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APEX AG SSTZ
Hibrary. of the Museum
OF

COMPARATIVE ZOOLOGY,

|

AT HARVARD COLLEGE, CAMBRIDGE, MASS.

Founded by private subscription, in 1861.
|

Deposited by ALEX. AGASSIZ.

No. dX NAO:

AN INTRODUCTION

TO

ANTM MOR PEO OGY:

ANY INTRODUCTION

ANIMAL MORPHOLOGY
Systematic Zoology.

BY

ALEXANDER MACALISTER, M.B. DuBL.,

PROFESSOR OF COMPARATIVE ANATOMY AND ZOOLOGY, UNIVERSITY OF DUBLIN.

PART I.—INVERTEBRATA.

LONDON :

FON GNA NS. GR EE Ny AND ¢O.
“7876.

- Av it
Ph ; AAO AG |4 ‘
t, PA
DUBLIN : 4
. Printed ut the University Press.
% vr - : “ af Pal kam Te r

‘
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bh ‘ Mee
r a ee ae " ee eh ,
\ ' . ; ,
my f\, iy ey a } AV el, at | ae? |

t ‘ 4 [

lve aa i 2 ON Oe

—}>—__.

THE study of Biology in the University of Dublin
has been within the last few years greatly en-
couraged by the introduction of Natural Science
into the Undergraduate Course, and by the exten-
sion of the means of practical instruction in Zoology
and Botany. .

In teaching Zoology and Comparative Anatomy,
I have found that Students desire to have a text-
book in their hands to enable them to learn the
terminology of the science, and by giving them a
connected view of the varieties of animal forms,
to assist them in remembering the practical instruc-
tion of the class-room.

There are in English many good works on special
provinces in Animal Morphology, and this Manual
is not intended to supplant such books, but to fit
Students for the profitable perusal of such works
as those of Rolleston, Huxley, Flower, &c.

vi Preface.

To reduce my lecture notes to a suitable size, I
have had to condense many parts to the smallest
bulk, and to leave out many matters of detail, such
as many of the recent embryological researches of
Lankester, Metschnikoff, Kowalewsky, and others.

I regret that, owing tothe long time that this
work (written in 1873) has been going through the
press, I have not been able to introduce into it
references to recent discoveries, such as that of the
unisexuality and tracheal system of Peripatus, &c.

For the sake of Junior Students, I have printed
the chief paragraphs in larger type, the details in
smaller, so that the general principles can be more
easily grasped.

I make no claim to originality, but have bor-
rowed largely from Gegenbaur, Carus, Haeckel,
Huxley, Lankester, Van Beneden, Schmarda, and
others. I have endeavoured to avoid the errors of
second-hand quotations, and of making extracts from
other Manuals, which are easily accessible to Stu-
dents; and, having been for fifteen years engaged
in the practical study of Comparative Anatomy, I
have been enabled to verify very many of the state-
ments herein made.

I return my best thanks to Mr. H. W. Mackintosh
for his valuable assistance in correcting the press,
and to Professor Reynolds for some suggestions in
Chapter I.

Preface. Vil

I regret that some errors have escaped notice in
correcting the proofs, the most serious of which is
that of Fig. 4, p. 59, which should read Heliophrys
variabilis, Gvreef, instead of Heliosphera radiata,
Sch.

eo. Ce :
e * ¢e > at
Lena? ay eh eae
; hs
Vial, is aa

GOUN TLE AES:

CHAPTER LE

Protoplasm.—Its properties and derivatives. Plastides, .

CHAPTER IT:

General Morphology.—Organs, and their groupings, .

CHAPTER: Tit:

Histology.—Epithelium and connective tissues, . .

CHAPTER TV:

Histology.—Muscular and nervous tissues,

CHAPTERS.

Tectology.—Individuality and the formation of organs,

CHAPTER. VE.

Reproduction.—Species, type forms, correlations of growth, parasi-
tism, degradation,

PAGE.

20

ot

Contents.

CHAPTER, Vit.

Distribution of Animals.—Primary classification,

CHAPTER VIL.

Sub-kingdom I.—Protozoa.—Class 1, Monera; Order 1, Gymno-

Class

Class

monera; Order 2, Lepomonera. Class 2, Labyrinthulez.
Class 3, Rhizopoda; Order 1, Imperforata; Order 2.
Perforata. Class 4, Flagellata; Order 1, Monadina;
Order 2, Noctiluce. Class 5, Protoplasta; Order 1,
Catallacta; Order 2, Amcebina; Order 3, Heliozoa, °

CHAPTER IX.

6, Radiolaria; Order 1, Monocyttaria; Order 2, Poly-
cyttaria. Class 7, Gregarinina, :

CHAPTER X.

7, Infusoria; Order 1, Opalineze; Order 2, Peridiniza;
Order 3, Acinetina; Order 4, Stomatoda, P

CHAPTER XI.

Sub-kingdom II.—Polystomata or Porifera; Order 1, Halisarcia ;

Order 2, Ceraospongia; Order 3, Gumminez; Order 4,
Halichondrie ; Order 5, Corticate Order 6, Acantho-
spongia; Order 7, Potamospongia; Order 8, Calcispongia,

CHAPTER XII.

Sub-kingdom III.—Ccelenterata. Class 1, Hydrozoa; Sub-class 1,

Hydroida ; Order 1, Eleutheroblastea,

CHAPTER XIE

Order 2, Gymnoblastea,

CHAPTER -XTY..

Order 3, Calyptoblastea ; Order 4, Monopsea,

PAGE,
~~ 42
49
60

66

84

93

Contents. Xi

CHAPTER XV.
PAGE.

Sub-class 2, Siphonophora; Order 1, Calycophoride; Order 2,
Physophoride. Sub-class 3, Calycozoa; Order 1, Lucer-
naride, . - : : : : - c 3 : 96

CHAPTER XVI.

Sub-class 4, Discophora; Order 1, Rhizostomida; Order 2,

Pelagiada, - ; c - ° 3 : : a 102
CHAPTER XVII.

Sub-class 5, Ctenophora; Order 1, Eurystomata; Order 2,

Saccate; Order 3, Tzeniatz ; Order 4, Lobatz, : 5 . 106
CHAPTER, XVIEI.

Class 2, Actinozoa; Sub-class 1, Zoantharia; Order 1, Malaco-
dermata; Order 2, Sclerodermata ; Order 3, Antipatharia,

Coral reefs, . : ; : : ; F ‘ ‘ GG
CHAPTER XIX,

Sub-class 2, Alcyonaria ;’ Order 1. Alcyonaceze; Order 2, Tubipo-
racee; Order 3, Pennatulacez; Order 4, Gorgonacez ;
Order 5, Isidaceze ; Order 6, Briareaceze ; Order 7,' Coral-
liacez, . - ‘ : : ‘ * 3 ‘ ‘ DLS

CHAPTER |XX.

Sub-kingdom IV.—Echinodermata. Class 1, Stellerida; Order 1,
Blastoidea; Order 2, Cystoidea; Order 3, Crinoidea; Order 4,
Ophiuroidea ; Order 5, Brisingoidea; Order 6, Asteroidea, . 12

Ge

CHAPTER. 2Xr.

Class 2, Echinoidea ; Order 1, Tessellata; Order 2,Euechinoidea, . 137

Xil Contents.

CHAPTER XXII.

PaGg.
Class 3, Holothuroidea; Order 1, Apneumona Order 2, Tetra-
pneumona; Order 3, Dipneumona, . 5 : : 5 . 148
CHAPTER XXTI.
Sub-kingdom V.—Vermes. Province 1, Archzostomata. Class 1,
Turbellaria; Order 1, Dendroccela ; Order 2, Rhabdoccela ;
Order 3, Nemertidea, 5 3 : : : 3 . 154
CHAPTER XXIV.
Class 2, Cotylidea; Order 1, Cestodea, , . : : 5 . 164
CHAPTER XXV.
Order 2, Trematoda, . ‘ : ; : ‘ ‘ : : 172

CHAPTER XXVI.

Class 3, Nematelmia’ Order 1, Gordiacez ; Order 2, Nematoda, ATE

CHAPTER XXVII.
Class 4, Acanthocephala, Class 5, Gephyrea; Order 1, Inermia ;

Order 2, Armata, ouI87
CHAPTER XXVIII.
Class 6, Rotatoria ; Order 1, Gasterodela; Order 2, Holotrocha ;
Order 3, Schizotrocha; Order 4, Zygotrocha, . « ; Bio!
CHAPTER XXIX,
Class 7, Hirudinea. Class 8, Onychophora, : : : , . 198

CHAPTER XXX.

Province 2, Deuterostomata, Enterocela. Class 9, Cheetognatha.

Class 10, Enteropneusta, . . 206

Contents.

CHAPTER XXXI.

‘Deuterostomata Schizoceela. Class 11, Cheetopoda, .

CHAPTER XXXII.

Deuterostomata Epiccela. Class 12, Bryozoa; Order 1, Gymnole-
mata ; Order 2, Phylactolemata,

CHAPTER XXXIIT,

Class 13, Tunicata,

CHAPTER XXXIV.

Sub-kingdom VI.—Mollusca. Division, and Class 1, Brachiopoda;
Order 1, Ecardines ; Order 2, Testicardines,

CHAPTER XXXV.

Division 2, Otocardia. Class 1, Lamellibranchiata; Sub-class 1,
Endocardines ; Sub-class 2, Exocardines; Order 1, Mono-
mya; Order 2, Heteromya; Order 3, Isomya, .

CHAPTER XXXVI.
Class 2, Cephalophora ; Sub-class 1, Scaphopoda ; Sub-class 2,

Pteropoda; Order 1, Thecosomata; Order 2, Gymnosomata, .

CHAPTER XXXVII.

Sub-class 3, Gasteropoda; Order 1, Branchiata; Order 2, Pul-
monata, 5

CHAPTER XAXVITT:
Class 3, Cephalopoda ; Order 1, Tetrabranchiata; Order 2, Dibran-
chiata, ;

CHAPTER XXXIX.

Sub-kingdom VII. — Arthropoda; Division 1, Branchiopoda.
Class 1, Crustacea, .

. >

Xul

PAGE.
. 209

5 ORAM

6 ai

- 255

. 280

us
=
eo

ye
BTS)
~I

XIV Contents.

‘CHAPTER XL.

Sub-class 1, Cirripedia; Order 1, Thoracica; Order 2, Abdo-
minalia; Order 3, Apoda; Order 4, Rhizocephala, .

CHAPTER ET:
Sub-class 2, Copepoda; Order 1, Gnathostomata ; Order 2, Sipho-
nostomata. Sub-class 3, Ostracoda. Sub-class 4, Bran-

chiopoda; Order 1, Cladocera; Order 2, ae Sub-
class 5, Trilobite, . - -

CHAPTER XLII.

Sub-class 6, Pcecilopoda. Sub-class 7, pir caret: ; Order +e
Decapoda; Order 2, Stomapoda,

CHAPTER XLIII.
Sub-class 8, Edriophthalmia; Order 1, Cumaceze ; Order 2, Leemo-
dipoda ; Order 3, Amphipoda; Order 4, Isopoda,
CHAPTER: XULY.
Division 2, Tracheopnoa. Class 2, Arachnoidea. Sub-class 1,
Pseudarachna ; Order 1, Pantopoda; Order 2, Tardigrada.

Sub-class 2, Autarachna; Order 1, Acarina; Order 2, Ara-
neina ; Order 3, Arthrogastra,

CHAPTER, XLV.

Class 3, Myriopoda; Order 1, Chilognatha; Order 2, Chilopoda ;
Order 3, Pauropoda, - : - : -

CHAPTER XLVI.

Class 4, Insecta,

PAGe.

- 343

- 346

- 351

5 2G)

- 363

Sead

. 383

Contents. XV

CHAPTER XLVIT.

PAGeE.
Sub-class 1, Ametabolica; Order 1, Mallophaga; Order 2,
Rhynchota; Order 3, Thysanura; Order 4, Thysanoptera ;
Order 5, Euplexoptera ; ‘Order 6, Orthoptera, . : : - 398

CHAPTER XLVHI.

Sub-class 2, Holometabola; Order 7, Neuroptera; Order 8,
Trichoptera; Order 9, Strepsiptera ; Order 10, Aphaniptera};
Order 11, Diptera; Order 12, Lepidoptera; Order 13, Coleop-
tera; Order 14, Hymenoptera, . : : 4 : dS

INTRODUCTION
TO

en SEAL sMO RPE O LOGY.

=

CoxAP PERK i,

THE group of colloids called Albuminoids is the most
complex and unstable series of bodies known to the
chemist, and, as we are as yet ignorant ofthe nature of
their apparently definite compounds, we know nothing
of their molecular constitution.* The phenomena of
lifet are always associated with and manifested in a
viscid, transparent, colourless, unstable albuminoid,
whose two special properties are contractility and the
power of converting other Carbon, Hydrogen, and
Nitrogen compounds, into a material like itself. An
ammoniacal solution of carmine stains it crimson. Of

* Albumen is slightly acid in reaction, and forms compounds with Ba,
Ca, Pb, K, Na, &c., the last pair being probably the protein of Mulder.
Schwartzenbach regards its compound with Platino-cyanide of Potassium
as being definite, but this is not confirmed by Diakonow’s analysis.

+ Which are motion, cyclical change, the evolution of heat, and the assi-
milation of other materials. Life is now generally regarded as a mode of
energy.

B

2 Introduction to Animal Morphology.

this body (Protoplasm or Bioplasm), white blood
corpuscles, the yelk spheres of eggs, the contents of all
growing cells, are examples. This substance shows
three forms of motion under different conditions :—1st.
When diluted with water, internal currents indicated
by the circulation of enclosed particles, the outline of
the mass being unaltered; a more definite motion than
the Brownian cyclosis of non-living fluids, and con-
nected with chemical change. 2nd. Motion attended
with change of form, irregular contractions of the whole
mass, with temporary protrusions at one part (called
pseudopodia),and recessions elsewhere; thus locomotion
can take place.* This form of motion may be changed
into the first by dilution, or the former into it by the
action of a weak (27) solution of NaCl, 3rd. Ciliary
motion,t the protoplasm mass having on its surface
constant hair-like processes of its own substance}
(cilia), rapidly vibrating to and fro, either from within
(as in spermatozoa) or from the outer layer of the mass.
Long whip-like cilia are called flagella, if sub-rigid,

* Thus Amcebe wander in the waters wherein they live, and white
blood corpuscles through the tissues of the bodies of higher animals, as
Waller, Recklinghausen, and Cohnheim have described. Such cells are
probably used as tissue-pabulum, as Young noticed in connective tissue,
Biesiadecki and Pagenstecher in epithelium, and Stricker, &c., in deve-
loping embryos.

+ Gegenbaur regards ciliary motion as different from protoplasmic.

t Flagella have been seen changing into pseudopodia in Protomyxa
(Haeckel) and in Myxomycetes (De Bary). The converse, or cilia changing
into pseudopodia, occurs in Magosphaera (/aeckel), Cilia are never out-
growths from a cell-wall, nor vacuolated nor granular. The granules
observed by Alexander Stuart in Opisthobranchiata have not been con-
firmed by others. Stzarvt has also described fine lines passing from the
cilia to the cell nucleus, which by contraction moved the nucleus! Pro-
bably these are of the nature of the longitudinal strie found by Zéerth in
cells of ciliated epithelium.

Introduction to Animal Morphology. 3

styl’, A flagellum originates as a process from the
protoplasm mass, which first undulates, then becomes
globular, and finally elongates (Emgelmann). In the
formation of a row of cilia the undulating knob
elongates into a ridge, which splits into parallel bands,
rapidly changing into cilia. The rate of motion of
cilia varies per minute from 720* to 480 (Ezgelmann),
190 (Krause), 150-100 (Valentzn).

The effects of reagents on protoplasmic motions are as
follows :—1. Very weak alcohol, moderate heat,} and very
diluted alkalies favour motions of the znd and 3rd form.
2. Ether, strong alcohol, chloroform, stop motions and render
the mass granular. 3. Hydrocyanic acid arrests movements.
4. Vegetable alkaloids, asa mule, affectthem but little. 5. Weak
acetic acid causes irregular contractions, and finally checks
motion. 6. Fresh water makes protoplasm masses spherical
and develops the first form of motion.{ 7. Carbonic acid de-
stroys ciliary action (Kzhne), but the access of air, if resorted
to speedily, restores it. 8. Hydrogen checks ciliary action,
but cilia thus stopped, if soon exposed to carbonic anhydride,
are at first set in motion, and then finally stop (Engelmann).
g. Cold checks amceboid motion and rotation of the yelk-
spheres, but (if not excessive) only retards, but does not
arrest, growth or life-progress. 10. Weak induction currents
accelerate amceboid motions or produce contraction (Kuhne,
Golubew); they also accelerate ciliary action (Kzs/zakowsky).
Every variation of intensity of the current acts as an excitant,
producing alternate contractions and relaxations. The
closure of a constant current is a stronger stimulus than the
opening. Strong currents stop all motions (Zxgelmann).

* T observed this rate in Planaria.

+ Moderate heat accelerates the motions of cilia (Weber), and the loco-
motion of corpuscles, which is greatest at 100° F. (Schultze). Yelk
masses contract and dilate at 90° F. (Peremeschko). 113° F. coagulates
protoplasm.

t The spherical state may be strong contraction (Azkne) or rest
(Hermann).

152

4 Introduction to Animal Morphology.

Protoplasmic motion is sometimes attended with- the
evolution of gas.* In an atmosphere of Hydrogen and in an
oxygenated solution of Hemoglobin, cilia move until the free
oxygen is gone (Azhne), but under some conditions vibra-
tions continue for a time without oxygen and without food, as
if the mass had in itself a store of energy.

The first stage of decomposition in protoplasm is
indicated by the formation of granules, and the disen-
gagement of fluid or gas making little clear spaces
(vacuoles). On account of the constantly occurring
partial contractions, homogeneous protoplasm masses
are rarely of large size, except where feebly acted on
by external stimuli; usually they split into smaller
particles. The contact of air, of oxygenated water, or
other stimuli, seems to cause the surface to undergo
chemical change; it ceases to be protoplasm, and be-
comes a limiting membrane, through deficiencies in
which protoplasmic threads may protrude (cilia ?)

As this material is constantly decomposing, new
protoplasm needs to be as constantly forming, but its
production is often irregular, and may proceed more
actively in one spot than elsewhere. Such a spot is
usually denser, and takes a deeper carmine dye than
the rest of the mass, and is often sharply defined. It
is called the nucleus, but it is not essential to growth,}

* As in Arcella (Zngelmann). Protoplasm is normally neutral or
slightly, alkaline, but after exhaustion of motion it is faintly acid, and some-
times weak alkalies revive for a time suspended motions. Possibly the
contraction may be the result of the force evolved by oxidation. The
contractions in a mass of protoplasm are always partial ; one side ofa cilium,
or one part of a mass contracts, and drags the rest after it. The evolution
of light in animals is sometimes attended with the decomposition of proto-'
ge into urate of ammonia. t+ Often porous.

{ Many cells have no nuclei, as all Monera, Hydrodictyon (Alga), the
scoeneen spheres of ova, &c.

Introduction to Antmal Morphology. 5

nor has it any properties other than those of any other
particle of vigorous protoplasm.* It may be granular,
sometimes vacuolated (/o//e¢t), and often has a denser
spot within it called the nucleolus. Each independent
protoplasm mass is uamed a plastide; a plastide with
no nucleus is a cytode; a nucleated plastide is a cell;
a naked cytode is called a gymnocytode; one invested
by a membrane is a lepocytode; a naked cell isa
gymnocyte (monoplast Sharfey); one with a cell-
membrane is a lepocyte (@ckel). The largest single
cells are the myeloplaxes of growing bones and the
muscle cells of Nematodes.

Plastides multiply by gemmation, a bud arising as
a small process from a parent cell, then enlarging and
becoming detached ; by fission, each splitting into two
or more nearly equal parts—in this process the nucleus
may or may not take partt;—by free cell formation,
nuclei arising in a mass of protoplasm, and around
each an area of protoplasm becoming isolated by
the differentiation of cell-membranes—this occurs in
developing embryos ;—by endogenous formation, as
shown by Wezssmann in the eggs of Diptera, and by
E. Van Beneden in the formation of the nucleus in
Pseudofilaria of Gregarina gigantea.{ It occurs pa-
thologically in tumours.

* Gegenbaur states that the nucleus differs from the surrounding pro-
toplasm by being non-contractile, but Adticher has demonstrated that a
free nucleus or a nucleus removed from a cell contracts actively. Mewmann
describes the nucleus as showing motions in dying cells. Free nuclei may
exist in masses of protoplasm.

+ Remak and Weiss have seen cells divide while the nucleus was ad-
herent to oneside. The same has been noticed by many other observers.

t The multiplication of cells in cartilage, some tumours or ova, is
ecetiines regarded as of this kind, but in reality it is more likely a con-
cealed form of fission. The instance given by Buhl of the formation of

6 Introduction to Animal Morphology.

In the simplest animals the protoplasm is homo-
geneous, but in the more complex the homogeneous
yelk protoplasm becomes differentiated in development,
and thus we find cells whose contents vary. It has
been supposed that protoplasm may be a compound
albuminoid resolvable into its elements (myosin, neurin,
&c.) in the course of growth; at least two substances
may be identified in it, one of which is active and
dilates on dilution with water, while the other is not.*
All cells are at first protoplasmic, whatever their ulti-
mate contents may be, and protoplasm seems to
possess the sum of the properties of the active cells
(muscle and nerve) derived therefrom. The chief ma-
terials derived from protoplasm in animals I have
appended in a note.t

To complete our introductory studies, it may be

pus cells within epithelial is more probably a case of wandering (Steudeler
and Volkmann).

* Heidenhain and Briicke suppose some cells to have a lacunary
structure, with a basis of a more solid albuminoid and a more fluid proto-
plasm contained therein.

+ Protoplasm derivates are of two kinds, Nitrogenous and non-
Nitrogenous, The first are :—

Albumen, C7HioNigSO2H,O, soluble in water, not precipitable by
alkaline carbonates nor sodium chloride, but is by heat. It varies in pro-
perty according to its source. Seralbumen (from blood serum) is not
coagulated slowly by ether. Ovalbumen is, and when injected under the
skin of an animal, speedily appears in the urine, which the other does not.
The ovalbumen of Raptorial birds is with difficulty coagulated by heat or
acid (Frémy and Valenciennes). In some swimming birds and reptiles the
ovalbumen, when diluted, is slowly coagulated by heat.

Globulin is insoluble in water, soluble in sodium chloride, coagulated
by heat, changed into acid albumen or synztonin by HCl; varieties of it are
Vitellin, not precipitable by NaCl, when added in substance to saturate
its solution ; JZyosim is thus precipitable. Paraglobulin or Fibrinoplastin,
when combined with another albuminoid 7b77nogen, forms fibrin, as in the
coagulation of blood,

Introduction to Antmal Morphology. 7

observed that the following inorganic materials are
found in animal bodies :—Oxygen in all the fluids,
Hydrogen in the intestinal gases of vertebrates
with H:S, Carbonic acid in all tissues, Calcium
Fluoride in bones and corals, Magnesium Fluoride in
some corals, Water in all tissues from enamel which
contains o*2 per cent. to the connective tissues of jelly
fishes with 99°5 per cent., Sodium Chloride also in all

Peptone is a dialysable form of albumen formed in the process of
digestion, not precipitable by heat, dilute acids, nor alkalies.

fibrin is insoluble in water or NaCl, swells in dilute acids, and this
softened form is coagulated on boiling; found in blood.

Casein is probably a mixture of 474. with a non-albuminous substance,
which is separated from it in digestion as a dyspeptone; soluble in alkalies,
coagulable by mineral acids, precipitable by lime and magnesia salts, in-
soluble in water or NaCl.

Keratin, the material of the cell-wall in epithelium, resembles casein
in many of its properties; it may be a compound of several albumen-
derivates.

Gerhardt regards these as similar in composition, but differing in
molecular arrangement. Zebonte and others regard them as each com-
posed of several radicles united in different proportions. From these are
derivable the following nitrogenous non-albuminoids :—

Protagon, present in nerve tissue. A mixture of Cerebrin C1;H3;NO3,

O;CigH310
with Lecithin, a body derived from ) O;CisH3;0
Glycerin C3H’’s O,;PO { OH
OC2Hy (CHs)3N,;OH,

Leucin CgHi, (NHz) O2 present in the tissues of Arthropods, in
pancreatic juice, &c. Zyrosin CgHyNO3 found with Leucin and in
Cochineal.

Kreatin C4HgN302H20 in smooth muscle, and with Kreatinin (CgH;N30)
in blood and muscle. Gwanin C3HsNsO in Cestodes and Siphonophora,
fishes and birds. Sarkzzin the muscles of hares and ruminants. Xanthin

CsH4N,O2, and Urea CO {NEL and Uroxanthin in urine. Chlorophyll

CigHzoN2O; in Turbellaria and some green annelids. d/ucim in mucus,
connective tissue, synovia. Lzmacin and Helicin are two varieties of it in
the slime of Mollusca. Collagen, in the intercellular substance of fibrillar
connective tissue is converted into Gelatin by boiling water or boiling

8 Introduction to Animal Morphology.

tissues, Calcium Carbonate either in a crystalline or
nodular form, usually the latter, in forms similar to
those assumed by it in deposits from viscid solutions
(see Harting, Verhandelingen der Koninklijke Akad.,
Amsterdam, 1873, 13 Deel, p. 4), Nitrogen in the
swim-bladder of fishes, &c., Hydrochloric acid in
the gastric juice, Sulphuric acid in the saliva of
Dolium galea, &c.

dilute acids, gelatinizing on cooling, precipitable by alcohol, corrosive
sublimate, &c.

Chondrin, formed by boiling chondrogen, which forms the hyaline
basis of cartilage, CigsH2sN2O; precipitable by acetate of lead, alum, but not
by mercuric chloride.

Ossein from the intercellular substance of bone resembles Gelatin in
most of its properties, but is more soluble.

Elastin from yellow elastic tissue is insoluble in water, alkalies, and
most reagents, except strong solution of Potass.

Spongiolin, allied to Keratin, is the element making the horny skeleton
of sponges.

_ Conchiolin, allied to Gelatin, is the animal element in the shells of
Mollusca.

Acanthin, like Spongiolin, is the substance which composes the spicules
in some Radiolaria.

Neossin, like Gelatin, is the element of which the Edible Birds’ nests
are made.

Chitin, the indurating material of the integument of Arthropods,
C2HgsN201 insoluble in all ordinary reagents, except in strong mineral
acids.

The non-nitrogenous elements are fats, which consist of the following :—

O.CigH3,0
Geese Gols: O.C;3H350
O.C\gH35;0
O.CigH330
Olein C3H"’’s O.CisH330
O.CigH330
O.CigH310
Palmitin C,H’"s O.CigH31:0
O.C\gsH310

OH
; : a by the substitution of acid
These are derived from glycerin C,H’’s on radicles for hydrogen, ~

Introduction to Animal Morphology. 9

We know little regarding the genesis of any of the
albuminoids or of the conditions under which proto-
plasm is formed. Analogy favours the possibility of
the artificial formation of this substance, as we can
form fibrin, casein, &c., from their isomeric relatives.
This hypothetic production of protoplasm is called
Abtogenests or <Archebtosts. Experiments* on this
point have been made by exposing albuminous in-
fusions to high temperatures, and then hermetically
sealing them in vessels. In the course of time minute
plastides have been found herein, which are called, if
straight, Bacteria, if coiled, Vibriones and Spirilla.
If Bacteria be destroyed by a heat of 140° F., and if
the fluid have been raised above this point, the reason-
ing is that the subsequently developed plastides are
formed by Abiogenesis ; but Coz has shown that in
clumps Bacteria may escape destruction even at a

It was long supposed that another body, to:which the name Margarin
was given, existed in animal fats, but its presence in such fats is doubtful. -
Some special fats are Beeswax, which consists of melissyl palmitate
(CsoH1, CigH3102), cerotic acid HC27Hs302, and cerolein.
_ Butters from milk contain olein, palmitin, butic acid (HC2oH50.), and
Butyric acid (HC4H,02), and sometimes other acids with glycerin.

Spermaceti or cetin consists of cetyl palmitate CigHs3, CisH,,O0,, and
yields on saponification an alcohol-like body named Ethal €,sH,,,OH-

Cellulose CgsHyO; is. found in the mantles of Tunicates. Starch
exists in some Infusoria. Glucose is found in insect secretions, &c.
Jnosite, in flesh ; Lactose CxH,,0n + H,0, in milk ; Trehalose Cy2H,,O11
+ 2H,O in the larva of Larinus nidificans; Scyl/ite, in shark’s flesh ;
‘Glycogen (CgH0O5); in the liver. Besides these are numerous other prin-
ciples, components of secretions in several glands.

* The conditions of the development of life in such experiments are :—~
An albuminoid fluid, moderate heat, oxygen and light. Even a partial
‘vacuum does not prevent the formation of bacteria. asian found bacteria
in a sealed solution of ammonic phosphate and sodic phosphate,-and of
antimonic potassiotartrate,

10 Introduction to Animal Morphology.

higher heat, and Calvert has shown the same regarding
Vibriones. Many of these experiments indicate the
existence of some hidden fallacy, as the organisms
produced are by no means the lowest, but compara-
tivelycomplex. The hypothesis that every protoplasm
mass is the produce of a pre-existing protoplasm is
known as Biogenesis or Panspermism.

CHAPTER IT.
GENERAL MORPHOLOGY.

PLASTIDES continuously grouped form /zsswes, which
vary according to the nature of their components and
of their intercellular substance. The fusion of cells
within a common investment constitutes the simplest
tissue (Cytocormi, possibly the condition in some
Protozoa). Continuous groups of similar cells (each
with its own wall) constitute homoplastic tissues, as
simple cartilage, hair, cuticle, &c. ; if the cells be dis-
similar, or if the intercellular substance be abundant,
they form a heteroplastic tissue,* as connective tissue,
muscle, nerve, &c. Each set of heteroplasts may
make an entire animal (as in some Radiolaria), or in
the body of a more complex animal they form an
organ-system (as the dermal, skeletal, muscular, &c.),
and these systems are part of a more complex
functional grouping or apparatus, as the locomotory
(of the muscular and osseous systems), circulatory,
respiratory, &c. The grouping of heteroplastic organs

* Heteroplasty is the method whereby physiological divis‘on of labour is
aecomplished,

Introduction to Animal Morphology. II

into systems is morphological, into apparatuses, phy-
siological.

The simplest animals are plastides or homoplastic
aggregates. In higher forms greater differentiations
occur, and when heteroplasts are grouped into organ-
systems, these are generally symmetrically arranged,
similar heteroplasts being placed side by side around
ahorizontalaxis. Thusastar-fish consists of segments
or groups of organ-systems, each built upon the same
plan, placed radially around a centre. Such segments
may be called antzmeres (Haeckel), They vary in
number: each segment of a bilaterally symmetrical
animal (Vertebrate or Arthropod) has two; some
Radiolaria, three; Meduse, four; many Echinoderms,
five; Zoantharia, six; Luidia, seven; Ctenophora,
eight, &c. The increase of a function may be pro-
vided for by a multiplication of organs, or a more
complicated development in those already existing.
Of these methods the former seems the simpler, hence
the next step in complexity is the formation of a chain
of similar groups in succession. To each element in’
this chain is given the name mefamere. These seg-
ments may be similar, as in the case of the zonites of
a worm, or else some may be specialized. The whole
chain constitutes a fersona,* in which the metameres
are usually successional (catenated), or else lateral
(fruticose). The highest degree of aggregation in the
animal kingdom is the colony, in which a number of
persone are united on a common stem as among the
compound Hydrozoa.

* The name Zersona may be given to one of the component elements of
a colony, whether it be built up °f metameres or no, although SS it
should be limited 1o such as are so composed,

12 Introduction to Animal Morphology.

- In comparing one persona with another, we call
such parts homologous as are of equal morphological
value, so that if the two compared forms were descend-
ants from a common parent, the homologous parts
would be developed from the same parts of the embryo;
_ thus the wing of a bird and the fore-limb of a horse
are homologous. Homologies may be complete or
incomplete, according as the organs compared are in
whole, or in part only, the equivalents of each other.
Thus the humerus of man and that of the frog are
completely homologous, while the heart of a fish and
that of a man are incompletely so. In comparing
different metameres of the same persona, correspond-
ing parts are said to be homodynamic (homotypical,
or serially homologous); thus fore and hind limb are
homodynamic parts. Incomparing different antimeres
of each metamere, the corresponding parts are said to
be symmetrical. In each antimere, if organs are re-
peated, the repetitions are called homonomous; thus
the fingers and toes of the extremity are homonomous
segments. Parts which resemble in function, but
having no necessary structural relationship, are said
to be analogous; thusthe lungs of a bird and the gills
of a fish agree in function, but are in no sense homo-
logous. The wings of insects and of birds are likewise
analogues, but not homologues.

The science which treats ofthe form, structure, and
arrangements of parts in animals, and the laws per-
taining thereto, is called Morphology. The science
which deals with the functions, actions, and properties
of parts is called Physiology. In the following pages
the animal kingdom is viewed from a morphological
standpoint,

Introduction to Animal Morphology. 13

CHAPTER ITI.
HISTOLOGY.

THE tissues formed by the grouping and differentiation
of cells may be classified as vegetative or passive tis-
sues (connective and epithelial), and animal or active
tissues (nerve and muscle). The action of the same
forces which in a simple cell cause the formation: of a
cell-wall, inamass of cells causes differentiation of the
surface plastides into an efzthelium, whose component
cells have more or less thick, keratine walls. "When ad-
herent togethersoasto forma porous lamina,thisis called
cuticle, and in it the cell elements may not be recog-
nizable.* Cells on a surface exposed to vertical pres-
sure, or to the drying influences of the air, are scale-
liket (pavement epithelium) ; when newly formed and
unmodified, they are spheroidal ;¢ if laterally com-,
pressed, moist, and on a free surface, they are columnar
or conical,§ and this form often exhibits a covering of
cilia.|| Under special circumstances, epithelial cells

* The chitinous cuticle of Arthropods can scarcely be recognized as of
connected cells, but as far as its development is known it seems to be a
chitinization of a thin protoplasm layer.

t As on the skin, lips, tongue. It may be unilaminar (Monoderic) or
stratified (Polyderic). Sometimes its cells are spinose, ribbed, or toothed,
as on the amnion ‘of the cat (Eberth). When the cells overlap each ‘other
they are squamose ; when they touch only at their edges they are tesselated.

{ Found in glands, and in the deep new layers of stratified epithelium as
a transitional form. § Found in the digestive tract.

|| Ciliated columnar epithelium occurs in the trachea and bronchi, the
Eustachian and Fallopian tubes, &c. Ciliated spheroidal, often flattened,
cells occur in the ependyma on the choroid plexus in the human brain.
These cells send deep processes from their attached sides. Ciliated tessel-
lated epithelial cells occur in the tympanic cavity of Mammals at the hinder

edge of the membrana tympani, and directly behind the attachment of that
membran

14 Introduction to Animal Morphology.

may be elongated, fibre-like (as in the crystalline lens),
branched, ribbed, pigment-holding, or goblet-shaped,
as in the mouth of a fish or reptile, the throat of a frog,
or in the vertebrate small intestine (except in birds).
This variety has an open mouth (stoma) of naked pro-
toplasm, as have some of the ordinary cylinder cells
in the stomach of man (Schultze), or the mouth may
be partially closed by parallel rod-like particles (Bref-
tauer and Stecnach). The body of such a cell (theca) is
dilated and then narrows into a pedicle. These cells,
as having the thinnest coating, are supposed to be the
most active agents in intestinal absorption (denied by
Th. Eimer ; they are described by Avmstecn and
others, as only altered cylinder ciliated cells).*

In homoplastic animals, the fluid contents of each
cell suffice for the physiological requirements of the
animal, but growing complexity requires functional
division of labour, and some epithelial cells are
clustered together for purposes of secretion. These
may be on the surface or in a shallow or deep, simple
or branched, recess : such a structure is called a gland.
The process ofsecretion may be one of the liquefaction
and conversion of the cell contents into the material
to be cast off, as in mucous glands, in which on sec-
tion a distinct layer of metamorphosing cells may be
seen with the microscope (Lunula of Gianuzzi). In
other cases there is not the direct cell waste.

The second group of vegetative tissuest includes

* The cells of the middle layer of the epithelium in the bladder of some
Mammals are tailed, and their processes seem joined to papillary emi-
nence of the connective tissue underlying.

+ His describes these as parablastic and developed secondarily in the
embryo.

Introduction to Animal Morphology. 15

connective tissue, cartilage, bone, cornea, dentine, &c.,
characterized by having ovoid or branching cells in an
intercellular substance,* which may contain mucin,
collagen, chondrogen or ossein, all of which are mor-
phologically equivalent. In the embryo it appears as
a cluster of closely adpressed plastides with feeble cell-
walls, and is known as indifferent tissue, as its after
development into one or other of the series depends
on external influences.

The forms of connective tissue are—rst. Cellular or paren-
chymatous, consisting of rounded or fusiform cellst with a
sparing intercellular substance, sometimes little more than a
thick cell-membrane. This simple form occurs in the ectoderm
of Ccelenterata, gland parenchyma, the notochord, &c. znd.
Mucous tissue, masses of oval, spindle, or branched cells with
interlacing processes, with a copious intercellular substance
containing mucin. This exists in the discs of Jelly fishes, Tu-
nicates and Heteropoda, the gelatine of the umbilical cord of
Mammals, &c. 3rd. Retiform or areolar, fine anastomosing,
sparingly or non-nucleated fibres, swollen at their junctions,
often with amoeboid cells in the interspaces. The connective
tissue of the vitreous humour of the eye, the investing reticulum
of absorbent glands,{ the tunica adventitia of blood vessels,
neuroglia, &c., are of this sort. 4th. Blood and lymph are
connective tissues with a fluid intercellular substance con-
taining cells (see p. 32). 5th. Fibrillar tissue, cells with
long or reticular processes in fasciculi together with fibres
and coiled fibrils around each fasciculus (S¢ricker). The inter-

* Which can be demonstrated by darkening it with a weak Nitrate of
silver solution. It is altered protoplasm as shown in bone (Waldeyer), car-
tilage (Remak and fiirstenburg), connective tissue (Schultze and Beale).

+ As this form includes lymph cells in its interstices, it is called cytoge-
nous (Kdlizker), or adenoid tissue (7s).

{ For preserving these cells J/zi//er’s fluid is one of the best media. It
consists of bichromate of potass 2} parts, sulphate of soda, one part, and
distilled water, 100 parts.

16 Introduction to Antmal Morphology.

cellular structure may be white, inelastic, containing mucin,
acted on by heat, acetic acid, and liquor potasse; or yellow,
elastic, and resisting most reagents. The white form exists
in tendons, fasciz, ligaments, the basement of serous mem-
branes in all Vertebrates. Among invertebrates it exists
in Molluscs, especially in Cephalopods, in Arthropods,*
Worms (Rezchert), and Echinoderms (Leydig). Yellow tissue
occurs in the ligamentum nuche and the interlaminar verte-
bral ligaments, and is confined to vertebrates. Its fibres are at
first protoplasmic within, and continue to grow by the in-
crease of the intercellular deposit on their outer surface.
White fibres do not increase in size when once formed.
The fibres may be the outgrowths of cells or (in tendons):
fibres and cells may be simultaneously formed.{ Fat is-
sometimes laid down within the protoplasm of connective -
corpuscles, especially in the parenchymatous form (Cza-
jewicz).§ 6th. Cartilage is a form of connective tissue in’
which rounded or fusiform, rarely processed (larynx of ox) or
stellate (Nautilus, sharks), cells are contained in a rigid chon-
drinous|| intercellular matrix. The simplest form parenchy-
matous cartilage is a mass of cells with little or no matrix ;
this is found in Geryonidze and Siphonophora, the gill sup-
ports of Chztopods, Limulus,§] Cephalopods, the notochord,
the skeletons of Myxinoid fishes, &c. Hyaline cartilage
has a glassy matrix often marked with clear rings round the

* Schlossberger denies its presence in Crustacea, as the so-called fibrous
tissue in the crab’s claw contains no gelatin. .

t Nitrate of silver produces a black marking within these fibres (Reckling-
hausen), and their centre takes a carmine dye (Frey), Rollett could not
detect a tubular structure in section, and Von Wittich cae not stain the
interior with indigo.

{ Avrause regards the connective tissue corpuscle as connected with the
Iymaphatié system. He describes spindle-shaped elements (Inoblasts) as
components in tendons.

§ Sometimes fat cells have no membrane, as in Amphibia. lemming
describes fat as laid down in the tunica adventitia of blood vessels.

|| Young cartilage often does not give the reaction of chondrin.

{| The cartilage in Limulus contains chitin in its intercellular substance.
(Gegenbaur).

Introduction to Animal Morphology. 17

cells,* which are often polynuclear. This exists in the
trachea, the articular ends of bones, &c. Fibro-cartilage has
a basis of fibrillar tissue containing cartilage cells: in the
embryo it begins as hyaline cartilage, but the matrix fibrillates
(Rathke and Rabl-Rickhardt). The quantity of retiform
fibrous tissue in the matrix is small in the adult laryngeal and
costal cartilages, large in cotyloid ligaments, the clavicular
articular crusts of Primates, and in interarticular cartilages.
Reticular-fibro cartilage, with a basis of elastic tissue, is found
in the external ear, the epiglottis, the processus vocalis of the
arytenoid cartilages (Rhemer), &c. Calcification takes place
in the cartilages of Sharks, &c., by the deposition of lime-
salts in the intercellular substance. In Mammals, a layer of
calcified cartilage lies at the junction of the ribs and costal
cartilages ; (reticular cartilage rarely calcifies). In the deve-
lopment of cartilage, nuclei first appear in the protoplasm,
these multiply, and the tissue divides into cell areas; the
cells become surrounded by clear margins: at first there is no
matrix, but this develops apparently out of successive concen-
tric cell-capsules.

7th. Bone is a form of connective tissue only found in
Vertebrates, consisting of corpuscles} united by branched
processes, in a matrix containing ossein and lime salts (Phos-
phate and Carbonate, with a small quantity of Magnesia, and
a trace of Ca Fl). The proportions of animal and earthy
matters vary in different species} and at different ages.§ The

* These may be split into laminze by chromic acid. Osmic acid shows
the matrix to be traversed by straight strize (juice canals of Bubnoff).
+ Rarely, as in some fishes and in dentine, there are no corpuscles but
only branching canaliculi or processes.
{ The proportions in some animals are :—
Man, Animal matter = 33 Earthy=67. Ox, Animal = 31 Earthy = 69.
IOUS 5 BE ep See Selle gpa SCO) ape ato
Cod = 55 son 134 es 105 ee Oxpoise, 55.0 (35) ann = (Os
Frog, ,, ” Sib) op = 64. Snake, ” = Sh! ” = 68.
This variation shows that bone is a mechanical mixture of these elements.
By dilute hydrochloric acid we may remove the earthy matter: by burning
we may remove the animal portion.
§ The proportions at different ages in Man are—4g per cent. of animal

Cc

18 Introduction to Animal Morphology.

matrix is arranged in plates* around vascular canals (Haver-
stan canals), and is studded with corpuscles} which send
processes (canaliculi) in all directions.t The lamellz are
pierced at right angles by calcified rods.§ In development
sometimes the lime salts are laid down in the intercellular
substances, so that the connective tissue corpuscles become
bone-cells, but this simple form of bone development is rare.
Usually in the ossifying of cartilage the corpuscles first mul-
tiply and become arranged in columns. Protoplasmic masses
ascend in spaces or canals between these, and vessels from
the periosteum shoot into their intervals: then a granular
osseous matter is deposited along the vessels so that the
groups of corpuscles lie in spaces (primary areolz) bounded
by the spicular growth of the bone substance. At this stage
the corpuscles become granular and break up into smaller cell
masses, while by absorption the primary areole are made to
communicate with each other, becoming secondary areolz
filled with a series of granular corpuscles (osteoblasts) and
free protoplasm. On the walls of these areole are laid down
laminz of homogeneous bone matter (secondary bone forma-
tion), in which the floating granular cells are embedded, the
spaces occupied by them being called lacune, and their pro-
cesses form the canaliculi. These secondary areolar spaces are
traversed by vessels and form Haverstan canals, or, when
larger and irregular, form cancellous or spongy tissue. The
primary bone is granular, the secondary is at first homoge-
neous.

Bone tissue thus formed may be compact, traversed by
vascular tubes (Haversian canals), or cancellous, with wide

matter in the bones of a child, 33 per cent. in the adult, and 28 in very
senile bones.

* The lamellz may be rst, around Haversian canals ; 2nd, intermediate
to such Haversian systems ; or 3rd, Peripheric : the latter are few (Zomes).
Each lamina consists, according to Sharfey, of densely decussated fibres.
The intermediate lamellz are parts of absorbed Haverstan systems.

t+ About 800 to a square millimetre in man.

t{ Ending in fine points at the articular ends.

§ The perforating fibres of Sharfey, which when decalcified are tubular
{Tomes and De Morgan).

Introduction to Animal Morphology. 19

secondary areolz. In this case the bone columns are usually
arranged so as to give the greatest strength consistent with
the amount of solid material.*

Within growing bone the unossified nucleated protoplasm,
formed by the proliferation of cartilage cells, becomes the
marrow, of which there are three kinds: yellow, gelatinous,
and red. The first consists of delicate connective tissue, ves-
sels and fat cells, and fills the shafts of long bones in most
Mammalia. The second form consists of an abundant trans-
lucent tissue (coagulable by acetic acid), and a few free nu-
cleated cells. The third form consists of a stroma of stellate
corpuscles entangling lymph cells, and surrounded by a close
capillary network of blood-vessels whose calibre is four times
greater than that of its feeding arteries. By the proliferation
of smaller cells, large colossal (myeloid) cells and polynuclear
masses (myeloplaxes) are formed.t In this tissue found in
the cancelli of young bone, Maumann, Bizzozero, and others
suppose the red blood corpuscles to be formed. (Red marrow
is sparingly present in birds.)

Bones may be long, flat, or irregular; they constitute the
sclerome or skeleton. Those developed in the integument
are called exoskeletal, those in an internal cartilage basis
form the endoskeleton, which consists of—rst, an axial or
central column protecting the nervous and visceral systems,
and znd, an appendicular part, or the skeleton of the limbs.
Dermal or integumental bones are developed by ossification
in a fibrous matrix (parvosfosis), and have no granular stage.
Endoskeletal bones may be developed by evdosfosis (ossifica-
tion beginning within the intercellular spaces of a cartilage
mass), or by ec/os/osis (ossification proceeding from the sur-
face inwards, beginning beneath the fervosteum or fibrous
sheath which surrounds all bones).

* Meyer distinguishes two sets of pillars in the cancelli, one set in the line
of greatest pressure (pressure lines, Driicklinien), and the other in the lines
of traction (traction lines, Zuglinien).

t Bredichin describes the colossal cells as formed from bone.

G2

20 Introduction to Animal Morphology.

CoH ALP fae ahve:
ANIMAL TISSUES.

MUSCULAR tissue consists of contractile cells. While
in the simplest cells the unaltered protoplasm alone
is contractile, here the entire cell is so. The simplest
muscle cell is fusiform, simple or forked* at its ends,
atv” to sto” long, with its thickest part not quite cen-
tral, and containing a rodlike nucleus capped by a
pyramidal mass of granules at its ends (A7/eds). When
it contracts, the cell surface shows transverse,ft and oc-
casionally longitudinal,} strie. Such cells joined by
connective tissue form fascicles of involuntary muscle,
such as are found in the intestinal wall of Vertebrates,
or in the body wall of all classes, except Arthropoda,
from Sponges upwards. Voluntary or striped fibres
consist of conjoined contractile cells within a
connective [some say elastic] sheath (Sarcolemma),
the contractile matter being in discs§ separated by
clear interspaces. Each fibre may be split artificially
into obliquely inclined transverse discs (cleavage
planes) or longitudinal fibrils (consisting of single
rows cf square sarcous elements, large and small
alternately, with clear interspaces).|| The sizes of

* Asin the fibres of the Frog’s bladder. Striped muscles ending in the
skin divide into pointed fibrils which appear continuous with the processes
of the connective tissue corpuscles of the dermis (Sater).

+ Metssner.

{ Wagener.

§ The dark bands (disdiaclasts) consist of granules of a double refracting
substance in the general isotropic myosin fluid substance of the fibre.

|| Intermediate forms exist between the smooth and striped fibres : thus
in the involuntary fibres of the bladder Schwalde saw a partial striation, and

Introduction to Animal Morphology. 21

fibres may vary : those of the Skate are ;” in diameter,
of Man =z32”, of Insects ;4,”. The lengths of fibres also
vary from }” to 2”. Muscular fibres end in tendons,
the tendinous material being continued as a sheath on
the fibre for a short distance. Every muscle acts
from one end which is more or less fixed (origin), on
the other end, which is more or less movable (inser-
tion). Muscles may be classified, according to their
shapes and the direction of their fibres, into prismatic,
penniform, triangular, quadrilateral, sphincteric, ellips-
oidal and skew.

The contraction of muscle is attended with chemical
change,* heat, the evolution of carbonic acid, and the
production of inosite, &c. In higher animals each
cubic inch of muscle is capable of giving out a con-
stant amount of work (about 100 foot pounds) in a
single contraction. As a rule, the work done by a
muscle bears a proportion to its weight, and for each
muscle when kept in action until complete fatigue
sets in, the total amount of work, multiplied by the rate
of work, is constant. The cessation of life in muscle
is shown by a continuous stiffness (rzgor mortis) due
to the coagulation of myosin in the inter-fibrillar
spaces, which lasts until the insetting of further
chemical change, when the cell contents change to
syntonin.

Nerve tissue is peculiarly animal, nothing similar
having been as yet detected in sensitive plants. Pro-
toplasm, when irritated, contracts, but its modifica-

the heart muscular fibres consist of uniting cells without (or with, Winkler)
a sarcolemma.

* Muscle when at rest is amphichromatic (alters the colour both of red
and blue litmus paper), but when in actionit becomes acid. In rigor mortis
it is also acid.

22 Introduction to Animal Morphology.

tions, epithelium, connective tissue, &c., donot. When
such elements increase in a heteroplastic body, some
sensitive replacement for the primordial protoplasm is
necessary: hence cells and fibres are set apart for re-
ceiving impressions and conveying irritations. The
simplest of such apparatuses are the neuro-muscular
cells of Hydra (Fig. 13). Nerve fibres first appear as
minute homogeneous bands (primitive fibrils, as in
some Ccelenterates and Annuloida). Such fibres are
commonly united in longitudinally striated bundles,
with scattered nuclei and an inter-fibrillar granular
tissue (naked axis cylinders,* as in many Inverte-
brates). These bundles may be invested with a medul-
lary sheath of a highly refracting oily substance and
protagon. On isolation, these fibres break up and
become varicose; after death the sheath coagulates.
The fibres of the optic and auditory nerves of Mammals
are of this kind. These vary from z359” to yoo” in
diameter. In the ordinary nerves of all Vertebrates (ex-
cept Acrania and Marsipobranchii) there is superadded
a transparent, structureless, feebly refracting, nucleated,
sometimes laminated, connective tissue (nucleated
sheath of Schwann), very thick in the nerves of Electric
Fishes. Bundles of medullated fibres enveloped in a
nucleated sheath of Schwann form the olfactory nerves
of Mammalia, or without sucha sheath in the olfactory
tract of Sharks. Similar fibres separately enveloped
in the connective sheath form the abdominal branches
of the sympathetic nerves (Remak’s fibres) in Verte-
brates, and are common in Invertebrates. Among

* Grandry describes the axis cylinders as made up of transversely placed
discs of one material, with a diverse substance intercalated. Schultze says
the axis cylinders consist of separate fibrils.

Introduction to Animal Morphology. 23

Crustacea the nerves have medullary sheaths. When
nerves divide, their sheaths attenuate, but the sheath
on small branches is thicker than on larger. On very
small branches the sheath of Schwazm is lost first, then
the medullary sheath: then the axis cylinder splits
into its component fibrils.

Nerve fibres begin in uni- or multipolar,* finely granular,
nucleated, and nucleolated nerve corpuscles (dilatations of the
axis cylinders ?) surrounded by a capsule of connective tissue.
Clusters of nerve cells embedded in protoplasm and a copious
inter-fibrillar matrix are called ganglia. Nerves end in diffe-
rent ways:—1. In free ends between epithelial cells (in cornea,
Hoyer and Cohnheim). 2z. In pear-shaped bodies (epiglottis,
Klein) or pyramids of protoplasm with clear elliptic nuclei
(testis, Lefzerich), or in branched gland-cells(?)(Pfliiger). 3. In
sense organs they end in fusiform or rodlike bodies with non-
vibratile blunt processes (gustatory cells of Zovén and Key,
the smelling cells of Schultze, sentient cells of rete mucosum,
Tomsa, retinal cones, and Cortian rods). 4. In Pacinian cor-
puscles, or dilated bulbs of diverging primitive fascicles sur-
rounded by a finely granular mass of protoplasm, and en-
closed in dense concentric laminz of connective tissue.t
Similar club-shaped bodies without the connective capsule
are the end organs of Krause. The corpuscles of Mezssner in
the sensitive palmar papillz, are furrowed bodies into which
a nerve enters and twines round once or twice, rising to its
top. 5. In muscle, nerve fibres end by entering the sarco-
lemma in little conical eminences (Doyérian papillz), then
breaking up into a wide-meshed plexus of fine filaments which
may end in a plate composed of an upper granular layer and

* Each cell may have many poles, but has only one peripheric branch
(Deiters). Sometimes a spiral filament (or 2, 3, or 4 such, as in the Frog)
winds round the straight peripheric branch—two kinds of these, nervous
from the substance of the corpuscle, fibrous from a basal network, are
described by Schwalbe.

+ Bodies like Pacinian corpuscles, arranged in chains on an axis band,
exist in the tympanum between the pyramid and the canal for the tensor
‘ tympani muscle, as well as in the mastoid cells.

24 Introduction to Animal Morphology.

a lower homogeneous surface made of the expanded axis cy-
linder. This lies on a layerof granular protoplasm lying directly
in contact with the disdiaclasts, or no granular layer may in-
terpose (Frog). In electric and pseudelectric plates, nerves end
in asimilar manner. Hensen describes nerves as ending in
the nucleoli of epithelial cells in frog skin; ZLzppmann, in the
nuclei of the corneal corpuscles ; Joseph, in the nuclei of bone
corpuscles.

Nerves when living are weakly alkaline, or neutral.*
After death, or when heated, they become acid; during
action they take in oxygen and give out carbonic
acid (Ranke). Impressions travel along nerves at the
rate of 111 feet per secondt (Helmholtz and Baxt),
nearly the same rate as that of a sound wave through
a material of equal density.

CHAPTER. ¥.
TECTOLOGY.

ANIMALS, as distinguished from plants, are living
beings whose nitrogenous form-elements are con-
tinuously united (not separated by partitions of ternary
compounds), assimilating organic matter only,t ab-

* Constant electric currents make nerves acid at the anode, but un-
changed at the cathode.

+ Donders states the rapidity of feeling as +”, of hearing 3”, of sight 4”.
In each of these and the consequent muscular action there are the following
stages :—1. Action on the percipient element ; 2. communication to nerve
ganglion cell; 3. increased action in this cell; 4. conduction to sensorium :
5. action in sensorium ; 6. action of volition ; 7. conduction to motor cells ;
8. action in these cells; 9. conduction to muscle; 10. action of muscle.
The psychical part he supposes to occupy about 0.06”.

} Like all organic beings devoid of green chlorophyll, such as
Saprophytes.

Introduction to Animal Morphology. 25

sorbing oxygen, and evolving carbonic acid. Muscle
and nerve exist only in them, as are the more complex
forms of connective tissue. Haeckel proposes to make
a third kingdom, Protista,* of a series of living beings
intermediate between plants and animals. But most
of these, though not falling in rigidly with the defi-
nition of either, have recognizable affinities pointing
to one group or the other, and as the limits of every
class are arbitrary, it is easier to draw one line of
demarcation than two: hence I have not adopted this
arrangement.

The animal kingdom, as it presents itself to us, is a
vast assemblage of individual forms. Individual may
be used as a physiological or as a morphological
term; in the former sense it means a single form
enjoying independent life for a longer or shorter time,
in the latter, a single form which is in itself an in-
divisible whole, whose parts are integral. Sometimes
the morphological individuality is a matter of dif-
ference ofopinion,asamong Sponges. Dr. Carpenter's
definition of an individual (the total product of a single
fertilized ovum) is inapplicable to most of the Protozoa
and confusing in discontinuous colonies, but yet with
a more perfect knowledge, doubtless it will be
found to be nearest to the truth. A morphological

* This kingdom, if recognised, would contain nine classes :—
1. Monera, composed of cytodes; 2. Protoplasta of cells, divided into
Gymnamcebe, Lepamcebz, and Gregarinz (all these have animal affinities) ;
3. Diatomacez, with siliceous shells, generally regarded as unicellular
Algz; 4. Flagellata, a mixed group, some probably vegetal, others cer-
tainly animal; 5. Myxomycetz, a most problematical group, with afhnities
to Fungi, but even stronger relations to Protozoa; 6. Labyrinthulea,
animals; 7. Phycochromacea; 8. Fungi, both usually regarded as vegetal ;
g. Radiolaria.

26 Introduction to Animal Morphology.

individual may be aplastide, an organ, an antimere, a
metamere, a persona, ora colony, and hence we speak of
individuals of the rst, 2nd, 3rd, 4th, 5th, or 6th orders.
Individuals of the 3rd to 6th degrees consist of organs
the study of whose mode of grouping is the science of
Tectology. Organs may be classified, according to
their functions, into:—1. Assimilative; 2. Nutritive ;
3. Depuratory; 4. Relational; and 5. Propagative.
In plastides the protoplasm fulfils all these functions.
With increasing complexity comes a division of phy-
siological labour and a localization of function, which
is termed differentiation, and seems due to the segre-
gation of some of the compound radicles which make
up protoplasm, myosin separating in one group of
cells, forming muscle, protagon, and myelin, in others
forming nerve, &c.

Relational organs appear first to be differentiated
in the form of an integument ; indeed, the cell-wall in
plastides is of thisnature. Ingroups of cells the outer
plastides harden into epithelium, and sometimes in
these cells, or even in the walls ofa plastide, carbonate
of lime (Foraminifera) or silica (Radiolaria) becomes
depositedasashell. Sometimes in plastides or groups
of plastides these substances are deposited as spicula
within the texture for purposes of support.*

In higher forms a layer of connective tissue forms
under the epithelium constituting a dermis, from pro-
toplasm exuded on whose surface the epithelium is
renewed. In such cases the epithelium is moulded to
the secreting surface.

* These deposits are formed in obedience to ordinary molecular forces,
as these mineral elements assume the same forms in viscid fluids, as proved
by the researches of Max Schultze, Rainey, Harting, &c.

Introduction to Animal Morphology. 27

The hardening of the outer surface interferes with
the general secretory nature of the surface, and hence
in recesses, spheroidal epithelial cells are set apart for
this, forming glands. Hardening likewise interferes
with the general sensibility of the surface, and hence
special processes, tentacles, &c., are developed. Lime
salts or chitin may be deposited in the surface cells,
forming shells, or in deeper tissues, as in Corals
and Echinodermata, or these may ossify, as in the
exoskeleton of Vertebrates.

In simple individuals the only vibrations necessary
to be recognised for the purposes of the organism are
those caused by material contact or heat. In complex
forms, means for the detection of the finer vibrations
are provided. For the centralization of perception,
the nerve elements are segregated in cells near the
end of the body foremost in progression, at the base
of special touch organs where such exist, or where
the surface is least protected. Around the pharynx
these form a single or secondarily double ganglion in
each antimere, united to its fellows by a commissural
ring, from which nerves pass to the sense organs, to
the mouth surface to end in taste cells, and to ciliated
cavities possessing the sense of smell. The multipli-
cation of metameres is attended with an extension of
the nervous system, on the inferior side of the viscera
as a twin cord, with ganglia in each metamere. The
enlargement of the upper element of the pharyngeal
ring forms a brain, and in Vertebrates this part
of the nervous system is prolonged backwards on the
upper side of the viscera as a spinal cord. As organs
for receiving impressions and acting on stimuli in-
crease, so the brain mass increases and differentiates,

28 Introduction to Animal Morphology.

and processes connected with it (nerves) permeate the
textures. To recognize sound waves a vesicle full of
fluid containing a calcareous body (Otolith) is de-
veloped, to which passes a nerve from the central
system. Such organs ofhearing are widely distributed.

They occur in Medusz, in many Worms in which they are
placed usually near the cephalic ganglion, in some Turbellaria,
where they are unsymmetrical, sometimes single, while in
parasites they are absent.

In Tunicates there is an unsymmetrical ear vesicle; in
Brachiopods it is only present in the larva ; in Lamellibranchs
the vesicles are close to the pedal; in Cephalophora, to the
pharyngeal ganglion ; in Cephalopoda they are cephalic, and
either simple vesicles (Octopus), or a more complex labyrinth,
both ligamental and cartilaginous, with single or multiple
otoliths.

To appreciate light, we find in Infusoria, &c.,
brightly-coloured pigment spots or photoscopic eyes,
sometimes separate from the nervous system (which
may discriminate light from darkness). More definite
eyes exist in Annulosa as crystal rods or cones at the
end of a nerve surrounded by pigment. A cluster of
these may form asingle mass (Sagitta, &c.) In higher
Arthropods a new element is added, for the chitinous
integument over the cones is clear, free from pigment,
and transparent, lenslike forming a lenticular cornea.

Single eyes of this form exist in Corycza, &c., but com-
monly they are in clusters forming compound eyes, as in
Insects. In such eyes the optic nerve ends in a granular
ganglion, in which the ends of the rods are imbedded ;
around these is the pigment mass, and over the end of each
is a separate corneal lens. As these are closely clustered,
each facet becomes hexagonal. These groups are called
facetted eyes, and from 3 to 8,000 may be in each cluster.
Sometimes the surface is smooth, and the facetting is only

Introduction to Animal Morphology. 29

seen within, as in Crustacea. In Arachnida there is only one
corneal lens for a number of crystal cones, and the same
occurs in the stemmata or single eyes of Insects. In some
Spiders there are muscular (iridal ?) fibres among the pigment,
and a rudimentary reflector or tapetum. Sometimes in
Crustacea, muscular fibres exist capable of drawing the cornea
to the cones, a rudimentary accommodating apparatus.
These eyes capable of receiving and recognizing images are
called Idoscopic (Jourdain).

The lowest animals live in water, hence pseudopodia
or cilia are sufficient means of locomotion. Some
Gregarine have a special contractile layer like the
axis of the stalk of Vorticella. Definite muscular
fibres appear in Hydrozoa, first as processes from the
neuro-muscular cells of Hydra attached to the ectoderm,
and these become arranged in strata. With antimeral
growth, muscle bands assume a symmetrical, and with
metameral, a homodynamic symmetry. When ap-
pendages form from the axis they have special bands
of these strata attached to them, and thus a muscular
system grows in complexity. Each muscle carries its
proper nerve, so the peripheral nervous system grows
part passu. According as the muscle is attached to
the dermis or to the inner connective tissue, it is
called exo- or endo-skeletal. The endoskeleton itself
first appears as a fibrous or cartilaginous investment
of the digestive and sense organs in Molluscs, but is
fully developed in Vertebrata.

The assimilative organs are differentiated next to
the relational. A naked plastide can take in and
digest food and eject effete particles at any part of its
mass, but the formation of a cuticle renders the pre-
sence of a mouth necessary. This appears first in
ciliated Infusoria, and may open directly into the

ae Introduction to Animal Morphology.

protoplasm of the plastide or cytocorm, or by means
of a funnel and wide passage, which sometimes
narrows into a tube (Esophagus). Polystomata, &c.,
have an internal cavity added, and in Ccelenterates
we find this lined by separate cells,* which secrete
a special fluid by which the food is dissolvedt, and
the nutritive part transuding the plastides of the.
walls nourishes the animal. Effete matters are ejected
either at the mouth or by a special opening at the
distal end (anus). An elongation of the communi-
cation between the stomach and anus to increase the
absorbing surface forms an intestine from which, for
the same purposes, blind pouches (ceca) may project.
Secondary appendages for the prehension and me-
chanical division of the food (jaws and teeth), for the
moistening of the food in deglutition (salivary glands),
and for the assimilation of fats (liver and pancreas$),
are afterwards developed in and from the tube.

* The development of an internal cavity is regarded by Haeckel as dis-
tinguishing the second or gastreea type of structure from the primitive
planula form.

t Gastric juice contains in higher animals water, pepsin (an albuminoid),
hydrochloric, butyric, and lactic acids, and phosphates of soda and lime,
&c. It converts albuminoids into dialysable forms (peptone, metapeptone,
parapeptone, &c.) by making them take up water.

} Saliva, the secretion of the parotid, contains water, ptyalin (an albumi-
noid), albumin, mucin, sulpho-cyanide of potassium, a fatty acid, and salts of
potass, soda, lime, &c. This fluid can saccharize starch in neutral alkaline or
weakly acid solutions. The secretion is mainly poured out under the agency
of stimuli, food, odours, &c. Other glands, submaxillary, sublingual, buccal,
labial, &c., are mucous glands pouring fluid into the mouth. The
secretion of the first of these acts feebly in saccharizing starch. These
secretions are but slightly influenced by the smell of food, but are actively
affected by the movements of mastication.

§ The liver secretes bile, an orange or yellow alkaline bitter fluid con-
taining water, cholesterin (a crystalline fat CssHgO,), sodic glychocholate,

Introduction to Antmal Morphology. 31

The alimentary canal may be the only body cavity,
or it may be suspended in a larger separate cavity
(Cceloma) formed either by outgrowing spaces from
itself (Ctenophora, Echinodermata, &c.), or by in-
vagination (Amphioxus), or by the splitting and
separation of two mesoblastic layers.

In simple animals the nourishment is taken into
the plastides of the stomach wall, but as these walls
become membranous, and as other organs become
more complex, the assimilated fluid collects in separate
spaces where, by osmose or the general contraction of
the body wall, or by a special contraction of a
muscular tube, it is made to move so as to bathe the
tissues. This newly-formed system is the nutritive or
circulatory. At first, as in Actinozoa, with a body
cavity (distinct from the stomach), it is in this space
that the nutritive fluid, mixed with water, is to be
found. In the lower Worms, where the digestive and
perivisceral spaces do not communicate directly, the
body cavity still contains the nourishing fluid, which
yet often contains sea water. In the higher Annulosa
definite vessels exist, but yet in some the blood only
traverses these for a limited part of its circulation, as
at each end they often freely communicate with the
perivisceralspaces. Insome Arthropods and Molluscs

and taurocholate, bilirubin (CigHigN2Os3), biliverdin (CigH2oN20s), as
pigments. In pigs the bile contains hyocholic and hyocholeic acids, in
ox gall, taurine (C2pHNSOs3). Glycocholic acid is CogHy;NO¢, taurocholic,
CxsHisNSO;. Bile precipitates peptones. In the gall bladder the bile is
thickened by the addition of mucin. The bile is largely excrementitious,
but also is an agent in saponifying fats. The pigments are formed of
altered hemoglobin. The pancreas secretes a fluid containing water,
phymatin, salts of soda, &c., tyrosin, leucin, guaninin traces. It emulsifies
fats, setting the acids free, and permits their absorption, dissolves albumi-
noids, saccharizes starch, even in acid solutions.

32 Introduction to Animal Morphology.

a closed system of vessels appears, larger vessels
traversing the tissues and carrying pure, nutritious
blood (arteries), ending in fine capillary vessels, in
which this blood acts as a pabulum to the tissues,
finally ending in larger vessels (veins), which return
the blood impoverished by the loss of some of its
nutritious parts, and carrying away the products of
tissue-waste. In Vertebrates, thissystem is still more
perfect and better organized. The venous blood re-
quires to be purified and to receive fresh nutritive
elements. The first end is accomplished by its being
exposed to oxygen, also by its passing in contact with
certain gland cells which abstract its impurities.*

* Blood is a connective tissue with a fluid intercellular matrix (called
liquor sanguinis) and corpuscular cells. The simplest form of cells are
amoeboid, sometimes vacuolated or simple, protoplasm : in the higher Verte-
brates these co-exist with reddish discoidal corpuscles. These corpuscles
have a firm central basis (zooid) composed of the nucleus and hemoglobin
inhabiting the cecoid or disc.

The red corpuscles consist of paraglobulin and haemoglobin, a crystal-
lizable principle which can absorb oxygen and exist in two states,
deoxidised (purple cruorin) or oxidised (scarlet cruorin).

The fluidin which the corpuscles float (liquor sanguinis) contains albumen,
fibrinogen, fatty matters (serolin, cholesterin, and ordinary fat, phosphates,
chlorides, &c.) When blood is exposed to the air, at rest, or under other
conditions, the paraglobulin (fibrinoplastin) of the liquor sanguinis and
corpuscles unites with the fibrinogen of the plasma, and forms fibrin, which
separates from solution, entangling the corpuscles and forming the clot.
The fluid part (liquor sanguinis 7zzws fibrinogen) is called the serum.

Pure blood in the arteries or in veins returning from the depuratory
glands is bright scarlet containing oxidised hemoglobin, a large quantity of
dissolved oxygen, and a small amount of carbonic acid. In the capillaries
this blood nourishes the tissues, parts with some of its protoplasm-forming
elements and with much of its oxygen, while it takes up urea, inosite,
kreatin, and a larger quantity of carbonic acid. Hence venous blood is dark
purple (coloured by deoxidised hemoglobin), contains 6-7 per cent. more
carbonic acid, and 9 per cent. less oxygen than the arterial (Sczelkow).

Introduction to Animal Morphology. a6

The exposure to air takes place in the respiratory
organs, of which there are four types—rst. In aquatic
animals, the blood, contained in organs called branchiz
(gills), is exposed to water containing oxygen in
solution; 2nd. Also in water dwellers, a system of
tubes communicating with the external water and
traversing the animal's body, admits this fluid so
as (through their walls) to aerate the blood in the
perivisceral space (water vascular system); 3rd. A
system of tubes (trachee) containing air, ramifying
through the body, whereby the blood may be directly
aerated; or 4th. A series of sacs (pulmonary sacs,
lungs) set apart for the reception of air, to which the
impure blood is brought, and exposed in capillary
vessels.*

The glandular depurants remove from the blood
the waste of nitrogenized material. They are the
dermal glandst (the only ones in the lowest forms),
and kidneys.¢

* In the respiratory organs, water, carbonic acid, and traces of other
substances are got rid of and oxygen taken in. As this oxygen enters into
chemical combination with the protoplasm in the tissues in the life
processes, in all living forms heat is evolved during such chemical
action, and the amount thereof varies with the activity of the com-
binations.

+ In the perspiration. or excretion of the dermal glands is contained
water, sodic chloride, ammonic lactate, butyrate, and acetate, some nitro-
genous materials, sometimes formic acid, and an odorous principle.

{ The kidney separates from the blood, urea, uric acid, often combined
with ammonia, kreatin and kreatinin, sometimes hippuric and benzoic acids,
xanthin and hypoxanthin, wrophzin, and salts similar to those in blood

serum.

34 Introduction to Animal Morphology.

CHOAPTE RIV ik
REPRODUCTION.

THE organs hitherto referred to deal with the well-
being of the individual: for the propagation of the
species other apparatuses are needed. The simplest
morphological individuals reproduce by discontinuous
fission or gemmation. Higher forms show a more
complex mode, which, however, still partakes more or
less obviously of these primitive methods. In this
process two cells co-operate: one organ derived from
the endoderm or inner germ layer of the embryo* (the
ovary), forms, by gemmation of its component plastides,
special cells (ova), which are to be the new individuals.
Another often similar organ, but derived from the
ectoderm or outer germ layer* (testis), forms elements
also from its own plastides, whose function is to unite
with and stimulate the ova into development (sperma-
tozoa). What the nature of the stimulation is we
know not, and it is as yet idle to theorize, though the
diverse origin of the two elements is suggestive. In
the simplest cases the organs producing these diverse
elements are, though dissimilar in origin, side by side
or united, or we may find them at separate parts of
the same animal. The ova are nucleated cells; the
spermatozoa are nucleated flagellate plastides formed
within a mother-cell. If ovaria and testes co-exist in
one individual, it is called monocecious or hermaphro-
dite. If the sex organs are in separate individuals
they are called dicecious. The contents of the sex
organs may be emitted by simple rupture (dehiscence),

* FE. Van Beneden.

Introduction to Animal Morphology. 35

or carried by ducts, called respectively oviducts and
vasa deferentia. All reproductive processes seem only
to differ from growth processes in that the results are
discontinuous, and they may be divided into two
series—ist. Agamogenesis, where no second or male
element is required to stimulate the (often internally
produced) germ into development. The simplest form
of agamogenesis, leaving out of account fission and
gemmation in plastides, is the production of the so-
called winter eggs in sponges, where we have a con-
stant and, as far as we know, continuous asexual pro-
pagation not necessarily interrupted by any periodic
recurrence of sexual reproduction. Such a form is
monogenetic agamogenesis, as the progeny and parents
are similar. In another case a primary form or proto-
zooid produces, by internal gemmation (without having
any developed sexual organs), a secondary form or
deuterozooid, and this may in time produce a tritozooid,
or it may develop sexual organs and produce ova,
which require the male elements to fertilize them. To
this process the name medagenes7s has been given, and
of it there are varieties: thus, when the deuterozooid is
sexual, and so differs from the protozooid, the process
is metagenests with successive heterogony, or if the pro-
tozooid be sexual, and by internal gemmation give
rise to a deuterozooid in which sex organs are also
developed, the mefagenests is said to be wzth contempo-
raneous heterogony, and it may be zsogenetic or diverse,
according as the deuterozooid agrees or disagrees with
the protozooid in sex. Where there are successions
only of two stages, the name dzgeneszs is sometimes
given in place of metagenesis.

In other cases the protozooids have generative

D2

36 Introduction to Animal Morphology.

organs like ovaria, but producing gemmules (more or
less resembling true ova), which do not require any
male stimulus for their development. These organs are
called pseudovarza, and the gemmules are viviparously
produced. Each of the deuterozooids can produce in
these cases /ritozoords, &c., as long as suitable con-
ditions of temperature and food continue; but on the
occurrence of some unknown checks upon this process,
the individuals of the last brood develop perfect sexual
organs and are oviparous. To this process the name
parthenogenesis, or more properly pseudo-parthenogenests,
is given. The products of the pseudovaria may be
eggs, as among the worker Bees, &c., from which
usually males are hatched (except in some Wasps).
Females with perfect sexual organs, but without the
stimulus of spermatozoa, may produce ova, as in the case
of Queen Bees, Psyche helix, Solenobia triquetrella,
and lichenella, or else embryos may be produced, asin
some Ccecide, Chermes, &c. 2nd. Gamogenesis is
that form in which the female gemmule requires the
stimulus of contact with the protoplasm of the male
spermatozoon, in order to cause its development. In
this case the ovum consists of a cell with a germinal
vesicle or nucleus, with a nucleolus or germinal spot.*
This is generally included within a yolk (Vitellus),
‘surrounded by a vitelline membrane. Outside this
are often layers of albumen and an enclosing shell.
There is often a micropyle or opening in the egg-
‘envelopes, whereby the contents may receive the
contact of the spermatozoa. On impregnation the
yelk shows amceboid motion, loses its germinal vesicle

* Within which may be a vacuole (Za Valette) or a solid bright spot
(Schrén).

Lntroduction to Animal Morphology. 37

and spot,* cleaves into two, then into four, then eight,
&c., until it is resolved into a morula or mulberry-
like mass of cytodes. The cytodes develop nuclei and
become cells. This process may involve the whole
yelk circumference, as in Mammalia, &c., and the eggs
are called holoblastic, the germ and yelk elements
being combined, or only a part, as in Birds, and the
rest is gradually absorbed as nutriment into the
cleaved part (meroblastic ova), the germ and yelk
being separate. The sphere of embryo cells produced
by the segmentation of the yelk is called the blasto-
derm, and in all animals above Protozoa this divides
into two layers (becoming aplanula),+ an outer serous
or epiblastic, and an inner mucous or hypoblastic,
within which forms a cavity (the cleavage cavity or
cavity of Baer). The embryo in meroblastic eggs is
supported on subgerminal processes. Between these
layers there forms a mesoblast of one or two lamine.
The after-stages differ in the different classes, and
will be considered under each head. Thus.all animals
in their earliest embryonic stages are identical; but
the process of differentiation takes place along di-
verging lines, and each stage narrows the circle of
resemblances, or as Von Laer expresses it, development
takes place from the general to the special.

Animal forms can be grouped into certain categories
called sfeczes,t each consisting of individuals identical

* In Entoconcha, J/l/er describes this as persisting and becoming trans-
formed into the nuclei of the cleavage cells.

+ Which by absorption at one pole forms a mouth, and becomes a
gastrula.

{ It is impossible to define sfeczes to the satisfaction of all naturalists,
as the conceptions in their minds are not the same, and species, genus, &c.,
must be looked on as more or less arbitrary (ideal conceptions).

38 Introduction to Animal Morphology.

in all essential characters, leading to the belief that
they have descended directly from a common stock.
A group of species closely resembling each other in
their general characters is named a genus. A group
of genera bound together by natural affinities is a
family, a group of allied families, az order,* of allied
orders a class, of allied classes a sub-kingdom, which
is the highest category in the predicamental line
under the animal kingdom. The embodiment of the
special form-characters of any of the categories is
called its ¢yje. Thus we speak of the type of a genus,
family, &c. When one type form unites in itself the
leading special characters of two or three diverse
forms, it is called a synthetic type. Such forms were
common in earlier periods of the world’s history.
Type-forms which retain as characters many of the
embryonic features of the entire superior category in-
cluding them, are called generalized types. ‘These are
the poorest in species, and the most local in distri-
bution of animal forms. The arrangement of indivi-
duals in these categories we know as classification, and
this is often a matter of difficulty, as no two individuals
are precisely alike. In categories of which we have
many individuals, connecting links between appa-
rently different forms constantly occur, so that a
systematist has either to make a large number of
small groups or the opposite (witness the family
Helicide, and in botany the genera, Hieracium, Rubus,
and Salix). We cannot define the exact limits of any
species until we know its range of variation, which
has never yet been precisely ascertained for any single

* When further divisions are required, we speak of orders being divided
into sub-orders, and classes into sub-classes,

Introduction to Animal Morphology. 39

a

species, as we are yet imperfectly acquainted with the
paleontological record of past life. On the other
hand, the necessity for the union of several so-called
species (by the discovery of a perfect series of links)
has often occurred in the experience of zoologists.*

In the characters of types, arrangements apparently
unconnected with each other always occur in groups:
thus, animals that suckle their young have always two
occipital condyles and non-nucleated blood corpuscles,
and animals clothed with feathers have a muscular
right auriculo-ventricular valve. These coincidences
are called correlations of growth, and can only be in-
telligently accounted for on the ground of a community
of descent.

In tracing the embryonic development of individuals,
a retrogression is sometimes noticed instead of a pro-
gression. This is the reverse of specialization, and
produces a simplification of organs. An animal ina
position in which certain organs would be useless,
loses them, and thus becomes reduced. Thus, re-
duction is the consequence of loss of function. Itisa
gradual process, organs becoming rudimental before
they become finally aborted. These rudiments are
called by Gegenbaur, significant finger-posts in compa-
rative anatomy. Two of the commonest conditions
under which reduction takes place are parasitism and
the grouping of persone into colonies.

A parasite is an animal living on or in the beady of
another, who is called its host. There are two con-
ditions often confounded under the name—1st. Com-

* When several usually distinct forms are included in one species, each
is called a sub-species ; less distinct forms are varieties. As a rule, the
groups poorest in species are the most aberrant,

40 Introduction to Animal Morphology.

mensalism, where one animal lives ov and feeds w7th
its host, but does not nourish itself at its expense. A
commensal may be merely indebted to its host for
house-room, as the Coronule on the Whale’s skin
(Oikosites), or it may feed on the food of its host, and
then is a Koinosite. This is called pseudoparasi-
tism. 2nd. A true parasite feeds on the tissues or
juices of its host, and may be an ecto- or an endo-
parasite, according as it is attached to the outside or
to the inside of its body surface.

In classification it is well to bear in mind that
no: character of structure or form is of equivalent
taxonomic value in all tribes, but the value of each
varies in each class (/orées) ; also that a character is of
good value in classification when its presence enables
us to predict correlative but independent characters
as accompanying it (Ro/leston).

The origin of species is a favourite subject of theory,
on which modern opinions may be ranged in two
series—ist. The special creation hypothesis (whose
advocates differ as to the number of separately created
types, their opinions depending on their conceptions
of species); and 2nd. The evolution theory, that dif-
ferent forms are descended from common stocks. The
supporters of this view differ according as they attach
a greater or lesser importance to the different physical
causes of variation. The fact that scarcely two indi-
viduals are alike may be stated generally thus, that
the descendants of a common stock are liable to vary.
As a larger number of individuals are produced than
can continue to exist under the conditions of food,
temperature, and other surroundings, some only, and
those necessarily the fittest, will survive; the fittest

Introduction to Animal Morphology. 4I

being those whose variations of forms are correlated to
their external conditions giving them the advantage
over their congeners. The offspring of each individual
usually inherit the parental peculiarities often intensi-
fied. Those that do not are (by hypothesis) at a dis-
advantage, and die off; hence permanent varieties,
sub-species, and species arise. When we bear in mind
that the physical conditions ofnature in any place have
been highly variable, it gives a greater force to this
explanation of the method of variation.* This is A/r.
Darwin's theory of Natural Selection. As a natural
deduction from evolution, we have Yr. Haughton’s
law, that ‘all structures are arranged so as to give the
maximum of work possible under the given external
conditions,” a law which is at the basis of the curious
study of Dysteleology,t for by its operation it} cuts
down all organs which, from altered external condi-

* But while explaining the method, Natural Selection does not explain
the cause. In artificial selection the cause is the presidence and direction
of human intellect. In Natural Selection there is a necessity fér predicating
the existence of a presidence similar in kind, but grander in degree, as the
changes effected by it are greater than those that artificial selection can
accomplish. This evolution theory explains the teleological correspondences
noticed in animals, for by hypothesis the organ progresses according as the
necessity for the function increases. Evolution also is morphological—that
is, structures progress only along certain lines, and of this we can give no
explanation, but can only say that it has been so—that is, evolution has
progressed under law.

t+ Dysteleology is the study of rudimental and vanishing organs
(Haeckel). They must be distinguished from provisional organs, which are
structures useful in one period of life, disappearing in others. Rudiments
may be constantly or only occasionally present in the species. They may
be retrograded structures on account of parasitism, &c., or vanishing heir-
looms of former lower states.

{ Ihave here personified the law, as one must do in speaking of the
operations of law in general, a significant fact, as it testifies to our con-
sciousness that a law is nothing but the expression of a personal will,

42 Introduction to Animal Morphology.

tions, do not give the maximum of possible work,
bringing them first to the condition of rudimental
organs, and then causing their complete obsolescence.

CHAPTER: Mil.
DISTRIBUTION OF ANIMALS.

ANIMALS exist almost everywhere on the globe. Each
form has a more or less extensive area. Asa rule,
synthetic and generalized types have the most limited
ranges. Correlations in distribution are also notice-
able, and hence the surface of the globe may be
divided into provinces, each characterized by its own
peculiar fauna. These provinces may be combined
into larger tracts or regions, of which there are
seven :—1st. Palearctic, or the northern half of the
Old World. 2nd. Nearctic, or America north of
Mexico. 3rd. Neotropical, or Central, and South
America (except Patagonia). 4th. Ethiopian, or
Africa south of the Sahara. 5th. Indian and
Malayan. 6th. Australian, or Australia and that part
of the East Indian Archipelago south-east of the
deep-sea boundary line pointed out by W/r. Wallace.
7th. Antarctica, or the region about the South Pole.

The provinces included here are as follows:—In the
Palzarctic—1st. The Eastern Polar, characterised by the pre-
sence of the Reindeer, Lemming, Wolf, Arctic Fox, and many
Mustelines, Salmonidz, Auks, Divers, and Gulls; and at its
southern limit Grouse and Surnia, the land Molluscs, Limax,
Arion, &c. znd, The Middle European, extending to the

Introduction to Antmal Morphology. 43

Pyrenzeo-Caucasian axial chain, characterised by the presence
of many Bats, Red Deer and Roebuck, Dentirostral birds, many
small Rodents, few true Reptiles, Cyprinoid fishes, Carabicine
and Staphyline Beetles. 3rd. Aralo-Caspian, stretching to
Siberia, rich in Rodents, Reptiles, the home of the Saiga
Antelope. 4th. Tartarian, the plateau region of Asia, the home
of the Horse, Sheep, Bactrian Camel, Yak, &c. 5th. Medi-
terranean, characterised by the Viverridz, Jackal, Lion and
Leopard, Fallow Deer, Pterocles, Flamingo, Ibis, Platalea,
Pelican, and Coleoptera Heteromera. 6th. Japanese, the pro-
vince of the Sieboldia, Inuus speciosus, Ursus lasiotis, &c.
7th. Chinese, the home of the Phasianidz, Labyrinthobranch
Fishes, &c.

In the Nearctic are included :—1st. The Western Circum-
polar, resembling the Eastern closely, and characterised by
the White Bear, Salmonide, Beaver, and fur animals, Musk
Ox, &c. 2nd. North American, the region of the Insectivores,
small Carnivores, Bison, Deer, Virginian Opossum, Dentiros-
tral, and Conirostral Birds, Tortoises and Percoids, Unionidz
and Astacoids.

The Neotropical region includes :—1st. Mexico-Antillean,
the home of the Ganoids, Amia, Lepidosteus, Scaphirhynchus,
Phyllostomine Bats, Solenodon, Ascomys, Dicotyles, Cer-
colabes, Alligator, Anolius, land Crabs, and land Mollusca.
2nd. Brazilian, characterized by CEdentates, Platyrrhine
Monkeys, Vampires, Capybara, Pontoporia, and birds. This
is the richest ornithological province in the world, the land of
the Trochilidz, &c. 3rd. Peruvian, the region of the Llama,
Condor, Eriomys, Octodon, &c. 4. Pampas, the province of
the Lagostomus, Harpalide, &c.

The Ethiopian includes :—rst. The Saharan, the home of
the Ostrich, Hyzena, Jackal, Jerboa, Percnopterus, Varani, and
Scincs, Locusts, and Melasomide. 2nd. The Guineean, the
province of the Gorilla, Chimpanzee, Mandrill, Cercopithecus,
Colobus, Manis and Orycterope, Hyzmoschus, Rhinoceros
and Chceropsis, Manatees and Potamogale, Malapterurus,”
Polypterus, Gymnarchus, Termites, &c. 3rd. South African,
the kingdom of the Antilopes, Pedetes, Giraffe, Lion, Hip-
popotamus, Gypogeranus, Snakes, the larger Cicindelidz,

44 Introduction to Animal Morphology.

Achatinide, &c. 4th. Madagascar—according to Haeckel, a
fragment of a once large central continent, Lemurien. Its,
fauna consists of Lemurs, Pteropine bats, Echinogale, Ericulus,
Centetes ; Didine birds and A%pyornis formerly lived herein.
The Indo-Malayan region includes the following provinces ;—
tst. India, the home of the Tiger, Canidz, Arctictis, Helictis,
Paradoxurus, Catarrhine monkeys, especially Semnopithecus
and Hylobates, Pteromys, Moschidz, Platanista, Cinnyride,
Bombycidz, and Bdellidz. znd, Malaya, the land of the
Orang utan, Bats, Tarsius, Sumatran Rhinoceros, Tapir, Anoa,
Babyroussa, Polyplectron, Peacocks, Argus Pheasants, Birds
of Paradise, &c.

Australia includes two provinces :—1st. Polynesia, the
kingdom of the Partulide, Nymphalidz, Apteryx, Strigops,
Nestor; and znd. Australia, the land of Marsupials and,
Monotremes, Bennett’s Cassowary, the Emu, Menura,
Scythrops, black Swan, Pezoporus, Scincs, &c.

The Antarctic region is little known, Patagonia, its first
province, is characterised by the presence of the Guanaco,
Dolichotus, Puma, and Rhea Darwinii. The other land
regions in it are little known.

Marine animals are distributed in zones of different depths,
of which five can be recognized :—1rst. Superficial, the area
of floating animals. 2nd. Littoral, or the region between
tide marks, the home of Annelides, &c. 3. Laminarian, or
that from low-water mark to about 10 fathoms. 4th. Inter-
mediate or coralline, that from the level of about. 10 fathoms
to a varying depth from 40 to 60, or 100 fathoms. 5th, The
Abyssal or deep sea zone, or that below 60-100 fathoms.
Life in these zones is modified by currents hot or cold,* and
varies geographically; thus, in the Arctic Ocean, the cha-
racteristic forms are the Walrus, Narwhal, Scorpzena,
Salmonidx, Amphipodous Crustacea, Chelyosoma, Cystingia,
&c.. In the Antarctic Ocean, are the Penguins and Auks, the

* * Some animals can bear wide limits of change of temperature, and
hence are called Eurythermal. Others are limited to regions where the
temperature changes within very narrow limits; such are known as
Stenothermal. Some forms can live in waters of very varying degrees of
saltness, and are called Euryhaline (J70d7us).

Introduction to Antimal Mforphology. 45

Falkland seals, &c. In the North Atlantic, Gadide and
Clupzidz, Porpoises and Dolphins, Rorquals and Whales,
abound. In the Mediterranean, Labroids and Dolphins,
Scomberoids, &c. In the North Pacific, Otaria, Enhydris,
and Cataphracta. In the middle Atlantic, Plectognathi,
Manatus, Petrels, Pteropods, and Cephalopoda. In the
Indian Ocean, Buccinidze, Dugongs, Hydroids, Tubipora,
Rhinodon, Siluroids, Squamipinnes, Corals, and Echinoder-
mata. Inthe Middle Pacific, are Corals and Holothurians
in abundance. In the South Atlantic, the Proboscis Seal,
the Cape Whale, &c. In the South Pacific, Physeter and
Whales, also Polyzoa and Brachiopoda.*

Distribution in time, or Historical Zoology, is an im-
portant branch of Zoology, but one imperfectly known,
owing to the impossibility of the preservation of soft
parts in a fossil form. In the annexed table I have
endeavoured to represent the order in which the
various classes of the animal kingdom appear to have
been developed, and their proportional importance in
the life of each of the past periods of the world’s
history as far as is yet known. The study of extinct
forms of life is called Paleeontology.

* T am largely indebted to the works of Schmarda for this summary.
(Die Geographische Verbreitung der Thiere, Wien, 1853; and Zoologie,
Leyily d,.1, p> Ils)

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Introduction to Animal Morphology. 47

xX = very numerous in species and individuals.

r= numerous in species and individuals, m = moderate development
specifically and individually, f = few species.

v = very few, and 1 = single species as yet known.

1. If Oldhamia be a Hydrozoan. 2. Graptolitide. 3. Mostly Rugosa.
4. Mostly Cystidea. 5. Mostly Crinoidea. 6. Scolithus-like burrows.
7. Histioderma, Arenicolites, known by their tracks. 8. Orthoceras, &c.
9 Ammonitide. 10. Trilobitide. 11. Conodontes, perhaps teeth of
Marsipobranchs. 12. Eosaurus possibly was an Ichthyopterygian.

As the number of known species in extinct forms
gives only a very imperfect idea of their absolute
numbers existing, as the forms known are probably
few in comparison with those unknown, so in the
foregoing table I have not given numerical ratios or
curves, as these are, with our present data, unreliable.

The total number of species known, as deduced
from this list, is 233.250, but as many new species
are described every year, this is a rapidly growing
series. Several of the series are probably under-
stated.

The animal kingdom includes eight sub-kingdoms,
which may be grouped as follows into two series :—

1. Protozoa, having no definite body cavity = sub-kingdom I. Protozoa.
2. Metazoa, having a definite body cavity (Gastrula).
Sub-series—1. Polystomata, having many apertures into the body cavity=
II. Porifera.
ys 2. Monostomata, having but one aperture of ingress into
the cavity =III. Coelenterata.
IV. Echinodermata.
V. Vermes.
VI. Mollusca.
VII. Arthropoda.
VIII. Vertebrata.

Of these the Ccelenterata and most of the Vermes
agree in preserving their embryonic mouth as the true
ingestive opening, and hence are called Archeosto-

48 Introduction to Animal Morphology.

mata, while in the Echinodermata, Chetognatha, and
Enteropneusta, as well as in the higher sub-kingdoms,
a second or adult mouth becomes substituted for the
embryonic: these arecalled Deuterostomata. Possibly
the Deuterostome worms should form a separate sub-
kingdom, but I have refrained from dividing the great
group Vermes until we have fuller information regard-
ing some of its classes (Gephyrea, Rotatoria, and
many of the aberrant forms).

The Deuterostomata differ primarily according to
the nature of the body cavity, which may be formed :—
ist. By outgrowths from the gastrula, as in Echino-
dermata, Chetognatha, and Enteropneusta (hence
called Enteroccela). 2nd. By the splitting of the
mesoblast, as in Molluscs and Polychete Annelids,
(hence called Schizoccela), or by an invagination
of the epiblast, as in Tunicata and Amphioxus,
(hence called Epiccela). Something like this method
will doubtless be the classification of the future, but
much embryological observation is yet required to
correct and improve it.

CHAPIER VIL,
PROTOZOA (Goldfuss).

PLASTIDES, homo- or heteroplasts, generally minute;
with no nervous system nor internal cavity ; often
forming shells or spicules, and containing, in their
protoplasm, granules, usually a nucleus, often a
nucleolus, and a clear contractile vesicle. They move
by pseudopodia or cilia, rarely by a contractile layer.

Introduction to Animal Morphology. 49

This sub-kingdom includes eight classes, which
form two diverging series.* _

CLAss 1. MONERA (Hacckel).—The simplest living
beings ; organless, aquatic cytodes with pseudopodia ;
rounded when resting or starved, irregular otherwise ;
reproduction asexual.

There are two orders of these :—1st. Gymnomonera, with
no resting stage nor capsule, reproducing by fission. They
may be single, non-vacuolated with simple (Protamceba,t
Fig. 1, A) or branched pseudo-
podia (Protogenes{), or united
in clusters by netted processes
(Myxodictyon), or in vacuolated
masses with irregular pseudo-
podia, found at great depths in
the Atlantic Ocean(Bathybius$).
2nd. Lepomonera, with a rest-
ing stage in which the body Magosphera planula. Protameba.
becomes surrounded by a cap- Pee
sule, and the interior breaks up into flagellate spores, which
on emission become like the parent. ‘This includes Proto-
monas, a non-vacuolated form found in decaying Nitella
stems ; Protomyxa, marine, in its resting stage a round orange
ball, whose contents break up into tailed spores, becoming
vacuolated amceboid cytodes with branched pseudopodia ;
two or three of these coalesce to form a mass like the parent.||
Vamppyrella is non-vacuolated, and reproduces by tetraplasts,
round masses at first dividing into two, then into four, &c.
Each of these becomes rounded with radiating processes :
they are parasitic on Algz (three freshwater and one marine

* Monera, Rhizopoda, Heliozoa lead us through Radiolaria to Porifera ;
Flagellata, through Peridinizea and Infusoria, lead us to Turbellaria.
+ Two marine and three freshwater species.
~ One marine species.
§ Doubtful.
|| This form may be propagated by artificial division.
E

50 Introduction to Animal Morphology.

species). Myxastrum, also non-vacuolated, marine, multiplies
by germs produced by radial fission, each being enclosed in
a siliceous envelope.

CLASS 2. LABYRINTHULEZ (Czenkowsky).—Nucleated
plastides found incrusting marine Algae, consisting of
a central granular mass, sending off branching and
interlacing fine protoplasm threads, possibly with a
differentiated axis, and forming variable meshes with
curved outlines. Through these threads, yellow
spindle-like cells glide in different directions, and
accumulate at certain parts of the thread in clusters.
A non-nucleated freshwater form has recently been
discovered on Sphagnum in Ireland by d/r. Archer
(Chlamydomyxa).* These myxomycetoid forms re-
quire further examination. Reproduction takes place
by fission; encystation of the spindles sometimes
occurs.

CLASS 3. RHIZOPODA (Dujardin). — Indistinctly
nucleated plastides, moving by filiform anastomosing
pseudopodia, containing circulating granules, vacuoles,
rarely one or more contractile vesicles. The yellow
or brown protoplasm secretes, near the surface of its
mass, a shell with one or many perforations, through
which the pseudopodia project, and they generally
form an expansion enclosing the shell. The shell is
usually calcareous,t but may be siliceous (Polymor-
phina, Nonionina), or of agglutinated sand-grains
(Textularia, &c.), or chitinous (Gromia), or scarcely

* Perhaps Pelomyxa (G7¢e/) is related to these.
+ CaCQO3 with Ca,HPO, in Orbiculina adunca, &c. Siliceous spicules
have been found in the spicules of Calcarina, Carpenteria, and around the

mouth in the sessile conical Squamulina.

Introduction to Animal Morphology. 51

perceptible except by limiting the pseudopodia to one
spot of origin (Lieberkthnia).

Its texture may be porcellanous (white, opaque), with a
terminal opening, or vitreous and pierced by holes scattered
over the surface. In the former case, pseudopodia project at
the terminal opening; in the latter, they protrude over the
whole surface. The shells may be one-celled oval (Ovulina),
spiral (Cornuspira), or flask-like (Lagena), or many-celled,
produced by continuous budding, but the whole mass makes
up one persona (Haeckel). These chambers may succeed
each other in a straight line* or in alternate series on two or
three alternate axes, either forming a spiralf or nott; or they
may be successive, forming a spiral which may be discoidal§
or inequilateral||; or the chambers may be wound on an
axis, each embracing half its circumference ; or, lastly, they
may be in complete circles with a porous circumference,** or
else irregular.}t The terminal opening may be round
(Cornuspira), oval (Guttulina), crescentic (Spirulina), semi-
circular (Globigerina, Fig. 2), reniform (Triloculina), linear
(Fusulina), or it may consist of several series of pores
(Polystomella).

Each chamber may have a complete wall, or may
be closed by the wall of its neighbouring compart-
ment. They communicate by single or multiple pores,
and each chamber may also have radial interseptal
canals traversing the septa to the outer edge. The
chambers, in some, form concentric rings around a
central cell (the nucleus), each whorl being a conti-
nuous tube of which the chambers are regularly serial
dilatations with narrow interspaces. The chambers

* Stichostegia, D’ Orbigny. || H. Turbinoidea.

+ Entomostegia, D’O. {| Agathistegia.

+ Enallostegia. ** Cyclostegia.

§ Helicostegia Nautiloidea. tt Soroidea, Schultze.

es)
to

52 Introduction to Animal Morphology.

are alternate in successive whorls, and from each
chamber a tube passes inward to the narrow inter-
cameral part of the whorl within (small Orbitolites).
In larger forms of this genus, each whorl canal is
horizontally divided into two parallel canals joined
by many vertical branches, and the chambers are
divided and displaced towards the surface, so that
each communicates with its canal bya double passage.
In the cycloidal Nummulites, each whorl not only sur-
rounds the margin of the one within it, but invests its
surface, thus producing rings of new chambers round
the margin, while the superposed lamina, lying close
together on the surface, are separated by fine inter-
lamellar spaces. There is thus a layer over the
central cell for each cell between it and the margin.
Each chamber communicates with its neighbours of
the same whorl by several openings, and with those
inside and outside by large diverging canals. Through
each lamina pass fine parallel canals, except where
the laminz are joined by imperforate radial pillars.
In these the sarcode is moulded to the cells, sends
stolons through the canals, and pseudopodia through
the marginal openings.

Living forms range from 0.3” to 0.002”. Some
fossil forms are much larger, several inches in
diameter. Some sessile irregular forms also reach
large sizes. Thus, Carpenteria consists of lobed conical
masses, ceasing early to grow spirally, and attached
to shells, &c.; dense sarcode protrudes through the
apical opening with siliceous spicules (?). Polytrema
is a scaly red encrustation on shells, &c., with no
spicules. The oldest known fossil, Eozoon, from the
Laurentian Serpentines of Canada, resembled these in

Introduction to Antmal Morphology. 53

habit.* Shell growth is slow, but injuries can be re-
paired. Monstrous forms are not uncommon.t

Over 2,600 forms are known, living and fossil, and of these
at least ten have survived from the Cretaceous period. They
occur in the seas of all climates, but are most abundant in
the superficial, littoral, and laminarian zones of tropical
seas. When they die they sink to the bottom, and hence
their dead shells are found at great depths.

Reproduction occurs by the formation of gemmules either
with or without encystation (Truncatulina). In Miliola,
granular, possibly reproductive, bodies have been seen, and
Rotalian shells have been found filled with black spherules.

Two orders are included:—1z. Imperforata, forms with
chitinous, arenaceous, or porcellanous shells, having only the
terminal aperture ; of these there are five families.

1st. Gromidze, test membranous one-celled, mouth simple,
pseudopodia hyaline, the shell may be ovoid (Gromiat), re-
tort-shaped (Lagynis), or globular with a wedge-shaped neck
(Sphenoderia), or the test may be scarcely detectible
(Lieberkiihnia). 2nd. Lituolide, shell arenaceous, often
coarsely grained (Astrorhiza, Lituola), or smooth, fine-grained
(Trochammina.) Valvulina is intermediate, with a perforate,
vitreous, basal lamina, covered by the sand grains. ‘The giant
fossils, Parkeria and Loftusia,§ are related here. 3rd. Cor-
nuspiridz, calcareous, one-celled, discoidal, coiled shells,
ex. Cornuspira. 4th. Mliliolide, many-chambered, por-
cellanous ; opening simple; whorls in one or several planes,
sometimes irregular, sessile, adherent (Squamulina, Nubecu-
laria||), or large, bottle-shaped (Dactylopora,] Conodictyum),
or discoidal (Orbiculina**), often Agathistegous (Miliola).

* Eozoon reached a large size, and was sessile, with numerous radial
canals, and a distinct proper chamber wall. Many other Foraminifera
make up rock masses. Fusulina, Miliola, and Globigerina are rock-forming
materials in the Carboniferous, Eocene, and Cretaceous series, respectively.

+ Dichotomous Nodosariz, double Polystomellz, &c.

} Freshwater.

§ Sometimes made the type of a family Parkeriadz.

|| Sometimes regarded as a separate family Nubecularide.

| Similarly separated as Dactyloporide, ** Separated as Orbiculinidz,

54 Introduction to Animal Morphology.

sth. Peneroplide, shells striated, brown, sometimes perforate,
with single, lobulate, or branched openings; shells helicoid,
ear-shaped, or discoidal, ex. Dendritina.

Order 2nd. Perforata or Foraminifera proper (D’ Orbigny),
shells vitreous, perforated, includes the following families :—
1st. Lagenide—monothalamous ; mouth circular ; shell hard,
finely perforated, ex. Lagena. znd. Orbulinide—monothala-
mous, with globose test. 3rd. Orthocerinida—chambers
successive, in a straight (Nodosaria) or bent line (Dentalina),
openings circular in the centre of the septum. 4th. Poly-
morphinide—cells alternating ; sides unsymmetrical, some-
times with a bifurcating axis, ex. Bulimina.* 5th. Cristel-
laride—nautiloid, finely perforate ; chambers encircling each
other, with an opening at the upper angle, ex. Cristellaria.
6th. Nonioninidz—vitreous, often siliceous; intercameral
opening at the lower angle, ex. Eozoon, Siderolithes,
Nonionina. 7th. Uvellinide—chambers uniserial, spiral,
turbinate, coarsely perforate, ex. Globigerina, spinose when
recent, Uvellina. 8th. Ro-
talinide—helicoid or tur-

Pigs 2.

binated, with embracing earl \\ We ues Mao

; \\\ WVHA Wht ff 7
chambers, ex. Rosalina, ~ \ AW WHY yp,
Rotalia. th. Borelide— \\\ WW pp

\\\ Vy ty

shell coiled onanelongated —~s
axis, divided by incomplete <<<
septa, ex. Borelis. roth. ~
Soritide—discoidal, with
cycloidal whorls of cham-
bers, ex. Cyclolina. 11th.

Conulinide—axis straight, G Ny 3S
thipt if WSS
mouth of many pores, ex. ~ /%Y Pin iN ANS
be

Y if
/ Hyp) i \ NS
Conulina. 12th. Textu- Wy / lik X\\' \\\
f 3 we Vi {\ ANY ' :
laride — axis elongated, fy yx
chambers symmetrical, al- are
ternate, double rowed,
(Frondicularia, Textularia). 13th. Cassidulinide—resem-
bling the last, but with the axis once curved perpendicular to

Globigerina bulloides.

* Made the type of a family Buliminidze,

Introduction to Animal Morphology. 55

the primary spiral. 14th. Nummulitide—finely perforate,
with a special septal plane differentiated from the rest
of the shell, without the ordinary tubular structure. Each
chamber wall is complete in itself, ex. Archeodiscus, Poly-
stomella,* Nummulites, Orbitoides, Fusulina ?

Probably these are not true families, as outward characters
are variable, and passage forms are numerous.+

CLASS 4. FLAGELLATA (Zhrenberg).—Nucleated plas-
tides, each moving by a long, permanent, whip-like
process ; reproducing by fission or gemmation ; motion
is by swimming or rolling (Doxococcus).

They are divisible into two orders:—1st. Monadina—
minute, vacuolated forms, with no differentiated ectosarc, and
simple flagella. These comprise two families :—rst. Mo-
nadidz—having a constant shape; reproducing by longitu-
dinal or transverse fission ; with one flagellum (Monas), or two
(Glenomorum); sometimes with a red speck (Microglena) ;
some are pear-shaped with a thick tail (Bodo), or the monads
may be in clusters, each with two flagella (Uvella). In
Anthophysa they are stalked, and have a contractile vesicle,
and in Polytoma the clusters of monadiform spheres produced
by incomplete division are within a hyaline cuticle. There
may be an oval (Cryptomonas) or a flask-like lorica
(Lagenella). Trichomonas has a few cilia as well as two
flagella.

Fam. 2nd. Astasiidz, with no lorica and a variable shape.
Colacium is parasitic on crustaceans ; others are free, with no
red speck (Astasia), or with one (Euglena) or two (Diselmis).
Peranema is rounded, tapering to the flagellum, with colour-
less granules and vacuoles within a thin cell-wall. There
may be several (Polyselmis), or two equal (Zygoselmis) or

* Sometimes separated as a family Polystomellide.

+ D’ Orbigny’s classification is embodied in a note on a former page: it
takes for its basis the modes of budding. Schultze divided them on the
same ground into Soroidea, Rhabdoidea, and Helicoidea,

56 Introduction to Animal Morphology.

unequal flagella (Heteronema*). Dinobryon has a loose
lorica, and reproduces by continuous gemmation ; hence it
appears as a branched colony, each plastide of which has a
pigment speck (absent in Epipyxis).t

Order 2nd. Noctiluce—transparent, phosphorescent, glo-
bose, metabolic animals, about 3'5’a5". The body has a
wide depression on one side (atrium), and a flagellum, con-
sisting of a clear cuticle over a closely-transversely-striated
axis, arising froma distinct papilla at its base ; near its root at
the bottom of the atrium is the mouth, opening into a short
cesophagus. On the inner wall of the tube is a ridge, and
from its floor springs a long cilium, near which are two brittle
rods. The cesophagus ends in a mass of protoplasm, from
which numbers of pseudopodia-like threads stretch in a netted
manner like a skeleton, to the surface, getting finer as they
approach it; along these threads vacuoles travel from the
cesophagus. Outside these threads lies an ectosarc not divided
into separate cell areas, but containing regularly disposed
nuclei. Reproduction is by fission,t gemmation,§ or by con-
jugation and encystation, two individuals having approximated
their mouths, their bodies become encysted. Another method
is by the formation of swarm-spores (Cvzenkowsky), the proto-
plasm mass segments into 2, 4, 8, &c. Onthe ectosarc (which
becomes saccular) arise surface tubercles, which form a disc
or boss, each of these becomes zoospore-like, and moves
about by its vibraculum.

CLASS 5. PROTOPLASTA|| (ZZaeckel).—Nucleated plas-
tides, having the central granule-, and vacuole-bearing
protoplasm (endosarc) surrounded by a firmer dif-
ferentiated layer (ectosarc), and often by a cuticle, so
that the blunt lobose pseudopodia cannot coalesce
when they come in contact (except in Actinophrys).

* The tail of the ametabolic Phacus is not to be confounded with a
second flagellum.

+ Some of these are probably vegetable.

{ Baddeley. § Gosse, Busch,

|| Lobosa, Carpenter,

Introduction ta Antmal Morphology. 57

Three orders are included :—1st. Catallacta (Haeckel)—
marine forms, intermediate between Protoplasta and Flagel-
lata; whose life-history consists of six stages: first, as a single,
quiescent, globular plastide, which becomes multicellular, ap-
pearing as a spherical body filled with pear-shaped cells, each
of which, at first stationary, begins to oscillate, becomes
ciliated and free by bursting the parent cell-wall. It then
assumes a peritricha-like form; its cilia thicken, coalesce,
and become transformed into pseudopodia, the plastides be-
coming ameeboid. To this order belongs Magosphaera
planula (Fig. 1, A), from the North Sea. Possibly Syncrypta,
Uroglena, and Synura (Uvella-like forms) may be spore
stages of allied freshwater forms, with one flagellum, as
Archer has noticed an amceboid stage in a Syncrypta-like
form. Some suppose these to be modified Sponges.

