■
THE
EAY SOCIETY.
INSTITUTED MDCCCXLIY.
wo . °IZ3
This volume is issued to the Subscribers to the Ray Society for
the Year 1911.
LONDON:
MCMXII.
A MONOGRAPH
OF THE
BRITISH DESMIDIACEJE
BY
W. WEST, F.L.S.,
Lecturer in Botany, Biology, and Bacteriology at the Technical
College, Bradford ,•
Ex-president of the Yorkshire Naturalists' Union;
AND
G. S. WEST, M.A., D.Sc, F.L.S., A.R.C.S.,
Professor of Botany at the University of Birmingham ; Formerly Professor
of Natural History at the Royal Agricultural College, Cirencester ;
and Scholar and Hutchinson Research Student of St. John's
College, Cambridge
VOLUME IV
LONDON
PRINTED FOR THE RAY SOCIETY
1912
PRINTED BY ADLARD AND SON
LONDON AND DOKKING
CONTENTS OF VOL. IV.
PAGE
Additional Bibliography . . . ■ . - . xi
Family Desmidiaceje.
Sub-Family II. Placodekm.e.
Tribe 5. Cosmari.e.
GrENtrs 15. Cosmarium i concluded) . . 1
„ 16. Xanthidiuh . . . . . -18
,, 17. Arthrodesmus . . . .88
18. Staurastrum . . . . .118
LIST OF THE PLATES.
Figs.
Figs
Figs.
Figs.
Fia-s,
Figs.
Plate XCVI.
1-2. — Cosmariwm Botrytis
(P. 1)
Plate XCYII.
1-6. — Cosmariwm Botrytis
(P- 1)
7-8. — C. controversum (p. 9)
9-11. C. tuberculatum (p.
42)
Plate XCVIII.
1-7. — Cosmarium ochthodes
(p. 10)
8. — C. coronation (p. 13)
9-15. — C. crenatum (p. 35)
Plate XCIX.
1-6. — Cosmarium cousjier-
sum (p. 13)
7. — C. Logiense (p. 16)
8-10. — C. margaritatuin (p.
18)
Plate C.
1 . — Cosma riu m ma rgari-
tatiim (p. 18)
2-6.— C. Quad rum (p. 20)
7-9. — C. Pseudobroomei (p.
22)
10-11.— C. Subbroomei (p. 23)
12. — C. Broomei (p. 24)
Plate CI.
1—15. — Cosmarium biretum
(p. 25)
Plate CII.
File's. 1-6. — Cosmarium amrenum
(p. 29)
,, 7-12. — C. pseud amoenum (p.
31)
,, 13-18. — G. annulatum (p. 39)
„ 19-21. — C. elegantissimiim (p.
40) "
,, 22. — C. punetulatum (Con-
sult Vol. Ill, p. 207)
Plate CHI.
Figs. 1. — Cosmarium basilicum
(p. 44)
2-3. — C. prominulum (p.
46)
4. — C. Portianum (Con-
sultVol. Ill, p. 166)
5-6. — C. Gayanum (p. 7)
7. — C. Pseudobroomei (p.
22,
8.— C. Botrytis (p. 1)
9. — C. amoenum (p. 29)
10.— C. Wittrochii (Consult
Vol. Ill, p. 179)
11—13. — C. taxichoiidrum (p.
45)
14. — Xanthidium subhasti-
ferum (p. 56)
Plate CIV.
Fitjs. 1-5. — Xanthidium armatum
(p. 51)
Plate CV.
Figs. 1-5. — Xanthidium armatum
(p. 51)
VIM
MSI OF THE PLATES.
Plate CVI.
Pigs. 1 I. Xanthidium armatum
(p. 51)
5 11. X. 8ubha8tiferum (p.
56)
Plate CVII.
Pigs. 1 b. Xanthidium tetracen-
trotum (p. 58)
5 8. X. controversum\(jp.
59)
9—10 X. subhastij'erum (p.
56)
Plate CVHT.
Pigs. 1 6. — Xanthidium Smithii
(p. 61)
i 19. — X. antilopasum (p.
63)
Plate CIX.
Pigs. 1 7. -Xanthidium antilo-
pasum (p. 63 )
Plate CX.
17. Xanthidium antilo-
pa "in ( p. 63 )
8-12.— .X. cristatum (p. 70)
Plate CXI.
Figs. I 5. Xanthidium cristatum
(p. 70)
6 9. A . fasciculatum (p.
7:.)
1". A'. N,„///,/,' (p. 61 )
Plate ('XII.
Pigs. 1 1. Xanthidium Brebis-
>■ (p. 77 i
5 9. A', uculeatum (p. 78
• • 1" 12. A. cowcinnMw (p. 86)
Plate CXIII.
Plate CXIII — continued.
Pigs
8. — X. Robinsonianum (p.
83)
9. — X. apiculiferum (p.
85)
„ 10-12. — X. Orcadcnse (p. 84)
13-24.- -Arthrodesmus Incus
(P- 90)
Plate CXIV.
Figs. 1-10. — Arthrodesmus Incus
(p. 90)
„ 11-17. — .4. triangularis (p.
97)
Plate CXV.
Figs. 1-5. — Arthrodesmus trian-
gularis (p. 97)
„ 6-7. — A. quiriferus (p. 101)
,, 8-11. — J-. crassus (p. 102)
,, 12-14. — J., controversus (p.
103)
,. 15-17.— A. phimus (p. 104)
,, 18. — J., quiriferus (p. 101)
Plate CXVI.
Figs. 1-3. — Arthrodesmus Buln-
heimii (p. 105)
,, 4-13. — J., convergens (p. 106)
,, 14. — A. subulatus (p. 109)
Figs
Fi
Plate CXVII.
1—5. — Arthrodesmus subu-
latus (p. 109)
6-10. — J., octocornis (p. Ill)
11-16.— X ///7/-///.S- (p. 113)
17. — A. trispinatus (p.115)
18-20. — ,4. ft nuixsimus (p.
116)
21. — /l. octocornis (p. Ill)
22 — X phimus (p. 104)
23 24. — Xanthidium aculea-
tum (p. 78)
Plate CXVIII.
1 7. Xanthidium variabile Figs. 1-3.— Xanthidhim Robin-
{ l'- y ' ' .<<, a in, i a m (p. 83)
LIST OF THE PLATES.
IX
Plate CXYIII — continued.
Figs. 4-6. — Stanrastrum Meriani
(p. 122)
,, 7-10. — St. Capitulum (p.
124)
„ 11-14.— St. pileolatum (p. 127)
,, 15. — St. rhabdophorum (p.
129)
,, 16-20. — St. muticum (p. 133)
Figs.
Figs.
Plate CXIX.
1. — Staurastrum muticum
(p. 133)
2-6. — St. minutissimum (p.
130)
7. — St. ellipticum (p. 138)
8-10. — *SV. coarctation (p.
139)
11-13.— St. granite (p. 140)
Plate CXX.
1-3. — Staurastrum grande
(p. 140)
4-8. — St. Bieneanum (p.
135)
9-13. — St. aversum (p. 144)
Plate CXXL
Figs.
1—2. — Staurastrum con-
spicuum (p. 143)
3-7. — St. lanceolatum (p.
149)
8-9. — St. pachyrhynchum
(p. 151)
Plate CXXII.
1-5. — Staurastrum tumidum
(p. 142)
6-10.— St. Clepsydra^. 152)
Plate CXXIII.
Figs. 1-7. — Staurastrum brevi-
spinum (p. 145)
8-10. — St. angulatum (p. 154)
Figs.
Figs.
Figs
Plate CXXIV.
1. — Staurastrum subpyg-
mseum (p. 162)
2-4.— St. inelegans (p. 153)
5-19. — St. orbiculare (p. 155)
Plate CXXV.
1-2. — Staurastrum orbicu-
lare (p. 155)
,, 3-5. — St. suborbiculare (p.
159)
„ 6-8. — St. retusum (p. 160)
„ 9-10.— St. tortum (p. 161)
,, 11-12. — St. Cosmarioides (p.
161)
,, 13-16. — *SY. subpygmseum (p.
162)
,, 17-22. — St. corniculatum (p.
163)
Plate CXXVI.
Figs. 1—2. — Staurastrum tracliy-
tithophorum (p. 165)
3. — St. rugulosum (p.
178)
4. — St. botrophilum (p.
166)
5-6. — St. turgescens (p. 167)
7. — St. Donardeuse (p.
169)
8-9. — St. alternans (p. 170)
10-15, 18.— St. dilatatum (p.
172)
., 16,17,19. — St. disputation (p.
176)
Figs
Plate CXXVII.
1-6.
Staurastrum strio-
latum (p. 177)
7.— St. dispar (p. 187)
,. 8-15, 17-22. — St. punctulatum
(p. 179)
,, 16. — St. alternans (p. 170)
23.— St. inflation (p. 191)
,, 24.— St. turgescens (p. 167)
X
LTST OF TIIF PLATES.
Plate CXXVIII.
Pigs. 1-0,9. — Staurastrwn punctu-
latum (p. 179)
7-8.— St. pilosellwn (p. 187)
„ 10-14. — St. granulosum (p.
188)
Plate CXXVIII — contin ued.
Figs. 15. — St. paxilliferum (p.
190)
,, 16. — Arthrodesmus trian-
gularis (p. 97)
(xi)
ADDITIONAL BIBLIOGRAPHY.
(See ArOL. I, pp. xvii-xxxvi; Vol. II, p. x; Vol. Ill,
pp. xiii-xv.)
Bachmann, Phytoplankton Seen Schottl. it. Schweiz. — H. Back-
mann, Vergleichende Studien iiber das Phytoplankton
von Seen Schottlands und der Schweiz. Archiv fih*
Hydrobiol. und Planktonkunde, Bd. iii, 1907.
Bernard, Protoc. et Desmid. Java. — C. Bernard, Protococ-
cacees et Desmidiees d'eau douce recoltees a Java.
Departement de ^Agriculture aux Indes-Neerlandaises.
Batavia, 1908.
Bernard, Alg. unicell. domains Malais. — C. Bernard, Sur
quelques Algues unicellulaires d'eau douce recoltees dans
le domaine Malais. Departement de l'Agriculture aux
Indes-Neerlandaises. Batavia, 1909.
Borge, Nordamerik. Siisxwasseralg. — 0. Borge, Nordameri-
kanische Siisswasseralgen. Arkiv. for Botanik utgiv. af
K. Sv. Vet.-Akad. Stockholm, Bd. 8, no. 13, 1909.
Borge, Siissw.-Algenfl. Spitzberg. — O. Borge, Die Siisswasser-
algenflora Spitzbergens. Videnskapsselskapets Skrifter.
I. Mat.-naturv. klasse, 1911, no. 11.
Borge, Algol. Notiz. 6-7. — O. Borge, Algologische Notizen,
6-7. Botaniska Notisei', 1911.
Borg. Freshiv. Alg. Damn. Dxped. N. E. Greenland. — F. Bor-
gesen, Freshwater Algae from the"Danmark-Expedition"
to North-east Greenland (N. of 76° N. lat.). Arbejder
fra den Botaniske Have i Kobenhavn, No. 53. 1910.
xii ADDITIONAL BIBLIOGRAPHY.
Coshman in Bull. Ton: Bot. Club— J. A. Cuslnnan, various
papers on North American Desinids in the Bulletin of
the Torrey Botanical Club, xxx, 1903, pp. 513-514 ;
wxi, 1904, pp. 161-164, pp. 393-397, pp. 581-584;
xxxii, 1905, pp. 223-229, pp. 549-553; xxxiii, 1906, pp.
343-35 1; xxxiv, 1907, pp. 599-601, pp. 607-615; xxxv,
1908, pp. 109-134.
Cushman in Ehodora.—J. A. Cuslnnan, various papers on
North American Desinids in Rhodora (Journal of the
New England Botanical Club), v, 1903; vi, 1904; vii,
1905; ix, 1907; x, 1908.
Cushman, Oliio Desmids. — J. A. Cuslnnan, A few Ohio Desmids.
The Ohio Naturalist, v, 1905, no. 7.
Georgev. Desm. Macedon. — P. Georgevitch, Desmidiaceen aus
dem Prespasee in Macedonien. Beihefte zum Botan.
Centralblatt, Bd. xxvi, 1910.
Georgev. Desm. Wlasina-See. — P. Georgevitch, Desmidiaceen
aus dem Wlasina-See [Servia] . Beihefte zum Botan.
Centralblatt, Bd. xxvi, 1909.
Gutw. Flor. Alg. Mont. Tatr.—R. Gutwinski, Flora Algarum
Monti inn Tatrensium. Bull, de l'Acad. des Sciences de
Cracovie, Avril, 1909.
Heering & Homf. Alg. Eppendorf. Moores.—W. Heering and
H. Homfeld, Die Algen des Eppendorfer Moores bei
Hamburg. Verhandl. Naturw. Vereins in Hamburg,
1904, 3. Folge xii.
Hustedt, Desm. et Bacill. aus Tirol— F. Hustedt, Desmidi-
aceae et Bacillariese aus Tirol. Archiv fur Hvdrobiol.
und Planktonkunde, Bd. vi, 1911.
Lai:sen, Fershvandsalg. Vest-Gh'bnl.—E. Larsen, Ferskvand-
salger fra Vest-Gronland. Arbejder fra den Botaniske
Have i Kobenhavn, no. 36, 1907.
Lemm. Plankton Jang-tse-hiang. — E. Lemmermann, Das
Plankton des Jang-tse-kiang (China). Archiv fur
Hvdrobiol. und Planktonkunde, Bd. ii, 1907.
ADDITIONAL BIBLIOGRAPHY. xiii
Lemh. Beitr. Kenntnis Planktonalg. — E. Leramermanii,
Beitrage zur Kenntniss der Planktonalgen, XXV] -
XXX. Archiv fur Hydrobiol. and Planktonkunde, Bd.
v, 1910.
Lutkem. Desm. Bbhm. — J. Liitkemuller, Zur Kenntniss der
Desmidiaceen Bohmens. Verhandl. der k. k. zool.-bot.
Ges. Wien, 1910.
Murkay, Dlstrib. Pelag. Organisms in Scott. Lakes. — James
Murray, On the Distribution of the Pelagic Organisms
in Scottish Lakes. Proc. Roy. Physical Soc. Edinburgh,
June 1905.
Ostenf. Algeiifl. Kossogol-Beckens in Mongolei. — C. H. Osten-
feld. Beitrage zur Kenntnis der Algenflora des Kossogol-
Beckens in der nordwestlichen Mongolei, mit spezieller
Beriicksichtigung des Phytoplanktons. Hedwigia, Bd.
xlvi, 1907.
Ostenf. Phytoplunkton Viet. Nyanza. — C. H. Ostenfeld, Phyto-
plankton aus dem Victoria Nyanza. Bugler's Botnn
Jahrbiich. Bd. 41, Heft 5, 1908.
Playfaie, New or Less-Known Desm. N. S. Wales. — Gr. I.
Playfair, Some New or Less Known Desmids of New
South Wales. Proc. Linn. Soc. New South Wales, 1907,
xxxii, part I.
Playfair, Some Sydney Desmids. — Gr. I. Playfair, Some
Sydney Desmids. Proc. Linn. Soc. New South Wales,
1908, xxxiii, part 3.
Playfair, Polymorphism and Life-History in the Desmidiacese.
Proc. Linn. Soc. New South Wales, 1910, xxxv, part 2.
Teodoeesco, Mater, for. alg. Bowman. — E. C. Teodoresco,
Materiaux pour' la flore algologique de la Roumanie.
Beihefte zum Botan. Centralblatt, Bd. xxi, Abt. ii, 1907.
Viket, Desm. Vallee du Trient. — L. Viret, Desmidiacees de la
Vallee du Trient (Valais, Suisse). Bull, de la Soc. bot.
Geneve, vol. i, 1909.
G. S. West, Alg. Tan Tean.—Gr. S. West, The Algae of the
Yan Yean Reservoir : a Biological and (Ecological Study.
Journ. Linn. Soc. bot. xxxix, March 1909.
XIV ADDITIONAL BIBLIOGRAPHY.
(I. S. West, Algol. Notes.— G. S. West, Algological Notes,
I-IV. Journal of Botany, March 1911.
\Y. & (i. S. West, Brit. Freshw. PhytoplanMon, etc. — W. West
and Gr. S. West, The British Freshwater Phytoplankton,
with Special Reference to the Desmid-plankton and the
Distribution of British Desinids. Proc. Roy. Soc. B,
vol. 81, 1909.
W. & G. S. West, PhytoplanMon Engl. Lake District,— W.
West and G. S. West. The Phytoplankton of the English
Lake District. The Naturalist, March-May, July-Sept.
1909.
BRITISH DESMIDIACE.E.
225. Cosmarium Botrytis Menegh.
(PI. XCVI, figs. 1, 2, 5-15.)
-? ?
Heterocarpella Botrytis Bory in Dictionnaire classiq. cTHist. nat. viii,
1825, p. 180. [Description too imperfect for identification.]
