — Tiii'adiate ; angles
elongated into lineai" ti-uncated pro-
cesses ; ceUules very minute, scattered.
SB. ii. p. 87; Br MJ. iv. p. 274, pi. 17.
f. 1. Fresh water. Ormsby, Noifolli.
(VI. 14.)

T. Petitaa-inus (y^sHlAich). — Valves
slightly convex, with 5 angles, with
a short horn at each angle. Sui-face
spinous, divided into compartments by
anastomosing lines or costas, which radi-
ate iiTeg-ularly fi-om the centi'e. Var. /3
with 4 angles, y with 6 angles. Wallich,
MJ. vi. p. 251, pi. 12. f. 10-14. St.
Helena. We scarcely see how this form
differs from Amphitetras ornata of
Shadbolt.

T. dubium (Br.). — Valve minute,
clypeate, with 6 angles, the lower one
much produced; surface of valve coarsely
mmctato. Br MJ. vii. p. 180, pi. 9.
f. 12. Mamitius, Califoruiau guano,
India. " We place this form (which is
not of unfrequent occurrence) provi-
sionally among the Triccratia. It pro-
bably forms the type of a now ffenus "
(Br. ;.r.). °

T. 3£allcus, Br MJ. vi. p. 164, pi. 8.
f. 6. Not Diatomaceous ?

Genus AMPHITETEAS (Ehr.). — Frustiilcs cclliiloso, cubiform, cohering
into a zigzag attached filament ; in lateral view quadrangular, with a pseudo-
opening at each angle. Since Mr. Brightwcll's discoveiy of quadrangular
states of Triceratium, the only remaining distinction between that genus and
the present is, that in this the frustules form catenate attached filaments ;
but, according to Professor Bailey (as ah-eady noticed), even this character is

858

SYSTEMATIC lUSTOflY OF THE INFUSOlilA.

not confined to Amphitetras. Professor Smith, indeed, remarks, " The pro-
jection of the connecting membrane beyond the suture of the valve is a cir-
cumstance which meets us for the first time in Amphitetras ; " but we believe
that tliis occurs in every genus in which the new portions of the di^'iding
frustules are formed within the persistent central portion, and in this respect
there is no perceptible difference between Triceratium and Amphitetras. As
some species have been placed in Amphitetras solely on account of their
quadi-ate form, the con-eetness of their position is consequently not free from
doubt.

Amphitetras antediluviana (E.). —
Lateral view with straight or concave
margins ; angles rounded, each Avith an
appai'ent opening ; cellules large, radiat-
ing, and concenti'ic. Living, Denmark,
England, America, &c. ; fossil, Oran,
Greece. ^xi. 21, 22.) A. tessellata,
Sh TMS. li. j3, sides very concave;
the cellules on the central portion are
smaller, and arranged in longitudinal
lines.

A. Adnatica (K.). — "Lateral view
quadrate; cellides radiating and con-
centric; primary sides plane." KSA.
p. 134. Adriatic Sea.

A. parallela (E.). — Cellules in lateral
view large, an-anged in pai'allel lines.
Fossil. Greece.

A. crucifera (Kitton, n. sp.). — Valves
punctate, and marked by a line passing
from the centre to each angle. Front
view deeply consti'icted on either side of
connecting zone. Valves minute, with
slightly convex sides, and produced
mammiform angles. Cleanings of shells
from West Indies. Distinguished by
the crucifoi-m lines of the valve, which
taper from the centre to the angles,

where they tenninate in points. We
have seen 4 or 5 frustules connected by
the angles.

Doiibtftd or imperfectly known Si)ecics.

A. 07-nata (Sh.). — "Size small, mar-
gins concave, and folded so that each
valve is not unlike iu form to a col-
legian's cap ; surface somewhat m-egu-
larly ornamented with delicate vein-like
markings." TMS. ii. p. 16, pi. 1. f. 10.
Natal. Var. /3, with 5 angles, (vm. 16.)
This is probably a state of some veined
species of Triceratiiun.

A. favosa (Harv. & BaU.). — " Sides
scarcely concave ; lateral view quadi-au-
gulai- ; angles almost straight, scarcely
produced ; surface tessellated with large
hexagonal cellules." Proc. of Acad, of
Philadelphia, 185.3. Mindanao.

A. Crux (Bri.). — Valves crucifonn,
with the angles widely roimded ; smface
coarsely pmictate. Cleanings from shells,
West Indies; Californian guano. Bri
JIMS. vii. p. 181, pi. 9. f. 13.' This may
be a 4-angled var. of Tnceratunn casicl-
latum or T. trisulcuin.

Genus AMPHIPENTAS (Ehr.).— Frustules fi-ee, simple, cellulose or gra-
nulate, pentagonal. Probably pentagonal forms of Triceratium.

Amphipentas altei'nans (E.). — Sides
concave ; angles obtuse ; the angles of
the external pentagon alternating with
those of a smaller central one, which has
a circular umbo at its middle. I^A.
p. 134 ; EA. p. 122, pi. 2. 6. f. 9. Cuba.
(XI. 32.)

A. Pentacrinus (E.). — Pentagonal ; its
dorsal surface presenting a striated ring.
Diam. 1-240". KA. p. 134. Fossil.
Greece. Fragments like Amphitetras.

K.Jlcxuosa (B. MS.). — Sides four or
five, gibbous ; angles conical ; sm-faco
flat; cellules hexagonal, covered by
minute puncta. Gulf-stream, (vi. 22.)
From drawings b}' Professor Bailey,
"Under a low power, the markings
appear circular, as represented in the
figures" (B.). The margins are imdidatcd
ui consequence of their gibbous projec-
tions, as in Triceratium Parmula, and may
be 4- and 5-angled forms of that species.

FAMILY XII.— TERPSINOE^.

FiTistules quadrangular, smooth, compressed, fiunishcd wii\\ unequal trans- •
verse costse or incomplete septa interrupted at the middle. We have scpa- ■
rated tliis small group from Striatelleie because, notwithstanding the groat t

OV THE TERPSINOEiE.

859

external resemblance of their solitary finistules, we believe them to differ
essentially in structure. In StriatelleJB the septa are longitudinal, and divide
the central portion into chambers. In Terpsinoeae they are transverse and
confined to the lateral portions, which appear in the front view as in Biddul-
phiese. The relation of TerpsinoesB to the latter was pointed out by Mene-
ghini. The smooth frustules and straight lateral margins without processes
distinguish the Terpsinoeae.

Genus ANAULUS (Ehr.). — rrastules simple, subquadrate, smooth ; septa
lateral, unequal, not thickened at their extremities; lateral view oblong.
Anaulus resembles Biddulphia, but its costse or septa are imequal, and it has
no tubular processes. A genus of Mollusks has been also, but more recently,
called Anaulus.

Anaultjs scalaris (E.). — Tm-gid in
the yoimg state; but when full-gTown
very wide and much flattened, having
4, 6, 8, or 14 lateral constrictions ; late-
rally oblong with transverse bars, giving
it a ladder-like appearance. EM. pi. 35 a.
22. f. 1, 2. Antarctic Sea. Diam. 1-480"
to 1-180". The lateral valves, in the
front view, have imdulated margins.

caused by the constrictions, (vm. 37.)

A. Cmnpylodiscus (E.). — Quadrangu-
lar ; each valve very much compressed,
triangular, with obtuse angles, and hav-
ing laterally two slight constrictions.
Berniuda. Diam. 1-372". It has the
habit of an unequal-sided Triceratium or
of a Campylodiscus.

Genus TERPSINOE (Ehr.). — Enistules concatenate; costffi unequal, capi-
tate, curved so as to resemble musical notes. " If we imagine a series of
frustules of Tabellaria joined together, not laterally, but the head of one to
that of another, or in the direction of breadth instead of length, we shall
form the most just idea of this genus " (Ehr.). The capitate costfe, which
in their form so greatly resemble musical notes, distinguish Terpsinoe from
every other genus.

We unite Tetragramma with Terpsinoe, as Professor Bailey finds the
" music-like notes" vary in number from two to at least eight on a side
and does not consider their number even specifically important. '

the costffi resemble notes of music, but
are confined to the central compartments
of the valves. In the lateral view it
resembles the preceding species, but has
tewer cross-bars.

T. Indica (E., Kiitz.). — Frustides
subquadi-ate (catenated?), compressed
two or fom- times constricted; lateral
valves densely gi-anidate, central portion
smooth, with two puncta at each end •
median costaj dilated at tlie end. KSa!
p. 119. = Anaulus Indicus, E. ludia*
ireq^uent. '

1. Jnvanensis TEM. pi. 34. 8. f. IG).

The figure resembles T. musica ; "but the
central portion is mariced by longitudi-
nal lines, which converge at each end.

Tebpsinoe musica (E.). — Frustides
finely punctated, with two or three trans-
verse Dands, the lateral valves having
costse in each division ; lateral view ob-
long, showing two or three inflations and
narrower rounded ends. EA. pi. 3. 4. f. 1 ;
Rab D. 1. 10. America, Africa, (xi. 47.)
Frustules with finely punctated lateral
portions, between which the central zone
(having two puncta at each end) appears
like a band. Two or three bars cross
lateral and central portions from one
lateral margin to the other, and divide
them obscurely into compartments. The
lateral view has the margins sinuated,
from constrictions coiTesponding with
the transverse bands.

T. Americana (Bailey). — Fi-ustules
quadrangidar, resembling those of T.
musica, but smaller, more minutely punc-
tate, with two transverse bars and two
costfe in each lateral valve. = Teira-
(/ramina Americana, Bail. Smitlisonian
Contr. 1853, p. 7. f. 1. A3 in T. musica,

Species knoum to tts only by name.

T. Asiatica, As.\a. = Tetrayratnma Asi-
atica, E.

T. Japonica (E.), Japan.

T. Austrahs (I'l), Sandwich Islands.

860

SYSTEMATIC HISTOllY OF THE INFUSOiilA.

T. Libyca = Tetragramma Libyctwi,
Africa.

T. Brasiliensis (E.). — Music-like marks

very small. Accordiug to Ehrenberg, it
approaches T. musica iu form. Brazil.

m

Geniis PLEURODESMIUM (Kiitz.). — Fnistules compressed, connected
fascia-like filaments by short thread-like processes ; lateral portions
punctated and furnished with music-like marks, the hyaline central smoother
portion forming a band between them.

Althoixgh Pleui-odesmium was placed by Professor Klitzing in a different
family from Terpsinoe, yet these genera appeared to us so closely allied that
we found it difficult to distinguish them, — a difficulty experienced also by
Mr. Tuffen West on examining an authentic specimen of Pleurodesmium
given us by our valued friend M. de Brebisson, which, however, was imfor-
tunately not in a condition to afford a satisfactory examination.

The frustules, as in Terpsinoe, agree with the Biddulphieae La having the
lateral valves largely developed and entering into the front view ; they are
furnished with costse, enlarged at the ends and resembling notes of music,
M. de Brebisson thinks this genus very distinct, the frustules being connected
in straight series by thread-like points of attachment proceeding from the
furrows ; but these he informs us are very short indeed, for which reason
Kiitzing, like ourselves, seems to h.ave overlooked them.

PLEUEODEsrauM £rebissotiu (Kiitz.).
Frustules contracted at theu'j miction ;

KSA. p. 115. Cayenne.

costffi iTigose

(vi. 23.) Lateral view oval, ha^-ing
transverse bai'S and undulated sides.

Genus EUJSTOTOGRAMMA (Weisse). — Front view as in Anaulus ; lateral
view lunate, with undulated dorsal and ventral margins. Dr. Weisse observes
that in the front view Eunotogramma resembles Gomphogramma, and in the
lateral one Eunotia (Epithemia ?). In both instances, however, the resem-
blance is evidently very superficial, and does not require the distinctions to
be pointed out. The genus doubtless belongs to the Tei'psinoeae, and seems
to differ from Anaulus only in the lunate form of the side view.

row connecting zone, and lateral, equal,
stout, pinna-like septa. Lateral view
semilanceolate, cousti-ieted at each sep-

EuNOTOGBAMMA tn- qumque- septem-
et novetnloculata (W eisse). — Lateral view
divided by two, four, six, or eight ti-ans-

verse septa into three, five, seven, or
nine loculi. Weisse, Bulletin de I'Acad.
de St. P(5tersbour»^ xiii. p. 278, t. 3. f. 37.
Fossil. Kussia. Front view with a nar-

tum, and therefore having as many
imdulations as loculi; ends rounded,
(vin. 30.)

FAMILY XIII.— CHJSTOCEREiE.

Frustules smooth or faintly punctated, simple or imited into awned fila-
ments ; lateral valves, in the nonfilamentous forms, usually unequal, inflated,
lobed, and often furnished with bristles or other appendages ; lateral view
oval or circular. Marine, mostly fossil. Until JIi-. BrightwcU pointed out
their true afiinity, the genera included in this group were distributed amongst
tkreo families. Between Syndendi-ium and the i^Jiguliferea; we can perceive
no resemblance ; but the connexion of Chajtoceros -with the Biddulphieas, and
the other genera with the Melosii'ccc, is far more plausible. In Stepliano-
pyxis, a true member of th.e latter family, the valves are crowned with
bristles or spines, as in some Cha^tocerea!. In Melosirenc, however, all the
members ought to be cylindiical, whereas in tliis family the shape, in the
lateral view, is much oftoner oval than cii'cidar. Althougli it is not difficult
to point out differences between the Chostocereic and other groujis, yet, on

or THE Cn^TOCEIlEiE.

861

account of the variety in their forms, we confess oui- inability, in the present
state of oiu- knowledge, to give a concise definition which shaU include its
own members and exclude all others. We shall therefore content oui-selyes
with pointing out those characters which will enable us to recognize with
tolerable certainty those Diatoms which belong to it. The filamentous species
differ by their awns so much from eveiy other genus that they cannot be
mistaken. Mr. Brightwell, in his excellent paper on Chastoceros, regards
this as the typal state: he says, "A careful examination of most of the
species of Chfetoceros and other allied genera, described by Ehi-enberg as
found ia a fossil state, have satisfied us that most, if not all these, will, when
foimd in a living state, turn out to belong to the singular filamentous and
horned group which may for the present be comprehended in the genus
Chaetoceros." Those forms also which have dissimHar-shaped valves, espe-
cially when lobed or hirsute, may be safely placed here ; and it is very pro-
bable that some species with unequal valves, still retained in MelosirejB,
might likewise be included Avith propriety.

The genera themselves are by no means fii-mly established ; for, as Mr.
Brightwell observes, " most of the described species have been found only in
a fossn, or rather, if we may so term it, a deposit state ; and in this state it
is clearly difficult to form a correct idea of either species or genera, since
deposits give no information as to the Diatoms being in threads or solitary
frustules." We shall not attempt to reconstruct the genera, for to do so
prematurely would only increase the difficulty and cause confusion; for
" much must yet be brought to light before a satisfactory classification of this
group can be effected " (Brightwell). Although only a few species have as
yet been gathered in a living state, yet, as most of them are foimd in g-uano,
it is probable that nearly all stiU exist ; and when their habits are better
known, we may fairly expect to obtain them. They seem to inhabit deep
water, as Mr. Norman has met with them, more than once, in the stomachs
of Ascidise from such situations.

Genus CBLETOCEEOS (Ehr.).— Fnistules without strise, united with the
adjacent ones by the interlaciag on each side of awns proceeding fi-om the
frustule or from a cingulum between the frustules, and so forming a filament.
The filaments are imperfectly sUicious and veiy fi-agile. The awns ai-e tubular,
sometimes spinous or serrated, and often of great length, thoiigh, according

to Kiitziug, short in an early state. Kiitzing defines the genus as follows :

" Frustules concatenated, equally bivalved, turgid, with two apertures on
each side, which at the earliest period are veiy shortly tubular and the cor-
puscles contiguous, afterwards longly awaed and the coiiniscles distant."
If the awns be overlooked or broken off, the frustules may be mistaken for
species of Melosii'a. No person who wishes to study this beautiful but diffi-
cult genus should fail to obtain Mr. Brightwell's valuable paper on it in the
Journal of Microscopic Science.

. * Frustules, iw lateral vieto, consincted at
the middle.

CHiETOCEBOS Diploneis (E.). — Fnis-
tiiles in lateral view pandurifonu, in
front view linear ; awns smooth. KSA.
p. 138 ; EM. pi. 33. 18. f. 1 ; Bai. in Amor,
.fourn. of Science, xlviii. pi. 4. f. 19 (la-
teral view). = C. Bacillariu, Bai. I. c. f. 18
(front view). Bermuda deposit. " Clm-
toceros Diploneis and C. Bacillnria arc
merely different positions of the same

species (J3ai. m lit.). In the front view
tlie frustules are linear, lliroo or four
times a.9 long as broad, with stout awus
arising from the angles. Lateral view
pandiu-iform, with roimded ends.

2 * Fnistules lateral/;/ oval or circular ;
awtis sjv'nous.

0. Soreafc (Bail.).— Frustules quadrate ;
awns very long, spinous, arising fi-om
tlie inner surface, not from the andos
BC. 1864, pi. 7. f. 22, 23; Bri JlklS iv.

862

STSTEMATIC HISTOBT OF THE nTPUSOElA.

p. 107, pi. 7. f. 12-15 ; Wallich, TMS. viii.
p. 48, pi. 2. f. 18 ; West, TMS. viii. p. 152,
pi. 7. f. 13. St. George's Bank, Atlantic
Ocean, (vi. 25.) " This species was
found in considerable numbers in the
contents of the stomach of the Botryo-
dactyla granclis." Awns 30 to 50 times
longer than the body.

C. Peruvianum (Bri.). — Valves hemi-
spherical, vdth two very stout, long,
recurved, spinous awns proceeding from
the centre of the rounded ends. Br JMS.
iv. p. 107, 1 16-18. In Peruvian guano.
A remarkable and very distinct species,
characterized by the roimded apex of
the valve. Lateral view circular P

3 * Frmtules laterally oval or circular ;
mo)7S smooth.

C. Tetrachata (E.). — Frustules with
foui', very long, filifomi, smooth awns on
each side. KSA. p. 138. Antarctic Sea.
Diam. without the a^vns, 1-1152".

C. DichcBta (E.). — Frustules with two,
Very long, filifomi, smooth, often flexu-
oae awns on each side. KSA. p. 138.
Antarctic Sea. Diam. without the awns,
1-1152" to 1-720". The description is
too imperfect to enable us to distin-
guish the species from some of the fol-
lowing ones.

0. confervoidcs (n. sp.). — Frustules
large, quadrate ; awns stout, smooth,
arising a little beneath the roimded
angles; lateral view circular. Motmt's
Bay (stomach of Ascidise), Cornwall.
We have seen only one concatenated
specimen; it formed a short, very fi-a-
gile, conferva-like filament of about 12
joints, which were equal in length and
breadth and in close apposition. Internal
colouring matter brownish, and collapsed
into a roundish spot in the centre of
each frustiile.

C. Wighamil (Bri.). — " Frustules cup-
shaped, with a band round the mouth of
the cup, and a neck or bulb proceeding
from the centre ; beset with minute short
spines or papiUse in all parts except the
band; lateral view oval; awns elon-
gated, smooth." Br MJ. iv. p. 108, pi. 7.
f. 19-36. In brackish water, near Brey-
don. Great Yamiouth. " Boiled in acid,
the filaments brealc up, and the frustides
in an isolated state, and detached rings
with the horns proceeding from them,
arc all thnt can be detected. The rings
may readily bo distinguished from the
frustules seen endwise, as they are open
and without dots, while the fruslulos
seen endwise are dotted " (Bri.). • Wc

have seen no perfect specimen of this
interesting species ; but as Mr. Bright-
well's fig. 12 shows two joints similar
to other species of this genus, we are
inclined to regard the Goniothecia-like
bodies as internal cells, of the same
nature as the internal cells of Himan-
tidium, Meridion, &c., which we believe
to be sporangia; but whatever their
true character may be, we have scarcely
a doubt that Mr. BrightweU is right in
supposing Goniothecium crenatum, G. his-
pidum, G. Navieula, and G. barhatum to
be allied forms belonging to the same
genus as this species, (xi. 24.)

0. incurvum (BaU.). — Frustules in
front view linear, with smooth, filiform,
recm'ved awns arising from the angles ;
lateral view oval. Bri. I. c. pi. 7. f. 9-11.
Fossil. Virginia, Peruvian guano. In
stomach of Ascidise, Penzance. Easily
known by its small size and slender
recm'ved awns.

G. furcillatum (Bail.). — Awns of ad-
joining frustules closely approximate
below, then diverging and Decoming
nearly parallel ; lateral view oral. Bai.
on Microsc. Forms in the Sea of Kamt-
schatka, p. 3, pi. 1. f 4. Common in the
Sea of Kamtschatka. The minutest spe-
cies in the genus.

C. didymus (E.). — Fi-ustules longer
than broad, gibbous or angular on the
outer margin, and usually slightly so on
the inner mai-gin also; awns smooth,
filifoiTO, arising from the angles. Bri.
I. c. pi. 7. £ 3-7 ; KSA. p. 138 ; EM. t. 35 a.
18. f. 4. Common in Peruvian guano.
Stomach of Ascidife, Penzance. A va-
riable species, distinguished by its angu-
lar or gibbous margins ; lateral view
oval. Ehrenberg's two figures in the
'Microgeologie' differ fi-om each other,
as well as from any specimens we hare
seen. Greatest diameter 1-1080".

C. Gastridium (E., Bri.). — Frustules
binate, smooth, transversely oblong,
truncated at each end, abruptly dilated
at the middle of the venti-al surface, not
contiguous, Bri. I. c. pi. 7. f. 8. = Gonio-
thecium Gastridium, EISI. pi. 18. f. 91.
Virginian guano. Elirenberg descinbes
and figures it with an external umbo
(gibbous), thus approaching to C. didy-
mus.

C. armatum (West). — Frustules qua-
di'angiilar, forming a compressed fila-
ment ; angles excavated ; from each an^le
arises a long, obtuse, cui-ved seta, with
several acute ones at tlie base. Vs^est,
TMS. viii. p. 151, pi. 7. f. 12. Abundant
on various parts of the roast of England.

or THE CHiETOCEREiE.

863

Tlii3 species, in its living state, is in- stance which has caused many douhts
vested with a mucous covering, and is as to its diatomaceous nature,
scarcely, if at all, silicious, — a circvmi-

Genus ATTHEYA (West). — Frustules compressed, annulate ; annuli inde-
finite ; valve elliptical-lanceolate, with a median line ; angles spinous. The
true position of this genus is doubtful ; but, from examination, it appears to
approach nearer to ChsEtoceros than to any other genus excepting Striatella,
from which, however, it is easily distinguished by the spinous angles and ab-
sence of stipes.

Attheya decora (West). — Annuli 12
to 28 ; septa alternate ; valve with me-
dian line and centi-al nodule. West,

TMS. viii. p. 152, pi. 7. f. 15. Cresswell
Sands, Drm-idge Bay. (vm. 35.)

Genus BACTEHIASTRUM (Shadbolt).— Frustules avmed, united into a
jointed, conferva-like, cylindrical filament; valves discoidal, with marginal
radiating awns. Bacteriastram agrees with Chaetoceros in its filamentous
character and in the presence of awns, but differs from it in having the awns
of its discoidal valves marginal and radiant. Marine. Stomachs of marine
animals, &c.

Bacteriastrum furcatiim (Sh.). —
Awns smooth, much elongated, forked.
=Actmisnis sexfurcatus, ERBA. 1854,
p. 237 ; EM. pi. 35 b. 4. f. 15 ; A. bisepte-
narius, E. ; A. hisoctonariiis, E. Atlantic.
The awns vary in number and in the
length of the forked portions, (vi. 26.)

B. curvatum (Sh.). — Awns simple,
elongated, smooth, symmetrically cuiTed
in one direction.

B. Wallicliii (EaUs). — Valves more or
less cup-shaped, with 4 to 12 smooth,
simple, divergent awns. = Cluetoceros
Bacteiiastrum, WaEich, TMS. viii. p. 48,
pi. 2. f. 16, 17. Atlantic. From Salp^,
Size extremely variable, (vi. 27.)

B. nodulomm (Sh.). — Awns simple,
straight, roiigh. — Awns covered with
small protuberances, like a imobbed
stick..

Genus DICLADIA (Ehr.). — Frustules simple, one-celled, bivalved ; valves
unequal, turgid, one mostly simple and unarmed, the other two-homed ;
horns sometimes branched.

DiCLADiA Capreolus (E.). — One valve
with two stjdes arising from conical
ba°es, and usually branched at the end.
EM. pi. 35 A. 17. f. 8 ; Bri JMS. iv. pi. 7.
f. 53-60. Virginia. Common in guano.
The frustule consists of a narrow-linear
central portion, projecting at each end,
and two tm'gid lateral valves, which
vary greatly in foi-m. Usually the in-
ferior one is smaller, simple, and unarmed,
but is often bilobed. The larger valve is
bilobed ; the lobes mammifonn or conical,
each terminating in a style divided at its
apex; occasionally, however, specimens
have the upper vnlve unarmed or simple.

D. antcnnata (E.). — One valve, with
two simple, setaceous, parallel, acute
spines, articulated at the base, like an-
tennsB ; the other valve unlniown. EM.
1.1. 35 A. 21. f 9 ; KSA. p. 24. Antarctic
'Sea. This and the next species were
constituted from single fragments.

I), bulhom (E.). — One valve with two
spines, which are divergent at tlie base.

connivent above, bidbose and slightly
sulcate in the middle part; the other
valve unliuown. EM. pi. 35 A. 21. f. 10 ;
KSA. p. 24. Antarctic Sea.

D. clathrata (E.). — Frustule with a
rounded, smooth, latticed body, and two
unequal frontal horns. EM. pi. 18. f 100 ;
KSA. p. 25. Fossil. Vir ffinia.

_D. Capra (E,.). — Smooth; one valve
with two simple spines, the otlier uni-
dentate or imperfectly sub-bidentate in
tlie middle ; centi'al portion naiTow-
Hnear. EM. pi. 18. f 99. = Penptera
Capm, KSA. p. 26. Fossil. Virginia.

I). Cervus (E.). — Smooth, large ;
frontal horns long, branched. = Pt'r(^<t')-a
Cervus, KSA. p. 20. Fossil. INIaryland.

I). 3Iitra (Bai.).— Valve having two
conical boms coalescing below into a
conical base, and bearing branclied pro-
cesses above. B. in Silliman's Anier.
Jouru. July 1856, pi. 1. f. 6. Sea of
Kamtschatlm. Perhaps a state of D.
Cnprenlus,

8G4

SYSTEMATIC HISTOHY OF THE INFUSOniA.

Gonus GOlSriOTHECIUM (E.).— Frustulcs simple, having a central con-
striction or furrow ; each end abruptly attenuate and truncate, so as to assume
an angular iigure. Fossil. Like other genera in this family, this is an un-
satisfactory genus. The fnistules are described as cylindrical; but we believe
that most, if not all of them, are oval when viewed laterally, Mr. Brightwell
makes the following remarks on eight of Ehrenberg's species : — " The two
largest and most common ai'e Q. Rogersii and G. Oclontella ; and we think it
probable these will turn out, if discovered in a recent or living state, to be
Chajtoceri, Of the remaining six species, we are led to conclude, from the
discovery of the Breydon species, that two of them belong to the genus
Chastoeeros, and are, when living, filamentous. They are G. Gastndium, of
which we have found many specimens with the horns perfect, and G. crenatum.
A figure of a fi-ustiile of this species is given in the ' Microgeologie ' of Ehren-
berg, and it can scarcely be distinguished from the fnistules of the Breydon
species. Q. hispidum and G. didymum scarcely appear to differ fi-om some of
the smaller fnistules of the Breydon species. G. Navicula and G. barbatum
are clearly allied to G. crenatum, or our Breydon species." The species differ
in form, and sometimes do not correspond with the generic chai-acter. G.
Gastridium (E.) is proved by Mr. BrightweU's discovery of its awns to be a
species of Cheetoceros.

GomOTHECiUM Odontella (E.). —
Valves binate, smooth, conjoined by a
central process, and by then- connivent
apices, so as to form on each side a
lar^e oblong apertm-e, constricted at its
middle ; margin undulate. EM. pi. 33. 15.
f. 16 ; KSA. p. 23 ; Bri JMS. v. pi. 7.
f. 47, 48. Virginia. Diam. 1-480" to
1-276". Distinguished by its large size
and undulated margin, the central un-
dulation forming an umbo ; lateral view
oval. (vi. 29.)

G. Rogersii (E.). — Valves binate,
smooth, conjoined by a broad centi-al
process, often with connivent apices,
ibnning suborbicular apertures ; margin
undulate. EM. pi. 18. f. 92, 93 ; KSA.
p. 23. Virginia. Diam. 1-588". Smaller
than G. Odontella ; " valves dorsaUy sub-
quadrate, angular, with three whorls,
laterally elliptic- oblong, with two or
three median circles; " central undulation
umbonate. Mr. BrightweU's figures are
more in-egular, and do not con-espond so
accurately with the definition.

G. ohtiisum (E.). — Valves smooth, in-
flated, with three rounded lobes ; central
or constricted portion forming a naiTOw
band. EM. pi. 18. f. 95 ; KSA. p. 23.
Virginia. Diam. 1-696".

G. monodon (E.). — Valves binate,
smooth, not contiguous, each linear-
oblong, truncate at each end ; outer side
uniformly straight, the inner with a
median tuberosity. EM. pi. 18. f. 97 ;
KSi\.. p. 23. Virginia, California. Ehr-
cnborg s figures represent a canoe-shaped
valve, the outer margin conve.x, the
inner with incurved ends and a central

projection (connecting process^ and
agrees but badly with the specinc cha-
racter.

G. hispidum (E.). — Fnistules semi-
lunate, hispid, with an umbo at the
centime of inner margLa. EM. pi. 18.
f. 107 ; KSA. p. 23. Virginia.

G. Navicula (E.). — Fnistules small,
smooth, with a linear produced central
portion and a turgid or inflated valve on
each side. EM. pi. 18. f. 105 ; KSA. p. 24.
Virginia. In this species the central
portion projects beyond the lateral valves,
mstead of being constricted.

G. didymum (E.). — Binate, smooth,
transversely oblong, obtuse ; one side
emarginate at the centre, the other with
two tubercles. EM. pi. 18. f. 104 ; KSA.
p. 23. Virginia. Diam. 1-1200". Ehr-
enberg's figure shows two unequal valves
without any interstitial portion, each
valve with two rounded lobes. It re-
sembles a hornless state of Dicladia,
except that it wants the central portion.

G. barbatum, EM. pi. 18. f. 106. Vir-
ginia. Ehrenberg's figm-e has a narrow-
lineai", longly produced central portion
and two imcqual turgid valves — the
smaller smooth, the larger conic \\it)i a
tuft of hairs at its apex.

G. crenatum, EM. pi. 39. 3. f. 74 Ehr-
enberg's figm*e is semilunate, with a
neck-like truncated cone on its inner
side. This species, except in being
smooth, exactly resembles Mr. ]3right-
well's figures of the internal frustules of
Chfttoccros Wighamii, and doubtless be-
longs either to tliat or to an allied .species
of Clia)toceros. (xv. 10.)

OF THE CH-ISTOCERE-IS.

865

Genus OMPHALOTHECA (Ehr.).— Characters unknown to us. Judging
from Ehi-enberg's figure of the only species, it seems scarcely distinct from
Goniothecium.

Omphalotheca Mspida, EM. pi. 35 a.
9. f. 4*. Ganges. The figure apparently
represents a frustule in the process of
division. The valves ai-e unequal; the

smaller one smooth, the larger some-
what conical and fiu'nished with scat-
tered spines ; connecting-zone slightly
produced beyond the valves, (vra. 44.)

Genus PERIPTERA (Ehi\). — Frustules simple, compressed, unequally
bivalved ; valves simple, continuous, not cellulose ; one valve naked, tui'gid,
the other winged or horned ; horns affixed to the extreme margin, sometimes
branched. Approaches very near to Syndendrium and Dicladia. "We think
these three genera might be united with advantage.

P. chlamidophora (E.). — Smooth, al-
most navicular; one valve at the side
plane and smunounted by a finely-nerved
membrane, the other turgid at the mid-
dle, unarmed. EM. pi. 18. f. 96. Fossil.

Peeipteba tetracladia (E.). — Smooth,
almost navicular; one valve with fom-
equidistant spines, branched at the apex,
the other simple. EM. pi. 33. 18. f. 9.
Fossil. Bermuda deposit. Diam. 1-1440",
including spines 1-864". Without the
spines, it resembles an ^Vmphora. (vi. 30.)

Bermuda, (vin. 25.)

Genus RHIZOSOLENIA (Ehr.). — Filamentous ; frustules subcylindrical,
greatly elongated, silicious, annulate ; annuli broadly cimeate ; surface stri-
ated, extremities calyptiiform, pointed with a bristle. This genus was con-
stituted by Ehrenberg for the reception of certain silicious organisms found
in guano and various fossil deposits. The characters assigned by him to this
genus are, " lorica tubular, with one extremity roimd and closed, while the
other is attenuate and multifid, as if terminating in little roots." The dis-
covery of this remarkable genus in a living state has, we believe, proved that
the species described by Ehrenberg are only fragments of forms similar to
those we are about to describe. Professor Schultze has detected in R. styli-
formis and B. calcar-avis a circulation of minute granules analogous to the
currents obseiwed in the hairs on the filaments of Tradescantia procumhens.
(Schultze, MJ. vii. p. 16.)

RmzosoLENiA stylifonnis (Bn.). —
Fnistules from 6 to 20 times as long as
broad ; transverse linps (annuli) distinct ;
surface striated, strise oblique, about 40 in
•001", terminal process at the base spatu-
late and bifid. Found m Noctilucse, Yar-
mouth : stomachs of Ascidians, York-
shire ; Salpse, Atlantic. Bri MJ. vi. p. 94,
pi. 5. f. 5; Norman, ANH. xx. p. 158;
Prof. Schultze, MJ. vii. p. 18. pi. 2. f. 1.
(vii. 32.) From the elongated base of
the calyptriform process a stout line or
rib runs up on either side to nearly tlie
apex of the cone ; at base of the lines a
small horn, slightly curved towards the
anniili, is frequently to be detected.
Self-division has been observed in this
and some of the following species.

li. imbricata (Bri.). — Frustidcs 4 to
7 times as lon^ as broad, annuli di-
■ stinct, surface of valve coarsely punctate,
terminal process subulate, entu'e. Found
> with the preceding species. Bri MJ.

p. 94, pi. 5. f. 6. The dii-ection of the
transverse lines (annuli) and puncta
give this species an imbaicated appear-
ance.

R. setigm-a (Bri.). — Frustules 5 to 15
tiines as lon^ as broad, annidi obscm-e,
strife very taint, terminal bristle fre-
quently as long as the coloiudess frustule.
In Noctilucos, Ascidians, and Salpse.
Bri. I. c. p. 96, pi. 5. f. 7. r\ai. 33.) ITaia
species is remarkable for the great length
of the terminal bristle and its extreme
delicacy.

11. alata (Bri.). — Annuli distinct, strias
faint, toi-mmal process alato, recm-ved,
blunt. In Ascidians, Yorkshire. Bri. I. c.
p. 95, pi. 5. f 8. This curious little spe-
cies is distinguished by its small but
conspicuous sotaj attached to the base of
the calyptriform process.

R. calcar-avis (Schultze). — Frustules
small, annidi indistinct ; tenuinal process
slightly sigmoid, the point resembling

a K

866

SYSTEMATIC HISTOKY OF THE lOTUSOETA.

a bird's claw. Heligoland. Scbultze,
MJ. vii.p. 21, pi. 2. f.5.

R. robusta (Norman, MS.). — Frustules
very broad, sligbtly sigmoid, anniili nar-
row, calyptriform processes with lines
radiating- ti-om the apices ; bristles short,
delicate, nearly linear. Stria? fine, about
55 in -OOl". Ascidians, North Sea,
Teignmouth, Heligoland, Australia,
(vra. 42.)

Doubtful and insitfficiently known Species.

R. Calyptrd (E.). — Valve (tei-minal
process) broadly conico-campanulate,
smooth, its apex attenuated, acute. EM.
pi. 35 A. 22.^ f. 17. ; Bri. I. c. pi. 5. f. 2.
Southern Ocean, (vn. 31.) This is pro-
bably the terminal process of R. styli-
formis.

E,. Campana (E.). — ^Valve large ; apex
conic, longly attenuated, varies as if
temiinated by little roots; sm-face very
finely granulated. KSA. p. 24. Bermuda
deposit.

K. ornitlwglossa (E.). — Valve tubular,
conical, smooth, slender, with a much
attenuated, acute apex, laterally resem-
bling the tongue of a bii'd. EM. pi 33.

13. f. 21. Antarctic Sea.

R. Ainericana. — Frustules smooth,
hyaline, tubular, inten-upted by septa,
one end round, the otner stylifonn,
simple or branched. EM. pi. 18. f. 98.
FossU. America. This seems a .species
very variable in size and fonn. The
outline, however, of the rostrate valve
bears some resemblance to a bottle, with
the neck or beak simple or branched.

R. hehetata (Bai.). — Valve calyptri-
fonn, punctate, with a smooth, cylin-
drical base ; apex expanded, compressed.
B. in SiUiman's Amer. Joum. Julj' 1856,
p. 5, pi. 1. i. 18, 19. Seas of Kamtschatka
and Ochotsk. The expanded apex re-
sembles in outline the flame of a candle.
The punctate conical portions are most
frequently seen ; but specimens with the
cylindrical base are occasionally found,
Bail.

'R.Pileolus (E.). — Valve small, short,
as broad as long ; central portion linear,
produced ; one valve resembling an umbo,
the other conical, bi-anched at apex. EM.
pi. 18. f. 103. Virginia. Diam. 1-1.320".
Has the habit of Dicladia or Gonio-
thecium.

Genus SYRINGIDIUM: (Ehr.). — Enistiiles simple, cylindrical; valves un-
equal, dissimilai', distended by a turgid middle ling. Maiitime.

SYRiNaiDiTiM bicorne (E.). — Smooth,
elongated, with three constrictions, one
end pointed, the other subglobose, two-
spined. EM. pi. 35 a. 9. i. 11*. Ganges.
Afi-ica. (vm. 20.)

S. Palaomon (E.). — Resembles the pre-
ceding species, but is granulated. EM.
pi. 34. 8. i. 15. Japan.

S. Americanum (Bai. MS. ; vn. 34,
from a di'awing by Professor BaUey). —

Common in Pai-a River, and sparingly
in the soimdings olT the mouth of the
Amazon, South America, Frastules
very miaute, punctated ; central portion
quadi'angular ; valves imequal, one with
a quadi'ate base, suddenly conti-acted and
then tapering into a pyi'amidal spine
terminated by a mucro ; the other valve
subglobose, with two short basal pro-
cesses, each ending in a spine.

Genus SYNDENDRIUM (Ehr.). — Frustules simple, bivalved, subquadran-
gular, one-celled, without umbilicus in the middle ; valves imoqual, rather
tm-gid, one smooth, the other furnished witli many styles branched at the
apex; margin naked. Syndendrium differs from Dicladia only in having
several instead of two spines on one of its valves ; yet Kiitzing has placed
them in different families.

SYNTJENDRitHM Diaclcma (E.). — Frus-
tules lanceolate, with several spines in
the centre of one valve, forked or peni-
ciUate (split up like a brusli), theii' length
equalling the thickness of the frustule.
EM. pi. 35 A. 18. f. 13 ; Bri MJ. iv. p. 7.
f. 49-52 ; Donkin, TMS. vi. p. 1. In

Genus HERCOTHECA (Ehr.). — Frustule simple, turgid, of two imequal
valves ; membrane of valves continuous, not cellulose, generally veined be-
neath the free sette, which are permanent ajul assume tlie place of an intogu-

Peruvian guano; Sea of Kamtschatka;
stomacli of Ascidia, Penzance. Diam.
1-1152". The central nortiou is narrow
linear, projecting at cacii end, the Literal
valves convex, one smooth, the other
with branched spines ; latei-al view oval.

OF THE COCCONEIDEiE.

867

ment. Hence the cori)iisclcs on the upper, contiguous margin of each valve
appear as if crowned and enveloped (as it were, shielded) by the opposite setas
or membranes.

IIercotheca mammillaris (E.'). —
Valves smooth, with the centre of the
base fringed round (fortified) with about
twentj- simple, opposite set<B, inserted

on the margin itself, and extending be-
yond the nianimill£B. EM. pi. 33. 18.
i. 7. Fossil. Bermuda, (vu. 35.)

FAMILY XIV.— COCCONEIDE^.

Frnstules elliptic, rarely bent, adnate by an inferior lateral surface, having
a median longitudinal line and central nodule. " The lateral surfaces prevail
so much that the central portion is reduced to a simple margin, and conse-
quently it is difficult to obtain a front view" (Meneg.). Campylodiscus and
Ehaphoneis, the only members of another family with which any of the
Coceoneideaj are likely to be confounded, are distinguished by the absence of
a central nodule. Those species of Navicula which are elliptic in the lateral
view somewhat resemble species of Cocconeis ; but they are never aduate,
and in them the central nodule is equally developed in both valves.

Genus COCCONEIS (Ehr.). — Characters, those of the famHy. Prustules
depressed or somewhat hemispherical ; the central nodule is wanting or
obscui'e in the inferior lateral surface, and sometimes there is a transverse
as well as a longitudinal line. " The general form of Cocconeis is that of a
disc of an ellipsoidal figure, with surfaces more or less exactly parallel, plane,
or shghtly curved. . . . The characters by which the species of this most
elegant genus are distinguished one from another are still very slight "
(Meneg.). The fnistules in this gemas are frequently fiu-nished vdth an
additional membranous covering, which also forms a border to them, and has
been admitted into the specific definitions ; but we believe this envelope
generally, if not invariably, belongs to the immature state, and afterwards
disappears more or less completely ; and on this accoimt we consider it an
unsafe diS'erential character. The descriptions apply to the lateral view,
unless otherwise stated.

* Disc smooth or with longitudinal lines.

CoccoNTiis hnga (E.). — Veiy minute,
linear-oblong, with roimded ends, smooth,
except a median line and nodule. EM.
pi. 5. 1. f. 25. Aquatic. Iceland.

C.pn?nila(K.). — Very minute, curved ;
lateral view oblong-elliptic, smooth,
without lines or accessory border. KB.
pi. 5. 9. f. 2. Aquatic. Europe. Length
1-15G0". Eabenhorst describes it as
destitute of median line and nodide.

C. pygmcca (K.). — Very minute,
smooth, elliptic, gii-t by a crenulato ge-
latinous border. KB. t. 5. 6. f. 4. Baltic
Sen, on Ceramium. 1-2(540".

C. moksta (K.). — Minute, smooth,
olhptic-oblong, without an accessory
border, densely aggregated. KB. pi. 5.
I' f- 1, 2. Marine. Venice. 1-1800" to
1-1080".

C. nirlulam (K.). — Elliptic-oblong,

smooth ; front view oblong, rectangidar,
KB. t. 4. f. 10. Coast of Normandy.
1-1320". Nidulatiug in mucus.

C. elongata (E.). — Small, smooth,
oblong-elliptic, plane. EM. pi. 5. 3. f 26,
Amenca, Europe, Africa, China. Smaller
than C. Placentula, but may be a variety
of that species.

_C. Crux (E.). — Smooth, elliptic, thin,
with a transverse linear umbilicus. KSA.
p. 53. Western Asia. Dinm. 1632".

C.diaj)hana(S.). — "Elliptical, scarcely
silicious, diaphanous ; strim obscui-e.
Length -0012" to -0018"." SBB. i. p. 22,
pi. 30. f. 254. "ft nodule dilated into a
stauros." Sidmouth, Jersey.

C. Pedicubis (E.). — Small, elliptic,
somewhat angular, slightly curved ; disc
with very fine, dotted longitudinal lines.
SBD. i. p. 21, pi. 3. f. 31. Aquatic.
Conmion. /3. satinn (li.), narrower near
the mai-gin, furnished with very delicate
3 K 2 ■

868

SYSTEMATIC HISTORY OF THE INFUSOKIA,

transverse striae : Saxony, y. minor (K.).
In this species tlie strioe are visible only
when Highly magTiified. It is best di-
stinguished by its slightly angidar or
rhomboid form — a character not noticed
by Ehrenberg, who gives in the ' Micro-
geologie ' only one figm-e, and five habi-
tats. Diam. 1-2200" to 1-960".

C. depressa (K.). — Minute, much de-
pressed, plane, elliptic, furnished near
the margm vsdth pimctated sti-ise. KB.
pi. 5. f. 8. 2. Aquatic. Em-ope. Accord-
ing to Rabenhorst, it resembles a small
and flat state of the var. salma of the
preceding species. Diam. 1-1800".

0. Placenhila (E.). — Plane, elliptic,
with faint, dotted longitudinal lines.
SBD. i. p. 21, pi. 3. f. 32. (vii. 36.)
Aquatic. Common. 1-1440". Ehren-
berg, in his ' Microgeolo^ie,' gives many
figures and upwards of sixty habitats for
this species. His definition differs from
that of Professor Smith, and is as fol-
lows : — " Plane, elliptic, with an abrupt
margin; within and without smooth."
Having seen no authentic specimens of
C Placentula and C. Pediculus, we have
adopted Professor Smith's views, but do
not implicitly rely on them ; for not only
do Ehrenberg and Smith differ in their
descriptions, but whilst the latter states
that both species occm- in the Lough
Moume deposit, the former has excluded
them from his lists of species found
in it.

C.p7-eetexta (E.). — Small, elliptic, with
six longitudinal lines on each side of the
centre, and a dilated, smooth, areolar
margin. EA. pi. 3. 3. f. 11. Japan,
India, Africa, America.

Cpunctata (E.). — Small, elliptic, with
eight punctated longitudinal lines on
each side of the median line. KB. p. 72,
pi. 29. f. 30. Austi'alia, America.

0. mglypta, EM. pi. 34. 6 a. f. 2. Flo-
rida. Ehrenberg's figm'e represents a
small elliptic form, with broadly rounded
ends, and a median line and nodule,
having on each side parallel, distinctly
dotted longitudinal lines.

C. striolata (llab.). — Small, narrow-
elliptic, with dense, faint longitudinal
striae on each side of the median line.
E.ab D. p. 28, pi. 10. f. 8. Aquatic.
Salzburg.

C. obhmf/a (K.). — Oblong-elliptic, with
somoAvhat acute apices and longitudinal
linos. KB. p. 72, pi. 6. 8. f. 7. North
Sea and Indian Ocean. 1-320".

C. limhata (E. ). — Large, elliptic, with
broadly roimded ends, very tine longi-
tudinal lines, and a subentire gelatinou.«

border. EM. pi. 14. f. 42. Adriatic and
Mediten-anean Seas. 1-576". Raben-
horst describes this species as like C.
Placentula vdth a distmctly developed
border-like membrane.

C. oceaniea (E.). — Large, roimdish-
elliptic, with numerous delicately punc-
tated, somewhat converging longitudi-
nal lines ; dorsum convex. KSA. p. 52.
Europe, America, (xu. 42.)

C. concentrica (E.). — Large, broadly
elliptic, with broadly rounded ends and
concentric longitudinal lines. KIB. p. 72,
pi. 28. f. 15. Mexico.

C undulata (E.). — Elliptic; dorsum
slightly convex ; exterior fuiTowed, with
imdulated concentric lines. KB. p. 72,
pi. 5. f. 11. Baltic, Asia, Africa. 1-432".
Not transversely stiiated.

C. lineata, EM. numerous figures and
habitats. Australia, Asia, Afiica, Eu-
rope. We have seen no description of
this species ; but, according to Ehren-
berg's figures, it seems to differ from C.
undulata in the nonconvergence of its
longitudinal striae. Apparently a very
common species, as Ehrenberg gives
upwards of fifty habitats.

0. fasciata (E.). — Large, elliptic ; disc
with dotted longitudinal lines on each
side the median line, intersected by a
ti'ansverse median smooth band. £B.
p. 72, pi. 28. f. 14. Aquatic. Pern.

C. gemmata, EM. pi. 37. 2. f. 1. Ore-
gon, JEgina. Ehrenberg's figure is large,
broadly elliptic, with roimded ends and
a smooth lineai- median line, having
on each side five or six parallel, lon-
gitudinal, moniliform series of large
granules.

C. aggregata (K.). — Oblong-elliptic,
girt with a broadish lacerated, crenulate
limb ; disc having near the margin finely
dotted rays, and in the middle punc-
tated longitudinal lines. KB. p. 72,
pi. 5. 8. f. 5. Baltic and North Seas.
1-1440".

C. marginata (K.). — Elliptic, with
radiatingly pimctated margin and dis-
coid longitudinal lines. KB. p. 72, pi. 5.
0. f. 1. JSIarine. Em-ope. 1-840".

0. dirtqjta (Greg.). — Broadly elliptic
or suborbicidar, with a smooth niedian
line, ha^ang on each side wavy longi-
tudinal and faint transvei-sc .stria?. GDC.
p. 19, pi. 1. f. 25. Scotland. The lon-
gitudinal stii.ne are most evident in the
centre, and the transverse, which are
somewhat radiant, near the margin.
Under a low power the nodule appeai-s
dilated into a stam-os. Professor Gregory
states that it differs in it=< brown colour

or THE COCCONEIDEiE.

869

and conspicuous stiiee from C. dlapham,
the only allied species.

2 * Disc with radiant or transverse
strice.

C. striata (E.). — Elliptic-oblong, of
mediiun size, with pai-allel or somewhat
converging transverse strife. EM. many
flgiu-es. Aquatic. Apparently common,
as Ehrenberg gives upwards of forty
habitats in different parts of the world.
Lough Mom-ne deposit.

C. borealis (E.). — Elongated-elliptic
or oblong with rounded ends and parallel
or converging transverse strife. EM.
several figm-es. Ehrenberg gives about
thirty habitats in Asia, Africa, «&c. Ex-
cept in its more elongated fi-ustule, it
j<carcely differs from C. striata.

C. transversalis (Greg.). — Small, nar-
now-elliptic, with fine, parallel, dotted
transverse strife reaching the median
line. Greg MJ. iii. pi. 4. f. 7. (vu. 3J.)
Scotland.

C. atmospherica, EM. pi. 39. 3. f. 9.
Scirocco dust. Ehrenberg's figure is
large, elliptic, with median line and
nodule and dotted parallel transverse
striae.

C. hyperhorea (E.). — Large, elliptic,
finely pimctato-stiiate ; strife in the
middle margin of the disc, 18 in 1-1200",
continued to the median furrow as
puncta; the fine triple line of furrow
with a single, distinct, transversely ob-
long median umbilicus. ERBA. xviii.
p. 526 ; EM. pi. 35 a. 23. f. 4. Assistance
Bay. Nearly resembles C. Scutum of
New Holland. Breadth rather more
than half the length.

C. nigricans (K.). — Narrow-elliptic,
densely aggregated, girt by an entire,
rather broad, brownish-black border;
transverse striae, 13 or 14 in 1-1200".
KB. p. 72, pi. 5. 8. f. 8. Trieste. /S. de-
nudata, border obsolete. 1C3. t. 5. 8.
f. 10. 1-1320" to 1-1200".

C. consociata (K.Y — Broadly elliptic,
with a hyaline, longitudinal median
line ; disc with 13 punctated, abnost
radiant strife on each side. KB. pi. 5. 8.
f.6. Maiine. Baltic. 1-1320".
_ C. Pinnularia (K.). — Roundish-ellip-
I tic, transversely striated, except a smooth,
crenated, longitudinal median fascia.
KSA. p. 52 ; KB. p. 73, pi. 5. f. 34.
= C'occoneis - — P, BA J. xlii. t. 2. f. 34.
America. This very doubtful species was
constituted by Kiitzing from Professor
Bailey's figure.

C. Perstca (Eab.). — Large, elliptic,
with a longitudinal median line, dilated

at centre and ends, and having 23 ^ra-
nidated transverse stria3 on each side.
Rab D. p. 27, pi. 3. f. 5. Persia.

C. major (Greg.). — Very large, thin,
fiat, broadly elliptic or suborbicular,
with numerous delicate ti'ansverse striiE ;
medifin line with central and terminal
nodules. GDC. p. 21, pi. 1. I 28. Scot-
land. Hyaline, without distinct border ;
stiise about 54 in -001 ", somewhat con-
centric with exti-eniities.

C. Scutellum (E.). — Elliptic, with
finely punctated ti-ansverse striae con-
centric with its extremities ; striae 18 in
•001". EL p. 194, pi. 14. £8; SBD. i.
p. 22, pi. 3. f. 34. Marine. According to
Ehrenberg, foimd in every quarter of the
globe ; yet he gives fewer habitats for
this than for some other species, (ix. 162,
163.) /3, nodule dilated into a stauros :
S. I. c. pi. 30. f. 34. y, disc with stam'os,
very fine strife, and two lateral semioval
mai'kings : Ro MJ. vi. pi. 3. f. 9. Dorsum
convex. 1-1150". The species thus cha-
racterized is very variable in size and
form and in the size of its pimcta. Per-
haps the varieties should be constituted
distinct species.

C. Arraniensis (Grev.). — Valve ovate ;
striae concentric with the exti-emities,
faint, moniliform, contiguous, reaching
the medifin line ; strife 30 in -OOl". Grev
JMS. vii. p. 80, pi. 6. f. 2.

C. specwsa (Greg.). — Small, rhomboid-
elliptic, with 12 distinctly gi'anidated
transverse stiiae in -OOl", and somewhat
concentric with extremities. Greg MJ.
iii. pi. 4. f. 8. Scotland. So nearly allied
to C. Scutellum, that, although its more
distant stiiae are foi-med of fewer and
larger granules, we must doubt whether
these species be really distinct.

C. Mediterranea (K.). — EUiptic or
eUiptic-oblong, with distinct puncta,
regulaiiy an-anged so as to form both
transverse and longitudinal series. KB.
p. 73, pi. 5. 6. i. 8. Mediterranean Sea.
Rather large; dorsum slightly convex.
1-840" to 1-552". In Kiitzing's figm-es
the stiiae appear somewhat concentric
with extremities ; and we doubt whether
it be distinct from C. Scutellum.

C. Peruviana (K.). — Elliptic, regularly
punctate, the larger puncta quadrate,
more distant. KB. p. 73, pi. 6. 6. f. 7.
Marine. Western snores of America,
1-840". Kiitzing's figure seems very
similar to C. Mediterranea.

0. Adriatica (K.). — Large, elliptic ;
strife granulated, transverse on the disc,
radiating on the margin. KB. p. 73
pi. 5. 6. f. 2 & 9. Adiiatic and Modi-

870

SYSXEMAXIC mSTOET OP THE INFUSOIUA,

terranean seas. 1-696" to 1-480". Dor-
sum convex. The strias in Kutzing's
figiu'es are concentric with the extremi-
ties ; and this species seems to diiier fi-om
C. Scutellum in its more distinct border.

C. distuns (Greg.). — Elliptic, with
somewhat attenuated ends, a delicate
median line and ti-ansverse series of
equal, rather distant granules. GDC.
p. 18, pi. 1. f. 23. (vn. 38.) Scotland.
This species agrees with C. Scutellum in
its granulated striae, somewhat concen-
tric with extremities, but it appears to
lis distinct. The striae ai'e fewer, the
granides far more conspicuous, and, ac-
cording to Professor Gregory, equal, and
situated on white, hyaline, faint bars,—
characters absent in C. Scutellum.

C. kmiprosticta (Gveg.^. — Large, rhom-
boid or broadly lanceolate with obtuse
apices, a median line, and transverse
series, of rather distant conspicuous
granules. Greg TMS. v. pi. 1. f. 28.
Scotland. This species agrees with C.
distans in having conspicuous transverse
series of gTanules somewhat concentric
with extremities, but differs in its elon-
gated form.

C. splendida (Gveg.). — Large, elliptic,
with conspicuous, moniliform trans-
verse striae, a broad margin, and a me-
dian line dilated at centi-e and ends.
GDC. p. 21, pi. 1. f. 29. Scotland. Sti-i^
somewhat concentiic with extremities,
their gi-anides near the margiii being
closer, and thus forming a continuous
rim, with the median line terminating
at its inner edge. Remarkable for its
large size. Length about -0044" ; breadth
•0039".

C. (Johnston). — Valve ovate;

sti'iae 20 in -001", concenti-ic ai'ound the
extremities, distinctly granular on either
side the median line, in then* course out-
wards faintly moniliform, more conspi-
cuously so and foi-ming a sort of border
near tlie margin. Johnston, JMS. viii.
p. 1.3, pi. 17. f. 1. Elide guano.

C. ptmctatissi7na (Grev.). — Elliptic,
densely areolato-pimctate ; strife monili-
form, concentric with extremities ; me-
dian line dilated at ends'; rim simply
striated. Grev MJ. v. p. 8, pi. 3. I 1.
Marine. Trinidad. Struc 20 in -001".
Dr. Greville says it differs fi'om C. 3Ior-
risii in its finer, closer, and more mi-
nutely punctated striae.

0. crehrcstriata (Grev.). — Elliptic-
oblong, delicately, closely, and unifonidy
punctato-striate ; sti'iae concentric with
oxtroniitios ; median line straight, simple.
Grev MJ. v. p. 9, pi. .3. f. 2. ' Trinidad.

Length -0022" to -0028"; breadth -0012"
to -0014" ; striaj 30 in -001", The figure
shows the ends of the valve more atte-
nuated than usual in this genus.

C. Grevillu(S.). — Elliptic, withti-ans-
verse costse ; striae moniliform, 15 in
•001". SBD. i. p. 22, pi. 3. f. 35. Eng-
land, South Afi'ica.

C. regcdis (Grev.). — Valve orbicular;
striae monUifomi, 5 in -001", occupying
about a third of the diameter, externally
continued by large dii5tant gi-anules,
forming three or fom- concenti-ic rows.
Grey JiMS. vii. p. 179, pi. 7. f. 1. Cali-
fomian and Algoa Bay guanos. Striae
coarse, outer granules large and promi-
nent, continued round the whole valve,
but smaller near the exti-emities. Median
line abbreviated.

0. pinnata (Greg.). — Valve oval ; sti-ias
concentric with the exti'emities, large,
moniliform, not reaching the median
line, but leaving a narrow elliptical blank
space ; median line distiact. Grev JMS.
vii. p. 79, pi. 6. f. 1. Lamlasli Bay.

C Parmida (B.). — Broadly elliptic,
with a median longitudiaal Une, having
on each side 10 to 12 large, iri'egular
ti-ansverse costae (or sidci) ; sm-face with
transverse gi-anidated striae. Bail. Proc.
Phil. Acad. 1853. Tahiti.

C. sulcata (B.). — Broadly elliptic or
suborbicidar, with 30 to 40 ti-ausverse
arcuate sulci. Bail. I. c. Puget's Sound.

C. incompicua (Grev.). — Suborbicular,
with a broad, rather strongly striated
border ; disc diaphanous, stiiae faint, con-
centiic with exti'emities, becoming ob-
scm-e in the centre. Grev MJ. v. p. 9,
pi. 3. f. 3. Trinidad. Diam. •0011" ;
sti-ia3 22 in -001". Dr. Greville 's figure
shows the sti-ite radiating rather tliau
concentric Tvith the extremities, aud
leaving a blank median space bisected
by the median line and nodule.

C. ornata (Greg.). — Elliptic, with a
strongly striated rim; disc Avith a hin-
ceolate" median blank space, bisected by
a faint median line aud large nodule;
strite somewhat radiant. GDC. p. 19,
pi. 1. f. 24. Scotiand.

C. Finnka (E.). — Ovate - obloug,
slightly convex, smooth externally, but
struited within. ^ lai^-^er, elliptic," three
or fom* times longer tliau broad. EM.
manj' figures. Ehrenberf!: gives about
thu-ty habit^its in Australia, Asia, Ame-
rica, "and Europe, (xii. 41.) 1-570" to
1-360". Ehi-enberg's figui-es do not agree
with his description. They are elliptic
with fin(dv-dottod trans\-crie stri;*, and
a blank-, "gcnei-nlly lanceolate longitu-

OP THE COCCONEIDEiE.

871

dinal fascia, bisected by median line and
nodule.

C. Bnmdusiaca (Rab.). — Very large,
with very convex dorsimi ; disc elliptic-
oblong-, with from 22 to 24 somewhat
diverging, transverse, gTaunlated costfe,
and an oblong central blank space bi-
sected by a lineal" median line. Rab D.
p. 28, t. 3. f. 16.

C. margaritifera (E.). — Broadly ovate,
with subacute ends and ti-ansverse gTa-
nidated strife like rows of pearls. Marine.
Bosphorus, South Africa. It is closely
allied to C. Americana, but is rather
larger and not curved.

C. nitida (Greg.). — ^Broadly oval, with
suddenly conti-acted, subacute, short,
point-like apices, transverse rows of
very large pearl-like gi'anules, and a
narrow-lanceolate blank median space.
GDC. p. 20, pi. 1. f. 26. Scotland. The
granides are so aii'anged as to fonn both
longitudinal and ti-ansverse series. With-
out the central nodule, which we have
not detected, this species agrees with
Rhaphoneis.

3 * Lateral view rhomboid.

C. rhombea (E.). — Rhomboid, with
about three longitudinal lines on each
side the median suture. EAI. pi. 35 a. 7.
f. 2. Aquatic. Niagara. 1-1200". Re-
sembles C. Americana. Witli the excep-
tion of the median line and nodule,
Ehi-enberg's figure has no markings.

C. Americana (E.). — Small, rhomboid,
with somewhat produced obtuse apices
and faint (sometimes obsolete) dotted
transverse strise. KSA. p. 53. C. Mexi-
cana, EA. t. 3. 5. f. 7. Mexico, (xn. 48.)

4* Strife decussating.

C. decussata (E.). — Large, broadly
elliptic, rough with decussating series of
apiculi. KB. p. 73, pi. 28. f. 17. Cuba,
India.

C. rhomhifera (B.). — Broadly elliptic
or suborbicular, with a sigmoid, ob-
liquely longitudinal median lino, run-
nin<j througli a smooth space, attenuated
at the ends and enlarged at the nodule
into a rhomboid figiu-e; surface decus-
sately and transversely punctate. Bail,
in Proc. Acad. Philad. 1853. Puget's
Sound.

6* Slrice transverse, separated into two
series on each side the median lino by a
blank longitudinal fascia.

C. pscudo-mnrf/innta (Grofj.). — I-inrge,
broadly elliptical, witli median lino and
nodvdea having on each side fine trans-

verse sti'ia3, inten-upted and separated
into two series by a longitudinal blank
fascia. G1)C. p. 20, pi. 1. f. 27. (vii. 39.)
Scotland. Thin, transparent, the ends
less roimded than in many species, me-
dian line not reaching the extremities,
and enclosed in the lanceolate space
formed by the convergence of the two
lateral fasciee.

0. tceniata, EM. pi. 6. 2. f. 12. _ FossU.
Morea. We have seen no description of
this species. The figure represents it as
elliptic, having its transverse sti'iffi di-
vided into two series on each side the
median line and nodule by a longitu-
dinal blank fascia, as in some species of
Na^dcula.

6 * Disc with longitudinal concentric lines
interrupted by radiating costce,

C. radiata (Greg.). — Elliptic, with
roimded ends, about 8 concentric lines
interrupted by numerous (18) strong
rays proceeding fi'om the umbilical
nodule. Greg TMS. v. pi. 1. f. 26.
Scotland.

C. costata (Greg.). — ^Valve oval, rather
broad, median line conspicuous, nodule
obsolete, marked with sti'ong entire
costse' reaching from the median line to
the margin; spaces between the costaa
striate ; sti'ise at right angles to the
costfe. Glenshira sand. Greg TMS. v,
p. 68, pi. 1. f. 27.

7* Median line and nodule excentric.

C. ? excentrica (Donkin). — Suborbicu-
lar, divided unequally by the median
line, which does not reach the margin,
and furnished with fine, dotted, trans-
verse, converging stiise. Donkin, TMS.
vi. pL3. f. 11. Marine, (vn. 40.) North-
umberland. One of Dr. Donkin's in-
teresting discoveries, remarkable for the
excentric position of its median line and
umbilical nodule, and probably the type
of a new genus. The striie converge
towards the umbilicus, then' puncta neai-
the margin are closer and more distinct,
forming a broad border.

8 * Transverse strim and conspicuous
margin,

C. coronata (Bri.). — Valve oval ; striaj
transverse, reaching the conspicuous
median line, suiToiuided by a costate
band; spaces between the costm punc-
tate ; costfe about 9 in -OOl" ; stria3 15
in -001". Bri JMS. vii. p. 179, pi. 9. f. 3.
Shell cleanings. West Indies. The me-
dian lino reaches only to the margin of
the band ; breadth ofband -0002".

-872

SYSTEMATIC HISTOEY OF THE INJj-USOEIA.

C.Jimbi-iata(E.). — Valve oval, with
a crenate intramarginal line ; coarse
transverse puncta reaching the median
line. EB. 1858 ; Bri JMS. vii. p. 179,
pi. 9. f. 43. Corsican Algae. This species
IS readily distinguished by its peculiar
looped margin.

Doubtful and unclescribed Species.

C. Navicula (E), — Striated ; the navi-
cular side ovate ; the front view narrow-
linear, with an obscm-e median, longi-
tudinal fui-row. KSA. p. 53. Baltic,
parasitic on Bacillaria paradoxa. 1-864".

C. paradoxa, EM. pi. 9. 2. f. 5. Fossil.
Puy de Dome. Figiu'es small, elliptic,
smooth, with one or two median longi-
tudinal lines and no nodule.

C. Britannica (Nag.). — Large, elliptic,
smooth, with an accessory limb, mar-
ginal outwardly ciu-ved lines, and a di-

stinct median nodule. KSA. p. 890. On
British Algae.

C. tenuismna (Niig.). — Elliptic, very
thin, with concave venter and con-
vex dorsum, sometimes with a narrow,
opaque, crenulated limb. KLSA. p. 890.
On British marine Algse. Varies in
breadth and in presence or absence of
striae and accessory border.

C. disciformis (E.), C. navicidaris (E),
C. Scutum (E.), Swan River ; C. stclluta
(E.), C. undata (E.), Western Asia; C.
tumida (E.), River Jordan ; C. acuta(E.),
Ural Moimtains ; C. turgida (E.), Siberia ;
C. Indica (E.), C. Bramaputra (EA C.
angusta (E.), India; C. Sol (E.), Oasis
of Jupiter Ammon, Africa ; C. SteUa (E),
Teneriffe ; C. Glans (E.), C. BrasiUensis
(E.), C. lirata (E.), Brazil; C. Morrisii
(S.), Black Sea.

FAMILY XV.— ACHNAJS-THE^.