Order z. Amcebina—mostly freshwater, small,* with one
or more wall-less contractile vesicles, and sometimes a
structureless cuticle (Auerbach). Food enters by invagination,
and in some the effete matters are expelled only at a limited
area (villous region). They multiply by fission, gemmation
(the throwing off of a pseudopodium), or encystation (the
body becoming quiet, globular, slime-coated, losing its
nucleus and contractile vesicle; then the endosarc divides
into spherules, which traverse the ectosarc and become free,
amcebiform). Arcella and Difflugiz have been seen conju-
gating by Cohn.t| Carter saw two amcebz united (either con-
jugation or incomplete gemmation, Schnezder). Difflugice and
Arcelle{ have been seen dividing within their tests into rest-
ing spores (Schneider, Perty). Carter has seen the nucleus in
Amoebe and Euglyphze becoming granular, and supposes it
to be connected with a sexual form of reproduction.§ There
are three families :—1st. Amcebidz, with no hard test, shape
constantly changing, owing to their inconstant pseudopodia,

a oo Te zs00'°

+ In some cases, the individuals conjugating were of different sizes and
colours.

+ Schultze saw the same in the Rhizopod Gromia.

§ As some higher animals pass through amcebiform states, some believe
all these to be larval forms,

58 Introduction to Animal Morphology.

which are protruded at all sides (Amceba), or at one side only
(A.limax), or radiating from one end (Petalopus). There
may be a delicate test, but not sufficient to prevent the
alterations in shape, incompletely (Pseudochlamys) or com-
pletely enclosing the body (Corycia), or a hyaline coat pene-
trable by the pseudopodia, after the retraction of which the
openings disappear (Amphizonella). In Pamphagus, lobose
pseudopodia protrude at one end, while in Diplophrys they
are as tufts at each end. Boderia is a giant Amoeba, repro-
ducing somewhat as Magosphera by pseudo-navicellar, but
non-ciliated, bodies (7. S. Wright). Podostoma has flagelli-
form pseudopodia.

Fam. 2. Arcellide—(Fig. 3). Test firm, one-celled, it may
be ovoid, coated with fine agglutinated sand-grains (Difflugia),
witha down-directed mouth, orhyaline, flattened, facetted, often
striated siliceous (?), with branched
pseudopodia, and many contractile
vesicles (Arcella), Euglypha has a
regularly sculptured chitinoid test
with depressions. Cyphoderia is
spinose. Amphitrema hasan opening
at each end from which pseudopodia
project. Echinopyxis sends its pseu-
dopodia through short tubular pro-
cesses of its test. Flatoun, Parvars,

Fam. 3. Actinophryide—Minute, spheroidal, freshwater,
slow-moving animals, with constant, radiant, ectosarcal pseu-
dopodia, which often unite at their tips. The contractile
vesicle is near the surface, and when distended appears as a
bubble. The ectosarc is marked by polygonal meshes of
granular protoplasmic threads enclosing vacuoles. They
multiply by fission. The globular forms are named Actino-
phrys, if stalked, Podophrya,* if depressed with marginal
pseudopodia, Trichodiscus. Clathrulina has a_ globular
stalked shell of lattice-work, through whose holes the pseudo-
podia protrude.

Fig. 3.

* If the pedicle be branched, Dendrosoma,
+ Siliceous, Greef.

Introduction to Animal Morphology. 59

Order 3. Heliozoa—(Fig. 4). Protoplasta with radiant pseu-
dopodia, often confounded with the last, but having a dif-
ferentiated endosarc containing nucleated masses, and a vacuo-
lated ectosarc, which appears alveolated. Each pseudopodium
is compound, having a firm endosarcal axis and a hyaline
granule-bearing ectosarcal surface-layer.* The endosarc has
no central capsule. They multiply by division, natural or
artificial, also (in Actinospherium) by encystation and the
division into many (10) resting spores, each in an Arcella-
like siliceous hexagonal test.
Raphidiophrys has fine siliceous
spicules traversing the large
green spherules, which make up
the body. Acanthocystis is
rounded with movable, straight,
bifid, hollow spines, discoidal
at the base, and curved flexible
spicules.| Actinosphzrium is
globular, like Actinophrys in
shape. Cystophrys has an irre-
gular body, and many spherical
endosarcal nucleated cells like
the yellow cells of Radiolaria.
Heterophrys is globular, with
no spicules, and unbranched pseudopodia, but with central
cells. Diaphoropodon has a difflugia-like test of foreign
bodies. These are mostly freshwater forms, and many have
recently been discovered by Archer, Greef, and Focke.

Fig. 4.

Heliosphera radiata Sch.

* Tn feeding, these do not surround the food, but draw it into the
ectosarc.
t+ It is often the nidus of a Rotatorian.

60 Introduction to Animal Morphology.

CHAPTER Ee
RADIOLARIA; &C:

CLASS 6. RADIOLARIA (JZ7il/er).—Heteroplastic per-
sone* or colonies,t with radiating, often anastomosing,
pseudopodia. The endosarc is enclosed in a chitinoid
central capsule,t pierced by fine pores, and consists of
fine cells, pigment, fat spheres, crystals, and protoplasm,
often with a median, sometimes compound, vesicle
(b2nnenblase or vesicula wntima) in its centre. The pro-
toplasm varies from extreme fluidity (Collospheride)
to firmness (Acanthometride). The skeleton consists
of spicules of silica or acanthin,§ lying outside, or
radiating and piercing through the central capsule.
They may be solid, clear, or striated (as in Dorataspis),
or hollow, with a central canal traversed by a thread
of protoplasm, which projects like a flagellum. The
radiating spicules passing from the centre through the
capsule are often joined regularly or irregularly by
tangential beams, making up ornamental forms like
discs, flower baskets, &c. The tangential beams may
exist with no radiant spicules. Within the central
capsule large nucleated cells sometimes exist, and
concretions of leucin and tyrosin (Kollker). In
the ectosarc there are alsocellular bodies and pigment
spots; and a layer of large alveolar cells often sur-
rounds the central capsule. Characteristic of the

* S050" — vo" ¥ a= 2)

t Largest in Zygostephanus, smallest in Physematium.

§ Acanthin occurs in Acanthometridz, is of cartilaginous consistence, de-
stroyed by concentrated sulphuric acid. It seems to be the base in which
silica is, sometimes at least, laid down, as some acanthin spicules silicify
with age,

Introduction to Animal Morphology. 61

group are large yellow cells found imbedded in the
sarcode, each included in a colourless membrane:
these yellow cells are short-lived, and multiply by
fission or endogenously. Their nuclei are sometimes
red, and often resist the action of caustic alkali, as
if encapsulated. Their number is variable, and not
constant in any species; but they are rarely absent
except in some Acanthometride. As they have been
seen living and multiplying when the rest of the body
was dead, Czenkowsky conjectured that they may be
parasitic, but they are too constant to be so.

Radiolaria are found either floating on, or at the
bottom of, the ocean, and they multiply by swarm-
spores or germs, developed from the contents of the
central capsule. JZilicr saw the inside of an Acan-
thometra full of monadiform vesicles, which became
actinophrys-like. Haeckel noticed the capsule-con-
tents of Spherozoum breaking up into vesicles, and
saw some of these vibrating. Schwerder saw amceboid
vesicles with movable flagella in Thalassicolla. The
formation of these swarm-spores was minutely traced
in Collosphera (which has a fenestrated shell) by
Crenkowsky ; here the contents of the capsules break
into little spheroids, which become monadiform, bici-
liated, and pass through the holes in the shell, each
spore with a crystalline rod, and a few oil globules
within. Young Radiolarians have no central capsule,
thus showing their relations to Heliozoa. The shells
of Radiolaria are abundant in some Tertiary deposits:
those from Barbadoes earth are well-known as
Polycystina. They existed as far back as the days of
the Carboniferous formation, if the genus Traquairia
be a true Radiolarian.

62 Introduction to Animal Morphology.

Radiolaria are divided into two orders :—1st. Monocyttaria,
including the forms with a single central capsule. This in-
cludes sixteen families, grouped into three series according
as they are devoid of spicules (Nuda), or possess spicules in
the ectosarc (Ectolitha), or traversing the central capsule
(Entolitha). There is one nude family:—1. Thalassicollide,
with a globular, double contoured, central capsule, often
marked polygonally on its surface, including Thalassicolla.
Thalassolampe has no alveoli round the central capsule.
Of Ectolitha there are seven families :—z. Myxobrachide,
including large, soft, floating forms, with one or many con-
tractile processes ; the vesicula intima is constricted radially
into a number of oval bladders. At the ends of the processes
are calcareous concretions, either separate oval, lenticular, or
oat-shaped (Coccoliths), or in clusters (Coccospheres).
The yellow cells contain starch. These calcareous masses,
and others cup-shaped (Cyatholiths) or rod-like (Rhabdo-
liths), are found in myriads imbedded in Bathybius, and in
the mud of the Atlantic bottom, but nowhere else have they
been found organically united to a definite body than in the
arms of Myxobrachia (Haeckel).

3. Thalassospheride, with tangential or radial skeleton of
ununited, solid (Physematium, &c.), or hollow (Thalasso-
planeta) spicules around the central capsule. 4. Aulacan-
thide, with hollow spines, partly tangential, partly radial,
serrated, and loosely united. 5. Acanthodesmiade, with few,
loosely united, sometimes ribbon or buckle-like spines. 6.
Cystidz, with the tangential skeleton forming conical or cup-
like forms, with only one pole closed, and the central capsule
at that end; there may be no mesial constriction (Litharach-
nium, &c.), ora longitudinal narrowing, dividing the body into
lateral chambers (Petalospyris, &c.), ora transverse constriction
(Lithomelissa) or several transverse constrictions(Eucyrtidium),
or several both transverse and longitudinal (Botryocampe, &c.),
The central capsule is often 4-lobed (Eucecryphalus, &c.)
7. Ethmospheridz, with a globular, basket-like skeleton, with
radiating bars not piercing the central capsule (Heliospheera).
There may be two concentric spheres (Diplosphera), or more
(Arachnosphera). 8. Aulosphzridz, with hollow, tangential

L[ntroduction to Animal Morphology. 63

spicules, loosely connected into a capsule, from which
radiating spicules pass, with whorls of spines along their
length. The meshes of the capsule are three-angled, and
the double-contoured central capsule is freely movable
within.

The Entolitha include eight families :—9. Cladococcide,
forming a basket of solid radiant spicules. 10. Colodendride,
similar, with hollow spicules. 11. Acanthometridz, with no
framework round the central capsule, but twenty radiant,
symmetrical, acanthin spicules piercing it, either fused to-
gether in the middle (Astrolithinze) or with wedge-shaped
ends lying symmetrically beside each other (Acanthometrinz),
or only traversing the capsule, and not united at the centre
(Acanthochiasmine). The spicules are irregular in Litho-
lophinze-; some have no yellow cells. 12. Diploconide,
capsule not basket-shaped, open at both ends, narrow in the
middle (dice-box shaped), with a strong-pointed spicule tra-
versing the central capsule. 13. Ommatidz, with a globular
framework bound together by radiating spicules piercing the
capsule. There may be one such frame and twenty rays
(Dorataspis), two (Haliomma), or more (Actinomma). 14.
Sponguride—The ento-capsular skeleton is spongy, and to
this a system of radial spicules and an inner regular basket-
work is often added. There may be, within, one or more of
these lattice spheres, and an outer, irregular, sponge-like
skeleton (Spongosphezrinz), sometimes as many as three of
these spheres, as in Spongodictyum, or there may be no inner
lattice sphere and irregular compartments in the outer
sponge mass (Spongodiscinz), or concentric inner chambers
and no lattice sphere (Spongocycline). 15. Discidz,
skeleton discoid or lenticular, with one or more concentric
trellis-spheres, including the central capsule (Coccodiscine),
or with the central chamber not so included, and spiral or
concentric, ringed cavities in the skeleton (Discospirinz).
16. Lithelidz, skeleton of several discs whose compartments
are arranged spirally on a common axis.

Order 2. Polycyttaria—Colonies ; several central capsules
in acommon sarcode. This order includes two families :—
ist. Sphzerozoide, having the central capsules included in a

64 Introduction to Animal Morphology.

common stock of vacuolated protoplasm, with no skeleton
(Collozoum), or a few needle-like, tangential spicules
(Sphzrozoum). Raphidozoum has four-rayed, differentiated
spicules. 2nd. Collospheridz, each central capsule sup-
plied with a perforated sphere whose openings are simple
(Collosphera) or tubular (Siphonospheera).

CLASS 7. GREGARININA.—Mostly parasitic, there-
fore degraded, forms,* one- or spuriously two-celled,+
with a distinct imperforate cuticle, on which may be
Striae, knobs, ciliiform threads (Monocystis agilis),
hooks or spines. They have no pseudopodia, but the
ectosarc shows undulatory contractions from behind
forwards. There is always a nucleus, often fat
particles in the endosarc, but no contractile vesicle.t
Sometimes there is a differentiated sub-cuticular layer
of transverse moniliform fibres (in G. gigantea of the
Lobster$). Food enters by endosmose or by invagina-
tion. Reproduction is by encystation, sometimes pre-
ceded by conjugation.|| In the one-celled forms, the
body becomes globular, the nucleus vanishes, and the
contents form roundish, lanceolate bodies (pseudona-
vicellz), which become free, and each bursting emits
an active amceboid plastide, which by degrees be-
comes developed into a Gregarine (Lzeberkihn). In
G. gigantea, the amceboid bodies are first gymno-
cytodes, which become quiescent and spheroidal; then
a tail-like process projects, or sometimes two, which

* A few free in decaying timber (Hiidner).

t The cuticle does not dip in between the cells, but the septum consists
of ectosarc alone.

t In Dicystidean forms, the nucleus is in one compartment alone, the
posterior.

§ Lankester regards this as only thickened cuticle.

|| In G. longissima three have been found united.

Introduction to Animal Morphology. 65

are close together: one slender, shorter, and im-
movable; the other, stouter and movable. The latter
becomes detached, and looks like a nematode, and the
rest of the body also elongates into a worm-like form.
(These pseudo-filarie have, perhaps, been taken for
nematodes by Bruch and Leydig.) Both these worms
dilate at one end, and narrow at the other; their
movements slacken, a nucleus and nucleolus appear,
and an outer membrane forms: thus Fig. 5.
they become perfect Gregarines.

They are found in the intestines of
Invertebrates, chiefly Arthropods,rarely
in Vertebrates. Allied forms called
Psorospermia may be stages of un-
known Gregarines, and consist of
spindle or pear-shaped cells, often
tailed, with clear rounded bodies ata. Monocystislumbrici.

. Pixinia rubecula.

: B

their smaller end, and a protoplasm. Pseudonavicella’ of
- . F 4 Zygocystis sp.

mass which sometimes is emitted asD. Amebiform stage.

an amcebiform body. They occur abundantly in the
muscles, &c., of Fishes and other Vertebrates.

Two families exist :—1. Monocystidea (S%ezz), with one
compartment and a central nucleus; including Mono-
cystis, found in worms (Fig. 5, A), the valves of the
human heart, human kidney, pine-wood, beetles, Eunice,
Nemerteans, &c. 2. Dicystidea, having two compartments,
with a septal layer of ectosarc between, and the nucleus in
the posterior ; including Stylorhynchus, with hooks round the
head, found in Calopteryx ; Didymophyes, with three parts,
head, fore, and hind body; <Actinocephalus, with spines
round the head ; Gregarina, with no hooks, found in Ephemera
Lobster, &c.; Pixinia, with hooks and a head separate from
the front segment of the body (Fig. 5, B).

Leuckart and Diesing have shown that gregariniform
bodies are developed from the eggs of Echinorhynchus
Proteus (Gregarina miliaria and diffluens).

a

66 Introduction to Animal Morphology.

CHAPTER X.

INFUSORIA.

CLASS 8. INFUSORIA (Wrisberg).—Minute (22s0" — v2”)
ciliated bodies, probably simple plastides, or, at most,
cytocormi, with a firm chitinous cuticle, an ectosarc
and an endosarc, a contractile vesicle and a nucleus.
A separate tubular fold of cuticle may form a sheath
distinct from the outer body wall (Vaginicola), or the
hinder end may be extended into a pedicle or an
anchor apparatus (Trichodina). The cilia may cover
the whole surface, and be all of the same kind
(holotricha), or some may be long or specialized into
styli, sete, uncini (heterotricha). They maybe on the
under surface alone (hypotricha), or only on a peri-
stome around the mouth (peritricha). Sometimes an
undulating membrane takes the place of cilia (Undu-
lina Pleuronema). The integument in Paramecium,
Nassula, Bursaria, &c., includes sharply contoured
trichocysts like those of Turbellaria, considered as
touch-organs by Sez, or as poison-organs by Leuckart.
Beneath the cuticle in Stentor, Prorodon, &c., is a
contractile, striped material, possibly a simple form of
muscle. In Spirostomum these striz are spiral, and
the body contracts in their direction. The contractile
stalk of Vorticella has also a_highly-refracting
muscular axis (Kzihne ; its muscularity is denied by
Meczntkow, as it is structureless, myophanic). The
outer layer of this stem is cuticle, and it straightens
the stalk by its elasticity. There is usually a mouth,
which may only be seen during feeding (Amphileptus,
&c.), or it may havea ciliated pharynx (Paramecium),

Introduction to Animal Morphology. 67

in which rod-like chitinous bodies—‘ teeth’’—may
exist (Nassula, Prorodon, &c.) There is Fig.6.

usually an anus, which may be posterior,
anterior, or in the vestibule of the mouth.
The pharynx penetrates to the endosarc (or
endoplasma), and terminates therein some-
times with a valve (Glaucoma); the food
there passes round in the protoplasm, often
in vacuoles, and is digested. The ectosarc Section of Pa-

ramzcium.
m. mouth.

(ectoplasma) is firmer, more homogeneous, 7? Mitractile
and possesses a contractile vesicle at either ,, Necicle.
or both ends. These contract rhythmically, often fifty
times in a minute, and the fluid within is expelled
into the parenchyma or out by surface-pores. One
or many canals may be attached to this vesicle:
(1, Spirostomum ; 8.10, Parameecium ; 30, Bursaria).
They appear to have definite walls, and are filled when
the vesicle contracts, or wzce versa. In Stentor there
is a circular canal around the mouth connected with
the vesicle. The contractions of these vesicles are
independent of the circulatory movement of the
protoplasmic endosarc, which is usually active, al-
though the contained granules are not contractile.

The body in Trachelius ovum
(Fig.7) consists ofan endosarc of pro-
toplasm threads, forming irregu-
lar meshes, whose interspaces are
filled with water. These threads
functionally represent the endosarc
of other Infusorians, but remind us
of Noctiluca. The ectosarc is
thin, and its contractile vesicle is
lenticular and flattened.

The only possible sense-organs Section of Trachelius ovum.

a. mouth.

F 2

68 Introduction to Animal Morphology.

are the pigment spots in Ophryoglena, which may be
photoscopic eyes, and consist of highly-refractinge
granules on the convexity of a clear, watch-glass-like
body. The latter structure exists in Bursaria without
pigment. Below the pharynx in Opercularia are two,
reniform, solid organs of unknown nature. A solid
body (nucleus) exists in all, sometimes movable, and
generally oval, band-like (Bursaria, Trachelius), or
string-like (Ophryoscolex), sometimes bent round the
pharynx (Vorticella). Within or beside the nucleus is.
a rod-like nucleolus.

Reproduction is by longitudinal, transverse, or
diagonal (Lagenophrys), fission, gemmation (Vorti-
cella), encystation, internal gemmation (Loxodes
bursaria, Cohn), or sexually by conjugation, often of
unequal individuals (Paramecium). The nucleus
(ovary) splits into spheres, or ova; the nucleolus, into
thread-like or rod-like spermatozoa. These become
interchanged in the two conjugating individuals, and
the ova develop. Sez describes having seen a brood-
canal for the extrusion of the germs.

These animals abound in stagnant waters, infusions,
&c. Some are parasitic, and a few marine, some of
which are phosphorescent. They may be divided pro-
visionally into four orders.

1. Opalinzea—oval, parasitic, sluggish, and mouthless ;
with a ligulate nucleus, no contractile vesicle, but several
permanent saccular spaces, or a contractile canal in O. Plana-
riarum and O.uncinata. They may be holotrichal, or the
cilia on the under surface may become uncini (Alastor), or a
wavy undulating membrane may replace the cilia (Undulina).
A mouth-like depression, with a row of comb-like cilia, exists
in Plagiotoma. ‘They increase by transverse fission, are found
in the intestines, &c., of Frogs, Newts, Molluscs, &c., and

Introduction to Animal Morphology. 69

may be, as Agassiz supposes, early stages of Trematode
worms.

2. Peridiniea—mouthless (mouth-bearing, Schmarda), free,
loricated forms, with a transverse ciliated furrow, no con-
tractile vesicle, but with a nucleus, vacuoles and chlorophyll
granules. Some have a red pigment spot (Glenodinium) ;
others have two or three long, curved, horn-like processes
(Ceratium). The lorica is often double, chitinous (or siliceous ?).
Many are marine, and vividly phosphorescent ; they multiply
by longitudinal or transverse fission, and have been seen full
of globules (Perty). Bazley regards some of these as Annelid-
larve. ‘They unite Flagellata and Infusoria.

3. Acinetina—stalked, membrane-clad forms with radiant,
retractile, tubular processes, whereby nourishment is sucked
in (hence called Suctoria by Claparéde, and Polystoma by
Greene). The stalk is an extension of the cuticle, and is
sometimes striated. ‘The processes may be branched (Den-
drocometes),* or in bundles, especially when the body is
lobate ; sometimes only one suctorial arm may exist (Rhyncheta,
parasitic on Cyclops). ‘The endosarc contains granules, anda
nucleus with apparently an investing membrane. The
ectosarc includes one or more contractile vesicles. By the
processes which the animal applies to its host, currents of food
granules enter and coalesce within into food globules. They
multiply by gemmation, rarely by fission. We know little of
their life-cycle. Some are, perhaps, as S/ezz supposes, larval,
but this is denied by Claparide and Lachmann. Eberhard saw
one form becoming ciliated and changing into Bursaria
truncatella. Ophryodendron is commensal with Plumularia,
and has two classes of zooids, proboscidean and lageniform,
both mounted on curved stalks.

4. Stomatoda includes the mouth-bearing forms, and con-
sists of four sub-orders :—1. Peritricha, with a ciliated peri-
stome, including five families :—1. Vorticellide (Fig. 8, C)—
stalked, bell-shaped forms, with mouth and anus opening inside
the peristome. The stalk may abort and the bell be sessile
(Scyphidia, Gerda), or it may be rigid, branched or un-

* The larva of Spirochona gemmipara (Stez7).

70 Introduction to Animal Morphology.

branched, with (Spirochona) or without (Epistylis) a spiral
leaf-like appendage to the peristome. The stalk is flexible,
unbranched in Vorticella, and on irritation contracts suddenly
into a close spiral. They multiply by longitudinal fission,
one half, being freed from the stalk, developing a posterior
crown of cilia, and a mouth at that side, while a new stalk
grows at what before was the anterior end. Buds may form
at the base of the bell, or encystation may take place, the
nucleus splitting into monadiform bodies, each of which, be-
coming free, develops into an Acineta (Svei). Carchesium
has a branched flexible stalk, but the muscle-band in-each
branch is independent. Zoothamnion has a_ branching
muscle, as well as stalk, and some of the buds thereon remain
permanently globular and unexpanded. Urocentrum has a.
pedicle, but is unattached.

2. Trichodinidze—urn-like, with
an anterior and posterior crown of
cilia, peristome not capable of
closure. ‘Trichodina, parasitic on
Hydra, has an anchor apparatus at
the posterior end, consisting of a
chitinous ring with two rows of
recurved uncini, and a flexible,
finely striated collar outside this
and above its base. Halteria has Eb
two similar ciliary crowns, but nO “4 o.seicha gibba. .

anchoring apparatus. B. Trachelocerca biceps.
Byivs C. Vorticella citrina.

3. Ophrydinide—often clustered, included in a sheath,
seldom stalked. If the lorica be gelatinous, and by imperfect
division hold together the perfectly divided animals, they
form soft masses often over an inch in diameter (Ophrydium).
In isolated forms the animal may be sessile in the lorica
(Vaginicola), or stalked (Tintinnus), or the lorica itself may
-be rigidly stalked (Cothurnia).

4. Dictyocystidz are marine forms with a siliceous, per-
orate, bell-shaped shell like that of a Radiolarian. Codonella
is closely allied, with a bell-shaped perforate test and a double
peristome; it is made the type of a separate family by
Haeckel.

Fig. 8.

C

Introduction to Animal Morphology. Vik:

5. Ophryoscolecidze—naked forms (found in the paunch
of Ruminants) with an anterior crown of a few cilia.

Sub-order 2. Holotricha—uniformly ciliated, including
seven families. 6. Cyclidinidz—aproctous, body flat or oval,
sometimes bristly, Cyclidium. 7. Enchelide—mouth and
anus at opposite poles; pharynx with no teeth ; body naked,
oval (Enchelys), or with a long, narrow neck, and a laterally
lipped mouth (Lacrymaria). Leucophrys is parasitic, with a
wide neck and an ad-oral ciliary spiral. 8. Chilodontidz
have an oval, striated surface with rows of cilia, mouth tubular,
anterior (Prorodon), or beneath, with lips and tooth-like pro-
cesses. The teeth may be numerous, as a wheel-like circlet
of hooks (Nassula), or with a lip-like anterior process
(Chilodon). In these, living embryos arise by a process of
encystation. Wagneria, whose mouth apparatus resembles
that of Prorodon, has two distal ciliated zones like
Trichodina. 9. Colepide—loricated, with mouth and anus
at opposite poles ; shell striated, perforated, toothed in front
and behind. 10. Tracheliidze—ciliated, shell-less, longitudi-’
nally striated, oval or irregular, with an antero-inferior mouth,
no teeth, and a narrow anterior proboscis, with sometimes
eyelid-like valves to the mouth (Glaucoma). Trachelius is
mentioned before (p. 67, Fig. 7). 11. Ophryocercide—
mouth anterior, anus ventral; the front end is sometimes
bifid (Trachelocerca biceps, Fig. 8,B). 12. Colpodide—shell-
less, mouth and anus ventral, sometimes with a tongue-like
tuft of oral cilia (Colpoda, common in hay infusions), or
with eye-specks (Ophryoglena). Amphileptus has no tongue-
like process, and is narrowed fore and aft into a proboscis
and tail. Uroleptus has only a tail. Paramecium (Fig. 6),
very common; has a compressed slipper-shaped body, a
lateral mouth, and stellate contractile vesicles.

Sub-order 3. Heterotricha—possessing a second, longer
set of cilia near the mouth, and fine cilia over the body.
This includes two families. Bursaride, with the mouth at
the bottom of a deep slit, not anterior, and guarded by long
cilia. The anus is posterior; the peristome is not spiral.
Bursaria is parasitic (in Man, Swine, Frogs). Spirostomum,
the largest Infusorium, is flattened and elongate, with a

72 Introduction to Animal Morphology.

moniliform pulsating vesicle. 14. Stentorida—funnel-shaped,
naked (Stentor), or surrounded by a gelatinous capsule, with
a spiral peristome of long cilia, mouth and anus close in the
same groove; nucleus moniliform; front of the body two-
valved (Freia) or ribbon-like, spirally inrolled (Chzetospira).

Sub-order 4. Hypotricha—only ciliated on one (the
under) side ; including four families. 15. Oxytrichidz—pos-
sessing bristles (Oxytricha, Fig. 8, A), hooks (Kerona), or styles
(Urostyla), or both hooks and styles (Stylonychia), by help of
which they can walk; shell-less, or with very thin test and
marginal cilia; one form (Kerona polyporum) is parasitic in
Hydra. 16. Euplotide—with a distinct test, hooks and
styles, ex. Euplotes. 17. Dysterida—with a tail-like foot,
and a membranous carapace of two separate (Iduna), or united
valves (Dysteria), or with no carapace (Huxleya). 18. Aspi-
discidz—shield-shaped, with a test; cilia reaching to the
anterior edge ; pharynx not obvious ; locomotory process as in
Euplotide, but with no fine cilia.

CHAPTER XI
SUB-KINGDOM II.—POLYSTOMATA (fuzxley).

AQUATIC animals, made up of differentiated plastides,
bounding a central cavity, thus forming Gastrule.
The cavity communicates with the external water by
many pores or interstices between the cells of the wall,
as well as by one or more terminal mouths or oscula
formed by absorption at one point in the wall of the
polyplast (Haeckel), or by invagination (in Sycon
ciliatum, J/etschnikoff). Sexual reproduction often
occurs, but there are no highly specialized tissues.

There is one class included :—

CLASS 1. PORIFERA (Gvant)—Sponges, whose
characters are those of the sub-kingdom.

Introduction to Animal Morphology. 73

The plastides are, in simple Sponges, arranged in
two layers, forming an outer (ectodermal) and an
inner (endodermal) wall for the central cavity. They
may be cytodes or cells, often amceboid and naked, or
with a thin, rarely a thick, cell wall; some or all of
them being ciliated or flagellate. In some forms the
protoplasm is undifferentiated, with free nuclei. The
interstitial pores often are inconstant, but may become
branching varicose canals. The walls of the central
cavity frequently become irregularly folded, and by
‘coalescence of the several folds and dilatation of their
communicating pores, the single central cavity be-
comes the focus from which irregular tubular branches
pass; by lateral budding, new zooids form beside the
older ones, and the branches from the central cavities
of each, communicate with the irregular sinuous inter-
zooidal spaces, thus giving rise to the complicated
system of passages found in such colonies as those of
the common toilet Sponge. In some the pores enlarge
into pseudoscula (Geodiine), or even into true oscula
(ALtklucho-Maclay).

Sometimes, as in Axinella, and less distinctly in
Raphiophora, there is a regularly radiant system of
canals from the osculum, foreshadowing the radial
symmetry of Ccelenterates.

Through the surface pores currents of fluid enter
the body cavity, propelled inwards by the cilia or
flagella of the lining plastides,* and expelled through
the large osculum or efferent aperture. The lining
plastides are nourished by the organic particles in the

* These may be uniformly distributed, or else there may be here and
there small cavities lined by ciliated cells, while the intervening passages
possess only amcebiform plastides.

74 Introduction to Animal Morphology.

passing fluid, which they take in after the manner of
Rhizopods, so that each plastide nourishes itself, as.
do the separate plastides of higher organisms.’ In
rare cases (Guancha blanca), the osculum serves as a.
mouth, taking in, as well as ejecting, the water
(Mrklucho-Maclay). The pores may close, and the
osculum diminish in size, by contraction of the sur-.
rounding plastides. The osculum may be simple, or
may have a circlet of lobes or papilla, forming a
rudimental tentacular crown, asin Osculina. In some
forms, true connective tissue is differentiated beneath
the plastide layer in the lining of the central cavity,
partly accompanying the canals and partly traversing
the sarcode. In the intermarginal cavities of Geodia,
fusiform contractile cells, identical with smooth
muscle-cells, also exist.

The surface plastides of many are differentiated.
into a uni- or multi-lamellar epidermis, often conti-
nuous over a whole colony. This layer in Reniera*
and Desmacella contains thread cells like those to be:
described in the next sub-kingdom (Fig. 10). Under
this cuticle are often extensive sub-cuticular and inter-.
marginal spaces, into which open surface pores from
without, and the canals of the zooids from within.

The individuality of a Sponge has been a matter
of dispute. Carter and Yames-Clark regard the
“‘sarcoids”’ or separate plastides as morphological in-
dividuals ; but the arguments in favour of this theory
would equally apply to the separate endoplasts of a
Ceelenterate, or to the white corpuscles of the human
blood. The view of zooidal individuality stated above

* Cnidz are also found around the spicules, and especially about the
stomach, in Reniera (Z7mer).

Introduction to Animal Morphology. 75

is the only one consistent with the varieties of structure
presented in the class.

The plastides are usually supported on spicules of
calcium carbonate, silica or horny matter (Spongiolin),
which are formed by the deposition of the indurating
material inaprotoplasmicbase. The mineral spicules
are not crystalline, but laid down particle by particle,
often in lamine. They sometimes have a central
cavity filled with an organic material (protoplasm *),
for, when heated, they often burst at one end, and be-
come blackened inside.

In size the spicules vary from 35” — 1’ (Hyalonema).
They are named from their shapes, and may be bi-, tri-, or hex-
radiate, according to the number of diverging rays; or, if
quinque-radiate, may have long or short axes, and simple or
forked rays. Some are simply acerate (needle-shaped), pin-
shaped, club-shaped, fusiform, cylindrical, furcate, radiate,
spinulate, rotulate (wheel-like), or birotulate (like two-toothed
wheels joined by an axle), or sinuous. Some are hamate
(hooked), or C- or S-shaped; others umbonate, anchor-like,
candelabriform or spheroidal. These names are sufficiently
expressive. The spicules are supposed to discharge different
functions, and are grouped into:—1st. Skeletal or essential,
supporting the body. 2. Connecting, retaining the outer
layer (when it is differentiated) in connexion with the interior.
3. Prehensile—projecting as a means of attachment to other
bodies. 4. Defensive—projecting externally to prevent their
being preyed upon. 5. Spicules of the surface membrane,
which may strengthen or support its plastides; these may be
either (a) tension spicules to keep it stretched, or (8) retentive
(hamate or anchorate), keeping it in its place.

Reproduction takes place :—1ist. Sexually, by the
differentiation of some of the deeper plastides, along
the line of the larger canals, into ova; others are con-

* Candelabriform spicules are solid.

76 Lntroduction to Animal Morphology.

verted into mother-cells, whose nuclei become sper-
matczoa, and rupturing the cell wall these flagellate
bodies are emitted, and fertilize the ova, which become,
by segmentation, first morule, then ciliated germs,
with a bilaminar membrane surrounding a central
cavity (planule), whose pole becomes thinned and
perforated by absorption (//aeckel ; Metschnikoff de-
scribes the cavity in Sycon ciliatum as formed by
invagination). Sexual reproduction has been detected
in Tethya, Reniera, many Calcispongia, &c.

2nd. Asexual reproduction may occur by division,
natural or artificial, or by budding, either continuously,
thus forming colonies, or discontinuously, by the for-
mation of detached gemmules. In the freshwater
Spongilla these are either ciliated plastides or swarm-
spores, or else rounded masses found in the older
parts of the animal’s body, consisting of a central
cluster of soft cells surrounded by a globular coriaceous
capsule pierced by an opening, and outside which is
a crust containing radial, dentated birotulate spicules
(Amphidiscs). These ‘winter eggs’’ grow in spring
by processes protruded through the infundibulum, or
opening. .

Sponges are divisible into eight orders :—

Order 1. Halisarcia—a doubtful group, including soft,
skeletonless forms, probably immature states of other Sponges.

Order z. Ceraospongia—Sponges with a skeleton of
Spongiolin fibres, 0.07 — 0.004 mm. in diameter, making an
irregular horny. net-work. These may be similar, homo-
geneous, structureless (when young), or consisting of con-
centric laminz (Spongia, Ditela) ; or with a differentiated axis
(Verongia, Aplysina); or an axis of sand grains and of the
spicules of other Sponges (Dysidea): or of special spicules,
either fully included (Chalina) or projecting on the surface
(Clathria); or else some fibres may be coarse and with a

Introduction to Animal Morphology. iW

sandy axis, while others are fine, homogeneous (Hircinia).
Auliskia has its fibres traversed by an Algoid 2? Cacospongia
is loose in texture, with laminated, slightly elastic threads.
Spongelia is hard, brittle, and scarcely elastic.

Order 3. Gummine—horny, caoutchouc-like Sponges
composed of densely interwoven homogeneous or striated
fibres, or of mucous tissue imbedding stellate spicules. In
the basis are often cartilage-like cells (K@él/zker). Spicules
may be candelabriform (Corticium), or none (Gummina), or
there may be an outer surface of compacted fibres and stellate
spicules (Chondrilla).

Order 4. Halichondrize—siliceous Sponges, with no cortical
layer, and a small amount of Spongiolin, with no anchorate
nor defensive spicules. ‘They may be massive, with cylindrical
needle-like spicules (Halichondriidz) ; or rugose, with simple
spicules usually pointed at both ends (Reniera); or blunt,
often knobbed at the end (Suberites). Ancorina is fleshy,
with acicular spicules. Clionidz are mostly boring Sponges,
with pin-shaped spicules, perforating oyster-shells, limestone,
&c. They have often two kinds of papilla, pore-bearing,
small, and osculum-bearing, larger, fewer. The surface may
be beset with siliceous polygonal plates (Cliona), or mulberry-
like bodies (Thoosa). Raphiophora patera (Neptune’s cup)
is a large goblet-like Sponge, 2-4 feet in height, with
numerous octoradiate oscula. Raphyrus isan allied, irregular
form. The family Arenospongide, including the genus
Xenospongia, which forms a disc of agglutinated sand, and
possesses diverging spicules in the sarcode and around the
oscula, may be worthy of ordinal rank.

Order 5. Corticateaa—globose, tuberous or branched, with
an outer cortex containing spiculigerous corpuscles, and an
inner layer of Spongiolin threads and siliceous needles, often
in radiating sheaves. Sometimes the cortex is thin, mem-
branous (Tisiphonia), or thicker, provided with siliceous:
globules and needles (Geodia), or globules only (Caminus).
Pachymatisma has short fascicles of spicules, and an unsym-
metrical central mass. Tethya is massive, sub-orbicular, with
a skeleton of fasciculate spicules radiating to the surface, with
sub-cuticular unsymmetrical cavities. The cortical spicules:

78 Introduction to Animal Morphology.

are uniform, simple, with stellules. Steletta has both simple
and anchorate spicules. The central spicules in Geodia
are grouped in long, radiating fascicles. Placospongia is
branched like a coral, with a central axis separated from the
cortex by a sarcode layer.

Order 6. Acanthospongia—including the Hexactinellz of
Schmidt ; siliceous Sponges with hooked, anchorate, triradiate,
or stellate spicules, separate or soldered into a continuous
network. The sarcode is soft, and contains little dif-
ferentiated matter. Euplectella,'the beautiful ‘‘ Venus’ flower
basket” of the Philippines, has the upper end of its tubular
cavity closed with a flinty network. Hyalonema has a long
twisted ‘‘glass rope” of spicules around the elongated
osculum (cloaca). Esperia has spindle-shaped or linear
needles, with hooks, anchors, &c., in the membrane or
sarcode; the persone in some Esperiz are polypoid and
bilaminar. Dactylocalyx is massive, with the spicules anky-
losed into a coral-like, expanded mass. Aphrocallistes is
tubular, with a net-like, continuous skeleton of siliceous
threads. Holtenia is a remarkable bearded form, dredged in
the North Atlantic. Allied to this order is the group
Lithistide, proposed by Schmidt for Sponges with a con-
tinuous skeleton, but without hex-radiate spicules.

Order 7. Potamospongia—massive or branched, often
green,* freshwater Sponges, with siliceous spicules united by
Spongiolin threads ; the ova have a coriaceous, spiculigerous
envelope. This includes the Spongillz of our rivers
(S. fluviatilis) or lakes (S. lacustris), which have smooth or
echinulated (S. echinata) spicules.

Order 8. Calcispongia—mostly littoral, smooth, white
Sponges, with calcareous, acicular, or triradiate spicules.
‘They may be single persone, with (Monosyca) or without a
mouth (Clistosyca); or colonies with one (Ccenosyca) or
many mouths (Polysyca); or a stock may have no mouth
(Cophosyca). The body wall may be solid, or pierced by
simple pores, or by regular or irregular canals. Many of
them develop sexual products, the spermatozoa being the

* Containing Chlorophyll.

Introduction to Animal Morphology. 79

flagellate nuclei of modified endodermal (?) cells. The forms
included herein are singularly plastic, easily modified by ex-
ternal conditions. The group with inconstant, simple,
dermal pores constitutes the sub-order Ascones.* ‘The series
with tortuous branched canals in the wall of the gastrzal
cavity are named Leucones, while those with regular, straight,
unbranched vessels and budding tubes are Sycones; any of
these may possess either simple or three- or four-rayed
‘spicules, or two or more kinds together, and by these Haeckel
divides them into genera. The flagellate plastides of
Leucosolenia (Ascones) have been regarded by /ames-Clark
as separate organisms grouped in a colony (see Synura).

CEA TER LL.
SUB-KINGDOM 3.—CCGELENTERATAt (Leuckart).

AQUATIC radiated persone (often in colonies) of more
than two antimeres, having a body cavity opening at
one pole by a mouth often surrounded by feelers
(tentacles). The body consists of two membranes, an
inner, cellular or endoderm, which at the mouth joins
the outer, or ectoderm. In the colonial forms, the
tubular prolongation of the body cavity of each
persona communicates with that of its neighbours in
the common stem of the colony (Ccenosarc), allowing
of community of nutrition, and the fluid, produced by
digestion in the stomach of each, circulates in this
tubular system, moved by the lining cilia. Dif-
ferentiations of the ectoderm form support-, loco-

* These are the simplest known gastrulz.
+ Diploblastica (Lankester), called so in contrast with the Ablastica
(Protozoa), and Triploblastica, including all the other Metazoa.

80 Introduction to Animal Morphology.

motory, and usually generative organs. The outer
surface is rarely ciliated in the adult, except in
Ctenophora. In the protoplasmic ectoderm exist
scattered or clustered nettle-ceils (cnide or trichocysts),.
(Fig. 9, B C), which are minute oval capsules filled
with fluid, and consisting of a fine homogeneous outer
layer, lined by a delicate membrane, which at the
apex is involuted into an axial tube, ending in a long,,
coiled, barbed thread. The slightest contact ruptures.
the outer layer, the tube becomes everted, and from its.
summit the thread suddenly uncoils and becomes.
rigid. The everted tube is armed Fig. 9.

with three or more barbs (Fig. 9, C),
A simpler form consists of a simple
sac and filament with no tube;
sometimes a second filament exists
in an oblong saccule at the barbed
end of the first thread. These are B
used in benumbing their prey by ad-
hesion, penetration, and possibly by

some virus; but each cell can only

A. Planula,
act once. In development, they first 8° a

appear as clear particles, which soon C- Fpeaal prot deal aan
assume a double contour (and sometimes exhibit
amceboid motions); then the spiral thread appears
within, and the cell becomes superficial and ready to:
act. They are most numerous on the tentacles, and
often regularly arranged.

Sexual reproduction occurs in every species, and.
the term individual is applied to the total product of a.
single impregnated ovum: when this consists of parts.
which sustain separate existence, each part is called a.

zooid.

Introduction to Animal Morphology. 81

The group is divisible into two classes :—

CLASS 1. HyDROzoA—Saccular or tubular persone,
either single or in varying degrees of aggregation,
with no separate digestive sac, and with the repro-
ductive organs external. To each individual, whether
persona or colony, the name Hydrosoma is given.
The following sub-classes are here included :—

Sub-class 1. Hydroida—locomotion never by meri-
dional rows of cilia; generative elements discharging
themselves externally. The zooids serving for the
nutrition of the hydrosoma are never joined in free
swimming colonies with the reproductive zooids.

Four orders are included :—

1. Eleutheroblastea (A //man).—Hydras are separate
persone attached at will by an aboral disc, and con-
sisting of a tubular digestive cavity with no anus. The
4-10* tubular tentacles are prolongations of both endo-
and ecto-derm (Fig. 10 T), and varyin
length from }” to 1o times the length
of the body (which is ‘08” — -4”, or even
more). The ectoderm consists of large
nucleated cells, from whose bases fila-
mentary processes are continued in-
wards (Fig. 11, A). /decnenberg re-
gards these as nerve cells, and the pro-
cesses as muscular, thus forming the SSS
simplest differentiated neuro-muscular #¥,"3 aurantiaca-

T, tentacles ; 0, ovary
apparatus. Between these cells are ‘4,jpermsenous Pa
smaller irregular interstitial cells, not forming a
special layer, but surrounding the bases of the first
series, and containing the nettle cells, which often

appear sunk in the sides of the larger ectodermal cells.

* Rarely twelve or more.
G

82 Introduction to Animal Morphology.

Fine bristles (palpocils) project from the walls of some
_of the surface interstitial cells (seen on the thread cell
in Fig. 9, B; protoplastic processes of 7. S. Wright).
The endoderm cells are large, unilaminar, vacuolated,
often flagellate, often with no distinct cell wall. The
thread-like processes of the ectoderm cells, united by
a copious intercellular substance, form an intermediate
layer of vertical fibres* (described by Kollzker).
Ameeboid cells wander through both layers. The
tentacles are not transversely septate, and their ecto-
derm is rich in interstitial tissue, and contains both
kinds of thread-cells and palpocils.
Reproduction may be by Fig. 11.

fission, and if artificially cut _» A B
up, all the lost parts are x |
rapidly reproduced, and buds
may spring from any part
except the tentacles (Fig. 11,
D), most frequently from
the proximal end, or that
nearest the aboral disc. Each
bud contains a prolongation
of the endoderm and ectoderm . D
and a pouch of the body
cavity ; a mouth and one or

D. Hydra viridis, showing the for-
two nodular tentacles develop mation of buds.
at the distal end; the latter expand and increase in
number; the body cavity at the base of the bud
nartows, closes, and the bud falls off (in from three
days to six months). Detachment may occur before
the aboral cavity is perfectly closed, leaving the

A. Neuro-muscular cell.
B. Spermatozoon of Hydra viridis.
C. Ovum of H. viridis.

* These fibres are more highly refracting when treated with acetic acid
than the granular contents of the basis of the ectoderm cells.

Introduction to Animal Morphology. 83

minute anal opening described by Corda, Leydig, and
flancock. A second race of buds may form on the
growing bud before its detachment: indeed, as many
as five such progenies have been found united. This
process is frequent in summer.

Sexual reproduction is commonest in autumn, but
is not confined to any season. The spermigenous
organs form near the base of the tentacles (Fig. 10, sf.)
At one spot, the interstitial ectodermal cells enlarge,
and become polyhedral, and with them are found
amceboid cells. The neighbouring neuro-muscular
cells thin out, and form a coating over this now conical
or wart-like growth. The nuclei in the altered cells
disappear, and their contents become granular and
confluent. Then from the amceboid cells, oval re-
fracting spermatozoa (Fig. 11, B) form, and become
flagellate, and escape into the surrounding water
through an apical opening in the papilla.

The ova also develop in the interstitial tissue, near the
proximal or aboral end (Fig. 10, 0). There, in one or two
separate projections of the ectoderm, cells increase, and free
nuclei appear in the surrounding intercellular protoplasm.
In each projection, one central, amoeboid, vacuolated cell con-
taining granules and vitellin particles increases in size, and a
nucleus or germinal vesicle appears within it, around a
germinal spot (Fig. 11, C). Green pigment grains, and
sharply-contoured, round: masses (pseudo-cells), like the yelk
granules of a spongilla-egg, develop within thiscell. After these
form, the germinal vesicle becomes indistinct. They are fer-
tilized 7m sztu, the head of the spermatozo6n touching the outer
wall of the egg; whereupon. the yelk segments, each part
exhibiting amoeboid motions, and the egg becomes a morula,
whose inner cells are polygonal and the outer cylindrical.
The outer surface of the egg is at first smooth, then becomes
rough with irregular projections, and dark. The cylinder cells

G2

Introduction to Animal Morphology.

exhibit a double contour, due to the formation of an outer,
thin, chitinous(?) cuticle, between which and the central
mass a fluid layer is interposed. The ovum now is set free,
and the central yelk cells fuse into a plasmodium, which
divides into a clear ectoderm and a darker endoderm. The
horny cuticle splits, and is shed; hence the adult has no
cuticle. The germ becomes ellipsoidal, clear at one pole,
where by gradual thinning it develops a mouth, surrounded by
4-7 tubercles, which become tentacles, into which the endo-
derm is prolonged. The embryo has thus no free ciliated
stage.

Hydre thus produced never develop sex-organs, but
multiply by gemmation or fission for several generations be-
fore new sex-products are formed. We have thus a perfect
alternation of generations.

To this group belong the voracious freshwater Hydra
viridis (Fig. 11, D), aurantiaca (Fig. 10), grisea, &c., differing
in colour, size, pit lengths of tentacles.

Protohydra pamela (Greef)—a marine, non- -tentaculated
form, found in the diatom slime of the Ostend oyster park,
also belongs here; it has no distinct cell-membrane, nor
pigment in its ectoderm, but large cnide and a cuticle.
Neither sexual nor gemmative reproduction have been found,
but it multiplies freely by fission. It may be a larval form.

CHAPTER XIII.
HYDROZOA.

ORDER 2. Gymnoblastea (A//man).—In the last
group, continuous aggregation is a temporary con-
dition, but in the other orders the colony is the
commonest state of existence. Each colony has a
root (hydrorhiza) attached to some sub-aquatic body ;
from this arises a simple or branched tubular,
ccenosarcal stem (hydrocaulus). These two parts

Introduction to Animal Morphology. 85

make up the hydrophyton. The wall of the tubular
somatic cavity is composed of endo- and ecto-derm,
covered by a chitinous, unorganized sheath (periderm),
a differentiation or secretion from the ectoderm. In
Hydra, the zooids which produce the sexual products
are similar to those which do not; but in these orders
the nutritive and generative zooids are dissimilar.
All the nutritive zooids of a colony, taken together,
constitute the ¢vophosome; all the generative, the
gonosome ; either set may be homomorphic (similar) or
heteromorphic (dissimilar). Each zooid of the tropho-
some is somewhat like a Hydra, and is called a
hydranth (or polypite),* the distal end of which is
prolonged into a proboscis (hypostome), at whose ex-
tremity is the mouth, and around whose base are the
tentacles, often irregularly scattered, and varying from
2 (Lar) to 100 or more. The cavities of the tentacles
are either divided by horizontal partitions (septate), or
else obliterated (Coryne). The endoderm and ecto-
derm are separated by a thin, hyaline, supporting
membrane, lying on the endodermal side of.the
muscular layer (Schulze). The endoderm is ciliated in
many forms.

If the hydrocaulus be cut in a living colony, the
distal end of the proximal segment develops a
hydranth, while the cut end of the distal portion only
forms an extension of the ccenosarc.

The gonosome is more variable than the tropho-
some, and consists of modified hydranths budding
from the ccenosarc ; these may be sessile closed sacs
(sporosacs), consisting of a process of the ectoderm and

* Hydranths of some Tubularize become free, but only as a first stage
of decadence; they never undergo any after metamorphoses.

86 Introduction to Animal Morphology.

endoderm, with a pouch of the somatic cavity con-
tained (Fig. 12, A), and are said to be adelocodonic
(a, Ondoe, kwdwv). The wall or perigonium of the sac
consists of three layers derived from the ectoderm

Fig. 12.

A. Sporosac. B. Sporosac with incipient radial canals. C. Phanerocodonic
gonophore; s., spadix. D. Gonocheme, section; 7.c., radial canal; ™. mouth; w.,
velum; #, tentacle; s., sexual products. E. Carmarina hastata; #., mouth, with
tongue-like process; d., disk; ¢., circular canal; s., sporosacs; ¢.7., cartilaginous
Ting; v., velum.

(ecto-, meso-, and endo-theca), having in the centre a
tubular, cylindroidal stalk of the endoderm (spadix,
Fig. 12, C, s.), on whose wall, under the endotheca,
the sexual products form. From the somatic cavity
in the base of the spadix, four radial canals lined by
endoderm may traverse the mesotheca (homologous
with that part of the tentacles of a hydranth included

in the base of the hypostome, seen in section in Fig.

Introduction to Animal Morphology. 87

12,B &C). Many zooids undergo further change, and
losing the ectotheca, the free pole of the mesotheca
opens, forming a bell, with the spadix (now called
manubrium) enclosed as.a clapper (Fig. 12, D), and its
cavity, opening at its extremity, forms a mouth (Fig.
12, D, m.) communicating with the stomach or cavity
of the manubrium, and through it with the radial
canals (Fig. 12, D, 7.c.), whose peripheric ends become
united by a circular canal (E,c.) around the margin of
the mouth of the bell or codonostome. These tubes
are called the gastro-vascular canals.* From the free
edge of the codonostome, tentacles project (¢.), and an
in-growing muscular horizontal velwm (v.) narrows the
aperture. This form of zooid is called phanerocodonic,
and it usually loses the pedicle joining it to the
ccenosarc, becomes free, and is called a planoblast or
medusa.t Ova or spermatozoa may develop under
the ectodermal layer of its manubrium (Fig. 12, D, s.),
and it is then called a gonocheme; but often the
medusa produces along its radial canals, within the
cavity of the bell, a second race of zooids, usually
sporosacs (Fig. 12, E, s.),in which the sexual products
are formed. Such medusz are called blastochemes,
and the second race are either saccular, or, as in
Tima, a long wavy tube along the entire radial canal.
To any of the zooids in which ova or spermatozoa are
formed, the name gonophore has been given. A
columnar zooid supporting gonophores along its side
is named a blastostyle. The manubrium of a free
medusa is homologous with the hypostome of the

* A circular lip below the stomach can, by contracting, temporarily
shut off these canals from the stomach.

t Most of the small floating umbrella-like Jelly fishes, abundant in our
seas, usually from the size of a pea to that of a walnut, belong to this class.

88 Introduction to Animal Morphology.

hydranth, and may be clavate, cylindrical, or long and
ribbon-like (Sarsia strangulata).

No form exhibits adelo- or phanero-codonic gono-
phores indifferently, but each has its specific gono-
phore. The umbrella-like bell, in free forms, is con-
tractile (except in Clavatella, &c.), and by it the zooid
swims; hence it is called a nectocalyx. Dicoryne,
however, moves by cilia, not by a contractile bell.
The tissues making up this bell are:—1st. A layer of
tesselated epithelium on its surface. 2nd. Loose
connective tissue, either homogeneous or with fine
fibres, containing neither collagen nor mucin, but
sometimes with stellate corpuscles. When homo-
geneous, it is described as being epidermal in origin,
and the fibres, &c., are considered ingrowths from the
deeper connective layer. This makes the chief mass
of the bell, but so little solid matter exists in these
masses of “‘ animated sea water,” that each 100 grains,
when dried, usually contains 2.50 grains of residuum,
and from ro kilogrammes of an allied form, only 30
grammes of solid matter were extracted. 3rd. Smooth,
rarely monilated muscle fibres (?) in the velum and
lining of the bell-cavity. In a few forms the sub-
muscular connective tissue develops into a cartilage-
like (Fig. 12, E, c.7.) ring, below the circular canal,
parallel to the codonostome, and receiving the nerve
ring; or radial rib-like cartilage rods, equalling in
number the lithocysts, may lie in the outer surface of the
bell (some Geryonide), or as a rod-like axis in the stiff
tentacles (some Trachynemide, &c.) The gastro-
vascular canals may be below, or imbedded in, the
connective tissue of the bell.

The marginal tentacles are usually simple, often

Introduction to Animal Morphology. 89

long, tubular, or septate and contractile. In their
bulbous bases, imbedded in the ectoderm of the gono-
chemes, are masses of black or red, homogeneous,
pigment spherules (oce//z), often with a clear, reflecting
body immersed, and sometimes with a nerve ganglion
at their bases. Around the margin of the bell in.
blastochemes, in the mid-spaces between the tentacles,
or sometimes irregularly distributed, are /zthocysts, or
sacculi, containing one or more, rounded, concentrically
laminated masses of calcium carbonate (or phosphate,
Flacckel), rarely crystals, as in Cunina. These bodies.
are longitudinally striated, and sometimes (Geryonide)
a ganglion lies under-each sac, and fine hairs go to
the concretion. In Tiaropsis, a pigment spot exists
at the base of the lithocyst, but otherwise ocelli and
lithocysts do not co-exist. Some lithocysts are
pedunculated, and a canal from the marginal vessel
passes into each, ending in an ampulla, below which
is the vesicle containing the otolith. Ocelli rarely
occur in blastochemes (except in Thaumantias, &c.);
nor lithocysts in gonochemes (except in Goodsirea) ;
Melicertum (a blastocheme) has neither.

Fine bristles (touch-organs) are found in the epi-
thelium over the ganglionic swellings at the bases of
the lithocysts in Cunina, and over the tentacles in
Rhopalonema. The nerve system may consist of a
ring connecting these ganglia, and true nerve cells
have been found in the latter. Radial and inter-
radial nerves may pass from these; but in general
this system is obscure, scarcely detectible.

The relation between the gonophore and the
hydranth has been proved teratologically. Agasszz
saw the sporosac of Rhizogeton, having discharged its

90 Introduction to Animal Morphology.

contents, elongating, developing tentacles, and be-
coming a hydranth. A//man saw the same in Cordy-
lophora. Blastostyles may pass into hydranths, as in
Hydractinia polyclinia, where the blastostyle has a
mouth, but no tentacles; in some Eudendria, the
young blastostyle has tentacles, but loses them when
the gonophores are developed.

The ova and spermatozoa are produced usually in
different gonophores ; the former by modifications of
the interstitial* endodermal, the latter of the ectoderm
cells (except in some Geryonide). The ova are im-
pregnated within their sacs, and undergo segmentation
as usual, and the embryo resulting is either cylindrical,
ciliated, and infusorium-like (planula, Fig. 9, A), or
polypoid, free, non-ciliated (actinula). The planula
becomes flask-shaped, its wide end forming a hydro-
rhiza; the narrow end rises into a hydrocaulus, and
finally develops a hydranth. The actinula swims fora
few days by the contraction of its body, then settles
down, forms a mouth, and becomes a_ hydranth.
Sometimes a planula develops directly into a medusa
with no hydroid trophosome (Cunina, J/‘Crady ;
Carmarina, Aigineta, and A‘ginopsis, JZetschntkof ;
Lizzia, Claparéde).

The alternation of generations may be binary
(hydranth, gonophore, + hydranth, gonophore, &c.),
or ternary (hydranth, blastostyle, gonophore, + h., b., g.,
&c.), or quaternary (hydranth, blastostyle, blastocheme,
gonocheme, + h.,b., b., g., &c.) ; or even more complex
if the hydranths be heteromorphic. The succession
is, as a rule, constant in each species; and no subse-

* The testis in Hydractinia and Tubularia is certainly ectodermal
(Kleinenberg and £. Van Beneden), while the eggs are endodermal.

Introduction to Animal Morphology. gI

‘quent non-sexual factor ever develops its antecedent.
In some cases, planoblasts have been observed to pro-
duce heteromorphic buds unlike their parents ; thus
ffaeckel describes Cunine as produced by budding
from meduse of the family Geryonide. To this
process, which is not yet understood, the name
Alleogenesis has been given. .

Medusze can be multiplied by artificial division;
‘even when cut into a hundred pieces, each became a
perfect medusa (//aecke/).

Gymnoblastea are divided into the following families :*—

1. Clavide—hydrocaulus rudimental or developed ; hy-
dranths club-like, with scattered filiform tentacles ; sporosacs
fixed, sessile, or shortly stalked. In Tubiclava, the hydrocaulus
is developed. Cordylophora, the only freshwater form, has
fusiform polypites at the extremities of a branched ccenosarc,
and sporosacs on the hydrocaulus, each with a branched
spadix. 2. Turride—hydrocaulus and hydranths as last ;
planoblasts,t with simple radiating canals, and simple
‘marginal tentacles. In Campaniclava, the hydrocaulus is
undeveloped, and the planoblast is bitentaculate. In Turris
the nectocalyx has striped muscular fibres, and each marginal
tentacle has a bulbous ocellated base. 3. Corynidze—
hydranths with scattered, often spirally arranged, capitate
tentacles, and fixed sporosacs; hydrocaulus developed, ex.
Coryne. 4. Syncorynide—hydranths with scattered, or
partly scattered, partly verticillate, capitate tentacles, with
gonochemes, formerly known as Sarsia, with a simple mouth,
four radial canals, and marginal tentacles, ex. Syncoryne.
‘5s. Dicorynide—hydrocaulus invested with a perisarc;
hydranths with verticillate filiform tentacles; planoblasts
natatory, ciliated, with two simple basal tentacles, ex. Dicoryne.

* Classification is a matter of some difficulty, as similar gonosomes may
be associated with dissimilar trophosomes (Isogonism) ; or dissimilar gono-
-somes may spring from similar trophosomes (Heterogonism).

t+ Carus calls planoblastic medusoids, parydrodea.

92 Introduction to Animal Morphology.

6. Bimeride—hydrocaulus with a perisarc, or rudimental >
hydranths without an abruptly differentiated hypostome ;.
tentacles filiform, in a whorl around the base of the mouth ;.
sporosacs fixed, ex. Bimeria. 7. Bougainvillide——hydro-
caulus with a perisarc; hydranths as last; tentacles filiform

in a single circlet around the base of the hypostome; gono--
phores phanerocodonic, with four radial canals; marginal
tentacles simple or clustered, ex. Bougainvillea. 8. Euden-
dridze—hydrocaulus as last; hydranths with an abruptly dif-
ferentiated peristome, and one circlet of simple verticillate
tentacles; sporosacs fixed, ex. Eudendrium. 9. Hydractinide—
hydrophyton forming a continuous expansion, its deeper
part being a series of freely communicating tubes of coenosarc,
covered by a chitinous perisarc ; hydranths, with filiform ver-
ticillate tentacles ; sporosacs fixed. In the female sporosacs,
there is a rudimental ectodermal male invagination, and in
the male sporosacs, the endoderm forms rudimental and
aborted ova, ex. Hydractinia. 10. Podocorynide—hydro-
phyton an adherent expansion of adnate, inosculating tubes,
with a chitinous perisarc; gonophores phanerocodonic, ex.
Podocoryne. 11. Cladonemide—hydrocaulus developed, in-
vested by a perisarc ; hydranths with two kinds of tentacles,
filiform and capitate; the phanerocodonic gonophores have
more than four radial canals, and branched marginal ten-
tacles, ex. Cladonema. 12. Nemopsidze—hydranths with a
proximal and distal circlet of filiform tentacles; planoblasts
often blastochemes, with four canals, and clustered dissimilar
marginal tentacles, ex. Nemopsis. 13. Pennariada—hydro-
caulus developed ornone ; hydranths with filiform and capitate
tentacles ; planoblasts with four canals and 1-4 marginal ten--
tacles,ex. Pennaria. 14. Cladocorynide—hydranths with both
simple and branched capitate tentacles; gonosome unknown,,
ex. Cladocoryne. 15. Myriothelida —hydranth solitary;
hydrocaulus none; tentacles scattered, capitate; sporosacs on
processes from the body of the hydranth, ex.Arum. 16. Cla-
vatellida—hydranths with simple, verticillate, capitate ten-
tacles ; gonophores are ambulatory medusz, with undeveloped
umbrella, and branching marginal tentacles, ex. Clavatella.
17. Corymorphidae—solitary ; hydrocaulus with no perisarc ;.

Introduction to Animal Morphology. 93

hhydranth with proximal and distal rows of filiform tentacles ;
planoblasts with one or more simple marginal tentacles, ex.
Corymorpha. 18. Monocaulide—solitary, naked; hydro-
caulus with hydranths, as last, and fixed sporosacs, ex. Mono-
caulis. 19. Hybocodonide—hydranths as last; hydrocaulus
with a perisarc; planoblasts medusiform, ex. Hybocodon.
20. Tubularide—hydranths with two rows of tentacles;
hydrocaulus with a perisarc; sporosacs fixed or planoblastic
(Carus); hypostome conical. Some forms periodically shed
their hydranths, ex. Tubularia. 21. Hydrolaride—hydro-
caulus undeveloped; hydranths with two filiform tentacles
from one side of the base of the bilabiate hypostome, which
has a head-like lobe; planoblasts with six radial canals and
‘simple marginal tentacles. The trophosome of Lar is very
singular in form.

CHAPTER XIV.
HYDROZOA.

ORDER 3. Calyptoblastea (4//man).—Colonial forms,
having the periderm expanded at the base of
each hydranth into a cup or receptacle (hydrotheca) ;
sometimes with a lid or operculum. The gonophores
are at first included in a similar capsule (gonangium),
which may hold one gonophore (monomeric), or many
on a blastostyle (polymeric). Blastochemes, excep-
tional in the last order (Nemopsis), are common here
(Campanularide) ; and sometimes the gonangia are
clustered within a common receptacle (corbula). The
gonophores may discharge their contents into the sea,
or into the cavity of the gonangium, or into a sac at
the summit of this cavity, and external to it (acrocyst,

94 Introduction to Animal Morphology.

an extension of the endotheca protruded as a pouch
through the summit of the gonangium). Gonothyraea.
has, above the opercular summit of the gonangium,.
two pedicellate, spherical, medusiform gonophores.
(meconidia), with 8-20 circumoral tentacles and radial
canals.

This includes the following families :-—

1. Campanularide—with terminal, seldom stalked, oper-
culate hydrothece ; hypostome trumpet-like; blastochemes:
(Eucope, Obelia) or sporosacs (Campanularia, Clytia,
Hincksia, Laomedea). 2. Campanulinide—hydrothece ovate,
operculate ; polypites cylindrical ; hypostome small, conical ;
blastochemes(Campanulina, Calycella). 3. Leptoscyphide—
hydrothece oval; the ocellated gonochemes are known as:
Lizzia, ex. Leptoscyphus. 4. A®quoridee—hydrothecz oper-
culate, the lid of converging lanceolate segments; blasto-
chemes discoidal, with (Mesonema, &c.) or without oral!
tentacles (/Equorea), and with many radial canals. Stomo-
brachium sometimes undergoes fission, and has fine retiform
canals in the muscular lining of the sub-umbrella ( Wrigh?)..
5. Lafoeide—hydrothece tubular ; polypites cylindrical ; pro-
boscis conical, ex. Lafoea. 6. Trachydride—hydrothecz
rudimental; polypites cylindrical; proboscis extensile, conical.
7. Thaumantiade—hydrothece non-operculate ; hypostome
trumpet-like ; blastochemes, with shallow stomachs ; tentacles.
often numerous (200 in Tiaropsis), or dissimilar. 8. Cop-
piniade—hydrothece united by an encrusting cellular mass.
g. Lineolaride—hydrothece sessile, tubular, with oviform,
sessile gonangia. +10. Sertulariadze—sea-firs; hydrothecz:
sessile, inserted on the stems and branches of the hydro-
caulus ; polypites retractile, with one circlet of filiform ten-
tacles; sporosacs fixed. 11. Haleciide—hydrothece none,
or rudimental, biserial, sub-sessile, joined to a lateral process:
from the stem; polypites not, or partly, retractile; blasto-
styles, bearing the sex-products (not in sporosacs), develop.
within modified single internodes of the stem (pseudogonan-
gia), each of which bears a hydranth (Ad/man), ex. Halecium.
12. Plumularide—hydrocaulus bearing, besides the ordinary

Introduction to Animal Morphology. 95

sessile unilateral hydrotheca, scattered degraded hydranths,
consisting of cup-like cavities of the perisarc filled with pro-
toplasm, in which nettle-cells are embedded, forming nettle-
batteries or nematophores, for the protection of the colony ;
gonozooids fixed,* simple, axillary, ex. Plumularia.

Order 4. Monopsea (A //man)—Possibly only a pro-
visional order, including those forms with no known
trophosome separate from blastochemes, and in which
the medusz develop directly from the egg.

Four families are included :—

1. Geryonide—manubrium elongated ; lithocysts inter-
tentacular; sex-organs in flat masses along the radial canals,
which may be four (Liriopinze) or six (Geryoninz); in the
former there are no centripetal canals, often a tongue-like
process, and eight (Xanthea) or four tentacles (Liriope) ; or
no tongue-like process, and eight (Glossoconus) or four ten-
tacles (Glossocodon). In the latter there are many blind
centripetal canals, with (Carmarina, Fig. 12, E), or without a
central tongue-like process (Geryonia), except in Leuckartia,
where these canals are absent. 2. A’ ginidz—disc with
tentacles springing above the margin ; radial canals, pouch-
like, wide 4-32; lithocysts marginal; Cunina has simple
tentacles, each with a conical cartilage at the base, springing
opposite the stomach pouches (in A‘gina they alternate), and
a broad simple mouth. A‘ginopsis, which has oral tentacles,
has been traced from its egg with no trophosome stage.
Agassiz makes a separate family Brandtidze for allied, but im-
perfectly known forms. 3. Trachynemide—blastochemes.
with no long manubrium, and stiff tentacles ; disc bell-shaped
(Trachynema), or flat (Rhopalonema). 4. Octorchida—with
a solid quadrangular manubrium, having a radial canal at each
angle, and eight genital masses, four in the manubrium and
four in the sub-umbrella, ex. Octorchis.

* The protoplasm of the nematophore has been seen to protrude pseu-
dopodia (Ad/man). These processes are sufficiently constant to be used in
classifying the Plumulariz (Avrchenpauer). Antennaria antennula has no
nettle-cells.

96 Introduction to Animal Morphology.

Order 5. Milleporida—trophosome colonial, en-
crusting submerged materials in tropical and sub-
tropical seas ; massive or lamellar, often antler-like,
branching, calcified; tentacles four; ccenenchyma
abundant ; tabule transverse. Only two genera sur-
vive: Millepora, with an irregularly tubular structure ;
and Heliopora, with tubular ceenenchyma and twelve
regular septa, forming coral-like masses. Possibly
the extinct Rugosa and Favositide should be included
here (Agassiz). The reproductive zooids of all are
unknown.

CHAPTER XV.
HYDROZOA.

SUB-CLASS 2. Siphonophora (L£schscholiz) — Free,
oceanic, often bilateral or asymmetrical, with a
muscle-bearing, flexible czenosarc, whose proximal
end is dilated, containing an enlargement of the
somatic cavity, often acting asa hydrostatic apparatus,
and usually bears barren, medusiform zooids, spe-
cialized into swimming bells (nectocalyces). The ova
are fertilized directly, and the germinal vesicle does
not disappear in the early stages of development.
The gonophores are medusiform, borne on the
peduncles of the polypites. About 120 species exist,
divided into two orders :—

Order 1. Calycophoride (Leuckar¢f)—having the
hydrosoma propelled by nectocalyces, each of which
resembles the bell of a planoblastic medusa without a

——

Introduction to Animal Morphology. 97

manubrium, but retaining its veil. The cavity of the
bell (nectosac) is lined by a muscular lamina, and
the pedicle of the nectocalyx has in it a process of
the body cavity, branching into four or eight necto-
calycine canals (like the gastro-vascular canals of a
gonophore). Between the proximal nectocalyces is a
groove (hydreecium) for the proximal end of the
ccenosarc, within which it can be wholly or partially
retracted. The ccenosarc is flexible, unbranched, con-
tractile, filiform, never invested by a periderm. The
proximal end of the somatic cavity dilates in front of
the nectocalyces into a variously shaped cavity
(somatocyst), ciliated within, containing large, re-
fracting globules, often air bubbles, and a vacuolated
endoderm, often nearly closing the cavity. Each
polypite has a narrow peduncle (proximal part), and.
consists of a wide, gastric portion, ciliated and villous
within, at whose opening into the peduncle there is
an endodermal fold (pyloric valve). The distal end of
each polypite is the hypostome. Coloured hepatic
cells may line part of the gastric wall (Praya), and
cnide exist among the villi of the endoderm. The
single so-called tentacle of each polypite arises from
the peduncle, and is a modified zooid consisting of a
slender basal “ pedicle,”’ a middle thick part or “ sac-
culus,” the equivalent of the manubrium, armed with
cnide, and a terminal, often coiled, “filament.” The
pedicle may expand where it joins the sacculus, and
when this dilatation encloses the base of the second
part it is called the involucre, and is a modified
medusa bell. A muscular angle-band (Lewckart),
folded in zigzags, lies on the hinder wall of the sac-
culus; its proximal end passes into the pedicle, its
distal into the flament. The peduncle of the polypite
H

98 Introduction to Animal Morphology.

often bears a protective leaf-like appendage (hydro-
phyllium), made of a layer of ectoderm, a process of
endoderm, and a pouch of the somatic cavity (phyllo-
cyst). These may be thin (Diphyes), or thick (Abyla),
on the ccenosarc, or on the peduncle of the polypite.
The gonophores bud from the peduncle, and may be-
come planoblastic ; sometimes each carries with ita
segment of the ccenosarc (which breaks midway be-
tween each group), supporting a polypite, tentacle,
and hydrophyllium. Such detached parts are called
Diphyozodids, and they move by the contraction of
the gonocalyx of the medusiform gonophore. The
coenosarc grows at the proximal end, so that the oldest
polypites are farthest from the somatocyst.

There are four families :—

1. Diphyide—with two polygonal nectocalyces, the hydroe-
cium of the proximal being complete; hydrophyllia large. In
Diphyes the proximal nectocalyx is mitrate, pentagonal in trans-
verse section, and larger than the distal ; the hydrophyllia are
spathiform, smooth ; the diphyozodids are known as Aglaisma,
Eudoxia, &c. In Abyla, the proximal nectocalyx is small,
polyhedral, the distal large and mitrate ; the hydrophyllia are
thick and facetted; its detached parts are called Diplophysa,
Amphiroa, &c. 2. Sphaeronectidaee—nectocalyx single, sphe-
roidal, with a complete hydreecium; hydrophyllia none; tenta-
cle attached to the peduncle, ex. Sphaeronectes. 3. Prayidae—
nectocalyces two, parallel, with incomplete or groove-like
hydreecia ; phyllocyst prolonged into four ccecal processes in
the thick, reniform, gelatinous hydrophyllia ; male and female
medusoids attached to the same ccenosarc, ex. Praya.
4. Hippopodidee—nectocalyces many, horse-shoe shaped (Hip-
popodium), or many-angled (Vogtia), with incomplete hydroe-
cium, and no hydrophyllia.

Order 2. Physophoride (£schschol/z).—Siphono-
phora, with the proximal end of the somatic cavity

Introduction to Animal Morphology. 99

expanded into a variously shaped pneumatophore,
containing at its apex a chitinous air-sac (pneumato-
cyst), which does not communicate with the cavity of
the pneumatophore, or with the somatic cavity, but
opens externally by a pore or stigma (except in
Physophora, Forskalia, Agalma, Athorybia, and
Halistemma), and is held in its place by a reflection
of the endoderm. Its shape may be spheroidal
(Athorybia), oval (Physophora), cylindrical and small
(Agalma), &c. The hydrophyllia and tentacles are as
in Calycophoride ; and there are also, on the ccenosarc,
hydrocysts, polypoid, protective, or prehensile processes
of endo- and ectoderm, each with one long, filiform
tentacle, closed distally, and profusely armed with
trichocysts. The tentacles may be simple cecal
tubes with vacuolated endoderm (Velella), or branchea
at the end (Porpita). Each may be at the base ofa
polypite (Apolemia), or projecting from the ccenosarc
independently of the polypites, each with a basal sac
(Physalia). In Physophora, the tentacle has a large,
spheroidal involucre enclosing the sacculus. From
the air-sac to the wall of the pneumatophore, septiform
processes pass in Forskalia and Agalma. In Velella,
slender, jointed, air-holding processes project from
the pneumatocyst into the wall of the hepatic organ
(pneumatic filaments). In Rhizophysa, long, branched,
cellular processes, covered by ciliated endoderm, pro-
ject from the wall of the pneumatocyst into the cavity
of the pneumatophore ; perhaps like the hepatic organ
of Velella.

The medusiform buds form on blastostyles, and are
often free; males (androphores) and females (gyno-
phores) may co-exist, or be separate. The appendages

on the coenosarc are usually unilateral.
Hi

100 Introduction to Animal Morphology.

There are seven families, viz. :—

1. Apolemiade—possessing nectocalyces; hydrophyllia,
with the other organs, arranged in groups at intervals along
the filiform ccenosarc; pneumatocyst small; tentacles with
no lateral branches; gonophore, free, ex. Apolemia. 2. Ste-
phanomiade—having nectocalyces; hydrophyllia, with the
other organs, in a continuous series on the filiform ccenosarc ;
tentacles with lateral branches ending in sacculi; pneumato-
cyst small; the sacculi may have no involucre, and a single
filament with biserial (Halistemma) or multiserial (Forskalia),
nectocalyces, and (especially in the former) a complex mus-
cular apparatus in the tentacles, or the lateral branches of the
tentacles may be involucrate with one (Stephanomia) or two
filaments, with a pouch-like middle lobe between; in this.
case, the ccenosarc is sometimes highly contractile, with leaf-
like thin hydrophyllia, and polypites dispersed spirally on the
coenosarc. Stinging filaments surround the stem on all sides
(Agalmopsis) ; or the stem may be rigid, and not very con-
tractile, with thick wedge-like hydrophyllia one over another
(Agalma). In Crystallodes, the ccenosarc is rigid, and the
polypites simply arranged on its ventral side, the tentacles
being between the hydrophyllia. 3. Physophorida—necto-
calyces in a double row (2-5 pairs), each channeled in-
ternally to fit the coenosarc, and with four radial and a circular
uniting canal. There is no pneumatocystic stigma, nor hydro-
phyllium, but an apical pigment spot in the pneumatophore,
and a series of proximal hydrocysts, with or without filiform
tentacles, ex. Physophora, Stephanospira. 4. Athorybiadee—
nectocalyces, none ; the globular cavity of the ccenosarc nearly
filled with the large pneumatocyst; hydrophyllia on the
proximal side of the other appendages ; tentacular branches
with involucral sacculi; two filaments, and a median fluid-
holding lobe, ex. Athorybia. 5. Rhizophysidae—ccenosarc
filiform; nectocalyces and hydrophyllia none; pneumatocyst
small, in a pear-shaped pneumatophore, and with a red patch
at its stigma, through which the sac can expel the contained
air; the tentacles have lateral branches, but no sacculi nor
muscle-bands, ex. Rhizophysa. 6. Physaliade—hydrosoma
pear-shaped, with no hydrophyllia nor nectocalyces ; coenosare

Introduction to Animal Morphology. 101

jrregular, thick, with a crest formed of ectoderm on the upper
‘surface ; having a horizontal, long air-sac between its layers,
divided alternately by smaller and larger transverse muscular
septa; the long tentacles have basal sacs, but no lateral
branches, and at intervals along their outer wall there are
kidney-shaped enlargements, armed with cnidz and an in-
ternal muscle-band, ex. Physalia, the Portuguese man-of-
war. 7. Vellelide—with no hydrophyllia nor nectocalyces ;
short submarginal tentacles; a single central polypite below
the flattened, strong, chitinous pneumatocyst, which is divided
into chambers by concentric partitions, and occupies the
whole ccenosarc ; the pneumatic cells of the air-sac commu-
nicate with each other by openings in the septa, two into
each chamber; there are also external stigmata, six in the
vertical plate and about seven in the horizontal; the soft
ectoderm is permeated by ciliated canals; the hepatic organ
is made up of deep brown cells, lining the branchings of the
gastrovascular canals, and opening radially (Porpita), or in
two series into the stomach (Velella). The genera are :—
Velella—oblong, with a solid vertical crest (with oblique
‘surface markings) crossing the disc diagonally ; reproductive
zooids planoblastic (Chrysomitra). Porpita—discoidal, with
branched tentacles, and no crest; it has a spongy, guanin-
containing body below the pneumatocyst, possibly an ex-
<cretory organ.

Order 3. Graptolitide.—Palaeozoic Hydrozoa with a free,
‘compound, often branched, hydrosoma, and uni- or bilateral
hydrothece containing nematophores, which were probably
nutritive ; some had a horny, basal pneumatophore ; other
parts are unknown.

Sub-class 3. Calycozoa (Leuckart, Podactinaria,
M. Edwards)—stalked, oceanic forms, capable of
attachment by an aboral disc (Fig. 13, /). The gene-
rative elements lie in symmetrical, band-like pro-
jections of the inner surface of the somatic cavity, and
are discharged into it.

There is one order and family, Lucernaridz, which

102 Introduction to Animal Morphology.

has a body like an inverted bell, with a medial, square
mouth on a projecting proboscis or hypostome. This
bell is fixed on a pillar, and can detach Fig. 13.

its aboral disc, and creep by its suckers, {
or swim like a Discophoran. The
body cavity is four-chambered. At
the margins of the disc are often litho-
cysts and clusters of tentacles, either
suctorial, adhesive, or similar to those
of Meduse, placed on the angles

(Lucernaria, Fig. 13), or in the intervals / dee of ace

ody; 2, mouth; x,

between the angles (Depastrum) of the cluster of suctorial ten-
es; 7, generative
octagonal disc; or the margin may be «lements.
entire, with the tentacles in several (1-3) rows (Car-
duella, Calycinaria). There are wide radial canals.
passing from the marginal suckers to the stomach.
The reproductive elements arise in these tubes, ex-
tending to the edge in Depastrum and Lucernaria,
not in Carduella. Development is direct. They live
in the N. Atlantic Ocean.

CHAPTER AVI.
HYDROZOA.

SUB-CLASS 4. Discophora (Z'schscholtz).—Free, oceanic
forms, with a basal wmérella, which is not a mesothecal
expansion of the base of a manubrium, and has no
velum, but is traversed by not fewer than eight
branching, anastomosing canals, and bears sense-
organs in marginal notches (Fig. 14). Reproductive
organs in symmetrical pouch-like dilatations of the
body cavity.

Introduction to Animal Morphology. 103

Two orders are included herein :—

1. Rhizostomida—Reproductive organs in free
zooids, with no marginal tentacles nor Fig. 14.
central mouth, but with a tree-like
mass depending from the umbrella,
bearing many, mouth-like openings,
formed by the irregular gaps produced
by the contact and adhesion of com-
plexly folded oral lobes. Ne

inthis order, and the’ next, the y,,_,:,atbody of Chaby-

dza marsupialis, show-

young embryo on emission from the ing'itsstalk cavity, two
egg is a planula (Fig. 15, 4), which, snd onc lithocyst below.
after a short locomotive period, attaches itself by its
narrow end to some solid body, and forms a mouth
and stomach by invagination at its distal end, around
which four rudi- Fig. 15.

mental tentacles
develop (15, ¢);
these elongate,and -
others form in their =
intervals. This
hydra-like | form
lengthens, its
mouth extends into

a manubrium-like

_ 4, Aurclia aur ta; 4, development of Aurelia aurita,
process, and lon planula; c, tiydra tuba; @, Hydra tuba budding;

: : e, Scyphistom a; /, Strobila; g, Ephyra; 7, tentacles;
gitudinal canals m. 6. marginal bodies; c. c. circular canal.

sketch from the mouth to the wall of the body.

This trophosome having lived for a variable time
(c.d.), the elongated wall of the hydra tuba (as it is
called) becomes marked by a series of transverse
grooves (e) around its circumference, which deepen,
dividing the tube into a series of superposed discs, like

104 Introduction to Animal Morphology.

a pile of saucers. In this “scyphistoma” stage, the
segments become more and more separable, each
saucer becoming lobate round its margin, and then
the column is called a strobila (/); finally, each
separates as a free swimming disc or ephyra(g), which
by degrees assumes its adult form, swims by the contrac-
tions of its umbrella, and develops ovaand spermatozoa
in its genital pouches. The young free zooids of Rhizos-
tomidz have a single central mouth (Lrandz), but as the
oral lobes increase in the complexity of their folds, and
as these folds irregularly cohere, they produce the irre-
gular polystomous, oral lobes, characteristic of the adult
(stomatodendra). A degree of bilateral symmetry
may be noticed in some Rhizostomide, and clavate
tentacles are scattered upon the oral lobes. The
bases of the stomatodendra unite into a syzdendrium,
attached by four stout processes or dendrostyles to the
under surface of the umbrella, between which are the
genital pouches.

The order Rhizostomida includes six families :—

1. Rhizostomide—with four genital pouches, opening by as
many sub-genital pores; eyeclusters eight, four in the meri-
dians of the arm-roots (per-radial), and four inter-radial ;
stomatodendra much curled, leaf like, forming sucking
combs, ex. Rhizostoma, Mastigias, &c. 2. Leptobrachida—
with four genital pouches, and four sub-genital pores ; single,
thin, unbranched stomatodendra, without tentacles, with one
tuft of border-plaits and suckers, ex. Leptobrachia. 3. Cas-
siopeiide—with eight genital pouches, and sub-genital pores;
eight ocelli; no tentacles; arms forming an eight-rayed
rosette, of dendritic tufts ; ex. Cassiopeia, Crossotoma, &c. 4.
Polyclonidee—with four genital pouches, and sub-genital pores;
stomatodendra long, continuously dichotomously twigged ;
no long tentacles ; twelve ocelli, four per-radial, and one on
each side of each of these (ad-radial), ex. Polyclonia, Sala-

Introduction to Animal Morphology. 105

mis. 5. Cepheide—with four genital pouches, and sub-
genital pores; short, complex stomatodendra, with sucking
mouths between the terminal twigs; tentacles long, thin ;
eyes eight; ex. Cephea, Cotylorhiza. 6. Crambesside—with one
central, cross-shaped genital pouch over the stomach, and
four sub-genital pores ; arms unbranched, with no tentacles,
but with many rows of isolated, wrinkled, capitate, sucking
knobs ; four per-radial, and four inter-radial eyes; ex. Cram-
bessa.

2. Pelagiada—Discophorans with marginal ten-
tacles, containing processes of the anastomosing
somatic canals around the umbrella margin. The
trophosome may be fixed, but producing free gono-
somes; or free, developing its sex-organs in its own
umbrella. The mouth is central; the gastrovascular
system consists of pouch-like processes.

There are three families :—

1. Charybdaeidee—with no marginal canal, simple mouth-
pillar, and branching lateral canals. The tentacles may be four
(Charybdzea), or four bundles (Tamoya). The former genus
has a lenticular eye-mass (Fig. 14),and pigment spot, imbedded
in its pillared lithocyst, into which latter a pouch of the
lateral canal is prolonged. 2. Pelagiide—with a marginal
‘canal; mouth-pillar, with four long, lobate (Chrysaora) or
leaf-like lobes around the mouth (Pelagia), or simple, four-
angled (Nausithoé). There are no radial branched canals,
and eight or twelve to twenty-four marginal tentacles (Chry-
saora); when eight they may (Nausithoé), or may not, alter-
nate with sense-organs. 3. Meduside—mouth-pillar un-
‘branched, lobed ; stomach with or without pouches; radial
canals branched, and with a marginal canal. The marginal
tentacles may be very many (Aurelia, Fig. 15), or few, or
none ; in the latter cases there may be eight (Sthenonia), or
sixteen (Phacellophora), or very numerous bundles of ten-
tacles on the under side of the disc (Cyanea). The sto-
mach is four-pouched in the last genus.

106 Introduction to Animal Morphology.

CHAPTER® XViE
CTENOPHORA (£schscholtz).

SUB-CLASS 5. CTENOPHORA.*—Transparent, pelagic,
gelatinous forms, radially and bilaterally symmetri-
cal; moving by meridional, comb-like rows of ciliated,
ectodermal swimming plates (ctenophores), between
which are interspaces or ctenomeres. There are
usually eight of these (four in Cestum, twelve in
Alcinoé) ; each plate is thick, and movable by muscle
at the base; thinner, but rigid to the ciliated edge,
where the central cilia are longer than the lateral.
Towards each pole of the often ovoidal or spheroidal
body the ctenophoral ridges end in rows of cilia, nar-
rowing finally to a point. The mouth is simple, or
with raised edges, at one end (oral pole), and opens
into a fusiform, tubular stomach, lined with coloured.
hepatic (?) cells. From this passes a wide, short fun-
nel, to the apical pole, where it ends by two anal
openings (apical pores) ; or may be closed (Cestum?).
This pole is usually uppermost in swimming. From
the base of the funnel arise two paragastric canals,
which pass one at each side of the stomach, towards.
the oral pole; and below these there are two or four
others (primary radial canals) passing horizontally ;
these (if two) bifurcate into secondary radial canals,
each of the four ending in a pair of tertiary canals;
one of these passes out to beneath each row of swim-
ming plates, and is there continued from pole to pole

* This possibly should be a class, equivalent to Hydrozoa, and inter-.
mediate between Discophora and Echinodermata; to the latter of which
it has many affinities (Agasszz).

Introduction to Animal Morphology. 107

under the ridge, as a ctenophoral canal. In some, «. g.
Beroé, paragastric and ctenophoral canals open into
a circular vessel around the mouth, and the radial
canals are obsolete. The whole tubular system is lined
by ciliated endoderm.

Retractile, hollow tentacles exist in Pleurobrachia,
one at each side, in sacs about the equator of the
body. These are fringed with smaller cirrhi, and
here alone thread cells are developed, often in clus-
ters. Intothese tentacles radial canals extend. The
parenchyma consists of connective tissue like that of
meduse, and a layer of meridional and transverse in-
terlacing muscular fibres lies superficially, which can
to some extent alter the body-shape, but does not act
in locomotion. In Beroé, lateral secreting organs
exist as small bladders, only visible when full; many
such exist in Cestum.

In Chiajea, W727 has described a second vascular
system, but this has not been confirmed.

At the apical pole is a spherical vesicle (ctenocyst,
absent in Eurhampheea), lined by ciliated epithelium,
and containing a pigment mass in Bolina, Idya, Pleu-
robrachia, and an otolith, to which stiff hairs pass from
the epithelium (acoustic hairs). In Eschscholtzia there
are two pigment masses beside the ctenocyst. Near
this pole also are two oblong apical areas, sur-
rounded by branched threads, or covered with hollow,
shaggy processes ; probably areas of sensation, as a
nerve extends to them.

A ganglion is placed between the apical canals of
the funnel, sending off filaments along the ctenopho-
ral ridges, as well as in the wall of the funnel and
stomach. Gvant¢ describes a circum-oral ring, and
something like this is described by Eimer.

108 Introduction to Animal Morphology.

They are hermaphrodites, and the sexual products
arise in folds or pouches of the radial canals, the ova
at one side, and the spermatozoa at the other. The
ova are expelled by the mouth at all seasons of the
year, and develop usually with no metagenetic forms.
At first only four ctenophores exist, as in the non-
ciliated Eucharis ; some may have a larval stage, such
as the Cellephobe of Busch. In development the cte-
nophoral canals arise as offshoots from the endoder-
mal cavity, and the gastro-vascular lobes appear at
first as solid cellular cords. There may be also in
the embryo provisional oral lobes, &c., like the per-
manent auricule of some forms.

There are over one hundred species, mostly small; Chia-
jea being the giant of the sub-class. They are distributed in
four orders.

1. Eurystomata (Leuckart)—oval, wide-mouthed, with no
appendages, and a circum-oral canal. This includes the
families Beroide, with entire margins at each pole, the apical
end being either conically extensile (Beroé),. or not (Idyia) ;
Neisidze with a compressed apical pole, which is deeply
notched, and unequal ctenophores; Rangidz with a deeply
notched oral pole.

2. Saccate (Agass7z)—no circum-oral vessel; tentacles
two, turned from the mouth ; ctenophores sub-equal or equal.
The families are:—Pleurobrachidz, with no lateral folds,
and a symmetrical, round, or oval body, having the cteno-
phores reaching from pole to pole (Pleurobrachia), or only
2 or # of the meridian, and the tentacles with simple
(Eschscholtzia), complex (Hormiphora) or no appendages
(Dryodea); Mertenside have broad, often heart-shaped,
bodies, with unequal ctenophores and simple tentacles
(Heckelia), or equal ctenophores prolonged on processes at
the apical pole (Gegenbauria), or with rounded sides (Mer-
tensia); Callianiridz are cylindrical, winged at the oral pole.

3. Teniate (Agassiz)—ribbon-like, with no oral lobes;
tentacles two, turned to the mouth. There is one family,

Introduction to Animal Morphology. 109

Cestidz, including the Venus’ girdle (Cestum), with a long
stomach, and Vexillum with a larger funnel.

4. Lobate (£schscholiz)—body with a pair of antero-
posterior lobate processes ; ridges and ctenophoral canals of
unequal length. The families are: Eurhamphceide—with
beak-like apical, lobate, oral pole and no tentacles ; Bolinide—
with rounded apical pole, small tentacles not in sacs, and
with the four shorter radial ridges in pairs, smooth on the
surface (Bolina), or papillose (Bolinopsis) ; Mnemiide—with
oral lobes separated from the lateral parts of the body by
grooves, and two of the radial canals ending in arabesque con-
volutions in the oral lobes. Eucharis and Chiajea are papillose,
the others are smooth, with large (Mnemiopsis), or small
auricles (Mnemia, Lesueuria) ; Calymmidze—with lobate pro-
cesses arising from the apical end, overlapping the oral end
as a mantle; Ocyroide—with forked lobes prolonged from
the apical end.

The aberrant Sicyosoma (Gegendaur), with no ctenophores
nor gastrovascular canals, but with nettle cells in the body
wall, may form a fifth order, or may be the young of Cestum
(Agassiz), or an Actinian larva (A7ehn and Letickart).

CHAPTER. XVITA:
CEASS. 2. ACTINOZOA,

RADIATED ccelenterates with tentacles (Fig. 17, 2)
round the mouth at the distal pole, and with a
stomach cavity separate from, ‘suspended within,
and opening into, the body cavity (s), the portion of
which around the stomach (perivisceral space) is di-
vided into compartments by vertical, radiating, mem-
branous partitions, mesenteries (Fig. 17, 7’), in which
the sex-organs are developed. Thus in transverse

110 Introduction to Animal Morphology.

section an actinozoon appears as two concentric tubes,
whose walls are joined by the radial mesenteries, while a
hydrozoon appears as a single
tube. Striped muscle, several
forms of connective and gland
tissue exist in some; but they
have no nervous nor vascular
system. Theectoderm consists
of two lamine, an outer, ecderon
or epidermis, of epithelium,
pigment, clear irregular gland
cells, and trichocysts with be- sectionofSea Anemone; 7, mouth;
bristled filaments, growing from i pelaplanicebeen oan nodose
f : ; doderm; 7, tentacle; g, generative
within outwards; and an inner, element; ¢, disc; s, body cavity.
enderon, growing from without inwards, made of
granular, striated connective tissue. The endoderm
consists of a muscular layer of circular and longitu-
dinal fibres (the former strongly developed in the
tentacles and around the mouth; this stratum may be
intermediate or ectodermal in origin), a connective
lamina, and an internal ciliated epithelium. The
tentacles are hollow, contractile, or fully retractile,
lined by endoderm, and both sensitive and prehensile;
between these and the mouth is a peristomial space.
The mesenteries are arranged in several orders suc-
ccessively developed: primary, reaching from the body
to the stomach wall; secondary, not extending to the
stomach, and placed between the primaries, &c.

A skeleton may be formed in the ectoderm by the in-
clusion of sponge spicules and other foreign bodies (Sagartia
Schilleriana, Heterozoanthus), but usually by the deposits of
calcium carbonate in the connective lamine. ‘These deposits
may be (1) discontinuous, of small, definitely shaped, spicular
bodies, as in Alcyonidz; or (z) continuous, coherent skele-

Introduction to Animal Morphology. IIT

tons, which may be (a) isolated, or amalgamated with a horny*
or chalky interstitial substance (axis of Melithea, &c.),
or (8) lamellated, with or without an organic basis (as
Gorgonia or Primnoa), or (y) crystalline, increasing by
chalky deposits, with scarcely an organic basis (Madrepores).
Spicules (Sclerodermites) are fusiform, laminar, ovoid, or
stellate ; a spicular skeleton is a polypzeroid ; one continuously
calcified, a polyparium or corallum;t+ the hard tissue is
Sclerenchyma, which may be compact or porous. Each
persona (Corallite) of a polyparium consists of some of the
following parts:—1. A calcified, ab-oral /oo/, continued in
colonial forms into the ccenenchyma. 2. The calcified
enderon of the persona (/heca) forming the wall of the cup
(calyx) ; this may consist of two layers, an endo- and an exo-
theca. 3. Calcified mesenteries (sef/at), passing in from the
endotheca, dividing the calyx longitudinally into radially-
arranged loculi. 4. Rib-like ridges on the outside of the
exotheca, opposite each system or between two (cos/ae).
5. Outside the exotheca, an ecderonic investing layer or
epitheca may form, often developed in inverse ratio to the
thickness of the theca. 6. Between the simple zooids ofa

* Apparently horny, but really chitinoid ; intermediate between Chitin
and Keratin.

t+ Analysis of Coral gives 89-96 per cent. of Calcium Carbonate ;
03-250 of Calcium and Magnesium Phosphate and Fluoride; 0°50 organic
basis with traces of Silica, Iron, Alumina. Magnesium Floride is present
in Peecilopora. There is, however, much variety. Silica may in some
cases reach 25 per cent.; Magnesia, 45 per cent. The specific gravity of
Coral averages from 2:20-2:80.

t Septa grows in cycles, the five or six primary folds form the first, the
secondary the second (also of five or six). Between these a third cycle
forms, of twelve laminz, one in each interval. The fourth cycle consists of
two orders of septa, one between every first and third, and one of still
shorter plates between the second and third. The fifth cycle consists of
three orders : one of shorter plates than the fifth order, between those of
the first and fourth ; a seventh order between the second and fifth ; an eighth
between the third and fourth, &c. Each order after the third cycle consists
of twelve laminz ; so when a whorl consists of eight orders they will follow
each other thus :—1, 6, 4, 3, 8, 5, 7, 2, 7, 5» 8, 35 4, 6, 1, &c.

112 Introduction to Animal Morphology.

colony there is ofteu an ecderonic tubular or laminar con-
necting material (feritheca), often as horizontal plates uniting
the zooids (epzthecal dissepiments). 7. A central columella may
form in the middle of each calyx, corresponding to the
enderon forming the floor of the somatic cavity below the
stomach; when this is a distinct pillar it is called columella
propria; when it consists of the centrally united septa, it is.
c. septali’s or pseudocolumella. 8. Smaller detached rods around
the columella, formed of the dismemberments of septa (palit
or bacill’). 9. Short transverse bars may unite one septum to
its neighbours (synzapticule). 10. Horizontal plates growing
inwards from the sides of the septa (endothecal dissepiments)
may divide the chambers into storeys; when these are com-
plete they are called fadu/e. A central pillar-like elevation of
the tabulz is a columella parie‘alis. The presence of a coral-
lum precludes locomotion.

The stomach wall often contains pigment (hepatic)
cells. The somatic cavity extends as a canal system
into the coenenchyma ; within it chyle corpuscles cir-
culate in a vehicle of sea water, which enters by the
mouth, and is expelled through the pores at the tips
or sides of the tentacles. On the mesenteries are
richly ciliated coiled threads (craspeda) containing
guanin, and consisting of an axis, often a central
closed canal, and a peripheric layer armed with thread
cells: these may protrude through small openings
(cinclides); sometimes found in rows on the body
wall, through which sometimes the chylaqueous fluid
escapes from the body cavity.

Reproduction is sexual, the sexes being separate
or united. The ova and spermatozoa arise along the
borders of the mesenteric folds, and when immature
the sexes can only be distinguished by the microscope.
The ova are fertilized in the body cavity, and the
ciliated planuliform larve are expelled by the mouth.

Introduction to Animal Morphology. 113

Fission may also occur, and may be imperfect, vertical,
producing cespitose, or horizontal, producing la-
mellar masses. Buds may also form, and may be
basogenic (from the base of the parent), stoloniferous
(from basal stolons), perigenic (from the sides of the
parietal ccenenchyma), or calycular, arising inside the
cup of the parent.

There are two sub-classes:—1. Zoantharia (Hex-
actinia)—having the mesenteries and simple, rarely
branched tentacles, in multiples of six (or five); the
former are in pairs; some or all of them bear longitu-
dinal muscular bands (vanes); around the mouth is
often an annular canal communicating with the several
perivisceral spaces; they are marine, and have no
central horny axis in their coenenchyma, except in
Antipathide.

Three orders are included :—r1. Malacodermata—
sea anemones ; rarely colonial, with either no corallum
or a few spicules; the body cavity is distended by
water, which can be expelled on irritation, causing
a rapid collapse; the tentacles are numerous, the
sexes separate (except Sagartia troglodytes), the body
cylindrical, and the craspeda developed. They can be
multiplied by artificial division; the embryos are
planuliform, then become ovate, and settling down
(sometimes in eight days), a mouth forms at the larger
end; the wall of the digestive sac forms as a ring
around the mouth, which grows down into the body
cavity.* At first the tentacles are five or six, and the
mesenteries as many, but they increase in number
rapidly. They live for several years. Cne kept by
Dalyell for six years produced 276 young. In the

* This is either a down growth or an invagination.
I

114 Introduction to Animal Morphology.

China Sea they have been found up to three feet in
diameter, and containing Clupeoid fishes as com-
mensals (Collingwood).

Three families exist :—1. Zoanthida—the only colonial
forms, with a creeping, leathery, filiform, spiculigerous
coenosarc; zooids united by a flat, root-like mass of stolons
(Palythoa), or by basilar budding (Zoanthus). The tentacles
are in several cycles, each one communicating with one
segment of the perivisceral cavity. Foreign bodies may be
enclosed in the coenosare (Heterozoanthus).

2. Cerianthide—hermaphrodite ; with no spicules; ten-
» tacles in two concentric circles, not alternate, two communi-
cating with each intermesenteric space. ‘The mesenteries
do not extend to the hinder end, and in the young there are
only four. The aboral end is pointed, perforate (Cerianthus),
or imperforate (Saccanthus). In the former, two mesenteries
extend farther than the others, and a deep, gutter-like groove
continues along its body cavity to its foot. It throws offa
slough of thread cells and mucus, mixed with foreign bodies.
Saccanthus has equal mesenteries.

3. Actiniide—separate person, with many series of ten-
tacles; stomach with two lateral grooves (cartilaginous in
Sphenopus). ‘This includes four sub-families :—Minyadinze—
having the foot dilated into a rounded air-holding sac; the
body may be warted (Minyas) or smooth, with simple
(Plotactis) or lobed tentacles (Nautactis). Actinina—foot
with a muscular sole (sucking disc); tentacles conical, often
uniform, not retractile (Anthea) or retractile (Actinia). The
mouth may have two long lips (Actinopsis), or several crispate
lobes (Metridium), or a trifid lip (Siphonactinia). A few are
rounded, or pointed distally, and free swimming ; of these,
Peachia and Halcacampa have a distal perforation. Milnea
and Arachnactis are rounded, and the former has a median
epidermic girdle; Ilyanthus is pointed, imperforate ; cinclides
are numerous, and often wart-like in Cribrina, Sagartia,
Adamsia, &c. Phyllactinaee—tentacles both simple and lobate,
the latter in an outer cycle (Phyllactis), or between two series
of simple ones (Rhodactis). Ulactis has a warted body.

Introduction to Animal Morphology. 115

Thalassianthine—tentacles all compound, outer hooked,
papillose (Heterodactyla), or the inner with rounded warts
(Sarcophianthus). The stem of the branched tentacles may
be warty (Phymanthus), or filamented (Actineria); the branches
may be pear-shaped (Actinodendron), or feathery (Thalas-
sianthe).

Order 2. Sclerodermata (Madreporaria)—colonies,
rarely simple; skeleton enderonic, continuous, cal-
careous, with hexameral symmetry (tetrameral in
Rugosa). This includes the reef-building corals of
past and present ages.

The following sub-orders are included :—1. Rugosa (sur-
mised to belong to Hydrozoaallied to Milleporidz), Palaeozoic*
with thecz, complete tabule and rudimental, or perfect im-
perforate septa, without synapticule; in multiples of four.
They have no true ccenenchyma, and increase by parietal or
calycular budding, not by fission. Four families are con-
tained :—1. Stauride—simple or branched, with incomplete
septa, united by lamellar dissepiments, the four primary septa
forming a cross. 2. Cyathaxonide—simple, with complete
septa and one septal groove ; dissepiments and tabulz none.
3. Cystiphyllide—simple, vesicular, with slight septa, and
bladder-like endotheca; sometimes an operculum to the
calyx. 4. Cyathophyllide—simple or branched, with incom-
plete septa and tabule; endothece closing the chambers ;
columella present (Axophyllinae), or none; septa regular
(Cyathophyllinz), or irregular (Zaphrentine). The Devonian
Calceola has an operculum of one, Goniophyllum of four
valves.

Sub-order 2. Tabulata—hexameral corals with tabulz and
few imperfect septa, including the families :—1. Seriato-
poridz—tree-like ; coenenchyma abundant, compact; septa
weak or bacillar; tabula few; chambers filled by the thick
wall and columella; palaeozoic, except the Red Sea Seriato-
pora. 2. Favositide—tabule strong; thece united to their
neighbours, with little or no coenenchyma; Peecilopora is the

* Except the Cretaceous and Eocene Stauridian genus Holocystis.

re

116 Introduction to Animal Morphology.

only living genus; these are referred by some to Hydrozoa.
3. Thecidee—Paleozoic ; thick, massive ; tabulz many ; septa
not reaching the centre, but uniting peripherally into a dense
spurious coenenchyma.

Sub-order 3. Tubulosa—Palaeozoic corals with a simple
pyriform (Pyrgia) or connected (Aulopora) colony with no
columella nor tabulz, and striz representing septa, and with
an imperforate theca. In Aulopora the ccenenchyma is basal.

Sub-order 4. Perforata—corals with a porous or netted
coenenchyma, with no tabule, well-developed septa, and
rudimental dissepiments ; thecz not costate. This includes
the families :—1. Madreporide—compound with thick, simply
porous thecz, not distinct from the coenenchyma ; chief radii
little or not at all perforated ; two strong septa may reach the
middle (Madrepora), or a spongiose columella may exist with
closely converging laminz (Eupsammide). Turbinarinze
have six strong septa developed without (Astreeopora), or with
acolumella (Turbinaria). 2. Poritidz have no lamellar septa,
but trabecule or bacilli form a netted skeleton ; the calyces
may have rudimental dissepiments; ccenenchyma either
netted, spongy, separate (Alveopora), or indistinguishable
from the calyces (Psammocora), or else rudimental or none
(Poritine).

Sub-order 5. Aporosa—with an imperforate (except in
family 7), compact, lamellar sclerenchyma; strong, rarely
perforate septa; well developed, often costate thece ;
chambers open for their whole extent, or partly closed by
dissepiments or synapticulz ; thecze and septa better deve-
loped than in other corals. This includes eight families :—
1. Turbinolide—simple ; multiplying by fission or budding ;
no ccenenchyma, dissepiments, nor synapticulz (except in
Ccenocyathus) ; surface granular. A columella may or may
not exist, and when present it may be surrounded by one
(Caryophyllinz), or many (Trochocyathinz), or no circlets of
bacilli. 2. Dasmiidee—Eocene corals with each septum made
up of three lamella attached to the costate thece. 3. Stylo-
phoride have abundant loose spinose ccenenchyma; septa
large, and coste strong; central cavity interrupted, not filled
by dissepiments ; gemmation irregularly lateral. 4. Oculi-

Introduction to Animal Morphology. 117

nidee—tree-like ; loculi divided by a few dissepiments, obli-
terating part of the calyx; budding lateral; coenenchyma
abundant, not distinct from the thecz; septa generally few,
usually with a columella; costz as striations or granules ;
septa may be unequal (Oculininz), or equal (Stylasterine),
with (Axohelia) or without coste; pali may form one
(Sclerohelia) or more circlets around the columella, or this
last may be absent (Trymohelia). 5. Astraeida—single or
compound, with no true coenenchyma nor synapticule ; each
theca joined directly to its neighbour, or united by its largely
developed coste, or by exothecal dissepiments ; endothecal
dissepiments numerous at the base; septa many, often in-
complete within, smooth (Eusmilinz) or spinose (Astraeinz) ;
the former group may have single corallites (Trochosmilia),
or many multiply by incomplete fission (Euphylliacez), or
gemmation (Stylinacez). Astraeinze contains five groups:
Lithophylliacea—simple, ccespitose or labyrinthose ; Faviacez
reproducing fissiparously, each calyx retaining its indivi-
duality; Astraacea massive, reproducing by gemmation ;
Cladocoraceee—tree-like, budding laterally; Astrangiacez
budding from stolons, or from the base, with short stocks.
6. Echinoporide—lamellar; gemmation sub-basilar; coral-
lites united at base by a spinose ccenenchyma. 7. Meruli-
nidz, with no ccenenchyma nor synapticule; theca per-
forate, with dissepiments ; septa imperforate. 8. Fungiidae—
simple or compound ; thecze feeble, porous, or none, with no
dissepiments nor tabulez, and many wart-like or spinose
synapticule ; gemmation basal ; the septa are porous, toothed,
or echinulated along their free edges, as are the thece in
Funginz, not in Lophoserine.

Order 3. Antipatharia (Edwards, Sclerobasica).—
Colonial forms with no sclerodermic deposits of lime,
but a solid, often black, axis (sclerobasis). The
zooids have six short broad tentacles.

Sometimes the ccenenchyma contains siliceous bodies,
rendering it granular (Leiopathes); its branches may unite
into a network (Arachnopathes), or fan (Rhipidopathes), or

118 Introduction to Animal Morphology.

remain free (Antipathes), or the unbranched axis may be
spirally twisted (Cirrhopathes). About thirty species are
known, mostly from deep Palearctic sea bottoms.

Sclerodermic corals only exist in clear sea water,
unmixed with freshwater, where the winter temperature
does not sink below 66° F., and usually between the
limits of 1-30 fathoms.

Three forms of reef exist :—1. Barrier reefs, gird-
ling continents or islands, at a distance from land.
2. Fringing reefs, surrounding islands, only separated
therefrom by shallow channels, and sloping seaward.
3. Atolls, or circular coral islands, with a lagoon in
the centre. The first and last forms grow on a
gradually subsiding, the second on a gradually rising,
sea bottom.

CHAPTER KIZG
ALCYONARIA.