? ? Cosmarium deltoides Corda in Almanach de Carlsbad, 1835, p. 178, t. 2,
f. 18, 19. [C. Botrytis according to Ealfs.]
Cosmarium Botrytis Menegh. Synops. Desm. 1840, p. 220 ; Ealfs in Ann.
Mag. Nat. Hist, xiv, 1844, p. 393, t, 11, f. 5 ; Hass. Brit. Freshw. Alg.
1845, p. 363, t. 86, f. 2 ; Kutz. Phyc, germ. 1845, p. 136; Ealfs, Brit.
Desm. 1848, p. 99, t. 16, f . 1 ; Kutz. Spec. Alg. 1849, p. 175 ; De Bary,
Conj. 1858, p. 38, 45-51, 72, t. 6, f. 1-24 ; Arch, in Pritch. Infus. 1861,
p. 733, t. 3, f. 48-54 ; Eabenh. Plor. Europ. Algar. Ill, 1868, p. 158 ;
Nordst. Desm. Brasil. 1870, p. 207 ; Delp. Desm. subalp. 1877, p. 22, t.
8, f. 31-39 [figures poor] ; Kirchn. Alg. Schles. 1S78, p. 151 ; Wille,
Ferskv. Alg. Nov. Semlj. 1879, p. 34; Klebs, Desm. Ostpreuss. 1879, p.
38, t. 3, f . 62, 63, and possibly others [figures inaccurate] ; Mask. N.
Zeal. Desm. Add. 1883, p. 251 ; ? Wolle, Desm. U. S. 1884, p. 74, t. 13,
f. 5 (6 and 7 ?) ; Wille, Sydamerik. Algfl. 1884, p. 14 ; Cooke, Brit.
Desm. 1887, p. 105, t. 39, f. 4 [figures poor] ; Hansg. Prodr. Algenfl.
Bohm. 1888, p. 199 ; Boldt, Desm. Gronland, 1888, p. 28 ; Hauptfl.
Zellmembr. u. Hullgallerte Desm. 1888, p. 86, 111, t. 2, f. 46, 51, 56;
De Toni, Syll. Alg. 1889, p. 979 ; Borg. Desm. Brasil. 1890, p. 37 ;
West, Alg. N. Wales, 1890, p. 2S9 ; Borge, Chlorophy. Norska Pinmark.
1892, p. 9 ; Eacib. Desmidyja Ciastonia, 1892, p. 390 ; West, Alg. W.
Ireland, 1892, p. 155 ; Alg. Engl. Lake Distr. 1892, p. 727 ; Lutkem. Desm.
Attersees, 1893, p. 556; Borg. Ferskv. Alg. Ostgronl. 1894, p. 13 ; Eoy
& Biss. Scott. Desm. 1894, p. 44 ; Borge, Siissw. Chlorophy. Archang.
1894, p. 19 ; Nordst. Index Desm. 1896, p. 64 ; West k G. S. West, Alg.
S. England, 1897, p. 490 ; Borge, Trop. u. subtrop. Siissw.-Chlor. 1899,
p. 19 ; G. S. West, Alga-fi. Cambr. 1899, p. 218 ; West & G. S. West,
Alga-fl. Yorks 1900, p. 82 ; Borg. Freshw. Alg. Faeroes, 1901, p. 227 ;
West & G. S. West, Alg. N. Ireland, 1902, p. 39 ; Hirn, Desm. Finnland,
1903, p. 7 ; West & G. S. West, Scott. Freshw. Plankton, 1, 1903, p. 527 ;
Larsen, Freshw. Alg. E. Greenland, 1904, p. 83 ; West & G. S. West,
Freshw. Alg. Orkneys and Shetlands, 1905, p. 21 ; Further Contrib.
Plankton Scott. Lochs, ]905, p. 484 ; Comp. Study Plankton Irish Lakes,
1906, p. 85 ; Phytoplankton Engl. Lake District, 1909, p. 137.
Euastrum interstitiale Kutz. Phycol. germ. 1845, p. 136. [ = C Botrytis
according to Kutzing in Ealfs' Brit. Desm. 1848, p. xix.]
VOL. IV. 1
2 J'RITISH DESMID1ACE K.
Cosmarium Botrytis var. interstitiale Kiitz. Spec. Alg. 1849, p. 175.
Euastrum (Cosmarium) Botrytis Nag. Gatt. einzell. Alg. 1849, p. 119, t.
7a, f. 3 ; Gay, Monogr. loc. Conj. Montpellier, 1884, p. 63.
Didymidium (Cosmarium) Botrytis Eeinsch, Algenfl. Frank. 1867, p. 120
[in part].
? Cosmarium Botrytis var. pseudospeciosa Istvanffi, Diag. prsev. Alg. nov.
Hungar. 1887, p. 236.
Ursinella Botrytis Knntze, Eevis. gen. plant. 1891, p. 923. [Vide Nordst.
in Hedwigia, 1893, p. 152.]
Cells above medium size, about 1J— 1J times as long*
as broad, deeply constricted, sinus narrowly linear with
a dilated extremity ; semicells ovate-pyramidate from
a broad, flat base, basal angles rounded, sides convex,
apex rather narrowly truncate or subtruncate, apical
angles rounded. Side view of semicell broadly elliptic.
Vertical view elliptic, ratio of axes about 1 : 1*8.
Cell-wall uniformly granulate, granules somewhat
small and generally without any definite disposition
(sometimes with a slight indication of a concentric
arrangement or even a disposition in decussating*
oblique series), about 30-36 visible at the margin of
the semicell. Chloroplasts axile, with two pyrenoids
in each semicell.
Zygospore globose, furnished with short, stout
processes, 3 (rarely 4) -fid at the apices, and generally
arising from broad, expanded bases.
Length 65-90 fx; breadth 51-68 /x; breadth of
isthmus 17-24 fx; thickness 33-40 jx; diam. zygosp.
without processes 54-66 [x, with processes 69-84 /x.
England. — Cumberland ! Westmoreland! (Ralfs).
Lancashire ! W., N., and E. Yorks. (zygospores from
Markington and Pilmoor) ! Cheshire (Boy). Leices-
tershire (Roy). Lincolnshire ! Norfolk ! Suffolk !
Essex! (Ralfs). Cambridgeshire! Warwickshire!
(Wills). Worcestershire! Gloucester ! (Ralfs). Mid-
dlesex (zygospores from Harefield) ! Surrey (zygo-
spores from Frensham Great Pond) ! Sussex (Ralfs).
Kent! Hants! Wilts ! Devon! (Bennett). ' Corn-
wall ! (Ralfs). Not uncommon in the plankton !
Wales. — General ! Frequent in the plankton !
Scotland. — General ! Zygospores from Loch Kin-
COSMARIUM. 3
ellan, Ross (Eoy § Blssett). Orkneys! Shetlands !
Lewis, Harris, X. and S. LTist, Outer Hebrides !
Common in the plankton !
Ireland. — Common ! Plankton of the lakes of
Mayo, Gralway, and Kerry !
Geogr. Distribution. — France. Belgium. Germany.
Austria and Galicia. Roumania. Bosnia. Hungary.
Italy. Portugal. Norway. Sweden. Denmark. Born-
holm. Finland. Poland. N. and S. Russia. Faeroes.
Iceland. Nova Zembla. Spitzbergen. Greenland.
Siberia. Mongolia. China. Japan. Afghanistan
(var.). Ceylon. Burma (var.). New Zealand. Azores.
United States. Brazil. Argentina. Patagonia.
C. Botrytis is the most generally distributed species of the
genus in the British Islands, and possibly in the whole of
Europe. It is found in all kinds of situations from stagnant
hogs to well-aerated, dripping rocks, hut occurs most abun-
dantly at the margins of pools and lakes. It is not uncommon
in the freshwater plankton, and in small pools it is frequently
found with zygospores. The granulation of the cell-wall is
of a uniform character, and the granules as a rule have no
definite disposition. The form of the semicell is somewhat
variable, but it is always distinctly pyramidate, with convex
sides, and an apex which is more or less truncate.
Within the arctic circle the species is often rather diminutive,
and Boldt records specimens from Greenland with a length
of only 49*2 /z and a breadth of 43'2/j.
Being such a cosmopolitan species, C. Botrytis exhibits a
considerable amount of variability, and in consequence of
this it has been overloaded with named varieties. "We have
attempted to clearly draw up the characters of about seven of
these varieties, which have been discovered in various parts
of the British Islands.
The development of the zygospore is better known in C.
Botrytis than in any other species of the tribe Cosmarieae. It
was worked out by De Bary in 1858 (Consult Vol. I, p. 11,
and this volume, PL XCVI, figs. 7-15).
Wille ('Ferskv. Alg. Nov. SeinljV 1879, p. 35) has described
a "forma obliqua," in which one side of the vertical view is
flat and the other almost semicircular; length 63 fi; breadth
46 fi. Both semicells were apparently deformed, their outline
in front view being somewhat irregular.
4 BRITISH DESMIDlACEiE.
C. Botryfis var. afghanicum Schaarschm. (' Afghan. Alg.'
1884, p. 245, t. 5, f. 19) is not a form of C. Botrytis.
Var. paxillosporum var. nov. (PI. XCVI, figs. 3, 4.)
Cell-wall minutely punctate between the granules.
Zygospore furnished with short, blunt spines, each of
which arises from the apex of a mamillate or bluntly
conical projection.
Length 72-80 fx ; breadth 57-61 fx; thickness
29-36 /a; diam. zygosp. without spines 42-56 /x, with
spines 60-72 fx.
England. — Yorkshire ! Surrey (zygospores from
Frensham Great Pond, and from pond east of Chapel
Wood) ! Cornwall !
Scotland. — Sutherland ! Near Kirkwall, Orkneys !
The vegetative cells of this variety differ only in the
presence of distinct punctulations between the granules, but
the zygospore differs markedly from that of typical G. Botrytis
in the blunt spines which arise from conspicuously swollen
bases. The spines of the mature zygospores remain bluntly
rounded with no trace of apical denticulations.
Var. subtumidum Wittr. (PI. XCVTI, fig. 1.)
C. Botrytis var. subtumidum Wittr. Gotl. Ol. sotv. Alg. 1872, p. 57, t. 4,
f. 12; Boldt, Desm. Gronland, 1888, p. 28; Andersson, Sverig. Chlor.
1890, p. 14 ; Schmidle, Chlorophy.-Fl. Torfstiche yirnheim, 1894, p. 58 ;
Koy & Biss. Scott. Desm. 1894, p. 44 ; Borge, Beitrage Alg. Schweden,
1906, p. 30.
Cells rather wider than in the type, basal angles
more projecting, slightly tumid in the centre of the
semicells, and with the granules covering the tumour
somewhat larger than the rest of the granules.
Length 52-80 ^ ; breadth 43-65 ju, ; breadth of
isthmus 10-15 /x; thickness 28-38'4 /x.
Scotland. — Aberdeen, Kincardine, Perth (Roy Sf
Bissett).
Geogr. Distribution. — Germany. Gralicia in Austria.
Sweden. N. Russia. Greenland. Siberia.
This variety must be exceedingly rare, and we have never
seen any form of C. Botrytis that we could with justice refer
to it.
COSMAEITJM. 5
Var. tumidum Wolle. (PL XCVII, figs. 2, 3.)
C. Botrytis var. tumidum Wolle, Desm. U. S. 1884, p. 75, t. 17, f. 3-5
[figures not accurate] ; Schmidle in Ber. Deutsch. Botan. Ges. x, 1892,
p. 210, t. 11, f. 13-14 ; Beitr. Algenfl. Schwarzwald. u. Rheineb. 1893,
p. 99, t. 4, f. 25 [figure not good] ; West & G. S. West, Alg. S. England,
1897, p. 490 ; Freshw. Alg. Orkneys and Shetlands, 1905, p. 21 ; Further
Contrib. Plankton Scott. Lochs, 1905, p. 484.
C. Subbotrytis Schmidle, Alg. Bern. Alp. 1894, p. 93.
Semicells with central tumour causing an inflation
on each side of the vertical view ; granules of the
central tumour larger than the other granules, and
with a very irregular disposition ; often with one large
granule adjacent to the isthmus.
Zygospore exactly as in the type.
Length 6-5-85 fx ; breadth 50-68 jx ; breadth of
isthmus 17-20 /x; thickness 34-38 /x.
England. — Epping Forest, Essex ! Near Goring,
Oxfordshire (with zygospores) !
Scotland. — Inverness ! Lewis, Outer Hebrides !
Shetlands ! Plankton of Loch Shiel, L. Cuthaig !
Genqr. Distribution. — Germany. Australia. United
States.
We see no justification for the separation of this variety as
a species distinct from C. Botrytis. It differs from the type
only in the slight central tumour adorned with granules of a
rather larger size than the other granules of the cell- wall.
Var. gemmiferum (Breb.) Nordst. (PI. XCVII,
fig. 4.)
Cosmarium gemmiferum Breb. Liste Desm. 1856, p. 301 ; Arch, in Pritch.
Infns. 1861, p. 733; Eabenh. Flor. Europ. Alg. 1868, III, p. 159 ; Lund.
Desm. Suec. 1871, p. 26 ; Nordst. in Wittr. & Nordst. Alg. Exsic. 1886,
no. 826 ; De Toni, Syll. Alg. 1889, p. 985.
C. Botrijtis var. gemmiferum (Breb.) Nordst. Bornh. Desm. 1888, p. 191 ;
G-utw. Flor. Glonow Okolic Lwowa, 1891, p. 52.
Ursinella gemmifera Kuntze, Eevis. gen. plant. 1891, p. 924.
Semicells with a central granulated tumour sur-
rounded by a smooth area of small extent, towards
which the surrounding granules are slightly reduced
in size ; vertical view with a small inflation on each side.
Length 65-89 /x ; breadth 55-72 [x ; breadth of
isthmus 14-24 fx ; thickness 35-48 jx.
6 BRITISH DESMIDIACE.E.
England. — Enbridge Lake, Hants (Roy). Sutton
Park, Warwickshire !
Scotland. Loch Kinellan and Falls of Connon,
Ross; Loch Ruthven, Inverness; near Alford and
Cambus O'May, Aberdeen; Fife (Roy Sf Bwsett).
Geogr. Distribution. — France. Galicia in Austria.
Sweden. Bornholm. Finland.
This variety differs from var. tumidum Wolle chiefly in the
clear space surrounding the central granulated tumour.
Var. emarginatum Hansg. (PI. CIII, fig. 8.)
('. Ilotnith var. rmn ni'ututinii Hansg. Prodr. Algenfl. Bohm. 1888, p. 199
(c. fig. I L6 : Roy & Hiss. Scott. Desm. 1894, p. 44; Nordst. in Wittr.
.V X..V.lst. Alt;-. Exsic. 1903, no. 1479 ; fasc. 35, p. 13 [forma] ; Teodoresco,
Mater, flor. alg. Rouman. 1907, p. 17i».
Semicells with a blunt notch (about 3/x, deep) in the
middle of the apex, causing an apical emargination ;
granules rather larger than in the type, but other
characters and dimensions are the same.
England. — Brent Reservoir, and in ditches at Kings-
bury Green, Middlesex ! Enbridge Lake, Hants (Roy).
Near Trimpley, Worcestershire!
Scotland. — Not uncommon on wet rocks (Roy Sf
Bissett).
Geogr. Distribution. — Germany. Galicia and Bohemia
in Austria. Roumania. Sweden.
Var. mediolseve West. (PI. XCVII, fig. 5.)
C. Botrytis var. mediolseve West, Alg. W. Ireland, 1892, p. 155,t. 21,f. 12;
Wes1 & Q. S. \\',,i, Alg. s. England, 1897, p. 490; G. S. West, AJga-fl.
Cambr. L899, p. 218; West & G. S. West, Alga-fl. Yorks. 1900, p. 83 ;
Schmidle in Simmer's Kryptogamenfl. der Kreuzeekgr. Karnten, 1901,
p. lol j Wesl & G. S. West. Alg. X. Ireland. 1902, p. 39.
bochthodes Schmidle, Weit. Beitr. Algenfl. Rheineb. u. Schwarzwald.
L895, p. 7.") (in pari ), fig. 27 a andb [not fig. 26 a-c ( = C. cymatopleurwm
\ar. tyrolicum) ; SchrSder, Beitr. Algen Reiseno-ebirges, 1898, p. 35,
t. 1. i. 11 (?).
Semicells with a smooth and faintly concave apex;
granules arranged in radiating and concentric series,
gradually becoming smaller towards the centre of the
semicel] which is quite smooth. Sides of vertical view
Bubparallel in the middle, and smooth.
COSMARIUM. 7
Length 65-70 fx ; breadth 55-59 fi; breadth of
isthmus 15 ja ; thickness 25-27 /x.
England. — Near Ingleton, TV. Yorks ! Strensall
Common, N. Yorks ! Near Brigg, Lincolnshire ! Lord's
Bridge, Cambridgeshire ! Esher West-end Common,
Surrey ! Hayes Common, Kent !