Frustules genuflexed dovmwards, either free, adnate, or stipitate, each
lateral surface having a median longitudinal line and the inferior one a
central nodule or stauros also. The Achnanthese, like the Cocconeideae, have
a nodule only on the inferior valve; but this is almost the only point of
resemblance. The bent frustule and dissimilar lateral surfaces distinguish
this family from every other. In their mode of growth the Achnanthese
resemble the Biddulphiese.

Genus ACHISTAJSTTHIDIUM (Kiitz.). — Frastnles unattached, soHtary or
few together, rarely numerous, in front view linear, bent ; ventral valve with
median line and central and terminal nodules ; dorsal valve without a central
nodule. The Achnanthidia resemble unattached fiiistules of Achnanthes, but
are generally very minute, and their proper position is still somewhat doubtful.
" Admitting it to be proved that in the species of this genus there positively
exists a median nodule in one of the lateral surfaces and not in the other,
and that two puncta exist in the extremities of the piimary. sm-faces, as
stated in the definition of the order and in that of the family, — admitting this,
we should still have to decide whether the uncertain relations of these cha-
racters to other families, and their inconstancy, will give us any right to
erect a distinct genus on principles so slight and precarious " (Meneghini).

* Frusttdes minute, smooth or obscurely
striated.

AcHNANTHiDitTM microccphalum (Iv.).
— Frustules extremely minute ; valves
lanceolate, with capitate apices; sti'iae
obsolete. KB. p. 75, pi. 3. f. 13 & 19 ;
SBD. ii. p. 31, pi. 61. f. 380. Fresh
water. Em'ope. (xiv. 15.) Front view
nan-ow-linear. 1-1080".

A. trinode (Ar.). — Frustides genicu-
late ; valves with one central and two
terminal inflations ; median line and
central nodide distinct ; extremities

rounded ; sti-iae obscure. = JSatmua tn-
nodis, SBD. ii. p. 94. Fresh water.
Britain, (vm. 9.)

A. lanccoMum (Br(5b.). — Fi'ustides
minute ; valves oblong-lanceolate, with
obtuse ends and turgid centre ; strife
obscm-e. Br^b. in KSA. p. 54 ; SBD. ii.
p. 30, pi. 37. f. 304. Fre.^li water. Eu-
rope. Frustules 2 to 100; striae 40 in
•001", S. The transverse baud of the
lower valve sometimes extends to both
margins, sometimes is bifid, and on one
half onlv.

A., ddicatidum (K.). — Frustules nii-

OF THE ACHNANTHEiE.

873

nute ; valves ventricose, witli rosti-ate
ends. KB. p. 75, pi. 3. f. 21. Falcatella
delicatula, Kab D. p. 46, t. 5. f. 4. Sub-
mai-ine. Germany, (xrv. 16.) 1-1680".

A. cryptocephalum (Nag.). — Valves
lanceolate - linear, with the subacute
apices attenuated or obsoletely capitate.
Niig. in KSA. p. 890. Smtzerland.

A. lineare (S.). — Frustules miaute ;
valves linear, obtuse, upper with median
line only, lower with median line and
nodules; stiiee obscm-e. SBD. ii. p. 31,
pi. 61. f. 381. Fresh water. Scotland.

A.. Jlexellum (K., Br^b.). — ^Valves ob-
long, with gibbous middle and very
obtuse ends ; median liae sigmoid. Breb.
KSA. p. 54. = CymheUa (?) -flexeUa, KB.
p. 80, pi. 4. f. 14 ; Eab D. p. 23, pi. 7. f. 15 ;

Achnanthes Bavariea, ERBA. 1853, p.
526 ; Cocconeis Thioaitesii, SBD. i. p. 21,
pi. 3. f. 33. Fresh water. Europe.
1-650" ; striae indistinct ; front view
with genuflexed venter, convex dorsum,
obtuse ends, and a notch-like punctum
at the middle of the lower maigin.

2 * Frustules larr/e, distinctly striated.

A. coarctatum (Br^b.). — Valves elon-
gated, linear-oblong, constiicted at the
middle, with slightly attenuated, obtuse
ends, striae distinct. Breb. in SBD. ii.
p. 31, pi. 61. f, 379. = Achnanthidium
Otrantinum, Rab D. p. 25, pi. 8. f. 3 ;
Achnanthes binodis, EM. pi. 34. 5 B. f. 1 ?.
Fresh water. Em*ope, Africa, America,
(vn. 41.)

Genus ACHNANTHES (Bory St.-Vinc, Ag.). — Frastiiles bent, soHtaiy
or aggregate, attached to a stipes, a central nodule in the lower or ventx'al
valve only. The frustules are bent downwards ; so that the upper margin is
convex, the lower one concave. In some species the lateral portions ai'e
turgid, the central one looking like a band between them ; in others they do
not enter into the front view. The superior lateral sui-face differs from the
lower in the absence of the central transverse peUucid Hne and central nodule,
the latter appeai'ixig like a pnnctum in the front view. A median longitu-
dinal Hne is present in both valves. In their obscure striae " three species
(minutissima, exilis, parvula) present great analogy of form with the pre-
ceding genus. In one of these (parvida) there is wanting the characteristic
angular bending, for which reason it becomes very similar to Odontidium
and Diadesmis. The other species (striatce) differ only by very slight cha-
racters from each other " (Meneg.).

* Valves divided by tivo constrictions
into three lobes.

Achnanthes ren<?7cosa (E.). — Valves
divided by two constrictions into three
oblong inflations ; apices rounded ; striae
distinct. EM. 1. 1. 2. f. 9 ; t. 1. 3. f. 18,
Id. = Monoyratnma ventricosa, E. Asia,
Africa, America.

2 * Valves distinctly striated, not three-
lobed. 3Iarine.

t Valves costate.

A. hmfvpes (Ag.). — Gregaiious ; valves
elliptic-oblong, costate, with moniliform
stria? between the costae. ASA. p. 1 ;
KB. p. 77, pi. 20. f. 1 ; SBD. ii. p. 26,
f. 300. = Conferva stipitata, Eng. Bot.
t. 2488 ; A. Carmichaelii, Grev. in Br. Fl.
u. p. 404. (vii. 42.) On Marine Algre.
Europe, America. Few-pointed; frus-
tules large, with stout elongated stipes;
front view turgid, with convex dorsum.
1-570" to 1-120".

2 1 Valves striated, but not costate.

A. brevipes (Ag.). — Gregarious ; valves
oblong, -svith attenuated acute ends ; stiite
distinct, moniliform, 20 in -001" ; stipes
stout, short. AgCD. p. 59 ; SBD. ii. p. 27,
pi. 37. f. 301. Marine. Europe, Ame-
rica, (x. 199-202.) Fi-ustules large, very
turgid in front view, with convex dor-
sum. 1-860" to 1-180".

A. salina (K.). — Frustides sti-iated,
very turgid, obtiLse-nngled, genuflexed,
with slightly notched venter ; valves
broadly linear, wdth cuueate ends ; strire
punctated ; stipes very short, thick. KB.
p. 77, pi. 20. f. 5. Salt marshes. Europe!
Difl'ers from A, brevipes only in its more
linear valves and cuueate ends. Professor
Smith was probably right in unitinsr
them. °

A. intermedia (K.). — Few-jointed :
fi-ustules striated, obtuse-angled, turgid •
valves sublinear, with acutely cuueate
ends; stipes short, distinct, fine. KB
p. 76, pi. 20. f. 6. On Enteromorpha
mtcstmalis. Gemany, France. Smnller

874

SYSTEMATIC HISTOET OF THE INFUSOEIA,

tlian A. hrevipes, with less turgid dorsum
and finer strios ; but we doubt whether
they are tridy distinct.

A. rhomhoides (E.). — Frustules large,
sti-iated, very tiu-gid, nearly straight;
valves broadly lanceolate, almost rhom-
boid, with acute apices; stipes short,
thick. EA. p. 121. = A. ventricosa, KB.
p. 76, pi. 20. f. 7. Marme. America,
Europe.

A. multiarticulata (Ag.). — Frustules
striated, tm-gid, with rather obtuse
angles ; valves elliptic-lanceolate ; stipes
stout, short. Ag CD. p. 59 ; KB. p. 76,
pi. 20. f. 8. Marine. Em-ope. 1-312".

A. Ca27ensis (K.). — Frustules striated,
turgid, obtuse-angled ; valves lanceolate-
elliptic or oblong ; stipes elongated, stout.
KB. p. 76, t. 21. f. 1. Marine. Cape
of Good Hope. 1-600". It varies with
few or many fr-ustules.

A. hacillaris (E.). — Frustules narrow,
striated, each slightly infiexed at the
middle, both dorsally and ventrally
equally bacillar, with rounded ends ;
stipes short. ERBA. 1843, p. 256. Ma-
rine. Venice. Often in long series. It
is smaller than A. longipes, and more
slender than A. hrevipes, E.

A. suhsessilis (K.). — Scattered, of few
fi-ustules ; valves lineai-oblong, with
roimded ends; striae monilifonn, 24 in
•001"; stipes nearly obsolete. KB. p. 76,
t. 20. f. 4 ; SBD. ii. p. 28, pi. 37. f. 302.=
Achnanthes turgens, EA. p. 121. Common
on tilifonn species of Enteromoi-pha in
salt marshes. Em'ope, America. 1-1150"
to 1-430". (vii. 43.) Easily recognized
by its all but sessile fi-ustules.

A. angustata (Grev.). — Front view
nan-ow ; length 0060" ; breadth -0004" ;
striaj 24 in -001". GrevMJ. vii. p. 163,
pi. 8. f. 9. In Califomian guano. " The
striiB agree in number with those of
A. subscssilis ; the relative length and
breadth, however, of the valve, as seen
in the front view, is so widely different
from the proportions of the species above
mentioned, that the possibility of its
being a variety cannot be entertained"
(GrevUle).

A. a-istata (Rab.). — Valves oblong-
elliptic; stria3 gently cm-ved, coarsely
moniliform, distant, 9 to 10 in -001".
Rab D. p. 26, pi. 8. f. 7. Italy.

A. genirftcxa (K.). — Fi'ustidea .small,
striated, turgid, obtuse-angled, strongly
bent; stipes short, rather stout. IvB.
p. 76, pi. 21. f. 3. Marino. Genoa.

A. Uregoriana (Grev.). — Front view
of frustulo bi'oadly linear; stiiic very
fine ; length •0060" to -0080" ; breadth

•0010" to •OOlS". Grev MJ. vii. p. 84,
]3l. 6. f. 13, 14. Marine. Scotland. In
point of size it rivals A. longipes, but is
A\adely separated from it in the character
of the sti'iation alone, to perceive whicli
requires not only a good ooject-glass but
delicate manipulation. As in many of
its congeners, the fi-ustules A^ary greatly
in both length and breadth (Grev.).

A. pachypus (Montague). — Frastules
small, finely striated, obtuse-angled,
rather tm-gid ; valves elliptic-oblong ;
stipes stout, vei-y short. Mont. Flor.
Boliv. pi. 1 ; KB. p. 76, pi. 29. f. aS.
Marine. Europe, Asia, America. 1-1730"
to 1-1320".

A. parvula (K.). — Frastules minute,
nearly sti-aight, obtuse -angled ; valves
elliptic-oblong, obtuse, finely striated;
stipes rather stout. KB. p. 76, t. 21. f. 5.
On Enteromoi-pha in bracMsh water.
Em-ope. Frustules stouter than in A.
exilis.

3 * Very mimde ; strice wanting or
indistinct. Fresh water.

A. exilis (K.). — Frustules slender,
linear ; valves lanceolate, tapering to
the subacute apices ; sti-ise indistinct ;
stipes slender, elongated. KB. p. 76,
t. 21. f. 4 ; Ralfs, ANH. xiii. p. 14. i. 12 ;
SBD. ii. p. 29. Fresh water. Em-ope,
Asia, America, (vn. 44.^ A. exilis is
easily kno-wn by its mmute, slender,
hyaline frustules fi-om every other spe-
cies except A. minutissima. From that
species it differs by its tapering, more
lanceolate and acute valves, and by its
elongated stipes.

A. mimdissima (K.). — Fi-ustules slen-
der, linear; valves lmeai--obloug, with
rounded ends ; strias obsolete ; stipes
fine, shorter than the frustule. KB.
p. 75, pi. 13. f 2 c ; Ralfs, ANH. xiii. pi. 14.
f. 11. Fresh water. Europe. We for-
merly considered this a variety of A.
exilis, and, still doubting whether the
differences ai'e constant, thinlc that Pro-
fessor Smith may rightly have imited
them.

Doubffid Species.

A.? arenicola (Bail.). — Frustules mi-
nute, rectangular or slightly curved;
valves lanceolate, sti-iate; stipes .«hort.
Boil. Sm. Cont. ii. p. 38, pi. 2. f. 19.
Marine. America. It is possibly a spe-
cies of Ilvalosira, but requires further
studv (Bnil.).

A' ausfralis, EM. pi. 35 a. 2. f. 1.
South Africa. Frustules linem-, imi-

or THE CYMBELLEiE.

875

formly ciu-ved, with truncate ends and
striated mar<^n,

A. ? in(equalis (E.). — Unequally bent
and smooth. EM. pi. 16. 1. f. 46, &
pi. 17. 2. f. 25. Fossil. Sweden, Finland.

A.? paradoxa (E.). — Fi'ustides ovate,
obtuse, twice as long as broad, with 16
transverse, scabrous, punctated lines in
1-1152". ERBA. 1845, p. 73. Fossil.

United States. 1-900". No nodule ob-
served, E.

iS^ecies known to us only by 7iame.

A. turgida (E.), Australia, America;
A. Indica (E.), India; A. Javanica (E.),
Java; A. ohtusa (E.j, Afiica; A. Semen
(E.), America; A, Jirastltensis (E.), Bra-
zil; A. incrassata (E.), America,

Genus CYMBOSIRA (Kiitz.). — Frustules as in Achnantlies, stipitate, con-
nected into series by a gelatinous process or hinge (isthmus). Cymbosira
diflPers from Achnanthes by the same character as Diatoma fr^om FragUaria.

CviiBOsmA Af/ardhn (K.). — Frus- obtuse apices. KB. p. 77, pi. 20. f. 3.

tides lineal', slightly ciu'ved, with roimded = Achnanthes seriata, AgCD. Marine,

apices ; valves lineai', oblong, scai-cely Venice, Cayenne, (xrv. 14.). 1-960" to

dilated at the middle, with rounded 1-288". Stipes very short.

Genus MONOGEAMMA (Ehr.). — Frustules ftirnished with transverse pia-
nules, a median, transverse, linear band on one valve only, three ventral
nodules and two dorsal. ( = Stauroptera with a stauros on one valve only, or
to a solitary Achnanthes with terminal puncta. — EEBA. 1843, p. 136.) Not-
withstanding Ehrenberg's remarks, we cannot distinguish this genus from
Achnanthidium. The species are known to us only by name.

MoNOGKAMMA Acknunthes (E), India. M. ventricosa (E.) = Achnanthes ve?i-
M. trinodis (E.), Sandwich Islands. tricosa.

FAMILY XVI.— CYMBELLEtE.

Frustules cymbiform ; valves lunate, with a longitudinal Une, and mar-
ginal or subcentral nodule. In shape the Cymbelleae are very similar to the
Eimotiese, but they differ essentially both from them and the Naviculcae by
the median nodules of the lateral surfaces being marginal or submarginal.

Genus CYMBELLA (xig., Kiitz.). — Frustules free, cymbiform ; transverse
striae interrupted by a longitudinal line having central and terminal nodules,
and dividing the valve into unequal portions. The frustules, in the lateral
view, have one margin (dorsum) convex, and the other (venter) straight, or
at least less developed. In consequence of this form, the longitudinal Line
divides the surface unequaUy, being much nearer the lower margin. CymbeUa
includes species distributed in the genera Cocconema, Navieula, and Piunu-
laria of Ehrenberg's system.

* Valves with one margin triundidate.

Cymbella Arcus (Greg.). — Valves
slender, semilanceolate, with straight
venter, convex, triundidate dorsum, and
produced, minute, capitate apices. Greg,
m MJ. iv. p. 6, pi. 1. f. 21 ; SBD. ii.

L85. Scotland. IMinuto ; longitudinal
e and nodules submarginal ; transverse
strire very fine, 40 in -OOl".

_C. sinuata (Greg.). — Valves lanceolate,
with subcapitftto apices, gently convex
dorsum, .and triundulate venter, Greg.
MJ. iv. p. 4, pi. 1. f. 17. Scotland.
Minute; transverse striae conspicuous,

about 20 in -001", scai'cely reaching the
median line.

2* Valves without triundulate margins.

t Valves with produced or capitate
apices.

C. JEhrenbcrgii (K.). — Valves broadly
lanceolate, with unequal sides, suddenly
contracted into rather obtuse, sliglitly
produced apices; transverse striie di-
stinct, punctate, 12 in 1-1200". KB. p. 79
t. 6. f. II ; SBI). i. p. 17, pi. 2. f. 21. =2^al
vicida incequalis, E Inf. 1. 13 ; Pimuduria
inaqualts, EM. many figures. Common,

876

SYSTEMATIC HISTOKY

OF TIIK INFDSOBIA,

both recent and fossil. Europe, Asia,
Africa, America, (vu. 46 ; ix. 154.)
Lai'ge ; length 1-216". Difl'ers from a
Naviciila only in having one margin of
the valves less convex than the other.

C. heteropleura (E., K.). — Valves
broadly lanceolate, with unequally con-
vex sides, suddenly conti-acted into short,
broad, very obtuse, beak-like apices ;
striae distinct. KB. p. 7Q.=.Pmnitluria
heteropleura, EM. pi. 5. 2. f. 11. North
America. Large; allied to C. Ehren-
hergii, but with more obtuse apices.

C. cuspidata (K.). — Valves broadly
lanceolate, with imequally convex sides,
suddenly contracted into subacute, short,
rostrate apices ; strife delicate, 18 to 20
in 1-1200". KB. p. 79, t. 3. f. 40 ; SBD. i.
p. 18, pi. 2. f. 22. Em-ope. 1-576".
(vn. 45.) Differs from the preceding
species in its smaller size, more graceful
form, and narrow beaks.

C. rostrata (Rab.). — Valves semilu-
nate, with dorsum sti'ongly and venter
slightly convex ; ends produced into
short, subacute beaks ; striae dotted, con-
verging, 12 or 13 in 1-1200". Rab D.
p. 22, pi. 7. f. 5. Italy. SmaU. Very
nearly allied to C. cuspidata.

C. porrecta (Rab.). — Valves tui-gid-
lanceolate, with unequal margins ; ends

Eroduced into rather long, stout, obtuse
eaks ; striae stout, somewhat converg-
ing, 6 in 1-1200". Rab D. p. 22, pi. 10.
f. 10. Italy. Venter less turgid than
the dorsirm.

C. fornicata (Rab.). — ^Valves limate,
with very fine convex dorsum, gibbous
venter, and produced, obtuse, rostrate
ends ; stricfi fine, smooth, 7 or 8 in
1-1200". Rab D. p. 22, pi. 10. f. 9.
Persia.

0. amphicephala (Nag.). — Smooth ;
valves elliptic, with unequal sides and
produced capitate apices; fi'ont view
oblong with truncate ends. KSA. p. 890.
Switzerland.

C. csqualis (S.). — Valves lanceolate,
nearly symmetrical, with shortly pro-
duced, slightly cui-ved, obtuse extre-
mities ; strife fine, 30 in -OOr '. SB D. ii.
p. 84 ; Grev. in ANH. 2 ser. xv. pi. 9.
f. 4. Britain. A very distinct species,
which differs from Navicula only by the
slightly cui-vcd ends, Grev.

C.pachycephala (Rab.). — ^Valves semi-
lunate, ciu^ved, with veiy convex dorsum
and gibbous venter, sti'onglv constricted
beneath the produced capitate apices;
striae granulate, somewhat coll^•crgiug,
7 or 8 in 1-1200". Rab ]). p. 22. = C.
eurijcephala, Rnb. t. 7. f. 10. Servia.

C. einthemioides (Rab.). — Valves arcu-
ate, witli convex dorsum, concave venter,
and produced, obtuse, slightly recui-ved
ends ; striae stout, somewhat converg-
ing, 6 in 1-1200". RabD. p. 22. = 6'.
costata, Rab. t. 7. f. 16. Salzburg.
Like an Epithemia, but having a central
nodule.

C. Gregorii (Ralfs). — Valves arcuate,
with convex dorsum, straight venter, and
slightly produced truncate apices ; striae
distinct. = C. truncata, Greg, in MJ. iii.
p. 38, pi. 4. f. 3. Scotland. SmaU.

C. turgida (Greg.). — Valves lunate,
with tui'gid, convex dorsum, nearly
straight venter, and produced, minute,
acute apices; strias very conspicuous,
about 24 in -001". Greg MJ. iv. p. 5,
pi. 1. f. 18. Scotland, America.

C. Pisciculus (Greg.). — Valves lanceo-
late, with convex dorsum, nearly straight
venter, and obtuse, siibcapitate apices;
striae about 30 in -001". Greg, in MJ.
iv. p. 6, pi. 1. f. 20. Britain.

C. excisa (K.). — Valves semilunate,
with slightl}' recurved, produced apices,
very convex dorsum, and a straight
venter, notched at its middle ; striae 16
in 1-1200". IGB. p. 80, pi. 6. f. 17.
Em-ope. Minute.

2 1 Apices neither rostrate nor capitate.

C. affinis (K.). — Valves lanceolate,
with subacute, scarcely produced apices,
and the dorsal margin more convex than
the ventral ; striae faint, 19 in 1-1200".
KB. p. 80, pi. 6. f. 15 ; SBD. i. p. 18, pi. 30,
f. 250. = Cocconema FiimUum, EM. many
figm-es. Emope, Asia, Australia, Afi-ica,
America. Minute; tei-minal nodules
large. 1-1150" to 1-620".

C. deUcatulu (K.). — ^^'alves unequally
and nai-rowly lanceolate, smooth. IvSA.
p. 59. France. Minute. 1-1200".

C. obtusiuscula (K.). — Valves lanceo-
late, with one margin rather less convex
than the other ; apices somewhat obtuse,
not produced; strife fine, 18 to 20 in
1-1200". KB. p. 79, pi. 3. f. 68. Europe.
1-600". Differs from a Na\'icula only by
its slightly miequal margins.

C. Helvetica (K.). — Valves elongated,
somewhat arched, slender-lanceolate,
with slightly gibbous venter, and rather
obtuse apices ; stria5 fine, grauidated, 13
or 14 in 1-1200". SD. i. p. 18, pi. 2. f. 24.
Europe, (xiv. 24-28.) Laree. 1-264"
to 1-240". Front view oblong, trun-
cate. Alrin to C. gastroides, but more
slender, K.

C.viaxima (Nag.}. — Valves slender,
with attenuated, i-ather obtuse ends, and

or THE CYlIBELLEiE.

877

inflated venter; strise 16 in 1-1200."
KSA. p. 890. Switzerland. 1-180" to
1-120".

C. gastroides (K.). — Valves lunate,
■with ottuse apices ; venter slightly con-
cave, with gihbous centre ; strife gTanu-
lated, 11 or 12 in 1-1200". KB. p. 79,
pi. 6. f. 4 6. Eiu-ope. (xiv. 18-20.)
Large.

C. tnmcata (Rah.). — ^Valves as in C.
gastroides, but with broadly truncate
apices. Rab D. p. 21 ; C. fulva, t. 7. f. 3.
= C. gastroides, KB. p. 79, pi. 6. f. 4 a.
Europe.

C. leptoceras (E., K.). — Valves slender,
arcuate, with gibbous venter and attenu-
ate apices ; strias veiy fine, 17 in 1-1200".
KB. p. 79, pi. 6. f. 14. = Cocconema lep-
toceras, EA and M. many figures. Eu-
rope, Asia, Austi-alia, Africa, and Ame-
rica. Minute ; front view elliptic-oblong,
with rounded ends.

C. macidata (K.). — Valves semiorbicu-
lar, with very convex dorsum and straight
or gibbous venter ; strias very fine, 12 to
13 in 1-1200". KB. p. 79, pi. 6. f. 2. =
C. Lunula, Rab D. p. 23. = Cocconema
Lunula, EA and M. many figures. Com-
mon. Europe, Asia, Africa, America.
Minute ; front view elliptic, with tmn-
cate ends.

C. obtusa (Greg.). — ^Valves semi-oval,
with very obtuse apices, convex dorsum,
and nearly straight venter; stTite very
fine, inconspicuous, about 36 in '001".
Greg MJ. iv. p. 5, pi. 1. f. 19. Scotland.
Minute.

C. ventricosa (Ag.). — Valves semilu-
nate, with very convex dorsum, straight
venter, and large, distinct terminal
nodules ; stiise inconspicuous, 30 in
•001". Ag CD. p. 9; KB. p. 80, pi. 6.
f. 16; SBD. ii. p. 84. Europe. Minute.

1-1000". Front view oblong, with trun-
cate ends.

C. microstoma (Rab.). — ^Valves innately
cm'ved,with broadly obtuse ends ; dorsum
convex, depressed at the centre ; venter
concave ; nodides very minute ; striae
smooth, 7 or 8 in 1-1200". Rab D. p. 22,
t. 10. f. 3. Persia.

C. Scotica (S.). — Valves slender, semi-
lanceolate, with straight ventral margin
and acute apices; striae 42 in -001".
SD. i. p. 18, pi. 2. f. 25. Britain.

C. gracilis (E., K.). — Valves slender,
semilanceolate, with sti'aight or slightly
concave venti'al margin and subacute
apices ; striae very fine or obsolete, 17 in
1-1200". KB. p. 79, pi. 6. f. Q.= Cocco-
nema gracile, EM. several figures. Eu-
rope, Asia, Afiica, America. Lough
Moume deposit. Small. 1-840" to
1-600".

C. lunata (S.). — Valves nai-row, lunate,
with slightly concave venter, and rather
obtuse apices ; striae distinct, 24 in
•001". SBD. ii. p. 84. Grev. in ANH.
2nd ser. xv. pi. 9. £ 6. Scotland. Di-
stinguished from C. Helvetica by its
smaller size and concave venter, and
from C. Scotica by its coarser sti'iae and
obtuse ends, Grev.

C. curvata (Rab.). — Valves smooth,
lunate, with convex dorsum, slightly con-
cave venter, and obtuse ends. Rab D.
p. 23, t. 7. f 14. 6. Italy.

C. ? Diance, E. = Cocconema Diance,
EM. yl. 15 A. f. 100 a. Lough Mom-ne
deposit. Small. Valves lunate, with
convex dorsum, concave venter, and ob-
tuse apices.

C. ? Naviculu = Cocconema Navicula,
EM. pi. 17. 2. f 35. Finland. —Valve
lanceolate, with the dorsum rather more
convex than the venter.

Genua COCCON'EMA (Ehr.). — Frustules cymbiform, stipitate ; lateral
surfaces lunate, striated, and divided unequally by a longitudinal line with
median and terminal nodule.s. The frustules are similar in form to those of
Cymbella, and when detached, their proper genus is often doubtful ; the lower
margin, however, is less frequently convex than it is in Cymbella.

Cocconema lanceolatum (E.). — Front
view lanceolate, truncate ; valves elon-
gated, arcuate, or semilanceolate, centi-e
of venter gibbous ; striae monilifoi'm, 21
in -001". EI. t. 19. i. 6 ; SBD. i. p. 75,
pi. 23. f 219. Europe, Asia, Australia,
Africa, America, (x. 194, 195.) Length
1-210" to 1-120". Ventral margin of
frustule nearly straight, with slightly
gibbous centre; stipes dichotomou.s,
nrtirulat,ed.

C. aspe)-um (E.).— Habit and size of
C. lajiceokitum, but with striae denticu-
late or interrupted by puncta. EM.
many figures. Australia, Asia, Ame-
rica ; fossil. Franco. 1-288". We fear
this form is scarcely distinct from C.
lanceolatum.

C. fossilc, EM. t. 19. f. 57. Greece.
Ehrenberg's figure represents a smaller
species than C. asperum, with straight
ventral margin, nearly mnrginal longi-

878.

SYSTEMATIC KISTOET OF THE IITFUSOETA.

tiidinal line and nodiiles, and deiaticulate
strire.

C. JSremw (Nag'.). — Pulvinate; valves
slender, sublimate, with attenuated ends
and obtuse apices; stria) very fine.
KSA. p. 890. Rocks in streams. Switzer-
land. Large ; stipes long, articulated ;
frustules in front view lanceolate.

0. cornutum (E.). — Valves slender ;
limate, gradually tapering into long ends,
with obtuse apices ; venter concave, gi-a-
dually tumid at its middle. EM. pi. 15 a.
f. 94. America, Berlin. Lough Moume
deposit. Large ; differs from C. lanceo-
latum in its more slender and tapering
form.

0. Mexicanum (E,). — Stout; valves
lunate, vdth obtuse, slightly produced
ends ; ventral margin slightly tumid ;
dorsum verjr convex ; striaa 18 in
1-1152", distmctly and elegantly granu-
lose. EM. pi. 33. 7. f. 6, 7. Mexico.
Large. 1-206".

C. Cistula (E.). — Valves lunate, with
very convex dorsum, and the concave
venter tumid at its centi'e ; stipes elon-
gated, filiform, subsimple. EI. t. 19.
f. 7 ; SBD. i. p. 76, pi. 23. f. 221. = Gom-
phonema semi-ellipticum, Ag CD. p. 33 ;
G. simplex, KSA. p. 37. Europe, Asia,
America. (x. 196-198.) 1-1150" to
1-430". Front view elliptic-oblong,
with obtuse ends.

C. Grcecwn (E.). — Habit of C. Cistula,
but with stronger and fewer strise, 12 to
13 in 1-576". ERBA. 1840, p. 12.
Greece. 1-575".

C. ? biceps (E.). — Valves tiu'gid, semi-
oval, each ends m a flat and ttunid mar-
gin, suddenly rostrate, obtuse ; sides
longitudinally sulcate and transversely
sti-iate. ERBA. 1845, p. 362. Marine.
India. 1-576". Habit of C. Cistula.

C. cymbiforme (Ag., E.). — Slender;
valves lunate, with somewliat obtuse
apices; venter straight or slightly con-
cave, with rather tiunid centre ; stipes
intricate, fonning a compact gelatinous
mass. EI. pi. 19. f. 8 ; SBD. i. p. 76,
pi. 33. f. 220. = Cj/mbvlla cymbifonnis,
Ag CD. p. 10; Frnstulia cymbiformis,
KSA. Europe, Asia, America, (xn.
46.) 1-500" to 1-150". Transverse
strise 16 in 1-1200". Front view linoar-
lanceolate, with truncate ends. It forms
a brownish compact covering on rocks,
which is frequently of considerable
thiclmess and extent.

CP acutimi (E.). — Slender, slightly
cuiwod, .smooth (?), with acute ends;
ventral margin slightly tumid in the
middle. EA. p. 123. Labrador, Falaise P.

Small ; habit of a curved NavicuUi am-
phioxys.

C. tumidum (Breb.). — Valves semilu-
nate, with obtuse, scarcely produced
ends; ventral margin nearly straight;
front view lanceolate, with truncate
apices. KSA. p. 60. France. Small.
1-576". Strise 16 in 1-1200". Stipes
elong'ated, filiform, simple.

C. affine (K.). — Valves lunate, with
very convex dorsum; stipes intricate.
KSA. p. 59. France. Minute. Resembles
Cymbella affinis, but is stipitate.

C. gibbiim (E.). — Valves semieUiptic,
with ti-imcate, slightly produced apices ;
transverse stiise very delicate. KB. t. 6.
f. 6. Europe, Asia. (xm. 10.) 1-480".
j3 sessile. Stipes obsolete. = Cymbella
Orsiniana, Rab D. p. 23.

C. Arcus (E.). — bemilunate, with ob-
tuse apices ; dorsum very convex, venter
not gilDbous. EM. several figiu-es. Asia^
America, Lough Mourne deposit.

C. parvum (S.). — Valves lunate, vpith
subacute ends; ventral margin scarcely
gibbous ; fi-ont view nearly linear. SBD.
i. p. 76, pi. 23. f. 222. (vn. 47.) CHff,
BeachyHead. IMinute. -0009" to -0016",
Sti-iaj 21 in -001".

C. Saxojiicum (Rab.). — Valves semi-
lunate, with acute ends ; ventral margin
straight or slightly concave ; dorsum very
convex ; strife faint. Rab 1). p. 24, 1 10.
f. 11. Saxony. Minute. The fi-ont
view is figm-ed as oblong, with ti'uncate
ends, and the stipes dilated beneath the
fi'ustule.

C. Boeckii (E.). — ^^^alves elongated,
lanceolate, with subacute apices ; fi-ont
view linear-lanceolate, obtuse ; striaj 26
in 1-1200". E Inf. t. 19. f. 5. = GompJio-
nema lanceolatum, Ag CD. p. 34 ; Dory-
phora Boeckii, SBD. i. p. 77, pi. 24. f. 223.
Marine. Europe. Large. 1-210" to
1-120. Stipes dichotomously divided,
(vn. 48.) This species is no doubt
wi'ongly refeiTed to Cocconema, since
both margins of the lateral valves are
symmeti-ical. We regard it as a stalked
Navicula, and find a centi-al, though in-
conspicuous, nodule — a fact whicli, we
think, forbids it being placed in Dory-
phora as Professor Smith proposed.

Species known to m only by name.

0. subfile (E.), Asia, America: C.
cinyulatum (E.), Georgia; C. Javani-
cu'm (E.), Java; C. AraucanitP. (E.),
America,

OF THE CTMBELIE^.

879

Gemis SYNCYCLIA (Ehr.)— Fnistiiles cymbiform, connected in a circular
manner Avithin an amorphous gelatinous substance. " Whenever the lateral
sm-faces ai'e inclined to each other by the different ^extension of the. two pri-
mary surfaces, the associated series must be formed circularly" (Meneg.).

Stocycli^v Salpa (E.). — Fi-ustules
senii-oval, smooth, mostly connected, in
sixes, into short tubes or rings ; colour-
ing matter pale green. E Inf. p. 233,
t. 20. f. 11 ; XSA. p. 61. Marine, near
Wismar. (vn. 53 ; x. 206.) Length
1-2300" to 1-570". When diy, longi-
tudinally plicate.

S. quaternaria (E.). — ^Fnistules binate

or quaternate, smooth ; coloiu'ing matter
golden- or reddish-browTi. ERBA. 1840,
p. 22 ; KSA. p. 61. Maiine. Em-ope.
1-864".

Species knotvn to tis only by name.

S. granulata (E.), Georgia j S. Am-
phora (E.), Palestine.

Genus ENCTONEMA (Kiitz.). — Frustules cymbiform, arranged in longi-
tudinal series within submembranous tubular filaments. Yalves divided
imequally by median line and nodules. " Encyonema differs from Schizo-
nema and other frondose genera of Diatomacese in. the form of its frustules,
a single frustule resembhng one of Cymbella or Cocconema. It is more
probable that some bodies, which are really congeries of the ova of certarQ
insects, will be at fij'st sight classed with Encyonema ; but these ova, although
cymbiform and arranged in longitudinal series, are neither siliceous nor

striated The lateral surfaces of the frustule, beiag convex, are observed

in the front view, in which also the frustules are quadrilateral, with two
puncta at each end. These pimcta are less easily discerned in the dorsal
view, and the dorsum is longitudinally convex. The lateral view is semi-
eUiptic, with numerous transverse striae, which are interrupted, as ia Cocco-
nema, by a longitudinal pellucid Line" (Ealfs). Professor Smith says that the
frustules of Encyonema, even when removed from the frond, may be distin-
guished from those of Cymbella, " as the terminal nodules of the median line
in Cymbella are placed at the exti-emities of the valves, while in Encyonema
they are removed to some distance above, and occupy a place nearer the
central nodiile."

'Engyq'nf.ua iirostratiim (Berk., Rolfs).
— Filaments subsimple ; valves with
rounded, mostly incm-ved ends; striae
18 in -001". Length -0016" to -0024".
Ralfs, ANH. 1st ser. xvi. pi. 3. f. 3;
KSA. p. 61 ; SD. ii. p. 68, pi. 54. f. .346.
= Momma prostratum, Berk BA. pi. 4.
f. 3 ; Schizonema prostratum, Grev BFl.
p. 414; Encyonema paradoxum, E Inf.
p. 237 ; Glcsonema Leihleini, Ag CD.
p. 31 ? Europe, Asia, America. The
valves have a depression beneath each
apex ; sometimes the depression is very
slight, at others so deep and notch-like
that the ends become rostrate. The
fomer condition is the E. paradoxum of
Kiitzing. (vrt. 49 ; xiv. 22J

E. Auerswaldii (Rab.). — Valves with
vei-y convex dorsum, slightly gibbous
venter, and contracted, produced, obtuse
ends ; strire 11 or 12 in -001". Rab ]).
p. 24, pi. 7. f. 2. Leipzig.

E. ccsspitosum (K.). — Filaments erect,
tufted, much interwoven; valves with

convex dorsum, slightly tumid venter, and
straight, slightly produced, obtuse ends ;
striffi 24 in -001". KSA. p. 61 ;' SBD. i.
p. 68, pi. 55. f. 346. = ^. jn-ostratimi, KB.
p. 82. Em-ope. The frustules ai-o
smaller than those of E. prostratum.

E. tnanyulum (E., K.).— Valves with
vei-y convex, gibbous dorsum, slightly
convex venter, and produced, acute
apices. KSA. p. Q2.= Glao»cma trian-
gulum, ERBA. 1845, p. 77; EM. t.35A.
7. f. 10. River Niagara. Dorsum so
turdd as to give the valve a ti-iangular
outline. " It is a vcrv remarlfable cir-
cumstance, that I often" found two differ-
ent sorts of frustules in the same tube
—one very delicate and straight lilce a
Naunema, the otiier the large curved
kind. Even to the present moment I
cannot explain this phenomenon ; for both
sorts were in considerable quantities and
quite free, and therefore it ia difficult to
suppose one a parnsite " (E.).

\\. Sinensis (E.). — Ynlvcs oblong,

880

SYSTEMATIC SISTOBT OP THE tNlfUSOEIA.

striated, with the habit of Cocconema,
but suddenly reflexed under the very
obtuse apices in the manner of Eimotia.
= Glceonetna Sinense, ERBA. 1847,
p. 484 ; EM. China, Java. Ehrenberg's
tigiu'e represents the valve distinctly
striated, with straight venter, very ob-
tuse, rounded ends, and the dorsal mar-
gin very convex, and cui-ved upwards at
each end.

E. gracile (Rab.). — Valves slender,
with trimcate apices, slightlj^ gibbous i

middle and indistinct strias. Rab D.
p. 26, pi. 10. f. 1. Salzburg. Frustules
minute.

Doubtf ul Species.

E. (/lohiferum (Ag.). — Filaments ab-
breviated, frustules simple or binately
conjoined, hyaline, with a globule in the
middle. = Gheonema qlohiferum, Ag CD,
p. 31. Italy.

E. Arcus= Glceonema Arcus, ERBA.
1856, p. 333, f. 26. Africa.

Genus AMPHORA (Ehr.). — Frustules free, cymbiform ; lateral view lunate
or arcuate, with a nodule at the middle of the ventral margin ; front view
with the median lines and nodules of valves approximate and within the
margin. The frustules are mostly very thin, hyaline, and imperfectly sili-
cious : their form is peculiar ; and Professor Amott, who has given in the
sixth volume of the 'Microscopic Journal' a detailed account of their structure,
aptly compares it to that of a coffee-bean rounded on the back and hollowed
out in front." Many of the species are insufficiently known ; they should be
viewed in front, back, and side. Fortunately, from their hyaline nature, the
dorsum and venter can in most cases be examined merely by the alteration of
the focus. The lateral view closely resembles that of a Cymbella, but has the
nodule marginal. The front view is usually barrel-shaped, owing to the con-
vexity of the valves, which are so curved inwards that their central nodul&s
are more or less approximate and frequently appear nearer to the connecting
zone than to the margins. The portions of the valves interior to the median
line are inconspicuous, and rarely afford diagnostic aid ; whilst the portions
exterior to the median lines are important, offer the best view of the trans-
verse striae, and vary in shape according as the median line appears straight,
concave, or flexed. In our descriptions we call these latter the outer por-
tions, and when they project inwards at the centre in a cuneate manner, or
a]3pear inflexed, we term them canoe-shaped. The dorsum is convex, shows
no nodules or lateral valves, and is mostly marked by longitudinal lines
between longitudinal series of short, transverse striae, like the connecting
zone of StriateUa, but unaccompanied by internal plates. The late Pro-
fessor Gregory, who directed attention to these facts, believed that Amphora
could be divided into two groups — simple and complex, from the absence or
presence of this structure. His arrangement, however, we ai-e unable to
adopt, because in many species a decision is difficult ; and indeed we think
that the longitudinal lines, so common if not invariable, indicate the complex
structure, although the hyaline natiu-e of the frustides may interfere with its
detection. In Amphora the specific characters are taken, almost constantly,
from the front view, and not from the lateral one as in most other genera of
Diatomacese ; and as the connecting zone varies greatly in breadth according
to the condition of the fmstule, due allowance must be made for that fact. If
division has recently taken place, the connecting zone will be narrow, and the
ends of the frustulc less broadly truncate than just previous to that process.
For the same reason we believe that the number of longitudinal lines varies
and affords no aid in distinguishing the species. Amphora contains several
species of Agardh's genus Cymbella, and ought, in our opinion, to have re-
tained that generic appellation. Because of its cymbiform frustides, we liave
removed this genus from the Naviculeoe, where Kiitzing placed it ; the same
reason, added to the presence of median lines and nodules, compels us to

OF THE CYMBELLEJS.

881

place it with the CymbeUefE instead of mth the SurireUeiS, as Eabenhorst
has done.

with transversely dilated nodules, and
64 ohscm-e strire in •001". SBD. i.
p. 20, pi. 2. f. 30. Fresh water. Para-
sitic on other Diatomaeeae.

A. rimosa(E.). — Gennany. Frustules
eUiptic-oblong, with rounded ends, nar-
row lunate outer portions, transverse
nodules, and no striae. EM. pi. 13. 2.
f. 17.

A., elegam (Greg.). — Fi'ustules oval,
with truncate ends ; outer portion of
valves lunate, vnth transverse nodule,
and very fine, inconspicuous, transverse
strife. Greg. TM. v. p. 70, pi. 1. f. 30.
Scotland.

A. ostrearia (Breb.). — Frustules hya-
line, elliptic-oblong, with rounded ends ;
outer portion of valves naiTOw, canoe-
shaped, with transverse nodule and di-

• Fnisiules in front view distinctly
constricted at the middle.

AsrPHORA binodis (Greg.). — Fmstules
constricted at the middle ; lobes inflated
at the base, with broadly linear, sub-
ti'uncate ends ; transverse striae obscure,
about 30 in -001". GDC. p. 38, pi. 4.
f. 67. Maiine. Scotland. Resembles
the next species, but is smaller, with
more rounded inflations and obscure
striae, Greg.

A. angularis (Greg.). — Frustules sinu-
ate-constricted at the middle ; lobes an-
gularly inflated, with short, broadly
linear, ti'uncate, produced ends ; strife
diatLact. Greg. MJ. iii. p. 39, pi. 4. f. 6.
(vn. 50.) Differs from A. binodis by
having angular inflations and coarser
sti'ise.

A. lip-ata (Greg.). — Frustules con-
stricted at the middle; lobes with in-
flated base and truncate end ; nodules
transversely dUated ; striae distinct.
GDC. p. 48, pi. 5. f. 82. Marine. Scot-
land. Strife about 36 in -001" ; connect-
ing zone with longitudinal Unes.

A. Ifilesiana (Greg.). — Frustules
linear, with slightly constricted middle
and truncate ends, fiu'nished with longi-
tudinal lines and conspicuous transverse
strife. GDC. p. 49, pi. 5. f. 83. Scot-
land. Striae about 28 in -001", Greg.

2 * Frustules not panduriform ; nodules
transversely dilated and bar-like.

A. membrayiacea (S.). — Frustules ellip-
tic-oblong, with roimded ends ; valves
with a central transverse band, and very
close transverse strias ; connecting zone
with longitudinal lines. SBD. i. p. 20,
pi 2. f. 29 ; Ro M.T. vi. p. 24, pi. 3. f. 8.
Brackish water. Europe. (yri. 51.)
Scarcely silicious.

A. lavissima (Greg.). — Frustules very
hyaline, linear-oblong, with roimded
ends ; outer portions of valves .slender,
tapering, with a transverse nodule, and
obsolete or indistinct striae. GDC. p. 41,
pL 4. I 72. Scotland.
_ A. lavis (Greg.). — Frastules very hya-
line, linear, with subtruncate ends ; outer
portions of valves very narrow, with a
transverse nodule and indistinct striae.
GDC. p. 42, pi. 4. f. 74. Scotland. Outer
1 portion of valve canoe-shaped ; striae
I about 60 in -OOl".
_ A. minutissiina (S.). — Friustules para-
sitic, very minute, oval or suborbicular,

stinct striae ; dorsum with nimierous,
very delicate longitudinal lines. Breb.
in KSA. p. 94. Marine. France. Lateral
view lunate, with convex dorsum and
straight venter.

A. quadrata (Breb.). — Fi'ustules hya-
line, quadrangular, with tnmcate ends ;
outer portion of valve small, inflexed,
with transverse nodule ; dorsum with
numerous, very delicate longitudinal
lines. KSA. p. 95. Marine. France.
Lateral view very narrow, lunate. A.
quadrata differs from A. ostrearia by its
straight margins and tnmcate ends.

A. rectangularis (Greg.). — Frustules
nanow, linear, with truncate ends ;
valves with a transverse nodide, and 40
fine transverse striae in -OOl". Greg.
TM. V. p. 70, pi. 1. f. 29. Scotland.

A. nobilis (Greg.). — Frustules very
hyaline, barrel-shaped, with truncate
ends ; outer portion of valves very nar-
row, ai'cuato, with ti-ansverse nodule,
and fine transverse strife; dorsum with
longitudinal lines. GDC. p. 49, pi. 5.
f. 87. Scotland. Large ; striae about
40 in -001"; ventral margin of valves
concave.

A. acM<M (Greg.). — Frustules elliptic,
with truncate ends ; outer portion of
valves arcuate, witli straiglit median
line, transverse nodide, and distinctly
moniliform, trans^-erse striae. GDO.
p. 52, pi. 5, 6. f. 93. Scotland. Large :
striiB about 36 in -OOl".

A. litoralis (Donkin). — Frustules oval,
with truncate ends ; outer compartment
canoe-shaped, with distinct monilifoim
striao and transverse bar-like nodule ;
dorsum with longitudinal series of short

3 L

882

BYSXEMATIC HISTOfiY OF TRE INFUSOEIA.

transverse striae. Donliin in TMS. vi.
p. 30, pi. 3. f. 15. Maa-ine. Nortliuniber-
land. (VII. 52.)

3 * Frustules with produced or rostrate
ends and roundish nodules,

A. aponina (K.). — Frustules lanceo-
late-elliptic, with produced, tiaincate
apices, and no longitudinal lines. KB.
p. 108, pi. 5. f. 33. Italy. Minute.
1-1080" to 1-650".

A. coffeceformis (Ag., K.). — Frustules
lanceolate, with produced, obtuse apices,
strong marginal longitudinal lines, and
faint or obsolete median ones. KB.
p. 108, t. 5. f. 37. = Fricstidia coffece-
formis, Ag. ; Navictda quadricostata, E
Inf. t. 21. f. 9. /3. Fischeri, with fewer
marginal and obsolete median longi-
tudinal lines. Carlsbad. 1-1720" to
1-480".

A. acutiuscula (K.). — Frustules turgid-
lanceolate, with acuminated, subacute
apices, and strong marginal longitudinal
lines. KB. p. 108, t. 5. f 32. Marine.
Genoa. Small. 1-576".

A. lineata (Greg.). — ^Frustules elliptic-
lanceolate, with prolonged conic ends
and conspicuous longitudinal lines ;
transverse strias fine, obscm-e, about 42
in -001". GDC. p. 40, pi. 4. i. 70. Scot-
land. Outer portions of valves narrow
hmate, with convex dorsum and straight
venter.

A. Ergadensis (Greg.). — Frustules
elongated lanceolate, vdth broad, slightly-
produced, trimcate ends; transverse strisB
conspicuous, about 24 in -OOl". GDC.
T^. 40, pi. 4. f. 71. Scotland. Remarkable
for its length. Outer portions of valves
slender, with nearly straight venter.

A. exigua (Greg.). — Frustules elliptic-
lanceolate, with slightly produced, ob-
tuse ends ; transverse strife about 28 in
•001". GDC._ p. 42, pi. 4. f. 75. Scotland.
Small ; in size and form it approaches
nearest to A. lineata, but its markings
are totally different, Greg.

A. Semen, EM. pi. 38. 17. f._ 10. Ice-
land. In the figure, this species is ven-
tricose, with broad, shortly produced,
trimcate ends, and without strife.

A. salina (S.). — Frustules elliptic-ob-
long, vdth slightly produced, tinmcate
extremities; valves lunate, rostrate,
with 64 strife in -001". SBD. i. p. 19,
pi. 30. f. 251. Brackish water. Sussex.
Scarcely silicious. -0008" to -0016", S.

A. tH7-gida'(Gvep^.). — Frustules broadlj'
elliptic or suborbicular, with short ros-
trate apices ; outer portions semilimate,
with capitate apices, and 24 rather

coarse radiant strise in -001" GDC
p. 38, pi. 4. £ 63. Scotland. Small.

A. mondifera (Greg.). — Frustules
elliptic-oblong, with short, broad, ros-
trate ends ; outer portions arcuate, with
capitate, reem-ved apices; dorsum with
converging longitudmal rows of distant
dots. GDC. p, 39, pi. 4. f. 69. Scotland.

A. cymhifera (Greg.). — Frustules in-
flated, with short, subcapitate, rostrate
apices ; outer portions arcuate, -with
capitate, recm-ved ends, and 22 rather
coarse transverse sti-ise in -001'' ; con-
necting zone with converging lon<n-
tudinal bars. GDC. p. 54, pi. 6. f. 97.
Scotland. (vii. 54.) Large ; dorsum
fiu-nished with longitudinS series of
transverse stiife, separated by longi-
tudinal lines or bars.

A.proboscidea (G.). — Frustules linear-
oblong, with produced, truncate extre-
mities ; valves ai'cuate, with rosti-ate,
capitate ends, and 20 coarse ti-fmsverse
strife in -001"; dorsum with longitudinal
series of ti-ansverse strise. GDC. p. 54,
pi. 6. f. 98. Scotland. Large. The
capitate beaks of the valves are longer
than in A. cymhifera, and are not re-
cm-ved, but bent forwfirds.

A. costata (S.). — Frustules ventricoae,
with short, broad, trimcate beaks, longi-
tudinally costate ; costse with a double
line of monUiform puncta. SBD. i.
p. 20, pi. 30. f 253. Marine. Britain.
Valves semUimate, with capitate ends ;
transverse striae coarse, about 16 in
•001", Greg.

A. Terroris (E.). — Valves elongated,
sti'aight, senulunate, suddenly attenuated
into stilifoi-m beaks ; transverse .stri;v
sti'ongly gi'anulated, 19 in 1-1200".
ERBA. 1853, p. 526 ; EM. pi. 35 a. 23.
£ 2. Akin to A. fasciata, out smaller
and more strongly granulate, E.

A. macilenta (Greg.). — Frustules nar-
row elliptic-lanceolate, with sliort.
broad, sli":htly produced apices ; outt^r
portion of valves -w-ith straight ventral
mai-gin, and about 30, rather coarse
pai-idlel striaj in •OOl". GDC. p. 38,
pi. 4. £ 65. Scotland.

A. gramdata (Greg.). — Frustules
linear-oblong or elliptic-oblong, with
short, broad, trimcate, slightly produced
apices; outer portion of valve witli
straight venti-al mai-gin, rostrate apices,
and from 24 to 30 transverse sln.-e m
•001" ; dorsum having longitudinal line*
alternating with series of granides
GDC. p. 53, pi. 6. £ 96. Scotland.

A. rentricosa (Greg.}.— Frustides lan-
ceolate, witli turgid middle and tapering

OF THE CYTHBELLEjE.

883

obtuse ends; outer portions slender,
ai'cuate, with slightly concave venter,
acute ends, and about 22 conspicuous
transverse sti-ise in •001". GDG. p. 39,
pi. 4. f. 68. Scotland.

4* Frusiules neither constricted at the
middle nor rostrate at the ends ; nodides
roumlish.

A. ovalis (K.). — ^Frustules turgid, oval,
with broadly rounded or truncate ends ;
outer portion of valves canoe-shaped,
with 24 distinct nioniliform stiiis in
•001" ; connecting zone with very fine
longitudinal lines. KB. p. 107, t. 5.
f. 35, 39. = Namcula Amphora, E Inf.
t. 14. f. 3. Fresh water, frequent. Eu-
rope, Africa, (vn. 56 ; ix. 153.) Large.
1-456" to 1-120".

A. Libyca (E.). — Frustules oval, with
with broadly rounded or truncate ends ;
lateral view semilunate, vnth very con-
vex dorsum, obtuse ends, and slightly
concave venter. EA. t. 3. 1. f. 42 ; EM.
many figures. Appai'ently the most
common species, since Ehrenbero' gives
upwards of 100 habitats for it in Europe,
Asia, Africa, and America. LougJi
Mourne deposit. (xn. 38.) We ai-e
unable to distinguish this foi-m fi-om A.
ovalis, and probably these have been
confounded ; we believe they are in
SBD., because there no species but A.
avails is noticed as occiu'ring in the
Lough Moui-ne deposit, whilst Ehren-
berg only mentions this species as found
in it. Ehrenberg's figures and descrip-
lion do not enable us to decide ; for the
latter is too indefinite, and the former
vary so much as apparently to belong to
more than one species. Almost the only
characters the figures have in common
are the oval form and striated valves.
The median line is either concave,
! straight, or produced at the nodule ; and
I the connecting zone is figured sometimes
smooth, and sometimes with longitudinal
lines.

A. pellucida (Greg.). — Frustules very
hyaline, oval, - with broadly rounded
ends ; outer portions of valves canoe-
' shaped, with about 30 very delicate strise
in -001". GDC. p. 41, pi. 4. f. 73. Scot-
land. Resembles A. ovalis in foi^m, but
1 differs in its niaiine habitat, very hyaline
I ^ect, and singular delicacy of the stiiro.
I The latter characters distinguish it also
from A. incurva, Greg.

A. truncata (Greg.).— Frustides bai-rel-
shaped, with truncate ends ; outer por-
; nons of valves canoe-shaped, striated ;
' dorsum with longitudinal aeries of short

transverse stiife. GDC. p. 43, pi. 5.
f. 77. Scotland. Larg^.

A. lineolata (E.). — Frustules turgid,
eUiptic-oblong, with truncate apices,
sti'ong longitudinal marginal lines, and
very fine ones in the connecting zone. E
Inf. 1. 14. f. 14; EM. pi. 13. 1. f. 19 ; Rab
D. pi. 9. f. 9, 10. Fresh water. Europe,
Africa, America. 1-480" to 1-140". The
figures referred to represent the fr-ustule
as large, baiTcl-shaped, with canoe-
shaped outer portions.

A. Ch-egorii. — Frustules barrel-shaped ;
outer portions canoe-shaped, with about
34 transverse stiise in^OOl"; dorsum with
longitudinal series of short transverse
striae. quadrata, GDC. p. 49, pi. 6.
£ 85. Scotland. Ends truncate.

A. Ch-evilliana (Greg.). — Frustules
broad, linear, oblong or barrel-shaped;
outer portidns canoe-shaped, with from
28 to 34 distinct, monilifoi'm transverse
striae in -001" ; dorsum with lono'itudinal
series of transverse striae. GTM. v. pi. 1.
f. 36 ; GDC. p. 50, pi. 5. f. 89. = coni-
pZea;a,GDC. p.51, pl.o. f. 90 ; A. fasciata,
GDC. p. 51, pi. 5. f. 91. Scotland.' Large;
ends trimcate.

A. sulcata (Br^b.). — ^Frustules hyaline,
oblong or elliptic- oblong, with truncate
ends ; outer portions canoe-shaped, with
38 transverse striae in •OOl" ; dorsum
with longitudiaal series of ti'ansverse
stiiffi. BD. pi. 18. f. 8 ; GDC. p. 51,
pi. 5. f. 92. France, Britain. Large ;
dilFers from A. costata in its not produced
but truncate apices, Brt^b.

A. robusta (Greg.). — ^Frustules broadly
oval, with rounded ends and canoe-
shaped outer portions ; ti'ansverse striae
distinct, monilifoi-m, 16 in 'OOl". GDC.
p. 44, pi. 5. f. 79. Scotland. Large ;
conspicuous fr'om its size and stoutness.

A. Protem (Greg.). — Frustules barrel-
shaped or oblong ; outer portions canoe-
shaped, with 22 fijiely monilifomi trans-
verse striae in •001". GDC. p. 46, pi. 5.
f. 81. Scotland. Large, with truncate
apices. Varies much in form and length.

A. Arcus (Greg.). — Frustules barrel-
shaped; outer portions naiTow, canoe-
shaped, with 16 to 18 coarsely monili-
fonii stiise in •OOl" ; dorsum with longi-
tudinal series of nioniliform transverse
8tria3. GMJ. iii. pi. 4. i" 4 ; TM. v. pi. 1.
f. 37 ; GDC. p. 50, pi. 5. f. 88. Scotland.
Largo, with truncatt* ends. The frustule
has the form of a baiTcl, with ribs and
bars. It is distinguished fi-om A. Gre-
villiana by its coarsely nioniliform strire.
Detached segments resemble in fom a
strung bow with rostrate apices,
3 L 2

884

SYSTEMATIC HISTORY OF THE INFUSOBIA.

A. vmeta (K.). — Frustules minute,
elliptic-oblong, witli truncate ends ;
lateral view semielliptic. KB, p. 108,
t. 3. f. 25. Marine. Venice and Con-
stantinople.

A. borealis (K.). — Frustules minute,
oblong-lanceolate, witb acute or ti-un-
cate apices; lateral view semilanceolate.
KB. p. 108, pi. 3. f. 18. Heligoland.
1-1200".

A. Hohcnaclieri (Rab.). — Frustules
minute, oblong or oblong-lanceolate,
with three longitudinal lines on each
side. BabD. p. 31, pi. 9. f. 11. South
Persia.

A. hyalina (K.). — Frustules hyaline,
elliptic-lanceolate, with acute or trun-
cate apices, and a few, very delicate
longitudinal lines; ti-ansverse sti'ise ob-
scure. KB. p. 108, pi. 30. f. 18 ; SBD.
i. p. 19, pi. 2. f. 28. Marine. Em-ope.
(vn. 58.) Imperfectly silicious. 1-600"
to 1-422".

A. nana (Greg.). — Frustules small,
nan'ow elliptic-oblong, vrith roimded
ends ; outer portions with straight ven-
tral margin, and about 50 ti-ansverse
sti-i£B in -001". GDC. p. 38, pi. 4. f. 64.
Scotland.

A. elliptica (Ag., K.). — Frustules
small, elliptic-lanceolate, tiu-gid at the
middle, with attenuated obtuse apices ;
valves distinctly striated. KB. p. 108,
t. 5. f. 31. = Cymhella elliptica, AD. p. 8.
Marine. Baltic. Associated in amor-
phous mucus, K.

A. navicularis (E.). — Frustules ellip-
tic-lanceolate, with subacute ends and
conspicuous transverse stiiae. EA. p. 122,
t. 1. 1. f. 12. Africa, America, (xii. 37.)

A. gracilis (E.). — Frustules small, nar-
row oblong, ti'uncate; valves slender,
transversely sti'iated. EA. t. 3. 1. f. 43 ;
EM. t. 37. 3. f. 1. Europe, Asia, Afi-ica,
America, Australia, (xn. 26.) Outer
portion of valve lunate.

A. affinis (K.). — Frustules oblong,
slightly attenuated, with rounded or
broadly truncate apices, marked with
longitudinal lines, the centi-al ones very
faint. KB. p. 107, t. 30. f. 66. France,
Britain. 1-960" to 1-390".

A. marina (S.). — Frustules elliptic,
with somewhat trimcate extremities ;
nodule very faint; strioe 40 in -OOl".
ANH. 1857, xix. p. 7, pi. 1. f. 2. Marine.
France, Britain. -0006" to •0024".
(vn. 59.) Not unfrequent, but has been
overlooked from its exact resemblance in
outline to A. affinis; it may be known
by its more delicate strire and inconspi-
cuous nodules, Sm.

A. duhia (Greg.).— Frustules oblong,
•with broadly rounded ends ; outer por-
tions stout, with concave venter, obtuBe
ends, and 24 fine transverse striaj in
•001". GDC. p. 42, pi. 5. i. 76. Scot-
land. It has some analogy with A,
manna ; but tlie striation is coarser, and
nodides distinct, Greg.

A. oblonga (Greg.). — Frustules elon-
gated linear-oblong or eUiptic-oblong,
with conic apices ; outer portions vely
naiTow, canoe-shaped, with conspicuous
nodule, and 24 distinct transverse striaa
in •OOl". GDC. p. 43, pi. 5. f. 78.
Scotland. Large.

A. elongata (Greg.). — Frustiiles elon- ■
gated, naiTow, oblong-lanceolate, trun- •
cate ; outer poi-tions very narrow, canoe- ■
shaped, with 26 conspicuous ti-ansverse ■
sti-i£e in •OOl" ; dorsum with longitudinal 1
lines. GDC. p. 49, pi. 5. f. 84. Scotland. .
Large.

A. angusta (Greg.). — Frustules nai- •
row linear-oblong, truncate ; outer por- -
tions ■with 44 fine tiansverse strias in
•001". GDC. p. 38, pi. 4. f. 66. Scot- ■
land.

A. obtusa (Greg.). — Frustiiles broad i)
linear-oblong, with broadly roimded
ends ; outer portions canoe-shaped, with bit
70 very fine transverse stiise in -001". ]
Greg. TM. v. pi. 1. f. 34. Scotland,!
Large.

A.plicata (Greg.). — Frustules hyaline,
broad lineai'-oblong, -with rounded an- ,
gles and ti-uncate apices ; outer portion
canoe-shaped, very faintly steiated;
dorsiun with longitudinal Imes. Greg.:
TM. V. pi. L f. 3L Scotland. Large.-
The longitudinal lines give a plicate '
appearance to the frustule, Greg.

A. crassa (Greg.). — Fi-ustules linear
or linear-oblong, -with roimded or sub-
truncate apices; outer portions canoc-
shaped, with fi'om 12 to 20 coarse trans-
verse strio3 in -001" ; dorsum with longi-
tudinal series of transverse stria?. GDC
p. 52, pi. 6. f. 94. =A. sulcata, Ho. MJ, t
vi. p. 18, pi. 3. f. 7 ?. Britain. Large. |

A. spectabilis (Greg.). — Finstule.s I
broad linear or linear-oblong, with 4
roimded angles and subtruncat* apices :
outer portions canoe-shaped, ■vvith 14 U
16 distinct tiansverse stria3 in -001":
dorsum with longitudinal series of tran^
veree stiire. GDC. p. 44, pi. 6. f. 80^
Scotland, (yn. 57.) Large.

A. excisa (Greg.).— Fi-ustulea hyalmej
broadly linear or linear-oblong, truncate
appearing notched at the sides from tin
marginnrposition of the nodides; outo
portion canoe-shaped, witli 52 very niT

OF THE CTMBELLE^.

885

transverse strise in •001"; dorsum with
longitudinal series of short sti-iue. GDC.
p. 49, pi. 5. f. 86. Scotland.

A. arenaria (DonMn). — Frustules hya-
line, broadly linear, with rounded angles
and slightly gibbous middle ; outer com-
partment of valves canoe-shaped; dorsum
faintly marked with longitudinal lines.
Donkin, TMS. vi. p. 31, pi. 3. f. 16.
Marine. Northumberland. Large; ti-ans-
verse striae obscui'e.

A. amphioxijs (Bailey). — Frustules
linear, with subtnincate apices ; lateral
view arcuate, finely sti-iated, with convex
doi-sum, concave venter, and rosteUate
recurved exti-emities. BMO. p. 39, pi. 2.
f. 20-22. United States. The side view
bears a striking resemblance to Eunotia
amphioxys, Bailey.

A. biscriata (Greg.). — ^Frustules elon-
gated linear, with roimded apices ;
median line marginal, except at the
centre, where it curves inwards; dorsum
with longitudinal series of coarse trans-
verse strife. Greg. TM. v. p. 71, pi. 1.
f. 32. Scotland. Lar^e.

A. tenera (S.). — Frustules narrow
linear, with roimded or trimcate ends ;
valve longitudinally rugose ; strice ob-
scure, 62 in -001". SBD. i. p. 20, pi. 30.
f. 252. Marine. England. Scarcely
silicious. Professor Smith regarded this
species as the^. lineolata, E., — an opinion
in which we are imable to concur, since
its narrow-linear foi-m is very imlike the
broad inflated figm-e of the latter, and
could never be described as tm-gid.

A. hacillaris (Greg.). — Frustules nar-
row linear, with slightly attenuated, ob-
tuse ends, outer portions very narrow,
arcuate, finely striated; dorsum with
longitudinal series of granules. GDC.
p. 55, pi. 6. f. 100. Scotland. Distin-
guished from A. pu&illa by its finer striaa
and granules, Greg.

A. piisiUa (Greg.). — Frustules narrow
linear, with subtnmcate apices ; outer
portions very narrow, canoe-shaped,
with 24 conspiciious stiia) in -001";
dorsum with longitudinal series of gi-a-
nules or short stnte. GDC. p. 53, pi. 6.
f. 95. Scotland.

A. Urebi (E.). — Lateral view arcuate,
t with obtuse apices, concave venter, and

about 25 very fine striiB in 1-1200".
ERBA. 1853, p. 526 ; EM. pi. 35 a. 23.
f. 3. Assistance Bay, North Pole.

A. aystallwa(E.). — Frustules smooth,
crystalline, with convex dorsum, concave
venter, and broadly tiomcate ends.
ERBA. 1840, p. 10. Tjom. 1-432".

A.fasctata (E.). — Frustules with con-
vex dorsum, plane venter, broadly ti'un-
cate ends, and lon^tudinal series of
closely set, fine strise. ERBA. 1840,
p. 11. Tjom. 1-456".

A. carinata (E.). — Frustules large,
navicular, with plane sides, acute apices,
and four lateral striated fasciae. ERBA.
1840, p. 10. Island of Tjorn. 1-240".