SUB-CLASS 2. Alcyonaria (Edwards, Octactinia, Ehren-
berg).—Actinozoa, with eight short, broad, pinnately-
fringed tentacles, and mesenteries in multiples of
four; usually with spicules, but no continuous en-
deronic skeleton. When the outer skeleton is conti-
nuous, it is epithecal, and there may be centrally a
sclerobasic axis or a tubular system. The eight septa
are not in pairs, nor do they bear longitudinal bands
of muscle. The following orders are contained :—

1. Alcyonaceee—Sclerobasis none; ectoderm leath-
ery, with noepitheca, but with calcareous spicules. The

Introduction to Animal Morphology. 119

somatic cavities of the polyps extend into the cceno-
sarc as a communicating tubular system, into which
the mesenteric folds extend. The sex organs develop
on these, as in Zoantharia, and craspeda are often
present. j

Three families are contained :—1. Cornulariide—rarely
simple (Haimeia with retractile polyps and a simple tube;
Hartea,* with stellate basal, and branched Fig. 17.
tentacular spicules), generally compound, ;
increasing by basal budding or bystolons;
in the former case, the spicules may be
fusiform, or cylindrical, spiny or tuberous,
and the polyps retractile (Sympodiumf),
or non retractile (Anthelia); the outer
layer may be smooth and the polyps re-
tractile (Lobularia). The stoloniferous
forms may have non-retractile, wart-like
calyces and a creeping, thick coenosarc bh Sees AP
(Sarcodictyum). The polyps may be Muricea granulosa; d, Al-

: - : cyonium digitatum; e, Pa-
tubular, non-retractile (Rhizoxenia), OY ralcyonium elegans.
retractile, ribbed and spiculigerous (Clavularia), or smooth,
non-spiculigerous (Cornularia). 2. Telestide—compound,
increasing to a tree-like colony by lateral budding, ex.
Telesto. 3. Alcyonidze—lobate or branched masses, formed
by lateral budding, often granular on the surface. Alcyo-
nium is fleshy, lobate, with retractile polyps on all sides;
Sarcophytum has a discoidal pedicellated polypieroid, barren
beneath ; Ammothea has semi-retractile zooids; Belonella is
capitate, with plaited-mouthed zooids; Xenia has clustered,
non-retractile polypes on the ends of the branches of a soft,
slightly-branched coenosarc; Nidalia has a cartilaginous,
cylindrical stem, with fusiform spicules, the zooids on the
upper surface of a hemispherical head; Spongodes has a
membranous, cellular, outer surface covered by opaque, fusi-
form spicules ; Nephthya has a branched, coriaceous, granu-

* This may be an immature form of Alcyonium (Wright).
t This may belong to Briareacez.

120 Introduction to Animal Morphology.

lated coenosarc, with large external spicules, and sub-cylin-
drical incurved polyp-cells; Paralcyonium is membranous,
branched, with large dermal spicules at the base, the somatic
cavities opening freely into each other.

Order 2. Tubiporaceee (organ-pipe corals of the
Indian Ocean)—sclerobasis none; the purple-red
epitheca is tubular, made of consolidated spicules
(Wright); the tubes are united by table-like, calcified,
perithecal dissepiments, from which new tubes bud ;
the eight green tentacles have oval lenticular spicules ;
the central mouth has a circular lip. Onirritation, the
tentacles first close together, then the whole polyps
sinks into the tube. The stomach has delicate walls,
ex. Tubipora.

Order 3. Pennatulacez (sea-pens)—sclerobase soft,
free-swimming, or sand-embedded, of calcified, horny
matter, traversed by soft radial bands. The lower
part of this axis is barren; the upper, or Jars polypz-
era, is variably branched, and its ectoderm is spiculi-
gerous (except in Halisceptrum and Lygus).* Three
kinds of zooids may exist:—1. Nutritive, tentaculate.
2. Sexual, non-tentaculate. 3. Rudimental, neither
sexual nor tentaculate.

Therearethree families :—1. Pennatulide—feather-shaped
colonies ; polyps along the margins of the pinnately-branched
axis; pars polypifera bilaterally symmetrical. In these, the
principal zooids may reach the fleshy pinnz, and the spicules
may be fascicular (Pteroides), or the zooids are on the ventral
side of the rachis, with the spicules scattered (Pennatula), or
none (Halisceptrum, Sceptonidium). The pars polypifera
may be narrow, and the pinnz short, with no spicules
(Virgularia, Lygus), or with a spicular plate below the pinnz
(Stylatura); or the zooids may be on a thick ridge of the

* Richiardi gives the name Zoanthodema to the coenosarc.

Introduction to Animal Morphology. 125

quadrangular rachis, with spiculigerous tentacles, and no
pinne (Pavonaria); or on thick pinnz alone (Scytalium).
Funiculina and Halipterus have no pinne; the former has
dorsal zooids and eight-toothed calyces along its rod-like
axis; the latter has lateral zooids with two-toothed cups.
Umbellularia has a long sterile axis, and the zooids, at first
simple, symmetrical, become grouped (20-30) in an umbrella
at the upper end. Pennatula and some of its allies are lumi-
nous, the light inhering in eight cords, consisting of vesicles
containing fat and multipolar cells (Pancer’), on the outer
surface of the stomach of the zooids, continued in the buccal
membrane.

2. Renillide have a kidney-shaped, parenchymatous,
laminar stock (a single pinnule), with the retractile zooids on
one side; no solid axis.

3. Veretillida—axis elongated, quadrangular, having re-
tractile zooids on its entire surface; its lower part bulbous,
naked (Lituaria), or soft; longitudinally divided into four
tubes by two intersecting membranes, with a calcareous axis
in the lower part of the stem (Cavernularia) ; or simple, fleshy,
with a rudimental, membranous (Sarcobelemnon), or boat-
shaped axis. A primordial Australian form (Pseudogorgia
Godefroyi) has simple rows of polyps, each on a warty pro-
jection of the polypieroid, and no trace of an inner, horny, or
calcareous axis, but a broad, single, central canal, a pro-
longation of the combined somatic cavities. There are two
long, slender, and six short, thick mesenteric filaments. This
is a passage form to Briareacez.

Possibly the club-shaped Kophobelemnon, with thin cal-
careous axis, and no pinnules, should be the type of a separate
family linking Veretillidz to the true sea-pens.

Order 4. Gorgonacee—rooted ; usually branched
colonies with minutely-ridged, flexible sclerobase; often
with characteristic enderonic spicules (dermosclerites) ;
thece often operculate.

Three families are included:—1. Primnoide—ccenen-

chyma, with scaly sclerites, and club-like zodid-bearing
papille (Primnoa) ; or spinose, with boat-shaped spicules and

122 Introduction to Animal Morphology.

cylindrical papilla (Muricea). In Primnoa, the operculum
consists of three-pointed scales, and the axis consists of con-’
centric, calcified, horny lamellze, surrounded by alternate,
non-spiculigerous rings of horny and crystalline calcareous
matter.

2. Gorgonidee—ccenenchyma smooth ; axis horny, some-
times flat, leaf-like, with anastomosing branches forming
small (Xiphigorgia) or large interstices, whose meshes are
either open (Rhipidogorgia) or filled with soft coenenchyma.
In this case the sclerobase may be expanded into thin
lamellz (Phycogorgia); or round, with netted branches in
the leaf-like coenenchyma (Phyllogorgia*). In others, the
branches are tree-like, not anastomosing ; and the zodids are
disposed either regularly on both sides of the ccenosarc
(Pterogorgia), or irregularly over its whole surface, which
may be fan-like or tasseled (Lophogorgia). The zodids are
either sunk into the thick, corky (Plexaura), or skin-like
(Leptogorgia) coenenchyma, or project on warts, with rounded
(Gorgonia) or bilabiate calyces (Eunicea). Plexaurella has
spicules in laminz between layers of horny matter. Sclero-
gorgia has an uncalcified, horny, spiculigerous axis.

3. Gorgonellidaz—axis corneo-calcareous, either straight,
unilaterally comb-like (Ctenocella), or rod-like (Juncella), in
structure like Plexaurella, but with spicules in the horny
laminz ; or branched, with (Vermicella) or without projecting
zodids (Gorgonella). In the last, the horny lamelle are con-
centric, calcified.

Order 5. Isidacezee.—The axis consists of alternate;
soft, and calcareous joints.

This includes two families :—Melithzidze—soft joints,.
suberose, concentrically laminated; hard joints made of
cemented spicules; branches arising sometimes from the
horny joints, which may be traversed by tubular canals
(Melithzea) ; Isidida—hard joints of concentrically laminated,
calcified membrane, traversed by radial lamellz, but without
spicules; soft joints horny, like the axis in Gorgonide ;.

* Hymenogorgia differs in having free branches.

Introduction to Animal Morphology. 123

branches arise from the calcareous (Isis) or horny joints
(Mopsea). Parisis seems to be a passage form.

Order 6. Briareaceee.—The axis is never horny,
but may be hollow (Ccelogorgia), or filled with spongy
tissue, with szlsceows (Solanderia), or calcareous
spicules (Briareus), and with large, nutritive canals,
or none (Spongioderma). The polypes may be partly
(Solenogorgia), or wholly retractile, either embedded
in the cortex (Paragorgia), or in wart-like calyces
(Briareus).

Order 7. Coralliacee—axis rigid, unjointed, cal-
careous, branched, finely grooved on the surface;
coloured deep red by iron oxide, with little or no.
organic matter. This is coated by a red ccenosarc,
traversed by the canals extending from the bodies of
the retractile, white polyps. These canals have per-
forate walls, and contain a milky, corpusculated fluid.
The precious red coral of the Mediterranean (Corallium
rubrum) belongs here. It lies in 10-30 fathoms of
water.

CHAPTER 2X.

SUB-KINGDOM 4. ECHINODERMATA.

MARINE, never colonial animals; each made up
of several (usually four or five) radially, often
bilaterally, symmetrical antimeres. The integu-
ment has a ciliated outer layer, beneath which
is a dermis containing calcified, never chitinous,

124 Introduction to Animal Morphology.

plates or spicules: this is called the perisome,
and it often bears spines. The nervous system
consists of a circum-oral filament, uniting the long,
radially-divergent threads, which are coloured orange,
brown, or green, by a pigment layer over the neuri-
lemma. The ciliated digestive canal is separate from
the cceloma or perivisceral cavity,* which is also
ciliated, and contains sea-water. A peculiar set of
water-holding canals Fig. 18.
exists (Fig. 18), separate
from i eae tract, SS Z
although arising as an
outgrowth from it, lined
by ciliated protoplasm ;
this consists of a ring
around the mouth, giving
off radial branches (c),
one or two in every anti-
mere, each again giving , Ambulacral sytem of Retinus, 4, ambu
off rows of small, hollow, # Pelian-vesicie; 7. madreporiform plate.
muscular processes (ambulacra, or pedicelli a), which
project on the surface, and by which the animal
moves. ‘This connexion of locomotion with the water-
vascular system is characteristic. Attached to the
circum-oral canal are also inter-radial sacs (Polian
vesicles, Fig. 18, 4), acting as reservoirs for the fluid
(which is sea-water containing chyle corpuscles).
Agassiz compares this system with the canals and
tentacles of Ccelenterata.

Muscular tissue is developed in the perisome in
inverse proportion to its calcification ; least in Echini,

* But this, as well as the water vascular system, is an outgrowth from
the alimentary canal (Metschnikoff and A. Agassiz).

Introduction to Animal Morphology. 125,

most in Holothuriz. The fibres are usually unstriped,
except in the jaw-muscles of Echinus, and the longi-
tudinal bands in Synapta. A non-ciliated, pseudhe-
mal circulatory system exists in most species, consist-
ing of a ring-like (arterial ?) canal, between the nervous
and water-vascular rings around the cesophagus,
with sometimes a second circum-anal (venous ?) circle,
and a fusiform muscular heart, uniting the two
circles.

The sexes are separate (except in Synapta,
Molpadia, &c.) The eggs are small, consisting ofa
shell, albumen, and a fine-grained yelk ; development
begins by the disappearance of the germinal vesicle,
and may be direct, but usually the egg produces a
larva (pseudembryo, W. Thomson), of which (except
in Crinoids and Holothurians) only the part around
the digestive canal develops into the mature form,
the rest being only provisional. This larva is
bilaterally symmetrical, and resembles that of some
of the Annnlosa. In this
stage all Echinoderms are
somewhat like in struc-
ture. From the egg is
emitted a ciliated planula,
whose cilia become re-
stricted to transverse or
lateral bands, which often
elongate into processes.
A stomach and intestine
form within, beginning asa 4
pouch, convex backwards,
opening at first by an
anus, but soon developing a

Pluteus larva of Ophiolepis ; s, skeleton >
A, pedicelli; s’, stomach; #z, mouth.

126 Introduction to Animal Morphology.

mouth. Close to this digestive tube a discoidal mass
of protoplasm forms, first on one side, then extending
around it; then, according to JAZzil/er, an involution
of the integument at one side of the back forms a
pouch, which narrows into a tube, whose fundus
dilates, in the protoplasm around the stomach, into a
rosette, extending around the cesophagus as a circular
vessel, from which the rudiments of the ambulacral
canals and pedicels arise. The primary involution
narrows into a tube, the stone-canal or hydrophore,
which leads from the outer ab-oral side into the ring-
canal; its outer opening becomes closed by the for-
mation ofa perforated, often labyrinthically tubulated,
calcareous scale, the madreporiform plate. The later
researches of J/etschnikoff and Agasszz indicate that
the perivisceral cavity, as well as the ambulacral
canals, are formed as offshoots from the digestive
canal. A symmetrical larval skeleton of spicules
may exist (except in Asteriade and Holothuriade),
no part of which is transferred to the adult. Whena
cceloma exists in the larva, it isnot continued into the
perivisceral cavity of the adult.*

This sub-kingdom is divisible into three classes :—

CLASS 1. STELLERIDA—Starfishes, having a central
disc, and usually 5-20 diverging arms., The peri-
stome is not calcified through its entire thickness, and
consists of :—ist, a leathery papillary layer, whose
spinose process may be clustered, bristle-like points
(paxillz), or echinulated, one-jointed spines. 2nd, a

* Prof. Huxley originally united these and the Scolecida under the
name Annuloida, a convenient, though unnatural, grouping, as the
Echinoderms are Deuterostomes, while most of the Scolecides are Archzeo-
stomatous. Such a group would consist of animals with a separate ali-
mentary canal, a water-vascular system, and a thread-like nervous system.

Introduction to Animal Morphology. Pay

calcified* layer of many-jointed plates,t bounding a
central, ambulacral groove on the under surface of
the arms. The dorsal surface of the body is convex,
and called antambulacral.

The mouth is central, inferior, often surrounded
by flat spines or tooth-like processes; it opens into
a central globular or pentagonal stomach in the
centre of the disc, held in its place by radial mesen-
teries. The intestine is spiral, ending near the mouth
(Comatula), or short, ending in a dorsal anus, or none
(Ophiuride, Ctenodiscus, Llwydia, Astropecten). The
circulatory organs consist of the circum-oral and
circum-anal rings, and a pulsating heart. (Yourdain
regards this as a gland, and the other pseudhemal
tubes as water-vascular.t) For respiratory purposes, the
sea-water not only bathes the surface, but enters the
body cavity either by surface pores, or by the genital
fissures (Ophiuride), or by inter-radial lamzne cribrose
(Solaster, &c.), as well as by the porous madrepori-
form plate. When there are several of these plates,
as in Echinaster, there have been several larval invo-
lutions of integument, and hence several stone-canals.

The pharyngeal nerve ring has few nerve cells,
or none (Asteracanthion), and sends two threads
covered with ganglion-cells (ambulacral brains)
along each ambulacral space; these widen to the
middle, and send branches to each joint of the
calcareous axis. Muscular fibres lie between the
joints of the skeleton, to assist in locomotion. The
ambulacral system consists of a circum-oral ring,

* Containing a trace of Calcium Phosphate.

oT Corresponding to the Auriculz of Echinide.

¢ The existence of a separate circum-oral vascular ring has been recently
‘denied.

128 Introduction to Animal Morphology.

Polian vesicles, and radial ambulacral canals with
pedicelli. Each of the last is a muscular tube, ending
externally in a foot and sucking disc, and having at
its inner or attached end a canal for the ambulacral
vessel, and an opening into a muscular ampulla or
reservoir (Fig. 18, 6). The foot consists of longitu-
dinal and circular muscular fibre, covered by ciliated
epithelium. Contraction of the ampulla and of the
circular fibres extends the foot, which is contracted
and retracted by the longitudinal fibres.

The sexual organs are grape-like pouches in the
inter-radial spaces. Development is rarely direct, or
viviparous. In common with all Echinoderms, they

can reproduce lost parts.

This class contains six orders :—

1. Blastoidea (Fleming )—Palaeozoic, pentameral, armless,
bud-like forms, fixed on a jointed, perforated, immovable
stalk, with a central mouth, inter-radial genital pores, and
with or without (Eleutherocrinus) an anus. The body (calyx)
consists of thirteen plates in three circlets, the lowest of three
unequal pentagonal basal tables; the second circle of five
forked radial plates, between which are five trapezoidal, inter-
radial plates. Above the calyx are five lancet-shaped ambu-
lacral pieces, homologous to the sub-ambulacral plates of
crinoids, fitting into the forks ofthe radial plates, and bearing
pinnule along their margins; their surfaces are striated, and
their margins perforated by pores. About fifty fossil species
are known. ‘They have large genital pores in five pairs, each
over an inter-radial (Pentatremites), or over an ambulacral
plate (Elceacrinus). The pores may be in three pairs and two
single (Eleutherocrinus).

2. Cystoidea—Palaeozoic, pedicled, or sessile; body glo-
bular or polyhedral, rarely flattened (Agelacrinus), with a wall
of many (often 1-2—300), sometimes porous, polygonal plates
in radial zones; mouth central, surrounded by pinnules or
weak arms, which may be fixed, or (rarely) free, pinnulated

Introduction to Animal Morphology. 129

(Comarocystis); anus always present; there were five lateral
ovaries (?) with openings, when present, surrounded by five
plates, almost always present; the pillar is short, jointed, or
none. About 8ospecies are known as fossils. Hyponome, from
Cape York, Australia—a small star-like free disc, ventrally
convex, with no calyx, and a dorsal scaly rosette—is the
nearest living ally, and approaches Agelacrinus.*

3. Crinoidea—stalked, at least in early life, with a cup-
shaped body of calcareous plates, with from 2-18, but com-
monly five, solid, primary, often branching, arms, independent
of the visceral cavity, except at the base, and furrowed longi-
tudinally above for the tentacle-like pedicelli given off by the
ambulacral tubes lying in these medial grooves radiating from
the mouth. This system seems purely respiratory. The
arms can move rapidly, and can close over the oral disc for
protection ; they have laterally articulated pinnules appended.
The ventral surface is, as in the last order, upturned; the
dorsal stalked.

The mouth is usually central, and in some fossil forms
mounted on a proboscis. The ciliated stomach winds around a
spongy calcareous spindle (compared to the lamina spiralis of
the Mammalian cochlea). The anus may be ventral, between
two water-vascular furrows, or absent (?) (Holopus). The di-
gestive canal never extends into the arms. The pseud-
hemal system consists of a central sacculus giving off
branches to the arms. The ovaries are external, membranous
lamellz developed under the soft skin on the ventral surface
of the pinne. The testes are similar, and the products
emptied by dehiscence.

The column rises from a root-like disc, adherent to some
solid body; sometimes several are rooted together. The
pillar itself consists of superposed calcareous joints, traversed
by a single or multiple axial canal. The joints are united by
ligaments and interarticular laminz of elastic vertical fibres,
and in some there are bundles of unstriped. muscle-fibres
(none in Pentacrinus); here and there are whorls of jointed
cirrhi. The basement material of the calcareous plates is a

* Chapman proposes an order Thyroidea for some forms which possibly
linked these to Asteroidea, ex. Edriaster.
K

130 Introduction to Animal Morphology.

soft, flexible, connective tissue, which calcifies by the deposi-
tion of netted, calcareous bands, longitudinally and trans-
versely. In Phytocrinus, the stalk at first bends spirally.
The body consists of—rst (next the pillar), 2—5 dasa/ plates
forming the elvis. 2nd, one or two circlets of parabasal
plates. 3rd, several orders of rvadza/ plates along the lines of
the arms; the upper surfaces of these have often two articular
faces at an obtuse angle for the two arms (vadialia axillaria).
There may be also several orders of zufer-radial plates.
The arms are often branched; their joints may be free, or
united by syzygies (immovable sutures). To these the
pinnule, each of which receives a fine thread from the nerve,
are laterally appended. ‘The segments may be numerous ;
thus in Pentacrinus briareus there are five basals, fifteen radials,
ten primary arms, each of seven joints, two secondary arms of
200 joints on each primary, eighteen hundred-jointed pinne on
each secondary arm, and 36,000 ten-jointed pinnules.

The embryo begins as a free ciliated body, which elon-
gates ; a bundle of cilia projects at the anterior end ; then it
assumes somewhat the appearance of a four-jointed worm, at
each segment of which is a ring of cilia; a calcareous net-
work now forms in the wall, and a mouth develops, which,
however, with the cilia is soon lost; the animal then becomes
sessile, somewhat polypoid, develops knobs at its free end
and an alimentary canal; the extended calcareous skeleton
masks the growth of the viscera, and the embryo becomes
opaque. Within the mouth a set of irregularly lobed gland
masses, brownish in colour, and probably hepatic, appear.
The pillar lengthens, and calcifies rapidly. There are about
600 fossil, and about 48 known living forms, divided into two
families.

Encrinide—permanently stalked; calyx either of tables
(Tesselata), all fossil forms, ex. Cyathocrinus, Poteriocrinus,
&c., or with naked skin between the arms (Articulata). The
surviving genera are :—1. Pentacrinus—with small calyx ; ten
strong, many-pinnulated arms; pillar joints five-lobed, with
appended cirrhi; basals, 5; sub-radials, none; radials, 15 ;
inter-radials, none. There are probably four species known.
2. Holopus—sessile, aproctous; basals, 4 (5, Ag.) ; radials, 4

Introduction to Animal Morphology. 131

(5, Ag.); arms long, close, four (five, Ag.) pair; these, like
the last,are West Indian. 3. Ophiocrinus—with five undivided
arms, sixteen ventral cirrhi, and no other ossicula. 4. Rhizo-
crinus—with a long, jointed column, and long rounded joints ;
calyx variable in its number of pieces ; anus circular, midway
between the mouth and the margin of the disc (North Atlantic).

Comatulide—feather stars; free when mature; stalked
when young; body with immovable dorsal cirrhi of 2-180
joints, representing those of the stem in Pentacrinus ; 10-40
pinnulated arms; anus ventral. They quickly pass through
the early stages of development, when they appear as ovate
bodies with four transverse rows of cilia, a keyhole-shaped
mouth and an anus. ‘The stalked condition has been named
Phytocrinus. The genera are Antedon, the common feather-
star, from which possibly Alecto may be distinct; and Pha-
nogenia, with a simple stelliform centro-dorsal joint, and basal
plates hidden, internal (from Malacca). Allied, are the fossils
Hertha, Pterocoma, &c.

4. Ophiuroidea—brittle stars, with rounded or pentagonal
flattened discs, and elongated arms differentiated from the
body, and containing no viscera. The ambulacral pedicelli
have no ampullz nor sucking discs, and feet are developed
medio-ventrally. Pedicellarize are wanting. There isa cal-
cified peristome of oral plates, grooved for the nerve ring,
and armed with falae angulares, or spurious teeth, based on
five small plates (or? angulares*), one at each of the five
angles of the mouth. The disc may be naked (Ophiomyxa,
Ophioscolex); or covered with fine, hard, equal granules
(Ophiocoma, Ophiarachna) ; or with shields (Ophiomastix) ;
or granules and scales (Ophiothrix) ; or many large, symme-
trical shields (Ophiolepis). The arms are special locomotive
organs, each enclosed in four rows of plates, dorsal, ventral,
and two lateral, within which is an axis of jointed, squarish,
dermal, calcareous plates, separated from the ventral surface
shields by the ambulacral vessel, and above the axis is the
nerve cord. Each plate consists of two ankylosed halves,
and there is a branch of the nerve and water vessel for each
joint of the axis. The first pair of axial segments is large,

* Possibly homologous with the teeth of Echini (?)
K 2

132 Introduction to Animal Morphology.

with halves more separable than in the succeeding joints, and
they are joined to their fellows of the other limbs so as to
form a calcareous ring, enclosing the water-vascular circlet,
whose ten branches to the oral tentacles pierce these plates.
These hollow tentacles are in pairs at each angle of the
mouth, one on each side of the radial water-vessel. The
madreporiform plate is ventral, distinct, or more commonly
covered by one of the oral plates. The stone-canal some-
times contains a free or attached pulpy mass. The Polian
vesicles are four; one, which in Asteriadz is anterior to the
wall with the stone canal, being absent. Between the arms are
genital fissures, through which the products of the inter-
radial sexual glands escape, and the sea-water enters. The
stomach is round or pentagonal, ciliated; the anus absent.
A few are viviparous, and rapidly developed (Ophiolepis,
squamata, and vivipara), but usually there is a free larval stage
(Fig. 19). The ciliated ovum assumes a bilateral form, like a
compressed eight-ribbed umbrella, which has, in each of its
two lateral primary rays, a calcareous spicule (s), at whose base
is a half circle also calcareous ; from these diverge respect-
ively two lower and two upper accessory rays, the latter of
which bifurcate ; thus there are eight diverging calcareous
rods over which the homogeneous protoplasm is spread.
Two little spines lie fore and aft where the calcareous basal
semicircles unite. These spicules are in contact, but not
ankylosed together. A central digestive canal forms (s’), ap-
pearing deep green from its contents; traces of the nerve
cords next appear. The plasma around the stomach forms
two longitudinal lateral folds, which unite as a lamina in front
of the stomach, traversed by the pharynx; then a cup-like
mass forms behind it; these represent respectively the ventral
and dorsal faces of the perisome. The adult rays soon
appear, grow, and become shielded. Then the lobate body
of the larva breaks up, and atrophies, and, together with
the skeleton, is lost, and the adult form is assumed. The
free-swimming, pelagic larva of Ophiolepis ciliata is known
as Pluteus paradoxus, that of O. Sundevallii as P. bimacu-

latus.
They are divisible into two families:—1. Euryalide—

Introduction to Animal Morphology. 133

genital fissures ten, two in each interbrachial space ; arms
not shielded, usually branched; abdominal groove closed by
a soft skin. The genital fissures may be in pits between the
oral shield, as in Asteronyx, which has the large disc and
arms naked; or as in Asteromorpha, which has a granular
disc and arms; or they may not be in pits, and the arms un-
divided and disc granulated (Asteroschema), or deeply annu-
lated (Asteroporpa). ‘The arms may be divided at the tips
only (Trichaster), or branching from the base (Astrophyton)..
In Astrophyton verrucosum, there are over 200,000 joints in
the arm-skeleton, each with two nerve threads and several
muscles.

2. Ophiuride—arms unbranched, shielded; ventral grooves
covered with plates; genital slits usually 5; madreporiform
plate fused with one mouth-shield. This includes about thirty
genera, in nine sub-families. Ophiodermine—mouth-edge
papillose ; oral shields large; tori angulares and disc granu-
lated ; arms arising from notches in the disc; genital fissures
zo (Ophioderma, Ophiocnemis) or 10 (Ophiopeza, Ophia-
rachna). Ophioscolecine—disc naked; mouth-edge papil-
lose ; tooth papille none ; spines smooth, imbedded ; ambula-
cral papillae present (Ophioblenna), or absent (Ophioscolex).
Ophiomyxine—tooth papille present ; mouth edge papillose ;
disc naked ; arms scaly (Ophiarthrum) or naked, the tips only
ofthe rough spines being free (Ophiomyxa). Ophiothricina—
mouth fissure not papillose; disc with multangular spines
(Ophionyx), or with granules, hairs, or spines, and hook-like
spines on the arms (Ophiothrix). Ophiocominze—mouth
slit papillose ; oral shields small, round; disc not notched
for the arms; tooth papillz present; disc granular; arm
spines either constantly visible or seen when the body dries
(Ophiopsila). Ophiacanthinae—like the. last in many re-
spects, with a shielded and granular disc, but with no tooth
papillae; arms with large lateral shields. Ophionereine—
with no tooth papillae; disc with minute shields; arms long,
narrow at origin ; radial shields covered. Amphiurinze—with
naked radial shields, and keeled lateral arm-scales. Ophio-
lepinze—disc symmetrically shielded; tori angulares naked,
not granular; mouth shields large; oral slit papillose. The

134 Introduction to Animal Morphology.

back of the arm insertion (which notches the disc) has a row
of papillz, either medially interrupted (Ophiura), or not
(Ophiocten).

Order 5. Brisingoidea—passage forms, with the disc of
Asteriadz and the arms of Ophiuride ; closely bristled, with
eleven long cylindrical arms, separate from the disc, but con-
taining short, single coeca from the stomach; anus sub-
central ; pedicellariz present ; madreporiform plate marginal,
dorsal; genital glands limited to the middle of the arms,
opening dorsally by two sets of pores. The open ambulacral
grooves, which do not extend to the mouth, have two series
of feet. The one species, Brisinga endecacnemos (Asdjornsen),
is found on the Coast of Norway, as well as in the Southern
Ocean.*

Order 6. Asteroidea—Starfishes having the arms conti-
nuous with the disc, being, in fact, its. prolonged angles.
The dorsal ant-ambulacral surface is covered by a coloured,
leathery membrane, bearing bristles (paxille) and compound
spines, sometimes moved by muscles. The madreporiform
plate is conspicuous, dorsal; sometimes there are several,
and as many stone-canals (five in Echinaster). In Pteraster,
it lies with the anus in the floor of a sub-cutaneous dorsal
pouch. The lower surface of each arm is medially grooved
for the ambulacral feet, which are at least in double rows, and
often bordered by warty papille (papzlle sulcorum). Under
the leathery membrane is a dermal skeleton of many vertebra
or segments, each consisting of several pieces (adambulacral,
intermediate, ventro-marginal, uniting, and dorso-marginal). In
Astropecten, there are over 12,000 pieces ; in Uraster, 11,000.
Each arm possesses a muscular system, consisting of :—
1st. Transverse fibres above and below each segment, joining
together the two lateral halves, which are movable on each
other; not ankylosed, as in Ophiuride. 2nd. Inter-vertebral
longitudinal muscles, smaller than the corresponding set in
Ophiuride. 3rd. Inter-ambulacral,longitudinal. 4th. Trans-
verse bands from the ad-orally expanded sides of the vertebra
to the floor of the ambulacral groove, which they can narrow.

Scattered over the body, or about the mouth, are prehen-

* Possibly the fossils Protaster, Palaeodiscus, &c., may belong here.

Introduction to Animal Morphology. 135

sile organs (fedicellarie). Each consists of a short pillar
supporting two or three movable blades or valves, which are
usually open, but can snap together like a crab’s pincers ;
some have two narrow-pointed (p. forcipata), or two or three
broad, overlapping blades (p. valvata), and they may be
sessile, asin Llwydia. The mouth is central, contractile; the
stomach is a sac with numerous (usually ten) lateral cceca,
each of which is tied to the dorsal surface of the body cavity
by a radial membranous fold, and consists of a stem giving
off 30-50 short, side branches, each ending in 6-8 vesicles
containing a yellow or brown bitter fluid (bile ?); two of
these stretch into each arm. The oral part of the stomach
may become everted as a sucking organ, paralysing its prey
by some secretion. Deslongchamps saw five everted soft
vesicles inverted into the mouth of a Mactra, which was being
devoured. McAndrew saw a similar sac attached to the
hinder end of a Littorina. There is no anus in Astropecten,
Ctenodiscus, or Llwydia; in the others it is central, sub-
central, or to the left of the madreporiform plate in an inter-
brachial pore. In Astropecten there are two non-ciliated
inter-radial cceca opening dorsally into the stomach; these
are absent in Llwydia, five in Archaster, five bifid ones in
Culcita; they are supposed to be hepatic or renal, but
contain neither uric acid nor ammonia. The nerve ring is
broad and flat, and may possess ganglion cells. Each radial
branch is covered by a layer of ganglion cells, and dilates to
the middle of the ambulacral space, being sometimes gutter-
shaped, the demi-canal being completed into a tube by fine
cellular tissue on the dorsal side. At the end of each ambu-
lacral row the nerve often leaves its groove, and gives off one
twig, ending ina gangliform swelling beneath the eye, and
another to an extensile, ciliated feeler (Gree/). The eyes are
near the ends of the rays, and consist of 80-200 small, conical,
stalked pigment granules, with crystal rods(?) surrounded by
gelatinous tissue, lying under a common cornea (?).

The ambulacral system has a thick-walled oral ring,
smooth, ciliated within, and surrounded by circular fibres
externally; the pedicelli are conical in the aproctous, cylin-
drical in the proctuchous forms. Each of the five Polian

136 Introduction to Animal Morphology.

vesicles may be simple or divided into 2-7 smaller vesicles
(A. aurantiacus), whose ducts, however, unite, so that there
are never more than five openings. Right and left of each
vesicle opens one of the ten spherical, hollow, grape-like
bodies appended to the canal (Otocysts of Baur, but more
likely the homologues of the oral tentacles of Ophiuridz).
Respiratory organs may exist on the dorsal surface as rounded
or conical foot-like skin-processes, communicating with the
body cavity (skin gills). In Solaster, the sea-water can enter
the body by inter-brachial cribriform plates, pierced by the
ducts of the genital glands.

The vascular system has its two rings and heart; when
there are several sand canals, there are as many hearts, and the
septum containing the heart is double the size of any of the
other radial mesenteries. The anal ring is wide, pierces all
the septa, and receives a genital vein on each side of each
partition. The oral ring isnarrower, more muscular, and lies
under the nerve, and over the water-vascular ring. Under
each angle of the mouth a vessel passes to each arm, and five
branches are distributed to the stomach. The blood in the
oral ring is yellow-brown, in the anal whitish.

Genital glands, each consisting of one (Ctenodiscus) or
many grape-like masses, lie in pairs on both sides of the
Septa, even to the tip of the arm; in Astropecten these are
numerous, and extend into the disc; in Llwydia, several
thousand glomeruli are scattered along the whole arm. Each
Astropecten may produce half a million eggs. The eggs in
some are developed directly (Echinaster, Asteracanthion
Miilleri; in Pteraster they develop in a dorsal brood sac,
with a narrow neck placed between the paxillated membrane
and the skeleton) ; but more commonly there is a larval stage,
which may be possibly be one of three kinds:—rst. Bipin-
naria—bilaterally symmetrical, skeletonless, flat, smaller at
one end, and with lanceolate lappets along the margin. The
rudimentary water-vascular rosette has swollen Miillerian ap-
pendages, and the stomach is formed in the protoplasm by
invagination (Solaster, Asteracanthion). 2nd. Brachiolaria—
with three warted arms anteriorly. 3rd. A worm-like larva of
four metameroid segments, which, speedily losing its seg-

Introduction to Animal Morphology. 137

mentation, becomes pentagonal. Development proceeds as
in pluteiform larve. In some, reproduction possibly occurs
by fission, thus explaining the occurrence of heteractinism.

The following families are included :—

1. Asteracanthiide—proctuchous ; ambulacra four-rowed ;
pedicellarize stalked, straight, valvate, ex. Asteracanthion, the
common orange starfish. 2. Astropectinidae—ambulacra two-
rowed ; back netted, paxillated; pedicellariz usually sessile ;
anus none, except in Archaster; body pentagonal (Cteno-
discus), or long-armed, with one ventral spine-bearing series
of border plates (Llwydia), or with two (Astropecten, Archaster).
3. Oreastride—ambulacra two-rowed ; skin rough, pierced by
numerous pores, flat on both sides (Astrogonium), or convex dor-
sally, often with large coarse eminences (Oreaster, Asteropsis).
Echinaster has long conical or cylindrical arms, with numerous
pores ; Cribrella, also long-armed, has few pores in the naked
interspaces of the netted skin; Solaster has ten or more
paxillated arms, and many pores; Chaetaster is clothed with
bristles, Ophidiaster with granulated plates. 4. Asterinidz
ambulacra as in last; body discoidal or pyramidal, sharp-
edged; skeleton of imbricate segments; dorsal wart single,
rarely double, ex. Asterina, Palmipes; Culcita is thick, with
a leathery surface; Pteraster has five short thick arms.

CHAPTER XXI.
CLASS 2. ECHINOIDEA (A gassz2).

GLOBULAR, oval, discoid, or heart-shaped forms ;
brown, orange, red, or green in colour; with a peri-
some (corona) of dermal, spine-clad, 4—6-angled, cal-
careous plates, arranged in usually twenty meridional
rows, each of many (5-20) plates passing from pole to
pole. The plates are deposits of calcium carbonate, and
sulphate and a few other salts, in a basis of nucleated

138 Introduction to Animal Morphology.

connective tissue, whose fibres cross and unite at
angles of about 120°-60°-go°._ Usually the interstices
are filled with protoplasm, in which resides the power
of repair after injury. In dried perisomes the organic
matter is about 9 per cent. Theplates may be flexible
(Astropyga), or rigid, and unite either by sutures filled
by an organic cement soluble in alkaline carbonates,
and ankylosing as age advances; or they may be
separated from each other by a soft area (Astheno-
soma). Before uniting, the plates grow as the body
enlarges, by additions to their edges. The rows of
plates are in pairs, five of which are pierced with
holes for the ambulacral feet, and five are inter-ambu-
lacral, each of two rows of imperforate plates. Both
series of plates are beset with tubercles (spine-warts)
for the articulations of the spine, in transverse rows,
and varying in size; for as there are large, medium,
and small spines, so there are primary, secondary, and
miliary warts. The first set have often an apical
depression for the round ligament of the spine, and a
granular “spine-ring’’ around the base, girdled by
smaller warts.

These plates, though apparently simple in the adult, are
compound in most of the regular Echinoidea, and each con-
sists of an ad- and an ab-oral entire plate (stretching from
interambulacrum to the median suture of the ambulacrum),
and one, two, or three intermediate half plates. At first they
are all entire, but the rapid growth of the ab- and ad-oral
plates causes the others to become triangular with the apex
inwards. At first the pore-pairs are in a slightly convex arc
near the margin; but as the test grows, the ad-oral pair are
moved inwards, and downwards, and the ab-oral similarly,
but more slightly, affected. Thus the arcs of pores in the
adult, if counted from below upwards, commence with the
second pair of a plate, and end with the first pair of the

Introduction to Animal Morphology. 139

plate above. As new plates are added at the vertex, pressure
increases downwards, and resistance is afforded by the cal-
careous arches (auricles) to which the jaws are attached, and
which extend over the ambulacral, as well as the interambu-
lacral areas. Thus all the peristomial plates fuse as a solid
ring round the buccal membrane. In Cidaridz alone all the
primary ambulacral plates are entire, and the sutures between
them never become effaced by coalescence, and as the bases
of the auricles are interambulacral, no opposition is offered
to the downward motion of the ambulacral plates, which, being
pushed over the buccal membrane, form a set of overlapping
lamine.

Around the anus is an apical circlet of five pen-
tagonal shields (genital plates (Fig. 20, c), large and
stellate in Astropyga), each pierced by a genital duct ;
with one of these the madreporiform plate is con-
fluent, giving it aswollen, rough appearance. Outside
and between these genital plates are five smaller,
heart-shaped, ocular plates (Fig. 20, 2), each at the end
of the ambulacral radius, and bearing on its surface a
red, cellular, photoscopic eye, with no refracting
media, but with the last twig of the radial nerve end-
ing init. The genital plates are in two pairs in front
and behind, and one posterior azygous plate.

In Spatangide, the place of Fig. 20.
this latter is taken by the madre-
poric plate, which, never sepa-
rated by a suture from the right
anterior genital plate, sometimes
(Meoma, Brissopsis) spreads more
or less over it, or even (Schizaster)
occupies it to such an extent that
both genital pore and gland have _,, pbactinal apparatus of Eehi-
disappeared. Further extension ™tmbulacral plates.
of the madreporic area causes obsolescence of the left

140 Introduction to Animal Morphology.

anterior, or even of this and the right and left posterior
as well (Abatus, Paleeostoma). In Rotula, the madre-
poric plate is fused with all the united genital plates.
Exceptionally it may unite with an ocular. The oral
opening is larger than the apical, and the auricles
project into the cavity around its border to support
the dentary apparatus. In discoidal forms, pillars
and processes along the ambulacra support the surface
of the shell. .

The surface spines are movable, and vary in length
from 24 times the diameter of the corona to a few
lines, and from thick clubbed forms to fine hairs.
They may be smooth, granular, ribbed, or verticillate.
When young, they are covered by cilia, and on section
show concentric lamine of regularly netted, calcified
tissue,* with meshes filled with protoplasm. The
proximal end of each spine has a socket for the spine-
wart. The largest have a round inter-articular liga-
ment from the summit-pit of the wart to the bottom of
the socket. Each spine joint is surrounded by a
capsular ligament from the edge of the socket to the
spine ring, outside which is a layer of longitudinal
muscular fibres (7o¢ores aculet) capable of moving the
spine. These are covered by ciliated epithelium and
pigment cells. These rays are rather support- than
locomotory-organs.

Among the spines in Spatangidz are linear areas covered
with fine, ciliated, clubbed bristles, with a calcareous axis
(semitee or fasciole). ‘These may surround all (s. peripetalz)

* Mackintosh has shown that the pattern of the network is generically
and possibly specifically characteristic. As the spines of some Diadematidze
produce stinging sensations, possibly the protoplasm contains cnidz
(Wright).

Introduction to Animal Morphology. 141

or one of the ambulacral areas (s. internz) ; or may surround
the body equatorially (s. marginales); or may divide the
sides uniting with the marginal semite (s. laterales) ; or may
lie in front of, or around, the anus (s. sub-anales). Around
the mouth is a buccal membrane bearing pedicellariz (modi-
fied spines, Z7oschel), usually with three valves, and having a
calcareous, netted axis in a soft, mucous tissue, and with
simple muscle bundles uniting the branches. These may
be :—1. P. globifere—with a solid stiff axis and a globular
head like a closed three-leafed bud. 2. P. stereophylla—
with a hollow axis and a round, calcareous head. 3. P. tri-
dentes—shorter, with a hollow axis, and serrated arms with
incurved points. 4. P. ophiocephale—with a longer pillar,
and leaf-like limbs.

The ambulacral system consists of a circum-oral
ring, five pedunculated Polian vesicles, cavernous in
structure, with netted, unstriped fibres in the wall on
the membrane over the dental apparatus, and five
ambulacral canals, one between each row of holes,
while proximal processes pass from the ambulacral
canals to the buccal tentacles (Perrier). The tube-
feet may be alike (ambulacra homceopoda), ordissimilar _
(a. heteropoda), and each has at its free end a radially
plaited sucking membrane, under which is a cal-
careous, netted vose¢fe, and sometimes a still deeper,
calcareous vzzg. Arcuated and branched spicules
often abound in the wall of the pedicelli. Heteropodal
forms like Spatangus may have (a) simple feet, with
no rosette; ((3) sucking spiculigerous feet, with an
entire or digitate margin ; (y) sensitive feet with broad
pencil-like ends and flattened knobs, supported on
fine, rod-like styles ; (8) gill-feet with pinnated margin ;
(e) buccal pedicelli with no ring, and a rudimental
rosette. The stone-canal from the madreporiform
plate has its walls stiff with calcareous spicules, but |

142 Introduction to Animal Morphology.

is never contractile. Sometimes the ambulacral radii
extend from one pole to the other (amb. simplicia or
perfecta), or they may be dorsal alone (a. interrupta,
or if arranged in lobate rays, a. petaloidea). The
pores are simple or slit-like (some Clypeastride, &c.)
In Spatangoids, the hinder inter-ambulacral field has
large symmetrically disposed spines (sternum). The
mouth may be polar, eccentric, circular, or valvular,
two-lipped (Spatangidz), and is sometimes surrounded
by a petaloid arrangement of pores (floscellus). The
peristomial membrane may have thick lips and cal-
careous plates(Echinoneus minor). Radial (decurtatores
Jabtorum) and circular muscular fibres are present in the
lips. Teeth may be present, rudimentary (Galerites),
or none (Spatangidz, Echinoneus, Cassidulina). The
peristomial edge of the corona is often notched for the
gills when they exist.

The anus is round or oval, and may be polar ina
granular plate (periproct, the morphological equiva-
lent of the whole dorsal surface of Asterias) in the
centre of the genital circlet. When eccentric, it may
open on the vertical side of the perisome (Aleurocysia),
or on the ventral side (cafacysfa), near the mouth,
midway between it and the margin, or at the margin
(Echinarachnius).

The dental apparatus is conical, with its narrow end
directed outwards, and its base inwards, and it can easily be
examined in the common sea urchin; it is suspended by
muscles and ligaments to the auricles, and consists of five
wedge-shaped jaws arranged around the pharynx. The flat
sides of each jaw are transversely striated and opposed to
each other. Each jaw consists of two segments united by
suture. These diverge at the base, and are separated by an
interspace, arched over by an zter-radial arch (Erganzung-

Introduction to Animal Morphology. 143

stiicke, JZever), each made of two segments (Epiphyses),
uniting by a median suture. Between each jaw and its neigh-
bour, along the base of the pyramid, lie flat radial pieces
(rotula, Schaltstiicke, J/eyer), forming a fixed basis for the
separate motions ofthe jaws. Parallel to,and deeper then these,
are five radial, Y-shaped manubria (Gabel- or Biigelstiicke)
attached within to the middle notch at the central end of the
radial pieces, externally projecting freely by their forked ends
between the jaws; each of these is also double, consisting of
an inner and outer segment, united by a suture. In the axis
of each jaw, between its segments, is a long, curved tooth,
whose tip projects as a hard, enamel-coated, chisel-like point,
and the basal end is fibrous, asbestos-like. ‘There are thus
forty segments in this “lantern ;” five teeth; five jaws, each
of two segments ; five radials; five inter-radials, each of two
pieces; and five manubria, each likewise double. The
muscles to move the apparatus are:—1. Five intermaxillary,
transverse fibres to approximate the jaws from the opposed
surfaces of each jaw to its neighbours (Jzterpyramidales).
2. Five intermanubrial clear bands, forming a pentagon on
the base of the jaws, forapproximating the manubria. 3. Five
pair of dilatatores orificit dentium, which can also retract the
whole apparatus, arising two from each auricle, and attached
to lateral grooves at the apex of the jaws. 4. Comminutores
ciborum, also five pairs arising from the interambulacral
margin, and passing upwards and inwards, narrowing to the
inter-radial arches. A fine muscle is described by Valentin
at the base of each tooth, but I have not found it. From
each inter-ambulacral space to the outer end of each manu-
brial fork stretches an oblique ligament, which has a few
smooth muscular fibres in its origin: besides these ligamenta
externa obliqua, there are ligamenta externa recta, thin
vertical membranes from the auricles to the inner end of the
manubrium. ‘The dental apparatus in Cidaridz differs from
that of Echinus, above described, as the epiphyses do not
unite mesially to form inter-radial arches, but are ankylosed

to the radial pieces. In Laganum the jaws are unsymme-
trical.

The pharynx is pentagonal, narrowing to the

144 L[ntroduction to Animal Morphology.

cesophagus, supported by five tendons attached to the
radial pieces, and has a muscular coat. There are
small glandular ceca along the cesophageal wall.
The intestine is long, once or twice coiled within the
somatic cavity, and held in its place by fenestrated
mesenteries from the wall of the ciliated perivisceral
cavity. Caca are present in some Clypeastride,
projecting between the pillars of the shell. The end
of the intestine (rectum) has firmer mesenteries than
the middle. The intestinal wall consists of an outer
serous ciliated layer, a middle muscular, and an inner
also ciliated with a layer of brown or yellow (hepatic ?)
cells.

The heart* is fusiform, in a common sheath with
the stone-canal, having an outer ciliated, a middle
spiral or reticular muscular (thick in Cidaris), and an
inner tessellated epithelial layer. The circum-oral
ring into which the heart opens sends radial vessels.
to the muscles of the jaws and to ove side of the intes-
tinal wall. Along the opposite side of the intestine
there is a second vessel, the intestinal vein, receiving
the blood from the wall of the intestine, and the chyle
from the digested food. This vessel breaks up, as it
approaches the perisome wall, into branches which
ramify on the wall, where their contents become
aerated. From hence the dark yellow blood is re-
turned by fine branchial vessels to the circum-anal
ring from which the heart arises. The heart current

* Perrier describes the heart as a gland, and denies the existence of
any other ring but the water-vascular one. He describes the passage of a
vessel from opposite the right anterior Polian sac to the intestine joining
the intestinal vein, thus uniting the ambulacral and circulatory systems, a
connexion also described as existing in Spatangus and Toxopneustes by

‘ Hoffman.

Introduction to Animal Morphology. 145

moves from anal to oral ring, and no part of the lining
of this system is ciliated.

Respiration is thus superficial, but in some there
are five peristomial, branched gills, with hollow stems
communicating with the body cavity, into which they
may admit the sea water; they are ciliated within
and without, extra vascular, and sometimes spiculi-
gerous.

The violet or green circum-oral nerve ring is close
to the teeth, covered with ganglion cells: it is irre-
gular in Spatangoids ; in the others, it sends through
each auricular loop an ambulacral nerve, or pair of
nerves, which runs between the two series of ambu-
lacra, and ends in the ocellus.* Two lateral threads
pass to the intestine, and several to the jaw muscles.
The ambulacral nerves thicken to the centre of their
course. The sphaeridia of Lovén, which may be
counted as sense organs, are globular or button-like
bodies on stalks, placed along the ambulacral line and
on the peristomial plates. They are absent in Cida-
ride, sunk in dome-like hollows in Clypeastride.t

The genital glands lie one in each inter-ambulacrum.
The testes are white, the ovaries reddish or yellow,
both lanceolate and plicated: they are four, and un-
symmetrical in most of the eccentric forms. The
ducts traverse the pores of the genital plates, and the
products are slowly emptied. The eggs are small,
10-12 in each grape-like bundle of the ovary. Half-
an-hour after impregnation, yelk rotation begins; in
3-4 hours fission occurs ; and in eight hours each egg is

* The spines round the ocellus are called “ eyelids.”
t There may be one or two spheridia in each peristomial plate. They
move slowly in Brissopsis.

L

146 Introduction to Animal Morphology.

mulberry-like, while cilia appear in twelve hours.
The larva is apple-shaped in three days, then be-
comes pyramidal, developing simple, calcareous rods
within, and ciliated ‘“epaulettes” on the surface
(except in Spatangus, in which also the calcareous
rods are fenestrated). The water-vascular rosette is
developed as usual in the eight-armed larva, which
soon begins to break up; its hinder end becomes
absorbed, and the first trace of spines and pedicelli
soon appear. Finally the larval skeleton is lost, and
the adult form assumed.

Anochanus Sinensis is an aberrant form with
spines, ambulacra, and pedicellarie, but no genital
glands, nor pores. It has an apical sac, in which are
several young echinids in various stages of growth;
possibly a case of metagenesis (Grade), or a concealed
form of fission, or most probably a simple case of
vivipareity.

They are divisible into two orders :—

1. Tessellata.—Palaeozoic—s-—6 series of plates, some of
which are hexagonal, in each inter-ambulacral space ; mouth
central, with a masticatory apparatus; spine-warts weak ;
anus dorsal; ambulacral plates may be in more than two-
rows (Melonites), or two-rowed with imperforate spine-warts
(Palechinus), or perforate; possibly passage forms to the
Cystidee.

2. Euechinoidea—with two sets of ambulacral and two of
inter-ambulacral plates alternating with each other. This
order includes two sub-orders:—1. Endocyclica or Regu-
laria—with central, or sub-central, round or 5-10 angled
mouth, with five equal ambulacral fields. This includes six
families :—1. Cidaride—with perforate, smooth tubercles
(spine-warts) ; no peristomial notches in the corona, nor per-
forated tubercles on the narrow ambulacral plates. The peri-
stomial membrane has scales and ambulacral feet. ‘There are

Introduction to Animal Morphology. 147

no circum-oral gills, and the spines are large and clavate;
anal plates ten. 2. Salenide—extinct, (except S. rari-
spina), jurassic and cretaceous forms with eleven anal plates.
3. Diadematide—perforated, crenulated tubercles; spines
usually hollow; the ambulacral area with perforate tubercles ;
peristome with notches. 4. Arbaciidee—tubercles smooth,
imperforate ; no sutural pores ; periproct closed by four plates.
5. Echinida—spine-warts and sutural pores as last ; periproct
of many plates ; body circular or pentagonal; pores in three
orfourpairson each plate; including Temnopleurine, with oral
notches shallow, and no ocular plate reaching the periproct ;
and Triplechinidz, with two ocular plates reaching the peri-
proct, and the oral notches deeper than broad. 6. Echino-
metridze—pores in five or six pairs ; body elliptical ; including
Heterocentrotus, with club-like spines ; Colobocentrotus, with
the dorsum of the test covered with pavement-like spines, &c.

Sub-order 2. Exocyclica—the anus notin the centre of
the apical apparatus: there are five families:—1. Galeri-
tide—genital pores four; ambulacra ending in an apical
point; including the toothless Echinoneus. 2. Dysasteridae—
Mesozoic, with the ambulacra converging to two apical
points; three anteriorly forming a trivium; with three
ocular and four genital plates, two posteriorly (bivium), with
two ocular and no genital plate. 3. Clypeastride—ambulacra
petaloid, often not distinct towards the margin; mouth
central, with teeth; anus inferior; spine-warts notched and
perforate ; shell wall with duplicatures, pillars, and chambers ;
madreporiform plate central; the shell may be inflated
and the jaws moveable on the auricles (Clypeastrine), or
fastened thereto, and the shell flat (Laganine); the shell
may be lobed, or pierced by large holes, and the am-
bulacral rows branched (Melittine). 4. Cassidulinide—
mostly cretaceous and eocene; toothless, with petaloid
ambulacra, imperforate and entire spine-warts; genital pores
five; anus posterior or inferior. 5. Spatangida—heart-
shaped, toothless, with an anterior reniform mouth, and inter-
rupted ambulacra; bivium embracing a sternal field; semite
may be entopetalar and sub-anal, not peripetalous (Echino-
cardium, Lovénia), or with a peripetalous area (Breynia) ;

E2

148 Introduction to Animal Morphology.

entopetalous, peripetalous, and lateral semitz wanting (Hemi-
patagus, without, and Spatangus with a closed anal semita).
The peripetalous may be present with (Agassizia, Schizaster,
&c.) or without a lateral semita (Brissus). In Leskea, the
mouth resembles that of a Cystidean.

CHAPTER. 2x18.
CLASS 3. HOLOTHURIDA.

SEA cucumbers, dark brown to purple-red, varying
from $”—10” long. Shell-less, elongated Echinoderms,
with an epidermis not divided into cell-areas, and a
dermis with many calcareous, specifically characteristic
spicules ; sometimes forming a scaly layer (Actinopyga
squamata, Cuvieria) ; rarely absent (Thyonidium, &c.)
Beneath this is an elastic connective layer, and a
lamina of circular, muscular fibres imbedded in proto-
plasm, and forming a continuous sac; some of these
fibres are continued into the mesenteries. Five deeper
meridional bands of longitudinal fibres extend from
mouth to anus, sending fibres into the tentacles.
These may, on irritation, act so forcibly as to expel
the viscera through the orifices, or to rupture the
surface. Within these there are often calcareous scales
and a ciliated lining.

The mouth is polar, toothless, surrounded by 10-20
plumose, simple or tasseled, prehensile, ciliated, sen-
sitive tentacles (altered ambulacra); these may be
equal or unequal, sometimes margined with little
suckers (Synapta digitata and inherens). The bases
of these contain ceecal branches of the water-vascular

Introduction to Animal Morphology. 149

system. The anus has around or pentagonal muscular
sphincter, into whose edges the longitudinal body
muscles are inserted. The pharynx is oval and
glandular, separated from the stomach by a sphincter,
surrounded at its origin by a moveable ring of 10, 12, or
15 plates, five of which are usually notched or pierced
(Synapta), vadzal, and five are zufer-radial ; these re-
present the auricles of Echini. Five muscular bands
unite these plates, and 10-12 pyramidal bands arise
by their apices therefrom, and have their broad bases
inserted into the pharyngeal wall: they can draw
forwards the pharynx. The digestive canal is straight
or curved, attached by often uninterrupted mesenteries.
It sometimes ends in a cloaca directly above the anus.
In the intestine there may be 2-4 longitudinal folds,
possibly the extension of an absorbing apparatus.
The alimentary canal contains diatoms, foraminifers,
and sand.

The dermis acts as a respiratory organ, so do the
remarkable tree-like, long branching organs, ciliated
within and without, which arise from the cloaca, and
stretch in the body cavity towards the mouth. Water
enters them from the cloaca, and passes into the body
cavity from them by holes in the tips of the branches.
These water-lungs are homologous to the inter-radial
ceca of Asteriade. Water enters in other forms by
inter-tentacular pores. The tree-like organs vary in
size; in some forms they are joined to the wall of the
somatic cavity by threads, and even where the trees
are absent (Synapta), these threads remain appended
to the mesenteries with attached to their inner ends
ciliated, slipper-like, or cornucopiz-like organs, and
communicating with the pseud-hemal system. Rarely

150 Lntroduction to Animal Morphology.

are the trees singly branched (Echinocucumis). The
pseud-heemal ring sends off two pulsating vessels along
the intestinal canal, dorsal and ventral, connected
by reticular vessels; branches pass from one of these
to the right water-lung, and in Aspidochirote a plexus
of branches of the dorsal vessel is related to the left
respiratory tree. The ventral vessel in Chirodota dis-
plays numerous varicosities. The yellow or brown
blood is coagulable, and contains colourless corpuscles
and amzeboid mucous cells.

The intestine is lined by yellow cells, secreting a bitter
fluid (bile ?). Solid fibres or thread-like tubes open into the
cloaca (Cuvierian organs). They may be as long as the re-
spiratory tree, and cecal (30, Bohadschia), or small (Holo-
thuria), filiform, grape-like, and very numerous; or bundles
of spindle-shaped sacs (Miilleria, Pentacta), filled with fine
vesicles. They are absent in Apneumona, &c. The body
surface often secretes slime from its dermal follicles. The
nerve-ring is often red, thicker than the radial branches, and
lies in front of the calcareous plates and water-vascular ring ;
it sends off tentacular and ambulacral nerves, the latter some-
times trifid, through holes in the radial plates. Inter-tenta-
cular pigment flecks in Synapta are described as ocelli, but
no nerves have been traced satisfactorily into them. Synapta
Beselii has small vesicles placed around the mouth where the
radial nerves pass through the holes in the oral plates,
possibly otocysts. The spicules in the tentacles usually differ
from those of the body.

The ambulacral oral circle may have 1-100 (Cla-
dolabes) Polian vesicles. The stone-canal is short,
usually single, but may be multiple (Synapta serpen-
tina), or branched (S. Beselii). It hangs free from the
body cavity,.often holding a wide, calcareous, spiculi-
gerous sac with a sieve-like wall at its end, represent-
ing the madreporiform plate. This canal has often a

Introduction to Animal Morphology. 151

stiff, inflexible wall, composed of an outer and inner
porous, and a middle spiculigerous membrane, and
the cavity may be labyrinthine. In the Dipneumona,
five branches pass to the calcareous ring, on the inner
side of which they divide into branches to each ambu-
lacral foot and tentacle. The pedicelli are conical,
without, or cylindrical, with a sucking disc, sometimes
irregularly scattered (sporadipoda), or in 2-5 rows
(stichopoda), making a discriminable dorsal (bivial)
and ventral (trivial) surface. The abdominal feet may
differ from the dorsal (heteropoda tristicha); rarely
the bivial fail altogether, and the ventral are limited
to a few series on the abdomen (Psolus). The pedicelli
have rudimental rosette plates; some non-retractile
feet have calcareous supports in their side walls.
Progression is by creeping; the actinoid Minyas
walks on its tentacles, and some Synapte can swim.
Except in Synapta and Molpadia, the sexes are
separate, as in the other Echinoderms. The sex-
organs are not radial, but single ramose, attached to
one or both sides of the dorsal mesentery. There is a
common duct opening dorsally beneath the mouth.
Only when the products are ripe can the testis and
ovary be distinguished from one another. The zoo-
sperms are pin-shaped ; the ovum has a firm, radially-
striated envelope, with a micropyle; Synapta vivipara
is viviparous ; Holothuria tremula develops directly ;
the others mostly undergo metamorphoses. From the
egg escapes a bilaterally symmetrical planula, which
develops an anus and a digestive canal. The cilia
limit themselves to two girdles, and the form is then
called Auricularia, with short sac-like processes, some-
times spicules, but no calcareous skeleton. Inmoving,

152 Introduction to Animal Morphology.

this rotates on its long axis, and soon develops a
mouth, stomach, and anus, and Miillerian swellings,
aswell as a calcigerous gland posteriorly. This body
then becomes barrel-shaped, opaque; its mouth dis-
appears, and it becomes a “‘Pupa;” draws in its side
lobes ; the stone-canal sinks into the body, the cilia
disappear, the tentacles and mouth form, and the
animal assumes its mature shape. The power of re-
producing lost parts is great.

As commensal entozoa in Holothurids have been
found fishes (Fierasfer), crustacea (Pinnotheres), and
gasteropods {Entoconcha mirabilis, whose eggs and
embryos have been found in the ovaries of Holo-
thuria), Helicosepina, a shell-less gasteropod, has
been found in Synapta digitata. Eulima, Montacuta,
and Stylifer, are found outside or inside Echinoids,
Starfishes, or Holothurids.

The class is divided into three orders, containing about
270 species.

1. Apneumona (#rand‘)—with no tree-like water-lungs
nor Cuvierian organs; anus and mouth polar; ambulacral
canals 5; hermaphrodite. ‘Two families are included :—
1, Synaptida—footless; in Synapta the skin bristles with
anchor-like spicules, and millet-seed plates in the intervals,
especially along the muscle-bands. Some species (S. in-
hzrens) have true nettle-cells; others in which these cells
have not yet been demonstrated, have a stinging power.
Anapta has no anchors, but biscuit-shaped spines. Chirodota
has calcareous wheels, with 6-16 spokes, which may be
mounted on an axis (Myriotrochus). Eupyrgus has conical
perforated plates and fifteen undivided tentacles. 2. Oncino-
labide—ambulacra present ; tentacles thread-like ; skin with
barbed spicules. Echinosoma has no ampulla to the ten-
tacles ; no feet, and rudimentary gills. :

2. Tetrapneumona (Schmarda)—with four gill-czca at the
end of the intestine; mouth and anus at the same end, each

Introduction to Animal Morphology. 153

surrounded by a ring of ten plates, and both at the narrow
end of a flask-like body; ambulacral canals in five double
rows, each with two sets of little feet and two Polian vesicles ;
tentacles 10; the single sex-opening is at the top of the
neck. This includes one species Rhopalodina lageniformis
from Congo.

3. Dipneumona, Pneumonophora (Brand?) have two tree-
like water-lungs and Cuvierian organs; the mouth and anus
are polar, and the ambulacral rows are never double. This
includes three families :—1. Liodermatide—footless, with
twelve shield-like tentacles (Liosoma), or ten single cylin-
drical (Haplodactylus) or branched tentacles (Molpadia). In
this genus, the cecal sacs of the water-vascular system end
in the skin, but are not prolonged into pedicelli. 2. Dendro-
chirote—tentacles branched, unequal; they may be sporadi-
podous, homcepodal, with ten(Thyone), twelve (Phyllophorus),
or fifteen retractile tentacles (Orcula); rarely stiff (Sclero-
dactyla) or heteropodal, with twenty tentacles (Cladolabes) ;
or the feet may be stichopodous in five rows, with twenty
(Thyonidium) or ten tentacles. The feet in each row are
uniserial, retractile (Ochnus), or non-retractile (Perlinus) ; or
they may be in 2-6 series with equal (Cladodactylus) or
unequal (Dactylota); or they may be tristichous (Psolus,
Cuvieria). 3. Aspidochirote—tentacles shield-like ; Cuvierian
organ cecal, well developed ; feet pentastichous (Aspidochir)
or heteropodal ; those of the trivium suctorial at the end;
those of the bivium conical (Stichopus), or sporadipodal,
homceopodal (Sporadipus), or heteropodal ; abdomen swollen,
as in Trepang (the edible Chinese form), or flat, with a round
(Holothuria), five-angled, toothless (Bohadschia), or five-
toothed anus (Actinopyga).

154 Introduction to Animal Morphology.

CHAPTER’ XXII.
SUB-KINGDOM 5.—VERMES. |

BILATERALLY symmetrical, usually soft, elongate,
often parasitic animals, of one or many metameres ;.
with differentiated dorsal and ventral surfaces, but
never with jointed limbs. The nervous system gene-
rally consists of one or two pharyngeal ganglia, and
sometimes an abdominal nerve-cord. Sense-organs
are rarely complex. Sexual reproduction occurs in
every species ; metagenesis is common, but fission or
gemmation is rare. The ova are holoblastic, and the
embryo has rarely a primitive streak (except in
leeches). The epidermis may be cellular or proto-
plasmic, ciliated at first, but the cilia are in general
early shed, and a deeper layer exposed, with bristles,
hooks, scales, &c. The dermis is fibrous or connective.
The subjacent muscular layer is either united to the
body parenchyma, or separated from the viscera by a
body cavity. There isatubular water-vascular system
opening externally, and often also into the body
cavity ; this may be excretory, as Lzeberkuhn found
guanin in its contents, but it is never connected with
locomotion. The mouth is at the end foremost in
progression, which may be specialized as a head.
The anus is farther back, or none. The higher forms
have a closed vascular system, but no pulsating sacs.

This polymorphic sub-kingdom may be divided
into two provinces, including thirteen classes.*

* Some unite Turbellaria, Cotylide, Nematelmia, and Acanthocephala

under the name Scolecida. Gephyrea has been joined to Echinodermata,
to Scolecida, or Annelida. Hirudinea has been placed beside or under

Introduction to Animal Morphology. 155

PROVINCE 1. ARCHAZOSTOMATA* (Huxley).

CLASS 1. TURBELLARIA (L£/renberg).—Unjointed,
rarely parasitic, ciliated, leaf- or ribbon-like worms,
rarely with chitinous processes or bristles (not arising
_ in follicles), or circlets of stronger cilia (Dinophilus).
The integument consists of cells or of undivided pro-
toplasm, containing, in the aquatic forms, nettle-cells
scattered or clustered ; sometimes rod- or spindle-like
bodies, with (Meckelia) or without appended threads
may exist in capsules, like those of the true nettle-
cells (absent in Geoplana, Schul¢zc).

The integument may also contain chlorophyll (Vortex
viridis, Convoluta Schultzii) or calcareous concretions (Sidonia
elegans). The component plastides are best seen in land
planarians, where the glandular elements are divided into
superficial and deep. The sub-cutaneous muscular layer
consists of usually three laminz, an outer circular, well marked
in Bipalium and Dendroccelum, often undifferentiated in
others, a middle, longitudinal (the strongest), and an inner
circular. The fibres in most are but spindle-cells loosely
scattered in a net-work of connective tissue (except in Ne-
mertinea).

Cotylidze, or united to Chzetopoda to form a group Annelida. Rotatoria
is placed by many among the Arthropods near Crustacea. Bryozoa and
Tunicata are usually and naturally united to Brachiopoda to form a sub-
division Molluscoida, but as the Mollusca proper are only an extreme of
specialization of this sub-division of Vermes, it would be still more natural
to add them all together in the one sub-kingdom. However, as for con-
venience we retain the specialized group separately, it is to a large extent
arbitrary where the line of demarcation is drawn ; so, though many eminent
zoologists, as Lankester, prefer to retain the Tunicates, &c., with the
Molluscoids, I have followed Gegenbaur in my classification.

* These characters (p. 47), being primary embryonic ones, should over-
ride the sub-kingdom characters here adopted ; but in the present condition
of our knowledge, we can scarcely apply them to all the included forms.

t Among Nemerteans, these vary in their arrangement.

156 Introduction to Animal Morphology.

The persistent embryonic mouth (homologous with
the anus of some higher forms) is either anterior or
abdominal, surrounded by radiating and sometimes
circular muscle-fibres, and may be trumpet-like,
plicated in some landforms. The part of the body in
front of it isthe pvostomzum. The pharynxis muscular
(except in Schizostomum), and may be protrusible,
with one-celled glands opening therein (Vortex, De-
rostomum), or with 2-3-celled (salivary) glands in
some Rhabdoccela. Short, retractile, marginal, or
dorsal tentacles may project ‘(Proceros, Stylochus,
&c.), or the skin of the front of the body may be
lengthened and crumpled as. pseudo-tentacule. In
Nemertinea, a special proboscis exists in front of the
mouth, an eversible muscular sac (Fig. 21,5) sometimes
as long as the body, or longer ; when retracted, it lies,
convoluted, in a sheath or short sac, surrounded by-a
corpuscular fluid, under the dorsal integument and
over the intestine; when protruded (by. the action of
the circular fibres in its wall), its apex is, in Nemertinea
enopla, armed with a strong spine, often surrounded by
smaller ones; a saccular poison gland (c), placed near
the end of the cavity of the protruded. proboscis, opens
by a duct at the base of the chief spine; a retractor
muscle arising from the body-wall traverses the axis
of the proboscis to its tip, and can draw it in. Some
Nemerteans (N. anopla) have no spines.

The stomach may be a simple pouch ehapaoaiea
with (Microstomide, Nemertinea) or without an anus,’
or it may give off branching, coloured ceca, or the
tube may begin to branch at the pharynx; in these
cases it is aproctous (Dendroccela). Some Nemerteans
have a body cavity around the stomach (which is held

Introduction to Animal Morphology. 157

in place by thread-like, muscular mesenteries) ; but in
most, the digestive cavity is an excavation in the
body parenchyma, lined by epithelium, and without
or with (Geoplana), a muscular coat for its chief
branches. The whole digestive tract is ciliated in
Nemerteans.

, The simplest forms have no circulatory system.
Nemerteans possess two lateral, pulsating vessels,
which dilate as they pass backwards, and _ Fig. 21.
unite in front. Each of these sends a
branch round the front of the nerve gan-
glion, which unites with its fellow to form a
third medio-dorsal tube. These may give 2:
off no branches (Tetrastemma), or may be Jmk 7
joined by transverse canals (indicating a 4{#
hidden metameric structure?). The blood
is white or reddish. There are no respira-
tory organs.* The water-vascular system
exists as two long, ciliated, often branched,
separate or connected lateral tubes, reticu-
lated within, opening by a posterior termi- %,«

nal, or by a lateral pore, rarely into the ines

mouth (Enterostomum Fingalianum, and Hated ee
Mesostomum). — of" proboscis ¢
> a £, astric
Therearetwo, oftenreddish, bi-lobed nerve Hands:«, eso.

> b |
phagus;z,intes-

ganglia,oneateachsideofthe pharynx, rarely tine; oz, ovary.
far apart (Valencinia); united by a commissure above
that tube. From this two lateral nerves pass backward
(weakin Dendroccela, strongerin Rhabdoccela), extend-
ing the whole length of the body in Nemertinea, and
in the larva of Prosorhochmus, each ending behind ina

* The arches beside the pharynx form in Lineus a rete mirabile, from
which it is only a step to the branchial organ of Balanoglossus.

158 Introduction to Animal Morphology.

gangliform swelling. In many Dendroccelans, the
feeble nervous system has no detectible ganglion cells,
and lies within the primitive vascular canals (water-
vascular system). Reddish or black photoscopic eyes
exist in many, either few on the neck or many mar-
ginal and clustered; refracting bodies are added in
Vortex, Mesostomum, &c., and rod-like processes in
Geodesmus. In eyeless Rhabdoccela, and a few
Nemerteans, there is sometimes, close to the ganglion,
a single clear ear-vesicle ciliated within, containing
a spherical otolith. This rarely co-exists with ocelli
(Erstedtia pallida, Monocelis anguilla).

Rod-like bodies lying on the ganglion in a few forms
may be touch-organs. In Nemerteans, there is on each side of
the front end of the body one or twociliated grooves (Fig. 21, ¢),
which may be shallow, conical, or with margins capable of
closure, on whose floor is a ganglion clothed by ciliated pro-
toplasm. The roots of these ganglia arise from the side
(Nemertes), back (Cerebratulus), or front (Polia humilis) of
the pharyngeal nerve centre, or from the lateral nerve cords
(P. bembix). These are regarded as smell-, taste-, or touch-
organs, or as the mouths of excretory ducts (?) (Van Beneden).
Traces of similar grooves exist in Microstomidz, Polygordius,
&c. They are absent in Cephalothrix, &c. In Carinella
annulata, a frill exists representing the upper lip of the
cephalic fissure. At the ends of the grooves are two lateral
sacs, with a funnel-like ciliated duct. The sac wall has a
streak of finely granular ciliated cells. In Bipalium, the head
possesses rows of papillz and ciliated pits.

Reproduction occurs rarely by transverse fission
(Microstomum), freely by artificial division, by conti-
nuous gemmation producing a tape-worm-like form
(Derostomum catenula), but commonly by ova. Most
are hermaphrodite, often self-impregnating, with a
common (most Rhabdoceela) or separate sex-openings

Introduction to Animal Morphology. 159

(Dendroceela). The female organs consist of—tst, a
germ-gland secreting the central part of the egg;
2nd, one or two yelk-glands secreting a cellular ma-
terial, not homologous with true yelk, which contri-
butes chiefly to the formation of the embryo. These
may open separately or in common into the oviduct,
which is at one part dilated into a uterus, where the
eggs accumulate and begin to develop. To this is
added a shell-secreting gland and an external duct or
vagina, often with a dilatation for the reception of the
semen (spermatheca). The male organs in Rhabdo-
ccela consist of a pair of pouch-like testes, with ducts
opening in seminal vesicles, and ending in a perforate
cirrus or penis, armed with recurved hooks, and,
when retracted, contained inasac. In Dendroccela,
many vesicular testes exist scattered through the
body, sometimes in pairs (Bipalium). In Convoluta,
some individuals have developed male and rudimental
female organs, and others the reverse, leading us to
the dicecious forms (Microstomide, Acmostomum
dioicum, Nemertinea, Planaria dioica). The sex-
organs of Nemerteans are simple follicles between the
intestinal ceca, opening laterally by pores above the
lateral nerves. The spermatozoa are rod-like. The
ova are rapidly developed ; sometimes several embryos
arise from one egg. In some cases (Borlasia), the
stomach cavity appears to form! by invagination
(Hubrecht). In other Nemerteans, the;embryo forms
as a vesicle of one layer (blastula), which becomes
ciliated, free, and then by invagination becomes a
gastrula.* In Nemertinea, the soft-shelled eggs are

* The blastula stage precedes the perfect triploblastic planula stage in

Ascidians, Amphioxus, &c., as well as in Nemerteans (Salensky). Knappers
describes Planaria as a true diblastula.

160 Introduction to Animal Morphology.

imbedded in slime, and early develop a helmet-like
larva (pilidium), with an apical flagellum, ciliated
sides, and a simple, inferior, alimentary canal. The
history of this is comparable with that of the Echino-
dermal pluteus, as only the digestive canal and the
blastema around it develop into the perfect form ;
the rest is only provisional. Some larve shed only

their ciliated skin.

This class contains the following orders :—

1. Dendroceela (Zhrenberg).—Digestive cavity tree-like,
aproctous ; pharynx protrusible ; body broad and flat; sex-
openings double; mostly marine; a few freshwater and land
forms. This contains two sub-orders :—1. Acephala—deve-
lopment often with metamorphosis; anterior end not spe-
cialized into a head ;. including four families :—1. Aceridae—
with no tentacles; eyeless (Polycladus, Typhlolepta), or with
2 (Dicelis), 3 (Tricelis), 4 (Tetracelis), or many eyes (Poly-
celis,* Leptoplana), in which the two vasa differentia are
united by a common duct. 2. Pseudoceride—with pseudo-
tentacule; the back is. smooth (Eurylepta) or papillose
(Thysanozoon); the latter has a double penis. 3. Prosthe-
ceridze—tentacles true, anterior; the pharynx is entire {Pros-
theceraeus, Homaloceraeus, Schmardea), or divided along its
protrusible margin (Phagocata).. 4. Notoceride—tentacles,
on back of neck; eyes none (Planacera), or at the base
(Stylochus), or at the point of the tentacles (Imogene).
Trachyplana has hyaline tentacles.

Sub-order 2. Cephalota—prostomium differentiated ; deve-
lopment without metamorphosis, including two families.
5. Carenota—head distinct, hammer-like (Bipalium, a land
form from Ceylon and India), four (Cephalocarena), or three-
sided (Goniocarena), with two tentacles (Carenoceraeus).
Polycladus is eyeless. 6. Planariidae—head not very distinct
nor tentaculate, often with processes ; mouth medio-ventral.
Planaria has two eyes; Anocelis has none; Dendroccelum has

* These genera have simple development.

Introduction to Animal Morphology. 161

auricular processes on the head; Rhynchodesmus and Geo-
desmus are terrestrial; Procotyla has a cephalic, and Bdel-
lura a caudal sucking disc.

Order z. Rhabdoccela.—Intestine a simple pouch ; pharynx
not protrusible in some; usually one sex-opening ; testes
pouch-like; many are freshwater, others marine. This
order includes five families :—1. Microstomidze—proctuchous ;
mouth small, round, terminal in Proporus (eyes none), and
Disorus (eyes six), sub-terminal in Vorticerus ; it is slit-like,
sub-terminal in Microstomum, terminal in Schizoprora.
2. Pharyngeide—pharynx protrusible, somewhat urceolate,
cylindrical, or conical; mouth terminal (Acmostomum), or
sub-terminal (Vortex) ; it may be a transverse (Stenostomum),
or a longitudinal slit (Derostomum) ; or central, with a cylin-
drical (Mesopharynx), or funnel-shaped pharynx (Chonosto-
mum), or post-central, with one (Monocelis), two (Diotis),
or no otolith (Opistomum). 3. Apharyngeide—pharynx
not protrusible; mouth circular, sub-terminal (Strongoylsto-
mum), or medio-ventral; eyes two (Mesostomum), or none
(Typhloplana); or the mouth may be slit-like, transverse,
behind the otolith (Convoluta), or longitudinal, terminal
(Telostomum), or sub-terminal ; eyes two (Macrostomum).*
4. Rhynchoprobolide—having a terminal proboscis, and a
sub-terminal (Prostomum), or central, round mouth (Rhyncho-
probolus). 5. Catenulide—several individuals united in a
longitudinal stock by continuous budding; head distinct ;
European and South African forms. 6. Dinophilida—form
alink to the next order, as they have a body cavity in which
lies the proctuchous stomach. ‘They also have a number of
girdles of long cilia.

Order 3. Nemertidea (@7sted, Rhynchoceela, Schultze)—
long, worm-like, mostly marine, proctuchous, dicecious,t}
proboscis-bearingt Turbellarians, with contractile, brittle,
sometimes transversely striped bodies (rudimental annula-
tion), and numerous dermal muciparous glands, with some-
times a fourth muscular lamina (of internal longitudinal fibres,

* Yelk and germ-glands united; separate in Orthostomum.
f Except Borlasia hermaphroditica.
} Proboscis small in Prorhynchus and in Polia involuta.

M

162 Introduction to Animal Morphology.

Cerebratulus). The large nerve ganglia are joined by a
double commissure, and the lateral cords are thick. The
eyes are seldom lens-bearing (Polia coronata, Nemertes
Antonina, Tetrastemma); sometimes two long series of pig-
ment specks and nerves exist, as in Borlasiasplendens. There
is usually a closed perivisceral cavity, except in the few fresh-
water forms. A separate circulatory system exists, with
currents, often oscillating to and fro. The straight intestine
has lateral ceca attached to the body wall by filamentary
mesenteries, which also support the sexual pouches. When
the latter are distended with eggs, they displace the other
viscera. Tetrastemma obscurum and Prosorhochmus Cla-
paredii are viviparous. They are united to the last order by
Microstomidze and Dinophilide, and to Trematoda by
Prorhynchus. In some there is a larval stage (Pilidium—see
above, p. 160%),

This order is divisible into two sub-orders :—1. Arhagea—
with rudimental or no cephalic grooves (p. 158). This in-
cludes two families :—1. Borlasidz—with a simple, un-lobed
head, and two (Cephalothrix), four (Cérstedia), or many eyes
(Ommatoplea, Polystemma), or eyeless, with a _ terminal
(Borlasia) or sub-terminal proboscis (Valencinia). Prorhyn-
chus has a very short proboscis. 2. Chlamidocephalidae—
head two-lobed, divided by a shallow or deep notch (Col-
pocephalus, Chlamidocephalus). The lobes may be long,
again lobed (Lobilabrum).

Sub-order 2. Rhagophora—with head grooves, including
three families. 3. Monorhagea—with one transverse groove,
eyeless (Tubulanus), or with two rows of eyes (Micruraf), or

* Tn the larvee of Echinodermata and Vermes, three types may be dis-
criminated—tIst, that in which a ciliary girdle divides the surface into an
anal and an oral field (Bryozoa, Gephyrea, Holothuria, Echinoidea) ;
2nd, that in which two ciliary zones divide the surface into three regions,
an oral, an anal, and a terminal (Asteriadze, some Chaetopoda, Fig. 22, B) ;
3rd, that in which one ciliary course separates the single oro-anal field
from an imperforate terminal one (Pilidium, Chaetopoda, Rotatoria,
Fig. 22, C). The second and third are derived from the first.

+ Micrura has a terminal, attenuated, and contractile style, a prolon-
gation of the body wall, ciliated externally.

Introduction to Animal Morphology. 163

‘a semicircle of many eyes (Hemicyclia). 4. Dirhagea—with
two grooves, which may be very long (Nemertes, Lineus),
‘or short, with four (Tetrastemma™), or no eyes (Meckeliat).
5. Tetrarhagea—with four grooves (which are converging
x-like (Ophiocephalus), or short, transverse (Loxorrhochma).
Schultzeand McIntosh divide Nemerteans into two sub-orders :—
1. Anopla—with no style in the proboscis; the nerve trunk
placed between the muscular
layers; the mouth opening be-
tween the commissures ; deve-
lopment with metamorphosis.
This includes :—1. Lineidze—
with elongated ganglia; the
body muscles externally longi-
tudinal, mesially circular, and
internally longitudinal; the
proboscis has no _ internal,
longitudinal norreticular layers,
but consists of five coats, ex- _ Diagram of Bipinnaria (p. 136) (B), and
“ a worm (C); A.c, anterior ciliary crown ;
ternal elastic, external longi- m, mouth; m2’, stomach; P.c, posterior
: ; ciliary crown; @, anus.
tudinal, circular, basement,
and glandular laminz; the vessels in the cesophageal wall
form a rete mirabile; the head fissures are deep; a separate
longitudinal band is detached from the investing stratum of
longitudinal fibres. Lineus has a long, slit-like mouth and
variable eyes; Borlasia a slender proboscis; Cerebratulus a
flattened body, thinning to the edge, and a cross-like arrange-
ment of fibres at each pole of the proboscis in transverse
section; Micrura and Meckelia are also included herein.
2. Carinellide—with the lateral nerves between the base-
ment and the outer circular layers, and no head grooves nor
medio-dorsal vessel ; it includes Carinella, with a short mouth
and wide snout; and Valencinia, with a long mouth and
narrow snout. 3. Cephalothricide have a wide interval be-
tween the nerve commissures and the proboscis, armed with

Fig. 22.

* Tetrastemma has four eyes in a square. In Prosorhochmus, they do
not form a square.
t Meckelia has feeble or no head fissures.

M 2

164 Introduction to Animal Morphology.

acicular papillz ; no head fissures. The larve are provided
with eyes, which are usually absent in the adults.

z. Enopla—nerve ganglia nearly double; globular, lateral
nerve trunks within proper muscular walls; mouth in front of
the nerve commisures, ventral ; no metamorphoses. This in-
cludes one family, Amphiporide, with two muscular coats
only, an outer circular and an inner longitudinal, a proboscis
of three parts, anterior or basal, with seven coats, middle
armed with the stylets, and posterior saccular, with two mus-
cular coats. The bodies are generally short, with a long pro-
boscis, except in Nemertes. There are three blood-vessels.
and two cephalic arches.

Rhamphogordius (Rathke)—a thread-like, dicecious or
moncecious, jointed worm, with only longitudinal fibres and
two terminal, proboscis-like lobes, is placed by some among
the Enopla, but by Schnezder is regarded as forming a sub-
division of Nematodes under the name Gymnotoma.

CHAPTER XXIV.
CLASS 2.—COTYLIDEA (Van Beneden).

ENDO- or ecto-parasites (sometimes only temporarily
so), with cup-like or irregular suckers formed of pro-
cesses of the muscular lamina of the body wall, covered
with skin. They have no body cavity, sometimes no
intestine, never an anus, and are ciliated in early life,
but shed their outer layer. To this variable group
belong two orders :—

1. Cestodea (Rudolpht), tape-worms—hermaphro-
dite, segmented, endo-parasitic, band-like persone,
with no digestive nor vascular system ; nourished by
osmose. The first segment (Head, Nurse, Scolex) is

Introduction to Animal Morphology. 165

imperforate, rounded, or facetted, and has 2-4 round or
elongated, sometimes movable, suckers (Fig. 23, B),and
may be armed with hooks of chitin (calcified or silici-
fied ?), acting as anchors, placed often alternately in
circlets. The blunt ends of these are in pouches, and
their roots thicken withage. There are fine hairs on the
head and suckers in Trizenophorus, and on the hinder
end of the body in Tetrarhynchus. The head may
have a central spur (rostellum, cupula), or, as in
Tetrarhynchus, a Fig. 23.
protrusible pro-
boscis, armed with
hooks. Behind the
suckers are occa-
sionally nerveless
redspecks,perhaps
rudimental eyes.
The head is borne
on a neck which

° A, Proglottis of T. solium; @, water-vascular
begins narrow, but system; 4, sexual orifice; c, uterus; d, testes; ¢,

vesiculze seminales ; J; vas deferens ; B, head of

rapidly widensinto _ T. medio-canellata.
the jointed body, which (except in evenness is
made up of 2-c0 metameres. The body grows from
the head (the oldest part) to the distal end, so that the
neck metameres are the newest, and the oldest joints
are those most remote from the head. Each segment
as it ripens develops reproductive organs, and is
named froglottis, in which stage it may have a brief
separate existence. As the immature segments
(Strobila) show an inter-metameral continuity of
textures, and as there is a single water-vascular and
(when present) nervous system, the entire worm is
regarded as a persona, not as a colony.

VS

Sorit

SOL IN

166 Introduction to Animal Morphology.

The component tissues are a chitinous integument, :
a muscular layer, usually not well differentiated from
the connective tissue (parenchyma), which makes up
the thickness of the body, and contains the water-
vascular system, consisting of two, four, six (Ligula),
or eight (Caryophylleus) lateral canals, which are
joined by transverse branches, one at the back of each
metamere, and anteriorly unite in arches. In the last
(oldest) joint the vessels unite directly in a common
excretory pore, in front of which may be a pear-like
contractile vesicle. These canals may have a fine
muscular coat, by which, or by the contraction of the
whole body, the circulation is maintained. They are
lined by tesselated, in the finer branches by ciliated
epithelium; sometimes lateral branches extend into
the muscular layer, even to the surface; and in their
finer ramifications, strewed sometimes abundantly
through the parenchyma, are concentrically laminated,
bright, spherical, calcareous bodies.* The other con-
tents are a clear fluid and small refracting granules.
The nervous system is not detectible in Tzenia, obscure
in others, or consists of a central flat swelling, sending
backwards fine branches, as in Tetrarhynchus at-.
tenuatus, crassus, and megacephalus.

Reproductive organs occur in every proglottis, and
may open ventrally, or in the female ventrally and
the male marginally, or in both marginally. In this
case, the male organ opens above and the female
below, often in a common groove. The marginal
openings are rarely at both sides of each segment,
with double sex-organs (T. cucumerina, elliptica), but
are usually alternate, right and left in successive seg-

* Dissolving without effervescence in acids.

Introduction to Animal Morphology. 167

ments. The male organsconsist ofa testis made up of
acluster ofglobular, grape-like ceca (Fig. 23,A 7), some-
times very numerous, thickest above, and disappearing
when the contents are discharged; the vas-deferens
from each testis dilates into a convoluted tube, which
at the sexual orifice ends in a thread-like penis, which,
when at rest, is coiled in a sheath. The female pos-
sesses separate germigenous and vitelligenous glands,
an oviduct, uterus, egg-shell gland, bursa-copulatrix
(spermatheca), and vagina. These waste after the
extrusion of the eggs. The uterus is usually a con-
voluted pouch, which, when full of eggs, becomes
rosette-shaped, or tree-like. The small oval eggs are
yellow or red, with a hard rough shell, and containing
many bright yelk granules. These eggs, with their
enclosing proglottides, are expelled with the feces of
their host, and the segments crawl slug-like on plants
or damp ground, often remaining free for many days.
Even after the death of the proglottides, the eggs long
retain their vitality. They pass into the stomachs of
other animals with the food, the egg-shell softens and
falls off, and the liberated embryo (Proscolex) begins
to travel through the connective tissues of the body of
the new host, or even in its blood-vessels (Leuckart
found them in the vena portae). This proscolex is an
oval or round clear body, with anteriorly six weak,
curved hooks, and a ciliated clothing which soon dis-
appears. On reaching a suitable site, the hooks
anchor it, and then disappear, and the body becomes
stationary. This, acting as a foreign body, causes a
local exudation of lymph and development of capil-
laries around it, nourishing and encapsulating it. The
larva dilates into a sac full of fluid (water with about

168 Introduction to Animal Morphology.

3 per cent. of salts of soda, anda trace of albumen),
whose wall divides into a surface cuticle, and a deeper
muscular layer of circular (outside) and longitudinal
(inside) fibres, within which is a layer of nucleated
cells. At the end where the hooks were in the pro-
scolex, a swelling of the sub-muscular cells takes place,
projecting at first equally on the outside and into the
saccular body. This grows inward, and divides into
two layers, an outer, receptaculum scolicis, and an
inner, proper body-wall of the scolex. The latter
grows, becomes worm-like, with a dilated, saccular
free end often coiled within the former, which becomes
flask-like and dilated. The water-vascular system
and its concretions early appear in this embryo, and
at the widest end of its cavity the suckers and hooks
form. This scolex was long thought to be a distinct
(cystic) worm, until the researches of Avichenmerster,
Van BReneden, &c., showed it only to be a temporary,
immature condition. Cysts of this kind may give rise
to colonies (when they are called polycampic) either
by the growth of buds from the primary larval sac
(Ccenurus), or by the formation within the primary sac
of a secondary or daughter cell, which develops new
cells by peripheric budding (Echinococcus), or each
cyst may only produce a single head (monocampic).
These cysts are common in the solid tissues of animals
(hydatids, “measles” in pork), and when introduced
into the stomachs of other animals, the outer cyst and
tail vesicle disappear, being dissolved away, the
suckers and hooks develop, and the worm moves in
the intestine of its host, sometimes carrying its caudal
vesicle with it. Hitherto the young worm has been
hollow, but parenchyma rapidly develops after the

Introduction to Animal Morphology. 169

second day of freedom, and the body lengthens, and
shows transverse lines, deepening into joints.

There are about 265 species, divided into seven families.

1. Taeniide—worms of many metameres; head with four
suckers (Fig. 23, B); sex openings usually marginal. Gymno-
taeniz have no rostellum nor hooks, and inhabit herbivorous
Mammals, Man, Amphibians, and Teleostean fishes. G.medio-
canellata (Fig. 23, B), with a black ring round each sucker,
dichotomousuterine pouchesand oval eggs isa common human
parasite in this country, Siberia, Abyssinia, &c., and some-
times is 1200 jointed. G. perfoliata and plicata occur in the
horse. G. dispar in frogs. G.pectinata in hares. Echino-
taenia has a rostellum and 1-4 circlets of hooks, and is para-
sitic in Carnivores and Omnivores, Man, &c. E. solium, the
common tape-worm of Western Europe, has two alternating
circlets, one of larger, one of shorter hooks, twenty-six in all,
each with a short process at its root, and often black hook
follicles; the uterine follicles are dendritic, and contain
spheroidal ova; its larval stage (Cysticercus cellulosz) is the
parasite of measly pork. EE. echinococcus, of the dog, rarely
in Man (Iceland), consists only of 3-4 metameres, and has a
rostellum; its scolex is the hydatid of the human liver
(Echinococcus hominis). FE. crassiceps, of the fox, develops
from Cysticercus longicollis of the field-mouse. E. elliptica,
of the cat, once found in a child, has double sex-organs in
each proglottis. E.acanthotrias is only known in its scolex
stage as a human parasite with three rows of hooks. E.
platycollis is developed from the human C. turbinatus (Ker).
E. nana, found in an Egyptian boy, has an oval rostellum
with one row of hooks. E. marginata, of the dog and wolf,
rarely in Man, develops from C. tenuicollis of ruminants
and swine. E. flavo-punctata, named from the colour of the
seminal vesicle when full, was once found in Man. E. ser-
rata, of the dog, from C. pisiformis, of the hare; E. crassi-
collis, of the cat, from C. fasciolaris, of the rat and mouse.
E. ccenurus, with a rostellum and two rows of hooks, in
dogs, develops from Ccenurus cerebralis of the brain of
sheep, which produces the disease known as the “‘ staggers.”

170 Introduction to Animal Morphology.

C. serialis is a similar scolex inrabbits. E. acanthorhynchus
a short, oval form, from the intestine of the black-necked
Grebe, has a long rostellum with 8-10 rows of hooks. As
Leuckart has shown that some Tzeniz early lost their rostellum
and hooks, other divisions of these worms have been pro-
posed as Sclerolepidota (with hard egg-shells), and Malaco-
lepidota (soft egg-shells) by Wecnland, or Cysticze and Cysti-
cercoide by Leuckart. Family 2. Dibothria—jointed worms,
rarely with hooks, and with two opposite suckers on the
flattened head, placed somewhat like the sense-grooves of
Nemerteans. Bothriocephalus, with its suckers correspond-
ing to the margins of the body, includes B. latus, the tape-
worm of Europe, east of the Rhine, sometimes thirty feet in
length, and with 5-10,000 joints, with wide segments and
genital organs opening centrally (marginally in B. longicollis
of the fowl); the uterus forms a rosette, and the eggs are
oval; within these are developed ciliated proscoleces with
six hooks. Under this ciliated integument a cuticle forms,
and the ciliary layer is shed ; the scolex is free, aquatic. They
are said to abound where lake-water is used for drinking.
Dibothrium has its suckers corresponding to the surfaces, not
to the margins. JD. claviceps, of the eel, and D. probosci-
deus, of the salmon, have marginal sex orifices. D. puncta-
tum, of flatfish, and D. cordatum, a human parasite in
Greenland, with an abundance of calcareous concretions,
have ventral openings. Family 3. Diphyllide—jointed ; head
with two suckers; two rostella armed with vertical hooks ;
neck bristled. Echinobothrium, a selachian parasite, has its
larvz in Crustaceaand Molluscs. Family 4. Tetraphyllide—
jointed, with four movable suckers, sessile or stalked ; this.
group includes three sub-families. Phyllobothrinz, with soft,
hookless suckers, selachian parasites. In Echeneiobothrium,.
the proglottides grow as large as the entire strobile, and the
suckers are ridged like those of Echeneis. Tetrabothrium
and Anthobothrium also live in sharks and rays. Phyllo-
bothrium delphini has been found self-impregnating. Phyl-
lorhynchine—neck thin or swollen; suckers four, and four
retractile proboscides armed with hooks. ‘Tetrarhynchus is
found mostly in sharks; its scolex is known as Anthoce-

Introduction to Animal Morphology. iy fe

phalus, found in Teleostean fishes. Pterobothrium inhabits
Trichiurus. Phyllacanthine have the suckers each armed
with 2-4 hooks. Acanthobothrium is a fish parasite.
Family 5. Ligulide—body only weakly transversely striped ;
head not separate; suckers, z, developed late; middle
of the body with a long furrow. The series of medio-
ventral sexual organs alone indicates the number of compo-
nent metameres. The proscoleces resemble those of Both-
riocephalus. Some multiply by buds, and their immature
forms are found in fish, their perfect forms in fish and water
fowl; some are viviparous. They are found often in the
peritoneal cavities of carp, minnows and sticklebacks. Family
6. Caryophylleide—body flat, unjointed, of one proglottis ;
fimbriated or sub-globose in front; a transverse, two-lipped
sucker lies at the front end; the body consists of a sexual
and an asexual (anterior) part; both sexes may have their
organs opening together medio-ventrally, or the penis may
be anterior; evolution is direct. Caryophyllazus mutabilis is
found in the carp. C. punctulatus in the conger; Eustemma,
in Falco pileatus, has the female opening on a sub-conical,
retractile eminence; Monobothrium and Diporus in fishes.
Family 7. Amphilinide—one-jointed parasites ; passage forms
to the next order, placed here as they have no trace of a di-
gestive canal, except an anterior muscular cecum (a modified
sucker (?) or rudimental pharynx); with a single sucker and
branched water-vascular system, and the oviduct opening
near the head. The development resembles that of Trema-
todes, ex. Amphiline, Amphiptyches. Gyrocotyle, from the
pygarg, has a gyrately-folded sucker and a dorsal pore to the
water-vascular system; in some points it seems to be related
to Malacobdella, Dvzestmg places these in the next, Wagener
in this order.

172 Introduction to Animal Morphology.

CHAPTER 2o3\-
ORDER 2.—TREMATODA (Rudolphr).

FLATTENED, lanceolate, or oval, mono-metameral,
endo- or ecto-parasites, with one or more ventral
suckers, and two pharyngeal nerve ganglia united
by a flat commissure, sending off weak lateral
nerves with no neurilemma, a branch to the oral
sucker and one to the digestive organs; a ganglion
sometimes underlies the ventral sucker (Distoma
lanceolatum). The cuticle is armed with bristles,
spines, or scales, which constitute a head armature
in D. echinatum, militare. The dermis is cellular
or protoplasmic, over a strong trilaminar muscular
stratum, whose inner, circular lamina mostly consists
of spindle-cells, and a connective parenchyma making
up the chiefbulk. The suckers have strong, radiating,
and weaker circular fibres, and in the centre of the
anterior one (except in Polystomidz) is the mouth,
leading into the muscular, suctorial, often globular
pharynx. A narrow cesophagus joins this to the in-
testine, which is usually an excavation in the paren-
chyma, lined by cylinder epithelium, and with no
muscular coat;* it is rarely simple (Aspidogaster,
Gasterostomum); usually forked or branched, aproc-
tous ; the branches are usually cecal, rarely anasto-
mosing ;f some, perhaps, hepatic. In D. filicolle, the
intestine disappears in the adult.

* A muscular coat is described by Leuckart.

+ The two limbs of the intestine may unite to form a ring (Gynee-
cophorus), which gives off branches (Epibdella, &c.), sometimes giving off
a central azygous process (Polystomum integerrimum).

Introduction to Animal Morphology. 173

The water-vascular system con-
sists of two lateral, non-retractile,
ciliated vessels, opening behind
by a common pore, or separately
(Iristomum). There may be a
contractile, non-ciliated sac at the
junction of the two tubes (Fig.
24, 7), or they may be united in a
ring (D. rachizum), or may form
a fine netted canal system (D.
dimorphum). The contents are
water, guanin, and calcareous con-
cretions. The circulatory system
is rarely definite. Tristomum
papillosum has a median tube,
giving offlateral branches. Small
(poison ?) glands surround the an-
terior sucker, and open outside anc es me
the mouth. Some larveand ecto- tee ee

7 = cretorius of (Z) the water-
parasites (Amphistoma sub-clava-_ vascular system; g, oviduct ;
z, ovary; &, cirrus in its pouch;

tum and Dactylogyra) have black 4 testis.
pigment flecks (eyes) in some cases, with rudimental,
crystal cones. The sexes are separatein Gyncecophorus,
Distoma filicolle, Wedlia bipartita ; others are herma-
phrodite. The female organs are, a germ-gland, two
yelk glands, an oviduct, uterus (a long coiled sac),
an azygos shell-gland, a vagina, and a receptaculum
seminis. In D. hepaticum, the common duct, before
it ends in the shell-gland, sends a duct backwards to
the surface. The male organs are two rounded, tubu-
lar testes, a vas deferens, vesicula seminalis, and an
ejaculatory duct, ending in a penis (cirrus), which is
protrusible from its pouch. Sometimes a canal runs.

174 Introduction to Animal Morphology.

from the oviduct to the testis to ensure self-impregna-
tion. The sex-organs always open medio-ventrally.
Gyrodactylus elegans is viviparous. The eggs are
often of odd shapes, and may be developed directly or
metagenetically. The embryos of some are non-
ciliated (D. tereticolle, variegatum).

There are two sub-orders :—

1. Monogenea—eggs large, often angled, pillared, or
filamented, with thick shell; development direct ; young not
ciliated. Ecto-parasites on the skin and gills of fishes,
crustaceans, &c. This includes six families :—1. Octocoty-
lide—long; hinder part of the body lengthened as a tongue-
like lobe, armed with eight suckers in two rows ; two suckers be-
side the mouth; body armed with hooks about the genital pore.
Microcotyle has small suckers and posterior hooks; Gastro-
cotyle has over thirty little suckers posteriorly, and the front
of the body is narrow; Phyllocotyle has two anterior and six
hinder suckers, and a tail armed with a sucker and hooks.
Anthocotyle is club-shaped in front, with two small suckers,
and has posteriorly six small, stalked suckers; at the hinder
point of trisection are two oval side suckers, with frilled
hinder margins, and each ending externally in a stalked
sucker. In Diplozoon, a carp parasite, the individuals, when
they attain maturity, unite in pairs (like the Siamese twins)
at their hinder point of trisection, becoming x-shaped. Each
single individual has two fore suckers, and two hinder areas
each with four suckers. The sex-openings are behind the
point of union. The cirrus is spiral, 2} times as long asthe
whole body. Choricotyle has posteriorly eight suckers on
long stalks, a crown of hooks round the sexual opening, and
two small front suckers. 2. Gyrodactylide—minute, fish
parasites, with two anterior suckers; the hinder part of the
body dilated, margined by small hooks, and armed with two,
long, recurved hooks ; pharynx protrusible, with a papillary
margin anteriorly; water-vascular stems 4, of which only two
end in the pore. Gyrodactylus is found in carp, &c.; in
these, second embryos may be developed within the first,

Introduction to Animal Morphology. 175

formed before their expulsion from the mother. 3. Polysto-
midze—with an anterior small, and six posterior larger suckers
on the flattened margin; hooks 2 (Polystoma), or 8 (Erpo-
cotyle). ‘Two of these have been found as human parasites,
Polystoma pinguicola (ovary, 7reu¢ler), and Tetrastoma renale
(kidney, Dellé Chiaje). 4. Udonellidz—leech-like ; minute ;
front of body with or without lateral suckers; intestine
simple; hinder suckers sessile, with no hooks, often found
on Lernez. 5. Myzostomidz—-aberrant, monoecious forms;
ecto-parasitic on Comatula, and with possible: affinities to
Chetopoda, to Tardigrada, or Crustacea; discoidal, soft,
surrounded by cilia, with latero-abdominal suckers, and hooks
like those of other trematodes; a protrusible proboscis; a
wide stomach; a narrow dendriform intestine, and an anus !
They have holoblastic ova, and ciliated, cylindroid larve,
which develop two pairs of processes like rudimental feet ;
these increase to five pair, and resemble the parapodia of
Cheetopods; in M. cirrhiferum, each bears a bristle; the
nerve system has a pharyngeal commissure and a few ventral
gangliform swellings ; the male sex-organs are double, and
open with the intestine; the testes are branched pouches;
the female organs open separately (Lovén) or with the intes-
tine (Semper). 6. Tristomidze—hinder sucker large, radiated,
with or without a stalk; in front are two round or long lateral
suckers ; intestine branched, with sex openings separate on
the left side. Cyclatella has a crown of tentacles; Tristoma
has hooks on the hinder sucker, ex. Callicotyle, Epibdella ;
some have eye-specks.

Sub-order 2. Digenzea (Van Beneden)—egegs small, nume-
rous; development metagenetic; the egg emits a variably
shaped larva, with or without cilia, sometimes with a touch
papilla and two lateral plates anteriorly; within this larva
arises a cylindrical, tailed body, which becomes free, and
may possess a mouth, pharynx, and water-vascular system, .
opening outwards and into the body cavity. This form sheds
its outer ciliated layer, and is known as a Redia. Sometimes
the water-vascular system extends into the tail, and there
may be a pulsating vesicle there. In other cases, the larva
develops within itself a rounded, or worm-like, tail-less,

176 Introduction to Animal Morphology.

organ-less sac (Sporocyst or Blastocyst, Dzesing), which
may undergo transverse fission. In the body cavity of a
Sporocyst, by internal gemmation one or many daughter cells
are produced, which resemble the parent. Within these, or
within a Redia, form, as internal buds, numerous small, oval
bodies, Cercariz, with movable, sometimes forked tails
(Bucephalus); these become free, and are expelled through
an opening in the ‘‘nurse,” and fora time enjoy free life in
water or on moist ground. They have two suckers, with the
mouth in the foremost, which deepens into a pharynx and
intestine ; the water-vascular system then develops, and the
animal is either swallowed by the host in which it is to be
developed, and becomes at once mature, or it burrows into.
the skin, or into the pulmonic cavities of freshwater Molluscs,
&c., and loses its tail, becomes surrounded by a cyst, and be-
comes a pupa, in which, when its host is eaten by some other
animals, and it is set free in the stomach, the sexual organs
develop, and the adult forms are assumed ; some encapsulate
themselves in plants, and are thus eaten.

The sub-order includes four families :—1. Monostomidze—
one sucker (oral) ; sporocysts in Planorbis; perfect forms in
water-fowl, &c. Monostomum lentis has been found in the
capsule of the human lens. 2. Amphistomide—a sucker at
each end; Diplostoma in the lenses of fishes’ eyes; Amphi-
stoma in frogs, ruminants, &c. 3. Distomide—suckers, 2 ;
one circum-oral in front; one ventral ; never terminal. This
includes the bristled and two proboscis-bearing Rhopalo-
phorus,* and the dicecious Gyncecophorus (Bilharzia) hema-
tobius, common (110 times in 360 subjects, Grzeszmger) in the
vene porte of Egyptians and Nubians. In these, the male has
a large abdominal groove, with two lips, in which the cylindrical
female is contained. The eggs are oval, with a terminal or
lateral spine. Distoma is hermaphrodite, and may be divided
into two sub-genera:—(a), with branched intestine, in-
cluding the ovate D. hepaticum, of the sheep, and rarely

* The proboscides limit the mouth at each angle. These are parasitic
in Opossums. The spines are in rows along the proboscis. R. horridus is
spined over the body.

Introduction to Animal Morphology. 177

of the human liver, about 3?” long, with bristled and appa-
rently puncturated surface; suckers small, close together, with
the sex-opening between them. D. Goliath lives in the
hepatic duct of Balenoptera rostrata; D. Jacksoni in the
Indian elephant; D. clavigerum develops from the Cercaria
of Planorbis; D. clavatum is found in the swordfish;
(8) intestine not branched; uterine pouches reaching the
end, as D. lanceolatum the elongate fluke of the sheep (fig. 24);
rarely in Man; D. crassum and heterophyes also rarely
human; D. trigonocephalus in the otter; D. ophthal-
mobium found in the eye of a child ; D. echinatum in wading
birds; D. squamula of the polecat; D. neuronaia has its
pupa in the nerves of the haddock: its perfect state (Gas-
terostoma gracilescens) in Lophius. 4. Dicyemidz consists
of problematical, ovate, immature, microscopic, ciliated
forms, found in the venous sinuses of the kidneys of Cepha-
lopoda, with oval or cordate head lobes. Planuliform or
worm-like larve develop within them. Several species are
known, which may be immature rhabdoccelous Turbellarians,
but are most probably Rediz of unknown Trematodes; two
clear lateral streaks are probably water-vascular tubes.

CHAPTER: XXVI.
CLASS 3.—NEMATELMIA (Vog?).

CYLINDRICAL, unjointed, mostly dicecious, parasitic
worms, with usually a distinct body cavity, and a ru-
dimental, non-ciliated, water-vascular system ; but no
suckers, bristled ambulatory papille, respiratory, nor
circulatory organs. There is no metameral division,
but the dermis is often ringed ; the nervous system is
often well developed, and the intestine has usually an
anus. Development is direct.
N

178 Introduction to Animal Morphology.

Two orders are included :—

1. Gordiacea (von Szebold)—long, thread-like, elastic,
aproctous, with a firm, fine cuticle, and a faintly
fibrous basement, covering a layer of longitudinal
fibres (which are flattened bands, with their flat sur-
faces in contact with each other), only interrupted
along the median line. The water-vascular system is
absent (Gordius), or represented by a row of cells
(Mermis). The short cesophagus passes from the
mouth to end in a bulb (Mermis), or in an intestine
(Gordius) opening into the body cavity. The nervous
system is feeble, but of the nematode type. The
sexual organs consist of simple tubes, developed in
the peri-enteric connective tissue, at the expense of
the vanishing digestive organs, and opening poste-
riorly (the female opening may be central in Mermis).
They are parasitic in insects for some part of their
life, free at other times ; when mature, they live mostly
in water or mud, where they reproduce, and their
young either return to their insect hosts (Mermis) or
undergo metamorphosis. They reproduce in large
numbers, and so suddenly do the young of M. albicans
appear in favourable seasons, as to give rise to the
belief that they have fallen with rain. The larve
have one or more cephalic boring spines, sometimes
(Gordius) an armature of recurved hooks.

There are three families and about thirty species :—
1. Gordiide—yellowish brown, or black, with an intestine;
head not papillose; females entire or forked at the tail ;
uterus one-horned ; males forked, with the spicule-less sexual
opening in the fork ; eggs pear-shaped. Gordius begins life
free, with a retractile spiny proboscis and a transversely
wrinkled body; it enters some aquatic insect, and becomes

Introduction to Animal Morphology. 179

encysted therein ; its perfect forms are found in Orthopterous
or Neuropterous insects, which it again leaves for repro-
duction, and becomes free, losing its mouth and intestine.
2. Mermidz—thread-like ; cesophagus short; head papillary ;
tail undivided papillary in the male, with a double penis
(spiculum, spermategz of Dvesing); egg-shells often with
brush-like tassels; eggs not in chains as in Gordius; uterus
two-horned; larve with single cephalic spines, found in
Lepidoptera, &c. 3. Sphzrularide—in the body cavity of
Bombus ; with no mouth nor cesophagus (or a mouth opening
into the body cavity?); skin with vesicles; male small,
zsv00 Of the size of the female, to which it is organically
fastened; female with a simply tubular ovary, a terminal
genital opening, and two rows of large cells in the body
cavity.