Ireland. — Churchill, Donegal ! Near Westport,
Mayo ! Nacoogarrow Lough, and between Clifden and
Roundstone, Gralway ! Clogerheen, Kerry !
Geogr. Distribution. — Germany.
This variety should be compared with G. Botrytis var.
mesoleium Nordst. (cDesm. Ital.' 1876, p. 27, t. 12, f. 2), from
which it is distinguished by its proportionately wider semicells,
by the absence of the small central protuberance, and by the
absence of the granules above the isthmus.
Var. depressum AY. & CI. S. West. (PI. XCVII, tig. 6.)
C. Botrytis var. depressum W. & Gr. S. West, Further Contrib. Plankton
Scott. Lochs, 1905, p. 500, t. 7, f . 1 ; Comp. Study Plankton Irish Lakes,
1906, p. So.
Cells shorter than in the type, about as long as
broad ; semicells depressed, basal part very wide and
basal angles very broadly rounded, apical angles very
obtuse.
Length 68-72 /x ; breadth 05-68 /x ; breadth of
isthmus 16-1 7 /u.
Scotland. — Plankton of Loch Ruar, Sutherland !
Ireland. — Plankton of Lough Corrib, Gralway ; and
of Lough Caragh, Kerry !
We have only met with this depressed variety in the
plankton.
It is possible that C. Hyacinthi Gutw. (' Flor. Glon. Okolic
Lwowa/ 1891, p. 62, t. 2, f. 30) is closely related to this
variety, but Gutwinski's figure is not very good. The only
distinction appears to be the presence of a central tumour in
the Galician form.
226. Cosmariimi Gayanum De Toni.
(PI. CIII, figs. 5, 6.)
Euastrum (Cosmarium) ellipticum Gay, Mon. loc. Conj. Montpellier, 1884,
p. 63, t. 2, f. 5 [not C. ellipticum Delp., 1877] ; Note Conj. du inidi
de France, 1884, p. 337.
8 BRITISH DESMIDIACE^.
Cosmarium Gayanum De Toni, Syll. Alg. 1889 (July), p. 994 ; Gutw. Flor.
Glon. Okolic Lwowa, 1891, p. 53 ; Flor. Glon. Okolic Tarnapola, 1894,
p. 94.
C. Gayii Gutw. Wahr. d. Prioritat, 1890, p. 69.
Ursinella Gayanum Kuntze, Revis. gen. plant. 1891, p. 924.
Cells large, in general outline elliptic, about 1| times
as long as broad, deeply constricted, sinus narrowly
linear with a slightly dilated extremity ; semicells
ovate-p3a,amidate from a flat base, basal angles sub-
rectangular but obtuse, sides convex, in the upper part
rather rapidly converging to the somewhat narrow and
subtruncate apex. Side view of semicell elliptic.
Vertical view elliptic, ratio of axes about 1 : 1*6. Cell-
wall finely granulate, granules arranged in radiating
and subconcentric series, about 12 visible on each
lateral margin and 4 at the apex. Chloroplasts axile,.
with two pyrenoids in each semicell.
Zygospore globose, furnished with numerous, short,
rather stout processes (about 21 visible around the
periphery) ; apex of each process 2-3-denticulate.
Length 70-90 ll ; breadth 48-64 jx ; breadth of
isthmus 16-19 ll; thickness 30-36 /x; diam. zygosp.
without processes 60 /x, with processes 95 fx.
Geogr. Distribution. — France. Galicia in Austria.
C. Gayanum is almost of the same outward form as C.
pyramidiitum, but is at once distinguished by its granulate
cell-wall. The granules are very small and disposed in a
very characteristic manner. The typical form has not been
observed in the British Islands.
Var. eboracense nob. (PI. XCIII, figs. 6-8.)
C. eboracense West, Alg. N". Yorks. 1889 (October), p. 292, t. 291, f. 4 ;
Alg. W. Ireland, 1892, p. 155 ; Roy & Biss. Scott. Desm. 1894, p. 100 ;
West & G. S. West, Alga-fl. Yorks. 1900, p. 82.
Granulation of semicells denser, granules more
numerous (19-23 visible on each lateral margin); apex
obscurely 4-6 granulate, rarely smooth and very faintly
concave ; granules in the centre of the semicells con-
siderably reduced.
Length 90*5-1 10//,; breadth 55-68 /x; breadth of
isthmus 20-22 ll ; thickness 39-41 lk.
COSMARIUM. 9
England. — Baildon, Arncliffe, and near Cray Moss,
W. Yorks! Cronkley Fell and Staindale, N. Yorks !
Richmond Park, Surrey !
Scotland. — Craig-an-Lochan, Perth !
Ireland. — Cloonee Lough and Kenmare, Kerry !
This variety differs in the denseness of its granulation, and
in the reduction of the granules in the centre of the semicells.
227. Cosmarium controversum West.
(PI. XCVII, figs. 7 and 8.)
Cosmarium controversum West, Alg. N. Wales, 1890, p. 289, t. 6, f. 31
[figure incorrect] ; Norclst. Index Desm. 1896, p. 81 ; West & G. S.
West, Further Contrib. Freshw. Plankton Scott, Lochs, 1905, p. 485 ;
Brit. Freshw. Phytoplankton, 1909, p. 179 ; Phytoplankton Engl. Lake
District, 1909, p. 287.
Cells fairly large, from 14- to 1-J times as long as
broad, deeply constricted, sinus narrowly linear with
a dilated extremity ; semicells pyramidate-trapeziform,
basal angles rounded, sides very slightly convex,
apical angles rounded, apex broadly truncate. Side
view of semicell ovate-elliptic. Vertical view elliptic,
with a rather small tumour at the middle on each side.
Cell- wall granulate, granules rounded, of uniform size,
arranged in decussating oblique series and in indistinct
vertical series, about 14 oblique series and 18-19
indistinct vertical series (sometimes not at all evident),
and from 30-35 granules visible at the margin of a
semicell ; with a large area in the centre of the
semicell in which there are hexagons of conspicuous,
rounded scrobiculations between the granules. Chloro-
plasts axile, with two pyrenoids in each semicell.
Zygospore unknown.
Length 90-96 /*; breadth 72-7 7 /u. ; breadth of
isthmus 22-32 [x; thickness 45 fx.
England.— Plankton of Grasmere, "Westmoreland !
Wales. — Capel Curig, Carnarvonshire !
Scotland. — Plankton of Loch Fadaghoda, Lewis,
Outer Hebrides !
The original figure of this Desmid represented the species
very indifferently, and the large, scrobiculated central area
10 BR1TISB DESMID1ACEJ3.
was quite omitted. This scrobiculated area occupies the whole
of the central tumour and the adjacent parts of the cell-wall.
It is distinguished from G. Botrytis by the broader apices
of the semicells, by the larger and regularly arranged granules,
and by the tumid and scrobiculated central area of the semi-
cells.
228. Cosmarium ochthodes Nordst.
(PL XCVIII, figs. 1-3.)
Cosmarium ochthodes Nordst. Desm. Arctose, 1875, p. 17, t. 6, f . 3 ; Desni.
Ital. 1876, p. 28; Wille, Ferskv. Alg. Nov. Semlj. 1879, p. 35; Wolle,
Desm. U. S. 1884, p. 76, t. 14, f. 4 ? (not fig. 3); Cooke, Brit. Desm. 1887,
p. 109, t. 41, f. 3 ; Boldt, Desm. Gronland, 1888, p. 29 ; De Toni, Syll.
Alg. 1889, p. 992; West, Alg. N. Wales, 1890, p. 290; Anderss. Sverig.
( !hlor. 1890, p. 14 ; West, Alg. Engl. Lake Distr. 1892, p. 728 ; Borg.
Ferskv. Alg. Ostgronl. 1894, p. 13 ; Boy & Biss. Scott. Desm. 1894, p.
169 ; Nordst. Index Desm. 1896, p. 187 ; West & G. S. West, Alg. S.
England, 1897, p. 490 ; G. S. West, Alga-fl. Cambr. 1899, p. 219 ; West
& G. S. West, Alga-fl. Yorks. 1900, p. 83 ; Lvitkem. Desm. Millstattersees,
1900, p. 10 ; Borg. Freshw. Alg. Faeroes, 1901, p. 228 ; West & G. S.
West, Alg. N. Ireland, 1902, p. 40 ; Larsen, Freshw. Alg. E. Greenland,
1904, p. 87 ; West & G. S. West, Freshw. Alg. Orkneys and Shetlands,
L905, p. 21; Teodoresco, Mater, flor. alg. Rouman. 1907, p. 180.
C. Botrytis A. d. ochthodes Klebs, Desm. Ostpreiiss. 1S79, p. 39.
? ? C. Botrytis var. squamosum Sehaarschm. Magyar. Desm. 1883, p. 263.
Ursinella ochthodes Kuntze, Bevis. gen. plant. 1891, p. 92.">.
Cells rather large, from 1^ to almost 1J- times as
long as broad, deeply constricted, sinus narrowly linear
with a dilated extremity ; semicells ovate-pyramidate
from a flat base, basal angles obtuse or scarcely rounded,
sides convex and upwardly converging to a rather
narrow, truncate apex (sometimes slightly retuse) ;
sides conspicuously crenate or only undulate, crenations
11-13 (commonly 12), small and rounded at the basal
angles, but larger and flattened above. Side view of
semicell obovate. Vertical view elliptic. Cell-wall
densely covered with flattened warts of somewhat
indefinite outline (irregularly circular), disposed in
rather irregular radial and concentric series, and
gradually becoming less distinct towards the centre of
the semicell, which is also often punctulate. Chloro-
plasts axile, with two pyrenoids in each semicell.
Zygospore globose, furnished with a few short, very
thick spines (about 11 visible around the margin);
apices of spines obtuse or slightly emarginate.
COSMAKIUM. 11
Length 70-94 /x; breadth 51-67 /a; breadth of
isthmus 1 7*5-27 /x; breadth of apex 19-25 //.; thick-
ness 34-43 ju ; diam. zygosp. without spines (50 /x, with
spines 70 /x; length of spines 6-7*5 /a.
England. — Cumberland ! Westmoreland ! (Bissett).
Lancashire ! W. and N. Yorks (zygospores from Lund's
Fell, N. Yorks) ! Cheshire (Boy). Leicestershire (Boy).
Worcestershire ! Warwickshire ! Essex ! Cambridge-
shire ! Oxfordshire ! Surrey ! Hants (Bennett).
Somerset ! Devon ! Cornwall ! Channel Islands
(Jersey) !
Wales. — General in Carnarvonshire (at over 3000
ft. on Snowdon) ! Merioneth !
Scotland. — Ross, Inverness, Aberdeen !, Forfar !,
Perth !, Stirling, Fife (Roy $ Bissett). Sutherland !
Outer Hebrides ! Orkneys ! Shetlands !
Ieeland. — -Achill Island, and near Westport, Mayo !
Derryclare Lough, Galwav ! Slieve Donard, Down (at
2000 ft.) ! Carrantuohilf, Kerry ! Cork !
Geogr. Distribution. — France. Germany. Austria
and Galicia. Bosnia. Roumania. Italy. Norway.
Sweden. Bornholm. Finland. Russian Lapland.
IV. Russia. Faeroes. Xova Zembla. Spitz! tergen.
'Greenland. United States.
G. ochthodes should be carefully compared with G. Boti'ytis
and G. tetraophthalmum, from both of which species it is very
easily distinguished by the totally different nature of its
surface-ornamentation. It is a widely distributed species in
upland districts and is not uncommon on old heaths in the
lowlands. The warts are broad, flattened elevations with a
somewhat irregularly-circular outline, and they vary con-
siderably in the extent of their development. In some indivi-
duals they are very prominent, causing the cell-margin to
appear distinctly crenate, whereas in others they are much
more flattened, the cell-margin only appearing undulate.
Var. amcebum West. (PI. XCVIII, figs. 4-6.)
C. ochthodes var. amcebum West, Alg. Engl. Lake Distr. 1892, p. 728 ;
! West & G. S. West, Alga-fl. Yorks. 19O0J p. 84; Freshw. Alg. Orkneys
and Shetlands, 1905, p. 21.
■C. ochthodes forma granulosum Liitkem. Desm. Attersees, 1893, p. 557,
t, 8, f . 9.
12 BRITISH DESMIDIACEjE.
C. ochthodes var. amosbo-granulosum Schmidle, Alg. Bern. Alp. 1894, p.
92, t. 6, f . 9.
C. speciosum Lund. var. australianum Nordst. forma Gutw. Flor. Glon.
Okolic Lwowa, 1891, p. 50, t. 1, f. 35 a; t. 2, f. 35 6. [ = C. ochthodes
var. amcebum according to Gutwinski, 1895.]
Semicells pyramidate-trapeziform, with broader
apices than in the type, margins only faintly undulate ;
Avarts very broad and flat, scarcely elevated, and sinuous
in outline ; cell-wall between the warts sparsely punc-
tate.
Length 87-00 fx ; breadth 60-07 ll ; breadth of apex
25-27 fx ; breadth of isthmus 21 /x ; thickness 40 /x.
England. — Foot of Brant Fell, Westmoreland !
Hampsfell and Hawkshead, Lancashire ! Mickle and
Cronklev Fells, N. Yorks !
Scotland. — Sutherland! Skye in Inverness ! Hoy,
Orkneys ! Near Scalloway and Bressay, Shetlands !
Ireland. — Lough Grartan, Donegal! Bog near Lough
Neagh, Londonderry !
Geogr. Distribution. — Austria and Galicia. Switzer-
land. Lapland. Spitzbergen.
This variety is about tlie same in size as the type, but the
semicells are more trapeziform, possessing broader apices.
The outline is but faintly undulate (much less undulate than
in the type), and the greatly depressed warts are very broad
towards the centre of the semicells. They are of almost in-
appreciable elevation and sinuous in outline (hence the varietal
name " amoebum ").
We sometimes find this variety and the type abundantly
in the same collection, in which case the differences stand
out most clearly. They can always be distinguished by out-
ward form alone, although the character of the cell-margin
and the sinuous " warts " are the principal features of the
variety.
Var. subcirculare Wille. (PI. XCVIII, fig. 7.)
C. ochthodes var. subcirculare Wille, Norses Kerskv. Alg, 1870, p. 26, t. 1,
f. 8; G. S. West, Alga-fl. Cambr. 1899, p. 219; West & G. S. West,
1900, p. 84 ; Wille, Algolog. Notiz. VII. 1901, p. 17.
Cells smaller than in the type, only a little longer
than broad ; semicells subsemicircular, margins uni-
formly undulate, and within the marerins with 3
COSMARIUM. 13
concentric series of flattened grannies; vertical view
oblong-elliptic, poles 6-7-undulate.
Length 48 n ; breadth 42 ^ ; breadth of isthmus
15 ju,; thickness 23 ja.
England. — Baildon and Boston Spa, W. Yorks !
Wimpole Park, Cambridgeshire !
Geogr. Distribution. — Norway.
229. Cosmarium coronatum Cooke & Wills.
(PI. XCVIII, fig. 8.)
Cosmarium coronatum Cooke & Wills in Cooke, 'Notes on Brit. Desmids,'
Grevillea, 1881, ix, p. 90 ; Wills in Midland Naturalist, 1881, iv, p. 74,
t. 5, f. 2 ; Cooke, Brit. Desm. 1887, p. 108, t. 41, f. 7 ; De Toni, Syll.
Alg. 1889, p. 1023 ; Nordst. Index Desm. 1896, p. 83.
Vrsinella coronata Kuntze, Be vis. gen. plant. 1891, p. 924.
Cells of medium size, a little broader than long,
deeply constricted, sinns narrowly linear with a slightly
dilated extremity ; semicells transversely subrect-
angular-trapeziform, angles rounded, sides upwardly
diverging, apex broad and slightly convex. Side view
of semicell depressed-globose, with a subtruncate apex.
Vertical view elliptic, ratio of axes about 1 : 1*8.
Cell-wall coarsely and somewhat distantly granulate,
granules rounded, arranged in three transverse series
(about 8 in each series) and with 15 or 16 visible at
the margin of the semicell.
Zygospore unknown.
Length 65-70 /x; breadth 75-80 ju; breadth of
isthmus 20 fx ; thickness 45 jjl.
Wales. — Capel Curig, Carnarvonshire (Cooke Sf Wills).
We have never seen this species, nor, in fact, any Cosmarium
with a granulation such as that described and figured by
Messrs. Cooke and Wills for C. coronatum.
230. Cosmarium conspersum Ralfs.
(PI. XCIX, figs. 1, 2.)
Cosmarium conspersum Balfs, Brit. Desm. 1848, p. 101, t. 16, f. 4; Arch, in
Pritch. Infus. 1861, p. 732; Eabenh. Flor. Enrop. Alg. Ill, 1868, p.
159 ; Cooke, Brit. Desm. 1887, p. 101, t. 39, f . 1 ; De Toni, Syll. Alg.
1889, p. 998 ; Borge, Chlor. Norska Finmark. 1892, p. 9 ; West, Alg.