A. Atomus (E.). — Veiy minute, on
one side elliptic with rounded ends, on
the other linear and trimcate. 1-2640".

A. ^gcea (E.). — Frustules navicular,
oblong, truncate, with 10 pimctated
longitudinal lines, oblong umbilici, and
curved lines; the space between the
umbilici with two straight lines cm'ved
at each end. ERBA. 1858, p. 13.
^gean Sea.

A. stauroptera (Bailey). — Frastules
elliptical, elongated, with striated mar-
gins ; centi'al portions crossed, as in
Staiu'optera, by a broad band. BC. vii.
p. 8, f. 14, 15. Halifax, Nova Scotia. The
figure is elongated, acutely lanceolate,
and the nodules connected by a ti'ans-
verse central depression.

Species, the descriptions of which are
tmknown to us.

A. cymhiformis, EM. pi. 16. 1. f. 43.
Lateral view semilunate, with convex
dorsum, straight venter, obtuse apices,
diverging striae, and submarginal sutural
line and nodule.

A. gigas, EM. pi. 6. 2. f. 13. North
Afiica. Figm-e imperfect, large, oval,
transversely striated ; connectmg zone
with faint longitudinal lines.

A. incurva, Greg. MJ. iii. pi. 4. f. 5.
Scotland. Lateral portion canoe-shaped
and finely striated.

A. paradoxa (E.), A. vulgaris (E.),
Asia ; A. Niloiica (E.), River Nile ; A.
ocellata (E.), Florida.

Genus RHIZONOTIA (E.). — Fnistulcs mth two median nodules (Avith
the character and form of Amphora), but by longitudinal division often
becoming a mass united together in a longitudinal series by a progeny of
stolons or silicious radicles. This form is adnate on Confervte, and has many
fine longitudinal strisc, which appear somewhat rough or granidar. The

886

SYSTEMATIC HISTORY OF THE INFU80H1A.

frustnle is very crystalline and transparent. It has internally pale-green
almost colourless ova, E.

Ehizonotia Melo (E.). — The lateral
coimecting portions of the progeny in
self-division mostly forked, 3 to 10.
ERBA. 1843, p. 139. = Rhizosolenia

Mdo, EM. pi. 35. 6. f. 14, 15 ?. Swan,
Avon, and Canning Rivers in Western
Australia, (yiti. 41.)

FAMILY XVII.— GOMPHONEME^.

Frustules in front view cuneate, laterally attenuated at the base, "with a
median longitudinal line and a central nodule. Mostly aquatic. The Gom-
phonemeae differ from the Meridiese and the Licmophorese, and the cuneate
species of SurireUa, by the median longitudinal line and the central nodule.
The cuneate form in the front view distinguishes it from the rest of the
Diatomaceae.

Genus SPHENELLA (K.). — Erustules in front view cimeate, free, neither
stipitate, afiixed, nor enclosed in a common gelatinous substance. Aquatic.
" The Sphenellse only differ from Naviculse in their cuneate form, perfectly
similar to that of Meridion, by which, too, the associations {8. angustata)
become flabeUiform and quasi- circular ; but they differ by the central nodule
of the lateral surfaces. Hence there remains a greater similitude to the
Naviculse ; and the distinctive characters are so slight, that the generic
characters of at least two species remain uncertain " (Menegh. p. 411).

Sphenella glacialis (K.). — Minute ;
lateral view lanceolate, with subacute
ends and very delicate ti'ansverse strife.
KB. p. 83, pi 3. f. 16. Monte Rosa,
Alps. 1-1320".

S. parvula (K.). — Miuute ; lateral view
lanceolate, with produced ends, the base
subdilated. KB. p. 83, pi. 30. f. 63.
France. 1-960". Striae indistinct. It
cannot be distinguished from a Navicula,
except on a front view.

S. angustata (K.). — Minute, flabel-
lately conjoined, naiTow lineai', cimeate,
lateral view lanceolate, with obtuse
ends. KB. p. 83, pi. 8. f. 4. Gennany,
Fi-ance. (xiv. 30.) 1-960".

S. vulgaris (K.). — Small j lateral view
finely striated, dilated at the middle,
and tapering to the stout beak-like

ends. KB. p. 83, pi. 7. f. 13. Germany,
France. 1-1020".

S. obtusata (K.). — SmaU ; lateral
view smooth, dilated above the middle,
with roimded obtuse apices. KB. p. 83.
pl.9. f. 1. Prussia, (xiv. 31.) 1-900".
Lateral view clavate-lanceolate.

S. rostellata (K.). — Solitary, smooth,
broadly cimeate ; lateral view dilated^ at
the middle, acuminate at each end. KB.
p. 83, pi. 9. f. 3. /3. ehngata, larger,
vsdth produced, obtuse apices. France.
1-1820" to 1-336".

S. ? Italica (K.). — Broadly cimeate :
lateral view obovate, slightly dilated at
the middle, and with a ti-ansverse me-
dian nodule. KSA. p. 63.^= Gompho-
tiema Italicum, KB. t. 30. f. 75.

Genus GOMPHONEMA (Ag.).— Fnistules affixed at the base or stipitate :
in front view cuneate ; laterally attenuated below, with a median longitudinal
line and central nodule. " As Cocconema fi-om Cymbella, so Gomphonema
only differs from Sphenella by the stipes, on which account species are now
referred to Gomphonema which formerly belonged to Sphenella. . . . Kiitrng
supposes the Gomphonemae to be at first fi-ec, lilce Sphenella, and that after-
wards they affix themselves. ... No direct observation coirfirms tlus hypo-
thesis ; and it is at least as just to admit the other, that the SphcnellfE are at
first attached like the Gompiionemoc and afterwards become free. Ehronhcrg
says that the Gomphonemae can become free and again adlicre " (Mcn^h.
p. 412). The descriptions apply to the lateral view, unless otherwise stated.

OF THE GOMPnOlTEME^.

887

* JF)'ustules in lateral view constncted be-
neath the apex, appearing urn-shaped.

t Lateral view witli the head apiculate
or acute.

GoMPHONEMA coronatum (E.). — Slen-
der, with ventiicose middle, obcordate
apiculate head, and lanceolate base ; front
view crested at apex. EM. pi. 6. 1. f. 33.
= G. acuminatum /3, SBD. i. p. 79, pi. 28.
f. 238 /3. Eiu'ope, America, Asia, Aus-
tralia, (xiv. 36.) G. coronatum is di-
stinguished from the allied foi-ms by its
inflated basal portion; but the lower
inflation is sometimes very obscm*e, and
we believe Professor Smith was justified
in regarding this form as a mere variety
of G. acuminatum. 1-480".

G. laticeps (E.)". — Habit of G. corona-
tum, but shorter, and head wider than
the central inflation. EM. pi. 5. 1. f. 34.
America, Asia. Ehrenberg's figures have
the basal portion linear, not inflated.
He gives about fifteen habitats.

G. Sceptrum (Eab.). — Habit of G.
coronatum, but larger and more robust,
: the middle more inflated and much
; broader than the obcordate apiculated
i head; base stalk-like, not inflated. RabD.
' p. 60, pi. 8. f. 8. America.

G. acuminatum (E.). — Slender, taper-
ing below into the stalk-like base, con-
stricted above the ventiicose middle;
head dilated, acuminate. SBD. i. p. 79,
pi. 28. f. 238. = G. trigonocephalum, EM.
pi. 6. 1. f. 36 ; G. appendiculata, Perty KL.
p. 204, t. 17. f. 12. Em-ope, Asia, Africa,
i America, and Austi'alia. (xm.23.) Difiers
from the foregoing species by a cimeate
or tapering apex. In a variety figTired
by Professor Smith the constriction is
nearly obsolete. 1-860" to 1-430''.

G. Brehissonii (K.). — Slender, narrow,,
with a longly attenuated base and a
slightly ventncose middle, separated by
a slight constriction from the cimeate,
attenuated, somewhat obtuse head. KSA.
p. 66. France. Stipes abbreviated or
nearly obsolete. Akin to G. acumina-
tum, but more slender, more elongated
into the stipes-like base, and head and
median inflation smaller.

G. Americanum (E.). — Lateral view
with three inflations, separated by two
' constiictions ; head ovate, subacute.
EM. several figures. America, Iceland.
1-864".

G. elongatum (S.). — Lateral view vrith
three inflations, the median one greatest ;
upper one oblong, with cimeate apex ;
lower slender, slight. S. in ANH. 2 ser.
XV. p. 6, pi. 1. f, 4.= G'. Brdbissonii, Greg.

MJ. ii. pi. 4. f. 18. France, England.
1-864", Scarcely distinct from G. Ame-
ricanum ; both have the inflated base of
G. coronatum, and cuneate head of G.
acuminatum.

2 1 Head roimded, neither acute nor
apiculate.

G. gemhiattmi (A.). — Frustules very
lai'ge, in fr'ont view cimeate, their ter-
minal pimcta obsolete ; lateral view in-
flated at the middle, constricted above
and below, with dilated, rounded ends ;
striae distinctly moniliform. SBD. p. 78,
pi. 27. f. 2S5. = Diom2}hala Clava Her cutis,
EM. pi. 15 a. f. 93. (vn. 60.) On rocks
in subalpine streams. Em-ope. This
species forms large spongy cushion-like
tufts composed of densely matted fila-
ments. The fi'ustules are easily recog-
nized by their large size, the .absence of
terminal pimcta in the front view, and
the conspicuous stiise of theii* lateral
valves. The neck is much consti'icted,
and the large head broadly rounded at
the end. Kiitzing refers G. Herculeanum
(E.) to this species, but, we believe,
erroneously.

G. capitatum (E.). — Lateral view tur-
gid at the middle and slightly con-
stricted beneath the broadly rounded
head ; puncta in fr'ont view evident.
SBD. p. 80, pi. 28. f. 237. = G. turgidmn,
EM. pi. 2. 2. £40:' Eiu-ope,Asia. 1-1720"
to 1-280". Striated, attenuated at its
base ; stipes elongated, dichotomous.
Sometimes the consti'iction, which is
less marked than that of the next spe-
cies, is nearly obsolete, and the fi'ustides
in the lateral view ai'e obovate.

G. constrictum (E.). — La.teral view
ventricose at the middle, Math a short
neck and broadly roimded head ; pimcta
at upper end of front view very evident.
SBD. pi. 28. f. 236.= G. truncatum, EM.
many tigm-es ; G. paradoxum, EM. pi. 9. 1.
f. 33, 34; G. pohliceforme, K., Eiafs.
Forms a brown discoloration on aquatic
plants. Common, (x. 187-190.) 1-1720"
to 1-280" ; stiiated, attenuated at its
base ; stipes becoming elongated and
branched. Distinguished from G. gemi-
natum by its much smaller size and
distinct puncta in fi-ont view. We find
this species very vai'iablo in the develop-
ment of its neck; and sometimes in a
young state the constriction is but slight,
and the form resembles G. capitaium.

G. subtile (E.). — Slender, lateral view
twice constncted; head small, obtuse;
neck slender, elongated. EM. several
figures, Asia, Africa, America, Lough

I

888

SYSTEMATIC HISTOEY OF THE 1NFU80EIA.

Moume deposit. It differs from G. con-
strictum iii its more slender fonii and
longer neck.

G. AtKjUcum (E.). — Twice constricted ;
head rounded, rather narrower than the
oblong inflated middle, which tapers
below into a linear stipes-like base. EM.
pi. 15 A. f. 86, Lough Mom-ne deposit,
Ireland, It is allied to G. subtile. Pro-
bably both forms should be imited to
G. constrictum.

G. Mustela, EM. pi. 17. 2. f. 37. Fossil,
Knland, France; recent, Berlin. We
have seen no description of this species.
Ehrenberg's figures represent the lateral
view elongated, with an oblong median
inflation, tapering below into a linear
stipes-like base, and above into the ob-
long head, which is rounded at the apex.

2* Frustules imbedded in a shapeless gela-
tinous substance. (GomphoneUa, Rab.)

G. olimceum (Lyngb., E.). — Frustules
and stipes forming a gelatinous mass;
front view broadly cimeate, with con-
spicuous terminal pimcta ; lateral valves
obovate or subclavate, distinctly stri-
ated, SBD. pi. 29, f. 244. = GomphoneUa
olivaccMm, Rab., j3. anqusta ; G. angusta,
K. ; G. ancjusta, Rab D. p. 61, t. 9. f. 2.
Smaller and shorter, with obsolete strife.
Europe. 1-2300" to 1-1020". It foi-ms
rather large mucous masses of a pale
brown colour, which, when dried, be-
come pale green with a granulated
appearance.

G, Lenormandi (Chauvin). — Front
view narrow, nearly linear ; lateral
valves lanceolate acute, with indistinct
strias. KSA. p. 65. = Sphenella P Lenor-
mandi, KB. pi. 30. f. 61 ; GomphoneUa
Lenormandi, Rab. Falaise, France.
1-960", Stipes slender, at length elon-
gated.

Q. parvulum (K.). — Frustules of the
size and form of Sphenella parvula, but
stipitate and aggregated into a dense
mucous stratum. liSA. p. 65, = Gom-
phoneUa parvula, Rab.

3 * F)-ustulcs in front view curved, tvtth
two longitudinal suture-lihe lines or
vittcB.

G. curvatimi (K.). — Frustules in front
view cm-ved, with distinct terminal
puncta and longitudinal vittas; lateral
valves clavate. KB. p. 85, pi. 8. f. 1-3.
= G. mimdissimum, E. Common. Eu-
rope, Asia, Africa, America, (xii. 9-12 ;
xrn. 11.) a, aquatic, = G. curvnlitm,
SBD.; /3, mai-ino,= G, tnarinum, SBD,

This species difiers considerably from
the other species of Gomphonema m its
curved frustules and longitudinal suture-
like sti'ise, and perhaps ought to be sepa-
rated fr-om them. It agrees ^vith Rhi-
pidophora in the latter character and
with Achnanthes in having a median
nodide in the ventral or concave valve
only. It varies in its mode of growth,
according as it is found in fresh, brack-
ish, saline, or marine waters. The frus-
tules are scattered, flabeUately conjomed,
or aggregated in minute cushion-like
tufts. The stipes is short, incrasisated,
and in-egularly branched, or more or less
elongated, slender, and dichotomously
divided. Professor Smith makes the
marine fonn a distinct species, and gives
the following differential characters: —
G, citrvatum : " Stipes elongated, fila-
mentous and dichotomous; striae 22 to
30 in -OOl'" ; aquatic," G. marinum :
" Stipes incrassated, branching in an
iri'egidar manner; striae 35 in -OOl"';
marine." Professor Smith, however,
admits that it is difficult to distinguish
them if we confine om- attention merely
to the fr'ustules; "but," continues he,
" the general appeai-ance of the growing
plants, ai'ising fi-om the chai-acters of
their stipes, is veiy different, and their
habitats are so wide apart that there can
be no doubt of their distinctness." We
are imable to concur in this opinion ; for
our experience is quite diflerent, and, as
we stated several j'eai-s ago, we find the
stipes in the marine form more elon-
gated than in the aquatic one. " I have '
attempted in vain to find some specific I
chai-acter to distinguish the marine foim i
It is more branched, has a rigid appear- t
ance, and the strife connecting the puncta . ■
on the fi'ont suiface are strongly mai'ked ; <
but inteimediate specimens occasionally I
occm', in which all these differences •!
vanish " (ANH. xii.).

4 * F)-ustules in hteral vieto obovate or
clavate.

t Crested or pointed at the apex.

G. cristatum (Ra.). — Frout-viewcrested; ;
lateral view obovate, crowned with a«
minute point. SBD. p. 79, pi. 28. f. 239. i
= G. nasutum, EM. pi. 2. 2. f. 41 ; Sfthe- ■
nella ? appendiculata, Perty, p. 203, 1. 17.
f. 14. Europe, Asia, Amenca. Stipes*
nearly simple; frustides in front view"
cuneate, ^vith somewhat roimded angles, i
crested as in G. coronatum ; tenninal i
puncta obsolete. Ehrenberg describes!
his G. nasutum as allied to G. Augttr,'

I

OF THE GOMPHONEMEiE.

889

but shorter and stouter. To O. erktntum
probably belongs the Mexican form de-
scribed "by Ehrenberg as a variety of
G. Augur, haying the apex constricted
into a small terminal nnicro.

G. Augur (E.). — Front view lineor-
cuneate, lateral view rhomboid, with
subacute apex and acuminated base.
EM. several figm'es. Em-ope, Asia,
Australia, Africa, America. 1-960".
"More slender and with sharper point
than G. cristatum," Rab. Professor
Kiitzing imites G. cj-istakcm to this spe-
cies; and certainly they, as well as G.
Lagenula, seem closely allied. Ehren-
berg's figiu-es vary considerably in form,
but all have the apex more cuneate than
we have ever seen it in G. o'istaturn.

G. Lagenula (K.). — Slender, linear-
cuneate, finely striated; lateral view
clavate, crowned with a minute point,
tapeiing and subacute at base. KB.
p. 85, pi. 30. f. 60. = G. spheeraphoriim, EM.
pi. 35 A. 7. f. 14. America, Eui-ope.
Stipes short. 1-720". This fonn ap-
parently differs from G. cristatum only
m its naiTower frustule.

G. apiculatum (E.). — Cuneate ; lateral
view obovate, with acute cimeate apex
and tapeiing base. EM. pi. 4. 2. f. 39.
Fossil. America, (xn. 28 & 53.) 3
more slender than G. apiculatum : EM.
pi. 2. 2. f. 43.

G. Turris (E.). — Much elongated,
clavate, its apex suddenly acutely cu-
neate. EM. several figui-es. Afi-ica,
America, India, Japan. Ehrenberg's
figiu-es vary in fonn, but are mostly
clavate, with or without a slight con-
striction above the middle. "Akin to
G. gracile, but stouter," E.

2 1 Apex in lateral view neither acute

nor apiculate.
■ G. ahbreviatum (Ag.). — Fnistules
broadly cuneate, conjoined in a flabel-
late manner ; lateral view obovate, with
indistinct strise and rounded apex. KB.
p. 84, pi. 8. f. 5-7. = EchineUa ahbreciata,
Ehr. 0. longipes (K.), stipes elongated ;
subbranched, = G. rotundatum, E. Eu-
rope, Asia, Australia, America. 1-1152"
to 1-840". Stipes rather thick, usually
very short and simple, but in var. ^
more elongated.

G. sphenelloides (Rah.). — Obovate,
smooth, with broadly rounded apex;
stipes simple, stout. Ilab D. p. 58, pi. 8.
f. 1. Italy. Front view cuneate. Pro-
bably only a form of G. ahbreviatum.

G. micropm (K.). — Front view lineai--
cuneate, truncate at each end; lateral

view obovate-lanceolate. KB. p. 84,
pi. 8. f. 12. Germany, France. Very
finely striated ? ; stipes very short and
obsolete, or elongated filifomi and sub-
ramose. " Resembles G. s2}henelloides,
but is smaller and more slender," R. /. c.

G. tenellum (K.). — Minute, smooth ;
lateral view obovate-lanceolate; stipes
abbreviated, simple. KB. p. 84, pi. 8.
f. 8. Em-ope. 1-1440".

G. Persicum (Rab.). — Lateral view
obovate, with rounded upper end, stri-
ated ; fi-ont view broadly cimeate. Rab D.
p. 59, pi. 8. f. 4. Persia. The figure re-
presents the front view with conspi-
cuous terminal puncta and longitudinal
vittffi or suture-like lines.

G. Hercynicum (Rab.). — Lateral view
obovate-lanceolate, with obtuse ends,
the upper one cimeate ; strise distinct ;
£i-ont view broadly cimeate. Rab D.
p. 59, pi. 8. f. 28.

G. subramosum (Ag.). — Lateral view
clavate ; fi-ont view cuneate, with acute
base ; stipes long, slender, nearly simple.
KB. p. 85, pi. 8. f. 15. = G. septatum, A^
CD. ; G. oculatum, KSA. ; G. discolor and
G. clavatum, E. (according to Kiitzing).
Common. Em-ope, Asia, Afi-ica, Ame-
rica. 1-1140" to 1-600". Strife very
faint. We quote G. clavatum (E.) under
this species in deference to Kiitzing's
authority, because the description -^tII
not detei-mine the question ; and although
Ehrenberg, in his 'Microgeologie,' figures
it from more than twenty stations, yet
those figiures differ so gi-eatly as to aftbrd
no decisive information : several of them
are lanceolate or clavate, whilst, like G.
Glaus (a species indeed described as
having a general resemblance to G. clava-
tum), the gi-eater nimiber have an inflated
centre.

G. erosum (Rab.). — Oblong-obovate,
with emarginate apex ; front view
naiTow-cuneate ; stipes dichotomously
di\aded. Rab D. p. 59, pi. 10. f. 12.
Dresden.

5 * Frustulcs in lateral view ventricose at
the middle, attcmiated at each end.

G. Glans (E.).— Ovate-oblong, tumid ;
upper end rounded, with a slightly tu-
mid neck. EM. pi. 4. 2. f. 35. lias a
general resemblance to G. clavatum, but
IS shorter, stouter, and more obtuse.
Ehrenberg's figures represent it witli
ventricose centre, broadly conical above
with rounded apex, and tapering below
into a short, slenderer base.

G. Oregonicum, EM. pi. 37. 2. f. 12, 13.
Fossil. Oregon. Ehrenberg's figure of

890

SYSTEMATIC HIST0E1

OF THE INFUSOEIA.

the lateral view has an oblong inflated
centre, suddenly constricted above into
a cone with rounded apex, and taper-
ing below into a slender base ; the front
view is large, broadly cuneate, with
striated lateral margins, rounded base,
and conspicuous piincta at upper end.
It differs fi-om G. Glans in its larger size
and more elongated inflated centre.

G. Mamilla, EM. pi. 37. 2. f. 10. Ore-
gon. Ehrenberg's figui-e of the lateral
view resembles G. Oregoniciim, but is
stouter in proportion to its length, and
the basal end is shorter and more
truncate.

G. giganteum (E.). — Very large and
tiu'gid, distinctly striated, lanceolate,
the subacute apex rather more acute
than the base. ERBA. 1852, p. 534.
Recent. California. It is more akin to
G. Mamilla than to G. Herculeanum,
but diflers in its larger size and slenderer
base. Centre inflated.

G. Herculeanum (E.). — Very large,
minutely striated, oblong, inflated at the
middle ; the ends attenuate and roimded,
the basal one slenderer. EM. pi. 35 a.
7. f. 12, 13. Lake Michigan, Niagara,
and Oregon. Stipes long, hyaline, dicho-
tomous ; length of frustule 1-216". Pro-
fessor Kiitzing imites this form to G.
geminatum; but according to Ehrenberg's
flgirres, they are very di fferent. The upper
end is figured in this species as broadly
conical, not dilated into a head as in
G. geminatum. The front view is repre-
sented as more eimeate, and fmnished
with conspicuous puncta at the upper
end.

G. intricatum (K.). — Inflated at the
middle, much produced at each end,
narrow, obtuse ; stipes rather rigid, mu-
cous, extremely interwoven, dichoto-
mous. KB. p. 87, pi. 9. f. 4. Germany.
Forms a firm slimy stratum on rocks.
1-420". This species is described and
figured by Kiitzing and Rabenhorst as
slender, with inflated centre, whilst Smith
describes the British forms as lanceolate,
— a diflerence which renders their iden-
tity problematical. Front view narrow-
cuneate.

G. longiceps, EM. pi. 7. 3 b. f. 9. Appa-
rently common, since Ehrenberg gives
thirty-eight habitats in Eiu'ope, Asia,
Austi-alia, Africa, and America. "VN'^e
have seen no description of this species ;
the figiu'es represent it as narrow-cune-
ate in the front view, and the lateral
\ie-w striated, inflated at the centre, with
the ends elongated into beaks, the apex
obtuse, and the base truncate.

G. veiitricosum (Greg.). — Much in-
flated at the centre, upper end conical,
lower slender, constricted above the
roundish base. Greg. MJ. p. 4, pi. 1. f. 40,
Scotland. -0013" to -0018". This form
much resembles G. Glam; the base, how-
ever, is dilated and roimded — characters
wanting in the figures of that species.

G. Cygnus (E.). — Nan'ow, with a lan-
ceolate inflated centi-e, and linear, elon-
gated, beak-like exti'emities. EM. pi. 5.3.
f. 33. America, Asia. Obtuse at apex,
and trimcate at base. Kiitzing thmks
this may be identical with his Sphenella
rostellata.

G. Vibrio (E.). — Elongated, inflated
at the middle, and gradually tapering
into long beak-like extremities ; the
upper one subacute. EM. pi. 39. 3. f. 71.
Cayenne. SD. i. p. 81, pi. 38. f. 242,
(xii. 35.) " Akin to G. gracile, but
longer, more slender, and approaching
to Pinnularia ampliioxxjs " (E.),

G. rostratum (Sm.). — Lateral view
ovate-elliptical, produced at the upper
extremity into a linear obtuse rostrum,
slightly constricted below; striae 30 in
•001". SBD. ii. p. 99. Barleylake, Co,
Cork. -0009" to -0012". Stipes distinct,

G. ? Hehridense (Greg.). — Lateral view
elongated, nan-ow-lanceolate, with in-
flated centi'e, acute equal apices, and
veiyfine striae. Greg. MJ. ii. p. 99. pi. 4.
f. 19. Mull deposit. Professor Gregory
remarks that it seems to stand between
G. tenellum and G. Vibrio, but that, only
its lateral view having been seen, ite
genus is uncertain.

6* Frustules lanceolate iti the lateral
vieto.

G. dicliotomum (K.). — Lateral view
naiTOw-lanceolate, with slightly obtuse
apices, striated ; front view nan-ow-
linear, cimeate. SD. i. p. 79, pi. 28.
f. 240. = G. gracile, EM. nimierous figures.
Common. 1-1150" to 1-860". Stipes
usually elongated and dichotomous, but
sometimes abbreviated and sub-simple.
The frustules somewhat resemble those
of G. olivaceum, but are uaiTower ; their
pmicta also are far less distinct. Thia
species appears generally diflused, since
Ehrenberg gives upwards of 100 habitats,
scattered over the world.

G. lanceolatum (E.). — Lateral view
striated, lanceolate, with acute ends;
front view liuear-cuneate, very gradu-
ally tapeiing at each end. IvB. p. 87,
pi. 30. f. 59. America, EhrenbcM's
figures represent the lateral view broader
than in G. dichotominn.

or THE GOMPHONElTEiE.

891

G. (0,ne (If.). — Eatlier tiu'gid, elon-
gate, steiated ; margins in front view
slightly curved; lateral view sublan-
ceolate, with an obtuse apex. KB. p. 86,
pi. 30. f. 54. Trinidad. 1-360". Stipes
abbre^aated, subraniose. " It differs from
6. dichotomum in its tinner habit and
broader sides; lateral apices more ob-
tuse " (K.). According to Rabenhorst, it
is slenderer than G. lanceolatum, but
scai'celj'' specifically distinct.

G. Fibula (Breb.). — Slender, elon-
gated, very narrow-cuneate ; lateral
view acicidar, very slender ; stipes short,
nodule obsolete. KSA. p. 65. France,
England. AJdn to G. dichotomum, but
differs in its slenderer fr'ustules.

G. exigimm (K.). — Minute, smooth,
lateral view lanceolate ; stipes slender,
subramose. KB. p. 84, pi. 30. f. 58. Ma-
rine. France, Jutland. 1-1440".

G. cuspidatum (Rab.). — Cuneate, often
curved ; lateral view smooth, lanceolate,
with acute ends. Rab D. p. 59, pi. 8.
f. 22. Saxony. With or without a
stipes.

G. (squale (Greg.). — Lateral view lan-
ceolate, with minutely capitate apices,
an exactly central nodule, and conspi-
cuous strise. Greg. MJ. iv. p. 12, pi. 1.
f. 41. Scotland. -OOl". Sti-ite 22 to 24 in
•001". It agi-ees nearly with some foi-ms
of G. tenellum, from which, however, it
differs in having much wider and coarser
Btrise, and in the central position of the
nodule, Greg. I. c. A slight constriction
exists beneath each end. Professor Smith
refers it to G. tenellum.

G. insigne (Greg.). — Lateral view lan-
ceolate, slightly rhomboid, with obtuse
ends ; strise 18 to 20 in -001". Greg. MJ.
iv. p. 12, pi. 1. f. 39. Scotland. -0016"
to -0025". " Distioguished by its size and
the coarseness of its striation. Side view
doubly conical, the angles at the broadest
part being strongly marked." Professor
Smith thinks it may be a form of G.
Sarcophagus.

G. Sarcophagus (Greg.). — Lateral view
clavate, lanceolate, constiicted near the
exti'emities, which are minutely capitate.
Greg. MJ. iv. p. 13, pi. 1. f. 42. Scotland.
!0014". Striffi 20 to 22 in -001". Widest

S>art about one-third from apex. Pro-
essor Gregory compares the outline to
that of a coffin.

G. viinutvisimiim (K.). — Linear-cune-
ate, smooth, with a slender subbranched
stipes; lateral view narrow-lanceolate.
KB. p. 84, pi. 8. f. IL Marine. Britain,
^i. 17.) Klitzing regards this as the
0. viinutissimum of Grcville ; but tliat

opinion is doubtless eiToneous ; for this
is a marine, and GreviUe's was an aquatic
gatiiering in which G. olivaceum and G.
curvatum were mixed together.

G. auritum (Braun.). — Broadly cune-
ate in fi-ont vjew, the upper end truncate,
with an awn at each angle ; lateral view
lanceolate, with a tenninal awn. Rab D.
p. 59, pi. 8. f. 3. Baden. Habit of G'.
intricatum, but fui'nished with awnlike
spines.

G. Navicidoides (S.). — Stipes distinct
and regidarly dichotomoiis ; fi-ont view
sublinear, tnmcate ; lateral view acutely
lanceolate, with the extremities equal
and nodide central. SBD. ii. p. 98. In
the Victoria Regia tank, Edinburgh.
According to Professor Smith, this spe-
cies, in a lateral view, is not to be di-
stinguished from a Navicula, as the
nodule is almost exactly central.

Species instifficiently described, or known
to us only by name.

G. digitatum (K.). — Frustules vei-y
minute and smooth, linear-cimeate, fla-
bellate; stipes simple, dilated above.
KB. p. 84, pi. 21. f. 2. 2. Marine. Cux-
haven. 1-680". Kutzing gives no de-
scription or figiu'e of the lateral 'vaew.

G. telographicum K.). — Frustules mi-
nute and very smooth, slender, cimeate,
somewhat more acute at base, umbel-
lately aggi'egated on a simple abbrevi-
ated stipes dilated at its apex. KB. p. 84,
pl.8.f.9. Maritime. Heligoland. 1-1200".

G. crassum (Rab.). — Front view
broadly cuneate, tnmcate above, romided
at base ; the lateral margins convex,
faintly striated. Rab D. p. 59, pi. 10. f. 13.
Persia. Although only the front view
is described and figiu-ed, yet the species
seems well distinguished by the convex
(not sti'aight) lateral mai'gins, giving
if an obovate form with the broader
end truncate. The pimcta are conspi-
cuous in the figui-e, as are also two lon-
gitudinal lines or vitta3.

G. pulm'natum (Braim). — Front •view
broad, linear-cuneate ; base smaller than
the very thick, serpentine, irregulaily
divided stipes. Rab JD. p. 58, pi. 8. f. 16.
Zvu-ich. " Forms little, very thick, smooth
knoblike cushions of equal height."

G. ? contractum (Iv.). — Very minute,
attenuated at the base, slightly con-
stricted at the middle, with a dilated
roiuidcd apex ; stipes simple, abbreviated
or obsolete. KB. p. 86, pi. 14. f. 21. 8.
Germany. 1-1440". Kiitzing's figure,
which ]s very minuto and pyi-ilomi,
shows no median line, nodule, or strire.

892

SYSTEMATIC HlSTOHr OP THE raPUSOllIA.

G. vmdare (E.), G. tenuicoUe (E.),
Australia; G. lonyicolle (E.), Australia,
Asia, America; G. Jordani (E.), Eiver
Jordan; G. ohtusiwi fE.), ^Vi-abia, Ame-
rica; G. turritum (E.), Arabia; G. mu-
cronatum (E.), G. rhomhoidmm (E.),

Asia; G. Mosambicense (E.), Africa-
G. 3Iarffaritaceutn (E.), G. Savanna
(E.), British Guinea ; G. lanceokitum
(E.), America ; G. Palea (E.), fossil,
Jura Mountains, France.

Genus SPHENOSIEA (E.). — Pnistules united into a straight compressed
filament; lateral sm-faces with tineqnal extremities and a distinct central
nodule. Aquatic. The frustules in front view are scarcely cuneate ; and the
genus could be better placed in the Naviculeae, as indeed Kiitzing himself
suggests; it seems to differ from them only iu the unequal ends of the
lateral surfaces.

SpHENOsrBA Catena (E.). — Frustules
smooth; lateral view with a mucro at
apex and a gradually attenuated, some-

what obtuse base. EA. p. 98, pi. 3. 1.
f.27; KB. p. 88, pi. 29. f. 47. Mexico.
(XI. 30.)

PAMILT XYin.— NAYICULE^.

Pnistules free, concatenate, or iacluded ia a more or less definite frond ;
front view generally linear or quadi^angular ; valves with similar ends, a
median longitudinal line, and central nodule. " The Navicnleae frequently
resemble individuals in other families, but are to be distinguished by the
central nodule of the lateral surfaces, as well as by the regularity and
symmetry both of these and the front view " (Menegh.). In the minuter
forms the nodules are frequently very indistinct; Avhen present, however,
they usually appear, in the front view, like a punctum at the middle of each
lateral margin. In doubtful cases this appearance will often aid in ascer-
taining their presence.

* Frustules nude.

Genus NAVICULA (Bory, Eab.). — Frustules simple, free, prismatic in front
view, rectangular laterally, with a longitudinal median peUueid line with
central and terminal nodules. Navicula was divided by Ehrenberg into two
genera — Navicula with smooth, and Pinnularia with striated valves ; but
this division was not received by Kiitzing or Brebisson, and is certainly un-
soimd, as it assigns the species to each genus according to the power of the
author's microscope, whilst striaj, we believe, are almost always, if not uni-
vei'saUy, present on the valves. The late Professor Smith reconstituted
Ehrenberg's genera, and made their characters depend on the presence or
absence of costoe. These characters were far better than those of Ehi-enberg ; ;
and were the costse always plainly developed as in Pinmdaria nohilis and its*,
allies, no difiiculty could occiu- in detennining the genera ; but in many of the ■
more minute species it is often very difficult to distinguish between striaj andl
costas. We have not admitted Pinnularia here, partly for the reason just:|
given, but principally because we cannot decide to which genus a large num-
ber of Ehrenberg's species should be referred.

slightly constricted at the middle andl

A. Valves more or less constricted at the
middle (Diploneis, E.).

Navicula Americana (E.). — Turgid,
linear-oblong, with slightly constricted
centre and broadly rounded ends ; striaj
wanting or indistinct. EM. pi. 2. 2. f.
16. New York and Khode Island.

N. Faba (E., K.). — Tm-gid, oblong,

rounded at the ends, marked by lonri-
tudiual lines; striae wanting or indi-
stinct. = Diploneis Faba, EB. 1845,»J
p. 365. River Tagus. The median line
mteiTupted by the central nodule ; tl
lines on each side continuous.

N. h/alina (E., K.). — Slightly conij
stricted at the middle, with oblong lobes,?

OF THE NAVICTJLEiE.

893

rounded ends, a longitudinal median
fascia of lines, and a naiTow pinnidated
hovdev. = Diploneis ? hyalina, EB. p. 362.
Marine. India. May be more aikin to
Cpnatopleura Solea.

N. binocUs (E.). — Smooth, minute,
narrow pandm'ifonn, -nith acuminated
rosti-ate apices ; median nodule very
distinct. EB. 1840, p. 18 ; ICB. p. 100, pi. 3.
f. S6. = Fra(/ilaria 'J> binodis, EA. p. 127.
Fossil, Santa Fiore ; recent in pools, &c.

N. duplicata (E.). — Smooth, small,
rather broad pandurifomi, with attenu-
ate subacute apices. EM. pi. 21. f. 35.
Cuba. In Ehrenberg's figure the ends
are somewhat cuneate, and the median
line simple.

N. incurva (Greg.). — Small, smooth,
sublinear, with a shallow sinus on each
side, and ends suddenly conti'acted into
obtuse subcapitate beaks. MJ. iv. p. 8,
pi. 1. f. 26. Scotland.

N. constricta, EM. pi. 38. 17. f. 3.
Volcanic ashes, Iceland. Ehi-enberg re-
presents it as smooth, minute, panduri-
fonn ; ends roimded, each terminated by
a minute nipple-like point ; median line
simple.

N. ejnarginata, EM. pi. 39. f. 83.
Ehrenberg's figure is minute, smooth, ;
panduriform, with each end suddenly
contracted into an obtuse, broad, mam-
mifonn beak.

N. paradoxa (E.). — Large, smooth ;
oblong, slightly constricted at the middle,
with four longitudinal median lines and
somewhat obtuse cimeate ends. EA.
pi. 1. 3. f. 4. 6. Peru.

N. imperialis (E., K.). — Dilated, with
constricted middle and subacute apices,
a simple series of conspicuous gi-anules
accompanjdng the middle furrow, which
is smooth on both sides; lateral series
alilce, two perfect ones inclosing an im-
perfect median sinus, all interrupted at
the middle. = Diploneis imperialis, EB.
1845, p. 362. Marine. Lidia. Granidcs
large, pearl-like.
_ N . Entomon (E.). — Large ; slightly
sinuato-constricted at the middle, with
oblong lobes and subacute cuneate ends ;
sti-ire 19 or 20 in 1-1200". EB. 1840.
= PrnnulariaUntomon, EA. pi. 1. 1. f. 3, 4 ;
Biphneis Entomon, EM. pi. 19. f 30.
Marine. Fossil, Greece ; recent, Eu-
rope, Asia, Africa. Distinguished by
its shallow stricture and smooth strijB.

N. Conops (E., K.].— Small, panduri-
fonn, very finely striated, witli cordate
lobes and acute apiculato apices. =Pm-
mdaria? Conops, EA. pi. 3. 7. f 20.
America.

N. mcurvata (Greg.). — Panduriform,
•with rounded ends ; striae 30 in -00 1",
minutely moniliform ; median line
straight, with dark shaded lines on each
side. TM. iv. p. 44, pi. 5. f. 13. Marine.
Scotland.

N. splendida (Greg.). — Lai'ge, pan-
duriform, much constricted, with elliptic-
oblong lobes and obtusely triangular
ends ; striae distinctly moniliform. TM.
iv. p. 44, pi. 5. i. 14. Marine. Scotland.
Median line straight, and having on each
side a nari'ow blank space.

N. Proserpince (E.). — Very large,
deeply constricted ; lobes almost rhom-
boid, with subacute apices ; sides stri-
ated, lines decussating at a right angle,
a broad, pellucid, smooth median fascia
divided by two lines into three parts ;
umbilicus cii'cular. = Diploneis Prosei--
pince, EB. 1858, p. 13. Marine, ^gean
Sea.

N. 3Iusca (Greg.). — Small, panduri-
form, with tm-gid lobes and acute cime-
ate apices ; striae rather distant, coarse,
moniliform, short, foi-ming a marginal
band. GDC. p. 7, pi. 1. f. 6. Marine.
Scotland. Striaj 18 in -001"; median
line and nodule distinct.

N. Bombus (E., K.). — Pandurifoi-m,
with subcordate lobes and subacute
apices ; striae dense, coarsely moniliform.
KSA. p. 83. = PinmdariaBombus, ERBA.
1844; GD.pl. 1. £ 12; Diploneis Bomhis,
EM. pi. 19. f 31. Eiu-ope. 1-384" ; striae
21 in 1-1200". Granules of the largest
striae in fom-s. Median line broad, with
a stjuare central nodide. Characterized
by its short tm-gid lobes and close, large,
pearly gi-anules.

N. didyma (E., K.). — Rather broad,
slightly constricted at the middle, with
short suborbicidar lobes and broadly
rounded ends ; striae distinct, granulate.
KB. p. 100, pi. 4. f 7 ; SD. i. pi. 17. 1 154.
= Pinnularia didyma, EA. pi. 2. 4. f. 3.
Marine. Em-ope, Asia, Africa, America,
(vii. 61; XV. 12.)

N. dissimilis (Rab.). — Large, pan-
duriform, with broadly rounded ends;
striae stout, cm-ved, converging, not
reaching the median line ; front view
gibbous at the centre and tapering to-
wards tlie ends, wliich are truncate. =
Pinnuhiria dissimilis, Rab. w. 46. xA 6
f. 32. Persia. V > V ^'

N. Pandura (Br(5b.). — Large, elong-
ated panduriform, M'ith elliptic lobes
and obtuse apices ; costse smooth. BD.
pi. 15. f. 4. = Pinmdana Pandura, GDC
p. 17, pi. 1. f. 22; N. niiida, TM. iv!
p. 44, pi. 5. f. 12. Europe. M. de Brd-

894

SYSTEMATIC HI8T0HY OF THE INFUSOHIA,

bisson regards this form as distinct from
JV. Crabro, E. ; and it undoubtedly is
fi'om the Trinidad Diatom figui-ed by
Dr. Greville for that species. We con-
sider, however, that N. Pandura, Br^b.
not only agrees in its smooth costse with
Ehrenberg's description and figure of N.
■Crabi'o, but also better in shape than
does Greville's N. Crabro, in which the
constricted portion is less elongated — a
fact pointed out by Greville himself.

N. Crahro (E., K). — Panduriform,
deeply constricted; lobes ovate or ob-
long, with subacute apices ; strise di-
stinct, obscurely moniliform, nitescent,
10 in -001". liA. p. 83 ? ; SBD. ii. p. 94 ;
MJ. V. pi. 3. f. 11, = Pinmdaria Crabro,
ERBA. 1844, p. 85 ? ; Diploneis Crabro,
EM. pi. 19. f. 29 ? Fossil, ^gina; re-
cent, America, Europe. Although we defer
to the opinions of Br6bisson, Smith, and
GreviUe, yet we think it highly probable
that the preceding species is the one
intended by Ehrenberg for D. Crabro.

N. genimata (Grev.). — Broad linear-
oblong, obtuse, with straight or slightly
concave sides ; strife moniliform, inter-
rupted, 10 in '001", with a single row of
pimcta near the median line. Edin.
New Phil. Jom'n. n.s. x. pi. 4. £ 7. Cali-
fornian guano. Distinguished by its
distant strise, which form a linear mar-
ginal band. Its affinity is with N. Crabro
and its allies.

N. nodidosa (Breb., K.). — Minute, ob-
long, constricted at the middle ; ends
conti'acted into obtuse mammiform
beaks ; ti-ansverse strise not reaching the
median line. KB. p. 101, pi. 28. f. 71. =
Pinnidaria Termes, EM. pi. 39. f. 100.
Recent, Cuba, Mexico, Africa; fossil,
Franzensbad.

N. gemina (E.). — Small, striated,
divided by a median constriction in both
views into two lenticular lobes; in lateral
view terminated by a median apicidus.
EB. 1840, p. 19. Mouth of the River
Elbe. 1-840" to 1-648".

N. Apis (E., K.).— Oblong, so much
constricted as to be nearly divided into
two semiorbicular lobes; strise slender,
granulate ; stricture smooth. liB. p. 100,
pi. 28. f. 76. = Pinnidaria Apis, EA. iii.
pL 7. i. 18. Mexico, Africa, Distin-
guished by its smooth stricture and its
finely granulate striaj (12 in 1-1200").

N. intmriipta (K.). — Sinuato-con-
stricted at the middle, with broadly ellip-
tic lobes and rounded ends ; sti'ise inter-
rupted opposite the nodule. I03. p. 100,
pi. 29. f. 93. = Navicula, BAJ. 1842,
pi. 2. f. 18. Marine. America, Jutland.

B. Valves divided into three or more por-
tions by two or four constrictions, but
not constricted at the centre (Nodosae),

N. Silicula (E.). — Smooth, linear
elongated, divided by two constrictions
into three nearly equal nodes; apices
obtuse. EM. numerous figures. = N.
ventricosa, E. Apparently' common, since
Ehrenberg gives upwards of fifty habi-
tats in Eui-ope, Asia, Austi'alia, Africa,
and America. This species might be
placed with almost equal propriety in
the following section.

N. polyonca (Br6b.). — Elongated, ba-
ciUar, sublinear, divided by two con-
strictions into three nodes, the middle
one largest ; ends roundish-capitate ;
sti-isB wanting or indistinct. KA. p. 85.
= Pinnularia undulata, MJ. ii. p. 97, pi.
4. f. 10. France, Britain.

N. mtchcockii (E.). — Smooth, linear-
oblong, each margin with three imdula-
tions; apices suddenly cuneate, sub-
acute. EM. pi. 5. 3. f. 11. America,
(vn. 62.)

N. limosa (K.). — Smooth or obscurely
striated, linear, with two constrictions
and three inflations, the middle one
largest ; ends cuneate, subacute. KB.
pi. 3. f. 50. Geimany.

N. nodosa (E.). — Linear, smooth or ob-
scurely striated, with three nearly equal
inflations; ends contracted into short ob-
tuse beaks. KB. p. 100, pi. 28. f. 82. Com-
mon, especially in small pools bythe road-
side, (rx. 143.) ^, striae more evident. =
Pinmdaria Legumen, EM. many figures,
1-430". Approaches N. Hitchcockii.

N. trinodislS.). — Valves with two con-
strictions, three neai-ly equal inflations,
rounded ends, and obscure strise.

N. mcsolepta (E.). — Smooth, elongated,
linear, ^"ith three inflations, the middle
one smallest; ends strongly contracted
into short obtuse beaks. EM. pi. 17.
2. f. 17. America, France. 1-420".

"N. nivalis (E.). — ^linute ; linear, some-
what naiTow in the middle, with tri-
crenate sides and obtuse apices. EB,
1853, p. 528 ; EM. pi. 35 b. a 2. f. 6.
Monte Rosa. Differs from N. tindosa in
its stouter apices : N. nodosa is lai'ger and
more slender. Ehrenberg's figure shows
the A'alves very miimte, with four con-
strictions and five nodules, including the
capitate ends, which nearly resemble the
others in size and form.

N. Formica (E.). — Smooth, linear,
with four constrictions and five oblon?
nodes. EM. pi. 4. 3. £ 8. Recent, United
States ; fossil, Finland.

or THE NATICULE-aE.

895

N. Monile (E., K.)-— Striated, linear,
constricted, vfith five, nearly ec[ual sub-
globose nodes, including the capitate
ends. = Pinnularia dionile, EM. pi. 17. 1.
f. 12 ; Pinimlaria isocephcda, EM. pi. 5.
3. f. 21. Berlin, America. It bas the
ends more capitate and the striae stronger
than N. nodosa.

N. Kochii (E., K.). — Large, elongated,
lanceolate, with subacute apices, each
side with three undulations, the middle
one most distinct; sti-iae obliq[ue j the
median smooth band very broad, extend-
ing to the apices. KA. p. 84. =PmwM-
laria Kochii, EB. 1845, p. 364. Fossil.
Kurdistan.

N. Pyrenaica (S.). — Elongated, slen-
der linear, with three intiations, the
median one gi-eatest; stri£B indistinct.
ANH. 1857, xix. p. 8, pi. 2. f. 5. Pyre-
nees.

N. undosa (E.). — Small, smooth,
broadly oblong-lanceolate, with three
undulations on each side, and conical
apices. EM. pi. 39. 3. f. 90. America,
Africa, Asia, France. Ehi'enberg de-
scribes it as akin to N. Hitchcockii.
Kabenhorst remarks that it resembles N.
Persica in form, but is scarcely one-third
its size and has no secondary imdulating
ribs.

N. Persica (Eab.). — Large, oblong-
lanceolate, with obtuse mammiform
apices ; each side with five imdulations,
and four coiTesponding longitudinal im-
dulated lines on each side the median
one. Eab D. p. 41, pi. 6. f. 55. South
Persia. Broadest at the centi-e, and
tapering in a pyramidal manner to each
apex.

N. inte(/ra (S.). — Small, lanceolate,
with slightly undulated mai'gins and
contracted apiculate apices; stiia3 in-
distinct, 36 in -001", reaching the median
line and most evident opposite the cen-
tral noA.^Ae. = Pinnldaria mtegra, SD. ii.
p. 96 ; N, rostrata, MJ. iv. pi. 1. f. 14.
Britain.

N. nndulata. = Pin7iularia mesotyla,
EM. pi. 16. 3. f. 27. Sweden, India.
Ehrenljerg's figure somewhat resembles
that of N. undosa in form, but is longer
and has parallel transverse striae.

C, Valves elongated linear or lanceolate,
tcith gibbous or injlated centre ; central
costcB, token pi-escnt, usually converging,
and often leaving a dilated smooth sjjace
round the median nodule,

' _ N. mesotyla (E.). — Small, smooth or
ji indistinctly striated, narrowly linear,
' with a central spherical inflation and

sliffhtly contracted obtuse apices. EA.
p. 131, pi. 4. 2. f. 7. ; EM. pi. 1. 3. f. 14.

Asia, Africa, America. 1-420".

N. incompicua (Greg.). — SmaU,smooth,
hyaline, linear, with rounded ends and
slightly gibbous centre; median line
strong, complex, interrupted by the de-
finite central nodule. GD. p. 6, pi. 1. f.
3. Scotland.

N. Icevissima (K.). — ^Minute, viti-eous,
clear, linear, with broadly rounded ends
and slightly gibbous centre ; striae want-
ing or indistinct ; centi-al nodule stauros-
like. KB. p. 96, pi. 21. f. 14. = Stau-
roneis rectangularis, MJ. ii. pi. 4. f. 17
(according to Smith). Fossil, Santa
Fiore ; recent, Britain. 1-570".

N. tmnidida (Rab.). — Small, linear,
with rounded, slightly enlarged ends, and
inflated centre ; central nodule stout.
EabD. p. 41, pi. 5. f. 9. Stockholm.
Closely allied to N. Silicula.

N. scopulorum (Breb.). — Elongated,
slender linear, vnth. central and terminal
inflations ; strias very faint, reaching the
median line, 56 in -001". KA. p. 81. =
N. mesotyla, KB. p. 99, pi. 5. f. 3 ; Pin-
nularia Johmonii, SD. i. pi. 19. f. 179.
In marine or brackish waters. France,
Britain. Front view turgid at the middle.
M. de Br^bisson assm-es us that Smith's
species is identical with his N. scopu-
lorwn; but Kutzing's figure and descrip-
tion would not lead us to infer the
identity.

• N. gibberula (K.). — Linear, with gib-
bous centre and very slightly enlarged,
obtuse, subtruncate apices ; stiiae very
fine. KB. p. 101, pi. 3. f. 50*. Em-ope.

N. leptogongijla (E.). — Elongated,
slender linear, striated, tumid in the
middle; apices slightly dilated, oblong,
obtuse. KB. p. 99, pi. 4. f. 9 ; EA. p.
130. = Pinnularia Iqotogongyla, EM.
many figures. Eiirope, America. Lough
Mourne deposit. Rabenhorst says that
this species has double the breadth of
N. scopulorum,

N. mesogonggla (E., K.). — Styliform
or bacillar, striated, with gibbous middle,
and broadly rounded but not dilated
ends. KA. p. 81. = Pinnularia meso-
gongyla, EM. pi. 10. 2. f. 2. Asia, Africa,
America. ^Vkin to N. nobilis, but with-
out dilated ends.

N. nobilis (E., K.). — Very large, elon-
gated, broadly linear, gradually dilated
at centre, and broadly rounded ends ;
co8to3 oblique, stout, close, not reaching
the median line. KA. p. 80. = Pin-
mdaria nobilis, EB. 1840, p. 20 ; SD. i.
pi. 17. f. 101. Europe, America, Asia,

896

SYSTEMATIC HlSTOBy OF TKE INFTJSOHIA,

Australia. 1-84" ; nodules large : costse
16 to 18 in 1-1200".

N. gigas (E., K.). — ^Very large, elon-
gated ; broadly linear, with gibbous centre,
and broadly rounded, slightly attenuated
ends ; costae broad, close, not reaching
the median line. KA. p. 80. =Pin7iularia
gigas, EM. pi. 2. 3. f. 1. America. Akin
to N. nohilis; nine pinmdes in 1-1200".

N. major (K.). — -Large, turgid, linear-
oblong, with slightly tumid ceuti-e and
broadly roimded ends: cost£B converg-
ing at the centre, stout, 12 in 1-1200".
KB. p. 97, pi. 4. f. 19, 20. = Pinnularia
major, SD. pi. 18. f. 161; Pinnularia
viridis, E., in part. Common, (vn. 65;
xn. 15, 31; xvi. 1-6.) This species
scarcely differs from N. nohilis and N.
gigas, except by its somewhat smaller
size and closer pinnules.

N. acrosphceria (K.). — Elongated,
slender linear, with dilated centre and
ends, rounded apices, and seventeen short
thick costse in 1-1200", which do not
reach the median line. KB. p. 97, pi. 5.
f. 2. = Pinnularia am-osphairia, Rab D.
45, pi. 6. f. 36 ; SD. pi. 19. f. 183.
lu'ope. Front view narrow-linear.
^ . pachyptera (E., K.). — Large, bacil-
lar, but short and stout, with gibbous
centre and broadly rounded ends, which
are not constricted ; pinnules stout, not
reaching the median line, 6 in 1-1200".
KB. p. 98, pi. 28. f. 58. = Pinnularia
pacliyptera, E. Labrador, Austi-alia.

N. hebes (Ralfs). — Small, oblong, with
gibbous centre and broadly obtuse ends ;
sti-isB distinct, 33 in -001", nearly reach-
ing the median line. = iV; obtusa, SD. i.
p. 50, pi. 16. f. 140. Britain.

N. cocconeiformis (Greg.). — Small,
subelliptic, with tumid centre and slightly
contracted, broad, obtuse ends ; strise in-
distinct, median line straight, nodule
definite. MJ. iv. p. 6, pi. 1. f. 32;
Grev. ANH. 2nd series, xv. pi. 9. f. 6.
Scotland. It much resembles Achnanthi-
diicm Jlexellmn, but its median line is
quite straight, Greg.

N. Macula (G.). — Small, oblong, with
tumid middle, and very broad, siibtrun-
cate ends ; strite very fine, parallel, nearlj^
reaching the median line, except opposite
the large, transverse, quadrate indefinite
median space. TM. iv. p. 43, pi. 5. f. 9.
Marine. Britain. Sti-ia) about 70 in
•001". In shape not unlike large speci-
mens of Achnanthidium Jh'xcl/inn, but tlie
median line is straight. The central
nodule is obsolete and is replaced by the
large, stain-lilce blank space, Greg.
N. gihha (E., K.).— Bacillni-, striated,

lanceolate, with dilated capitate ends
KB. p. 98, pi. 28. f. 70. = Pijinulari'a
gibba, EA. pi. 1. 2. f. 3 ; SD. pi. 19. f.
180. Common. Europe, Asia, Africa,
America. Sti-iae close, not reaching the
median line, 30 in -001".

. Tabellaria (E., K.). — BacUlar, elon-
gated, striated, rather turgid, ventricose
at the middle, with dilated, broadly
rounded apices. KB. p. 98, pi. 28. f. 79.
= Pinnularia Tabellana, EA. pi. 2. 1.
i. 26 ; SD. i. pi. 19. f 181. Europe, Asia,
Africa, America, (xn. 21.) The central
dilatation tapers less than in N. gibba,
and the strife are more distant. It is
more slender than N. nohilis.

N. porrecta (E., K.). — Large, elon-
gate-lanceolate, broadly tumid at the
middle, and gradually tapering into the
broadly obtuse apices; striae oblique.
KA. p. 81. = Pinjiidaina porrecta, EA.
p. 133. North America. Akin to N.
decurrens.

N. decurrens (E., K.). — Striated, nar-
row, elongate-lanceolate, tiunid at the
centre, somewhat narrowing towards the
ends, which are broadly rounded. KA.
p. Q\. = Pinnularia decurrens, EM. many
figures. /3 slenderer, = Pi«;!?</ar('a Tra-
becula, y, stria3 obsolete, =A''ar(('M/«
Trabecula, E. Ehrenberg gives upwards
of 80 habitats. Akin to N. gihha.

N. Esox (E., K.). — Large, elongated,
striated, narrow-lanceolate, witli slightly
gibbous centre and attenuated but obtuse
ends ; stiise parallel, nearly reaclung the
median line. KB. p. 94, pi. 28. f. 53. =
Pinmdaria Esox, EA. p. 133, pi. 1. 2. f. 4.
Chili, (xu. 43.)

D. Valves with a smooth, transverse
middle fascia.

N. cardinalis (E.). — Large, broadly
linear, with rounded ends ; costas stout,
radiant, 9 in -001", interrupted by a
smooth, ti'ansverse median baud. = /•/«-
nularia cardinalis, SD. i. pi. 19. f. 166 ;
Stauroptcra cardinalis, EM. several fi-
gures ; Sfauroneis cardinalis, KB. p. 106,
pi. 29. f. 10. Europe, Asia, Australia,
Africa, America, (xn. 72.) A well-
marked species, easily recognized by its
large size, rounded not attenuated ends,
and coarse stria}, which are shorter near
the transverse median fascia. Perhaps
this and other species haviug a trans-
verse smooth median fascia might ad-
vantageously be retained in Stauroneis,
notwithstanding that the fascia is not
formed by a thickened prolongation of
the central nodule.

N. dir^rgrn.t (S.). — Large, oblong-

I

OF THE ITAVICTJLXiiE.

897

lanceolate, somewhat contracted towai'ds
the rounded ends ; costiB radiate at cen-
time, interrupted by a smooth ti'ausverse
median fascia, 11 in •001". = Pinnularia
divergois, SD. i. p. 57, pi. 18. f. 177.
Britaiu. The costae near the central uo-
dide are shorter and radiant; the others
are divergent.

N. Brebissonii (K.). — Linear -oblong,
■with obtuse ends ; costte fine, indistinct,
close, 30 in -001", not reachbig the me-
dian line, interrupted by a transverse
median fascia. KB. p. 93, pi. 3. £ 49. =
Pinnularia stauroneiformis, SD. i. p. 57,
pi. 19. f. 178. Europe. Front view
linear, with rounded angles.

N. globiceps (Greg.). — Minute, narrow
linear-oblong, consti'icted beneath the
globidar ends; costse fine, distinct, not
reaching the median line, interrupted by
a ti'ansverse median bl.ank band, 36 to
40 in -001" . = Pinnularia qloiiceps, MJ.

t iv. p. 10, pi. 1. f. 34. Scotland. Di-

: stinguished by its capitate apices and

; transverse cross-like median band.

N. parva (E.). — I^iuear, constricted
beneath the capitate ends ; costae 24 in
•001", interrupted at the middle by a
transverse, blank, cross-like band. = Stau-
roptera parva, EA. p. 135, pi. 3. 1. f. 19 ;
Stauroneis parva, KB. p. 106, pi. 29. f. 23 ;

' Pinnularia interrupta, SBD. i. p. 59,
pi. 19. f. 184. Eui'ope, Asia, America.

1 Transverse band dilated outwards.

i N. Bohemica, EM. pi. 10. 1. f. 4.
Bohemia. Ehrenberg's figure is rhom-
boid, with obtuse apices, three median

! lines, between which and the margins
are longitudiaal series of dots, all inter-
rupted by a transverse median blank
space, but no distinct nodule ; front view
narrow-linear, with rounded ends.

_N. Claviculm (Greg.). — Narrow-linear,
with two constrictions ; central inflation
small, smooth; terminal ones oblong-
clavate, striated; sti'ise parallel, nearly
reaching the median line, about 32 in
•001". Gt). p. 6, pi. 1. f. 5. Scotland.

' Nodule definite ; front view linear, with
rounded angles, broader than tlie lateral

' "ew, the margins sti^iated except at the

I middle. ^

j E. Frmtules in the lateral view havinr/ the
■ ' etria; on each side of the median line
divided into two series (rt marginal and
<i median) by a longitudinal line, blank
space, or fascia.

t Valves elliptic.

N. L,jra (E.). — Elliptic or oUiplic-
! "Wong, marked by two narrow longi-

to

tudinal blank spaces, which are con-
nected by the central nodule, in the form
of a lyi-e ; strife 22 to 24 in •001", often
indistinct, the middle ones longest. =
Navicula and Pinnularia Lyra, E., GD.
p. 13, pi. 1. f. 13 ; N. Gregoriana, Grev.
MJ. V. p. 10, pi. 3. f. 7. Marine. Em-ope,
Asia, Afi'ica, A merica, N. Lyra, var. recta,
Grev., large, oblong-lanceolate obtuse ;
blank lines nan-ow, contracted at the no-
dule, otherwise parallel with the median
line ; striae 24 in -001" : Edin. New Phil.
Jom'., U.S., X. pi. 4. f. 3 : Califomian
guano : distinguished by its large size
and straight blank lines. Either N. Lyra
is very variable, or more than one species
has been included imder the name. The
valve is eitlier rounded at the ends or
(more usually) has a short, produced,
conical point. The blank spaces are
linear, inclined inwards at the nodule,
and the tips, which are attenuated, usu-
ally bent outwards, but are sometimes
straight or even incurved.

N. approximata (Grev.). — Oblong,
with produced, conic apices ; strijB inter-
rupted, 17 in -001" ; outer band broad, not
dilated opposite the nodule ; blank lines
linear, nearly sti-aight. Grev. Edin. New
PhU. Jom-., U.S., X. pi. 4. f 10. Califomian
guano. Allied to N. Lyra, but distin-
guished by the total absence of any con-
traction of the blank spaces opposite the
nodule. From N. Hennedyi it differs in
its linear, subparallel blank spaces, and
larger blank space round the nodule.

N. irrorata (Grev.).— Broad, parallelo-
gi-amic or oblong, suddenly contracted
at the ends into mammifoi-m apices ;
strife 15 in -001", fomiing a broad-linear
marginal band, and a narrow one of very
imequal breadth next the median line ;
blank spaces not reaching the ends.
Grev. I. c. f. 1. Califo rnian guano.

N. forcipata (Grev.).— Oval or oblong,
with roimded apices, and marked by two
nan-ow longitudinal l)lank spaces, which
diverge from the nodule m a curved
nmnner and converge at the apices-
striffi 35 in -001", t]ie middle ones longest!
MJ. vii. pi. 6. f 10, 11. Marine. Britaiu!
J^istinguished from N. Lyra by its
smaller size, closer strire, aiid conuivent
points of tlie blank spaces.

N. nummularia (Grev.). — Suborbi-
cular; striaj moiiilifurm, about 24 in
•001", interrupted by two narrow-linear
blank lines wliicli contract opposite tlio
nodule, then cun'o outwards, couA-erge,
and meet at tlio t(n-minal nodules. Grev.
VA'm. New Plul. Jour., n.s., x. pi. 4. f. o!
Califomian guano. Valve small ; striai

y M

898

SVST]5MATIC IIISXOUY

OX'' THE INFUSOUU.

concentric vAth the extremities. Tlie
blank spaces have a considerable resem-
blance to those of N. forcipata, Grev.

N. spectahilis (Greg.). — Broadly ellip-
tic, gradually tapering to the obtuse
apices ; blank spaces broadly linear, con-
verging at nodide and ends ; strise 22 in
•001", coai'sely moniliform, the outer
series forming a broad marginal band
much dilated opposite the nodule. GD.

£9, pi. 1. f. 10. Marine. Scotland,
ai'ge (inner) bands of striiB linear.
Distinguished from N. Lyra by broader
blank spaces and the brown coloiu- of
the striated portions ; its nodide also is
indefinite.

N. siiborhicularis (Greg.). — Small,
broadly oval or suborbicidar ; strife con-
spicuous, about 18 in -OOl", divided by a
longitudinal line into two series, outer
one broadest opposite the indefinite cen-
tral nodide. = N. Smithii suhorhimlaris.
GD. p. 15, pi. 1. f. 17. Marine. Scotland.

N. Coi<pe7-i (Bailey). — Large, oblong,
with slightly constricted sides and con-
tracted mammiform apices ; strite punc-
tate, divided into series by two narrow
longitudinal blank bauds united by the
transverse nodule. = Pinnularia Co^ipm-ii,
BMO. p. 39, pi. 2. f. 3. United States.
The outline is like that of N. paradoxa ;
and the markings somewhat resemble
those of N. Lyra, /3. Blank spaces con-
nivent at their apices.

N. Hennedyi (S.). — Elliptical, with
rounded or mammiform ends ; strioB mo-
niliform, divided into series by two nar-
row, lunate longitudinal blank spaces,
series

the marginal series of nearly equal
breadth throughout. SBD. ii. p. 93 ;
Greg. MJ. iv. pi. 5. f. 3. = Stauroncis an-
qidata, Johnston, MJ. viii. p. 13. Marino
Britain, (vn. 69.) Stria3 24 in -OOl"
not perceptibly longer opposite the cen-
tral nodule, which is indefinite.

N. clavata (Greg.). — Broadly elliptical
with apices produced into mammiform
points ; striae monilifoim, divided into
series by two arcuate longitudinal blank
spaces bent outwards at their ends
marginal series of nearly equal breadth
tkroughout. TM. iv. pi. 5. f. 17. Marine-
Scotland. Sti'ite 20 in -001", not per-
ceptibly longer opposite the central no-
diue, wliich is indefinite.

N. nvhv.losa (Greg.). — EUiptic-oblonrr;
blank spaces large, semilunato ; striai
fine, 34 to -30 in -001", forming a nan-ow
marginal band of equal breadth. GD.
p. 8, pi. 1. f. 8. Marine. Scotland. Inner
bands of strife, very narrow linear, close
to median line. Aspect of valve hazy

and indistinct; sti-iatcd portions bluish
under a low power ; nodule indefinite.

N. prcetvxtu (E.). — Large, elliptic
Avith broadly rounded ends; stria? di-
stinctly moniliform, 8 to 10 in -001",
forming a marginal border of nearly uni-
form breadth, which is separated from
the narrow median band by a large
spai'sely gi-anular space on each side.
EB. 1840, p. 20; GD. p. 9, pi. 1. f. 11.
= Pinnularia pratcxta, EM. pi. 19. f. 28.
Marine, Scotland ; fossil, Greece. 1-288".
This species is distinguished by its large
size, coarse stiiation, much rounded enM,
and a broad semilunate space between
the marginal and inner bands of striae,
furnished with scattered granules.

N. CaliJ'ornica (Grev.). — Broadly
elliptic, with flattened sides ; strife mo-
niliform, divided into naiTow mar^nal
and median bands by a large, semilu-
nate, smooth intermediate space on each
side the median line. Grev. Edin. New
Phil. Jom'., U.S., X. pi. 4. f. 5. Califomian
and S. Afiican guanos. Marginal striae
20 in -OOl". Differs fi'om N. pratexta in
having the sides of the valve flattened,
and the broad intennediate space be-
tween the marginal and median striae
smooth.