Order 2. Nematoda (Rudolphz\—free or parasitic
round worms, with a smooth, never ciliated, some-
times double refracting cuticle; rarely with bristles
or lateral wing-like expansions beside the head (these
are sometimes inconstant, as in Ascaris dactyluris).
This layer is chitinoid, and sometimes makes the body
stiff, but is less resisting to re-agents than the chitin of
Arthropods; it is traversed by fine pores, often annu-
lated, transversely striped, or laminated, the superficial
layers being the most chitinous. The dermis is
thinner, obliquely striated, made of granular proto-
plasm, and longitudinal and vertical connective fibres ;
it is often traversed by lamine, and sometimes con-
tains unicellular glands. In Trichocephalus, there is
a ventral row of rod-like bodies in the dermis. In
Trichosoma, a ventral and dorsal row; in others,
nail-like rods. Young nematodes usually moult several
times. The muscular lamina, thicker than the inte-
gument, as it isin most Vermes, consists of two sets

N 2

180 Introduction to Animal Morphology.

of large,* flattish, spindle-shaped, longitudinal fibres,
either continuous (Trichocephalus) or divided into
dorsal, ventral, and lateral tracts, separated by
thickenings and prolongation of the cutis. Some-
times vesicular processes are appended to the fibres
(tracheal sacs of Lozanus), and in some the processes
of the muscular fibres unite with the nerves, or run
into the neurilemma, especially around the pharyngeal
ring, reminding us of the neuro-muscular cells of
Hydra. The muscle fibres may be solid, flat (Platy-
myaria), or tubular (Ccelomyaria), with a striated wall
enclosing granular protoplasm, continuous with that
in the vesicular swellings.

The nervous system consists of an cesophageal
ring covered by multipolar ganglion cells, surrounded
by a sheath, sending forwards two branches in the
lateral field, and four in the mesial line, some of which
go to the oral papille ; ganglion cells lie in the course
of these. Behind, the ring gives dorsal and ventral
branches ; two of the latter often speedily unite to
form a ventral (cephalic) ganglion, and in some young
forms post anal ganglionic enlargements exist. Touch
papille exist in some; perhaps the oral lobes may be
of this nature. Nerveless eye specks exist in some
free forms, while true eyes are present in the free
genera, Enoplus and Urolabes.

‘The mouth is anterior, surrounded by lips or pa-
pille, which sometimes become chitinized as jaws ;
it is rarely cup-like (Cucullanus). The cesophagus is
narrow, often gradually thickening, surrounded by
circular fibres in some (Heterakis, Oxyuris), separate

* In Strongylus gigas each is 4 ma. ,; Ascaris lumbricoides 3 mm. ;
Dochmius hypostoma 2 mm.

Introduction to Animal Morphology. 181

from the body wall, to which it may be suspended by
mesenteric strings. Little spines sometimes arm its
oral end, even in embryos (Enoplus and Anguillula).
In Ascaris megalocephalus there is a gland in the
cesophagus opening outwardly. In Cheiracanthus
aculeatus, of the tiger, four czecal (salivary ?) glands
open into the mouth; while a lining of gland-cells in
the oesophagus is not uncommon. In some, the
oesophagus acts as a sucking tube, and is divided into
a glandular and a suctorial part. The so-called
stomach is distinct, muscular, often globular, some-
times with a chitinous, gizzard-like lining, and may
be suctorial, the true stomach then being the dilated
end of the straight intestine, into which this gizzard
opens by a narrow pylorus. The intestine has a
glandular lining, a muscular coat (for its lower third
only in some), and it is held in its place by thick, in-
terrupted, cellular mesenteries, the appendices nour-
riciéres of Cloguet. The anus is ventral, longitudinal,
sometimes sub-terminal or terminal (Trichina, Tricho-
cephalus), absent only in one family; glandular ceca
often occur in the course of the intestine. Anguillula
appendiculata has one from the intestine, Asc. hali-
coris from the stomach. The body cavity contains a
perivisceral fluid (blood?), in which a few oval and
amoeboid corpuscles float. A water-vascular canal
lies in each of the thick lateral lines of the dermis ;
these open by a common medio-abdominal pore,
usually at the level of the muscular stomach. They
are seldom absent, branched in Strongylus auricularis,
and forming a ribbon-like lateral organin Filaria. The
four circum-anal ceca in Ascaris dactyluris, which
open by narrow ducts within the anus, may be excre-
tory organs, possibly renal.

182 Introduction to Animal Morphology.

The sexes are separate, except in Pelodytes,
Filaria, and Ascaris nigrovenosa. The organs are
large, and produce large quantities of sexual pro-
ducts. The male possesses one, rarely two, ventral,
convoluted, tubular testes, ending in a vas deferens
leading to a seminal vesicle, often villous within.
The duct opens beside the anus, and is armed with
one or two chitinous spicules, arising from muscular
pouches. The epithelium of the testis is ovoidal, of
the vesicle and ductflatter. The female possesses 1-5
convoluted tubular ovaries ; usually two, uniting at the
pre-anal, often medio-ventral, vagina, which equals
the spicula in length. Sometimes there are two
papille midway between the anus and tip of the tail,
in Pelodera appendiculata prolonged into ribbon-like
appendages. The first part of each ovary may be
germigenous, the next part vitelligenous, and this may
join the terminal dilated part or uterus by a narrow
tube (Leptodera appendiculata). The sexual tubes
are first filled with granular protoplasm, which forms
a central rachis, on which the eggs or the mother-
cells of the spermatozoa develop. In some of the few
hermaphrodite forms, both products develop in the
same tube, sperm-cells first, afterwards ova, as in the
parasite form of Ascaris nigrovenosa (which has a
female appearance). Some species are viviparous,
others lay hard or soft-shelled eggs, a few have a
metamorphic development; thus Urolabes palustris
is the larva of Filaria Medinensis. The eggs of
Dochmius trigonocephalus of the dog develop into ©
Rhabditis-like forms in water, and after several
moults, again enter the dog’s intestine with its drink,
and in twenty-four days lose the stomach teeth, and

Introduction to Animal Morphology. 183

assume the adult form. Some of these larve have
been found retaining the Rhabditis form in the
mollusc Physa. Ascaris nigrovenosa lives as a her-
maphrodite form, often 12 mm. long, in the lung of
the brown frog, and produces ova. The young, bred
from these, enter the cloaca of frogs, and assume a
Rhabditis form, with short, pointed tails; these be-
come free, dicecious, in mud or water, and produce
eggs, which emit Rhabditoid embryos, often in the
uterus, and then entering into frogs, again moult,
lose their teeth, and develop forms like the original
Ascaris.

Passive wandering occurs in some forms; thus
some Strongyli begin life in Fish, and end in fish-
eaters. Cucullanus elegans begins in Cyclops, and
with these enters the stomach of fishes. Active
wandering occurs in Trichina spiralis, &c. Some
forms have a boring cephalic spine. About goo
species are known.

They are divisible into four sub-orders :—

1. Rhabdophora—free, marine, slender, bristled; with
two rows of pre-anal cylindrical rods, whereby they creep.
Chaetosoma has 2-15 pair of straight rods; males small, with
two spicula; females with two spermathece and pre-centrally
opening vagina. Rhabdogaster has many short, curved rods,
in the midst of which is the female orifice. This genus has
no cephalic hooks, while the former has movable hooks in a
double series. These appear to be the nearest allies of
Chaetognatha.

Sub-order 2. Cystoopseade—imperfectly known, aproc-
tous parasites (under the breast-shields of the sterlet), with
thread-like males and oval cystic females ( Wagner).

Sub-order 3. Hypophalli—rod-like appendages none;
penis ventral, in front of the tail. This includes fourteen
families :—1. Cucullanide—parasitic ; head distinct. Cucul-

184 Introduction to Animal Morphology.

lanus has two apical shell-like valves based on a chitinous
ring, sending off processes. Lecanocephalus has a patelli-
form head, a spinulose body, and a sword-like penis-sheath.
Heterocheilus, of the Manatee, has a short neck and three
unequal lips. Conocephalus, of the Dolphin, has a conical
head with a retractile border, a simple uterus, and two
ovaries. In Ancyranthus, of the Tortoise, the head is armed
with 4-8 pinnatifid spines, with two long central and two
small lateral, bicuspid spines ; in Elaphocephalus, found in the
sheath of the digital tendons of a macaw, and in Aspido-
cephalus, the head has lateral leathery shields and a central
mouth. 2. Cirrhostomidze—free, thread-like; mouth cir-
riferous ; a caudal gland opening at the tip of the often papil-
lary, bifid tail; stomach not globular. Phanoglene has two
large cervical eyes. Enchelidium has one postoral pigment
mass, with several lenses. The tail has no papilla in the
marine Pontonema ; it is suctorial in the freshwater Amblyura.
Oncholaimus has two or three, and Odontobius has 3-6 teeth.
Enoplus has 2—4 teeth and red eye-specks. 3. Anguillulide—
stomach muscular; pharynx seldom with chitinous teeth; no
caudal gland. Dorylaimus has a central stilet-like tooth in
its protrusible proboscis. Diplogaster has several teeth, as
has Rhabditis, the vinegar and paste eel. Anguillula—free
or parasitic; has no teeth nor penial sheath. Myoryctes
is parasitic in the muscles of frogs. Pelodytes is her-
maphrodite (in Mollusca). Angiostomum has chitinous,
pharyngeal plates, and no stomach. Leptodera is bila-
biate, and has, like the last, a two-bladed penial sheath.
4. Hedruride—mouth two-lipped; the straight females
have a hinder sucking groove with a central hook; the
males are coiled; penial sheath, none (Hedruris), or
double (Symplecta). 5. Ophistomide—mouth two-lipped,
ventral; head cup-like (Stelmius), or rounded, continuous
with the body ; sometimes with a chitinous support (Dacnitis) ;
female tail unicoronate (Ophiostomum), or bifid (Rictularia).
6. Spiruridz—long, with terminal mouth ; head papillose or
lipped; hinder end of male coiled, winged (papillose in
Eucamptus) mouth, with one papillose, circular (Spirura), or
two lips (Cheilospirula), or none (Spiroptera); S. hominis

Introduction to Animal Morphology. 185

has been found in the human bladder. 7. Tropidocereide—
male slender; female sub-globose, with four longitudinal
bands; neck with two basilar spines. 8. Cheiracanthide—
body armed as far as the middle with pointed lateral lamelle ;
head bristled, two-lipped ; penis not sheathed ; in cats, tigers,
alligators, &c. 9. Physalopteridea—males with a winged
tail-vesicle filled with a clear fluid; mouth bilabiate, papil-
lose outside, toothed within; in alligators and Mammals.
1o. Ascaride—mouth with three labial lobes, and sometimes
touch papillae; stomach often with teeth. The penis in
Ascaris is thread-like, with a two-leaved sheath. A. lumbri-
coides is the common human round worm, also in the orang,
swine, &c.; 5-11” long; tapering to each end; each lip has
many (200) papillz ; the females are largest, and, as in other
species, the most numerous ; the vagina opens at the anterior
third. A. mystax, of the cat, is winged at its head. A.acus,
of the gar-pike, has linear wings. A. heteroptera has inequi-
lateral wings. Haligmus has a spiral, sheathless penis.
11. Oxyuride—long, with naked or spiny tails ; mouth ter-
minal, papillose, or lobate; teeth pharyngeal (Passalurus),
cesophageal (Pharyngodon, with no penial sheath), or at the
junction of the pharynx and cesophagus (Heterakis). Oxyuris
has no teeth; the tail is acute in the female, papillose in the
male. O. vermicularis is the human thread-worm. Cosmo-
cerca is four-lipped, and has a ventral horny plate. Tachy-
gonetria is viviparous. 12. Ptychocephalida—thread-like ;
head sub-globose, with five radiating folds; cesophagus with
three horny grooves; in beetles. 13. Filaride—hair-like ;
mouth round; penis thread-like, with one or two leaf-like
sheaths. Filaria Medinensis, the Guinea worm, is viviparous,
and begins life as a form like Urolabes; pierces the skin of
bathers, then develops in the cellular tissue, and may attain
the length of several feet. F. capucinus has been found in
American monkeys. F. lentis in the human eye. F. Loa in
the eye of a Negro. Filaroides, of the polecat, is ringed.
Gongylonema, of the mouse, has in front a longitudinal
series of bulbilli. 14. Liorhynchide—mouth in the centre
of a protractile tube; found in fishes.

Sub-order 4. Acrophalli—proctuchous; penis terminal.

186 Introduction to Animal Morphology.

This includes two families :—1. Strongylide—cylindrical,
long, with a disc or vesicle at the tip of the tail, from which
the penis arises; some have a terminal mouth with six
(Deletrocephalus) or 4-8 converging, chitinous rods (Diapha-
nocephalus) ; others have a chitinous ring around the head,
and a mouth inferior (Dochmius, D. duodenale, of the human
duodenum, is common in Egypt) or terminal, and the penis.
surrounded by three papilla (Stephanurus), or with a two-
leaved penis sheath (Sclerostomum). The young of S. ten-
tracanthum has a free Rhabditis form. Metastrongylus.
longevaginatus, with a bilobed male disc and two long yellow
spicules, has been found in the bronchial glands of Man.
Ollulanus is found in the stomach of cats. Eustrongylus in
the human kidney. 2. Trichotrachelide—body long, with a
thread-like neck; the spiral males have a simple spiculum,
sometimes with no penis sheath (Trichina). This form lives.
encysted and sexless in the muscles of Man, swine, &c.; but
when set free by being swallowed, the sexual organs develop,
young are produced, which burrow and become encysted in
the muscles; the males have two terminal tubercles, one anal
and one genital. Onchocerca reticulata, of the muscles of
horses, is closely allied. Trichosomum has a tubular penis
sheath, and a short neck. In T. crassicauda, of the rat’s
bladder, there are pigmy males without spicula in the uterus.
of the females, as well as free living males with spicula.
Trichocephalus, the common hair worm of the human
czecum, has a long, thread-like neck, a swollen body, anda
vesicular, echinulated penis sheath; its muscle layers are
rudimental.

Introduction to Animal Morphology. 187

CHAPTER XXVII.
CLASS 4.—ACANTHOCEPHALA (Rudolpht).

CYLINDRICAL, dicecious parasites, with a protrusible
proboscis, armed with transverse or oblique rows of
strong recurved hooks, resembling that of the strongy-
loid genus Hystrichis; at its base is a sheath, within
which it may be retracted by four lateral retractor
muscles. This organ is attached to, and often im-
bedded in, the wall of the intestine of the host. The
yellow cuticle is sometimes armed with chitinous
hooks, and always traversed by pore-canals, whereby
nutrition takes place. Beneath it and the proto-
plasmic dermis is a layer of striped, circular, and
longitudinal muscular fibres. Three laminz of muscle
lie in the wall of the proboscis sheath. There is no
mouth nor intestine. A nerve ganglion lies at the base
of the proboscis, to which it gives two branches.
Two or more lateral nerves pass bagkward. In the
muscular layer are many branching* canals, with two
chief lateral stems, extending forwards. These have
no special walls, so the granule-holding, often red,
fluid within them is moved by the contraction of the
body and the motions of the proboscis. Possibly this
may be a nutritive apparatus like the gastro-vascular
canal of Ccelenterata. The lateral stems end in a
circular vessel in the neck, from which, branches pass
to the proboscis. With the stems of these probosci-
dean vessels canals communicate from two band-like

* Not always much branched. In E. porrigens the branches appear
in some young specimens to be few, straight.

188 Introduction to Animal Morphology.

organs (lemnisci), which lie directly behind the pro-
boscis, each of which has a central large vessel giving
off many close branches. Although these vessels do
not open outwards, yet they probably form a water-
vascular system ; the smaller vessels of the lemniscus
and those of the body wall do not anastomose. From
the base of the proboscis a central connective band is
continued backwards, which supports the sexual
organs (ligamentum suspensorium ; Lésfes describes
a rudimental intestine and gland attached to this).
The males are smaller, and have a hinder sucker used
in copulation, in the middle of which is the protrusible
penis, with two retractor muscles at its base. They
have also 2-3 testes whose ducts opens into a common
vas deferens, dilated into several vesicule seminales.
The females have an ovary, which may fill the whole
body, often divided longitudinally, and emitting the
ova by dehiscence. A bell-shaped uterine funnel re-
ceives these, and they pass out by a short vagina at
the posterior end of the body. The fusiform eggs
have no germinal vesicle, and the embryo forms peri-
phericallyinthem. Theeggs areeatenby Amphipods,
Isopods, &c., and their embryos appear as hook-
armed gregariniform worms.* These burrow out of
the intestine, lose their hooks, become encysted, and
are eaten in this stage by fish, water-fowl, &c., in
which they finally develop. The musculo-vascular
layers develop from the outer embryonic lamina,
within which the nerves, proboscis, and genitals arise.

Echinorhynchus is unsegmented. E. gigas inhabits the
intestines of Swine, and was once found in Man (Lamdé/); E.

* The embryo of E. claviceps has no hooks at first.

Introduction to Animal Morphology. 189

porrigens, the lesser Rorqual and Eider duck. E. major, the
hedgehog. Paradoxites, found in owls, is divided into
metameres, of which the first (proboscis-bearing) and the last
three are large.

CLASS 5. GEPHYREA (Quatrefages).— Dicecious
marine, oval, elongate, or sac-like, sometimes ringed,
but never jointed, nor with locomotory processes,
varying from 3” to 1’ in length. The cuticle is
chitinous, sometimes with papillary thickenings, rarely
with cnidz (Anoplosomatum Antillense). The dermis
consists of connective tissue, containing no spicules,
but numerous follicular dermal glands sometimes im-
bedded, or on papillary elevations. Some of these
are round, each containing four vesicles around a
cellular, expanded nerve-ending, sending four bands
into the vesicles (organs of Semper). Some have
bristles in rows on the surface, and in Bonellia the skin
contains chlorophyll. The muscular coat is thick,
striped, with outer circular and inner longitudinal
fibres, often netted, and closely attached to the skin.
The body cavity is ciliated within. The nervous
system consists of an cesophageal ring with a single
or double dorsal ganglion (Sipunculus, Sternaspis),
sending backward a ventral cord in the body cavity ;
rarely outside the muscular lamina(Priapulus). Only
in Echiurus are there faint successive swellings on
this cord, and in Sipunculus there is a terminal
swelling giving off branches. These appearances and
the rudimental partitions in the body cavity of Phas-
colosoma are indications of metameric division. The
ventral cord has a contractile connective sheath
(of two laminz separated by soft cells) continued on
the lateral branches, which may be irregular, symme-

190 Introduction to Animal Morphology.

trical (Sipunculus), or alternate (Phascolosoma). In
Sipunculus, some filaments unite with the circular
muscular fibres. Eye-specks are present in a few
adults, and the larva of Sipunculus has four, close to
the ganglion, but vanishing indevelopment. The front
of the body in some is prolonged into a proboscis, usu-
ally retractile by means of two or four muscular bands
from the body wall, and ciliated, often armed with
bristles, and sometimes surrounded by tentacles. The
mouth is terminal or slightly ventral (Sternaspis), and
the pharynx is armed in Priapulide with horny teeth.
Salivary ceeca open herein in Sipunculus (Ae/ferstezn
and Ehlers). The intestinal canal is ciliated within
and without; small in calibre; slung by mesenteric
threads; rarely by a membrane; it may be scarcely
longer than the body (P. brevicaudus) ; or more
usually, long and coiled. (In an Echiurus of 6” it
measured 33.) Its middle region is glandular, often
yellowish (hepatic *), as in Bonellia ; or with numerous
glandular ceeca appended (Phascolosoma). The oral,
gastric, and intestinal regions are distinguishable
in the young, sometimes in the adult (Priapulus).
The anus may be dorsal, sometimes anterior, even
at the junction of the body and proboscis, or ter-
minal.

There may be no vascular system, or it may con-
sist of two long vessels, one along the medio-ventral
line, giving off many branches to the intestine and the
wall of the body, and one dorsal running along the
intestine, and often coiled with it.

In Sipunculus these are joined by a circumoral vessel,
which sends prolongations into the hollow tentacles, and has
appended to it one or two contractile sacs like the Polian

Introduction to Animal Morphology. 191

vesicles of Echinoderms. This portion has been described
as a special tentacular or aquiferous system. Similar ceca
may be appended to the dorsal vessel ; but when there are no
tentacles, this canal breaks up into fine branches anteriorly.
In those with no vascular system (except Halicryptus) there
isa posterior opening, capable of voluntary closure, into the
body cavity, whereby water can pass in and out for aerating
purposes(?) A similar anterior opening I have found co-
existing with a vascular system in several genera. The fluid
in the circulatory system may be colourless, pale red, blue or
violet. ‘There may be a similar fluid in the body cavity con-
taining amceboid, flagellate, and ciliated (?) corpuscles.
Priapulus has at its hinder end a fimbriated tuft, which
may be respiratory. Echiurus has opening into the intestine,
at its lowest part, branched organs, receiving vessels from the
ventral trunk, like the tree-like organs of Holothurians, which
are either excretory or respiratory. There is a rudiment of
this in Sipunculus and others, and in Bonellia it has many
openings into the ceeloma. The tentacles of Sipunculus also
act as breathing organs. There are certain ventral ciliated
pouches (often four) homologous with the segmental organs of
Annelids. In Echiurus all the four may be utilised as ex-
cretory ducts for the sex-organs. In Sternaspis, one pair
only is connected therewith, the others containing a yellow
material (urinary?) Thalassema has only one pair existing
corresponding to the former pair in Sternaspis; these open
inwards by fine spiral canals. In Sipunculus there is one
pair representing the latter pair in Sternaspis, and non-sexual.
In Bonellia there is only one, forming a funnel-shaped
uterus, and representing the right(?) of the sexual pair of
Sternaspis.

The males are fewer than the females, often
dimorphic (in Bonellia as a planaria-like form, living
in the female sexual organs, Kowalewsky). The sexual
organs are string-like, simple or in pairs (or a ciliated
furrow on the intestine Sipunculus, Peters), dehiscing
into the body cavity. A few are hermaphrodite

192 Introduction to Animal Morphology.

(Sipunculus, Aeferstezn). In Bonellia the eggs are
developed in a longitudinal, medio-ventral fold.

The embryos are free-swimming, ciliated, with a
ciliary girdle and an anterior mouth dorsally over-
lapped by a bilobate upper lip; ventrally, there is
either a single lower lip or several ciliated processes
(five in Phascolosoma minutum) the homologues of
the trochal discs of Rotifera. These in Sipunculus.

Fig. 25.

A B

Gi

A, larva of Phascolosoma ; ¢, upper lip; 7, lower lip; 2, intestine ; 7, mouth;
B and C, mollusc larve.

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Seo, Oe
Po Sto
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90 998
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oF 5:

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cts

develop into the tentacles. Similar lobes are not
confined to Gephyrean larve, but reach their greatest
development in the form Actinotrocha (probably the
larva of the Chetopod Phoronis). The metamor-
phoses in development resemble those of the Echino-
dermal larve, as only part of the larva is concerned
in the development of the adult.

They are divisible into two orders :—

1. Inermia—bristles and vascular system, none. Family
1. Sipunculide—cylindrical, with the mouth at the tip of the
retractile proboscis surrounded with tentacles, often with

Introduction to Animal Morphology. 193

hooks; intestine usually spiral; anus dorsal; teeth none;
skin netted with anastomosing muscle fibres (Sipunculus), or
papillose, with cylindrical (Phascolosoma), or clustered (Den-
drostomum) tentacles. Family z. Aspidosiphonide—with
two dermal shields beside the proboscis, and a posterior
anus, ex. Aspidosiphon, Diesingia. Family 3. Priapulide—
proboscis retractile, ribbed ; tentacles none ; anus posterior ;
tail bearing a tuft of hollow, pouch-like processes, and with
a pore into the body cavity (absent in Halicryptus) ; the pro-
cesses are thread-like in ten long rows in Lacazia. Anoplo-
somatum has cnide.

Order z. Armata—bristled, with a developed vascular
system. Family 4. Thalassemide—cylindrical or fusiform,
with a non-retractile proboscis above the mouth; anus pos-
terior ; excretory organs opening into the intestine ; proboscis
short, undivided (Echiurus), or long, single (Thalassema), or
forked (Bonellia), or absent, but a tubularly protrusible mouth
instead (Ancistropus). Family 5. Sternaspides—ringed ;
abdomen flat, with a posterior horny shield, bristled round its
edge; several girdles of bristles anteriorly ; anus dorsal, sub-
terminal, ending in a retractile papilla, with simple tubular
threads beside it, ex. Sternaspis. Family 6. Chetodermide—
surface beset with spines; gills z, branched; proboscis
retractile.

CHAPIER XXVIII.
CLASS 6. ROTATORIA (Lhrenberg’.

MICROSCOPIC,* dicecious, aquatic, smooth, or slightly
annulated animals. The rings are most distinct when
the cuticle is not fully chitinized, and are often six,
equal or unequal ; but there is no trace of visceral re-

194 Introduction to Animal Morphology.

petition. The surface may be naked or loricated, the
lorica being either closely applied or as a loose sheath.
At the anterior end lie one or more ciliated, lobate
discs (homologous with the anterior ciliary zone of the
larvee of Echinodermata, Gephyrea, &c.), the motion
of whose (usually double) rows of cilia gives the ap-
pearance of rotating wheels. Between the cilia are
long, stiff bristles, and in Notommata centrura a cluster
of such bristles lies in the centre of the body. Beside
these ¢rochal discs there is often a ciliated, frontal lobe
(calcar or antenna, double in Melicerta), and there
may be a ciliated, dorso-ventral groove on the surface.
The dermis is of finely granular protoplasm, with a
layer of round cells like the parenchyma cells of Tur-
bellarians. Under this is an interrupted muscular
layer of circular and longitudinal, smooth or striped
fibres, often divided into bands, which may be spe-
cialized for the contraction of the body (which they
sometimes draw in like a telescope), and retraction of
the trochal disc.

There is one cervical nerve-ganglion, often in
symmetrical halves, lying on, not around, the pharynx,
giving off branches to the eyes and bristles, as well as
lateral body-filaments. The eyes are one or two, red,
placed on the neck or forehead ; when only one there
is rarely, when two there are usually, lenses and
nerves connected therewith. Some have eyes in the
embryonic, and lose them in the adult, state. Touch-
bristles may be placed around the frontal lobes or
trochal discs, and one or two conical or cylindrical,
hair-beset tentacles may be placed on the neck. On
the ganglion lies a sac containing a white, chalky
matter, with, in a few cases, a duct apparently opening

Introduction to Animal Morphology. 195

anteriorly (excretory or auditory ?). Beside it there is
occasionally a closed vesicle containing neither solid
matter nor clear cells.

The mouth is ventral, only anterior and terminal
in Floscularia and Stephanoceros; it opens into a
muscular, often bulbous, non-ciliated pharynx, contain-
ing the horizontally acting, semi-lunar, or horn-like
jaws. These consist of two parts : a lower jaw (incus)
made of a fulcrum and two movable rami, and an
upper jaw (malleus) made of a handle and a toothed
blade or uncus. Muscles are attached to chitinous
ridges on these. Sometimes a reserve pair of jaws
lies beside the functional pair. The cesophagus is short,
the stomach large, ciliated, lined by coloured hepatic
cells, and receiving the secretion of a pair of rounded
(pancreatic ?) glands; it may be blind, with ciliated
cardiac ceca, or may end in a straight intestine with
a dorsal anus. There is no circulatory nor respiratory
apparatus ; the clear or faintly reddish chyle moves
freely in the body cavity. The water-vascular system,
well marked in Limnias and Floscularia, consists of
two long, often convoluted, canals, with cellular, ci-
liated walls, and short side branches or ovate vesicles,
each with a single, central, basal filament. These have
tubular or funnel-shaped openings into the body
cavity. The two stems unite in a contractile vesicle,
ending in the cloaca, or where there is no cloaca,
opening directly behind. In embryos there exists in
front of the cloaca a cellular organ, disappearing in
after development (primitive kidney of Leydzg ?)

The hinder end is elongated into a short or long,
closely ringed or clearly jointed tail, which may be
either a trace of metameral growth or made of two

02

196 Introduction to Animal Morphology.

fused parapodia. <A few are sessile, tube-dwellers.
The tails of others contain glandular tissue, and may
end in a forceps of two blades for holding to foreign
bodies. Some have long, bristled, swimming feet,
three, six, or more (Triarthra, Hexarthra, Polyarthra).
Pedalion has beside its two trochal discs, two median
dorsal, two median ventral, two right lateral, and two
left lateral appendages (imperfectly jointed ?) like those
of Dinocharis, and moved by striped muscle; it has
also two caudal ciliated lappets.

The sexes are dimorphic, the males being few,
small, with no digestive organs except a rudimental
pharynx, but with a water-vascular system. The
azygos, saccular testis appears early in the embryonic
male, and the end of the vas deferens is protrusible as
apenis. Themale may differ, even in shape of its trochal
discs, from the female. The females have a roundish
or crescentic ovary, an oviduct opening dorsally into
the cloaca, when such exists. The eggs are of two
kinds, thin-shelled in summer; but as no males are
found at the time of their production, they constitute
an example of parthenogenesis. From some of these
eggs males develop, but they are always vastly fewer
than thefemales. The winter eggs are hard, and often
rough-shelled. The eggs have no primitive streak,
and develop slowly. The embryos are directly deve-
loped, varying only in the growth or disappearance of
organs. Floscularia has a worm-like larva, with a
ciliary zone (Wezsse).

There are about 215, mostly freshwater, species, some of

which bear drying, and revivify on moistening.
Order 1. Gasterodela*—body sacciform, with neither

* Some make an order Gastrotricha for Ichthydium, Chetonotus, &c.
Taphrocampa having a chewing apparatus, joins this to the true Rotifers.

Introduction to Animal Morphology. 197

lorica nor intestine. In Asplanchna there is an entire trochal
disc and toothed jaws. The male has two large and two
small pairs of limbs, but no muscles. Ascomorpha has no
water-vascular system, and rudimental, toothless jaws. Some
species, otherwise undistinguishable from Notommata, are
also aproctous (N. myrmeleo).

Order 2. Hoiotrocha—proctuchous, disc entire, rounded,
including the families—1. Ptygurida—only the post-abdomen
segmented; disc circular, with one (Ptygura) or two crowns
of cilia (Diplotrocha). 2. C&cistidae—tail long; disc round
or elliptical; eyes present in the embryo, persisting or
vanishing (CEcistes); body in cylindrical, yellow thece,
fastened to the base, single (Cécistes), or in free colonies
(Conochilus).

Order 3. Schizotrocha—proctuchous, trochal disc lobed,
notched, or divided. 1. Megalotrochide—deeply notched ;
thece none; umbrella-shaped, free, and possessing eyes
when young, but the adults are sessile and blind. 2. Floscu-
laridee—disc 2-4 lobed, or with 5-6 tentacles (Stephanoceros),
sometimes with two proboscides and a tubular lorica beset
with lenticular bodies (Melicerta). 3, Hydatinide—un-
sheathed ; disc many-lobed. Pleurotrocha has one tooth and
no eyes. Hydatina has a short foot, no eyes, and several
teeth. Notommata has a nuchal eye. Hexarthra and Poly-
arthra have limb-like processes. Diglena has two frontal
eyes. Triophthalmus has three eyes. 4. Euchlanida—like
the last, but loricated. Euchlanis has one eye-speck and a
short jointed foot. Salpina is pointed at each end, has one
eye and a dorsal groove. Metopidia has two eyes, and Lepa-
della none.

Order 4. Zygotrocha—two, simple, trochal discs, often
with a frontal lobe between them. Family 1. Philodinide—
naked, with a long divided tail ; jaws two, crescentic, with two
teeth on each; often viviparous, with two frontal (Rotifer)
or nuchal eyes (Philodina, found in Alpine snows), or none
(Callidina). 2. Scaridinide—foot with long joints, often
with long bristles; not retractile; skin soft (Scaridium), or
hard (Dinocharis). 3. Brachionide—loricated, completely
enveloped behind (Anurza), or with the foot passing through

198 Introduction to Animal Morphology.

a hole in the lorica, which may be sculptured, or elongated
into horns in front; eyes none (Noteus), two (Pterodina),
or one four-angted nuchal (Brachionus). Arthracanthus has
long, pointed, retroverted lorical spines. 4. Perosotrocha—
worm-like, with a rudimental trochal disc. Albertia, parasitic
in earth-worms, has only a ciliated oral edge. Lindia, also
parasitic, is non-ciliated, with two club-like head processes,
and a short bifid foot. Apsilus is a non-segmented, thick-
skinned form, found on Nymphza leaves. The young
females are ciliated, and with eyes; the males retain these,
but adult females lose them. Balatro is also non-ciliated.

CHAPINE Ax Lx.
CLASS 7.—HIRUDINEA.

MOSTLY aquatic, ecto-, rarely endo-parasites,* con-
sisting of a chain of homonomous metameres, called
zonttes, usually ringed on the surface, but the rings are
surface markings, 3-5 being on each zonite. A suck-
ing disc exists at one or both ends, the hinder one
usually large, the anterior small, often spoon-shaped,
sometimes shielding the head. Secondary lateral
suckers exist on the feet of Branchellion and on the
head of Branchiobdella. The cuticle is smooth, rarely
warted (Pontobdella), bristled only in Acanthobdella,
ciliated in Malacobdella. The dermis is of loose,
round, or angular connective cells, often with stel-
late or branched pigment cells (Piscicola), and in
it are two kinds of unicellular glands, a superficial set
pouring out mucus, either universally distributed or

* Macrobdella, from Valdivia, is the giant of the order, measuring 2°5’. '

Introduction to Animal Morphology. 199

only at the mouth and sucker (Piscicola, Branchio-
bdella), and a deeper, secreting a chitinous material
which constitutes the “cocoons” for the eggs. These
are only developed during oviposition. There are
three laminz of unstriped muscular fibres, circular,
radiating, or sagittal and
longitudinal, having a rich
development of connective
tissue between the fibres.
Some of the second set stretch
laterally from the dorsal to
the ventral surface; of these
radial fibres, mixed with con- , Transverse section of Leech; @»,

dorsal vessel; z, digestive canal; mz,

muscular wall; wx, ventral nerve

Bective. |tissue,,.the suckers 227. © scsmental creat 2 paren,
chiefly consist. There is rarely “2; /® !#teral vessel.

a body cavity (Branchiobdella), but such may exist in
the embryo, though absent in the adult.

The nervous system consists of a ventral cord
dilated into ganglia at regular intervals (twenty-
three in the common leech,
twenty-one in Clepsine,
Baudelot). In the young
these are two lateral cords,
which remain apart in Ma-
lacobdella (Fig. 27, C), but
approximate and often fuse
inothers. Theanteriorand
posterior ganglia are the
largest, and are knotted;
four are fused anteriorly in
Clepsine ; seven in Hirudo ; ar generative organ of Leech; g,

gland; s, seminal vesicle ; 2, penis; Z,

o s testis; d, vas deferens; 0, ovaries; v,
seven posteriorly in Clep- uterus; B, digestive canal of Leech,

showing cca; C, nervous system of

sine. Above the pharynx, 3onesaa

200 Lntroduction to Animal Morphology.

branches of the first ventral ganglion unite to form an
upper, lobate, pharyngeal ganglion, made of several
little clumps of nerve cells. No branches arise from
the inter-ganglionic cords, but the twigs from the
ganglia are numerous and symmetrical. An indistinct
third central cord may exist in some parts of thenerve
axis. The neurilemma contains muscle-cells, and is
double, the layers being separated by pigment cells.
A single nerve lies beneath the intestine, send-
ing branches to the ceca. It has ganglion cells
along its whole course. Curious sense-organs exist
in the form of ‘‘ cup-like organs,’ most abundant on
the head, and hinder, but not hindmost, rings. Each
of these is a little depression covered by clear cells,
and having a nerve twig terminating in the centre
(Hirudo, Hemopsis, Nephelis, &c). These resemble
the organs of Semper in Gephyrea, or, more remotely,
the lateral line organs of fishes. Some of these have
pigment flecks, and are then considered eyes, but they
are possibly only general sense-organs; of these there
may be two (Clepsine), four (Piscicola), eight or ten
(Hirudo). In the common leech they are in two series
on the 1-3rd and 5-8th rings. In it, also, a row of
white spots on the horizon of the eyes marks the
division into zonites. Limbs are absent, or as flat
lateral appendages (Branchellion, Branchiobdella).
The mouth is in or below the anterior sucker, lead-
ing into a muscular pharynx, sometimes protrusible as
a proboscis, which has then special retractor muscles,
and no teeth. Others have 2-3 plates of calcified
chitin (jaws), with serrated edges (teeth), or unarmed.
Brown, oral, salivary cells may line the pharynx,
opening outwards like the glands of Trematodes. The

Introduction to Animal Morphology. 201

cesophagus may be long (Hzementeria), or short, but
the stomach is long, with alternate dilatations and
contractions (Pontobdella), or with lateral ceca; of these
Clepsine has six, Hirudo nine, Piscicola ten, Aulaco-
stomum only two. These may be branched as in Clep-
sine, reminding one of a dendroccelous Turbellarian.
The pylorus is surrounded by a sphincter, and the
straight intestine runs often between the two hindmost
czeca, which are longest, the only ones present in
Aulacostomum. The intestine may also have ceca
(Clepsine) and a pre-anal dilatation (Piscicola). The
anus is dorsal above the hinder sucker.

The circulatory system contains often red blood,
the colour residing in the fluid, seldom in the corpuscles.
In most, the blood flows in the nearly obliterated
body cavity which here exists as a system of sinuses.
These may form two lateral pulsating vessels, and a
median sinus divided by the viscera into dorsal and
ventral vessels, which in Clepsine and Piscicola have
valves, but these around the pharynx are continuous
as a vascular ring, and freely anastomosing ; lacunary
branches from these vessels complicate their relations ;
some of these are contractile spacesin Nephelis. These
lacune permeate freely the spongy dermis and mus-
cular layers. Respiration is dermal, and the lateral
vascular organs in Branchellion and Ozobranchus
may also be for breathing purposes.

The excretory organs are tubes with glandular
walls, symmetrically arranged along the ventral
aspect, varying from two (Branchiobdella) to seventeen
(Hirudo), either closed internally, or opening within
by a ciliated, funnel-shaped orifice, while the outer
opening maybe on a lateral wart. A primitive set of

202 Introduction to Animal Morphology.

three pairs of these “segmental”? organs develop,
separate from the primitive streak, on the hinder half
of the abdomen. These never open inwards, and
vanish when the permanent segmental organs appear.
Sometimes the wide, pouch-like forms open internally
into plexiform canals, formed of an aggregate of large
cells with branching spaces between them. These
are not sexual in function.

Leeches are mostly hermaphrodite, but not self-im-
pregnating. The sex-organs resemble those of Trema-
todes, as a symmetrical pair of eachkind exists, opening
ventrally. The testes are either two simple pouches.
(Pontobdella), or else a row of glomeruli* (Fig. 27, A, Z)
on each side, whose efferent ducts unite in two lateral
longitudinal vasa deferentia, dilating near their end
into seminal vesicles, whose ducts unite ; an accessory
gland (sometimes acinose, Clepsine) secretes an.
albuminous matter, which unites the spermatozoa into
clumps (spermaphores). The end of the duct may be
protrusible as a penis, or there may be a special penis
sometimes armed with recurved hooks (Branchio-
bdella). The male organs open in front of the female..
In Branchiobdella the sixth segment wall secretes the
semen, which escapes by two canals to a glandular
pouch at the base of the penis. There are two
Ovaries and oviducts, often with an albumen gland at
their confluence into a dilated sac (uterus). The eggs
are enclosed in a smooth or rough capsule or cocoon,
surrounded by fluid albumen, within which the embryo
begins to creep, developing a pharynx ; then a primi-
tive streak forms, on which the ventral nerve cord

* Five pair, Ichthyobdella, Branchellion; 6, Piscicola ; 8, Hzemopsis ;
9, Hirudo; 12, Aulacostoma.

Introduction to Animal Morphology. 203

develops, each ganglion being primitively double;
later appear the sex-organs and a series of solid
oblique cell buildings, which, becoming hollowed,
form the segmental organs. In some (Piscicola) the
ova are cells detached from the wall of the ovary; in
others (Nephelis, Clepsine, Hirudo) a thin, tortuous
protoplasmic rachis forms in the ovary, from which
the eggs bud as grape-like masses, and become de-
tached. Fossil leeches have been found in the Litho-
graphic slate.

The forty genera may be grouped in a single order, con-
taining six families :—

1. Malacobdellidee—dicecious, soft, flattened, ciliated, not
ringed; pharynx protrusible; anterior sucker none; the
colourless blood flows in two lateral and one dorsal vessel ;
two chains of lateral ganglia (Fig. 27, C), the terminal ones
of which are united by long commissures; parasitic on Mol-
lusca; in some respects allied to Amphiptyches. 2. Acan-
thobdellida—hermaphrodite, spindle-shaped, flat ; anterior
end with a bundle of bristles at each side; anus in the pos-
terior sucker. 3. Histriobdellide—dicecious; hinder part
split into two movable processes; head with tentacle-like
processes; two horny jaws in the pharynx, and a simple in-
testine; they live on lobsters’ eggs. 4. Branchiobdellide—
moncecious, round, unequally segmented, papillose; head-
lobe separated from the oral sucker; two jaws, one dorsal
and one ventral, in the pharynx; anus over the posterior
sucker; genital opening medio-ventral. Branchiobdella is
eyeless, and lives on the gills of crabs. Temnocephalus has
a lobate head and two eyes. 5. Clepsinide—moncecious,
short, flat, gradually enlarged in front, with three rings in
each metamere ; anterior sucker present or absent, with no
jaws and a protrusible pharynx ; anus over the hinder sucker ;
eyes present; parasitic on Molluscs, Fish, and Frogs.
Clepsine biocvlata has the generative openings between the
25th—6th and the 27th-8th rings ; it carries its young fastened

204 Introduction to Animal Morphology.

under its abdomen for a while. Hamenteria has a mouth in
front, not in the middle, of the sucker, in a protrusible pro-
boscis ; both genital openings are on a common wart; the
glands about the neck pour out an irritating secretion, which
cause urticaria in the human subject. Piscicola has a linear
body with wide anterior genital openings, and is not capable
of rolling itself up. 6. Hirudinida—hermaphrodite ; nar-
rowed in front and behind; four or five rings on each meta-
mere; an anterior sucker present; pharynx slightly protru-
sible, with three toothed jaws; anus over the hinder sucker.
Pontobdella has six eyes, and both suckers are on narrowed
ends; the body warted, not ringed; they are ecto-parasitic
on Fishes. Branchellion has, on each edge, twenty-six leaf-
like processes ; they are not ringed, and have 4-8 eyes; living
on the gills of the Turbot and Torpedo, &c. Ichthyobdella
is elongated, obsoletely ribbed, with 4-8 ocelli and sub-
elliptic suckers. Hzmopsis has ten eyes and jaws as
hardened folds of the pharynx. These do much mischief, as,
when young, they are taken in by cattle with the water which
they drink, and attach themselves to the pharynx, and even
may enter the wind-pipe. ‘Trochetia has toothless jaws, and
genital openings between the 32-3 and 37-8 rings. Aula-
costomum (Horse-leeches) are cylindrical, with the hinder
lip of sucker obliterated; caca small, or none; intestine
wide ; anus large; genital openings in males between 24-5
rings, in females 29-30. Hirudo has the first disc ringed,
not separated by a constriction from the flattened body ; eyes
10; jaws 3, Semilunar, with 30-100 teeth, and 100 rings on
the body. H. medicinalis, the German leech, is dark green,
with black spots below. H. officinalis, the Hungarian leech,
is olive green, without spots below ; each jaw has 70-90 teeth
each, with two roots. The sex-openings are as in Aulacosto-
mum. They take three years to become sexually mature, and
live 18-20 years. The cocoons are laid in summer and
winter, and the young embryo begins to creep in 4-6 weeks.
A few retain the cocoons attached to their bodies, thus ap-
pearing viviparous.

The thirst for blood in leeches can be increased by putting
them in a mixture of wine and water, or one part of vinegar

Introduction to Animal Morphology. 205

and eight of water. Trachelobdella has no ocelli, and a
round retractile neck (found on Gobius Capito). Bdella
has a deep grove on the under side of the fore lip. Podo-
bdella is elliptic, closely ringed, without eyes or teeth, and
with a stalked sucker. Pinacobdella has an elongate body,
with seventeen dorsal scutella and no eyes. Typhlobdella
sub-lanceolate, with 81-93 rings, three jaws, no eyes; it in-
habits the subterranean waters of the Baradla cave at Aggtelek,
Hungary. Its orifices are as in Hirudo.

CLASS 8. ONYCHOPHORA (Grade).—One genus
(Peripatus) with an elongated, cylindrical body of
several metameres, head lobes and mouth segments
united, and with two frontal feelers and two eyes.
The mouth is very shortly protrusible, with two
parallel, hook-like teeth. The pharynx is short,
divided into a wide anterior and a narrower posterior
part. The stomach forms a simple tube, ending in a
short narrow intestine. There is a soft epidermis, a
connective dermis, three muscular layers as in leeches,
and no surface bristles ; but each of the down-directed
feet bears a single, double, or multiple chitinous claw.
The vascular system consists of a single dorsal stem.
Two lateral canals exist imbedded in the muscular
lamine, which may also be vessel stems, but they
have a glandular lining (Grube). No other excretory
organs are described. The nerve system consists of a
pair of closely united, large ganglia above the
pharynx, which send branches on each side of the tube
to unite below. Two diverging, ventro-lateral cords
arise here, which unite at the end, and the two cords
(which are coated with nerve cells) are joined by many
fine commissural threads. There are six single
branches from the cord in each metamere, but there
are no special ganglionic differentiations in its course.

206 Introduction to Animal Morphology.

They are moneecious, myriapod-like, and live in damp
earth. P. juliformis, &c., inhabit the Antilles. P.
Cayennensis and Chilensis, South America, others
are found at the Cape of Good Hope. L£/ers refers
these to Arthropoda, Van Beneden to Cotylide.
Schneider places them beside Hirudinea.

CHAPTER 7OXX.
PROVINCE 2.—DEUTEROSTOMATA.

THIS province includes two sub-provinces, differing
according to the method of the formation of the
celoma. The first of these, Enteroccela, includes
those in which the body cavity is formed as an out-
growth from the digestive sac, and includes two
classes. .

CLASS 9. CH2TOGNATHA (Leuckart)—free, marine,
moncecious, cylindrical forms, 3” —1” in length, divided
into a head, body and tail; the last is margined by a
striated fin,* an expansion of the cellular cuticle, and
one or two pair of similar fins may lie farther forward.
The surface is often bristled, and in Sagitta draco a
lateral bundle of these acts as afin. The muscular
‘fibres are striped, in four longitudinal bundles, sepa-
rated by dorsal-ventral and lateral lines. The head
has 4-6 sets of pre-oral sete, and on each side of the
slit-like ventral mouth a lateral set of prehensile
hook-like bristles.

* The fins seem to be bristles united by a cuticle. The bristles are
brittle, arising in follicles.

Introduction to Animal Morphology. 207

The intestine is straight, attached medio-dorsally
by a longitudinal band to the body wall, medio-ven-
trally by interrupted mesenteric threads, traversing
which, close to the ganglion, is a.vessel. The anus is
ventral, near the hollow tail, which is divided by a
partition, and in which spermatozoa form from proto-
plasmic masses detached from its walls, and escape by
lateral slits, to which sometimes seminal vesicles are
appended. There is a saccular ovary on each side of
the intestine, opening beside the anus. An oval,
ventral nerve-ganglion (=the cephalic ganglion of
Nematodes) sends backwards a pair of lateral branches,
and forwards another pair which unite pre-orally in a
hexagonal ganglion. This sends off lateral branches
to the conical tentacles when they exist (S. cepha-
loptera), and two anterior branches to the pair of eyes,
which consist of radially arranged crystal cones on a
nervous layer and mass of pigment.

Sometimes a dorsal, wheel-like disc exists, placed
like a saddle. The non-ciliated embryos are directly
developed, the egg passing through a gastrula stage.
The one genus Sagitta is found in the Mediterranean
and Atlantic. Chetosoma is probably one of its
nearest allies. They have been regarded as Verte-
brates (JZezssner), or as Molluscs (forbes).

CLASS 10. ENTEROPNEUSTI (Gegendaur)—worm-
like, brittle, contractile, dicecious animals, flattened,
except at a collar-like swelling in front, and consist-
ing of two, lateral, flattened parts, and a middle annu-
lated portion showing traces of metameric growth.
The finely ciliated, protoplasmic cutis secretes much
mucus by its unicellular glands. The muscular coat
is strong, the two, lateral, longitudinal bundles of fibres

208 Introduction to Animal Morphology.

not continuous mesially ‘above or below; the circular
fibres are stronger below. Anteriorly there is a hollow
proboscis (sipho) for boring in the sand, with a round
opening at its free end,and a triangular one below.
This is separate from the digestive canal, and being
near to the pharyngeal ganglion is probably a sense-
organ like the grooves of Nemerteans. The mouth is
large; the intestine, for the most part fused with the
body wall, has lateral hepatic ceca containing a
greenish fluid, is often full of sand, and has a terminal
anus.

The digestive canal in front bears a curious respi-
ratory organ, supported on a basket-work of homo-
geneous cuticular (chitinoid ?) rods, which in arrange-
ment and genesis resemble the branchial skeleton of
Amphioxus. Between these gill arches are vertical
slits (like those of a Tunicate or of Amphioxus) for
the exit of the water which, entering by the mouth,
bathes the vascular, ciliated, branchial membrane
stretched on this framework. Each rod consists of
three vertical plates, joined by transverse bands, and
they are in contact at their outer end. These arches
only surround the dorsal half of this region of the in-
testine, and the incurving of the lower ends of the
arches constricts the cavity so as to make it, in vertical
section, somewhat resemble the figure 8.

The intestinal walJl within exhibits two ciliated
furrows, from which branching grooves pass in several
directions, forming a ciliated network. The ovaries
are red, the testes white, lying in the lateral parts of
the body, and shining through the skin. There are
usually four series of sex-glands. The embryos are
girdled by a single crown of cilia (AZecznzkof/), and

Introduction to Animal Morphology. 209

early become constricted into an acorn-like anterior
part, becoming the proboscis, and an oval body.
There are in the adult four large vascular trunks,
dorsal, ventral, and two lateral; the first carries
blood from behind forwards, and divides at the gills
into four branches, of which one enters the respiratory
organ. There is one genus, Balanoglossus, whose
three species inhabit the Adriatic and the Indian
Ocean. The larva has been often confounded with

the pseudembryos of Echinodermata, and is named
Tornaria.

CTIAPTER. 22 XX,
SUB-PROVINCE 2.—SCHIZOCGLA.

CLASS 11. CH#TOPODA (Vaz Beneden).—The single
class of this sub-province includes the Deuterostome
worms whose cceloma is formed by a splitting of the
germinal layers. They are cylindrical or flattened,
of several (2-400) metameres or zonztes.* The first
(prostomium), second (peristomium), and last are
heteronomous, the others homonomous.t Some secrete
a cuticular or calcareous tube, or agglutinate sand
into a case. Each zonite bears bristles, rarely scat-
tered over the surface, usually in diverging bundles,
often around a central aczcula or seated on a forus, and

* Echinoderes and Turbanella are intermediate between the simple and
truly jointed forms.

+ Or some central zonites heteronomous from the development of the
sex-organs.

Ie

210 Introduction to Animal Morphology.

raised on unjointed, movable side-processes of the
body wall (parapodia*). These bristles are chitinous,
striated, full of protoplasm, rarely hollow, calcareous
(Euphrosyne) ; they arise in follicles, and muscular
fibres are attached to their roots. When the cuticle is
hard the young bristles have often deciduous points
for piercing their way through the surface. There are
variously arranged dermal appendages or cirri, often
shield-like (e/ytvae) and iridescent, or groups of long
pillared suckers, as in Pelogenia, somewhat like the
ambulacra of an Echinoderm. Nettle-cells, or rod-
like bodies resembling them, are found in the tentacles
and cirri of Spionide, Cheetopteride, Ariciide, &c.
The cirri on the prostomium are thread-like (an/fenne),
or thick and fleshy (fa/fz). Those of the peristomium
are called tentacles. The tail has generally two long
Cine:

The cuticle is of many layers, soft and thin at the junctions
of the zonites. ‘The whole surface is rarely ciliated (Ichthy-
diidz). Polyophthalmus and Prionognathus have cilia in
bundles. Partial ciliation is common, especially on the ap-
pendages (Capitella has two ciliated head-lobes). The
cuticular lamine are often striated, the superficial and deep
striz crossing at angles of 70° or go°. Through these layers
pass pore canals, which may open on wart-like eminences.
The connective cutis is thinner than the cuticle, and contains
pigment cells, bacillar corpuscles, and glands, of four kinds—
uni-cellular (in Lumbrici) ; mucous, with an epithelial lining,
often lobate and numerous, either over the whole surface,
along the line of the cirri, or along the notopodia only
(Sphzrodorum); tubular glands in Nereids secrete globular
concretions; calcigerous dorsal glands in Serpulz, which

* These are rarely bristle-less, never modified into jaws. In higher
forms there are two pair on each zonite: two dorsal, one on ao side,
called Notopodia, and two ventral, Neuropodia.

Introduction to Animal Morphology. 211

secrete the tube in which the worm lives. The mucous
glands of the clitellum in earthworms secrete a chitinous
material, like that of the cocoon glands of leeches. The
sub-dermal layer may be nucleatéd protoplasm (Chztonotus),
simple, parallel, non-nucleated fibres, unstriped or striped,
longitudinal and circular ; sometimes each fibre has a cortical
and a medullary layer (Nephthys). The longitudinal fibres
are divided into tracts by dorsal, ventral, and lateral lines.
Oblique fibres cross from the neuropodia to the notopodia.
Deep processes of this layer form septa, dividing the body
cavity into metameric chambers, except at the front end,
where the first few segments have no partitions. In Polyoph-
thalmus, two longitudinal septa, below and free from the di-
gestive tube, attached to the medio-ventral and lateral lines,
cut off two long chambers from the general body cavity.
Direct openings into the body cavity exist in Lumbricus and
Enchytraeus.

The mouth opens on the peristome, and may have
a protrusible, cylindrical, club-like or leaf-like epi-
pharynx or proboscis, with a boring spine in some
Syllide. The mouth may have 1-5 toothed jaws,
often with hooks at the base, and the peristome may
have papille or tubercles. The cesophagus has some-
times simple salivary glands, and may dilate into a
muscular proventriculus, in which may be chitinous
teeth (Gnathosyllis) and glands. The digestive canal
is rarely divided into stomach and intestine, coiled in
Chloreema and Pherusia. It often has lateral ceca in
each metamere, simple or branched, with terminal
glandular pouches (Aphrodite). The intestine has, as
in Gephyrea, epithelial, basement, and muscular coats
(the last transversely striped in Phreoryctes). The
middle tract of the intestine may have a lining of
yellow or green hepatic cells, but has never separate
glands. In the lowest part, gland cells containing

PZ

212 Introduction to Animal Morphology.

little concretions may exist. The anus is terminal, or
dorsally sub-terminal.

The vascular system may be absent (Glyceria,
Tomopteris,* &c.) or rudimental. Polygordius has a
single dorsal vessel giving off cecal transverse
branches. Most worms have four longitudinal canals—
1, a pulsating dorsal vessel, double in
Nephthys, carrying blood from behind
forwards, lying in a cellular mass on
the digestive canal; 2,a ventral vessel,
rarely pulsating (Clymene, Maldania),
or double (Eunice)t; 3, two lateral
symmetrical trunks, usually accom-
panying the lateral nerves, rarely pul-
sating (Protula Dysteri). These stems
are joined by terminal and metameric
cross branches, some of which may bedi-
lated, acting as simple hearts (Szenurus,
&c., Fig. 28); these give off parietal and Citcnlainey adele
visceral branches, some of which end °f Senuris variegata,

showing the dorsal

Fig. 28.

and ventral vessels,

ceecally, but most others have a closed Ho patorerse snes.
or lacunary communication between (Ors saat tone ot
the arterial and venous branches. To °° %‘*!™

these branches contractile ceca may be appended
(Lumbriculus variegatus), which may lie in contact
with the ducts of thesegmental organs. Inthe cepha-
lobranchiate forms the dorsal vessel dilates into a pul-
sating sac (branchial heart) on the pharynx, sending
off gill-vessels, which return to the ventral stem. In
Polyophthalmus the dorsal vessel divides into lacunary

* In these the perienteric corpusculated fluid circulates in the body
-cayity, moved by the peritoneal cilia.
t+ There may be two dorsal and two ventral vessels in Hermella.

Introduction to Animal Morphology. 213

capillaries on the intestine. The blood may be color-
less, with colored corpuscles (Glyceria, Phoronis,
Dujardiniz), or more commonly is a yellow, green,
red, or blue serum with colorless corpuscles. The
color is often dissimilar in allied species.

Respiration may take place by the surface, by the
water admitted into the perivisceral cavity, or by gills
which may be modified, filiform cirri, over or under
the parapodia, or dermal, ciliated, comb-like, pinnate
or branched processes, into which often pouches of
‘ the body cavity enter, attached to the notopodia. In
the tube-dwellers there are long contractile threads in
bundles, or spirals, or fans, or tree-like, with a carti-
laginous axis of support (Sabella). Some of these
cirri may lose their respiratory functions, become
club-like, and act as opercula to the tube. This
operculum may have a calcareous, terminal disc
(Serpula), or it may be dilated into a brood-pouch for
the young (Spirorbis). In Fabricia, a temporary tube-
dweller, the operculum retrogrades into a simple
tentacle. The gillscontain either simple cecal diverti-
cula from the transverse communicating vessels, or
they may have separate inferent and efferent vessels.
Colobranchus has eight oval, ciliated (respiratory :)
laminze around the anus, and the lower end of the in-
testine is also ciliated. In Hesione, air bubbles have
been seen emitted both by the mouth and anus. In
some Syllide the periodic taking in and expulsion of
water from the intestine has been noticed.

Each metamere has usually a pair of symme-
trical excretory (segmental) organs, often acting as
ducts for the sex-glands. These may be simple
mucous pouches in Tubifex, Nais, &c., larger and

214 Introduction to Animal Morphology.

tortuous in Lumbricus, &c., having an internal funnel-
or rosette-like opening into the body cavity, followed
by a straight or coiled glandular portion, and a small
narrow outer orifice, often in the next metamere to
that wherein is the funnel. The ciliated canal below
the intestine in Protula may also be an excretory
organ.

The nervous system consists of a large double pre-
oral ganglion, each part often of 2-4 knots, sending
branches to the eyes and oral cirri. Its two compo-
nents may be close together (Enchytreeus), or sepa-
rated laterally (Aonis). Two lateral branches form a
ring around the pharynx, and unite below to form
two symmetrical chains of ventral ganglia, stretching
backwards, and giving off lateral branches. These
chains are remote from each other, and joined by
transverse commissures in the embryo and in adult
Serpule, &c. In other worms they approach in
the course of growth, and may coalesce into one cord
(anterior end of Terebella), in the centre of which runs
a thick distinct band of nerve tissue. The anterior
ganglia may be unequal (Clymene), and are usually
largest. Sometimes on each metameric branch at the
base of the parapodia little ganglia exist, also united
by longitudinal commissures (Pleione).

A special nerve system, homologous to the azygos
nerve of the leech, and analogous to the sympathetic,
lies on the intestine, connected to the pre-oral ganglia
on the cessophagus, and when there is an epipharynx
sending branches to it, it expands backwards on the
intestinal wall, having special ganglia of its own, and
differs in texture from the ordinary systemic nerves.

Sense organs are widely distributed. The cirri

Introduction to Animal Morphology. 215

of the anterior segments are sensitive, and may be
jointed. The ciliated grooves in Polygordius re-
semble those of Nemerteans. The eyes, usually on
the prostomium, consist of a pigment spot, a nerve,
and generally a lens, often 2-3 lenses on the one pig-
ment spot. They are rarely simple specks, usually
close to the ganglion. When there are four they are
rarely equal; one pair is generally large, and the
other only pigment spots. Branchiomma has many
eyes on its tentacles, Sabella on its gills. Each has a

A, section of body of Worm (peristomium) ; @, cuticle; 4, dermis; c, f, dorsal and
ventral muscular plates ; d, opening of the segmental organ; £, cceloma; %, dorsal
vessel; z, ventral vessel; g, intestine; 7, sexual organ; e, nerve ganglion. B, section
of Amphioxus. C, section of vertebrate embryo.

pigment spot, and diverging crystal cones on it.
Eyes exist in the tail segment in Fabricia, Amphi-
corina, and Amphiglena. Polyophthalmus has three
prostomial eyes resting on the ganglion, the middle
with three, the lateral with two, crystal cones. Each
succeeding metamere has also a pair of eyes sunk in
its skin, and receiving a nerve from the ganglion of
the segment. Myxicola has also metamericeyes. In
Torrea and Alciope the eyes are large, with a retina,
choroid, iris,and lens. Otocysts exist as simple trans-
parent vesicles on the pharyngeal ring of Arenicola

216 Introduction to Animal Morphology.

and Amphiglena, with many otoliths (in Fabricia and
Amphicorina with one).

The capacity of repairing injury is very great.
Reproduction may occur asexually by gemmation
from the penultimate segment, asin Nais, Chaetogaster,
Eolosoma, Myrianida, &c. In the last, A/z/ne Edwards
saw a chain of six continuous, the first with ten, the
second with fourteen, the third with sixteen, the fourth
with eighteen, the fifth with twenty-three, the sixth
with thirty joints. Of another species, Claws saw
12-16 new, four-jointed individuals in a chain. De-
tachment of some metameres, followed by the growth
of a head, is a form of fission occurring in some species.
Some species have asexual as well as sexual forms ;
the former give origin to the latter by budding. They
are dicecious, except Lumbricus, Protula, Amphiglene,
Spirorbis, and some Serpule, and often dimorphic.
In Lumbricus the sex-organs are in a limited number
(mostly 8-15) of zonites, the glandular layers of the
integument of which are swollen dorsally and laterally,
forming a saddle-like eminence (clitellum), which is
separated from the lower unthickened part by a
muscular ridge on each side. The ventral sete of
this region are clasping for copulation. Each hasa
single bristle. There are two pairs of testes, con-
nected to which are wide saccular vesicles into which
the semen passes. In each of these vesicles is a pair
of funnel-like organs, ending in a vas deferens, which
on each side unites with its neighbouring vessel, and
passing backwards, opens at each side in the base of
a bristle-like copulatory organ on the fifteenth ring.
The orifices have glandular lips. The spermatozoa
are short thin threads with swollen heads. The pair

Introduction to Animal Morphology. 217

of ovaries are small, behind the testes, having two
wide-mouthed oviducts behind them, attached to the
body wall; with these communicate round sperma-
thecal sacs lying near the testes. The oviducts open
anteriorly to the penis. In the earthworm six segments
in advance of the clitellum are the copulatory, ad-
hesive organs, which are modified, imperforate, loco-
motor sete. Most other worms have no _ special
genital ducts, but empty the sex-products through the
segmental organs. The ova may form on the inner
wall of the dissepiments, or of the body cavity
(Tomopteris), or in 1-3* pair of ovaries, and the semen
in 1-4 pair of testes. Each sex-organ has a vessel or
acellular string in its axis, from which the sperm
cells or eggs bud.

The ova are either single or in clusters
within capsules, cocoon-like in Lumbricus,
pillared in Arenicola, with copious or no
albumen (Tubifex). A few (Eunicea, Syllis, 2477838

=
POLI bd} |W

Cirrhatulus) are viviparous. Lumbricus de-
velops directly. Most of the others have in-
direct development by a dissimilar larva.
This has no gastreal stage, according to
some observers, and may be ciliated at the
extremity (Telotrochal), at one end only
(Monotrochal as in Polynoé), or at both ends
(Amphitrochal as in Terebella), or ciliated in
the middle (Mesotrochal as in Spiochaetop- Polytrochal larva of
ee renicola,

terus), or with many wreaths of cilia (Poly-_

trochal as in Arenicola, Fig. 30). Lysidice has five ciliary

* CEnone diphyllidia has in the side of each ring two little grape-like
ovaries, whose common oviduct opens at the base of the parapodia.
Euphrosyne has symmetrical ovaries extending as winding pouches, opening
at the back of the inner edge of the gills. Chloeia has lobed ovaries, each
lobe a long pouch.

218 Introduction to Animal Morphology.

wreaths and a ciliated ventral surface. From these larve the
head becomes differentiated with its two segments; then the
tail, the cilia are lost, and intermediate segments form by
gemmation. Spirorbis and Pileolaria have brood-pouches.
wherein the embryos pass their early stages of development.
Some retrograde in growth, e.g., many Cephalobranchs have
eyes and otocysts, which are lost afterwards.

About 1500 species are known, none of which are true
parasites, though some are commensals; thus the larve of
Alciope live in Cydippe, Lepidonota cirrhule in the tubes of
Chaetopterus insignis, Nereis fucata in shells occupied by
Paguri, and a little Amphinome in Pentelasmis anatifera.
They are mostly marine, littoral, a few freshwater or terri-
colous. They are divisible into four orders :—

1. Oligocheta (Grube, Scoleina, Gegendbaur)—mostly terres-
trial or freshwater, with few (2-8) rudimental bristles in each
cluster ; no tentacles, gills, nor cirri; mostly hermaphrodite.
This includes the following families :—1. Ichthydiide—un-
segmented, or with segments only indicated by bristly and
ciliary wreaths; head ciliated. Ichthydium is not bristled,
while Dasydytes is bristle clad, with a simple truncate tail,
and Chetonotus with a forked tail. Taphrocampa, allied to:
these, has a mastax like a rotifer. 2. Naididae—segments
few ; skin thin; head lobes united, often prolonged ; bristles
in two rows; eggs simple, single, large; hard-shelled in
Aelostoma. Aulophorus secretes a tube which it carries.
about; its upper bristles are hair-like, the lower stiff.
Mesopachys has all the bristles hair-like. Nais has its under
row of bristles fixed. 3. Enchytraide—bristles two-rowed,
equal, awl-shaped (Enchytreus), or hook-like (Parthenope) ;
mouth segments united ; blood colorless; eggs large, singly
includedincapsules. 4. Tubificida—mouth segments united,
often lengthened; skin transparent; four rows of simple
(Enaxes) or forked (Saenuris) bristles; eggs large, without
albumen, severalin one capsule. 5. Lumbricidee—cylindrical,
many-jointed, with a clitellum (except in Helodrilus and
Criodrilus) ; prostomium free (except in Criodrilus); skin
opaque; head lobes conical ; bristles hook-like, two or more
rowed, or over the whole surface (Pericheta); eggs many,

Introduction to Animal Morphology. 219

with albumen, and in a common capsule ; eyes none; blood
red; mouth unarmed. Lumbricus, the common earthworm,
has two-rowed hooked bristles, three salivary, several ceso-
phageal glands on the thirteenth ring, and a muscular
stomach behind the proventricle or crop in the fifteenth ring ;
it has two pair of testes and five pair of capsuligenous glands.
Pontoscolex lives in the sand of the Red Sea. Phreoryctes
lives in wells. Hypogeeon reaches an enormous size, as does
Megascolex.

2. Gymnocopa (Grube)—body long, flat, not sharply seg-
mented, in front broad; parapodia only developed in front,
two lobed, without bristles, but the two or four short frontal
feelers and the two long tentacles are bristled; eyes two;
mouth with no epipharynx nor teeth; segmental organs with
a rosette-like opening ; dicecious; marine. This includes one
family and two genera, Tomopteris and Esclischoltzia.*

3. Notobranchiata (Schmarda)—gills various or rudimental,
appended to the notopodia, vascular ; eyes and cirri various ;
parapodia usually present. Family 1. Polyophthalmidet—
small, marine, free, with few segments, no parapodia; head
three-lobed, with no cirri; a protrusible unarmed epipharynx ;
eyes before described; they are passage forms between
Naididz and Serpulide. 2. Halelminthide—parapodia, ap-
pendages and eyes absent; body in a membranous tube, ex.
Capitella. 3. Maldanide—long, round, unequally segmented,
living in tubes in sand; prostomium flattened, with entire
(Clymene) or split margin; no eyes, gills, nor feelers ; para-
podia bilobed; epipharynx club-shaped, often papillose
(Notomastus). 4. Chetopteride—zonites heteronomous ;
body divided into three regions, living in leathery or stony
tubes ; gills none ; head segments with three feelers; eyes 2
(Chzetopterus), or none (Spiochetopterus) ; larva mesotrochal.
5. Halonaide—with no parapodia, but with appendages and
eyes, ex. Dero, with caudal, branchialappendages. 6. Aphro-
ditide—segments unequal, with dorsal, shield-like elytrae ;

* This name is pre-occupied.
t Families 1, and 2, and 5 are made the types of a separate order
Haloscolecina by Carus.

220 Introduction to Animal Morphology.

head-lobes developed, with a single tentacle and lateral
antenne and palpi; eyes sessile or stalked (Pontogenia,
Hermione) ; gills small, simple ; epipharynx mostly with two
upper and two lower teeth and jaws; vascular system often
rudimental ; one central tentaculum and lateral antenne, and
sometimes palpi. Polynoé has no _ prostomial tubercle;
eyes 43 12-35 pair of elytrae. Gastrolepidia has ventral as
well as dorsal scales. Aphrodite, the sea-mouse, has an
oblong body, iridescent elytree on the 2-4, 5-7 *** 23-25-28,
&c., segments; eyes sessile, facial tubercle under the single
frontal tentacle. Iphione is oblong, with two lateral head-
lobes and two frontal tentacles ; noto- and neuropodia united.
Acoétes has two eyes, and no facial tubercle. 7. Palmyride—
elytra none: each segment covered by a fan-like group of
paleaceous scales; dorsal cirri alternating with tubercles ;
segments many “Bhawania), or few; eyes 2 (Palmyra) or 4
(Paleanotus). 8. Amphinomide—angular or flat ; segments
equal, not many; head small, usually with five tentacles ;
toothless ; gills dorsal, comb- or tree-like; bristles hair-like,
serrate, not acicular; head-lobes often compressed; pro-
stomial caruncle may be long, each segment carrying several
branched gills (Euphrosyne); the caruncle is absent, and the
head-lobes small in Hipponoé, or there may be round head-
lobes with frontal feelers, and two bipinnate gills on each
segment remote from the feet (Chloéia), or at the point of
the feet (Notopygus). The head caruncle may be heart-
shaped (Amphinome), or with leaf-like lateral lobes (Her-
modice). 9. Euniceide—rounded, long, with many meta-
meres, flattened ventrally, living in sand-burrows; head-
lobes notched in front, with 1-5 tentacles; several separate
upper, and two, often united, lower jaws; parapodia simple,
with acicula; gills either beside the dorsal cirri, simple,
comb-shaped (Eunice, Onuphis), or spiral (Diopatria), or
else absent (Lumbriconereis, Lysidice), or replaced by leaf-
like dorsal cirri (A®none, Aglaura). 10. Nereide—body
long, with two anal cirri; head flat, small, with four eyes,
two small middle and two large outer feelers ; peristome with
eight feelers; epipharynx protrusible, with two large hori-
zontally movable jaws, armed with denticles; parapodia

Introduction to Animal Morphology. Dol

double, with acicula, and no hair-like bristles ; they may be all
similar (Nereis), or some of the dorsal cirri feather-like (Den-
dronereis, &c.) 11. Nephthyide—body long, many-jointed ;
lateral feelers small; peristome with no cirri, but with para-
podia and papillz in place of teeth. Nephthys, the “ hairy
bait” of fishermen, has one anal cirrus. 12. Glyceride—
many ringed segments; proboscis club-shaped, protrusible ;
bristles with acicula; gills short, or none; chylaqueous
fluid colored in some by red corpuscles; vascular system
none. The proboscis may have four hooked teeth with no
points (Glycera), or rows of pointed teeth (Glycinde).
13. Phyllodocide—long, many jointed; head lobes small;
feelers 4-5 ; eyes 2-4; epipharynx with papilla ; ventral cirri
leaf-like; larvee monotrochal; the cirri leaf-like, covering
‘the back (Phyllodoce), or leaving it mostly uncovered
(Eulalia). These genera have four pair of prostomial cirri.
Eteone has two, and the leaf-like cirri do not at all cover the
back. Alciope has two large, Lopadorhynchus two small,
eyes. 14. Hesionide—few-jointed, with broad head-lobes
and long peristomial tentacles; protrusible unarmed epi-
pharynx, with no gills; oars one- (Hesione, Oxydromus) or
two-branched (Ophidromus), or with an upper tubercular
branch and two delicate teeth (Castalia). 15. Syllide—
elongated; head with tentacles, often with eyes; peristome
with 2-4 cirri, often united to the prostomium; pharynx not
protrusible, sometimes toothed, or with a chitinous tube which
bears a boring spine; oars one-branched, with two aciculate
bristle-clusters ; ventral cirri short, or none; blood colorless,
but with colored corpuscles in Dujardinia; circulatory organs
undeveloped or rudimental ; the sexes are dimorphic ; repro-
duction often by budding; there may be a metagenetic con-
dition, the product of the development of an egg multiplying by
gemmation; but itself remaining sexless (Autolytus). Oophylax
and Paedophylax carry their eggs about until they develop.
Gnathosyllis has pharyngeal jaws. Schmardia and Grubea
have a dagger-like pharyngeal organ. 16. Leucodoride—
segments heteronomous, a few being small; prostomium with
one thick and two little feelers ; peristome with two long re-
spiratory cirri; feet two-oared, with bristles, or bristles and

222 Introduction to Animal Morphology.

hooks; most are tube-dwellers, buried in sand or fastened
to stones; body transparent; eyes 2 (Disoma), or none.
17. Nerinide—segments homonomous; head with eyes;
feelers often none; feet one- (Pygospio) or two-oared
(Nerine). Spio has tongue-like gills. Colobrachus has a
peculiar anal breathing organ. 18. Cirrhatulide—rounded,
fusiform ; head with no teeth, feelers, nor tentacles; oars in
two series, on the lower hooks; thread-like gills on five or
six anterior segments (Dodecacerza), or on all but the first
and last (Cirrhatulus). Andoninia has spindle-like blood
corpuscles. 19. Ariciide—with no feelers nor teeth, and
generally four eyes; segments short; oars two-branched.
The epipharynx is leaf-like in Anthostoma, protrusible in
Ephesia, which is eyeless, but not protrusible in the four-
eyed Sphzrodorum. 20. Opheliide—feelers and eyes none;
zonites few; oars small, one or two only with bristles, one
set of gills limited to the middle of the back (Ophelia), or on
nearly every segment (Travisia) ; head pointed ; tail papillary ;
body flat beneath, with (Ophelia) or without a definite ‘ sole”
(Ammotrypane). Ophelia has in its perivisceral fluid stellate
bodies with immovable processes. 21. Arenicolidze—head
small, conical, with no eyes nor feelers, and a papillary pro-
boscis ; the middle segments have tree-like gills, while the
front and tail segments have none; oars double, the upper
bristled, the lower hooked ; the larve are polytrochal; they
burrow in sand. Arenicola, the “ lug-bait,” has no tail ap-
pendages. Scalibregma has anal cirri. Eumenia has gills
on the anterior segments.

4. Cephalobranchiata—mostly tube dwellers, with breath-
ing organs on the head, either as long contractile threads, or
fan-like, or spiral; pinnate or comb-like lobes, and sometimes
tree-like gills on the prostomium; some have dorsal cirri,
likewise respiratory ; noteethnorepipharynx. 1. Pheruside—
free, and peristome bristle-less; gills of simple threads,
surrounded by a girdle of long, yellow, thick bristles ; zonites
not ringed ; parapodia with upper linear and lower hook-like
bristles ; blood green; body often shaggy, with sometimes
terminal suckers, whereby they adhere to foreign bodies
(Chlorzma Dujardinii is found adherent to Echini) ; intestine

Introduction to Animal Morphology. 223

coiled; stomach with a spiral appendage. Siphonostomum
gelatinosum has two ciliated head-lobes. 2. Hermellidae—
tubicolous ; segments heteronomous, of two or three kinds,
the hinder thread-like, with no appendages; the head-lobes
are fleshy, cylindrical (Sabellaria), or leaf-like, split (Centro-
corone) with a circlet of yellow palez on the prostomial
border, which acts as an operculum. The tube is built of
cemented shells. 3. Terebellide—inhabiting soft, fragile
tubes ; heteronomous with two regions; head with neither
palez nor lobes, but with large, movable, ciliated gills, serving
as touch- and prehensile organs; in most there are 1-3 pair
of tree-like gills on the first body-ring, sometimes with a
jointed framework. Sabellides has lateral, thread-like gills ;
Polycirrhus none. Terebellides has the gills on an azygos
medio-dorsalcolumn. 4. Amphicteneide—tubicolous, hetero-
nomous, with three body regions; prostomium united to the
peristome, with a middle lobe and two bundles of thread-like
gills; tail segments with imperfect rings ; gills simply (Pecti-
naria) or complexly comb-shaped (Scalis), or elongated ; anal
cirri one (Scalis), or two (Amphicteis). 5. Sabellide—
tubicolous, heteronomous, with two body regions; head-gills
pinnate, in two circlets or spirals, one of which may be rudi-
mental; some have eyes on the cirri; the tube may be
temporary (Amphicorina, Fabricia) open at both ends.
Heterosabella has no sheath for the body. Myxicola has two
head-eyes, four tail-eyes, and forty pair of metameric eyes.
Phoronis has the gills on a horseshoe-shaped lobe ; body not
ringed, with no parapodia; blood with red corpusclés; its
larva is the form called Actinotrocha. The tube in Sabella
is open only at one end, and membranous. Protula has a
ventral dermal expansion. PP. Dysteri is hermaphrodite.
6. Serpulide—tubicolous, heteronomous, with two ciliated
skin folds on the front segments; the gills have a spiral basis,
with one or two opercula with chitinous or calcareous discs ;
blood red, green, or blue; the tubes are attached to stones,
&c., calcareous, worm-like (Serpula), spirally rolled (Spi-
rorbis), or free (Ditrupa). Filograna has eyes at the base of
the gills.

224 Introduction to Animal Morphology.

Chzetopod worms have existed since the days of
the Cambrian formation (Arenicolites, Histioderma,
Helminthites), possibly since the Laurentian (Scoli-
thus?). Tube dwellers are found in Silurian and
Carboniferous rocks.

CHAPTER: XXL.
CLASS 12.—BRYOZOA* (Ehrenberg).

COLONIES with tree-like, or membranous, fixed stocks:
(polyzoaria) supporting numerous persone in cellsf,
and composed of an outer chitinous or calcareous
ectocyst or cuticle, and an inner endocyst or dermis
(rarely absent as in Rhabdopleura). They are rooted
by a process of the ectocyst, and bear the cells for the
moncecious persone on one or two sides of the stock,
or radially around it. Each cup rarely communicates
with its neighbour (except in Ctenosomata, where also
they have serrated mouths). They may be joined one
to arlother, or united by ccenenchyma, and the
branches joined by stolons. The ectocyst consists of
indistinct epithelial cells and often of calcified, vertical,
hollow fibres. The endocyst—soft, ciliated, and con-
tractile—lines each cell, and is reflected inwards at

* This and the next are probably Epiccelous (p. 47); and should probably
form a separate province. This class is also named Polyzoa (Zhomzpson).

t Cristatella, which has no ectocyst, glides along snail-like. Some
Selenariz move by their enormous vibracula. Lophopus, which has a
gelatinous ectocyst, is also capable of locomotion.

Introduction to Animal Morphology. 225

the cell mouth to be continuous with the outer mem-
branous investment of the tentacles. It consists of a
layer of large, irregular, connective cells with (distally)
or without (proximally) a nucleated intercellular sub-
stance. Within is a layer of fine longitudinal and
transverse fibres, crossing each other at right angles,
and permeated by fine, netted canals containing oval
corpuscles. Each polypide or persona is lodged in a
cell, and possesses a crown of 8-80 ciliated, hollow, oval
tentacles* (branchiules, vaz Geneden) like those of
Chaetopoda, whose cavities communicate with the
cceeloma; each tentacle consists of an outer wall of
round, often nucleated, cells, and an inner structure-
less layer. They are seated on a basis or lophophore,
either horseshoe-shaped, as in all the freshwater
genera, except Paludicella and Urnaria, or else cir-
cular, as in all the marine forms except Pedicellina
and Rhabdopleura. The former group have a buccal
shield, valve or epistome (homologous with the foot of
a Mollusc) arching over the mouth, and the tentacles
are often united for }-{ of their extent by a basal
membrane forming a calyx. The epistome is not to
be confounded with the operculum of the cell, an ecto-
cystic process found in Myriozoon and Chilostomum.

Three kinds of appendages (undeveloped person) are
found on the ectocyst of the colonies :—1. Avicularia—two-
armed graspers, with a calcareous basal part, in shape some-
what like a bird’s head, with a horny, sometimes serrated,
beak, and a movable limb or under jaw; between these there
is often a ciliated lobe. They are placed near the mouth,
and open and shut rhythmically, grasping prey. Three forms
are described—a. pedunculata, on a movable, often jointed,
stalk ; a. sessilia, with no stalk; a. immersa, sunk into a pit

* Often in multiples of four.

Q

226 Introduction to Animal Morphology.

in the surface of the ectocyst. 2. Vibracula, consisting of an
oval capsule with no basal part, ending in a long seta like the
lower jaw of Avicularia. 3. Oocysts—globular marsupial
cells, found in Chilostomata, receiving the eggs on extrusion.

Each persona consists of an oval sac filled with a
watery, corpusculated fluid, extending into the ten-
tacles, and in which the digestive canal floats. The
mouth of this canal can be partly protruded from the
cell by evagination, and can be retracted at will.
The mouth is simple, projecting, contractile ; its epi-
stome, when present, is globular or pyramidal, hollow,
ciliated externally, and raised by a special inner
muscle. A muscular pharynx leads by a ciliated
cesophagus into the non-ciliated intestine, from which
a cecal stomach depends, whose cardiac and pyloric
orifices are close together above. The intestine at
first widens, leads backward, and then, narrowing,
opens by an anus close to the mouth, but external to
the tentacles. The flexure of the digestive canal is
always concave towards the nerve ganglion. The
walls of the canal consist of an outer, thin layer of
contractile fibre-cells, disposed circularly, and an inner
of small, simple (hepatic) cells, thick, green, or brownish
in the stomachs of many genera. Marine forms have
often knotty thickenings of their muscle fibres. The
stomach is gizzard-like in many of the Ctenostomata,
and often contains chitinous teeth. In Bowerbankia
it has two opposed balls of dark, radiated fibres, and
is lined by small chitinous plates; in action the balls
elongate and approximate, and the radiating fibres
become parallel. Hislopea has a somewhat similar
gizzard. There is novascular system ; the perivisceral
fluid nourishes the tissues, and is renewed by osmose

Introduction to Animal Morphology. 227

through the intestinal wall. The fluid is aerated at
the tentacles or body surface.

Each persona has a yellow, oval or lobed ganglion
between the mouth and anus, sending two strong
branches to the tentacles and two to the cesophagus,
round which they make a ring (Fredericella, &c.)
Below this may be a sub-oral, pharyngeal ganglion in
a few cases (Dumortier). Serialaria and other cteno-
stomatous, branched forms havea colonzal nerve-system,
taking its origin from a ganglion at the base of each
branch of the stock, which unites by fine plexiform
branches with the nerves of each persona. This ex-
plains the consentaneous action noticed in a colony
such as Mimosella.

No special sense-organs exist, except perhaps the ciliated
body near the ganglion in Pedicellina; but many colonies of
freshwater forms show by their motions that they are sensitive
to light. The muscular lamina is never complete, but con-
sists of specialized bundles, which are—rst, two retractors of
the lophophore; 2nd, retractors of the polypide, from the floor
of the cell to the cesophagus; these lie in the axis of the
pillar in Pedicellina; 3rd, two rotators of the lophophore, in
the freshwater form ending in each corner of the crescentic
disc; 4th, retractors of the tentacles from the lophophore,
placed between each pair of tentacles, sending a branch on
each side; 5th, the levator of the epistome; 6th, Parieto-
vaginalis anterior, many short transverse bands from the
invaginated part of the endocyst to the protrusible part;
7th, Parieto-vaginalis posterior, stronger, behind the last, to
the permanently retracted part of the endocyst ; 8th, Parietalis,
annular body fibres, whose anterior fibres are the sphincter
vaginalis. Besides these, there are radiating fibres joining
the two valves of the Avicularia, and opercular muscles in
Chilostomum.

The irregularly rounded testes are either seated
2

228 Introduction to Animal Morphology.

directly under the stomach wall or attached thereto
by a funiculus or cord which passes from the stomach
to the hinder wall of the body cavity. The ovary is
anterior, near the top of the cell, attached to the inner
surface of the endocyst, sessile, pillared, or on a special
funiculus. The ova and spermatozoa pass into the
body cavity, and there probably impregnation takes
place. The escape of the sex products thence may be
by an opening in the body wall near the anus (Alcy-
onella, Farrella, according to JZeyer, van Leneden,
&c.) In Halodactylus gelatinosus, Membranipora
pilosa, &c., there is a canal with a ciliated, external
mouth, leading from the body cavity outwards, be-
tween the base of two tentacles, and joined to them.
The embryo, after cleavage, is ciliated and hollow;
soon an opening forms at one end into the hollow,
thus forming an intestine; and a lophophore appears
as an eminence on the floor of the cavity. It may in-
crease by budding, even before it is perfectly deve-
loped. The locomotor embryo is pear-shaped, but
soon losing its cilia, it settles down, differentiates into
endocyst and ectocyst; new buds develop from the
former, which, growing continuously, build up the
colony, each new cell being separated by a partition
from its parent. Sometimes stolons are produced
from the primary polypide.

Gemmation is sometimes discontinuous, the separate
gemma (statoblasts) springing from the funiculus as flat,
ovoid, often spinose, internal buds, consisting of two watch-
glass-like shields, surrounded by a spongy, air-holding
annulus ; they are detached when the parent dies, generally
in autumn, and grow in the ensuing spring; they have no
blastodermic nor ciliated stage, but many have, according to
van Beneden, a structure like a Purkinjean vesicle. In the

Introduction to Antmal Morphology. 229

growth of the embryo in Rhabdopleura there are two fleshy
side lobes attached along the dorsal edge, which do not in-
crease as growth progresses, and are supposed by A//man to
be the homologues of the mantle lobes of lamellibranchiate
Molluscs. Rounded germ capsules are found inside polypide
cells (zooecia), of which the original inhabitant has died.
These are formed from protoplasmic masses below the fundus
of the stomach, and originate new inhabitants for the deserted
house. A second rarer way for new inmates to arise is by
budding from the endocyst.

About 600 species exist, divided into two orders :—

1. Gymnolemata (A//man)—with no epistome, a funnel-
shaped mouth, and the 9-16 tentacles on a circular lopho-
phore ; they never develop statoblasts. This includes six sub-
orders :—

Sub-order 1. Cyclostomata—calcareous, porous, each per-
sona retractile into its cell; mouth terminal, wide; avicularia
and vibracula none; cell-mouth with no crown of bristles ;
they are mostly fossil (Mesozoic); some have a jointed,
colonial axis (Crisiade); others are unjointed, and with
opercula to the cells (Myriozoidz); the cells may have thin
mouths, separate, protruding (Tubulata), or united in project-
ing bundles (Fasciculata).

Sub-order z. Ctenostomata—retractile, with terminal, wide
mouth, and no avicularia nor vibracula ; the oval or cylindrical
cells not pillared, but though separate, arising from a common
stalk ; cell mouth with a setose margin for its closure. The
colony may be horny and crust-like, freshwater, each cell joined
to 4-6 neighbour cells (Hislopiadz, a passage form), or they
may be marine, spongy, massive, or crust-like ; the imbedded
cells with contractile mouths (Alcyonidiadz), or plant-like
branched marine forms, upright or creeping, with projecting
cells. A gizzard is always present in Vesiculariade.

Sub-order 3. Chilotomata—lophophore and sheath pro-
trusible ; cell mouth narrower than the cell, placed at the
front near the terminal pole; mouth often with a horny
operculum, or a sphincter; avicularia and vibracula often
present, rarely very large and ‘numerous, used as creeping
organs (Selenariadz); the colony in the other families is

230 Introduction to Animal Morphology.

firmly rooted, jointed (Catenicellide, Salicornaride, &c.), or
unjointed, flexible, never attached for its whole length
(Scrupariadz, Flustridz, Gemellaride, &c.), orincrusting, ad-
herent directly to foreign bodies (Escharide, Hippothoide,
Porellida, &c.)

Sub-order 4. Paludicellida—freshwater, horny; tentacle
sheath not fully protrusible; cells spindle-like ; mouth tubu-
lar; common stem none, includes one genus, Paludicella.

Sub-order 5. Urnatellida—one freshwater soft form,
whose personz are incompletely retractile into the semicir-
cular cell; stalk jointed, slightly branched.

Sub-order 6. Loxosomida—a marine polypoid passage
form with a pillar and foot; ten tentacles; no anus, and
lateral gemmation.

Order 2. Phylactolemata (A//man)—lophophore horse-
shoe-shaped, with many tentacles, and an epistome; cells
equal, without polymorphism ; never calcareous ; reproducing
often by statoblasts (in the third sub-order only). This in-
cludes three sub-orders :—

Sub-order 1. Rhabdopleurida—marine, abyssal, with
branched, adherent, membranous stock imbedding a chitinous
rod, to which the polypides are attached by processes or
funiculi. The bilateral lophophore has a large shield-like
organ on its hemal side, made of the two coalescent lateral
embryonic lobes.

Sub-order 2. Pedicellinez—one marine genus ; cells soft,
hemispherical, stalked, springing irregularly from a common
stolon ; tentacles solid, partly retractile, united at base into a
calyx.

Sub-order 3. Lophopoda—freshwater, horny ; the arms of
the lophophore free or obsolete; cells cylindrical, dichoto-
mously branched: tentacles fully retractile; colony with no
special stem. These may have an adherent stock and stato-
blasts unarmed with hooks* (Plumatellidz), or a discoidal
colony and two circlets of hooks on the statoblasts (Cristatel-
lidze).

* Except in Pectinatella.

Introduction to Animal Morphology. 231

CHAP Rin Ox OGE iT:
CLASS 13.—TUNICATA.

SINGLE or aggregate, fixed or free, hermaphrodite,*
marine Molluscoids ; rarely symmetrical;t developed
with metamorphosis ; varying from the size of a pin’s
head to that of an apple, or larger in colonial forms ;
and sometimes divisible into three parts (named thorax,
abdomen, and post-abdomen). The epidermis is often
incrusted with sand, &c., or uneven, and sometimes
consists of two layers, a superficial, non-cellular in
Doliolum and Appendicularia, becoming cellular in
others by immigration of cells, and a deeper epithelial
containing larger cells compound to those of the
chorda dorsalis of vertebrates, and crystals of calcium
carbonate, and often stellate (Botryllus, &c.) or glo-
bular (Didemnium) spicules also of lime, rarely sili-
ceous (Salpz). Similar calcareous bodies in the flat
Chelyosoma form two circlets of eight plates of horny
consistence, four around the branchial, three around
the atrial opening, and one intermediate. In Appen-
dicularia the cuticle forms a remarkable case (the
Haus, of A/ertens), said to exist only in males.t

The cutis is never separate from the cuticle, and forms
with it the so-called outer wall of the mantle; it consists of
connective tissue and pigment corpuscles (often stellate), and
crystals, in a copious intercellular matrix, which consists of
Tunicine, C;,HiO,, only differing from Cellulose by being

* Doliolum is dicecious.

t Pelonaia is bilaterally symmetrical.

} If Schizascus be a true tunicate, it is remarkable as having a bivalve
shell (Lacaze Duthiers).

232 Introduction to Animal Morphology.

less easily saccharized. ‘The consistence of the integument
varies from that of soft mucous tissue to a leathery or gristly
hardness; an inner polygonal cell layer lies underneath it.
Fibre-like forms often traverse the cutis, as in Cynthia and
Botryllus, and fat globules are common; rarely the entire
surface layer is homogeneous (Appendicularia), or has a few
scattered nuclei(Doliolum). ‘The cutaneous vessels are often
numerous, and end in dilated ceca. In colonial forms the
integument is common to the stock, and takes its share in
the protrusion of stolons for the growth of the colony, and
by the vessels in it the vascular systems of the persone may
communicate. In Rhodosoma the dermis is in two symme-
trical lateral folds.

The deeper muscular and connective layers are
homologous to the sub-cutaneous laminez of other
vermes, and may be inseparable from the dermis
(Monochitonida), or separate, except at the orifices, or
where special bands unite them (Dichitonida). This
condition has been used as a basis of classification by
Fleming, but it is inconstant in allied species. There
are two or three layers of muscle, an outer longitu-
dinal, an inner circular, and sometimes a second
longitudinal layer internally, usually in separate, not
branched, bands; sometimes each fibre consists of
cortical and medullary layers, and shows widely sepa-
rated transverse stripes. Sometimes the circular are
the stronger (Cynthia microcosmus), and in the swim-
ming forms the sundered muscle bands are strong.
Each orifice is usually guarded by a sphincter, and in
the shielded Chelyosoma this is a six-sided figure with
attachments to the under sides of the superficial plates.
Six fan-like radiating muscles also exist in this form.

The body has two orifices, an anterior, oral or
branchial, more or less wide, sometimes with a crenated
border, or two lips, or four marginal grooves ; some-

Introduction to Animal Morphology. 233

times with short tentacles; it leads into a branchial
chamber often with plaited walls, whose lining mem-
brane is vascular (papillose in Chelyosoma), and shows
a deep, ventral, longitudinal, ciliated groove, bordered
by two mucous folds or lips. At the floor of this
ventral groove is an elongated, rigid, rod-like, whitish
organ, the endostyle, hollow, ciliated at its base, with
an outer sheathing layer of cylinder cells, within
which is a clear membranous layer, and two rigid
yellowish lamine. Between the cutis and the mus-
cular layers are dorsal and ventral longitudinal
sinuses containing the blood, sending branches to the
branchial membrane. This branchial chamber varies
from a very small size to nearly the whole length of
the body (Pelonaia); it is homologous with the
breathing chamber of Balanoglossus ; it often exhibits
two ciliated bands extending from the front end of
the groove for the endostyle to beneath the ganglion.
The wall of the sac appears to consist of longitudinal
and transverse bands, crossing at right angles, leaving
quadrangular meshes ; these bands contain branches
from the dorsal and ventral sinuses.

At the fundus of the branchial sac the cesophagus
opens, usually with radiating plice, and no lip-like
folds ; it passes ab-orally, often backwards, then di-
lates into a stomach, which may be fusiform, cylin-
drical, four-angled (Perophora), or with many inter-
nally projecting laminz (Diazona), or divided longi-
tudinally by seven or eight furrows stretching from
the cardiac to the pyloric end. It may be simply
striated, and the pylorus may be narrowed by a valve
or by fleshy papillae. The outer wall of the stomach
is striated in Dendrodoa, and the cavity has a cellu-

234 Introduction to Animal Morphology.

lose lining in Cynthia. On the wall of the stomach is
often a layer of yellow or green cells, some of which
project inwards (Appendicularia). A somewhat similar
coating of gland cells exists in Sidnyum ; these may
represent a liver. One or two gastric czeca in Salpa
are also supposed to be hepatic. The short cecal
tubes of Chelyosoma, the long follicles of Cynthia, the
separate lobular bodies of Phallusia intestinalis or
Boltenia, are more specialized forms of hepatic organ.
Amauroucium has a streak of glandular ceca on the
stomach wall. The stomach is usually directed to-
wards the hemal surface, and ends in the intestine,
which passes neurad; thus the digestive canal has
first a heemal and secondly a neural flexure, the latter
being the most conspicuous and constant, while the
former is due to a secondary spiral folding. No part
of the intestine is protrusible. The tube has usually
a thin muscular wall (absent in Salpze), and-is often
suspended by thread-like mesenteries. It may be
spirally folded throughout (Sidnyum), or only at its
terminal part (Aplidium, Polyclinium). In Clavellina
it is divisible into three regions, a clear, thin-walled
part, a thicker glandular tract, and a thin rectal
portion. Glandular ceca may open into the intestine,
or it may have a coating of hepaticcells. In Boltenia
reniformis, small sub-conical masses of nucleated
connective tissue and protoplasm are attached to the
upper surface of the rectum. The intestine contains
usually diatom frustules, often Radiolarians,&c The
hinder part of the canal may be surrounded by a
narrow meshed plexus of vessels with whitish con-
tents, forming a peculiar vascular appendage. The
anus is on the surface beneath the tail in Appendicu-

Introduction to Animal Morphology. 235

Jaria, but in others it is at the bottom of an atrial or
cloacal chamber beside the branchial cavity, whose
opening may be simple or surrounded by a 10-11-
cleft rosette. In the simple forms the cloaca is an ir-
regular sac lined by a thin membrane. The neural
side of the branchial sac projects into this chamber,
and the partition is pierced by many openings with
ciliated borders, whereby the water from the branchial
enters the atrial chamber. The atrial opening in
fixed forms is usually anterior and dorsal, close to the
mouth. In free swimming forms it is usually directed
backwards. In Polyclinide a tongue-like process
can close this opening, and in others its lips may be
crenated. In colonial forms each cluster of persone
may be grouped radially around a common cloaca,
into which their intestines open.

The nervous system consists of a supra-pharyngeal
ganglion placed usually between the oral and cloacal
openings. A pair of nerves loop around the mouth,
and may form a circumpharyngeal ring, but without
an inferior ganglion. Thenerve threads are primitive
nerve fibrils, and those distributed to the muscles
appear continuous with the fibres thereof; branches
pass to the sphincters, to the muscular lamina, and to
the viscera. In Appendicularia a nerve extends
into the tail, in which it shows several successive
enlargements.

(This tail in Appendicularia acts as a swimming
organ, is longer than the body, and consists of a layer
of dermis with or without epithelium, a layer of cir-
cular, and one of longitudinal fibres with the nerve
cord, and a series of large nucleated cells in a homo-
geneous sheath, forming the tail axis.)

236 Introduction to Animal Morphology.

As sense organs may be reckoned the 6-30 oral,
simple, rarely pinnate (Cynthia ampulla) tentacles
when they exist, a ciliated, flask-like fossa in the
middle-line of the back of Salpe, in front of the dorsal
end of the gill framework, may be a sensory organ
like the groove in Nemerteans.

Red or yellow ocelli may exist around the mouth, or
around both mouth and atrial opening (eight round the former
and six round the latter in Phallusia). Pyrosoma has one red
ocellus behind the ganglion. In Salpz the horseshoe-shaped
pigment speck may have many crystal cones and a nerve
filament. A small auditory (?) vesicle lies on the ganglion in
Chondrostachys. A similar clear round sac with a single
otolith lies directly on the ganglion in Appendicularia.
Another exists between the third and fourth muscular girdles,
but not in the ganglion, in Doliolum. A sac is placed on
the nerve centre in Salpa, with black pigment spots and
four semicircular otoliths. In Chelyosoma an otocyst, with
striated walls full of whitish material, lies close to the gan-
glion, and a second, pear-shaped, with a blackish body within,
is in front of the ganglion. A sac, communicating with the
respiratory canal by a duct, and lying on the ganglion, but
without an otolith, has been also supposed to be sensory.

The heart is a simple fusiform or cylindrical tube,
rarely ovoid or lobular (Cystingia), contained usually
within a fine walled space (pericardium), and lying,
posteriorly and ventrally. It sends the dorsal and
hzmal vessels into the branchial wall, except in
Doliolum and Appendicularia ; but there are no capil-
laries elsewhere, the blood circulating in lacune. In
action the heart exhibits a curious unique alternation,
discovered by Vaz Hasselé, first contracting in one di-
rection, then stopping for a short time, then contracts
in the opposite direction; it acts from 48-75 times a

Introduction to Animal Morphology. 237

minute, and has been noticed making 45-180 con-
tractions in one way, then pausing for a time equal-
ling the duration of two beats, and then making 170
contractions the other way. The blood is colourless,
with ovoid or irregular corpuscles, rarely red. The
heart isabsentin Pelonaia. In Salpait sends a branch
to the closely united mass of viscera (“nucleus’’), and
a hemal canal to the branchial chamber.

There are no external generative organs. Self-
impregnation occurs, except in those cases of pro-
tandry where the spermatozoa are earlier developed
than the ova, or in the dicecious forms. The testes
are three or four milk-white pouches, usually around
the ovary, and opening onamammillary eminence into
the cloaca. They are rarely symmetrical (Pelonaia).
The spermatozoa have discoidal bodies and flagella.
The ovary is usually a sac, opening into the cloaca;
single (Phallusia), double (Boltenia, Pelonaia), race-
mose‘(Cystingia) opposite to it. Carus describes a
second gland secreting the gelatinous covering of the
ova.

The eggs are rarely developed directly, usually
with the intervention of a larval stage, and sometimes
one or two metagenetic forms intervene between each
act of sexual reproduction (Doliolum).

In Ascidia and Phallusia the segmented yelk as-
sumes its mulberry form, hollows within, and appears
as a spherical, cellular body (blastula); a groove in-
dents one side of this; the lips of the groove rise and
close it in, except at one spot, and thus the body be-
comes bicavitary, the dorsal groove contracts, and the
nerve ganglion develops either within it, or in its close
vicinity. On a plane between the dorsal neural cavity

238 Introduction to Animal Morphology.

thus formed, andtheventral space, a double row oflarge
cells appears, which extends into the tail, and forms
an axis for that organ. These cells resemble those of
the chorda dorsalis of Vertebrates, and have a similar
relation to the neural and visceral cavities of the pri-
marily bicavitary body to that possessed by the
dorsal chord. Upon these phenomena, observed by
Kowalewsky, Kupffer, and others, is rested the theory
of relationship of Tunicates and Vertebrates, which is
strengthened by the setting apart here of a portion of
the digestive canal for respiratory purposes. <A dif-
ferent, but much less satisfactory, interpretation of
these appearances is given by Donz¢z and ALeczntkow.
The embryo is usually tadpole-like, rarely without a
tail (Molgula tubulosa).

In Appendicularia the branchial openings are
formed by a double invagination, one outside of the
skin and one inside of the pharynx. In all the en-
dostyle is developed from the original epithelium of the
branchial openings.

In Salpz a curious life cycle exists. An egg de-
velops within a brood-sac of a parent Salpa, and dif-
ferentiates into two parts : one, the placenta, which is
always on the hemal side; and the other, the embryo
itself. In this foetal stage, digestive, nervous, and
circulatory organs are developed, and at the hinder
end of the foetus a curious cluster of fat-holding cells,
the elceoblast, forms, which soon afterwards disap-
pears. This solitary form soon becomes free-swim-
ming, and from the ab-oral side of the heart it develops
a thread-like organ, which elongates, thickens, and
segments into a chain of variously aggregated Salpe,
which have communicating circulatory organs. Each

Introduction to Animal Morphology. 239

of these aggregated Salpze again develops sexual
organs, and from their eggs a second brood of solitary
Salpe spring.

In the compound forms, like Botryllus, a simple
egg develops an embryo with one tail and a many-
lobed body with a central opening, the cloaca, around
which each lobe becomes a persona.

The egg in Pyrosoma develops an incompletely
organised embryo or cyathozooid, which by budding
gives rise to four zooids united together by a vascular
cord. The tubular heart of the cyathozooid has a
peripheral sinus between its two tunics, and is the
centre of a social vascular apparatus, whereby the
embryo is nourished.

Three types of aggregation are met with among
the Tunicates—rst, solitary forms; 2nd, social zooids
connected by a common vascular system; and 3rdly,
compound, united by a fusion of the dermis, but with
no internal union. These forms have a single, some-
times branched, cloaca for each colony.

About 300 species are known, some of which (Pyrosome
and Salpz) are brilliantly phosphorescent. The light in
Pyrosoma emanate from two lateral cell masses, formerly
considered to be ovaries (Pancer?).

They are divided into two orders :-—

1. Thaliacez ( Z7oschel)—free swimming, simple, or united,
prismatic or cylindrical, with a clear cutis; the openings at
either end; gills as a band in the branchial chamber; deve-
lopmentmetagenetic. Family 1. Appendicularide—tailed, like
the larve of other forms; cloacal; respiratory organs with
one opening and two tubular spaces ; ovaries and testes post-
intestinal ; thc cutis forms a house or theca; heart does not
reverse its actions. 2. Salpide—mouth and cloaca opening
at opposite poles; heart reversing its actions alternately;
circular muscular bands usually well marked; viscera in a

240 Introduction to Animal Morphology.

round opaque mass at one end of the body (nucleus) in
Salpa, but not in Salpella. Anchinia has no muscular bands
for locomotion. 3. Doliolidz—barrel-shaped, with equal,
regular, hoop-like, circular muscle-bands ; gill cavity flat.
4. Pyrosomatidz—stock a cylindrical tube open at one end,
made up of many individuals united; each persona opens
outwards and inwards by its polar mouth and cloacal openings
respectively. The gill sac is like that of an Ascidian proper.
Each egg develops four individuals, which rapidly multiply
by buds from the endostyle. 5. Kowalewskiide—heart, en-
dostyle, and intestine absent ; pharynx ciliated with four rows
of teeth, otherwise as in Appendicularia.

Order z. Chthonascidie (#rown)—fixed, rarely imbedded
in sand or mud ; mouth and cloacal opening at one end more
or less tubular, with the ganglion between them ; branchial
sac regular, with many rows of gill slits.

1. Pelonaiade—imbedded in mud; individuals united,
with no heart and symmetrical sex organs. 2. Ascidiade—
fixed to stones, having a heart, undergoing metamorphosis in
development; sex organs unsymmetrical. Chelyosoma is
flat, and has the peculiar many-angled plates above described.
Rhodosoma has a two-winged cutis. Boltenia is long stalked, -
with four rayed openings and compound tentacles. Cystingia
is similar, with an irregular anus. Dendrodoa has a longitu-
dinally folded gill sac and a tentacle crown, and one (left)
ovary, while Cynthia has two and Pandocia has one ovary
(the right). Molgula has no longitudinal folds in the branchial
membrane, an eight-lobed mouth and a six-lobed cloacal
opening. Phallusia has a six-lobed mouth and a four-lobed
atrial outlet. 3. Clavellinidza—family stock branched, with
stalked person, and often with common circulation. There
may be creeping stolons (Clavellina), or a single stolon with
a few individuals (Perophora), or in compound, greenish,
large masses (Syntethys). In Chondrostachys the individuals
are grape-like on an upright stem. 4. Botryllinide—com-
pound, usually forming an expanded, mucous, or spongy,
often lobed mass, united by their common cutis, but without
common circulation. They are divided into three sub-fami-
lies :—(a). Botrylline—having the persone united around

Introduction to Animal Morphology. 241

the common cloaca, the abdomen not sharply marked off;
they may be regularly arranged (Botryllus) in stars or discs,
or irregularly (Botrylloides). (B.) Didemninz—having the
body divided into thorax and abdomen, and each embryo
producing two individuals. In Leptoclinum there are few
systems andasix-lobed mouth. Enccelium has many systems
and an obsoletely rayed mouth. Didemnium has many
systems and a pedunculate abdomen. Distomus has one or
more circles of personz, and each has a six-rayed mouth and
anus. Diazona has regular concentric circles of personz
forming a rosette-like disc. (C.) Polyclininzee—body with
not only a thorax and abdomen, but a post-abdomen, con-
taining the heart. Polyclinum has a pedunculated post-abdo-
men; the mouth is six-rayed; the anal opening prolonged
horizontally and irregularly cut. Aplidium has the anal
opening indistinct, and no central cavity. Sidnyum has an
eight-toothed branchial opening, and a simple, tubular, folded,
anal opening. Synoicum has a six-rayed mouth, an irregu-
larly six-rayed anus, and a sessile post-abdomen. Amouro-
cium has indistinct abdominal divisions; mouth six-rayed.
In Parascidium the mouth is eight-rayed, with two eye-specks.
Sigillina is seal-like, the narrowing circlets rising one over
another.

CHAPTER XXXIV.
SUB-KINGDOM 6.—MOLLUSCA (Cuvzer).

MOSTLY aquatic, soft-bodied persone, composed of
one, two, or three obscurely marked metameres, with
a concealed bilateral symmetry. Their structure can
be easily understood by regarding them as Vermes*

* We know as yet of no absolute passage forms or direct synthetic
types.

R

242 Introduction to Animal Morphology.

with no articulated appendages, modified by unequal
lateral development, and by a fusion of metameres.
The integument and muscular layers unite to form
a contractile envelope,* consisting of—ist, an epi-
dermis, ciliated in the embryo,t becoming superficially
tesselated in the adult, or forming a laminated cuticle,
pierced by non-glandular pore canals, as in some
Cephalopods; 2nd, a dermis of connective tissue,
sometimes cartilaginous in parts (Carinaria, Loli-
gopsis), containing glands,} pigment cells,§ often
granules, spicules, or networks of carbonate of lime}||
sometimes with follicles giving origin to bristles like
those of Chetopods,§] or rarely with clusters of cnidz
like those of Turbellaria ;** 3rd, a muscular layer,
never separable from the last, usually consisting ofin-
terrupted bundles oftransverse fibre cells externally, and
of a more continuous inner layer of longitudinal fibres.
The head of the larva is furnished with an expan-
sion of the integument for locomotion, the Velum,

* When there is much connective tissue, as in the clear dermis of
Heteropods, the capacity of form-change is small. The development of a
shell also limits its contractility.

t In the adult, ciliation is confined to the gills, except in a few forms,
as Phyllirhoé.

+ These are—ist, unicellular glands like those in worms; to these the
goblet cells, scattered on the surface of some molluscs, seem to be related ;
2nd, mucous glands, with ducts scattered over the surface as czecal follicles ;
3rd, colour glands secreting a deep purple fluid, as in Murex, Aplysia, and
Purpura. These are usually limited to areas on the surface.