W. Ireland, 1892, p. 152 ; Alg. Engl. Lake Distr. 1892, p. 726; Liitkem.
14 BRITISH DESMIDlACEiE.
Desm. Attersees, 1893, p. 557 ; Roy & Biss. Scott. Desm. 1894, p. 44 ;.
Schmidlc, Beitr. alp. Alg. 1895, p. 454 ; Nordst. Index Desm. 1896, p.
79 ; W. & G. S. West, Alg. S. England, 1897, p. 488; Schmidle, Lapp-
mark Siisswasseralgen, 1898, p. 35 ; W. & G. S. West, Alga-fl. Yorks.
1900, p. 88 ; ? Hirn, Desm. Finland, 1903, p. 8 ; Larsen, Freshw. Alg.
E. Greenland, 1904, p. 84.
C. anomalum Delp. Desm. subalp. 1877, p. 29, t. 9, f. 10-15 [in part].
C. conspersum a. Ralfsii Eacib. Nonn. Desm. Polon. 1885, p. 75.
Ursinella conspersa Kvmtze, Revis. gen. plant. 1891, p. 924.
Cells large, about 1-g- times as long as broad, deeply
constricted, sinus narrowly linear with a dilated
extremity ; semicells subrectangular, slightly wider at
the apex than at the base, angles slightly rounded,
sides almost straight, apex convex (in some specimens
much more than in others) ; cell- wall uniformly granu-
late, about 30 granules showing round the margin of
a semicell, granules disposed in about 9 horizontal
series and 13-15 vertical series, commonly with slight
irregularities. Side view of semicell almost circular.
Vertical view elliptic, ratio of axes about 1 : 1*6.
Chloroplasts axile, with two pyrenoids in each semicell..
Zygospore unknown.
Length 82-110 jjl; breadth (max.) 65-77 (jl; breadth
of isthmus 20-27 fx ; thickness 40—16 /x.
England. — Westmoreland (Bissett). Malham Tarn,
W. Yorks. Mickle and Great Shunnor Fells, N. Yorks !
Sutton Park, Warwickshire! (Wills). Sussex (Rolfs).
Keston Common, Kent !
Wales. — Cap el Curig (Cooke Sf Wills), Bettws-y-Coed
(Boy), and near Bethesda !, Carnarvonshire. Llyn
Coron, Anglesey ! Dolgelly, Merionethshire (Balfs).
Scotland. — Glen Tilt and Ben Lawers, Perth !
Ireland. — Clifden to Roundstone, and Creggan
Lough, Galway ! Adrigole, Cork ! Dublin and
Wricklow (Arc! i it).
Geogr. Distribution. — France. Germany. Austria.
G-alicia. Roumania. Italy. Norway. Sweden. Born-
holm. Finland. Poland. N. Russia. Iceland. Nova
Zembla. Greenland. United States. Brazil. Paraguay.
Typical C. conspersum is a very uncommon Desmid. We
have seen no specimens exactly similar to the figure given by
RalfSj the apices being generally more convex and the con-
C0SMAR1UM. 15
striction not quite so deep. The granules are disposed in
fairly regular transverse and vertical series, and the cell-wall
between the granules is quite smooth. The vertical view is
elliptical with no flattening of the sides.
The var. latum (= C. latum Breb.) and other forms with
more rounded semicells are much more frequent than the
somewhat angular Desmid described by Bali's, although for
the most part these forms have been recorded under the name
" C. cons per sum."
Borge (' Chlor. Norsk a Finmark.' 1892, p. 9) has recorded
a "forma minor" of this species from the extreme north of
Norway with a length of only 52/^ and a breadth of 44 fx.
Var. latum (Breb.) nob. (PI. XCIX, figs. 5, G.)
Cosmarium latum Breb. Liste Desm. 1856, p. 128, t. 1, f. 10; Rabenh.
Plor. Europ. Alg. Ill, 1868, p. 158 ; ? Cooke, Brit. Desm. 1887, p. 101,
t. 41, f. 8 ; De Toni, Syll. Alg. 1889, p. 999 ; West, Alg. N. Yorks, 1889,
p. 292 ; Roy & Biss. Scott. Desm. 1894, p. 105, t. 2, £. 10 ; Nordst. Index
Desm. 1896, p. 156 ; W. & G. S. West, Alg. S. England, 1897, p. 4S8 ;
Some Desm. IT. S. 1898, p. 306 ; Alga-fl. Yorks. 1900, p. 88 ; Borg.
Freshw. Alg. Faeroes, 1901, p. 227 ; Borge, Siisswasseralgen Siid.
Patagon. 1901, p. 21 ; W. & G. S. West, Alg. N. Ireland, 1902, p. :!7 ;
Borge, Beitriige Alg. Schweden, 1906, p. 30 ; W. & G. S. West, Freshw.
Alg. Burma, 1907, p. 206.
C. anomalum Delp. Desm. snbalp. 1877, p. 29, t. 9, f. 10-12, and 15
[figures poor and inaccurate].
Ursinella lata Kuntze, Revis. gen. plant. 1891, p. 925.
Cells proportionately wider; semicells generally with
a conspicuous upward dilation, so that the apical part
is distinctly wider than the basal part, apex usually
(but not always) more convex ; grannies about equal
in size and number to those of typical G. conspersum,
arranged in vertical and indistinct oblique series.
Length 88-107/x; breadth 76-88^; breadth of
isthmus 27*5-34 /x; thickness 40-50 /x.
England. — Near Bowness, "Westmoreland ! (Bissett).
Mickle and Great Shunnor Fells, Pilmoor, and Carlton
Bank, N. Yorks ! Delamere, Cheshire (Boy). Brent
Reservoir, Middlesex !
Wales. — Capel Curig !, Llyn Ogwen !, and Glyder
Fawr (Boy), Carnarvonshire.
Scotland. — Sutherland !, Ross, Inverness, Aberdeen,
Kincardine, Forfar, Perth!, Stirling (Boy Sf Bissett).
Lewis and Harris, Outer Hebrides !
16 BRITISH DESM1DIACE.E.
Ireland. — Brrigal, Donegal ! Slieve Commedagh,
Down ! Frequent in Mayo and Gahvay !
Geogr. Distribution. — France. Germany. Italy.
Roumania. Norway. Sweden. Denmark. Faeroes.
Greenland. Central China (a form). Celebes. United
States. Patagonia.
Brebisson's original figure of Cosmarium latum does
justice neither to the angularity of this Desmid nor to the
disposition of its granules. The figure given by Messrs. Roy
and Bissett in 1894 was the first one to portray its salient
features. We find it impossible, however, to separate C.
latum as a species from C. conspersum. The differences are
too slight, and many intermediate conditions exist. The var.
latum is much more generally distributed than typical C.
conspersum, and differs chiefly in its slightly greater breadth
and more convex apices. The granulation of the two forms
is very similar, and in both cases the cell-wall between the
granules is smooth. The ratio of the breadth to the length
in C. conspersum is 1 : P35, whereas in the var. latum the
average ratio is 1 : IT 8.
Note :— Cosmarium latum Breb. var. minor Rov & Biss.
*j
(Scott. Desm. 1894, p. 105, t. 2, f. 11 [= G. similatum Roy
& Biss. MS.] ; Gutw. Wykaz. Glonow Wadow.-Makow. 1897,
p. 148 ; W. & G-. S. West, Alga-fl. Yorks. 1900, p. 88 ■ Wittr.,
Nordst. et Lagerh. Alg. Exsic. 1903, no. 1481 ; fasc. 35, p. 13).
This Desmid was obtained by Messrs. Roy & Bissett from
above Loch Etchachan on Ben Macdhui in Aberdeenshire,
and from Canlochan in Forfar, and we have obtained it from
Boston Spa and Ogden Clough in West Yorkshire. It was
described as " very like the type [C. latum] in form, but
smaller and more closely granulated. Length 60-67 /u ;
breadth 48-55 n ; isthmus 20-22 fi." We give a copy of their
figure on PI. XCIX, fig. 7, but Ave consider that this Desmid
is not correctly placed with the forms of Cosmarium conspersum
Ralfs. The semicells are too rounded, and the granulation is
both finer and denser. Its dimensions and its granulation
are those of Cosmarium Logiense Bissett [vide Vol. Ill, PI.
LXXX, figs. 1 and 2], with which species it should more
rightly be placed. It might be called C. Logiesse Biss. forma
expansa nob.
Var. rotundatum Wittr. (PI. XCIX, fig. 3.)
C. conspersmnKalfs var. rotunda/ urn Wittr. Skandinav. Desm. 1869, p. 13,
i. 4 ; Wille, Ferskv. Alg. Nov. Semlj. 1879, p. 35 ; De Toni, Syll. Alg.
COSMARIUM. ] 7
1889, p. 998; Borge, Chlor. Norska Fimnark. 1892, p. 9; Liitkem.
Desxn. Attersees, 1893, p. 558; Borg. Ferskv. alg. Ostgronl. 1894, p.
13; Gutw. Flor. Glon. Okolic Tarnapola, 1894, p. 95; Roy & Biss.
Scott. Desm. 1894, p. 44; Liitkem. Desm. Millstiittersees, 1900, p. N;
W. & G. S. West, Alga-fl. Yorks. 1900, p. 88; Borge, Beitriige Alg.
Schweden, 1906, p. 30.
C. conspersum b. rotundatum forma scandinavica Racib. Nonn. Desm.
Polon. 1885, p. 75 ; Gutw. Flor. Glon. Okolic Lwowa, 1891, p. 53.
Relative length and breadth similar to that of var.
latum ; lateral margins of semicells snbparallel; granules
typical, disposed in transverse and vertical series.
Length 86-110 fx ; breadth 66-80 [x ; breadth of
isthmus 25-33 /x ; thickness 37-55 \x.
England. — Skipwith Common, E. Yorks !
Wales. — Glyder Fawr, Carnarvonshire (Roy).
Scotland. — Ross, Inverness, Aberdeen, Kincardine,
Stirling (Boy <$• Bissett).
Geogr. Distribution. — Germany. Austria and Galicia.
Roumania. Norway. Sweden. Nova Zembla. India.
This variety as we know it is in no way inferior in size to
typical C. conspersum, but other observers have recorded much
smaller forms. Raciborski records both a "forma inter-
media" (length 1Q-I2.fi; breadth 55-61 fj) and a "forma
minor" (length 54-55^; breadth 43 /u) from Poland; and
Boldt describes and figures a rather small form from Green-
land in which the semicells possess upwardly diverging sides
(length 12-82 u ; breadth 52*2-64-8 n). It may be, however,
that these forms would be better referred to the var. latum.
Var. subrotundatum West. (PL XCIX, fig. 4.)
C. conspersum Ralfs var. subrotundatum West, Alg. W. Ireland, 1892, p.
152, t. 21, f. 7.
Superior angles of semicells greatly rounded ;
granules rather more numerous, disposed in about 12
horizontal and 21 vertical series.
Length 84 fx ; breadth 82 jx ; breadth of isthmus 30 /x ;
thickness 42 /x.
Ireland. — Cromagloun, Kerry !
It might be mentioned here that the most dilated and
rounded of all the Cosmaria of this type is a North American
species with greatly inflated semicells, which has been des-
cribed as Cosmarinm Johnsonii W. & G. S. West (' Some
Desm. U. S.' 1898, p. 306, t. 17, f. 4).
VOL. IV. 2
18 BRITISH DESMIDIACEiE.
231. Cosmarium margaritatum (Lund.) Roy & Biss.
(PL XCIX, figs. 8, 10.)
Cosmarium latum Breb. var. margaritatum Lund. Desm. Suec. 1871, p.
26 ; Nordst. Norges Desm. 1873, p. 12 ; Boldt, Desmid. Gronland, 1888,
p. 26 ; De Toni, Syll. Alg. 1889, p. 999.
C. margaritatum (Lund.) Boy & Biss. Jap. Desm. 1886, p. 194; West,
Freshw. Alg. Maine II, 1891, t. 315, f . 16 ; Roy & Biss. Scott. Desm.
1894; p. 167, t. 2, f. 12 ; Johnson, Rare Desm. U. S. II, 1895, p. 292,
t. 240, f. 32 ; Nordst. Index Desm. 1896, p. 165 ; W. & G. S. West,
Desm. Singapore, 1897, p. 165 ; Alg. S. England, 1897, p. 488 ; Sehmidle,
Lappmark Siisswasseralgen, 1898, p. 35 ; G. S. West, Alga-fl. Cambr.
1899, p. 217 ; W. & G. S. West, Alg. N. Ireland, 1902, p. 37 ; Freshw.
Alg. Cevlon, 1902, p. 169 ; Freshw. Alg. Orkneys and Shetlands, 1905,
p. 21 ; G. S. West, Alg. Third Tanganyika Expedit. 1907, p. 122.
Cells fairly large, about I3- times as long as broad,
deeply constricted, sinus narrowly linear with a dilated
extremity ; semicells subrectangular (sometimes ellip-
soid-subrectangular), apex very slightly convex, sides
slightly convex, never upwardly divergent, basal angles
rounded, superior angles broadly rounded ; cell-wall
uniformly granulate, from 28 to 32 granules showing
round the margin of a semicell ; granules solid, dis-
posed in oblique decussating series, about 12 series in
each direction, and also in indistinct vertical series,
cell -wall between the granules punctate, the punctula-
tions arranged in hexagons around each granule. Side
view of semicell subcircular. Vertical view oblono--
elliptic with convex sides. Chloroplasts axile, two
pyrenoids in each semicell.
Zygospore unknown.
Length 66-105 /a; breadth 56-82 jx ; breadth of
isthmus 19-31 /x ; thickness 40-48 /x.
England. — Austwick Moss, W. Yorks ! Chippenham
Fen, Cambridge ! Frensham Great Pond and Thursley
Common (very abundant) , Surrey ! New Forest, Hants !
Wales. — Llyn-y-cwm-ffynon and Capel Curig, Car-
narvonshire ! Plankton of several of Welsh Lakes !
Scotland. — Pool near View Rock, Strath pelf er,
Ross; Slewdrum, Aboyne, Cambus O'May, Dalbagie,
Glen Clunie, and Castleton, Aberdeen (Boy Sf Bissett).
Plankton of Loch Doon, Ayr ! Rhiconich, Sutherland !
COSMARIUM. 19
Harris and Lewis, Outer Hebrides ! Orkneys ! Shet-
land s !
Ireland. — Lough Anna, Donegal ! Dublin and
Wicklow {Archer) . Lough Derryclare, and near Round-
stone, Galway ! Foxford, Mayo !
Geogr. Distribution. — France (f. minor). Germany.
Galicia in Austria (f. minor). Norway. Sweden.
Greenland. Ceylon. Singapore. W. and Central
Africa. United States. W.Indies. Brazil (f. minor).
It is a doubtful question whether C. margaritatum should
be separated from C. conspersum as a species, or whether it
should be placed as a variety in close association with the
var. latum. Tts complete separation is, however, a con-
venience, as it is the only British Cosmarium of this type with
well-marked punctulations between the granules. The granu-
lation is constant in character, but the granules exhibit con-
siderable variation in size in different individuals. The basal
portion of the semicell is generally distinctly wider than the
apical part, owing to the greater rounding of the apical
ang-les. The slight differences in the outward form of the
semicells, and the presence of regulaiTy arranged punctula-
tions between the granules, are the only characters which
separate C. margaritatum from C. conspersum var. latum.
The smaller forms of this species are known as : —
Forma minor (Boldt) W. & G. S. West, Welw. Afric.
Freshw. Alg. 1897, p. 121 ; C. latum var. margaritatum forma
minor Boldt, Desmid. Gronland, 1888, p. 26. Length 44-62 li ;
breadth 38-48 fx ; breadth of isthmus 12'5-13'5/z; thickness
25-30^. (PI. XCTX, fig. 9.)
The largest forms we have observed occurred in abundance
at Chippenham Fen, Cambridgeshire, and reached a length of
105 ft. This is slightly larger than the Desmid described as
" G. margaritatum var. major " by Schmidle (' Alg. Carolin.'
1901, p. 347, t. 12, f. 5), but that^seems scarcely to belong to
C. margaritatum on account of its different proportions and
its smooth apices.
Forma subrotundata nob. (PL C, fig. 1.)
Semicells relatively wider and more rounded, almost
reniform in outline ; granules hollow (excavated from
the interior).
Length 92 ix ; breadth 80 ix ; breadth of isthmus 31 fi.
20 BRITISH DESM1DIACE.L.
Walks. — In the Plankton of Llynau Dywaunedd,
Carnarvonshire !
Scotland. — Rhiconich, Sutherland !
In this form the semicells are much more rounded than
usual, and the hollow granules are similar to those of C. suh-
latum Nordst. and C. Pardalis Colin.
232. Cosmarium Quadrum Lund.
(PI. C, figs. 3-6.)
Cosmarium Quadrum Lund. Desm. Suec. 1871, p. 25, t. 2, f. 11 ; Boldt,
Siber. Chlorophy. 1885, p. 107 ; Cooke, Brit. Desm. 1887, p. 102, t. 42,
f. 1 ; Boldt, Desmid. Ghronland, 1888, p. 26 ; De Toni, Syll. Alg. 1889,
p. 985 ; Anderss. Sverig. Chlor. 1890, p. 14 ; West, Alg. Engl. Lake
Distr. 1892, p. 726 ; Roy & Biss. Scott. Desm. 1894, p. 173 ; Nordst.