1^ . polysticta (Grev.). — Elliptical; stria--
moniliform, fonning a naiTow mai-ginal
band, separated fi-om the median line bv
an iiTegidarly pimctate, lunate inter-
mediate space ; strire 25 in -001". Grev.
I. c. f. 2. Califomian guano. Valve mi-
nute. Differs fi-om N. prcctexta in its
smaller size and fai* less rounded ends.

N. Smithii (Br^b.). — Elliptic, with
roimded apices ; stiite distinct, 21 in
•001", interrupted on each side of tbe
median line by a longitudinal line ; tli'
inner series narrow, fainter. = iV'i clUptw ■
SD. i. p. 48, pi. 17. f. 152. Marine.
Europe. The outer series of striffi
broad, but not dilated opposite the
central nodule.

N. fusca (Greg.). — Large, elliptic-
oblong, with broadly rounded end?:
striaj coarsely monilifonn, about 10 ni
•001", divided on each side by a lo"?'"
tudinnl line into two series, the mwr
one fainter. = .A': Smithii, ^ fusca, (A^-
p. 14, pi. 1. f 15. ]\Iarinc. Scotland.
Diflers from N. Smithii in its much hirgt r
size and- more distant strive. NoduJ>-
indefinite ; median smooth space na^^o^^
lanceolate. .

N. tiitrscms (Greg.).— SniaU, elliptic-
Inuceolato, with obtuse apices; stn.i'
obscurely moniliform, about IG in "00 1 >
con^•crgi"ng at centre, divided on eacb.

OF THE lJ-ATICUI,EvT3.

899

side by a longitudinal line into two series,
reaching the median line. = iV; Smifhii,
y nitescem, GD. p. 15, pi. 1. f. IG. Ma-
rine. Scotland. Colourless under a low
^ower; median line linear, nodide de-
fauite. Distinguished from N. Sinithii by
its smaller size, the chai-acters of nodule
and median Une, and its bright-white
aspect.

N. quadrifasciata (E.). — Elliptic-ob-
long, with attenuated, obtuse ends ;
striiB 20 in 1-1200", divided on each side
of the median line into two linear series.
EB. 1840. = Pimiularia quadrifasciata,
EM. pi. 19. f. 25-27 J N. lineata,' DonWn,
MT. vi. p. 32, pi. 3. f. 17 ? Marine. Fossil,
Greece ; recent, iBritain. 1-430". Series
. of strife separated by a nan-ow blank line.
N. elliptica (K.). — Elliptic or linear-
elliptic, with roimded ends ; strias di-
stinct, connivent, 27 in ' -001", divided
into two series on each side the median
space by a longitudinal line. = iV. Par-
mula, KA. p. SO ; N. ovalis, SD. i. p. 48,
I pi. 17. f. 153. Em-ope._
I N. pygnuea (K.). — Minute, elliptic or
oblong-elliptic, with roimded ends, hj^a-
i liae, with very faint, close stiise, and a
i panduriform blank median space. KA.
; p. 77. =K mintdida, SD. i. p. 48, pi. 31.

I. 274. In brackish or fresh water.
■ France, England. Although the strise,
\ which are very indistinct, are not inter-
il rupted, yet the peculiar fonn of its me-
; dian space shows that its proper position
is in this gi'oup.

N. csstiva (Donldn). — Large, naiTow-
elliptic, with rounded ends ; strias fine,
distinct, costate or obscurely momliform,
> reaching nearly to the median line,
' crossed on either side near their inner
• ends by a longitudinal line. TM. vi.
. ■ p. 32, pi. 3. f. 18. Marine. Northimi-
: t berland. This beautiful species differs
I' I from iV. Smithii in its more gracefidly
} elliptical figure, in its costate and much
1) : finer striaa, and in the darker-brown
\'i colour when moimted in balsam. The
r' dry valve is pale-brown. Donlrin.
Y'' N. Allmaniana (Grog.). — Small, oval,
1.1 with subacute apices ; costa) about 20 in
I "001", somewhat radiant, nearly reaching
the median line, divided by a lino near
to and concentric with the margin. =
r'!nnularia Allmaniana, GD. p. 16, pi. 1.
21. Marine. Scotland. The marginal
ries of costve narrow, conspicuous,
border-like ; the inner one fainter.

2 t Valves linear, with dilated centre
and ends.

N. liahcnhorafii (Ralfs). —Elongated,

slender, gradually dilated at centre and
broadly rounded ends; strife fine,_ short,
divided on each side the median line by
a narrow, blank, longitudinal line. = Pin-
nularia interriipta, Eab D. p. 44, pl. O.
f. 3. Italy. Divided by two constiic-
tions into throe oblong portions; the
inteiTupting line undulated like the
margins. This species resembles a slen-
der N. nohilis with interrupted stiicB.

F. Valves with capitate or rostrate apices.
t Valves inflated or ventricose.

N. Orvx (E.). — Cruciform, with di-
verging costse, which do not reach the
median line. = Pinmdaria Crux, EM.
pi. 12. f. 37. Asia, Cassel. This species
has the lateral view like a Biblarium, but
with median line and nodide.

N. Trochus (E.). — With strongly in-
flated middle, and obtuse, rosti-ate ends,
longitudinally stiiated. Elnf. p. 179,
pi. 21. f. 8. Fossil. Sweden. 1-860".

N. in/lata (K.). — Minute ; with much
inflated centre, and short, obtuse, beak-
like ends ; stii;e wanting or indistinct.
KB. p. 99, pi. 3. f. 36 =A^. Follis, EM.
several figures. Fossil, Sweden, Santa
Fiore ; recent, Europe.

N. ainphisbana (Bory). — Inflated,
elliptic, with capitate or conic apices ;
striffi close, delicate. E Inf. p. 178, pi. 13.
£ 7 ; SD. i. p. 51, pi. 17. f. 147. Common.
Eiu'ope, Asia, Africa, America. 72 ;

IX. 141.) 1-1700" to 1-240". Median
nodule orbicidar. The Pinmdaria am-
p)liish(ena, EM., is probably a state of this
species exhibiting more conspicuous
strio3.

N. Placenta (E.). — Minute, ventricose,
roimdish-elliptic, ^vith a nipple-like pro-
jection at each apex. EM. pi. 33. 12.
f. 23. Oregon.

N. sphcBrophora (K.).— Elliptic-lance-
olate, strongly constricted into capitate
or conic apices; strico wanting or in-
distinct. KB. p. 95, pi. 4. f. 17 ; SD. i.
p. 52, pi. 17. f. 148. Europe, Asia. Veiy
similar to N. amjihishcvna, but it is less
inflated, and it appears destitute of strire.
According to Rabonliorst, it differs also
by having faint longitudinal lines.
1-320".

N. hrcvis (Greg.). — Smnll, elliptic,
contracted into short, broad, mammiform
ends; strife fine, about 35 in -OOl",
nearly reaching the median line, shorter
opposite the indefinite central nodule
GD.p.O,pl. l.f.4. Scotland. Trofessor
Walker Arnott is probablv correct iu
uniting this to N, amp/iisbtrtia.

3 M 2

900

STSTEjrATIC mSTORY OF THE TNPtrSOTiTA,

N. tiimens (S.). — Inflated, elliptic, with
the ends suddenly contracted into short,
obtuse beaks ; striis indistinct, 36 in
•001". SD. i. p. 52, nl. 17. f. 150. Brack-
ish water. England.

'N.picsilla (S.). — Small, inflated, ellip-
tic, suddenly contracted into short, conic
beaks ; striiB distinct, punctate, radiant,
26 in •001". SD. i. p. 52, pi. 17. f. 52.
=N. gastroides, Greg. MJ. iii. p. 40, pi. 4.
f. 17. Brackish water ? Britain. Prof.
Gregory distinguished his N. gastroides
from this species by its stouter habit,
larger size, and having a brown colour
even in balsam ; but we unite them as
Professor Smith has done, being imwill-
ing- to add another doubtful species to
this group, which we believe is already
too numerous.

N. Anglica (Ralfs). — Minute, elliptic,
suddenly constricted beneath the round-
ish capitate ends; strife very distinct,
pimctate, radiate, reaching the median
line, 24 in •OOl". = N. tmnida, SD. i.
p. 53, pi. 17. f. 146.

N. Carassius (E.). — Small, inflated,
broadly lanceolate, with the ends sud-
denly contracted into short, conical
beaks ; striae wanting or indistinct. EA.
p. 130, pi. 2. 2. f. 11. France, America.
Is smaller than N. ampMsbcena.

N. capitata (E.). — Minute, with in-
flated centi-e, and short, obtuse, beak-
lilce ends ; strias diverging, 10 in 1-1200".
E Inf. p. 179, pi. 13. f. 20. = Pinmdaria
capitata, EM. pi. 35 A. 1. f. 4. Europe,
Asia, Australia, America. 1-1150" to
1-576".

N. Semen (E.). — Small, eUiptic-ob-
long, slightly contracted into tlie broad,
obtuse ends ; sti-iaj obsolete or appai'ent.
EA. pi. 4. 2. f. 8 ; in EM. many flgm-es ;
SD. i. p. 50, pi. 16. f. 141. /3, sti-ite di-
stinct, = Pinnularia Semen, EM. Eui'ope,
Asia, Africa, America.

N. eeqiialis (E., K.). — Inflated, elliptic-
lanceolate, suddenly contracted at the
ends into nipple-like points ; striiE fine.
KSA. p. 77. = Pinnularia csqualis, EA.
131; EM. many figures. Em-ope. Lough
Mourne deposit, Iceland.

N. diomphala (E.). — Sti-iated, short,
broadly lanceolate, suddenly conti-acted
into obtuse beaks ; median nodule trans-
verse, divided by a longitudinal line into
two parts. EA. p. 132, pi. 3. 7. f. 25.
America.

N. Gasirum (E., K.). — Small, striated,
inflated, elliptic, contracted at tlie ends
into short conical beaks ; striic radiant.
KB. p. 94, nl. 28. f. 50. = Pinmihtria
Gastrum, EM. several figures; Pin-

nularia Placentula, EM. several figures.
Asia, Afirica, America.

N. hirostrata (Greg.). — Ventricose,
elliptic-oblong, with shortly rostrate
apices ; sti-ia3 fine, close, radiant, reaching
nearly to the median line. MJ. iii. p. 40,
pi. 4. f. 5. Scotland.

N. tceniata (E.). — Small, inflated,
elliptic, suddenly contracted into minute,
romided, conical beaks ; pinnules strong,
fonning a naiTOw marginal border. =
Pinnularia tccniata, EM. pi. 39. f. 95.
The piimules separated from the median
line t)y a broad blank space. Perhaps a »
Mastogloia. (xv. 15.)

N. biceps (E.). — Small, turgid, lance-
olate, slightly consti'icted into obtuse,
conical apices ; sti'ise wanting or indi-
stinct. EA. p. 130 ; EM. many figure?.
Europe, Afi'ica, America. ' Rather more
slender than N. amphisbeena.

N. crassula (Nageli). — Smooth, ellip- -
tic, with capitate apices ; front view i
broadly linear, ti'imcate. 1-720". KSA. _
p. 890. Switzerland.

N. satlpta, EM. pi. 10. 1. f. 5. Bohe- -
mia, Asia, America. Ventricose, sud- -I
denly tapering into shoa-t, broad, obtuse
beaks, the median line inten-upted by
the indefinite nodule, which extends on
one side in a semicracial smooth band ;
the rest of the .sm-face granidated. Front
view linear, with rounded angles and
gibbous sides.

N. signata (E.). — Minute, inflated,
prolonged into naiTow beaks ; strise
radiant, reaching the median line, the
six central ones sti-onger. = Pinnularia
signata, EM. pi. 34. 6 a. f. 7. Florida.

N. Rostellum (S.).— Small, yenti-icose.
oval, with the apices produced into poin; -
like beaks ; stri.ie indistinct, 80 in -001 .
SBD. ii. p. 93 = i\': opiculata, Greg. MJ.
iv. pi. 1. £ 13. Britain. ,

2 t Valves lanceolate. \
N. Crassinern'a (B.). —Minute, lance-"'
olate, with shortly rostrate apices: stn.T
wanting or indistinct. SD. i. p. 47, pi. 31.
f. 271. Fi-ance, Britain.

N. rhynchocephala (K.). — Slender,
lanceolate, with longly rostrate npic^y
strias wanting or obscure. KB. JJ. l^"-^
pL- 30. f. 35 ; SBD. p. 47, pi. 16- 1. 13--
Em-ope. Is lonc-or and more .'slender tliiui
N. cryptocephala, with more producoii

apices, (vn. 68.) ,

N. /<>;)to;-/iV«o//M5(E.).— Small, smootH.
linear-lanceolate, with sti-aight, subacute,
longly rosh-ate apices. EA. p.
Mexico. Aldn to N. dirlnjnchus, bU'
with longer bealrs.

r

OF THE NAVICTJLEiE.

901

N. leptocephala (Rab.). — Small, lance-
olate, with elongated, slender, obtuse,
somewhat clavate beaks ; strire wanting
or indistinct. Rab D. p. 39, pi. 6. f. 69.
Em-ope.

N. exilis (I^.). — ^Very minute, smooth,
lanceolate, with produced, obtuse apices.
KB. p. 95, pi. 4. f. 6. Germany.

N. rostrata (E.). — Finely punctated,
broadly lanceolate, almost rhomboid,
rapidly tapeiing into acute beaks ; cen-
ti-al nodide lai'ge. EB. 1840, p. 18 ; KB.
p. 94, pi. 3. f. 45. Fossil. Santa Fiore.
1-216". Front view linear^ with trim-
cate apices.

N. Uharotitis (E.). — ^Elongated, smooth,
oblong-lanceolate, with the ends con-
ti-acted into conic beaks. EB. 1845,
p. 239 ; EM. pi. 35. bb. f. 12. Four times
as long aa broad.

N. Otrantina (Rab.). — Oblong-lance-
olate, with rounded, slightly contracted
ends. Rab 1). p. 44, pi. 6. f. 42.

N. dirhynchus (E.). — Small, naiTow-
lanceolate, with conic, rostrate apices ;
stiise wanting or indistinct. EA. p. 130,
pi. 3. 1. f. 11. Falaise, Mexico.

N. Garganica (Rab.). — Minute, lan-
ceolate, suddenly contracted into short,
thick, obtuse apices ; strife distinct, ob-
lique, reaching the median line, six near
the central nodule stouter than the rest.
-Piimularia Garyanica, Rab D. p. 44,
6. f. 41. Italy.

N. amphiceros (K.). — Minute, broadly
lanceolate, with produced, rostrate apices,
and fine stria?. KB. p. 95, pi. 3. f. 39.
Germany, Asia.

'N.steilif/cra (E., K.). — Rhomboid-lan-
oolate, with the apices suddenly atte-
iiiated into obtuse beaks ; the \erj fine
unctated pinnides distinctly radiating
nom the orbicular, smooth umbilical
^pace. KA. p. 70. =Pimmlaria stelligera,
EB. 1845, p. 364. Marine. India.

N. Petersii (E., K.) — Dilated, large at
ach end, suddenly attenuated into a very
hort beak; median line double, with a
iian-ow, longitudinal imibilical space ;
pinnules very fine. KA. p. 70. = I'i?mu-
Uu-ia Petersii, EB. 1846, p. 364. Mouth
iif the river Tagus.

N. f/uttulifcra (Rab.). — Minute, slen-
'lur, acicular, with a glaas-liko globe at
'■ach apex, RI). p. 40, pi. 6. f. 74. South
I'ersia.

N. pachycepliala (Rab.). — Minute,
lender-lanceolate, constricted beneath
tlie capitate apices ; striae converging ;
central nodule stout, teminal ones ob-
solete. = Pimmlaria pachi/ccphala, RD,
p. 43, pi. 6. f. 40. Italy.

N. cincta. = Pinnulana cincta, EM.
pl. 10. 2. f. 6. Bohemia. This species
13 figured as minute, lanceolate, vnth
obtuse apices ; sti'ia3 oblique, those oppo-
site the central nodule radiant and stouter
than the others.

N. Gregorii (Ralls). — Small, nan-ow
linear-lanceolate, contracted at the ends
into minute beaks ; striae distant, parallel,
scai'cely reaching the median line. =
Pinnularia ajnculata, Greg. MJ. iii. p. 41,
pl. 4. f. 21.' Scotland.

N. angustata (S.). — Minute, nan-ow^-
lanceolate, constiicted beneath the capi-
tate apices ; striae indistinct, 45 in -001".
SD. i. p. 52, pl. 17. f. 156. = N. diceplmla ^3,
KA. p. 76 ? Britain, Falaise. Front
view nai-row-linear.

N. cn/ptocephala (K.). — Very minute,
lanceolate, with globose, capitate apices ;
sti-ifB wanting or indistinct. KB. p. 95,
pl. 3. f. 20. Em-ope.

N. Veneta (K.). — Very minute, lan-
ceolate, rather broad, with produced,
slightly obtuse apices; strise wanting
or indistinct. KB. p. 95, pl. 30. f. 76.
Brackish water, Venice. Resembles N.
cryptocephcda, but is shorter and broader.

N. Fusidium (E.). — Narrow-lanceo-
late, distinctly but slightly constricted
beneath the capitate apices. EM. pl. 5. 3,
f. 4. America, Asia.

N. Iqitostylus (E.). — Lateral view
turgid-lanceolate, suddenly tapering into
short beaks with capitate apices. = N.
Platalea, EM. pl. 15 a. f. 42.

N. ampldrrhina (E.) = Pintndaria am-
2}hirrhina, EM. pl. 15 a. f. 20. Lough
Mom-ne deposit, Japan, America. Ehr-
enberg figm-es this species as inflated-
lanceolate, rapidly tapering mto subacute
beaks ; strice parallel.

_N. amplm-hynchus (E.). — Small; tiu--
gid-lanceolate, suddenly constricted at
the ends into short, subcapitate bealfs;
stria3 indistinct or wanting. EA. pl. 3. 1.
f. 10 ; KA. p. 70. Em-ope, Asia, Aus-
ti-alia, Africa, America, (xii. 6.)

N. amphistyhis (E., K.). — Elongated
baciUar, with tm-gid middle, attenu-
ated, filifonn, obtuse apices, and deli-
cate pinnules. KSA. p. 75.=Pin)iidan'a
amphistylus, EB. 1845, p. 79. Fossil.
Oregon. 1-372".

N. ordinata (Br(5b.). — Minute, smooth,
connected in a parallel manner into
short, fragile filaments ; valves slender-
lanceolate, contracted at the ends into
short, often capitate beaks. Br(5b. = jV;
aponina /3, KA. p. 69. Falaise.

N. euryciphala (Rab.). — Large, ro-
bust, oblong, slightly coutractod at the

002

SYSTEMATIC IHSTOllT

OF THE INFUSOniA.

eud>i into very short and broad, tnincatc
beaks. Rab D. p. 40, pi. 0. £ 70. Ger-
iniiiiy. Median line and nodule strongly
developed, liesenibles Stauroneis j^luty-
stoina, but with a rounded, not trans-
verse metlian nodule.

3 1 Valves linear.

N. (Ucephala (E.). — Elongated linear,
constricted at the ends into capitate or
broadly conical beaks; strife either ob-
scure or distinct, 19 in 1-1200". = iV«i;j-
cula and Piimularia dicqjJmla, EM. many
iigmes ; Pinnularia biceps, Greg. MJ. iv.
pi. 1. f. 28? Common. Eui-ope, Asia,
Ai'rica, America. 1-8G0" to 1-480".

l^i. Ijroducta (S.). — Linear, abruptly
contracted at tlie ends into short, obtuse
beaks ; strite faint, 42 to 48 in -001".
SD. i. p. 51, pi. 17. f. 144. = N. cmiphi-
ri/nchus, SD. i. p. 51, pi. 16. f. 142. Britain.
(Vn. 00.)

N. hirostris (E.). — Elongated narrow-
linear, suddenly contracted at the ends
into conical apices ; stri;B distinct, close,
parallel. = Pinnularia hirostris, EM. pi.
15 A. f. 24. Fossil. Lough Mourue de-
posit ; Sweden. This fonn seems scai-cel}'
to difl'er from N. dicephala, except in
having slenderer frustides.

N. (/racillima (Greg.). — Slender, nar-
row-linear, constricted beneath the capi-
tate apices ; costie fine, 27 in -001", not
reaching the median line. — Pinmdaria
(/racillima, MJ. iv. p. 9, pi. 1. f. 31 ; SD.
ii. p. 95 ; Pinmdaria tenuis, MJ. ii. pi. 4.
f. 9? Britain. •

N. linearis (Greg.). — Minute, narrow-
lineiir, constricted beneath the subcapi-
tate ends ; costse very fine, about 40 in
•001", parallel, reaching the median line.
— Pinnularia linearis, MJ. iv. p. 8, pi. 1.
f. 29. Scotland.

N. siihcapitata (Greg.). — Muiute, nar-
row-linear, constricted beneath the capi-
tate ends ; striie subdistaut, conspicuous,
.short. = Pinnularia suhcapitata, MJ. iv.
p. 9, pi. 1. f. 30. Scotland.

N. M(/inensis(GrG'r.). — Minute, linear,
constricted beneath the subquadrato
capitate ends; striai fine, about 30 in
•001", slightly oblique, reaching tlie
median Yu\ii. = Pinnularia Elginensis, MJ.
iv. p. 9, pi. 1. f. 33. Scotland.

N. linipida (Perty). — Ifathor large,
.striated, broadly linear-oblong, suddenly
contracted at the ends into short, broad,
obtuse beaks. I'erty, ]\lic. Org. of Alps,
r. 201, pi. 17. f. 9. ■ Alps. Front view
linear, with truucatt" ends; stria) 10 to
11 in 1-1200".

N. Pisciculus (E., K.). — Elongated,
slender, sti^iated, narrow-linear, slightly
contracted at the ends into conic beaks ;
striae very delicate. KA. p. 75. = Pin-
nularia Pisciculus, EA. pi. 2. 1. f. 30,
Cayenne, India, Falaise.

N. limhata (E.). — Small, linear, eacli
end suddenly contracted into a short,
broad, truncate beak, and a wide border
appeanng within. EA. p. 130, pi. 1. 2
f. 16. ChUi.

N. lonr/iceps (Greg.). — Minute, nar-
row-linear, with the ends conti-acted
into short, obtuse points; nodule inde-
finite ; stria) wanting or inconspicuoui;.
MJ. iv. p. 8, pi. 1. f '27. Scotland.

N. ajjfinis (E.). — Small, linear-oblong,
with the ends suddenly con ti^acted ui :
short, broad, oblnse beaks ; striae waul-
ing or indistinct. EA. p. 129, pi. 2. 2. f.7:
SD. i. p. 50, pi. 16. f. 143. Very common.
Ehrenberg gives upwards of seventv
habitats, (xu. 32.) 1-570" to 1-420".
Resembles N. dicephala.

N. duhia (E.). -.-Small, linear-lanceo-
late, with the ends suddenly contracted
into conic beaks; striie wanting or in-
distinct. EA. p. 130, pi. 2. 2. f. 8. Asia,
Austi'alia, Africa, America. Akin to
N. affinis.

N. amhigua (E.). — Small, oblong,
somewhat inflated, -nnth the ends sud-
denly contracted into short, conic beaks ;
strife wanting or indistinct. EA. pi. 2. 2,
f 9 ; EM. pi. 15 B. f. 15. America, Aus-
tralia, Lough Moiu-ne deposit.
sembles N. uffinis and N. dicejyhala.

N. rostellata (K.). — Minute, sti-iated,
linear-oblong, with elongated, roslTsit
acute apices. KB. p. 95, pi. 3. f. 0
Wangerooge.

N. colmnnaris (E.). — Lai^ge, elongated,
broadly linear, suddenly contracted into
short, very broad, rounded ends, ami
marked by numerous longitudinal liue.-^.
EM. pi. 14. f. 23. Berlin.

N. ampliata, EM. pi. 17. 2. f. 7, .V
pi. 15 A. f. 32. Finland, Siberia, Loiigli
Mom-ne deposit. Ehi-enbei^g's figures re-
present this species as large, snioolh,
broadly linear, suddenly contracted nt
the eiids into broad, rounded, luanmn-
form beaks.

N. Vcspa (R.).— SmaU, linear-oblonir.
constricted beneath the capiiato apico^
nodides minute; striiC parallel, clo>
nearly reaching tlie median line. =i'
mdaria EM. pi. 33. 5. f. 9. A-m;

Africa, America,

N. iiwurra (Greg.). — Small. Imcnr,
with sliglilly siiiiiated .sides; ends con-
tracted into 'short tnmcate beaks ; stnse

OF THE N'AVICXrLE.'E.

903

•wanting or inconspicuous. MJ. iv. p. 8,
pi. 1. f. 2C5. Scotland;

N. apiculata (Brt5b.). — Striated, linear,
suddenly attenuated at each end into a
short apiculus ; front view broad, qua-
di-ate, with striated lateral margins :
striffi strong, 14 in -001", nearly reaching
the median line. Breb DC. p. 16, pi. 1.
f. 20.= Piiimdana rostellata, GDC. p. 16,
pi. 1. f. 20. Marine. Europe. Striae
somewhat radiant. The frustules are
I Rich compressed, and very similai' in
the fi'ont view to those of N. retusa.

4+ Valves subqnadrate or elliptical, with
conical terminal points.

N. lacustris (Greg.). — ^maU, oblong
or subquadi'ate, with acute or shortly
rostrate apices ; stiice fine, distinct,
slightly oblique, nearly reaching the
median line, 28 or 30 in -001". MJ. iv.
p. 6, pi. 1. f. 23. Scotland. The only
species with which this could be con-
foimded is N.Jirma ; but the latter is
longer and lai'ger, of a brown colour,
with finer, less conspicuous, and pai'aUel

•Stl'iiB.

N. hiimerosa (Br6b.). — Striated, sub-
quadrate ; ends truncate, with a minute,
conic central point; strife fine, monUi-
form, 24 in -001", radiant, reaching
nearly to the median line, shorter oppo-
site the roimdish imibilical space. SD.
ii. p. 94 = iV! quadrata, Greg. TM. iv.
p. 41, pi. 5. f. 5. Mai-ine. Em-ope. Ac-
cording to Dr. Donldn, the diy valve,
under a low power, is hyaline and
colourless.

N. gramdida (Breb.). — Striated, rather
large, elliptic or subqnadrate ; ends with
a conic central point ; strise conspi-
cuously moniliform, 16 in '001", radiant,
reaching nearly to the median line.
Donkin, TM. vi. pi. 3. f. 19. Marine.
.Em-ope. Distinguished from N. hume-
rosa Dy its more distant and coarsely
.gi-anidated sti-iiE. " Dry valve of a dull
bluish colour, inclining to purple "
(Donkin).

N. compacta (Grev.). — Small, sub-
quadrate, with slightly concave sides,
rounded shoidders, and the median line
prolonged into conic points ; strite faint,
. 42 in -001", reaching nearly to the me-
^an line. Greg. MJ. v. p. 11, pi. 3. f. 8.
arine. Not imcommon. The striie are
early parallel. A species well marked
a)y its quadrate shape.

_N. lulissima (Greg.). — Broadly oUi^itic,
' Vrith slightly produced mammilorm
ftpicos ; striaj distinct, finely moniliform,

radiant, nearly reaching the median line,
shorter, and leaving an orbicular hyaline
space roimd the central nodule. TM. iv.
p. 40, pi. 5. f. 4. Marine. Britain,
(vn. 70.) Distinguished fi-om N. gra-
mdata by its straw or light-bro^vn colour
in balsam, and less conspicuous granules.

N. Barclayana (Greg.). — Elliptic-
oblong, with minute, conic apices ; striae
about 38 in -001", finely moniliform,
short, forming a narrow marginal band,
and enclosing- a lai-ge, lanceolate smooth
median space. GDC. p. 8, pi. 1. f. 9.
Marine. Britain. The marginal striated
band is of nearly imiform breadth, ex-
cept near the base, where it becomes
naiTower.

N. marina(Rs}£3). — Oval, with slightly
produced conic apices, and 33 distinct,
moniliform, radiant striae in -001", which
reach the median line. = N. punctulata,
SD. p. 52, pi. 16. f. 151. Marine. Eng-
land.

N. pr-oducta (Ealfs). — Oblong-elliptic,
much constricted at each end, as if ob-
tusely mucronate ; sm-face elegantly
marked by decussating pimctated lines;
puncta in quincunx. =iV; decussata, EB.
1843, p. 256. liabit of N. Amphishcsna.

G. Valves lanceolate or rhomboid.

N. rliomhoides (E.). — Rhomboid-Ian-'
ceolate, with subacute apices and 85,
very faint, parallel strios in -001". EA.
pi. 3. 1. f. 15 ; SBD. i. p. 46, pi. 16.
f. 129. Mexico, Europe, Australia.

N. rhomhica (Greg.). — Rhomboid-
lanceolate, with very tine but distinct
sti-ia3, 45 in -001", reaching the median
line. MJ. iii. p. 40, pi. 3. f. 16 ; TM. iv.
p. 38, pi. 5. f. 1. Mai'hie. Scotland.
(yti. 71.) Accordmg to Professor Gre-
^017, N. rhombica is distinguished from
JSf. rhomboides by the different appear-
ance of its median line and central
nodule, as well as by its distinct striae.

N. rhombea (E.). — Broadly rhomboid-
lanceolate, vni\\ acute apices, and delicate
longitudinal lines on each side; trans-
verse strite wanting or indistinct. EA
p. 131, pi. 3. 7. f. 27. Mexico. 1-480"
to 1-360".

N. Dcmeranc (E.). —Smooth, rhom-
boid, tumid, strongly tapering into acule,
subrostrato apices. EB. 18 15, p. 79.
Domerara. 1-576". " Distinguisiied from
N. rhombea only by its subrostrate ends "
(Rabenhorst).

N. deciissntn (E., K.). — Rhomboid-
lanceolate, with subacute apices, an ob-
solete umbilical space, and very fine,

904

SYSTEMATIC UISTOEY

OF THE INFU«OttIA.

decussating, punctated strise. ICA. p. 70.
z=Pinmtlaria decussata, EB. 1845, p. 8G4.
Marine. India.

N. Inclica (E.). — Rhomboid-lanceo-
late, with somewhat obtiLse apices, a
small umbilicus, and thick-set, fine, lon-
gitudinal, punctated lines (8 on each
side). EB. 1845, p. 363. Maiine. India.
Somewhat resembles N. decussata.

N. ? asperula (E., K.). — Turgid, short,
rhomboid-lanceolate, six-angled, rough
with punctated strife ; umbilicus subor-
bicular; the longitudinal median space
much dilated near the umbilicus. ICA.
■p. 71. = Pirnmlaria? asperula, EB. 1845,
p. 364. Marine. India.

N. Libelliis (Greg.). — Rhomboid-lan-
ceolate, with obtuse ends; sti-ise fine,
imifoiin, about 60 in -001", reaching the
median line ; front \'iew broadly lineai",
with the central portion longitudinally
lined. GDC. p. 57, pi. 6. 1 101. Scotland.
In form it much resembles N. rhom-
hica, but is more obtuse and broader,
with imiform striae. Professor Walker-
Amott regards this species as escaped
frustides of Schizonema GrevtUii, — an opi-
nion, indeed, shared by Professor Gre-
gory himself.

In. suhtilis (Greg.). — Elongated, trans-
lucent, very slender, rhomboid-lanceo-
late, with a minute, definite nodule;
costse about 30 in -OOl", parallel, reach-
ing the medifm line. = Pinmdaria subtilis,
GDC. p. 16, pi. 1. f. 19. Mai-ine. Scot-
land.

N. lanceolata (Ag., K.\ — Minute,
narrow-lanceolate, with M indistinct,
parallel strije in -001". KB. p. 94, pi. 28.
f. 38 ; SD. i. p. 46, pi. 31. f. 272. Europe,
America.

N. sen'ans (K.). — Small, lanceolate,
with fine longitudinal lines, and subacute
apices ; fi-ont view broadly linear. KB.
p. 92, pi. 28. i. 43; SD. i. p. 47, pi. 16.
f. 130. = JV. lineolata, EM. several figiu-es.
Europe, Asia, Australia, Afiica, Ame-
rica. 1-288". Ei'ustules freciuently co-
hering.

N. Suhda (K.). — Elongated, slender,
naiTow-lanceolate, with tapering, sub-
acute apices, and fine longitudinal lines.
KB. p. 91, pi. 30. f. 19. Mai-ine. Em-ope.

N. tcncUa (Breb.). — Minute, smooth,
veiy naiTow - lanceolate, with acute
apices ; front view linear, slightly con-
stricted at the middle. KA.p. 74. Europe.

N. ampMoxys (^E.). — Elongated, nar-
row-lanceolate, with acute apices ; striaj
indistinct or wanting. EA. pi. 1. 2. f. 8 ;
EiSI. ninny figures. Europe, Asia, Aus-
tralia, Africa, America, Lough Mounio

depo8it._ More slender than N. yrucUk.
Front view nalTo^vl-linear.

N. Cari (E.).— Minute, smooth, lance-
olate, slender, acute at both sides, with a
circular median nodule. EI. p. 179 • EM
pi. 12. f 20. Fossil. Cassel. 1-11,50"."

N. oxyphjllum (K.). — PeUucid, glas-sy,
smooth, slender -lanceolate, gi~,vdually
tapering to the acute apices; median
nodule obsolete. ICB. p. 92, pi. 30. f. 17.
Maiine. Near Flinsburg.

N. ■ velox (K.). — Mmute, smooth,
broadly or oblong lanceolate, with acute
apices. KB. p. 91, pi. 3. l 06. = i\': ob-
luiu/a, EA. pi. 3. 1. f. 14. Wangerooge,
Mexico.

N. apmina (K.). — Minute, smooth,
slender-lanceolate, with acute, subros-
ti-ate ends. KB. p. 91, pi. 4. f. 1. Europe.
Front "view narrow-linear.

N. C'esatii (Rab.). — Minute, smooth,
slender-lanceolate ; fi-ont view linear,
witli rounded ends. Rab D. p. 39, pL 6.
f 89. Piedmont. Veiy like N. aponim,
but more slender in the lateral, and
broader in the front view.

N. digito-radiata (Greg.). — Small, ob-
long-lanceolate, with obtuse ends; stiiii
fine, distinct, aljout 25 in "001", reacliiiu
the median line, those neai- the centi-al
nodule more distinct and highly radiant
= Pinnularia digito-radiata, MJ. iv. p. 9,
pi. 1. f. 32. Scotland.

N. Solaris (Greg.). — Elongated, nar-
row-lanceolate, Asath obtuse ends ; strisB
fine, very distinct, 36 in 'OOl", oblique,
radiant, and shorter opposite the inde-
finite central nodule. TM. iv. p. 43,
pi. 5. f 10. Maiine. Scotland. Colour
brown; strife so highly radiant round
the centi-al blank spot as to present tli
appearance of a sim -with rays. It
longer than N. radiosa, -n-ith finer and
more inclined strife.

N. 3Icditerranea (K.V— Minute, nar-
row-lanceolate, with obtuse apices and
20 strife in 1-1200" ; fi-ont view stiictlv
linear, truncate. KB. p. 93, pi. 3. f 17.
Marine. Europe. 1-1200".

N.punctulata,'EU. pi. 15a. f.34,B.f.l3,
14. Lough Moume deposit, Sweden,
Africa. Ehrenberg figures this specie?
as rhomboid-lanceolate, with longitu-
dinal, pardlel, dotted lines.

N. oppriidicuMa (Ag., K.).— Mmuto,
lanceolate, with sliglitly tui^d mum'
and subrostrale obtuse ends. KB p. 9.).
pi. 3. {. 2S.=Frusfiilia and CymhcUa ap-
pmdimlata, Ag. Europe. Front view
linear, with truncate ends. In the lateral
view the apices are somewhat produced,
but scarcely rostrate.

OF THE NAVICULE.^;.

905

N. obtusa (E.). — Small, oblong-lan-
ceolate, yvith obtuse, roimded apices.
EA. p. 131. North America, Asia,
Africa. Kiitzing thinks it probably
identical -with iV. appendiculata.

N. wjlexa (Greg.). — Small, lanceolate,
vdth subacute apices; costse conspi-
cuoiis, 26 in -001", nighly radiant, nearly
reaching the median line, except oppo-
site the central nodule, where they are
short, lea^ang a large, roundish blank
s'pace. = Pinmdaria injiexa, TM. iv. p. 48,
pi. 5. f. 20. Scotland. Beneath each
apex is a strong, dark cross-bar, pro-
bably caused by a depression, Greg.

N. fortis (Crveg.). — Small, oblong-
lanceolate or somewhat rhomboid, with
obtuse apices ; costoe conspicuous, 16 in
•001", not reaching the meditan line,
gi'adually shorter and more radiant near
the central nodule. = Pinmdaria foHis,
TM. lY. p. 47, pi. 5. f. 19. Scotland.
Turgid ; costte prominent, so as to appear
more distant than they actually are.

N.??)?<<i'crt (K.). — Very minute, smooth,
turgid-lanceolate, with distinct median
and terminal nodules. KB. p. 93, pi. 3.
f. 32. Wangerooge. 1-1560".

N. Jurgensii (K.). — Minute, smooth,
tm'gid or oblong-lanceolate, with obtuse
apices and obsolete median nodule ; front
■view broadly linear, with tnmcate ends.
KB. p. 93, pi. 3. f. 8. Island of Wan-
gerooge, Gei-many. 1-720".

]>i . inridida (K.). — Small, lanceolate,
with obtuse, slightly produced apices;
striae wanting or indistinct. KB. p. 91,
pi. 4. f. 10. 15. Em-ope.

N. carinata (E.). — Large, lanceolate ;
front view linear, with a broad dorsal
longitudinal keel. EB. 1840, p. 18.
Fossil. Shores of the Rhine, in volcanic
schists. 1-216".

N. diaphana (E.). — Large, smooth,
diaphanous, elongated, lanceolate, with
obtuse apices ; the umbilicus intercepting
the double median line. EB. 1845,
p. 78. Guiana. 1-192". Habit of /SaM-
rmieis phcBnicenteron.

N. Schojnburgkormn (E.). — Large,
elongated, lanceolate, with obtuse apices,
and the habit of N. dia}}hana, but -with
three longitudinal median lines, EB.
1845, p. 70. Guiana. 1-180".

N. latiusmla (K.). — Rather lai'ge,
oblong or elliptic-lanceolate, with ratlier
obtuse apices ; striaj shorter opposite tlie
central nodule, 10 to 12 in 1-1200".
KB. p. 9.3, pi. 5. f. AO. = N.patu/a, SD.
i. p. 49, pi. 10. f. 139. Eiu-ope, Ireland.
Twice ns long as broad ; front view
broadly linear, with trmicate ends.

N, Scliomhurghii (E., K.). — Large,
lanceolate, equal, three times as long
as broad, witli subacute apices, and 25
strite in 1-1152". KA. p. 71. = Pin-
mdaria Schoniburf/kii, EB. 1845, p. 80.
Guiana. Is smaller and more oDtuse
than iVi aqualis.

N. palpehralis (Br<§b.). — Broadly lan-
ceolate, with subacute apices, and 27
radiant striae in -001", which do not
reach the median line. SD. i. p. 50,
pi. 31. f. 273. Marine. France, Britain.
Strife short, leaving a lanceolate median
blank space.

N. angalosa (Greg'.). — Broadly lanceo-
late or oblong, with subacute apices j
striae conspicuous, short, forming a nar-
row margmal band, shorter near the
middle, and leaving a smooth, rhomboid
median space. TM. iv. p. 42, pi. 5. f. 8.
Marine. Britain. N. angidosa is larger
than N. palpeh-alis, and the angidar me-
dian space is a good and pennanent mai'k
of distinction ; nodule deiinite.

N. radiosa (K.). — Small, slender-
lanceolate, with subacute apices, and
from 15 to 18 distinct, radiant striae in
1-1200". KB. p. 91, pi. 4 f. 23. = Pin-
mdaria radiosa, SD. ijp. 56, pi. 18. f. 173.
Gennany, Britain. With stronger strife
than N. gracilis.

N. mdpina (K.). — Rather turgid, lan-
ceolate, with acute apices; front view
broadly linear, wdth ti'imcate ends and
punctate margins ; striae obsciu-e. KB.
p. 92, pi. 8. I 43. Gei-many. Inter-
mediate between N. gracilis and N. cus-
pidata.

N. cuspidata (K.). — Broadly lanceo-
late, with acute apices, a very minute,
orbiculai- central nodule, and close, very
fine transverse striae. KB. p. 94, pi. 3.
f. 24, 37 ; SD. i. p. 47, pi. 16. fri31. = A'b-
vicida fidva, EM. many figm-es. Common.
Eiu'ope, Asia, Afiica, America, (xii. 5.)
Front view narrow-lineai-. 1-1150" to
1-180". The lateral view is broader and
more rhomboid than in N. gracilis.

N. Cantoncnsis (E.). — Broadly oblong-
lanceolate, -with acute, slightly produced
apices ; stria3 wanting or indistinct. EB.
1847, p. 484. Canton. 1-480". Itdiilers
from N. cuspidata in its shorter and acute
apices.

N. amplmphenia (E.). — Lanceolate,
navicidar, gradually attenuated into the
apices, with an oblong median nodule;
strife wanting or obscure. EA. p. 120-
EM. pi. 9. 1. f. 10. America, Asia, Africa)
Europe. Distinguished from N. cuspi-
data by its oblong iiodido.

N. phylkpta (K.). — Minute, slender,

906

SYSTEMATIC 1U8T0EY 01' TITE INTUSOBIA.

smooth, naiTow-lanceolate, with acuto
apices; front view strictly linear, with
truncate ends. KB. p. 94, pi. 30. f. 56.
Marine. Em-ope.

N. Melear/ris (K.). — Somewhat turgid,
lanceolate-acuminate, with an elegantly
punctate margin. KB. p. 92, pi. 30. f. 37.
Marine. Em-ope. Front view broadly
lineal-.

N. gracilis (E,). — Small, elongated,
slender-lanceolate, with subacute ends;
strifB very fine, radiant, 22 in -001",
reaching the median line. E. Infus.
p. 176 ; EM. many figures. Em^ope, Asia,
Africa, America, Lough Mom-ne deposit.
1-1500" to 1-560".

N. oxypUra (K.). — Elongated, slender,
narrow-lanceolate, with acute apices, and
fine, slightly radiant, transverse strige.
KSA. p. 69. = Pitmularia ainphioxys, EM.
manyfigm-es ; P. acuta, SD. i. p. 56, pi. 18.
f. 171. Europe, Asia, Australia, Africa,
America.

N. Kefvingensis (E.). — Small, striated,
lanceolate, navicular; striae converging
at the centre, 17 in 1200". EB. 1840,
p. 20. = Pinnuluria Kefvingensis, EM.
pi. 10. 2. f. 4, 5. Fossil. Bohemia,
Asia.

N. peregrina (E., K.). — Striated, nar-
row-lanceolate, gradually tapering to the
subacute apices ; pinnules oblique, reach-
ing the median liue, 13 in -001". KB.
p. 97, pi. 28. f. 52. = Pinnularia peregi-ina,
EA. p. 133, several figm-es ; SD. i. p. 56,
pi. 18. f. 170. Mai-ine. Em-ope, Asia,
Africa, America.

N. Icptostigma (E.). — Striated, lan-
ceolate, with subacute, slightly produced
apices; the ti-ansverse dotted striae in-
conspicuous. EB. 1845. = Pinnidaria
leptostigma, EM. pi. 33. 12. f. 25. Fossil.
United States. Twice as long as broad.
1-432".

'N . Uhrenberg{{(K.). — Lanceolate, with
somewhat acute apices, and fine, radi-
ating stria?. KB. p. 92, pi. 3. f. 38. =
Navicula lanceolata, E. Inf. pi. 13. f. 21.
Europe.

N. neglecta (K.). — Tm-gid, lanceolate,
with subacute apices, margins longitu-
dinally costate and transversely striated.
KB. p. 92, pi. 28. f. 44.= Pinnularia lan-
ceolata, EA. pi. 3. 1. f. 6. Europe, Ame-
rica. Front view oblong, ^vith incras-
satod middle and truncate ends. 1-1150"
to 1-280" ; striffl 13 in 1-1200".

N. Sempronia (Forty). — Minute,
acutely lanceolate ; striaj not reaching
the median lino ; front view liuoai-,
slightly narrowed towards tlio ends.
I'orty, Microsc. Org. p. 204, pi. 17. f. 8.

Alps, lielongs to the smaller species,
and is very like N. exilis.

N. directa (S.). — Slender, narrow-
lanceolate, acute; costae fine, parallel,
reaching the median line, 20 in -OOl".
= Pinnuluria directu, SD. i, p. 50, pi. 18.
f. 172. Marine. Sussex. Front view
narrow-linear.

N. inilchru (Greg.). — Broadly lanceo-
late or somewhat rhomboid ; striae radi-
ant, strongly monilifoi-m, nearly reaching
the median line, shorter opposite the
slightly dilated indefinite nodules. TM.
iv. p. 42, pi. 5. f. 7. Marine. Scotland.
Rapidly tapei-iag to the obtuse apices.

N. longu (Greg.). — Much elongated,
lanceolate or slightly rhomboid, acute;
costaj conspicuous, about 12 in -001",
nearly reaching the median line, some-
what shorter and radiant opposite the
central noAvile.=Pimiularia longa, Greg.
TM. iv. p. 47, pi. 5. £ 18. Scotland. The
only Imown form to which it has any
resemblance is iV. directa, but the latter
foi-m is not rhombic, and the sti-iae are
much more numerous and paralleL

N. acutiusculu (Greg.). — Elongated,
slender, linear-lanceolate, acute; costae
distinct, about 30 in -001", reaching the
median line, centi-al ones radiant and
more conspicuous. = P/?«H?^/fl?-;a acuiius-
cula, TM. iv. p. 48, pi. 5. f. 21. Scotland.

N. costutu (K.). — Oblong-lanceolate,
with obtuse apices, and longitudinal
pimctated lines; median nodule lai-ge,
terminal ones minute. KB. p. 93, pi. 3.
f. 56. Fossil. Santa Fiore. Front
view oblong, with broadly rounded
apices.

N. Norvegica (E., K.). — ^Broadly ob-
long, with acute apices, a narrow striated
border, and a smooth median space ; striae
30 in 1-1200". KA. p. 79. = Pinnidaria
Norvegica, E. Mai-ine. Europe. Front
view narrow-linear, truncate. 1-360".

N. Libyca (E.). — SmaU, stTiated,
acutely oblong-lanceolate, -with 14 strias
in 1-1200" ; front view quadningidiur,
■with ti-uncate ends. EB. 1840, p. 20.
Sinai. 1-550". It has the habit of If.
fulvn, but is wider, and not rostrate.

N. Pupula (K.). — Minute, smootlu
oblong-lanceolate, with slia-ht produced
apices. KB. p. 93, pi. 30. £ 40. Europa.

N. alpina (S.). — Large, oblong-lan-
ceolate, with obtuse ends, ami 7 to 9
stout, distant, radiant costaj in •001">
which do not reach the median liue.=
Pinmdaria alpina, SD. i. p. 55, pi. 1&
£ 108. France, Scotland, l^ont view
broadly linear, with ti-uncate ends; costtB
shorter near the central nodule.

OF THE NATICULEJ!.

907

N. distmts (S.). — Lanceolate, -with
subacute apices ; costre radiant, distant,
10 in •001", not reaching tlio median
lme. = Pitmiihin'a (h'stans, SD. i. p. 56,
pi. 18. f. 1G9. Marine. Common, espe-
cially from deep dredgiug's. Costae
shorter opposite tlie central nodule.

N. eleyans (S.). — Broadly or elliptic
lanceolate, with slightly acuminated
ends; sti'ife distinct, 24 in -001", waved,
Tadiate, nearly reaching the median line,
shorter opposite the central nodule.
SD. i. p. 49, pi. 16. f. 137. Marine.
England.

N. permagna (Bai.). — Large, tm'gid-
lanceolate, with obtuse apices, a mai-
ginal band of pimctated strife, and a
broad, lanceolate, longitudinal median
blank space ; nodide iudetinite. =P«Hm<-
1 aria per murjna, BMO. p. 40, pi. 2. f. 28 &
38. United States.

H. Valves linear or oblong, neither
rostrate nor constricted.

t Ends scarcely cuneate.

N. BaciUum (E.). — Linear, with trun-
cate, roimded ends ; strite indistinct, 54
in -001". EM. several figiu'es. = iVi hacil-
htris, Greg. MJ. iv. pi. 1. i. 24. Ehi-en-
berg gives about 50 habitats in Em-ope,
Asia, Australia, Africa, and America.

N. borcalis (E., K.). — Small, striated,
linear, with slightl}' attenuated, rounded
apices ; stria3 stout, rather distant, not
reaching the median line, 13 in -001".
KB. p. 96, pi. 28. f 68-72. = Pinnularia
horealis, EM. nimierous figures; Pinnu-
laria latestriata, Greg. MJ. ii. pi. 4. f. 1.3.
(vn. 74.) A veiy common and widely
dilliised species. Ehrenberg gives about
200 habitats for it. )3 longer and more
dilated at the middle, = Pinnularia
C'araccana, E. Under moss on trees.
The front view of this species is linear,
with truncated ends and striated mar-
gins, and resembles that of detached
ti-ustules of Denticida and Odoutidium.

N. Cldlcmis (]<]., K.). — Largo, linear,
with broadly rounded apices, and 11 or
12 stout costaj in 1-1200". I^A. p. 79. =
Pinnularia CJiilonsii, EM. pi. 34. 11. f. 3.
Australia, Asia, Africa, America, (xii.
33.) Gostre parallel, equal. Approaches
to N. viridis, but is shorter and broader.

N. rectamjidata (Greg.). — Linear, with
ti'uncate roimded ends ; costro rather di-
stant, 22 in -OOl", neariy reaciiing the
niodian line, except onposito the dilated
indefinite nodule, and there sliortin- and
diverging. GDC. p. 7, pi. 1. f, 7. Marine.
Scotland.

N. Iridis (E.). — Largo, elongated,
linear-oblong, tapering into the obtuso
apices, finely striated both longitudinally
and transversely, iridescent. EA. p. 130,
pi. 4. 1. I 2. New York.

N. oblonga (K.).— Elongated, slender,
oblong or lineai-oblong, with roimded
apices ; costio stout, connivent at the
centre. KB. p. 97, pi. 4. f. 2l.=Pinnu-
laria jiolyptcra, EA. p. 133 ; P. macilenta,
E. Common. We follow Kiitzing and
Smith in referring P. macilenta, E., to
this species ; Ehrenherg's figiu'es, how-
ever, differ from theirs in being more
linear, with less tapering apices. 1-140".

N. Oregonica (E., K.). — Elongated,
bacillar, imLfornily and gradually de-
creasing towai'ds the rounded apices;
pinmdes stout, 23 in 1-1152", KA.
p. 71. =Pinnidaria Oregonica, EB. 1845,
p. 79. Fossil. Oregon. 1-228". It
approaches to N. Digitus, but is more
slender.

N. truticata (K.). — Minute, smooth,
linear, with tmncato-roimded ends, and
an inner marginal border tsvice con-
stricted ; front view broadly linear,
tnmcate. KB. p. 96, pi. 3. f. 34. Eu-
rope.

N. Liber (S.). — Linear-oblong, with
rounded apices, and 48 delicate sti-iaa in
•001" ; colour of dry valve piu-plish.
SD. i. p. 48, pi. 16. f. 133. Marine.
Sussex.

_ N. Stylus (E.). — Elongated, narrow-
linear, with roimded ends, and having
longitudinal dotted lines on each side.
EM. j)l. 15 A. f. 36. Asia ; Lough Moume
deposit.

N. Ergadensis (Greg.).— Rather small,
narrowly linear-oblong, %vith roimded
ends ;_ costaj distinct, 25 in -001", nearly
reaching the median line, shorter and
radiant opposite the roundish, smootli
umbilical s^acq. = Pinnularia Eniademis,
TM. iv. p. 48, pi. 5. f 22. Scotland.

N. styhformis = Pinnularia sti/liformis,
EM. ^)1. 38 A. 17. £ 6. Australia, Africa^
America. Elirenberg's figiu-e represents
a portion of an elongated, narrow, strictly
linear valve, with rhomboid ends, and fine,
parallel striie which reach the median
lino.

N. DactyhK (E., K.).— Large, clou-
gated, linear-oblong, passing by a very
gentle curve into tlie sliglitly narrower,
broadly rounded apices ; pinnules 14 in
1-1200". KB. p.'oS, p{. 28. f. 59.=
Pinnularia Daciylus, EA. p. 132, pi. 4. 1.
f. 3. Europe, Asia, Africa, America!
Lough Mourne deposit.

N. viridis (Nitzsch, K.).— Elongated,

908

SYSTEMATIC HISTOET

OF Tins nrFusoniA.

slender, linear-oblong or linear lanceo-
late, with obtuse apices ; 12 to 14 radiant
costrs in 1-1200", shorter opposite the
central nodule. KB. p. 97, pi. 4. f. 18.=
Pinnularia viridis, E., in part ? ; Naviciila
viridtda, E. (ix. 133-136.) Common.
1-3000" to 1-280".

N. he')m2}te7-a (K.). — Nari'ow, linear-
oblong, with obtuse, conic apices, aad
14 or 15 radiant costte in 1-1200", which
do not reach the median line. KB.
p. 97, pi. 30. f. 11. = Pinnularia hemiptei-a,
SB. ii. p. 95. America, Em-ope. Front
view lineal', with roimded angles. Often
overlooked from its resemblance to N.
viridis, from which it is distinguished by
its finer strife and naiTower valve.

N. cBquinoctialis (Mont.). — Rather
lai'ge, linear-oblong, with roimded apices,
and 4 stout, radiant pinnules in 1-2600".
Montague, Annales des Sciences Nat.
1850, p. 309. Guiana. 1-260" to 1-150".
In form it resembles N. Dacti/hts, but
differs in its size and much laro-er striae.
In the latter respect it approaches to iV.
pacht/ptera, but has not the median infla-
tion of that species.

N. plcu7-opJiora (K.). — Large, stout,
oblong, or linear-oblong, with broadly
rounded ends, and 6 stout costse in
1-1200". KA. p. 79. ^Pinnularia costata,
EM. pi. 4. 2. f. 5 ; Pinnularia megaloptera,
EM. pi. 3. 1. f. 4. America, Asia.

N. Suecica (E.). — Oblong-eUiptic, with
broadly roimded ends, short, stout, rather
distant marginal costfe, and large central
blank space. E Inf. p. 189, t. 21. f. 18. =
Pinnularia Suecica, 'EM. Fossil. Sweden.

N. lata (Breb.). — Large, linear-ob-
long, with roimded apices, and 8 stout
costse in -001", which do not reach the
median line, and are shorter and some-
what conuivent opposite the central
nodule. KA. p. 79. = Pinnularia lata,
SB. i. p. 55, pi. 18. f. 167. France, Bri-
tain. Front view very broad linear, with
rounded angles, truncate ends, and
striated margins; the central nodules
large. This species approaches closely
in character to N. Suecica.

N. Dit/itus=Pin7iuluria Digitus, EM.
pi. 33. 8." f. 15 ; pi. 38 a. 3 b. f. 1. Ame-
rica, Java. This species is figiu-ed aa
large, linear-oblong, with broadly
rounded ends, and stout, parallel costos
which do not reach the median line.

N. Dux=Pinnidaria Dux, EM. pi. 8. 2.
f. 5. Fossil. Hungary. Ehrcnberg repre-
sents it 08 large, elliptic-oblong, with
rounded ends and divergent costtc, which
do not reach the median line, and arc
shorter opposite the central uodidc.

N. ostrearia (K.). — Small, elliptic-
oblong, with rounded ends, large central
nodule, and close, fine stria). KA. p. 77.
Mfirine. France.

N. retusa (Br6b.). — Sti-iated, namw-
linear, with rounded ends; front -view
broad, quadi'ate, with romided angles,
truncate ends, and concave and stiiated
lateral mai-gins. Breb BC. p. 10, pi. 1.
f. 6. Marine. Em-ope. The frustules
are much compressed ; and con.sequenlly
the front view is so much broader than
the lateral sm-faces, that it is diflicult to
obtain a good sight of the latter. N.
retusa, N. apiculata, and a few allied spe-
cies probably ought, as suggested by M.
de Br^bisson, to foim a separate group, if
not a distinct genus, distinguished by
the gi'eat comparative breadth of its
front view, with its sti-iated and sinu-
ated or constiicted lateral margins.

N. scita (S.). — Nitescent, linear-ob-
long, with attenuated, obtuse ends; strias
very faint, 45 in -001" ; nodule smaU.
ANH. 1857, xix. p. 8, pi. 2. f. 4. Pyrenees.

N. parvida (Greg.). — Small, narrow
linear-lanceolate, with obtuse ends and
distinct costEe, which do not reach the
median \me. = Pinmdaria parva, MJ. ii.
p. 98, pi. 4. f. 11. Mull.

2 t Valves linear or oblong, with
cuneate ends.

N. amphigomplms (E.). — Large,
broadly linear, with shai-ply cuneate ends,
with or without obscm-e longitudinal
lines ; striae obsolete or distinct. EA
p. 129, pi. 3. 1. f. 8; EM. many figures.
America, Asia, Em-ope. Lough Moume
deposit. /3, sti-ia3 distinct. = Pinnularia
amphigomjyhus, EM. pi. 14. f. 11.
Cavenne, France.

f^. dilatata (E.). — Lai'ge, oblong or
broadly lineai-, with obtuse, cuneate ends,
and fiu-nished -mXh. longitudinal lines
near the margins. EM. many figures.
Em-ope, Lough Mounie.

N. diqyhenia (E., K.). — Linear, elon-
gated, -with, shai-ply cuneate ends, finely
striated neai- the margins. KB. p. 93,
pi. 28. f. 54. = Pinnularia disphcnia, EA
p. 132. America, Australia. Approaches
to N. amphi</omphus.

N. acuta (K.).— NaiTow-lmear, smooth,
with acute, shortly cimcate .apices. KB.
p. 93, pi. 3. f. 49. Island of angerooge,
Australia.

N. subacuta= Pinnularia subacuta, LM.
pi. 35 A. 0. f. 12. Perth, Austraha.
Elii-enbcrg's figiu-e represents this species
as lineal-, with cuneate apices, fine, close,

OF THE NATICULEiE.

909

parallel sti'm, which reach the median
line, and a small central nodule.

N. acuminata (S.). — Linear, with
acutely cuueate ends and parallel costse,
which do not reach the median liue.=
Pinnularia acuminata, SD. i. p. 55, pi. 18.
f. 164. Premnay peat.

N. minor (Greg.). — Minute ; lateral
view linear, with acutely cuueate ends ;
striae fine, nearly parallel, not reaching
the median line, 36 to 40 in -001". GDC.
p. 6, pi. 1. f. 1. Scotland.

N. crassa (Greg.). — Linear- or elliptic-
oblong, with obtusely cuneate ends;
sti'iiB fine, but distinct, moniliform, radi-
ant, nearly reaching the median line, but
leaving an orbicular blank space roimd
the central nodule. MJ. iii. p. 41, pi. 4.
f. 18. Scotland. Is of a brown colom"
in balsam.

N. Utriculm (E., K.). — Striated,
linear-oblong ; ends attenuated, with a
slight marginal curvature, into the obtuse
apices. KLB. p. 9S. = Pin}iularia Utri-
culus, EA. p. 134. Mexico. Aliin to
N. disphenia.

N. trif/onocephala ^E.). — Striated,
linear, with the ends dilated into lai'ge
cuneate heads. = Pinnularia trigonoce-
phala, EM. pi. 34. 8. f. ]1._ Japan. Veiy
unlike any other species in having the
cuneate heads much dilated and broader
than the intermediate portion.

N. microstoma (K.). — Large, tiu'gid,
elongated oblong, with obtusely cuneate
ends, longitudinal lines, and a veiy mi-
nute oblong median nodule ; strijB nume-
rous, obscure. KA. p. 71. = JV; lata, 1£B.
p. 92, pi. 3. f. 51 ; N. jirma, SD. p. 48,

{)1. 16. f. 138. Europe. Front view broadly
inear, with tmncate ends, rounded an-
gles, and broad lateral borders, turgid at
the middle. Perhaps Professor Smith
was right in imitinj; this to N. firma.

l^.firma (K.). — Large, tm-gid, oblong-
lanceolate, with obtuse, cuneate ends,
thick borders, and large median nodule ;
striae wanting or obscure. KB. p. 92,
pi. 21. f. 10. Fossil. Santa Fiore.
_ N. maxima (Greg.). — Large, striated,
linear, with longitudinal lines, and ob-
tuse, cuneate or conic ends ; striae fine,
parallel, nearly reaching the median lino,
shorter opposite the centi'al nodule,
about 52 m -001". GDC. p. 15, pi. 1.
f. 18. Marine. Britain. (vit. 75.)
Generally elongated; nodule definite,
suiTounded by a smooth space. Front
view linear, naiTowest at the middle,
with striated margins. Difl'ers from N.
firma in its paler colom-, finer strioB, and
more obtuse apices, Greg.

lii. fonnosa (Greg.). — Large, sti-iated,
linear or linear-oblong, with longitudinal
lines, obtuse, cmieate or conic ends ;
striae distinct, slightly inclined, not
reaching the median line, shorter oppo-
site the lai'ge central nodule, about 35
in -001". TM. iv. p. 42, pi. 5. f. 6.
Marine. Scotland. Agi-ees in form with
N. maxima, but is distinguished by its
more conspicuous and slightly inclined
striae which do not reach the median
line, leaving a longitudinal median blank
band.

N. Kerguelemis (R.). — Oblong, with
obtusely cuneate ends ; costas stout,
radiant ; nodule indefinite. = Pioinularia
Kei-guelensis,'EM..^l. 35 a. 2. f. 15. Africa.

I. Valves elliptic, with rounded ends.

N. cocconeoides (Rab.). — Small, ellip-
tic, with broadly roimded ends, and 11
to 13 parallel and distinct, but faint
strios in 1-1200", which reach the median
line. — Pinmdaria cocconeoides, Rab D.
p. 43, pi. 6. f. 18. Stockholm.

N. scutelloides (S.). — Small, subor-
biculai", with 18 monilifomi, radiant
striae in -001", nearly reaching the
median line. SD. ii. p. 91 ; Greg. M J. iv.
pi. 1. f. 15. Britain.

N. peclinalis (BriSb.). — Linear-elliptic,
with roimded ends, and 22 striae in -001".
SD. ii. p. 92. Marine. France, Britain.
Front view with trimcate ends.

N. Algeriensis (Mont.). — Elliptic-ob-
long, with 10 striaj on each margin,
M. Fl. d'Alg^r. p. 190. Marine. Algiers.

N. Cluthensis (Greg.). — Elliptic, with
broadly rounded ends; strife conspicu-
ous, moniliform, reaching the median
line, about 20 in -001"; median line
broadest at the central nodule, slightly
attenuated towards the ends. GDC,
p. 6, pi. 1. f. 2. Scotland, (ra. 73.)

N. ovalif (Niig.). — Finely striated,
oval elliptic ; front view broadly lineai-.
1-720" to 1-000''. Ii^^.p.890. Switzer-
land.

N. ohlongella (Nag.). — Smooth, ob-
long-oval ; front view broadly linear
1-720" to 1-430". KA. p. 890. Switzer-
land.

N.fossilis, EM. pi. 10. 1. f. 6. Bohemia.
Ehrenber^'s figure sliows this species
elliptic, slightly rlioniboid, with rounded
ends ; the median sutiu-e of three lines
interrupted by the indefinite central
nodule.

N. nana (Grog. ilfS).— Minute, oval,
obtuse; costse radiant, nearly reacliino-
the median line; umbilical space not

910

SYSTEMATIC mSTOEY OF THE TNPUSOfilA,

dilated. = Pinnularia ptjipncea, E]\I.
pi. 10. 1. f. 9; MJ. iv.' pi. 1. f. 8.
Em-ope.

N. Iqnda (Greg.). — Minute, hyaline,
oval, or oblong, with obtuse ends ; strife
indistinct from their transparency,
slightly radiant. MJ. iv. p. 7, pi. 1.
f. 25. Scotland.

N. occanica. — Elliptic-oblong, twice
as long as broad, with subacute apices,
small, round, clearly-defined umbilicus,
and double median line; margin deli-
cately but widely striated ; pinnules 20
in 1-1200". Southern Ocean. 1-570".

K. Median line Jlexuose,

N. tumida (BrcSb.). — Large, tumid,
striated, twisted, oblong, with obtuse
apices, a Hexuose median line, and close,
fine stria3, which reach the median line.
ICA. p. 77. = iV. Jennerii, SD. i. p. 49,
pi. 16. f. 134. Marme. France, Britain,
(vn. 55.) Front view broad linear ob-
long, with rounded angles; frustules
twisted, so that the hyaline central por-
tion appears flexuose.

N. convexa (S.). — Lai'ge, tumid, stri-
ated, twisted, linear oblong, with conic
apices, a flexuose median line, and 21
stiiffi in -001", which do not quite reach
the median line. SD. i. p. 49, pi. 18.
f. 136. Marine. England. Front ^dew
broadly linear-oblong, with roimded
angles, and a narrow, flexuose, longi-
tudinal median band.

N. Westii (S.). — Broadly lanceolate,
with subacute apices, and 38 delicate
striae in -001", which nearly reach the
slightly flexuose median line. SD. i.
p. 49, pi. 16. f. 135. Marine. England.
Coloiu- of dry valve dark pui-ple; front
view lineal', with rounded angles, and a
narrow, slightly flexuose median band.

N. ? campylogramma (E.). — Small,
ovate, obtuse, smooth, with a flexuose,
sigmoid median line, and orbicular cen-
tr.al nodide. EB. 1853, p. 36. Bavaria,
Rhine. Probably identical with Achiian-
thidiiinijlcxcllum, since Ehreuberg states
that ho has seen it, together with Ach-
nanthes ? Bavarica, disti-ibuted imder the
name of Cymhellajiexella.

N. tortuosa (E.). — Smooth, crystalline,
rather turgid, and somewhat tortuous,
so that one end has a more obtuse apex.
EB. 1843, p. 271. 1-288".

N. dissimilis (S.). — Frustules oblique ;
elliptic ; median lino somewhat diagonal
from the obliquity of the fi-ustide, re-
curved at extremities; stria) obscure.
ANII. 1857, xix. p. 8, pi. 2. f. 0. Pyrenees.