§ Chromatophores, or connective corpuscles filled with pigment, having
radiating, muscular fibre cells (?) attached to their periphery, whose contraction
causes the cells to assume a stellate appearance, found in Cephalopoda and
Pteropoda.

|| As in Doris, &c.

As on the mantle edge of Brachiopods and Chitons.

** As in the dorsal papille of Golide.

Introduction to Animal Morphology. 243

margined by a crown of large, simple, or clustered
cilia, sometimes bilobed, with an anterior and posterior
median notch, or divided into four or more tentacle-
like lobes, which may have ciliary girdles. This is a
form of the primary ciliary crown of the larve of
Vermes, like the lophophore of Polyzoa. A fold of
integument at each side of the body is called the
mantle, and may be single and continuous, or of two
lateral, united, or separate lobes; it may be present
in the embryo, and lost as age advances, or may be
absent. The mantle lobes are probably homologous
with the basal papille of the notopodia, and between
them on the ventral surface the dermal and muscular
wall is developed into a thick process or /oo/, the chief
organ of progression, which may have a flat sole or a
sharp edge, and may be rudimental in sessile forms
(oysters, &c.) As this is the ventral surface of two or
three united metameres, it may be divided into two or
three parts, named, respectively, pro-, meso-, and
meta-podium ; sometimes it is longitudinally divided
into a middle and two lateral parts. The relation
between the foot and the under surface of the ordinary
body wall of a worm is shown by the fact that the
viscera are often prolonged into, and lie above it; its
upper surface may develop an appendix or epipodium.

When the mantle is present it usually secretes a
shell,* more or less completely enclosing the body ;
in its simplest form this is a single lamina on the
mantle surface (wszvalve), or when the mantle is bi-
lobed it consists of two plates united dorsally by a
hinge, and is called a bzvalve. The first form may be

* Composed of Conchiolin 0.04, Calcium Carbonate 0.94, Calcium
Phosphate, Alumina, Iron, and Silica, 0.02 =1.00.

RSE 2

244 Introduction to Animal Morphology.

laterally symmetrical, but from unilateral growth
often assumes a spiral form. Shells increase in ex-
tent by additions secreted by the thick and glan-
dular margin of the mantle, in the form of long
prismatic cells, or minute, conical shell-columns.
The surface of the mantle secretes the nacreous or
mother of pearl layer,
which increases’ the
thickness of the shell,
and consists of thin
overlying plates, whose
Wavy, out - cropping
edges, viewed by re-

flected light, appear iri- yuinees'E foots B double gill lamella’
descent. The outside.of . reece ee chomantle WE
the shell is coated with % Gasteropeds B sillss B, foot.

a fine ferzostracum, a horny cuticle often covered with
hair-like or laminated processes. The shell may de-
velop internal processes, as in Brachiopoda, but it is
always an epidermal structure. An internal skeleton
sometimes exists as a series of symmetrical, simple,
cellular cartilages around the pharynx or cesophagus,
but not homologous with any specific part of the ver-
tebrate endo-skeleton. The muscular system is, as a
rule, feebly developed, though special parts of it,
modified by the forms of the shell and foot, may be
very strongly marked. The nervous system consists
of a pharyngeal ring, having a pair of epi- and a pair
of hypo-pharyngeal ganglia united by commissures ;
of these, one or other may preponderate, or they may
become fused or sub-divided, or their commissures
may be short or long. The hypo-pharyngeals are
often displaced downwards into the foot, and hence

Fig. 30.

Introduction to Animal Morphology. 245

are called pedal ganglia. Two long (sympathetic *)
nerves, arising from the cesophageal ganglion, may
unite posteriorly to form a parieto-splanchic or anal
ganglion. Sense-organs may exist as_ tentacles,
ciliated smell organs, eyes, otocyst, &c.

The digestive canal never communicates with the
body cavity, and is more or less looped, so that the
anus is often near the mouth, and always near the
breathing cavity. Theintestine issometimes attached
to one or more rudimental transverse partitions,
traces of the metameric septa. There are often dental
organs, sometimes a crop, always a liver. The circu-
lation is lacunary ; the blood clear (rarely coloured),

Fig. 31.
eat “ho ¢ y x
cation) Nee) kh i 2" : a:
meee ae sn/, ae
aae Vee &

A, segment of the dorsal vessel ofa Worm; 1, 1, 1, inferent vessels; 2, cephalic end ;
2’, abdominal end. B, heart of Nautilus; 1, 1’, auricles; 2, cephalic aorta; 2’, abdo-
minal aorta. C, heart of Lamellaibranch or Loligo. D, heart of Octopus. E, heart
of Gasteropod.

corpusculated, and propelled by a heart, which re-
sembles a segment of the circulatory system of worms
(Fig. 31), receiving blood from one or two pairs of
dilated, transverse vessels distended into auricles, or
rather into dilated, branchial sinuses (Fig. 31, 1, 1’),
which receive blood from the gills, and empty it into
a longitudinal dorsal vessel, modified into a ventricle,
usually straight, rarely flexed on itself, and sending
forward a cephalic (Fig. 31, 2), and backwards an

246 Introduction to Animal Morphology.

abdominal aorta (Fig. 31, 2’). A part of the body
cavity surrounding the heart is called the pericardium.
Some regions of the integument, either the mantle
itself, or a single or double pair of folds within the
mantle lobes, or an area of the skin of the back, be-
come spongy and dilated as breathing organs, or gills.
In land molluscs the cavity within the mantle lobes,
or part of it, is set apart as an air-breathing space or
pulmonary cavity ; but the breathing organs are never
combined with the pharynx, and are always ciliated.
One or two pair of excretory organs (modified seg-
mental organs) commonly exist, opening both on the
surface and into the body cavity ; these maybe simple
tubes, or may have glandular walls. When largely
developed, they receive blood from the viscera, and
transmit it directly to the gills, forming a rudimental
portal system. The outer openings of these organs
may receive the ducts of the sexual organs, or may
open in common with them, or may be separate. Other
renal organs, special developments of the vascular
system, exist in Cephalopoda and Brachiopoda.
Molluscs are usually hermaphrodite, with a single
sex gland (often placed close to the liver), some of
whose acini produce ova, others spermatozoa. The
male and female products may be emptied by a com-
mon duct, or the oviduct and vas deferens may arise
in common, and then separate, and finally reunite, or
the primary common part may be short or absent.
Various accessory organs are appended in some
classes. Development is attended with some form of
metamorphosis. The ova are holoblastic, except in

Cephalopoda.
Mollusca are mostly marine; a few are pseudo-

Introduction to Animal Morphology. 247

parasites.*¥ They can be arranged in two divi-
sions :—

Division 1. Brachiopoda (Dumerzl)t — marine
molluscs, usually small,t included in a bivalve shell
whose line of articulation is haemal, transverse, and
whose valves are ventral and dorsal, equilateral, but
dissimilar,§ the ventral being usually the more convex,
overhanging the dorsal at the hinge, and often having
a longitudinal median furrow, while the dorsal has a
median ridge. The valves are opened|| and closed
by muscles, and have no elastic ligament, and the
beak of the ventral valve is often pierced by a hole]
for the passage of a pedicle by which the shell is
attached to foreign bodies, or the surface of the ventral
valve may be itself adherent (Crania, Thecidium).
All the adult forms of living species are fixed.**

The shell is generally dull-coloured,{{ slow-growing,
laminated, and marked on the surface with concentric lines
of growth,{t often with radial ridges, alternate on the opposite
valves, sometimes (in fossil forms) with hollow spines. The
shell has no nacreous layer, but consists of elongated, parallel,

* Vulsella, Coralliophila, Magilus, Gastrochaena, are found in corals,
Stylifer in Starfishes, Eulima in Holothurians, Entoconcha mirabilis in
Synapta, &c.

¢ Palliobranchiata (Blainville), Brachionopoda (Lrewz), Spiro-
branchiata (Schmarda).

£ From 0.01" to 3" in length; often as broad as long.

§ The valves are scarcely distinguishable in Lingula.

|| But in the hinged forms can only open for a very small distance, in
Waldheimia from }” to +4;’, unless violence be used.

‘I The opening may be in the back, between it and the hinge, or be-
tween the two valves (Lingula).

** When set free the dorsal valve, being heavier, is downward.

+t Usually grey or brown. Waldheimia picta is spotted; Rhynchc-
nella is very dark; Lingula green and brown; Crania white.

tt Sometimes lamellose, as Orbicula, Crania.

248 Introduction to Animal Morphology.

conical prisms placed at angles of 10° or 12°, with the surface
of the shell. Through the shell are vertical perforations,
finer internally than externally, only absent in Spiriferide
and Rhynchonellidz, occupied by processes of the outer layer
of the mouth, compared by Huxley to those whereby the
tunic adheres to the test in Tunicates. Sometimes the shell
is horny and chitinoid (Discina); in Lingula it consists
chiefly of calcium phosphate (85. per cent.), with carbonate
(12.) and magnesium carbonate (2.). Waldheimia has more
calcium carbonate. The perforations may be branched to-
wards the surface (Crania), or fine and parallel, like dentine
tubes (Lingula, Discina). The shell prisms are usually equal
and with rounded bases, but may be unequal and irregular
(Crania). The ventral valve presents, near its articulation,
and beneath its beak, a convex or flat surface (Azmge area), in
the centre of which is a triangular depression (del/zdium),
which may be single (d. discrefum), or with a median division
(d. sectans), or partly surrounding the perforation (d. amplectens).
The opening at the summit of the deltidium is the deltidial
opening. The shell is often auricled, beside the hinge area.
The two valves may be united only by soft parts (neither by
a hinge nor an elastic ligament), or by a long straight line of
contact, without teeth (Productide, Chonetidz), or by a
perfect hinge, consisting of two teeth on the ventral valve
fitting into two sockets on the dorsal. The outside of the
shell is covered by a fine periostracum. The peduncle of
attachment varies in length from a few lines to several inches
(Lingula) ; it is thick, brownish, semi-cartilaginous, flexible,
scarcely elastic, with a single or double (Lingula) horny
sheath, with sometimes an inner cylinder of longitudinal
muscles within it (inner pillar muscle, as in Lingula). A
musculus peduncularis extends from the ventral valve to the
base of the pedicle in Waldheimia. A pair of these exist in
Rhynchonella.

Within the shell in Terebratulide, Spiriferide, and
Rhynchonellide are internal processes of calcareous matter,
forming a loop for the support of the arms characteristic of
the group. These consist of the same material as the shell,
but are imperforate in Terebratulide. They are attached to

Introduction to Animal Morphology. 249

the dorsal valve, and may arise from each side of a flat inner
hinge plate (Waldheimia), or from an internal longitudinal
median ridge running along the dorsal valve of the shell
(septum dorsale*), as in Bouchardia and Kraussia, or from
both (Terebratella, Morrisia), or from the inside of the valve
itself. The base of the loop on each side is called the crus,
and often has a crural process or spur passing inwards, which
may join its fellow of the opposite side, forming a crural
bridge. The loop itself may be short, down-directed, or may
bend again upwards and backwards, and its two limbs may
remain separate (and become spirally coiled as in the extinct
Spirifers), or may unite, forming a terminal bridge.

The mantle is bilobed, full of lacunary blood spaces,
the chief agent in respiration, as no separate gills
exist. The mantle surface often contains calcareous
spicules, sometimes branched, or united into a crust.
Its free border is beset with separate or clustered,
long, transparent, ringed bristlest arising in special
glandular follicles, movable by muscular fibres at-
tached to them at their bases. The mantle consists
of an outer, netted, connective layer, an inner, homo-
geneous layer, and a central lacunary area, bounded
by areduplication ofthe two laminz. Muscular fibres,
anterior and posterior parietal muscles, exist in it,
especially in Lingula, passing from one mantle-lobe
to the other.

The arms are two, long, hollow, symmetrical pro-
cesses, when at rest folded with 1-20 spiral windings,
or S-formed (Morrisia), and placed one at each side
of the mouth, attached to the loop of shell when it
exists. They consist of semi-cartilaginous connective

* Double in Pentamerus.
+ Branching in Discina.

250 Introduction to Animal Morphology.

tissue, and are united at their base by a band of the
same material. A groove runs along the upper
surface of each, bordered by a double row of many
parallel sub-rigid bristles or filaments, each of which
is clothed with cilia; three muscular bands lie under
the groove and attached to these bristles, which can
move them (a) outwards, widening the groove (6), in-
wards, narrowing it, or (c)downwards. These bristles
are contractile* and hollow, with calcareous supports
in Spirifer rostrata and Terebratula pectunculoides.
The arms themselves are traversed by large canals,
and are chiefly moved by the distension of these with
fluid, which enters from the body cavity, and is re-
tained by the action of circular basal fibres. Each
arm contains—rst, a chief canal beginning cecally at
its base; 2nd, a small afferent canal whereby the
bristles may be distended; 3rd, an efferent canal ;
4th, a prolongation of the body cavity forming an arm
pouch ; and 5th, a canal at the base for the reception
of the calcareous loop support. Besides these are
numerous lacune for blood.

The muscles which move the valves of
the shell are :—1st. Two pair of occlusores,
anterior and posterior, passing from valve to
valve, tendinous medially in Rhynchonella
and Terebratula. znd. Two pair of dzva-
ricatores from the ventral valve to the hinge
process of the dorsal, one chief and one
accessory pair; these are the cardinal 4,46 of shell o
muscles of some authors. 3rd. Adjustor Walthennis fee ieee
ventralis, from the ventral valve to the ;
peduncle. In Lingula there are three adjustors (a. ex-
ternus, centralis, and posticus); of these two (external and

* A respiratory function is assigned to these.

Introduction to Animal Morphology. 251

central) arethe homologues of the ventral adjustor of Wald-
heimia.

The mouth is a transverse slit between the arms;
beneath it is a prominence or lower lip, the homologue
of the foot of Otocardians. The short, undifferentiated
pharynx and cesophagus pass in front of the crural
processes of the shell between the occlusores, and end
in a stomach, which may be oval, tubular, fusiform
(Crania), or lenticular (Lingula); from it, towards the
ventral valve, passes the intestine, which is either
short, with one neural flexure and with a cecal end
(Terebratulide, Rhynchonellide), or long, coiled, tra-
versing the liver, and ending in a papillary anus
(Lingula, Discina, Crania). Thefirst form is a second-
ary degradation, since in Thecidium, an impervious
cord from the cecal intestine passes to where the anus
would be. The intestine is fixed by a longitudinal
mesentery of two parts, dorsal and ventral, extending
from behind the cesophagus to the end of the attach-
ment of the occlusor muscle. Two transverse parti-
tions, the remains of the inter-metameric septa, also
suspend the intestine. The first, gastro-parietal, con-
sists of a middle (absent in Lingula) and two lateral
portions ; the second, or ilio-parietal, is farther back.
The liver is a multilobar mass made of many cecal
pouches, with many ducts in Crania, four in Lingula,
two on each side opening into the stomach; in Lingula
two lobes are in front, and two behind the gastro-
parietal band.

The circulation is lacunary, the vessels (excepting
a few primary ones) having no proper walls. The
heart is a saccular organ, lying on the stomach be-
hind the middle gastro-parietal bands; it has two

252 Introduction to Animal Morphology.

walls, an outer homogeneous, an inner muscular.* It
receives an anterior stem from over the cesophagus,
and sends off lateral branches; the vein collects the
blood of the lacune and of the mesenteric spaces.
The two lateral vessels are united for a short distance;
each divides into two branches, anterior and posterior ;
the former going to the dorsal lobe of the mantle, and
giving offmedial and lateral branches; the dorsal branch
supplies the reproductive glands, the other traverses
the ilioparietal septum, over the excretory organ, and
supplies the ventral lobe of the mantle. In the wall
of the mantle are two accessory hearts or pyriform
sacs receiving and transmitting blood; these are pro-
bably homologous to the venous accessory organs in
Cuttlefishes. There is no pericardial segment of the
body cavity, unless the space included in the ilio-
parietal septum be considered as such.

One or two pair of excretory organs exist, which
are modified segmental organs. In Rhynchonella
one pair is dorsal and one ventral. The dorsals are
absent in Lingula and Terebratula; in the former the
ventral organs lie between the two layers of the ilio-
parietal septum. They open by a tubular part ex-
ternally near the bases of the arms, and by a radially
folded funnel, which has been mistaken for a heart,
into the bodycavity. In Terebratula the tubular part
is short, and the mouth separated by the occlusores ;
the tubular part is lined by glandular epithelium.
This tube is the usual channel for the extrusion of the
sexual products.

The nervous system consists of a large hypo-

* Lingula has no heart (Semper), and the circulation is carried on by
cilia in the large vessels.

Introduction to Animal Morphology. 253

pharyngeal ganglion, sending two lateral, visceral
branches, which form two small, lateral cesophageal
ganglia, and end in two labial ganglia. From the
large ganglia come off laterally nerves to the upper
mantle lobe and to the arms. Two cords pass beside
the cesophagus, forming a pillar-like pair of gangli-
form swellings, sending branches to the ventral mantle
lobes. There is no esophageal ganglion in Lingula,
but two lateral ganglia, sending many radial nerves
in the mantle. Two similar ganglia exist in Discina.

Most Brachiopods are hermaphrodite ; a few (The-
cidium, &c.) are dicecious. The sexual gland is a four-
(rarely two-) lobed yellow mass, either in the body
cavity, and partly round the intestine and muscles
(Ecardines), or in the space between the mantle lobes.
(Testicardines). How impregnation occurs is un-
known; but as they are always in clusters, there
would not be much difficulty. The sexesin Thecidium
differ in the shape of their shell, and this genus has
also a brood-pouch wherein the eggs are retained by
fine filaments. The embryology of Brachiopods con-
firms strongly their relationship to Vermes. The ova
appear first as caudate ciliated bodies, early develop-
ing a bilobed mantle, and a velum or ciliated head-
lobe, on each side of which are four, hollow, ciliated
processes. The free larva has two ear-vesicles on the
nerve centres, disappearing in the adult. Eyes also
exist as pigment spots, which also disappear. The
intestine early develops, and the velum is modified
into the arm basis. The fry of Discine have been
found attached to the valves of their parents, and the
fossil Stringocephalus has been found with many
embryo shells within it. Some larve creep by means

254 Introduction to Animal Morphology.

of a pair of spines, one on each side of the ventral
mantle lobe.

Of the 2000 species known, only 80 are living ; the others
are mostly palzozoic. ‘They are more abundant in the
Southern than in the Northern Hemisphere, and live at
depths of 10-200 fathoms. The horny shelled forms are
littoral and sub-littoral. They are most abundantly found
on a stony bottom, and feed on Diatoms, Sponges, &c.) This
division includes two orders :—

1. Ecardines (van der Hoeven)—intestine long, with a lateral
anus; shell hingeless; no arm supports; a vasiform heart ;
mantle margin ununited ; generative glands in the perivisceral
cavity. Herein are the families:—1. Lingulide—horny,
tubular shells, witha muscular peduncle, springing between the
beaks of the two nearly equal shell valves, ex. Lingula, from
the Pacific. 2. Discinida—chitinous shell, with an opening
in the under valve (Discina, Pacific). 3. Craniidae—calca-
reous shell adherent by the under valve (Crania, Atlantic).

Order 2. Testicardines (Gegenbaur)—digestive canal short,
aproctous; mantle lobes united behind; shell calcareous,
with a hinge line and prismatic structure. ‘This includes the
following families :—Rhynchonellide—arm loop calcareous,
of two parallel crura; shell with no area; hinge line curved
or straight ; both valves convex and radially ribbed; rarely
punctated ; the beak in Rhynchonella is imperforate (Medi-
terranean and Pacific). 2. Terebratulidee—arm support strong,
looped, never spirally developed ; shell biconvex, perforate
at the beak, and punctated ; of the included genera the shell
is directly adherent to stones in Thecidium, attached bya
peduncle in others; the loop is very short in Terebratula,
longer and reflected in Waldheimia, attached to the septum
dorsale in the long, narrow Bouchardia; the loop for the
sigmoid arms in the minute Morrisia is not reflected. Kraussia
has small°oral arms and a transversely ovate shell, and some-
times a branched apophysis. Megerlia has the loop trebly
attached to the hinge plate, and by two slips to the septum.

Of extinct families Spiriferidze (Paleozoic) has spirally
coiled diverging arm supports and an impunctate shell.

Introduction to Animal Morphology. 255

Chonetide (Paleozoic) has a tooth-bearing hinge and tubular
spines. Strophomenidz (Paleozoic, Leptaena, also Liassic)
is similar, but with no spines. Productidze has no teeth in
the hinge, only a straight line, and the dorsal valve often
concave.

CHAPTER X:XXV.

DIVISION 2.—OTOCARDIA (//aecke/).

MOLLUSCS having hearts consisting of one or two
auricles and one ventricle. The integument is dif-
ferentiated dorsally into a mantle, ventrally into a
foot. The nervous system consists of a pharyngeal
ring with, usually, epi- and hypo-pharyngeal ganglia,
and one or more visceral ganglia united to the epi-
pharyngeal by commissures. Three classes are in-
cluded herein :—

1. Lamellibranchiata (Blaznvzlle)*—aquatic, mostly
marine, fixed or free; with a large mantle usually
covering the whole body, and consisting of two, more
or less, symmetrical lateral lobes, continuous from
before backwards, and overhanging the mouth, at-
tached together medio-dorsally, and secreting on its
outer surface a shell of two lateral valves. There is
no specialized head-segment with centralized sense-
organs. The shell is often equivalve (except at the
hinge). The valves are rarely equilateral,t and are
united medio-dorsally by a longitudinal, movable

* Acephala, Cuvier ; Bivalvia, Linnaeus.
t As in Pectunculus.

256 Introduction to Animal Morphology.

hinge, outside which is an elastic ligament, which
during life keeps the valves open.

This consists of an outer thickening of the periostracum,
over a layer of “‘ cartilage” consisting of an iridescent material
soluble in caustic potass, which exhibits two sets of strie,
vertical and horizontal; this lies in a pit or chondrophore,
often elongated and spoon-like (Mya, Mactra), sometimes
multiple.* Each shell valve has on its upper edge, over-
hanging the hinge, a beak or umbo, which may be central
(Pectunculus), but is usually nearer the anterior (mouth) side,
which is thus shorter than the posterior, which bears the
ligament.| The umbo may be straight (Mytilus), or bent
forwards (Venus, &c.), rarely backwards (Lyriodon), or spirally
coiled (Isocardia, Diceras, Chama). The right valve may be
smaller than the left (Ostrea, Pandora, Lyonsia), or vice versa
(Chamostrea and Corbula). The periostracum may be
evanescent or permanent, often bristled or tufted, sometimes
prolonged beyond the edge of the valves (Solemya, Cyrto-
daria}, or extending over the siphon (Mya, Glycimeris, &c.)
The shell surface is marked with concentric lines of growth,
beginning around the umbo, also with radial lines, ridges,
scales, or spines, corresponding to irregularities in the mantle
border. The valves may be capable of perfect closure, or
may gape posteriorly for the emission of the siphons, rarely
in front (Rocellaria, Gastrochaena) for the protrusion of the
foot, or ventrally (Galeomma). At the hinge there are teeth
in each valve fitting into corresponding hollows in the neigh-
bouring valve. Those directly under the beak are cardinal ;
those in front or behind it are /a/eral.{ The cardinals may

* Tridina, Crenatula.
+ In Donax, Glycimeris, Solemya, &c., the umbo is nearer the hinder
than the front edge of the shell.
ae ral ape
t Sometimes the teeth are formulated e.g. C fe) ir fies
£. 3 la.2 Up.2
right valve 2 anterior on the right valve I
laterals

meaning Cardinals, ———____ Santenononeil ;
( Sa? irae 3° anterior on the left valve 2”

posterior right 1
posterior left 2

Ne

Introduction to Animal Morphology. 257

be rudimentary, or the laterals or all may be absent (Mytilus).
The animal may lie permanently on one side, having its
smaller valve uppermost, and this side may be constant for
the species (Oyster, Pecten, &c.), or may vary (Chama). A
few are found in the morphological position with the foot
downwards, fixed (Humphreysia), or free (Lepton). Under
the periostracum in the shell is a layer of prismatic elon-
gated cells; polygonal in section; secreted by the mantle
edge; deeper in the nacreous or mother of pearl layer;
secreted by the mantle surface; constantly increasing in
thickness during life. The prismatic layer is absent in
Cyclas, &c., and the membranous wall of the shell is there
pierced by many pore canals. The outer stratum of this
layer in other shells is pierced by many branching tubes (the
hyphee of a fungus, Ad/ker). Foreign bodies between the
mantle and the shell become coated with this shell layer, and
form pearls. A fine, white, structureless layer underlies the
nacre, consisting of calcareous granules in an organic base-
ment. The sizes of shells vary from 1” to 23’, and the
weights from 3 grains to 300lbs. The colors are white, red-
dish brown, green or olive (the last in freshwater forms).
Irregularities of structure and arrangements are met with
in the shells of the extinct sub-class Endocardines, and in
the living Tubicola, where the animal inhabits a calcareous
tube, to which the valves may be solidified (Aspergillum), or
the right solidified and the left free (Clavagella). In these
the hinge ligament is at first flexible, but becomes calcified.
In Anatinidz a calcareous nodule develops in the hinge carti-
lage.* Shells may have flat processes on each side of the
umbo (auricles, as in Pecten, or, when large, a/ae, as in Perna
Avicula). In Spondylus the teeth are locked, limiting the
motion of the valves. In Pholas, beside the ordinary lateral
valves, there are other accessory shell plates, two umbonal
plates, a dors-umbonal, and a dorsal in place of the ligament.
The shell structure in the teeth of many forms is radiate,
appearing in sections like the mineral Wavellite. Shell con-

* In Venus, Cardium, &c., the cartilage is very small, in a cavity be-
tween the primary teeth.
SS

258 Introduction to Animal Morphology.

sists of conchiolin 4 per cent.; calcium carbonate 94 per
cent.; phosphoric acid, silica, iron oxide, &c., 2 per cent.
The optical properties of the calcium carbonate agree with
those of Arragonite.

The mantle lobes may be free from each other
along the lower margin (wzz/fora), as in Ostrea and
Pecten, or they may be united at one spot, so as to
leave a small hinder excretory and a very wide ante-
rior slit (dzfora). In others the anterior opening is
subdivided by a second union, so that there is an an-
terior or foot opening, a middle or ingestory, anda
posterior or exhalant orifice (¢zfora). The walls of
the latter pair of orifices may unite and be elongated
in the form of a double-barreled tube whose upper
canal is exhalant or excretory, and the lower is inha-
lant (or both may be used indiscriminately, Clark).
Sometimes the anterior or foot orifice is tubular, siphon-
like (Kellia). The mantle consists of epithelium on
both sides of a connective basement, having along its
free border muscular fibres and glands, and contain-
ing blood-vessels, or lacune, and nerves—often ten-
tacles, &c. In Teredo the mantle contains cells like
the cellulose-holding elements of Phallusia. The line
of attachment of the muscular fibres of the mantle to
the shell is called the fadlzal line, and is roughly pa-
rallel to the lower edge of the shell, often interrupted
(Ostrea, Saxicava, Panopea, &c.) When a siphon
exists, the hinder edge of the pallial line is indented
by a deep Zallial stnus whose fundus points forwards,
and whose depth is proportional to the length of the
siphon (sometimes as in Cyclas a siphon may exist
with no pallial sinus). The wall of the siphon con-
tains circular fibres around each tube, and longitudi-

Introduction to Animal Morphology. 259

nal retracting fibres over the wall of both tubes. The
distal end of the siphon is often fringed by sensitive
processes (siphonal tentacles, as in Mya).

The mouth is directed forwards, and bordered by
two or more ciliated, sensitive, labial tentacles,* like
the base of the arms in Brachiopoda. There is no
odontophore, nor salivary gland (Teredo has two irre-
gularly-lobed, oral glands with a common duct). The
cesophagus is short (long in Teredo); the stomach
globular or oval, and the intestine has one, neural, or
2-12 flexurest (most numerous in Cardium). On the
right of the stomach there opens a cecal pouch im-
bedded in the liver, or between it and the genital
gland, containing a curved crystad style, or transparent
rod, rounded at one end, which is often attached by a
triangular process, flattened or pointed at its free end,
and made of tesselated epithelium, sometimes lamel-
lar, or with calcareous particles in it: this is irregu-
larly periodic in development, being largest after the
winter. Its cecal pouch has a valvular opening, and
rarely is rudimental, the style then lying in the intes-
tinal tract ; itis only present in Anomia among the
Monomya, absent in Ostrea, &c., and is sometimes
absent in Cyclas, Pisidium, and Galeomma. It may
act as a gizzard. The intestine having traversed the
liver, next pierces through the ventricle of the heart
(except in Ostrea, Anomia, Teredo); then, passing
over the main (posterior) adductor, ends in the cloaca.

* Small in Lucina, Corbis, &c.

t Unio has three concentric coils, of which the first is marked by a pair
of longitudinal ridges on its mucous membrane; the second, which pro-
jects into the foot, by transverse folds, and the third by longitudinal
ridges.

S 2

260 Introduction to Animal Morphology.

A. solid diverticulum passes from the upper surface of
the intestine behind the muscle in Pinna (the trachea
of Polz). The cloacal may be quite separate from the
branchial chamber. The liver is many-lobed, acinose,
often mixed with the sex gland, and opening by two,
three, four, or many ducts, into the stomach and up-
per end of the intestine.

The foot or ventral surface of the body is usually
laterally compressed, sharp-edged, never trifid, nor
provided with an epipodium ; it may be straight (cor-
mopoda) or bent on itself (pelecypoda), ploughshare,
or club-like, or rudimental, in sessile forms (Ostrea,
Anomia),* ormay be provided with a gland secreting a
silky chitinoid material (byssus), whereby the animal
is anchored.

There are two pair of retractor muscles for the foot (one
pair in Dreissensia), the anterior arising from the inner sur-
face of the shell close to the umbo, the posterior being near
the attachment of the hinder adductor. (An additional pair
of retractors, behind the anterior adductor, exist in some
Unionide.) There is one protractor of the foot arising be-
hind the anterior adductor and passing in front of the foot.
The muscles are smooth and longitudinally striped. The
base of the foot receives the liver, digestive canal, and sex
gland.t In boring forms it is cylindrical, and has siliceous
particles in its dermis. The foot may be pierced by an open-
ing (Unio), leading into a long canal which ends in lacune ;
from these the water flows when the foot is suddenly retracted.
Galeomma has a double canal; Cyclas has many sitve-like
openings; Mactra one large aperture.t The byssus gland is

* ZEtheria, the freshwater oyster of the African rivers, has a large foot.

t Cryptodon has a long cylindrical tentacle-like foot, with no viscera
extending into it, and the liver and sex organs in branched processes lying
between the gills. The foot is pillar-like in Arca.

} Openings are found in Solen, Cardium, and many others.

Introduction to Animal Morphology. 261

a tongue-like process, grooved at its base, single or lobed,
having part of the foot retractor, or a special muscle inserted
into it as a retractor; the form of the threads depends on the
grooves of the byssus organ, and we may find them each with
a rind, and consisting of separate threads ( Mytilus, Malleus,
Dreissensia, Pecten), or with a rind, but not consisting of
threads (Arca), or with no rind and its root broadly expanded
(Lima, Meleagrina), or without an expanded root (Pinna,
Perna). A byssus gland may exist in the embryo, vanishing
in the adult (Unio, Cyclas). The shelly plug whereby Ano-
mia is anchored seems to be of this nature, and a retractor
muscle is attached to the plug. The foot and other parts
secrete phosphorescent mucus in Pholas and Lithodomus.
The foot is the organ of locomotion. Lyriodon has been
seen jumping four feet high by its contraction.

The shell is closed by adductor muscles which
pass transversely from one valve to the other; they
are attached to scar-like muscular impressions con-
spicuous on each valve, and are usually two in num-
ber (Dzmya) ; sometimes close together, or even fused
(Tridacna). In Miilleria and A‘theria there are two
adductors in the embryo and only one in the adult ;
others (JZonomya) have but one (posterior) adductor.
In Anomia there is a third muscular scar, hence the
name 77zmya has been given to it. Thetwo in Dimya
may be similar in size (/somya), or form (Homomya) or
dissimilar (Heteromya). Some, as Pecten, with small
foot, swim by alternate closure and opening of the
shell.

The heart lies in a part of the body cavity called
the pericardium,* under the hinge line and above and
behind the liver; it is lined by tesselated epithelium.

* Anomia has no pericardium,

262 Introduction to Animal Morphology.

On its upper surface are two dark-brown crescentic
membranous folds, pierced by fine reticular openings,
and surrounded by capillary lacune (the red-brown
organ of Keber): these, with the ducts of the organ of
Bojanus, serve as outlets from the pericardium. The
heart has one ventricle with a spongy interior, tra-
versed by the intestine ; in Ungulina the latter only
traverses the wall of the heart, and does not enter its
cavity. In Arca the intestine splits the ventricle in
two; in Ostrea, Anomia, and Teredo, the heart lies
under, and is not pierced by, the intestine. Two au-
ricles (one in Anomia)* receive the blood from the
gills, and transmit it through a two-valved auriculo-
ventricular opening into the ventricle, from the front
of which arises the anterior aorta (see Fig. 31°),
whose branches supply the foot, mantle, anterior ad-
ductor, &c. In Anomia this vessel has an arterial
bulb at its base. The ventricle gives off behind the
posterior aorta (absent in Teredo), which passes be-.
tween the foot muscles to the pericardium, organs of
Keber and Bojanus, intestine, &c. The large vessels
have coats and an epithelial lining, but end mostly in
wall-less lacune ; sets of true capillaries, however,
having structureless walls with scattered nuclei,
exist, as an erectile layer in the foot, mantle, and in-
terbranchial septum, and as arborescent branching'’s on
the intestinal wall. The blood is returned by veins,
partly into the venous sinus, under the organ of
Bojanus,t or into that organ itself, or directly into

* The two auricles unite in the oyster.

t In Arca each ventricle gives off an aorta, and the two unite to form
a common trunk.

t This sinus receives one branch from the erectile tissue of the foot,.

Introduction to Animal Morphology. 263

the auricle. In the organ of Aozanus the blood
becomes mixed with water, and thence passes by
channels (branchial arteries) to the gills, and is re-
turned by sacculated bronchial veins into the auricle.
The heart beats 5-10 times (Unio), or 20-30 times
in a minute, and continues to act after the animal is.
taken out of the water. The sinus venosus and
bloodvessels have no propelling power.

The gills are lamellar, placed longitudinally on
each side between the mantle and the foot, having the
free borders directed ventrally. They are usually
symmetrical (except in inequivalve genera, particu-
larly in Anomia), and in two pairs on each side
(Corbis, Lucina, and many other Lucinide, have but
one pair); of these, the external are the smaller and
the later in development. Each gill lamella consists
of two layers of comb-like* filaments, which are free
(Arcide, Pecten, Trigonia, Spondylus), or united by
horizontal bands into a continuous multifenestrated
plate, supported on a framework of chitin rods, ar-
ranged in rows behind each other, and richly ciliated
on the surface. The layers are more or less united,
directly or by a connecting membrane. The inner
gill lamella may adhere to the foot, leaving an inter-
nal branchial channel between them; the outer la-
mella may be unilaminar; the space between the gill-
lamellz is the interbranchial chamber. The ciliary

two from the viscera, and one from the mantle. Its blood is poured into
the organ of Bojanus.

* A lamellibranch is aptly compared by Keferstein to a book whose
back is represented by the hinge line, its cover by the shell valves, its fly
leaves by the mantle lobes, its second and third pages at each side by the
gill lamellz, and its interior by the visceral sac and foot. In Anomia the

sickle-like gills are removed from the visceral cavity, and do not extend
as far as usual.

264 Introduction to Animal Morphology.

motion of the gills of marine bivalves is immediately
checked by immersion in fresh water.

The organ of Bozanus is yellow or brown, spongy,
bilaterally symmetrical, placed dorsally next the base
of the gills, the lateral parts being sometimes medially
united.

It is tubular, opening within into the pericardium bya
radially lamellar extremity which surrounds the tendon of the
posterior retractor, and lies on the front and lower surface of
the hinder adductor; its central part is sometimes dilated
into a spongy cavity; the outer part opens on each side into
the mantle cavity. Into its spongy tissue the blood from the
viscera enters by a portal system of vessels, and mixes with
water, admitted by the duct of Bojanus. In its recesses in
Lutraria and Mactra uric acid is found, and, in Pectunculus
pilosus, granules of calcium phosphate. In Teredo this or-
gan is a dark layer, containing urate of ammonia, overlying
the auricle of the heart ; in Ostrea it is also appended to the
auricle close to the commissure between the epipharyngeal
and visceral ganglia, and contains concretions. The sex or-
gan opens into this organ in Pecten, Lima, and Spondylus, or
the duct of the sex organ unites with its duct in Arca, Modi-
ola, and Mytilus; in Pinna they open on the same papilla,
but the sex duct is the farther back. The ducts are separate
in Cardium, Chama, Pecten, Unio, &c. This is a modified
segmental organ; its cavity is regarded by Aolleston as a
water-vascular organ; its function is excretory, probably uri-
nary.

The nervous system consists of—1st, an epipharyn-
geal (labial, cerebral) ganglion on each side, either re-
mote and with a long commissure (Lucina, Arca,
Mytilus, &c.), or close together (Venus, Mactra, &c.) ;
or united (Teredo); this lies on the tendon of the re-
tractor pedis anterior, and in front of the protractor
pedis, above the mouth, and gives off on each side

Introduction to Animal Morphology. 265

labial, pallial and anterior branchial branches. The
hypopharyngeal ganglion is united to the former by two
commissures, one on each side of the digestive canal.

It is sometimes close to the first ganglion (Pecten), but is
usually remote, placed in the foot, hence itis called the pedal
ganglion (or, from its describer, the Mangilian). When the
foot is small or absent, the ganglion is small or obsolete, as
in the oyster; it is also small in Teredo. It sends branches
to the retractors of the foot, to the adductors, to the body
wall, but none to the viscera. From the epipharyngeal gan-
glion two lateral commissures pass backwards to the front of
the hinder adductor, where they unite to form a visceral or
anal ganglion, giving off a posterior branchial, and lateral
and posterior pallial branches (the first of these branches in
Ungulina has a separate ganglion on it atits origin). These
ganglia are usually bright yellow, translucent, and contain round
fat cells, small, colorless, medullary cells, and non-meduilated
nerve fibres. ‘They are symmetrically disposed in equivalve
forms, but are unsymmetrical in inequivalves. <A few fila-
ments from the epipharyngeal ganglion represent the labial
nerves of Brachiopods. In Unifora there are two long circum-
pallial nerves along the margins of the mantle lobes ; some-
times there are small ganglia along this line in Trifora, as in
Solen.

As organs of sense, there are, 1st, labial tentacles ;
2nd, marginal tentacles, supplied by the circumpallial
nerve; thread-like in Lima, Pecten, &c.; thicker and
contractile in Donax and Mactra, sometimes highly
extensile (Lepton). In siphonate forms these are
grouped about the mouth of the siphon. In Unio
there are a few papillary tentacles at the hinder end
of the mantle border. A siphonal ganglion supplies
these in the siphonate forms; 3rd, otocysts exist, one
on each pedal ganglion ; they are oval, with a homo-

266 Introduction to Animal Morphology.

geneous basement membrane lined by ciliated epithe-

lium, and filled with fluid, holding one or more glo-

bular otoliths, which during life rotate rapidly; they

have either one nerve in each (Unio), or else they lie

directly on the ganglion ; sometimes they are deeply

imbedded in the foot (Cytherea); 4th, eyes exist in

the larve of all as pigment spots with a lens, seated

on the head under the velum; these in the adult are

lost, but secondary eyes develop as pigment specks,

with neither nerves nor crystal cones, as the siphonal

eyes of Solen and Mactra, or else as true eyes along the

mantle edge, sessile or stalked, consisting of cornea,

lens, crystal cones imbedded in pigment, iris with a

movable pupil, and in Pecten and Spondylus there is

a tapetum cellulosum. Into each eye in Pecten’ two

branches from the circumpallial nerve enter, one into:
the fundus, and one into its side; these eyes may be

from 8 to 90 in number, and are often brightly
colored. The senses and psychic phenomena in la-

mellibranchs are of a low order, but a degree of me-

mory is evinced if it be true that oysters taken from

beds occasionally uncovered at low water never open

their shells, while those taken from greater depths are

more careless about the opening and closure of their
valves.

Lamellibranchs have symmetrical, usually dicecious
sexual organs, with no accessory apparatus; some
(Ostrea, Pisidium, Pandora, Kellia,Galeomma, Cyclas,
&c.), are monececious. In Ostrea the ovigerous and
spermigerous acini are mixed side by side in the one
gland.* In Pecten varius the gland is bilobed, the

* But according to Davaine they are not functional together, but pro-
tandrous, the male acini reaching perfection when the females are unripe,

Introduction to Animal Morphology. 267

male lobe being above and in front, the female being
below and behind, but the ducts are united, as in Cy-
clas. In Pandora the two lobes, now separate, have
separate ducts, as in Clavagella. In the dicecious
Margaritana, islands of ovary have been found in the
testis. In Mytilus the gland is entirely overlapped
by the mantle lobes. In Anomia it is in the under
(right) lamella of the mantle. The gland is usually
under and beside, often inseparable from, the liver
(not so in Pinna), anterior to the hinder adductor, and
in the side of the visceral sac. The genital opening,
when separate from the organ of Gozanis, is on each
side at the base of the abdomen. Kellia, Montacuta,
and Galeomma are viviparous; in others the eggs are
hatched in a gill pouch (Spherium, Cyclas, &c.), or in
the interbranchial chamber. Most bivalves are proli-
fic; one Unio lays 3,000,000, and one oyster 600,000
eggs in a single season. The eggs have usually an al-
bumen layer, thickened into a pillar-like process (mi-
cropyle) at one end; development begins by a rotation
and cleavage of the yelk and the formation of a larva
with a unilobar velum, often with a flagellum. The
mantle (or in Cyclas the foot) is the first part to be
developed, and the other viscera follow.

The 14,000 recent and fossil Lamellibranchs are divisible
into two sub-classes :—

Sub-class 1. Endocardines—extinct, with rough reticu-
lated shells, with unequal valves, the right attached to
foreign bodies; umbones displaced from the margin to
near the middle of the shell; ligament internal; hinge

so that according to season an oyster appears wholly male or wholly female.
This statement has been called in question.

268 Introduction to Animal Morphology.

teeth on the free valve alone, allowing the valves to move
parallel to each other; the mantle lobes uniforal, dimyary.
These form one family (Hippuritide) and eight genera,
from the cretaceous rocks, except the miocene Tamiosoma.

Sub-class 2. Exocardines—shell not reticulated ; umbones
smaller, marginal; ligament external; valve-opening hinge-
like ; teeth usually on both valves. This includes the follow-
ing orders :—

Order 1. Monomya (Zamarck)—with one adductor, liga-
ment nearly internal; mantle uniforal; hinge nearly or quite
toothless, with one circumpallial nerve; no pallial sinus nor
siphon, and an inequivalve shell. This includes the follow-
ing families:—Anomiadz, with unsymmetrical body, no
labial palp, nor eyes; arched hinge line, obsolete ligament,
and the under valve pierced for the calcified byssus; rarely
free, with transparent shells (Placuna). Ostreidz, with labial
palps separate from the gills; foot obsolete ; ligament inter-
nal in one conical groove; shells sessile; lamellz rarely free
(Ostrea), smooth (Gryphza). Spondylide, with straight hinge
line; ligament half-external ; a triangular hinge area on the
shell; teeth two, locking, rarely none (Pedum); foot small,
pointed. Radulidz, with gaping shells ; long pallial tentacles ;
no ocelli; foot not byssiferous (with a byssus, Svolzcza); hinge
toothless. Vulsellidz, with long compressed shells; narrow
gills, much produced posteriorly, united together and to the
mantle at their border; rectum simple. Pectinide, with no
hinge area; mantle with ocelli; gills equal; foot small, cy-
lindrical, sometimes byssiferous. ‘The shells are auricled,
usually regular, smooth (Amussium), or radially ridged (Pec-
ten), rarely unsymmetrical (Hinnites). Aviculidze, with ter-
minal, not medial umbo, except in Crenatula; shells one or
two-winged (Avicula), sometimes hammer-shaped (Malleus) ;
foot small, byssiferous, for which one valve is grooved.

Order 2. Heteromya—muscular scars double, unequal,
sometimes, as in Miilleria (fam. A®theriidze), becoming mo-
nomyary in the adult. The shells of the rest are usually equi-
valve, or nearly so, the ligament external; there are never
lateral teeth, and the cardinals are weak; mantle uniforal
(Pinnidz) or biforal, with a wide pedal slit (Mytilidz). This

Introduction to Animal Morphology. 269

family includes Mussels (Mytilus) without (and Crenella, Mo-
diola and Lithodomus with) false siphons. Dreissensida—
umbones terminal, each with a shelf-like septum, and a trifo-
ral mantle. Modiolarcide—triforal; with no septum in the
non-terminal umbo.

Order 3. Isomya.—adductor scars two, equal or sub-
equal on each valve: this order contains two sections :—
§ 1. Integropalliate—pallial sinus none; shell regular,
rarely gaping ventrally, with hinge teeth: this comprehends
five sub-orders: rst Arcacee—mantle edge free, rarely si-
phonate (Ledidz); hinge teeth, many; cleft, symmetrical ;
foot large; its families are :—Arcide—uniforal; hinge teech
in a straight line; gills sub-pinnate; oral tentacles as
processes of the gills ; byssus present (Arca) or none (Pectun-
culus). Nuculidee—hinge teeth serrate ; shell anteriorly elon-
gate; ligament internal. Ledide—labial tentacles long,
convolute; siphons retractile ; ligament internal (Leda) or
external (Malletia). Sub-order 2. Trigoniaceze—uniforal ;
hinge teeth v-like, diverging ; mantle-edge with eyes; foot
bent, for leaping ; including one family mostly of fossil forms,
ex. Trigonia. Sub-order 3. Unionacez (Naiades)—uniforal
(siphonate in Spatha, &c.); one family of freshwater, olive
shells with thick epidermis, nacreous within ; foot not byssi-
ferous (except Byssanodonta); embryos with at first only
one adductor; cardinal teeth present, with (Unio) or without
lateral teeth (Baphia), or absent, with (Barbala) or without
laterals (Anodonta). Sub-order 4. Lucinaceze—biforal (ex-
cept Astartidz); anal opening simple ; foot cylindrical. The
families are: Lucinide—equivalve ; a branchial siphon;
gills one pair; anterior adductor scar round (Corbis), double,
(Cryptodon), or band-like (Lucina). Astartide—uniforal ;
gills two pair, with bearded edge; lateral teeth one or none;
ligament in a groove (Crassatella), or external; foot rarely
with a byssus (Mytilicardia); shell concentrically (Astarte)
or radially ribbed (Cardita). Galeommidze—byssiferous; an
anal siphon ; gills two pair; mantle edges projecting through
the gaping shell. Leptonide—siphonal, byssiferous; foot
ligulate or tapering ; mantle with (Lepton), or without ten-
tacles ; ligament internal (Montacuta) or external (Lasea, &c.);

270 Introduction to Animal Morphology.

a long anterior mantle tube, open (Lasea), or closed be-
low (Kellia). Ungulinide—foot hollow, worm-like, with a
terminal erectile gland; four foliaceous oral palps. Sub-
order 5. Chamacez—siphons short, separate; foot small or
rudimental ; shells unequal; inner gill pair small. The fami-
lies are: Tridacnide—muscle-scars united ; anus with tubu-
lar valve ; outer gills unilamellar; shell thick, with (Tridacna)
or without a byssus (Hippopus). Chamidz—shells adherent,
irregular, inequivalve, umbo spiral; two outer gill plates
united behind ; anal valve simple. Sub-order 6. Cyprinaceze—
often triforal; gills unequal; foot large. Families: Cypri-
nidae—foot byssiferous ; umbo spiral in Isocardia ; epidermis
thick; mantle open in front and below; siphons wide, short ;
teeth 2-3 cardinal and 1 lateral. Cyrenidz—mantle open in
front; margins simple; epidermis thick; hinge teeth 3.3 or
2.2; siphons diverging (Cyclas), or united (Pisidium). Car-
diidee—Cockles, pelecypodal; siphons short, sessile; shell
equivalve, radially ribbed (Cardium), or smooth (Lzvicardium,
&c.

§ 2. Sinupalliata—pallial line with a deep sinus, mostly
pleuroconchal. This includes four sub-orders. Sub-order 6.
Veneracez—siphons moderate ; mantle wide, open in front ;
foot large, pointed; gills four. The families are: Veneride—
foot long, slender; siphons united at base or for the whole
length (Dosinia) ; hinge teeth 2-3, with often a tooth under
the lunula, but no other lateral tooth; a byssus in Tapes, not
in Venus. Petricolide—foot with a byssal groove; siphons
unequal, separate to their base; shells gaping posteriorly.
Sub-order 7. Tellinacez—siphons long, fully separate; mantle
wide open in front ; outer gill lamellar, often rudimental ; foot
large. Families:—Paphiide—hinge cartilage present; si-
phons thick, separate from the base; foot tongue-like ; shell
close; pallial sinus small. Scrobiculariide—hinge cartilage
present: siphons long, unequal; shell gaping behind ; foot
pointed, not high. Cumingia bores in coral, &c. Tellinide—
hinge cartilage none; ligament strong, external; gills un-
equal; hinge teeth one or two; lateral teeth absent (Psam-
mobia), or present (Tellina). Donacide—hinge cartilage
none; shell wedge-shaped; siphons shorter. Sub-order 8.

Introduction to Animal Morphology. 27a

Myaceze—siphons long, united; gills not extended thereinto;
shell gaping behind, with an inner hinge cartilage; shell and
siphons covered with periostracum. Families :—Glaucono-
myidze—mantle lobes open sufficiently for the protrusion of
the keeled small foot. Solenide—body long; mantle open
fore and aft; hinge anterior, terminal; byssus none. Saxi-
cavide—elongate foot with byssus groove ; cartilage small
or none; pallial line interrupted (Saxicava), or continuous
(Panopea). Anatinidze—quadriforal ; hinge with ossicles; gills
unilamellar, the one larger in Thracia being subdivided intotwo
half lamellz ; shell with an outer layer of fine prismatic cells
(Pandora, Mydora). Mactride—ligament internal; siphons
united ; labial tentacles long, pointed; foot straight; shell
gaping (Lutraria) or closed; outer ligament separated from
the cartilage by a shell ridge (Trigonella, &c.), or united to
it (Rangia, &c.); mantle lobes separate (Mactra, &c.), or united
(Lutraria, &c.). Corbulida—mantle lobes closed; cartilage ina
spoon-like pit; oral palp small; siphons short, with cirri at
their openings; foot with a byssus groove. Myide—mantle and
cartilage as in last ; foot not byssiferous. Sub-order g. Phola-
dacez—siphons long, united; gills elongated into them; shell
small, only covering part of the body, whose surface often se-
cretes a calcareous tube; borers. Families: Gastrochznidze—
tube-dwellers; body clavate; shells small, equivalve ; tube closed
in front ; shell valves free in the tube (Gastrochzna), or the left
attached and the right free (Clavagella), or both fused (As-
pergillum). Pholadide—body symmetrical ; mouth-lobes
long; foot short; hinge teeth none; siphons either bearing
loose shelly plates at their end (the faletfes of Teredo, the ship-
worm), or with no fale¢fes and rough, sculptured shells, as in
the stone-boring Pholas. Kuphus has palettes, but no true
shelly valve. Pholas has two triangular organs, covered with
cilia, and containing fat and granular protoplasm, near the
upper end of the mantle, which are the seats of its lumino-
sity (Pancer?).

272 Introduction to Animal Morphology.

CHAPTER XXXVI.
CLASS 2.—CEPHALOPHORA (Blaznville).

OTOCARDIANS with a head, bearing sense-organs, and
a mouth with, on its floor, a masticatory apparatus or
vadula, placed on an eminence partly muscular and
partly cartilaginous; on this radula are transverse
rows (joints) of irregularly shaped, but regularly dis-
posed, teeth of conchiolin. Except in the first sub-
class, the body is not fully covered by the mantle,
which usually secretes a one-valved shell, often with
a separate posterior, but not articulating portion.
Three sub-classes are included :—

Sub-class 1. Scaphopoda (#ron2)—marine, dice-
cious, symmetrical forms, linking the next group to
the bivalves; forming whitish, small, tubular, ele-
phant’s-tusk-shaped shells, concave dorsally, and open
at both ends.

The shell is concentrically laminated, each new layer
underlying its predecessor, and extending farther forward,
with no periostracum, and thicker behind than before ; its
surface layer is homogeneous, on a prismatic stratum whose
columns bend inwards and outwards alternately as in Patella;
the lining vertically striated laminz appears crenate on
transverse section. The oldest part (narrow end) of the shell
is often traversed by a fungus. Two or four oblique dorsal
muscles (like the columellaris of Gasteropoda) attach the
animal to the shell.

The mantle is thick in front, and has no outer
epithelium nor glands, but many pigment specks and
transverse ciliated folds; posteriorly it has a spoon-

Introduction to Animal Morphology. 273

like process, in front, many unequal sucker-like ten-
tacles: its fore and hinder openings have sphincter
muscles. The front of the head is joined to the buccal
region by a narrow fseudo-collum. Eight radiating
ciliated tentacles surround the mouth, into which two
salivary glands, and two, ciliated, glandular, buccal
pouches open. The buccal cavity is guarded in front
by a valve, and contains an oval, wide radula of 25-30
joints, each of five plates, the median one-toothed, the
inner lateral uncinated, the outer lateral unarmed ; it
lies on a tongs-shaped lingual cartilage whose branches
are approximated below by one transverse adductor,
and divaricated by two sheathing muscles. Two ru-
dimental conchiolin-covered pharyngeal jaws oppose
the radula. The cesophagus is short, the stomach
gizzard-like, receiving the paired bile ducts; the
glandular intestine has a primary neural flexure, and
forms three folds under and parallel to the cesophagus,
finally passing between the two organs of Bozanus,
and through the anal sinus to its termination behind
the foot. The liver is large, triangular, of one (Sipho-
nodentalium) or two (Dentalium) lobes consisting of
ceeca lined by large, polygonal, coloured cells.

There is no heart, but the colourless blood accu-
mulates in five, wall-less, lacunary sinuses, anal (the
largest), post-abdominal, buccal, cervical, and pedal.
From the post-abdominal sinus, it enters an anterior
mantle vessel, forming a vascular ring, from which,
and from the other sinuses, richly netted lacune pass
into the mantle and foot, which act as breathing organs,
there being no gills. The anal sinus has a pair of
outer openings, one on each side of the anus, whereby
water is admitted.

Ab

274 Introduction to Antmal Morphology.

The foot consists of a central, obtuse, cylindrical
lobe, hollowed at its base, and two lateral, symme-
trical, wing-like epipodia. The organs of Bozanus are
symmetrical, brown, compact, of many follicles lined
by gland cells, lying on the rectum; they open into
the hinder part of the mantle cavity, and the right
receives the genital duct.

There are two pear-shaped epipharyngeal ganglia,
joined by a long commissure in front of the buccal
mass, and behind the pseudo-collum ; from these arise
two pedal commissures, two buccal, two tentacular,
and four mantle nerves (inner and outer pair), as well
as an azygos mantle-nerve. The hypopharyngeal
(foot) ganglion is close to its fellow, gives off many
(nine) foot nerves, and each has seated on it a sphe-
rical, ciliated otocyst containing many rapidly-moving
otoliths. A pair of anal ganglia are attached to-
gether by a fine thread, and to the epipharyngeal by
two filaments. Besides these are two anterior and
two posterior sympathetic ganglia, joined by commis-
sures, lying on the intestine. There are no eyes, but
the animal retracts its foot if exposed to light.

The long, lobed sex-gland differs in the male and
female only in the nature and colour of its contents,
being white in the male, red and yellow in the female.
It fills the entire (Siphonodentalium) or front (Denta-
lium) of the metasoma, and has no accessory organs.
The eggs have shells, and form on stalked processes
in the ovary; when impregnated, the yelk rotates,
segments, and forms a ciliated gastrula, which elon-
“s gates, and the external cilia form seven complete
circlets, the foremost of which dilate into a velum,
and the others vanish. On each side posteriorly a

ss

Introduction to Animal Morphology. 275

scale-like shell forms as a partial bivalve investment ;
the three-lobed foot then forms, the shell valves unite,
become tubular and elongated anteriorly.

The one family, Dentaliidea, includes ten genera,
of which Dentalium and Siphonodentalium have an
entire-margined hinder opening. Antalis has the
hinder opening with a deep side notch. Dentalium
has a short, thick foot; in Siphonodentalium it is long
and cylindrical.

Sub-class 2. Pteropoda (Czvzer)—small, active,
marine, crepuscular, carnivorous forms, with rudi-
mental head and sense-organs, and large epipodia,
symmetrically developed as ‘“‘fins,’’ one at each side
of the anterior end. These are composed of two or
more layers of muscular fibres in a firm connective
base, covered by tesselated epithelium, sometimes
with rows of cilia (Styliola). By their rapid to and
fro wavings, these fins act as swimming organs;
rarely a second pair of linear fins lies behind the front
pair (Cymodocea). The rest of the foot is rudimental,
with separate elements. The propodium in Pneumo-
dermon, Clio, &c., is elongated into retractile, lateral,
circumoral processes, like the arms of Cephalopoda,
armed with stalked or sessile (Spongobranchia) suck-
ing discs. The mesopodium is often horseshoe-
shaped, or both these parts may be absent (Cleodora).
The metapodium in Limacinide bears a few-whorled,
spiral operculum.

The mantle may be none, rudimental, or developed, se-
creting a shell on or in its texture, and this, with the mantle,
may be persistent or lost in the adult (Cymbuliide). Its
lobes may bound a cavity opening ventrally (Cleodora), as in
Cephalopoda, or dorsally (Limacina) by a slit directed for-
ward behind the epipodia. The shell may be of pure con-

gh

276 Introduction to Animal Morphology.

chiolin ; when calcareous it is rich in phosphates, and con-
sists of a periostracum, a layer of vertical prisms bent a little
at their inner ends, and an irregular granular layer within; in
shape it may be of united dorsal and ventral valves, globular,
acicular or spiral, sinistral in Spirialis, Limacina, Heterofusus,
dextralin Cheletropus. There is a retractor muscle for the
drawing in of the body. The shell-less forms have an inte-
gument of cellular connective tissue, with longitudinal (ex-
ternal) and circular (internal) muscular fibres,* containing
calcareous grains, pigment cells,t and fat-secreting glands.
under a layer of cylinder epithelium.

The mouth is anterior, round, or slit-like, with or
without lips; in Tiedemanniaitisona proboscis. There
is a radula present (except, perhaps, in Halopsyche
and Tiedemannia), whose base is retractile into a
sheath; it is armed with five rows of teeth, an
axial series bordered by two intermediate and two
lateral rows. In Clione there are bundles of lateral
teeth at each side of the mouth, whose bases are im-
bedded in muscular tissue. Clione and Pneumoder-
mon have eversible sacs, one at each side of the
radula, sunk in deep pits, and armed with recurved
hooks; these can be protruded as prehensile organs.

The straight cesophagus has a crop-like dilatation
in Tiedemannia, and ends in the oval or fusiform
stomach, which has strong muscular wallst, some-
times with teeth of conchiolin and longitudinal folds
(Hyalea). The pylorus is at the centre of the length
of the stomach, and the short intestine has first a

* Either smooth, homogeneous, of fused cells, or branched, stellate

fibre-cells.
+ Tiedemannia has stellate chromatophores, with or without muscular

processes.
t Circular externally, longitudinal internally; with a connective basis

and a ciliated lining.

Introduction to Animal Morphology. 277

neural flexure, except, perhaps, in Limacina. The
anus is mostly lateral, near the front edge of the
mantle, or in shell-less forms under the fin. The
salivary glands are tubular ceca in Clione and Pneu-
modermon, rudimental or absentin others. ‘The liver
is large and lobed in Thecosomata, or as numerous
yellow or green gastric cecainGymnosomata. These
organs lie in a single or partly divided sac.

The heart, which is not rhythmic in action, lies in
front of the visceral sac(Cymbulia), to its right (Pneu-
modermon), to its left (Limacina), or within it, and con-
sists ofan auricle with thin walls of branched muscular
fibres, ciliated within, and a globular or pear-shaped
ventricle of thick, transverse muscle, non-ciliated,
having a double auricular, and one (Hyalea), two
(Styliola), or no (Cleodora) aortic valve. The aorta
sometimes begins in a bulb, and gives an anterior
cephalic branch, traversing the nervous collar to the
epipodia, and a posterior, visceral. The heart is ina
thin-walled pericardium in Hyalea, Pneumodermon,
&c. The arteries are thin-walled, and end in lacunae,
as there are no capillaries nor veins, unless the
channel from the front of the kidney to the gill-shield
in Styliola be considered as a vein. From the lacune
the blood enters the auricle. The gills may be two,
absent (Pelagia), or crescentic lateral folds in the
mantle cavity (Hyalea), or a ciliated shield on the
ventral side of that cavity (Styliola), or the lining of
the whole or part (Limacina) of the mantle-sac, or ex-
ternal leaf-like appendages (Pneumodermon), or an
outer terminal ring (Spongobranchia), or a median
ciliary girdle (Trochocyclus). The excretory organ
(kidney) is tubular, with one opening within the

278 Introduction to Animal Morphology.

mantle or beside the anus, and a second, surrounded
by a sphincter, into the pericardium. This organ
may be hyaline (Cymbulia, Clione), or thick, con-
tractile (Styliola), or soft, spongy, and glandular
(Hyalea, Cleodora). Beside it in Pneumodermon is a
wheel-like ciliated body of unknown function.

There is a circum-cesophageal nerve-ring with two
large, confluent, sub-cesophageal ganglia, joined by a
commissure over the cesophagus; from these pass
branches to the epipodia and to the body wall. A
sympathetic ring with one or two pair of ganglia sur-
rounds the intestine lower down. In Pneumodermon,
Clione, &c., there are two or, usually, three, rarely
four, pair of united ganglia, the hypopharyngeal bear-
ing otocysts, with mulberry-like otoliths. These
ganglia consist of oval or unipolar nerve cells. The
head bears paired, large (Theceurybia), or small
(Hyalea) tentacles, which are rarely seated on the
front of the fins (Limacina and Styliola virgula), or
absent (Halopsyche). There are three pair of feelers
in Clione australis. Anterior feelers in Clionopsis are
supposed, but without sufficient reason, to be olfactory.
Eyes represented by pigment specks are found on the
visceral sac of Hyalea. Similar masses with lens-like
bodies lie on tentacle-like processes on the neck in
Cleodora and Styliola acicula, &c.

The single, lobed, hermaphrodite gland lies behind
the stomach and beside the heart in the visceral sac:
its duct dilates into a seminal vesicle, receives the
duct of an albumen gland, and a small receptaculum
seminis, and then ends in a vagina, in front of which
is the eversible imperforate penis. The outer part of
the gland produces ova, the inner, spermatozoa; but

Introduction to Animal Morphology. 279

the two parts are not functional together. The ova
completely segment, and produce rotating embryos,
developing one, rarely three, ciliary circlets, the front
one of which becomes a bilobed velum. This is lost
as the foot and epipodia develop.

There are two orders, including twenty-three genera and
ninety living species :—

1. Thecosomata (Blainville)—having a shell, an indistinct
head, gills in the mantle cavity, and a 2-5 rowed radula.
Families :—1. Hyaleide—shells inoperculate, symmetrical,
subulate (Styliola), triangular, depressed (Balantium), inter-
nally septate (Triptera), or globular, with a lateral slit
(Cavolina). 2. Thecide—Palzozoic, operculate, gill-less,
with straight shell. 3. Limacinidze—operculate, sinistrally
spiral, turreted (Heterofusus), or helicoid, open in Eccyliom-
phalus. 4. Cymbuliide—shell internal; fin not retractile ;
gills none, ex. Tiedemannia, Halopsyche. The fossil families,
Conularide and Tentaculitidz, unite these to Hyaleidz.

2. Gymnosomata (Blaznville)—shell and mantle absent ;
head and foot distinct; larva with several ciliary zones.
Families :—1. Clionide—gills none; epipodial lobes one
pair; head with a pair of stalked eyes, three pair of head
cones, and two (Clione), four (Clionopsis), or no (Cliodita)
tentacles. The footis rarely absent (Pteropelagia). 2. Pneu-
modermonidz have external gills diversely placed as noted
above.

280 Introduction to Animal Morphology.

CHAPTER XV
SUB-CLASS 3.—GASTEROPODA (Cuv7er).

CEPHALOPHORA, whose bilateral symmetry is often
hidden by the spiral coiling of the body. The undi-
vided mantle secretes a shell which consists of one,
two (rarely eight), pieces, antero-posteriorly, never
laterally, disposed. The head bears 1-3 pairs of ten-
tacles over the mouth. The foot is elongated, ventral,
muscular, often fitted for creeping (their commonest
mode of locomotion). This large class includes two
types of structure—ist, water-breathing forms with a
veliferous larva(Branchiata) ; and, 2nd, air-breathing
forms whose larva has no conspicuous velum (Pulmo-
nata). The former may have the gills behind
(Opisthobranchiata), or in front of the heart (Proso-
branchiata).

The skin consists of a cuticle-like epithelium,
rarely ciliated entirely* (Phyllirhoé) in the adult,
always so in the larva,t and a connective basement
containing unstriped muscle; sometimes with clear,
glossy, connective, or cartilage cells (Carinaria, Pte-
rotrachea), often calcareous{ concretions (Opistho-
branchiata§), unicellular pigment glands (Pulmonata),
and pouch-like mucous follicles,|| as well as pigment

* Cilia are widely distributed in Opisthobranchiata. The cilia are most
extensively spread where the gills are smallest. In others the cells are
cylindrical.

+ In Pontolimax a layer of cells underlies the cuticle like a deeper epi-
thelial stratum.

t These often assume specifically characteristic shapes.

§ In Doris these make a form of dermal skeleton.

|| In Elysia these are in pearly rows, and in oval groups in Gasteropteron.

Introduction to Animal Morphology. 281

cells, which are not acted on by muscular fibres (like
the chromatophores of Pteropoda). Cnide, like those
of Turbellaria, exist in clusters on the ends of the dorsal
papille of AZolis and its allies. Bristles arising in
follicles adorn the sides of some Chitons. The sub-
cutaneous muscular lamina is not easily separable
from the dermis, and usually consists of external
longitudinal, and internal circular bundles of flat,
anastomosing, unstriped fibres, not in separate layers
(they are otherwise arranged in Kolidz). These
structures make up the body wall, of which two parts
are generally differentiated—ist, the post-cephalic
neural surface or foot; 2nd, the hemal surface, which
usually forms a mantle. The foot is usually flat, sole-
shaped for crawling, and is then rarely divided.* In
Heteropoda it is differentiated into three parts—pro-,
meso-, and meta-podium—and forms a vertical swim-
ming organ or fin, moving as a screw propeller. The
upper and hinder edge of the foot may be prolonged
into lateral lobes or epipodia, which may be elongated
and wavy (Haliotis, Aplysia, Turbo), large and lobed
(Rissoa), formed into lateral swimming fins (Gaste-
ropteron), or as a pseudo-mantle (Doris). In Stylo-
cheilus the metapodium is very long. The foot is a
thickening of the body wall with well-developed
longitudinal muscular fibres, often with large mucous
glands.t The upper surface of the metapodium bears
often a differentiated area, secreting a shelly structure,

* In Harpa, Ancillaria, Voluta, Oliva, the propodium is indicated by a
transverse groove. In Strombus the pro- and meso-podium are marked
out by grooves. A longitudinal groove divides it in Phasianella, and the
two sides can move independently. Transverse grooves exist in Pedipes
and Auricula brunnea.

+ In Janthina these are large, and secrete the egg-raft.

282 Introduction to Animal Morphology.

the operculum.* The front edge has, in some, two
lip-like, often glandular, processes. The foot is rudi-
mental in Glaucus, or absent (Phyllirhoé, Vermetus,
&c.), or its sole may be reduced to a sucker, as in the
males of some Heteropoda.

The dorsal (hemal) area of the skin behind the
head usually forms a mantle with lateral folds, secret-
ing from its surface, but not by special glands, a
shell, but both disappear; shell and mantle may
vanish early, and the dorsal integument may show
instead, papille (A‘olist), or branched processes (Den-
dronotus), or cirri (Tethys). The mantle may be
margined by a series of tentacles (Haliotis, Parmo-
phorus); its edge is thick and muscular, frequently
fringed with pigment-glands secreting the colours of
the shell. The edge alone secretes the prismatic ele-
ment of the shell. The surface secretes the nacreous
lining. The shell covers the dorsal side of the
animals, and is homologous with the pair of valves.
and ligament of a bivalve, or with the anterior valve
of a Brachiopod; it may be of two kinds, either
symmetrical, limpet-like (and then may have a slightly
coiled apex, as in Calyptreea), or an inner shelf as in
Calyptreea, Crepidula, &c., or a perforate apex as in
Fissurella, or a hinder notch as in Emarginula. The
aberrant Chiton shell is also symmetrical. In others the
shell is coiled, and then may be globose (Natica), sub-
globose, oval, conical, subulate, fusiform, pyriform,

* In Harpa the metapodial lobes are large, and overlap the body shell.
The dermal area referred to here is called the opercular mantle; it may
exist without an operculum, as in Marginella; it may have a collar of ten-
tacular processes round it (Turbo, Ampullaria).

t+ These bear cnidz. No such weapons exist in the Proctonotidz : but
these have terminal openings to their papillze.

Introduction to Animal Morphology. 283

discoid, auriculate, lenticular, &c. They may be
coiled to the left (laotrope), rarely to the right
(dexiotrope) ; in the former the mouth is to the right,
and the shell is called dextral; in the latter to the
left ; hence the form is called sinistral. This may be
normal,* but is often an abnormalty. Coiled shells
are spirals of a peculiar modulus, resembling (and in
Ammonites identical with) the true logarithmic spiral,
usually differing in having a definite point of start-
ing, and forming another geometrical species, the
concho-spiral.t (In Argonauta, of the next class, the
spiral is parabolic, Hezs). In some cases the starting
point of the spiral is at a certain distance from the
centre, and the first whorl runs around a central
nucleus with a definite radius (cyclocentric, concho-
spiral).f In discoidal shells the shape is determined
by the nature of the centre and the ratio of the pro-
gression, as well as the shape of the section of the
chamber§ (which is constant). In most coiled shells,

* Clausilia, Busycon.

+ Ifthe width of the first whorl = the parameter of the spiral a, the
spire in general = #, and the ratio of progression = #; then in the first
whorl, 4 =a; inthe second, =ap; in the third, 2 = af’; in the mm,

h=ap(™),. The radius (7) of the mh whorl = + eae (pm). There

may be two valves for # in the inner and outer whorls, when the spire is said
to be diplo-spiral. This is the case in many gasteropods. My measure-

ments lead me to believe that some land molluscs are triplospiral.
(p-1) ; ifa = at , this be-

+ The radius would then be r=a +
+ Biot

comes logarithmic as x = ag™.

§ It was determined by the Rev. Canon Moseley that the geometrical
form of this section was constant, so that the spire might be said to be
produced by the revolution of a constant geometrical form around an axis,
the producing plane being constantly increasing, but retaining its specific
form throughout.

284 Introduction to Animal Morphology.

however, the generating figure as it proceeds slips
down out of the original plane along a vertical axis,
and the angle of descent is usually a constant one,
and contributes another element to those necessary to
be known to determine the shell form. This may be
called the helicoidal co-efficient, and as its value for
the last few whorls in multispiral shells may differ
from its value for the earlier whorls, shells may be
diplohelicoid as well as diplospiral.*

The shell consists of several strata of prisms, which
vary in inclinations. It is lined by a smooth layer,
not often nacreous. The mineral matter being biaxial
in its behaviour to light, resembles Arragonite; it
forms 82-99 per cent. of the shell, and gives it its
heavy specific gravity (2.70-2.97) and hardness. The
animal matter is conchiolin, and forms 0.82 - 8. per
cent. In Cyprea, Turbo, &c., the shell is porcellanous,
and in the former the mantle lobes are reflected over
the outside of the shell, on which they secrete an
enamel layer. Some shells contain phosphoric acid,
magnesia, and iron oxide. C. Schmzdt found the
superficial mantle cells to contain a calcic albuminate,
from which the shell substance is doubtless laid down.
The periostracum (absent in Cyprza, &c.) may be
pilose, silky, lamellar, or shaggy.

In coiled shells the smooth and porcellanous apex
often differs in appearance from the succeeding
whorls ; it consists of the original shell of the embryo,

* The following classification includes all shell forms :—1. Spiral, in-
cluding a, turreted; 6, cylindrical; y, short; 6, globular; e, depressed ;
Z, discoidal ; n, convolute ; 6, trochiform ; 1, fusiform ; x, turbinate; X, pau-
cispiral; p, multispiral; v, ear-shaped. 2. Irregularly spiral. 3. Shield-
shape. 4. Boat-shaped. 5. Conical. 6. Multivalve (Chiton). 7. Pseu-
docamerated (Euomphalus, Triton (Simpulum), corrugatum).

Introduction to Animal Morphology. 285

and is called the nucleus. The line of contact of suc-
cessive whorls is the suture. Theaperture at the end
of the last, or body whorl, is surrounded by a variably
shaped margin (ferztreme), which may be circular,
oval, semicircular, angular, spiny, or ridged, according
to the shape of the mantle edge. The pillar along
which the whorls are coiled is called the columella,*
and it may be perforated below by a canal (Umbilicus),
or covered by a thick shelly deposit (Umbilical
callus).t The part of the last whorl overlapping the
columella is the columellar lobe. The apex is turned
backwards (except in Patella), sometimes breaks off
in the adult, producing decollate shells (Subulina
[Rumina] decollata, Urocoptis). The peritreme is
entire in vegetable feeders, or its anterior end, or both
ends, may be prolonged into siphons, which are
formed by long, gutter-shaped processes of the mantle.
In Typhis and Haliotis the shell is pierced by holes,
corresponding to deficiencies in the mantle edge.
The sheli in some cases is rudimental, contained
within the mantle (Limax, Parmophorus), and then it
may be soft, or else glassy, like that of Cymbulia
(Marsenia), or made of calc-spar-like material (Arion).

The operculum may be membranous, horny, or
shelly, and usually is of the form of the generating
plane of the spiral, and keeps itself geometrically con-
stant by rotating on its own axis while revolving

* Rarely the whorls may be disjointed, as in Vermetus where there is
no columella ; or the entire wall of the chamber may be perfect without
confluence with its contiguous neighbour, as in Scalaria where there is
also no columella. In conyolute shells like Cyprzea the peritreme may run
along the whole length.

+ The shape of the shell may vary in the two sexes; the female shell
having the last, or body whorl, wider than the male.

286 Introduction to Animal Morphology.

around the axis of the spire; its lines of growth thus
mark its surface with a spiral which may be mz/t- or
pauci-spiral,* according to the number of whorls,
When the generating figure is a circle, then the oper-
culum grows by regular additions all round, and is
concentric. Other forms are called zmbricate, ungutcu-
late, articulate (when marked with processes). The
operculum has always more conchiolin in its composi-
tion than the shell whose mouth it closes. In Pul-
monates the side of the foot (not an opercular lobe)
secretes a temporary covering, the efzphragm or
claustlium, which is shed after hybernation is over ;
this is solid, consisting of calcium phosphate 86 per
cent., and organic matter 6.5 per cent., but is not a
true operculum. Litiopa, Rissoa, and Cerithidea are
fixed by a byssus formed as a dried mucous secretion,
but not from a special gland.

The body of a Gasteropod is divided into a pro-
soma and a metasoma. ‘The former includes the head
and neck, and to its under surface the foot is often
united in front of the mantle edge. The mantle is
only part of the differentiated body wall of the meta-
soma. The head in Opisthobranchs often bears a
velum in the adult, and this may be lobed at its free
edge (in Tethys forming a funnel) : in Prosobranchs it
bears tentacles, and often eyes, on stalks (ommato-
phores), or sessile. The mouth opens in many Pro-
sobranchs at the end of a proboscis, which is a re-
tractile part of the head, not an extensile portion of

* The number of whorls depends on the curve of the opening, and the
consequent rate of rotation necessary to keep the operculum geometrically
constant in shape. The spiral is usually dexiotrope. In Atiantide there
is a laotrope shell, and also a laotrope operculum. The spiral is usually
only seen on the outer surface (pagina externa).

Introduction to Animal Morphology. 287

the digestive canal. This is protruded by its circular
fibres, and by means of its lacunz becoming distended
with blood; it is retracted by muscles attached not to
its tip alone, as in the proboscis of worms, but to its
whole extent. In some the proboscis is permanently
partly protruded. A similar proboscis often exists in
Heteropoda. The mouth is anterior, may be bordered
by lips,* with a marginal sphincter, and leads into a
buccal cavity, surrounded by a reddish muscular wall
(sometimes with transversely striped fibres), forming
an oval, buccal mass, in which are imbedded two or
four true cartilages, forming an early example of an
endo-skeleton. To these the muscles are attached,
and they support the masticatory organs. These
may be horizontally opposed lateral jaws armed with
flat plates (Heteropoda, Paludina), or sharp teeth
(Dolium), sometimes approximated (Marsenia) or
united above, forming a vertical unpaired jaw on the
upper pharyngeal wall, as in Pulmonata; but more
commonly there is an inferior, unpaired, median organ
(radula, odontophore, or tonguet) on a cartilaginous
support, bearing on its surface teeth arranged in suc-
cessive rows, each consisting of a middle or axial
tooth (rachis teeth, dentes), bordered by one or more
intermediate teeth (uzczzz) on each side, outside
which arelateralteeth. Theradula begins posteriorly
in a sac} in the pharynx below the cesophagus, and is
partially retracted thereinto. When not in use it

* The lips are fringed in some, as in Nubecula tulipa.

t The tongue proper is the eminence on the floor of the mouth sup-
porting the radula, and containing one or two cartilages; it has a central
eavity (cavum pulvinare), and a retractor muscle from the cartilage.

{ The tongue sheath is variable, spirally wound and long in Patella.

288 Introduction to Animal Morphology.

stretches forward, and ends anteriorly by being at-
tached by a globular, toothless portion (Orbis radulz)
to the floor of the pharynx. The teeth are of chitin
or conchiolin, with calcic phosphate, and are true
cuticular structures ; they vary in number from ten
(Pontolimax) to many thousands (Trochide); their
forms and numbers are of taxonomic value.* The
radula is absent in Phyllirhoé, Tethys, &c., as are the
pharyngeal jaws in Aplysia, Tethys, &c.

In Doris there is a prehensile collar of two arched lancet-
like conchiolin plates outside the buccal lips, covered with a
file-like surface of close groups of bifid pointed warts. Pon-
tolimax and Elysia have a prehensile, eversible sac appended
to the tongue; in Pleurobranchus, Lobiger, Lophocercus,
&c., there are two such side pouches in the buccal mass,
attached in front and free behind, having long, outwardly-
curved, slipper-sole-shaped, horny plates.

Into the mouth behind, rarely in front of the radula, open
the ducts of the salivary glands, which are usually two long
(Atlantide, &c.), or short czeca (Carinaria, olis, &c.), some-
times branched (Lobiger, Lophocercus, &c.), sometimes
corkscrew-like (Voluta), or forked (Pleurophyllidia, &c.), very
rarely. In Terebra and Polycera only a single follicle exists.
In Phyllidia two lateral and one azygous. In Pleurobranchus
there are three long, branched ceca reaching to the liver.

* The forms of radula are:—1. Gymnoglossa—toothless, as Acus.
2. Rachiglossata—with only rachis plates, as Volutidae. 3. Hamiglossata—
with rachis plates and one row of lateral teeth (Murex, Buccinidze, Olividze).
4. Toxoglossata—with no rachis teeth, but an intermediate and a lateral
row (Conidze and Pleurotomide). 5. Tznioglossata—with one row of
rachis teeth and three lateral plates on each side (Strombidz, Littorinidz,
Cerithiade, &c.) 6. Ptenoglossata—with no rachis teeth, and manylateral
(Scalaria, Janthina). 7. Rhipidoglossata—with one rachis row, 4—6 in-
termediate and many small lateral rows (Neritidze, Trochidze, Haliotidz).
The paired jaws are also variable in Pulmonates, being absent (Agnatha),
with a sharp tooth (Oxygnatha), striped with a crenated edge (Aulaco-
gnatha), or with marginal rows of teeth (Odontognatha).

Introduction to Animal Morphology. 289

There is one doubtful yellow gland in Conus, four in Jan-
thina, Littorina, and Dolium, while in Murex the glands of
both sides unite to a common duct, and in Umbrella one duct
communicates with a large branched organ. In some the
saliva contains free sulphuric acid, secreted by a special
under lobe, which has a muscular investment.* This part of
the gland is tubular; the rest is acinose.

A large muscle (columellaris) arises from the lower
end of the columella in the body whorl of the shell,
and is inserted into the operculum (hence it can shut
the shell), into the foot, and mantle edge. In Pulmo-
nates, where, as also in Fissurella, it is double and
symmetrical, it sends off slips to the tentacles (ve-
tractores tentacularum) and to the buccal mass (7e-
tractores buccalest). It is crescentic in section in
Capulus, and displaced to the right in Haliotis. Its
size is generally proportional to the capacity of the
shell ; but in Pterotrachea, which has no shell, a cor-
responding muscle exists.

From the upper and hinder wall of the buccal mass passes
the pharynx (lined by a reddish epithelium in some Hetero-
pods), and the short, longitudinally folded and ciliated
cesophagus, which opens sometimes into the middle of the
stomach. It has a long glandular diverticulum in Lopho-
cercus, or a crop, which may be pear-shaped (Elysia), saccular
and unilateral (Tethys, Lymnza, Planorbis, Buccium), or oval
(Dolium, Cyprza, Voluta, &c.) A czcal pouch, filled with

* Dolium Galea, Tritonium nodiferum, hirsutum, Simpulum corrugatum,
Cabestana cutaceum, Semicassis sulcosa, Cassidaria echinophora, Phyllo-
notus trunculus, Rhinacantha brandaris, Aplysia camelus, Pleurobranchsea
Meckelii, Pleurobranchus tuberculatus. In Dolium there is 0.4 per cent.
of free H.Cl, and 2.7 per cent. of H2,SO4.

t In Opisthobranchiata there are upper and lower pairs of protractors,
and one lateral pair of retractors, for the buccal mass, separate from the
columellaris.

U

290 Introduction to Animal Morphology.

gelatinous tissue and fusiform or stellate cells* (the Chia-
jean organ, or the organ of Delle Chiaje), opens into the
cesophagus in some genera.

The stomach is usually simple, thin-walled, pouch-
like, rarely four-angled, with four tooth-like pro-
jections (Pterotrachea), often with cecal pouches
projecting from it towards its cardiac or pyloric ends ;
its epithelium is columnar (Heteropoda), or ciliated in -
tracts, and often elevated into tooth-like processes
(Telescopium), or lobular projections (Mitra). It is
gizzard-like in Aplysia, with cartilaginous pyramids
in its wall, and is lamellated with cartilage plates in
Umbrella. The folds of its lining may be armed with
hard epithelial cutting ridges (Tritonia, Scyllea). In
Philine the large stomach fills half the body cavity,
and has three bony plates in its wall. Scaphander
has similar three-sided plates with rounded angles.
The beginning of the intestine in Aplysia, Tethys,
and Pleurobranchus is dilated, in Aplysia, hidden in
the liver, and is sometimes regarded as a third sto-
mach. ‘The intestine is short, ciliated, simple, and
ends, usually forwards and on the right side, rarely
posteriorly (Vaginulus, Onchidium), in an often wart-
like anus, never lying in the respiratory cavity. Its
wall consists of a muscular stratum, mostly of circular
fibres, but with longitudinal intermixed, not in sepa-
rate layers, often with oval, calcareous concretions
freely scattered in it. The rectum is differentiated in
Prosobranchs, and is often dilated and longitudinally
folded within on the right side of the mantle cavity.
The intestine is shortest in flesh-eaters like Buccinum,
sometimes straight, with no flexure.t In Pulmonates

* Dolium, Murex, Buccinum, Voluta, Conus, Pleurobranchus.
t+ Apneusta, Phlebenterata.

lntroduction to Animal Morphology. 291

and vegetable feeders like limpets it is long and
coiled. A crystal style, like that of bivalves, exists
in Bithynia, Strombus, Trochus, &c., in a pyloric
czecal pouch. The primary flexure of the intestine is
heemal in branchiate, neural in pulmonateforms. The
anus has a sphincter, and in Purpura and Murex
grape-like excretory glands open intoit. Entoconcha,
Rhodope, and some other Apneusta, are aproctous.
The mouth and anus are never on the same medial
plane, but in some Opisthobranchs the latter is medio-
dorsal. A transverse mesentery is only found in the
last-named group. The few- or many-lobed liver
surrounds the intestine in Prosobranchs and Pulmo-
nates, slung by funnel-like threads in Tethys. In
Heteropods it is deep brown, and mixed with the sex-
gland, with one or more ducts, and often with con-
cretions, as among Opisthobranchs.

In some of this latter division the liver has one duct
opening to the right behind the kidney; in others it consists
of a number of gastric ceca (Doris), or two lateral rows of
brown intestinal diverticula, the ends of which may be within
the body (in Pleurophyllidiz and Rhodope scattered over the
whole intestine), or in a side expansion of the body (Elysia),
or in long papille on the dorsal surface (AZolide). These
ceca are widened ducts, and resemble somewhat the branched
canals of Dendroceela. The ducts of these cca may unite
into acommon pouch opening into the intestine, and this
may be single, under (Dotonidz) or over the ovary (Zolide),
or double (Fionidz), or three (Proctonotide). Detached
elliptical (pancreatic ?) follicles exist singly in Aplysia and
Doris, a pair in Doridium.

The heart* is dorsal, rarely median (Doris), usually

* Absent in Entoconcha and Rhodope.
Wz

292 Introduction to Animal Morphology.

in a thin-walled pericardium,* in front and above the
genital gland; it consists of one (usually) or twot
auricles, always ‘directed towards the breathing
organs, and one round or pyriform ventricle, in some
genera pierced {by the intestine.t| There are two,
rarely one, auriculo-ventricular, and two aortic valves.
The ventricular muscle is red,§ and its fibres pass in
all directions, crossing its cavity as trabecule. The
blood may be bluish, and richly corpusculated (Pul-
monata) transparent (Heteropoda), rarely red (Planor-
bis), usually whitish opaline, and containing copper
in some Pulmonates (Harless and Wicke).

The auricle is larger than the ventricle in Hetero-
poda, but is represented only in Abranchiates by
muscular threads surrounding the inlet of the ven-
tricle:

The ventricle gives off an aorta, which soon divides into
cephalic and abdominal branches ; the aorta, springing from
a bulbus in Heteropoda, divides into corporal and visceral
trunks corresponding to these, and the former divides into
caudal and pinnal branches for the meta- and epipodium ;
and the caudal branch in Carinaria divides into two lateral
branches and a medial penial artery in the male. These
vessels in Pulmonates are white, being full of calcareous con-
cretions. Where the rectum pierces the heart there are two
aortz (as well as two auricles), which unite, and then divide
into the two primary branches. Thecephalic aorta in Proso-
branchs and Pulmonates gives off cerebral and pedal arteries.

* To which it is tied by fibrils in Prosobranchs ; it is free in front of
the visceral nucleus in Heteropoda.

t+ Two in Janus, Haliotis, Fissurella, Emarginula, Chiton, &c.

} Chiton, Nerita, Neritina, Turbo, Emarginula, Fissurella, Parmo-
phorus.

§ Especially in Pulmonates ; its fibres are branched and polynuclear in
Heteropoda.

Introduction to Animal Morphology. 293

These vessels end mostly in lacunary spaces, either separate
from (Patella) or communicating with the body cavity. In
the liver, foot, some parts of the mantle, velum, and the intra-
pericardiac wall of Aplysia, capillaries exist, which, in the last
named place, form a rete mirabile connected to the aorta. In
Haliotis the lacune are specialized, and, though wall-less,
look like an intermediate form between lacunz and true capil-
laries. From these lacunze the blood returns to the heart
either by slits in the pericardium (Heteropoda, Pontolimax,
Acteonia, Elysia), or is collected in large spaces near the
auricle (Abranchia), or enters venous trunks that bring it to
the gills. There are no vessels in Rhodope nor Entoconcha,
and none but the aorta in Pontolimax and Phyllirhoé ; there
are no veins in Opisthobranchiata. In Prosobranchs, anterior
and posterior blood-sinuses, beginning by open ends, convey
the blood to the branchial artery and to the kidney, where
there is a close venous plexus, and whence comes a portal
vein to the branchial artery and to the auricle.

There is a water-vascular system commencing by
one* or more large, or several} small openings in the
foot, with a network therein, and opening into the body
cavity. Water taken in by these makes the foot large
and prominent, while it mixes with the blood, dilutes
it, and perhaps aerates it as well. In Dolium there
is an opening into the vascular system beside the
anus.t The respiratory organs may be absent
(Abranchiata, as Rhodope), or the surface, with its
superficial lacune, may be respiratory (Dermobran-
chiata, as Pterotrachea, Pontolimax, Phyllirhoé). In
others the gills are either parallel plates or cylin-

* Pyrula, Strombus, Buccinum.

+ Natica canrena.

{ In Pleurobranchus there is a small opening behind the genital orifice
Jeading to the stem of the branchio-cardial vessel,*between the point at
which it receives a branch of the circum-dorsal sinus and the auricle.

204 Introduction to Animal Morphology.

droidal processes, of which there are never more than
two sets, and often one (the left) is rudimental.

Rarely are they symmetrical, as in Patella, Chiton, &c.,
between the foot and the edge of the mantle (Cyclobranchi-
ata). In Haliotis the two gills are displaced to the one side.
They may be in a special mantle cavity (Aplysia, Bulla, Pro-
sobranchiata), into which a siphonal gutter, never a complete
tube, may lead. The gills are sometimes uncovered when
the mantle is absent (Gymnobranchiata), and then they may
be as a row of dorsal papillz (Cerabranchiata*), each of which
has a separate circular muscular coat, and often a nest of
cnidz at the tip. In Scyllzea, Tethys, Dendronotus, &c., the
dorsal processes are branched, tree-like, in two rows, and with
no liver-czeca (Polybranchiata). Sometimes they form a dor-
sal circlet or wreath round the anus (Pygobranchiata, as in
Doris, sometimes only half surrounding it, crescentic, as
Heptabranchus). In most Heteropods the gills form a clus-
ter of thread-like or leaf-like organs near the point of the nu-
cleus and beside the heart, between the anus and ciliary
organ (Pterotrachea) ; sometimes they lie in a mantle cavity
within a shell (Atlantidz). In this group the gills are simple
enlargements of the body wall covered with a thin dermal
and muscular layer, with no proper branchial vessels (Nucleo-
branchiata), whereas in the others the gills are special organs.
In Elysia, &c., the gills are flat lateral expansions, sometimes
radially folded (Placobranchiata). In some of these Gymno-
branchiate forms the axis of the gill stem has a firm elastic
skeleton, composed of a double row of flattened hollow glo-
bules piled on top of each other. In the shell-bearing Opis-
thobranchs and in Prosobranchs the gills lie under the mantle
lobes, and may be symmetrical on both sides (Dipleuro-
branchiata), or obsolete on one side (Pomatobranchiata). In
the last form the shapes of the gills are very variable, and
there may be one (Umbrella), two, or three branchial veins
to the auricle, with or without special walls. In Prosobranchs

* The lateral appendages of Dorideans (Ancula, Triopa) are not
branchial, but only dermal processes. i

Introduction to Animal Morphology. 295

they may be leaf-like or like a row of threads (Patella), in a
collar or in a pouch (near the cavity) at the dorsal side of the
body whorl, bounded beneath by the body wall, above by the
mantle, and behind by the union of the two: on the floor of
this cavity is the vagina, or the seminal groove; between this
and the anus is the opening of the kidney. The mantle may
be bi-lobed and a gill pair present (Haliotis, Vermetus, Ma-
gilus, Conus, Pleurotoma, &c.) In Strombus, Natica, Mo-
dulus, only a slight band, as long as the right gill, marks the
place of the left gill. This rudiment is broad in Cassis, short
and triangular in Cyprea, absent in Sigaretus, Pteroceras,
Calyptreea, Littorina, Nerita. In Janthina and Valvata the
long gill filaments protrude out of the mantle cavity. The
gill shapes usually vary with the shell shapes. In Turbo the
gill cavity is divided, and each gill lies in a separate space.
This is imperfectly the case in Phasianella.

Passage forms from the branchiate to the pulmo-
nate division occur in Ampullaria, where the wall of
the mantle cavity at certain places shows large
vascular plexuses coexisting with the gills. In the
Neurobranchiata the same arrangement occurs, but
the gills become obsolete. The presence of a siphon
in most of these shows their affinity to Prosobranchs.
In the pulmonates proper this part of the mantle ca-
vity is shut off from the rest as an air-chamber, and
has a muscular wall, a narrow mouth with a circular
sphincter; rarely dermal gill-processes coexist, as in
Onchidium. Ancylus and Acroloxus have no pul-
monary cavity separate from the general mantle
cavity. The aquatic Limnea uses its air chamber as
a float.

The kidney is single, white or yellowish, lamellar
or spongy, often containing uric acid, and consisting
of an internal part opening into the pericardium, and
an external, opening near the anus.

296 Introduction to Animal Morphology.

In Pulmonates it lies between the pulmonary vein and the
heart ; in Prosobranchs between the gills and the heart, in
the floor of the gill cavity close to the beginning of the in-
testine. In Acteon and Phyllirhoé it appears as a long clear
pouch ; a pair of similar pouches are present in the embryo
of Ancylus. Its outer opening in Prosobranchs is often duct-
like, usually has a sphincter, and often radial dilating fibres.
In Heteropods this organ contracts rhythmically, like a heart,
and is supposed to force water into the blood, and to act asa
portal heart, propelling the venous blood which it receives
into the heart. In Carinaria it has a lining of gland-cells, as
in Prosobranchs. In Opisthobranchs there are four types of
kidney :—1st, single, as in Prosobranchs (Phyllirhoé) ;
2nd, with its inner part differentiated as a portal heart, send-
ing blood into the pericardium and gills, the outer part re-
maining glandular (Fiona) ; 3rd, the portal heart developed,
while the renal part is obsolete (Janus); 4th, the outer
glandular part dissevered from the portal heart, which is often
absent (Doris).

Other accessory glands are the purple glands in the wall
of the mantle in Dolabella, and over the whole surface in Aply-
sia, or beneath the intestine in the mesentery ; the depilatory
glands in Aplysia at the bottom of the right swimming
fold; the foot gland in Slugs (K/eeberg) a cluster of unicel-
lular glands near the inner surface of the foot.* In Geoma-
lacus and Arion there isa similar tail gland. In Prosobranchs
transverse leaf-like mucous glands lie often on the roof of the
mantle cavity. In Fiona two large glands, whose function is
unknown, lie in the body cavity beneath the stomach, and
open under the mouth. Pleurobranchus tuberculatus has
surface glands at the base of its dorsal warts.

The nervous system consists of a pharyngeal ring
with a pair of eyes, and a pair of hypo-pharyngeal

* To get rid of the mucus in the dissection of Slugs and Snails, Gulliver
recommends drowning them under an inverted tumbler filled with water
and placed in a basin. For marine Molluscs the best method of pre ara-
tion is to kill the animal with vinegar, then to open its visceral cavity by a
long slit, and immerse for an hour in spirit of wine before dissecting.

Introduction to Animal Morphology. 297

ganglia: the upper are the cerebral ganglia; the lower
the pedal, behind which lie two parietosplanchnic
ganglia; these are all joined by commissures (called
respectively commissure cerebralis, pedalts, visceralis,
cerebro-pedalis, and viscero-pedalis), and the ganglion
cells are often red or yellow. The epi- and hypo-
pharyngeals of each side may approximate, and may
even fuse, while the upper is often divided into two—
an upper, or brain, and a lower, or branchial ganglion,
or the epipharyngeals may unite and form a single-
lobed nerve (Heteropoda). Asa rule, the higher the
animal the greater the degree of coalescence.

Derived from the epipharyngeal, and on its primary
branches in some Opisthobranchs, there may be tentacular
and branchial as well as cerebral ganglia, and from the pedal
ganglia come off branches to the m. columellaris. The brain
ganglion gives off branches to the tentacle, eye, olfactory or-
gan, ear, and penis. These commissural rings derived from
these ganglia in some Opisthobranchs surround the pharynx,
on the anterior of which are two buccal ganglia, united by a
commissure or fused into a bilobed ganglion in Littorina.
Each ganglion consists of unipolar, rarely bipolar, cells
in a neurilemma, which in Pulmonates (Zonites Algira)
has been shown to contain involuntary muscle fibres.

The tentacles are absent in Chiton, two in most
Prosobranchs, or four in others—one pair often spe-
cialized for the support of the eyes (ommatlophores).
In these the nerves end in a ganglion, from which
pass fine filaments, ending in stiff surface bristles
(Trochus); they are covered by ciliated epithelium.
Between the tentacles of Phasianella and in front of
them is a median head lobe. A tentacle may spring
from the foot, as in Buccinum, Harpa, &c., in front or

298 Lntroduction to Animal Morphology.

behind. Tethys and other Opisthobranchs have a
velum moved by separate muscles.

The eyes rarely absent (Chiton, Vermetus, Jan-
thina?), are seated either on the summits (Helix, Te-
rebra), middle (Murex, Conus), or bases (Littorina, &c.)
of ommatophores, or else are sessile (Opisthobranchi-
ata). In Strombus the ommatophores bear flagelli-
form tentacles. The eyes are globular or oval, covered
with a cuticular cornea, a firm lamellar dermal sclero-
tic, lined with a pigmentary choroid layer, which is
continued in front as an iris. The bilaminar retina
consists of crystal cones, fibres, and granules, spread
on a vitreous humour, in front of which is embedded
a lens.

The eyes are most complex in Heteropoda, enclosed in
irregular eye capsules, which freely communicate with the
body cavity. There is also a protractor and a retractor
muscle for the eyeball in some (Pterotrachea), in which also
the retina has a vesicular layer under the rods. In_ some
Prosobranchs the optic nerves are united at their origin. In
Pulmonates a layer of pigment separates the two laminz of
the retina. In Opisthobranchs they are rarely in front of the
bases of the tentacles (Aplysia, Dolabella), and are sometimes
far apart (Haminea). Neither tentacles nor eyes are ever
seated on the proboscis. The optic nerves often form a gan-
glion behind the eyeball.

The sense of smell may be seated in the tentacles of Nu-
dibranchs, which are lamellar, screw-like (in Janus), or
branched. In some there are radiately folded ciliary surfaces,
like the wheel organs of Pneumodermon. In Pulmonates this
sense 1s probably seated in a large lobate grey organ on each
side of the mouth, in contact with the skin, and only covered
by epithelium: within are many nucleated cells, and over
its surface is a shallow groove (organ of Semper). The
ciliary organ of Heteropods is probably sensory, but of un-

Introduction to Animal Morphology. 299

known function, seated in front of the nucleus and under the
anus, not far from its opening; it is strongly ciliated, with
swollen borders and hair-like nerve endings.

The ears are paired, round vesicles, usually behind
the eye, close to the foot ganglion, rarely to the
epipharyngeal (CEolide, Abranchiata, Heteropoda).
They are generally in contact with the nerve centres,
more rarely on the end of a nerve (Heteropoda), or the
vesicle may have a stalk reaching to the foot ganglion
(Neritina, Elysia). There are often many otoliths
(100 in Pleurobranchia, 40 in Doris), which are some-
times pillar-like and arragonitic, sometimes only one
and lamellar, as in Martynia, Tergipes, Rhodope, or
mulberry-like (Phyllirhoé). In Paludina the ear sac is
movable by muscles. The otocyst is ciliated within,
but the cilia disappear in old individuals of some
species. The nerve sometimes enters the sac in two
or three filaments. A tube leads from the surface to
the otocyst in some Pulmonates. A sympathetic sys-
tem exists in the form of a pair of cesophageal gan-
glia joined by a commissure, with other posterior
visceral ganglia in pairs.

Prosobranchs are usually dicecious: Pulmonates
and Opisthobranchs usually hermaphrodite. In Opis-
thobranchs most commonly all sex products are formed
in one set of follicles in a hermaphrodite gland, or
there may be separate male and female follicles in the
one gland, or separate glands in the one animal. The
reproductive organs are usually on the right side, in
the post-abdomen, seldom separate from the liver, and
there is a common duct widening into a uterus, with
which communicates a gland for the secretion of the
nidamental capsule in which the egg is laid. The

300 Introduction to Animal Morphology.

arrangements of the ducts are liable to vary,* and to
them may be appended receptacula seminist and
nervous glands, with clear and opaque cells.~ The
penis is protrusible like a glove-finger, sometimes spi-
rally rolled when not in use. In Pulmonates there is
always a multilobar hermaphrodite gland, often with
cecal processes (Limnza), with an often tortuous her-
maphrodite duct ending in a double tract, the female
product escaping by an oviduct into a dilated uterus,
below which is a pouch-like vreceptaculum seminzs and
an albumen gland; the female organ ends in a va-
gina. The male duct begins as a ciliated groove,

* The varieties are as follows :—A. Genital gland branched, diffused in
the body.

I. Male and female glands separate, with a branched prostate, and
both ducts far forward = Elysia (Placobranchiata) [Pagenstecher
describes Elysia as having a hermaphrodite gland].

II. Male and female glands not separate, but distinguishable ; pros-
tate diffused ; vagina far back = Pontolimax (Abranchiata).

Male and female glands not separate, but distinguishable; pros-
tate unknown, all sex ducts united = Tergipes (Gymnobranchiata).

III. Male and female glands united; prostate simple; follicles sepa-
rate = Rhodope (Abranchiata).

Male and female glands united, prostate simple; follicles her-
maphrodite = Phyllirhoé (Abranchiata).

B. Genital gland consolidated behind the liver; prostate simple.

IV. Male and female ducts at first united, then separate, ovarial,
vaginal and seminal openings close in a cloaca = Fiona, Facelina,
Tethys, Doris, Dendronotus, Pleurobranchus, Pleurobranchza.

V. Male and female ducts united for along extent, with no inner
canal to the penis; genital openings separate, but close together
= Pleurophyllidia, Umbrella.

Male and female ducts united for a long extent, with no inner
canal to the penis; penis far in front of the vagina, with a ciliated
canal = Aplysia, Doridium, Gasteropteron, Philine.

+ Described as the Swammerdamian vesicle.

+ Umbrella has a czecal pouch between the vagina and uterus.

Introduction to Animal Morphology. 301

and has appended to it a multifimbriated prostate.
The end of the vas deferens is muscular, elongated
as a penis often with a long flagel- Fi
lum. The spermatozoa are united by
albuminous matter into masses or sper-
matophores. In Helicide there is ap-
pended to the male organs an eversi-
ble sac, whose papillary mouth is close
to the opening of the mucous glands;
within this the epithelium is calcified
into a sharp quadrangular darvé, vary-
ing in shape in different species. This
is everted, and is used previous to the
mutual impregnation of two indivi- isin ee
duals as an organ of irritation. Its erhormaphrodite gland
use lasts about two hours in a snail, brated prostate ioe
and is followed by a 5-7 minutes’ im- gland rece tye
pregnation. In Limax the two indivi- ee aor
duals twist spirally round each other in coitt. Self-
impregnation has only been noted in Tergipes Ed-
wardsii, and Limneza auricularis, in the whole class.

22
JO:

7°

Heteropods are dicecious: the penis of the males is
a projection of the body wall with no sac, but with a gland-
ular extremity, on the right side; and in Pterotrachea a
mesopodial sucker is added. The lobed testis occupies the
hinder part of the nucleus, and from the opening of the vas
deferens a ciliated groove leads to the testis. In the females
there is an ovary in the same position as the testis (often only
distinguishable from it by its contents), an oviduct, albumen
gland, uterus and vagina. Prosobranchs are mostly dicecious
(except Chiton and Valvata). Some (Cymba, Littorina,
Paludina), like the Pulmonates Plicaphora_ ventricosa,
Clausilia similis, Pupa umbilicata and marginale, Helix ru-
pestris, and some species of Achatinella and Vitrina, are

302 Introduction to Antmal Morphology.

viviparous. Fixed forms, like Vermetus, are impregnated by
the diffusion of spermatozoa in the surrounding water. Chi-
tons alone have symmetrical ducts, and a median ovary lying
on the aorta. They have rarely any appendages except a
penis, often placed on the right side of the head below the
eye. The ovary is embedded in the liver, and has a tortuous
oviduct. Neritina and Paludina have accessory albumen
glands, and its uterine wall secretes myelin. There may be
a prostate in the male (Natica), often a vesicula seminalis.
The penis is absent in Trochidz and Scutibranchs; in others
it is present, and has a claw-like appendix in Dolium and a
penial gland in several other genera.

The eggs are laid usually in chains or in gelatinous
masses, or contained in nidamental capsules. The masses
may be (a) irregular, with the capsules fixed one to the other
(coherentes), dehiscing bya slit or by a round operculige-
rous opening; or with the capsules in a common membrane
attached to foreign bodies (adherentes). These may dehisce
by a slit, or by around opening, and the capsules may be
sessile,* or stalked, cyathiform, oviform, or funnel-shaped ;
otherwise, they may be in (0) regular masses, coherent or ad-
herent, with a central axis of attachment, as in Pyrula, on
which they may be sessile or stalked.

The eggs are sometimes large, with calcareous shells
(Pulmonata) ; the yelk undergoes total cleavage, and the body
is built of the peripheric cells of the blastoderm. ‘The larva
develops a velum and ciliary circlet, and beneath the velum
forms the mouth, intestine, and anus. The foot begins as a
ciliary process below the mouth, and then the mouth and
shell form, then the ear cysts appear, afterwards the tentacles
and eyes; the anus, at first terminal, becomes anterolateral,
and the embryo becomes free-swimming.t ‘The shells of the

* Purpura capsules contain from 30 to 150 eggs, but only one usually
reaches perfection.

+ In a Prosobranch larva there are four stages :—Ist. From the begin-
ning of rotatory movement to the formation of a general ciliary clothing.
2nd. To the formation of a velum, foot, mantle, and shell. 3rd. The de-
velopment of the first spire of the shell, of the heart, and the primary

Introduction to Animal Morphology. 303

Jarvee (nucleus, p. 285) differ considerably in some cases from
those of the adults. In Opisthobranchs the larval shell and
mantle often disappear; in Marsenia the larval shell (Echino-
spira) is lost, and a new one developed.* In the embryos of
some slugs there is a pulsating caudal sac (in Limnza two
sacs), which seems to keep up a circulation ; this is lost in the
adult. In Pulmonates the larva has no conspicuous velum,
but a homologous structure exists, and often persists in
the adult, as in Limnza; on the left side of the neck in this
genus a primitive /-shaped kidney of round cells and con-
nective tissue is developed. They have also a cervical um-
bilical vesicle of stellate and fusiform cells and fibres. Some
are very prolific. Dendronotus Ascanii has been calculated
to lay 25,000 eggs annually, and a S. Atlantic Doris 600,000.

They are mostly marine. A few are fixed ; but most
move by crawling, rarely by swimming (Thetis, CLolis,
Glaucus, &c.) Entoconcha is parasitic; Montacuta
striata lives on Spatangus purpureus; many species
in cold climates hybernate; Helix Hauffenii, and
zoospeum live in caves, and are eyeless.

[he sub-class is divisible into two orders, Branchiata
(Branchiogasteropoda) and Pulmonata.

1. Branchiata—respiration aquatic; larva with a conspi-
cuous velum; intestine with a hzmal flexure or straight.
This includes the following sub-orders :-—

1st. Abranchiata—separate gills none; surface ciliated;
rachiglossate; larva with a shell which is soon lost. The
families are, Pontolimacidz—body flat ; foot broad; tentacles
filiform or none (Rhodope),f or as two, lateral, head crests
(Pontolimax); anus dorsal. 2. Phyllirhoide—free swim-

flexure of the intestine. 4th. The loss of the velum and full development
of the mantle, radula, &c.

* Larve of this class have been described as distinct genera: thus
Macgillivraya is the larva of Dolium, Cheletropis of Murex, &c.

+ This, the lowest Gasteropod, has no eyes, mantle, heart, nor tentacles.
The tentacles are thread-like in Cenia and Dermatobranchia.

304 Introduction to Animal Morphology.

ming; footless ; anus lateral, right ; tail thread-like (Acura),
or flattened (Phyllirhoé).* 3. Elysiidae— placobranchiate ;
jaws none ; anus dorso-lateral; tentacles ear-shaped (Elysia),
or club-shaped (Placobranchus): probably the aberrant gela-
tinous Pterosoma, with no proboscis, foot, gills, radula (?) nor
tentacles, sessile eyes, and lateral, fin-like folds, should form
the type of a family.

Sub-order 2. Opisthobranchiata (A@i/ne Edwards)—gills
exposed or slightly covered, behind the heart ;| hermaphro-
dite ; larva shell-bearing ; mostly carnivorous; gelatinous, full
of sea water, which they discharge rapidly on being caught.
When a shell exists in the adult it is inclosed in a duplica-
ture of the mantle. This includes the following sections :—

§ I. Cerabranchiata (p. 294):—Family 1. Hermxide—
genital ducts separate, rachiglossate ; tentacles none (Alderia),
or two contractile thread-like (Stiliger), or longitudinally
folded (Hermza). 2. AXolidide—rachiglossal; tentacles not
retractile ; foot rudimental (Filurus{); small (Chiorcera), or
large; gills on foot-stalks (Calma), or on sub-pallial expan-
sions (Fiona), or on the back; head tentacles none (Cal-
liopza), or four (£olis).§ 3. Glaucide—gills on lateral’
pedicles ; foot none. 4. Dotonide—tentacles retractile into
a sheath ; gills muricate (Doto), or smooth (Gellina). 5. Proc-
tonotide —ptenoglossal ; liver diffuse ; tentacles simple
(Proctonotus), or pectinate (Janus).