Index Desm. 1896, p. 218 ; Schmidle, Lappmark Siisswasseralgen, 1898,.
p. 34; ? Ost-Afrika Desmid. 1898, p. 26; Borge, Trop. u. subtrop.
Sussw.-Chlor. 1899, p. 20 ; W. & G. S. West, Alga-fl. Yorks. 1900, p. 88 ;
Freshw. Alg. Ceylon, 1902, p. 170 [forma] ; Borge, Beitrage Alg;.
Schweden, 1906, p. 30 ; G-. S. West, Alg. Third Tanganyika Expedit.
1907, p. 122 [forma].
C. conspersum Ralfs c. Quadrum Bacib. Nonn. Desm. Polon. 18S5, p. 75.
Ursinella Quadrum Kvmtze, Bevis. gen. plant. 1891, p. 925.
Cells of medium size, in general outline quadrate^
about as long as broad or slightly longer, deeply con-
stricted, sinus narrowly linear, with a slightly dilated
extremity ; semicells subrectangular, basal angles
rounded, superior angles broadly rounded, sides slightly
convex (sometimes almost straight), apex generallv
very slightly retuse, sometimes straight. Side view of
semicell subcircular. Vertical view oblong-elliptic,
with straight parallel sides. Cell-wall densely granu-
late ; granules solid, arranged in decussating oblique
series and in somewhat less distinct vertical series, from
34 to 37 showing at the margin of a semicell, and
slightly reduced in size in the middle of the apex.
Chloroplasts axile, with two pyrenoids in each semicell.
Zygospore unknown.
Length 60-83 [x ; breadth 54-74 /x ; breadth of
isthmus 18-29 /a; thickness 27-40 /u.
England. — Brant Fell and near Bowness, Westmore-
land ! Cullingworth, TV". Yorks !
Wales. — Capel Curig, Carnarvonshire !
Scotland. — Loch Inver, Sutherland; Pittellachie
COSMAEIUM. 21
and Tomacliar in Cromar, Aberdeen ; near source of
the Barvie, Kincardine (Boy Sf Bissett). Ben Lawers,
Perth ! Argyll !
Ireland. — Dublin and Wicklow (Archer).
Geogr. Distribution. — France. Germany. Galicia
in Austria. Norway. Sweden. Bornholm. Finland.
Poland. X. Russia. India. Ceylon (var.). Sumatra.
Samoa (var.). Central Africa. United States.
C. Quadrum is the rarest of the C. coiispersum-grouip in the
British Islands, although one of the most frequent tropical
species. It is distinguished from all forms of C. conspersum
and C. margaritatum by the rectangular semicells with a
broad flattened apex which is slightly refuse in the middle.
The vertical view is also oblong with parallel sides, and the
granules are invariably reduced in size in the median portion
•of the apex of each semicell. The cell-wall between the
granules is quite smooth.
The smaller forms of this species are known as : —
Var. minds Nordst. Norges Desm. 1873, p. 11; De Toni,
Syll. Alg. 1889, p. 985; Schmid-le, Beitr. Algenfl. Schwarz-
■wald. u. liheineb. 1893, p. 101; Borg. Ferskv. Alg. Ostrgronl.
1894, p. 14; etc. Length 38-50//; breadth 38-48 /i ; thick-
ness 18-23/1.
C. Pseudobroomei Wolle var. madagascariense W. & G. S.
West, Alg. Madag. 1895, p. 03, t. 7, f. 34 is very near to
■G. Quadrum var. minus. It differs from the latter, however,
in its convex apices and in the reduction of the granules near
the centre of the semicells. It mio-fit best be regarded as a
form of C. Quadrum under the name " C. Quadrum var.
MADAGASCARIENSE nob."
Two other Desmids require mentioning in reference to
C. Quadrum. The first one is G. sublatum Nordst. (c Freshw.
Alg. N. Zeal. & Austral/ 1888, p. 45, t. 5, f. 1-4). We give
& figure of a specimen from Australia (Victoria) for compari-
son with the figures of G. Quadrum. It differs only in two
points, in the hollow granules and in the intergranular punc-
tulations. These are scarcely specific differences, as even a
form of G. margaritatum is known with hollow granules. It
would be better placed as C. Quadrum var. sublatum (PI. C,
fig. 2).
The second one is C. Pardalis Colin, which is more especially
a tropical species. It is more angular than G. Quadrum,
with larger granules and intergranular punctulatioiis. It is
22 BRITISH DESMIDIACE.E.
interesting as being the only species of the C. conspersum-
group of which the zygospore is known. This spore is smooth
and globular (vide West, ' Freshw. Alg. Maine ' II, 1891,
p. 355, t. 315, f. 10).
233. Cosmarium Pseudobroomei Wolle.
(PL C, figs. 7, 8; PL CIII, fig. 7.)
Cosmarium Broomei Ralfs, Brit. Desm. 1848 [in part], t. 33, f. 7.
C. Pseudobroomei Wolle in Bull. Torr. Kot. Club, 1884, p. 16, t. 44. f. 36,
37 ; Desm. U. S. 1884, p. 86, t. 51, f. 36, 37 ; Turner, Freshw. Alg. E.
India, 1893, p. 66, t. 9, f. 41 ; Nordst. Index Desm. 1896, p. 208 ; Borge,
Austral. Siisswasserchlor. 1896, p. 20, t. 3, f. 34 ; Borge, Trop. u. sub-
trop. Sussw.-Chlor. 1899, p. 20, t. 1, f. 22 ; Liitkem. Desm. Central
China, 1900, p. 119 ; W. & G. S. West, Freshw. Alg. Ceylon, 1902, p. 170;
Gutw. Alg. Ins. Java, 1902, p. 601 ; G. S. West, Alg. Third Tanganyika
Expedit. 1907, p. 123.
Cells small, about as long as broad, very deeply
constricted, sinus narrowly linear with a slightly
dilated extremity ; semicells oblong-rectangular with
the angles slightly rounded, sides very slightly convex,
apex straight or very slightly convex. Side view of
semicell subcircular. Vertical view oblong, with sub-
parallel sides and broadly rounded extremities. Cell-
wall densely granulate ; granules small and solid,
arranged in decussating oblique series and in somewhat
less distinct vertical series (as in G. Quadrum), from 23
to 32 showing at the margin of a semicell. Chloro-
plasts axile, with two pyrenoids in each semicell.
Zygospore subglobose and smooth.
Length 33-38 fx ; breadth 29-36 /x ; breadth of
isthmus 85-12 [x ; thickness 1 6-17*5 p.
Wales. — Capel Curig and Llyn-y-cwm-ffynon, Car-
narvonshire !
Geoijr. Distribution. — Galicia in Austria. Central
China. India. Cevlon. Java. Madagascar (var.).
E. Africa (var.). Central Africa. United States. Brazil.
There is little doubt that the zygospore figured by Knlfs on
his supplementary plate 33 under the name of "C. Broomei''
is that of G. Pseudobroomei. The latter is distinguished from
G. Broomei by the entire absence of a median inflation in the
vertical view, and by its somewhat coarser granulation.
C. Pseudobroomei approaches very closely the smaller forms
COSMABIUM. 23
of C. Quadrum var. minus. Borge records Australian speci-
mens up to a length and breadth of 45*5 fx.
Another closely allied species is G. creperum W. & Gr. S.
West (' Alg. Madag.' 1895, p. 63, t. 7, f. 11), which differs in
the open sinus, the more rounded sides of the semi cells, and
the more distantly arranged granules.
The granulation of G. Pseudobruomei appears to be variable
in density, some specimens exhibiting many more granules
per semicell than others.
Var. convexum W. & G. S. West, (PL C, fig. 9.)
C. Pseudobroomei var. convexum W. & G- S. West, Freshw. Algae Orkneys
and Shetlands, 1905, p. 21, t. 1, f. 22.
Lateral margins of semicells convex and with the
angles more rounded ; grannies as in the type but
disposed most evidently in vertical series.
Length 46 /x; breadth 375 [x; breadth of isthmus
12*5 jx ; thickness 24 /x.
Scotland. — Near Lerwick, Shetlands !
This variety is slightly larger than any other known form
of the species, and is proportionately less wide.
234. Cosmarium Subbroomei Sclimidle.
(PI. C, fig. 10.)
Cosmarium Subbroomei Sclimidle, Beitr. Algenfl. Sclnvarzwald. u. Rheineb.
1893, p. 104, t. 5, f. 22-24.
Cells small, about as long as broad, very deeply
constricted, sinus narrowly linear with a very slightly
dilated apex ; semicells oblong-rectangular with slightly
rounded angles, sides and apex very slightly convex.
Cell-wall finely granulate; granules about the size of
those of G. punctulatum, disposed in 10-12 subvertical
series, 25-27 showing at the margin of a semicell,
with a few indistinctly arranged granules just above
the isthmus in the centre of the semicell. Side view
of semicell subcircular. Vertical view rather narrowly
elliptical, with three prominent papilla-like granules
at the middle on each side. Chloroplasts axile, with
two pyrenoids in each semicell.
Zygospore unknown.
24 BEIT1SH DESMIDIACEiE.
Length 40 fi ; breacltli 36 /x.
( reogr. Distribution . — Germany.
The illustration on PI. C (fig-. 10) is copied from one of
Schmidle's original figures. We have seen nothing exactly
like it from the British Islands, although we have met with a
Gosmarium from Surrey which must be regarded as a form
of it.
Forma. (PI. C, fig. 11).
Semicells slightly trapeziform, granules somewhat more
numerous; in the vertical view with a very slight granulated
protuberance at the middle on each side. Length 42 u ;
breadth 38 m; breadth of isthmus 12//; thickness 23^.
England. — In a mill-pond E. of Chapel Wood in S.E.
Surrey !
235. Cosmarium Broomei Thwaites.
(PI. C, fig. 12.)
Cosmarium Broomei Thwaites in Balis' Brit. Desni. 1848, p. 103, t. 16,
f. 6 ; Arch, in Pritch. Infus. 1861, p. 734, t. 1, f. 7 ; Eabenh. Flor!
Europ. Alg. Ill, 1868, p. 171 ; Lund. Desm. Suec. 1871, p. 29 ; Nordst.
Desm. Ital. 1876, p. 41 ; Kirchn. Alg. Schles. 1878, p. 154 ; ? Wolle
Desm. U. S. 1884, p. 86, t. 17, f . 6, 7 ; Cooke, Brit. Desm. 1887, p. 109,
t. 40, f . 1 ; Hansg. Prodr. Algenfl. Bohm. 1888, p. 251 ; De Toni, Syll.
Alg. 1889, p. 1026 ; West, Alg. N. Yorks. 1889, p. 292 ; Alg. N. Wales,
1890, p. 290 ; Alg. W. Ireland, 1892, p. 156 ; Alg. Engl.^Lake Distr.
1892, p. 728 ; Roy & Biss. Scott. Desm. 1894, p. 44 ; Nordst. Index Desm.
1896, p. 70; W. & G. S. West, Alg. S. England, 1897, p. 490; Atoa-fl.
Yorks. 1900, p. 88. &
Ursinella Broomei Kuntze, Revis. gen. plant. 1891, p. 924.
Cells rather small, almost quadrate, about as long
as broad, very deeply constricted, sinus narrowly
linear with a slightly dilated extremity; semicells
oblong-rectangular or rectangular-trapeziform, with the
angles slightly rounded, sides convex and sometimes
slightly convergent upwards, apex straight or faintly
retuse. Side view of semicell subcircular-depressed.
Vertical view narrowly elliptic, with a conspicuous
rounded inflation at the middle on each side. Cell-
wall densely and finely granulate, granules cmite small
and disposed in close vertical series, about 30-34
showing at the margin of a semicell. Chloroplasts
axile, with two pyrenoids in each semicell.
Zygospore unknown.
COSMAEIIDI. 25
Length 42-52 p. ; breadth 32-45 p ; breadth of
isthmus 12-16 /x; thickness 21-30 /u.
England. — Crummock Water, Cumberland ! LoupIi-
rigg, Westmoreland ! Risley Bog, Lancashire ! Culling-
worth, Wigton Moor, Baildon, Adel Bog, and Moughton
Fell, W. Yorks ! Pilmoor, Mickle and Great Shunnor
Fells, N. Yorks ! Riccall Common, E. Yorks ! Glou-
cester (Ralfs). Near Chapel Wood, Surrey ! Sussex !
Hants (Bennett). Cornwall (Marquand).
Wales. — Bethesda !, Capel Curig !, Snowdon!, and
(xlyder Fawr (Roy), Carnarvonshire. Dolgelly, Meri-
oneth !
Scotland. — Near Brin, Inverness; near Alford,
Aberdeen; Strachan, Kincardine (Roy Sf Bissett).
Ireland. — Near Westport, Mayo ! Near Recess,
Galway !
Geogr. Distribution. — France. Germany. Galicia in
Austria. Italy. Norway. Sweden. Denmark. S.
Russia. United States. Brazil.
C. Broumei differs from all allied species in the possession
of a large protuberance in the middle of each semicell. The
granulation is also characteristic, being very tine, and com-
parable to that of C. biretum. It is a I'are Desmid and we
have only met with it as solitary examples.
The zygospore of this species is as yet unknown, as that
figured by Ralfs ('Brit. Desm.' 1848, t. 33, f. 7) is most
probably that of C. Pseudobroomei. It is not unlikely, how-
ever, that the zygospore of C. Broomei will be found to lie
smooth.
The Cosmarium figured by Wolle ('Desm. IT. S.J 1884,
t. 17, f. 8, 9) as a " smaller variety and zygospore" of ('.
Broomei is now known as another species — G. spinosporum
Lao'erh.
ov
23 G. Cosmarium biretum Breb.
(PI. CI, figs. 1-8.)
Cosmarium biretum Breb. in Ealfs' Brit. Desm. 1848, p. 102, t, 10, f. 5;
Arch, in Pritch. Infus. 1861, p. 733 ; Rabenh. Flor. Europ. Algar. Ill,
1868, p. 171 ; Lnnd. Desm. Smec. 1871, p. 30 ; Nordst. Desm. Arctoa',
1875, p. 26 ; Desm. Deal. 1876, p. 40; Kirchn. Alg. Schles. 1878, p. 154 ;
Wolle, Desm. U. S. 1884, p. 86, t. 17, f . 1, 2 [figures bad] ; Cooke, Brit .
Desm. 1887, p. 108, t. 39, f. 5 [figures bad] ; Hansg. Prodr. Algenfl.
Bohm. 1S88, p. 202, 251 ; Hoff in Nordst, Bornh. Desm. 1888, p. 195 ;
26 BEIT1SH DESMIDIACEiE.
Nordst. Freshw. Alg. N. Zeal. 1888, p. 78 ; De Toni, Syll. Alg. 1889, p.
1018 ; ftacib. Desm. Nowe, 1889, p. 92 ; West, Alg. N. Wales, 1890, p.
289 ; Heimerl, Desm. alp. 1891, p. 595 ; Eoy & Biss. Scott. Desm. 1894,
p. 43 ; Nordst. Index Desmid. 1S96, p. 62 ; W. & G. S. West, Alg. S.
England, 1897, p. 490; G. S. West, Variation Desm. 1899, p. 389, t. 10,
f. 22-28 ; W. & G. S. West, Alga-fl. Yorks. 1900, p. 88 ; Freshw. Alg.
Ceylon, 1902, p. 169 ; Larsen, Freshw. Alg. E. Greenland, 1904, p. 83.
C. quadrangulatum Hantzsch in Eabenh. Alg. Sachs. 1860, No. 969 ;
Kabenh. Flor. Europ. Alg. Ill, 1868, p. 170; De Toni, Syll. Alg. 1889,
p. 1052.
? C. anomalum Delp. Desm. subalp. 1877, p. 29, t. 9, f. 14 [not 1. 10-12, 15],
C. biretum var. intermedium Wille, Ferskv. Alg. Nov. Semlj. 1879, p. 35,
t. 12, f. 15.
C. biretum forma grcenlandica Boldt, Desmid. Gronland, 1888, p. 25, t. 2,
f. 26.
C. biretum forma subconspersa Boldt, 1. c. p. 25 ; Nordst. in Wittr. &
Nordst, Alg. Exsic. 1896, no. 1266 ; 1903, fasc. 35, p. 13.
Ursinella bireta Kuntze, Revis. gen. plant, 1891, p. 924.