L. Fruslidas lunately curved in the
front view.

N. gemijlexa (K.). — Parasitic, smooth,
narrow-lanceolate, obtuse; front view
linear, with truncate ends, lunately
cmwed. KB. p. 101, pi. 21. f. G. Maiiue.
Peru.

M. Frustules lunately curved in the
lateral view,

N. Neapolitana (Rab.). — Lunately
cmved, linear, with ti-imcate ends, and
transA^erse striae. = Fulcatella Neapoli-
tana, Rab D. p. 46, pi. 5. f. 3. Italy.

N. lunata (K.). — Smooth, small, lu-
nately cim^ed, naiTow-linear, A\lth
slightly roimded ends ; front ^lew
linear, tmncate. KB. p. 101, pi. 4.
f. 1. 4. = FalcateUa lunata, Rab D. p. 40.
Italy.

N. Romana (Rab.). — Smooth, attached
by a gelatinous base; lunately ciu'ved,
linear, with truncate ends ; front view
linear lanceolate, trimcate. = FalcateUa
Romana, Rab D. p. 46, pi. 5. f. 1. Italy.

DouUful or insufficieyiily described
Species.

N. variatis (Greg.). — ^Fomi and size
variable; strife oblique, 14 to 18 in
•001", nearly reaching the median line,
more conspicuous opposite the central
nodule, and highly radiant. TM. iii.
p. 12, pi. 2. Britain. In this species
Professor Gregory disregarded fonn and
size, considering the number find dispo-
sition of the strife as the essential cha-
racters.

N. mittabilis (Greg.). — ^Form and size
variable ; strife as in N. rarians, but
finer, and from 24 to 26 in -001". TM.
iii. p. 14:.= Pinnularia cxiyua, MJ. ii.
pi. 4. f. 14. Britain. We concur in
opinion with the late Professor Smith,
that these species are too vaguely de-
flned, and that probably they are con-
stituted of forms belonging to various
other species.

N. minutissima (Rab.). — Exceedingly
minute, but with distinct median nodule.
Rab D. p. 39, pi. 6. f SO. Persia,

N. megalodon = Pinnularia mcgalodon,
EM. pl.'33. 14. f. 2J. America, The
centi'fil portion of a largo, oblong species,
with stout, distant, parallel cost^e, which
do not reacli the median line.

N. omphulia (E.). — LarM, iridescent,
with very fine, granulated, decussating'
lines; umbilicus orbicular, solid, hyalint^
divided by the straiglit median line.
Fossil. Fragments in Bermuda deposit.

OF THE NAVICULEJE.

911

N. Rhaphonek = Pinnularia Rhaplio-
ncis, EM. pi. 35 a. 9. f. 7. Ganges.
jMiuuto, oblong, with subacute apices, a
small central nodule, and diverging strias.

N. eunjsoma (E.). — Minute, smooth,
elliptic, with roimded ends, and mai'ked
by two narrow, longitudinal blank lines,
which converge at each end and are
coimected at the centre by the ti-ansverse
nodide. EB. 1838. = Stauroncis eury-
soma, EM. pi. 21. f. 36. Fossil. Algiers.
Apparently more allied to the lyi'ate
gi-oup of Navicula than to Stam-oneis.

Species from JEhrenherg, known to us
only by name.

N. ceratostigma, N. Jordani, N, Legu-

mm, N. amphilepta, N. ohliqua, N. tnrgida,
N. Sencycilensis, N. FalMandice, N. Cntha-
rincB, N. conspemi, N. Saiicmnce, N. aula-
coplmna, N. Barbudemis, N. JEurycdc,
N. leptoceros, N. spftceroptera, If. Vibrio,
iV. leptotermia.

Pinmdaria affinis, Ehrenberg gives 30
habitats. It may be a form of Navicula
affinis, with more evident sti'ia3.

P. ambigua, P. australis, P. insularis,
P. pletironectes, P. Preissii, P. Fusus, P.
Phenana, P. Craticula, P. j)teroplicena,
P. plaUjsoma, P. Catharinm, P. anomala,
P. Hemprichii, P. Licuarcc, P. Capensis,
P. Caffra, P. antarctica, P. Folium, P.
microsplienia, P. jjleuronectes, P. Arau-
canice, P. Barbadensis.

Genus STAURONEIS (Etr., Kiitz.).— Frustules simple, free in front view
parallelogramic ; valves with median line and nodules, central nodule trans-
versely dilated. Stauroneis differs from ISTavicula in having the central
nodule prolonged into a transverse pellucid band (stam-os) free from strite.
"In a few cases. we meet with the semblance of a staiu'os in the genus
Prnnularia [Navicula] ; but in these instances a closer examination wUl show
that this appearance arises from the interruption of the costaj merely, and
not from the dilatation of the central nodule, which is still found unchanged "
(Smith). Ehrenberg divides this genus into Stauroneis and Staiu-optera— the
former having smooth, and the latter striated frustules; but we agree with
Professor Kiitzing in thinldng the distinction, as in Navicula and Pinnularia,
unsatisfactory, and that many species would be referred by the observer to
the one or other genus according to the magnifying power of the microscope

used in the examination.

* Valves constricted at the centre.

Statjboneis constricta (E.). — Small,
oblong, deeply constricted at the centre,
and slightly contracted into obtuse
apices. EA. p. 134, pi. 1. 2. f. 12 6.
Chili, Austi-alia, Afiica.

S. Rabenhorstii. — Linear, with broadly
rounded ends and concave sides; costae
stout, oblique ; stam-os linear. = Stauro-
ptera constricta, liab D. p. 50, pi. 9, f. 10.
Italy.

2* Valves tcith 2 or 3 undukdions.

S. inflata (K.). — Small, linear, with
two cdnatrictions, and three dilatations ;
ends broadly roimded; stauros linear,
reaching the margin. KB. p. 105, pi. 30,
f. 22. Trinidad. 1-480" to 1-428".

_S. i^«fo/ie?i(J5reb.). — Lanceolate, acute,
with two undulations; stauros very
slightly dilated towards the margin;
stri.'t) distinct, 22 in -001"; front view
rectangular. -008" to -OlS". TM. vii.
P. 180, pb 9. f. G. Fresh water. INlel-
Dounic. Tliis beautiful species resembles
S. acuta, but is easily distinguished by
its marginal undulations.

S. Legumen CE.). — SmaU, oblong-
lanceolate, each margin with three uu-
didations; apices apicidated; stauros
Imear, reachmg the margin. EB 1844
p. 135; EM. pi. 39. 3. f. 104; 'Greg!
MJ. IV. pi. 1. f. 9. = Stauroncns linearis,
SD. 1. p. 60, pi. 19. £ 193. America
Em-ope. (vn. 67.)

3* Valves with, a sigmoid median line.

_ S. Sigma (E.). — Stout, lanceolate,
sigmoid, with obtuse apices; stam-os
abbreviated. EB. 1844, p. 88; EM
pl. l8. f 63. Fossil. Richmond deposit!
it has the form and size of Pkurosiqma
acuminatum; but its median noduie is
dilated, as if geminate. 1-240". Ehr

S. oblimm (Greg.). — Small, short, ob-
long, or broadly lanceolate, with a sigmoid
or oblique median line ; stauros reachin.r
the margin ; strioo fine, 45 in -001" M f
IV. p. 10, pi. If. .35. Lochleveu. (vn.63.j

4* Valves with rostrate or capitate
apices.

S dijatata (E.).-Smnll, vontricoso.
with mmute, mammiform beaks j stauros

912

SYSTEMATIC HISTOUT OP TICE INFTJSOEIA.

lineal", nearly reaching the margin. EA.
pi. 1. 2. f. 12 a; SD. i. p. GO, pi. 19.
f. 191. America, Australia, (xn. 16.)

S. exilis (K.). — Very minute, ventri-
cose, shortly rostrate; stauros linear.
KB. p. 105, pi. 30. f. 21. Trinidad.
1-2400".

S. punctata (K.). — Small, ventricose,
■with rostrate apices, and 27 radiant
punctate sti-ite in -001" ; stauros linear,
abbreviated. KB. p. 106, pi. 21. f. 9 ;
SD. i. p. 61, pi. 19. f. 189. Britain.
Fossil, Santa Fiore.

S. anceps (E.). — Small, lanceolate,
constricted beneath the subcapitate
apices ; stauros linear, not reaching the
margin ; stiite very delicate, 45 in -001".
EA. p. 134, pi. 2. 1. f. 18 ; SD. i. p. 60,
pi. 19. f. 190. Eiu'ope, Asia, Afiica,
America.

S. Cmcicula (S.). — Small, elliptic-
lanceolate, somewhat venti-icose, pro-
duced at the ends into minute, conical
beaks; stam-os very naiTOw, linear,
reaching the margin. SD. i. p. 60, pi. 19.
f. 192. Marine. Ii-eland. (vn. 64.)

S. ventricosa (K.). — Very minute,
veutiicose, constiicted beneath the capi-
tate apices ; stam'os linear, not reachmg
the margin. KB. p. 105, pi. 30. f. 27.
Gemiany, France, Britain.

S. capitata (E.). — Very small, oblong,
twice as long as broad, suddenly con-
stiicted beneath the capitate apices;
striiB 18 in 1-1560". EB. 1844. Southern
Ocean. Front view linear. 1-1152".

S. phyllodes (E.). — Tiu'gid-lanceolate,
with the apices produced into short,
subacute beaks ; stauros linear, reaching
the margin. EA. p. 135, pi. 1. 2. f. 10.
America, China, (xn. 7-9.)

S. Semmi, EM. pis. 35 a, and 38 a.
many figui-es. Ehrenberg gives about
80 habitats in Asia, Afiica, and Ame-
rica. Lateral view small, ventricose,
with mammiform apices and linear
stauros.

S. Tuscula (E.). — Small, striated,
elliptic-oblong; apices suddenly con-
tracted, unibonate ; stauros linear, reach-
ing the margin ; striae oblique. =iVrtri'cf//ff
Tuscula, EB. 1840, p. 21; KA. p. 77 ;
Stauroptcra Tuscida, EM. pi. 6. 1. f. 13.
Fossil. Santa Fiore, Siberia. Front
view linear.

S. mesoimchya, EM. pi. 15 a. f. 26.
Lough Mourne deposit. Ijarge, oblong-
lanceolate, suddenly contracted into maiu-
mifonn, obtuse apices ; stauros linear.

S. birosf.n's (E.). — Smsdl, narrow-
lanceolate, witli produced, rostrate, sub-
acute apices; stauros linear. EA. p. 134,

pi. 2. 2. f. 1. America, Africa.

S. Platalea (E.). — Lateral view slender
lanceolate, constricted beneath the capi-
tate apices; stauros linear. EM. pi. 15 a.
f. 30. Lough Mom-ne deposit ; Mexico.

S. Sieboldii (E.). — Large, turgid-
lanceolate, tapenng into obtuse beaks;
stam-os lineal-. EM. pi. 34. 8. f. 12.
Japan.

S. Ehrenhergii (E.). — Small, inflated,
oval, with produced, manimifonn apices ;
staui'os linear; stiise parallel. = 8tau-
roptera platystoma, EM. pi. 14. f. 13.
Berlin.

S. platystoma (E., K.). — Linear-ob-
long, contracted at the ends into mammi-
form beaks ; staiu'os linear. KB. p. 105,
pi. 3. f. 58; EM. pi. 3. 1. f. 8.=Nanciila
p)latystoma, E Inf. pi. 13. £ 8. Germany,
America, Asia. (rx. 142.) 1-1100" to
1-240".

S. ampMcepliala (K.). — Linear-oblong,
with produced, rosti-ate, capitate apices ;
stam-os lineal-. KB.*p. 105, pi. 30. f. 25.
Germany, France.

S. linearis (E.). — Minute, linear-ob-
long, with parallel mai-giaal lines, at-
tenuated at the apices into somewhat
obtuse beaks ; stam-os linear. EA. p. 135,
pi. 1. 2. f. 11. America, Em-ope. Lough
Mourne deposit.

S. macrocepliala (K.). — Linear, slen-
der, consti-icted beneath the capitate
apices ; transverse strias very dense.
KA. p. 92. = StauroiHera macrocepliala,
Rab D. p. 49. France. 1-425".

S. platijcephala = Staurojitera plafi/ce-
phala, EM. pi. 17. 2. f. 9. FossU. Fin-
land. Linear, suddenly constiicted be-
neath the dilated, broadly roimded ends ;
stam-os linear, reaching the margin;
striae parallel.

S. excellens (Perty). — Striated, broadly
lineal-, suddenly contracted into broadly
rounded, manmiifoi-m beaks. Pertv, Inf.
p. 205, t. 17. f. 11. Alps. Foiiu and
size of S. j)la(ystoma, but sti-iated. Its
nearest ally is S. tnicrostaiiroi), E. ; but it
is lai-ger and somewhat broader, with
less broadly rounded ends.

S. microstauron (E., K.). — Striated,
linear, suddenly constricted beneath the
broadly rounded, subcapitate apices;
stauros linear. J03. p. 106, nl. 29. f. 13.
= Stauroptcra microstauron, EA. pi. 1. 4
f. 1. Asia, Afiica, America,

S. monoyramma (E.).— Oblong, turgid
at the middle, and contracted at each
end into a broad, rounded, conical beak.
EA. p. 135 ; KB. p. 105, pi. 29. f. 18.
Surinam. Kesembles Achnanthes ven-
tricosa.

OF THE KAVICULEJE.

913

S. granulata (E.). — BaciUar, with
tiu-gid middle and obtuse ends; trans-
verse strife granulated. = Stauroptera
granulata, EB. 1847, p. 484. Canton.
1-480". Allied to Fragilaria ? mesotyla,
and to Achnanthes ventricosa.

6* Valves neither constricted, rostrate,
nor furnished with a sigmoid median
line.

t Valves lanceolate.

S. Phomicentm-on (Nitzsch., E.). —
Large, broadly lanceolate or somewhat
rhomboid, gi-aduaUy attenuated into
rather obtuse apices; stauros slightly
dilated outwards, reaching the margin ;
stiife fine. EA. pi. 2. 5. f. 1; SD. i.
p. 59, pi. 19. f. 185. =Bacilluria Phceni-
centeron, Nitzsch ; Cymbella Phoenicen-
teron, AD. p. 10; Navicida Phccnicen-
teron, E Inf. Common. Europe, Asia,
Afiica, America, (ix. 139 ; xn. 17, 18.)
1-400" to 1-140".

ptei-oidea (E.). — Large, broadly or
sharply lanceolate, with obtuse apices,
and very fine, pimctated, transverse
striaB ; stauros linear, reaching the mar-
gm. EA. p. 135 ; EM. pL 3. 3. f. 7.
America. Akin to S. Baileyi; larger
than S. Phoenicenteron, E.

S. Baileyi (E.). — Large, broadly lan-
ceolate, tapering gTadually to the obtuse
apices ; surface with very fine longi-
tudinal, undulated lines ; staiu-os lineai",

reaching the margin. EA. p. 134 ; EM.

several figures. America. Altin to S.

Phoenicenteron and S. pteroidea, E.
S. ampliilepta (E.). — Lanceolate, little

acuminated, with obtuse apices ; stauros

linear; stafise none, or indistinct. EA.

pi. 1. 2. f. 9-13. America, Africa,

Siberia. It is scarcely distinct fi'om S.

Phoenicenteron.
S. gracilis (E.). — Slender-lanceolate,

gradually attenuated into obtuse apices ;

stam-os linear, scarcely reaching the
I margin; strieB indistinct, very delicate.

EA. pi. 1. 2. f. 14 ; SD. i. p. 59, pi. 19.

f. 186. America, Europe, Asia, Africa.

I Smaller and more slendler than the pre-
ceding species.
S. apiculata (Grev.). — Oval, obtusely
ftpiculate ; stauros linear, abbreviated ;
rtriffi fine, 34 in •001". Edin. New Phil.
Joum., U.S., X. pi. 4. f. 8. Californian
gttano. Infiated, suddenly contracted at
the ends into conic beaks; stauros not
reaching more than hnlf way from the

i median line to the margin.
S. lanceolata (K.). — Slender-lanceo-
J»te, tapering into the narrow, subrostrate
ii

ends ; stauros linear, reaching the mar-
gin ; stria} obsolete or indistinct. KB.
p. 104, pi. 30. f. 24. Falaise. 1-180"
to 1-160".

S. Atlantica (E.).— Small, lanceolate,
with obtuse apices ; fi-ont view linear.
EB. 1845, p. 155. In pumice from the
Isle of Ascension. Akin to S. amiMle]}ta,
but more obtuse. 1-1152".

S. salina (Sm.). — Small, slightly con-
tracted at the obtuse apices; stauros
linear, nearly reaching the margin ; strifB
faint, 45 in -001". SD. i. p. 60, pi. 19.
f. 188. Marine. Britain.

S. minuta (K.). — Smooth, lanceolate,
rather obtuse, three times as long as
broad. KA. p. 89. Thuringia. 1-1200".

S. dtd>ia (Greg.). — Minute, smooth,
narrow-lanceolate, with somewhat tnm-
cate apices ; stam'os linear, nearly reach-
ing the margin. MJ. iv. p. 11, pi. 1.
f. 37. Scotland. When examined under
a high power, the valve exhibits two
parallel lines within the mai'gin on each
side.

S. staurophcena (E.). — Lanceolate,
smooth, slightly conti-acted at the sub-
acute apices ; stam-os linear, not reaching
the margin. E A. p. 135 ; EM. pi. 2. 3. f. 1 1.
North America. Distinguished from S.
Phcenicenteron by its abbreviated stauros.

S. GregoHi (Ralfs). — Rhomboid-lan-
ceolate, with acute apices ; stam-os linear,
reaching the margin ; stria3 tine, nearly
parallel, 60 in ■001". = Staiironeis am-
phioxys, Greg. TM. iv. p. 48, pi. 5. f. 23.
Scotland. Highly convex, and even in
the best position showing the mai'gin as
a broad black line, Greg.

S. inanis (Perty). — Striated, lanceo-
late or eUiptic-lanceolate, witli ^•ery fine
transverse striae. Perty, Inf. p. 206, pi. 17.
f 7. Alps. In form nearly agreeing with
S. linearis, E., but striated.

S. lineolata (E.). — Broadly lanceolate,
with obtuse apices, and parallel, dotted,
longitudinal lines ; stauros linear. EA.
p. 135, pi. 2. 1. f. 19. Cayenne.

S.pumila (K.). — Minute, cUiptic-lau-
ceolate, with acute apices, and short,
marginal, punctated, transverse strife ;
stauros reaching tlie margin. KB. p. 106,
pi. 30. f. 43. Marine. Christianin,. Front
view linear, with rounded angles and
truncate ends. 1-1440" to 1-1080".

S. Achnanthes (E., K.). — I>nnceolate,
with obtuse apices ; stritB distinct, ob-
lique ; stauros linear, reaching the mar-
gin. K13. p. 106, t. 29. f. 22. = Stauroptera
Achnanthes, EA. p. 1.36, pi. 3. 3. f 7-
EM. pi. 17. 1. f. 10. Australia, Ame-
rica, Falaise.

3n

914

SYSTEMATIC HISTOEY OP UTE INFTTSOEIA,

S, truncata (Eab.)- — Minute, oblong-
lanceolate, \nth very obtuse apices ;
staiu'os linear; strias distinct, oblique,
14 or 15 in 1-1200". = Stauro2)tera trun-
cata, Rab D. p. 49, pi. 9. f. 12. Bosnia.

S. acrocephala (Rab.). — Broadly lan-
ceolate ; turgid at the middle, rapidly
tapering to the acute apices; stauros
dilated outwards, reaching the margin ;
sti'iie pimctate, parallel. Rab D. p. 48,
pi. 9. f. 19. Saxony.

S. acuta (S.). — Elongated slender-
lanceolate or rhomboid, tapering to the
subacute apices ; stauros conspicuously
dilated outwards, reaching the mai'gin ;
strife oblique, 30 in -001". SD. i. p. 59,
pi. 19. f. 187. Britain, (vu. 76.)

S. pulchella (S.). — Lanceolate, or
linear-lanceolate ; stauros conspiciiously
dilated outwards, reaching the margin ;
striae oblique, very distinct, pimctate,
30 in -001". SD. i. p. 61, pi. 19. f. 194.
Marine. Britain. (vn. 77.). Front
view broad, linear-oblong, with rounded
angles and constricted centi-e.

S. aspera (E., K.). — Turgid, lanceo-
late or linear-lanceolate, with subacute
apices ; strias oblique, pimctate-asperate ;
stauros abbreviated, dilated outwai'ds.
KB. p. 10Q. = Staur(vptera aspera, EA.
p. 134, pi. 1. 1. £ 12 ; BC. vii. pi. 1. f. 18.
America, Europe. Front view linear,
with truncate ends.

2t Valves oval or oblong.

S. Fenestra (E.). — Small, eUiptic-ob-
long, with parallel marginal lines, and
obtuse, cuneate apices. EA. pi. 2. 1.
f. 20. America, Japan.

S. Pecliii (Rab.). — Small, oval, with
rounded ends ; costse stout, 11 or 12 in
1-1200"; stam-os linear, reaching the
margin. = Stauroptera Peckii, Rab D.
p. 49, pi. 9. f. 13. Lusatia.

S. polygramma (E.). — Elliptic-oblong,
with rounded ends and longitudinal
dotted lines ; stauros abbreviated. EA.
p. 135, pi. 2. 6. f. 30. Cuba.

S. semicruciata (E.). — Very large, re-
sembling Navicula viridis, but having the
crucial umbilicus of Stam-oneis. = aS^am-
roptera semia-uctata. EB. 1843, p. 45.
Asia.

3t Valves linear.

S. dendrobates (E.). — NaiTow-linear,
with obtuse ends, and a densely and
obliquely striated border; front view
oblong-quadrate. = Stauroptera dcndro-
bates,!^. Under moss on trees. America.
1-490".

S. Roraim(F = Stauroptera Roi-aim<P,

EM. pi. 34. 5 A. f. 9. Linear, with cu-
neate ends, a transverse median line, and
parallel striifi.

S. oUonga (Bail.). — Linear, -with acute,
cimeate ends, and oblique punctato-as-
perate sti-ife ; staui-os abbreviated, dilated
outwards. = Stauroptera oblonga, BC.
p. 10, pi. 1. f. 17. America. The sizi;
and markings of Stauroptera aspera,
E., but having its valves oblong, vnth
parallel sides, and acute angular ends,
Bailey.

S. Isostauron (E., K.). — Elongated,
linear, with broadly rounded, slightly
attenuated ends ; stauros linear, reaching
the margin ; sti-iae parallel. KB. p. 106.
= Stauroptera Isostauron, EA. p. 1.35;
EM. pi. 16. 1. f. 7. Labrador, Sweden,
Finland, (xn. 73.)

S. Liostauron (E.). — Stylifonn, linear-
oblong, with scarcely attenuated, roimded i
apices ; staui'os linear. EA. p. 135 :
EM. pi. 5. 1. f. 16. Iceland.

Doubtful Species.

S. ? explicata (Perty). — Small, not t
striated, with rounded ends, and much i
inflated centre (cruciform) ; enlarge- -
ments acute. Perty Inf. p. 205, pi. 17.
f. 10. Alps. About the size of S. ten- -
trieosum, K., but still more inflated at
the middle, and the inflations pointed, i
not rounded, Perty. The figure has no
median line or other markings, and re-
sembles a Biblarimn rather than a Stau- ■
roneis.

S. niesogongyla (E.). — Lateral view ».
linear, with rounded ends and gibbous i
centre; ti'ansverse strise parallel, inter- ^
rupted by a ti-ansverse central band.
Probably a Navicula, since the figure
shows a small, definite central nodule.
EM. pi. 6. 1. f. 7. Guiana, Fossil, San
Fioro.

S. gi^ba (E., K.).— Form of KavietiJa
gibba, but furnished with an imperfect
transverse fascia. KB. p. 107, pi. 29. '
f. 24. = Stauroptera ? gibba, EA. p. 135,
pi. 1. 2. f. 3. America, Africa. The
figure represents a Navicula with the
strioe shorter opposite the dilated um-
bilical space. ji i'

S. paucicostata (Rab.).— Small, Imear, i^,
with inflated centre, and dilated, rounded
apices ; co.stai distant, 4 or 5 in 1-1200' ,
much inclined. = Stauroptera pauci-
costata, Rab D. p. 49, pi. 9. f. 15. Eu-
rope. The figure shows a rhomboirt
umbilical space resembling the dilated
nodule seen in many Navicular, but not
a true stfluros. . ,

S. mandnia (Bail.). — Oval, with

I

OF THE NATICULE^ai.

915

slightly produced, mammiform apices ;
smface pimctato-striate, with a large
smooth centi'al space. BMO. p. 40,
pi. 2. f. 32. Florida. Eesemhles -S".
punctata, K., hut is larger, and has the
ends not so much produced. The figiu'e
shows a dilated umbilical space rather
than a true stam-os.

S. scalaris (E., K.). — Small, linear-
oblong, with rounded ends ; costie stout,
parallel, 12 in 1-1200", not reaching the
median line. KB. p. 106. = Stauroptera
scalaris, EA. pi. 4. 2. f. 3, Labrador,
(xu. 10, 14, 30.) Scarcely belonging to
thisgenus, since Ehrenberg's figm-es show
a definite central nodide. It differs from
Navicula borealis by its coarser costte and
their interruption opposite the median
nodide.

S. amphioxys = Stauroptera amphioxys,
EM. pi. 6. 1. f. 14. FossU. Santa Fiore.
Ehrenberg's figure represents an elon-
gated, naiTOw-lanceolate Navicula, with
acute apices, and a minute centi'al nodide

which is not dilated into a stauros ; striae
radiant.

S. pere(irina = Stauroptera peregrina,
EM. pi. 6." 1. f. 15. FossU. Santa Fiore.
Ehrenberg's figiu-e represents a small,
lanceolate Navicida, with a minute
centi-al nodule, but no stauros ; striae
radiant.

S. ? ovalis (Greg.). — Small, smooth,
oval ; stauros broad, indistinct, reaching
the margin. MJ. iv. p. 11, pi. 1. f. 36.
Britain. Perhaps a Cocconeis.

Species from EJireoiberg known to us
only hy name,

S. piisilla, S. sphmrophoron, S. Indica,
S. Placentula, S. Eologramma, S. gibhosa,
S. JEthiopica, S. Amphisbcena, S. Capensis,
S. Galapagica, S. decurrem, S. brevh'ostris,
Stauroptera nobilis, Stauroptera lei^toce-
phala, Stauroptera Distauridium, Stau-
roptm-a Braziliensis, Stauroptera Tabel-
laria, S. asperula, Stauroptera Siamensis,
Stauroptera trinodis.

Genus STAUEOGRAMMA (Eab.). — Like Stauroneis, but with decussating
striae, and prominent knots at the intersections, Eab.

Stattrogbamma Persicum (Rab.),
Oblong-lanceolate, with truncate apices ;
staiu'os linear, reaching the

margm ,

median line dilated towards the ends.
Rab D. p. 50. = Stauroptera decussata,
Rab D. pi. 9. f. 14, Persia, (vin. 36.)

Genus PROEOSTAUEOS (E.). — Frustules simple, free ; with the cha-
racters of Stauroneis, except that its terminal puncta in the front view ai-e
approximate and not lateral. We doubt whether this genus can be separated
from Stauroneis ; for, if we imderstand Ehrenberg's definition, the apparent
position of the terminal puncta depends upon the greater convexity of the
? lateral valves, which therefore appear, in the front view, like a border on
each side of the connecting zone, and the puncta are within the angles. The
species are unknown to us. EB. 1843, p. 136.

Pbohostaubos splendens (E.). — River
Senegal.

P. ? subulatus ? (E.). — Senegal, Cape of
Good Hope. At first sight it reminds
one of Gomplionema gracile, E.

Genus PLEUEOSIPHONIA (E.). — The characters of this genus arc
unknown to us ; but, from Ehrenberg's figure of -P. affinis, we think it is
probably identical with Mastogloia.

Pleubosiphonia affinis (E.). — Ob-
long-lanceolate, with capitate ends, me-
dian line and nodules, and a marginal
liand of transverse striae. EB. 1856,
p. 32. = Fragilaria Navicida, E. 1841 ;
I';M. 33. 1. f. 14. Arabia, Africa, Pei-u.

Species known only by name.
P. Amphisbcena (E.), Arabia, Africa,
Peru, Mexico ; P. fidva (E.), Arabia,
Africa ; P. Phcenicc'ntcron (E.), Arabia.,
Africa; P. Lihyca (E.^, Africa ; P. obtusa
(E.), Africa ; P. gracilis (E.) Africa.

Genus PLEUEOSIGMA (Smith) (Gyrosigma, Ilassall, RabenJiorst, &c.).
— Frustules simple, free, elongated ; front view linear or lanceolate, narrower
'han the lateral view ; valves depressed or slightly convex, sigmoid (rarely

3 N 2

916

SYSTEMATIC HISTOHT OF THE INFX7S0EIA,

straight), with a sigmoid median line, central and terminal nodules, and fine
decussating strice, which are resolvable into dots. Pleurosigma is distinguished
fi'om Donkinia and Amphiprora by the elongated-narrow front vieAV and
more depressed valves. The median line, also, is sigmoid, whUst in those
genera it is usually straight, or appears sigmoid merely from the t-wisting of
the frastule. This genus was first separated by Dr. HassaU from Navicula,
under the name of Gyrosigma. HassaU, however, like Ehrenberg, erroneously
considered it identical with the SigmateUa of Kiitzing, whereas they belong
to very distinct families ; and even their sigmoid forms belong to different
smfaces, SigmateUa having it in the front, and this genus in the lateral view.
Gyrosigma has been adopted by Eabenhorst and others ; nor do we think the
name so objectionable as to render its rejection necessary. If, then, we admit
Professor Smith's name, we do so for the reasons given by Brebisson : —
*' Gyrosigma (Hass.). — Peutetre ce dernier nom de genre n'etait-U pas bien
convenable selon les lois de la nomenclature ; dans tons les cas, il est certain
que, malgre son droit de priorite, U est a peu pres generalement abandonne.
D'ailleurs, on est d'autant moins dispose a reprocher ce changement de nom
a M. W. Smith, que le soin tout monographique qu'U a apporte a I'etude des
nombreuses especes de Pleurosigma qu'il a decouvertes, en fait \m genre tout
a lui " (Breb DC. p. 17). Ehrenberg does not admit Pleurosigma, because it
" does not differ in its physiological characters from Navicula " (EB, 1854,
p. 236).

* Frustules rostrate. 2 f Beaks short, stout.

t Beaks filiform.

PLEtraosiGMA ^asCTo/a (E., S.). — Tur-
gid-lanceolate, with long linear beaks
abruptly cm-ved ia contrary directions ;
striffi 64 in -OOl", indistiQct. SD. i. p. 67,
pi. 21. f. 211. = Ceratoneis Fasciola, E.
Mai'ine. Europe, (xii. 60, 61.) Coloui- of
dry valve pale-pink. 1-430". Mr. SoUitt
states this Diatom near Hull is veiy
smaU, the markings 90 in -001", while
those from Boston in Lincolnshire are
large, with only 50 striae in -001".

P. macnmi (S.). — Elongated slender-
lanceolate, with very long filifonn beaks
curved in contrary directions ; transverse
striae 85 in -OOl", very indistinct. SD.
i. p. 67, pi. 31. f 276. Brackish water.
England.

P. prolongatum (S.). — Narrow-lance-
olate, gradually tapering into slender
beaks curved in conti-aiy directions ;
transverse striae 65 in -OOl", indistinct.
SD. i. p. 67, pi. 21. f. 212. Marine.
England.

P. ar citatum (Donkin). — Turgid-lan-
ceolate, straight, with long, very slender,
strongly arcuate beaks exuded in con-
trary directions ; striae obscm'e median
line straight, central. TM. vi. p. 25,
pi. 3. I 10. Marine. England. Closely
allied to P. macrum, but distinguished
from it by the long, strongly arcuate
beaks. Dry valves very pale-brown.
(Donlrin.)

P. distortiim (S.). — Stout, turgid-lan-
ceolate, produced into short, broad, ob-
tuse, subrostrate extremities, which are
abruptly bent in contrary directions;
transverse striae obscure, 75 in -001";
median line central. SD. i. p. 67, pL 20.
£210. Marine. England. Small; colour
pale pink. 1-320".

P. JSstuarii (Brih., S.). — Broadly
lanceolate, rapidly tapering into sub-
rostrate, obtuse ends; median line di-
agonal, subniarginal near the ends ; striffi
oblique, 54 in -001" ; coloui- pale purjik'.
SD. i. p. 65, pi. 31. f. 275. = Aan-
citla jEstuarii, KA. p. 890; Gi/rosigma
^stuarii, Br^b. Marine. Europe.
Bather small; 1-290". Habit of P.
Tlmringicum, but smaller, paler, and
vrithou't the marginal notch, Kiitz.

P. littoralc (S.Y — Turgid-lanceolate,
rapidly attenuated into the cur^-ed, sub-
rostrate, somewhat acute ends ;_ loi^?!*');
dinal striae conspicuous, 24 in -001 ,
ti-ansverse 50 in -001": colour pur-
plish. SD. i. p. 67, pi. 22 f. 214.
karine. Europe. 1-200" ; median hue
subcentral.

2 * Valves gtbhous at the middle.
P. Sinensis (E.). — Large, elongated,
broadly linear, flexuose, sigmoid, vnt n
gibbous ceutrc and broadly rounded,
somewhat incrassated ends, ^''L^'''.
curved in contrarv directions. = i\

•

I
I

OF THE NATICTJLEiE.

917

Sinensis, EB. 1847, p. 484 ; EM. pi. 34. 7.
f. 11. China. 1-80".

P. reversum (Greg.). — Elongated
naiTow-linear, with inflated or lanceolate
centare, and dilated ends which are tui-ned
in contrary directions ; median line sig-
moid, subcentral except near the ends ;
strife extremely fine. GDC. p. 58, pi. 6.
f. 105. Marine. Scotland. This form
may be identical with P. Sinensis; but
the valves are nan-ower and with less-
roimded apices than in Elu'enberg's
figm'e of that species.

3 * Valves linear.

P. BaUicum (E., S.). — Lai'ge, broadly
linear, sti-aight, except towards the
attenuated obtuse ends, which are curved
in contrary directions ; longitudinal and
transverse striae, 38 in •001" ; colour
dark brown. SD. i. p. 66, pi. 22, f. 207.
= Navicula Baltica, E Inf. pi. 13. f. 10 ;
Gyrosigma Balticiim, Rab D. p. 47, pi. 5.
f. 6; P. inakron, Johnston, MJ. viii.
Marine or brackish waters. Common,
(yin. 33; ix. 144.) 1-70". Median
line flexuose, subcentral.

P. obscurum (S.). — Small, linear, with
attenuated, rather obtuse ends ; median
line very flexuose, not central ; strife ob-
Kque, 75 in -001". SD. i. p. 65, pi. 20.
f. 206. Marine or brackish waters. Britain.
Var. (3 smaller. 1-193" ; colom- pale pink ;
median line marginal near the ends.

P. simum (E.). — Small, linear, with
the ends obliquely roimded on opposite
sides ; median line sigmoid, nearly cen-
tral. = Navicula sima, EB. 1845, p. 363 ;
EM. pi. 34. 7. f. 9. India. 1-430".

P. Scalpellum (K.). — Small, linear,
slightly sigmoid, gradually attenuated
into the obtuse apices ; median line sub-
central. = Navicula Scalpellum, KA. p. 85 ;
KB. pi. 30. f. 13 ; Gyrosigma Scalpellum,
Rab D. p. 47, pi. 5. f. 10. Trinidad,
Persia.

P. Sciotoensis (SuUivant). — Linear,
moderately sigmoid, graduaUy attenu-
ated into the rather obtuse ends ; strire
transverse and longitudinal, 40 in -001".
SiUiman's J. xxvii. p. 251. Fresh water.
United States. -001". " Not anlike P.
Spencerii, for which it has passed as a
variety ; but it is a larger species, with
sides more parallel and ends less acute.
Its striation at once distincfuishes it "
(Sull.). "

4 * Valves lanceolate or linear-lanceolate,
t Valves linear-lanceolate.
P. Wansbeckii (Donkin). — Linear-lan-

ceolate, vsdth tapeiin^, subacute, slightly
sigmoid ends ; median lines sigmoid,
not centi-al ; longitudinal and transverse
stria3, about 50 in -001". Donkm, TM.
vi. p. 24, pi. 3. f. 7. =P. Balticum, (3, SD.
Marine. England. Pale straw-coloured.
•0045" to -005". Much smaller than P.
Balticum, and with more numerous sti-ife.

P. lamprocampum (E.). — Slender,
narrowly linear-lanceolate, tapering to
the rather obtuse apices ; sigmoid, with
flne transverse striae ; median line cen-
tral; front view \v[ie,ax.= Navicula lam-
procampa, EB. 1840, p. 20 ; KB. p. 102,
pi. 4. f. 6 ; Gyrosigma lamprocampum^
Rab D. p. 47, pi. 5. f. 9. Marine. Europe,
1-144".

P. curvulum (E.). — Linear-lanceolate,
with rather obtuse apices, sigmoid. =
Navicula curvula, E Inf. pi. 13. f. 14 ;
Gyrosigma curvulum, Rab D. p. 47, pi. 5.
f. 8. Eui'ope, America.

P. speciosum (S.). — Linear-lanceolate,
flexed chiefly at the somewhat abmpt,
obtuse ends ; median line submai-ginal
near the ends ; strise oblique, 44 in •OOl" ;
SD. i. p. 63, pi. 20. f. 197. England.
Pale straw-coloiu'. 1-85". It is shorter,
less tapering, and has more rounded
apices than P. for^nosiim; the median
line also is not diagonal at the centre.

T. formosu7n (S.). — Large, elongated,
linear-lanceolate, much flexed, gradually
tapering to the obtuse apices ; median
line diagonal ; striae oblique, 36 in •OOl".
SD. i. p. 63, pi. 20. 1 195. Marine. Eng-
land, (vni. 32.) Colour chestnut-brown.
1-66". WeU distinguished by the po-
sition of its median line, which, owing
to a twist in the valves, appears to coin-
cide with the edges for a considerable
distance at either end, and then crosses
in a diagonal direction.

P. Longinum (Bri.). — Lanceolate,
flexiu-e moderate, extremities greatly
elongated, acute ; median line central ;
strise ti-ansverse, 86 in •OOl". -020" to
•025". Colour pale straw. TM. vii.
p. 180, pi. 9. f. 7. Arctic regions.
_ P sinuosum (E.). — Small, sti-iated,
linear-lanceolate; striae 15 in 1-1200"
1-480". = Navicula sinuosa, EB. 1840,
p. 21. Marine. Europe. Has the figiuHj
of P. simum, but is more slender,

P. subtile (Br(5b.).— Very slender, pel-
lucid and delicate ; slightly sigmoid, very
narrow linear-lanceolate, subuliformwith
rather obtuse apices. = Navicula subttlis,
KA. p. 87. Marine. France. 1-160"
to 1-120".

P. tetmtssimum (S.). — Very narrow
linear-lanceolate, gradually tapering to a

918

SYSTEMATIC HISTORY

OF THE INFU80ETA.

fiue point ; transverse strife 48 in -001" ;
median line central. SD. i. p. 67, pi. 22.
f. 213. Brackish water. Essex.

P. Apulum (Rab.). — Slender-lanceo-
late, much cui-ved, with obtuse ends,
ti-ansversely striated ; front view broadly
linear. Rab D. p. 47, pi. 5. f. 7. Italy.
In the figiu'es the valves are linear, very
but not symmeti-ically sigmoid, with
tapering ends and central median line.

2 1 Valves lanceolate, with oblique striae.

P. delicutulum (S.). — Slender-lance-
olate, gi-adually tapering to the acute
apices ; flexure moderate ; median line
central ; striae oblique, 64 in -001". SD.
i. p. 64, pi. 21. f. 202. Brackish water.
Britain. Length 1-112"; breadth
1-1500". Colour pale pink.

P. inflatmn (Shadbolt). — Small,
broadly-lanceolate, with acute apices ;
median line central, much flexed, as well
as the valve ; striae oblique. TM. ii.
p. 16, pi. 1. f. 9. Marine. Natal.

P. decorimi (S.). — Large, elongated,
rhomboid-lanceolate, imiformlj^ flexed,
gTadually tapering to the subacute apices ;
striae oblique, 36 in -001" ; median line
diagonal, marginal near the ends. SD. i.
p. 63, pi. 21. f. 196. Brackish water.
England. Colour pale chestnut.

P. angulatum (Quekett, S.). — Large,
broad, sigmoid, rhomboid-lanceolate,
rapidly tapering to the subacute apices ;
median line somewhat diagonal ; striae
oblique, 52 in -001". SD. i. p. 65, pi. 21.
f. 205. = Navicilla angidata, Quekett,
Microsc. p. 438, pi. 8. f. 4 to 7. Marine.
Britain. Colour pale chestnut ; flexm'e
moderate,

P. quadratuin (S.). — Large, very
broad rhomboid, rapidly tapering to the
subacute apices, which are slightly flexed;
sti'iae oblique, 45 in -001" ; median line
central. SD. i. p. 65, pi. 20. f. 204. =P.
angidatum, ANII. 2na series, ix. p. 7.
Marine. Em'ope. Colour chestnut ;
length_l-110"_; breadth 1-428". Easily
recognized by its very broad angular form.

P. lunceolatum (Donlrin). — Straight,
broadly lanceolate, acute ; mediau line
straight or gently sigmoid, with the ter-
minal nodules tui-ned in contrary direc-
tions ; striae very fine, oblique, about 70
in •001". TM. vi. p. 22, pi. 3. f. 4.= P.
transversale, /3, Mr. Roper. Marine. Eng-
land. Straw-coloured; -0056" to '006" ;
front view narrow linear-lanceolate.
The extremely fine striae require the
most careful manipulation with very
oblique light, to render them visible with
a superior l-5(h objective.

P. naviculaceum (Br^b.). — Rather
small^ lanceolate, straight, gradually
tapenng to the obtuse apices, which are
slightly tmned in contrary directions ;
median line sigmoid, not central ; striaj
very fine, oblique. B. Diat. of Cherbourg,
1854, p. 17, f 7. = Gyrosigma transver-
sale, M:icrog. Diet. pi. 11, f. 37, 38 ; P.
transversale, SD. li. p. 96. Marine.
Common, especially in deep waters. Thia
species, viewed laterally, greatly resem-
bles a Navicula in its lanceolate straight
form. Its apices are only slightly in-
clined to opposite sides. The median
line, however, is sigmoid, and the striae
are oblique and decussating.

P. marinum (DonMn). — Broadly lan-
ceolate, straight, slightly sigmoid near
the obtuse ends ; median line sigmoid on
each side of the centi-al nodule ; striae
oblique. TM. vi. p. 22, pi. 8. i. 3. Marine.
Northumberland. Straw-coloiu-ed ; stiia
about 45 to 50 in -001". -0055" to -006".
The well-marked sigmoid flexure of the
median line on both sides of the centi'al
nodule distinguishes this species, and
renders it easy of recognition.

P. Nubecula (S.). — Small, lanceolate,
nearly straight, with obtuse apices, cen-
tral median line, and 55 oblique stiiae in
•001" ; colour veiy pale. SD. i. p. 6^
pi. 21. f. 201. Mai-iue. England.

P. intermedium (S.). — Elongated, pale
straw-colom", slender lanceolate, nearly
straight, tapering to the subacute apices ;
median line subcentral; striae oblique,
55 in •001". SD. i. p. 64, pi. 21. f. 200.
Marine. England.

v. rigidum (S.). — Lai'ge, stout, pale
straw-colour, lanceolate, nearly straight,
with rounded apices; median line cen-
tral; sti-ia3 oblique, 48 in -001". SD.
i. p. 64, pi. 20. i. 198. Marine. England.

P. validnm (Sh.^. — Large ; lanceolat^
nearly sti-aight, with very obtuse apices,
oblique striae, and slightly flexed median
line. MT. ii. p. 16, pi. 1. f. 8. Marine.
Natal.

P. elongatinn (S.). — Lai^e, much
elongated, lanceolate, gradually tapering
to the acute apices, nearly sti'aight, ex-
cept at the ends, whicli are slightly
curved; striae oblique, 48 in ^"^^"^
mediau line neailv straight. SD. i. P- "4,
pi. 20. f 199. Marine. 'England. Oleai
straw-colour. Length 1-75"; breadth
1-920".

P. striqosum (S.). — Larffe, elongated
broadly lanceolate, gi-adually attenuated
to the obtuse apices ; flexure slight ; me-
dian lino not central near the ends;
stria) oblique, 44 in 001 '. SD. i. p. 64,

OP THE NAVICTJIEJB.

919

pi. 21. f. 203. Marine. Britain. 1-90" ;
coloiu" pale straw ; front view narrow
linear-lanceolate, with obtuse apices.

3 t Valves lanceolate, with longitudinal
and transverse strife.

P. ohtusatiim (Sullivant). — Oblong-
lanceolate, slightly sigmoid, with obtuse
apices ; -0025" ; strife transverse and
longitudinal, 56 in -OOl". Silliman's J.
xxvii. p. 251. Fresh water. United
States. A very small species, remark-
able for the obtuse ends. It may be a
CoUetonema, but we have not observed
it in gelatinous envelopes.

P. Spmiceri (Quekett, S.). — Small,
lanceolate, moderately flexed, gradually
tapering to the obtuse apices; median
line central ; strise very fine, transverse
50 in -001", longitudinal 55 in -001".
SD. i. p. 68, pi. 22. f. 21B. = Navicula
Spenceri,Q,\xQkett. Freshwater. America,
Europe. Coloiu* pale brown. 1-270".

P. Parheri (HaiTison). — Lanceolate,
considerably flexed, apices produced,
median line centi'al ; strise ti-ansverse,
55 to 60 in -001"; longitudinal strife
faint ; colom* pale yellow. Lincoln-
shire. MJ. viii. p. 105.

P. Wormleyii (Sullivant^. — Lance-
olate, conspicuously sigmoid, suddenly
attenuated into acute apices; -003";
strife, longitudinal and transverse, 52 in
•001". Silliman's J. xxvii. p. 251. Fresh
water. United States. Resembles P.
Speticeri, but is a smaller species, more
evidently sigmoid, and with rather ab-
ruptly attenuated ends ; its striae are
more difficult to resolve, and the texture
of its valves is thinner.

P. lacustre (S.). — Lanceolate, consider-
ably flexed, gradually tapering into the
obtuse apices ; longitudinal and trans-
verse strife, 48 in -001"; median line
subcentral. SD. i. p. 68, pi. 21. f. 217.
Fresh water. England. 1-144".

P. Tlmringicum (K.). — Lanceolate, sig-
moid, gi'fiduaUy attenuated to the sub-
acute apices, obsoletely notched at the
middle of each margin; median line
central; sti-ife wanting or indistinct. =
Navicula Thuringica, KB. p. 102, pi. 4.
f, 27 ; Gyrosigma Tlmringicuni, Rfib D.
p. 47, pi 5.' f. 4. Thiiringia. Fi-ont
view narrow-linear ; 1-264" to 1-168".

P. Agellm (E.). — Large, lanceolate,
flexed, gradually tapering to the obtuse
apices, marked longitudinally with very
fine lines, and thus appearing furrowed ;
median line eentva]. = Navicula Aoelhis,
EB. 1840, p. 18; EM. pi. 15 a. 'f. 31 ;
Gyrosigma Agcllus, Rab D. p. 47. Fresh

water. Germany, Lough Moume deposit,
Siberia. Fi-ont view nearly linear, ^vith
subacute apices ; 180". Is more slender
and longer than P. Hippocampus, E.

P. attenuatum (K., S.). — Lai'ge, elon-
gated, flexed, lanceolate, gradually at-
tenuated into the obtuse apices ; lon-
gitudinal strife 30, and transverse 40 in
•001" ; median line central. SD. 1. p. 68,
pi. 22. f. 21Q. = Navicula attmuata, KB.
p. 102, pi. 4. f. 28 ; Gyrosigma attenuatum,
Rab D. p. 47. Fresh water. Europe.
1-120". Coloiu- purplish brown; front
view nfUTOw-lanceolate, with tiamcate
ends.

P. ctcspidatmn (Rab.). — Slender-lan-
ceolate, very much flexed, with long,
tapering, obtuse ends ; median line cen-
tral. = Gyrosigma cuspidatum, Rab D.
p. 47, pi. 5. f. 5, 6. Fresh water. Europe,
America. It is always mixed with P.
acuminatum.

P. acuminatum (K., S.). — Lanceolate,
tapering into the obtuse apices ; flexure
considerable ; median line central ; lon-
gitudinal strise 40 in -001", transverse
52 in 'qOl". SD. i. p. 66, pi. 21. f. 209.
= Navicida acuminata, T\B. p. 102, pi. 4.
f. 26 ; Navicula Sigma, EB. 1843, p. 209 ;
Gyrosigma Hassallii, Rab D. p. 47.
Marine. Eiu'ope, Asia, Africa., America,
(ix. 146.) Front view narrow-linear,
with obtuse apices ; 1-162" ; colour
pale brown.

P. Hippocampus (E., S.). — Large,
elongated, broadly lanceolate, obtuse ;
flexiu'e considerable; colom-pale brown;
strise as in P. attenuatum ; median line
central. SD. i. p. 68, pi. 22. f. 215. =
Navicula Hijjpocampus, E Inf. pi. 13. f. 9 ;
Gyrosigma Hippocampus, HBA. pi. 102.
f. 11 ; Rab D. p. 47. Marine. Europe.
(IX. 145.) 1-166" ; fi-oiit view lineaa-,
truncate.

P. Strigilis (S.). — Large, much elon-
gated, lanceolate, imiformly tapering to
the subacute apices, flexed ; median line
central; strias, transverse and longitu-
dinal, 36 to 40 in '001". SD. i. p. 66
pi. 22. f. 208. Brackish water. England.
Length 1-80"; breadth 1-830" ; colour
pale brown. _ Notable for its graceful
form and distinct striaj.

P. Scalprum (Gaillon). — Small, sig-
moid, gi-adually attenuated into the
rather obtuse apices, longitudinally
striated. = Cymbclla Scalprum, AD. p. 11 •
Navicula Scalprum, E. Inf. ; KB. pi. 4'
f. 25. Marine. Europe, Asia, America!
Length 1-430" to 1-290".

P. Normanii (n. sp.). — Broadly lan-
ceolate, slightly flexed, with rather ob-

920

SYSTEMATIC HISTOET OF THE INFUSOHIA.

Nomian, Esq.

P. acutum (Norman, MS.) — Large
broadly lanceolate, elongated, moderately
flexed, ^adually tapering to the very .
acute apices ; median line delicate, much i
flexed, not central ; striai oblique, 50 in i
•001" Marine. Stomaclis of Ascidians,
&c. Europe. Veiy pale straw-colour or r
nearly hyaline ; -Oil" ; median line :
flexed throuq-hout.

tuse ends, and a slight, transverse cen-
tral depression ; median line stout, nearly
centi-al ; sferise oblique, 40 in -001". =
P. laiiceolatiim, Norman, MS. Marine.
Eui'ope. Foimd in nearly every gather-
ing from deep water, and in stomachs
of Ascidians, Noctilucse, Pectens, &c.
Colour tawny brown ; ^0048" to -0110" ;
median line scarcely flexed, except near
the ends. The description is by George

Genus TOXOIS'IDEA (Donkin). — Fnistules simple, free ; lateral valves *
elongated convex, with, the sides not symmetrical ; median Une arcuate, with i
central and terminal nodules, its ends curved towards the same margin; :
striae oblique. Marine. Toxonidea is closely allied to Pleurosigma ; indeed I
the forms placed here are regarded by Professor Amott as distorted species •
of that genus. The absence, however, of a sigmoid flexure, both m. the valves ;
and median line, is so dilferent from what we find in Pleui-osigma, that we \
think it advisable to admit Toxonidea until Dr. Donkin's views are disproved
by more perfect observation.

Toxonidea Gregoriana (Donkin). —
Large, lanceolate, with the obtuse ends
cm-ved upwards ; median line conciuTcnt
with the lower margin near the ends ;
sti'isB fine, oblique, about 50 in '001".
TM. vi. p. 19, pi. 3. f. 1. Britain. Straw-
colom-ed; -008" to -009"; median line
ciu-ved upwards near the end, and " re-
sembling the figm'e of an imbent Scy-
thian bow ; doisum rather more con-
vex than the venter.

T. insignis (Donkin). — Ai'cuate or
semi-lunate, with produced, subacute
ends ; median line not central, strongly
arcuate ; striae very fine, about 75 or 80
in -001". TM. vi. p. 21, pi. 3. f. 2. •0048"

to 'OOG" ; " valves resembling a straw- •
coloured strung bow or a cocked hat,"
with vei-y convex or gibbous dorsum and i
straight venter. Professor Amott rC'
gards this species as a distorted state of i
Pleurosigma ^stuarii. Britain.

T.tindulata (Norman, 3IS.). — Ai-cuate,
with three slig-ht dorsal imdulations, ob-
tuse somewhat reciu-ved apices, and con-
cave venter gibbous at its centre ; striae
oblique, 50 in •OOl". From Ascidians.
North Sea. Very pale straw-colour, with
pinkish reflections ; "0055" ; longitudinal
sutm'e concurrent with the ventral mar-
gin except at the inflated centre, (vin.
46.)

1

Genus DONKINIA (n. g.). — Fnistules simple, £i-ee ; front view pandiui-
form, as broad as the lateral view ; valves convex, keeled, with nodules an
decussating stria3 as m Pleui'osigma. Marine. We have constituted this
genus for the reception of some Diatoms possessing characters intermediate
between Pleurosigma and Amphiprora, and have much pleasure in dedicating
it to Dr. Donkin, who, amongst his many interesting discoveries, first directed
attention to several of the species placed in it. Dr. Donkin rcfen-ed the ,
species to Pleurosigma on account of the similai-ity of striation ; but they n|
differ from that genus in the broad, constricted front view ; and fi-om the.«c
characters, together with their very convex, keeled valves, we were inducca
to regard them as more nearly allied to Amphiprora. Indeed there is ^
little essential difference between keel, crest, and wing, these being, in om"
opinion, merely different stages of development. This opinion was also
adopted by Professor Amott, whose critical knowledge of genera commands
the highest deference. The species placed in Donkinia difter from Amphi-
prora, not only in their decussating strioa (a character sometimes chflicult to
verify, and of rather doubtful generic value), but also, according to Dr.
Donkin, in the absence of lateral wings to the valves.

UoNKiNiA cristata (E.).— Narrow-Ian- central nodule transversely oblong;
ceolate, gradually subidate at each end ; dian line sigmoid, crested. = Anvint'

OF THE NAVICTJIE.^!.

921

cristata, EB. 1854, p. 240; EM. pi. 35
BB. 4. f. 13. Atlantic.

D. inversa (E.). — Short, narrow, sig-
moid, with subacute apices ; front view
very broad, quadrangular, constricted at
the middle, with broadly ti'uncate ends
and marginal g\&ndis. = Navicula inversa,
EB. 1840, p. 18. Europe. 1-576". "It
is allied to Ampliiprora alata, but wants
the winged portions" (E.).

D. carinata (Donldn). — Straight, linear-
lanceolate, acute, very convex; coloiu'
didl purple; median line strongly sig-
moid, mai'ginal near each end ; strise
oblique, fine, about 55 to 60 in "OOl". =
Pleurosigma carinatum,T>Qn^\n., I. c. p. 23,
pi. 3. f. 5. England. -0046"; valve
twisted ; median line diagonal at the cen-
tre, marginal near the ends. (vm. 49.)

D. compacta (Grev.). — Sti-aight, very
convex, linear, obtuse, sigmoid fi-om
having the ends sloped in contrary
directions ; median line much flexed,
diagonal at the centre, marginal near
the ends ; sta-ise very fine, 53 to 60
in ■001".=Pleti}'Qsiffma conipactum, MJ.
V. p. 12, pi. 3. f. 9 ; Pleurosigma rectum,
Donkin, TM. \\. p. 23, pi. 3. f. 6 ; Am-
phiprora Ralfsii, Amott, MJ. vi. p. 91.
Britain. -0045" to -005". Accordmg to
Dr. Doniin, the strije are longitudinal
and transverse ; colour very pale.

D. mhiuta (Donlrin), — Short, very

convex, lineai'-oblong, subacute, sigmoid
from the sloping of one margin near each
end in contraiy directions ; median line
much flexed ; strioe very fine, transverse
ones distinct, about 55 in -001", longi-
tudinal ones ohscm-e. =Pleurosig7na mi-
nutuni, Donkin, I. c. p. 24, pi. 3. f. 8.
England. -0025" ; colour, very pale
brown. D. minuta seems to differ from
D. compacta, to which Professor Arnott
woidd imite it, chiefly in its smaller size.

D. angusta (Donkin). — Very con-
vex, linear, with acute, slightly apicu-
lated apices ; median line strongly sig-
moid, marginal, except a central diagonal
portion; strise obscm-e, longitudinal. =
Pleurosigma angustmn, Donkin, I. c. p. 24,
pi. 3. f. 9. England. -005" to •0055" ;
colour dull purple. Another form closely
allied to D. compacta,

D. reticulata (Norman, MS.). — Linear-
lanceolate, with rather obtuse apices;
median line strongly diagonal at the
centre, then marginal and slightly pro-
jecting; striae oblique, distinct, 22 in
•001". Stomach of Ascidians, Shark's
Bay, Australia. Collected by Dr. Mac-
donald. Colom- purplish brown; fr-ont
view oblong, with truncate ends and con-
stricted middle. For the description of
this species we are indebted to George
Norman, Esq.

Genus AMPHIPEOEA (Ekr.) (Entomoneis, Ehr,). — Erustules free, simple,
in front view constricted at ttie middle ; valves convex, with a longitudinal
wing, and central and terminal nodules ; strife, when present, transverse.
Marine. Amphiprora is distinguished by its lateral wings, whicli are con-
stricted at the middle, so that the frustule in front view, when not twisted
(which, however, frequently occurs), is more or less panduriform, with tinm-
cate or broadly-rounded ends. The late Professor Smith stated that the
peculiar frustules of this genus could not be confounded wdth any others,
save those of a few species of Nitzschia. From the recent discoveries of
Dr. Donkin, Amphiprora is found far more closely allied to Pleiu-osigma
and Donldnia. Prom these genera it differs by its alate valves, and by
having transverse striae only. According, however, to the late Professor
Gregory and Dr. Donkin, the valves of Amphiprora are furnished, in addition
to the median crest, with lateral ones also, similar to those of Simrella ; and
certainly the frustules in the front view most frequently exhibit a longitu-
dinal line on each side between the margin and the central portion — an
appearance not unlikely to depend on such a foi-mation, particularly in A.
ornata and A. paludosa, in which those lines arc undulated. An end view
is required to ascertain whether this be really the case, since the same
appearance would result from a depression along the sides of the median
crest, and even tlie undulations may be produced by transverse ridges.

AMPHiPBonA alata(E.,K.). — Very hya-
line, generally twisted ; front view broad-
ly winged, strongly constricted; wingcon-

tinued roimd the ends ; lateral view with
apiculate ends and n double line of puncta
accompanying the keel; strine 42 in

922

SYSTEMATIC HISTOEY OP THE INFUSOMA.

•001". KB. p. 107 ; SD. i. p. 44, pi. 15.
f. 124. = Navtcula and Entomoneis alata,
EB. 1845, p. 154. Common, especially
in salt-water marshes, (xin. 5 to 7.)
1-570" to 1-430" ; centi-al portion with
longitudinal lines.

A. Kiitzingii (Br(5b.). — Very hyaline ;
front view slightly constricted, longi-
tudinally lined, vdth rounded apices.
KA. p. 93. Fi-ance.

A. comtricta (E.). — Very hyaline ;
front view oblong, sinuato-constricted,
with rounded ends; lateral view naiTow,
with sti-aight median line, and transverse
stauros-likeband. EA.p. 122, pi. 2. 6. £28;
SD.i.p.44,pl. 15. f. 126. Em-ope, America,
(xn. 1.) Strias very faint, 68 in -001".

A. duplex (Donkin). — Broad, pandm-i-
form, with truncate ends and roxmded
angles; lateral view narrow, not stri-
ated ; keel strongly sigmoid, imacconi-
panied by puncta. TM. vi. p. 165, pi. 3.
I. 13. England. Resembles A. alata in
the broad, deeply-constricted fi-ont view
with conspicuous alte, but differs from it
in the absence of strife and puncta, and
in the narrow-linear lateral view.

A.plicata (Greg.). — Front view deeply
constricted, with broadly roimded ends ;
each valve with a plate extending from
its inner margin to the nodule, furnished
like the wings with about 50 fine trans-
verse striae in -001" ; central portion
with faint vertical lines or folds. GDC.
p. 33, pi. 4. f. 57. Scotland. Approaches
nearest to A. alata, but differs from it in
the folds of the middle space, and. in the
presence of lateral plates. Judging from
the figm'e quoted, the longitudinal lines
are simUar to those present in A. alata
and other species, and we doubt the
distinction of the lateral plates.

A. pulclira (Bailey). — Large ; fi-ont
view deeply constricted, with rounded
ends, distinctly striated, pimctate near
the margin. BC. ii. p. 38, pi. 2. f. 16
& 18. Florida. Of ten twisted ; central
portion naiTOW, sigmoid, with a few fine
longitudinal lines.

A. qiiadrifasciata (Bailey). — Small;
front view moderately constiicted, with
truncate or slightly rounded ends ; valves
striated, lanceolate, with produced ros-
tellate apices. BC. ii. p. 38, pi. 2. f. 2-4.
United States. When living, the colour-
ing matter fomis foui- yello-\vish trans-
verse bands ; not contorted.

A. vitrcn (S.). — Straight; front view
oblong, with rounded ends and slight
constriction ; lateral view lanceolate ;
striiu 52 in -001". SD. i. p. 44, pi. 81.
f. 270. Britain. I

A. c%am (S.]|. — Straight; front view
linear-oblong, with broadly rounded ends
and very slight notch-like constriction ;
lateral view lanceolate ; strite 40 iu
•001". SD. ii. p. 90. ; GDC. p. 3.3, pi. 4.
f. 58. Britain. " Distinguished from .4.
vitrea by its longer and comparatively
more lanceolate and slender finistule,
and closer strise" (S.). Professor Amott
would unite this with A. vitrea.

A. obtum (Greg.). — Front view linear-
oblong, with slightly sinuated sides and
rounded ends : striae very line. GDC.
p. 34, pi. 4. f. 60. Scotland. Ala of
nearly uniform breadth.

A. minor (Greg.). — Front view oblong,
with slightly sinuated sides and rounded
ends ; striae rather coarse ; central smooth
portion lanceolate. TM. v. p. 75, pi. 1.
f. 38. Scotland.

A. pusilla (Greg.). — Front view qua-
drangular ; alas slightly constricted, the
constriction apparently overlapped by
the convexity of the valve ; lateral view
acutely lanceolate; striae fine, about 60
in -001". GDC. p. 33, pi. 4. f. 56. Scot-
land.

A. lepidoptera (Greg.). — Elongated ;
fi'ont view linear, with broadly rounded
ends ; the notch-like constiiction of the
alae apparently overlapped by the con-
vexity of the valve ; lateral view lan-
ceolate, apiculate ; striae fine, about 48
in -001"; GDC. p. 33, pi. 4. f. 59. Scot-
land. The alas ai-e caiiied round the
ends, and in the lateral view appear like
an apiculus.

A. maxima (Greg.). — Front view very
broad, pandurifonn, with rounded ends,
the notch-like constriction overlapped
by the convexity of the valve ; striffl
distinct, about 36 in -001" ; lateral view
acutely lanceolate. GDC. p. 35, pi. 4
f. 61. Scotland.

A. complexa (Greg.). — Fi-ont view
broadly panduriform, with broadly round-
ed ends; alae with marginal pimcta ; striae
delicate, about 45 in -001" ; centi-fil por-
tion oblong, vnt\\ concentric longitudinal
lines. GDC. p. 36, pi. 4. f. 62. Scot-
land.

A.paludosa rS.).— Twisted; front view
dilated, broadly win":ed, deeply con-
stricted, with rounded or tnincate ends,
and a waved longitudinal line on each
side between the mai-gin and central
portion ; sti-iae 60 in -001" SD. i. p. 44,
pi. 31. f. 269. Britain. Fresh or slightly
brackish water, according to Smith;
marine, according to Professor Arnott,

A. wwa/rt (Bailey).— Small; front Anew
deeply constricted, with truncated or

OF THE NATICULEJS.

923

rounded ends, and a longitudinal row of
undulations on each side. BC. ii. p. 38,
pi. 2. f. 15 & 23. America. Often
twisted. " The iiifSe-like rows of pin-
nules distinguish this species from all
others" (Bailey).

Douhtful Species.

A. recta (Greg.). — Front Yiew qua-
drangular, Avith rounded angles and very
slightly constricted sides ; striae fine hut
distinct. TM. v. p. 67, pi. 1. f. 40. Scot-

land. The figure presents no appearance
of alee, but only convex lateral valves,,
such as are seen in several species of
Navicula.

A. navicularis (E.). — Oblong, with
obtuse ends and radiant transverse striae ;
front view quadrangular, with two
piincta at each end. EA. p. 122 ; EM.
several figures. Fresh water. America.
Apparently a Navicula with the ter-
mmal pimcta of the front view less mar-
ginal than usual.

Genus DTADESMIS (Klitz.). — Frustiiles navicular, united into a filament ;
valves with central and terminal nodules. Habit of Fragilaria, but the valves
furnished with median line and central nodule. Diadesmis differs from
Sphenosira only in having the lateral surfaces with similar ends.

* FresMoate}- or Fossil.

DiADESJns confervacea (K.). — Breadth
of articulations twice the length ; valves
minute, smooth, with acute, acuminate
ends. KB. p. 109, pi. 30. f. 8. Trinidad.
(XIV. 32, 33.) 1-960".

B. l(Bvis (E., K.). — Smooth; breadth
of articulations three to four times the
length. KB. p. 109, pi. 29. f. 69. = Tabel-
laria Icevis, EA. pi. 1. 2. f. 17. Chili,
(xn. 40.)

D. sculpta (E., K.). — Ai'ticulations
with striated margins ; valves linear-
oblong, with roimded ends and a narrow
striated border. KB. p. 109, pi. 29. f. 26.
= Tabellaria sculpta, EA. pi. 1. 2. f. 6.
Chili. Resembles Navicula borealis, E.

D. ? Bacillum (E., K.). — Articidations
striated, linear-oblong, with rounded
ends, and a large, oblong, longitudinal
median nodule. KB. p. 109. = Navicula
Bacillum, E. Fossil. Greece.