§ II. Cladobranchiata—gill papillz branched or leaf-like.
6. Heroidze—tentacles not retractile; teeth 2. 1. 2, anda
labial veil between the tentacles. 7. Tritoniadz—tentacles
retractile; liver simple (Tritonia).|| 8. Melibzide—teeth
co. 1. 0.34 liver diffused ; tentacles retractile, linear (Meli-
bea), or lamellate; gills tree-like (Dendronotus), on three

* Sometimes infested by a parasitic gymnophthalmatous medusa,
Mnestra.

+ The heart beats in some 50-96 times per 1’’.

+ This genus has a ringed abdomen.

§ £olis (Flabellina) punctata and Dendronotus arborescens emit sounds.
apparently by ejecting water, but this does not disturb the surface of the
water in a basin.

|| T. Hombergi grows to 1-1} feet long. Tf In Scyllzea 24. 1. 24.

Introduction to Animal Morphology. 305

little dorsal eminences (Nerea). 9. Tethyide—tentacles as
last; tongue and radula none.

§ III. Pygobranchiata—dermis spiculigerous. 10. Onchi-
doride—gills retractile, in separate cavities ; semilunar (Hep-
tabranchus), or in a circle (Hexabranchus), or in two lobes
(Villiersia) ; skin stiff, spicular (Onchidoris), or soft. 11. Tri-
opidze—gills retractile in one cavity; teeth 8. 0. 8 (Triopa),
or 2. 1. 2 (Idalia). 12. Doridide—gills retractile (except in
Acanthodoris), teeth numerous, equal; mantle weak (Casella),
none, or well developed, with the body depressed, rounded
above (Doris), or angular (Goniodoris).

§ IV. Pleurobranchiata (Mono-, or Di-pleurobranchiata)—
gills covered by the mantle edge on the right or on both
sides, the first sub-section including the following fami-
lies: — 13. Runcinidze—shell-less, slug-like, marine; a
shelly gizzard. 14. Pleurobranchidea—shell internal, asym-
metrical (Pleurobranchus, &c.), or none (Pleurobranchea,
Neda); genital openings close together; tentacles free.
15. Umbrellidz—shell external, discoidal; apex sub-
central; eyes intertentacular; head in a pre-pedal fissure
(Umbrella), or projecting (Tylodina). 16. Lophocercidze—
shell coiled, unsymmetrical; side lobes of foot undivided
(Lophocercus), or lobed (Lobiger). 17. Aplysiida—tentacles
ear-like; stomach gizzard-like; foot with lateral lobes;
teeth o.0. 0; shell internal, calcareous (Dolabella), or
subcartilaginous (Aplysia)*, or none (Bursatella, Notarchus,
&c.). 18. Philinide—shell subspiral or none (Postero-
branchza); foot borders reflected round it; gizzard with
calcareous plates; teeth 1. 0. I or 2. 1. 2; tentacles none, or
adherent, as in the succeeding four families ; foot rudimental,
with two lateral epipodia (Gastropteron), or large; shell
forming a complete whorl (Philine). 19. Bullidae—frontal
lobe quadrangular; eyes sessile; teeth «.0. & ; shell invo-
lute, making a half whorl (Smaragdinella), or less (Cryp-
tophthalmus), or one or more whorls (Bulla, Atys, &c.)
20. Cylichnidaee—shell perfect, with an elevated spire in
Tornatina; teeth 6. o. 6; head disc with lateral lobes.

* The purple secretion of Aplysia contains iodine. The secretion of
its depilatory glands sometimes urticates the hand.
x

306 Introduction to Animal Morphology.

21. Aplustride—shell perfect ; lateral processes of head lobes
ear-like ; teeth 13.013. 22. Actazonidze—shell perfect,
operculigerous, involute: teeth .0. o or 12. 0. 12. The
shell-less Dipleurobranchs include (22) the toothless Phylli-
diidz, and (23) the jaw- and tongue-bearing Pleurophyllididz,
with lateral anus.

Sub-order 3. Heteropoda(Cuvzer)—dicecious, marine, trans-
lucent; foot compressed, fin-like; shell thin or none; viscera in
a nucleus; gills pectinate or filamentary ; propodium vertical,
fin-like; mesopodium suctorial in the males of some, the
sucker having special circular and radiating fibres.* Family 1.
Pterotracheide—body long; nucleus small, often stalked,
naked (Pterotrachea, Firoloidea),{ or with a shell (Carinaria
and Cardiapoda); gills tufted, pre-nuclear ; tentacles none
(Pterobranchea), or present. 2. Atlantidz, shell discoidal,
spiral, operculigerous, into which the animal is retractile.t

Sub-order 4. Prosobranchiata (Milne Edwards),§ includ-
ing shelled Gasteropoda, which have the gills in front of the
heart, and a veliferous larva. The visceral cavity is large,
and the body nearly symmetrical. The following sections
are included :—

§ I. Polyplacophora (Blainville)—chitons depressed, ovate,
with a broad foot and a shell of eight valves. The mantle border
is smooth or with excrescences; moncecious (J@:ddendorf) ;
cyclobranchiate ; teeth 4-6. 2. 1.2, 4-6 on a long radula;
intestine straight or coiled; anus posterior, median ; tentacles
brain and eyes none; heart medio-posterior, elongated ; sex
organs paired, with two openings. The shell in Cryptoplax,
&c., is imbedded in the mantle. The anterior and posterior
valves are semicircular ; the six intermediate have each three

* And between these are long radial glands.

+ The larva of this genus has two gizzard-plates in the stomach. The
peculiarities of Heteropods come out late in Embryogenesis.

${ Bellerophon, Eccyliomphalus, and Cyrtolithes are fossils allied
thereto.

§ The number of species in each group of Gasteropoda is as fol-
lows :—Opisthobranchia, 825 living, 335 fossil. Heteropoda, 54 living,
1g1 fossil. Abranchiata, 25 living, none known fossil. Prosobranchiata,
8600 living, 5670 fossil, Pulmonata, 5800 living, 530 fossil—in all, 21,980.

Introduction to Animal Morphology. 307

facets, a posterior flat pyramid with an umbo, and a pair of
lateral areas; each of these consists of a /egmentum under the
epidermis ; free between the mantle edge, and an articulamen-
Zum, deeper layer ; there are two pair of joints, articult antict and
postic?, along the edge of the lateral areas. ‘There is but one
family.

§ II. Cyclobranchiata( Docoglossa)—Limpets, with coni-
cal, inoperculate shells ; tentacles two, with eyes at their bases ;
foot large and flat; radula with no middle plate, and ridged
lateral and intermediate plates. This includes the family
Pateilide, with a long radula; teeth z. 4.2; muscular im-
pression on shell crescentic. The gills surround the head
(Patella), or may be interrupted there (Nacella). Lepetidz
have no eyes nor gills. Tecturide have a free gill on the
right side of the neck.

§ III. Aspidobranchiata — herbivorous, rhipidoglossal ;
shell conical, spiral, flat or cap-like; foot large ; gills double;
penis none. This includes—1. Fissurellida—foot large ;
shells flat (Parmophorus) or limpet-like, with an apical (Fis-
surella) or pre-apical (Rimula) opening, or an anterior mar-
ginal fissure (Emarginula).* 2. Haliotida—shells ear-like,
nacreous within, left border with a row of holes along the
suture; an anal siphon. 3. Pleurotomaridz—conical, fossil
shells, with a notched mouth, represented now by Anatomus
and Stomatia. 4. Trochidz—scutibranchiate; foot lobate
and filamented along the side; shell nacreous within ; oper-
culum smooth and calcareous in Phasianella ; orbicular, horny
in Turbo, with a solid convex, calcareous, inner pagina,
and a turbinate ventricose shell. Imperator has an oblong
or ovate operculum, also calcareous within ; in Adeorbis it is
calcareous, multispiral. Rotella has a flat, polished shell;
Delphinula a horny concentric operculum and a turbinated
shell; Trochus a membranous operculum and a conical shell
with a flat base. Gena is ear-shaped, inoperculate, and Bro-
deripia is limpet-like. 5. Neritidz—scutibranchiate ; foot
oblong, triangular, not fringed ; shell thick; peritreme cres-
centic, spire not prominent; operculum calcareous, pauci-
spiral, often articulate. Nerita is marine; Neritina freshwater ;

* This genus has a rudimental operculigerous lobe.
. xX 2

308 Introduction to Animal Morphology.

Clithon is spiny; Navicella is patelloid, with a rudimental
operculum.

§ IV. Ctenobranchiata—gills two, pectinate, in the mantle
cavity; penis present; never rhipidoglossal. It is divided
into two sub-sections, according as the peritreme is entire
(Holostomata), or elongated into a canal corresponding to
the siphon of the mantle (Siphonostomata).

Sub-section 1. Siphonostomata consists of three series :—
I—Tenioglossata, including the following families:—1. Strom-
bidz—head with an annulated rostrum; eye-stalks thick,
giving rise to the tentacles when they exist; outer lip of
the shell wing-like; foot narrow, divided; outer edge of
mantle entire (Strombus), or cleft (Pteroceras); spire long
in Rostellaria. ‘Terebellum has no tentacles, and unequal
eye-stalks. 2. Aporrhaide—foot trigonal; eye-stalks small
at the base of the long tentacles ; outer lip of canal expanded;
spire long (Aporrhais), or short (Struthiolaria). 3. Pedicula-
riadee—irregular shells, parasitic on Mediterranean corals; eyes
sessile at outer side ofthe base oftentacles. 4. Doliide—siphons
recurved ; foot small, with lateral lobes ; shell ventricose ; eyes
on short stalks ; operculum none (Cassidaria, Dolium), or small
(Cassis) ; shell usually thick or thin, spirally ribbed (Dolium),
in Ficula pear-shaped, with a long canal. 5. Tritoniidze—
spiral elongated, with continuous (Ranella), or discontinuous
(Tritonium), varices, and long siphonal canal; foot small ;
shell sometimes distorted (Persona). 6. Cyprzidz—shells
porcellanous, smooth-ribbed (Trivia), or tubercled (Pustula-
ria), involute ; tentacles long, subulate ; foot broad; opercu-
lum none; inner lip of shell corrugated, rarely smooth
(Ovulum, Volva).

Series II. Toxiglossa—radula 1.0.1; siphon with a poi-
son gland opening through the hollow teeth. Families 7 :—
Conide—foot with one conspicuous pore; shell inversely
conical, with a long narrow aperture, with simple lips, and
nearly flat (Conus), rarely produced spire (Dibaphus) ; pro-
boscis and siphon short ; operculum small, unguiculate. 8. Te-
rebride—shell long, multispiral, acute; mouth and canal
small; siphon long; operculum ovate, pointed, with apical
nucleus. 9. Pleurotomidse—shell fusiform or conical, its

Introduction to Animal Morphology. 309

outer border with (rarely without, Bela) an anterior notch ;
operculum lamellose or none (Mangilia). 10. Cancellariidae—
spiral, ovate shells; proboscis none ; tentacles far apart, with
basal eyes; operculum none ; foot small, triangular.

Series III. Hamiglossata—(1-1-1). Families, 11. Muri-
cidze—shell with foliaceous or spiny varices, a straight canal ;
eyes at the bases of the tentacles ; foot broad, single in front,
with leaf-like operculum. Murex has at least three rows of
varices; Typhis has hollow spines; Trophon a crown of la-
mellose varices ; Fusus is spindle-shaped, with an oval mouth ;
Pyrula pear-shaped, with a wide opening ; Columbella thick,
with a narrow mouth; Fasciolaria has fusiform shells, whose
outer lip is striped transversely. 12. Buccinide—anterior
canal short; foot large; border of the outer lip smooth
(Buccinum), or toothed (Nassa), often cancellated (Phos), or
smooth, oval (Pusionella); canal sometimes reduced to a
notch (Purpura). In Concholepas the mouth is very wide,
and the spire almost none; Monoceros has a strong tooth on
its outer lip ; Magilus, living in coral, has, when young, a re-
gular spiral shell, but becomes irregular as age advances.
13. Mitride—shell smooth, with a pointed spire, small mouth,
and sharp columellar folds ; proboscis long ; operculum none
or small. 14. Olivide—foot large, trigonal, divided into
fore and hind lobes; eyes medial, stalked; proboscis short ;
siphon long; shell cylindrical, smooth (Oliva, &c.), or lon-
gitudinally ribbed (Harpa). 15. Volutide—rachiglossal ; shell
notched anteriorly at peritreme; columella sharply folded ;
siphon long ; proboscis short ; operculum none; shell oval.

Sub-section 2. Holostomata — herbivorous, with no
siphon, and an entire peritreme. This includes the fol-
lowing series ;—I. Ptenoglossa (oo .0 0 ), including, 16. Sca-
lariide—foot small; eyes near the base of the tentacles ;
operculum corneous, paucispiral; shell aciculate, white, lon-
gitudinally ribbed (Scalaria). 17. Solariidaee—shell trochiform,
last whorl angular, widely umbilicated ; mouth four-angled ;
eyes at the base of the lower groove-like hollow tentacles.
18. Ianthinide—shell thin, snail-like, bluish, with thin lips;
eyes none; tentacles four; pelagic inoperculate forms, se-
creting a purple fluid; eggs cohering into a “raft.”

310 Lntroduction to Antmal Morphology.

Series II. Tanioglossata (3.1.3), including, 19. Ceri-
thiidee—foot small, round ; eye near the base of the tentacle ;
shell multispiral, slender, without or with periostracum, with
small mouth, canalated fore and aft; operculum horny, spiral.
20. Melaniade—freshwater; shell often corroded, slender,
with a thick, dark periostracum; outer lip of peritreme
sharp; tentacles arch-shaped; proboscis not retractile.
21. Pyramidellidz—shell oval, or tapering, nucleus dexio-
trope; tentacles broad, ear-shaped; proboscis retractile ;
operculum horny (Stylifer, Chemnitzia, &c.) 22. Turritel-
lidae—shell slender, tapering, multispiral ; apex often broken ;
peritreme round, simple; gill single; foot short; opercu-
lum horny; Czcum has a tubular, non-spiral shell, with a
multispiral operculum. 23. Vermetide—sessile; shell irre-
gularly spiral, tubular, frequently fissured (Siliquaria), one,
left, pectinate gill. 24. Xenophorida—shell lamellose, trochi-
form, with many agglutinated foreign bodies in it; proboscis
long; eyes at the base of the long thin tentacles (Phorus).
25. Naticidsz—shell globular, paucispiral, smooth, short-
spired; mouth semilunar; columella swollen; proboscis.
long; eyes may be absent. 26. Entoconchide, including
a curious parasite existing as a shell-less pouch attached to
the calcareous ring of Synapta, only containing sexual organs ;

from these develop a naticoid shell, whose further history is.

unknown. 27. Marsenidz—shell thin, ear-shaped, horny,
inoperculate ; hidden in the foot; the larval shell is com-
pletely shed. 28. Acmzeadze—shell and animal limpet-like ;
radula long; operculum none; foot large. 29. Capulide—
foot as last; shell patelliform with a trace of a spire, and an
internal, lamellar, horseshoe-shaped (Capulus, Calyptraea), or
funnel-shaped (Crucibulum), or horizontal, muscular lamella
(Crepidula) ; Hipponyx forms a shelly lamina under the foot.
30. Littorinide—foot thick; eyes at base of tentacles; oper-
culum paucispiral, horny; mouth entire round; shell oval;
siphon rudimental. 31. Paludinide—freshwater ;_ shell
oval, with olive-green periostracum, and entire mouth ; oper-
culum eccentric, lamellose. 32. Valvatide—freshwater ; glo-
bular or discoidal, with a tentacle from the mantle; gills
projecting out of the mantle cavity; foot small. 33. Ampul-

Introduction to Animal Morphology. 311

lariadee—freshwater ; foot large; eyes on short stalks; pul-
monary cavity coexisting with the gills.

§ V. Neurobranchiata—terrestrial, dicecious, operculige-
rous, breathing air by a vascular net-work on the roof of the
mantle cavity ; tentacles two, non-retractile, behind or at the
base of which are the eyes; penis anterior. This includes :—
1. Cyclostomide—shell conical, tznioglossate, often de-
pressed ; foot long; mouth round or oval, entire or witha
double margin; operculum paucispiral or multispiral, horny
or calcareous. 2. Stoastomidze—shell conical; columella
flattened ; eyes at the base of the tentacles; radula rhipido-
glossal; operculum not spiral, but semicircular, triangular, or
none. 3. Aciculide—foot small; lips parallel; peritreme
thickened (Acicula), or canaliculated below (Geomelania).

Order 2. Pulmonata (Cuver)—air breathing, symmetrical,
terrestrial, herbivorous, hermaphrodite Gasteropods, naked,
or shell-bearing, with no operculum, except in Amphibola.
The lung is behind the heart, and the larva has no con-
spicuous velum. The shell is deposited not outside, but as
calcareous granules, in the mantle substance. They are very
abundant in warm climates. They are divisible into three
sub-orders :-—

1. Acera—with no tentacles, including the Australian
family Amphibolide, living in brackish water; with the penis
under the right eye; shell umbilicate, globular.

Sub-order 2. Stylommatophora—eyes on the ends of
stalks or processes of the body wall (hinder tentacles), which
may be contractile and coexisting with two other simple ten-
tacles, as in Veronicella, or with no other tentacles, as in
Onchidium ; or the tentacles may be two; retractile, as in
Janellidz ; or four retractile, as in the following families :—
Limacide—shell hidden in the mantle (which is fused with
the back); jaws strong, crescentic. Arion has a shell of
several pieces and a caudal gland, as in Geomalacus, while
Limax, the common slug, has no tail gland. Parmacella has
a subspiral shell. 2. Testacellida—carnivorous, small; jaws
none; the shell may include the whole body (Glandina), and
may have its last axis oblique (Streptaxis) ; it is rarely conical,
multispiral (Cylindrella), or small, as in Testacella and Dau-

312 Introduction to Animal Morphology.

debarda. 3. Helicide—herbivorous; shell external, spiral ;
body separated from the foot ; jaws strong, crescentic. Helix,
the snail, has a complete peritreme with separate borders,
modified by the projection of the whorl before the last; its
1800 species form about fourteen sub-genera. Bulimus has
oval shells, with unequal margins to the peritreme, and in-
cludes 1200 species. Achatina is Bulimoid, non-umbilicated,
with an open posterior end and a sharp edge. Vitrina has a
glass-like shell with a simple mouth. Nanina is snail-like,
polished, umbilicated, depressed, with a bilobed mantle.
Zonites is umbilicated, multispiral, with a tail gland. Acha-
tinella is often dexiotrope, like the slender cylindrical
Clausilia. Pupa is ovate or cylindrical, with a toothed or
plane peritreme, and with tentacles, small, anterior, or none
(Vertigo).

Sub-order 3. Basommatophora—eyes posterior, or internal
to the two tentacles, sessile, including :—1. Limneidze—
shell horny, translucent, with a large body whorl, a sharp lip,
often retroverted (Anphipeplea), rarely dexiotrope (Physa),
discoidal (Planorbis), or patelliform (Ancylus), or neritiniform,
with a wide mouth (Latia). 2. Auriculide—shell thick, with
a thick periostracum; inner lip folded; jaws strong; the
spine may be much elevated (Carychium), the outer lip sharp
or thick. Allied to this is the patelliform genus Siphonaria,
which has a gill in the pulmonary cavity, and is thus a passage
form. Pulmonates have been arranged according to their
jaws, by JZérch, into six groups:—1. Oxygnatha, or those
with a sharp tooth on the jaw, as Limacidz and Vitrinide.
2. Agnatha—jawless, as Testacellidze and Onchidiidz. 3. Aula-
cognatha—with striped jaws, crenated at the edge, as Pupa,
Clausilia. 4. Odontognatha—jaws with marginal rows of
teeth, as Arionide, Helicide (except Pupa, &c.) 5. Gonio-
gnatha—with superficially striated jaws, as Orthalicide,
Veronicellide, Janellide, Succineide. 6. Polygnatha—with
more than two jaws, as Limnzide.

Introduction to Animal Morphology. 313

CHAP TE eee 2 V FEF.
CLASS 3.—CEPHALOPODA.

MARINE, carnivorous, dicecious, symmetrical molluscs,
the highest of the sub-kingdom; with partially cleft
ova; a distinct head surrounded by the modified foot ;
respiration branchial; sense-organs well developed ;
the bodies are antero-posteriorly shortened and verti-
cally elongated ; they creep with the head downwards,
and swim laterally with their upper side forwards.
The integument is smooth, rarely papillose, covered
by a porous cuticle of united cylinder (Nautilus) or
pavement cells, on a basis of fibrillar tissue, beneath
which are one or two layers* of nucleated pigment
cells with contractile processes (chromatophores).
The pigment is rarely in the surface epithelium.t
Under these is often a layer of lamellar, highly re-
fracting corpuscles (/fiztterchen}) producing by inter-
ference a play of colours.

Beneath these layers, loose connective tissue covers
a muscular and connective substratum, containing
usually a network of capillary blood-vessels. The in-
tegument of the sides of the body is differentiated into
a mantle which incloses a cavity whose opening is
directed downwards (backwards in progression), and
which lies on the posterior (or what is generally con-

* When of two layers they are of different colours.

+ Asin the tentacles and about the eyes of Nautilus ; some of those
cells are ciliated.

{ The chameleon-like change of colour, so striking in Cephalopods, is
-due both to the changes in shape and size of the chromatophores and to
these flitterchen,

314 Introduction to Animal Morphology.

sidered as the ventral) surface. The inferior free
mantle edge may completely surround the head as a.
collar (Sepia), or may unite with the body integument
antero-laterally, so that the mantle becomes only a
latero-posterior duplicature of skin dorsally (pos-
teriorly). The lateral integument is often expanded
into flat lobes or fins, which may be rounded (Sepiola)
or angular (Ommastrephes), terminal or sub-terminal.

The mantle may secrete no shell (Octopus), or may
have imbedded in it a pair of thin conchiolin plates
anteriorly (Cirrhoteuthis). In Loligo there is an an-
terior shell (gZadzws) of conchiolin, inclosed in the
mantle, consisting of a central rachis, without (Sepiola)
or with two thin lateral wings,* varying in shape.
This is formed within a “ pen-sac,’’ which is a space
formed in the embryo by an upgrowth of a ring-like
wall of the mantle, the margins of which close to-
gether by later growth. In Octopus the fossa is.
developed, but its margins never close in. In Sepia
there is posteriorly, and united to the horny “ pen,” a
lamellated, soft, calcareous shell, forming the well- »
known cuttlefish bone (used for tooth powder), each
of whose lamellez is separated by an interspace filled
by animal matter.

The extinct Belosepia had a similar shell, but the lamellz
were farther apart, separated by hollow intervals. In the ex-
tinct Belemnites the interior (phragmocone) is composed of
lamellz, separated by chambers which communicate with
each other by a canal (s¢phuncle), outside which a part of the
original lamellose sepiiform shell remains as a coating
(pro-ostracum), covered with a horny sheath, and like the shell
of Sepia, often ending in a beak or rostrum. The belemnitic

* These wings are broader in the female than in the male.

Introduction to Animal Morphology. 315

internal shell is usually straight, but in the miocene Spiruli-
rostra is coiled, conducting us to the form of shell in the
existing Spirula, where the chambered, coiled, purely nacreous
internal shell represents the phragmocone of a belemnite.
We know as yet of no passage forms linking these to the ex-
ternal shells of the same pattern, like Nautilus, but such may
have existed among the numerous fossil forms (Crioceras,
&c.) of whose soft parts we know nothing. Many consider
these two kinds of shells as utterly diverse in morphological
nature.

There are two types of external shells among
Cephalopods—tst, the camerated form, in which the
animal inhabits a large terminal compartment, behind
which are several air-holding* chambers, divided by
transverse septa, but communicating by a tubular
prolongation of the body cavity (siphuncle). Some
fossil forms are straight (Orthoceras), curved, hook-
like (Hamites), openly coiled (Crioceras), or involute
(Goniatites, &c.), sometimes helicoid or turreted, and
the septa dividing the chambers may be evenly con-
cave towards the peritreme, or complexly lobed at
their margin of attachment (Ammonites, &c.) The
siphon may be columellar, median, or lateral. The
shell consists of an outer porcellanous, an inner
nacreous, and sometimes an imperfect middle, gra-
nular, coloured lamina. The second form of shell is
unicameral, smooth, as in the female Argonauta,
secreted by the lobed dorsal arms, and forming a
parabolic spiral of 1th whorls. It is to be regarded
as a pedal shell, and its homologies are rather with
an operculum than with a shell proper.

An internal skeleton exists in all as a cartilaginous

* This air contains more nitrogen than ordinary air, and no carbonic
acid.

316 Introduction to Antmal Morphology.

peripharyngeal crescent or ring, analogous, but not
homologous to a cranium. In Nautilus it is horse-
shoe-shaped, and its cornua end above and below in
pointed processes. In Dibranchs it is median, peri-
cesophageal,* with two lateral processes, either flat
expansions forming roofs for the orbits, or else forming
perfect orbital cavities. In Sepia there is also a
pointed median cartilage outside the basal part of the
arms, and also a semilunar piece in the anterior dorsal
region of the mantle. In Octopus the latter is repre-
sented by two lateral pieces, with no medial part, and
in Loligo it is absent. There is often a neck cartilage,
largest in Loligo, absent in Sepiola; and at the base
of the funnel are two hinge cartilages (absent in
Octopoda). Along the sides of the lateral fins are
two cartilages, long and sword-like in Sepia. The
cartilage cells in Sepia send numerous long fine pro-
cesses through the intercellular substance, giving it a
finely striped appearance.

On account of the antero-posterior shortening of
the body, the foot approximates to, and surrounds the
mouth, and has its margin divided either into a cluster
of many tentacles (Nautilus), or into 8—1o long sucker-
bearing arms. Two epipodial lamelle spring from
the posterior side near the head, and, in most, unite to
form a tube (/wnxnel) directed downwards and back-
wards, with its upper end towards the mantle cavity.
The mantle margin overlies it so closely in life that
this funnel is the only communication of the mantle
cavity with the outerworld. Thetentacles in Nautilus
are triangular in section, and arranged in two circlets,

* Forming a hollow ring with the nervous system in its transverse
cavity.

Introduction to Animal Morphology. 317

the outer wreath being incomplete over the funnel,
and consisting of nineteen at each side, the two dorsal
of which unite to form a cucullus, which, when the
animal is retracted, acts asanoperculum. The inner,
smaller circlet consists of twelve tentacles on each
side. Each of these tentacles has a basal sheath, and
in the male the sheaths of the four ventral inner ten-
tacles unite to form a spadix.* The female Nautilus
has ninety-six tentacles.| The genus has a double
musculus columellaris from the shell to the head car-
tilage, not continued into the tentacles.

The other Cephalopods have eight arms in a
circlet round the head, formed of the modified margin
of the foot, and two longer tentacular arms arising
within these. These arms may be united by membrane
to their tip (Cirrhoteuthis), or only at their bases ; they
are numbered from their dorsal side as first, second,
third, and fourth pair.

Each arm consists of a central canal, containing an artery,
avein, and a nerve. Circular and longitudinal fibres sur-
round this, and a dermal layer over all. Its oral surface is
covered with rows of cup-like suckers, each of which has a
smooth or toothed, hard epidermal ring round its mouth.
Radial and papilla-forming vertical piston-fibres, by retract-
ing the centre, help it to act as a sucker or adhesive organ;
sometimes (Onychoteuthis) some suckers are modified into
hooks. The m. columellaris in these is represented by a
muscle extending from the head-cartilage. Thereare also in
all Cephalopods—1, m. collaris, a broad band around the
neck ; 2, depressor infundibult ; and 3, adductor infundrbult, to
alter the position of the funnel; 4, m. Jaferalis (under the
ganglion stellatum in ordinary cuttlefishes), passing from the

* Somewhat similar to the hectocotylized arm of a Dibranch.
f 38 external, 24 internal, 14-15 pair of labial ten-tacles, and 2 pair
of tentacles behind the eye. The male has 60.

318 Introduction to Animal Morphology.

head-cartilage to the side of the mantle. The fin along the
side is moved by muscles attached to its cartilaginous support.

The mouth is surrounded by an annular lip, at-
tached to the base of the arms by a buccal membrane.
Within this is a parrot-like beak of two dark brown,
vertical, conchiolin jaws, of which the under overlaps
the upper. Internal to these is a soft ciliated (taste ?)
organ, in front of the vertical internal tongue, on
which is stretched the broad radula, armed with long
hollow lateral hooks, with a dental formula in each
row of 3-1-3, or (Eledone and Octopus) 4-1-4, or
(Nautilus) 4-5-4. Into the mouth open one or two
(Onychoteuthis, Eledone, Octopus) pair of large,
smooth, or lobed salivary glands. The posterior pair
is absent in Sepia, Loligo, &c.; short and small in
Octopus and Eledone. In Nautilus there is a lateral
(salivary ?) glandular mass on each side of the mantle.

The cesophagus is narrow and long, dilating into
a fusiform crop in Nautilus. Argonauta has a long
oval crop, but in Octopodide it is much shorter. In
Nautilus the cesophagus passes through a transverse
intermetameric septum, stretching between the head
segment (prosoma) and the visceral bag (metasoma).
The stomach is saccular, thick-walled (Octopus and
Nautilus*), ciliated within; the cardiac and pyloric
openings are close together, and the lowest part of
the stomach is saccular. The intestine begins with
a dilatation which in Nautilus is lamellar, in Loligo
is spiral, in Rossia is curved and round; into this
open the two bile ducts. The longitudinally folded
intestine is moderately straight, and ends in the

* In this animal having tendinous plates and thick cuticle, like a bird’s

gizzard.

Introduction to Animal Morphology. 319

middle line of the mantle cavity, usually communi-
cating with the funnel in an anus either round (Nauti-
lus), or with one, two, three, or (in Sepia) four
triangular anal valves; largest in Sepioteuthis ;
thread-like in Loligopsis; the flexure of the intestine
is neural.

The liver is reddish yellow, witn four loose lobes
in Nautilus; two separate (Sepia), or transversely
united (Rossia) lobes; firm and compact in others.
Yellow, firm lobules (pancreatic lobes), which commu-
nicate with the two bile ducts, are easily distinguished
in most forms.

All but Nautilus have an ink bag, a long sac with
a lamellar iridescent lining, and a slender duct open-
ing near or into the anus (Decapoda). In Octopus it
is imbedded in the liver; in Sepiola it becomes
periodically enlarged, and divided into one central
and two lateral parts, which show regular contrac-
tions. The secretion of this bag is sefza, composed of
melanin, magnesic and calcic carbonates, and mucus.
These animals hide themselves, when pursued, by
darkening the water with this fluid. This sac is de-
veloped as a diverticulum from the chamber of the
anal tubercle, and this is primarily a segmentation
from the alimentary canal. In Cephalopods the sys-
temic heart lies at the floor of the visceral cavity, and
consists of a round or transversely oval ventricle, with
striped muscles in its walls. It has a valve at each of
its auricular and arterial openings. There are two
auricles (four in Nautilus, Fig. 31, B). There are two
aorte, arising one at each end of the heart (Sepia, Lo-
ligo, Fig. 31, C), or close together (Octopoda, Fig 31, D).
The cephalic aorta is the largest, and gives off pallial,

320 Introduction to Animal Morphology.

intestinal, and infundibular branches, and in the head
ophthalmic and tentacular vessels, which may be
united by an annular vessel round the mouth. The
visceral aorta supplies the liver and genital organs,
and in Ommastrephes gives off a pair of branches to
the fins (pinnal), which are dilated into accessory cir-
culatory organs. The arteries end in capillaries and
lamine which open into the veins, which vary in
almost every genus. The brachial veins form a cir-
cular sinus at the base of the arms, and send a cephalic
vein upwards, which receives pallial and visceral
veins, and branches from the large lacune; it then
divides into two (Dibranchiata) or four (Tetrabran-
chiata) branches, which go to the two or four gills.
In Dibranchs these are dilated at the bases of the
gills, and surrounded by muscular fibres, forming a
pair of branchial hearts. The gills are pyramidal,
non-ciliated, in the mantle cavity, and consist of
united lamelle or of complexly folded dermis, bathed
by sea-water, which passes in and out of the mantle
chamber in swimming.

The branchial veins from these dilate, and form the two or
four auricles of the heart. The blood is colourless, and con-
tains copper. On the branches of the cephalic vein, before
they form the branchial hearts, there are spongy renal ap-
pendages containing czca and often yellow or violet concre-
tions projecting into the aquiferous lateral sacs of the mantle
cavity, and communicating with the pericardium. These
may be the homologues of the organs of Sojanus or of the
gasteropod kidney, the spongy venous processes resembling
the spongy glandular part of that organ, or they may be
kidneys of another type. Over the surface are certain aqui-
ferous pores, by which water enters the lacune and mixes
with the blood ; these may be cephalic (or a pair on the back
of the head), as in Philonexis, Tremoctopus, Argonauta, or

Introduction to Animal Morphology. 220

buccal, four (Histioteuthis, Ommastrephes), or six (Sepia,
Loligo), or anal (one pair at the base of the funnel), as in
Philonexis, Ommastrephes, and Onychoteuthis; sometimes
there are brachial pores at the base of the arms. Water
also enters the perivisceral cavity, which here, as in other
molluscs, acts as a large circulatory lacuna.

The cerebral, pedal, and visceral pairs of ganglia
are close together, united by short commissures, or
even coalescent. The pharyngeal ring is protected
partly by the cartilage, and its investment is com-
pleted by a membranous sheath.*

The pedal ganglia in Nautilus give off branches which
form a tentacular ganglion. In Dibranchs the corresponding
nerves often unite into a common trunk. On each side of
the mantle cavity on the musculus laterals is a large ganglion
stellatum connected with the visceral ganglion by commissures,
and distributing branches to the mantle. From the cerebral
ganglion arises a commissural band, which forms above the
cesophagus an upper buccal ganglion, and ventrally below an
inferior buccal, to which the sympathetic nerves are attached,
two long stems running along the cesophagus, and forming
a stomach ganglion, or pair of ganglia, giving branches to
the other viscera. ‘Two stems attached to the hypopharyngeal
ganglion pass along the large venous trunks, and unite in a
pair of branchial ganglia at the base of the gills, joined by a
commissure.

The sense of touch is seated chiefly in the tentacles,
taste in the before described pre-lingual papilla (or in
similar organs in Nautilus). The organ of smell may
be a short, trigonal, ciliated, hollow process, like the
sheath of a tentacle (Nautilus) placed below the eye,

* This sheath is more complete in Dibranchs, in which the nerves often
pierce through the cartilage to their destination. The intravaginal space
is not filled by the nerve centres, but contains a fluid ora glandular (?)
mass.

¥

222 Introduction to Animal Morphology.

ora pair of ciliated grooves, one behind each eye,
supplied by a nerve arising along with the optic (this
organ is smaller in Octopods than in Decapods).
Another peculiar sense-organ lies on the inner wall
of the funnel, as a flat, whitish eminence whose surface
consists of cells containing strongly refracting, rod-
like bodies. The organ of hearing is a round sac,
in Tetrabranchs lying on, in Dibranchs inclosed in,
the head cartilage, and containing one or many
(Nautilus) flat or rounded otoliths; its nerve springs
from the pedal ganglion. There is a membranous
sac or labyrinth within the cartilage, separated from
it in Octopods, but joined to it by processes and sulci,
which renders it complex in Decapods. ‘The nerves
end in fine rods, or under a thick epithelial ‘ auditory”’
plate. A ciliated canal traverses the cartilage,
whereby the dermal sac has been involuted for the
formation of the otocyst. The optic nerve arises from
the brain, and forms a large ganglion directly behind
the large eye-ball, whose orbit of cartilage is conti-
nuous into the sclerotic. Below and behind the eye-
ball is a peculiar “ white body,’* probably an aborted
nerve ganglion, representing the epipharyngeal gan-
glion of other molluscs. The anterior wall is trans-
parent, and forms a cornea in Loliginide.

Investing the eyeball is a silvery lamina (argentea externa),
under which is a somewhat cup-like cartilage forming the
fundus of the eyeball, and pierced by the branches of the
optic ganglion. The thick front edge of this cartilage is
called the equatorial ring, and from it longitudinal muscular

* In development the optic ganglion grows at the expense of the white
body, and, according to the researches of A/r. Lankester, the optic nerve
and ganglia appear to be developed from the mesoblast.

Introduction to Animal Morphology. 208

fibres pass forwards (fibres of Zanger) to the origin of the
iris, which is a circular fold in front of the lens, also contain-
ing a support-cartilage within it. Within this is an argentea
interna, and the retina. ‘The front of the choroid is thickened
into a corpus ciliare (c. epitheliale), developed from the anterior
lining cells of the primitive optic vesicle, which surrounds
equatorially, and is continuous with, the biconvex lens whose
hinder surface is the more convex. Behind the lens isa
fluid vitreous humour. The retina consists of two layers, an
outer (s/ratum conjunctivum) and an inner (s. epztheliale). These
consist of seven lamina, the outer of four* and the inner of
three.| There is neither lens nor cornea in Nautilus, and
the eye chamber is an open cup, as it is in the earliest stage
in the embryo of Dibranchs. There is no cornea in Loli-
gopsis nor Histioteuthis, and in Loligo there is a hole in the
cornea, whereby the sea-water bathes the front of the lens.

The lobate, unsymmetrical ovary dehisces into a
segment of the perivisceral space, from whence its
products enter the usually azygous genital ducts
(paired in Octopodidze, OOmmastrephes). The oviduct
opens at the beginning of the funnel, or in forms with
hectocotylized males, deeper in the mantle cavity.
The oviduct wall has an annular gland in Nautilus
and Octopods, and near its mouth a pair of rudimental
glands, long lamellar pouches, secrete the sheath for
its eggs.

The testis has a capsule which, like that of the
Ovary, is only attached to it at one spot; its vas
deferens is long, coiled, widening to its end, often
with one or two prostatic appendages, or a coiled
cecal pouch. The papillary opening of the vas has

* Membrana limitans, or surface connective, nerve vesicles, and a reti-
cular or connective support layer.

t A pigment layer containing rods, granules, a layer of rods and an
inner limiting homogeneous layer.

Ve2

324 Introduction to Animal Morphology.

sometimes a long surface groove communicating
therewith. Sometimes one arm, with few suckers
(Sepia), or with a spoon-shaped end (Octopus, Eledone),
is set apart as a male sex-organ, and reaches a large
size, having a filamentary extremity and a Need-
hamian vesicle at its free end; this, being set free,
enters the mantle cavity of the female, and thus im-
pregnates it. This arm is called a Hecfocotylus ; it is
the third right arm in Octopus Carena, and Tremoc-
topis, the third left in Argonauta, and was formerly
regarded as a trematode parasite. A new arm is
produced when the hectocotylus is detached. In
Nautilus the oviduct opens unsymmetrically on the
right. The spermatozoa are united by the secretion
of the cecal pouch into cylindrical spermaphores, the
moving filaments of Needham.

The ova undergo only very partial segmentation
at a germinal flat discat the pointed end of the ovum;
here a cap of cells becomes visible (£/as¢oplasts), and in
the underlying substance a series of bodies form,
which look like nuclei, but without differentiated cell
areas round them (au/oplasts) ; these become branching
contractile cells, in which inheres the rhythmically
contractile power of the yelk sac.

After segmentation, the mantle, gills, and epipodia
form, then the sense-organs, then the foot and its mar-
ginal processes.* There is no metamorphosis, and the
organs are formed by the time the shell breaks.

Of the z000 known species, only 218 are now living.
They are divided into two orders :—
1. Tetrabranchiata (Owen)—shell siphonate, camerated ;

* Most of our knowledge of the embryogeny of Cephalopods we owe
to Mr. Lankester’s researches, and to those of Salensky.

Introduction to Animal Morphology. 325

gillsfour; tentaclesnumerous; ink-bag none; epipodial lamellz
convolute with ununited edges; eyes stalked ; mantle attached
annularly to the shell. There is one living genus, Nautilus,
the type of the family Nautilide, whose septa are simply
curved ; of the fossil genera, ten belong to the same family,
and eighteen to the family Ammonitidz, with lobate septal
margins.

2. Dibranchiata (Owen)—external shell none ; arms 8-10,
acetabuliferous ; epipodia united to form a funnel ; epidermis
with chromatophores ; an ink-bag, and two gills with branchial
heart at base, also exist. About 212 species are living, 159
being extinct. They are divided into two sub-orders :—1. De-
capoda (Leach)—with two tentacular arms, except in Cheiro-
teuthis, retractile into pouches under the eyes, and pedicellate
suckers. Here are included two series :—I. Chalcophora—
with an inner calcareous shell. This includes the following
families :—Spirulide—shell an open spiral, camerated, sipho-
nate, nacreous, included in the hinder part of the body; eye
with a closed cornea. Belemnitidz—extinct, with a straight
included, camerated, siphonate shell; arms with six rows of
small suckers. Sepiadze—oval, with long, lateral fins; eyes
with closed cornez ; shell prolonged to a point; its lamelle
not separated by siphonate chambers (Cuttlefishes). Series
II. Chondrophora—shell of conchiolin supported either by
two internal fleshy bands (Cranchiadz, Loligopsidz), or by
three internal cartilages (Cheiroteuthidz, Onychoteuthide,
Loliginidz). Herein are contained two groups:—1. Myop-
sidee—eyes with closed cornea; littoral, including the families
Loliginidee—elongate, with suckers on the buccal membrane,
and inner shell as long as the body ; mantle free. Sepiolida—
short, with rounded fins, and no buccal suckers; mantle at-
tached anteriorly; shell half as long as the back. Group
2. Oigopside—eyes with open cornex, pelagic; including
Cranchiade—round, with terminal fins ; mantle united to the
small head by a neck band; eyes large, and the corneal
opening small; funnel with a valve. Loligopsidz—soft,
transparent, long, pointed behind, with terminal fins ; funnel
long, with no valve; eyes stalked; shell lancet-shaped, as
long as the back. Cheiroteuthide—long, with two dorsally

326 Introduction to Animal Morphology.

placed fins; mantle united by hinge cartilages, linear
or dilated, not by muscle; arms united by membrane;
funnel short, with no valve; shell long, slender; tenta-
cles non-retractile. Thysanoteuthide—long or oval ; arms
free; inner shell auricled at base, or hastate. Onychoteu-
thide—long, cylindrical; eyes with a wide corneal open-
ing and a sinus above; arms with hooks along their margin;
funnel with a valve; shell dilated at both ends (Enoploteu-
this), in front with one central and two lateral ribs (Omma-
strephes). Sub-order 2. Octopoda (Leach)—arms eight, with
sessile suckers, each without a cuticular ring; body short,
roundish ; mantle usually without a hinge cartilage ; oviduct
paired; nidamental gland none. This includes Cirrhoteu-
thide—arms united by membrane to tip: body soft, with
round fins; a cartilaginous inner shell; the suckers alternate
with cirrhi. Octopodide—mantle joined to the visceral sac
by a broad muscle at the median line; shell and water pores.
none; suckers short, in one (Eledone) or two rows (Octopus).
13. Philonexidze—mantle witha cartilaginous, button-like hinge
apparatus, and many water pores ; suckers fleshy, peduncled ;
arms all free (Philonexis), or two of them webbed (Tremocto-
pus). Argonautide—arms subulate, the two upper webbed
at end, and secreting a shell in the female; mantle hinge
apparatus as in last ; male much smaller than female.

The gigantic pelagic forms, krakens of the Scandinavians,
belong to Onychoteuthidz, and form the genus Architeuthis
of Sveenstrup. The arm of one of these, driven on the west
coast of Ireland in 1875, measured thirty feet in length.

Introduction to Animal Morphology. 327

CHAPTER. XXXIX.
SUB-KINGDOM 6.—ARTHROPODA (vz. Szebold).

SYMMETRICAL, mostly dicecious,* non-ciliated schizo-
coelous (p. 47) persone, of a limitedt specifically con-
stant number of often heteronomous metameres or
somites, each usually with a pair of ventrally-articu-
lated,+ hollow,§ jointed organs, as feelers, jaws, or limbs.
The body consists of head, thorax, and abdomen: the
first contains not fewer than four united somites,
bearing the sense-organs preorally; the second bears
the locomotory limbs; the third contains the vegeta-
tive and reproductive organs.|| The heart, when pre-
sent, is dorsal, tubular, often segmented, and the
circulation is more or less lacunary. Breathing
takes place by the surface, gills, or trachee. The
digestive system is absent in some parasitic Crusta-
ceans, aproctous in the larve of Myrmeleo and some
Hymenoptera. In others the mouth is anterior, ven-
tral, the anus rarely dorsal (Dias, &c.), usually termi-
nal, or sub-terminal. The intestine is seldom tortuous
(Insecta), or it may have lateral ceeca (Arachnida).
On the surface is a firm, coloured, lamellated, nearly
structureless layer of Chitin,§] with or without an in-

* Except Cirripedes and Tardigrades, and anomalously in some insects.

t Except in Myriapods.

} The wings ofinsects and the shell-flaps of Entomostraca are unjointed
processes, not true limbs.

§ Containing muscles for their motion.

|| These organs are never metamerically multiplied, though the respira-
tory and nervous systems are so arranged.

| Peligot supposes that Chitin (Ci7Hjs:NOu) is a mixture of a proteid
and a cellulose compound.

328 Introduction to Antmal Morphology.

terstitial calcareous deposit, pierced by many pore
canals* and by processes of the dermis, strong around
each metamere, thin in each intermetameric space,
so as to allow of motion, and it is periodically shed
and renewed. It is often prolonged for a short way,
or for the whole length, into the interior of the diges-
tive canal, and sometimes projects into the body for
the attachment of muscles (endophragma, or endo-
thorax). Uni- or multicellular hairs or bristles may
form as extensions of this layer, either firmly attached
or loose (scales of Lepidoptera). Under this is a
colourless, chitinogenic, cuticular layer of hexagonal
epithelial cells, or of continuous protoplasm, with re-
gularly scattered nuclei. Beneath this is the con-
nective dermis. The muscles are colourless, not in
laminz, but metamerically divided, with transversely-
striped fibres grouped in numerous bundles.t There
is a pharyngeal nerve ring, with an epipharyngeal
brain-ganglion (absent in Pentastomide),} and a hy-
popharyngeal pair of ganglia with complex commis-
sures,§ from which a double ventral cord extends,
having in each metamere a pair of ganglia whose
upper surfaces are motor and the lower sensory (?).

* Which are either fine, and full of air and water, or larger, and con-
taining protoplastic processes of the cuticle. In Sphzroma they are wide,
anastomosing, and branching.

+ Lubbock describes fifty-eight in a single somite of an insect, arranged
as flexors, extensors, elevators, depressors, retractors, protractors, adduc-
tors, abductors, and rotators. The fibres do not anastomose, and are of
great power—thus a flea can leap 200 times its own height.

+ Not homologous with the brain of a Vertebrate ; nothing but the most
general comparisons can be made between the nerve centres ofa Vertebrate
and those of an Arthropod.

§ Complex, because the head ganglia are made up of several fused me-
tameric ganglia.

Introduction to Animal Morphology. 329

The nerve cells are unipolar, and the interior of the
ganglion consists mostly ofgranular substance: many
have a sympathetic system having its roots in the
ventral ganglia, and a separate vagus nerve at-
tached to the pharyngeal ring. The ova undergo
partial cleavage,* the undivided part of the yelk re-
maining within the elongated blastoderm, which early
shows a primitive streak and a division into symme-
trical lateral swellings. Except in Isopods and Am-
phipods the segments appear before their appendages.
The germ divides into two layers, the outer forming
the skin, muscles, and heart, the inner, the digestive
and reproductive (?) organs. Parthenogenesis occurs
in several cases, Metagenesist in one. In most cases
the young undergo either progressive or retrogressive
metamorphosis.

There are two primary divisions of Arthropoda :—

Division I. Branchiopnoa (Schmarda)—water-
breathers,t mostly with two pairs of jointed head
appendages or antenne. This includes the polymor-
phic class Crustacea (Latrezl/e), characterised by hav-
ing the body divided into cephalo-thorax,§ abdomen,
and often post-abdomen. Each metamere usually
bears an appendage, even when it is fused with its
neighbours. The “crust” of each metamere consists
of a dorsal and a ventral lamina united at the point
of attachment of the limbs. In some the dorsal shell
consists of two median, /erga/, and two lateral, epzme-

* Except in some Cirripedia, Copepoda, Pentastomidz, the summer eggs
of Daphnia, Artemia, &c.

t+ Heteropeza, Family Cecidomyide.

{ Some Isopods are terrestrial, but gill-bearing.

§ Sometimes only the anterior thoracic segment or segments unite with
the head, leaving the hinder free.

330 Introduction to Animal Morphology.

val, pieces, while the ventral consists of two central
sternal and two episternal portions. These plates are
always united, and at their sutures send in apodemata
or processes. In lower forms the number of somites
is varied by suppression or multiplication (Apus).
The normal number of post-abdominal somites is six,
of abdominal, five, of thoracic, three, and of cephalic,
S1X.

The chitinous layers are usually calcified; the
cuticle* often contains unicellular glands opening into
the pore canals, sometimes clustered (Argulus), and
stellate pigment cells, green, purple and red—the
latter colour being the most permanent, as boiling or
reagents redden the others.

The limbs vary in each class, but Fig. 34.
in the higher forms the arrangement is
as follows :—Pre-orally there are two
pair of antenne, the anterior smaller
(antennules), and the hinder larger :
the former usually consist of three ba-
sal joints (the basi-, ischio-, and mero-
podite), terminated by a many-jointed
annulated feeler or pair of feelers:
the latter has five basal joints (coxo-,
basi-, ischio-, mero-, and carpo-
podite), and a long, ringed, feeler,
like the foregoing. The sternum of
the antennary somite is called efzsto-
ma, and behind itis theclypeus, labium, PPPowtt OoSmay a
or upper lip. The post-antennar seg- “""*“*""™"*?® re
ment bears as its appendages on each

*In Sapphirina the cuticle is marked on its surface by a system of
wavy lines which give it an irridescent appearance.

Introduction to Animal Morphology. 331

side a mandible, which, with its fellow of the opposite
side, forms the front pair of jaws; each usually
bears externally a several-jointed palp, only absent
in terrestrial and parasitic forms; the next segments
bear maxillee or hinder jaws, and one or more of the

a

Fig. 35.

Limbs of Pandalus Jeffreysii :—a, a’, right and left 2nd pair of pereiopoda ; 4, outer
antenna; @, inner antenna; c, 3rd pereiopod; e, telson; /, pleopod; g, gnathopod.

following or thoracic appendages are also specialized
for the purpose of chewing.

The limbs behind this in lower forms consist of a
basal process ( froto-podite), to which is appended an
outer (exo-podide), and an inner (endo-fodite) process,
the latter sometimes represented by tufts of bristles:
in the higher forms the protopodite is lengthened, and
divided into parts corresponding to those in the base
of the antenna above given, and terminated by two
joints representing the ringed end of the antenna
(pro- and dactylo-podite).

_ The mouth is ventral, often displaced a little back-

332 Introduction to Animal Morphology.

wards.* It has, above, the labium, and below, a lower
lip (in Isopods and Amphipods), or a bifid tongue
laterally lie the masticatory limbs and their approxi-
mator and divaricator muscles. The salivary glands
are absent or unicellular in Copepoda and Cladocera;
largest in Gyge. The narrow cesophagus dilates into
a crop in some Entomostraca, and ends by projecting
into the stomach, whose anterior part is generally
gizzard-like, muscular, and lined by chitinous tooth-
processes, shed at each moult. The deepest portion
of the chitinous teeth is calcified in Decapoda, forming
a solid mass (Crab’s eyes), pierced by pore-canals.
The posterior part, or chyle-stomach, is thin-walled,
and usually constitutes the longest part of the diges-
tive tract; it may be of equal calibre throughout, or
dilated anteriorly, as in Isopods. Into it opens the
liver, which may be either simple cecal pouches or as
a complex gland. The ceca may be one azygos
(Schizopoda, Sida, Pleuromma) ; two, short (Clado-
cera), or long (Caprella, Cyamus); two lateral and a
medial (Polyphemus, Temora); two pair (Oniscus,
Gammarus, Lygidium); three pair (Idothea, Arga,
Ligia); four pair (Mysis, two small anterior and two
large posterior, Balanus), or none (Chthamalus, Coro-
nula, &c.) Or the ceca may be divided at their fun-
dus, or ramified (Argulus, Hedessa). In Apus there
are seven, ending in branched glandular nerves. In
Phyllosoma there is a pair of finely-branched ceca.
The second form of liver consists of numerous follicles
scattered over the wall of the chyle-stomach (Bopyrus

* Sometimes so much so that the cesophagus first bends forwards, and
then turns sharply on itself as in Limulus.

Introduction to Animal Morphology. 333

and Stomapoda).* The hepatic cells are yellow or
brown, and contain oil globules. Similarly colored
cells may form patches on the wall of the chyle-
stomach. The intestine is short, straight (except in
Cladocera), sometimes sacculated (Sapphirina), and
possessing ceca; rarely villous in patches (Gyge), or
marked on its inner wall with longitudinal grooves
(Isopoda). The anus is terminal, ventral, except in
Cladocera and some Copepods. In Astacus, Limna-
dia, Daphnia, &c., the intestine has been observed to
take in and discharge water rhythmically. Where
the chyle-stomach joins the intestine, or in the intes-
tine, are often cells holding concretions (of uric acid ?)
forming a layer of limited extent. In some larve this
renal area is isolated in a special cecum, which per-
sists in Cyclopsine Castor.

The other secretory glands are :—1. A poison
gland in Argulus, seated beside the mouth, with its
duct opening onthe proboscis. 2. The shell gland of
Copepoda, a coiled, fine tube on each side of the head,
opening by a slender duct at the base of the antenna.
In Phyllopods its duct opens into the mantle cavity.
In Schizopods and Decapods it is seated in the basal
joint of the antenna, and hence is called the anten-
nary gland, or the green pregastric gland, from its
colour in the crayfish. 3. The cement gland in Cirri-
pedia, placed at the base of the pedicles (which its
duct traverses) ; its secretion, poured out at the fixed
end of the stalk, is the medium of attachment. In the
Balanide this gland is complex, and lies on the basal
plate of the shell, which is surrounded by the anasto-

* There may be ten hepatic lobes, as in Stomapoda. In Decapods
they are combined into a bi-lobed organ.

334 Introduction to Animal Morphology.

moses of its ducts. This and the preceding gland
may be homologous, and possibly the “ voo¢s”’ of Rhi-
zocephala may represent its ducts.

Beside the intestine in the abdomen is a mass of
connective tissue and undifferentiated protoplasm,
containing yellowish or reddish fat: these are largest
proportionally in Entomostraca, and are among the
chief sources of the oil which many fishes store in
their livers. In Copepods this adipose body has a la-
cunary structure, and may act as a mesentery. Di-
gestive organs are absent in the rudimental males of
Cirripedes and parasitic Copepoda. The intestine is
absent in Monstrilla.

The body cavity contains blood, which is colorless,
reddish, or pale violet, with nucleated white corpus-
cles. A heart exists (except in Cyclopide, Corycei-
de, Harpactide, and Peltidide, among Copepoda,
most Ostracodes, and a few others) as a dorsal vessel,
whose simplest form, as in Cladocera, is a sac, over
the intestine, receiving blood by two lateral openings
(venous ostva), and sending it forward by one short
stem to bathe the brain, and enter the interstices of
the tissues, from whence it is returned to the heart.

In Pontellide and Calanidz there is a posterior ostium as
well as two lateral; and in Calanella the aorta is longer, and
divides into two. In Argulus there is one ventral osculum,
and the blood is sent by the heart partly through the body
and partly through amedio-posterior opening to the gill-like
appendages. In Phyllopoda the heart is elongated, and com-
posed of successive chambers (twelve in Apus), like a chain
of communicating Daphnia hearts. These have many ostia
(twenty pair in Artemia), but they do not correspond to the
metameres, as there is usually one for several somites. In
Poecilopoda the heart is surrounded by a pericardiac sinus;

Introduction to Animal Morphology. 335

in Limulus it has seven pair of ostia, and sends not only an
arterial stem fore and aft, but also four branches from four of
its intermediate chambers: these divide in the abundant in-
terstitial tissue, and end in lacunze. In Isopoda there are
fewer ostia (three in Tanais), and the heart stretches forward
to near the head. It extends towards the tail in Amphipoda,
where the ostia are also few (three, Phronima, seven, Gamma-
rus). These have one anterior aorta, or an anterior and aru-
dimental posterior. In the larve of the Podophthalms there
are two venous ostia; but as development proceeds, the num-
ber of chambers (five) and ostia may enlarge, as in Stomapoda,
and the heart then gives off anterior, posterior, and lateral

Circulatory system of Lobster; #, pericardium; %, heart; a, middle anterior
aorta; a”, hepatic artery; a”, ventral artery; a’, posterior aorta; v, ventral venous
sinus; v, veins from head; uv”, veins from the limbs; 4, gills; v.d, branchial veins.

branches, or as in Schizopoda and Decapoda the organ be-
comes concentrated, reticulated within, not divided into
chambers, and with its five pair of ostia not in a series, but in
a group. The anterior aorta is short, and gives off three
branches, a middle to the brain and eyes, and lateral to the
digestive and reproductive organs. The posterior aorta
divides into dorsal and ventral branches; the former to the
muscles of the trunk; the latter, which divides into anterior
and posterior branches, sending a vessel to each limb. These
branches end in capillaries, communicating, however, with
the perivisceral lacunz, from whence the blood enters a

336 Introduction to Animal Morphology.

ventral vein, passing in the sternal canal to a central sinus,.
from which branchial arteries convey it to the gills, and from
thence branchial veins pour it into the pericardial sinus.

The heart wall in Limulus and Decapods consists of
several strata of striped muscle within a connective envelope,
and at the orifices are passive valves. The heart is held in
its place by elastic processes and radial musculi alares, which,
by their contraction, dilate the vessel. In some Copepods:
the heart beats 100 times per minute.

Breathing may take place by the surface (Cope-
poda), by modified lamellary feet (Phyllopoda), or
appendages of the feet, by pouch-like appendages of
the thoracic segments (Amphipoda), or independent
organs attached to the base of the feet, or by the
mantle or lateral duplicatures of the skin in Ento-
mostraca.

In Cirripedes the inner wall of this mantle is often folded
into gill-like lamellae between the wall and the base of the
cavity. In Lepadidz the hollow of these gill-folds becomes.
a brood-pouch. Others have gills variable in number and
position, at the base of the cirri. Bran-
chipus and Artemia have gills on all
their feet. Apus on the anterior swim-
ming feet. In Nebalia the respiratory
and non-respiratory feet are sharply dis-
tinguished from each other; in others
there isnot much difference. In Isopods
they are attached to the five abdominal
feet as tile-like plates, of which, in , [ransversesection oflim-
Sphzroma, &c., one pairis differentiated % nerve ganglia; 2, gills;
and folded, or divided into strips (Ione). ”

In Oniscus and Porcellio one pair is altered into gill covers,
or the limbs of the last segment may form a cover (Idothza) ;
others are altered into vibratile organs which create cur-
rents in the gill cavity. In the terrestrial Porcellio and
Armadillidium the anterior gill is air-holding. In Tylus four

Introduction to Antmal Morphology. 237

pair have fine slits in them, through which air enters into
cecal tubes. In Stomapods the gills are fringes at the bases
of the five abdominal feet. They are branched processes of
the limbs of the cephalothorax, either floating freely (Thysano-
poda), or roofed in by a process of the carapace according as
they arise from the bases of the thoracic feet or from the body
wall; in these cases, as swimming does not provide fora change
in the water bathing the gills, there are thin; flat, external pro-
cesses from the bases of the maxillipedes which create in-
ternal currents. In Amphipoda the 5-6 pouch-like gills are
often covered by elongations of integument, sometimes closing
in a perfect (Typhus), or imperfect gill cavity (Sergestes).
In Poecilopoda the first pair of abdominal feet, by the basal
union of their proximal joints, form an operculum, under
which are the gills. Caprella hastwo short gills. In Lopho-
gaster there are not only dorsal, but ventral gill filaments,
projecting freely between the feet. Euphausia has the gills
of the first pair of limbs as a single pouch-like process. In
Decapods the gills are lamellar, twenty in Nephrops and
Homarus, twenty-one in Scyllarus. The outer wall of the
gill chamber has in some crabs a number of glandular swell-
ings, which in Gecarcinus and other land crabs are large
and spongy, and keep the gills wet. When the gills exceed
the feet in number, the supernumerary lamellz are attached to
the first and second pairs of limbs.

The nervous system has long commissures uniting
the pre-cesophageal with the post-cesophageal gan-
glion, and a ventral chain of ganglia, primarily paired,
but usually united medially. The nerves often arise
along with, and apparently from, the commissures.

The brain ganglia are small and separate, with a median
commissure in the parasitic Copepods. In Lepadidz the
ventral chain consists of 4-5 ganglia, while in Balanidz there
is but one, compound, condensed. In Peecilopoda there is a
large pharyngeal mass, united by three commissures under the
pharynx, and giving a double branch to the trigonal tail. In
many Amphipods the size of the brain depends on that of the

Z

338 Introduction to Animal Morphology.

eyes. When they are large, as in Phronima, the brain is large,
while in eyeless forms it is exceedingly small; sometimes it
is lobed (Oniscus). In the ventral cord of these there is often
a considerable degree of fusion of ganglia, which are 10-12
in number, 7-13 in Isopods, 9 in Laemodipoda. In De-
capods and Stomapods, as the mouth retreats from the eyes,
the lateral commissures are often enormously long, and united
in front of the hypopharyngeal ganglion by a transverse com-
missure.* In Stomapods there is an anterior small epi-
pharyngeal brain, followed by the long united commissures,
and a large cephalothoracic ganglion, the fused metameric
ganglia of the peri- and post-stomial segments, from which
the thoracic limbs derive their supply ; then follow three ab-
dominal, and six post-abdominal ganglia, of which the last is
often large. In Schizopoda there are six cephalothoracic and
abdominal, and six post-abdominal ganglia, and in Anomoura
the post-abdominal ganglia are fused into one. In crabs all
the post-oral ganglia form a hypopharyngeal central mass.

The antennar, antennular, and optic nerves arise
from the brain ; the auditory nerve varies in its origin.
In Cirripedes there are two visceral nerves, one from
the ventral ganglion, and one from the pharyngeal
ring; these unite in a plexus. An azygos gastric
nerve also exists from the ventral ganglion, and there
is a corresponding nerve in some Branchiopoda. A
cardiac nerve and ganglion exist in Limulus; but
these are obscure in most Entomostraca. Thenumber
of ganglia is thus variable, the small numbers indi-
cating concentration, not simplicity. The nervous
system in Cladocera approaches most nearly to that
of Vermes. Apus has the largest number of ganglia
(two thoracic, eleven abdominal, and about forty-nine
post-abdominal). Branchipus and Artemia have
thirteen pair.

* Apus has a similar commissure.

Introduction to Animal Morphology. 339

Sense-organs are well developed in the higher
Crustacea. The antenne are organs of touch, and
possess, near their points, groups of minute rod-like
nerve-endings like short stiffbristles, into which nerves
pass, and end in a granular protoplasm. Similar,
but more elongated, bodies in the anterior antenna
are supposed to be olfactory, or else a conical organ (in
Decapods) at the base of the outer antenna, whose free
end is either open or closed, may be an organ of smell.
The olfactory rods are better developed in males
than in females, and are sometimes pectinated.

The ear is a dermal sac, either closed, containing
an otolith, or open, with a simple or complex mouth,
sometimes containing a foreign body acting as an
otolith. The cavity is lined with regularly disposed,
stiff acoustic hatrs, either attached to the otolith, and
holding itin its place, or freeat oneend. These hairs
have their shafts continuous with a delicate, superfi-
cial, chitinous layer lining the vesicle, and are only con-
nected to the deeper structures by their axes. Similar
hairs, like the sensory rods of the antenna, are found
out of the vesicle.

The organ in Decapods is open at the base of the inner
Fig. 38.

Crangonyx subterraneus, a blind Crustacean.

antennule, and supplied by a branch of the inner antennary
Z2

340 Introduction to Animal Morphology.

nerve. Closed vesicles are found in the larva of the crab,
containing an otolith, which is afterwards lost. They are
also closed in Hippa, Pinnotheres, Hyas, Ocypoda, Gelasi-
mus, &c. There is no earin Crangon, Pandalus, Phyllosoma,
Erichthus, Thysanopoda. In Mysis it is a closed vesicle,
with an otolith attached by two hairs, and it is placed at the
base of the inner appendage of the tail-fan, receiving its
nerve from the last ganglion.

The eye is only absent in cave-dwellers like
Astacus pellucidus of the Kentucky cave, and may
be of several types. The essential part consists of a
nerve fibre, ending in a long crystal cone, whose apex
is directed inwards, merging into the nerve, and
whose base is highly refracting and turned outwards.
There is no special lens, but the chitinous integument
is transparent where it covers the organ, which in the
simplest case is quite free, and capable of sub-dermal
motion.* Such single crystal cones exist in Cope-
pod larvee, one on each side of the brain ; sometimes
a cluster of these may be present (Coryceide, &c.),
either medial, cyclopean, or bilobed. Sometimes two
pair of these clusters are present, the outer of which
may develop large crystal cones, while the inner
fuse medially, and are rudimental, giving the appear-
ance of three eyes.

In higher forms the chitinous integument becomes
moulded on the front of the crystal cone as a corneal-
lens, and is thus promoted into being a part of the
organ. Usually several, or many such crystal cones,
imbedded in pigment, are united, forming a compound
eye. The corneal lens may be simple over the cluster

* In Argulus the eyes lie in a blood sinus in the head-shield. In many
Copepoda a muscle passes from the wall of the orbital cavity to the eye-
ball to move it.

Introduction to Animal Morphology. 341

of cones, but is usually divided, each cone having its
own hexagonal corneal lens or facet. Eye-like sense-
organs, or, at least, red shining spheres, are distri-
buted on the sides of the thoracic legs of some, or
between the four anterior abdominal swimming feet.
In Podophthalms the eye is mounted on an un-
jointed stalk, considered by some as a true limb.
Cirripedes are hermaphrodite, the ovaria and testes
being branched pouches, only distinguishable by their
products. In Barnacles the ovary is in the stalk, and
is formed in an outgrowth of the mantle, into whose
cavity it opens at the base of the first pair of cirri. In
Balani they are imbedded in the mantle, the testes
surround the digestive canal, and the vasa deferentia
accompany the intestine, and often unite and open at
the post abdomen. In free Copepods the ovary or testis
is single, central, lying on the intestine. There are
two oviducts, one on each side, opening either sepa-
rately or together, and having their hinder part often
dilated into a uterus, or having a series of egg-holding
czeca (Coryceeide). The wall of the last part is gland-
ular, or a gland lies on it which secretes an adhesive
material whereby the eggs are united in clusters, and
carried by the female beneath the abdomen. There is
often aterminal receptaculum seminis. Some parasitic
Copepods have a double ovary, and the testes are
either similar or single, with a double tortuous vas
deferens, dilated at its end into a vesicula seminalis,
in which the spermatozoa are cemented into sperma-
phores, and with a papillary end which may act as a
penis. Sometimes the right vas aborts (Pontellide,
Calanide). In Branchiopoda the ovary is either mul-
tilobar or a series of pouches along the intestine. In

“42 Introduction to Animal Morphology.

Poecilopoda the ovary consists of long, tortuous,
branched, and anastomosing tubes, those of the two
sides united medially. In Isopods the ovary is long,
saccular, with a median oviduct. In Oniscus the tes-
tis consists of three pair of pouches, which unite into
one pair of vesiculee seminales. Mysis and Decapods
have a median ovary, with two large, lateral, saccular
(Mysis), or lobate oviducts : these open at the base of
the third pair of feet. In Anomoura the testes are ab-
dominal. Some Stomapods have lateral pouches from
the median ovary, and two or more oviducts which
unite at a common sexual orifice. In Cirripedia and
some Copepods, pigmy or complementary males are
developed, with no digestive organs,* like those in
Rotatoria. The spermatozoa may be globular (Phyl-
lopoda), flattened (Palemon), crescentic (Cladocera),
thread-like (Argulus), radiated (Decapoda), sometimes
dimorphic (Isopoda), and either amceboid or motion-
less. In Cyclopsine, Branchipus, &c., the antenne of
the males act as claspers.

In development the ova may undergo complete di-
vision, with no primitive streak, and form a larva or
Nauplius, with an oval body, one eye, and three pairs
of limbs. In higher forms the cleavage is only partial,
a primitive streak forms from which the germ lamel-
le extend, inclosing the unsegmented food yelk; the
young becomes a Zoca with a spinose carapace, paired
eyes, and post-abdomen. Sometimes both the Nau-
plius- and Zoea-stages are gone through before emer-
gence from the egg.

* Complementary males are developed in the hermaphrodite forms
Cryptophialus, Alcippe, &c., as in the dicecious forms, as Ibla, Scalpellum,
&c. The male of Limnadia Hermanni is unknown.

Introduction to Animal Morphology. 343

CHAPTER XL.
SUB-CLASS 1.—CIRRIPEDIA (Lurmezster).

THE Crustacea are mostly marine; over 3000 species
are known as now living, divided into the following
sub-classes :—

Sub-class 1. Cirripedia (Burmezster)—retrogradely
metamorphosing Crustacea; sessile in their adult con-
dition; fixed by the front of the head. The dorso-
lateral integument is reduplicated around the body asa
mantle, and the pre-ovarian cement (antennary ?) gland
pours out a secretion through the third or disc joint of
the modified antennez, whereby the body is anchored.*
The hinder part of the body is free, lying in the
mantle cavity, and protrusible, retaining six pair
of prehensile, polyarthrous limbs, each with an endo-
and exopodite. The mantle becomes calcified and
chitinized in parts, forming a shell of several pieces,
united by intervening soft portions. The body may
be on a flat basis or stalked, the stalk or peduncle
being soft, horny, flexible, composed of the front of
the head, the cement ducts, and their secretion. The
feet (cirri) and soft part of the body periodically moult,
but the shell grows in successive layers, and is never
cast.

The mouth lies in the mantle cavity, bordered by
a pair of toothed mandibles and a palp-bearing cly-
peus. The maxille unite and form an under lip. The

* In Lepas fascicularis the abundant cement forms a basis for the attach-
ment of a cluster of individuals, and may even form a float for them.

344 Introduction to Animal Morphology.

stomach is small, with hepatic czeca at its pylorus, and
with two small, lobed, anterior glands, which may be
salivary. The anus is between the two hindermost pair
of cirri. The heart is a simple, tubular, dorsal vessel,
with an anterior s¢zus longitudinalts (Martin St. Ange),
but the peripheral circulation is lacunary ; respiration
is dermal, or in some Lepadide by lancet-shaped gills,
or in Balanide by folds of the mantle lining. The
larve possess simple eyes, which disappear at the
first moult after the animal becomes sessile.

There are pigmy eye-bearing, saccular males, con-
taining no organ but a testis, straight cirri, and adhe-
sive antennze, sometimes lodged in transverse pits in
the shell of the female (Scalpellum). The young are
minute azwpliz, free, oceanic, at first oval, pointed
behind, with one or two pair of antenne ; the mantle
layers then begin to form on each side, and the Nau-
plius becomes a cypris-like Pufa, which at the fourth
moult becomes sessile, inclosed in the mantle; at the
fifth moult eyes and antenne disappear as such, being
completely modified, the mantle calcifies, and addi-
tional abdominal limbs form, which develop into the
cirri, while the mouth appendages and the post abdo-
men develop. Cirripedes are marine, found on stones,
ships, and as oikosites on whales, fish, mollusca, &c.
About 100 living species are known.

They are divided into four orders :—

1. Thoracica (Darwin)—stalked or sessile, with six cirri-
ferous segments; a rudimental abdomen with post abdominal
appendages; labrum not separately movable; pupa dodeca-
pod. This contains three families :—1. Lepadidz, Barnacles—
peduncle containing the ovary and cement gland; shell late-
rally compressed, trigonal, with rounded angles, with (Lepas)

Introduction to Animal Morphology. 345

five calcareous plates, one dorsal, azygos (carina), two large,
lateral, anterior (scwfa), and two, small, posterior (¢erga) ; an
adductor muscle is attached to the scuta, but all are separately
movable on each other. Sometimes these pieces may be far
removed from each other, and small (Otion), reduced to
two, or even no calcified plates may exist (Anelasma), or the
plates may be 20-100, the five principal being detectible
(Pollicipes), or 15-20, indistinguishable (Scalpellum, the
males of this form have 2-4, the females 15-20 plates).
2. Balanide—sessile, conical or cylindroidal, on a calca-
reous basis, which has the ovary and cement gland be-
tween its lamelle ; shell-pieces, 4-8, immovable in a circle,
whose posterior (upper) opening is closed by a retractile
operculum of two pairs of plates (scuta and terga), moved
by adductor and depressor muscles. In this shell the lepa-
‘dine carina forms an annular wall, within which the scuta and
terga are prolonged, their posterior ends forming an opercu-
lum. The annular wall consists of two symmetrical, lateral
pieces (carina and rostrum), with a thin, outer (vadzus), or
inner (a/a) lateral process; between the carina and ros-
trum there may be one pair of lateral plates, or two pair
(rostro-lateral and carino-lateral). ‘The rostrum sometimes
has an ala, with a test of six (Chthalamus) or eight plates
(Octomeris). The rostrum in others has a radius, and
the shell may be all of one piece (Pyrgoma), or of four
vertical plates (Tetraclita), or six, as in Balanus, or in the
whale oikosite Coronula. 3. Verrucide—scuta and terga
with no depressor muscles, movable at one side; on the
Other fused with the rostrum and carina.

2nd. Abdominalia (Darwin)—mantle compressed, conical,
with a lateral opening (Alcippe), or flask-like, with terminal
opening (Cryptophialus) ; with no calcareous plates, but with
a broad adhesive disc; body, at least for its hinder part, seg-
mented ; labrum long, movable; cirri abdominal, three pair ;
dicecious, with pigmy males, of which two are attached to
each female.

3rd. Apoda (Darwin)—mantle filamentary ; mouth sucto-
rial ; body imperfectly segmented, with no cirri, ex. Proteo-
lepas.

346 Introduction to Animal Morphology.

4th. Rhizocephala (& Miller) — Suctoria (Lilljeborg) ;
parasites on the abdomen of crabs ; adults mouthless, saccular,
elongated (Peltogaster), or transversely elliptical (Sacculina),
membranous, filled by the ovary and testes, which appear to
communicate ; the end of the oviduct dilates into a brood
pouch ; the digestive canal has vanished (Sacculina has an
cesophagus); foot-like tubes (modified antennze or cement
ducts) spring from the head and penetrate to the liver and
intestine of the host. The larva isa tailed Nauplius, which
develops a mantle and head tubes; then the nauplian feet
are lost, and six pair of abdominal feet developed, which are
finally lost. These are Cirripedes degraded by parasitism.
In Thompsonia the larva seems to pass the nauplius stage in
the egg, from which it starts as a two-eyed Cypridine larva

(Semper).

CHAPTER, 20:
SUB-CLASS 2.—COPEPODA (JZ. Edwards).

CRUSTACEA with a cephalothorax, a pair of jaws, two
pair of maxillipedes, and one or two of abdominal
feet, some of which abort in the parasitic forms; gills.
none, or leaf-like, abdominal appendages (Caligine).
The free forms have movable and palpiferous man-
dibles, and two pair ofantenne, the anterior of which
become rudimental in the parasitic species. The in-
testine is simple and straight. The sex-organs open
on the fifth abdominal segment at each side, and the
spermaphores are flask-like and left adherent to the
mouth of the oviduct, where they remain even after
they are emptied. The young begin life as Nauplii,
the anterior pair of limbs becoming antennez, the

Introduction to Animal Morphology. 347

hinder the mandible and maxillipede. The post ab-
domen bears a fringe of bristles, and often is split into
rudder-like processes ; many are acardiac.

Two orders are included :-—

1. Gnathostomata—free, minute, marine, or freshwater,
with developed jaws, and a moderate post-abdomen. ‘This
includes two families :—1. Cyclopide—first pair of anten-
ne long, oar-like, with (on the right only, Diaptomus)
thickened clasping joints in the male; the female carries
two (one in Diaptomus and Canthocamptus) lateral egg-
sacs; eye either median (Cyclops, Diaptomus) or paired
(Cetochilus, Sapphirina). The male Sapphirina is luminous.
Cetochilus sometimes dyes the sea a deep red. Monstrilla,
Calanus, Pontella, and Corycea are often made types of sub-
families. 2. Notodelphidze—parasites in the branchial sacs
of Ascidians; body 11-12 ringed; in the females the fourth
and fifth metameres are united, forming a brood-sac for the
eggs; maxilla many-cleft ; first abdominal ring joined to the
cephalothorax.

Order 2. Siphonostomata
(Latreille)—adults ecto-para-
sitic on fish, with suctorial
mouths, soft bodies, and
retrogressive metamorphosis ;
jaws reduced to bristles ; thorax
imperfectly or not segmented ;
front feet hook- or sucker-like ;
the males are often pigmy, and
the females usually carry their
eggs, like Cyclops, in two Cyclop quadricornis, with its two
sacs. They include the fol- SSR Eee. Nampns ae
lowing families :—1. Ergasilida—passage forms, the females
only parasitic; body thick; antenne jointed and bristled ;
second pair clawed ; post-abdomen jointed, with bristle-bear-
ing tail; abdominal feet removed from the medial line; the
males in Nicothoé, &c., are Cyclops-like, and in the female
(a lobster parasite) the abdomen forms on each side a long
lateral sac, and the egg clusters are between these. The

348 Introduction to Animal Morphology.

pyriform Ergasilus lives on the gills of eels, Lichomolgus in
Ascidians. 2. Argulinide—body flattened; cephalothorax
and abdomen fused ; post-abdomen small; eyes two, aggre-
gate; two pair of maxillipedes; females with no egg-sacs;
front antenne hook-like, the second jointed ; abdominal feet
only cleft at the tip ; liver multiramose ; proboscis protrusible,
with two annular poison glands; front maxillipedes forming
suckers (Argulus) or hooks (Gyropeltis). 3. Caligidae—flat ;
cephalothorax discoidal; post-abdomen small, often un-
jointed, with two terminal lamellae. The front pair of an-
tenne are fused at base, and only the last two (Caligus,
Dinemura, Pandarus) or three (Laemargus, Elytrophora) ;
joints free; the mandibles are two stilets within the suctorial
proboscis ; the females carry egg-sacs. 4. Dichelestida—
cephalothorax small, separate from the five abdominal
somites ; anterior antenne free, many-jointed ; second hook-
like ; males unknown; first pair (Dichelestium), or all the
abdominal feet, two-branched (Kréyeria). 5. Chondracan-
thida—worm-like, with small cephalothorax, a rudimental
pair of foot-jaws ; abdominal feet leaf-like; males pigmy;
abdomen unsegmented
(Chondracanthus), or
the three foremost joints
united, the fourth nar-
row, and the fifth very
long (Peniculus). 6.
Lernzopoda — worm-
like, witha pairofpigmy
males on each female ;
body formed of two
segments (cephalotho-
rax and abdomen) ; the
second pair of maxilli-
pedes unite in a terminal sucker; cephalothorax pyriform
(Achtheres), or worm-like (Anchorella, Tracheliastes). 7. Pen-
nellide—worm-like, with a short, unjointed cephalothorax
with unjointed limbs, lateral suckers, and minute abdominal
feet. Pennella has a feather-like post-abdominal appendage
(Fig. 40).

A, Pennella Orthagorisci. B, head magnified.

Introduction to Animal Morphology. 349

Sub-class 3. Ostracoda (Latrezlle)—free, micro-
scopic, freshwater, or marine Crustaceans, whose
hardened tegumentary folds form a bivalve, ventrally
open, shell-like case, closed by an adductor muscle;
they form one family. The body is of a bean-like
form, often acardiac, with gills appended to the first
and second pair of feet, while the third and fourth
have none. The rudimental post-abdomen is un-
jointed ; the eyes are two, single or aggregate; the
two pair of tentacles are equal and bristled; the
mandibular palps jointed. There is a crop with a
cartilaginous bristled and folded ring around it, and
the intestine has a convolution. There are six testi-
cular pouches,* ending in a tortuous vas deferens. In
the males the third pair of legs form claspers; the
third and fourth pair of abdominal legs are absent in
Cypridina; swimming feet in Cypris,t clawed in
Cythere.

Sub-class 4. Branchiopoda—usually minute, mostly
freshwater forms, the direct expansions of the Nauplius
type, with 1-3 pairs of jaws, a distinct head, rudi-
mental thoracic limbs, but a large abdomen, either
homo- or hetero-nomously segmented, bearing 5-60
feet; a heart is always present, and the cesophagus
rarely has a crop; the feet, or some of them, are flat,
lobed, with gill appendages; the eyes are simple or
compound, but never with a facetted cornea ; the males
are few, often with large spermatozoa, and impregna-
tion precedes the deposition of the hard-shelled win-

* The viviparous Cythere has a lash-like spermatozo6n, with one end
broad, abrupt, and the other pointed, with a pedicle attached at right
angle.

+ In Cypris the spermatozoa are coiled, three times the length of the
male animal,

350 Introduction to Animal Morphology.

ter eggs, while in summer pseudova are produced by
parthenogenesis.

Two orders are included :—

1. Cladocera (ZLa¢frei//e)—including one family, short, com-
pressed, with a two-valved shell, which does not cover the
united large head and rudimental thorax. The front antennz
are small and palp-like, the second pair large, bristled, and
cleft, acting as oars and as claspers in the males. The eye
has often a ring of crystal cones around the central pigment
mass, and a secondary eye may be present beside it. The
unjointed post-abomen is bent down, with two claw-like
processes. The gill feet are four pair(Polyphemus, Evadne),
five (Daphnia, Lynceus), or six (Sida, Holopedium). In the
females the eggs are received into a brood-pouch between
the shell and the body posteriorly. Bosmina has two long
frontal processes covered with sensory rods. The larve, on
emission from the egg, have the adult number of legs; 20-50
pseudova are laid by each female, but only 1-3 winter eggs,
which are darker, with a compact yelk, and are surrounded
by a second shell or ephippzum, derived from the lining of the
brood-pouch.

Order 2. Phyllopoda (La/reille)—elongate, with often a
thin dorsal shell, but less perfect than in Cladocera; eyes
two, large, and one or two small, stalked or sessile; abdomen
many-jointed, tail-like posteriorly ; the thoracic limbs rudi-
mentary or none; the abdominal leaf-like, except the first
pair; mandibles without palps. Apus, Limnadia, and their
allies have sessile eyes, and a shield-like (Apus) or bivalved
mantle. Apus has two closely set eyes, two pair of rudimental
antenne, and sixty pair of branchiferous feet, of which the
first is the largest ; the eleventh has two rounded valve-like
flaps for holding the eggs, close to the sexual orifice; the
seven hindmost abdominal joints have no limbs. Limnadia
has only 18-27 pair of legs.

The stalked-eyed forms have no mantle, eleven pair of
gill feet, and a post-abdomen of 6-9 joints, with two movable
end-lamellz, at whose base the female has an egg-pouch,
most are marine, Branchipus and Chirocephalus are freshwater.

Introduction to Animal Morphology. 351

Artemia lives in brine pools and salt lakes. Nebalia has a
secondary binocular larval stage.

Sub-class 5. Trilobite (Walch)—paleozoic, shield-like
forms of 6-20 somites, divided into three lobes by two longi-
tudinal grooves. Cephalothorax semicircular, with two
lateral compound eyes or none; between these is the
glabella ; outside them the gene; below the glabella is the
labium or hypostome; the middle lobe of the abdomen is
called rachis, the laterals pleure ; behind the abdominal seg-
ments is a post-abdomen whose rings are united, more or
less, into a pygidium ; the limbs are unknown; between the
eye and glabella is a depressed area, the fixed cheek, and
traces of the several component somites of the cephalothorax
are often present as imperfect transverse sutures or grooves.
‘The young was Naupliiform with unsegmented body. About
500 species are known, mostly Silurian.

CLERP PER SSE
CRUSTACEA.

SUB-CLASS 6. Poecilopoda (Zaérezdle )—heteronomously
segmented Crustacea, covered by two hard dorsal
shields, one behind the other, the front one being
convex forwards; eyes two, sessile, compound, far
apart, on the front shield; cornea unfacetted; six
pair of limbs around the mouth ambulatory, ending
in pincers in the females,* and with their basal joints
spinous, and acting as jaws; the five posterior pair
are lamellar, gill-bearing and natatory. Two ocelli lie
between the compound eyes; the pharyngeal nerve-
ring is wide, with transverse commissures ; the simple

* In the males the first (Limulus Polyphemus), or first and sceond pair
(L. Moluccanus), have but one claw at the end.

352 Introduction to Animal Morphology.

nerve cord forks posteriorly; there is a trigonal,
bayonet-shaped tail or telson ; the mouth has a small
labrum and a rudimental metastoma; the hinder
shield or operculum is hexagonal; the natatory feet
and tail are absent in the larva. The ambulatory
legs consist of—1st, a modified pair of antenne (the
front, short pair); 2nd, a pair of mandibles; 3rd and
4th, two pair of maxille; 5th and 6th, two pair of
maxillipedes. The third pair of thoracic limbs are
expanded, and united medially, forming a flat plate
over the five pair of swimming feet. The operculum
corresponds to the post-abdomen of the trilobite, and
has articulated to it six pair of marginal spines (post-
abdominal feet), while the tail is the appendix of the
last joint of the post-abdomen. The gills consist of
130-150 plates, like the leaves of a book, arising from
the outer part of the coxopodite of each limb, which
has, at its inner side, two lamellar terminal joints.
The male has a small cylindrical penis. They are
natives of the Moluccas and of N. America, and form
one genus, Limulus. ;

Perhaps to this group belong the paleozoic fossils,.
Pterygotus and Eurypterus, which have many free thoracico-
abdominal segments; eyes as in Limulus; mouth with a
broad metastoma; antennze one pair chelate; one pair of
broad maxillipedes serrated at their bases; free abdominal
_ somites, with no appendages.

Sub-class 7. Podophthalmia* (Zeach)—heterono-
mously segmented Crustaceans, with twenty somites,t

* This and the succeeding sub-class are known as Malacostraca
(Zatreille), to distinguish them from the foregoing or Entomostraca ; they
have always thirteen thoracico-abdominal somites.

t+ Twenty-one, according to those who reckon the telson as a.

somite.

Introduction to Animal Morphology. 353

with compound facetted eyes on movable stalks; the
three thoracic limbs modified into maxillipedes, and
respiration by special gills. The cephalogaster (head,
thorax and abdomen) is generally covered by a large
calcified dorsal shield of two parts, an anterior or
cephalostegite, often prolonged medially forwards into
a rostrum, a posterior or omostegite. The sex-opening
is at the ninth or eleventh post-oral somite, and all
the post-abdominal segments behind this have special
metameric shell rings. The antenne are unequal,
usually with divided filaments; the liver is consoli-
dated, arborescent; development with a long meta-
morphosis.

Two orders are included :—

Order 1. Decapoda (Laérez/le)—Crabs and Lobsters ; gills
lamellar, in a cavity under cover of the cephalo- and omoste-
gite, springing from the coxopodites of the hinder pair of
maxillipedes, and of the five pair of ambulatory legs.* The
oviduct opens at the base of the third, the male organ
at the base of the fifth pair of legs. The segments
of the head from before backwards bear the eyes, an-
tennules, antennz, mandible (with a 3-6 jointed palpt), and
two maxillz, respectively; the three thoracic segments bear
three pair of maxillipedes, which overlap each other. The
next pair is often large, with the hinder distal angle of the
propodite lengthened so as to be capable of opposing the
dactylopodite, so as to grasp objects when the latter is flexed
by its powerful muscles ; these are the pincers orchele. The
second and third pair of abdominal feet have generally much
smaller nippers. In all these the largest blade of the claw is
internal. The fourth and fifth pairs have non-prehensile
dactylopodites, and are usually seven-jointed. When the
post-abdominal segments are movable their limbs consist of

* The processes from which gills spring on the limbs are known as
epipodites.
T This is of use in directing food currents into the mouth.
2A

354 Introduction to Animal Morphology.

a basal protopodite, bearing an endo- and an exo-podite, the
latter of which, in the sixth or last post-abdominal segment is
transversely divided into two joints. This segment also bears
a flat terminal joint or telson, sometimes counted as a seventh
somite.* In Astacus it is divided by a transverse suture.

The heart is short, polygonal, suspended by 3-6 elastic
ale cordis. ‘The stomach is suspended by a muscular, partial
mesogastrium from the front of the sternum, and from the
base of the rostrum. ‘The latter fibres are inserted into the
cardiac ossiclet of the gizzard. In Macrura it lies directly
beneath the part of the omostegite over the anterior abdo-
minal segments, and behind the curved line on that shield
which marks the contact of these somites with the posterior
thoracic.

The gills are usually arranged in rows. In Macrura there
are three series, the external largest, consisting of the leaf-
like gills of the two hinder maxillipedest and four foremost
abdominal legs, the middle and inner of the branched gills
springing singly in the second maxillipede, and occasionally
from the last abdominal leg, and of pairs of similar gills at-
tached to the epimeral plates at the bases of the basipodites
of the intervening limbs. These organs are often much
divided. There are three sub-orders :—

1. Macrura (Za/ret//e)—post-abdomen as long as, or longer
than, the cephalothorax, with limbs on all its segments, the
last pairand telson expanded into a swimmer. The hinder
pair of maxillipedes do not conceal the others. The embryo,
before its maturity, has an exopodite on each of its ambulatory
legs, like those which remain on the two hinder pair of maxilli-
pedes.§ The omostegite is lengthened laterally into free,

* It is dorsal, and late in development, never bears limbs, nor a conti-
nuously calcified sternum, nor pleurz, and hence is probably not a somite.

+ The gizzard ossicles are—pyloric posteriorly, cardiac anteriorly, to the
sides of which are attached pterocardiac ossicles, and behind them supero-
lateral ossicles join these to the pyloric.

{ On whose outer plicated surface alone gill filaments are developed.

§ The presence of this on the hinder maxillipedes has led to the discri-
mination of these from the anterior; thus, in the nomenclature of Spence
ate the two maxille and first maxillipede are the first, second, and third

Introduction to Animal Morphology. 355

even-edged, hair-margined pleurz over the gills (dranchioste-
gites). The post-abdominal pleure have smooth surfaces
gliding on each other; those of the first and second overlap
the preceding segments, while those farther back are over-
lapped by the pleure in front. The brain arises from the
early fusion of six ganglia. The second maxilla has a spoon-
shaped epipodite ( flagellum, scaphognathite). A few develop
with very little metamorphosis, others begin life as Nauplii,
consisting of an anterior unsegmented part, with swimming
bristles behind (head and swimmeret), and as growth proceeds
intermediate parts form, producing a prosoma (thorax),
mesosoma (abdomen), and a metasoma (post-abdomen).
The following families are included :—1. Palinuride—Spiny
Lobsters ; pereiopods separated medially by a wide sternum ;
antenne long (Palinurus), or flat (Scyllarus). The ovum de-
velops from its nauplius stage into a Phyllosoma, or com-
pressed, transparent pyriform larva, with stalked eyes, a wide
cephalothorax, and a small segmented abdomen, with long
thin legs. 2. Astacidee—cephalothorax laterally compressed ;
post-abdomen flattened ; anterior pereiopods large, chelate ;
gills numerous. The larva in Astacus only differs from the
adult in the undeveloped tail; in Homarus in the presence
of exopodites on the pereiopods, and the absence of some of
the uropods. The freshwater Astacus differs from the marine
Homarus anatomically in having fewer gills, longer hepatic
ceca, a large undivided cecal remnant of the umbilical
vesicle, while Homarus has a smaller, bilobed sac; but it has
a dorsal, single, rectal cecum, which Astacus has not.
Homarus has also an undivided telson and a small rostrum.
Callianidea has respiratory appendages to the pleiopods.
Nephrops is often sold under the name of Prawn. 3. Caridide,
Shrimps—shell horny, flexible ; cephalothorax and abdomen
laterally compressed; sternum linear; gills few; their larve
have no cephalothorax nor post-abdominal legs; large

Siagonopods, while maxillipedes two and three are the first and second
Gnathopods. The ambulatory legs are called by him Pereiopfods, and the
post-abdominal Pleopods ; the hindmost three, when expanded, are
called Uropods.

2A 2.

356 Introduction to Animal Morphology.

maxillipedes and small gills. In Crangon the two pairs of
antenne are closely approximated. In Alpheus the inner
antenna is above the outer at origin, and the rostrum is small,
or large, serrated (Palemon). ‘Troglocaris, from the cave of
Adelsberg, is eyeless. Peneus, with small rostrum, has a
distinct nauplius stage.

S

Hippolyte Gordoniana.

Sub-order 2. Anomura (Jf. Edwards)—post-abdomen small,
nearly, or quite limbless, with soft terminal processes, not sunk
into a sternal hollow; pterygostomial regions isolated by a
suture from the cephalostegite; the fifth, or fourth and fifth,
pair of pereiopodsaborted; the last maxillipede large; the larva
is a Zoéa (see next order). The families are:—1. Hippidze—
witha long cephalothorax; and z. Lithodinide—withacrab-like
cephalothorax; both these have a hard-shelled post-abdomen.
3. Galatheide have large chele and a roundish (Porcellana)
or elongate (Galathea) cephalothorax, a moderate post-
abdomen, and tail-fin. 4. Paguride—hermit crabs, have un-
equal chele, round, soft, post-abdomen, with a terminal
sucker, imbedded plates, and 2-3 pair of soft, fin-like, rudi-
mental feet; they hide this part in the deserted shells of

Lntroduction to Animal Morphology. 357

Gasteropods. Coénobita is a terrestrial form, which, in the
West Indies, uses the shells of Bulimi. Pagurus is the
common hermit crab. Birgus latro, the tree crab, is said to
break open cocoa nuts.

Sub-order 3. Brachyura (La/éredlle) crabs—post-abdomen
short, compressed, turned up in a hollow of the sternum under
the cephalothorax, with no swimmeret on the last joint, and
thread-like pleiopods ; antenne short; the dorsal surface is
marked medially from before backward into gastric, genital, car-
diac and intestinal regions, laterally into hepatic and branchial:
the foremost pereiopod is chelate; the male post-abdomen
is narrow, lanceolate; the female broadly ovate; between it
and the sternum the eggs are carried in clusters; the fore--
most of the two rudimental pleiopods in the males is a clasper ;
in the female the same acts as a support organ for the gills,
which are 7-9 on each side; the nervous system is concen-
trated into a single peripharyngeal ring. The larva or Zoéa
is characterised by having a cephalothoracic shield with a
central spine, and a long post-abdomen without appendages.

The following families are included :—1. Catometopa—
cephalothorax four-angled; gills fewer than nine; male
sexual orifice sternal. Ocypode has a flagellum from the
ommatophore, continued past the eye, supposed to indicate
the relation of the stalk to a limb. Pinnotheres lives be-
tween the valves of molluscs. Thelphusa is a S. European
and N. African river crab. Gecarcinus, a W. Indian land
crab, has between its gill lamelle hard processes, which pre-
vent them closing, and allow in air. 2. Cyclometopa—cara-
pace oval, transversely elongate; gills nine; male sex-organs
in the hip-joint of the fifth pereiopod. Cancer, the edible
crab, has a serrated anterior edge. Portunus is rounded in
front, and toothed laterally; the fifth pereiopod is natatory.
Corystes is antero-posteriorly elongate. Carcinus has long
postero-lateral edges to its carapace. 3. Oxyhryncha, spider
crabs—carapace trigonal, pointed in front, an anterior pro-
boscis. 4. Dromiide—fifth pereiopod smaller than the others,
displaced dorsally ; gills fourteen. Dromia is covered with
brown hair. 5. Oxystomata—mouth triangular, not quadrate,
as in the foregoing, with a rostrum in front; gills often only

358 L[ntroduction to Animal Morphology.

six. The carapace is pyriform in Dorippe, semicircular in
Calappa, round in Matuta, globular in Leucosida, obversely
pear-shaped in Ranina.

Order 2. Stomapoda (Zamarck)—marine, with thin chi-
tinous shell; gills branched, free at the base of the pleiopods,
or none (Mysis), rarely on the cephalothoracic legs; the
hinder thoracic resemble the anterior abdominal legs; the
tail has a broad swimmeret attached to the last somite; de-
velopment is from a Zoéa. There are three families :—
1. Schizopoda—Omostegite reaching to the beginning of
the post-abdomen, and in front covering the antenne and
eye pedicles; outer antenne arising below the inner; all
legs sub-equal ; gills none (Mysis), or on all the eight thora-
cico-abdominal feet (Thysanopus). 2. Leuciferina—carapace
small, but reaching to the post-abdomen; in front of it isa
long head-process, on which the antenne, antennules, and
eyes are seated; the four hinder pair of limbs are sim-
ple, slender, and the post-abdomen linear. 3. Squillina—
long, with small cephalothoracic shield, leaving the front of
the head and the hinder abdominal rings free; gills on the
post-abdominal legs; the second pair of thoracic legs large,
its comb-like last joint shutting into a groove in the penulti-
mate joint, like a penknife blade; the heart is long.

CHAPTER tit:
SUB-CLASS 8.—EDRIOPTHALMIA (Leach).

SMALL, but not microscopic Crustacea, with twenty
body-somites, compound, sessile eyes, and rarely a
carapace. Four orders are included :—

1. Cumaces (A7véyer)—marine, uniting many of the cha-
racters of Schizopoda with those of Edriophthalms; the
short cephalothorax does not cover the hinder abdominal

Introduction to Animal Morphology. 359

rings; one gill only is attached to the first maxillipede, under
the pleura; there are no chele nor eyes; the inner antenne
are small, bicirrose, the outer large in the male, small in the
female; the limbs shorten from before backwards, the four
anterior in the males, and the first, or first and second in the
female, have swimming appendages ; the gills are simple ex-
pansions of the organs in Zoea, to which larval form this is
the nearest mature ally; the eggs are large and few, and the
larva emerges one-fourth the size of the mother.

2. Lemodipoda (Lafrezile\—post-abdomen rudimental,
with obsolete appendages ; head fused with the first thoracic
ring, so that the front feet appear to be jugular. There are five
pair of clawed feet, the third and fourth pair represented only
by membranous gills on the bisegmented abdomen; the
mandibles have no palps; the maxille are two-jointed. Two
families are included :—1. Cyamide, whale-lice—body flat,
oval; head small; upper antenne four-jointed ; gill vesicles
on the abdominal segments in the female utilized as egg-
bearers ; maxillipedes united into a labium, and bearing palps.
z. Caprellidze—body free, jointed, slender, with long three-
jointed antenne ; penultimate joints of the first and second
limbs thick; third and fourth absent; fifth, sixth, and seventh
pair long.

Order 3. Amphipoda (Zamarck)—head and _prothorax
united, covered by a horny shell; segments nearly homono-
mous, laterally compressed ; limbs seven pairs, two thoracic,
and five abdominal ; one pair of maxillipedes forming a lobate
under lip ; second and third pair of thoracic limbs prehensile ;
the four anterior abdominal are gill-bearing ; post-abdomen
with seven segments, and several feet with bristle appendages ;
the three hinder pair of abdominal feet are concave forwards,
the others are convex forwards, hence the name; stomach
with gizzard plates, and one or two pair of hepatic czeca; de-
velopment is without metamorphosis. In the egg there is
formed a larval membrane, separate from the chorion and
inner egg-membrane, the remains of the nauplius carapace,
which is lost at birth; a heap of cells extends from this to
the back of the embryo (micropyle apparatus of JZezssner),

360 Introduction to Animal Morphology.

the remains of the ancestral dorsal spine of the Zoea*. These
transformations take place in the egg, and the young has
assumed its adult form on its emergence.

Niphargus Kochianus ; Niphargus fontanus.

The families are :—1. Gammaride—head small ; antenne
many-jointed ; maxillee 4-5 jointed ; some (Ceraphis) build
nests of seaweed, &c., like Caddis cases, and most swim on
their sides. Orchestia and Talitrus, Sandhoppers, have short
antennules, and the third thoracic limbs chelate. Gammarus,

* The Ancestral Zoea was of the type of the Archizoea, whose descend-
ant is the pupa? stage of the Cirripede rather than the specialized Zoéa,
of the crab. The preceding Nauplius resemble that of the Copepod (the
Archinauplius).

Introduction to Animal Morphology. 361

the freshwater shrimp, has a large antennule and a mandi-
bular palp. Lysianassa has no prehensile feet. Chelura
terebrans bores into submerged timbers, 2. Hyperide—
marine, often of extraordinary shapes; head large, thick ;
antenne often rudimental; second maxilla three-jointed ; all
the limbs are prehensile, and the uropoda form a swimming
tail; the body is not bent as in Gammaridz, so they cannot
leap. Phronima has only one pair of antenne.

Order 4. Isopoda (La/éredile)—integument membranous,
rarely calcified ; segments nearly homonomous, dorsally com-
pressed ; the two hinder thoracic limbs and the five abdominal
legs equal, ambulatory; the post-abdominal feet lamellose ;
maxillipede forming a lower lip ; the intra-ovular Nauplius has
two trefoil-like side processes, representing the carapace,
spines and gills of Zoea, but on emission from the egg the larva
only differs from the adult by wanting the fifth abdominal
pair of legs; the embryo in the egg is ventrally turned, as in
Schizopods, not dorsally, as in Amphipods or most Decapods ;
the first thoracic segment is free from the head, except in
Praniza, where the three thoracic segments and head unite ;
the gills are attached to the pleiopoda, each of which has ex-
ternal to it an epipodial membrane, which is delicate and
respiratory in the aquatic, thick, tile-like protective in the
terrestrial forms ; the antennz are four; the eyes often close
together; the eggs are sometimes carried in brood-pouches
attached to the legs; there is a mandibular, but no maxillary
palp.

The following families are included :—1. Pranizidze—with
two large pair of antenne; head and thorax fused; last
pleiopod and telson forming a tail; ambulatory limbs five
pairs ; thoracic rudimental ; the young and the female Praniza
are suctorial and parasitic; the adult male is free, and has
been described under the name Anceus. 2. Bopyride—male
small, jointed ; female broad, eyeless, unsymmetrical, with no
mandibular palp, and a rudimental mouth ; parasitic on other
crustaceans (shrimps) ; males attached to the females, as in
Siphonostomata. Bopyrus has in the female lamellose pleio-
pods; Ione has branched threads; Liriope is parasitic on
the parasite Peltogaster; Cryptonisus is planaria-like, with

362 Introduction to Animal Morphology.

no segmentation, but has a segmented free-swimming young.
3. Cymothoide—feet (the three anterior pair in A®ga) with
claws; antennz large; maxillipede operculate; head small ;
mostly parasites on the gills of fish (Cymothoa), or free
(Serolis, &c.) The young Cymothoze are free-swimming.
Family 4. Sphaeromidze—broad, shield-like, littoral ; antennz
two pair, arising close together ; head large transversely ; legs
simple; front ring of post-abdomen rudimental, united to-
gether; a swimming tail in some; they can roll themselves
into a ball, except Cymodocea. Monolistra, from Adelsberg
cave, is blind. Family 5. Oniscidz (millepedes, slaters)—
under stones in damp, not wet, places; oval, with rudimental
or no antennules and mandibular palps ; flat maxillipedes ; feet
all equal, ambulatory ; post-abdomen six-jointed ; its last seg-
ment with the pleopods modified into lamellz or bristles ;
the foremost gill spaces have openings through their epipodial
opercula, leading into canals, which are a form of trachez
whereby air enters; the body is flatly compressed, not invo-
luble, in Oniscus and Porcellio, and pointed behind in Ligia.
Armadillo is more convex, capable of rolling into a ball, the
last pleiopod with a large (in Armadillidium a small) basal
joint. The recurrent nerve in Oniscus has an azygos ganglion
frontale, as in Insects and Myriopods. Family 6. Idoteide,
box slaters—body long, equally broad, cylindrical (Arcturus),
or compressed (Idotea) throughout, with a short antennule,
but no mandibular palp; post-abdomen with no posterior
tail process. Family 7. Asellida—body as in last, but witha
long posterior process on the shield-like hinder segment.
Asellus is the freshwater millepede. Limnoria terebrans de-
stroys submerged wood. The cylindrical Tanais has the first
and second thoracic rings fused to the head.

Introduction to Animal Morphology. 363

CHAPTER XLIiv.
DIVISION 2.—TRACHEOPNOA (Schmarda).

AIR-BREATHING Arthropods with one pair of antenna,
and either a cavity for the reception of air, or else a
system of tubes (trachez) conveying it through the
body. Three classes are included :—

Class 2. Arachnoidea (V. der Hoeven\—mostly ter-
restrial, with the head and thorax fused into a cepha-
lothorax, bearing four pair of limbs. The abdomen
is limbless, rarely with a post-abdomen, and the eyes
are simple. The mandibles (as such) are absent, but
their palps become developed in Scorpions as chele,
or food-graspers, and the antenne act as mandibles.
The maxillary palps become the first and second am-
bulatory legs, while the third and fourth pair are the
pro- and meso-thoracic limbs. Like Crustacea, they
often moult, and at that time lost parts are restored.
They do not part with their limbs as readily as Crus-
taceans, which, under circumstances of seizure or
fright, often voluntarily sever one oftheir legs between
the basi- and coxopodite.

The nervous system in the adult is concentrated,
with short commissures, or may be simplified by the
abortion of segments, as in Pycnogonide. In Scor-
pions the epipharyngeal ganglion is laterally con-
stricted, supplying the stemmata, and sending two
commissures to the limb-supplying hypopharyngeal
ganglion, which consists of seven fused ganglia, three
post-oral cephalic, three thoracic, and one abdominal :
behind it are three abdominal and four post-abdomi-

364 Introduction to Animal Morphology.

nal ganglia, the last of which sends two branches to
the end-claw of the tail.

Galeodes and Phrynus have two pharyngeal ganglia, from
the hinder of which two medio-ventral cords pass to the so-
mites, forming one posterior abdominal ganglion (often re-
presented by a commissure), and two ventral cords, with a
ventral ganglion. Pycnogonum and Tardigrades have four
nearly confluent ganglia in the ventral cord (more separate in
Nymphon). In Scorpions and Epeira a visceral nerve springs
from the brain, and passes along the cesophagus, on which it
forms a ganglion. In Opilio the visceral nerve comes from
the ventral ganglion, and forms many small ganglia. A simi-
lar nerve exists in many spiders.

There are no special organs of touch, of smell, nor
of hearing. The eyes consist of clusters of crystal
rods, largest in Lycosz, covered closely with a con-
vex corneal-lens. Pigment surrounds the cones in
spiders, sometimes forming a tapetum, and even a ring
or iris in front, around the surface of each cluster,
along the margin of the cornea lens: in this are im-
bedded circular muscular fibres in some _ species.
Scorpions have two large eyes close together, and
laterally a group of 2-7, smaller. In Spiders there
are eight in two rows. In Opilio there are three or
four. Pycnogonum has four; others have two, and
Pentastomum none. In some species of Trombidium
they are stalked. The skin is generally soft, sensi-
tive, never completely calcified, usually beset with
hairs or bristles, rarely with scales; sub-dermal glands
sometimes exist, as the two lateral organs of Adeno-
pleura. The muscles of the body are yellowish, and
remarkable vertical bands pass between the viscera,
which they hold in their place. These fibres can make

Introduction to Animal Morphology. 365

temporary depressions, which have been mistaken for
stigmata. The segments ofthe limbs are built on the
Crustacean type, but the full series of seven are rarely
developed. In some parasitic Mites the foot is dis-
coidal. Oribates has postero-lateral dermal folds, like
the mantle of Entomostraca, or the wings of Insects.
The mouth is often surrounded by a lip-like swell-
ing, and armed with the antennary jaws, which are
strong, hollow, with an opening on their inner side,
into which the duct of a poison gland (the homologue
of the shell gland of Crustaceans?) opens. In this
duct are spiral muscular fibres, which squeeze out the
poison. In Solpugide the first pair of
feet becomes masticatory or prehensile.
Salivary glands exist in the higher
forms. Two pair of lobed glands are
present in Scorpions, two convoluted
pouches in Galeodes, several pair of
small sacs in some Mites.* In Aca-
rines the mouth is suctorial. There is
rarely a pharynx, and the cesophagus
is narrow, thick, sometimes with a
chitin-lined longitudinal groove open- ee Shy LON hg
ing into the stomach, which is long, Spider: x, nervering

around oesophagus ;

with its anterior part (stomach proper) © ¢#ca from the sto-

mach; Z, liver ducts ;
elongated into ceca, which enter the %,losca, with tne
limbs. Such caeca are two, rudimen- ¢Ppnjns into it (out-
tal in Scorpions and Phrynide, five
pair in Spiders, entering the limbs and palpi. In

Mygale the hinder pair branch and anastomose. In

* It is not easy to unravel the connexion between the poison gland of
the antennz and the salivary glands in spiders, but they seem to be quite
separate.

366 Introduction to Animal Morphology.

Galeodes there are four, but the hinder send off lateral
ceca, and two pair bifurcate, so that six pair enter the
limbs and palps. In Pentastomum and Listrophorus
there are none. In Mites there are eight, often
branched, glandular ceca, in Phalangium as many
as thirty, in several rows. Usually these do not ex-
tend beyond the first or second joint of the limb; but
in Pycnogonum they stretch to the penultimate joint.
Sometimes in Spiders these ceca unite into a ring-
like stomach, extending backwards into the intestine,
which in Galeodes also has one or more ceca: the
rectum is globular in Spiders, or long, as in Scorpions.
The liver may be absent (Pycnogonide, Pentastomide),
or a granular envelope for the intestine (Ixodes,
Adenopleura), or short, slightly branched pouches
(Trombidium), or eighteen closely branched ceca in
two groups, one anterior and one posterior (Galeodes),*
ora large yellow-brown lobed organ with 2-3 (Spiders),
or 4-5 (Scorpions) ducts on each side. In the last case
it fills up a large part of the abdomen.