U. quadrangulata Kuntze, 1. c. p. 925.
Cells rather under medium size, about as long as
broad, very deeply constricted, sinus narrowly linear
with a slightly dilated extremity ; semicells some-
what variable in outline, commonly subrectangular-
trapeziform, with the sides straight or slightly convex
and upwardly diverging, basal angles slightly rounded,
apical angles rounded (sometimes obliquely truncate or
even slightly produced), apex usually convex (some-
times truncate in the middle). Side view of semicell
subcircular or ovate. Vertical view elliptic, with a
protuberance of variable magnitude (sometimes scarcely
evident, at other times large) at the middle on each
side. Cell- wall densely granulate ; granules small,
closely disposed in vertical series, or more frequently
more or less irregularly arranged, from 40 to 54 showing'
at the margin of a semicell. Chloroplasts axile, with
two prominent pyrenoids in each semicell.
Zygospore globose and smooth.
Length 54-74 /x ; breadth 50-06 [x ; breadth of
isthmus 19-24 /x; thickness 35-42 fx.
A smaller form, which gradually merges into the above, is
known ;is: —
Var. minis Hansg. Prodr. Algenfl. Bohm. 1888, p. 251;.
C. biretum forma minor Teodoresco, Mater, nor. alg. Rouman.
1907, p. 181.
Length 38-52 /i ; breadth 35-52 fi; breadth of isthmus 13—
19/*; thickness 23 /u j diam. zygosp. 39-45 p.
COSMABIUM. 27
As it is impossible to draw an arbitrary line between the
larger and smaller forms, they have not been discriminated in
the following localities : —
England. — Cullingworth and Roundhay Park, W.
Yorks ! The Washes, Sutton, Cambridgeshire !
Sutton Park, Warwickshire (Wills) ! Middlesex
(pure gathering from Brent Reservoir) ! Surrey !
Sussex (Half's). Wilts ! Xear St. Just, Cornwall
(abundant) !
Wales. — Dolgelly, Merioneth !
Scotland. — Bridge of Don, Aberdeen ; Garrol,
Kincardine (Roy Sf Bissett).
Ireland. — Lower Lake of Killarney, Kerry ! Dublin
and Wicklow (Archer).
Geoqr. Distribution.- — France. Germany. Galicia in
Austria. Hungary. Italy. Roumania. Sweden.
Bornholm. S. Russia. Nova Zembla. Spitzbergen.
Greenland. Ceylon. New Zealand. Liiited States.
C. biretum is by no means frequent, being found principally
in the marshes and ditches of low-lying districts. It often
occurs in great abundance among various species of Pota-
mogeton, and may sometimes be obtained almost pure in the
large drains of the east of England. When occurring in
great quantity G. hi return generally exhibits many variations
in form. The divergence of the lateral margins varies very
much (consult figs. 2, 6, and 7 on PI. CI), with the result that
the semicells of some forms possess a much broader apex than
those of others. The conformation of the apex is also markedly
different in different individuals. In some it is straight or
but slightly convex, and may even be retuse in the middle,
whereas in others it is strikingly elevated, being very convex
and often truncate in the median part (PI. CI, figs. 4 and 7).
Such differences may, however, be found in the semicells of
the same individual.
The prutuberance on each side of the vertical view is also
a character which varies greatly. Sometimes it is very large,
and all specimens show some signs of it, although in certain
individuals it is scarcely appreciable.
The granulation of C. biretum is one of its most charac-
teristic features.
The three described forms — var. intermedium Wide, forma
grmnlandica Boldt, and forma subconspersa Boldt — do not
28 BRITISH DESMID1ACE.E.
possess any characters sufficiently definite to recognize tliem
as distinct types. There is, however, a type of this species
(var. trigibberum) which possesses characters by which it can
always be identified, and which must, therefore, be regarded
as a distinct variety.
Brebisson described a " forma triquetra" of this species.
(Consult Breb. ' Liste Desm/ 1856, p. 130, t. 1, f. 9; Rabenh.
'Flor. Eur. Alg.' Ill, 1868, p. 171; Cooke, 'Brit, Desm/
1887, p. 109; etc.) The cells in vertical view are triangular
with rounded angles, and there is a small inflation in the
middle of each concave side. Breadth 56—59 fi. (PI. CI,
fig. 9.) This form has ouly been observed in France.
Var. trigibberum Nordst. (PI. CI, figs. 10-15.)
C. biretum Breb. subsp. trigibberum Nordst. Desm. Arctoae, 1875, p. 26,
t. 7, f. 19 [inclus. Q. biretum forma supernumeraries Nordst. 1. c. t. 7,
f. 18] ; Joshua in Journ. Bot. xxi, 1883, p. 291 : Be Toni, Syll. Alg.
1889, p. 1018 ; G. S. West, Variation Desm. 1899, p. 390, t. 10, f. 29-34 ;
W. & G. S. West, Alga-fl. Yorks. 1900, p. 88.
Cells usually larger than in the type ; semicells of
somewhat variable form, often more rounded ; vertical
view showing three small protuberances along each side.
Length 43-100/*; breadth 38-82 /a ; breadth of
isthmus 12-33^; thickness 32-48 /a.
England. — Rounclhay Park, W. Yorks ! The Washes,
Sutton, Cambridgeshire ! Sutton Park, Warwickshire !
Near Cirencester, Gloucestershire {.Joshua).
Scotland. — Keithick, near Coupar- Angus, Perth
{Boy Sf Bissett).
Geogr. Distribution. — Spitzbergen.
The distinguishing feature of this variety is the possession
of three protuberances on each side in the vertical view, a
central one and one close to each end. Considerable range
of variation is shown in the outline, but we find the cells of
var. trigibberum to be more rounded in general contour than
those of typical C. biretum, and rarely to possess semicells
with divergent lateral margins. The three protuberances on
each side of the vertical view may be slight and more or less
of equal size (PI. CI, figs. 10 6 and 13 b), or the central one
may be, much larger than the other two, the latter varying
in their relative proximity to the ends (PI. CI, figs. 116
and 12 b).
The granulation is precisely like that of the type.
COSMARIUM. 29
237. Cosmarium amoenum Breb.
: (Pi. on, figs. 1-4 ; pi. cm, fig. 9.)
Cosmarium amoenum Breb. in Ralfs' Brit. Desm. 1848, p. 102, t. 17, f. 3 ;
Arch, in Pritch. Infus. 1861, p. 733 ; Rabenh. Flor. Europ. Ale. Ill,
1868, p. 159; Limd. Desm. Suec. 1871, p. 46; Kirehn. Alg. Schles.'
1878, p. 152 ; Wolle, Desm. U. S. 1884, p. 78, t. 14, f. 5, 6 [figures very
poor] ; Cooke, Brit. Desm. 1887, p. 110, t. 40, f.2 [figures poor] ; Boldt,
Desmid. Gronland, 1888, p. 29 ; De Toni, Syll. Alg. 1889, p. 988 ; Borg.
Desm. Brasil. 1890, p. 37; Anderss. Sverig. Chlor. 1890, p. 14; West,
Alg. N. Wales, 1890, p. 290 ; Alg. W. Ireland, 1892, p. 156 ; Alg. Engl.
Lake Distr. 1892; p. 728; Lutkem. Desm. Attersees, 1893, p. 558; Roy
& Biss. Scott. Desm. 1894, p. 41 ; Nordst. Index Desm. 1896, p. 43 •
W. & G. S. West, Alg. S. England, 1897, p. 488 ; Schmidle, Lappmark
Susswasseralgen, 1898, p. 35 ; W. & G. S. West, Alga-fl. Yorks. 1900,
p. 88 ; Lutkem. Desm. Millstiittersees, 1900, p. 7 ; W. & G. S. West, Alg.
N. Ireland, 1902, p. 38 ; Borge, Beitrage Alg. Schweden, 1906, p. 29.
Ursinella amcena Kuntze, Revis. gen. plant. 1891, p. 924.
Cells somewhat small, almost twice as I0112: as
broad, moderately constricted, sinus rather variable,
often slightly open and acute-angled (more rarely
sublinear) ; semicells rounded-quadrate with sides
and apex very slightly convex, sometimes semi-elliptic ;
cell-wall granulate, granules in more or less distinct
vertical series (from 6 to 9 of these series visible
across the face of a semicell), about 20-25 visible
round the margin of a semicell, granules at the base
of the semicell sometimes more or less regularly
disposed in vertical pairs. Side view of semicell
ovate-oblong or subelliptic-oblong. Vertical view
broadly elliptic, ratio of axes 1 : 1*2. Chloroplasts
axile, with two pyrenoids in each semicell.
Zygospore unknown.
Length 42-5-55 li; breadth 23-30 ll; breadth of
isthmus 11-17 ll; thickness 20-24 ll.
England. — Angle Tarn, Cumberland ! Westmore-
land ! (Ralfs). Cocket Moss, W. Yorks! Strensall
Common, N. Yorks! (IF. B. Turner). Skipwith
Common, E. Yorks ! (Rev. W. Foiuler). Surrey !
Wilts ! Cornwall ! (Marquand).
Wales. — Capel Curig, Llyn-y-cwm-ffynon, bog
between Grlyder Fach and the river Llugwy, and
Glyder Faw'r, Carnarvonshire ! Dolgelly, Merioneth !
30 BRITISH DESMIDIACEiE.
Scotland. — Sutherland!, Inverness!, Aberdeen, Kin-
cardine, Forfar, Perth !, Argyll (Boy <$• Bissett). Outer
Hebrides ! Shetlands !
Ireland. — Donegal! Mayo! Gal way ! Kerry!
Dublin and Wicklow (Archer). Lough Neagh, Antrim.
Geogr. Distribution. — France. Germany. Austria
and Galicia. Italy. Norway. Sweden. Denmark.
Bornholm. S. Russia. Greenland. Ceylon. United
States. Brazil.
Although widely distributed in the older bogs, C. amoenum
is a very uncommon Desmid. Apart from the variation
exhibited by the sinus, the cell has a very characteristic
shape.
The granulation is not altogether uniform, and the vertical
series are often very indistinct. Near the base of the semicell
the granules are often associated in pairs, usually in a more
or less irregular manner, but sometimes with sufficient
regularity to give the appearance of a basal ring of paired
granules. This feature may be present to a greater or less
extent on one or both semicells, but owinar to its g-reat
variability is of little importance.
C. amoenum var. annulatum Eichl. & Ghitw. (cNonn. spec,
alg. now' 1894, p. 163, t. 4, f. 5), by reason of its general
proportions, the form of its sinus, and the fewness of its
granules, should be relegated to C. psmdmoenum var.
basilare Nordst., notwithstanding the fact that two pyrenoids
are present in each semicell. In very closehy allied forms too
much importance should not be placed upon the presence
of solitary or binate pyrenoids in axile chloroplasts. [Consult
Gosmarium subcostatum, C. subcostatum forma minor, and
C. subcostatum var. Becliii in Vol. Ill, pp. 236-239.]
C. amoenum var. Lundellii Roy & Biss. (' Scott. Desm.'
1894, p. 42; C. amoenum forma major Lund. 'Desm. Suec.'
1871, p. 46), which Messrs. Roy and Bissett record from
"Ross, Inverness, Banff, Aberdeen, Kincardine, Forfar,
Perth, and Stirling," appears to us to be very near to, if not
identical with C. sph,8eroideum West (1892). Its characters
were very briefly indicated by Lundell, and not at all by
Messrs. Roy & Bissett, so that it is difficult to make certain
of this identity. It should be pointed out that C. sphseroideum
(litters from C. amoenum in its somewhat larger dimensions,
its greatly inflated semicells, and in the larger and more
flattened granules.
COSMAEIUM. 31
Var. mediolaeve Nordst. (PL CII, figs. 5, 6.)
C. amaenum var. mediolseve Nordst. in Botan. Notis. 1887, p. 160 ; Freshw
Alg. N. Zeal. 1888, p. 50, t. 5, f . 12 ; De Toni, Svll. Alg. 1889, p. 989 ;
West, Alg. W. Ireland, 1892, p. 156 ; Eoy & Biss Scott. Desm. 1894,
p. 42 ; Borge, Sussw.-Chlor. Feuerland u. Is. Desola. 1906, p. 26 ; G. S.
West, Alg. Yan Yean, 1909, p. 64.
Semicells destitute of granules in the median part
(or lower median part), with two horizontal series of
granules across the base, and with the rest of the
granules disposed in decussating oblique series.
Length 45-76 /x ; breadth 26-40 /x. ; breadth of
isthmus 9-20 [x.
Scotland. — Dalbrake in Strachan, Kincardine (Boy
$ Bissett).
Ireland. — Ballynahinch, Galway !
Geogr. Distribution. — Australia. New Zealand.
Patagonia.
This variety varies much in size, the largest specimens
exceeding those of any other form of C. amoenum. The
granules are smaller than in typical C. amoenum, and their
disposition is quite different. The clear space in the median
part of each semicell is often punctate.
238. Cosmarium pseudamoenum Wille.
(PI. CII, figs. 7-9.)
Cosmarium pseudamoenum Wille, Svdamerik. Algfl. 1884, p. 18, t. 1, f. 37 ;
De Toni, Syll. Alg. 1889, p. 996 ; West, Alg. W. Ireland, 1892, p. 156 ;
Borge, Siissw. Cblor. Arehang. 1894, p. 19 ; Liitkem. Desm. Central
China, 1900, p. 119; W. & Gk S. West, Alga-fl. Yorks. 1900, p. 89; Alg.
N. Ireland, 1902, p. 38 ; Borge, Alg. erst. Regnell. Exped., II. Desmid.
1903, p. 85 ; Beitrage Alg. Schweden, 1906, p. 29 ; G. S. West, Alg.
Third Tanganyika Expedit. 1907, p. 123 [forms].
C. inornatum Josh. Burmese Desm. 1886, p. 648, t. 24, f. 26, 27 ; De Toni,
Syll. Alg. 1889, p. 966.
TJrsinella pseudamoena Kuntze, Bevis. gen. plant. 1S91, p. 925.
U. inornata Kuntze, 1. c. p. 925.
Dysphinctium pseudamoenum Schmidle, Beitr. Algenfl. Schwarzwald. \i.
Eheineb. 1S93, p. 92, t. 4, f. 4, 5. [Schmidle's figures are possibly
C. amoenum?^
Cells somewhat small, about twice as long as broad,
almost cylindrical, only slightly constricted, sinus a
small and open notch ; semicells oblong with the sides
straight or very slightly convex, apex broadly rounded
32 BRITISH DESMIDIACE.L.
or faintly truncate in the middle ; cell- wall uniformly
granulate, granules small and rather variable in dis-
position, sometimes irregular, sometimes in more or
less distinct longitudinal series, and not infrequently
in decussating oblique series. Side view of semicell
oblong with a rounded apex. Vertical view subcircular-
elliptic. Chloroplasts axile, with one pyrenoid (or
two ?) in each semicell.
Zygospore unknown.
Length 44-59 /x; breadth 18-29 fi ; breadth of
isthmus 15-24 fi ; thickness 21-255 fx.
England. — Skip with Common, E. Yorks !
Ireland. — Dungloe, near Glenties, Loughs Anna,.
Claggan, Magrath and Sproule, Donegal ! Foxford,
Mayo ! Clifden and Athry Lough, Galway !
Geogr. Distribution. — Germany. Galicia in Austria.
Sweden. Bornholm. Finland. N. Russia. Central
China. New Zealand (var.). E. Africa. LTnited
States. Brazil.
The distinctions between C. pseudamcenum and C. amoenum
are very slight. The cell of C. pseudamoenimi is proportionately
a little narrower, the constriction is less deep, and only one
pyrenoid is present in each semicell; but we are inclined to
think the latter character is not constant.
It is a species which requires thorough investigation.
Var. basilare Nordst. (PL Oil, figs. 10-12.)
C. pseudamcenum Wille var. basilare Norclst. in Botan. Notis. 1887, p. 160 ;
Freshw. Alg. N. Zeal. 1888, p. 50, t. 5, f. 14; W. & G. S. West, Some
Desm. U. S. 1898, p. 308 ; Borge, Beitrage Alg. Schweden, 1906, p. 29.
Semicells with a transverse double series of granules
across the base just above the isthmus, each pair of
granules being part of a bigranulate wart.
Length 40-53 /x ; breadth 22-5-30 fx ; breadth of
isthmus 15-22 ju, ; thickness 18-19 jx.
Scotland. — Near Tarbert, Harris, Outer Hebrides !
Geogr. Distribution. — Sweden. United States. New
Zealand.
The double series of basal granules are well marked in this
COSMARIUM. oo
variety. We have already commented upon the tendency
towards the formation of a similar basal zone in certain forms
of C. amoenum.
239. Cosmarium latifrons Lund.
(PI. XCIV, fig. 6.)
Cosmarium latifrons Lund. Desm. Suec. 1871, p. 30, t. 3, f. 7 ; De Toni,
Syll. Alg. 1889, p. 1011 ; Eoy & Biss. Scott. Desni. 1894, p. 104 ; Nordst.
Index Desmid. 1896, p. 156.
Ursinella latifrons Kiuitze, Eevis. gen. plant. 1891, p. 925.