D. Navicula (E.). — Frustules oblong,
Bmooth, fom" or five times as long as

broad, with a smooth median stricture.
= Fragilaria ? Navicula, EA. p. 127,
pi. 1. 3. f. 8. Peru. We place this form
in Diadesmis because the frustules, in
the front view, have a minute punctum
at the middle of each lateral mai'gin, —
an appearance which usually indicates
the presence of central nodules.

D. Gallica (S.). — Filaments straight
or cm'ved; valves linear-elliptical, with
about 45 obscm-e strias in -001". Sm.
ANH. Jan. 1857, p. 11, pi. 11. f. 16.
Havre.

D.pei-egruia (S.). — Victoria tank, Glas-
gow. This species is unknown to us.

2* Marine.

D. Williarnsoni (S., Greg.). — Front
view linear, -with central and terminal
dilatations; valves linear, with attenuated
ends and 16 to 18 dotted striae in -001.
GDC. p. 25, pi. 2. f. 40. = Himantidium
WilliamsottijSED. ii. p. 14, pi. 33. f. 287.
Marine. Scotland.

Genus STIGMAPHORA (Wallich). —Frustules free, naviouloid; valves
lanceolate, loculate ; loculi with central and marginal puncta. Marine.
Frustules very hyaline, with two minute cells at the mid(Ue of each mai-gin
in both views ; valves with median line.

SxiGMAPHonA rostrata (Wallich). —
Valves rostrate ; beaks with a median
row of puncta. TMi viii. p. 43, pi, 2.
f.5, 6. (viu.43.) India.

S. lanceolata (Wallich). — Valves
acutely lanceolate, without median rows
of puncta. TM. viii. p. 43, pi. 2. f. 7, 8.
Inma.

924

SSSTEMATIC HISTOHY OP THE rNFUSORIA.

2* Frustules naviculoid, enveloped in gelatine or enclosed in a definite
tubular or gelatinous frond.

Subfamily SCHIZONEME^ oe LACERNAT^.

This group is remarkable for the great external resemblance some of its
species have to acknowledged Algae, widely as they differ in internal structure.

Genus FEUSTTJLIA (Ag.). — Frustules bacUlar or navicular, immersed in
an amorphous gelatinous substance. For the present we retain this genus
in the SchizonemeiE, but believe that, in most if not all the species, the frus-
tules are more like a Synedra than a Navicula, and want the central nodnle
of the latter.

t Striae evident.

FnusTinLiA salhia (E.). — ^Very narrow
linear, transversely stiiated ; in front view
with rounded ends, in lateral view sud-
denly acute. E Inf. p. 232. Saline
springs, Germany.

2 1 Strise wanting, or very indistinct.

F. Kutzinc/iana (Rab.). — Smooth, lan-
ceolate, with tnmcate apices. Rab D.
p. 35, pi. 8. f 3. = Synedra mucieola, KB.
p. 68, pi. 14. f. 5. On stones in a rivulet
near Nordhausen.

F. minuta (Rab.). — Minute, linear,
smooth, in front view with truncate
apices ; valves with acutely cimeate ends.
Rab D. p. 35. t. 8. f. 4. = Synedra Friis-
tidum, KB. pi. 30. f 77. Fresh water.
Germany and Italy. It forms an olive-
brown gelatinous mass on stones, and
becomes green in di-ying.

F. torfacea (Braun). — Rhomboid-lan-
ceolate, with obtuse apices, a stout me-
dian rib, and small central nodule. RabD.
p. 50, t. 7. f 2. Germany. It forms dii'ty-
yellow, rather firm, smooth or rugged
gelatinous masses about plants in bogs.
An authentic specimen from Professor

Braun appears to us identical with Na-
vicvla rhomboides.

F. Saxonica (Rab.). — Slenderer than
F, torfacea, with valves more acute;
front view linear, with broadly rounded
ends. Rab D. p. 50, t. 7. f. 1. Saxony,
Fonns dirty-olive-brown tremulous jelly-
like masses in" little cavities of damp
rocks.

F. Smcheriana (Kah.^. — Valves spin-
dle-shaped, with acute, pointed ends;
front view naiTow-lanceolate, ■with ob-
tuse apices. Rab D. p. 50, pi. 10. i. 14.
Germany. Fonns dirty gelatinous masses
on moss in streams.

F. acicidaris (E.). — Bacilla slender,
smooth, with acute apices ; valves more
acute, like a fine needle. ERBA. 1853,
p. 527. Mai'ine. Kingston Bay. Frus-
tules like those of F-agilaria HJtabdo-
soma, but ftee and heaped together
without ordei-.

F. bacillaris (E.). — Bacilla linear, pin-
nulate, with truncate apices in the front,
and romided in the lateral ^new. EB.
1853. Marine. Kingston Bay. This
species, like -F. acicidaris, seems included
in gelatine dilated like an idva, which,
when dry, appears membranaceous. In
the same' membrane both species are m-
cluded, with many other Diatomacea;.

Genus MASTOGLOIA (Thwaites).— Frastules oblong, naviculoid, annulate,
in a gelatinous mammillate cushion or frond ; annuli loculated ; locuh open-
ing by foramina along the line of suture. " The finistules of Mastogloia
are notably distinct from those of the other genera of this tribe, having the
annulate structure of Ehabdonema with the canaliculi of SirrireUa." " li^c
canaliciili are, however, formed differently fi'om those of Surirella, not hcmg
connected with the valve, but with the annulus, which projects as a scptiim
into the body of the frustule. The frastule itself is ordinaiily cxcentnc to the
mucus developed around it, and sits as it were on the summit of a httle
nipplc-liko cushion of gelatine " (Smith).

pi. 62. f 388. = Dicktcia Danseii, ANR.
1848. Brnclcish water. Britain. (xy.30.)

Mastogloia Danseii (ThwaitesV —
Valves clliptic-oblonfr, with 8 to 20 lo-
culi; strite 42 in 001". SD. ii. p. 04,

M. hinceoMa (Thw.).— Valves oblong-

OF THE KAVICTJLE^.

925

lanceolate, -witli subacute apices and 8 to
30 locidi ; strife 42 in -001". SD. ii. p. 64,
pi. 54. f. 340. Brackish water. Britain.

M. Smithii (Thw.). — Valves oblong-
lanceolate, with produced, obtuse or
capitate apices, and 6 to 24 loculi ; sti-iro
42 in -001". SD. ii. p. 65, pi. 54. f. 341.
Fresh or brackish water. Britain.

M. apiculata (S.).— Valves elliptic-
lanceolate, with slightly produced, ob-
tuse, conic apices, and 30 to 50 loculi ;
strijB 42 in -OOl". SD. ii. p. 65, pi. 62.
f. 387. Marine. Britain.

M. GrevilUi (S.). — Valves linear, with
obtuse, cuueate ends, and 15 to 20 locuH ;
strife moniliform, 24 in 001. SD. ii.
p. 65, pi. 62. f. 389. Fi-esh water. Britain.

M. minutu (Grev.). — Valve elliptic-
lanceolate or elliptic-oval, conspicuously
apiculate ; locidi 12 to 18 ; sti-ise very fine
and close. Trinidad. Grev. MJ. v. p. 12,
pi. 3. f. 10. It is a species evidently allied
to M. apiculata, but differs in_ being
scarcely half the size, and essentially in
the much larger loculi ; it is also much
more apiculate.

Genus PHLYCT^NIA (Kutz,).— Frustules navicular, included in (globose)
gelatinous cells. Marine.

smooth (?), linear, with rounded ends
contained in distinct, but contiguous,
gelatinous cells. KA. p. 9Q. = D-ustulia
maritima, E Inf. p. 232. Near Gothen-
burg. 1-1200" to 1-1150". This species
occurs as a brownish jelly-like mass on
stones. In the gelatinous cells Ehr--
enberg observed fi'om one to twenty
frustules.

Phxyct^nia minuta (K.). — ^Parasitic ;
ceUs hyaline, achromatic, solitary, scat-
tered, or binately approximate and aggre-
gated ; included naviculse few, binately
or quatemately conjoined, smooth ;
front view linear, with truncate apices ;
valves broadly lanceolate, with acumi-
nated ends. KSA. p. 96. Adriatic Sea.

P. maritima (E., K.). — Navicul*

Genus DICKIEIA (Berkeley). — Erond subgelatinous, plane, attenuated to-
wards the base, containing scattered, navicular, imperfectly sUicious frustules.
Marine. Dickieia is distinguished by its plane frond and scattered frustules.

DiCKEEiA ulvoides (Berk.). — Frond
undivided ; valves elliptical. ANH. xiv.
pi. 9; SBD. ii. p. 66, pi. 54. f. 342.
Britain, (xv. 31.) Frond linear or
obovate-stipitate ; sti-ise obscure, 36 in
•001" ; nodule transverse, Sm.

D. pinnata (Palfs). — Frond divided ;
valves elliptic-lanceolate. ANH. 2nd
ser. viii. pi. 5. f 6; SBD. ii. p. 66, pi. -54.
f. 343. Britain. Autumn. Di^dsions of
frond subpinnate; striae obscm-e, 40 in
•001" ; nodule pimctifonn, Sm.

Genus EHAPHIDOGLCEA (Kiitz.). — Frond globose, gelatinous, tender,
filled with fusiform bundles of naviculae disposed in radiating thi'eads.
Marine. " The principal character of this genus is taken from the amor-
phous disposition of the gelatinous substance in which tho frustules ai'e
immersed. The frustules are mixed together in a disorderly manner in
Berkeleya, whilst in Ehaphidogloea they are arranged in fusiform fascias,
confluent by the pointed extremities " (Meneg.). We think this genus
might, without inconvenience, be united with Berkeleya.

RnAPHiDOGi.CEA mcclusina (IC). —
Minute ; fascicles lanceolate-acuminate,
in irregular, reticulately -branched, con-
tinuous, radiating threads ; naviculse
lanceolate. KB. p. 110, pi. 22. f. 7. Me-
diterranean Sea. 1-600".

P. manipulata (K.). — Globose, pisi-

fomr; rays of fascicles reticulated, not
interrupted; naviculaj linear-lanceolate,
obtuse. KB. p. 110, pi. 22. f. 5. Europe.
1-700" to 1-200".

R. interrupta (K.). — Pisiform, with
slender rays of fascicles, interrupted in
a joint-like manner, with gi-adually ta-
pering branches; navicidsB linear, slightly

attenuated at the truncate apices. KB.
p. 110, pi. 22. f. 6. Adriatic Sea. 1-300".

B. mtcam (Lyngb., K.). — Subglobose ;
rays of tlie larger fascicles irregidar,
obsolete ; naviculse linear - lanceolate,
subulate, rather acute, elongated. KB.
p. 110, pi. 22. f. 8. = Schizo»ema micaiis,

AD. p. 17 ; Naunema micanj^, E Inf.
Friistnlia costnta, Lobarzeusltyinljinnira,
1840, pi. 5. f. 1. Europe. Uv. Tulfeu
West informs us that, from careful obser-
vation of living specimens, he is satisfied
that this species is identical with Am-
phiplmra pcllncida, in wliich opinion tho
late Prof. Smith fidly concurred.

926

SYSTEMATIC HISTOET OF THE INFTJSOBIA.

Genus BEEKELEYA (Grev.). — Fnistules naviculoid, linear-lanceolate
included within tubular submembranaceous filaments, which are free at
their extremities, but immersed . below in a more or less definite tubercle.
Marine. Berkeleya differs from Schizonema in having the base of the fila-
ments immersed in an orbicular gelatinous tubercle. This tubercle is at first
fii'm and definite, but finally, especially when growing on rocks, becomes
enlarged, soft, and often somewhat indefinite.

Bekkeleya fragilis (Grev.). — Fila-
ments subsimple, minute ; frustnles
crowded, slender, lanceolate or linear-

lanceolate, with the strias obsolete or
wanting. GBF. p. 416 ; SD. ii. p. 67,
pi. 54. f. 344. On Zostera, Algas, and
rocks. Europe. The gelatinous tubercle
during growth becomes attenuated and
more dSFused, and sometimes forms an

indefinite slimy covering about the base
of the filaments. In a di-ied state this
species acquires a metallic lustre.

B. Adriatica (K.). — Filaments branch-
ed ; branches distinctly subdivided ; frus-
tnles narrowly linear-lanceolate, rather
obtuse. KB. p. 109, pi. 22. 1 4. Adriatic
Sea. (xrv. 34, 35.) 1-300". Scarcely
distinct from B. fragilis.

Genus COLLETOKEMA (Breb.). — Frustnles naviculoid, arranged in series
within a tender, simple or divided, filiform or globose frond. Aquatic.
According to Professor Smith, " the freshwater habitat and slightly divided
frond distinguish the present genus from Sclmonema; and [he adds] the
frustnles are also more firmly siliceous than those of that genus, and the
character of the valve can usually be well seen after maceration in acid."
Professor Kiitzing describes CoUetonema as having a filifonn frond composed
of series of naviculfe held together and enveloped by an amorphous gelatinous
mucus, without an exterior gelatinous tube. We doubt if any of the above
characters sufiiciently distinguish CoUetonema from the allied genera, becaiise
they are either inadmissible in generic definitions, uncertain, or not peculiar
to the genus. The absence of an external tube, if constant, would be of
generic importance ; but we sometimes find the frastule contained within an
evident (although tender and evanescent) tube, whilst in Micromega, on the
other hand, the presence of an external tube is sometimes doubtful. The
fronds are exceedingly thin and tender, readily permitting the escape of their
frustnles, which may then be mistaken for species belonging to other genera ;
thus Professor Smith remarks that it is possible that Pinnularia radiosa may
be merely the free state of CoUetonema neglectum, and Navicula crassinervia
the same condition of C. vulgare.

CoLLETONEMA eximium (Thw., K.).
— Frond filiform ; frustule in lateral
view sigmoid, striated. KA. p. 891 ;
SD. ii. p. 69, pi. 56. I 350. = ScMzonema
eximium, ANH. 1848} Gloionema sig-
moides, EB. 1845 ; Encyonema sigmoides,
KA. p. 62. ? Britain, Deraerara ? Valves
linear, sigmoid from the ends sloping in
opposite directions ; strioe 50 in -Oul".
(viii. 43.)

C. viridulum (Br6b.). — Frond filifonn ;
naviculffl spirally and densely arranged ;
valves lanceolate, rather obtuse, smooth ;
front view linear-oblong, slightly and
gradually attenuated towards the ti-un-
cate apices. KA. p. 105. France.

0. lacustre (Ag., K.). — Frond filiform,
simple or subramose, finer than a hair,
enclosed in an imperceptible membrane ;
naviculoo elliptic or parnllelogramic, in
a single or double series. KSA. p. 105.

= Scliizonema lacustre, Ag CD. p. 18.-
Sweden. Tufts erect, brownish yellow; in
size and habit like SpJiacclaria cirrosa.

C. vidgarc (Thw.). — Frond filiform,
simple or di%dded, gradually tapering,
containing one or two regular rows of
frustules ; valves oblong-lanceolate, with
slightly contracted, obtuse ends. SD. iL
p. 70, pi. 56. f. = Schizonema vulgare,
ANH. 1848. England and France. Less
common, according to Professor Smith,
than the next species. Stri.ne 72 in -001".

C. ncglccium (Thw.).— Frond slightly
divided, obtuse, containing nmueroiis
and closely packed fi-ustules ; valves lan-
ceolate, witii obtuse ends. SBD. ii-
p. 70, pi. 56. f. 352. = Schizonema neg-
lectutn, ANH. 1848. England.

C. subcoh<Brens (Thw.).— Frond glo-
bose, gelatinous, pervaded by iiTCguJM
rows of frustules; valves oblong, with

OP THE NAVICtriiEiE.

927 •

rounded apices. SD. ii. p. 70, pi. 56.
f. 353. Dorset. Striss 28 m •001". In
the character of its frond this species
somewhat agi'ees with Rhaphidogloea;
but the friistules are an-angea in series,
not in fascicles, as in that genus.

Dmibtful Species,

C. ? ampMoxys (E., K.). — Known only
from fi-agments. Naviculse parallelo-

gramic, smooth; valves acutely lanceo-
late. KSA. p. 105. = Natmema am-
phioxys, EA, pi. 3. 2. f. 5. Mexico,
(xn. 55-57.)

0. ? Ameiicanum (E., K.).— Naviculfe
sti-iated, large, linear, with subacute
apices, densely an-anged within branched
tubes. liA. p. 105. = Naunema Amei-i-
canum, EB. 1845, p. 79. River Hudson.
Sti'ite 18 in 1-1200".

Genus SCHIZONEMA (Ag., Kiitz.) (Monema, G-rev. ; Monnema, Meneg. ;
Jfaimema, Ehr.), — Frustules naviculoid, arranged confusedly or in a single
file, within a capillary, submembranaceous, single-tubed, more or less branched
frond, of nearly equal diameter throughout. This genus, constituted by
Agardh, has been repeatedly divided and reunited, and the generic names
altered and transposed in an arbitrary manner without regard to priority.
Dr. Greville founded Monema for the species with single tubes, retaining
those with compound fronds in Schizonema. This division seems judicious,
and indeed has been adopted by nearly every succeeding writer, although
Greville's names have been disused or differently applied. Agardh recognized
the distinctions, but retained Schizonema for the species with a frond of
simple structure, and founded Micromega for the species having a compound
structure. As this arrangement has been followed by Kutzing, and acquiesced
ra by Greville, we use it here. There is the greatest difference, however, in
the distribution of the species, even amongst those who admit both genera.
" This discordance of opinion," observes Meneghiui, " as to the arrangement
of some species ia one or other of the two genera, which, independently of
their names, appear so distinct and so clearly defined, arises from the great
difficulty of discerning the parallel tubes including the particular series of
naviculffi. In some species the wall of the external tube is clearly distinct,
and the naviculae are confused -wnthin ; but in some others it seems as if,
instead of a tube, there wer6 a mucous mass in which the naticulse are im-
mersed." Professor Smith considered that " this great diversity of opinion
owes its origin to the variableness and inconstancy of the characters adopted
by the writers who arranged the species under two genera. The presence of
only one or of many files of frustules is certainly, to some extent, dependent
upon the stage of growth of the specimen examined ; and the appearance of
secondary tubes within the general mucus-envelope is more or less apparent
in different portions of the same frond, or according as it is examined in the
fresh or dry state. A very extensive comparison of specimens leads mc to
beheve that in every case where the development of the frond is much
advanced, as in the older or basal portions, numerous files of frustules may
be observed." For these reasons Professor Smith imited the genera and
divided Schizonema into two sections, " the fiirst having frustules fia-mly
siliceous, and fronds, in consequence, somewhat setaceous and robust ; and the
second including those species whose fi-ustiilcs are flaccid and delicate in
character." As we consider the diagnostic differences sufficient, we have
retained, with slight alteration, the arrangement of the species in these
genera given by Meneghini in his memoir upon the Diatomacea3. The frond
in Schizonema is generally densely tufted and more sparingly branched than
in Micromega. It is always single-tubed, and usually very slender, with
even, parallel margins. The ends of the filaments, wliich in the early state
are often empty, finally become iiiptured and permit the escape of the
naviculac. In a recent state these characters wiU generally suffice to deter-

•928

SYSTEMATIC HISTOET OF THE INFUSOKIA.

mine the genus, even before minute mici-oscopic examination. We place
more reliance upon coloui- in the discrimination of species than some writers
allow. The colour for the most part depends upon the contents of the frus-
tules, and, according to our experience, is subject to little variation, except
in old specimens rendered unfit for comparison by the escape of the naviculib.

* Central nodule transversely dilated.

ScHizojTEMA cruciger (S.). — Filaments
much divided ; naviculae crowded ;
valves lanceolate, acute, striated; me-
dian nodule transversely dilated into a
stauros. SD. ii. p. 74, pi. 56. f. 354.
Britain. Striffi distinct, 40 in -001".

2 * Central nodule punctifor7n, sometimes
obsolete.

S. Grevillii (Ag.). — Frond membra-
naceous, much branched, level-topped;
naviculfe in front view subquadrate ;
valves oblong-lanceolate, with 60 striae
in -001". Ag CD. p. 19 ; SD. ii. p. 77,
pi. 58. f. 364. = Monnema Grevillii,
Meneg. ; S. quadripunctatum, Harv. On
rocks and mud. Fronds densely tufted,
brown, tm-ning to a dirty verdigris-green
when dried, and adhering imperfectly to
paper. Navicidse large, crowded at base,
m a single file near the extremities. S.
quadripunctatum of British writers is an
old state, and tm-ns of a rusty colom* in
drying. 1-576",

S. crinoideum (Harv.). — Filaments
very slender, achromatic, sparingly
branched, densely woven into a pale-
green or brownish stratum ; nav^culse
very minute, disposed in an hregidar
loose series. Harv. Manual, p. 214. =*S'.
tenelhrni, KB. p. Ill, pi. 23. i. 8 ; 3Ton-
nema quadi-ipanctatum, Meneg. Europe.
Filaments exceedingly slender, with long,
simple, hexuose branches. Brown when
recent, olive-green and glossy when diy.
1-1386".

S. Dillioynii (Ag.). — Frond densely
tufted, rich brown, very slender; navi-
culsB minute; valves lanceolate-acute,
smooth. SD. ii. p. 77, pi. 58. f 366.=
Monema Billwynii, GCF. pi. 297. Hocks,
mud, and Algre. Naviculas imper-
fectly silicious, more or less crowded,
especially near the extremities; fronds
turning deep green on immersion in
fresh water, and quicldy acquiring an
offensive smell ; generally glossy when
dried. 1-1000".

S. implicatum (Harv.). — Frond capil-
lary, densely tufted, much branched,
curled, and entangled ; naviculoe very
minute, irregidarly crowded ; valves lan-
ceolate, rather obtuse. SD. ii. p. 78,

pi. 59. f. 367. On mud in sheltered
places. Tufts of a duller brown than
S. Dillioynii, gradually turning in fresh
water to a dark olive-oi-een, not quickly
becoming offensive. Frustules in form
and size similar to those of S. rutilans.

S. dnhium (Harv.). — Resembles S.
Dilkvynii; but the long branches, naked
below, are fmnished towards their sum-
mits with numerous curled ramuh. Harv.
Manual, p. 212. = S. Dillwynii /3, KA.
p. 101. Rocks, &c. Tufts unequal-
topped ; apices of ramuli acute ; naviculae'
very minute and densely packed.

S. virescens (Harv.). — Fronds very
slender, densely tufted, tenacious, very
much branched from the base; ramuli
numerous, cm-led, upper ones longest,'
swelling towai'ds the tips, which are
dark-colom-ed and end in a sudden
point ; naviciUas minute. Harv. Manual,
p. 212. North Devon. Tufts dense,
brownish olive, not much altered in
drying. Under the microscope it has
much the appeai'ance of S. Dillwymi;
but the thickened, dark-coloured tips
are remai-kable.

S. rutilam (Trentepohl, Ag.). — Densely
tufted; filaments elongated, subsimple,
brownish and empty at base, hyaline
and filled with crowded linear-oblong
frustides at the apex ; when diT, shining
and reddish. Ag CD. p. 18 ; KB. p. 112,

SI. 23. f 6. 1, 2. = Momiema rutilans,
leneg. " It differs fi-om S. DiUicynii by
its more vamish-like lusti"e, reddish
colour when dry, and finer and more
simple filament" (Ag.).

S. noffmannii (Ag.). — Filaments
tufted, subsuuple, arachnoid, when dry
shmiug with a reddish lustre ; navicidss
small, smooth, crowded ; valves lanceo-
late. = S. rutilans, var. Jlqff'manni, KB.
pi. 23. f. 10; Monnema Ilofinannf, Meneg.
Europe, Aberdeen, (x. 207.) Professor
Kiitzmg makes this form a variety of
S. rutilans ; but Moneghini observes that
they difier in external characters and m
the dimensions and shape of the navi-
culffi. 1-1080" to 1-960".

S. Balticum rE.).— Navicidag striated,
slender, linenr-lauceolat«, in front view
truncate, in lateral view subacute, dense,
crowded in the intricatelv branched fila-
monfc". EInf. p. 286, pi. 20. f. 15.=-S

OP TITE NATICTJUOiE.

929

rutilans, var. viride ; Blonnema octo-
carpoides, Meneg. Europe, England.
1-1200".

S. HJirenberffii (K.). — Fi'ond parasitic,
lubricous, tufted, green, branched;
branches crystal-hyaline, soft, obtuse at
the apex ; naviciilEe (in dried specimens)
inconspicuous, tender, arranged in obso-
lete series, oblong in one view, trimcate
in the other, with rounded ends. KB.
p. 113, pi. 23. i.9.=Natmema Dillwynii,
E Inf. p. 235, pi. 20. f. 13. Eiu-ope.
1-1320".

S. spadiceum (Grev.). — Filaments' ca-
pillary, tufted, much branched, of a red-
dish olive-green colour; ramuli much
divaricated, ultimate ones patent ; navi-
culffi linear- oblong, elongated. Grev. in
Hooker's Br. Fl. p. 412. Scotland.
Fronds often with a faint metallic lustre
when diy. Filaments very slender, and
of neai'ly equal thickness throughout.

S. Adriaticum (Ag.). — Filaments finer
than a hair, elongated, subsimple, when
dried of an opaque olive gi-een ; naviculse
nan-ow, lanceolate. AgCD. p.2l. Venice.

S. confertum (S.). — Frond filifonu,
sparingly divided throughout ; navicnlEB
exceedingly crowded ; valves shortly lan-
ceolate, acute, with indistinct, marginal
strife. SD. ii. p. 75, pi. 57. f. 359. Aber-
deen. -0008" to -0011".

S. lutescens (K.). — Trrfted, when di'y
of a reddish colour, glossy; filaments
subsimple, capillary, coloui'ed and empty
at base, hyaline and filled with navi-
culfe at the apex ; naviculse oblong-lan-
ceolate, obtuse. KB. p. 112. Europe.
1-1200".

S.Jlavimi (K.). — Frond tufted, lubri-
cous, yellow; filaments tenacious, cry-
stalline, achromatic, straight, fastigiate,
branched; branches attenuated at the
apex, erect ; naviculte scattered or inter-
ruptedly aggi-egate, oblong or linear, with
obtuse or trimcate ends. KSA. p. 101.

i France. Navicidse rather broad.

S. luteum (K.). — Frond tufted, yellow ;

' filaments achromatic, capillary, subfra-

: gile, nearly equal throughout ; naviculos
linear or acicular, inconspicuous, alter-
nately loosely and densely compacted.

: KA. p. 102. France. 1-1080".

S. sordidum (K.). — Fronds minute,
tufted, parasitic, didl brownish-grey;
filaments subdichotomous, achromatic,
with equal branches; naviculse slender,
truncate ; valves lanceolate-linear, rather
obtuse. KB. p. 113, pL 24. ll. =3£on-
nema sordidum, Meneg. On Zostera.
Europe. 1-1440" to 1-1200".

S. tetme (Ag.). — Filaments arachnoid,
iiTegidarly branched; naAdculfe elliptic,
disposed almost in a single series. KB.
p. 112, pi. 23. f. 2. = Monnema tenue,
Meneg. Adiiatic Sea. When dried it
appears as a sidphur-green stain; fila-
ments inconspicuous from their tenuity,
Ag. Professor Kiitzing refers Agardh's
species to his S. miccosum, but we doubt
their identity.

S. simjjlex (E., K.). — Frond subsoli-
tary; naviculse smooth, oblong, with
rounded ends, in a simple series within
flexible filiform tubes. KA. p. 99. =
Naunema simplex, E Inf. p. 234, pi. 20.
f. 12 ; Ilonnema inconspicuum, Meneg.
p. 436? Adi-iaticSea. 1-1150" to 1-570".

S. Zenormandi (K.). — Parasitic, short,
subsimple, in woolly tufts ; filaments
achromatic, for the most part with empty
apices ; navicula3 quadi'angular, arranged
in a simple series. KA. p. 99. = Mon-
7iema Lenoi'mandi, Meneg. France.
Allied to S. ti-nuc, but with smaller
frustides, Meneg.

S. teniiisshmim (K.). — Filaments
crisped, subramose, hyaline, very slen-
der, densely interwoven into a compact,
brown mucous stratum; navicula3 very
minute, linear, trimcate, in obsolete
series. liB. p. Ill, pi. 23. f. 111. 1-3.
= Monnema tenuissimum, Meneg. Adii-
atic Sea.

S. striolatum (K.). — Fi-onds tufted,
m-een, crisped, capillaiy, fastigiatcly
branched ; filaments transversely stri-
ated, nearly empty at the base, filled at
the apex, crystal-hyaline througbout ;
naviculfe oblong, obtuse in tlio lateral,
truncate in the front view. ^ claviffcrum,
branches irregular, covered \v\th oibovate
or clavate ramuli. KB. p. 114, pi. 26. f. 2.
= Monnema striolatum, Meneg. Ger-
many and France.

Genus MICROMEGA (Ag., Kiitz.) ( = Sclii7;oncma, Meneg.). — Frustulos
na\iculoid, arranged in two or more longitudinal scries within a gelatinous
filiform or setaceous frond, or contained within tubes united longitudinally
into a compound, often membranaceous frond. Micromega is distinguished
from Schizoncma by its compoimd frond. We believe that under one genus
bave been comprised species belonging to two distinct types, which perhaps
' ought to form two genera.

3o

930

SYSTEMATIC HISTOBJ 0]? THE INFUSOHIA..

The first contains species having series or files of naviculaj surrounded by
a gelatinoiis covering, and by theu" union forming a compound, generally
stout frond, externally furnished with a common epidermis. Type, M. Smithii.
The species of this section are highly gelatinous, and consequently adhere
fii'mly to i^aper in di-ying, are frequently of considerable thickness at the
base, and often have their extremities lobed, proliferous, or peniciUate. The
margins, especially in old specimens, are generally more or less rough or
irregular. The frustules are released by the destruction of the gelatine, and
not by injury to the extremities, as in the case of tubular fronds. Each
series of frustules seems to have its own proper gelatinous covering, and the
junctions are marked by faint longitudinal lines ; but these, which have
been supposed to indicate tubes, are often very indistinct ; hence arises much
of the (hffieulty in determining their proper genus.

The second section contains species which have a strictly compound frond
of distinct tubes longitudinally connected, each tube similar to a frond of
Schizonema. The fronds are generally membranaceous, and adhere imper-
fectly to paper; the frustules, arranged more or less irregularly in their
tubes, are liable to escape from an opening at any part. Type, M. cornoides.
If these sections, as is probable, should hereafter rank as genera, the three
aUied genera might be named and characterized as follows : —

1. MoiwEMA (Grev., Meneg.) (=Schizonema, Ag., Kiitz.). — Frond tubular,
single-tubed.

2. ScHizoiTEMA (Ag., Grev., Meneg.) (=Micromega, Ag., Kiitz.). — Frond
gelatinous, not tubular.

3. MiCEOMEGA (Ag., Ehr.). — Frond tubular, two- or more tubed. The
branching in Micromega, especially in the species belonging to the first
section, results from the separation of the series of naviculae, and is not the
branching of a tube, as in Schizonema.

and darker-colom-ed fronds, and its larger
and very obtuse valves.

M. to7-quatum (Harv.). — Frond robust, i
simple below, much divided above, ulti-
mate divisions much twisted; naviculse
in longitudinal files ; valves oblong-lan-
ceolate; stiife 40 in -001".= Schizonema

* Frond gelatinous, containing longitu-
dinal series of navicidce.

MiCKOMEGA Smithii (Ag.). — Frond
robust, setaceous, gelatinous, firm, simple
below, much branched above, frustules
in longitudinal series ; valves lanceolate,
acute ; striae 40 in -OOl". = Schizonema
Smithii, AD. p. 18; SD. ii. p. 76, pi. 57.
f. 362. Rocks and Algse. Common.
Fronds usually scattered, pale-yeUowish
olive; naviculae disposed in subdistant
files within the colourless jelly of the
frond. 1-600".

M. helminthosu7n (Ohauv.). — Fi'onds
robust, setaceous, gelatinous, lubricous,
tufted, much branched, with acute apices;
navicidae in longitudinal series; valves
eUiptic-oblong, with rounded ends ; striaj
48 in -001". = ScMzone^na hclmiiithosKm,
AD. p. 20; I^A. p. 103; SD. ii. p. 74,
pi. 56. f. 355 ; S. Arbuscula, KB. pi. 27.
i. 1 ; Naunema Arbmcida, E Inf. ; N. fni-
timdosum, Kji. p. 104. Rocks. Colour
olive-brown, becoming greenish-grey and
without gloss in drying. 1-504". It
may be known from M. Smithii by its
more tufted, often gregarious, lubricous

torquatum, Me. ; SD. ii. p. 76, pi. 67.
I 361 ; S. Smithii, /3. torquatum, liarv.
Manual, p. 211; ilicromega setaceum, y.
torquatum, KA.. p. 107. Britain. In size

and coloiu- it agi-ees with M. Smithii, but
is remai'kable for having its branches
ciu'led ; its naviculte are more distinctlyi
in chauis, shorter and broader in propor-
tion to theu- length than in that species. <i
1-720" to 1-690".

M. Polyclados (K.).— Fi-ond setaceous,^
dichotoniously branched ; branches .elon-iJ
gated, slender, rather rigid; nayiculffla
(membranaceous P), flaccid, in distinctJ
tubes. KB. p. 118, pi. 28. f 1. Eiirope-J
Spei-matia elliptic. 1-1086" to 1-9W) J
Jleneghuii unites this form ^vith M. »r-|

quotum. vii
M. nchdostim (Me.). — Fi-ond slightlj
greenish, cloudy, subachroraatic, fomung
an intricate mucous stratum ; tubes gela-.
tinous, achromatic, obsolete; na^•lCuJa'

i

OF THE NATICULE^.

931

slender-lanceolate, rather obtuse, loosely
scattered. = Schizonema nehulosum, KA.
p. 99. Daknatia. " Kutzing is right in
remarking that my Schizonema nebulosum
corresponds to 31. torquatum in the form
and dimensions of the naviculse. Al-
though when dried upon paper it only
forms a light cloud, yet, when diligently
examined, it proves similar in ramifica-
tion to Harvey's species " (Me. p. 445).
1-1080".

M. Wyattii (Haiw.). — Frond carti-
laginous, setaceous at base, much
branched ; branches capillary, erect,
sti'aight, with acute axils, tapeidng to a
fine point; naviculse lanceolate, densely
packed in jelly. = Schizonema Wrjattii,
Hai-v. Manual, p. 211. England. Foims
globose tufts. This species comes neai'
S. Smithii, but is much more slender,
and opens more readily and with greater
elasticity after being dried.

M. moUe (S.). — Fi'ond gelatinous,
simple below, membranous by cohesion
above ; margin much divided, into acute
segments ; naviculae in crowded files ;
valves lanceolate, acute, with 48 stri»
in •001". = Schizonema molle, SD. ii. p. 77,
pi. 58. f. 365. Britain. -0012^0 -0015".
The navicidas are veiy like those of M.
helminthosum, but the foim and stnicture
of the frond are altogether difierent. The
frond is soft and flaccid, but the naviculse
are fimdy silicious.

M. diver gens (S.). — Fi-ond simple be-
low, sparingly divided or by cohesion
irregularly snbmembranous above; valves
oblong-lanceolate, with 42 striae in -001".
= Schizonema divergens, SD. ii. p. 76,
pi. 57. f. 363. Lame Lough. •0013" to
•0018". Eemarkable for the difiused
arrangement of the primai-y divisions.
The species is closely allied to M. Smithii
and M. torquatum.

M. sirospermum (K.). — Frond rather
-tout, rigid, olive, cartilaginous, much
branched; branches unequal, irregular,
curved, setaceous; naviculse lanceolate,
in dense series, often inflated into glo-
bose; spermatia concatenate. KIA. p. 109.
■ = Schizonema sirospermiim,M.e. England.
Perhaps a state of M. Smithii. 1-720".

M. setaceum (K.). — Frond setaceous,
olive, rigid, subdichotomous ; branches,
lateral and terminal, abbreviated, spine-
: like ; navicula3 in crowded series ; valves
■lanceolate, acute. KB. p. 117, pi. 25.
f. 2, 3. = Schizonema setaceum, Me. Adri-
atic Sea. 1-720" to 1-606". Spematia
elliptic-globose.

M. corymhosum (Ag., K.). — Frond
wborescent, rather stout at the base,

firm, rigid, yellowish, much branched;
branches setaceous, rig-id, here and there
corymbose; navicidao in distinct, close
series; valves elliptic-lanceolate. KB.
p. 117, pi. 27. f. 9. = Schizonema coryin-
6osMm, AD. p. 21. England. 1-960".

M. hydruroides (K.). — ^Fronds greenish
or bro-wn, ultra-setaceous, rigid ; branches
elongated ; ramuli fasciculated, capillary ;
naviculse in close series, minute, rather
broad ; valves with roimded ends. =
Schizonema hydruroides, KB. p. 114, pi. 26.
f. 7. Heligoland. 1-1380".

M. Bryopsis (K.). — Frond green, seta-
ceous, rigid, branched ; branches scat-
tered, superior ones patent, obtuse ; na-
viculas oblong, truncate in front, and
rounded in lateral view. = Schizonema
Bryopsis, KB. p. 114, pi. 26. f. 8, HeU-
goland. 1-680".

M. trichocephalum (K.), — Frond green-
ish-yellow, ultra-setaceous, rigid, tufted,
spaiingly branched ; inferior branches
scattered, simple ; temiinal ones crowded,
cui'\'ed, subulate, capitate ; naviculse in
very close series, minute. = Schizonema
trichocephalum, KB. p. 114, pi. 27. f. 3.
Heligoland. 1-1440".

M. capitatum (K.). — Frond pale gi'een,
setaceous; branches elongated, slender,
virgate, with a corymbose, capitate, acute
apex ; naviculse in distinct series, minute ;
valves lanceolate. = Schizonema capita-
tum, KB. p. 114, pi. 27. f. 4. Heligoland.
1-1200".

M. myxacanthum (K.). — Less stout
than M. corymhosum, gelatino-cai'tila-
ginous, pale brown ; branches diverging,
attenuated at the base, digito-multifid
at the apex ; divisions patent, acute ;
series of lanceolate naviculse at base
few and loose, above more numerous,
crowded at the apex. KB. p. 117, pi. 24.
f. 8. = Schizonema myxacanthum, Me.
Adriatic Sea.

M. aureum (K.). — Frond ai'boresceut,
setaceous at base, rather rigid, ochra-
ceous-yellow, much branched, fastigiate ;
branches capillary, pale, mucous ; series
of naviculse and tubes distinct, crowded ;
valves lanceolate. KJB. p. 117, pi. 27. f. 8.
= Schizonema aurcum. Me. Sidmouth.
1-960".

M. obtusiiyn (Grev.). — Frond robust,
setaceous, elastic, firm, irregularly dicho-
tomous, with rounded axils and obtuse
apices ; naviculse minute, crowded in
iiTc^ular files; valves elliptic-oblong. =
Schizonema obtmum, Grev BF. vi. pi. 302 ;
SD. ii. p. 78, pi. 58. f. 368. Britain.
The naviculoo are excessively crowded,
and we are uncertain whether this spe-
3 0 2

932

SYSTEMATIC HISTOHY OF THE INFUSOBIA.

cies ouglit not rather to' be placed in
Scliizonenia. "Frond thicker than a
hog's bristle, and nearly of equal diameter
throiig-hout ; coloiu- brownish-yellow, be-
coming yellowish-green in dying. A
handsome and distinct species, well
marked by its roimdish axils and obtuse
apices " (Harvey).

^ _M. Blytlii (Ag.). — Frond elongated,
iiliform, many times in-egularly dicho-
tomous, •ftdth roimded axils, cylindrical,
not attenuated; naviculaj in numerous
parallel series. AD. p. 23. = ScJiizonema
Blyttii, Me. Norway. An elegant and
remarkable species ; fronds erect.

M. mesofjlwoides (K.). — Frond stout,
very gelatinous, greenish, irregularly
branched ; branches dense, mmierous,
imequal ; ramiili incrassated at the apex,
patent; naviculte rather irregularly ag-
gregated, dense ; valves with attenuated
apices. — Schizonema mesoglceoicles, KA.
p. 103. Aberdeen. 1-600".

M. huinile (K.).— Frond parasitic, very
short, tufted, erect, subramose ; branches
with obtuse, hyaline empty apices ;
naviculfe acute, linear-lanceolate, ar-
ranged in two to four series. = Schizo-
nema liumile, KB. p. Ill, pi. 23. f. 7.
Adriatic Sea. Naviculse in fi-ont view
linear, truncate. 1-1200".

M. papillosum (Me.). — Frond para-
sitic, small, very mucous, gi-een; fila-
ments ultra-setaceous, subsimple or fm--
nished with acute spiniform ramuli,
everywhere covered with very minute,
regularly disposed papillae ; valves nar-
row-elliptic, rather obtuse. = Schizonema
papillosum, Me. p. 452. Dalmatia. Na-
viculse in series, four times as long as
broad, in front view slightly elliptic,
with truncate ends. The papillre appear
hemispherical or slightly conical, and
are arranged in quincunx, Me.

M. Stalianum (Me., K.). — Fronds pa-
rasitic, gelatinous, gi-een or o;reenish-
brown; filaments setaceous, elongated,
iiTegularly branched; branches diverg-
ing, short ; naviculas in series, six times
as long as broad ; valves elongated-
elliptic, obtuse. KA. p. 106. = Schizo-
nema Stalianum, Me. p. 452. Dalmatia.
Is very mucous and adheres strongly to

fiaper; naviculae in front view exactlv
inear. 1-420" to 1-360".

M. Corinaldi (Me.). — Frond parasitic,
small, gi-een ; filaments subsimple, se-
taceous ; frustules minute, five times
as long as brond; valves narrow-ellip-
X ic. = Schizonema Corinaldi, ]\Ie. p. 453.
J^Iar.seillos. Naviculaj in series, in front
view exactly linear. The threads, .slightly

mucous, are usually simple ; the few ra-
mifications are short and divaricate, Me.

M. fastigatum (K.).— Frond setaceous,
olivaceous, much branched ; ultimate
branches subcorymbose, with lanceokte-
acuminate apices ; na\dcul8e minute, ob-
long, obtuse, in loose series. KA. p. 108,
Torquay. Secondary tubes obsolete.

M. medusinum (K.). — Frond cartila^
gino-gelatinous, hyaline, brown, turgid
at the base, separated at the apex into
penicillate fibres; series of navicul®
loosely entangled, intermixed with flex-
uose longitudinal fibres. KB. p. 118,
pi. 25. f. 6. = Schizoneyna medusinum, Me.
Adriatic Sea. Valves lanceolate.

M. hyalinimi (K.). — Frond coloiu-less,
hyaline, gelatino-cartilaginous, soft, seta-
ceous at base, much branched ; branches
attenuated, capillary, empty at the apex ;
series of naviculae few, loose, intemuxed
with a few fibres ; naviculae minute ;
valves oblong-lanceolate, obtuse. KB.
p. 117, pi. 24. f. 6. = Schizonema h)/alinum,
Me. Adriatic Sea. Naviculae 1-960" to
1-780"; in front view truncate.

M. tenellum (K.). — Frond colourless,
hyaline, gelatino-cartilaginous, setaceous,
branched, subdichotomous ; branches
delicate and empty at the apex ; series
of slender na^aculae and internal tubes
distinct. KB. p. 117, pi. 24. f. 7. = Schi-
zonema tenellum. Me. Adriatic Sea.

M. Hyalopus (K.). — Frond colourless
and hyaline at the base, above greenish,
narrow, much branched; branches fas-
tigiate, subacute, fuU to the apices ; lower
series of naviculae lax, superior crowded;
valves lanceolate. KB. p. 117, pi. 25.
f. 5. = Schizonema Hyalopus, Me. Adri-
atic and French Seas, Jersey. Internal
tubes obsolete ; na^•icula^ in front view
oblong, truncate ; spermatia immersed,
globose.

M. laciniatum (Harvey). — Frond ro-
bust, setaceous below, incrassated above,
very tender and gelatinous, cleft into
numerous tapering branches; navicular
very minute, in close files ; valves ellip-
tic-lanceolate, o\)t\ise. = Schizonema laci-
niatum, Ilarv. Man. p. 210; SD. ii. p- '^S
pi. 59. f. 371 ; S. scoparium, KB. p. IH.
pi. 27. f. 7. Europe. Frond cleft above
into numerous irregular jagged branches.

M. parasilicum (Griff., K.). - Fro"J
gelatinous, capillarv, tufted, much ana
intricately branched from the base ;
branches 'flexuose, with rounded axils;
frustulcs crowded in distinct file.« ; valves
lanceolate, acute. KB. p. 11«, pl- 2'- 1-
= Schizonema parasiiicum. llarv. Man.

OF THE NAVICtTLE.Ii;.

933

p. 213 ; SD. ii. p. 79, pi. 59. f. 371. Eu-
rope. Coloiu- pale yellowish, sometimes
brownish. Naviculte 1-1380".

M. invesicns (Montague). — Fronds
para.?itic, miniite, lubricous, brown,
opaque, fasciculated; filaments dilated
at the base, diilusely ramose ; branches
anastomosing ; naviculse large, in one or
two series. = Schizonema investens, Mont.
Annales des Sci. Nat. 1850, p. 308.
Guiana. Naviciilse with two nuclei.

M. mueosum (K.). — Frond soft, highly
mncous; filaments contiguous and con-
fluent; branches iiTegidar; naviculte in
few files; valves elliptic-oblong, with
roimded ends, delicately striated. = Schi-
zonema mucomm, KB. p. 115, pi. 26. f. 9 ;
SD. ii. p. 75, pi. 57. f. 360. Adi-iatic Sea,
England. This species can scarcely be
the Schizonema temie of Agardh, as
Kiitzing has supposed.

M. parviim (IM^.). — Frond olive-green,
mucous; filaments hyaline, simple (?),
much entangled and cmwed ; naviculce
in distinct, loose, oblique or straight
series ; valves lanceolate. = Schizonema
jmrvum, Me KA. p, 100. Venice, Cay-
enne. Naviculte m front view linear,
rectangular. 1-1200".

M. Meneghinii. — Frond green, very
gelatinous; filaments very hyaline, lu-
bricous, fastigiately di\'ided and laci-
niated; naviculaa lanceolate, in loose,
rather distant ^^x\&%. = Schizonema hom-
hycinum, Me KA. p. 100. Venice.
1-1200".

M. Kiitzinffii. — Fronds tufted, intri-
cate, much branched ; filaments hyaline,
with rather acute apices; naviculiB in
distinct series ; valves lanceolate, acute.
= Schizonema jloccosum,YJii. p. 11.3, pi. 24.
f. 3. Germany. NavicidiB in front view
oblong, truncate. 1-600".

M. crispum (Mont.). — Fronds small,
crisped, capillary, green, branched : fila-
ments obtuse, dilated and midtifid at
the apex; navicultE very minute, much
crowded in obsolete sGne!*. = Schizone7na
crispum, KB. p. 113, pi. 29. f. 71. Auck-
land Islands.

M. plumosum (K.). — Frond tufted,
wavy, rather curled, green, fastigiately
branched ; filaments densely filled at the
ends, dilated, multifid ; navicuLc distinct,
very minute ; valves oblong-elliptic, with
rounded ends. = Schizonema plumosimi,
KB. p. 113, pi. 26. f. 1. Em-ope. Navi-
ciUre in front view oblone:, truncate.
1-1440".

M. Zanardinii (Me.). — Frond very fine,
pale green ; filaments capillary, gradually
separating into corymbose' arachnoid

branches of one series ; naviculas in loose
series, foiu- times as long as broad ;
valves elliptic. =<S'c/ti^o«e?na Zanardinii,
Me. p. 453. Venice. Naviculas in front
\-iew exactly linear. Fronds in globular
tufts, which, dried upon paper, form
imiform spots, in which the separate
threads can only be distingviished_ by a
lens. In its mode of ramification it re-
sembles M. flagelliferum, Me.

^l. flagelliferimi (K.). — Fronds very
minute, tufted, parasitic, floccose, capil-
lary; branches erect, separated at the
apex into flagelliform fibres; series of
the very minute naviculos and internal
tubes distinct. KB. p. 116, pi. 24. f. 4.
= Schizonema Jiagelliferum, Me. 1-1920"
to 1-1560".

IsL floccomm (K.). — Frond minute,
subcapillary, branched, rather delicate,
gelatinous; series of the long, obtuse
and ti'imcate naviculas .and internal tubes
very distinct. KB. p. 116. Adriatic Sea.
1-720';.

M. intricatum (K.). — Frond delicate,
subgelatinous, nebulose, pallid yellow,
irregidarly branched ; branches patent,
upper ones abbreviated; series of navi-
cidte loose, intermixed with very fine
longitudinal fibres ; navicidce oblong,
obtuse, very minute. KB. p. 116, pi. 26.
f. 5. = Schizonema intricatum, Me. Eng-
land. 1-1440" to 1-680".

M. bombgcinum (K.). — Frond pale yel-
low, contorted, twisted, much branched,
capUlary; naviculte remotely concate-
nate, inconspicuous, and very minute.
KB. p. 116, pi. 26. f. 6. = Schizonema
bomhycinum, Me. Em-ope. (xiv. 43, 44.)

M. ? Agardhii (E.). — Navicidte very
nan-ow, acute, arranged in a simple
series within a proper tube ; tubes liis-
cicidtitely joined into a filament. = ^Sfc/u-
zonema Aqardhii, E Inf. p. 238, pi. 20.
f 16. _ North Sea. (x. 208.) Professor
Kiitzing unites this species with 3£. bom-
bgcinum; but the frustules are apparently
(judging from the respective figures)
much largei-.
_ M. patens (K.). — Frond minute, para-
sitic, iioccose-capillai-y, soft, gelatinous ;
branches divergent or patent, with ob-
tuse apices; series of uaviculto and in-
ternal tubes distinct ; navicul.io very
minute. KJ3. p. IIG, pi. 24. f. 6. = Schi-
zonema patens, Me. 1-2400",

M. lineatum (K.).— Frond decumbent,
intricate, capillary, olivaceous, tenacious,
lubricous, subraniose; brauches at the
apex attenuated, curved, rather obtuse •
series of the vi-ry minute lanceolate
I uaviculsQ distinct. 103. p. 116, pi. 28.

934

SYSTEMATIC HISTOKY

OF THE INFUSOEIA.

f. 4. = ScJdzonema lincatum, Me. Dal-
matia. 1-1320" to 1-1200".

M. (jraciUimum (S.). — Frond capillary,
simple below, sparingly branched and
submembranous towards the apices ; na-
■\dcula3 crowded in irregular files ; valves
lanceolate, acute. = Schizonema gracilli-
mum, SD. ii. p. 79, pi. 59. f. 372. Tor-
quay. -0009".

M. Ulyricuni (K.). — Fronds forming a
didl-, obsciu'e-green, mucous, intricate
stratum ; filaments very fine, simple (?),
soft, hyaline ; naviculse acuminate, lan-
ceolate, in dense series, indistinct when
dried. = Schizonema Illyi-icum, KB. p. Ill,
pl.22. f. 3. Trieste. 1-1680" to 1-1440".

M. minutum (K.). — Frond parasitic,
very short, fine, decumbent, subramose ;
branches tapering to acute apices ; navi-
culse acute, lanceolate, in few (2 to 4)
series. = Schizonema miniitum, KB. p. Ill,
^1. 23. f. 5. Adriatic Sea. Naviculse in
iront view linear. 1-1176".

2 * Frond composed of tubes longitudi-
nally connected,

M. comoides (Grev.). — Filaments dirty
brown, coarse, membranaceous, elongated,
twisted, composed of parallel tubes ;
fnistules crowded ; valves oblong-lan-
ceolate; sti'ise 48 in ■001". = Schizo7iema
comoides, Grev. (scarcely of Agaxdh,
certainly not the Conferva comoides of
Dillwyn); Hook Br. F. p. 413 ; SD. ii.
p. 75, pi. 57. f. 358 ; Schizonema araneo-
sum, KB. p. 113, pi. 25. f. 9. Flat rocks,
often in vast quantities. It is very re-
markable that this coarse, dii-ty-looking
species should ever have been confoimded
with the Conferva comoides, Dillw. The
latter, we were assured by Mr. Dillwyn,
was totally imlike the present species,
and was correctly described by him.
Unfortimately Mr. Dillwyn was unable
to find an onginal specimen of his spe-
cies, but he believed that a very slender
simple-tubed Schizonema, of a bright
brown colom-, which we once found in
great abimdance in April, on the rocks
outside the Mumble Liglithouse neai*
Swansea, was the true Conferva comoides.
The present species is usually twisted in
a rope-like manner, retains its colour in
diying, is very opaque, and does not
adhere to paper.

M. ramosissiynum (Ag.). — Frond robust,
film, membranaceous, much branched;
branches short, swelling upwards ; frus-
tules minute, densely arranged in distinct,
parallel tubes ; valves oblong-hiiiceolate.
AD. p. 22. = Schizonema ramosissimum,

Ilarv. Man. p. 210 ; SD. ii. p. 78, pi. 59,
f. 369. Europe. Somewhat resemblea
M. comoides in appearance, but is less
elongated and less twisted. Does not
adhere to paper.

M. apicidatum (Grev., Ag.). — Frond
robust, ultra-setaceous, cartilaginous,
ii-regidarly dichotomous ; branches with
clavate ends, terminated by a mucro;
secondary tubes distinct; navicida3 mi-
nute, crowded; valves lanceolate. AD.
p. 22 ; KB. p. 117, pi. 27. f. 10. = Schi-
zonema apiculatum, AA. p. 11; Harv.
Manual, p. 210. Scotland.

M. corniculatum (Ag.). — Frond very
stout, cartilaginous, erect, rigid, subdi-
chotomous, much branched above ; ulti-
mate ramuli subulate and spine-like;
navicidse slender, lanceolate, contained
in distinct secondarj' tubes. AD. p. 24 ;
KB. p. 118, pi. 28. f. 2. = Schizonema cor-
niculatum, Me. Adi'iatic Sea. Habit of
a small Fucus. 1-600".

M. penicillatwn (Chauv., Ag.). — ^Frond
thick and simple at the base, divided at
the apex into veiy numerous, penicdlate,
fastigiate, capillary branches. AD. p. 23.
= Schizonema penicillatum, Ghauvin ; M.
corniculatum /3, KA. p. 109. France.

M. pallidum (Ag.). — Frond pulvinate,
rigid, subcartilaginous, stout, much
branched; ramrdi suberect, abbreviated,
obtuse; naviculse minute, in lax series
within distinct secondai-y tubes. AD.
p. 23; KB. p. 118, pi. 28. f. 3. = SchiM-
nema pallidum, Me. Adriatic Sea.
(xrv. 39-42.) Tufts hemispherical,
dense ; colour pallid, verging on brown-
ish yeUow. 1-720" to 1-696".

M. chondroides (K.). — Frond minute,
cartilaginous, olive-coloured ; terminal
branches aggi-egated, clavate, obtuse,
here and there with hau--like spines;
series of navicidse and secondary tubes
very distinct, crowded; navicidffi mem-
branous, flaccid, minute. KB. p. 11^)
pi. 25. L 8. = Schizonema chondroides, Me.
Adriatic Sea. 1-1380" to 1-1320". Sper-
matia immci-sed, globose.

M. spincscens (K.).— Frond dwarfish,
setaceous, sliglitly dilated uuwards ; ter-
minal ramuli acute, spine-like ; series ot
naviculse and secondary tubes crowded,
very distinct; valves lanceolate. I^JJ-
p. 118, pi. 27. f. U. = Schizonema sjnnef-
cens. Me. Adriatic Sea. Naviculse in
front view oblonff, tnmcate. 1-9W) to
1-720". Spermatia internal, globose.

M. albican.1 (K.).— Frond setaceou.^
whitish or olive-gi-eeu ; brancJies ana
ramuli equal in thickness, fasciculatea
or whorlcd ; naviculse in distinct senc* ,

OP THE ACTlNISOEiE.

935

lanceolate; secondary tubes distinct. KB.
p. 118, pi. '27. f. 12. = Schizonema albicans,
Me. Adriatic Sea. 1-1200" to 1-1080".
Meueghini describes the valves as broadly
elliptic.

M. Berkeleyi (K.).— Frond tufted, didl

olive-brown ; filaments setaceous, rather
rigid, branched ; branches erect, attenu-
ated ; naviculee large ; valves eUiptic-
oblong, in very distinct secondary tubes.
KA. p. 106. Torquay. Naviculas in
front view parallelograniic. 1-1080".

FAMILY XIX.— ACTINISCE^.

Individuals silicious, furnished with radiating spines. Marine. The Acti-
nisceas bear little or no resemblance to the Diatomaceae, and ought to be ex-
cluded from them. M. de Brebisson thinks they would be more appropriately
placed near the Ai'cella, Eugiypha, or some allied genus. On the other hand,
Professor Bailey would refer them to the Polycystina.

Genus ACTIMSCTJS (Ehr.). — Frustules solid, star-like. Actiniscus differs
from Dictyocha and Mesocena in having a solid centre or body from which
rays, varying in number and form, diverge.

Actiniscus Sirius (E.). — Rays 6,
acute, winged at the base. EM. pi. 33.
15. f. 1. 1-1150". Alive, Norway; fossil,
America. The rays seem to arise from
the disc, and not from the margin.

A. Pentasterias (E.).— Rays 5, acute,
not (or but partially) exserted. EM.
pi. 35 a. 23. f. 1. 1-1150". Alive,
Norway ; fossil, Greece and America.

A. Tetrasterias (E.). — Rays 4, acute,
not (or but partially) exserted. EM.
pi. 18. f. 62. 1-1008". Vii-ginia. The
last two forms may be varieties of A.
Sirius.

A. ? Stella (E.). — SteUate, with 6,
marginal, obtuse rays or tQ&\h.= Dicty-

ocha, E. 1838. Fossil, Europe and
Afi'ica.

A. ? quinarius (E.). — Stellate, with 5,
marginal, obtuse rays or teeth. 1-3120".
Fossil. yEgina.

A. .? Bota (E.).— Wheel-like, with 10,
short, obtuse, spoke-like rays. 1-1920",
Oran.

A.? Discus (E.). — Disciform; centre
smooth ; rays 8, marginal, not exserted.
1-2304". Oran. According to Ehren-
berg, the last fom* species may belong to
Phytolitharia.

A. ? Lanceafius (E.), — Stellate, with
8 exserted, lanceolate rays, and some
central shorter ones. 1-240",

Genus DICTYOCHA (Ehr.),
forated ; foramina large.

* Fora7nina, or cells, two or three.

Dictyocha Ponticulus (E.). — Fms-
tides oblong, unarmed, transversely
divided into 2 cells. 1-432". Fossil.
Bermuda.

D. Quadratum (E.). — Subquadrate or
oblong, transversely divided into 2 cells,
a spine at each eucl. 1-480". Bermuda.
These two foims were fii'st obsei-ved and
figured by Professor Bailey.

D. Pons (E.). — Romidish, ^vith 2 cells
and 4 spines. 1-504". Oran.

D. triacantha (E.). — Triangular, with
spinous angles ; cells .3, unarmed. Mary-
land.

D. tripyla (E.). — Roundish, with 4
irregular spines; cells .3, unarmed.
1-492". Oran.

D. trifaimtra (E.). — Quadrate, 4-
spined; cells 3, dentate. Recent and
fossil, '(xv. 35.)

-Frustules free, spinous, reticulately per-

D. Abyssarum (E.). — Frustules trian-
gular, with 2 cells ; spines 3 ; 1 cell fur-
nished with an internal tooth. EB.
1854, p. 238. Atlantic.

2* Dia?nond-shaped or quadrate; 4-
spined; foramina 4 or more.

D. Fibula (E.). — Cells 4, unarmed.
1-1150" to 1-5G0". Recent and fossil.
(XV. 34.)

p. Epiodon (E.). — Resembles D.
Fibula, but the cells ai-e fm-nished Avith
a tooth. Recent and fossil.

D. abfiormts (E.).— Cells 5, unequal,
all marginal. 1-1080". Fossil.

D. Crux (E.). — Four unanned cells
round a central one. 1-G24". Fossil.

D. StaurodoH (E.). — Resembles D.
Crux; but each marginal cell bears a
tooth. 1-576", Fossil, Virginia.

D, mcsophthalma (E.). — Resembles
the two preceding species ; but each mar-

936

SVSTEMATIC mSTORY OF THE INFUSOHIA.

ginal cell has 2 opposite teeth, which
constrict it. 1-372 . Fossil. Sicily.

D. btp(ti-tita(E.). — Resembles D. Crux,
hut has 2 minute cells in the centre.
1-504". Fossil. Oran and Sicily.

D. superstnccta (E.). — Spines 4; cells
9, 4 marginal. 1-600". Fossil. Sicily.

3* Spines 6 (2 usually longm-).

_ D. hiternaria (E.). — Cells 6, all mar-
ginal, the 3 largest next each other.
1-432". Antarctic Ocean.

D. Hexathyra (E.). — Cells 6, 5 mai'-
ginal and 1 central. 1-864. Fossil.
Sicily.

D. Speculum (E.). — Six imarmed cells
round a central one. Common, both
recent and fossil. 1-860". (xn. 62, 63.)

D. gracilis (K.). — Resembles D. Spe-
culum ; but the spines ai'e elongated and
slender. Recent.

D. diommata (E.). — Six unarmed cells
round 2 central ones. 1-660". Fossil.
Virginia.

D. aculeata (E.). — Resembles D. Spe-
culum; but each marginal cell bears a
tooth. Common, both recent and fossil.

D. jBi?iociilus (E.). — Resembles D.
aculeata, but has 2 minute cells in the
centre. 1-444". Fossil, ^gina.

D. zibe7-a (E.). — Cells unanned, 7 mai-
ginal and 2 centi-al. 1-600". Maryland.

1). triommata (E.). — Cells imarmed,
6 marginal and 3 centi-al. 1-864".
Virginia.

D. Haliomma (E.). — Cells 10, 7 mar-
ginal and 3 central. 1-840". Oran.

D. hemis2}hcerica (E.). — Hemispherical,
6-spined ; 12 cells, in two circles, round
a central one ; the inferior aperture half
closed by 6 marginal teeth. 1-744".
Bermuda. D. triommata and D. diom-
mata resemble, in their tm'gid habit,
this species.

4* Spines more than 6.
D. septenaria (E.). — Spines 7; cells

unanned, 7 marginal and 1 central
1-864". Oran.

D. Ornamentum (E.). — Resembles D,
septenai-ia ; but each marginal cell bears
a tooth. 1-444". FossU. Sicily.

D. heptacanthus (^E.). — Spines 7 ; cells
13, 7 of them margmal. 1-552". FossiL
Greece.

D. octonaria (E.). — Habit of B. Orna-
mentum, with 8 spines; marginal cells
in-egular, fewer in niunber at that part
where the spines are increased, and with
a very large centi-al cell. 1-1152" ex-
clusive of spines. Perhaps a monsti-ous
variety of JD. Orname7itum.

D. Stauracanthus (E.). — Eight-spined ;
4 marginal, dentate cells, roimd a central
one. 1-648". Fossil. America.

D. polyactis (E.).— Rays 9 or 10; 10
marginal cells and 1 central, arranged in
a reticulate stellate fonn. In chalk-marL

5* Pentagonal ; angles acute, hut not
spinom.

D. elegans. — ^Pentagonal, perforated by
numerous small cells and 7 centi-al large
ones, of which one occupies the centre.
1-912". FossU. Caltanisetta, SicUy.

Doubtful or obscure Species.

D. Navicula (E.). — Cells 8 ; iigm-e ob-
long, obtuse, cylindi'ical, reticular-, with
a median septiun like a Navicula. Fossil
in chalk mail. Elu'enberg's figure re-
sembles D. Ponticulus.

D. ? splendens (E.). — Oblong, tabular,
with dentate apertm-es (cells), 13 in
number. If it be calcareous, it is similar
to Coniopelta.

D. anacantha (E.). — Resembles B.
Speculum, ■with obsolete spines. EB.
1854, p. 238. North America. Perhaps
a varietj'.

D. EreU (E.). — Resembles B. Specu-
lum, with small, subequal spines ; walls
of the cells thin. E. I. c. North America.
A doubtful species ; perhaps a variety.

Genus MESOCENA (E.). — Frustules free, each forming a ring, wliich is
mostly margined with spines or teeth. Mesoccna resembles Dictyocha, but is
destitute of its central reticulation.

Mksocena heptagona (E.). — Frustules
annular, with 7 external teeth. EM.
pi. 20. 1. f. 49. (XII. 71.) Actiuiscus ?,
E. Peru.

M. octogona (E.). — Frustules annular,
with 8 external teeth. Peru. As this
form diflers from 31. heptagona merely
by its additional tooth, it is probably a
varietj'.

M. hisoctonaiia (E.). — Frustules annu-
lar, with 8 external teeth, and as many
internal ones alternating with them.
= M. bioctonaria, KA. p. 142 ; EM.
pi. 35 A. 18. f 10. In Peruvian guano.

M. binonaria (E.).— Frustules annular,
with 9 external teeth, and as many
internal ones alternating with them.
EM. pi. 85 a. 18. f. 9. In Pcrunan

ADDENDA.

937

guano. Probably a variety of the pre-
ceding species.

M. Circulus (E.). — Cell circular j mar-
gin tuberculated. 1-576". EM. pi. 19.
f. 44. In Greek marl.

M. Diodon (E.). — In the form of a
smooth elliptic ring, armed at each end
with a small tooth. 1-396". EM.
pi. 33. 15. f. 18. Maryland.

M. elUptica (E.). — Frustules elliptic,
with 4 teeth. 1-624" to 1-456". EM.
pi. 20. 1. f. 44. Fossil. Zante.

M. triangula (E.). — Triangiilar, with
rough sides, and mucronate apices. EM.
pi. 22. f. 41. Fossil, chalk-marl.

M. .f Spongiolithis (E.). — An elliptic
ring, with 4 slight alternating swellings.
1-492".

GENEEA OF DOUBTFUL POSITION.

Genus EUCAMPIA (Ehr.). — Frustules hyaline, imperfectly silicious,
cuneate, without terminal puncta, united into a jointed, spiral filament.
Marine. This genus, placed by Ehrenberg and Kiitzing with the Desmidieae,
was judiciously removed by Professor Smith to the Diatomacese, with which,
it agrees in stinicture and in the colour of internal matter. Professor Smith,
however, considered it allied to Meridion ; in our opinion it is more nearly
related to the Biddulphiese, as shown by the absence of costae and terminal
puncta, its dotted valves, and their prominence in tlie front view.

EucAMPiA Zodiaciis (E.). — Frustules,
in front view, with the junction-margins
deeply sinuated, so as to form foramina
between the joints. E. Leb. Kreide-
thierchen, pi. 4. f. 8; SD. ii. p. 25, pi. 60.

f. 299. Em-ope. (n. 43.)