Opening into the rectum are, in Scorpions, simple
or slightly branched canals passing between the lobes
oftheliver. In Spiders these canals are much branched,
with two terminal ducts. In Phalangium and Acarus
they are tortuous, unbranched. These may be uri-
nary, homologous to the Malpighian tubes of Insects ;
they are absent in the Pseudarachne. Uric acid is
found in two gastric ceeca in Gamasus.

The fatty body is found in the abdomen of Mites
and Scorpions, but is replaced by the liver in some
Spiders. In Mites (Sarcoptes) it sometimes contains

* Kittary regards the hinder of these as renal.

Introduction to Animal Morphology. 367

uric acid concretions. In Scorpions the long, eight-
chambered, tubular heart lies in a pericardiac sinus,
suspended by alar ligaments or muscles, which help it
to dilate; into each chamber venous blood enters
through a pair of ostia protected by valves ; out of the
heart, in front and behind, pass arterial continuations
of the heart, the anterior aorta, to the cephalothorax
and limbs, the posterior to the abdomen ; lateral ar-
teries also arise from the heart. A supraspinal branch
of the anterior artery runs along and supplies the
nerve cord. Some organs seem to have capillaries,
but the colourless blood also enters the insterstitial
lacune, from whence it is collected in a sinus, and
distributed to the air vessels by lacune, with no
walls, and from thence it is poured into the pericar-
diac sinus.

Spiders have an abdominal heart, with three
pairs of ostia, but no pericardial sinus nor capillaries ;
the anterior aorta bifurcates into lateral branches; the
posterior ends abruptly by a free mouth. Pycnogo-
num has a two- (or three-) chambered heart, with two
pairs of ostia. Mites and Tardigrades are acardiac.

Respiration takes place by the dermis in many
Mites, but usually by tracheze, which are tubes placed
symmetrically, opening on the surface by lateral,
transversely oval holes (sézgmafa), and carrying air
into the interior of the body. These tubes consist of
a connective basis, continuous with the dermis, lined
by a chitinous cuticle, which, by its elasticity, keeps
the tube open. When well developed, this lining
thickens into a spirally-coiled thread, here and there
interrupted by the sacculation of the tube. The stig-
mata are surrounded by chitinous rings, and usually

368 Introduction to Animal Morphology.

protected by circles of hairs, and sometimes have
valves moved by muscles. The tracheze branch and
end in a network around the viscera ; sometimes large
branches coalesce, making longitudinal or transverse
air channels through the whole body. In Arachnida
the trachee are usually incomplete, and only in limited
regions of the body. Their branches are usually fas-
ciculate. Trombidium has one pair, as has Phalan-
gium, in which they are freely branched. In Galeodes
there are three pair. In the short dilated trachee of
some, the lining membrane is dilated into many (60-
100 in Scorpions) book-leaf-like plates, whose inter-
spaces receive air from the stigmata; these are called
tracheal-lungs, but they are only closely compressed
trachez with the lumina of their tubes flattened. Many
intervening gradational forms exist. Ofthese, one or
two (Mygale) pair exist in Spiders; two pair in Phry-
nidz ; four pair in Scorpions, in the four anterior ab-
dominal segments. In others a pair of trachee, with
no spiral thread nor branches, co-exist.

Beside the poison gland of the antennary jaws,
and the lateral glands of Adenopleura, there is a pair
of tail glands in the Scorpion, opening at the base of
the tail claw. The spinning gland of the spider con-
sists of several pair of abdominal glands, opening on
the flat spinning field, or an eminence below the anus,
by ducts which can be opened or closed at will, these
secrete a material which, when extended and exposed
to the air, becomes chitinoid. There may be two
(Mygale), three (most genera), four(Drassus, Clubione)
pair of spinning warts, on each of which many (400 in
Tegenaria, 100 in Segestria, 1000 in Epeira) ducts
open, hence each thread consists of hundreds of

Introduction to Animal Morpholozy. 369

strands. The material is extruded suddenly and in
large quantity, especially when the female lays
eggs; the material is arranged by the comb-like
claws.

All but Tardigrades are dicecious; the testes are
single or clustered ceeca. The vasa deferentia open
far from the anus, at the base of the abdomen, between
the stigmata, and in this bilateral termination they
resemble the Chilognaths. Accessory saccular glands
secrete the adhesive material which makes sperma-
phores. The only intromittent organs are the wart-
like processes in Scorpions, the protrusible penis of
(Phalangium), which corresponds to the ovipositor of
the female, and has two large branching bristles at
its end, the double spiculum of Pentastoma, or the
single one ofsome mites. In male spiders the spoon
shaped last joint of the maxillary palp places the
spermaphores in the female vulva. The ovary is tubu-
lar, with grape-like eggs on a central rachis, or rarely
in a ring round it (Phalangium, some Mites). In
Scorpions (which, like Phrynus, are oviparous) the
ovary consists of three azygous communicating tubes.
In Phalangium the two oviducts unite, and a duct
passes to the protrusible ovipositor ; a similar organ
present in some Mites. Parthenogenesis is described
in Cheiletus. Tardigrades have a median epi-intestinal
ovary, two lateral testes, each with one vas deferens
and a common receptaculum seminis. In Galeodes
there are two ovaries, as in Spiders. Many Mites
have an imperfectly annular ovary, and Pentastoma
has a long ovary ending in two oviducts united by an
annular canal. From thence comes a single canal
dilated into a uterus, which ends at the vulva. Where

2B

370 Introduction to Animal Morphology.

this arises from the ring are two receptacula seminis.
In males the testes also end in a ring vessel.

In Pycnogonide the sex-glands have no ducts,
but their secretions are emptied into the body cavity,
from whence they escape by openings at the bases of
all, or one pair of legs.

Development begins, except in Pseudarachna, by
a partial segmentation of the yelk, and the formation
of a primitive streak at the ventral side of the embryo;
the young early assume their adult form ; many mites
are at first hexapod, until after several moults. The
young Pycnogonum has an unjointed body, and two
or three pair of two- or three-jointed legs. Pentasto-
mum retrogrades in development. The embryo of
Ixodes and of scorpions possess the Micropyle appa-
ratus of Aezssner, indicating their relationship to
Archizoea.

Arachnida are divisible into two sub-classes :—

Sub-class 1. Pseudarachna (aecke/)—retrograded forms,
with complete yelk-division; no trachez, liver, nor renal
tubes; a small epipharyngeal ganglion and a ventral cord of
four approximated ganglia. The orders included are dissi-
milar.

Order 1. Pantopoda (Burmeister)—marine or littoral; in-
tegument chitinous ; abdomen rudimental, peg-like, unjointed ;
cephalothorax four-jointed, bearing four pair of long 7-9
jointed, claw-bearing legs; rarely shorter (Zetes) ; usually as
long as, or longer than, the body; antennary jaws sharp or
none (Pycnogonum); mandibular palp 4-5 jointed (Nymphon),
or none (Pycnogonum); ocelli four on a frontal ridge. The
narrow cesophagus has three flat, bristled ridges ; the stomach
five pair of long glandular czca, the front, short pair stretch-
ing into the antennary jaws; the testes open at the end of
the first or second joint of the divided meropodite, in which
the gland lies; the ovaries lie in the same segment, and open

Introduction to Animal Morphology. 371

at the base of the coxopodite, where there are accessory legs
for attaching the ova. There is one family, Pycnogonide, and
seven genera; some are fish-parasites.

Order z. Tardigrada (Duwjardin)—hermaphrodite, minute,
worm-like, acardiac, with soft skin; cephalothorax and ab-
domen fused; four obscure metameres, and four pair of short
legs, rudimental, each with three or four curved claws; the
last pair of legs terminal; mouth suctorial, on a fleshy tube,
with two salivary glands, and the antennary jaws forming two
piercers, with protrusor and retractor muscles; cesophagus
gizzard-like; stomach large, with many grape-like ceca;
ocelli two; the single ovary and the lateral testes open into
the cloaca; ventral ganglia are further apart than in the last
order. They live in damp moss and gutters, and can bear
drying with impunity, like Rotifers. They lay a few large
eggs during the moulting process, and the slough acts as
an egg sac. ‘There is one family Arctisca. Macrobiotus has
no palps or bristles. Echiniscus has marginal bristles. Mil-
nesium is palpate, but with no bristles. Emydium has
both.

Sub-class 2. Autarachna (aeckel)—true Arachnids, with a
developed abdomen, rarely undergoing retrogression, usually
with respiratory and excretory organs, and ova with partly
cleaving yelk. Three orders are included :—-

Order 1. Acarina—soft-skinned, with unsegmented abdo-
men, united to the cephalothorax ; ocelli none or two, rarely
more ; respiration tracheal or dermal; mouth either mastica-
tory, with claw-like antennary jaws, or suctorial, the rostrum
or sucking tube being the united pair of mandibular palps,
containing the stilet-like antennary jaws; ventral cord, with
one ganglion; anus ventral; legs four pair, each with two
end-claws; digestive canal simple, or with czeca, which are
often bifurcate at their end, sometimes all directed forwards.
There is no heart nor separate liver (except the grape-like
ceca in Trombidium, &c.). The trachee have often few
branches or none, no spiral thread, and one pair of stigmata
at the bases of the antennary jaws, or of the third or fourth
limb-pair. The sexual opening is simple, preanal, often farfor-
ward, and the oviduct is often widened into auterus. The vas

2B 2

372 Introduction to Animal Morphology.

deferens may have accessory glands (three pair in Argas). The
young are generally hexapod. Eight families are included:
1. Pentastomidz—nearly colorless, worm-like endoparasites
from the internal cavity of Vertebrates, with a long annulated
body ; beginning life as an ovate embryo with two pairs of
short, two-jointed, two-clawed feet; mouth with two hook-like
antennary jaws ; this larva becomes pyriform, a tail forming,
with terminal bristles, and after a few moults the hooks are
lost, and are followed by others which form an anterior series,
two on each side of the mouth. The worm-like adult has a
simple digestive tube, with villiferous ridges internally anda
terminal anus. The mouth has a chitinous ring and a pair of
small salivary glands. The testis is single, sub-gastric at
the anterior one-third of the body; the two vasa deferentia
are united at their origin, each passes forwards convoluted,
and ends ina long penis, coiled when at rest, and included in
a sac projecting near the anterior end. The ovary is long,
simple, over the stomach, with its oviducts opening anteriorly
into a sac, beside the pharyngeal ganglion, which communi-
cates with a pair of large oval lateral receptacula seminis ;
from this sac one or two vagine pass backwards, opening
preanally. There are stigma-like pits, but no trachee. There
is one family and genus. P. tenioides inhabit the nostrils,
&c., of dogs; P. imperatoris and proboscideum, the lungs of
the boa, &c. They are the only Arthropods with a continu-
ous clothing of longitudinal muscular fibres, which, like the
muscles of the intestine, are striped. There is an cesophageal
nerve ring. ‘The larve of some are encysted in the liver of
the hare, &c. P. constrictum has been found in the human
liver. 2. Acaridz, Mites—minute, oval or elongate, with soft
body and chitinous supports for the short legs, which have
each two claws, and often an adhesive disk ; mouth mandibu-
late or suctorial; ocelli and trachez none; often parasitic.
Demodex, from the human sebaceous follicles, has a worm-
like, unringed abdomen. Sarcoptes, the itch insect, has an
oval, undivided body, and the feet all (in the males), or the
foremost two pair (females), with suckers; the back bears.
conical processes, and the male has three testes and a spicu-
lum. Acarus, the cheese and flour mites, have scissors-like

\

Introduction to Animal Morphology. 373

antennary jaws. Glyciphagus lives on feathers, &c. Dermato-
dectes on horses, sheep, &c. 3. Ixodidz (ticks)—body leathery
or horny, extensile, antennary feet piercers, with recurved
hooks ; palps 3-9, jointed, in I. Gervaisii with a sucker on the
last joint; legs two-clawed ; eyes two or none. ‘They live in
bushes, and attach themselves to passing animals, whose blood
they suck, whereupon their bodies swell immensely. The first
pair of maxillz, at their bases, form a kind of underlip, ring-like
below. The sex-openings are far forward. Argas has a rough
dorsal surface and two terminal hooks on the antennary feet.
Ixodes is smooth, dorsally, with (Hyalomma) or without eyes
(Amblyomma). Adenopleura, from the pangolin, has a flat-
tened body, a serrated hinder margin, and two lateral glandu-
lar sacs. The claws have an oval cushion or caruncle at their
base. The dorsal integument is covered with closely undu-
lated ridges. 4. Gamaside, Spider mites—eyeless ; feet
equal, hairy, two-clawed, and with a sucking disk ; antennary
jaws scissors-like; palps free, the joints equally long; body
undivided; parasitic on beetles (Gamasus), reptiles, and
birds (Dermanyssus), but not fastened by a piercing beak.
Pteroptus with a long end-joint to the palp; lives on bats.
5. Oribatide—viviparous, grass and wood mites, hard and
horny, cracking like glass when pressed ; antennary jaws, re-
tractile; no ocelli; feet with 1-3 claws; back shield often
with wing-like lateral folds and two suckers at the bor-
der of the cephalothorax; palps four-jointed. Nothrus
has a four-angled body, and thick three-clawed legs; Phy-
toptus lives on vine leaves; Leiosoma, Hoplophora, &c., on
other vegetables. 6. Hydrachnide, Water-mites—legs often
finely bristled; body undivided; eyes two; antennary jaws
claw-like (Atax), or sharp-pointed, needle-like (Hydrachna), or
bristle-like (Limnochares) ; palps short, bristled or hooked at
the end. The young are suctorial; parasitic on water insects.
Pontarachna is marine. 7. Trombidide—soft, brightly co-
lored, undivided; ocelli four (Erythrzus), or two (Tetrany-
chus); antennary jaws, claw- (Trombidium), or needle-like
(Tetranychus) ; palps scissors-like. ‘Trombidium is parasitic
on Aphides, &c. Tetranychus telarius secretes a web on the
leaves of lime-trees. 8. Bdellide—brightly colored; body

374 Introduction to Animal Morphology.

constricted at the origin of the first pair of limbs, and also
behind the head; ocelli 2-6; legs equal; long, thin, with
separate claw-joints, living in damp earth.

Orderz. Araneina, Spiders—having the unjointed cephalo-
thorax and the saccular abdomen united by a narrow pe-
duncle; breathing by tracheal lungs and trachez; mouth
masticatory, rarely with no labium (Aphantocheilus); anten-
nary jaws pierced by the poison duct; eyes 6-8; spin-
ning warts posterior, rarely only two (Stenochilus Hobsoni);
stomach annular, surrounded by the voluminous liver. There
are usually two trachez behind the tracheal lungs, and the
sex-openings are between the lung stigmata. The non-
chelate palps are simple in the female, but in the male they
are swollen at the tip and grooved beneath, and have several
hook-like appendages ; by these the spermaphores are placed
in the female vulva. They are predaceous, with often comb-
like paired claws, and undergo no metamorphosis, but moult
frequently. There are two Sub-orders:—1. Tetrapneumones
(Latreille)—with four lungs and stigmata, and four spinne-
rets, of which two are small; ocelli eight, close together ;
large spiders, forming one family, Mygalide, with long,
foot-like palps, with two end claws; many of them dig bur-
rows, which they line with web-material, and for which they
form a lid fastened by a silken hinge (Cteniza, Atypus, &c.).
Mygale, with down-directed antennary jaws and screw-like
copulatory palp, is said to attack small birds. Sub-order 2.
Dipneumones (La/rez//e)—lungs two ; stigmata two or four; in
the latter case, as in Segestria, Dysdera, &c., the hinder pair
open into trachez; spinnerets three pair; antennary jaws,
with indirected claws; ocelli scattered. The families are:
1. Araneide—sedentary web-spinners, with ocelli in two
transverse rows: some are tube- or flask-spinners (§ Tubi-
tele), having the second and third pair of legs shorter than
the first and last. Dysdera has four eyes in the first row,
two in the second. Nops has but two eyes. Segestria has
three rows, each of two eyes. Drassus has eight unequal eyes.
Clubiona has eight eyes, of which the four hinder and two
extreme of the front row form a crescent. Argyroneta (the
water-spider) has straight rows, Tegenaria (the house-spider)

Introduction to Animal Morphology. 375

two slightly curved rows of ocelli. Some (§Orbitelz) spin
geometrical webs, in whose middle they lurk; their first and
second pairs of legs are longer than the fourth, and they have
eight ocelli either in two transverse lines (Tetragnatha), or
the four medial in a square, and the lateral on the edge of
the cephalothorax (Epeira). Gasteracantha, Mithras, and
Acrosoma (S. American), have the abdomen very broad, and
often with long lateral horns. Other Spiders are either La-
terigradz, spinning single threads, living in web-united clus-
ters of leaves, and moving sideways (Thomisus), or else
Inequitele, resembling Thomisus in having the first pair of
legs the longest, but spinning irregular webs, whose threads
cross each other in inconstant directions, as in Pholcus, which
has its outer, or Theridion, which has its inner, ocelli the
largest. Family z. Lycoside—wandering or hunting Spiders,
spinning no webs, but the females carrying egg-sacs; ocelli
in three rows ; some have a cephalothorax narrowing in front,
with the second (Dolomedes), or fourth (Lycosa, the Taran-
tula) pair of legs the longest. Others have a square cephalo-
thorax, and leap on their prey (Salticus, Eresus). Myrmecia
is ant-like in shape.

Order 3. Arthrogastra” (Gerstaecker)—abdomen sessile,
segmented ; mandibular palps developed as pincers or chel?-
cere. ‘They are divided into five Sub-orders, each containing
a single family.

1. Phalangita (Gerst.) Opilonidea (Harvest-men)—short-
bodied; abdomen thick, transversely folded, or six-jointed ;
cephalothorax unsegmented ; respiration tracheal; chelicere
three-jointed, with no poison gland ; ocelli two (the so-called
hinder pair are said by Krohn to be gland sacs); third and
fourth feet two-clawed; first and second, one-clawed. The
female has an ovipositor. Hermaphrodites have been found
producing small ova in the lobes of the testis. They hunt
their prey. Cyphophthalmus is a blind cave-dweller, with
eight abdominal rings. The hind legs are often, in S. Ame-
rican forms, large and curiously bent (Gonyleptes). Trogu-
lus and Phalangium are European.

z. Pseudoscorpiones (ZLa/rezl/e)—small, flattened, cylindri-
cal, or pear-shaped ; abdomen eleven-jointed, with spinning

376 Introduction to Animal Morphology.

glands; rudimentary, membranous antennary jaws, but large
chelicerous mandibular palps; they have a coiled intestine
and trachez; ocelli z-4 (Obisium). Chelifer has a groove
on the cephalothorax, and is common in old books, on flies,
&c.

3. Scorpiodea (Gerstaecker) —cephalothorax unjointed ;
abdomen of seven segments, with a six-jointed post-abdomen ;
mandibular palps as very large chelicera, with the inner angle
of the propodite elongated, to meet the dactylopodite; an-
tennary jaws also claw-like; respiration is by tracheal lungs,
with four stigmata on the ventral side of the third to sixth
abdominal ring, surrounded by raised edges or perctremes.
The last body-segment is narrow, cylindrical, with a terminal
perforate claw and poison-gland; a pair of comb-like ap-
pendages (modified legs ?), with down-directed teeth, lie at
the base of the abdomen behind the last pair of legs; these
are supposed to act in copulation (in the male) and oviposi-
tion (in the female). The males have more teeth in these
combs than the females; they also have a longer post-
abdomen and flatter claws. They are viviparous, and produce
20-60 at once. Heterometrus afer reaches six inches in length.

Sub-order 4. Pedipalpi (Za/rezl/e)—spider-like, with a ter-
minal claw on each two-jointed maxillary palp ; mandibular
palps with unequally long chele, not capable of closure, as
the angle of the propodite is not sufficiently prolonged ; eyes
eight ; abdomen with 11-12 segments, and no post-abdomen,
and four tracheal-lungs on the second and third abdominal
rings. Phrynus is viviparous. The abdomen and thorax are
more distinct than in true scorpions. ‘There is no comb-like
appendix, nor poison apparatus. ‘Thelyphonus has the three
hindmost joints of the body slender, ending in a long-jointed
tail process, and has an oval cephalothorax. Phrynus has
leg-like chelee and no tail. Nyctalops has a divided cepha-
lothorax, the first segment elongate, bearing the two anterior
pair of legs; the hinder smaller.

Sub-order 5. Galeodea—cephalothorax four-jointed ; ab-
domen long, ten-ringed ; antennary jaws scissors-like, with no
poison-gland, but a vesicular dilatation at base; tracheal
stigmata on the second and third joint; an abundant hair

Introduction to Animal Morphology. 377

clothing, &c.; the leg-like maxillary and mandibular palps
have no claws. Sternum broad, with a mesial groove ; legs
with two long claws each; ocelli one pair; crescentic stalked
processes arise at the origin of the hindmost pair of legs,
which may be homologous to the combs of the scorpions.
Galeodes (Solpuga) inhabits S. Europe and Asia.

CHAPTER XLV.
CLASS 3.—MYRIOPODA (Gerstaccker).*

ARTHROPODS with a distinct head, one pair of an-
tenne, trachea, and a long cylindrical or flattened
body of 9-160, nearly homonomous, limb-bearing
somites. Each metamere has a ring of chitinous or
calcified (Julus) integument (Chilopoda), or the rings
of each pair of segments are confluent, or the rings
may be only partially chitinized as dorsal, or dorsal
and ventral plates. The subulate or filiform seven-
or many-jointed antenne arise under, rarely over,
the frontal plate, and have many single or clustered
sensory-rods. The mouth is ventral, surrounded by a
lip. The hook-like mandible bears a movable palp
on the chewing surface. Both pair of maxillee may
unite mesially to form a lower lip (Chilognatha), or
the second pair alone may unite (Chilopoda), or may
be absent. There is no distinct maxillary palp. The
ventral ganglia are paired, homonomous, 8-16 (Litho-
bius), 22 (Scolopendra), 140 (Geophilus), united by
commissures; there are two epipharyngeal ganglia
joined by a commissure, and giving off optic and

* Myriapoda of Leach and older writers.

378 Introduction to Animal Morphology.

antennary nerves. The ganglia of the post-oral head
segments unite into a hypopharyngeal ganglion in
front of the ventral cord. In Iulus the ventral ganglia
are confluent, so the entire cord has a coating of gan-
glion cells. A visceral nerve from the epipharyngeal
ganglion unites with its fellow on the cesophagus,
forming a ganglion, from which an azygous branch
passes backwards, forming visceral ganglia, commu-
nicating with lateral cesophageal branches from the
brain ganglion also. Other visceral twigs arise from
the ventral ganglia. A delicate peritoneal layer, con-
taining transverse muscular bands, keeps the ventral
cord in its place, and in the fatty, concretion-holding
body, at each side of it, is a longitudinal blood sinus.
In Polydesmus, branches seem to arise from the com-
missures. There are no otocysts. The eyes may be
compound, with a facetted cornea (Scutigera), or
simple, in one or two rows, or in a cluster on the
upper or lateral part of the head; rarely absent. The
optic nerve has a special ganglion.

The cesophagus is narrow, with one pair of simple
(Iulus), lobed (Lithobius), or three pair of grape-like
salivary glands (Scolopendra) ; the stomach is cylindri-
cal : the intestine straight, often dilated, or convoluted
(Glomeris), with a posterior anus; the gastric gland-
cells may be hepatic, as there is no other liver; the
urinary tubes are tortuous, thread-like, two (Iulus) or
four (Scolopendra), like those of insect-larvee, opening
into the rectum.

The heart is long, with a chamber for each seg-
ment,* separated from its fellows by valves, and with

* Not always. In Iulus, although this was the embryonic condition,

they unite in pairs, so each chamber giving off two pair of branches, in
each segment.

Introduction to Animal Morphology. 379

a lateral row of venous ostia; it is kept in its place
by triangular musculi alares attached to the body wall,
and gives off from each chamber a pair of arteries for
each somite. The front chamber sends off medially a
cephalic branch, and on each side a branch which
surrounds the cesophagus as a pair of rings, which
uniting form the large blood sinus that accompanies
the ventral nerve cord (thus like the arrangement in
the Scorpion). There is no venous nor capillary
system, nor a pericardial sinus, but the blood flows
in lacune and perivisceral spaces.

The paired trachez open ventrally or laterally,
and may be equal to (Geophilus), or fewer than
(Scolopendra), the number of segments. In Iulus a
bundle ofsimpleor slightly branched non-anastomosing
tubes passes from each stigma; in Glomeris they are
branched ; in Scolopendra they have free longitudinal
and transverse anastomoses ; in Lithobius and Scolo-
pendra, stigma-bearing and stigma-less segments
alternate.

Scattered on the surface are often, pear-shaped
glands, secreting a brown, corrosive fluid, with a very
disagreeable smell, opening by dorsal pores (foramina
repugnatoria). The thorax and abdomen are not
differentiated, and each segment bears ventrally, either
near the middle line or laterally, 1-2 pair of 6-7
jointed legs, which on all segments are alike, with
single or double end-claws.

They are dicecious, oviparous. The whole yelk
cleaves, and the food yelk lies outside the wall of the
alimentary canal, between it and the integument. The
ovary is either a single pouch, with a single or double
oviduct, or is double (Craspedosoma), united anteriorly,

380 Introduction to Animal Morphology.

but with two oviducts opening separately. Opening
into the vulva, rarely into the oviduct, are two stalked
receptacula seminis and a pair of cement glands,
whereby the eggs are stuck together. The testes are
double (Iulidz, Glomeris) or single, with, in the former
case, one vas deferens between them ; in the latter a
series of lateral pouches communicates with a central
convoluted vas deferens, which dilates or divides into
two, which either open separately on small papille, or
again unite, and form a small penis; 1-3 pair of ac-
cessory glands, for the secretion of adhesive matter to
make spermaphores, are appended to the end of the
vas, as well as vesicule seminales. The females are
larger than the males. The genital openings are
posterior in Scolopendra, or between the second and
third body ring in Chilognatha, in which sometimes
the male has a double spiculum on the seventh seg-
ment, which carries the spermaphores from the opening
of the vas to the female vulva. The ova are laid in
the ground, and in development form two germ-
layers, an outer xeuro-cpithelial, and an inner, which
divides into many protovertebra-like bodies, giving
rise to the muscular and other systems. The primary
neural region in the egg is concave, and the embryo
is invested with a structureless larval skin, like that of
Crustaceans and Acari. The larve are apodous or
hexapod, and the number of legs increases at every
moult, and the eyes and antenne afterwards develop ;
the terminal rings are the first developed, then the in-
termediate. Some Scolopendra are viviparous. The
bite of some is poisonous, as the foot-jaws have a
poison-gland. They are largest in the tropics.

Introduction to Animal Morphology. 381

There are three orders :—

Order 1. Chilognatha (Za/rezlle\—cylindrical, or semi-
cylindrical, with two pair of legs on every segment after the
fifth or sixth; thoracic rings with free dorsal plates; each
segment has a stigma in front of the articulation of each leg;
often very small, except in Polydesmus ; the genital orifice is
between the second and third ring, the latter of which has no
legs; the small antennz consist of seven joints, the last
often hidden in the sixth; the’coxopodites of the first pair of
legs are directed forwards, and partly unite to form a labium.
In development new segments arise between the third last
and second last segment of the hexapod larva. The number
of somites is not always specifically constant, and the shell
of each joint is either a ring or half ring, in Glomeris allow-
ing the body to be rolled into a ball; sometimes the ventral
plates are divided, and extended laterally as laminz pleurales.
The first thoracic ring has no limb in Polydesmus, and when
the seventh ring bears the penis it has no limb. In Iulus the
two testes are united by transverse anastomoses; on each
side of the back on all (Iulus, Polyzonium), or some seg-
ments (Polydesmus), are foramina repugnatoria.

Three families are included :—1. Glomeride—wood-
louse-like, short, concave below, semicylindrical, with either
twelve segments and seventeen pair of legs (Glomeris), or
thirteen segments and twenty pair of legs (Sphzrotherium) ;
each ring has one dorsal and four ventral plates, the lateral
of which (laminz pleurales) articulate with the legs; the first
ring is small, covered by the second, the last is shield-like ;
the spicula are pre-anal, placed far back. 2. Iulide—cylin-
drical ; ventral and dorsal plates united in a suture; head large,
free; first thoracic ring not covered by the second; last ring
compressed, with an anal slit. The eyeless Polydesmus and
Strongylosoma have twenty rings; Polyxenus has nine. They
have also a sternal space between the origin of the legs, and
a lateral plate, or ridge, or bundle of hairs. Iulus has fifty,
Lysiopetalum forty-five rings, and the limb-pairs medially in
contact. Spirobolus reaches a length of nine inches. 3. Si-
phonizantia—bodies semi-cylindrical, capable of being spi-
rally rolled up; head small, hidden under the first body ring ;

382 Introduction to Animal Morphology.

mouth prolonged into a sucking tube; the body covers the
limbs; surface smooth (Polyzonium), or rough, and 70-, 80-
jointed (Siphonophora).

Order 2. Chilopoda (Lafreille)—somites flattened, each
with a dorsal and ventral plate, and not more than one pair
of limbs; antennze of more than fourteen joints; generative
organs posterior. The third thoracic ring has a free dorsal
plate; so has the second in Lithobius and Geophilus; penis
none; stigmata lateral; the first and second pair of legs con-
verted into foot-jaws, the hinder of which is perforated by the
poison-duct, and claw-like; the stigma pairs are fewer than
the somites. The larve may have 6-8 pair of legs, and new
segments arise between each pair of their predecessors. ‘The
mandibles are weak, with rudimental palps. The last pair of
legs are often turned directly backwards. There are two
families. 1. Cermatiide—antenne bristle-like, longer than
the body; limbs long, especially the last pair; those of the
first thoracic ring palp-like, with no end claw; stigmata in
the middle line of the back, ex. Scutigera. 2. Scolopendridz
—antennz subulate, shorter than the body; eyes never com-
pound ; stigmata lateral. The antenne are polyarthrous,
bristle-shaped in Lithobius, or fourteen- (Geophilus), seven-
teen- (Cryptops), nineteen- (Eucorybas), or 18-, 20-jointed
(Scolopendra) ; the ocelli are usually four, and the body seg-
ments unequal (Scolopendra, &c.), or equal, as in the blind
Cryptops and Geophilus. Heterostoma has large, sieve-like -
stigmata. Arthronomalus electricus is phosphorescent.

Order 3. Pauropoda (Zudbock)—minute (5” long), white,
with no trachee; ten somites sparsely setose; generative
organs anterior; legs nine pairs, of which one is on the third,
and two pair on each of the fourth, fifth, sixth, and seventh
segments. The head has no foot jaws; the antenne are five-
jointed, bifid, with three long, many-jointed appendages ; the
larva is hexapodal; dorsal plates, like those of Chilopoda.
This includes one genus. Found in decaying leaves in tem-
perate climates.

Introduction to Animal Morphology. 383

CHAPTER XLVI.
CLASS 4.—INSECTA (Latrezlle).

ARTHROPODS segmented into head,* thorax, and ab-
domen ; the first, like that of a myriopod, of six fused
somites ; the thorax consists of three, pro-, meso-, and
meta-thorax, each of which bears a pair of legs; the
abdomen is of 7-11, usually nine somites,f limbless in
the adult. Respiration is tracheal. Life is usually
limited to one period of sexual maturity, and develop-
ment is generally attended with metamorphosis.

The adult integument is usually chitinous, with
hairs, bristles, or scales (calcified in the larva of Stra-
tiomys), often with unicellular glands opening into
the cuticular pore-canals, or into hairs whose tips
must be broken before the secretion is emptied, or
into the intermetameric spaces. In some insects are
clustered glands secreting wax. In Aphides and
those Coccida that secrete wax-threads, they occupy
large surface-areas. In bees these glands, opening
by many ducts, masses of gland-cells, trachez, and a
covering layer of fat, make up, on front of the ventral
rings, the “‘wax-organ.’’ Aphides have also surface
honey-glands. Some dermal gland-cells are phos-
phorescent, and odoriferous glands are often seated at
the bases of the limbs, or intermetamerically, or around
the anus. The products of these are often emptied

* Some Coccina have the prothorax and head united.

f Eleven, the normal number, only present in Orthoptera. Two are
most commonly aborted or indistinct. Of these, strictly, eight are abdo-
minal and three post-abdominal.

384 Introduction to Animal Morphology.

as a sudden shower. Many larve have spinning
glands, early or late in development, as gland pouches
on the upper lip: these secrete threads, often around
sticks or foreign bodies (Oiketicus). Some Hymenop-
tera have a caudal sting. The colors of insects are
in the chitinous layer.

The head bears the compound eyes, between and
in front of which is the faczes, consisting of the inter-
ocular region, /vozs, and an anterior segment or cly-
peus; beneath the mouth is the gwz/a; on each side
are the gene; behind the facies is the occzpu¢t, which
joins the frons at the vertex, and is attached to the
prothorax by the neck. The head may be received
into an anterior notch in the thorax (caput recepiumnt),
or concealed by the thorax (c. ob¢ectum), or free (c. le-
berum). The single pair of antenne arise below the
eyes, and may be clavate, capitate, dentate, pectinate,
flabellate, geniculate, aristate, &c.; between these
may be ocelli or single eyes. The head also carries
the oral organs, which consist of an azygous upper
lip (¢abcum), movably jointed to the clypeus; laterally
there are, first, a pair of biting mandibles, hinged, and
moving like a pair of tongs, never palpiferous nor
jointed ; each has two condyles at base for articula-
tion with the inner wall of the gena. Behind these
are the maxille, usually more delicate than the former,
and consisting of a transverse basis articulated to the
gula (cardo); on this is placed a stzfes, which, on a
separate portion, or sguwama, bears a maxillary palp.
Internal to the stipes projects the mala or lamuzna,
often divided into external and internal. Still farther
back are the second pair of maxille, rarely remaining
separate, usually united mesially as a lower lip

Introduction to Animal Morphology. 385

(abeum), sometimes palpiferous. The united cardines
of this pair of maxille form the chin or mentum, in
front of which a tongue or ligula may be formed by
the union of stzfes, sguama, and mala. These parts
may be modified in different ways as suctorial organs.

The dorsal surface of each segment of an insect’s thorax
is the pro-, meso-, or mefa-notum; the under surface is the
pro-, meso-, or meta-sternum, and the sides are called pleura,
each of which is divided transversely into a fore (scapu/a) and
hinder piece (epzmerum). The mesonotum bears a some-
what triangular area (scu/ellum), with two lateral areas or pa-
vapsides. Endothoracic projections exist at the sutures,
Mesially on the metanotum is the fost-scutellum. Sometimes
the thoracic segments are closely united, or the prothorax
may be free (prothorax liber); in this case alone is it large.
The legs articulate in cavities (acefabula) between the sternum
and pleure. The first part of the leg is the coxa, more or
less sunk in the acetabulum; next follows a ring or /vochanter
to articulate with the next joint, or femur; then follows the
tibia, often with a movable projecting spur (ca/car) ; and lastly
the /arsus, of several joints, carrying at its end two, rarely one
claw, and often dermal folds between (pseudonychia). Limbs
may be natatory and flattened, gressorial, fossorial, saltatory,
or raptorial.

Dorsally articulated are the wings arising between
the notum and pleure of the meso- and meta-thorax ;
that on the first is the fore-wing, that on the second
the hind-wing. These are flattened saccular elonga-
tions of the integument, whose inner walls coalesce,
and are separated and supported by the cose of the
wing, consisting of branches of trachez with a thick-
ened chitinous lining, and chitinized externally. In
beetles, &c., the fore-wing becomes thickly chitinized,
loses its flying power, and becomes an ¢/ytron or wing
cover. Wings may be absent, especially in females.

2C

386 Introduction to Antmal Morphology.

Each abdominal ring is divided into separate large
dorsal and small ventral, sometimes into lateral,
pieces; thus the abdomen is distensible; posteriorly
it often bears anal or genital appendages—bristles,
spines, stings, forceps, vagine, cerci. The abdominal
segments of the adult never carry limbs except in the
beetle Spirachtha eurymedusa, whose third, fourth,
and fifth segments bear two-jointed appendages.

The larve of Lepidoptera and many Hymenoptera bear
small papillary processes, like the parapodia of worms, on
the somites behind the thorax, but the three anterior pair
alone exist in other larve, as in Myriopods, and these alone
have adult successors. In the larve of Phryganea the thora-
cic limbs are utilized as assistants to the jaws. The wings
are structures comparable with the shells of Entomostraca ;
their motions in flight are very rapid. The house-fly makes
300 strokes per second (Marvey); the point of the wing de-
scribes a figure of 8. The muscles are striped, colorless or
yellow, and complexly arranged.

The epipharyngeal nerve ganglion is large and
lobed ; the hypopharyngeal is joined to it by short,
but to the first thoracic by much longer bands; the
three thoracic ganglia may unite into one or two, and
the ventral ganglia vary from six to four.

In parasitic insects the hypopharyngeal ganglion and the
ventral cord become closely united. The brain ganglion is
generally medially divided; in ants and bees it is singularly
convoluted and lobed ;* the antennary, optic, and commis-
sural nerves arise from separate lobes. The ventral ganglia

* Probably these may be sensorial. /azvre’s experiments indicate that
co-ordination of motion may reside in the hypo-, and willin the epipharyn-
geal ganglia.

Introduction to Animal Morphology. 387

are originally pairs, but they early fuse; the longitudinal
commissures, however, remain double. From the hypopha-
ryngeal ganglion arise the oral nerves; from each thoracic
ganglion the branches for the legs and wings of that somite ;
the abdominal ganglia are usually small, except the last,
which sends branches to the outer reproductive organs. The
nerve cord may extend for the whole length of the body, as
in Orthoptera and Neuroptera, with 6-9 abdominal ganglia.
In Hymenoptera there are only two thoracic ganglia and
1-3-4 or 6 abdominal. In Coleoptera there may be also not
only two thoracic (the meso- and meta-thoracic being fused),
but the abdominal ganglia may be united into one mass (La-
mellicornes, Scarabeide, Melolonthide, Curculionids, or
may be segmented into eight (Carabide, Lucanide, Ceram-
byces). Other families show intermediate conditions. In
Thysanura the number of ganglia in the ventral chain is vari-
able—twelve in Lepisma, three in Smynthurus. In some
Hemiptera there is a single thoracic and a single abdominal
ganglion. In Lepidoptera there is a union of the second and
third thoracic ganglia in the adult, but they are often distinct
in the larva; and of the first and second, and often third ab-
dominal ganglia, which are also distinct in the larva. The
last (fourth abdominal) ganglion is bilobate, and seems
double. In all cases the commissures are not only laterally
but antero-posteriorly double, and the ventral portion has
been supposed to be sensitive, the dorsal to be motor, the
latter passes over, and fuses only partially, or not at all,
with the ganglia.* ‘The nerves arise by two roots, one from
each of these elements.

* The nerve cord is kept in its place by a muscular layer springing
from the body wall, and passing transversely over the chain of ganglia,
sometimes attached to the neurilemma of the interganglionic commissures
(Orthoptera), or also free from it (Hymenoptera), or as a meshwork of
irregular fibres, interlaced and inserted into the neurilemma (Diptera). In
Lepidoptera the neurilemma thickens, and forms a solid cord between the
longitudinal commissures, and into this connective axis the muscles are
inserted.

AAO

388 Introduction to Animal Morphology.

Besides this nerve system there are three series of
visceral nerves :—First, symmetrical, lateral, sympathe-
tic nerves arising from the back of the brain ganglion,
and running on the side of the cesophagus, forming
one, two, or manygangliathereon. Second, the zervus
recurrens, a medial nerve, arising from a small trian-
gular single, rarely double or triple (occasionally)
ganglion frontale, anterior to the epipharyngeal gan-
glion (from each side of the front of which its roots,
the nervi vagi, spring), passing backwards on the
dorsal aspect of the oesophagus, to form a plexus with
branches of the foregoing. Third, xervz transversz,
arising from the upper cord of the ventral nerve chain ;
each of which divides into two branches in front of
each ganglion, receives branches of communication
from the foregoing, and supplies the trachez and the
muscles of the stigmata. In development the nerve
system is comparatively late in being differentiated
from the tissues around it. The nerves terminate in
distinct Doyérean eminences in muscles, often in ¢ouch
rods, or hair-like free ends on the surface.

The antennez are abundantly provided with touch
corpuscles, which also exist on the palps and tarsi.
Short conical bodies on the front of the antenne may
be organs of smell.* Hearing organs are not uni-
versal, but the antennary rods of graduated lengths
have been shown to vibrate in response to certain
musical sounds; some have a chitinous ring, over
which is stretched a drum-like membrane ; beneath this
is a trachea dilated into a vesicle, on which is seated

* Or the fine pores on the antennze of Lamellicornes (Zvichson), or the
stigmata ? (Cuvier).

Introduction to Animal Morphology. 389

a ganglion whose nerves end in club-like rods, with
fine acoustic hairs. This is placed under the knee on
the outside of the front pair of legs in Crickets, or in a
shallow depression on the metathorax, close to base
of the third pair of limbs, and receiving its nerve from
the third thoracic ganglion in Acrididz. In Locusts
it is placed on the front pair of legs, and there is an
opening into its cavity. At the base of the halleres
of Diptera and at the base ofthe hind wings of beetles
there are areas where the chitinous integument is
pierced abundantly by pore-canals, and beneath which
are clusters of rod-like nerve endings, like those in
other auditory organs, but with no tympanic ring nor
membrane.*

Eyes are absent in cave-dwellers, or those living
in dark places, but are usually two, compound, ses-
sile, lateral, with sometimes accessory cornea-bearing
ocelli, varying in number: this class of eyes, or none,
exist in larvee as arule. The compound eyes consist
of 20-, 50-, 4000 (House-fly), 28,000 (Dragon-fly), hexa-
gonal, rarely quadrate facets. The organ is stalked in
Chloeon, Diopsis (Dipteron), and some Strepsiptera
and Hemiptera, but the stalks are not movable.

The muscles of insects are grouped into those with, and
those without, prolongations from the exoskeleton (tendon)
for their insertion; the first group are either conical, with
a single, or pyramidal with a laminated tendon, penniform
or compound (arising by several heads). In the larva of
Cossus ligniperda there are 228 muscles in the head; 1647
in the body; and 2118 in the viscera; but these, which
are little more than divided fasciculi of fibres, are capable

* Hicks and Lesfes describe auditory (?) vessels in the antennz of
Lamellicornes.

390 Introduction to Animal Morphology.

of grouping into larger series.* There are retractors and
occlusors of the spiracles, and numerous muscles for the
limbs and wings, which nearly fill the entire thorax.

The pharynx has often lobate processes (efz- and
hypo-pharynx) on its under surface, not to be con-
founded with outer movable processes of the tongue
or paraglossa. The cesophagus is often dilated into a
crop which may be a thin-walled and pedunculate,t
lateral sucking stomach; double in Chrysis and Lepi-
doptera ; the proventriculus, or gizzard crop, has mus-
cular walls and chitinous teeth, absent in suctorial
insects ; the thin-walled stomach has no chitinous lin-
ing, but is glandular, often with ceca or villi within.

The small intestine, or z/ewm, which follows, ends in the
rectum, at whose lower end are 4-6 longitudinal ridges, on
which rectal glands open. ‘The length of the intestine
varies with the solidity as much as with the nature of the
food ; thus the vegetable-feeding suctorial Cicada has a long
intestine, while the grasshopper has a much shorter one. In
larve the gastric region is long, and the intestinal short,
while in the adults these conditions are more than reversed,
and the intestine generally becomes curled. The stomach
may have ceca along its entire extent, or only at its origin
(Orthoptera), two (Locusts and Crickets), six (Acrididz), 4-8
(Perlide), none (Earwig and Phasma); the stomach itself
may be long and convoluted, as in Melolontha, Bees, &c.
The rectum generally dilates at its pre-anal end, and there

* Each wall of the caterpillar of the cabbage butterfly consists from within
outward of—first, two layers of longitudinal ; second, superficial and deep
internal obliques ; third, superficial and external obliques; fourth, a super-
ficial rectus, fifth, another layer of oblique fibres ; sixth, triangular diagonal
fibres ; seventh, transverse fibres in several layers.

+ Where the duct of this sucking stomach joins the cesophagus there is.
a flat muscular sucking disc.

Introduction to Auimal Morphology. 391

are many tracheze on its papillary ridges, which in the
aquatic larve of many dragon-flies are extended into trachei-
ferous lamellz, named /racheal gills,* which by the opening
and shutting of the anus are kept bathed with currents of
water, and thus serve as respiratory organs. Some Hymen-
opterous and Pupiparous Dipterian larve-have no anus, and in
ant-lion larva the rectum, thus cut off from the stomach,
becomes a spinning apparatus, with a fine outlet, and
receives the Malpighian tubes. In the larve of Dyticus
and Hemerobius, as well as in Myrmeleo, there is no mouth,
but there is a large opening at the point of each of the
powerful maxillz leading by a canal into the cesophagus.

Salivary glands are usually present (absent or
small in Ephemeride, Odonata, Scalide, Aphides, &c.)
They are two long, lobed pouches in Termes; tortu-
ous tubes in Beetles, Diptera, and Lepidoptera, or
1-3 pair of acinose glands in Hemiptera and Or-
thoptera. Panorpa has six large glands in the male,
and only one minute pair in the female. The duct is
dilated in Mantis, Lucilia, &c. Fine longitudinal or
tortuous brown or whitish AZalpighian tubes open into
the intestine (except in Podure, Coccide, Aphis, and
Chermes), but present in Lepisma and in most other
insects. There are four in most Diptera and Hemip-
tera, six in Lepidoptera and Neuroptera, four or six
in Beetles. They open close behind the stomach in
Hymenoptera, Diptera, Cicadx, Lepidoptera, &c.
Larve have usually the same number of tubes as
adults, except in Bees, whose larve have only four.
They rarely branch, but sling-like unions between
their ends are found in some, and sometimes vesicular

* Similar to these are the many-jointed cerci anales of many Beetles
and Lepidoptera, which are possibly the representatives of the tail oars of
Copepods.

392 Introduction to Animal Morphology.

dilatations. In many Hymenoptera they are nume-
rous and short; in some Orthoptera over 100, and in
Gryllotalpa, where they are numerous, they unite into
a single duct. In Melolontha they open into a
smallceecum: they contain uric acid, oxalic acid and
leucin.

There is no liver: in some Hemiptera and Orthop-
tera cecal tubes are described as pancreatic. The
fatty body is large in larve, yellow, lobed, often fas-
tened to the body wall and to the viscera which it
suspends; around it are often netted tracheal branches.
Its materials are used up in the pupa stages, and it di-
minishes as the sex-organs mature. In Lampyris it
is modified into the luminous organ, which consists of
a flat transparent lamella of polyhedric cells, richly
supplied with tracheze and nerves. On the dorsal side
these rest on a layer of white opaque non-luminous
cells, which contain concretions of urea. Probably the
luminous organ in Elater is similar.

The blood is colorless, green, or red, with clear
nucleated corpuscles and fat granules. The heart is
dorsal, tubular, chambered, as in Myriapods, but
lying in the abdomen, supported by triangular /zga-
menta alaria, or muscult, one attached to the outer
connective coat of each chamber, and slung thereby to.
the body wall, and often to the neighbouring trachee ;
it is continued forwards, as the cephalic aorta, into
the thorax and head. There are usually eight cham-
bers, each of which receives blood through a pair of
venous ostia guarded by valves, and sends its blood
into the one before it, regurgitation being prevented
by valves, until it reaches the aorta, from whence the
blood returns by lacune to the heart. There is no

Introduction to Animal Morphology. 393

true pericardium for its collection. In the limbs defi-
nite blood channels are traceable, and in the wings
true walled vessels and capillaries have been de-
scribed.

The aorta is an anterior chamber of the heart, without
venous ostia, or ligamenta alaria (Weissman). The heart
muscle is not in discriminable strata. It acts more rapidly
in the adult than in the immature stages. In Sigara coleop-
trata there is an accessory contractile space in the tibia.
The heart is a simple tube in some Dipteran and Hymenop-
teran larve.

Respiration is by various kinds of trachee. Some
aquatic insects have a closed system, with no stig-
mata—a breathing organ differing from gills, in that
the blood is aerated by oxygen separated from the
water, and conveyed in tubes to the blood. The tubu-
lar system in the gill covers of Oniscus is closely re-
lated hereto. In Phryganea and some Dipteran larve
there is a sub-dermal free branching of tubular or
lacunary air channels, the dermis separating the air
from the surrounding medium. A second breathing
organ consists of leaf-like surface processes or areas
containing these closed trachee (tracheal gills before
referred to); these form a lateral row along the body
of an Ephemeron larva and in other Pseudoneuro-
pteraand Neuroptera, and persist in the Orthopteron,
Pteronarcys regalis, which has thirteen pair. A third
form of closed tracheez is found in Dragon-flies, &c.,
where the internally placed trachee ramify on ridges
within the rectum. Wings may be permanent, homo-
logues of these external gills. Open tracheze are
most common, and they vary in number, and in the

394 Introduction to Animal Morphology.

arrangement of the stigmata, which may be two,
sometimes tubular, posterior (in aquatic larvee), or four
(two in front on the second somite, as well as two be-
hind, as in headless Dipteran larve), but usually they
are more numerous. In adult insects they are in the
soft intermetameric rings under cover of the wings.
There is one pair in aquatic Hemiptera (Nepa).
Smynthurus has one pair of stigmata on the head be-
neath the antenne. Papirius has no trachee, nor has
the larva of Chloeon for its first few stages before its
tracheal gills develop. Podura has four pair of abdo-
minal stigmata; others have even one on every post-
cephalic somite. The stigmata may have a raised
border (Peritreme), valves, bristles or a sieve like
cover (Estrus larvee, Lamellicornes). These trachez
may be simple unbranched, or may have simple anas-
tomosing tubular branches, or may have vesicular di-
latations, with no spiral thread, as in some flying
insects. The anastomoses may produce continuous
longitudinal or transverse canals.

Many insects emit sounds which are audible to us,
and probably many others produce notes too high for
our appreciation. They may depend on the rubbing
of the body rings together, the streaming of air from
the stigmata, the rubbing of the wing covers against
the back or the hind legs, or the head against a chiti-
nous plate.

All insects are normally oviparous and dicecious,
the sexes often differing conspicuously. The testes
are two, rarely twelve, in a pair of clusters, as in some
beetles, branched or pouch-like, united into one in
some Lepidoptera, in a connective sheath (dunzca
vaginalis). From each passes a vas deferens, which

Introduction to Animal Morphology. 395

unites with its fellow in a common ejaculatory duct,
to which are appended 1-3 pair of long, tortuous, or
branched mucous glands for uniting the thread-like
spermatozoa into spermaphores, and one or two vesz-
cule seminales. There is often a chitinous, grooved,
or tubular penis, which may lie in a special capsule
(some beetles), and may be an elongation of the end
of the duct. The sex orifices are usually in the
space between the eighth and ninth ring, rarely
far forward, as in the female Strepsipters. In Libel-
lula, the penis is on the second abdominal segment,
and has at its base a seminal vesicle, which, by a
bending of the abdomen before copulation, is filled
from the vas, which opens far back.

The female has a tubular ovary on each side (or a
dense, often verticillate, bundle of ovarian pouches, as
in Hydrobius, &c.), fixed by an
ovarian ligament. The oviduct
begins as a calyx, and opens into
a common uterus, ending in a
vagina, at whose mouth open one
(Cicada) ortwosimple or branched
colleterial glands, by whose se-
cretion the eggs are united and
fixed in their places. <A vrecepta- j
tulim seminis opens intO the Reproductive organs of Lytta.
vagina, or into the hinder part of oe Sa ae ; peor aie
the oviduct, and there is often a separate cecal pouch
from the vagina or bursa copulatrix for receiving the
penis. Owing to these receptive cavities, one impreg-
nation fertilizes successive broods of eggs. There
are also chitinous organs whereby the eggs are laid,

396 Introduction to Antmal Morphology.

(ovzposztors), in the forms of piercers or saws, &c. The
ovipositor and penis are both altered metameres.

In the ovary arise two series of products. The
terminal cells of the ovarian tubes produce the ova
proper, but in the epithelial wall of the tube lower
down is secreted a yelk mass for the nutrition of the
germ.

Insects’ eggs have an outer, often sculptured, shell,
which has usually a micropyle at one pole. In some
Diptera the eggs are retained and hatched in a cecal
process from the vagina. In Melophagus the colleterial
glands secrete a fluid whereby the young are nourished
in the larval stage.

True or pseudo-parthenogenesis (p. 36) occurs in
many insects. Metagenesis has been described in
Cecidomyia, where a larva produces embryos: but as
there is a peculiar pseudovarum present, though with
no oviduct, this is probably a form of pseudoparthe-
nogenesis.

In the developing egg, after the partial (rarely
complete, Poduridz) fission of the yelk, a germinal
membrane forms usually around the yelk, with a pri-
mitive ventral streak, in which the abdominal and
head segments begin to appear. Eggs are thus
usually ectoblastic, but some seem to have a periphery
of yelk, and be endoblastic. The germ is inclosed in
a cellular amnion (chitinoid, structureless in Poduride,
Packard). Finally, the germ breaks the shell, some-
times by the help of provisional organs (Pentatoma,
Phryganea, Mantispa). The young thus produced is
a larva, and this may only differ from the perfect
adult in size, and in the number of corneal facets, or
else the larva may, by developing wings and a more

Introduction to Animal Morphology. 397

sharp differentiation of the thorax, assume its adult
form. Insects which only undergo changes like these
are called ametabolous. Other insects, while under-
going the growth of wings, &c., lose embryonic
organs, and are called hemimetabolic. Most, how-
ever, differ very much in their larval and perfect states,
and the former passes through a quiescent or fupa
period before it becomes mature; these are holome-
tabolic. The larve, or caterpillars in general, are
annelid-like, nearly homonomous, with a soft skin,
and stumpy or no feet; when present, the three an-
terior pair are often discriminable from the others
(which are called prolegs*),in shape and colour, and in
being several-jointed (often five). They are voracious,
with powerful jaws, a large stomach, and a large fatty
body ; they grow rapidly, and moult frequently. On
attaining their full size, those with labial silk-glands
spin a cocoon ; others become quiescent, inclosed in a
thickened skin, and cease to eat. This pwfa or
chrysalis stage lasts until the internal organs attain
perfect development. They seem to undergo a nearly
perfect histolysis, and from certain areas of formative
tissue, called zmaginal discs, rearrangement takes
place; then the pupa skin splits along the back, and
the zmago or perfect adult is produced. The pupa
may be free when the locomotory organs remain free
from the trunk, as in Hymenoptera and Coleoptera,
or obtected when these organs are inclosed in the
pupa skin, and so are covered, as in Lepidoptera, or
coarctate, when the whole body is wrapped up, with
no trace of limbs, as in Diptera. Onbecoming free,

* Prolegs may be seven pair (Tenthredo), or eight (Cimbrex).

398 Introduction to Animal Morphology.

the soft imago body speedily dries, and early dis-
charges the urine which had been accumulating during
the pupa-sleep.

Some larve have bristles, or, in Sphingide, a
dorsal horn. The head bears a pair of procephalic
scales or lobes, in front of which is a froclypeuws. The
larval antenne differ from those of the imago, and
joint with the front edge of the procephalic shield,
external to the articulation of the mandible, thus re-
sembling the antenne proper of Crustacea, while the
imago antenne, arising farther inwards and forwards,
-are the homologues of the antennules (Zaddach).
Some larve are dimorphic.

CHAPTER XLVII:
CLASS INSECTA.

INSECTS are almost all terrestrial; very few (Halo-
bates, Gyrinus) are marine. About 175,000 species
are known, which can be divided into two sub-classes,
according to the extent of their metamorphoses.

Sub-class 1. Ametabolica—with no, or imperfect
metamorphosis.

This includes the following six Orders :—

1. Mallophaga (Vi/zsch)—wingless, flattened, ametabolic ;
parasitic on birds and mammals ; antennz 3-5 jointed; eyes
simple; mouth masticatory; mandibles hook-like; palps
four-jointed, or none; meso- and metathorax mostly fused
abdomen 9-10 ringed, but with few (4-6) ganglia; pharynx
muscular; intestine simple. The antennze may be three-
(Trichodectes) or five-jointed, thread-like, with no maxillary

Introduction to Animal Morphology. 399

palp (Philopterus), or clavate, four-jointed, with (Liotheum)
or without a palp (Gyropus). ‘This may be a sub-order of the
next.

2. Rhynchota (/adricius)—with or without wings; mouth
suctorial ; labium elongated into a long, apparently jointed,
tube (vagina), only open above at the base, where it is covered
by the opercular labrum. Within this the maxille and man-
dibles are altered into sharp, protrusible, piercing sete;
maxillary palps none; labial palps merged into the vagina;
eyes moderate, compound or simple; the antennz are either
short, 2-3 jointed, and aristate, or long. When wings exist,
the fore pair are often, for at least half their extent, leathery
or horny, forming Aemzelytre or sheaths for the hinder pair.
The tarsus is usually 2-3 jointed; the stigmata are ventral;
there is no crop; along, often trifid, stomach; the intestine
is usually tortuous, with four Malpighian tubes; there is no
bursa copulatrix (except in Cicada, which has a double re-
ceptaculum seminis); the larvz, at the first moult, show the
rudiments of the wings; many of them have odorous glands
on the metathorax or abdomen ; they are mostly retrogressive
forms, living on plant or animal juices, and include three
sub-orders :—

1. Pediculina (Burmeister)—lice, wingless, ametabolic,
with two ocelli and a sharp proboscis armed with recurved
hooks ; antenne thread-like, five-jointed ; thorax obscurely
segmented (Pediculus) ; extremely small in Phthirius; para-
sites on mammalia. At least three species infest mankind :—
Pediculus capitis, the head-louse; P. vestimenti, and P.
tabescentium, the louse which multiplies so rapidly in the
disease Phthiriasis, of which Herod, Sulla, Honorius (King
of the Vandals), the Emperor Arnulf, Philip II., &c., died.
Hematopinus is a common pig- and cattle-parasite.

z. Homoptera (La/reil/e)—wings two or four, equal, lying
straight, and imbricated on each other when at rest; often
absent in the females ; mouth usually turned back ; prothorax
short, and the three thoracic rings more or less united ; eyes
compound, with ocelli between them. Here belong the fol-
lowing families:—1. Coccide—mostly tropical, phytophagous;
antenne six- or more jointed; proboscis, and often hind

400 Introduction to Animal Morphology.

wings, rudimental in the male; tarsus two-jointed (one-
clawed in Dorthesia) ; females wingless, rounded, winged in
Aleurodes, their bodies covered with eggs; the males have
a pupa stage in a cocoon; Coccus cacti yields cochi-
neal; C. lacca yields shellac ; Porphyrophora yields German
cochineal; C. ceriferus yields Pe-lac wax. 2. Aphididae—
antennze five- (Chermes), six- (Rhizobius), or seven- (Aphis)
jointed, often longer than the body; wings four, or none;
tarsus two-jointed; salivary glands and Malpighian tubes
none. Aphides, Lachnus, and Schizoneura have two elan-
dular cornula or honey tubes at the end of the abdomen,
the secretion of which is eagerly devoured by ants; ocelli
none. Pseudoparthenogenesis occurs among these; the
eggs hatched in spring, producing wingless, imperfect
females, whose ovary produces germs with no germinal
spot (pseudova), which develop without fertilization. This
process goes on in successive broods until the altered con-
dition of food and temperature at the incoming of autumn
checks it, and this last brood consists of males and females
with perfect sex-organs, whose fertilized eggs survive the
winter to undergo the same round on the renewal of favour-
able outer conditions. Schizoneura lanigera, with a red,
spotted abdomen, is a pest of fruit trees. 3. Psyllidae—
antennz as long as (Psylla), or shorter than, the body (Livia) ;
8-10 jointed, with two fine terminal ariste;ocelli three ;
femur thick ; tarsus two-jointed, with lobes between the two
proper claws; fore wings leathery. 4. Cicadellinide—head
free; frons broad: ocelli two, or none (Typhlocyba, found
on diseased potatoes) ; antenne short, two-jointed, aristate ;
fore wings leathery; hind legs long. Aphrophora, with two
sharp calcaria on its hind leg, secretes the ‘cuckoo-spit.”
Ledra has two upright, ear-like processes on the prothorax.
5. Membracide—head down-directed, with two ocelli be-
tween the eyes; prothorax with large processes, which often
overhang the abdomen, and whose shapes are often eccentric,
as stalked globules or ridges, &c.; mostly American, except
Centrotus. 6. Fulgoride: Lantern-flies—head with vesi-
cular or cornute processes; wings colored. F. laternaria is
the lantern-fly of Guiana. Flata limbata produces Chinese

Introduction to Animal Morphology. 401

wax. 7. Cicadide—head short, vertical; eyes prominent ;
ocelli three ; antennz internal to the eyes, seven-jointed; a
bursa copulatrix and two receptacula seminis ; intestine 6-10
times as long as body; a drum-head-like elastic membrane
lies on the under side of the first abdominal ring in the male,
whose tension is altered by a muscle producing the charac-
teristic shrill rertrywvia ; behind this drum-head is a vesicular
trachea.

Sub-order 3. Heteroptera (Za/rec//e)— anterior wings
hemielytre, horny in front, membranous behind. The first
four families are aquatic (Hydrocores), the others are terres-
trial (Geocores). 1. Notonectidze—back convex ; venter flat ;
head large; antennz four-jointed, hidden; ocelli none: hind
legs flattened, natatory, bristled along their edge; anterior
tarsus one- (Corixa, Sigara) or three-jointed (Notonecta).
z. Nepidz, Water Scorpions—broad and flat ; caput receptum ;
eyes large, and no ocelli; fore feet for grasping, hinder for
swimming; stigmata with sieve-like opercula. In Ranatra
there are large, thoracic, tracheal vesicles and largely deve-
loped tracheze elsewhere. Nepa and Ranatra have also two
tracheal tubes opening at the anus. 3. Galgulide—body
discoidal ; antennz four-jointed ; ocelli distinct. 4. Ploteres—
body small, with no neck, silky haired below; antennz long,
four-jointed ; middle and hind legs long, whereby they can
leap on the surface of the water. Halobates inhabits the
Pacific Ocean. Hydrometra has a large pro-, overlapping
the meso-, thorax. 5. Reduviide—tropical ; head free; an-
tenn thread-like, four-jointed; proboscis subulate, triar-
throus ; prothorax with transverse constrictions. Conorhinus
sometimes sucks human blood. 6. Membranacei—flat, usually
wingless, with four-jointed antenne, three-jointed vagina,
and two-jointed tarsus. Cimex, the bed bug (introduced into
England in the sixteenth century), has no ocelli. Aradus has
wings. 7. Capside—head small, recept, trigonal; ocelli
none; eyes small; vagina four-jointed; tarsi unequal, three-
jointed ; hemielytra with an appendage in front of the
membranous part. 8. Coriside—head flattened, deeply
recept; ocelli two; antennz thread-like, often highly
coloured; wings membranous, often with forked veins;

2D

402 Introduction to Animal Morphology.

mostly tropical. Anisoscelis has dilated tibia: some have
remarkable forms.

Order 3. Thysanura (Za/red/e)—wingless, ametabolous,
living in damp, dark places, hair- or scale-clad, rarely with
compound eyes, but with two groups of 6-14 ocelli; mouth
masticatory; Malpighian tubes few, long ; abdomen with ter-
minal bristles or a bifid tail. Lepisma has the typical lower
lip of Orthoptera; others have no trace of a second maxilla,
asin Myriopods. They include two families :—1. Poduridae—
cylindrical mouth, small, with no palp ; abdomen 6-3 ringed,
with a fork-like tail, whereby they can spring; hairy or scaly
back ; prothorax small, hidden; ocelli four (Achorutes), seven
(Desoria), or eight. Cyphoderus has a cup-like mesothorax.
Podura scales, being finely lined, are used as test objects for
the microscope. Smynthurus has cephalic stigmata. 2. Le-
pismidze—fusiform, with small metallic scales and many-
jointed antenne ; abdomen ten-ringed, with five end-bristles,
of which the middle is the largest. Machilis (Petrobius) has
compound eyes. Nicoletia is blind. Lepisma, the scales of
which are also commonly used as microscope tests, lives in
sugar.

Order 4. Thysanoptera (Haliday}—small, flattened, found
in vegetables; head cylindrical; mouth suctorial, directed
downwards and backwards; maxille fused with the labrum;
mandibles bristle-like; antennze 8-9 jointed; eyes large;
ocelli present ; maxillary palp 2-3 jointed ; labial two-jointed ;
prothorax small; wings two pair, equally long, bristled, not
folded, with few veins ; rarely short or none. Tarsi two-jointed,
with a sucking disk and no claws; intestine about twice as
long as the body; malpighian tubes four, free at the tips.
The females of Thrips have a compressed four-valved ovi-
positor. Phlceothrips has a tubular last abdominal segment
in both sexes.

Order 5. Euplexoptera (Westwood): Earwigs—head free ;
clypeus short; labrum large, crescentic ; labium cleft to the
base of its stipites; ocelli none; eyes over the thread-like
12-40 jointed antenne ; prothorax quadrangular; hemielytre
much shorter than the abdomen, with no membranous area ;
hinder wings thin, fan-like, with radial coste, useless for

Introduction to Animal Morphology. 403

flight; tarsus three-jointed; abdomen nine-ringed; the
seventh and eighth are short in the female, and covered by the
sixth ; posteriorly is a forceps of two incurved processes on
both sexes. The female incubates her eggs.

Order 6. Orthoptera (Aay)—hemimetabolic, with no
pupa stage; wings four, with reticulated costz; when they
are unequal, the fore pair is small, pergamentaceous; the
hinder membranous, broad and longitudinally folded ; mouth
masticatory; mandible toothed ; maxilla overhung by a helmet-
like, outer lamella (galea), with 5—7-jointed palps; labium
completely cleft, its palps three-jointed ; the eyes are large,
and there are usually 2-3 ocelli and many-jointed antennz ;
the salivary glands have a receptaculum and 6-9 glandular
pouches opening into the stomach. ‘There are many short
Malpighian tubes, and the ventral nerve cord is sometimes
curved, and longer than the sessile abdomen. Some have no
bursa copulatrix, but often a two-valved oviscapt formed of the
modified last abdominal rings; larve apterous, but wings
appear at the fourth moult; tracheal gills or cere? anales are
often present. This polymorphic group includes the follow-
ing sections and families:—§ 1. Cursoria—running forms,
including: 1. Blattidae—flat, oval; head covered by the pro-
thorax ; antennz bristle-like ; tibia spiny ; tarsus five-jointed ;
wing covers overlapping medially ; abdomen with 9-10 dorsal,
and six (female) or eight (male) ventral rings. In Polyzosteria
both sexes, in Heterogamia and Perispheria the females
alone, are apterous. All but Blabera have a lobe between the
tarsal claws. Periplaneta orientalis is the common cockroach.

§ 2. Gressoria, walkers. 2. Phasmidz—body linear, rod-
like, with all the legs equal, and often lobate dilatations of the
femur and tibia; tarsus five-jointed, with an accessory claw
between the two normal claws ; eyes semicircular; upper lip
deeply notched; mesothorax elongated; tropical, walking-
stick insects. In Bacteria and Bacillus both sexes are wing-
less. The male alone has wings in Cladoxenus, and both in
Phasma, Prisopus, and the leaf insect Phyllium. 3. Mantidze—
head free, vertical; thorax and abdomen elongate; wings
large ; front legs flattened, sharp, raptorial. Schizocephala

2D2

404 Introduction to Animal Morphology.

has its prothorax three times the length of the meso- and
meta-thorax.

§ 3. Saltatoria, leapers—female with an ovipositor (except
in Gryllotalpa); mostly winged. 4. Gryllidze—cylindrical,
with thick, free head, elliptic eyes; bristle-like antennz ;
maxillary palp with a vesicular point; fore wing horizontal ;
hinder larger, closely folded; hind leg long, thick; fore
limbs are for burrowing in Gryllotalpa, or simple, gressorial,
and the prothorax smaller, as in Gryllus. Acheta, the house:
cricket, belongs here. Platyblemma has a wide forehead.
5. Locustide—wings, when in rest, imbricated; body long,
laterally compressed; antennz bristle-like; the males have
a sound-apparatus in the right elytron; the hind legs are
long, with thick thighs. Schizodactylus has the wings elon-
gated, and spirally twisted behind. Here is included Dec-
ticus, the grasshopper. 6. Acrididze—head vertical; body
laterally compressed; elytre small, with no sound-organs ;
tarsi threesjointed ; forehead with a longitudinal keel. édi-
poda migratoria is the destructive locust.

§ 4. Corrodentia—wings homonomous, not capable of
folding together ; tarsi 2-3 jointed ; end segment of the lower
lip of two lobes. 7. Embide—head longitudinal, free, four-
angled, with small eyes; ocelli none; prothorax narrow in
front; tarsus three-jointed. The larvz spin cocoons in these
tropical forms. 8. Psocide—head large, with a vesicular
forehead ; long bristle-like, 8—1o jointed antennz ; no maxil-
lary palps; wings, when present, unequal, the hinder being
one-half the size of the fore. Troctes pulsatorius is the book-
louse or death watch.

§ 5. Socialia—besides the winged sexual individuals, there-
are apterous, sexless forms. 9. Termitide (white ants)—
head free; antenne short; rosette-like; 13-20 jointed;
ocelli three; outer maxillary lamina leaf-like; tarsus four-
jointed ; males and females with delicate wings, apterous.
workers, with small round head, and small mandibles, and
soldiers, with large square head, and sting mandibles, exist
in the colony. In impregnated females the abdomen is very
large. They build large hills of clay, cemented by their
saliva, within which are regular galleries.

Introduction to Animal Morphology. 405

§ 6. Amphibiotice—with aquatic larve. 10. Perlidee—
body long, flat, with bristle-like antenne, lateral eyes, equal
thorax rings, large hind wings, and a ten-ringed abdomen ;
aquatic larva has hypo-thoracic tracheal gills, which are
retained during life by Pteronarcys. 11. Ephemerida—
delicate, soft-skinned; eyes large in the males, small in
the females; mouth rudimental; mesothorax long; fore wing
large, triangular; hind wing small, or none (Ccenis). After
the last moult it only lives a few hours; but the larva, which
has strong jaws, and large lateral gills, lives 1-2 years in
water. 12. Libellulide (Dragon-flies)—body long; wings
delicate, equal, large, netted; jaws large, covered by the
large upper lip; prothorax small; abdomen 9-11-ringed;
larve with external (Agrion, &c.) or intestinal gills, and an
elongated tongs-like labium (mask), which may be joined to
the other parts of the head.

CHAPTER: XLVILE-
SUB-CLASS 2.—HOLOMELABOLA.

INSECTS with full metamorphosis, and a pupa stage:
herein are included eight orders.

Order 7. Neuroptera—prothorax free ; tarsus five-jointed ;
mouth masticatory, with cleft labium, bearing a three-jointed
palp ; wings membranous, equal, the hinder never folded ;
body long; head short; eyes rarely very large; antennz
many-jointed, thread-like, convoluted (Panorpa); suctorial
stomach rarely absent (ibid.); ovarian caeca numerous, ver-
ticillate, or pectinate; pupa free; larve carnivorous. The
families are:—1. Megaloptera—antennz club-shaped; head
vertical, ligula undivided ; larve with large heads, and sucking
claws ; including Myrmeleon or Ant-lion, whose larva lives
in funnel-like sand-burrows, sucking whatever falls therein.

406 Introduction to Animal Morphology.

2. Hemerobiide —antenne like strings of pearls; ocelli
none ; larva without suctorial claws; ligula strong, undivided ;
Chrysopa perla, the aphis-lion, emits a pungent odour. The
larve of Sisyra live in Spongilla fluviatilis. Hemerobius has
the last joint of the palp very long. Mantispa has the fore-
limbs predatory. 3. Sialida—head flat, horizontal; ocelli
present (none in Sialis); labium with a membranous, me-
sially-slit ligula, with terminal palp. Raphidia is called the:
camel-neck fly from the shape of its prothorax. 4. Panor-
pide, Scorpion-flies—head vertical, beak-like, with the cly-
peus at its extremity over the oval labrum, and a smaller
bidentate mandible.

Order 8. Trichoptera (A77by)—resembling the last, but
with hair-clad or scaly unequal wings, of which the hinder
pair are folded; mandibles membranous; maxilla and lower
lip united into a valve-like flap, the palpi being nearly obso-
lete, or 2-5 jointed. The prothorax is reduced to a collar,
and the meso- is longer than meta-thorax. This includes one
family, Phryganeide or Caddis-flies, whose larve by agglu-
tinating sticks, &c., make a case for themselves (spiral in
Mormonia). The males and females often differ in the num-
ber of joints in their maxillary palp.

Order 9. Strepsiptera (A774y)—minute viviparous insects ;
parasitic on the abdomen of bees and wasps. The males have-
four wings, the anterior short and twisted; the hinder large,
fan-like infolding, and membranous, but with trifling power
of flight; head short, vertical; eye large, with few facets ;
antenne 4-6 jointed ; legs clawless, with a four-, three-, or two-
jointed tarsus. Females wingless, with a cephalothorax, and
a worm-like abdomen; mandibles as two long, crossing
bristles; maxilla fused to the labium, with a large two-
jointed palp; labial palp none; pro- and meso-thorax
short ; metathorax very large. The larve have at first six.
long legs, two tail bristles, and tracheal gills. They live
on wasp-larve, and at their first moult their limbs are
lost, and they become worm-like, then attain their pupa
stage, and the female never leaves her pupa skin. The eggs.
are developed scattered in the whole body. The eyes are:
stalked in Stylops, sessile, fifteen-jointed in Elenchus.

Introduction to Animal Morphology. 407

Order 10. Aphaniptera (A7rby): Fleas—laterally com-
pressed, wingless, or with scale-like rudiments, with simple
or no eyes, short antenne, lying in a groove; labrum none;
mandibles long, slender, saw-like, having between them the
needle-like epipharynx. Maxille short, broad, with long,
four-jointed palps; labium cleft, palp-like, often jointed;
thoracic segments homonomous, discrete; hind legs saltatory ;
larvee white, hairy, footless, worm-like. Blood-sucking para-
sites, closely related to Diptera, forming one family Pulicide.
The labium is distinct (Pulex), or rudimental (Sarcopsylla,
the chigoe; its females burrow in the skin of exposed parts
in the West Indies).

Order 11. Diptera—metabolic, with suctorial mouths, two
transparent, mesothoracic wings, with radiate coste, and rudi-
mental, often irregular, mesothoracic wings, modified into scale-
like or pin-like halferes, or balancers; eyes two, very large ;
ocelli three, vertical; neck slender. The mouth isa proboscis,
of which the labrum and labium each make make half-tubes ;*
the maxille (sca/pella), mandibles (cw/éellr), are bristle-like,
or knife-like, accessory organs, and the former always bear
palps. There is also in the last a median sharp epi-
pharynx (glossarium). The labial palps are absent, but
the maxillary palps often appear (Fig. 45.)
as labial (Stratiomyide, Muscide).
The antenne are single, pecti-
nate, or short, three-jointed, with
a bristle (arisfa) at the tip, which
may be naked (arisfa nuda), or
hair-clad (pz/osa), or terminal (apz-
calis), or dorsal (dorsalis). The , PlanofWing of Dipteron: 1, An-

: terior basal cell; 2, hinder marginak

prothorax fused with the strong cell; 3, third basal cell; 4, second
A nee basal cell; 5, discoidal cell; 6, axil-

mesothorax. The wing is divided lary cell; 7, lobe cell; 8, sub-mar-

6 : : . ginal cell, Zvew ; 9, sub-costal cell ;
by its coste into celluli (Fig. 45), Schiner ; 6, mediastinal cell ; 2, hu-

: meral costa; 7, radial costa; 9, first
and at its base has two lobes, an longitudinal costa ; 2, cubital costa;

alula and a squama, the latter over % discoidal costa ; 2, 2, uniting cos-
tz; 2, postical costa; 2, anal costa;

the halteres; the foot ends in two ~, axillary costa.
claws, with one or more intervening cushions or pulvilli,

* That of the labrum = valvuda, of the labium = vagina, with often a
terminal lip, capitulum.

408 Introduction to Animal Morphology.

covered with sucking hairs, whereby they can walk on
glass, &c. They have a stalked suctorial stomach, four
or five often uniting Malpighian tubes, no bursa copu-
latrix, often three receptacula seminis, and a footless larva ;
some are viviparous; Miastor is said to be metagenetic, Chi-
ronomus is parthenogenetic. The aquatic larve have tracheal
gills, and some have long breathing tubes. They are divisi-
ble into two series.

Sub-order 1. Pupipara—viviparous, the larve born when
ready to become pupz. The thoracic rings fused; labium
unjointed, antennz short, with a small knob, or two joints,
often. parasitic, unwinged; the abdominal ganglia are fused
into one, intestine long. The families are :—z. Braulide or
Bee-lice—wingless, with large eyeless heads, two-jointed
antenne, and five-ringed abdomen ; claws comb-like; 2. Nyc-
teribiide, Bat-flies—horny, with compressed, wingless, or
abortively winged, head cup-like; halteres with a terminal
knob; claws two-toothed; base of the second pair of legs
with two comb-like organs; 3. Hippoboscide—spider-like,
horny, flat-bodied, with large eyes; halteres free, small;
eggs few, hatched singly, and the young nourished by sucking
the secretion of the colleterial glands. Hippobosca, the
horse-fly, has no ocelli. Sternopteryx is found on young
swallows, Raymondia on bats, Melophagus on sheep.

Sub-order z. Ovipara—the female lays eggs, or larvee just
emitted from the egg. These form two sections :—§ 1. Coarc-
tate. The pupz form within the larval integument, which
hardens into a pupa shell. The families included are:—
1. Stratiomyidz—antenne three-jointed; proboscis with a ter-
minal fleshy lip ; larvz often with radiant cerci anales; heads
often spiny, abdomen 7-8 (Xylophaga, &c.), or five-ringed
(Stratiomys, &c.) 2. Syrphide—antenne three-jointed, with
single end joint, proboscis as last; fourth costa of wing
simple, not forked as in last. 3. Conopide—head with large
eyes, thread-like proboscis; halteres free; wings long; para-
sitic on other insects, Myopa and Conops on bats. 4. Muscide
flies—antennz three-jointed, with an end bristle; larvz soft,
with two protrusible lips ; two horny jaws ; ocelli distinct ; pro-
boscis with a fleshy end-lip; palps one-jointed ; abdomen five-
ringed—a very numerous family. One species of Tachina

Introduction to Animal Morphology. 409

is parasitic on earwigs. Sarcophaga carnaria is the flesh-fly ;
M. domestica, the house-fly ; Calliphora vomitoria, the blow-
fly, Lucilia Cesar, the gold-fly, with glistening emerald green
wings ; Glossina morsitans, the Tsetze of Africa; Anthomyia
and Scatophaga are the dung-flies. About 8000 species of flies
are known. 5. (Estridw, Gadflies: bots—antennz short, wart-
like, with a naked arista; proboscis rudimental; larve with
recurved hooks on the edges of their wings. The eggs of
Gastrophilus equi, laid on horses, &c., are licked by them,
and develop in the digestive canal. Hypoderma, the deer
and ox bot, has no larval hooks.

§ Obtectze—pupa inclosed in a separate case, like that
of Lepidoptera. These form two sub-sections :—1. Brachy-
cera, with short antennze, not more than three-jointed, of
which, however, the last may be complex. This includes two
groups, one with the proboscis short, the other (Brachysto-
mata); the other with it long (Tanystomata). The former
includes five families:—1. Scenopinide: Window-flies—
abdomen flat ; maxillee rudimental; larve thread-like. 2. Pla-
typezide—legs short; pulvilli two; found in mushrooms.
3. Dolichopodide—long-legged; pulvilli three. 4. Leptide—
maxilla and epipharynx free; larva with two anal breathing
tubes. 5. Therevide—tarsus with two pulvilli; pupa spiny.
Group 2. Tanystomata—r1. Asilide—elongated; head ap-
pendaged. The united mandibles and epipharynx form a
piercer; maxilla sharp; labium pointed; tarsus with two
pulvilli. 2. Empide—head small; proboscis variable in
length, when long turned downwards, and with no terminal
valve; piercing organ as in the last, but finer; abdomen
eight-ringed ; halteres uncovered. 3. Bombiliide—antennze
long, three-jointed, sometimes far apart; eyes large, conni-
vent in the males; proboscis sometimes as long as the
body, with bristle-like piercers ; abdomen often woolly, 6-7-
ringed; larvz parasitic on other insects, in whose nests they
live ; pup with hook-like bristles. Bombylius is like a bee.
Nemestrina has a proboscis four times the length of the
body. 4. Tabanide—antennz with three joints, annulated,
often divided; eyes often bright coloured; mandibles pre-
sent only in the blood-sucking females; the half tubular

410 Introduction to Animal Morphology.

labrum and epipharynx act as sucking organs. Hadrus
pierces the human skin deeply (Brazil). 5. Inflata—head
bent down, small, entirely occupied by the eyes; thorax
and six-ringed abdomen large inflated; proboscis variable,
sometimes longer than the body, and turned under the
thorax, or absent ; palps rudimental.

Sub-section 2. Nematocera—antenne six-, or more-jointed.
This includes two families :—6. Culicidze: Gnats—proboscis
long, thread-like; mandibles and maxilla free. The females
alone sting, and the irritating fluid supposed to be instilled
is the saliva. The pupacan move, and has thoracic breath-
ing tubes; the larva has an anal air tube. 7. Tipulide:
Crane-flies—proboscis short, fleshy; maxille fused with the
labium, often also with the labrum; antennz often plumose
in males; wings usually long and small; the larva of Core-
thra has thread-like anal gills, four dorsal gill vesicles on the
back, and no fatty bodies. Ctenophora has in the male
comb-like teeth on the antennz. ‘Tipula has very long legs.
The larve of Sciara sometimes wander in quantities in damp
ground, following each other in chains. Cecidomyia cereale
is the Hessian fly, which destroys grain. Heteropeza (Miastor)
is the form in which Metagenesis is described. The larva of
Ptychoptera has a long cephalic breathing tube.

Order 12. Lepidoptera—wings four, covered with small,
coloured, imbricated scales; mouth suctorial; thoracic rings
united; maxillz united, elongated as a spiral anélia or
suctorial tube, spirally rolled when not in use. The labrum
and mandibles are aborted, and the labium is modified. The
antenna is many jointed, club-like, filiform, or pectinate ;
eyes large; ocelli two or none. The maxillary palp is short,
two-jointed, but the labial is always large. The prothorax is
collar-like; the wings are radially veined. They have a suck-
ing stomach, a convoluted intestine; six malpighian tubes,
three of which may open together. The ovaria are usually four
tubes, with a receptaculum, and a large bursa copulatrix. The
larve are coloured, often hairy, with 5-6 ocelli on each side,
and prolegs behind thesix anterior. There are never prolegs on
the first, second, seventh, or eighth abdominal segments, so
there may be only 5-7 pair. The pupz are obtected; but

Introduction to Animal Morphology. Alt

the angular chrysalis case is marked with surface lines, isolat-
ing areas called Opthalmo-, Ptero-, Podo-, and Cerato-thece. The
surface scales have a short, easily broken pedicle of attach-
ment. A natural classification of the Lepidoptera is a desidera-
tum; but theyare often grouped, according to size, into Micro-,
and Macro-lepidoptera. The former are minute, with bristle-
like antennz, often pectinate in the males, diurnal or nocturnal,
with naked or sparsely-haired cocoon-spinning larve, with 4-5,
rarely three, pair of prolegs. Another method of division is into
Rhopalocera, or those with the antennz club-like, and Hetero-
cera, with variable antenne. The families are :—1. Ptero-
phoride—legs long; wing slit into feather-like plumes;
larve with five pair of prolegs. 2. Tineidz—labial palps
long, scaly; maxillary often long, many-jointed, very often
linear, pointed, or fringed ; larve tubicolous; live on buds
and branches (Lithocolletis). Tinea pellionella (clothes moth)
and sarcitella live in woollen fabrics ; T. uvella in grapes;
T. granella in corn. The females of some are wingless.
3. Tortricinide—proboscis short; larva with five pair of pro-
legs, living in rolled up leaves. 4. Pyralidz—with large labial
and maxillary palps; hinder wing with, at its border, a
bristled retinaculum. The Macro-lepidoptera have large
broad, or long narrow wings, and are nocturnal, crepuscular,
and diurnal forms. The nocturnal have the wings expanded,
one colour predominating; when at rest roof-like, or rolled
in to the body; larve with 2-5 pairs of prolegs. 5. Pha-
lenidz—ocelli none; body slender; antennz bristle-like,
or pectinate; proboscis small; wings delicate, with a retina-
culum, caterpillars with 2-3 pair of prolegs. The larva of
Apterus betularius, causes the tufts on birch trees. 6. Noc-
tuidee—body short, thick, conical; proboscis long, and palps
large ; fore-wing small, with two distinct spots; hinder joined
to fore bya retinaculum ; tibia spurred; larvz usually naked.
There are three types:—1. Geometriformes often diurnal,
with broad wings; larve with rudimental abdominal feet.
z. Noctuine with naked larve. Trachea piniperda de-
stroys pine trees. 3. Bombyciformes—with hairy caterpillars.
7. Bombycidz—body thick, woolly; antennz shortly pecti-
nate; proboscis weak; wings sometimes absent (Psyche), or

412 Introduction to Animal Morphology.

abortive (Orgyia) in the females; caterpillars with five pair of
prolegs, naked or hairy. ‘Those with no retinaculum are
Saturnia, Bombyx, the silk-worm moth, &c.; those with a
retinaculum are Psyche, the female of which lives in a spi-
rally coiled caddis-like case, &c. Allied-hereto are the Cossi,
wood-borers, with no ocelli; wings closely scaly, the front one
much the larger; and Hepialus, with equal long-pointed
wings; found on the root of the hops. There are two fami-
lies of Crepuscular Lepidoptera. 8. Chelonarida—antennz
clavate, often pectinate in males; proboscis spiral; wings
small, the foremost often spotted, with a retinaculum; ocelli
rarely absent (Glaucopis). 9. Sphingide—antennz prisma.
tic, three-angled, thin at the point; body fusiform, often
brightly coloured; fore-wing large, triangular, hinder short ;
larve with five pair of prolegs, smooth, with a horn above the
anus. Macroglossa is truly diurnal. Acherontia, the death’s
head moth, is so called from the skull-like figure on the
back. The diurnal forms are rhopalocerous—having hairy,
clavate antenne ; they have no ocelli; large wings, brightly
coloured on both sides, vertically folded on the back when at
rest; the larve are often spiny; the pupe are flat, angular,
with no cocoon. The families are: 10. Hesperidze—larve in
rolled up leaves; imago small ; thick-headed; with two pair
of spurs on the hind leg; wings small and thin. 11. Papilio-
nide: Butterflies—wings large, hard, usually of equal breadth,
and with no retinaculum. This large family has been divided
into two groups: 1. Succincta—pupz with the head directed
upwards, surrounded by a sling: this includes—§ 1. Equi-
tes—hind-wing usually tailed; fore-wing with four cost
on the inner side of the discoidal space. The females of
Parnassius have at the distal end a pouch, formed of the
hardened cases of adherent spermaphores. § 2. Pierines—
fore-wing with three longitudinal coste; hind-wing not
tailed. Ageronia has rudimental fore-legs. Group 2. Sus-
pensee—pupz suspended by a thread, with the head down-
wards. § 3. Danainz—fore-legs rudimental; palp diver-
gent, short. § 4. Heliconinz —fore-legs rudimental ; palp
longer than head, divergent. § 5. Acrainze—fore-legs per-
fect: palp divergent. § 6. Nymphalinee—fore-limbs rudi-

Introduction to Animal Morphology. 413

mental, with fringed tarsus; palp large; both wings broad.
§ 7. Morphinee—fore-leg small, not fringed ; palp small; wings
broad. § 8. Satyrinze—fore-leg small; antennz delicate ;
palps closely approximated; wings ocellated. § 9. Liby-
theine—palp as long as, or longer than thorax, thick,
straight ; fore-limb small in male, perfect in female. § 10. Ery-
cinine—palp small, with naked end-joint; fore-leg pefect.
§ 11. Lyceninz —fore-leg small; palps long; caterpillars
flat, short and broad; eyes of imago, hairy (Thecla), or
naked.

Order 13. Coleoptera: Metabolous—four-winged, with a
free large prothorax; and the anterior pair of wings (elytre)
hard, fully chitinized, and covering the succeeding pair;
head mostly recept, with two compound, and rarely any sim-
ple, eyes; antennz variable, 6-30 jointed; mandibles chiti-
nous ; maxillze often leathery, with an aborted inner lamella;
maxillary palp four-jointed; labial three-jointed; ligula un-
divided; mentum overlaps the labrum proper; mesothorax
weak, with a scutellum, and bearing the elytre; metathorax
strong, bearing the functional wings. ‘The elytrz have three
margins; the inner is usually straight (except in Meloé, &c.)
Where they touch medio-dorsally they form a suture, along
which they may be adherent, when the hind pair of wings
are functionless (e/y/re connata). ‘The hinder edge may
form an apex, or may be shortened (e. dreviata), so as
not to cover the posterior abdominal rings, when they are
called ¢. ¢runcata; when their inner edges do not touch they
are e. dehiscentia, or, if they overlap, e. complicantia. The
hind-wing has its costze mostly longitudinal, and it is folded
longitudinally, and once or twice transversely, so as to lie
when at rest completely under the elytron. The costz often
disappear in the wings of smallspecies. The legs are gressorial
or cursorial, rarely swimming, and more rarely leaping. The
intestine is tortuous in the vegetable feeders, shorter, but
more differentiated, in carnivorous forms. The penis is
long, horny, covered with a sheath, and retractile. The Malpi-
ghian tubes are four short, or six long. The nerve-chain con-
sists of three thoracic, and fouror five abdominal ganglia, which
may be more orless fused. The ovaries are fascicular tubes. A

414 Introduction to Animal Morphology.

few (Staphylinide) are viviparous; the larve are usually
naked, hexapod, or footless, rarely with ocelli; the pupz
are exserte. A few larve (Meloé, Rhipidius, Metoecus, Lytta),
are parasites. In Sitaris and Meloé there is a doubled larval
stage. About 83,000 species are known, of which 10,000 are
European.

They are divisible into the following Sub-orders :—

Sub-order 1. Cryptotetramera—mostly with a four-jointed
tarsus, the penultimate joint being small. This includes
four families :—1. Endomychide—head long; abdomen 5-6-
ringed ; larve living in fungi. 2. Coccinellidz : Lady Birds—
head short; body short, convex; flat beneath; antennz
short, eleven-jointed. 3. Pselaphidze—elytre only covering
part of the abdomen. 4. Trichopterygide—antenne eleven-
jointed, thread-like ; wings with long marginal hairs.

Sub-order 2. Crypto-pentamera—tarsi five-jointed, but the
penultimate joint very small. 5. Bruchide—head long, with
a thick neck; abdomen with five ventral rings; often found
in leguminous pods. 6. Curculionide—head prolonged into
a proboscis ; cesophagus long; jaws at the tip of the snout;
antenne arising in lateral grooves ; meso- and metathoracic
ganglia fused. About 10,000 species are described. 7. Bos-
trichide—body small; head thick, short; mandibles pro-
jecting ; palps small; eyes elongate, lateral; antenne with
swollen ends. The larve destroy the wood and bark of
trees in which they burrow. Hylurgus and Hylesinus thus
destroy the tips of the branches of pine trees. Scolytus and
Tomicus are also destructive, the former especially to elms.
8. Longicornes (Cerambycidz)—body elongated; head pro-
minent; antenne as long as, or longer than the body, usually
eleven-jointed; mandible large, usually with a single point.
g. Chrysomelide: Gold Beetles—eyes lateral; antennz mo-
derate, thread-like, usually eleven-jointed ; mandible with a
forked point; larvee with long legs, and ocelli. Some col-
lect their excreta in their back, or form it into a shell, which
they drag along. 10. Erotylide—like the last, but with a
flat, 3-4-jointed club at the end of the eleven-jointed an-

tenne.
Sub-order 3.—Heteromera—pro- and mesothoracic limbs,

Lntroduction to Animal Morphology. 415

with five-jointed tarsi ; metathoracic limb, with four large tarsal
joints. This contains: 11. Tenebrionide—often wingless ;
mandibles short, strong ; antenne 1ro-11-jointed ; elytra often
connate ; many have an ammoniacal smell, or are coated over
with a sort of surface secretion ; Blaps, the churchyard-beetle,
Tenebrio, the meal-worm, often found in ships’ biscuits,
belong here. 12. Lagriarie—antenne eleven-jointed, free,
pre-ocular; palps larger than the head; prothorax twice as long
as the mesothorax ; larve hairy, with four ocelli on each side.
13. Salpingida—head horizontal, free, not narrowed at base ;
antennze clubbed at end; otherwise as last; larve with
horny plates on eachsegment, and five pair of ocelli. 14. Py-
rochroide—antenne thread-like, or pectinate (Pyrochroa) ;
head recept; larve with enormous penultimate segment,
and two pair of ocelli. 15. Melandryade—antenne pre-
ocular, thread-like, maxillary palp with large end seg-
ment; larve with five pair of ocelli; living in dead wood.
16. Mordellide—body long, wedge-shaped ; head vertical ;
maxillary palp with a knife-like terminal joint; mandible
with a membranous margin internally; eggs large, oval.
17. Rhipiphoride—palps with single joints; mandible with
no membranous margin; antennz serrated in females, pecti-
nated often in males. The larve of Metoecus paradoxus live
in wasps’ nests, that of Rhipidius blattarum in the abdomen
of Blatta. 18. Cantharidide—antennz 8-11-jointed; head
and neck smaller than the soft, leathery elytra. The body
secretes a pungent blistering substance (Cantharidine). In
some forms the eggs are deposited in the nests of bees, and
emit hexapod bristled larve, which are endoparasite. This
larva moults, becomes free, then pupiform, emits a second
larve of different shape, from which the pupa, and finally
the imago, arise. This is called Hypermetamorphosis (/aéve).
Cantharis, the Spanish fly, or blistering beetle, belongs here.
Sitaris is in its larval stage parasitic in Anthophora pilipes.
Meloé, the oil beetle, has rudimental wings. 19. G‘deme-
ride—longicorn-like, with heteromerous tarsus, and a softer
surface clothing ; larve hairy, warted.

Sub-order 4: Pentamera—tarsi of all limbs five-jointed.
This includes: 20. Carabide—body long, convex, hard,

416 Introduction to Animal Morphology.

often metallic in lustre; antenne thread-like, eleven-jointed ;
mandible sharply curved; intestine with two anal glands,
whose secretions contain butyric acid. Brachinus crepitans,
the bombardier beetle, expels this forcibly, together with air,
when disturbed. The elytre are sometimes connate. An-
ophthalmus, a cavern form, is blind. The larve are long,
sometimes hairy. Procerus includes the largest known spe-
cies. 21. Cicindelide—slender, often lively-coloured, spot-
ted, or bald; head broader than neck ; maxillary palps with
terminal hooks ; larve linear, with broad head and prothorax ;
often with the eighth ring broader and higher than the others,
and with two fleshy dorsal processes. 22. Amphizoide—hairy ;
the fore-limbs gressorial; the costz of the hind-limbs approxi-
mated, flattened, as in the next family ; outer edge of the
maxilla with an unjointed process. 23. Dyticidse—flat, aqua-
tic, oval, with thread-like, eleven-jointed antenne : hind-legs
flat, oar-like ; the neck has lateral odoriferous glands. The
intestine has an appended cecal sac, with many transverse
folds. In swimming, the hind legs move simultaneously
(Dyticus, &c.), or alternately (Pelobius). 24. Gyrinide—
eyes divided by the edge of the head into an upper and
lower series; antennz short; hind-leg short, fin-like; they
swim in circles, and fly as the last; larve centipede-like,
with lateral abdominal appendages, and mouth as last.
Some are marine as well as fresh water. 25. Hydrophi-
lide—oval or semi-circular, with broad swimming hind-
feet; antenne six- (Sperchus) nine-jointed (Hydrophi-
lus, Hydrobius); club-shaped; palps as long as antenna.
These beetles are recommended by Professor Klein as the
best animals wherein to trace the structure of muscular
fibres, and nerve endings therein. 26. Staphylinidz (Brache-
lytra)—body long; elytrz short; hind-wing folded; antennz
10-11-jointed ; males sometimes heteromerous ; larve like the
perfect insect, with two hinder bristles to the abdomen, and
a tubular anus ; stomach, villous internally, preceded by a pro-
ventricle with chitinous ridges. 27. Pausside—antennz 2—-10-
jointed, clavate; head trigonal; tarsus four-jointed; elytra
long four-angled, with a fold at the outer angle ; ventral rings
four. 28. Hysteride—antennz retractile, short, bent, the

Lntroduction to Animal Morphology. 417

three last joints dilated; tortoise-like beetles, which, when
caught, feign death. 29. Silphidz : Carrion beetles—antennz
clubbed ; ligula bilobed ; abdomen of six free moveable seg-
ments; anterior and middle legs with conical basal joints. Lep-
toderus from the Adelsberg cave is eyeless. 30. Scaphididae—
small, fungicolous ; antennz with a clubbed or capillary end ;
basal joint of fore-limb cylindrical ; abdomen with a conical
point. 31. Phalacridae—small, oval, convex, with a small fourth
tarsal joint; abdomen with five free rings. 32. Nitidularide—
small, with antenne clavate; legs short; maie tarsi often
heteromerous. 33. Colydide—antennz clubbed, tarsus four-
jointed ; the last or last pair of the five ventral rings alone
are moveable; the body has a sculptured surface. 34. Cucuji-
dz—body compressed, with moniliform (Cucujus), or clavate
(Silvanus), or thread-like antenne (Brontes); all the five
ventral rings free. 35. Cryptophagide—antennze with a
1-3-jointed terminal club ; tarsi five- (Cryptophagus), rarely
three- or four-jointed ( Mycetophagus). 36. Dermestidae—
-antenne short, retractile; a single frontal eye. Anthrenus
museorum is the pest of entomological cabinets. The
larva of Dermestes lardarius is the bacon grub. 37. Byrr-
hide—oval ; tibia folds into the femur like a penknife.
38. Parnide—antennz clubbed, with retractile head; aquatic,
but without swimming feet, and with a silky clothing, and a
_varnish-like coating. 39. Scarabeide (Lamellicornes)—
antenne short, the first joint large, the last three, or more,
forming a lamellated club; eyes lateral. Dynastes has the
clypeus united to the forehead, and the mandibles un-
covered (sheathed in Cetoniew, &c.) Melolontha, the
cockchafer, is found on the leaves of sycamore, and other
trees, to which it is very destructive. Ateuchus sacer was
the sacred Scarabeeus of the Egyptians. Geotrupes is the
dung beetle. Lucanus and its allies have comb-shaped an-
tenne. 40. Buprestide—bright-coloured, long, flat beetles,
with serrated antennz ; short legs; eyeless larve ; ceca are ap-
pended to the stomach or proventricle, and often to the
cesophagus (Anthaxia). 41. Eucnemide—cylindrical, with
retractile antennz, globular femora on the fore and middle
pairs of legs; labrum indistinct. 42. Elateride—long, de-
2

418 Introduction to Animal Morphology.

pressed ; labrum distinct; legs with linear tibiz ; prothorax
with a chin process, directed forwards, and a basal spine
fitting into a groove in the mesothorax; by this they can
spring when laid on their back. Pyrophorus noctilucus is
the firefly, emitting light from two spots on the thorax. The
larva of Agrites segetum is the wire-worm dreaded by agri-
culturists. 43 Cebrionidze— mandibles sickle-like; legs.
fossorial; prothoracic process bent upwards; larve like
those of last. 44. Rhipiceride—antennze between the eyes.
45. Cyphonide—mandibles short; ligula membranous, large.
46. Malacodermata—soft-skinned, leathery; females often
wingless ; mandibles short ; tibize rarely with a terminal spine ;
this includes Lampyris, the glow-worm. The light-organ
consists of a delicate-walled capsule, including polygonal
cells, inclosed in a finely granular mass, and situated in the
abdomen. The luminous rings are clear, waxy-like externally.
Lamprocera, from S. America, has feeble light organs. Phos-
phzenus has both sexes wingless. 47. Clerida—moderately
large, with slender body, and membranous or horny ligula.
48. Xylophaga, wood-borers—cylindrical; head often co-
vered by the neck-shield. Lymexylon navale is destruc-
tive to oak woods.- Anobium pertinax, the ‘‘ death-watch,”
makes its sound by striking with their jaws against wood-
work; Ptilinus pectinicornis bores in books; Ptinus fur, the
herbarium beetle, devours dried plants.

Order 14. Hymenoptera—wings four; naked, membra-
nous, few-veined; fore pair larger; prothorax small, annu-
lar, as in Lepidoptera and Diptera, united with the
mesothorax on the dorsal side, while its ventral part, which
articulates with the head, remains free ; females with an
ovipositor; head free, with two large compound eyes, and
usually three frontal ocelli; mandibles strong; maxille and
labium united, and sometimes extended as a proboscis ; both
pair of maxille are freely articulated, allowing of their retrac-
tion; and the mentum is smaller than the palpigerous region
of the labium ; paraglossz are also often largely developed ;
the antennz often consist of a basal scape, and a terminal
funiculus of 11-12-jointed linear joints, or may be of many

Introduction to Animal Morphology. 419

filiform segments; maxillary palps with six,—labial with
four joints. The nervation of the wing is shown in the
sketch. The eight or nine-jointed abdomen may be nearly
sessile, but when of fewer segments Fig. 42.

it joins the metathorax by a narrow
stalk (petiole). There is in the female
post-abdominally often an aculeus
inclosed in two valvule, or within
a tube (terebra). The salivary glands — wing of Hymenopteron:
are prape-like in bees, &c.; the sto- 3,2» humeral cells, 3) 4,5:

‘ first, second, and third cubital
mach is long, annular, and complex; ells; 6, radial cell; 7,8, dis-

coidal cells; ¢ cubital veins;
and in ants there is a gizzard. The 4, radial veins.
short vasa malpigit may be many score. The female has no
bursa copulatrix, but there is a receptaculum seminis, with an
appendicular gland. Many have two post-abdominal glands,
simple or branched, opening into a common vesicle, whose
duct ends in a sting, by which they pierce the nerve
cord of insects, on which their larve feed. The tracheze
often dilate into vesicles, especially about the base of the
abdomen. The meso- and metathoracic ganglia are fused, as
are often the last pair of the 5-6 ventral ganglia. The larve
have 6-8 pair of pedes spurt?, as well as the ordinary feet in
some, while others are footless. The saccular stomach is
at first aproctous, as the intestine does not communicate
therewith until after the first moult.

There are three sub-orders :—I. Aculeata—sting-bearers ;
larvee aproctous; eyeless, footless, abdomen petiolate. This
includes, 1. Apiaridze: Bees—wings not folded; anterior
with two or three (Bombus) cubital cells; sting barbed ;
maxillary sheath elongated, knife-like ; labium suctorial.
The basal joint of the hindermost tarsus is flattened, and
often bristled, to collect pollen for the food of the larve.
Many of the females are workers. They form hexagonal cells
for their young, of wax, or (as Anthophora, &c.) of foreign bo-
dies, glued together by saliva. Some bees lay their eggs in
the nests of others (like cuckoos). Apis mellifica is the com-
mon honey-bee, whose female is the queen bee, and whose
young are cared for by females with rudimental sex-organs

Z2E2

420 Introduction to Animal Morphology.

(workers). Osmia makes thimble-like cells. Xylocopa, car-
penter-bees, cut passages in old wood. 2. Vespide, Wasps—
often naked; antenne slender, notched and bent; eyes reni-
form; prothorax elongated to the wing roots ; maxillz often
leathery; wings longitudinally folded. They are solitary, or co-
lonial, and the latter have workers, like those of bee colonies.
The nests are of paper-like vegetable pulp. Vespa and Po-
listes are the ordinary social wasps, whose colonies consist
often of workers, until the end of the season, when the males
and females appear. In the latter genus parthenogenesis oc-
curs. Polybia and Epipone chartaria build large conical nests
in S. America. Eumenes, Odynerus, and other solitary ge-
nera build clay nests. 3. Crabronide—antenne short, not
bent; mandibular palp, six,—labial, four-jointed ; forewings
not folded, narrow; sting not barbed, nor broken on being
used. The female either kills prey to feed her larve (Bem-
bex), and brings it to them daily, or paralyses other larve by
injuring their nerve-cord, and brings them in numbers into
the nest, providing the young at once with enough food for
their whole larval state (Cerceris, Sphex, &c.) Tachytes isa
cuckoo wasp, like the nomade bees, laying eggs in the nests
of Sphex. 4. Pompilide, Sand wasps—antenne long; pro-
thorax stretching to the wing roots; wings large, broad, the
fore with three cubital cells; legs spiny. 5. Heterogyne—
sexes dimorphic ; females wingless (Mutilla, &c.), or nearly
so (Sapyga, Myzine, &c.); mostly parasitic on other Hyme-
nopters. 6. Chrysidide—metallic coloured, with bent 13-
jointed antenne; 3-4-ringed abdomen; one cubital cell on
the forewing. 7. Formicidz, Ants—colonial; maies and fe-
males winged, but workers apterous, with small thorax, eyes,
and no ocelli; an anal gland, secreting formic acid, which
acts as an irritant. Some feed on the sweet, honey-like sub-
stance which they suck from Aphides. Formica rufa, the
red ant, builds ant-hills; Polyergus holds individuals of other
species as captives in its nest; Myrmecocystis has a globular
abdomen ; Atta cephalotes is the visiting ant of S. Ame-
rica.

Sub-order z. Entomophaga—trochanter biannulate ; ab-

Introduction to Antmal Morphology. 421

domen petiolate. The females lay their eggs with an ovipo-
sitor or terebra, covered by two valves, in Fig. 43.

the bodies of the larve of other insects,
in whose cavitiesthefootlesslarve,when
hatched, are endoparasitic. 8. Chal-
cidide—antenne bent, 4-6-jointed ;
terebra ventral; prothorax not elon-
gated to the wing-root. Blastophaga
is an agent in fertilizing figs. 9. Cy-
nipide, Gall-flies—antenne thread-
like, 13-16-jointed ; abdomen com-
pressed. Cynips lays eggs in oak
leaves and branches, forming nut-galls.
Rhodites forms the “‘ Bedeguar’ on Pi
roses. Synergos (a cuckoo form) lays Apocrypta paradoxa. A fig
eggs on the galls of Cynips. 10. Proc- Psi
totrypide—antenne straight or elbowed, 10~15-jointed,
rarely 8; minute black parasites. 11. Ichneumonidze—thin,
long, antenne many-jointed, thread-like; terebra terminal,
straight ; abdomen attached to the upper side or to the end
(Ichneumon) of the metathorax.

Sub-order 3. Phytophaga—abdomen sessile; ovipositor
saw-like ; larve with more than six feet, and proctuchous.
1z. Tenthredinide, Saw-flies—antennz thick at end; 3-30-
jointed; metathorax with a deep notch above; eggs laid
under the epidermis of leaves. Nematus lives in willow
leaves. Tenthredo, the saw-fly, is common on roses, and the
larva of one form, Athalia centifolia, is often destructive to
turnips (Nigger caterpillars). 13. Uroceride, tailed or wood
wasps—antenne straight, thread-like, 11, 24-jointed; abdo-
men cylindrical, nine-ringed, with prominent terebra.

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ABATUS, 143.
Abdominalia, 345.
Abiogenesis,, 9.
Ablastica, 79.
Abranchia, 239.
Abranchiata, 299, 303.
Abyla, 98.

Abyssal zone, 44.
Acanthin, 8, 13, 60.
Acanthobdella, 198.
Acanthobdellidz, 203.
Acanthobothrium, 171.
Acanthocephala, 187.
Acanthochiasmine, 63.
Acanthocystis, 59.
Acanthodesmiacez, 62.
-Acanthodoris, 305.
Acanthometra, 60.
Acanthometridz, 60, 63.
Acanthospongia, 78.
Acaridz, 372.
Acarina, 371,

Acarus, 365, 372.
Acephala, 160-255.
Acera, 311.

Aceridz, 160.
Acetabula, 385.
Achatina, 312.
Achatinella, 312.
Acherontia, 412.
Acheta, 404.
Achtheres, 348.
Achorutes, 402.
Aciculina, 311.
Aciculidze, 311.
Acineta, 69.
Acinetina, 69.
Acmostomum, I61.
Acoetes, 220.

SOLE X ;

Acreinz, 412.
Acraspeda, 102.
Acrididz, 389, 404.
Acrocyst, 93-
Acroloxus, 295.
Acrophalli, 185.
Acrosoma, 375.
Actzonia, 293, 306.
Aczonide, 306.
Actineria, 115.
Actinia, 114.
Actiniadze, I14.
Actiniine, I14.
Actinocephalus, 65.
Actinodendron, 115.
Actinomma, 63.
Actinophryna, 58.
Actinophrys, 56.
Actinopsis, 114.
Actinopyga, 148, 153.
Actinospheerium, 59.
Actinotrocha, 192.
Actinozoa, 109.

Actinozoa, development of, in time,

Actinula, go.

Aculeata, 419.

Acura, 304.
Adambulacral pieces, 134.
Adamsia, 114.

Adductor muscles, 261.
Adelocodonic, 86.
Adelsberg cave, 356, 362.
Adenopleura, 364-6, 373.
Adeorbis, 307.