Cells small, as long as broad, moderately constricted,
sinus very narrow and linear ; semicells widely trapezi-
form, sides upwardly diverging from a broad base,
inferior angles obtuse-angled, superior angles slightly
rounded, apex wide and convex ; cell-wall finely
granulate except in the centre of each semicell, the
margin having a finely serrate appearance, in the
centre with a small protuberance furnished with three
vertical series of larger granules. Side view of semi-
cell ovate, with a granulate inflation near the base on
each side. Vertical view elliptic, with a small tri-
granulate inflation at the middle on each side, granulate
except for an elliptic, smooth area in the centre. Chloro-
plasts axile, with one pyrenoid in each semicell.
Zygospore unknown.
Length 34-38 ^ ; breadth 34-38 /a ; breadth of
isthmus 15 jm; thickness 23'3/x.
Scotland. — Barrelwell Moss near Brechin, Forfar
(Roy Sf Bissett).
Geogr. Distribution. — Galicia in Austria, Norway.
Sweden. X. Russia (a form). Siberia.
C. latifrons is a small species somewhat resembling certain
forms of C. biretum in external shape, but with very distinctive
characters.
240. Cosmarium lepidum West.
(PI. XCIV, fig. 10.)
Cosmarium lepidum West, Alg. N. Yorks. 1889, p. 292, t. 291, f. 14; Roy
& Biss. Scott. Desm. 1894, p. 105 ; Nordst. Index Desm. 1896, p. 157 ; W.
& G. S. West, Alga-fl. Yorks. 1900, p. 89.
VOL. IV. 3
3 !• BRITISH DESM1DIACE.E.
Cells very small, subquadrate, about as long as
broad, deeply constricted, with a linear sinus ; semicells
transversely rectangular with straight sides and apex,
basal and apical angles scarcely rounded, apical angles
sometimes very slightly produced ; cell- wall uniformly
granulate giving the margins a minutely crenulate
appearance, granules disposed in transverse rows, three
of which are visible across the front of each semicell.
Side view of semicell circular. Vertical view elliptic,
ratio of axes about 1 : 1*7.
Zygospore unknown.
Length 16-17*5 fx ; breadth 17-18'Oju; breadth of
isthmus 6'5-7/a; thickness 10 ll.
England. — Mickle Fell, N. Yorks !
Scotland. — Ben Chiurn, Perth !
241. Cosmarium promontorium W. & G. S. West.
(PI. XCIV, fig. 9.)
Cosmarium promontorium W. & G. S. West, New Brit. Freshw. Alg. 1894,
p. 7, t. 1, f. 14; Nordst. Index Desmid. 1896, p. 206.
Cells small, about 1^ times longer than broad, deeply
constricted, sinus narrowly linear with a dilated
extremity ; semicells broadly subrectangular, with the
sides more or less irregularly biundulate, with three
crests (including the basal and apical angles) and two
hollows, the upper hollow being deeper than the lower
one, basal angles rounded, apical angles subacute and
prominent, apex convex but widely truncate in the
middle; with one series of minute granules just within
the margin of each semicell, about four within each
lateral margin and four within the apex. Side view of
semicell rounded-ovate, with the upper part of the
sides slightly retuse. Vertical view elliptic, with a
small inflation at the middle on each side. Chloroplasts
axile, with one pyrenoid in each semicell.
Zygospore unknown.
Length 22 [x; breadth 17/x; breadth of isthmus
3"5/x; thickness 10*5 ll.
Ireland. — Oorid Lough, Galway !
COSMARIUM. 35
242. Cosmarium crenatum Ralfs.
(PI. XCVIII, figs. 9-12.)
Cosmarium crenatum Ealfs in Ann. Mag. Nat. Hist. 1844, p. 394, t. 11,
f . 6 [in part] ; Hass. Brit. Freshw. Alg. 1845, p. 365 ; Ealfs, Brit. Desm.
1848, p. 90, t. 15, f. 7 b and c [not 7 a] ; Arch, in Pritch. Infus. 1861,
p. 732; De Not. Desm. Ital. 1867, p. 47, t. 4, f. 34; Eabenh. Flor.
Enrop. Alg. Ill, 1868, p. 165; Lund. Desm. Suec. 1871, p. 34; Nordst.
Desm. Spetsb. 1872, p. 29, t. 6, f. 7, 8; Desm. Arctose, 1875, p. 38 ; Alg.
aq. dulc. et Char. Sandvic. 1878, p. 12 ; Kirchn. Alg. Schles. 1878,
p. 149; Wille, Ferskv. Alg. Nov. Semlj. 1879, p. 40; Boldt, Siber.
Chlorophy. 1885, p. 105; Cooke, Brit. Desm. 1886, p. 95, t. 37, f. 13;
Hansg. Prodr. Algenfl. Bohm. 1888, p. 195 ; De Toni, Syll. Alg. 1889,
p. 941 ; West, Alg. N. Yorks. 1889. p. 292 ; Alg. N. Wales, 1890, p. 289 ;
Alg. W. Ireland, 1892, p. 150 ; Alg. Engl. Lake Distr 1S92, p. 726 ;
Borge, Chlor. Norska Finmark. 1892, p. 10 ; Liitkem. Desm. Attersees,
1893, p. 553 ; Borge, Siissw. Chlor. Archang. 1893, p. 21 ; Borg.
Freshw. Alg. Ostgronl. 1894. p. 14; Eoy & Biss. Scott. Desm. 1894,
p. 44; G-utwr. Flor. Glon. Okolic Tarnapola, 1894, p. 86; Schmidle,
Beitr. alp. Alg. 1895, p. 388 ; Nordst. Index Desmid. 1896, p. 87 ; W. &
G. S. West, Alg. S. England, 1897, p. 488 ; W. & G. S. West, Alga-fl.
Yorks. 190U, p. 80; Bnrg. Freshw. Alg. Faeroes, 1901, p. 227; Borge,
Siisswasseralgen Sud-Patagon. 1901, p. 22 ; Bohlin, Flor. Algol, d'eau
douce d. Acores, 1901, p. 65 ; W. & G. S. West, Alg. N. Ireland, 1902,
p. 37 ; Hirn, Desm. Finland, 1903, p. 8 ; Borge, Alg. erst. Eegnell.
Exped., II. Desmid. 1903, p. 92 ; Larsen, Freshw. Alg. E. Greenland,
19U4, p. 84 ; W. & G. S. West, Freshw. Alg. Orkneys' and Shetlands,
1905, p. 22 ; Borge, Beitriige Alg. Schweden, 190B, p. 34 ; Teodoresco,
Mater, flor. alg. Kouman. 1907, p. 177.
Euastrum crenatum Gay, Monogr. loc. Conj. 1884, p. 60. [not E. crenatum
Focke, Phys. Stud. 1847, p. 41, 1. 1, f. 3, which = Cosmarium ortogonum
Delp. ; nor E. crenatum Nag. Gatt. einz. Alg. 1849, p. 120, t. 1a, f. 8,
which = Cosm. Naegelianum Breb. ; nor E. crenatum Perty, 1852,
which = Cosm. dovrense Nordst.]
Cosmarium crenatum forma tricrena.ta Boldt, Siber. Chlorophy. 1885, p.
105.
C. crenatum a. Balfsiana Eacib. Nonn. Desm. Polon. 1885, p. 76.
C. crenatum e. major Eacib. 1. c.
Ursinella crenata Kuntze, Eevis. gen. plant. 1891, p. 924.
Cosmarium crenatum var. psychophilum Schmidle, Lappmark Siisswasser-
algen, 1898, p. 29.
C. crenatum forma sublsevis Schmidle, 1. c. p. 29.
C. ordinatum Larsen, Ferskvandsalg. Vest-Gronl. 1907, p. 333, t. 7, f. 11.
[not C. ordinatum (Borg.) W. & G. S. West, 1896].
Cells rather small, 1]-1^ times as long as broad,
moderately deeply constricted, sinus linear but not
quite closed ; semicells pyramidate-quadrate, with the
basal angles rectangular and slightly rounded, sides
3-crenate (or more rarely 4-crenate), apex truncate and
4-crenate, with 1-3 smaller subsidiary crenulations
within each lateral and apical crenation, internal
crenulations smooth or furnished with one or two
3G BRITISH DESMIDIACE.E.
minute granules, in the centre with 3-6 vertical costse,
sometimes smooth and indistinct, more rarely indis-
tinctly granulate. Side view of semicell rectangular,
basal angles slightly tumid, sides and apex faintly
retuse, apical angles minutely granulate. Vertical
view elliptic, with a broad 3-6-undulate inflation at
each side, poles subtruncate and minutely granulate.
Chloroplasts axile, with one pj^renoid in each cell.
Zygospore globose, furnished with many stout ver-
rucas (about 16 visible at the margin), slightly at-
tenuated and 2-, 3- or 4-furcate at the apex.
Length 27-43 (rarely to 59) fx ; breadth 22-31
(rarely to 44) p ; breadth of isthmus 9-13 fx ; thickness
14-22 (rarely to 2S) jx ; diam. zygosp. without verruca?
29 fx, with verrucas 38 /x.
England. — Cumberland ! Westmoreland ! Lanca-
shire (Balfs). W. and N. Yorks ! Sub-fossil at Filey,
E. Yorks! Leicestershire (Boy). Gloucestershire
(Balfs). Surrey! Sussex, Hants, and Wilts ! (Balfs).
Devonshire ! Cornwall !
Wales. — Llyn Teyrn on Snowdon, Penmaenmawr,
Moelfre, near Dolbaclarn Castle, Bethesda, Capel Curig*
(Cooke I' Wills), Moel Siabod, and Llyn Cwlyd, Car-
narvonshire ! Merionethshire ! Glamorganshire !
Scotland. — Common ; zygospores from Muchalls,
Kincardine, and Rannoch, Perth (Boy §• Bissett). At
3500 ft. on Lochnagar ! Orkneys ! Shetlands ! Outer
Hebrides !
Ireland. — Donegal ! Galway ! Kerry ! Dublin and
Wicklow (Archer). Down (up to 2000 ft.) !
Geogr. Distribution. — France. Germany. Austria
and Galicia. Bosnia. Hungary. Roumania. Italy.
Norway. Sweden. Denmark. Bornholm. Finland.
N. and S. Russia. Faeroes. Iceland. Nova Zembla.
Spitzbergen. Greenland. Siberia. Japan. India.
Australia. Abyssinia. E. Africa. Azores. Sandwich
Islands. United States. Brazil. Ecuador. Argentine.
Patagonia.
C. erenatum is largely an alpine and arctic Desmid. In
COSMARIUM. 37
mountainous areas it is not uncommon in boggy springs and
amongst mosses on dripping rocks. In more lowland districts
it is principally confined to ancient heaths.
The common British form has three crenations at each side
of the seinicell and four at the apex. Specimens are not
uncommon, however, with four crenations at each side, the
lower one being very variable in size, so that we have found
it impossible to draw any clear distinction between those forms
with three lateral crenations and those with four. The lateral
and apical crenations, as in so many Desmids, are merely
the optical expression of ridges which run across the cell
transversely to the greatest breadth. These ridges are them-
selves broken up into hummocks, so that one or two series of
crenations may often be focussed within the marginal ones.
Sometimes each crenation is minutely bigranulate, but this is
by no means a constant character even in the two halves of
the same cell. The vertical ribs in the centre of the semicell
are also very variable, sometimes being scarcely evident and
at other times more or less distinctly granulated.
After a careful consideration of the variation exhibited by
C. crenatum we have been compelled to include within the
general description of the species Boldt's forma tricrenata
and Schmidle's var. psychophilum (founded upon Nordstedt's
Spitzbergen forms) and var. sublsevis.
It should also be mentioned that C. crenatum varies much
both in size and in general proportions.
Forma Boldtiana (Gutw.) nob. (PI. XCVIII, figs.
13, 14.)
Cosmarium Boldtianum Gutw. Flor. Glon. Okolic Tarnapola, 1894, p. 100
t. 3, f . 36 ; Schmidle, Alg. aus Sumatra, 1895, p. 304.
C. tricrenatum Gutw. Prodr. Flor. Alg. Galic. 1895, p. 351.
Semicells with 5 or 6 crenations on each lateral
margin, the two lowest ones often much reduced in
size.
Length 29-42 ft ; breadth 22-28 p ; breadth of
isthmus 10-14 /x; thickness 10-18 fu
Scotland. — Not uncommon, but scarce (Roy Sf
Bissett).
Geogr. Distribution. — Gralicia in Austria. Sumatra.
This form only differs from the more typical forms in its
lateral crenations. It was originally figured by Ralfs ('Brit.
Desm.' 1848, t, 15, f. la).
38 BRITISH DESM1DIACE/E.
Var. bicrenatum Nordst. (PI. XCVIII, fig. 15.)
C. crenatum var. bicrenatum Nordst. Desm. Spetsb. 1S72, p. 30, t. 6, f . 10 ;
Desni. Ital. 1876, p. 35 ; Boldt, Desmid. Gronland, 1888, p. 18 ; Roy &
Biss. Scott. Desm. 1894, p. 44.
C. bicrenatum Joshua, Notes Brit. Desm. II, 1883, p. 291 ; Cooke, Brit.
Desm. 1886, p. 96, t. 42, f. 13.
Semicells with only two lateral crenations.
Length 24-3 3 /* ; breadth 17*5-26 /x; breadth of
isthmus 9*5-11 /x; thickness 12-1 5 /x,.
England. — Leicestershire (Roy).
Scotland. — Not uncommon, but scarce (Hot/ Sf
Bissett).
Geor/r. Distribution. — Italy. Norway. NovaZembla.
Spitsbergen. Greenland. Siberia.
243. Cosmarium Grantii Ptoy & Biss.
(PI. XCI, fig. 11.)
Cosmarium Grantii Roy & Biss. Scott. Desm. 1894, p. 102, t. 1, f. 10;
Nordst. Index Desm. 1896, p. 134.
Cells small, almost as long as broad, deeply con-
stricted, sinus linear; semicells subsemicircular-
rectangular, basal angles scarcely rounded, margin 12-
crenate, four up each side and four at each apex, the
three lower lateral crenations rather smaller than the
others, with a radiating series of about six very minute
binate granules within each cremation, and in the middle
immediately above the isthmus with two horizontal
series of conspicuous granules, five in each series.
Side view of semicell subquadrate, basal and apical
angles rounded, sides slightly retuse in the upper
portion, apex truucato-convex, with two granules on
each side just above the isthmus. Vertical view
elliptic-oblong, with a broad inflation at the middle
on each side.
Zygospore unknown.
Length 34-35 ju; breadth 30-31 /x ; breadth of
isthmus 13-14 p; thickness 15-16/*.
Scotland. — Grassel and Slewdrum, Aberdeen;
Letterbeg in Strachan, Kincardine (Roy Sf Bissett).
COSMARIUM. 39
We have not yet seen this species, which Messrs. Roy and
Bissett state has only been observed on wet rocks.
244. Cosmarium annulatum (Nag..) De Bary.
(PL Oil, figs. 13-15.)
Dysphinctium (Calocylindrus) annulatum Nag. Gatt. einzell. Alg. 1849,
p. 110, t. (i P ; Reinseh, Algenfl. Frank. 1867, p. 181 ; Hansg° Prodr.
Algenfl. Bohm. 1888, p. 186 ; De Toni, Syll. Alg. 1889, p. 887 ; Heimerl,
Desm. alp. 1891, p. 594; Hirn. Desm. Finland, 1903, p. 14.
Cosmarium annulatum (Nag.) De Bary, Conj. 1858, pp. 46, 72; Lund.
Desm. Suec. 1871, p. 46; Nordst. Desm. Arctoae, 1875, p. 30; Alg. aq.
dule. et Char. Sardvic. 1878, p. 14; Wille, Ferskv. Alg. Nov. Semlj.
1879, p. 49 ; Boldt, Siber. Chlor. 1885, p. 108 ; Desmid. Gronland, 1888,
p. 29 ; Borg. Desm. Brasil. 1890, p. 42 ; West, Alg. W. Ireland, 1892,
p. 157; W. & G. S. West, New Brit. Fresh w. Alg. 1894, p. 7, t. 2, f. 42;
Borg. Freshw. Alg. Ostgronl. 1894, p. 22 ; W. & G. S. West, Alg. S.
England 1897, p. 492 ; Bohlin. Flor. Algol, d'eau douce d'Acores, 1901,
p. 66 ; W. & G. S. West, Alg. N. Ireland, 1902, p. 42.
Penium annulatum Arch, in Pritch. Infus. 1861, p. 51; Rabenh. Flor.
Europ. Alg. Ill, 1868, p. 122 ; Lutkemull. Desm. Attersees, 1893, p. 544.
Calocylindrus annulatus Kirchn. Alg. Schles. 1878, p. 143 ; Cooke, Brit.
Desm. 1887, p. 122, t. 43, i. 15.
Cells rather small, subcylindrical, 2-2^ times as long-
as broad, scarcely constricted, sinns not evident; semi-
cells rectangular, sides 4-5-unclulate including the
apical angle, apex convexo-truncate, with 4-5 trans-
verse series of small nodules (5-6 in each series)
corresponding to the marginal undulations. Vertical
view circular, with about 14 marginal undulations (or
nodulations). Chloroplasts ....?, with two trans-
versely-disposed pyrenoids in each semicell.