E. Britminica (S.). — Frustules cune-
ate, not excavated. SD. ii. p. 25, pi. 61.
f. 378. Europe. Stomach of Pectens.

Genus LITHODESMIUM (Ehr.).— Fnistules not cellulose, united into a
jointed, prismatic wand ; valve triangular, with one side plane, and the others
.undulated. Lithodesmium was placed with the Desmidieoe by Ehrenberg,
and with the Diatomacese by Kiitzing. Its non-cellulose structiu-e, however,
prevents our associating it with the Anguliferae, as proposed by the latter.

LrrHODESivircrM: undidatum (E.). —
Frustules smooth, very pellucid ; valves
with obtuse angles. E. Leb. Kreide-

thierchen, 1840, p. 75, pi. 4. f. 13.
Marine. Cushaven. (u. 41, 42.)

Genus MICEOTHECA (Ehr.).— Frustules simple, fi-ee, compressed, qua-
drate. Placed by Ehrenberg and Kiitzing with the DesmidieiB. We remove
it to the Diatomaceae, because of its marine habitat and golden colour • little
however, is known about it, and its nature is doubtful. '

■ ilicnoTHECA octoceras (E.). — Cell
quadrate, hyaline, with fom* spines at
each end J internal matter of a golden

colour. E Inf. p. 164, pi.
Marine. Kiel. (vm. 31.)

12. f. 10.

ADDENDA TO THE DIATOMACEiE.

Cyclotella pertenms (B.). — Valves
minute, slightly convex; surface minutely

cellulate or punctate ; cells radiant. B.
on Mic. Foi-ms in the Sea of Kamtsch'atka!

The following coiTcctions and addition to Cyclotella are adopted from Prof.><i«!ni.
Amotfs paper in JMS. viii. p. 244. "i^^ssoi

For C. operculata (p. 811), substitute : —
C. operculata (Ag., Kutz.). — Ends of operculata, E. Fresh water. Euroue
trustules undulate ; valves with smooth [Professor Araott regards Stonham
centre, and close, short marginal striaj. pyxis Niagar(e,im&fQr\mm S. Equptiams
KB. p 50, pi. 1. f. 1. = FnMia and as identical with 0. AstrmaA '^-^^
f^ymbclla operculata, Ag. ; Pyxidicula ^

938

SYSTEMATIC HISTOEY OP Tin? INFCSOBIA.

For 0. rectangula (p. 811), substitute :-

C. Mmeghiniana (If.). — Front view
rectangular ; valves minute, with smooth
centi'e and rather coarse marginal sti'iaa.

For 0. Dallasiana (p,

C. Dallasiana (Sm.). — Frustxdes with
flat ends ; valves with bullate-rugose
centre and coarse marginal sti-iae. SD.
ii. ^. 87.= a radiata, Bri. TMS. viii.
pi. 6. f. 11. Brackish water. Europe,
America.

0. minuttda (K.). — Fi'ustules with
flat ends ; valves with radiating dots or
striae at centre. KB. pi. 2. f. 3. = C.

KB. p. 50, pi. 30. f. 68. C. rectangula,
Rab D. p. 11. Europe. Fresh water.

813), substitute : —

operculata, SD. i. p. 28, pi. 5. f. 48. Eu-
rope. (Kiitzing, however, describes hia
C. minutula as iindulate.)

C. Kiitzingiana (Th.). — '■ Ends of frus-
tules imdulate; valves with convex,
smooth centre, and long, coarse mar-
ginal sti-ise. SD. i. p. 27, pi. 5. f. 47.
Brackish water. Europe.

CoccoNEis Finnica. — On careful ex-
amination of several fossil deposits said
by Ehrenberg to contain this species, we
can find no form resembHng the figures in
the ' Microgeologie,' excepting Navicula
elliptica.

EuPODiscus ? Peruviamis (Kitton,
MS.). — Valve orbicular, finely punc-
tated, with two small, roundish sub-
marginal processes, and a submai'ginal
series of close minute apicidi. Peruvian
and Calif ornian guanos. We regard the
genus of this Diatom as doubtful. The
valve has some resemblance to an Au-
liscus 5 but the puncta are not in flexuose
lines. The processes, as seen in front
view, are short and subtruncate, and
the circle of apiculi which connects
them shows an afiinity to Cerataulus.
The processes of the one valve alternate
with those of the other, and are often
visible at the same time.

E. ? Grevillii (Ralfs, n. sp.). — Disc ob-
scurely punctate, with (3) clavate inti'a-
marguial processes, and a circlet of spines
between the processes and the centre.
Monterey. Dr. GreviUe. The processes,
which are rather distant from the mar-
gin, resemble those of Aulacodiscus, and
the circlet of spines that of Sj'stephania ;
but the absence of connecting lines re-
moves it from the former, and the pre-
sence of processes from the latter genus.

I'odosiha ? compressa (West). — Frus-
tule geminate, free ? ; polar always shorter
than equatorial diameter ; valves elliptic,
obscurely punctate ; puncta scattered ;
angulum smooth. Creswell Sands,
Druridge Bay, Yarmouth Sands. West,
TMS. viii. p. 150, pi. 7. f. 11. rrai. 34.)
This form occurs plentifully on tlie sandsj
the frustules always occur in pairs. Tlie
absence of stipes or any attachment, the
compressed valves, and the want of a

thickened umbilicus, render its position
in the present genus doubtful.

Epithemia (Uunotia, E.) Sancti An-
tonii = E. Beatorum = Denticula ? lauta
(Bail.). — This species has been foimd
by Mr. Kitton in the Monterey-stone and
Richmond deposits; in the latter they
occur in filaments of 6 and 7 frustules,
clearly showing that they are improperly
laced in the present genus, and are pro-
ably allied to Denticida.
Navicula hullata (Norman, n. sp.).—
"Elliptical, extremities slightly pro-
duced; strise in a marginal and two
central bands ; marginal band of un-
equal width ; the blank spaces between
the gi'anules studded with a line of cir-
cular bosses; sti'iae moniliform, 14 in
001". Stomachs of Ascidians, Shark
Bay, Austi-alia " (Norman in litt.).

N. Sillimanorum (E.). — Inflated at the
centre ; apices produced, roimded, and
consti'icted ; strise radiant, not reaching
the median line. EM. pi. 2. 2. f. 13.=
Pinnularia Sillimanorum, EA. p. 133.
New York deposit. This species re-
sembles Gomphonema gcminattim, but is
distinguished b}' its less conspicuous
strise and equal ends ; the figure lu EM.
represents only a fragment.

N. Cyprimts (E., K.).— Small; valves
oblong, slightly contracted into the very
broad obtuse ends ; central nodule ob-
long ; strite evident. KB. p. 90, pi.
lQb.=Pinmdaria Cyprinus, EA. pi. 1. U-
f. 7. Chili.

N. Eemickcana (Rab.). — Resembles
N. cmpidata and N. rostrafa ; but the
capitate ends are more prolonged, and
the striai ai-e only 30 in -001". KaO'
Algen Sachs. No. 802. Dresden^

Aulacodiscus SoUitdanus (Nonuan,
MS.).— "Disc Irn-go, hyaline, with six
conspicuous processes, distant from m&T-

ADDENDA.

939

gin; gi-aniiles radiating, not reacMug
the centre, 9 in 'OOl" ; smooth round the
base of the processes. Deposit from
Nottingham, oelow Maiyland, which
seems to be identical with the Bermuda
tripoli, and contains several forms pecu-
liar to that deposit " (Norman in littX

A. Barhadensis (Ralfs, n.s.). — Disc
large, hyaline, very minutely punctated,
with small imibilicus, (3) intramarginal
roimdish processes, and faint connecting
lines. Barbadoes deposit. Distinguished
by its very obscui'e pimcta. The rather
large processes, when nearly out of focus,
appear to have a central dot.

Teiceeatixjm crenatum (Kitton, MS.),
— Sides roimded, mai'gin crenate; gra-
nules radiating from the pseixdo-nodule,
distinct at the maa'gin, but less con-
spicuous as they approach the centre. =
jDiscoplea undulata, EM. pi. 33. 18. f. 3.
Nottingham deposit. The presence of
the pseudo-nodule shows it to be an ally
of T. Brightioellii ; but the neai-ly orbicu-
lar outline and crenate margin distin-
guish it from that species. The fi'ag-

nient figui-ed by Ehi'enberg we have no
doubt is identical with this form.

T. Buwerbanldana (Ralfs). — Valves
with two concentric circles, radiating
lines between the ch'cles, distinctly punc-
tated angles, and blank or indistinctly
pimctated centre. Barbadoes deposit.
The large valve has nearly straight sides,
and obtuse angles; it is divided into
three parts by two suture-like cu-cles,
the outer one with a border of bead-like
dots, which are most evident nearest the
sides ; the liaes between the cii'cles are
abbreviated, only one on each side reach-
ing the inner circle.

Cbaspedodiscus Barhadeiisis (Ralfs,
n. s.). — Border very broad, its diameter
greater than that of the centi'e ; cellules
of centre very minute, those of border
larger and arranged in cmwed, decussat-
ing lines. Bai'badoes deposit. Disc
about the size of C. Coscinodiscus, but
with a much smaller centre. It differs
from both that species and C. microdiscus
in having the cellules of the border in
cm'ved series.

Substitute the following descriptions for the notices of Cbaspedodiscus SteUa
and C. Frmiklini at p. 832 : —

C? Stella(Ei.'). — Valves hemispherical,
with a very broad, smooth, obsoletely
radiated limb, and a small, finely cellu-
lose centre, having an irregular margin ;
rays 12, irregular. EB. 1855, p. 238 ; E
M. pi. 35 B. B. 4. f. 11. North America.
On account of its rays, this foi-m may be
the type of a new genus ; but they were
distinct only in a smgle specimen, whUst
in the greater number scarcely a trace of

To C. semiplanus (Bri.), add : —

This Diatom, which is not imcommon
in the Barbadoes deposit, is no doubt
incoiTectly placed in tliis genus. In our
opinion it is closely allied to Astero-
lampra, and should either be united to
that genus, or a new genus formed to

To C. marginatus (Bri.), add : —

We consider that this Diatom also is
wrongly referred to Craspedodiscus, and,
notwithstanding its large punctated
centre, is really more allied to Astero-
lampra, — its marginal compartments,
however, being extremely minute. In
the Barbadoes deposit we find discs
sometimes j^as in Asterolanipra) without
any umbilical cellidos, and sometimes
with a large cellulose centre, and these

them could be detected. It approaches
to the characters of Synibolophora.

C. FranMini (E.). — Disc tm-gid, with
a deciduous, broad, hyaline, smooth
marginal limb, and a very fine punctated
(yellowish) centre, having an irregular
margin ; centre and limb of nearly the
same diameter. ERBA. 1853, p.' 526;
Eai. pi. 35 A._ 23. f. 6. Assistance Bay.
Akin to Coscinodiscus disciger.

include this and other allied discs asso-
ciated together in the deposit. Mr.
Bi-ightwell's specimen must have been
imperfect, since we find the radiating
lines invariably correspond in nimiber
with the marginal compartments.

extremes so connected by intermediate
states as to make it doubtful whether
the cellulose centre is available even
as a specific distinction. We hope Dr.
Greville, who has paid much attention
to these forms, wiU soon publish a
monograph of them in continuation of
his former admirable paper on Astero-
lanipra.

I

940

SYSTEMATIC HISTOET OF TUB INFtTSOKIA.

For OnASPEDODisctJS coronatus, substitute the following : —

Genus BRIGHTWELLIA (Ealfs, n. g.).— Disc Avith a large granulated
centre, separated from a broad punctated Umb by a circlet of oblong ceUules.

"We bave constituted this genus to receive a beautiful Diatom placed by Mr.
BrightweU in Craspedodiscus, but which differs so greatly from other Diatoms
that we believe it should form the type of a new one, which, with much plea-
sure, we dedicate to the author of the excellent monographs of Triceratium
and the Chsetocereas.

Brightwellia coronata (Bri., Ralfs).
— Central portion of valve with an
irregular blank umbilicus and radiating
series of granides, which are closer and
in curved lines neai* the circlet of cellules.
= Craspedodiscus coronatus, Bri JMS.
viii. p. 95, pi. 5. f. 6. Barbadoes deposit.
This species is very variable in size. In
a diy state it is of a purplish or brown
colour, but in balsam hyaline; the centre
has the gi'anules irregular near the um-

bilicus, and interrupted by blank ravs;
but near the circlet of cellules they be-
come more regular, and form curved,
moniliform lines. The broad limb is
usually brownish when dry, and marked
by numerous radiating lines, similar to
those of Coscinodiscus concinmis, and
have in the intervals extremely minute
obliquely arranged granules. The radi-
ating lines, although conspicuous in the
dry state, nearly disappear in balsam.

After CYMATOPLEtTRA Ocuni (p. 793), insert : —

C. imdtifasdata (Kiitz.). — Valves C. thermalis (Kiitz.). — Slightly pan-
linear, with acutely cuneate apices, and duriform, otherwise as in C. muUifasciatu.
very fine transverse striae. = Surirella =SurireUa thermalis, KB. p. 60, pi. 3.
midtifasciata, KB. p. 60, pi. 3. f. 47. f. 46. Em-ope.
Europe.

Genus CYLINDEOTHECA (Eab.).— Frustules exactly cylindrical, with
percurrent spires, and imbedded in an amorphous, gelatinous mucus.

CYirNDB,0THECA(?ers<eji6er£rm"(Rab.). (rarely one or three) spires. Eab. Algen
— ^Frustules lanceolate, acute, with two Sachsens, No. 801. Dresden.

Note. — Mr. Ealfs originally proposed to introduce a family Synedrea;. as
mentioned in p. 758, but subsequently transferred the genera to the family
Siuirelleae, the genera in which he distributes thus : —

* Frustules hacillar ; valves Jceeled — Fitzschte^.
Genera. Nitzschia, Ceratoneis, Amphipleura, Bacillaria, and Homoeocladia.

2* Frustules hacillar; valves scarcely broader than front view, not Icedcd—

STITEDREig.

Genera. Synedra, Dcsmogonium, Dimcregramma, and Staurosira.
3* Frustules not hacillar; valves mostly hroader than front vim, mt keeled-'

SuMRELLEiE.

Genera. Ehaphoneis, Tryblionella, Cymatopleura, Sui-irella, Campylodiscus,
and Calodiscus.

INDEX

TO

THE FIGUEES ILLUSTRATING THE DIATOMACE^,

Plate Page

AcHNANTHES brevipes x. 199-202 873

exilis vn. 44 874

longipes vn. 42 873

subsessilis vn. 43 874

AcHNANTHiDiTJM coarctatum vn. 41 873

delicatiilum xiv. 16 872

microcepbalum xrv. 15 872

trinode vni. 9 872

AcTiNOCYCLTJS Ralfsii v. 84 835

AcTiNOGONiUM septenarium ..... v. 55 813

AcTiNOPTYCHTjs ? hexaptetus xi. 31 840

Jupiter XI. 28 840

senarius rx. 132 839

undulatiis v. 88 . 839

AMPHiCAsrPA mirabilis iv. 5 765

Amphipentas alternans xi. 32 858

flexuosa vi. 22 a, 6 858

Amphipleura inflexa rv. 31 783

pellucida iv. 30 ; ix. 140 j xni. 1 . . 783

rigida xm. 2 783

Amphipboha alata xm. 5^ 6, 7 921

constricta xn. 1 922

Amphitbtbas antediluviana xi. 21, 22 858

omata viii. 16 858

Amphoea angidaris vn. 50 881

cymbifera vn. 54 882

fracilis xn. 26 884

yalina vn. 58 884

litoralia vu. 52 881

Lybica xn. 38 883

marina vn. 59 884

membranacea vn. 51 ; 881

monilifera vn. 79 882

naviculai'is xii. 37 884

ovalis vn. 56 ; ix. 153 883

spectabilis vn. 57 884

Anaulus scalaris vni. 37 859

Abachnoidiscus oniatus xv. 18-21 842

AsTEEiONELLA formosa IV. 17 779

llalfsii IV. 18 779

Astebolampra Marylandica xi, 33 836

AsTEBOMPHALus Arachiie v. 66 837

Brookeii v, 79 837

942

INDEX TO TnE FIGtmES OP DIATOMACEai,

Plate Page

AsTEROMPHALTJS centraster viii. 14 838

Darwinii v. 86 837

elegans v. 87 837

heptactis vm. 21 838

Hookerii xi. 34 836

Attheya decora vm. 35 863

AuLACODisctrs Beeveriae vi. 5 844

Kittoni vm. 24 844

Oreganus vi. 4 845

pulcher vm. 28 845

AuLiscus pruinosus vi. 1 845

sculptua VT. 3 845

Bacillahia cursoria rv. 20 , 784

paradoxa rv. 19 ; ix, 166, 167 784

Bacteriastbum furcatum vi. 26 863

Wallichii vi. 27 863

Behkeleya Adriatica xiv. 34, 35 926

BiBLARiuM Castellum (EM. 33. 2. 1) iv. 44 806

BiDDULPmA Indica vi. 12 849

Macdonaldii vm. 23 849

obtusa xm. 30-32 848

pulchella u. 46-50 848

Tuomeyi vi. 10 848

Caeodisctts superbus vm. 50 802

Campylodiscus Clypeus xvii. 516-518 801

Ebrenbergii xu. 12, 13, 22, 23 802

flexuosa xn. 11 802

Hibemious rv. 38 799

parvulus xv. 22, 23 801

spii-alis rv.39 802

CEEATATTLtrs Isevis vr. 7 847

turgidiis vr. 8 846

Cebatoneis Closterium xir. 59 783

longissima rv. 23 783

spii-alis xm. 9 783

Ch^tocebos boreale vr. 25 861

Wighaniiii vr. 24 862

Cladogbamma CaUfornicum vm. 11 814

CLrMACosPHENrA moniligera xr. 45, 46 772

CoccoNErs Americana xn. 48 871

distans vrr. 38 870

excentrica to. 40 871

Finnica xri. 41 870

Oceanica xrr. 42 868

Placentula vrr. 36 868

pseudo-marginata vrr. 39 871

Scutellum rx. 162, 163 869

transversalis vrr. 37 869

CoccorfBMA Boeckii vrr. 48 878

Cistula X. 196-198 878

cymbifomie xrr. 46 878

gibbum xrrr. 10 878

lanceolatum x. 194, 195 877

parvum vrr. 47 8< 8

CoLr.ETONEMA Auipbioxys xrr. 55-57 927

eximium "^tu. 43 926

neglectum vni. 47 926

CoscrNODrscus concinnus v. 89 828

cxcavatus ATir. 26 829

nitidus vnr. 18 831

ovalis V. 78 831

INDEX TO THE FiaUBES OF DIATOMACEiE.

d43

Plate Pago

CosciNODiscus radiatus xi. 39, 40 830

stellaiis v. 83 828

Craspedodiscits Coscinodiscus .... v. 80 832

elegans xi. 38 832

Ctclotella Atlantica xv. 3 812

atmospherica xv. 1, 2 812

opercidata v. 53 811

punctata viii. 13 813

rectangula v. 54 811

Scotica XIV. 17 811

Sinensis xv. 4 812

Cymatopleuba elliptica ix. 149 5 xvi. 7, 8 793

Solea K. 155; XVI. 9 793

Cymbella Ajcus VII. 78 875

cuspidata vn. 45 876

Ekrenbergii vn. 46; rx. 154 875

gasti-oides xw. 18-20 877

Helvetica xiv. 24-28 876

Cymbosira Agardhii xiv. 14 875

Denticula elegans xiii. 4 773

Desmogontum: Guianense xv. 13 790

Dladesmis confervacea xiv. 32, 33 923

Iffivis xn.40 923

DiATOMA Ehrenbergii iv. 15 779

elongatum iv. 14; ix. 169 779

hyalmnm iv. 16 778

mesodon ix. 170 778

vulgare iv. 13 ; ix. 168 778

DiATOMELLA Balfouriana iv. 51 810

DiCEXELA. ulvoides xv. 31 925

DiCLADiA Capreolus vr. 28 863

DiCTYOCHA Fibula xv. 34 935

Speculum xn. 62, 63 936

tiifenestra xv. 35 935

DiCTYOLAMPRA Stella V. 58 813

DraEBEGBASiMA distans iv. 34 790

Hamsonii vni. 6 790

nanum iv. 33 790

pinnatum Aon. 4 79 1

sinuatum iv. 12 790

Tabellaria iv. 35 790

DiscosiRA sulcata v. 68 822

DisiPHONiA australis = Diatomella

Balfomiana iv. 52 810

DoNKiNiA carinata vm. 49 921

Encyonema prostratum vn. 49 ; xiv. 22 879

Endictya oceanica v. 70 831

Epithemia alpestris xm. 8 760

Armis XV. 11 759

gibba xn. 27 759

Eranulata. , rx. 165 761

ibrile xn. 24, 25 761

longicomis xv. 6-9 760

Musculus xin. 18 760

Porcellus xiii. 12 761

turgida IV. 1 ; IX. 156-161 ; xi. 1-8 761

Westermanni iv. 2 ; ix. * 157 760

Eucampia Zodiacus 11. 43 937

EuNOTiA pontaglyphis iv. 3 764

quinaria xn. 39 764

triodon IV. 4 ; rx. 164 763

944

INDEX TO THE EIGTTRES OF DIATOMACEiE.

Plate Page

EuNOTOGBAMMA tn- qmnque- sep-

tem- et novemloculata .... vm. 30 860

EuoDiA gibba vnr. 22 . . '.852

Ettpleuma ocellata vni. 2 809

pulchella vm. 8 809

EupODisctrs Argvis vi. 2 ; xi. 41, 42 843

I^agilahia capucina ix. 173-176 ; xiv. 1, 2 . . 776

virescena rx. 176 777

Gephybia incurrata v. 50 809

media v. 49 809

Gomphogbamma rupestre iv. 46 806

GoMPHONEMA acuminatum xm. 23 887

apiculatum xn. 28, 53 889

constrictum x. 187-190 887

coronatum xiv. 36 887

cm-vatum xi. 9-12 ; xin. 11 888

geminatum vii. 60 887

minutissimum xi. 17 891

Vibrio xu. 35 890

GoNiOTHEcniM crenatum xv. 10 864

Odontella n. 29 864

Gbajvimatophoba gibba xi. 48, 49 808

liamidifera xin. 22 808

marina iv. 47 j xi. 52, 53 808

serpentina rv. 48 808

Gbammonbma Jui'gensii xv. 24, 25 778

Haliontx undenarius v. 82 833

Heliopelta Metii xi. 35 841

Hemiaulus antarcticus xi. 54 851

Hemidiscus cimeiformis vi. 14 853

Hebcotheca mammillaris vn. 35 867

Hetebostephania Rothii v. 85 833

HiMANTiDiTTM Guianense xii. 54 766

monodon xii. 29 ; xv. 16, 17 765

Papilio xn. 45. 49-62 766

pectinale iv. 6 ; ix. 171-176 765

Soleirolii xiv. 13 765

HoMCEOCLADiA filifoi'mis rv. 25 785

Martiana iv. 24; xiv. 47-49 784

moniliformis xiv. 45, 46 785

pumila XIV. 37, 38 785

sigmoidea rv. 26 785

Hyalodiscus subtilis v. 60 815

Hyalosiba delicatula rv. 42 804

obtusangula xrv. 29 804

rectangula xiv. 23 804

Hydboseba compresaa vi. 8 852

triquetra vi. 13 852

IsTHMA enervia x. 183 851

LiCMOPHOBA divisa xm. 16 772

flabellata iv. 9; x. 191-193 771

LioSTEPHANiA magnlfica v. 56 813

Rotula V. 57 813

LrPABOGYBA dentroteres v. 72 8^o

LiTHODESMiuM undulatum 11. 41, 42 937

Lysicyclia Vogelii vm. 39 815

Mastogloia Danseii xv. 30

Mastogonia Actinoptyclius v. 59 814

Melosira arenaria rai- 17 "ly

coarctata xi. 20 & 27 818

Dickieii XV. 29 820

INDEX TO THE PIGTOES OF DTATOMACEiE.

945

Plate Pago

Melosiha Horoloo;iiim v. 62 819

Italica XI. 29 J XV. 33 818

Juvgeusii v. 63 817

mouilifomiis v. 71 817

Nageli XV. 26, 27 822

nunimiiloides v. 64 : xi. 14 816

orichalcea v. 65 ; vin. 33 818

Roseana v. 67 818

subflexilis v. 63 817

sulcata IX. 131; XI. 26 819

varians iv. 32; ix. *131; xv. 32 817

Meridion circulare ix. 177-179 ; xiit. 21 .. 767

INLesocena heptagona xn. 71 936

jMichomega Agardhii x. 208 933

bombycinum xiv. 43,44 .' 933

paUidiim xiv. 39-42 934

IMiCROTHECA octoceras viii. 31 937

Navicttla affinis xn. 32 902

Amphii'hynchus xu. 6 901

Amphisbsena vn. 72 ; rx. 141 899

borealis vn. 74 907

cardinalis xn. 72 896

CliUensis xn. 33 907

Clutliensis vn. 73 •. . 909

cuspidata xn. 5 905

didyma ra. 61 ; xv. 12 893

Esox xn. 43 896

Hennedyi vn. 69 898

HitcbcocMi vn. 62 894

latissima vn. 70 903

major vn. 65 ; xn. 16, 31 ; xvi. 1-6 896

maxima vn. 75 909

nodosa ix. 143 894

producta vn. 66 902

rhombica vn. 71 903

rhyncbocephala vn. 68 900

Tabellai-ia xn. 21 896

tseniata xv. 15 900

tumida vn. 55 910

viridis ix. 133-136 907

Nitzschia BriglitweUii vra. 7 780

scalaris iv. 22 781

Sigma IV. 21 781

sigmoidea ix. 148 781

? valens xn. 44 782

Odontidium hyemale ix. 172; xin. 24, 25 ... . 775

Odontodiscus eccenti'iciis v. 90 . . . 832

. Omphalopelta areolata vni. 15 841

Omphalotheca bispida vni. 44 865

Onccsphenia ? Caroathica vni. 1 768

Pehipteha chlamidophora vni. 25 865

tetracladia vi. 30 865

Peristephania Eutycha v. 73 824

Perithyra denaria viii. 19 842

Plagiogramma pulchellum iv. 32 774

Pleurodesmium Br(5bissonii vi. 23 860

Pleurosigma aciiminatum rx. 146 919

Balticum vin. 33 ; ix. 144 917

Fasciola xn. 60, 61 91G

fonnosum viii. 32 917

Hippocampus ix. 145 919

3 r

946

INDEX TO THE PIGTJEES OF DIATOMAOEiE.

Plate Paco

Pleuhosiphonia afRnis vm. 45 915

PoDOCYSTis Adriatica iv. 10 772

PoDODiscus Jamaicensis xiii. 28 815

PoDosiBA ? compressa vin. 34 815

liomioides n. 45 815

PoDOsrRA Montagnei v. 61 815

PoDOSPHENiA cuneata xiii. 136 769

Ehrenbergii iv. 7 ; xm. 14 769

gracilis x. 186 769

hyalina xm. 13 769

POHPETA quadi'iceps vi. 6 850

Pyxidicula Adriatica xiii. 83 825

globata XVII. 506-509 825

Rhabdonema Adriaticiun xni. 27 805

arcuatiim ix. 180-182 j x.203, 204. . 804

Crozieri iv. 43 805

minutum rv. 41 804

mirificum vni. 12 805

Rhaphoneis Amphiceros xts^. 21 791

Rhipidophoiia Meneghiniana .... xm. 19 771

Nubecula xm. 17 770

paradoxa iv. 8 770

tenella xm. 15 770

RfflzoNOTiA Melo vm. 41 886

RrazosoLENiA Calyptra vn. 31 866

robusta vm. 42 866

setigera vn. 33 865

stylifoimis vn. 32 865

ScEPTBONEis Caduceus rv. 11 772

ScHizoNEMA Dillwynii vm. 40 928

Grevillii vm. 38 928

Hoffinannii x. 207 928

Sphenella angustata xiv. 30 886

obtusata xiv. 31 886

Sphenosira Catena xi. 30 892

SxATmoGBAMMA Persicum vm. 36 915

Stauboneis acuta vn. 76 914

Crucicula vn. 64 912

dilatata xn. 16 911

Isostauron xn. 73 914

Legumen vn. 67 911

obliqua vn. 63 911

Pboenicenteron ix. 139; xn. 17, 18 .... 913

pbyUodes xn. 7-9 912

platyatoma ix. 142 912

pulchella vn. 77 914

scalaris xn. 10, 14, 80 915

Staueosiba constraens xv. 5 791

Stephanodiscus ./Egyptiacus v. 69 824

STEPHiVNOGOiaA polygoiia v. 77 814

Stephanopyxis rerox v. 75 826

TuiTis V. 74 826

Stigmaphoba rostrata vm. 48 923

Stbiatella unipunctata rv. 40 j . • • 803

Stylobiblium Clj'peus rv. 45 805

Sublrella biseriata xvi. 20-26 ^9*

constricta xiii. 3

Craticula xn. 19, 20

Gemiua xn. 2-4 <^

spleudida rx. 150-152 ^.^o

fitriatula rx. 137, 138 <^

INDEX TO THE FIGiniES OF DIATOM ACEiE.

947

Plate Pago

Symbolophoha Trinitatis xi. 36 833

Stoctclia Salpa ra. 53; x. 206 879

Stnedba Arciis iv. 27 789

capitata iv. 29; x. 185* 788

fiiltrens xra. 20 789

Gallionii xii. 34, 30 788

lunaris x. 185 785

piilcheUa n^ 28 786

robusta vin. 3 789

suttilis IX. 147 786

Ulna X. 184 788

SYEiNGiDraM Americanum vn. 34 866

bicorne vm. 20 866

Systeph.\nia Corona v. 81 832

Tabellaria flocculosa xm. 29 807

ventricosa xm. 26 807

Tebpsinoe musica xi. 47 859

Tessella interrupta Yin. 5 804

Tetbacyclus lacustris xi. 24, 25 ; vm. 10 .... 806

Toxonidea undulata vm. 46 920

Tbicebatittm altemans vi. 21 854

casteUatuni vm. 29 854

contortiun vi. 18 853

exiguuni vi. 16 857

Faviis XI. 4.3, 44 855

punctatum vi. 20 856

Solenoceros vi. 15 856

spinosum vi. 19 853

trisiilcum vm. 27 854

venosum vi. 17 854

Tbyblionella acuminata iv. 37 792

gracilis rv. 36 792

Xanthiopyxis oblonga v. 76 827

Zygocebos Siu'irella xi. 50, 51 850

Mobiliensia vi. 11 850

3p 3

949

DESCEIPTION OF THE ENGRAVINGS.

PLATE I. (Desmids).

Figures 1 to 14. Cosmarium margaritiferum, &c., under different stages of develop-
ment: 1,2. Frond, enclosing "vesicles" filled with moving granules; 3. Supposed early state
of moving granules ; 4. Early stage of self-flssion ; 5. Fission-products escaping the enclosing
wall of parent cell ; 6. Separation completed ; 7. Sporangium still connected with parent
frond ; 8. Same with mammilLiform spines ; 9. Sporangium further developed ; 10, 11.
Supposed mature sporangia ; 12. Same, broken and empty ; 13, 14. Yovmg supposed
products of sporangial contents : all after Mrs. Thomas, TM. 1855. [We are disposed to
think that one or two other species besides Cosmarium margaritiferum are here confounded.
4, we suggest, may possibly be C. ceelatum or C. cristatum, showing nascent segments ;
7, C. Broomei, the empty frond to the right showing a segment not yet fully developed ;
8 and 9 appear to us as probably more likely to represent the conjugated state and sporan-
gium of C. bioculatum, of which figs. 10, 11, 12, may represent the ultimately extruded
inner membrane, while figs. 13 and 14 may ti'uly be the young fronds developed from their
contents, and which have not yet commenced vegetative self-di^asion.] 15-17. Spha?ro-
zosma vertebratum (Ralfs): 15. A portion of a filament seen in f. v. X200; 16. tr. v.
X 400 ; 17. 8. V. X400. 18, 19. Micrasterias papiUifera (Breb.) : 18. f. v. X 100 ; 19. Spo-
rangium x200. 20. M. rotata (Ealfs), f. v. xlOO. 21. M. radiosa (Ag.), f. v. xlOO.
22. M. Crux-Melitensis (Ealfs), f. v. X 100. 23-25. Euastrum Didelta (Ealfs): 23. f. v.
with endoohrome ; 24. e. f. in f. v. ; 25. tr. v. : all x200. 26. E. rosti-atum (Ealfs), f. v.
X400. 27, 28. Xanthidium armatum (Breb.) : 27. f. v. ; 28. s. v. : both x200. 29, 30.
Ai'throdesmus octocornis (Ehr.): 29. var. /3, f. v. ; 30. var. a, f. v. : both x400. 31-34.
Staurastrum cuspidatum (Br6b.) : 31. f. v. ; 32, showing the nascent segments ; 33. tr. v. ;
34. e. v.: all x400. 35,36. Ankistrodesmus falcatus (Ealfs), x400. 37-39. Sceno-
desmus obtusus (Meyen), after Niigeli, showing segmentation of the cell-contents, x300.
40-42. S. caudatus, after NageU, x300. 43. Same, segmentation of cell-contents, x400.
44, 45. A few marginal cells of " Pediastrum Selena3a (Kg.)"=:P. pertusum (?), after
Niigeli, X300. 46-48. P. (Anomopedium) integrum (Nag.): 46. Xl50; 47. x400;
48. s. V. X400. 49-51. Coelastrum sphajricum (Niig.) : 49. x200; 50, 51. X300.
52. Pediastrum Ehrenbergii (Braun), after Braun, x4d0. 53. P. Selensea (Kg.) [non
Ealfs, = P. pertusima], after Niigeli, Xl50. 54, 55. Coelastrum cubicum (Nag.), after
Nageli, x300. 56-58. Sorastrum spiiiidosum (Nag.): 56. x300 ; 57, 58. xBOO.
59-61. Pediastrum Boryanum, var. brevicornis, after Braun : 59. Two marginal cells
one empty, the other discharging the original inner membrane closely investing the micro-
gonidia; 60. The same halt an hour afterwards, considerably dilated, tlie niicrofonidia
each with a pointed hyaline beak, and at first slowly moving ; 61. Microgonidia,
eventually emitted, swimming freely: all x300. 62. P. granuLatum (Kg.). 63. Brood
of macrogonidia emerged from shell of old frond, X400. 64. A few marginal cells of an
old frond, some empty, the cell-contents of others undergoing previous segmentation, and
one discharging the inner membrane investing the brood of macrogonidia (Braun), x400.
65. Same as 63, seen from the edge, x400. 66. Same, seen in f. v., tlie cells now sUghtly
emarginate, x400. 67. Same, four hours after the macrogonidia have ceased to move tlie
marginal cells now drawn out into horns, but not yet having assumed tlieir ]>roper form
and all exhibiting spaces between, not yet having become closely applied to each other'
X 400. 68, 69. P. Boryanum : microgonidia treated with tinctiu'o of iodine and sul-
phuric acid, showing the vibratile cilia, the slightly retracted contents, and a nucleus
X500. (Figs. G3-6y after Braun.)

PLATE II. (Desmids).

Figures 1 &, 5. Closterium Leibleinii (Kg.), x200: 1. A frond filled with endochrome
and an empty one lying across it (the latter shows tlie central suture) ; 5. S]iorangi\im lying
between the conjugated, and now empty fronds. 2 & 6. Closteri\nn striohitum (Ehr.)
XlOO: 2. A frond witli cndoclirome, sliowing the longitudinal lillcta and flie single row of
large granules; 6. Two empty conjugated fronds, sliowing the stritc and the orbicular

950

DESCRIPTION OP TILE ENGEAVHTGS,

Bporangium lying between them, enveloped in mucus. 3. Staiu-astrum (Desmidium, Elir.)
euatophanum, e. v. 4. Spii-otajnia condensata (Br6b.), x200: the frond is seen with its
spiral band of endoclvrome, and surrounded by a mucous hyaline sheatli. 7. iStaurastrum
(Desmidium, E.) senariiun. 8 & H. Docidium Ehrcnbergii (Ealfs), x 100 : 8. Conjugating
fronds, the sporangium in an early stage of development ; 11 shows the process of develop-
ment by fission, the young segments partially grown. 9. Docidium clavatum (Kg.), x 100,
10&30. Euastrum jDectinatum (Br6b.), x200: 10. A single frond; 30. Tlie spinouB
sporangium, the empty segments adjacent. 12, 13. Tetmemorus Brebissonii (Ealfs), x
200: 12. f. V. ; 13. s. v. 14, 15. Penium margaritaceum (Br6b.), x200: 14. f v. var. a;
15. s. V. of two empty fi-onds, var. y, the sporangium between them. 16, 17. Staurastrum
alternans (Breb.), x400: 16. f. v.; 17. e. v. 18 & 23. Xanthidium cristatum (Br6b.),
X400: 18. f. v.; 23. e. v. 19 & 36. Scenodesmus quadi-icauda (Ealfs), x400: 19. A
j'rond of two cells ; 36. one of foiu" cells. 20, 21, 24, 25 & 31. Staui-astrum polymor-
phum (Breb.), x400; 20. e. v. (of five-rayed var.); 21&31. f.v. ; 24. A frond multi-
plying by selt-division ; 25. Sporangium with its furcate spines, and around it the empfy
and previously conjugated fronds. 22. Micrasterias denticulata (Breb.), X 100, sporan-
gium of. 26. Cosmai'ivim cselatum (Ealfs), X300: front view of frond multiplying by
self-division, the young segments partially grown and their surface stiU smooth. 27. Pe-
diastrum tetras (Ealfs), x400, f.v. of a frond. 28, 29. Tetrachastrum oscitans (Diion),
XlOO: 28. f. v. ; 29. tr. v. of e. f. 32 & 35. Hyalotheca dissihens (Brdb.): 32. x200,
tr. V. with investing hyaline gelatinous sheath; 35. X400, f.v., also showing the sheatL
33,34. Cosmai'ium undulatum (Corda), x400 : 33. f.v. ; 34. Sporangium with the
empty fronds. 37 & 40. Desmidium quadrangulatum (Ealfs): 37. X 200, f. v. of fila-
ment; 40. X300, tr. V. 38,39. Didymoprium Borreri (Ealfs), x400: 38. tr. v.; 39.
Portion of a filament, f. v. Diatoms : — 41, 42. Lithodesmium undulatum ; 43. Eucampia
Zodiacus. Desmid : — 44. Micrasterias Americana. Diatoms : — 45. Podosira monilifor-
mis attached to Polysiphonia ; 46, 47, 49, 50. Biddulphia pulcheUa; 48. Denticella
Biddulphia.

PLATE III. (Desmids).

Figure 1. Gonatozygon Ealfsii (De Bary), tliree joints of, x300 ; 2. Same, conju-
gated, showing sporangiiun, XoOO. 3. Genicularia spirottenia (De Bary), single joint of,
X 150 (vide De Bary, op. cit. iv. 1. p. 717), X300. 4. Leptocystinema Eiiahani (Archer),
X200, shovsing front and side views of the band of eudochrome, and two joints with
nascent halves. 5. Aptogonum Baileyi (Ealfs), X400; 6. Same, e. v. 7. Desmidium
Aptogonum (Br6b.), portion of a filament, X400; 8. Same, e. v. x400. 9. Spondylosium
depressum (Br6b.), x300: five joiuts, one dividing. 10. S. pulchellum (Archer), x450:
five joints of a filament. 11. Euastrum oblongum (Ealfs), x200. 12. E. insigne (Hass.),
X200. 13. E. binale (Ealfs), X 400. 14. Cosmarium pyramidatum (Breb.). X 300;
15. Same, e. v. x300. 16. C. cylindricum (Ealfs), x300; 17. Same. e. v. x300. 18.
Staurastrum avicula (Br(5b.), x 300; 19. Same, e. v. x300. 20. S. teliferiun (KaUs),
X300; 21. Same, o.v. x300. 22. S. spongiosum (Brdb.), x300; 23. Same, e.v. x300.
24. S. quadraugulare (Br6b.), x300; 25. Same, e. v. 26. S. globulatum (Br^b.);
27. Same, e.v. 28. S. gi-acile (Ealfs), x300; 29. Same, e.v. x300. 30. S. restitum
(Ealfs), x300; 31. Same, tr. v. x300. 32. S. fureigerum (Breb.), x200; 33. Same, cv.
X200. 34. S. margaritaceum (Menegh.), X 300 ; 35. Same, e. v. X 300. 36. Arthro-
desmus Incus (Hass.), X 400. 37. Triploceras verticillatum (Bailey). 38. Docidium
Baculum(Breb.), x200. 39. Clostorium didymotocum (Corda), XlOO. 40. C. turgidum
(Elir.), X 100. 41. C. Uneatum (Ehr.), X 100 ; 42. Same, conjugated, showing the double t
sporangium, XlOO. 43. C. attenuatum (Ehr.), XlOO. 44. C. rostratimi (Elu-.). XlOO. '
45. Penium interruptum (Br6b.), X200. 46. Docidium Elu-cnbergii (Ealfs), x200,aftOT
W. Arclier (Nat. Hist. Eeview, vii. p. 375) : commencement of growth of lateral tube
preparatory to the formation of zoospores. 47. Same, the zoospores emitted and forming
an external cluster (p. 716). 48-54. After De Bary (op. cit.) ; all X 190, showing develop-
ment of sporangium of Cosmarium Bofrytis (Meiiegh.) : 48. The inner membrane witii
contents escaping by bursting tlio outer wall of the sporangium ; 49. The same esoapea.
somewhat fm-thcr developed, preparatory to segmentation of the contents, tlie extCTnal
membrane doubled; 50. Tlie same, division finished; 51. The same, li hour after;
52. The same, at a later stage; 53. Gfrm-ccUs, ordinarv vegetative division begun;
54. Product of the first division of a germ-ccU, each new half (but not until now) liaraig
assumed the characteristic form of the species. 55-60. After De Bary (op. cit.), all XoA .
sliowing development of sporangiiun o( Cosmarium Mcneghiuii (Breb.) : 55. Empty ou -
eidc coat of a sporangiiun witli an open sht or fissure by \\\nch the inner membrane (witli
contents) has come out; 56. Tlie emerged inner membrane and contents; 57. A pan* ot
germ-cells formed therein ; 58. The same, one escaping ; 59, 60. Products of the germ-

DESCKIPTION OF THE ENGEAVINGS.

951

cells, showing one segment tbo form of the gevm-cell, the other, ordinary vegetative division
supervening, having assumed that characteristic of the species. 61. Euastrum didelta
(Ealfs), X 150, abnormal condition of, after W. Archer (Nat. Hist. Eeview, vi. p. 469),
sho^ving a central irregular sti-uoture produced between the original segments, apparently
owing to the non-formation of a septum on the resumption of vegetative growth, and
forming with them but one uninterrupted cavity ; and in tliis instance the new central
growth having assumed the size and neai-ly the form of an entu-e frond, its axis of growth
and plane of expansion are at right angles to the old segments. 62. Ai-throdesmus Incus
(Hass.), XSOO, abnormal condition of, after W. Ai-cher, I.e., showing an abnormal growth
analogous to preceding, but carried on to another vegetative generation, the middle portion
being older than those produced between it and the original segments, the whole still
forming within but one iminterrupted cavity. 63. Cosmocladium pulcheUum (Breb.),
X250.

PLATE rv. (Diatoms).

[Plates IV. to VIII. are engraved by Mr. Tuffen West. Many of the figures are from original
drawings, others from specimens, and all of them are magnified 300 diameters.]

Figure 1. Epithemia tm-gida, f. and s. v. 2. E. Westermanni. 3. Eunotia pentaglyphis.
4. E. triodon. 5. Amphicampa mirabihs. 6. Himantidium pectinale, f. and s. v. 7.
Podosphenia Ehrenbergii, f. and s. v. 8. Ehipidophora paradoxa. 9. Licmophora flabel-
lata. 10. Podocystis Adriatica. 11. Sceptroneis Caduceus. 12. Dimeregramma sinu-
atum, f. and s. v. 13. Diatoma vulgare, f. and s. v. 14. D. elongatum. 15. D. Ehi'en-
bergii. 16. D. hyalinum, f. and s. v. 17. Asterionella formosa. 18. A. Ealfsii. 19.
Bacillaria paradoxa, f. and s. v. 20. B. cm-soria. 21. Mtzscliia Sigma. 22. N. scalaris,
f. and s. V. 23. Ceratoneis longissima, f. and s. v. 24. Homceocladia Martiana, f. and s. v.
25. H. iiliformis. 26. H. sigmoidea. 27. Synedra Ai'cus, f. and s. v. 28. S. pulchella,
f. and s. V. 29. S. capitata.. 30. Amphipleura pellucida. 31. A. inflexa. 32. Plagio-
gramma pulcheUum, f. and s. v. 33. Dimeregramma nanum, f. and s. v. 34. D. distans,
f. and s. V. 35. D. Tabellaria, f. and s. v. 36. Tryblionella graciUs. 37. T. acuminata.
38. Campylodiscus Hibernicus. 39. C. spirahs. 40. StriateUa vmipunctata, f. and s. v.
41. Rhabdonema minutum, f and s. v. 42. Hyalosira delicatula, f. and s. v. 43. Rhab-
donema Crozieri, f. and s. v. 44. Biblai-ium CasteUiim (EM. 33. 2. 1.). 45. StylobibUum
Clypeus. 46. Gomphogramma rupestre, f. and s. v. 47. Grammatophora marina. 48.
G. serpentina, f. and s. v. 49. Gephyria media, f. and s. v. upper and under valves.
50. G. incmwata, f. and s. v. ditto. 51. Diatomella Balfouriana, f. and s. v. 52. Disi-
phonia australis.

PLATE V. (Diatoms).

Figure 53. Cyclotella operculata, f. and s. v. 54. C. rectangida, f. and 8. v. 55.
Actinogonium septenarium. 56. Liostephania magnifica. 57. L. Rotida. 58. Dictyo-
lampra Stella. 59. Mastogonia Actinoptychus. 60. Hyalodiscus subtilis. 61. Podosira
Montagnei, f. and s. v. 62. Melosh-a Horologium, f. and s. v. (EM. 33. 2. 17). 63. M.
Bubflexilis, f. and s. v. 64. M. nummuloides, f. and s. v. 65. M. orichalcca. 66. Asto-
romphalus Arachne. 67. Melosira Roseana, f. and s. v. 68. Discosira sulcata, f. and s. v.
69. StephanocUscus yEgyptiacus, f. and s. v. 70. Endictya oceanica, f. and s. v. 71. Me-
losira Borreri, f. and s. v. 72. Liparogyra spiralis, f. and s. v. 73. Peristephauia Eutycha.
74. Stephanopyxis Turris. 75. S. ferox, f. and s. v. 76. Xanthiop.yxis oblonga. 77.
Stephanogonia polygona, f. and s. v. 78. Coscinodiscus ovalis. 79. Astcroniphalus
Brookei. 80. Oraspedodiscus Coscinodiscus. 81. Systephania Corona. 82. Ilalionyx
imdenarius. 83. Coscinodiscus stellaris. 84. Actinocyclus Ralfsii. 85. Heterostcphania
Rothii. 86. Asteromphalus Darwinii. 87. A. elegans. 88. Actinoptychus undulatus,
f. and 8. V. 89. Coscinodiscus concinuua. 90. Odontodiscua eccehtricus.

PLATE VI. (Diatoms).

Figure 1. Auliscus pruinosua. 2. Eupodiscus Argus : a, s. t. ; h, f. v. (the latter
from Kiitzing). 3. Auliscus scidptua : a, a. v. ; 6, f. v. 4. Aulacodiscua Oreganus. 5.
A. Beeveriic. 6. Porpeia quadriceps : a, s. v. ; h, f. v. 7. Cerataidua Isevia : a, s. v. ;
b, filament. 8. Hydrosera comprcssa, a. v. 9. Ceratauliis turgidus : a, s. v. ; fi, f. v'.
10. Biddulphia Tuomcyi: «, s. v. ; 6, f. v. 11. Zygoceros Mobdiensia: a, a. v. ; 6, f. v.
12. Biddulpliia Indica. 13. Hydrosera triquetra : a, a. v. ; A, filament. 14. Ilomitliscus
cuneiformis: a, a. v.; b, f. v. 15. Triccralium Solenoceros. 16. T. cxiguiuu. 17. T.

952

DESCRIPTION OF THE ENGEATrNOS.

venosum. 18. T. contortum. 19. T. spinosum. 20. T. punetatum. 21. T. altemans:
a, 8. V. ; b, f. V. 22. Amphipcntas flexaosus : a, with five angles ; h, var. witli four angles!
23. Pleurodesmium Brdbissonii : a, s. v. ; b, f. v. 24. Chaitoceros Wighaniii : a, Gonio-
thecium-like frustule, f. v. ; b, same, s. v. ; c, s. v. of connecting zone and awns without the
frustule; f/, filament entire. 25. C. boreale: a, s. v. ; f. v. 26. Bacteriastrum furcatum.
27. B. Wallichii ; a, s. v. ; b, filament (Tliis figure is introduced for the sake of the f. y.
which so closely resembles Bacteriastrum furcatum and B. curvatum as to be undistin-
gnishable in this aspect). 28. Dicladia Capreolus : a, s. v. ; b, f. v. 29. Goniothecium
Odontella: «, s. v. ; i, f. v. 30. Periptera teti-acladia.

PLATE VII. (Diatoms).

Figvire 31. Rhizosolenia Caly^stra. 32. R. styliformis, from a figure sent by G. Norman,
Esq., Hull. 33. R. setigera. 34. Syringidium Americanum. 35. Hercotheca mam-
miUaris. 36. Cocconeis Placentula. 37. C, transversalis. 38. C. distans. 39. C. pseudo-
marginata. 40. C. excentrica. 41. Achnanthidium coarctatum. 42. Achnanthes longipes.
43. A. subsessilis. 44. A. exilis. 45. Cymbella cuspidata. 46. C. Ehrenbergii. 47.
Cocconema parvum : a, s. v. ; b, f. v. 48. C. Boeckii : a, a. v. ; b, f. v. 49. Encyonema
prostratum (frustules) : a, s. v. ; b, f. v. 50. Amphora angularis. 51. A. membranacea.
52. A. litoralis. 53. Syncyclia Salpa. 54. Amphora cymbifei-a: a, upper surface in
focus ; b, lower surface in ditto. 55. Navicula tumida : a, s. v. ; b, f. v. 56. Amphora
ovalis. 57. A. spectabilis: a, up^jer surface in focus; b, lower surface in ditto. 58. A.
hyalina. 59. A. marma. 60. Gomijhonema geminatum. 61. Navicula didyma. 62.
N. Hitchcockii. 63. Stauroneis obUqua. 64. S. Crucicula. 65. Navicula (Pinnularia)
major. 66. N. producta. 6?. Stauroneis linearis. 68. Navicula rhynchocephala. 69.
N. Hennedyi. 70. N. latissima. 71. N. rhombica. 72. N. Amphisbajna : a, s. v. ; 6, f.T.
73. N. Cluthensis. 74. N. boi-ealis. 75. N. maxima. 76. Stauroneis acuta. 77. S.
pulchella,

PLATE VIII. (Diatoms).

Figure 1. Oncosphenia? (Diatoma elongatiun y, SBD.). 2. Eupleuria ocellata. 3.
Synedra robusta 4. Dimeregramma pinnatum. 5. Tessella iiiterrupta. 6. Dimeregramma
Harrisonii. 7. Nitzscliia Brightwellii. 8. Eupleuria pulchella. 9. Achnanthidium
trinode. 10. Tetracyclus lacustris, s. v. 11. Cladogramma Califomicum. 12. Rhab-
donema mirificimi, f. v. and s. v. 13. Cyclotella punctata. 14. Asteromphalus centraster,
punctations of compartments omitted. 15. Omphalopelta areolata. 16. Amphitetras
ornata. 17. Melosira arenaria, s. v. 18. Cosciaodiscus nitidus. 19. Perithyra denaria.
20. Syringidium bicorne. 21. Asteromphalus heptactis. 22. Euodia gibba. 23. Bid-
dulpliia Macdonaldii. 24. Aulacodiscus Blittoni. 25. Periptera chlamidophora. 26.
Coseinodiscus excavatus. 27. Triceratium trisulcum. 28. Aulacodiscus pulcher. 29.
Triceratium castellatvun. 30. Eunotogramma, s. v. 31. Microtheca octoceras. 32. Pleu-
rosigma formosum. 33. P. Balticum. 34. Podosira? compressa. 35. Attheya decora.
36. Staurogramma Persicum. 37. Anaulus scalaris. 38. Scliizonema Greiillii. 39.
Lysicyclia Vogelii. 40. Schizonema Dill^vynii. 41. Rliizouotia Melo ? 42. Rhizosolenia
robusta. 43. Colletouema eximium. 44. Omphalotheca liispida. 45. Plcurosiphonia
affinis. 46. Tosonidea undulata. 47. CoUetonema negleotum. 48. Stigmaphora roslrata.
49. Donkinia cai'inata, s. v. 50. Calodiscus superbus.

PLATE IX. (Diatoms).

Figure 131. Melosira sulcata. »131. M. varians. 132. Ac(inoptychus senariuB.
133-136. Navicula viiidis. 137, 138. SiuireUa striatula. 139. Stauroneis^ Plioemc-
enteron. 140. Amphipleura pcUucida. 141. Navicula Amphisbivna. 142. StaiuK)neis
platystoma. 143. Navicula nodosa. 144. Pleurosigma Balticum. 145. P. hippoeanipus.
146. P. acuminatum. 147. Synedra subtilis. 148. Nitzscliia sigmoidea. 149.
toplcura cUiptica. 150-152. Surirella splcndida. 153. Amphora ovalis. 154. GymbeUa
Ehrenbergii. 155. Cymatopleura Solea. 156-161. Epithemia turgida (except, m group
157, those (igures marked with a cross). *157. Epitliemia Wes(ernianni. 162, 163. Ooc-
conois sculclhun. 164. Eunotia triodon. 165. Epithemia granulatn. 166, 167. Bacu-
laria paradoxa. 168. Diatoma vulgare. 169. D. elongatuni. 170. D. niesodon. 1/1.
Himantidiuni pectinale. 172. Odontidium hyemalc. 173-175. Fragilana cap\icina.
176. F. virescens. 177-179. Meridion circulare. 180-182. Rhabdonema arcuatiuii.

DESCRIPTION OF THE ENGHATINGS.

953

PLATE X. (Diatoms and Protozoa).

Figure 183. Isthmia enervis. 184. Synedi-a Ulna. *185. S. capitata. 185. S.
luiiai-is. 186. Podosplienia gracilis. 187-190. Gomphonema constTictum. 191-193.
Licmopbora flabellata. 194, 195. Cocconema lanceolatum. 196-198. C. Cistula.
199-202. Achnanthes brevipes. 203, 204. Rbabdonema arcuatum. 205. Aciiieta
mystacina. 206. Syncyclia Salpa. 207. Schizonema Hoffmannii. 208. Micromega
Agardliii. Protozoa: — 209-211. Cyclidium Glaucoma. 212. Pantotriclium Enchelys.
213. Cbffitomonas Globulus. 214, 215. Cbastotyplila armata. 216-218. Cha;toglena
volvocina. 219, 220. Peridinium Tripos. 221. P. Michaelis. 222, 223. Peridinium
Fusus. 224-226. Glenodinium apicuJatum. 227. Trichodina tentaculata. 228-230.
T. Pediculus. 231, 232. Urocentrum Turbo. 233, 234. Stentor Eoeselii.

PLATE XI. (Diatoms).

Figxires 1 to 8. Epitbemia togida (Tbwaites) : 1. A view of concaTe sui-face ; 2. A
side view ; 3. Apposition of concave surfaces in the first stage of conjugation ; 4. A front
view of a single endocbrome, sbowing it to bave divided into two segments ; 5. The young
sporangia lymg transversely between the cleft parent frustules ; 6. The same, viewed end-
ways, sbowing their cyhndiical figure; 7. Increased growth of the sporangia; 8. The pro-
duced sporangia ultimately much larger than parent fronds, and now striated like the
latter. At the commencement of conjugation the fronds are enveloped in mucus, as shown.
9, 10, 11, 12. Gomphonema curvatum (Tbwaites), illustrating the process of conjugation
in this being, which generally resembles that in Epitbemia. 14. Melosira nummuloides
(Ealfs). 17. Gomplionema minutissimum (Tbwaites) conjugating. 18. Dinophysis acuta
(Ehr.), f.v. 19. D. limbata (Ebr.), f. V. 20 & 27. Melosira coarctata (Ehr.), f. vs. 21,22.
Amj)bitetras antediluviana (Ealfs) : 21. A partial s. v. ; 22. filament. 24, 25. Tetracyclus
lacustris (Ealfs) : 24. Eilament ; 25. A marginal view. 26. Melosira sulcata (Ehr.), a
filament. 28. Actinoptychus Jupiter (Ehr.). 29. Melosfra ItaUca (Elu-.), filament.
30. Sphenosira Catena (Ehr.), filament. 31. Actinoptychus? hexaptera (Elu*.). 32.
Ampbipentas? alternans (Ehr.). 33. Asterolampra Marylandica (Ehi-.). 34. Asterom-
phalus Hookeri (Ehr.). 35. Heliopelta Metii (Ehr.). 36. Symbolopbora Trinitatis (Ebr.).
37. Spirillina vivipara (Ebr.) : a member of the family ArceUina, having a close afiiaity
with the calcareous-shelled Polytlialaniia or Eoraminifera. 38. Craspedodiscus elegans
(Ehr.). 39,40. Coscinodiscus radiatus (Ehr.) : 39. f. v. ; 40. s. v. 41,42. Eupodiscus
Argus (Ebi'.): 41. f.v.; 42. s. v. (In fig. 41, the sites of the tbi-ee tubular processes,
which led Elirenberg at first to call it Tripodiscu.s, are seen.) 43, 44. Triceratium Eavus
(Ehr.) : 43. f. v. ; 44. s. v. 45, 46. Climacosphenia moniligera (Ebr.) : 45. f. v. ; 46. s. v.
47. Terpsinoti musica (Ehr.). 48, 49. Grammatopbora gibba (Ehr.) : 48. f. v., showing
the two imperfect septa (vittas, Kiitz.) at each end; 49. s. v. 50, 51. Zygoceros Sm-u-eUa
(Ehr.) : 50, s. v. ; 51. f. v. 52, 53. Grammatopbora marina (Ehr.) : 52. f. v. ; 53. s. v.
54. Hemiaulus antarcticus (Ehr.), f. v.

PLATE XII. (Diatoms, Protozoa, &c.).

Figure 1. Amphiprora constricta (Ehr.), f.v. 2, 3, 4. Surirella O^mraa (EJu\):
2, 3. f.v.; 4. s. V. : these figm-es were intended es25eciaUy to represent tlie foot-like pro-
cesses (ciUa ?) and the foramina through which these are protruded. 5. Navicula cuspidata
(Ebr.), B. V. 6. N. amphirhyncus (Ebr.), s. v. 7, 8, 9. Stauvoneis pbyllodes (Ehr.):
7, 8. s. V. ; 9. f. V. 10, 14, 30. Stam-oneis scalaris (Elir.) : 10. s. v. ; 14. Process of self-
division seen on f. v. ; 30. s. v. 11. Camisylodiscus flexuosa (Ehr.), f. v. 12, 13, 22, 23.
C. Ehrenbergii (Ehr.): 12 & 22. f. vs. ; 23. s. v. ; 13. Viewed lying on one end. 15 & 3l!
Navicula major (Ehr.): 15. s. v. ; 31. f. v. 16. Stam-oneis dHatata (Ehr.), s. v. 17 is!
S. Plioenicenteron (Ehr.) : 17. f. v. ; 18. s. v. 19, 20. Surirella Craticida (Ebr.) : 19. f. v •
20. 8. V. 21. Navicula Tabellaria (Elir.), s. r. 24, 25. Epitliemia Librile (Elir.) : 24. f. v! ';
25. s.v. 26. Ampliora gracihs (Elu-.), s. v. 27. Epitliemia gibba (Ebr.), ventral surface!
28 & 53. Gomphonema apiculatum (Elu\): 28. f.v.; 53. s.v. 29. Hiniantidiuni
monodon (Ehr.), s. v. 32. Navicula affinis (Ebr.), s. v. 33. N. Chilensis (Ehr.)
ventral surface, s. v. 34 & 36. Syncdra Gallionii (Ehr.) : 34. f. v. of four conjoined •
36. s.v. 35. Gomplionema Vibrio (Ehr.), s.v. 37. Amphora iiavicularis (Ehr.), f v'
38. A. Libyca (Ehr.), f. v. 39. Eunotia quinaria (Ehr.), s. v. 40. Uiadesmis lasvis
(Ehr.), f. V. 41. Cocconeis Einnica (Ehr.), s. v. 42. C. oceanica (Ehr.), s. v 43 Na
vicula Esox (Ehr.), s.v. 44. Nitzscliia valeiis (Ehr.), f.v. 45, 49, 50, 51 52 Ili'man
litUum Papilio (Ebr.): 45 & 51. Eilaiueuts ; 49. A single frustule sct'u ou ventral

954

DESCRIPTION OF THE ENGEAVINGS.

surface; 50&52. s. v. 46. Cocconema cymbiforme (Ehr.), b. v. 47. Peridinium con-

strictum (Elu-.) : the median sulcus or constriction is well seen dividing the lorica into
two segments — patellae or valves, each of which is here again composed of several facettes.
A distinct nucleus (sexual gland, Elu-.) is shown. 48 a, b. Cocconeis Americana (Ehr.):
48 a. 8. v. ; 48 h. Several frustules adherent to a portion of Conferva. 54. Himantidium
G-uianonse (Elu-.), f. v. of a filament. 55, 56, 57. C'olletonema Amphioxys (Elir.) : 55.
8. v. of a single frustule ; 56. f. v. ; 57. A collection enclosed in their mucous investment,
Been in different positions. 58. Sphserozosma ? . . . (Brightwell) : this production waa
found by Mr. Brightwell (see 'Fauna Infusoria of Norfolk'). We cannot perceive any
affinity between his drawing and the membei's of the genus Spharozosma, to which he has
surmised it might belong. 59. Ceratoneis Closterium (Ehr.), s. v. 60, 61, Pleurosigma
Fasciola (Ehi-.). 62,63. Dictyocha Speculum (Elu-.) : 62. Viewed in front ; 63. Viewed
sideways. 64. Difflugia acanthophora (Ehr.) : its surface illustrates what is termed an
imbricate disposition of the scale-like markings ; a navicular body is represented in its
interior, as seen through its transparent lorica. 65, 66. Asplanchna BrightwelUi (Bright-
well). These two figures are from Mr. BrightweU's book : 65 is there described as " a
young specimen (female), just emerged, in which the red eye and germs of other organs
are seen;" in 66 "may be seen the oesophagus leading to the stomach, and above the
stomach two small bodies (either salivary or hepatic glands), and under it the opaque
ovisac." 67, 68, 69. Zoothamnium Arbuscula (Brightwell) : these tliree figiu-es from
Mr. Brightwell illustrate the curious cycle in development referred to in the text. 70.
Vaginicola . . . ? (Brightwell) : apparently a Vaginicola undergoing spontaneous fission.
71. Mesocena heptagona (Ehr.). 72. Navicula cardinalis (Ehr.), b. v. 73. Stauroneis
Isostauron (Ehr.), s. v.

PLATE XIII. (Diatoms).

Figure 1. Amphipleura pellucida. 2. A. rigida. 3. SurireUa constricta. 4. Den-
ticula elegans. 5, 6, 7. Amphiprora alata. 8. Epithemia alpestris. 9. Ceratoneis
spii-alis. 10. Cocconema gibbum. 11. Gomphonema cm-vat\mi. 12. Epithemia Por-
ceUus. 13. (left) Podosphenia hyaUna ; (right) P. cuneata. 14. P. Ehrenbergii.
15. Rhipidophora teneUa. 16. Licmophora divisa. 17. Ehipidophora Nubecula.
18. Epithemia Musculus. 19. Rhipidophora Menegliiniana. 20. Synedra fulgens.
21. Meridion circi.ilare, var. 22, Grammatophora hamulifera. 23. Gomphonema
acuminatum. 24, 25, Odontidium hyemale. 26. TabeUaria ventricosa. 27. Rhab-
donema Adriaticura. 28. Pododiscus Jamaicensis. 29. TabeUaria flocculosa. 30, 31,
32, 32 a. Biddulpliia obtusa. 33. Pyxidicula Adriatica.

PLATE XIV. (Diatoms).

Figures 1 to 12. Eragilaria capucina. 13. Ilunantidiiun Soleirolii. 14. Cym-
bosira Agardhii. 15. Achnauthidium microcephalum. 16. A. delicatulum. 17. Oyclo-
tella Scotica. 18, 19, 20. Cymbella gastroides. 21. Rhaphoneis Amphieeros. 22.
Encyonema prostratum. 23. Hyalosii-a rectangula. 24-28. Cymbella Helvetica. 29.
Hyalosu-a obtusangula. 30. Sphcnclla angustata. 31. S. obtusata. 32, 33. Diadesmis
confervacea. 34, 35 a, h. Berkeleya Adriatica. 36. Gomphonema coronatimi. 37,
38 a, b, c. I-Iomoeocladia pumila. 39-42. l^Iicromega pallidum. 43, 44. M. bomby-
cinum. 45, 46. Homceocladia moniliformis. 47-49. H. Martiana.

PLATE XV. (Diatoms).

Figures 1, 2. Cyclotella atmospherica (Ehr.). 3. C. Atlantica (Elir.). 4. C. Sinensis
(Ehr.). 5. Staurosira construcns (Ehr.). 6, 7, 8, 9. Epithemia longicornis (Ehr.). 10.
Goniothecium crcnatum (Eln-.). 11. Epithemia Argus (Elu-.). 12. Nawula didyma (Ehr.).
13. DesmogoniumGuianensc(Ehr.). 15. Navicida Utuiata (Ehr.). 16,17. Ilimanlidnnu
monodon (Elir.) : 16. Two frustules conjoined in front view ; 17. s. v. 18, 19, 30, 21.
Arachnoidiscus ornatus (Shadbolt) : 18. External membrane, as seen when detaclied from
tlic inner I'ramcwork, or when viewed from the outside of the shell as an opaqiie object ;
19. The inner framework is exhibited on a black disc as nn opaque object ; 20, The mem-
brnno and framework united, as seen by transmitted light, x2t)0; 21. The same, more
ampliricd, X500. 22,23. Campylodiscus parviUus (Smith) : 22. s. v. ; 23. Partial f. v-
24, 25. Gnnnmoncnia Jurgensii (Ralfs) : 24. Front and s. v. of a single frustule ; 26. A
filament. 26, 27. Melosira Niigeli : a series of figiu*cs to illustrate (he distribution of the
chlorophyll (endochroaie), and the prosenoe of a nucleus : 26 a. viewed from the base ;

DESCaiPTIOlT OP Tin3 ENaHAVTNGS.