Adjustor ventralis, 250.
LE ga, 362.

fE gina, 95.

fEgineta, 9o.

424 Index.

AR ginide, 95. Ameeba, 2, 57.
/Eginopsis, 90, 95. Ameebide, 57.
LEolide, 283, 291, 304. Ameeboid motion, 2.
fEolis, 291. Amouroucium, 234, 241.
fEquorea, 94. Amphibia, 46.
AZ quoride, 94. Amphibiotice, 405.
4fschna, 405. Amphibola, 311.
A&theria, 260. Amphicorina, 223.
Agalma, 99, 100. Amphiceteis, 223.
Agalmopsis, 100. Amphicteneidz, 223.
Agamogenesis, 35. Amphidetus, 147.
Agassiz, 69, 89, 95, 96, 106, 108, | Amphidiscs, 76.

109, 128, 137. Amphileptus, 66, 71.
A gassizia, 148. Amphiline, 171.
A gathistegia, 51. Amphilinide, 171.
Agelacrinus, 128-9. Amphinomide, 220.
Ageronia, 412. Amphinome, 220.
Aglaisma, 98. Amphipeplea, 312.
Aglaura, 220. Amphipoda, 337, 359-
Agnatha, 288, 312. Amphiporide, 164.
Agrion, 405. Amphiptyches, 171, 203-
Ale, 257, 345. Amphiroa, 98.
Ale, cordis, 354. Amphistoma, 173, 176.
Alastor, 68. Amphistomide, 176.
Albertia, 198. Amphitrema, 58.
Albumen, 6. Amphiura, 131.
Albuminoids, 1. Amphizoide, 416.
Alcinoe, 106. Amphizonella, 57.
Alciope, 221. Ampullaria, 295.
Alcippe, 345. Ampullariide, 310.
Alcyonacez, 118. Amussium, 268.
Alcyonaria, 118. Anacharis, 421.
Alcyonidz, 110, 119. Anal valves, 319.
Alcyonidiide, 229. Analogous, 12.
Alcyonium, 119. Anatinide, 257, 271-
Alecto, 131. Anatomus, 307.
Aleurodes, 400. Anceus, 361.
Alleogenesis, 91. Anchinia, 240.
Allmann, 81, 90, 93, 94, 229. Anchorella, 348.
Alpheus, 356. Ancillaria, 281.
Alternation of generations, 90. Ancistropus, 193.
Alula, 407. Ancorina, 77.
Alveopora, 116. Ancula, 294.
Amblyomma, 373. Ancylus, 295, 296, 312-
Amblyura, 184. Ancyracanthus, 184.
Ambulacra, 124, 141. Andrena, 419.
Ambulacral system, 124. Androphores, 99.
Ambulacral brains, 127. Anelasma, 346.
Ametabolica, 398. Angiostomum, 184.
Ametabolous, 397. Angle-band, 97.
Ammonites, 315. Anguillula, 181-4.
Ammonitide, 325. Anguillulidae, 184.
Ammothea, 119. Animal tissues, 9.

Ammotrypane, 222. Animal matter in bone, 17-

Animal, characters of, 24.

Anisoscelis, 402.
Anisodactylus, 416.
Annelida, 209.
Annulata, 154.
Annuloida, 126.
Anobium, 418.
Anochanus, 146.
Anocelis, 160.
Anodonta, 269.

Anomia, 259, 260, 262, 263.

Anomiade, 268.
Anomoura, 338, 358.
Anopla, 163.

Anoplosomatum, 182, 193.

Antalis, 275.
Antarctic ocean, 44.
Antartic region, 42.
Antedon, 131.

Antenna, 194, 330, 322, 388.

Antennaria, 95.
Antennules, 330.
Anthaxia, 417.
Anthea, 114.
Anthelia, 119.
Anthocephalus, 171.
Anthocotyle, 174.
Anthophora, 419.
Anthomyia, 409.
Anthophysa, 55.
Antimeres, 11.
Antipatharia, 117.
Antipathes, 118.
Antipathide, 117.
Antlia, 410.
Antlion, 391, 405.
Ants, 420.
Anurea, 197.
Anus, 30.

Aonis, 224.
Apate, 417.
Aphaniptera, 407.
Aphantocheilus, 374.
Apharyngeide, 161.
Aphididz, 398.
Aphides, 383.
Aphis, 391.
Aphkrocallistes, 78.
Aphroditide, 219.
_ Aphrodite, 220.
Aphrophora, 400.
Apiariz, 419.
Apical areas, 107.
Apical pores, 106.

Index. 42

Lor

Apis, 419.

Aplidium, 234, 241.
Aplysia, 221, 289, 290, 305.
Aplysiide, 305.

Aplysina, 76.

Aplustridz, 306.
Apneumona, 152.
Apneusta, 290.

Apoda, 345.

Apoderus, 417.

Apolemia, 99, 100.
Apolemiadz, foo.
Aporosa, 116.

Aporus, 419.

Aporrhais, 308.
Appendicularia, 231, 232, 234, 235-

238.
Appendiculariidz, 230.
Aprocta, 161.

Apsilus, 198.
Apterus, 411.

Apus, 330, 338, 350.
Aquiferous pores, 320.
Arachnactis, 114.
Arachnide, 368, 371.
Arachnoidea, 46, 363.
Arachnopathes, 117.
Arachnosphera, 62.
Aradus, 401.
Aralo-Caspian region, 43
Araneide, 374.
Araneina, 374.
Arbaciide, 147.
Arca, 261, 262, 269.
Arcacez, 269.
Arcella, 4, 57-
Arcellidz, 57.
Archeodiscus, 55.
Archzostomata, 48, 155.
Archaster, 135.
Archebiosis, 9.
Archer, 50, 57, 59-
Archinauplius, 360.
Architecture of Cancelli, 19.
Architeuthis, 326.
Archizoéa, 360, 370.
Arcidz, 269.

Arctia, 412.

Arctic ocean, 44.
Artisca, 371.
Arcturus, 362.
Arenicola, 222.
Arenicolidz, 222.
Arenicolites, 47.

426

Arenospongia, 77.
Areolar tissue, 15.
Areole, 18.

Argas, 372.

Argentea externa, 322.
Argentea interna, 321.
Argonauta, 283, 315.
Argonautidz, 326.
Argulinidze, 348.
Argulus, 330, 348.
Argus, 374.

Argyroneta, 374.
Arhagea, 162.

Arhynchea, 161.
Ariciide, 222.
Aricia, 222.

Arion, 283, 296, 311.
Arista, 407.

Arm of Cephalopods, 317.

Arm supports, 248.
Armadillo, 362.
Armadillidium, 362.
Armata, 193.
Arnstein, 14.
Artemia, 351.
Arteries, 32.
Arterial blood, 32.
Arthracantha, 198.
Arthrogastra, 375.
Arthronomalus, 382.
Arthropoda, 47, 327.
Articulamentum, 307.
Articulata, 130.
Articuli, 307.

Arum, 92.
Asbjornsen, 134.
Ascaridz, 185.
Ascaris, 185.
Ascidia, 237, 240.
Ascomorpha, 197.
Ascones, 78.
Asellidze, 362.
Asellus, 362.
Asiliidze, 409.
Aspergillum, 257, 271.
Aspidisca, 72.
Aspidobranchiata, 301.
Aspidocephalus, 184.
Aspidochir, 153.
Aspidochirotz, 150.
Aspidogaster, 172.
Aspidosiphon, 193.

Index.

Aspidosiphonide, 193.
Asplanchna, 197.

-Astacidze, 355.

Astacus, 354-5.
Astarte, 269.
Astartidze, 269.
Astasia, 55.
Astasiidee, 55.

Asteracanthion, 127, 136, 137.

Asterina, 137.
Asterinide, 137.
Asteroide, 134.
Asteromorpha, 133.
Asteronyx, 133.
Asteroporpa, 133.
Asteropsis, 137.
Asteroschema, 133.
Asthenosoma, 138.
Astrea, 117.
Astreeaceze, 117.
Astreidz, 117.
Astreeinz, 117.
Astreeopora, 116.
Astrangiacea, I17.
Astrogonium, 137.
Astrolithinz, 63.
Astropecten, 127, 334.
Astropectinidz, 137.
Astrophyton, 133.
Astropyga, 138-9.
Astrorhiza, 53.
Atax, 373.
Ateuchus, 417.
Athalia, 421.
Athorybia, 99, 100.
Athorybiadz, 100.
Atlantic ocean, 45.
Atlantidze, 294, 306.
Atolls, 118.

Atta, 420.

Atropos (Troctes), 400.

Atypus, 374.
Atys, 305.

Auditory organ (insects), 383.

Audouinia, 222.*
Aulacantha, 62.
Aulacanthide, 62.
Aulacognatha, 288, 312.
Aulacostomum, 201, 204.
Auliskia, 77.
Aulophora, 116.
Aulosphera, 62.

* By mistake spelled Andoninia, 222.

Aurelia, 103, 105.
Auricles, 257.
Auricula, 281.
Australian region, 42.
Australian province, 44.
Autarachna, 371.
Autolytus, 221.
Autoplasts, 324.
Aves, 46.

Avicula, 257.
Avicularia, 225.
Aviculidz, 268, 312.
Axial skeleton, 19.
Axinella, 73.

Axis cylinder, 22.
Axohelia, 117.
Axophyllinz, 115.

Bacillus, 903.
Bacteria, 403.
Bacterium, 9.
Baddeley, 56.

Baer, V., cavity of, 37.
Bailey, 69

Balanidz, 345.

Balanidz, nerves of, 337.

Balanoglossus, 157.
Balantium, 279.
Balantidium, 71.
Balanus, 345.
Balatro, 198.
Baphia, 269.
Barbala, 269.
Barrier reefs, 118.
Basal plates, 130.
Basipodite, 330.

Basogenic budding, 113.

Basommatophores, 302.
Bastian, 9.

Bate, Spence, 354.
Bathybius, 49, 62.
Baudelot, 199.

Baur, 136.

Baxt, 24.

Bdella, 373.

Bdellidz, 373.
Bdellura, 161.

Beak of cuttlefish, 318.
Beale, 14.

Bees, 36, 383.
Beeswax, 8.

Bela, 308.

Belemnites, 314.
Belonella, 119.

Index.

Belosepia, 314.
Bembex, 420.
Beneden, Van, E.,

427

Beneden, Van, P. i 2 34, 158, 164,

168, 175, 2258 228.
Beroé, 107, 108.
Beroidz, 108.
Bhawania, 220.
Biesiadecki, 3.
Bifora, 268.
Bile, 30
Bilharzia, 176.
Bimeria, 92.
Bimeride, 92.
Binnenblase, 60.
Biogenesis, 9.
Bioplasm, 2.
Bipalium, 155, 160.
Bipinnaria, 136.
Bird’s bones, 19.
Birgus latro, 356.
Bithynia, 291.
Bivalves, 243.
Bivium, 147.
Bizzozero, 19.
Blabera, 403.
Bladder, 14, 20.

Blainville, 193, 247, 255, 279-

Blaps, 415.
Blastocheme, 87, 93.
Blastocyst, 176.
Blastoderm, 37.
Blastoidex, 128.
Blastostyle, 87, 90.
Blattidz, 403.
Blatta, 103.

Blind crustaceans, 356, 362.
Blood, 18, 33.
Boderia, 58.

Bodo, 55.
Boettcher, 5.
Bohadschia, 153.
Bojanus, 180, organ of, 262.
Bolina, 104, 107.
Bolinidze, 109.
Bolinopsis, 109.
Boltenia, 234.
Bombus, 179, 419.
Bombylius, 409.
Bombyliidz, 409.
Bombyciformes, 411
Bombycide, 411.
Bombyx, 411.

Bone, 17.

428 Index.

Bonellia, 193.
Bopyridz, 361.
Bopyrus, 361.

Borelide, 54.

Borlasia, 161, 162, 163.
Bosmina, 350.
Bostrychide, 414.
Bothriocephalus, 170.
Botryllidz, 240.
Botryllinz, 240.
Botrylloides, 241.
Botryllus, 232, 239, 249.
Botryocampe, 62.
Bouchardia, 249, 254.
Bougainvillea, 92.
Bougainvillide, 92.
Bowerbankia, 226.
Brachelytra, 416.
Brachinus, 416.
Brachiolaria, 136.
Brachionidz, 197.
Brachionopoda, 247.
Brachionus, 198.
Brachiopoda, 46, 247.
Brachycera, 409.
Brachystomata, 409.
Brachytarsus (Curculionide), 414.
Brachyura, 367.
Branchellion, 198, 201, 204.
Branchie, 33.

Branchial sac, 233.
Branchiata, 20, 303.
Branchiobdella, 198, 202.
Branchiobdellidz, 203.
Branchiogasteropoda, 303.
Branchipus, 350.
Branchiopoda, 349.
Branchiopnoa, 329.
Branchiostegites, 355.
Branchiules, 225.
Brandtidz, 95.

Brandt, 104, 225.
Braulide, 408.

Brazil province, 44.
Bredichin, 19.
Brettauer, 14.

Breynia, 147.
Briariacee, 121-3.
Briareus, 123.

Brisinga, 134.

Brisin goidez, 134.
Brissopsis, 139, 145.
Brissus, 148.

Bristles in Mollusca, 242, 250, 281.

Brittlestars, 131.
Bronn, 240, 247, 272.
Brontes, 417.
Bruch, 56.
Bruchide, 414.
Briicke, 6.
Bryozoa, 46.
Bubnoff, 16.
Bucephalus, 176.
Buccinide, 309.
Buccinum, 289, 290.
Buhl, s.
Buliminiz, 54.
Bulimus, 312.
Bulla, 305.
Bullidz, 305.
Buprestidz, 417.
Burmeister, 342.
Bursaria, 66, 67.
Bursaride, 71.
Bursatella, 305.
Busch, 56, 108.
Busycon, 283.
Butic acid, 8.
Butter, 8.

Butyric acid, 8.
Byrrhidz, 417.
Byssanodonta, 269.
Byssus, 260, 286.
Byssus gland, 261.

Cabestana, 289,
Cacospongia, 77.
Czeca, 30, 144, 332.
Cecide, 86.
Czecum, 310.
Czecum of Cephalopods, 318-
Ceenis, 405.
Calanidze, 341.
Calanus, 347.
Calappa, 358.
Calcar, 194, 385.
Calcarina, 50.
Calceola, 115.
Calcispongia, 78.
Calcium fluoride, 7.
Caliginide, 346-8.
Caligus, 348.
Calma, 304.
Callepteryx, 405.
Callianidea, 355.
Callianira, 108.
Callicotyle, 175.
Callidina, 147.

Index.

Calliopzea, 304.
Calliophora, 409.
Calvert, 9.

Calycella, 94.
Calycinaria, 102.
Calycophoridz, 96.
Calycozoa, IOI.
Calycular buddings, 113.
Calymmidz, 109.
Calyptoblastea, 93.
Calyptrea, 282, 310.
Calyx, III.

Cambrian period, 46.
Caminus, 77-
Campaniclava, 9I.
Campanularia, 94.
Campanularide, 93, 99.
Campanulina, 94.
Campanulinide, 94.
Canaliculi, 18.

Canals Ctenophoral, 106.
Cancellariide, 309.
Cancellous tissue, 18.
Cancer, 357-
Cantharidee, 415.
Cantharis, 415.
Canthocamptus, 347,
Capitella, 219.
Capitulum, 407.

Capnea, 114.

Caprella, 337.
Caprellidz, 357.
Capsidz, 401.
Capsulide, 310.
Capulus, 289, 310.
Caput, 384.

Carabide, 387, 415.
Carbonic acid, 7. i
Carbonicacid, action or protoplasm,
Carboniferous period, 46.
Carchesium, 70.
Carcinus, 357.

Cardiidz, 270.

Cardinal teeth, 256.
Cardita, 269.
Cardiopoda, 306.
Cardium, 260, 270.
Cardo, 384.

Carduella, 102.
Carenocerzeus, 160.
Carenota, 160.
Carididz, 355.

Carina, 345.

Carinaria, 242, 290, 296, 306.

429

Carinella, 163.
Carinellidz, 163.
Carinolateral plate, 340.
Carmarina, 86, 90, 95.
Carmine, action on protoplasm, I.
Carpenter, 24, 56.
Carpenteria, 50, 52.
Carpopodite, 330.
Garters (575674.
Cartilage, 16.

Cartilage hinge, 256.
Cartilage in Cephalopoda, 316,
Cartilage in Medusz, 88.
Carus, 91, 93, 237.
Carychium, 312.
Caryophyllzidz, 171.
Caryophylleus, 171.
Caryophylliidz, 116.
Caryophyllia, 116.
Casein, 7.

Casella, 305.

Cassidaria, 289, 308.
Cassidulina, 142.
Cassidulinidz, 147.
Cassiopeia, 104.
Cassiopeiide, 104.
Cassis, 295, 308.
Castalia, 221.
Catacysta, 142.
Catallacta, 57.
Catenicellidze, 230.
Catenulide, 161.
Caterpillar, 397.
Caterpillar, muscles of, 390.
Catometopa, 357.
Caudal ear of Mysis, 340.
Cavernularia, 121.
Cavolina, 279.

Cavum pulvinare, 287.
Cebrionidz, 418.
Cecidomyia, 396, 410.
Celine ois:
Cellephobe, 108.
Cellular tissue, 15.
Cellulose, 8.

Cement gland, 333.
Cenia, 313.

Central capsule, 60.
Centrotus, 400.
Cephalic grooves, 158.
Cephalobranchiata, 222.
Cephalocarena, 60.
Cephalogaster, 352.
Cephalophora, 46, 277.

430

Cephalopoda, 46, 242, 313.

Cephalostegite, 353.
Cephalota, 160.
Cephalothricidz, 163.
Cephalothrix, 162.
Cephea, 105.
Cepheidz, 105.
Cerabranchiata, 294, 304.
Cerambycide, 387, 414.
Ceraospongia, 76.
Cerapus, 360.
Ceratium, 69.
Ceratothecz, 411.
Cercariz, 176.
Cerceris, 420.

Cerci anales, 386, 403.
Cerebratulus, 162-3.
Cerebrin, 7.
Cerianthidze, I14.
Cerianthus, 114.
Cerithidea, 286.
Cerithiidee, 309, 310.
Cermatiide, 382.
Cerolein, 8.

Cerotic acid, 8.
Cestidze, 109.
Cestodea, 164.
Cestum, 106-7.
Cetochilus, 347.
Cetonia, 347, 417.
Cetylic Palmitate, 8.
Cheetaster, 137.
Cheetodermide, 193.
Cheetognatha, 183, 206.
Cheetonotus, 218.
Cheetopterus, 219.
Chzetosoma, 183, 207.
Cheetospira, 72.
Chalcidize, 420.
Chalcophora, 322.
Chalk formation, 46.
Chalina, 76.

Chama, 256, 257.
Chamacez, 270.
Chamidez, 270.
Chamostrea, 256.
Chapman, 129.
Charybdea, 105.
Charybdeeidze, 105.
Cheiletus, 369.
Cheilospirula, 184.
Cheiracanthidze, 184.
Cheiracanthus, 181.
Cheiroteuthus, 325.

index.

Chele, 352.
Cheletropus, 276, 303.
Chelicerze, 375.
Chelifer, 376.
Chelonaridz, 412.
Chelura, 361.

Chelyosoma, 231, 232, 233, 240.

Chemnitzia, 312.
Chermes, 36, 400.
Chiajea, 107, 108, 109.
Chiajean organ, 290.
Chilodon, 71.
Chilodontide, 71.
Chilognatha, 377.
Chilopoda, 377, 382.
Chilostomata, 229.
Chinese province, 43.
Chiorzera, 304.
Chirocephalus, 350.
Chirodota, 150, 152.
Chironomus, 257, 408.
Chitin, 8, 327.

Chiton, 292, 297, 298, 302.
Chlamidocephalidz, 162.
Chlamidocephalus, 162.
Chlamydomyxa, 50.
Chloéia, 220.

Chloeon, 389, 394.
Chlorzema, 222.
Chlorophyll, 155-7.
Chondracanthide, 348.
Chondrilla, 77.
Chondrin, 7.
Chondrophora, 325.
Chondrophore, 256.
Chondrostachys, 240.
Chonetidze, 248.
Chonostomum, I61.
Choricotyle, 174.
Choroid plexus, 13.
Chromatophores, 242, 313-
Chromic acid, 16.
Chrysalis, 397.
Chrysaora, 105.
Chrysididz, 420.
Chrysis, 390.
Chrysogaster, 386.
Chrysomelide, 414.
Chrysomitra, 107.
Chrysopa, 4006.
Chthamalus, 345.
Chthonascidiz, 240.
Cicada, got.

| Cicadellidze, 400.

Cicadidz, 401.
Cicindela, 416.
Cicindelide, 416.
Cidaridz, 146.
Cidaris, 146.
Cienkowsky, 50, 56, 61.
Ciliary motion, 2.
Ciliata, 71.
Cimbex (Tenthredinidz), 421.
Cimex, 397, 401.
Cinclides, 112.
Circulation in Cephalopods, 319.
Circulation in Crustacea, 334.
Circulation in Insects, 393.
Circulation in Leeches, 207.
Circulation in Molluscs, 245.
Circulation in Nemerteans, 157.
Circulation in Gephyrea, 190.
Circulatory system, 31.
Cirolana (Cymothoidze), 362.
Cirrhatulidz, 222.
Cirrhopathes, 118.
Cirrhostomidz, 184.
Cirrhoteuthis, 314.
Cirripedia, 338, 343-
Cladobranchiata, 304.
Cladocera, 350.
Cladococcide, 62.
Cladocoracez, I17.
Cladocoryne, 92.
Cladocorynide, 92.
Cladodactylus, 183.
Cladolabes, 150, 153.
Cladonema, 92.
Cladonemidz, 92.
Cladoxenus, 403.
Claparéde, 69, 90.
Clark, 258.
Class, 38.
Classification, 38.
Clathria, 76.
Clathrulina, 58.
Clausilia, 282, 301, 312.
Clausilium, 286.
Clavagella, 257, 267,2 71.
Clavatella, 88, 89, 92.
Clavatellidz, 92.
Clavellina, 234, 240.
Clavellinidz, 240.
Clavidee, 91.

(

Clavularia, 119.
Cleodora, 275, 277, 278.
Clepsine, 199, 203.

Index. 43

Clepsinidz, 203.
Cleridz, 418.

Cliodita, 279.

Cliona, 77.

Clione, 276, 277, 278, 279.
Sa a
Clionopsis, 278, 279.
Clistosyca, 78.
Clistosaccus (Rhizocephala), 346.
Clithon, 308.

Cloquet, 188.

Clubione, 368, 374.
Clupeoids commensal, 117.
Clymene, 219.
Clypeaster, 147.
Clypeastridze, 147.
Clypeastrine, 147.
Clypeus, 330.

Clytia, 94.

Cnidz, 74, 80, 193, 281, 242.
Coagulation of blood, 6.
Coartactee, 397, 408.
Coccidee, 341, 399.
Coccina, 383.
Coccinella, 414.
Coccodiscinz, 63.
Coccoliths, 62.
Coccospheres, 62.
Coccus, 400.

Cochineal, 400.
Cocoon, 144, 397.
Codonella 70.
Codonostome, 87.
Coelenterata, 47.
Ccelogorgia, 123.
Cceloma, 31, 124.
Ccenis, 405.

Ccenobita, 557.
Ccenocyathus, 116.
Ccenurus, 168.
Coenosare, 79.
Coenosyca, 78.

Cohn, 9, 57, 68.
Cohnheim, 2, 23.
Colacium, 55.
Coleoptera, 387, 413.
Colepide, eh is
Coleps, 71.

Collagen, 15.
Collingwood, 114.
Collosphzeridz, 61, 62.
Collozoum, 63.
Colobocentrotus, 147.
Colobranchus, 213, 222.

432 Index.

Colodendridz, 60, 63.

Colonial nervous system, 227.
Colones, II.

Colpocaphelus, 162.
Colpocephalum (Mallophaga), 399.
Colpoda, 71.

Columbella, 309.

Columella, 112, 285.

Columellar lobe, 285.
Columellaris musculus, 272, 289.
Columnar epithelium, 13.
Colydiide, 417.

Comarocystis, 124.

Comatula, 127.

Coriside, 401.

Corixa, 401.

Cormopoda, 260.
Cornucopiz organs of Synapta, 149.
Cornula, 400.

Cornularia, 119.
Cornulariide, 119.
Cornuspira, 50.
Cornuspiride, 53.
Coronula, 345.
Corpuscles, 32.

Corpus ciliare, 323.
Corpus epitheliale, 323.
Correlations of growth, 39.

Comatula, parasite of, 175.
Comatulidz, 131.
Commensalism, 46.
Comminutores ciborum, 143.
Complementary males, 292.
Conchiolin, 8.

Conchoderma (Lepadidz), 345.

Concholepas, 309.
Conchospiral, 283.
Conide, 304.
Conocheilus, 197.
Conocephalus, 184.
Conodictyum, 53.
Conodontes, 47.
Conopide, 408.
Conorhinus, 401.
Contractile vesicle, 48, 67.
Conularide, 279.
Conulinidz, 54.
Conus, 289, 298, 308.
Convoluta, 161.
Copepoda, 346.
Cophosyca, 71.
Coppinia, 94.
Coppiniidee, 94.
Coral composition of, III.
Coral, conditions of, 118.
Coral reefs, 118.
Coralliacez, 123.
Coralline zone, 44.
Coralliophila, 247.
Corallite, 111.
Corallium, 123.
Corallum, III.
Corbis, 259, 263, 264.
Corbula, 93, 256.
Corbulide, 271.
Corda, 83.
Cordylophora, 90, 91.
Corethra, 410.

Corrodentia, 404.
Corti, rods of, 23.
Corticium, 77.
Corticate, 77.
Corycia, 57.
Corymorpha, 93.
Coryne, 95.
Corynidez, 91.
Corynactis, 114.
Corystes, 357.
Cosmocerca, 185.
Cossus, 412.
Coste, III, 385.
Cothurnia, 70.
Cotylidz, 164.
Cotylorhiza, 105.
Coxa, 385.
Coxopodite, 330.
Crabs, 353.
Crabro, 420.
Crabronide, 420.
Crambesside, 105.
Cranchiide, 325.
Crangon, 356.
Crangonyx, 339.
Crania, 247, 248.
Craniide, 254.
Craspeda, I12.
Craspedosoma, 379.
Craspedota, 96.
Crassatella, 264.
Crenatula, 264.
Crepidula, 282, 310.
Cribrella, 137.
Cribrina, I14.
Crickets, 389.
Crioceras, 315.
Criodrilus, 218.
Crinoidea, 129, 46.
Crisiadze, 229.

Cristatellide, 224.
Cristellaria, 54.
Cristellariidz, 54.
Crossostoma, 104.
Crucibulum, 310.
Crustacea, 46, 329.
Cryptodon, 260.
Cryptomonas, 55.
Cryptonisus, 361.
Cryptophaga, 417.
Cryptophagide, 417.
Cryptophialus, 345.
Cryptopentamera, 414.
Cryptops, 305.
Cryptoplax, 308.
Cryptotetramera, 414.
Crystal style, 259, 292.
Crystallodes, 100.
Cteniza, 374.
Ctenobranchiata, 308.
Ctenocella, 122.
Ctenocyst, 117.
Ctenodiscus, 127, 135, 136.
Ctenomeres, 106.
Ctenophora, 106.
Ctenophora, 410.
Ctenophores, 106.
Ctenosomata, 229.
Cucujide, 417.
Cucujus, 417.
Cuckoospit, 400. _
Cucullanidz, 183.
Cucullanus, 180, 183.
Culcita, 137.
Culicidze, 410.
Cultelli, 407.

Cuma, 358.
Cumaceze, 358.
Cumingia, 270.
Cunina, 89, 90, 91, 95.

Cuplike organs, leeches, 260.

Cupula, 165.
Curculionide, 387, 414.
Curculio, 414.

Cursoria, 403.

Cuticle, 13.

Cuttlefishes, 325.

Cuvier, 241, 275, 311, 388.
Cuvieria, 148, 163.
Cuvierian organs, 156.
Cyamide, 359.

Cyamus, 359.

Cyanea, 105. ‘
Cyathaxonia, 115.

Index. 433

Cyathocrinus, 130.
Cyatholiths, 62.
Cyathophyllide, 115.
Cyathophyllinz, 115.
Cyathozooid, 127.

Cyclas, 258, 259, 260, 266, 267, 270
Cyclatella, 175.

Cycles of Septa, 112.
Cyclidium, 71.
Cyclidinidee, 71.
Cyclobranchiata, 294, 306.
Cyclocentric, 283.
Cyclolinidz, 54.
Cyclometopa, 367.
Cyclops, 347.

», parasite of, 67.
Cyclopidz, 346.
Cyclopsine (Canthocamptus), 347.
Cyclostegia, 51.
Cyclostomata, 229, 311.
Cylichna, 305.
Cylindrella, 311.
Cymba, 301.

Cymbulia, 277, 278, 285.
Cymbuliade, 275.
Cymodocea, 275, 362.
Cymothoa, 362.
Cymothoidz, 362.
ue 421.

ynthia, 232, 234, 236, 240.
Cyphoderia, See ae
Cyphophthalmus, 375.
Cypreea, 389.
Cyprzeidee, 308.
Cypridina, 349.
Cypris, 349.
Cyprinaceze, 270.
Cyprinz, 270.
Cyrenida, 270.
Cyrtidze, 62.
Cyrtodaria, 256.
Cyrtolithus, 306.
Cysticze, 170.
Cysticercoidea, 170.
Cysticercus, 169.
Cystic worms, 168.
Cystidz, 47, 129.
Cystidez, 128.
Cystiphyllideze, 115.
Cystoopseadz, 183.
Cystophrys, 69.
Cythere, 349,
Cytherea, 206.
Cytocormi, 11.

2

434

. Cytode, 5.

Cytogenous tissue, 15.
Czajewicz, 10.

Dacnitis, 184.
Dactylocalyx, 74.
Dactylogyra, 163.
Dactylopodite, 331.
Dactylopora, 53.
Dactylota, 153.
Dalyell, 113.

Daphnia, 350.

Dart of Helix, 301.
Darwin, 41, 344, 345
Dasmiide, 116.
Dasydytes, 218.
Daudebarda, 311.
Davaine, 266.
Decapoda, 325, 353.
Decollate shells, 295.
Deiters, 23.

Delle Chiaje, 175.
Delphinula, 307.
Deltidium, 248.
Demodex, 372.

De Morgan, 18.
Dendritina, 54.
Dendrochirote, 153.
Dendroccela, 160.
Dendroccelum, 163.
Dendrocometes, 69.
Dendrodoa, 233, 240.
Dendronereis, 221.
Dendronotus, 282, 300, 303, 304.
Dendrosoma, 38.
Dendrostomum, 193.
Dendrostyle, 104.
Dentalina, 69.
Dentalinidze, 275.
Dentalium, 273, 274.
Dentes, 287.
Depastrum, 102.
Depilatory glands, 300.
Depuratory organs, 26.
Dermal bones, 19.
Dermal glands, 33, 364.
Dermanyssus, 373.
Dermatobranchiata, 303.
Dermaptera (Euplexoptera), 402.
Dermestes, 417.
Dermobranchiata, 293.
Dermosclerites, 121.
Dero, 220.
Derostomum, 161.

Index.

Deslongchamps, 135.
Desmacella, 74.
Desoria, 402.
Deuterostomata, 48, 206.
Deuterozooids, 35.
Development of Cartilage, 17.
> of animals in time, 46.
Devonian formation, 46.
Dexiotrope, 283.
Dextral, 283.
Diadematide, 147.
Diakonow, I.
Diaphanocephalus, 186.
Diaphoropodon, 59.
Diaptomus, 347.
Dias, 327.
Diazona, 233, 241.
Dibaphus, 308.
Dibothnia, 170.
Dibothnum, 170.
Dibranchiata, 325.
Dicelis, 160.
Diceras, 256.
Dichelestidz, 348.
Dichelestium, 348.
Dichitonida, 232.
Dicoryne, 88, 91.
Dicorynide, 91.
Dictyocystideze, 70.
Dicyemidze, 117.
Dicystidea, 65.
Didemniinz, 241.
Didemnium, 231, 241.
Didymophyes, 65.
Diesing, 65, 171, 176, 179.
Diesingia, 193.
Differentiation, 26.
Difflugia, 57, 58.
Digenea, 175.
Digenesis, 35.
Digestive canal of Brachiopoda, 227.
,, of Bryozoa, 226.
a ,, of Chzetognatha, 207.
i ,, of Crustacea, 332.
of Gasteropoda, 290.
of Lamellibranchiates,
259.
Leeches, 201.
A ,, of Molluscs, 245.

bP)

a 5, of Rotifera, 195.
+» 5), Of Synapta, 149. _
9 ,, of Trematodes, 177.

+ 5, of Tunicates, 233.
Diglena, 197

Dimya, 261.
Dinemura, 348.
Dinobryon, 56.
Dinocharis, 196, 197.
Dinophilus, 161, 155.
Dioecious, 34.
Diopatria, 220.
Diopsis, 389.
Diotis, 161.
Diphyes, 98.
Diphyide, 98.
Diphyllide, 170.
Diphyozéoids, 98.
Dipleurobranchiata, 294, 306.
Diploblastica, 74.
Diploconidz, 63.
Diplogaster, 174.
Diplohelicoid, 284.
Diplophrys, 57.
Diplophysa, 98.
Diplosphzera, 62.
Diplospiral, 284.
Diplotrocha, 197.
Diplozoon, 174.
Dipneumona, 153.
Dipneumones, 374.
Diporus, 171.
Diptera, 389.
Dirhagea, 163.
Discidz, 62.
Discina, 248-9.
Discinide, 254.
Discophora, 102.
Discospirinide, 63.
Disdiaclasts, 20.
Diselmis, 35.
Disoma, 222.
Disorus, 161.
Dispharagus, 186.
Distoma, 176.
Distomide, 176.
Distomus, 241.
Distribution of animals, 42.
Ditela, 76.
Ditrupa, 223.
Diurna, 412.
Divaricatores, 250.
Dochmius, 186.
Docoglossata, 307.
Dolabella, 305.
Doliidz, 308.
Doliolidz, 240.
Doliolum, 231, 232, 237.
Dolium, 289, 308.

Index.

Dolomedes, 375.
Donacidz, 270.
Donax, 265.
Donders, 24.

| Donitz, 238.
Dorataspis, 60, 63.
D’Orbigny, 61.
Doridea, 305.

| Dorippe, 358.
Doris, 281, 291.
Dorthesia, 400.

| Dorylaimus, 184.
Dosinia, 270.
Doto, 354.
Dotonidz, 291.
Doxococcus, 55.
Doyérean papillz, 23, 388.
Dragon flies, 393.
Drassus, 368, 374.
Dreissena, 260, 261.
Dromia, 357.
Dromiidz, 257.
Driicklinien, 19.
Dryodea, 108.
Dujardin, 50, 371.
Dujardinia, 221.
Dumortier, 227.
Dysasteridz, 147.
Dysdera, 374.
Dysidea, 76.
Dyspeptone, 7.
Dysteleology, 41.
Dysteria, 72.
Dysteride, 72.

| Dyticus, 391, 416,

Ear in Crustacea, 329.
» in Insecta, 388.
5, in Mollusca, 299.
5, in Cephalopoda, 322.

Eberth, 2, 13.
Eberhard, 69.
Ecardines, 253, 254.
Eccyliomphalus, 306.
| Ecderon, IIo.
Echeneiobothrium, 170.
Echinarachnius, 142.
Echinaster, 137, 134.
Echinidz, 147.
Echiniscus, 371.
Echinobothrium, 170.
Echinocardium, 147.

BV Ys

Earthy matter of bone, 17.

4

5

436 Index.

Echinococcus, 169. Embryogeny of Ophiuride, 132.
Echinocucumis, 150. 55 ofconnective tissue, 15.
Echinodermata, I1, 46, 47, 123. Empide, 409.
Echinoidea, 137. Emydium, 371.
Echinometridz, 147. Enallostegia, 51.
Echinoneus, 142. Enchelide, 71.
Echinopora, 117. Enchelidium, 184.
Echinopyxis, 58. Enchelys, 71.
Echinorhynchus, 65, 188. Enchytrzeus, 220.
Echinosoma, 152. Encope, 147.
Echinospira, 303. Enccelium, 241.
Echinotzenia, 169. Encrinide, 130.
Echinus, 147. Enderon, 110.
Echiurus, 184, 191, 193- Endocardines, 257, 267.
Ectoderm, 79, I10. Endocyclica, 146.
Ectolitha, 62. Endoderm, 79.
Ectoparasites, 40. Endogenous cell formation, 5.
Ectoplasm, 67. Endolitha, 62, 63.
Ectosarc, 56. Endomychide, 414.
Ectostosis, 19. Endoparasite, 40.
Ectotheca, 86. Endoplasma, 67.
Edible bird’s nest, 8. Endopodite, 332.
Edriaster, 129. Endosarc, 56.
Edriophthalmia, 358. Endostosis, 19.
Edwards, 117. Endotheca, 86, III.
Eggs of Gasteropods, 302. Endothecal dissepiments, 112.
Ehlers, 190, 206. Engelmann, 3, 4.
Ehrenberg, 193. Enopla, 164.
Eimer, 14, 74, 107. Enoploteuthis, 326.
Eleocrinus, 128. | Enoplus, 184.
Elaphocephalus, 184. | Enteroccela, 48, 206.
Elastin, 8. Enteropneusti, 207.
Elater, 392. Entoconcha, 37,152, 247, 291, 293.
Eledone, 326. Entoconchidz, 350.
Eleutheroblastea, 81- Entolitha, 62.
Eleutherocrinus, 128. Entomostegia, 51.
Elysia, 284, 291, 293, 300- Entomostraca, 342.
Tlysiide, 304. Entozoa, 177.
Elytron, 385, 413. Eocene formation, 46.
Elytrophora, 348. Eosaurus, 47.
Emarginula, 2, 282, 292, 307. Eozoon, 52, 53, 54-
Embide, 404. Epaulettes, 146.
Embryogeny of Arachnida, 370. Epeira, 364, 375-

* of Brachiopoda, 253. Ependyma, 13.

Fs of Bryozoa, 228. Ephemeride, 391.

# of Corynidz, 95. Ephemera, 393.

< of Crinoidea, 130. Ephippium, 350.

es of Echini, 146. Ephyra, 193, 104.

w of Gasteropoda, 302. Epibdella, 175.

‘ of Hydra, 82. Epiblast, 37.

ns of Insecta, 396. Epiccela, 48.

am of Mollusca, 298. Epidermis, 13.

3 of Myriopoda, 380. Epiglottis, 17.

of Nemertinea, 165. Epimera, 329.

[ndex. 437

Epipharyngeal ganglion, 264.
Epipharynx, 390.
Epiphragm, 276,
Epiphysis, 143.
Epipodia, 275.
Epipodites, 354.
Epipyxis, 56.
Epistome, 225, 330.
Epistylis, 70.
Epitheca, 111.
Epithecal dissepiment, 112.
Epithelium, 13.
Eresus, 375.
Erganzungstiicke, 142.
Ergasilidz, 347.
Erichson, 388.
Erpocotyle, 175.
Errantia, 219.

Ervilia, 270.
Erycinide, 413.
Escharide, 413.

Eschscholtz, 96, 98, 107, 104, 1006.

Eschscholtzia, 107, 108.
Esperia, 78.

Ethal, 9.

Ethiopian province, 42.
Ethmospheeride, 62.
Euaxes, 218.
Eucecryphalus, 62.
Eucharis, 108-9.
Euchlanidz, 197.
Euchlanis, 197.
Eucnemide, 417.
Eucope, 94.
Eucorybas, 382.
Eucyrtidium, 62.
Eudendridee, 92.
Eudendrium, 90, 92.
Eudoxia, 98.
Euechinoidea, 146.
Euglena, 35.
Euglypha, 57, 58.
Eulima, 247.
Eumenidz, 420.
Eunicea, 122.
Euphausia, 337.
Euphrosynidz, 121.
Euphrosyne, 121.
Euphylliacez, 117.
Euplectella, 78.
Euplexoptera, 402.
Euplotes, 72.
Eupsammidez, 116.

Eupyrgus, 152.

Eurhamphza, 107.
European province, 43.
Euryalide, 132.
Euryleptide, 160,
Eurystemma, 171.
Eurystomata, 108.
Eustrongylus, 186.
Evadne, 350.
Evolution theory. 40.
Exocardines, 268.
Exocyclica, 147.
Exopodite, 331.
Exoskeleton, 27.
Exotheca, IIT.
Eyelids of Echini, 145.
Eyes of Arachnida, 364.
», of Cephalopoda, 362.
» of Crustacea, 340.
», of Enoplus, 186.
5, of Gasteropoda, 298.
», of Gephyrea, 190.
5, of Insecta, 389.
», of Meduse, 89.

Fabricia, 221.
Facelina, 300.
Facies, 384.
Faivre’s experiments, 336.
Family, 38.
Farrella, 228.
Fasciculata, 229.
Fascicola 140.
Fasciolaria, 309.
Fat, 16.

Fatty body, 366.
Faviacea, 117.
Favositidee, 96, 115.
Femur, 308.
Fibrillar tissue, 15.
Fibrin, 6.
Fibrinogen, 6.
Fibrinoplastin, 6.
Fibro-cartilage, 16.
Fibula, 308.
Fierasfer, 152.
Filament, 97.
Filaria, 187-8.
Filaride, 185.
Filaroides, 185.
Filograna, 220.
Filurus, 304.

Fins of Pteropoda, 275.
Fiona, 296, 304.
Fionidz, 291.

438 Index.

Firoloidea, 306.
Fission, 5.
Fissurella, 292, 307.
Fissurellide, 307.
Flabellum, 304.
Flagellata, 25, 55.
Flagellum, 23, 355-
Flata, 400.
Fleming, 128, 232.
Flemming, 16.
Flitterchen, 313.
Floriceps, 169.
Floscellus, 147.
Floscularidz, 197.
Fluke, 176.
Flustridz, 230.
Focke, 59.
Foot, 243.
Foot, canals of, 260.
5) wCOlal a
», muscles of, in Molluscs, 260.
5, of Scaphoda, 274.
Foraminifera, 54.
Foramina repugnatoria, 379.
Forbes, 46, 207.
Forewing, 385.
Forficula, 402.
Formica, 420.
Formula of Conchospiral, 283.
Forskalia, 99, 100.
Free cell formation, 5.
Freia, 72.
Fremy, 5-
Frey, 16.
Fringing reefs, 118.
Frondicularia, 54.
Frons, 384.
Fulgora, 400.
Fulgorida, 400.
Fungia, 117.
Fungiade, 117.
Fungine, 117.
Funiculina, 121.
Funnel, 316.
Fiirstenburg, 14.
Fusulina, 51.
Fusus, 309.

Gabelstiicke, 143.
Galathea, 356.
Galatheide, 356.
Galeodea, 376.

Galeodes, 363, 366, 269.
Galeomma, 256, 259, 360-

Galeommidz, 269.
Galerites, 142.
Galeritidee, 147.
Galgulide, 401.
Gamasus, 366, 373.
Gamasidez, 373.
Gammaride, 360.
Gammartus, 360.
Gamogenesis, 36.
Ganglion, 23.
Ganglion stellatum, 34.
Gas, evolution of, 4.
Gasterocotyle, 174.
Gasterodela, 196.
Gasteropoda, 280.
Gasterostoma, 177.
Gasterotomum, I72.
Gastracantha, 281, 375.
Gastric juice, 30.
Gastrochena, 247, 286.
Gastroparietal septum, 251.
Gastropteron, 305.
Gastrotricha, 196.
Gastrovascular canals, 87.
Gastrula, 37, 72.
Gecarcinus, 337, 357-
Gegenbaur, 5, 16, 39, 109, 153, 207,
254.
Gegenbauria, 108.
Gelatin, 7.
Gellina, 304.
Gemellariadz, 230.
Gemmation, 5.
Gena, 307.
Genz, 38.
Generalized types, 38.
Genus, 38.
Geocores, 401.
Geodia, 77.
Geodiide, 72.
Geographical distribution, 42.
Geomalacus, 296, 311.
Geomelania, 311.
Geometriformes, 411.
Geophilus, 379, 382.
Geoplana, 161.
Geotrupes, 417.
Gephyrea, 154, 189.
Gerda, 69.
Gerhardt, 7.
Gerstzecker, 375.
Geryonia, 95.
Geryoninz,

95.
| Geryonidz, 88, 89, 91, 95-

Gianuzzi, 14.

Gills, 33, 263.
Gizzard, 226.
Glabella, 351.
Gland, 14, 242.
Glandina, 301.
Glaucide, 304.
Glaucoma, 67, 71.
Glauconomyide, 251.
Glaucopus, 412.
Glaucus, 303.
Glenodinium, 69.
Glenomorum, §5.
Globigerina, 51, 59.
Globulin, 6
Globulina, 51.
Glomeris, 378, 380.
Glomeridz, 381.
Glossata, 386.
Glossocodon, 95.
Glossoconus, 95.
Glucose, 8.
Glycerea, 122.
Glycerin, 7.
Glyciphagus, 373.
Glycogen, 9.
Gnathopods, 355.
Gnathostomata, 377.
Gnathosyllis, 121.
Goblet cells, 13.
Goldfuss, 47.
Goliathus (Scarabeide), 417.
Gonangium, 93.
Gongylonema, 185.
Goniatites, 315.
Goniocarena, 160.
Goniodoris, 305.
Goniognatha, 312.
Goniophyllum, 115.
Gonocheme, 86, 87.
Gonocalyx, 86.
Gonophore, 17.
Gonosome, 87.
Gonothyrzea, 94.
Goodsirea, 89.
Gordiacez, 178.
Gordiide, 178.
Gordius, 178.
Gorgonella, 122.
Gorgonellidz, 122.
Gorgonia, III.
Gorgoniacez, 121.
Gorgonide, 122.
Gosse, 56.

Index. 439

Grandry, 22.

Grant, 107.

Grantia, 78.
Graptolitidze, 47, IOT.
Greef, 58, 84, 133, 155.
Greene, 69.
Gregarinina, 61, 64, 65.
Gregarina, 61.
Gressoria, 403.
Griesinger, 176.
Gromia, 50.
Gromide, 53.
Grube, 146, 205.
Gryllidz, 404.
Gryllotalpa, 404.
Gryllus, 404.
Gryphza, 268.
Guancha, 74.

Guanin, 7.
Guineaworm, 185.
Guineean province, 43.
Gula, 384.

Gulliver, 296.
Gummina, 77.
Gummine, 77.
Guttulina, 56.
Gymnameebe, 49.
Gymnobranchiata, 244.
Gymnoblastea, $4.
Gymnocopa, 219.
Gymnocyte, 5.
Gymnocytode, 5.
Gymnoglossa, 288.
Gymnolemata, 229.
Gymnosomata, 277.
Gymnoteenia, 169.
Gymnotoma, 164.
Gynzecophorus, 176.
Gynophore, 49.
Gyrinus, 398.
Gyrocotyle, 171.
Gyrodactylidze, 174.
Gyrodactylus, 174.
Gyropeltis, 348.
Gyropus, 399.

Haeckel, 2, 5, 11, 25,'30, 41, 49,
51, 56, 61, 62, 70, 72, 91, 255,
379, 371-

Haeckelia, 108.

Heematopinus, 399.

Heementeria, 204.

Heemopis, 204.

Haimeia, 119.

440

Halcacampa, 114.
Haleciide, 94.
Halecium, 94.
Halelminthide, 219.
Halopsyche, 278-9.
Halichondria, 77.
Halicryptus, 191, 193.
Haligmus, 185.
Haliomma, 63.
Haliotidz, 307.

Haliotis, 281, 285, 295, 297.

Halisarcia, 76.
Halisceptrum, 120.
Halistemma, 99, 100.
Halobates, 4or.
Halonaidz, 219.
Halteres, 387.
Halteria, 70.
Hamiglossata, 288.
Haminea, 298.
Hamites, 315.
Hancock, 83.
Haplodactylus, 153.
Harless, 292.
Hartea, 119.
Harpa, 281, 389.
Harting, 8, 26.
Haughton, 41.

Haus Appendicularian, 231.

Haversian canals, 18.
Heart, 144, 245, 261.
Hectocotylus, 324.
Hedruris, 184.
Heidenhain, 6,

Heis, 283.

Helicidee, 311.
Helicosepina, 152.
Helicoidez, 35.
Helicostegia, 51.
Heliopora, 96.
Heliosphera, 62.
Heliozoa, 59.

Helix, 301, 312, 313.
Helmholtz, 24.
Helodrilus, 218.
Hemelytra, 399.
Hemerobius, 391.
Hemicyclia, 163.
Hemimetabolous, 397.
Hemiptera, 387, 391.
Hemipatagus, 148.
Hensen, 24.
Hepialidex, 412.
Heptabranchus, 305.

Lndex.

Hermzidz, 304.
Hermea, 314.
Hermann, 3.
Hermaphroditism, 34.
Hermella, 223.
Hermione, 220.
Heroidez, 304.
Hertha, 131.
Hesione, 213, 221.
Hesperiade, 412.
Heteractinism, 137.
Heterakis, 180, 185.
Heterocentrotus, 147.
Heterocera, 411.
Heterocheilus, 184.
Heterodactyla, 115.
Heterofusus, 276-7.
Heterogonism, 91.
Heterogyna, 420.
Heterogony, 35.
Heteromera, 414.
Heterometrus, 376.
Heteromorphic, 85.
Heteromya, 261, 268.
Heteronema, 65.

Heterophrys, 59.

Heteropoda, 15, 242, 281, 287, 298,
6

306.
Heteropoda tristicha, 151.
Heteroptera, 400.
Heteroplasty, 19.
Heterosabella, 223.
Heterostoma, 382.

‘Heterotricha, 66, 71.

Heterozoanthus, 114, 116.
Hexabranchus, 395.
Hexarthra, 196.
Hexactiniz, 113.
Hexactinelle, 78.
Hicks, 389.

Hincksia, 94.

Hinge of bivalves, 256.
Hinnites, 268.
Hippidz, 356.
Hippolyte, 330, 356.
Hipponyx, 310.
Hippopodiidz, 98.
Hippopodium, 98.
Hippopus, 270.
Hippothoide, 270.
Hippuritide, 268.
Hircinia, 77.
Hirudinea, 198.
Hirudinide, 204.

Hirudo, 199, 200, 201, 203, 204.
His, 14, 15.

Hislopea, 226.
Hislopeidz, 229.
Histioderma, 47, 224.
Histology, 12.
Histriobdella, 263.
Hoeven, Van der, 303.
Hoffmann, 144.
Holocystis, 115.
Holometabola, 297.
Holopedium, 330.
Holopus, 129, 130.
Holostomata, 308-9.
Holothuriada, 120, 148.
Holothuria, 153.
Holotricha, 66.
Holotrocha, 197.
Holtenia, 78.
Homalocerzeus, 150.
Homarus, 337, 355-
Homodynamic, 12.
Homeeopoda, I5!.
Homologous, II.
Homomorphic, 85.
Homomya, 261.
Homonomous, 12.
Homoplastic, 10.
Homoptera, 399.
Homotypical, 12.
Hoplophora, 373.
Hormiphora, 108.
Hoyer, 23.

Hubner, 64.
Hubrecht, 159.
Human parasites, 185.
Humphreysia, 257.
Huronian formation, 46.
Huxley, 72, 126, 155, 248.
Huxleya, 72.

Hyalea, 276.
Hyaleidz, 279.
Hyalomma, 373.
Hyalonema, 78.

Hyas (Oxyrhyncha), 357.
Hybocodonide, 93.
Hybocodon, 93.
Hydatids, 168.
Hydalina, 197.
Hydra, 22, 81.
Hydra, parasites of, 70.
Hydrachna, 373.
Hydractinia, 90, 92.
Hydractinide, 92.

L[ndex.

Hydranth, 85.
Hydra tuba, 103.
Hydride, 81.
Hydrobius, 395.
Hydrocaulus, 84.
Hydrocores, 401.

| Hydrocysts, 99.

Hydrodictyon, 4.
Hydrogen, 7.
Hydroida, 81.
Hydrolaride, 93.
Hydrophilus, 416.
Hydrophyllium, 98.
Hydrophyton, 85.
Hydrorhiza, 84.

| Hydrosoma, 81.

Hydrotheca, 93.
Hydrozoa, 11, 46, 81.
Hymenogorgia, 122.
Hymenoptera, 391.
Hyperidze, 361.

| Hypoblast, 37.

Hypogzeon, 219.

| Hyponome, 129.

Hypophalhi, 183.
Hypopharyngeal ganglion, 265.
Hypostome, 85, 350.
Hypotricha, 66.

Hystrichis, 187.

Ianthina, 281, 289, 298, 309.
Ibla, 342.

Ichneumon, 421.
Ichthydium, 166, 218.
Ichthyobdella, 202, 204.
Idalia, 305.

Idoscopic eyes, 27.
Idoteidze, 362.

Iduna, 72.

Idyia, 107-8.
Hleoparietal septum, 251.
Ilyanthus, 114.
Imaginal discs, 347.
Imago, 397.

Imbricate, 286.
Imogene, 160.
Imperator, 307.
Imperforata, 53.
Impregnation, 36.
Inachus, 357.
Inzequitelze, 375.

Incus, 195.

India, 44.

Indian province, 42.

441

442 Lndex.

Individual, 25. Knappert, 159.
Inermia, 192. Kober, 189.
Infusoria, 66. Koinosites, 40.
Inosite, 8. Kolliker, 77, 82, 251.
Insecta, 46, 383. Kophobelemnon, 121.
Integropalliata, 269. Kowalewskaia, 240.
Intermediate zone, 44. Kowalewsky, 191, 238.
Interpyramidalis, 143. Krakens, 321.
Interradial arch, 142. iSralsena 23.
Interradial plates, 130. Kraussia, 249, 254.
Intromittent organ, 309. Krober, 375.
Involucre, 91. Krohn, 109.
Involuntary muscle, 20. Kréoyer, 368.
Tone, 368. Kréoyeria, 348.
Iphione, 220. Kiichenmeister, 168.
Trregularia, 147. Kiuhne, 3, 66.
Ischiopodite, 330. Kupffer, 238.
Tsidacez, 122. Kuphus, 271.
Isididze, 122.
Isis, 122. Labial tentacles, 257, 265.
Tsocardia, 256. Labium, 330, 385.
Isogenetic, 35. Labrum, 351, 384.
Isogonism, 91. Labyrinthulez, 25, 50.
Isomya, 261, 269. Lac, 400.
Isopoda, 361. Lacaze Duthiers, 231.
Ixodes, 366, 371. Lacazia, 193.
Ixodide, 373. Lachmann, 69.
Lachnus, 400.
James Clark, 74. Lachrymaria, 71.
Janellidze, 311. Lactose, 8.
Janus, 292, 296. Lzmargus, 348.
Japanese province, 43. Lzmodipoda, 359.
Joseph, 24. Leevicardium, 270.
Joung, 2. Lafoea, 94.
Jourdain, 29, 127. Lafoeidz, 94.
Julus, 378, 381. Laganine, 147.
Juncella, 122. Laganum, 143.
Jurassic period, 46. Lagena, 50, 59.
Lagenidz, 54.
Keber, organ of, 262. Lagenella, 55.
Keferstein, 190, 191, 263. Lagenophrys, 68.
Kellia, 258, 266, 267, 270. Lagmiariz, 415.
Keratin, 7. Lagynis, 53.
Kerona, 72. Lamarck, 268, 358, 359.
Key, 23. Lambl, 188.
Kidney, 33, 195, 296, 320. Lamellibranchiata, 46, 255.
Kirchenpauer, 44. Lamellicornes, 388.
Kistiakowsky, 3. Lamina, 384.
Kittary, 360. Lamineze cribrosze, 127.
Klastoplasts, 329. Laminarian zone, 44.
Klebs, 20. Lampyride, 418.
Kleeberg, 296. Lampyris, 392.
Klein, 23. Land crabs, breathing of, 377.

Kleinenberg, 81. Langer, 322.

Index.

Lankester, 64, 76, 155, 322.
Lanter of Aristotle, 143.
Lantern flies, 4oo.
Laomedea, 94.
Laotrope, 283.
Lar, 85, 93-
Larinus, 9.
Larvee, 386, 396, 397-
» » antennze of, 398.
», Echinodermal, 162.
Lasea, 269.
Laterigrade, 375.
Latia, 312.
Latreille, 329, 347, 353, 254; 357)
359 361, 374+
Laurentian age, 32, 46.
La Valette, 36.
Law of Baer, 31.

5, of Haughton, 41.
Leach, 352, 358.
Lebonte, 7.
Lecanocephalus, 184.
Ledidz, 269.

Leda, 269.

Ledra, 400.
Leiopathes, 117.
Leiosoma, 373.
Lemniscus, 188.
Lepadella 197.
Lepadidz, 337, 344.
Lepas, 344.
Lepetidz, 207.
Lepidoptera, 386.
Lepisma, 387.
Lepismidze, 402.
Lepocyte, 5.
Lepocytode, 5.
Lepomonera, 49.
Leptaena, 255.
Leptonidz, 269.
Leptobrachidz, 104.
Leptobrachia, 104.
Leptoclinum, 241.
Leptodera, 182, 184.
Leptogorgia, 122.
Lepton, 257.
Leptoplana, 160.
Leptoscyphide, 94.
Leptoscyphus, 94.
Lemea, 347.
Lernzopoda, 348.
Leskea, 148,
Lespés, 188, 389.
Lesueuria, 109.

443

Letzerich, 23.

Leuciferinz, 358.

Leucin, 7.

Leuckart, 65, 66, 71, 96, 97, 101,
108, 109, 167, 170, 172.

Leucodoride, 221.

Leucones, 78.

Leucophrys, 71.

Leucosidez, 358.

Leucosolenia, 78.

Leydig, 16, 65, 83, 195.

Liassic formation, 46.

Libellula, 395.

Libellulidze, 405.

Libytheidz, 413.

Lichomolgus, 348.

Lieberkihn, 154.

Lieberkiihnia, 50, 53.

Ligamenta alaria, 392.

Ligia, 362.

Ligulidee, 171.

Ligula, 384.

Lilljeborg, 395.

Lima, 261, 264.

Limacide, 311.

Limacin, 7.

Limacina, 278.

Limacinidee, 275, 276.

Limax, 311.

Limnadia, 350.

Limnza, 289, 295, 300, 312.

Limneidz, 312. :

Limnochares, 373.

Limnoria, 362.

Limpets, 307.

Limulus, 16, 352.

Lindia, 198.

Lineidz, 163.

Lineolaride, 94.

Lineus, 163.

Linguatula (Pentastoma), 372.

Lingula, 247, 248, 250, 252, 253,

254.
Lingulide, 250.
Liodermatide, 153.
Lion, bones of, 17.
Liorhynchus, 185.
Liosoma, 153.
Liotheidze, 39g.
Lippmann, 24.
Liquor sanguinis, 32.
Liriope, 95, 361.
Liriopine, 95.
Litharachnium, 62.

444

Lithelidz, 63.
Lithistide, 78.
Lithobius, 377.
Lithocolletis, 411.
Lithocyst, 89.
Lithodinide, 356.
Lithodomus, 269.
Litholophinz, 65.
Lithomelissa, 62.
Lithophylliacez, 117.
Litiopa, 286.
Littoral zone, 44.

Littorina, 284, 297, 298, 301.

_ Littorinidze, 310.
Lituaria, 121.
Lituolide, 52.
Liver, 20, 291, 319.
Livia, 400.

Lizzia, go, 94.

Liwydia, 11, 127, 135, 136.

Lobatee, 109.
Lobiger, 288, 305.
Lobilabrum, 162.
Lobosa, 56.
Lobster, 353.

Ae parasite of, 54.

Locusta, 389.
Locustidee, 404.
Loftusia, 63.
Loliginide, 325.
Loligo, 328.
Loligopsidz, 325.
Loligopsis, 242.
Longicornes, 414.
Lophocerine, 117.
Lophocercus, 289, 305.
Lophogaster, 337.
Lophogorgia, 122.
Lophophore, 225.
Lophopoda, 230.
Lophoseris, 117.
Lophyropoda, 346.
Lovén, 23, 145, 175.
Lovenia, 147.
Loxodes, 62.
Loxorrhochma, 163.
Loxosomide, 230.
Lubbock, 328, 382,
Lucanus, 387.
Lucernaria, 102.
Lucernaride, IOI.
Lucilia, 391.
Lucina, 259, 260.
Lucinacez, 269.

Index.

Lucinidz, 269.
Lumbricus, 218.
Lumbriconereis, 220.
Lunula, 14.
Lutraria, 264, 271.
Lycaenide, 413.
Lycosa, 375.
Lycosidze, 375.
Lygus, 120.
Lynceus, 356.
Lymexylon, 418.
Lymph, 165.
Lynceus, 350.
Lyonsia, 286.
Lyriodon, 256.
Lysianassa, 361.
Lysidice, 220.
Lysiopetalum, 381.
Lytta, 395.

Macgillivraya, 303.
Machilis, 402.
Mackintosh, 140.
Macrobdella, 198.
Macrobiotus, 371.
Macroglossa, 412.
Macrolepidoptera, 411.
Macrostomum, 161.
Macrura, 354

Mactra, 256, 260, 264, 266, 271.

Madagascar, 44.
Madreporaria, I15.
Madrepores, 111.
Magilus, 295, 309.
Magnesium fluoride, 7.
Magosphaera, 2, 57, 49.
Mala, 384.
Malacobdella, 198, 203.
Malacobdellidz, 203.
Malacodermata, 113.
Malacolepidota, 170.
Malacostraca, 352.
Malayan province, 44.
Maldane, 219.

Malletia, 269.

Malleus, 195, 261.
Mallophaga, 398.
Mammalia, 46.

Man, bones of, 17.
Mangilia, 309.
Mangilian ganglion, 265.
Mantis, 391.

Mantispa, 396.

Mantle, 243, 275.

Index. 445

Manubrium, 87, 143. Mesosternum, 385.
Marey, 386. Mesostomum, 161.
Margarin, 8. Mesotheca, 86.

Marginal bodies, 88, 103, Mesozoic Age, 46.
Marginal tentacles, 265. Metagenesis, 35, 329, 390.
Marrow, 19. Metamere, II.

Marsenia, 285, 303. Metanotum, 385.

Martin St. Ange, 344. Metamorphosis, 36.
Martynia, 299. Metapodium, 243.
Mastigias, 104. Metasoma, 286, 355.
Matuta, 358. Metasternum, 385.
M‘Andrew, 135. Metastrongylus, 186.
M‘Crady, go. Metazoa, 49.

M<‘Intosh, 163. Metoecus, 415.

Measles, 168. Metopidia, 197.
Meckelia, 155, 163. Metridium, 114.
Meconidia, 94. Metschnikoff, 71, 90, 124.
Mecznikow, 66, 208, 238. Mexico, Antillean province, 43.
Mediterranean province, 43. Meyer, 19, 143, 228.
Meduse, 11, 87. Microcotyle, 174.
Meduside, 105. Microglena, 55.
Megaloptera, 405. Microlepidoptera, 411.
Megalotrochide, 197. Micropyle, 36, 396.
Megascolex, 219. Micropyle apparatus, 359, 370.
Meissner, 20, 23, 207, 359, 370- Microstomidee, 161.
Melaniidz, 310. Microstomum, 161.
Meleagrina, 261. Micrura, 162-3.
Melibeeidze, 304. Middendorff, 306.
Melibzea, 304. Miklucho Maclay, 73, 74.
Melicerta, 197. Miliola, 53.

Melicertum, 89. Miliolidz, 53.

Melissyl Palmistate, 8. Millepora, 90.

Melithzea, III, 122. Milleporide, 96.
Melithzidee, 122. Milnesium, 371.
Mellittine, 147. Milne Edwards, 306, 356.
Meloe, 414. Milnea, 114.
Melolonthide, 387. Minyas, I5I.
Melolontha, 312. Miocene formation, 46.
Melonites, 146. Mites, 365.
Membracidz, 400. Mithras, 375.

Memory in Oysters, 266. Mitra, 290, 309.

Meoma, 139. Mitride, 309.

Mermide, 179. Mnemia, 109.

Mermis, 178. Mnemiide, 109.
Meroblastic ova, 37- Mnemiopsis, 109.
Meropodite, 330. Modeeria, {Turridze), gr.
Mertensia, 108. Modiola, 269.
Mertensidz, 108. Modiolarca, 269.
Merulinide, 117. Molgula, 238, 240.
Mesonema, 94. Mollusca, 47, 241.
Mesonotum, 385. Molpadia, 125, 151, 153:
Mesopharynx, 161. Monadina, 55.
Mesopodium, 243. Monas, 55.

Mesosoma, 355- Monera, 449..*

446

Monobothrum, 171.
Monocampic, 168.
Monocaulide, 93.
Monocaulis, 93.
Monocelis, 161.
Monoceros, 309.
Monochitonide, 232.
Monocystidea, 65.
Monocystis, 64.
Monocyttaria, 62.
Monoderic, 13.
Moneecious, 34.
Monogenea, 174.
Monogenetic, 35-
Monolistra, 362.
Monomeric, 95.
Monomya, 261, 268.
Monopleurobranchiata, 315.
Monopsea, 95.
Monorhagia, 162.
Monostomide, 176.
Monostomum, 176.
Monosyca, 78.
Monstrilla, 334.
Montacuta, 267, 269.
Mopsea, 123.

Morch, 312.

Morphine, 413.
Morphological individual, 25.
Morphology, 12.
Morrisia, 249, 254.
Moseley, 283.

Motores aculei, 140.
Motions of protoplasm, 2.
Mucous glands, 14.
Miller, 15, 61, 37, 126, 345.
Miilleria, 268.

Murex, 289, 291, 298, 309.
Muricea, 122.

Muricidz, 309.

Musca, 408.

Muscle cells, 5.

Muscular tissue, 20.
Muscles of Echinus, 143.
Insects, 389.

” ”
?

3 », Bryozoa, 227.
Mutilla, 420.
Mya, 256.
Myacea, 271.
Myeloid cells, 19.
Myeloplaxes, 18.
Mygalide, 374.
Mygale, 365, 368, 374.

,» Molluscs, 288, 317.

Index.

Myide, 271.
Myodora, 270.
Myopside, 6.
Myoryctes, 184.
Myosin, 6.
Myriopoda, 377.
Myrmecia, 375.
Myrmeleo, 327.
Myriothelidz, 92.
Myriotrochus, 152.
Myniozoide, 229.
Mysis, ear of, 340.
Myopsidz, 274.
Myosin, 6.

Mysis, 340, 358.
Mytilus, 256, 257, 267.
Mytilicardia, 264.
Myxodictyum, 49.
Myxobrachia, 62.
Myxomycetes, 25.
Myzostoma, 49.
Myzostomide, 175.

Nacella, 307.
Nacre, 244.
Naidiz, 218.
Nais, 218.
Nanina, 312.

| Nassa, 309.
| Nassula, 66, 71.

Natural selection, 71.
Naumann, 19.
Nauplius, 342.
Nausithoe, 105.
Nautactis, 114.
Nautilus, 316, 325.
Nearctic region, 42.
Nebalia, 351.
Necrophorus, 418.
Nectocalyx, 88, 96.
Nectosac, 97.
Nectocalycine canals, 97.
Neda, 305.
Needham’s filaments, 327.
Neiside, 108.
Nematelmia, 177.
Nematoda, 179.
Nematophore, 95.
Nemertes, 162, 107.
Nemertidea, 161.
Nemopsidz, 92.
Nemopsis, 92.
Neossin, 8.
Neotropical region, 44.

Index. 447

Neozoic Age, 46. Obisium, 376.
Nepa, 394. Occiput, 384.
Nephrops, 355. Occlusores, 250.
Nephthya, IIT. / Oceania, 92.
Nephthys, 221. Ocelli, 89, 150.
Nereis, 220. Ochnus, 153.
Nerine, 222. Octactinia, 117.
Nerita, 292. Octocotyle, 174.
Neritidze, 307. Octomeris, 345.
Neritina, 292, 307. | Octopus, 245, 314.
Nerve endings, 23. | Octorchidz, 95.
Nervous system of Bryozoa, 227. Octorchis, 95.

_ yy» 9) Cheetognatha, 207.| Oculinidz, 116.

i a 5) ichimuss14'5¢ Oculininz, 117.

- Pl elinnGinea lz: Ocypode, 357.

3 » 9») Nemerteams, 157. Ocyroidz, 109.

5 » 3) Mollusca, 207, 287. Odonata, 391.

5 is) Sects; eq00: | Odontobius, 184.
Neurin, 6. | Odontognatha, 288, 312.
Neuroglia, 15. | Odontophore, 287.
Neurobranchiata, 311. | Odynerus, 420.
Neuromuscular cells, 81. C£cistidz, 197.
Neuroptera, 405. C£cistes, 197.
Nicoletia, 402. (Ecoid, 32.
Nicothoe, 347. (Edipoda, 404.
Nidalia, 117. C&rsted, 161.
Niphargus, 360. CErstedia, 162,
Nitzsch, 398. | CEsophagus, 30.
Noctiluce, 56. | Oéestrus, 394.
Noctua, 411. | Oigopside, 325.
Noctuide, 411. Oikosites, 40.
Nodosaria, 54. Oiketicus, 384.
Nonioninide, 54. | Oldhamia, 47.
Nops, 374. Olfactory organs, 339.
North America, 43. d | Oligocheta, 218.
Notarchus, 305. | Oligopori, 146.
Noteus, 198. ‘ Oliva, 281, 309.
Notoceridz, 160. Olividze, 309.
Notodelphys, 347. Ollulanus, 186.
Notochord, 15. Ommatide, 63.
Notommata, 194. Ommastrephes, 314.
Notonecta, 401. Ommatoplea, 162.
Nubecularia, 53, Ommatophores, 286, 297.
Nubicula, 287. Omostegite, 353.
Nucleobranchiata, 294. Onchidium, 290, 295.
Nucleus, 4, 237. Onchidoridz, 308.
Nucleolus, 4, 11. Onchidoris, 305.
Nummulites, 52. Onchocerca, 186.
Nutritive organs, 206. Oncholaimus, 184.
Nyctalops, 376. Oncinolabes, 152.
Nymphon, 364, 370. Oniscidz, 362.
Nymphalide, 412. Oniscus, 362.

Onuphis, 220.
Obelia, 94. Onychophora, 205.

448

Onychoteuthidz, 325.
Oocysts, 226.
Oophylax, 21.
Opalina, 68.
Opalinzea, 68.
Operculum, 225, 285.
Opercularia, 68.
Ophelia, 221.
Ophiacantha, 133.
Ophiarachna, 133.
Ophiarthrum, 133.
Ophidiaster, 187.
Ophidromus, 221.
Ophioblenna, 133.
Ophiocephalus, 163.
Ophiocnemis, 133.
Ophiocoma, 131.
Ophiocominez, 133.
Ophiocrinus, 131.
Ophiocten, 133.
Ophioderma, 133.
Ophiodermine, 133.
Ophiolepinz, 133.
Ophiolepis, 131.
Ophiomastix, 131.
Ophiomyxa, 131, 133.
Ophiomyxinz, 131.
Ophionereinz, 133.
Ophiopeza, 133.
Ophioscolex, 133.
Ophioscolecinz, 133.
Ophiostoma, I, 133.
Ophiothrix, 134.
Ophiura, 133.
Ophiuridz, 133.
Ophiuroides, 127, 131.
Ophrydide, 70.
Ophrydium, 70.
Ophryocercidz, 71.
Ophryocerca, 71.
Ophryodendron, 70.
Ophryoglena, 68, 71.
Ophryoscolecida, 71.
Ophryoscolex, 71.
Opilio, 364. ~
Opilionide, 375.
Opistomum, 161.

Opisthobranchiata, 280, 304.

Orbicula, 53, 247-
Orbis-radule, 288.
Orbitelz, 375.
Orbitolites, 52.
Orbitoides, 55.
Orbulina, 54.

Index.

Orbulinide, 54.
Orchestia, 360.
Orcula, 153.
Order, 38.
Oreaster, 137.
Organ, 26.

Organ system, I0.
Organ-pipe coral, 120.
Oribates, 365.
Oribatidze, 373.
Origin of species, 40.
Ornithomyia, 419.
Orthocerina, 54.
Orthocerus, 315.
Orthoptera, 403.
Orthostomum, 161.
Oscula, 71.
Osculina, 73.
Osmic acid, 16, 17.
Ossification, 18.
Osteoblasts, 18.
Ostracoda, 348.
Ostreidze, 268.
Ostreea, 268.
Otion, 345.
Otocardia, 255.

Otocysts, 36, 50, 236, 265, 299.

Otoliths, 28, 158.
Ova, 83.
Ovalbumen, 6.
Ovary, 34.
Ovipositors, 396.
Ovulum, 308.
Owen, 324, 325.
Ox bones, 17.
Oxygen, 7.
Oxygnatha, 388.
Oxyrhynchus, 357.
Oxystomata, 357.
Oxytricha, 72.
Oxytrichidz, 72.
Oxyuris, 180, 185.
Oxyuride, 185.
Oyster, 257, 259, 261, 267.

Pachymatisma, 77.
Pacific Ocean, 45.
Pacinian corpuscles, 23.
Packard, 396.
Pagenstecher, 2, 300.
Pagina, 281.

Paguridz, 356.
Pagurus, 356.

Palzarctic region, 42.
Palzechinus, 146.
Palzemon, 356.
Palzontology, 45.
Palzeozoic age, 46.
Pal angulares, 131.
Palzodiscus, 134.
Palzostoma, 140.
Palettes, 271.

iPalt pits.
Palinuridz, 385.
Palinurus, 355-
Pallial line, 258.
Pallial sinus, 258.
Palliobranchiata, 247.
Palmipes, 137.
Palmyra, 221.
Palpocils, 82.
Paludicella, 225.
Paludicellidze, 230.
Paludina, 301.
Paludinidz, 310.
Palythoa, 114.
Pampas, 43.
Pamphagus, 57.
Pancerl, 121, 239, 271.
Pancreas, 31.
Pandalus, 331.
Pandarus, 348.

Pandora, 66, 67, 256, 270.

Panopza, 271.
Panorpa, 391.
Panspermism, 9.
Pantopoda, 370.
Paphiidz, 270.

Papilio, 387.

Papirius, 394.

Papille sulcorum, 139.
Parabasal plates, 130.
Parablastic, 14.
Paradoxites, 184.
Paraglobulin, 6.
Paragastric canals, 106.
Paraglossa, 390.
Paragorgia, 123.
Paralcyonium, 120, 122.
Paramecium, 66, 70, 71.
Parascidium, 241.
Parasitism, 39.
Parenchyma, I5.
Parietalis, 227.
Parietovaginalis, 227.
Parisis, 123.

Parkeria, 53.

Index.

Parkeriade, 53.
Parmacella, 311.
Parmophorus, 282, 292, 295, 307.
Parnassias, 413.
Parostosis, 19.

Pars polypifera, 120.

Parthenogenesis, 36, 229, 369, 396-

Parydrodea, 91.
Passalurus, 185.
Patagonia, 44.
Patella, 293—4, 307.
Patellidz, 307.
Pauropoda, 382.
Pauropus, 382.
Pausside, 416.
Pavement epithelium, 13.
Pavonaria, 121.
Paxille, 134.

Peachia, 114.

Pecten, 251, 261, 263, 264, 268.
Pectinide, 268.
Pectinaria, 223.
Pectunculus, 255, 256, 264.
Pedalion, 196.
Pedicellariz, 135, 141.
Pedicelli, 124.
Pedicellina, 230.
Pedicle, 47.
Pedicularidz, 308.
Pediculina, 399.
Pediculus, 399.
Pedipalpi, 376.
Pedipes, 281.

Pedum, 268.
Peduncle, 248.

Pelac wax, 400.
Pelagia, 105.
Pelagiada, 105.
Pelagidz, 105.
Pelecypoda, 260.
Peligot, 327.
Pelodera, 182.
Pelodytes, 182.
Pelomyxa, 55.
Pelonaia, 231, 237.
Pelonaiadze, 240.
Peltogaster, 346.

Pen (Cephalopoda), 314.
Peneus, 356.
Peniculus, 348.
Pennaria, 92.
Pennariide, 92.
Pennatula, 121.
Pennatulaceze, 120.

2G

449

450

Pennatulidz, 120.
Pennella, 348.
Pennellidz, 348.

Pen sac, 314.
Pentacrinus, 129, 130.
Pentamera, 415.
Pentamerus, 247.

Pentastoma, 364, 366, 399.

Pentastomide, 366, 372.
Pentastoma, 396.
Pentatremites, 128.
Pepsin, 7.

Peptone, 7.
Peranema, 55.
Peremeschko, 3.
Pereiopod, 355.
Perforata, 54, 116.
Pericheta, 210.
Periderm, 85.
Peridiniza, 64.
Perigenic budding, 86.
Perigonium, 86.
Periosteum, 19.
Periostracum, 284.
Peripatus, 205.
Periplaneta, 403.
Perisome, 124.
Perisphzeria, 403.
Peritheca, 112.
Peritreme, 285, 376, 394.
Peritricha, 66.
Perivisceral space, 31.
Perla, 405.

Perlidae, 405.
Perlinus, 1

Permian formation, 46.
Perna, 257.
Perophora, 233, 240.
Perosotrocha, 198.
Perrier, 141.
Persona, 11, 308.
Perspiration, 33.
Perty, 57.

Petalopus, 57.
Petalospyris, 62.
Peters, 191.

Petiole, 418.
Petricolide, 270.
Petrobius, 402.
Pfliiger, 23.
Phacellophora, 105.
Phacus, 56.
Phagocata, 160.
Phalacridz, 417.

Index.

Seen eee

Phalenide, 411.
Phalangita, 375.
Phalangium, 366, 375, 389-
Phallusia, 237, 240.
Phanerocodonic, 86, 87.
Phanogenia, 131.
Phanoglene, 184.
Pharyngeal crop, 289.
Pharyngeidze, 161.
Pharyngodon, 185.
Phascolosoma, 189, 192, 193.
Phasma, 403.

Phasmide, 403.
Phenomena of life, 1
Pherusia, 222.

Philine, 305.

Philinidze, 305.

Philodina, 197.
Philodinidz, 197.
Philonexis, 376.
Philopteridz, 399.
Phlebenterata, 291.
Phlceothrips, 402.
Pholadacez, 271.
Pholadidz, 271.

Pholas, 257.

Pholcus, 375.

Pholoe, 221.

Phorus, 310.

Phoronis, 218.

Phos, 309.
Phosphorescence, 261.
Photinus, 412.
Photoscopic eyes, 28.
Phoxochilus, 370.
Phreoryctes, 219.
Phragmocone, 314.
Phronima, 337, 361.
Phryganea, 393, 396, 406.
Phrynidz, 377.

Phthirius, 399.

Phthiriasis, 399.
Phylactolemata, 230.
Phycochromacea, 25.
Phycogorgia, 122.
Phyllacanthidze, 171.
Phyllactis, 114.
Phyllidiida, 306.
Phyllirhoe, 242, 303-4.
Phyllium, 403.
Phyllobothrium, 170.
Phyllocotyle, 174.
Phyllocyst, 98.
Phyllodoce, 221.

Index 454

Phyllogorgia, 122. Pleurophyllidia, 288, 305.
Phyllonotus, 289. Pleurophyllididz, 305.
Phyllophora, 153. Pleurotomaridz, 307.
Phyllopoda, 350. Pleurotomidz, 308.
Phyllosoma, 334. Pleurotrocha, 197.
Phymactis, 114. Plexaurella, 122.
Phymanthus, 115. Plexaura, 122.

Physa, 312. Plicaphora, 301.
Physalia, 99, 100. Pliocene, 46.
Physaliadz, Ioo. Plotactis, 114.
Physalopteridz, 185. Ploteres, 401.
Physematium, 60, 62. Plumatellidz, 230.
Physiology, 12. Plumularia, 69, 95.
Physiological individuality, 25. Plumulariade, 94.
Physophora, 99, 100. Pluteus, 125, 132.
Physophoridz, 98, 100. Pneumatic filaments, 99.
Phytocrinus, 130. Pneumatocyst, 99.
Phytophaga, 421. Pneumodermon, 275, 276, 27°.
Phytoptus, 373. Pneumodermonidz, 279.
Pieride, 412. Podactinaria, Io1.
Pilidium, 162. Podobdella, 205.
Pinacobdella, 205. Podocoryne, 92.
Pinna, 268. Podocorynidz, 92.
Pinnide, 268, 357. Podophrya, 54.
Pinnotheres, 152. Podophthalmia, 362.
Piscicola, 198. Podura, 391, 402.
Pisidium, 259, 266, 270. Poduride, 396, 402.
Pixinia, 65. Poecilopoda, 337, 351.
Placobranchiata, 294, 300, 304. Poecilopora, III, 115.
Placospongia, 78. Polar province, 42.
Placuna, 266. Polfelder, 107.
Plagiotoma, 69. Poli, 260.

Planacera, 160. Polia, 161, 162.
Planaria, 3, 160. Polian vesicles, 129.
Planariidz, 160. Polistes, 420.
Planoblast, 187. Pollicipes, 345.
Planorbis, 289, 292, 312. Polyarthra, 196.
Planula, 37, 91. Polybia, 420.
Plastide, 5. Polybranchiata, 294.
Platoum, 58. Polycampic, 168.
Platyblenna, 404. Polycelis, 158.
Platyclinia, 411. Polycera, 288.
Platypeza, 412. Polyclinium, 234, 241.
Pleistocene, 46. Polyclinidz, 235.
Pleopod, 355. Polycladus, 160.
Pleurze, 351, 385. Polyclonia, 104.
Pleurobrachia, 107. Polyclonidz, 104.
Pleurobrachidz, 108. Polycyttaria, 63.
Pleurobranchiata, 305. Polyderic epithelium, 13.
Pleurobranchiza, 289. Polydesmus, 378, 381.
Pleurobranchinz, 305. "| Polyergus, 420.
Pleurobranchus, 281, 305. Polygnatha, 312.
Pleurocysta, 142. Polymeric, 93.
Pleuronema, 66. Polymorphina, §0.

2G 2

452

Polymorphinidz, 84.
Polynesia, 44.
Polynoe, 220.
Polyophthalmos, 216.
Polyparium, III.
Polypieroid, 111.
Polyphemus, 350.
Polyplacophora, 316.
Polypi, 81.
Polyselmis, 56.
Polystemma, 162.
Polystoma, 75.
Polystomata, 72.
Polystomella, 51, 55-
Polystomidz, 175.
Polysyca, 78.
Polythalamia, 51.
Polytoma, 55.
Polytrema, 52.
Polyxenus, 381.
Polyzoa, 224.
Polyzonium, 381-2.
Pomatobranchiata, 294.
Pompiliidz, 420.
Pontarachna, 373.
Pontellidz, 341.
Pontobdella, 198.
Pontogenia, 220.
Pontolimacide, 303.
Pontolimax, 288, 293, 300.
Pontonema, 184.
Porcellana, 356.
Porcellio, 362.
Porellidz, 230.
Porifera, 47, 72.
Poritidz, 116.
Poritine, 116.
Porphyrophora, 400.
Porpita, 49, 101.
Portunus, 357.
Post-scutellum, 385.
Posterobranchea, 305.
Potomospongia, 78.
Poteriocrinus, 130.
Praniza, 361.
Pranizide, 361.
Praya, 97, 98.
Prayidz, 98.

Prehensile collar of Doris, 88.

Priapulidz, 189, 191.
Priapulus, 193.
Primnoa, 121.
Primnoide, 121.
Prisopus, 403.

Index.

Proboscis, 156, 287,
Procephalic scales, 398.
Procerus, 416.
Processus vocalis, 17.
Proclypeus, 348.
Procotyla, 161.
Proctonotidz, 282, 304.
Proctucha, 168.
Productide, 248.
Proglottis, 165.
Prolegs, 397.
Pronotum, 385.
Proostracum, 314.
Propodite, 331.
Propodium, 243.
Proporus, 161.
Prorhynchus, 161, 162.
Prorodon, 66, 67.
Proscolex, 167.
Prosobranchiata, 280, 306.
Prosoma, 286, 355.
Prosorrhochmus, 162-3.
Prosternum, 385.
Prosthecerzeide, 160.
Prostomium, 157.
Prostomum, 161.
Protagon, 7.
Protamceba, 49.
Protaster, 134.
Proteolepas, 344.
Prothorax liber, 385.
Protista, 25.
Protogenes, 49.
Protohydra, 84.
Protomonas, 49.
Protomyxa, 2, 49.
Protoplasm, 2, 6.
Protoplasta, 25, 56.
Protopodite, 331.
Protozoa, 46, 47, 48.
Protozooid, 35.
Protula, 223.
Psammocora, I16.
Pselaphide, 414.
Pseudarachna, 370. -~
Pseudembryo, 125.
Pseudoceride, 160.
Pseudocamerated shells, 284.
Pseudochlamys, 57.
Pseudocollum, 273.
Pseudocolumella, 112.
Pseudogorgia, 121.
Pseudonychia, 385.
Pseudofilariz, 65.

Pseudomantle, 281.
Pseudonavicelle, 65.
Pseudoneuroptera, 393.
Pseudoparasitism, 40.
Pseudoparthenogenesis, 36.
Pseudopodia, 2.
Pseudo scorpiones, 375.
Psuedostigmata, 365.
Pseudotentaculata, 156.
Pseudova, 401.
Pseudovaria, 36.
Psocus, 404.
Psorospermia, 65.
Psolus, 151, 153.
Psyche, 36, 411.
Psyllidz, 4o1.
Ptenoglossa, 288, 399.
Pteraster, 137, 154, 156.
Pterobothrium, 171
Pterocardiac ossicles, 359.
Pteroceras, 298, 305.
Pterocoma, 131.
Pterodina, 198.
Pteroeides, 120,
Pterogorgia, 122.
Pteronarcys, 393, 405.
Pteropelagia, 279.
Pteropoda, 275.
Pteroptus, 373,
Pterosoma, 304.
Pterotrachea, 280, 290, 295.
Pterophoride, 415.
Ptilinus, 418.

Ptinus, 418.
Ptychocephalidz, 185,
Ptyguridze, 197.
Ptygura, 197.

Pulex, 407.

Pulicide, 407.
Pulmonary sacs, 33.

Pulmonata, 280, 311, 346, 363.

Pupa, 152, 397.

Pupipara, 408.

Purple glands, 297.
Purpura, 291.

Pusionella, 309.
Pustularia, 308.
Pycnogonidze, 364, 367, 370.
Pycnogonum, 370.

Pye raneia
Pygobranchiata, 294, 305.
Penden fc ad
Pyramidellidz, 310.
Pyrgoma, 345.

Index. 453

Pyrochroide, 415.
Pyrophorus, 418.
Pyrosoma, 239.
Pyrosomidz, 240.
Pyrula, 319.

Quaternary age, 47.
Quatrefages, 189.

Rabl-Ruckhardt, 16, 17.

Rachiglossata, 288.

Radial canals, 73.

Radial plates, 130.

Radialia axillaria, 130.

Radiolaria, 11, 25, 60.

Radius, 345.

Radula, 272, 287.

Radulidz, 268.

Rainey, 26.

Ranatra, 401.

Ranella, 308.

Rangia, 271.

Rangide, 209.

Ranke, 24.

Raptorial birds, 6.

Raphidiophrys, 59.

Raphidozoum, 64.

Raphiophora, 73.

Raphyrus, 77.

Rataria, 107.

Rathke, 16, 17, 164.

Reagents, action of, on proto-
plasm, 3.

Receptaculum scolicis, 168.

Recklinghausen, 2, 16.

Red brown organ of Keber, 261.

Redia, 1.75.

Reduvini, 401.

Reefs, coral, 118.

Regularia, 146.

Reichert, 11.

Remak, 14, 22-5.

Reniera, 74, 77.

Renilla, 121.

Reproduction, 34.

Reproduction of Arachnida, 369.

op of Brachiopoda, 250,
= of Bryozoa, 228.

op of Crustacea, 348.

Fr of Ctenophora, 108.
* of Discophora, 103.
or of Echini, 145.

aS of Gasteropoda, 299.

5, of Hydra, 82.

454

Index.

Reproduction of Insecta, 395.

>?

of Infusoria, 68.

of Lamellibranchiata,
266.

of Rhizopoda, 53.

of Scaphopoda. 274.

” of Sponges, 75.
Respiration, 33.
Rete mirabile, 157.
Retrogression, 38.
Rhabdoceela, 161.
Rhabdoidea, 55.
Rhabdoliths, 62.
Rhabdophora, 183.
Rhabdopleura, 224, 226, 229.
Rhagophora, 162.
Rhamphogordius, 164.
Rhaphidozoum, 63.
Rheiner, 17.
Rhinacantha, 289.
Rhipiceridz, 418.
Rhipidoglossata, 288.
Rhipidogorgia, 122.
Rhipidopathes, 117.

, Rhipiphoride, 415.
Rhizobius, 400.
Rhizocephala, 334.
Rhizocrinus, 131.
Rhizophysa, Ioo.
Rhizophysida, 100.
Rhizopoda, 50.
Rhizogeton, 89.
Rhizostoma, 104.
Rhizostomida, 103.

Rissoa, 286.
Rocellaria, 256.
Rolleston, 40, 264.
Rollett, 15.

Rosalina, 84.
Rostellaria, 308.
Rostellum, 165.
Rostral plate, 345.
Rostro-lateral plate, 345.
Rotalia, 53-4.
Rotalinide, 54.
Rotatoria, 193.
Rotifer, 197.

Rotulz, 140.
Rudimental organs, 41.
Rudolphi, 164.
Rugosa, 47, 95, 115.
Ruminant parasites, 71.

Sabella, 223.
Sabellaria, 223.
Sabellides, 223.
Saccanthus, 114.
Saccate, 108.
Sacculina, 346.
Sacculus, 97.
Saenuris, 218.
Sagartia, 110, 113, 114.
Sagitta, 200.
Sahara, 43.
Salamis, 104.
Salenidze, 147.
Salensky, 159, 329.
Salicornaria, 229.

Rhizostomide, 104.
Rhizoxenia, 119.
Rhochmocephalide, 163.

Salivary glands of Spiders, 315.
e of Teredo, 259.
+ of Cephalopoda, 318.

Rhochmocephalus, 163.
Rhodactis, 114.
Rhodope, 291, 293, 300, 303-
Rhodosoma, 232, 240.
Rhopalocera, 411.
Rhopalodina, 153.
Rhopalonema, 89.
Rhopalophorus, 176.
Rhyncheta, 69.
Rhynchoceela, 161.
Rhynchodesmus, 161.
Rhynchonellide, 246.
Rhynchoprobolidz, 161-
Rhynchota, 399.
Richiardi, 120.
Rictularia, 184.
Rimula, 307.

Saliva, 31.

Salpa, 231.
Salpella, 240.
Salpidz, 239.
Salpina, 197.
Salpingide, 415.
Saltatoria, 404.
Salter, 20.

Salticus, 375.
Sapphirina, 330, 347-
Saprophytes, 24.
Sapygia, 420.
Sarcobelemnon, 121.
Sarcoids, 74.
Sarcolemma, 20.
Scarcophaga, 409.
Sarcophianthus, 115.

Sarcophyton, 119.
Sarcopsylla, 407.
Sarcoptes, 366, 372.
Sarsia, 89, 91.
Saturnia, 412.
Satyride, 413.
Saxicava, 271.
Saxicavide, 271.
Scalariidz, 309.
Scalibregma, 222.
Scalidz, 391.

Scalis, 223.
Scalpellum, 345.
Scaphidiidz, 4o1.
Scalpella, 407.
Scaphognathite, 355.
Scaphopoda, 272.
Scapula, 385.
Scarabeeidze, 387, 417.
Scaridinidz, 197.
Scatophaga, 409.
Scenopini, 409.
Sceptonidium, 120.
Schaltstiicke, 143.
Schiner, 407.
Schizascus, 231.
Schizaster, 139, 148.
Schizocephala, 403.
Schizoccela, 48.
Schizodactylus, 404.
Schizopoda, 338, 358.
Schizoneura, 400.
Schizoprora, 161.
Schizotrocha, 197.
Schlossberger, 15.

Schmarda, 45, 69, 152, 329, 363.

Schmardea, 160.
Schmardia, 221.

Schmidt, 78, 284.
Schneider, 57, 61, 164, 205.
Schrén, 36.

Schultze, 51,55, 57, 161, 163.
Schulze, 85.

Schwalbe, 20, 23.
Schwann, sheath of, 22.
Schwartzenbach, 1.

Sciara, 410.

Sclerenchyma, III.
Sclerobasica, 117.
Sclerobasis, 117.
Sclerodactyla, 153.
Sclerodermata, 116.
Sclerodermites, 111.
Sclerohelia, 117.

Index. 455

Sclerolepidota, 170.
Sclerostomum, 186.
Scolecida, 154.
Scolex, 164.
Scolopendra, 377, 382.
Scolopendride, 382.
Scolytes, 414.
Scorpions, 363, 369.
Scorpiodez, 396.
Scrobiculariida, 270.
Scrupariadz, 230.
Scutellum, 385.
Scutigera, 382.
Scyllza, 304.
Scyllarus, 337, 355.
Scyllite, 9.
Scyphidia, 69.
Scyphistoma, 103.
Scytalium, 131.
Sczelkow, 32.
Segestria, 368, 374.
Segmental organs, 190, 213, 246,
252.
Selenaridz, 229.
Semitz, 131.
Semper, organ of, 200, 298.
Semper, 175, 189, 252, 346.
Sense, organs of, 27.
Sepia, 316.
Sepiola, 314.
Septa, III.
Septum dorsale, 249.
Sergestes, 337.
Seriatopora, I15.
Seorles, 362.
Serpula, 223.
Serpulide, 223.
Sertularidz, 74, 94.
Sertulariadz, 97.
Sharpey, 5, 18.
Shell, 243, 247, 284, 314.
Siagonopods, 355.
Sialis, 406.
Sicyosoma, 109.
Sida, 360.
Siderolithes, 64.
Sidnyum, 234, 241.
Siebold, 178, 327.
Sigara, 293, 401.
Seigretus, 295.
Sigillina, 241.
Silpha, 417.
Siliquaria, 310.
Silurian period, 46.

456 Index.

Sinistral shells, 276, 283.
Sinupalliata, 270.
Siphodentalium, 273, 274.
Sipho, 208.
Siphonactinia, 114.
Siphonaria, 312.
Siphonizantia, 381.
Siphonal tentacles, 259.

» ganglion, 215.
Siphonodentalium, 273.
Siphonophora, 96, 382.
Siphonospheera, 64.
Siphonostomata, 308, 347, 361.
Siphuncle, 314, 315.
Sipunculide, 192.

Sipunculus, 189, 190, 191, 192, 193.

Sirex (Uroceridz), 421.
Sisyra, 406.

Sitaris, 414.

Slabberia, 91.

Slugs, foot gland of, 296.
Smaragdinella, 305.
Smynthurus, 387.
Socialia, 404.
Solanderia, 123.
Solarium, 309.
Solaster, 136-7.
Solemya, 256.

Solen, 260, 266.
Solenide, 271.
Solenobia, 36.
Solenogorgia, 123.
Solenonema, 185.
Solifugze, 365.
Solpuga, 365, 377.
Somatic cavity, 85.
Somatocyst, 197.
Somites, 327.
Soritide, 54.
Soroideze, 51, 55.
Spadix, 86, 317.
Spatangidz, 139, 145, 147.
Spatangus, 139, 148.
Spatha, 262.

Species, 37.

Species, number of living, 46.
Spence Bate, 46, 354.
Spermaceti, 8.
Spercheus, 415.
Spermategee, 179.
Sphaerechinus, 138.
Spheeridia, 145.
Spherites, 246.
Spheeria, 167.

Spherodorum, 222.
Spheeronidze, 362.
Spheeronectes, 98.
Spheronectide, 98.
Spherotherium, 381.
Sphzerozoum, 64.
Spheerularidez, 179.
Sphex, 420.
Sphenoderia, 53.

‘Sphenopus, 114.

Sphenotrochus, 412.
Sphingidz, 400.
Sphinx, 412.
Sphyrocephalus, 160.
Spicules, 75.
Spiders, 364.

Spines, 140.

Spine warts, 138.
Spiniger,

Spio, 222.
Spiocheetopterus, 219.
Spirachtha, 386.
Spirialis, 292.
Spina, 9.

Spirifer, 250.
Spiriferidze, 254.
Spirobolus, 381.
Spirillina, 56.
Spirochona, 70, 79.
Spirolina, 55.
Spiroptera, 184.
Spirorbis, 223.
Spirostomum, 67, 71.
Spirula, 315.
Spirulina, 50.
Spirulirostra, 315.
Spirura, 184.
Spiruridze, 184.
Spondylidze, 270.
Spondylus, 270.
Spondylostomum,
Spongelia, 77.
Sponges, 72.
Spongia, 76.
Spongilla, 78.
Spongioderma, 123.
Spongobranchia, 275, 277.
Spongiolin, 8, 75.
Spongocycline, 63.
Spongodes, 119.
Spongodictyum, 63.
Spongodiscidinze, 63.
Spongospheerine, 63.
Spongotrochus,

Lhdex. 457

Sponguride, 63. Stricker, 215.
Sporadipus, 153. Stridulantia, (Cicadidz), 401.
Sporadipoda, 151. Strobila, 103, 109, 165.
Sporocyst, 176. Strombus, 281, 295, 298, 308.
Sporosac, 85. Strongylide, 186.
Squama, 384, 407 Strongylosoma, 381.
Squamulina, 60, 63. Strongylostomum, 161.
Squilla, 358. Strongylus, 186.
Squillina, 358. Strophomenidz, 255.
Staphylinidz, 416. Struthiolaria, 308.
Staphylinus, 416. Stylasteridze, 117.
Starch, 8. Stylatura, 120.
Statoblasts, 228. Stylifer, 247, 310.
Stauridz, 115. Stylinacea, 117.
Stearin, 8. Styliola, 275.
Steenstrup, 326. Stylocheilus, “2 81.
Steenstrupia, gI. Stylochus, 160.
Steganophthalmata, 105. Stylommatophora, 311.
Stein, 66, 68, 69, 70. Stylonychia, 71.
Steinach, 14. Stylophoridz, 116.
Stelletta, 78. Stylops, 406.

Stelmius, 184. Stylorhynchus, 65.
Stellerida, 126. Suberites, 77.
Stenochilus, 374. Sub-kingdoms, 38.
Stenostomum, 161. Subulina, 285.

Stentor, 12, 66, 67. Succincta, 412.
Stentoridz, 71. Suctoria, 345.
Stephanoceros, 197. Suspensa, 412.
Stephanomia, 100. Swammerdamian vesicle, 300.
Stephanomiadz, 100. Sycon, 72.
Stephanospira, 71. Sycones, 78.
Stephanunis, 186. Syllis, 221.
Sternaspidia, 193. Syllida, 221.
Sternaspis, 189, 193. Symplecta, 184.
Sternopteryx, 408. Sympodium, 119.
Sternum, 142. Synapta, 125, 148, 152.
Steudeler, 6. Synaptidee, 152.
Sthenonia, 105. Synapticula, 112.
Stichopus, 153. Syncoryne, 91.
Stichostigia, 51. Syncorynidze, gt.
Stigmata, 367. Syncrypta, 57.

Stiliger, 304, Syndendrium, 104.
Stipes, 384. Synoicum, 241.
Stoastomidze, 311. Syntethys, 240.
Stolicza, 268. Synthetic types, 38.
Stomapoda, 337, 358. Syntonin, 6.

Stomatia, 307. Synura, 57.
Stomatoda, 69. Syringopora, II5.
Stomatodendron, 109. Syrphidz, 418.
Stomobrachium, 94. Syzygies, 130.

Stratiomyidz, 407, 408.

Stratiomys, 383.

Strepsiptera, 389. Tabanidz, 409.
Streptaxis, 311. Tabanus, 409.

458

Tabule, 112.
Tabulata, 115.
Tachina, 408.
Tachygonetria, 185.
Taenia, 169.
Taeniadz, 169.
Taeniatze, 108.
Tzenioglossata, 9, 288, 304-
Tzeniosoma, 163.
Talitrus, 360.
Tamoya, 105.
Tanais, 362.
Tanystomata, 409.
Tapes, 270.
Tapeworms, 164.
Taphrocampa, 196.
Tardigrada, 364.
Tectology, 24.
Tecturide, 307.
Tegenaria, 308.
Telescopium, 290.
Telestidz, 119.
Telesto, 119.
Tellinacez, 270.
Tellina, 270.
Tellinidze, 270.
Telostomum, 161.
Telson, 354.
Temnechinus, 147.
Temnocephalus, 293.
Temnopleura, 147.
Tenebrio, 415.
Tenebrionide, 415.
Tentaculidee, 279.
Tenthredinidz, 421.
Tenthredo, 421.
Terebella, 223.
Terebellide, 223.
Terebellum, 308.
Terebratulide, 254.
Terebratula, 254.
Teredo, 258, 262, 264.
Teredinide, 262.
Tergipes, 297.
Termes, 404.
Termitidz, 404.

Terricolz (Oligocheta), 218.

Tessellata, 130, 146.
Testacellidz, 311.
Testicardines, 253, 254.
Testis, 34.

Tethya, 77.

Tethyidz, 282, 288, 305.
Tetrabothrium, 170.

Index.

Tetrabranchiata, 324.
Tetracelis, 160.
Tetraclita,"345.
Tetranychus, 373.
Tetraphyllide, 170.
Tetrapneumona, I52.
Tetrarhagea, 163.
Tetrarhynchus, 165, 170.
Tetrastemma, 162, 163.
Tetrastoma,.175.
Tettigonia, 401.
Textularia, 49, 54.
Thalassicolla, 62.
Thalassianthe, 115.
Thalassemidz, 193.
Thalassolampe, 62.
Thalassoplaneta, 62.
Thalassospheera, 62.
Thaliacea, 239.
Thaumantiade, 94.
Thaumantias, 89.
Theca, 14, III.
Theceurybia, 278.
Thecidium, 241, 253, 259.
Thecide, 116, 279.
Thecosomata, 279.
Thelphusa, 357.
Therevidze, 409.
Theridion, 374.

Thetis, 303.

Thomisus, 374.
Thomson Wyville, 125.
Thompsonia, 346.
Thoosa, 77.

Thoracica, 344.
Thorax, 385.

Thrips, 402.

Thyone, 153.
Thyonidium, 148, 153-
Thyroidea, 129.
Thysanopoda, 337.
Thysanoptera, 402.
Thysanteuthis, 326.
Thysanura, 402.
Tiaropsis, 89, 94.
Tiedemannia, 276.
Tinea, 411.
Tineide, 411.
Tintinnus, 70.
Tipula, 410.
Tipulidze, 410.
Tisiphonia, 77.
Tissues, 10.
Tomicus, 414.

Tomes, 18.
Tomopteris, 219.
Tomsa, 23.
Tornaria, 209.
Tornatina, 305.
Torrea, 215.
Tortricidz, 411.
Toxiglossata, 288, 308.
Toxopneustes, 147.
Trachea, 33, 367.
Trachea of Poli, 260.
Tracheliastes, 348.
Tracheliidze, 71.
Trachelius, 76.
Trachelobdella, 205.
Trachelocerca, 71.
Trachelomonas, 55.
Tracheopnoa, 363.
Trachydra, 94.
Trachydridze, 94.
Trachynema, 95.
Trachynemidz, 88, 95.
Trachynotus, 217.
Trachyplana, 160.
Traquairia, 61.
Travisia, 222.
Trematoda, 172.
Tremoctopus, 326.
Trepang, 153-
Treutler, 175-
Triznophorus, 165.
Triarthus, 196.
Trias formation, 46.
Tricelis, 160.
Trichaster, 136.
Trichina, 181, 186.
Trichocephalus, 179, 181, 186.
Trichocysts, 71.
Trichoda, 72.
Trichodectes, 399.
Trichodina, 66, 70.
Trichodinidz, 70.
Trichodiscus, 58.
Trichomonas, 55.
Trichoptera, 406.
Trichopterygide, 414.
Trichosoma, 179.
Trichosomum, 186.
Trichotrachelide, 186.
Tridacna, 261, 270.
Trifora, 257.
Trigonella, 271.
Trigonia, 263, 269.
Trilobitida, 47, 351.

Index. 459

Triloculina, 51.
Trimya, 261.
Triopa, 294, 305.
Tniopide, 305.
Tniophthalmus, 197.
Triplechinidz, 147.
Triploblastica, 79.
Triptera, 279.
Tristomum, 173.
Tristomida, 173.
Tripneustes, 147.
Tritozooids, 35.
Tritoniidz, 304, 308.
Tritonium, 290, 308.
Trivia, 308.
Trivium, 147.
Trochammina, 53.
Trochal discs, 194.
Trochetia, 204.
Trochidz, 307.
Trochocyathus, 116.
Trochocyclus, 277.
Trochus, 207, 291, 302.
Trochosmilia, 117.
Troglocaris, 356.
Trogulus, 373.
Trombidium, 8, 364.
Trophon, 309.
Trophosome, 85.
Tropidocercus, 185.
Troschel, 141, 239.
Truncatulina, 53.
Trymohelia, 117.
Tubiclava, 91.
Tubicola, 257.
Tubifex, 213, 218.
Tubiporacez, 120.
Tubipora, 120.
Tubitelee, 375.
Tubularia, 85, 90, 95.
Tubularide, 93.
Tubulanus, 162.
Tubulata, 229.
Tubulosa, 116.
Tunicata, 15, 231.
Tunicin, 231.
Turbanella, 209.
Turbellaria, 155.
Turbo, 281, 309.
Turbinaria, 116.
Turbinolia, 116.
Turbinolide, 116.
Turride, 91.
Turris, 91.

460

Turritellide, 310.
Turritopsis, 91.
Tylodina, 305.
Tympanum, epithelium of, 13.
Type, 38.

Typhus, 285, 309.
Typhlocyba, 400.
Typhlobdella, 205.
Typhloplana, 161.
Typhlolepta, 160.
Tyrosin, 8.

Udonella, 173.

Ulactis, 114.

Ulonata, 403.

Umbellularia, 121.

Umbilicus, 285.

Umbo, 256.

Umbrella, 102, 290, 294, 295, 300.
Uncini, 28.

Uncus, 195.

Undulina (Trypanosoma), 66, 63.
Ungulina, 262.

Ungulinidz, 270.

Unifora, 258, 265.

Unio, 259, 261, 265, 266, 269, 270.
Unionacex, 262.

Unionidee, 262.

Univalve, 243.

Urania, 246.

Uraster, 134.

Urea, 7.

Umnatellidz, 230.

Urocentrum, 70.

Uroceride, 421.

Uroglena, 57.

Urolabes, 189.

Uroleptus, 71.

Uropods, 355.

Urostyle, 72.

Uvella, 57.

Uvellina, 54.

Vacuoles, 4.
Vagabunde, 375.
Vaginicola, 66.
Vaginulus, 290.
Valenciennes, 6.
Valencinia, 3, 162.
Valentia, 143.
Valvata, 295, 309, 310.
Valvatidze, 310.
Valvula, 407.
Valvulina, 53.

Index.

Vampyrella, 49.
Vanes, 113.
Varieties, 39.
Veins, 32.
Velella, 99, Iol.
Velellidz, Ior.
Velum, 89, 298.
Venus, 256, 270.
Veneraceze, 270.
Veneridz, 220.
Veretillide, 121.
Veretillum, 121.
Vermes, 48, 200.
Vermetide, 310.
Vermetus, 285, 298.
Vermicella, 122.
Verongia, 16.
Veronicella, 311.
Veroneidz, 345.
Vertebre, 134.
Vertebrata, II, 47.
Vertigo, 312.
Vesicula intima, 60.
Vesiculariadee, 229.
Vespa, 420.
Vespide, 420.
Vexillum, 109.
Vibracula, 226.
Vibriones, 9.
Villiersia, 305.
Virgularia, 129.
Vitellin, 6.
Vitellus, 36.
Vitrina, 312.
Vogt, 177.
Vogtia, 98.
Volkmann, 6.
Voluta, 281, 309.
Volutidze, 309.
Volva, 308.
Vortex, 155.
Vorticella, 66.
Vorticellidze, 69.
Vorticerus, 161.
Vorticlava, 92.
Vulsella, 247, 268.

Wagener, 20, 171.

Wagner, 183.

Wagneria, 71.

Waldeyer, 14.

Waldheimia, 247.

Waller, 2.

Water-lungs Holothurian, 149.

Index. 461

Water vascular system, 33, 166, 173, | Xylocopa, 420.

195, 293- Xylophaga, 408.
Wax organ, 383. Xylotropha, (Cossus), 405.
Weber, 3.
Wedlia, 173. Yellow cells of Radiolaria, 61.
Weinland, 170. Yellow elastic tissue, 15.
Weisse, 196.
Weissmann, 393. Zaddach, 398.
Wheel organ of Pneumodermon, | Zamicsoma, 268.

278. Zanclea, 92.
White corpuscles, 2. Zaphrentis, I15.
Wicke, 292. Zetes, 370.
Will, 107. Zoantharia, 113.
Willsia, 92. Zoanthide, 114.
Winkler, 21. Zoanthodema, 120.
Wittich, Von, 16. Zoanthus, 114.
Wright, E. P., 119, 120, 146. Zoea, 342.
Wright, T. S., 58, 82, 94. Zonites, 198, 312.
Wrisberg, 58, 66. Zonites, 297.
Zocecia, 229.

Xanthea, 95. Zooid, 32.
Xanthin, 7. Zoothamnion, 69.
Xenia, 119. Zygocyrtide, 62.
Xenophora, 310. Zygocystis, 65.
Xenospongia, 77. Zygoselmis, 55.
Xiphigorgia, 122. Zygostephanus, 60.

Xyphosura ( = Peecilopoda), 351.

END OF PART TI.

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