955

266. from the lateral surface; two bands of chlorophyll are seen on each side, and their
section at the angles; 26c. ii-om the base; 27. Seen from below, nucleus with nucleoli
and sap-currents; Im-go and small clilorophyll-globules ; 27 6. Seen from the side; the
two lateral bands of clilorophyll are seen, and a parietal nucleus, with sap-currents irom it,
in the centre of one side ; 37 c. An individual after division, seen from the side, ihe
chlorophyll bands appear only in section. Each secondary ceU has a paa-ietal nucleus.
28 a, A, c, d. BaciUaria Niigeli : a, viewed from the broad side, a granular nucleus m the
centre ; b, also the broad side, an individual before division, the nucleus primai-Uy divided ;
c, division complete ; d, viewed from the base (in section). 29 a, b, o, d. Melosira Dickieu
(Thwaites) : a, filament, in ordinary state ; 6, filament, the terminal cells of wluch are
becoming converted into sporangia ; c, sporangia ; d, sporangial frustules becoming deve-
loped from one of the halves of a previously divided sporangium, x220. 30 a, b. Mas-
togloia Danseii (Thwaites): a, portion of frond, x35; b, a part of same, x220. In it
two fr'ustules are shown, one in front, the other on side aspect. 31 a, b, c, d. Dickieia
ulvoides (Ealfs) : a, natural size, in different stages of grovrth ; b, fi-ustules (navicular
bodies) highly magnified when fresh ; c, one when dried ; d, a lateral view of the same ;
e, a portion of frond, less highly magnified, showing the simple and binate frustules.

32. Melosira vai-ians (Thwaites) (=Gallionella, Elu-.), filament with sporangia, x220.

33. M. Italica, filament with sporangia. 34. Dictyocha Eibula. 35, D. trifenestra.

PLATE XVI. (Diatoms and Dbsmids).

Figures 1 to 6. Navicula (Pinnularia, Ehi-.) major. From Schleiden's ' Principles of
Botany,' to illustrate the structm-e of the silicious valve. 1. s. v. (venter, Ehi-.). "In the
middle line are two clefts, terminating at the centre, as well as at the other ends, with a
little circular enlargement, more clearly seen in figs. 3 and 5. The rounded spot in the
middle, and at the two ends, is not a hole as represented by Ehrenberg. That such a hole
is decidedly sometimes not present, is seen in such fragments as figs. 3 and 5. In the
position of the obUque lateral clefts (strife or costse, Ehr.), the valve consists of two leaves,
penetrated by tlie clefts, which, where both the lamellae touch each other, are somewhat
broader, which explains the varying breadth of the clefts according to the alteration of the
foci. Fragments in which this structm-e is clearly represented may be frequently obtained
by crushing the valve (fig. 6). 2. A front view, showing that the rounded enlargements of
the median line are but depressions on the external surface. The double contoui', denoting
the thickness of the wall, is well seen. Tliis clearly shows that a passage exists from the
top to the bottom of the valve, which may be easily confirmed if the valve, or better still an
oblique section of it, be looked at from above ; fig. 5 is such a section." 7, 8. Cymato-
pleura eUiptica (Smith). 9. C. Solea. 10-19. Closterium Ehrenbergii (Smith), showing
the stages in its conjugation, and the formation of the sporangia : 10. A single frond in ita
ordinary condition; 11. Two fronds approacliing to conjugate; 12. Conjugating fr-onds
vmdergoing self-division, the upper showing the protuberances tlu-ough the torn apices of
which the contents of the divided fronds pass into the sporangia ; 13. Shows the passage of
the endockrome-sac and its contents; 14. Conjugated fronds having perfected thefr spo-
rangia; 15 (after M. Morren). Development of the "propagules" into young fronds;
16, 17, 18, 19 (from Morren). Development of a sporangium into a Closterium with
unequal segments: the figures are all magnified 100 times. 20-26. Surfrella biscriata
(Smith). To illustrate the structure of the valve and self-division of the frustide : 20. View
of frustules on the completion of self-division ; 21. Apertiu-cs of costal canals seen in front ;
22. Silex of connecting membrane after maceration in acid ; 23. f. v. (the broad median
longitudinal band is the connecting zone of the two valves) ; 24. s. v. ; 25. e. v. ; 26.
Transverse section of empty frustule.

PLATE XVII. (Diatoms and Phytozoa).

Figures 506-509. Pyxidicula globata. 511 & 515, Xanthidium ? ramosum. 512.
X. liirsutum. 513, 514. X. ? dillbrine. 516-518. Canipylodiscus Clypcus. 519-531.
Spirillum Bryozoou. 532, 533, Astasia navalis. 534. Gygos sanguineus.

PLATE XVIII. (PiiYTozoA).

Figure 1. Monas Crcpusculum, x800. 2. Monas Punctum. 3,4, Uvolla Glaucoma
X '■i'M: 4. Dctaclied monads. 5, Polytoiiia Uvella. 6, Microglena monadina. 7. Gle-

956

DESCRIPTION OF THE ENGEAVINGS.

noraomra tingons, X 250. 8. Doxocoecua ruber. 9. Bodo intestinalis, x3(X). 10 & 21.
Monas Leus. 11 a, b. Cercomonas lobata. 12 a, b. C. triincata. 13 a, b. Amphimonas
dispar. 14. Chilomonas Paramecium, X 380. 15. Monas elongata. 16. Trepomonas agilis.
17. Monas globulosa. 18. Chilomonas granulosa. 19. Monas attenuata. 20. Cercomonas
acuminata. 21. Monas Lens (two figs.). 22, Cercomonas longicauda. 23. C. Globulus.
24. Spiromonas volubilis. 25. Pleiu-omonas jaculans. 26. Ileteromita exigua. 27. Tre-
pomonas agilis. 2& a,b, c, d. Trichomonas Batracliorum. 29. Cryptomonas ovata, x300.
30. Prorocentrum micans. 31. Lagenella euchlora. 32. Cryptoglena conica. 33, 34]
Trachelomonas Volvocina. 35 a, b, c, d. Chonemonas Sclu-ankii : c, d. Var. C. unifilis."
36. Astasia htematodes. 37-39. Euglena sanguinea. 40, 51, 54. E. viridis, encysted
and in act of fission. 41,42. E. Pyrum, x400. 43,44. E. longicauda. 45. Ambly-
ophis vii'idis. 46. Euglena viridis. 47. Chlorogonium euchlorum. 48 a, b, c. Astasia
limpida. 49, 50. A. contorta. 52. Euglena spirogyra. 53, 55. Eutreptia viridis.
56. Zygoselmis intequalis. 57. Bacterium triloculare. 58. Spirocliajta plicatilis. 59.
Spirillum Undida. 60. Vibrio Bacillus. 61. Sjiirillum Undula. 62. Vibrio Bacillus*.
63.. Spii'odiscus fulvus. 64. Vibrio Eugula. 65, 66. Sporouema gracQe. 67, 68. Spi-
rulina plicatilis. 69. Zoogloea Termo : a mucoid mass of Vibrios, the individuals of which
are equivalent to Bacteriiun Termo of Dujardin.

PLATE XIX. (Phytozoa).

Figure 1. Chromatium Weissii. 2. Menoidium peUucidum. 3. Tetramitus descissus.
4-6. Mallomonas PlosUi. 7 a, b, c. Phacotus viridis. 8. Anisouema Acinus. 9, 10.
Trypemonas volvocina. 11. T. cylindi-ica. 12. Chonemonas acuminata. 13, 14. Lepo-
cinclis Globidus. 15. Hirmidium inane. 16. Chlamydomonas pulvisculus. 17. Dinema
griseoluin. 18, 19. Eutreptia viridis. 20-31. Chlamydococcus (Protococcus) pluvialis,
its forms and development, after Cohn : 20. A stdl cell revived after desiccation ; 21. Cell
with nucleus ; 22. Still cell with dense external coat ; 23. Fission of primordial within the
parent cell ; 24. Eission of a still cell, wall of parent cell become gelatinous ; 25. Division
of secondai-y cells ; 26. Fission of encysted cell into four secondary, and 27. into thirty-
two cells ; 28. The several cells produced set free, a membrane thi-own out around one ;
29, An irregular-shaped, Euglena-Kke zoospore; 30. A cell on the point of assuming
the motUe condition; 31. A very small, globular, encysted zoospore. 32-37. Gronium
pectorale : 32. A perfect tabular frond ; 33. Detached cells, showing their contractile
vesicles ; 34. Four cells (gonidia) united by the radiating tubular processes of theu* external
membrane, into wliich the gi-een contents do not enter ; 35. Excepting one cell of the
tablet, all the others have jiroceeded, to a gi-eater or less extent, by the process of fission, to
generate "daughter cells," or the rudimentary gonidia to form new tablets; each one is
still sm-roimded by the "mother-cell" wall; 36. A tablet, of wliich the original gonidia
are widely separated, and loosely held m situ by the external cell -wall ; fission has further
proceeded, and rudimentary tablets formed firom each original gouidiimi, consisting of
sixteen " daughter cells " (maorogoiiidia) ; in 37 the counectiug bonds are quite dissolved,
and the sixteen secondary tablets set free: all x500. 38-58. Stephanospluera pluvialis,
exlubiting its forms and modes of develoiiment : 38. An equatorial view; 39. Lateral
view, gonidia spindle-shaped, with protoplasmic elongations ; 40. Dinsion of gonidia into
four "daughter cells" ; 41. Fiu-lher divided into eight, united in an annular form ; 42.
A further-advanced stage, maorogonidia now forming distinct families, like the one repre-
sented in fig. 57 ; 43. Division of gonidia preparatory to forming mierogonidia ; 44. A
full-grown resting cell ; 45. Beginning of division of a resting cell ; 46. Division into
four, outer membrane disappeared ; 47. Tapering of one end of secondary or " daugliter "
cell preparatory to formation of ciUa ; 48, 49. Naked zoosjiores ; 50. Encysted zoospore
(gonidium) ; 51, Resolution of all the gonidia, except one, of a niatiu'e Stophanosphfcra
into mierogonidia; 52. Delached ciliated mierogonidia; 53. An encysted zoospore with
protoplasmic elongations of the primordial cell ; 54, 55. Di>nsion of encysted zoospore ;
56. More advanced stage of division ; 57. A young family of eight cells ; 58. Anotlier, with
the cellular envelope still visible within the membrane of the mother cell: XoOO (Colin).
59-69. Pandorina Morum : 59. Perfect form, with sixteen gonidia, side new; 60. The
same, polar view ; 61. A gonidiuin, side view ; 62. A frond with the gonidia divided ;
63. A more advanced frond ; 64. A young frond of fig. 63, after formation of cilia, set
free ; 65, 66, Young Ironds, goniclia pushed close togetlier ; 66. A polar view ; 67. End or
polar view of a frond like 65, the gonidia of wliicli are encysted and turned red and their
gelatinous envelope nearly dissolved ; 68, A side view of the same; 69. A single encysted
gonidiiun. Figs. 59 to 68 (except Gl ), X 100 ; figs. 61 & 6'J, X 400 (Heufrey).

DESCRIPTION OF TBGE EKGBAVnSTGS.

957

PLATE XX. (PiiYTOzoA).

Figures 1-14. Polytoma Uvella, forms and development of: 1. Perfect form; 2.
Same, acted on by clu-omic acid, which lias separated the primordial cell from the external
envelope; 3-6. Stages of fission-process ; 7. Besting stage ; 8. External membrane broken
up mto grannies ; 9. Fission into four ; 10-12. Ai-rangement of secondary or " daughter "
cells ; 13. Contraction of body within extei-nal envelope ; 14. Body retracted from ante-
rior extremity: x300 (Schneider). 15-21. Eission and formation of microgonidia in
Clilorogonium euchlorimi. 22, 23. Pandorina Moriun (?) : 22. A presumed form of,
with encysted immature fronds, Xl50; 23. Another presumed form, x220. 24.
Chlamydococeus (?), a presumed form of; the two internal globular cells of a clear
ruby-crimson ; the moving granules probably monads ; suggested to be Spermatozoa, X 220
(Cm-rey). 25. Volvoeina, a developmental phase of one of the, having encysted gonidia.
26-28. SyncryptaVolvox, x260. 29,30. Synura Uvella : 30. Section of a group (Ehr.).
31, TJroglena Volvox. 32. Volvox Globator. 33-49. Illustrations of structm-e and
development of Volvox Globator (Busk and Williamson) : 33. A section showing parietal
cells and contained gemmce ; 34. Portion of edge of an embryo Volvox viewed in the
equatorial plane to show the common envelope and the position of the subjacent cells or
gonidia ; the last not passing beyond the external gelatuaous (?) coat (Busk) ; 35. Highly
magnified view of three cells ; the faint Hnes between mdicate the limits of the gelatinous
envelope of each cell ; 36. Section of a specimen mounted in glycerme (Will.) ; 37. Cells
seen from above, showing radiating tlu'cads ; 38. ObUque section, moimted in glycerine ;
39-41. Single cells ; 42-44, 46, 47. Progressive development of Volvox by fission ; 45.
Diagram of a superficial view of a portion of a globe (Will.) ; 48, 49. Winter spores of
Volvox aureus : 48. An earlier ; 49. A later and mature condition (Busk).

PLATE XXI. (Peotozoa).

Figure 1. Amoeba Schultzii, x330. 2. A. globularis, x330. 3. A. porrecta, X330.
4. A. princeps, X 100. 5 a, b, c. Amoebiform germs or " Proteans " of SpongiUa. 6.
MiHola vulgaris. 7-9. Arcella vulgaris ; 8. A side view; 9. Empty shell. 10. Difflugia
globulosa, Xl50. 11. Euglyphaalveolata, empty shell, x340. 12-14. Gromia oviformis :
12. A young specimen ; 13, 14. Nuclear bodies found in (Schultze), X 300. 15. Arcella
Okenii. 16. Gromia oviformis, X300. 17. Difflugia pyrrformis. 18 a, b. Supposed
young forms of Gromia Dujardmii : a,x72; b, X 180. 19 a-f. D. Enchelys : a, b. Different
forms ; c. Contents resolved into granules ; d, e. Eission into two and four portions ;
/. Two individuals coherent. 20 a, b. Early stage of an undescribed Miliola : a, X 72 ;
b, x330 (Schultze). 21, 22. MiUola obesa: 21. A yomig specimen, x72; 22. Shell'
after the removal of the calcareous matter by dilute acid. 23. M. Anconensis. 24.
Animal contents of a Miliola after dissolution of the shell by acid ; displaying a constric-
tion at each half turn, and the deUcate membranous envelope at the lower and larger
extremity. 25. Cornuspira perforata. 26. Rotalia Veneta, seen in front. 27. RosaUna
omata, portion of shell of, X 100. 28. Polystomella venusta, X 72. 29, 30. P. Stella-
borealis, seen in front, X72; 30. Portion of cell to show structure, Xl80. 31. Rotalia
Veneta, shell after action of acetic acid, xl80. 32. Nuclear body from the last chamber
of Textilaria pieta, x330. 33. Rotalia Veneta, x50. 34 <!■, b. Acervidina acinosa;
b. Natural size. 35. Acervulina globosa, portion of shell, x3()0. 36. Textilaria picta'
Xl 80. 37. Acervulina globosa, section througl I thickness of shell, x300. 38. Polymor-
phina siUcea, siUcious matter detached by pressure, x300. 39. Polystomella strigilata,
animal substance with attached particles apparently assiuning an independent existence,'
x330. 40. Portion of contents of Gromia Dujardhiii. (Figures 20 to 40, Schiiltze.)

PLATE XXII. (Protozoa).

Figures 1-3. Amoeba radiosa ; 2. An older specimen ; 3. One nearly divided into
two. 4, 5. A. Limax. 6. A. guttula. 7-11. A. bilimbosa : in 7 and 9 tlio external
envelope strongly marked by a double outline; a clear zone wthin it; 9. First stage
of encysting; 10. A nucleus with a central clear space, and one witli two nucleoli-
11. A specimen acted on by solution of iodine ; contained starcli-granules coloured blue'
12-18. A. actinophora : in 13 two pulsating vesicles occm- ; 15. Specimen acted upon bv
acetic acid, showing double outline of integument ; 16 contains refracting particles of a
crystalline form ; 17. Some such particles isolated, and more highly magnified ; 18 Two
coherent individuals, indicative either of fission or of conjugation. 19. Cadiiim' mar'inum
20 -23. Amoeba biUmbosa : 20. Treated with iodine, the starch-granules coloured blue;

958

DESCniPTION OF THE ENGnATINOS.

21. An encysted specimen ; 22. A i-uptured and empty cyst ; 23. Probably the act of
fission. The large eii-cular body lying between the two halves is an encysted Oxytricha
which has been taken np by the Amceba. 24-27. Cyphidium aureolum. 28, 29. Grega-
rina Sipimculi ; 29. A double being, the residt of fission. 30-32. Progi-essive develop-
ment of the contents of a Gregarina from an Annelid (Coenurus variegata) into pseudo-
navicelloB,— in other terms, three pseudo-navicella capsules. 33. G. clavata. 34. G.
Sieboldii, full-grown. 35, 36. G. Terebella ; 36 exliibits longitudinal costse. 37. A
group of Psorospermia, from a cyst in the eye of a Cyprinus Tinea. 38 a, b, c. Full-
grown Psorospermia : a, viewed in front, X 900 ; f>, seen from above ; c, on one side. From
the vesicula of Gadus lota. 39. Psorospermia from a cutaneous cyst on a GasterosteuB
(Stickleback), X 580. 40. Psorospermia from a cyst of Gosterosteus aeuleatus ; a group
showing the difTerent stages of development. 41. Psorospermia burst by pressure from
Cyprinus Brama ; h, the contained amoebiform body isolated, X 900. 42. Epipyxis
TJtrieulus. 44, 45. Microtheca octoceros. 46. Opalina Lumbrici. 47. O. armata,
transverse fission. 48, 49. Dinobryon Sertularia.

PLATE XXni. (Protozoa).

Figures 1, 2. Actinophrys, figured as one phase in the development of Yorticella
microstoma by Stein : a, external coat ; b, nucleus ; c, vesicle. In 2 a ciliated embryo
appears witliin a distinct sac. 3-5. Podophrya fixa (?), represented by Stein as another
phase, besides figs. 1 and 2, in the development of Vortieella microstoma. A ciliated germ
is seen in 4, which in 5 is about to escape. 6-8. Other forms of Podophryean Acinete as
figured by Stein : 6, 7. As treated with acetic acid ; the development of an embryo from
the nucleus is shovni in figs. 7 and 8. 9-14. Vortieella-eysts, after Stein's figures. In 9
the nucleus is resolved into monadiform germs ; 10, 11. Development of cyst-contents into
secondary cysts, which are further seen in figs. 12 and 13 as become fusiform and protruded
through the wall of parent cyst, so as to discharge their monadiform germs without, as seen
in fig. 14. 15, 16. Acineta diademiformis, vsdth its embryo. 17-20. A. Unguifera, or
Acineta with the tongue-like process attributed to Opereularia berberina ; 20 shows an
empty capsule. 21. A. digitata, or Acineta with the finger-like processes. 22, 23. Acineta
attributed by Stein to Opereularia Liehtensteinii ; 23. A specimen acted on by acetic add.
24, 25. Actinophrys oeulata ; 25 represents three individuals in the act of conjugation,
treated with acetic acid. The contents of two have intermingled ; a large vacuole with food-
particles lies between them. The individual on the other side is simply coherent. (1-26,
Stein.) 26, 27. Acineta ferrum-equinum ; 27 shows the escape of the ciliated embryo.
The horseshoe-shaped nucleus appears as a clear space. 28. Actinophrys Sol. 29,30. A-
Eichhornii ; 30. A highly magnified section to show the retieidated, structvtre. 31, 32. A.
Sol: 31. In the act of self-division (conjugation ?) ; 32 shows tlu-ee vesicular expansions
concerned in the introduction of food, and an encysted animalcule just brought to the
surface. 33-35. Podophrya fixa ; 34. In act of fission ; 35. Segment becoming one inde-
pendent and about to separate. 36, 37. Encysted Podophrya. 38, 39. Stages of Podo-
phrya towards encysting. 40, 41. AcinetiB with embryos. 42, 43. Transformation of
the embryo into an Acineta, figured as commencing in 43, and as completed in 42.

PLATE XXIV. (Protozoa).

Figures 274, 275. Lacrymaria Proteus. 276, 277. Leucopluys patida. 278. L.
Spathula. 279, 280. L. sanguinea. 281. Holophrya Ovum. 282, 283. Prorodon teres.
284-286. Coleps hirtus. 287, 287*, 288, 289. Trachelius ^bias. 290, T. Ovmn.
291-293. Loxodes Eostrum. 294. Bursaria Vortieella. 295. B.lcucas. 296. B. Pupa.
296*. Spirostomum vii-ens. 297, 298. S. ambiguum. 299. Phialina viridis. 300-
302. Glaucoma scintillans. 303-309. Chilodon Cucidlulus. 310, 311. Nassula elegans.
312, 313. Ampliileptus Anser. 314-316. A. Fasoiola. 317-319. Tracheloccrca Olor.
320. T. biceps.

PLATE XXV. (Protozoa).

Figures 321-323. Aspidisca denticulala. 324-328. Kolpoda Cucullus. 329-332.
Paramecium Aurelia. 333. TJroleptus Muscidus. 334, 335. Ophrvoglena acmninata.
336, 337. Oxytricha gibba. 338, 339. Ceratidium cuncatuju. 340, 341. Kerona
polyporum. 342. Urostyla grandis. 343, 344. Styloiiycliia lauceolata. 345, 346.
Discocephalus rotatoriua. 347, 348. Himantophorus Cliaron. 349. Chlauiidodon
Mnemosyne. 350-353. Euplotcs Charon. 354, 355. Ptygura Melicerta. 356. Ich-

nESCurpTiON or the ENGEAvmas.

959

thydium Podiira. 357, 358. Chastonotus Larus. 359, 360. Glenophora Trochus.
361-364. CEcistes crystallinus. 365-370. Conoobilus Volvos.

PLATE XXVI. (PiiYTOzoA).

The following figures are derived from M. Dujardin'a excellent treatise, ' Histoire des
Infusoires ' : — Figure 1. Hesamita nodulosa. 2. Anthophysa Miilleri. 3, 4. Acineta
tuberosa ; in 4 the cilia included. 5. Heteromita ovata. 6. Crumenula texta. 7. Poly-
selmis vii'idis. 8. Anisonema sulcata. 9 a, b. Oxyri-his marina. 10 a, b. Ploeotia vitrea.
11. Heteronema marina. 12 a, b. Zyzoselmis nebulosa. 13. Peranema globulosa. 14.
Cyclidium distortum. 15. C. abscissum. 16 a, b. Acomia CycUdium ; b, self-dividing.

PLATE XXVIL (Protozoa).

Figiires 1-9. Vorticella microstoma : 1. With a bud growing from its base ; 2. A
specimen about to detach itself from its stalk, and having a posterior wreath of cUia ; 3. Self-
division proceeding ; in 4 complete ; ba,b, c, d. Encysting-process ; 5 e. A cyst ruptured by
pressure, giving exit to the included Vorticella, apparently unchanged ; 6. Supposed transi-
tional forms from rudimentary campanulate organisms to undoubted Vorticella ; 7-9.
Process of encysting, and progressive disappearance of special organs. 10-15. Vaginicola
crystallina : 10, Self -division ; 11. One of the fission-products contracted and ready to
escape by means of its posterior vrreath ; 12-15. Acinetce formed from Vaginicoloe. 16-23.
EpistyHs nutans : 16. Two individuals on a stem ; the ciUary apparatus protruded in one,
contracted in the other ; 17, 18. Supposed Acinetce ; Acineta-body of the EpistyHs ; in 17
the wavy outline indicates the contractions taking place in the integinnent ; in 18 the out-
stretched cUiary fibres or processes, two nuclei, and a large contractile vesicle are visible ;
19. Another such body, with its siu-face much contracted, and its contained substance
wasted by the development of embryonic nuclei ; 20. Another figure assumed by the
Acineta-body ; 21. The ultimately withered state arrived at by the Acineta-body of an
Epistylis, after the exhaustion of its contained formative blastema by the repeated produc-
tion of embryos ; 22, 23. Very young forms (probably) of the Epistylis nutans, and appa-
rently the Epistylis Botrytis of Ehrenberg.

PLATE XXVIII. (Protozoa).

Figures 1-3. Nassula ambigua: 1. Under surface; the two long articulated filaments
within are portions of OscOlatorioB ; c, vesicle; c?, nucleus; 2. Encysted specimen ; 3. Ani-
malcule forced from its cyst by pressure. 4-7. Glaucoma scintiUans : 4. Under sm'face ;
5. An encysted being, seen in 6 undergoing ti'ansverse fission, which in 7 appears oblique,
owing to a change of position of the resulting segments. 8, 9. Prorodon teres : 9. Its nucleus
surmounted by a rim-like nucleolus. 10. Stylonychia MytUus. (1-10, Stein.) 11-15.
Nassula elegans : in 11 internal germs occur in a cavity (uterine) eommunicatiug externally
by a canal (oviduct) ; 12. Germ loosing itself from the parent ; 13. A fission-product
enclosing a germ ; 14. Germ developing Acinetiform tentacles ; 15. Nucleus terminated
at its narrow end by a nucleolus. 16. Stontor MiiUeri, surrounded by an envelope with
monads in its interior ; 17. Same, animal contracted in its case. (U-17, Cohn). 18,19.
Vaginicola valvata. The valve is seen closed at b in fig. 18 ; fission has occurred both iu
tliis and in 19, but the animal is contracted in the former, and expanded in the latter
example; in 19 the valve appears as a streak parallel with one side. 20-23. Lagotia
viridis : 20. Head of a yoimg individual ; 21. Lateral view of animal and of its eUiated
head ; 22. Tip of one of the lobes of ciliated head ; 23. Animal with front view of head.
(18-23, Wright.) 24-26. Otostoma: the oral cavity is seen as an ear-shaped space ; in 25
two vesicles also are seen opening externally. (Carter.) 27-30. Coenomorpha Mcdusula.
31. Panophrys griseola. 32. Habrodon curvatus. 33, 34. Blejilinrisma hyalina. 35.
Cinetochilum margaritaceum. 36, 37. Cyclogranima rubens. 38, 39. "Stichotricha
secunda. 40-42. Ptyxidium ovulum ; in 42. Act of fission. 43, 44. Stichotricha
secunda. 45. C'olobidium pellucidum. 46,47. Mitophora dubia. 48,49. Apioiiidium
modestiun. 50, 51. Lcmbadion bidlinum. 52-54. Breonidium rcniigans. 55-57.
Opistliiotricha tenuis. 58-60. Mcgatricha partita. 61. Acropisthium mutabilo. 62 63!
Siagontherium tenue. (27-03, Perty.) 64 a-k. Enchelys Farcimon, illustrating change of
form consequent on the introduction of food. 65-71. Nassula viridis : 65. Natm-al form
X370; 66, 67. Cysts; 70,69,68,71. Development of cyst-contcnts into monndiform
germs, enclosed within saccxdar theca;, and at length discharged externally as iu fig 71 •

960

DESCRIPTION OF THF, ENGBWINGS.

X300 (Cienlcowslcy). 72,73. Enclielys Pupa. 74-76. Stylonychia pustiilala: 74. the
animalcule encysted, x300. 75,76. Rotating cells within the cysts, x220 (Cienkowsky).

PLATE XXIX. (Protozoa.)

Figure 1. Vorticella Campanula, viewed from the ventral aspect. 2. Carchesium
poly]Dinimi, viewed in front and directly upon the ciUated disc : i, the mouth ; e, tlie anui.
3. Scyphidia limacina. 4. Opercularia berberina; seen from the back. 5, 6. C'liajtospira
Miilleri : 6 represents the animal in motion. 7. Stentor polymorphus, showing vascular
canal around the head and along one side. (1-7, Lachmann.) 8-13. S. cajruleus, and its
supi^osed internal germs or embryos in different stages of development (Eckliard). 14, 15,
Trichodina Pediculus: 14. A lateral view; 15. Anterior extremity. 16. T. mitra. 17.
T. Pediculus, a dead, distended specimen. (14r-17, Stein.) 18. Stylonychia pustulata,
encysted (Stein). 19, 20. Amphileptus fasciola: seen encysted in fig. 19, and as escaped
from tlie cyst in fig. 20. 21-24. Oxytricha Pellionella : 21. Encysted ; 22. Cyst acted
upon by hydrocliloric acid ; 23. Animal revived in its cyst prior to its escape ; 24. The
free animal. 25-34. Paramecium (Loxodes, Cohn) Bursaria, its structure and develop-
ment : 25 to show circulation of contents ; 26. Portion of integument highly magnified ;
(19-2G, Cohn;) 27. Transverse fission; 28. Nucleus seen at c, the nucleolus at d; 29.
Embryo attached to the nucleus ; 30. Embryo escaped but still adherent by acinetiform
tentacles ; 31. Nucleus and attached nucleolus separated by acetic acid ; 32, 33. Nucleus
and nucleolus during fission of anunal ; 34. Nucleus, nucleolus, and commencing embryo.
35-47. Kolpoda Cucullus, illustrating its forms and development : 37. Acted on by alcohol,
to bring its nucleus into view; 38. An animal contracted into a spherical shape; 39. A
similar one undergomg fission; 40. Encysted Kolpoda; 41. Same, in act of fission; 42.
Fission completed ; 43. Specimen treated with alcohol ; 44. Cyst-contents divided into
four ; cyst-wall soft and irregular ; 45. Embryo escaping from a cyst ; 46. A ruptured
cyst giving exit to encysted germs, as seen in 47. 48-59. Chilodon Cuculhdus : 48 b. The
so-called dental cylinder ; c, nucleus and nucleolus ; 49. A specimen with a large upper
lip, equivalent to C. uncinatus (Ehr.); 50. Transverse, and 51. Longitudinal fission; 52.
Contracted prior to encysting ; 53, 54. Cysts ; in 54 an embryo developed ; 55. Appa-
rently laminated cyst discharging its contents ; 56, 57. An empty cyst, with the aperture
tlirough wliich its contents have escaped remaining ; 58. A cyst containing a parent animal
and an embryo ; 59. A liberated embryo, equivalent to Cyolidium Glaucoma (Ehr.).
(26-59, Stein.)

PLATE XXX. (Peotozoa, after Stein).

Figures 1-4. Opercularia articulata : 2. A highly magnified view of the head ; 3, 4.
Supposed Acinetse of this species ; an embryo shown fig. 4. 5-8. Oplu-ydium versatile :
In 5 the animal is seen extended, and in 6 contracted; 7. Encysted animal; 8. Its sup-
posed Acineta. 9, 10. Carchesium polypinum : 10. A highly magnified view of its stem.
11. Epistylis crassicollis. 12. Cothurnia cm"va. 13, 14. C. Sieboldii : 14. A side view.
15, 16. C. Astaci : 16. Animal contracted. 17-26. Spirochona gemmipara, and its develop-
ment: 17 exhibits a gemma; 18-20. Progressive development of tlie spiral head in a
gemma ; 21. Encysted gemma ; 22. Supposed Acineta (the Dendrocometes) in its early stage;
23. As fully developed ; 24. Embryo (seen in 23) set free ; 25. A Dendrocometes, without
arms, but with a contained embryo ; 26. A free embryo revolving on its long axis. 27, 28.
Spirochona Scheutenii ; 28. After the action of spirit of wine. 29-36. Lagenophrys
Vaginicola, its structure and development : In 29 a gemma is seen in tlie act of fission ; in
30 the animalcule has its rotatory appivratus retracted ; 31 shows the detachment of the
head of the animal from the mouth of its sheath, to allow escape of a gemma ; 32. Act of
fission ; 33. Formation of a gemma at posterior extremity; 34. Several gemmte enclosed;
35, 36. Act of fission ; complete in fig. 35, where the parent segment is detached from the
orifice of the sheath, leaving a portion of its interior extremity. 37. Oi^ercularia micro-
stoma: A, extended; u, contacted.

PLATE XXXL (Protozoa).

Figures 1-4. Bursaria leucas, and the position and structure of the trichocysts found
in its intcgimient: 1. x90; 2. Diagram of the margin, to show position of tricliocysts m
the dermal layer ; 3. Trichocysts projected from the surface after the application of acetic
acid ; 4. Detached spii-al trichocysts "in the sfecond stage of evolution from elongated OTW
corpuscles (Allman). 5-6. Coretlu-ia Sertidaria; : in 5 the two sorts of processes are bota

DESCHIPTION' OF THE ENGEAVINGS.

961

seen ; that in the right is the normal form ; 6, More magnified view of the fusifonn process,
showing tlie terminal depression or apertm-e. 7-13. Lagotia producta, its structure and
development: 7. Animal extended, in 8 contracted; 9, 10, 11. Larva or embryo; 10
represents it attached; 12. Diagram of structure of the sheath, showing the ectoderm
(coUetoderm) at a, the chitinous tube at b, and the endoderm at c ; d points out the mode
of overlapping of the sevei*al segments of tube ; 13. Highly magnified view of a portion of
tube. 14,15. Zooteirea religata : 14. Animal expanded ; 15, Conti-acted. (5-15, Wright.)
16-20. Peridinium uberrimum: 17. Seen on opposite side to that shown in 15; 18.
Transverse fission ; 19. Same specimen after the application of solution of iodine ; 20.
Nucleus isolated (AUman). 21, 22. P. depressiun : 21. A side-, 22. A front-view. 23.
P. longipes. (16-23 after Bailey.) 24-27. Dysteria armata: 25. Parts of mouth ; 26, 27.
Process between two styles: 26. A front-, and 27 A side-view (Huxley). 28. Tui-baneUa
hyalina, dorsal view : d, the muscular oesophagus ; g, testis ; /, mature egg ; c, ovary
(X350). 29,30. Cheetcmotus masimus : 29. Dorsal view (X 350); 30. A lateral view.
31. Ideal section of Tiu'baneUa hyahna tlu-ough the generative organs. (28-31, Schultze.)
32-39. NoctUuca miUtaris : (32. N. punctata, Busch : a, orai cavity or hilum ; h, sharp-
bordered rod ; c, nucleus ; d, proboscis [cihum] ; /, brown corpuscles, after Busch ;)
33. Front view, a, the tooth ; b, oral aperture ; c, position of suj^posed anus (after
Webb) ; 34. Dorsal view, shovnng the groove ; and 35. A latero-inferior view, displaying
the oral cavity with the tooth, d ; the ciliimi a gastric pouch, e ; and a presumed anal
aperture (Huiey) ; 36-39 (after Busch) : 36. A germ in process of development ; 37.
Brown granular body, seen at / in fig. 32 ; 38. A germ ; 39. Further advanced, acquiring
the characters of a NoctQuca.

PLATE XXXII. (EoTATORiA).

Figures 371, 372. Microcodon Clavus. 373. Cyphonautes compressus. 374-378.
Megalotrocha albo-flavicans. 379-382. Tubicolaria Najas. 383, 383*. Stephanoceros
Eichhornii. 384, 385. Ploscularia omata. 386, 387. Melicerta ringens. 388-392.
Limnias CeratophyUi. 393. Enteroplea Hydatina. 394. Hydatina senta. 395, 396.
Pleurotrocha gibba.

PLATE XXXIII. (EoTATOEiA),

Figures 397, 398. Furcularia Eeinhardtii. 399 & 417. Monocerea bicoruis.
400-402, & 425. Polyartlu^ platyptera. 403. Diglena lacustris. 404, 405. D.
grandis. 406-408. Triarthra lougiseta. 409. Rattulus limaris. 410, 411. Distemma
Forficula. 412 & 414. Triophthalmus dorsalis. 415. Eosphora Najas. 416. Notom-
mata Copeus. 418-420. N. Myrmeleo. 421. N. Tigris. 422. Synchasta pectinata.
I 423, 424. Scaridiiun longicauda.

PLATE XXXIV. (Rotatoria).

Figures 425* 426. Cycloglena Lupus. 427-429. Theorus Ternalis. 430-433.
Lopadella ovalis. 434-437. Monostyla quadridentata. 438-440. Mastigocerea carijiata.
441-444. Euchlanis? triquetra. 445, 446. E. Lynceus. 447-453. Salpiua mucronata.'
454 -456. Dinocharis Pocillum. 457-459. Monura dulcis. 460-462. Colurus deflexus.
463-465. Metopidia Lepadella. 466, 467. Stephanops lamellaris. 468, 469. Squa-
mella oblonga. 470-473. CaUidina elcgaus.

PLATE XXXV. (RoTAToniA).

Figure 474. Hydrias cornigera. 475. Typlilina viridis. 476-480. Rotifer vul-
^'.iris. 481-484. Actiiiurus Neptunius. 485, 486. Monolabis conica. 487-489.
Philodina aculeata. 490. P. roseola. 491-494. Noteus quadricornis. 495-497.'
Anurtea Squamula. 498. A. stipitata. 499-501. Bracliionus polyacanthus. 502-504!
I'terodina Patina. 505. P. clypeata.

PLATE XXXVI. (Rotatoria).

Figure 1. Melicerta ringens, protruded and fully expanded, witli tlie upper part of its
be at a ; h, one of the tactile tubes ; the circulai' disc at c is tlio pellet-cup ; at m are the
«ws and gizzard (oesophageal head) ; and below, the stomach ; c, a much less magnified

3 Q

962

. DUSCHirXTON OF XUE ENGKATINGS.

specimen, partially protruded from its tube, which is liere shown entire, x300. 2. Lim-
nias Ceratopliylli : the end is protruded beyond the smooth tube or sheath ; at e is the
pi-ojecling cliin. 3. Notommata am-ita, viewed laterally, contracted: it exliibits the oeso-
phageal head and jaws (6), the intestine, the large ovarium, the contractile sac below, the
grape-like ganglionic mass in the head(^), and the tortuous vessels on each side, running
the length of the body. 4. The same animal extended and rotating ; the ear-like cUiated
appendage, whence the specific name, is seen on each side of the head. 4 a. The ciliated
lobes of the rotary organ ; i, the gizzard, with its jaws ; g, the cerebral (?) mass ; k, glands
above the stomach; o, large matiu'cd egg in the ovary. 5. Notommata aurita, viewed
dorsally, the viscera omitted, to show the muscular system ; the transverse muscles are
seen at t, and the longitudinal, crossing them, at I; the grape-like ganglionic mass
aj)pears connected with special muscles, as also the gizzard, traced in dotted outline, and
tlie telescopic-working tail or foot (i) ; the looped band at the head (o) indicates the
tubular cavities in the head-mass. 6. The same animal, showing chiefly its water-vascular
system ; the large sac near tlie bottom of its cavity {v) is the contractile bladder, from
wliich proceed, on each side, convoluted tubes (tortuous vesicles) furnished with tremulous
respiratory tags, as near a ; the transverse muscular bands seen at t. 6 *. The dental
apparatvis of the gizzard as seen in action. 7, 8. The male of Asplanchna priodonta:
7. s. V. ; 8. f. V. The cavity is seen occupied chiefly by the large testes in fig. 7 ; the
sperm-duct is represented opening externally at the pointed base. 9. The female of
Asplanchna priodonta : at a are the gill-like fissures ; a large oral cavity opens into a
narrow oesophagus, which ends below in a stomach. One of the strong longitudinal
muscles is displayed, also tortuous vessels and ciliated tags, with an ovary. 10, 11. The
jaws of the Asplanchna detached.

PLATE XXXVII. (Rotatoria).

Figure 1. Stephanoceros Eichhornii: a, sheath; b, pharynx; c, prorentriculus, or
crop ; d, maxillary head with jaws ; e, stomach with large glandular cells ; f, intestine or
rectum ; g, ovary with contained ova {g at pedicle indicates the longitudinal muscles in.
that segment) ; tt, respiratory canal and tags. 2. Ovary and the enveloping membranous
sac, or uterus, extending from it, containing ova in different stages of development: a,
stroma of ovary with inherent ova ; the darker segment probably indicates the position of a
winter ovvun developing ; b, ovum dividing ; c, ovum in which division of yelk has been
several times repeated ; d, an ovum in which the rude outlines of the embryo are distin-
guishable, the two eyes at d, and the sac with the so-called urinary concretion &i k\ f
points to the uterine or ovarian enveloping membrane. 3. A very young Stephanoceros.
4. An embryo of Stephanoceros immediately after its exit from the shell. 5. An ovimi of
Lacinularia. 6. Another ovum of the same, its yelk in process of fission. 7. A portion
of the ovary of the same, with four contained ova. 8. An ovimi of the same, in which
division has been repeated several times. 9. Another ovum, wherein fission has been
repeated until the yelk is broken up into a number of ceUs. 10. A young embryo of
Lacinularia immediately after its exit from the egg. 11. Another embryo, further developed.

12. Termination of a tentacidar process of Mehcerfai ringens, showing the piston-like disc,
capable of retraction by a muscular band affixed to it, and surmomited by a brush of cilia.

13. A view of the same process, with the brush of cilia extended. 14. The same, with the
cilia retracted. 15. An embryo of Melicerta ringens, wliich has attached itself and has
commenced the formation of its case or sheath. 16. An embryo of the same animal as it
appears when swimming freely. 17. Melicerta ringens, fully developed, with the lobes or
petals of its ciliary wreath («) fuUy expanded; b, uncmi ; c, ciliated process, representing
a fifth lobe; dd, tcntacula, as shown in figs. 12, 13. 14; c, jaws; ^, lower or second
stomach ; h, intestine ; k, coloured globules ; /, suctorial end of pseudopodimn ; w, nnisclra ;
n, gland ; o, oram. 18. Two muscidar fasciculi, showing transvci*se markings. 19'
Lacinularia sociaHs: a, pharynx; b, maxillffi, or jaws; c, muscular crop; rf, stomach;
e, lower segment of stomacli, terminating in a narrow rectimi and anus at if: g, r
didar (?) process ; h, ovary ; i, respii-atory canal ; k, pedicle (Huxley). 20. MaxiIlaJ oi
Lacinularia socialis. 21. Winter ovum in act of division. 22. Segmentation ot a
portion of the ovary, of a dilferent cluiracter from the rest, in process of fornung a
ovum. 23. Maxillcc of Melicerta ringens, in bulb. 24. Winter ovum of I>acuuilaria.
25. A portion of ovary of Notommata centrura: a, the homogeneoiis gcrmnial spot; 0, we
clear areola around it ; c, yelk-mattcr. 26. Maxillic of MeUccrtfl ringens. 27. V\ inter ovum
of Asplanchna SiebolcUi treated with solution of soda. 28. Winter ovum in its na""?'
BMe. 29. Mule of Asplanchna Sieboldii, viewed from the abdominal surface: " tw
anterior short arms ; b b, the posterior longer arms ; c, testis, or spermatic sac, fi^J^vL
spermatozoa ; d, water- vascular canal. 30 a, b, c, d, c, f. The corpuscles of tlie preceoing

DESCaiPXION OP THE ENQILVVING3.

963

at c represent the earliest stage of the spermatic particles ; those at a the matiire mcluding
the rod-Uke particles. 31. The maxiU.i3 of Asplanclma Sieboldii; the striated muscular
bands moving them are very distinct. 32. Tlie female of Asplanclma Sieboldii: a,
pharynx; A, ceUs of stomach; c, horseshoe-shaped ovary; d, saccular or uterine portion
of oviduct, or ovarian sac, with contained matm-e ovum; c, contractile vesicle; tags of
water-vascular canal; k, ditto; ff, muscular (?) cushion within ciliary wreath supporting

spmes.

PLATE XXXVIII. (Rotatoria).

Figure 1. Rotifer inflatus, body extended; rotary apparatus withdrawn. 2. The
same Rotifer, with the horn-Uke appendages of its rotary apparatus expanded. 3. Tlio
same Rotifer, strongly conti-acted into a globidar form. 4. Philodina erythrophthalma, in
a contracted condition, as foimd when di-ied. 5. Euclilanis triquetra, viewed on the under
side : a points to the lining membrane of the lorica in which the muscles are inserted ;
b, muscles ; c, ganglionic enlargement ; d, respiratory tube ; e, areolar tissue of head ;
/, oesophagus, or tube between maxillary head and stomach. 6. Anursea heptodon. 7.
Brachionus rubens, the young just emerged from the shell. 8-10. B. Bakeri: 8. Young
from the egg ; 9. Summer egg ; 10. Winter egg. 11. Notommata centrura, a portion of
the respiratory tube, with the ciUary tags within. 12. TCTinination of a tag, with the
cilium within. 13. A portion of a water-vascular canal, with ciliated tags of Asplanclma
Sieboldii. 14. Diagram of head of Bracliionus polyacanthiis, viewed from the mouth
side. 15. Diagram of head of the same, viewed from above. 16. A portion of the cerebral
gangUon and of the nerves proceeding fi-om it, and the eye consisting of two portions.
17. Eye of Bracliionus Bakeri, detached. 18. Eye of Euclilanis unisetata. 19. Eye of
Caligus. 20. Diagram of head (trochal disc) of Philodina. 21. Diagrana of same, viewed
from the mouth side. 22. Rattulus carinatus. 23, 24. Salpina spinigera. 25. Noteus
quadricornis, dorsal view : a, maxillte ; c, anterior spinous cornu of lorica ; c c, posterior
cornu ; d, ovary; /, vesicle of water- vascular system; e, canal of ditto; h, stomach;
i, muscles. 26. Notommata centrm-a, dorsal view, siu'rounded by a mucous external
envelope, and Uned by a subtegumentary lamina or dermis : b, antenna ; c, glandular sac
around oesophagus ; d, elongated process of rotary organ, called the under lip ; e, tags of
respiratory canal ; /, stomach, with large glandular cells of its wall ; ff, intestine ; h, pan-
creatic glands ; i, vesicle of water- vascular or respiratory system; k, cerebrum; I, canal of
respiratory tube surrounded by a granular coat ; o, ovary ; ovum ; n, muscular bands ;
q, chitinous lining of oesophagus ; r, transverse muscles. 27. Brachionus Bakeri : a, lorica
or carapace ; b, posterior horns ; c, anterior horns ; d, lobes of trochal disc ; e, siphon or
antenna ; / gastric canal or oesophagus ; ff, convoluted respiratory tube ; I, pancreatic
glands. 28. Asplanchna priodonta : a, longitudinal muscles ; b, oesophagus ; c, stomach ;
d, ovary; e, pharynx. 29. Pterodina Patina, foot not shown: ac, convolutions of respi-
ratory canal; b, longitudinal striated muscles. 30. Polyartlira platyptera : a, cUiated
tubercular processes of head ; c, compound feathery processes used as locomotive organs ;
d, mature ovum adherent externally ; m, striated longitudinal muscles. 31, 32. Poly-
chsetus subqiiadratus. 33. MaxiUse of Notommata vermicularis, with the red eye, con-
sisting of two portions («). 34. Maxilla; of Hydatina senta. 35. Maxilla; of Albertia
vermicularis. 36. Albertia vermicularis, x200. (Figiu-ed after Dujardin, Huxley, Leydig,
and Perty.)

PLATE XXXIX. (Rotatoria).

Figures 1-3. Lindia torulosa: 1. Rotaiy organ retracted; 2. Dental apparatus of
ditto; 3. Rotary organ expanded. 4-7. Euclilanis dilatata: 4. Female, lying on its
back, abdomen upwards ; 5. Male, lying on its back ; 6. The granular heap from a young
male; 7. Male, lying on its abdomen. 8, 9. Notommata parasita (Ehr.): 8. Male;
9. Female. 10-20. Brachionus urceolaris: 10. A summer ovum in tlio act of fission ';
11. The embryo escaping from a summer egg, with rupture of shell ; 12. A young nuilo
after its escape from tlie egg; 13. A male escaping from the egg; 14. A young male,
older than Dg. 12 ; 15. Female, rotary organ fully expanded ; 16. Female, \nlh four male
eggs in dill'erent stages of development attadied ; 17. Female, rotary organ retracted
tentacular process (calcar) protruded ; 18. Female, lateral view ; 19. Maxillary bulb
(mastax), with teeth in position ; 20. A winter, ephippial, or lasting ovum. 21-24 Br'V-
chionus militaris: 21. Female, lying on its back; 22. Female, lying on its abdomen-
23. A winter ovum ; 24. A male ovum. (Cohn.) '

3q2

964

DKSCTllPTION 01' THE ENGSAVINGS.

PLATE XL. (EoTAToiiiA).

Figure 1. Hydatina senta, female, lateral view : a, dorsum and oral carity, extending
to an apex at 6 ; c, mastax with maxilla) ; d, canal between mastax and stomach ; /, cloacal
orifice ; g, vesicle ; h, ovary ; i, coils of respiratory tube ; k, cerebral ganglion ; I, cUiatcd
tactile fossa ; m, longitudinal muscles. 2. Enteroplea Hydatina, the male of Hydatina
senta. 3. Ova in an immature state, as found in the unimpregnated ovary of Hydatina
senta : a, germinal spot ; b, germinal vesicle ; c, membrane of ovum occupied mth gi-anular
yelk-matter. 4. The lining membrane of stomach of Hydatina senta, everted, showing
cUia. 5. Vibratile tag, supported on its pedicle, attached to the respiratory canal. 6. The
male sexual organs (of Enteroplea Hydatina) detached, and higljy magnified : a, penis ;
b, gland siUTOunding its bag ; c, vesicles with granules ; d, fold of integument surrounding ■
penis when retracted. 7. Detached spermatozoa. 8. Stephanops muticus, seen from,
beneath. 9. Same, side view. 10. Another view from beneath, or the ventral surface.
11. Brachionus Dorcas, female, newly born. 12. Same, male, newly born (Gosse).
13. B. Mulleri (male) : a, head mass ; b, eye ; c, muscles ; d, posterior mass ; e, sperm-
sac ; /, urinary concretion ; g, foot. 14. B. Pala, male, newly bom. 15. Same, male
egg, nearly mature. 16. B. Bakeri. 17. Sacculus viridis, male, newly born. 18. Same,
female, with male ova attached. 19. Brachionus angularis, male. 20. B. urceolaris,
mastax and dental apparatus, ventral aspect: a, mastax; b, malleus; c, manubrium;
d, articulation ; e, uncus ; /, incus ; g, ramus ; h, fulcrum ; i, muscle connecting the imcus
with the ramus ; j, muscle for extending the malleus ; muscle for throwing in the
manubrium ; k, muscle for bending the malleus ; m, buccal funnel ; n, saUvary glands ;
o, alula. [These letters have the same signification where met with in the following figures
after Gosse:] 21-23. B. urceolaris: 21. Jaws viewed nearly from above; 22. Dental
apparatus, lateral aspect ; 23. Buccal funnel, salivary glands, mastax, and dental appa-
ratus, dorsal aspect. 24. Diglena forcipata, jaws closed, ventral aspect. 25. Eloscularia
ornata, jaws, dorsal aspect. 26. The same, frontal aspect. 27. Stephanoceros Eich-
hornii, jaws, dorsal aspect. 28. Same, uncus, obUque aspect.

965

INDEX

TO

THE DESCKIPTION OF THE FAJMH^IES AND GENERA
OF INFUSORIA.

AcariiEtim, 503.
Achnanthem, 872.
Achnanthes, 873.
Achnanthidium, 872.
Acineria, 629.
Acineta, 564.
Acinetina, 564.
Acomia, 613.
Acropisthium, 614.
Actinisceis, 935.
Actiiiiscus, 935.
Actinocyclus, 833.
Actinogonivun, 813.
Actinophryina, 243, 558.
Actinophrys, 559.
Actinoptychus, 839.
Actinuriis, 704.
Alastor, 571 .
Albertia, 693.
Albei-tims, 693.
Alyscum, 615.
Amblyophis, 541.
Amoeba, 548.
Amoebcsa, 548.
Amphicampa, 765.
Amphimonas, 498.
Ampliileptus, 636.
Amphipentas, 858.
Amphi pleura, 783.
Amphiprora, 921.
Amphitetras, 8.57.
Amphora, 880.
AnauluB, 859.
Ancyrium, 501.
Atiffuliferece, 852.
Anisonema, 512.
Ankistrodesmus, 752.
Anthophysa, 500.
Anur.Ta, 707.
Apionidium, 615.
Aptogonum, 723.
Arachnoidiscus, 841.
ArceUa, 554.
Arcellina, 551.
Arthrodesmus, 736.
Arthrogyra, 822.
Aspidisca, 631.

Aspidiscina, 631.
Asplanchna, 691.
Astasia, 539.
AstasicBa, 188, 538.
Asterionella, 779.
Asterodiscus, 838.
Asterolampra, 836.
Asteromphalus, 836.
Attheya, 863.
Aulacodiscus, 843, 938.
AuUscus, 845,

Bacillaria, 715.
Bacillaria, 784.
Bacteriastrum, 863.
Bacterium, 532.
Bfflonidium, 614.
Berkeleya, 926.
Biblarium, 805.
Biddulphia, 847.
Biddulphiece, 846.
Blepharisma, 628.
Bodo, 496.
Brachionaa, 706.
Brachionus, 709.
Brightwellia, 940.
Bursaria, 620.

Cadium, 558.
Calia, 629.
CalHdina, 701.
Calodiscus, 802.
Campylodiscus, 798.
Carcliesiura, 588.
Cephalosiphon, 670.
Cerntaulus, 846.
Coratidium, 642.
Ceratium, 577.
Ccratoneis, 782.
Cercomonas, 497.
Ch(Efocere(e, 800.
Clifctoccros, 861.
Chfctoglena, 575.
Cliirtomonas, .573.
Chfetonotua, 661.
Cha3to8pira, 597.
Chnetotyphla, 575.

Chilodon, 624.
Chilomonas, 495.
Chlamidodon, 646.
Chlamydococcus, 522.
Clilamydomonas, 146, 521.
Cbromatium, 502.
Chloraster, 494.
CUorogonium, 543.
Chonemonas, 513.

ClLIATA, 668.

Cinetochikun, 630.
Cladogramma, 814.
Clenodon, 684.
CHmacosphenia, 772.
Closterium, 746.
Cobalina, 571.
CocconeidecB, 867.
Cocconeis, 867.
Cocconema, 877.
Coccudina, 648.
Coelasferimi, 755.
Coenomorpha, 597.
Colacium, 544.
Colletonema, 926.
Colepina, 616.
Colepa, 616.
Colpoda, 632.
Colobidium, 615.
Coif odea, 631.
Colm-us, 698.
Conocliilus, 664.
Corethria, 563.
Cornuspira, 558.
Corycia, 5.50.
Cosxinodhcem, 827.
Coscinodiscus, 827.
Cosmarium, 731.
Cosmocladium, 752.
Cofchurnia, 603.
Craspedodiscus, 831, 939.
Crumenula, 511.
Cri/pfomonadina, 140, 505.
Cryptx)glena, 509.
Cryptomonas, 507.
Ci/clidina, 671.
Cyclidium, 497, 572.
Cycloglena, 690.

966

INDEX XO THE FAMILIES AND GENEEA OF INFUSORIA.

Cyclograimna, 630.
Cyclotella, 811, 937.
Cylindi'otlieca, 940.
Cymatoplem-a, 793, 940.
CymbeUa, 875.
Ci/mhellecB, 875.
Cymbosira, 875.
Cypliidium, 565.
CypLoderia, 557.

Dasydytes, 661.
Dendrosoma, 662.
Denticula, 773.
Bcsmidiacem, 715.
Besmidiece, 715.
Desmidium, 723.
Desmogonium, 789.
Diadesmie, 923.
Diatoma, 778.
Biatomacem, 756.
Biatomem, 756.
Diatomella, 810.
Dickieia, 925.
Dicladia, 863.
Dictyocha, 935.
Dictyolampra, 813.
Didymoprium, 723.
Difflugia, 653.
Diglena, 687.
Dileptiis, 638.
Dimeregramma, 790.
Dinema, 546.
Binohryina, 546.
Dinobryon, 647.
Dinocharis, 698.
Diophrys, 648.
Diplax, 695.
Diploneis, 892.
Dipodina, 713.
Discocephalus, 645.
Discosira, 822.
Diselmis, 511.
Disoma, 608.
Distemma, 689.
Distigma, 544.
Docidium, 744.
DonMnia, 920.
Doxococcus, 495.
Drepanomonas, 513.

Eraydium, 713.
Enchelia, 605.
Enchelys, 607.
Encyonema, 879.
Endictya, 831.
Enteroplea, 677.
Entomoneis, 921.
Entopyla, 810.
Eospliora, 689.
Epholota, 562.
Epipyxis, 546.
Epistylis, 588.
Epithomia, 759, 938.
Eretcs, 501.
Euaatrum, 728.
Eiicampio, 937.

EucJdanidota, 693.
Euclilanis, 695.
Eudorina, 520.
Euglena, 541.
EiiglcncBa, 188, 538.
Euglypha, 556.
Eiuiotia, 762.
EunotiecB, 769.
Eunotogi'amma, 860.
Euodia, 862.
Euphyllodium, 772.
Eupleui-ia, 809.
Euplotes, 646.
EuplofAna, 645.
Eupodiscece, 842.
Eupodiscua, 842, 938.
Euti-eptia, 646.

Eloscularia, 674.

Floscularima, 665.
Fragilaria, 776.
FragilariecB, 773.
Erustulia, 924.
Furcularia, 679.

G-astroclireta, 615.
Genicularia, 721.
Gephyria, 809.
Glaucoma, 624.
Glenodinium, 578.
Glenomorum, 494.
Glenophora, 662.
Gloeococcus, 524.
Gomphogmmma, 806.
Gomplionema, 886.
GonvphoneimcE, 886.
Gonatozygon, 721.
Goniothecium, 864.
Gonium, 152, 517.
Grammatophora, 807.
Grammonema, 777.
Gromia, 556.
Grymffia, 503.
Gyges, 516.
Gyi'osigma, 915.

Habrodon, 614.
Halionyx, 833.
Halteria, 644.
Harmodirus, 629.
Heliopelta, 840.
Hemiaidus, 861.
Hemidiscus, 852.
Hercotlieca, 866.
Hetoromita, 499.
Heteronema, 545.
Heterostephunia, 833.
Hcxamita, 499.
Himautidium, 765.
Himnntopborus, 646.
Hirmidiura, .528.
Ilolophrya, 612.
HomoDOclndia, 784.
Hyalodiscus, 814.
Hyalosira, 804.
Hyalotheca, 722.

Hydatina, 677.
Hydatinma, 677.
Hydrias, 702.
Hydromorina, 503.
Hydrosera, 852.

Ichfhydina, 660.
Ichthydium, 661.
InsileOa, 827.
Isthmia, 851.

Kerona, 642.
Kolpoda, 632.
Kolpodea, 631.
Kondylostoma, 627.

Labidodon, 682.
Lacemata, 924.
Lacinularia, 670.
Lacrymaria, 609.
LageneUa, 509.
Lagenophrys, 604.
Lagotia, 605.
Lagynis, 568.
Larella, 712.
Lecquereusia, 557.
Lembadion, 629.
LepadeUa, 694.
Leptocystiiiema, 722.
Leucophrys, 571, 610.
Licmophora, 771.
Licnwphorem, 768.
Limnias, 670.
Liiidia, 693.
Liosipbon, 626.
Liostephania, 813.
Liparogyra, 823.
Litbodesmium, 937.
Loxodes, 619.
LoxopbyUmn, 639.
LysieycUa, 815.

Macrobiotus, 714.
MaUomonas, 501.
Mastigocerca, 695.
Mastogloia, 924.
Mastogoma, 813.
Megalotroclia, 665.
Mcgalotrochcea, 664.
Megatricha, 614.
Melicerta, (372.
Melosira, 815.
MchmrecB, 810.
Menoidium, 502.
Meridic(S, 766.
Meridion, 767.
Mcsocenn, 93l>.
Metallacter, 537-
Metopidia, 699. _
Micrastoi-ias, 725.
MicrocodoH, 665.
Microglena, 493.
Micromega, 929.
Microtlieca, 937.
Milnesiiun, 714.
Mitophora, 644.

INDEX TO THE FAMILIES ANB GENEKA OF

INFTTSOEIA.

967

Monadhia, 130, 485.
Monns, 489.
Monema, 927.
Monocerca, 680.
Monogramina, 875.
Monolabis, 704.
Monostyla, 695.
Moniira, 698.

Nassula, 625.
Naiinema, 927.
NaAacida, 892, 938.
Naviculece, 892.
Nitzsclua, 779, 940.
Noteus, 707.
Notogonia, 700.
Notommata, 681.

Octoglena, 690.
Odontidium, 775.
Odontodiseus, 832.
OScistes, 663.
(Ecistina, 663.
Ompbalopelta, 841.
Omphalotheca, 865.
Oncosphenia, 768.
Opalina, 569, 627.
Opalinaa, 569.
Opercularia, 592.
Ophidomonas, 509.
Ophrydina, 598.
Oplirydium, 599.
Ophryoccrcina, 630.
Ophryodendron, 568.
Ophryogleiia, 638.
Opisthioti'iclia, 614.
Otostoma, 639.
Oxytricha, 640.
Oxytrichina, 639.
Oxyrrhis, 512.

Pamphagiia, 551.
Pandorina, 157, 517.
Panoplirys, 627.
Pantotrichum, 573.
Pararaecium, 634.
Fediastreee, 24, 752.
Pediastrum, 754.
Pelecida, 629.
Penium, 750.
Peranema, 545.
Peridiniaa, 574.
Peridinium, 576.
Periptera, 865.
Peristephania, 824.
Perithyra, 842.
Peronium, 501.
Phacelomonas, 494.
Phacotug, 513.
Pliacus, 511.
PhiaUna, 623.
Philodina, 70.5.
PhilodiiKea, 700.
Phlyctsenia, 925.

PllYTOZOA, 485.

Pinnularia, 892.

Plagioguatba, 692.
Plngiogramma, 773.
Plagiotoma, 571, 627.
Pleurodesmium, 860.
Pleuromonas, 502.
Plem-onema, 639.
Pleurosiphonia, 915.
Plem-osigma, 915.
Pleurotrocha, 679.
Ploeotia, 512.
Ploesconia, 647.
Podocystis, 772.
PodocUscus, 815.
Podopkrya, 561.
Podosira, 815, 938.
Podosphenia, 769.
Polyartkra, 686.
Polyselmis, 540.
Polytoma, 504.
Pompholyx, 712.
Porocyclia, 823.
Porpeia, 850.
Prorocentrum, 509.
Prorodon, 612.
Prorostauros, 915.
Protozoa, 199, 547.
Pseudo-difflugia, 557.
Pterodina, 711.
Ptygura, 661.
Ptyiidium, 615.
Pyxidicula, 824.

Eattulus, 688.
Ehabdomonas, 503.
Ebabdonema, 804.
Ebapbidogloea, 925.
Ebaphoneis, 791.
Ebipidopbora, 769.
EinzopoDA, 243.
Ebizonotia, 885.
Eliizosolenia, 865.
EoTATOKiA, 392, 649.
Eotifer, 702.

Salpina, 697.
Sacculus, 662.
Scandium, 686.
Scenodesmus, 753.
Sceptroneis, 772.
Scbizonema, 927.
Schieonemcce, 924.
Scypbidia, 596.
Siagontbcrium, 614.
Sorastrum, 755.
Spatbidiiun, 611.
Spboerosira, 524.
Sphjerozosma, 723.
Spbonella, 886.
Spbenodoria, 557.
Spbenosira, 892.
Spirilliiia, 554.
Spirillum, 533.
Spiroclifuta, 533.
Spirocbona, 598.
Spirodisciis, 537.
Spiromonns, 502.

Spirostomiim, 622.
Spirotajnia, 751.
Spondylomorum, 505.
Spondylosium, 724.
Sporonema, 537.
SquameUa, 700.
Squamulina, 558.
Staurastrum, 737.
Staua-ogramma, 915.
Stauroneis, 911.
Stauroptera, 911.
Staurosira, 791.
Stentor, 581.
Stephanoceros, 668.
Stepbanodisciis, 823.
Stepbanogonia, 814.
Stepbanoma, 529.
Stepbanops, 699.
Stepbanopyxis, 826.
Stepbanosira, 823.
Stepbanospbtera, 164, 529.
Sticbotxicba, 644.
Stigmapbora, 923.
StriateUa, 803.
StriatellecB, 803.
StylobibUum, 805.
Stylonycbia, 643.
Surirella, 794.
SurirellecB, 783, 940.
Symbolopbora, 833.
Synapbia, 528.
Syncbaeta, 685.
SjTQcrypta, 519.
SyncycUa, 879.
Syndendrium, 866.
Synedra, 785.
Synedrea, 940.
Symira, 519.
Syringidium, 866.
Systepbania, 832.

Tabellaria, 807.
Tapbrocampa, 692.
Tardigh-vda, 713.
Tardigrada, 714.
Terpsiuoe, 859.
Terpsinoeee, 858.
Tessella, 804.
Tetmomorus, 746.
Tctracbastrum, 724.
Tetracyclus, 806.
Tetraniitus, 601.
Tetrasiphoii, 713.
Tbeorus, 690.
Tiiitinnus, 600.
Toxonidia, 920.
Trachelina, 016.
Traclielius, 618.
Tracbclocerca, 630.
Trncliclomonas, 510.
Treporaonns, 499.
Triarllira, 688,
Tricci-aliiuii, 853, 939.
Tricboda, 008.
Tricbodiim, 583.
TrichocUscuB, 661.

968

INDEX TO THE FAMILIES AND QENEHA Or lOTTSOEIA.

Trichomonas, 500.
Trinema, 556.
Trioplitlialmus, G89.
Ti-iploceras, 747.
Tryblionella, 792.
Trypemonas, 513.
TurbaneUa, 381.
Tubicolaria, 668.
Typlilina, 702.

Urceolaj'ia, 596.
Urocentrum, 585.

Uroglena, 520.
TJroleptus, 637.
Uronema, 616.
Urostyla, 643.
UveUa, 492.

Vaginicola, 601.
Vaginifera, 598.
Vibrio, 532.
Vibrionia, 184, 529.
Volvocina, 144, 514.
Volvox, 180, 526.

Vorticella, 585.
Vorticellina, 579-

Xanthidium, 735.
XantliiopyxiB, 826.

Zoogloea, 537.
Zooteirea, 563.
Zoothamnium, 594.
Zygoceros, 850.
Zygosehnis, 544.

THE END.

PRINTED BV TAYLOR AND KRANCIS, RED LION COURT, FLEKT STREET.

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