Zygospore unknown.
Length 36-54 /x; breadth 16-23 /x; breadth of
isthmus 14-5-21 [x.
England. — Westmoreland (Bissett). Cornwall (Mar-
quand). Tintagel, Cornwall !
Wales. — Llyn Cwlyd, Carnarvonshire !
Scotland. — Ross, Aberdeen, Kincardine, and Perth
(Roy cj- Bissett). Shetlands !
Irkland. — Xacooo-arrow Louoli, Calwav! Carran-
tuohill, Kerry ! Adrio-ole, Cork ! Dublin and Wick
low (Archer). Slieve Donard, Down!
Geogr. Distribution. — France. Germany. Austria
and Galicia. Hungary. Italy. Norway. Sweden.
40 BRITISH DESMIDIACE.E.
Denmark. Bornholm. Finland. S. Russia. Xova
Zembla. Franz Joseph Land. Spitzbergen. Green-
land. New Zealand (var.). Sandwich Islands. "West
Indies. Brazil.
This characteristic species occurs mostly on wet rocks. It
requires further investigation, especially of living specimens,
as there is much doubt concerning the nature of its chloro-
plasts, and its position in the genus Cosmarium is by no means
certain.
Var. elegans Nordst (PI. Gil, figs. 10-18.)
C. annulatum var. elegans Nordst. Norges Desm. 1873, p. 23 ; Desm. Ital.
1876, p. 42 ; West, Alg. Engl. Lake District, 1892, p. 728 ; W. & G. S.
West, Further Contrib. Freshw. Alg. W. Indies, 1899, p. 284 ; Borg.
Freshw. Alg. Faeroes, 1901, p. 228 ; W. & G. S. West, Alg. N. Ireland,
1902, p. 42 ; Freshw. Alg. Orkneys and Shetlands, 1905, p. 23 ; Borge,
Beitrage Alg. Schveden, 1906, p. 36.
Crenations distinctly but minutely bigranulate.
Length 40-57-5 /n ; breadth 17-29 ^
England. — Borrowdale, Cumberland! Blea Tarn
and Pike of Bliscoe, Westmoreland ! Hawkshead,
Lancashire !
Wales. — Moel Siabod !, Pen-y-gwryd (Roy), and
Glyder Fach !, Garnarvonshire.
Scotland. — -Aberdeen, Kincardine, Forfar, and Perth
(Roy §' Bissett). Kirkcudbright!
Ireland. — Dublin and Wicklow (Archer). Slieve
Donard and Slieve Cominedagh, Down !
Geogr. Distribution. — Norway. Sweden. Faeroes.
Italy. West Indies.
G. annulatum var. elegans appears to be widely distributed,
and is a much prettier Desmid than the type. It is at once
distinguished from all forms of C. elegantissimum by its broadly
truncate, smooth apex, and by the scarcely evident median
constriction.
245. Cosmarium elegantissimum Lund.
(PI. CII, fig. 19.)
Cosmo ri\<in elegantissimum Liind. Desm. Suec. 1871, p. 53, t. 3, f. 20;
Wolle, Desm. U. S. 1884, p. 78, t. 14, f. 8-9 ; Johnson, Rare Desm.
U. S. II, 1895, p. 292, t. 2-10, f. 27 ; Nordst. Index Desmid. 1896, p. 116.
Cosmaridium elegantissimum Hansg. Prodr. Algenfl. Bohm. 1886, p. 246.
Pleurotseniopsis elegantissima De Toni, Syll. Alg. 1889, p. 909.
COSMARIUM. 41
Cells rather under medium size, about 2^ times
longer than broad, perfectly cylindrical with hemi-
spherical ends, median constriction very slight, sinus
a slight excavation; semicells oblong, with a rectangular
base, apex strongly convex. Cell-wall furnished with
emarginate verrucas (about 19 visible round the margin
of a semicell), disposed in regular vertical and hori-
zontal series, about 8 or 9 horizontal series and about
9 vertical series seen in front view. Vertical view
circular, with about 22 small nodulations round the
margin. Chloroplasts parietal, in three bands enclosing
two p}Trenoids in each semicell.
Zygospore unknown.
Length 82-88 n; breadth 33-37 »; breadth of
isthmus 24-27 j/.
Wales. — Capel Curig, Carnarvonshire (Boy fy
Bissett).
Ireland. — Derryclare Lough, Galway !
►Scotland. — Moidart, Inverness ! Powlair and
Slewdrum, Aberdeen ; Near Bridge of Bogandreep
and Blackball in Strachan, Kincardine ; Glen Garry
(Ron Sf Bissett), Ben Lawers, and Loch Katrine, Perth !
Geogr. Distribution. — Sweden. Bohemia in Austria.
United States.
Forma minor West. (PL CII, figs. 20, 21.)
C. elegantissimum Lund, forma minor West, Alg. W. Ireland, 1S92, p. 1(34,
t. 24, f. 10; Alg. Engl. Lake District, 1892, p. 730; W. & G. S. West,
Alg. S. England, 1S97, p. 492 [recorded as type] ; Borge, Trop. u. sub-
trop. Siissw.-Chlor. 1S99, p. 19 ; W. & G. S. West, Alga-n. Yorks. 1900,
p. 94 [recorded as type].
Cells less than two-thirds the size of the typical form.
Length 49-54 p; breadth 22-23 fi; breadth of
isthmus 17—19*5 /x.
England. — Borrowdale, Cumberland ! Bowness and
Helvellyn, Westmoreland ! Near Cockley Beck, Lanca-
shire ! Pilmoor, N. Yorks ! Skip with Common, E.
Yorks ! Thursley Common, Surrey ! New Forest,
Hants !
Wales. — Yr Orsedd, Carnarvonshire !
42 BRITISH DESMIDIACE.E.
Scotland. — Sutherland! Harris and Lewis, Outer
Hebrides !
[reland. — Acliill Island, Mayo! Carrantuohill,
Kerry !
Geogr. Distribution. — Uruguay.
This small form appeal's to he more frequent than the type.
It somewhat resemhles C. annulatum var. elegans, hut the
horizontal series of bigranulate warts are situated closer
together, and the convex, verrucose apex is quite distinctive.
We have described from the United States a var. simplidus
of C. elegantissimum in which the warts are entire, rounded
elevations (Cf. W. & CI. S. West, 'Some Desm. U. S.' 1898,
p. 308, t. 17, f. 7). This form also has the hemispherical
poles so characteristic of all forms of C. elegantissimum.
24(3. Cosmarium tuberculatum Arch.
(PL XCVII, figs. 9-11.)
Cosmarium tuberculatum Arch. Descript. New Cosm., etc., 1863, p. 247, t.
12, f. 11-15 ; Rabenh. Flor. Europ. Alg III, 1863, p. 178 ; Eoy & Biss.
Scott. Desm. 1894, p. 177 ; W. & G. S. West, Alga-fl. Yorks. 1900, p. 95.
Calocytindrus tuberculatxis (Arch.) Cooke, Brit. Desm. 1887, p. 123, t. 43,
f. 15 ; West, Alg. N. Yorks. 1889, p. 293.
Disphinctium tuberculatum De Toni, Syll. Alg. 1889, p. 892.
Cells minute, about lj times longer than broad,
moderately constricted, sinus widely open and shallow,
forming an obtuse angle ; semicells elliptic-hexagonal,
the upper convex margin bordered by -5-7 (usually 6)
minute and rather depressed granules. Side view of
semicell ovate-elliptic, with the upper convex margin
furnished with 5-6 granules. Vertical view broadly
elliptic, with 6-7 granules round the margin.
Chloroplasts . . . . ?
Zygospore unknown.
Length 15-18"5/x; breadth 12-14 /x; breadth of
isthmus 7-8 /t ; thickness 7'5-8"5 /a.
England. — Mickle Fell, N. Yorks!
Scotland. — Scotston Moor, Aberdeen ; Durris,
Kincardine ; between Loch Lomond and the head of
Loch Long, Dumbarton (Roy §' Bissett).
Ireland. — Dublin and Wicklow (Archer).
COSMARIUM. 43
We have only observed this minute species on one occasion.
Its outward form and granulation are very characteristic.
247. Cosmarium cylindricum Ralfs.
(PI. XCIV, fig. 7.)
Cosmarium cylindricum Ralfs in Ann. Mag. Nat. Hist, xiv, 1844, p. 392.
t. 11, f. 1 ; Hass. Brit. Freshw. Alg. 1845, p. 365, t. 86, f. 4 ; Ralfs, Brit.
Desm. 1848, p. 106, t. 17, f. 4; Arch, in Pritch. Infns. 1861, p. 734, t. 3,
f. 16-17; Rabenh. Flor. Europ. Alg. III. 1868, p. 176; Wille, Norges
1906, p. 29.
Penium Ralfsii Kiitz. Spec. Alg. 1819, p. 167; Delp. Desm. subalp. 1877,
p. 90, t, 15, f. 26-28.
Dysphinctium ? cylindricum Reinsch, Algenfl. Franken, 1867, p. 181 ;
Turn. Freshw. Alg. E. India, 1893, p. 44.
Calocylindrus Ralfsii Kirchn. Alg. Schles. 1878, p. 142.
Calocylindrus eylindricus (Ralfs) Racib. in Spraw. Kom. fizyjogr. Akad.
Una Krakow. 1884, p. 9 [= a. typica Racib.] ; Cooke, Brit. Desm. 1887,
p. 122, t. 43, f. 1-4; West, Alg. N. Wales, 1890, p. 291.
Disphinctium Ralfsii Hansg. in Osterr. bot. Zeitschr. XXXVII, 1887, p.
99 ; Prodr. Algenfl. Bohm. 1888, p. 186 ; De Toni, Syll. Alg. 1889, p. 888.
Cells rather small, subcylindrical, a little more than
twice as long as broad, very slightly constricted ;
semicells snbrectangnlar or snbqnadrate, with the
sides slightly divergent, apical angles rounded, apex
convex-truncate. Cell- wall furnished with small
granules rather densery arranged in somewhat in-
definite longitudinal series, 25-27 visible round the
margin of a semicell. Vertical view circular.
Chloroplasts . . . . r
Zygospore unknown.
Length o8-o7 fx; breadth 19-24 fx; breadth of
isthmus 15-17 /x.
England. — Helvellvn, Westmoreland ! Sussex
(Ralfs). Kent (Ralfs). Cornwall (Ralfs).
Wales. — Llyn Padarn !, and Capel Cnrig ! (Goohe Sf
Wills), Carnarvonshire. Machynlleth, Montgomery
(Ralfs).
Scotland. — Aberdeen, Kincardine, Forfar, Perth,
Arran (Roy Sf Bissett).
Ireland. — Athry Lough, Galway ! Dublin and
Wicklow (Archer).
44 BRITISH DESMlDIACEiE.
Geogr. Distribution. — France. Germany. Poland.
Austria. Italy. Norway. Sweden. N. and. 8.
Russia. Nova Zembla. United States. India.
This rather rare Desmid requires further investigation,
especially with regard to the nature of the chloroplasts. It
is not at all certain in the present state of our knowledge
whether it should be placed in the genus Cosmarium or in the
genus Penium.
248. Cosmarium subcylindricum West.
(PL XCIV, fig. 8.)
Cosmarium subcylindricum West, Alg. Engl. Lake Distr. 1S92. p. 728, t. 9,
f. 22 ; Nordst. Index Desm. 1896, p. 244.
Cells small, about If times longer than broad,
slightly constricted ; semicells semi-elliptic, with the
sides almost straight. Cell-wall densely granulate,
granules small and indefinitely disposed, with a single
transverse ring of larger granules at the base of each
semicell and immediately next the isthmus. Vertical
view circular.
Zygospore unknown.
Length o~/x; breadth 21 ll ; breadth of isthmus
18 li.
England. — Louglirigg, Westmoreland !
This Desmid differs from Cosmarium cylindricurn in the
shape of its semicells, especially the rounded poles, in the
irregular arrangement of the small granules, and in the ring
of larger granules at the base of each semicell. AVe have only
seen it on one occasion.
Addenda to G-enus Cosmarium.
249. Cosmarium basilicum G. S. West.
(pi. cm, %. i.) i
( 'osmarium basilicum G. S. West, Alga-fi. Cambr. 1899, p. 218, t. 396, f. 7 ;
Nordst. Index Desmid. Suppl. 1908, p. 29.
Cells of medium size, about 1^ times longer than
broad, deeply constricted, sinus narrowly linear with
COSMARIUM. 45
a very strongly dilated apex ; semicells subsemieirailar,
basal angles snbrectangular and slightly rounded, apex
very slightly flattened. Cell- wall granulate; granules
rather distant and arranged in somewhat irregular
oblique series, slightly diminishing in size towards the
centre of each semicell ; above the isthmus with 3
rather irregular transverse series of small granules,
about 5 or 6 in each series ; between the granules
minutely and densely punctate. Side view of semi-
cell circular. Vertical view elliptic with rounded
poles, ratio of axes 1 : 1*5.
Zygospore unknown.
Length 79 /x; breadth 66 {jl; breadth of isthmus
17 /x ; thickness 39 /x.
England. — Chippenham Fen, Cambridgeshire !
This species has the same outward form as G. radiosum
Wolle, but is otherwise very different from it. It should be
compared with C. dentiferum Corda, and with forms of C.
margaritiferum.
2-50. Cosmarium taxichondrum Lund.
(Pi. cm, figs. 11-13).
Cosmarium taxichondrum Lund. Desm. Suec. 1871, p. 39, t. 2, f. 13 ; Wille.
Norges Ferskv. Alg. 1880, p. 32; Wolle, Desm. U. S. 1884, p. 71, t. 16, f.
32-34; Lagerh. Bidr. Amerik. Desra.-fl. 1886, p. 237; Hansg. Prodr.
Algenfl. Bohm. 1888, p. 197 ; De Toni, Syll. Alg. 1889, p. 990 ; Borge,
Siissw. Chlor. Archang. 1894, p. 31 ; W. & G. S. West, Alg. Madag. 1895,
p. 66, t. 7, f. 2 ; Nordst. Index Desmid. 1896, p. 250; Cushman in Bull.
Torr. Bot. Club, xxxii, 1905, p. 551 ; Borge, Beitriige Alg. Schweden,
1906, p. 42.
C. taxichondrum a genuina Racib. Desm. Nowje, 1889, p. 88.
Ursinella taxichond ra Kuntze, Revis. gen. plant. 1891, p. 925.
Cells rather small, a little longer than broad, very
deeply constricted, sinus linear and slightly undulated ;
semicells semicircular, with the basal angles slightly
thickened and giving a faint impression of being
directed downwards, apex slightly flattened or sub-
truncate; cell- wall punctate, furnished with a prominent
granule in the median part of the semicell immediately
above the isthmus, and with two transverse arcuate
series of granules in the upper median region of the-
46 BRITISH DESMIDIACE.E.
semiceil, 3 in the upper series (just within the apex)
and 5-6 in the lower series. Side view of semicell
circular, with 3 prominent granules on each side.
Vertical view elliptic, poles somewhat conical, with
5-6 grannies at the median part of each side and 3
others within them. Chloroplasts axile, with two
pyrenoids in each semicell.
Zygospore unknown.
Length 36-50 /x ; breadth 32-5-45 /x ; breadth of
isthmus 9-14 /x; thickness 19-24 /a.
Scotland. — Rhiconich, Sutherland !
Geogr. Distribution. — Bohemia in Austria. Hungary.
Norway. Sweden. Poland. N. Russia, Siberia (var.)
China. Japan (var.). India. Ceylon (var.). Java.
Madagascar (and vars.). Abyssinia, Central Africa
(var.). United States (and vars.).
C. taxichondmm is a very rare British species, and is only
known to occur in these islands in its typical form. In tropical
and subtropical countries it is, however, much more abundant,
and exhibits considerable variation. There are about fourteen
named varieties, some of which are very characteristic and
retain fairly constant characters.
251. Cosmarium prominulum Racib.
(PI. CIII, fig. 2.)
Cosmarium prominulum Eacib. Noun. Desm. Polon. 1885, p. 79, t. 11, f. 7;
De Toni, Syll. Alg. 1889, p. 1004 ; West, Alg. W. Ireland, 1892, p. 149 ;
Liitkem. Desm. Attersees, 1893, p. 550; Koy & Biss. Scott. Desm.
1 894, p. 172 ; Nordst. Index Desmid. 1896, p. 206.
Ursinella prominula Kuntze, Eevis. gen. plant. .1891, p. 925.
Cells very small, as long as broad, deeply constricted,
sinus open with a rounded extremity ; semicells sub-
hexagonal, twice as wide as their height, lateral angles
obtusely niamillate, apex widely truncate, within each
lateral angle with a very small protuberance. Side
view of semicell rhomboid, lateral angles and apex
rounded, upper sides concave. Vertical view rhom-
boid-elliptic, with a large tumour at the middle on
each side, and a very small one on each side close to
COSMARIUM. 47
the poles. Cell-wall smooth. Chloroplasts axile, with
one central pyrenoid in each semicell.
Zygospore unknown.
Length 13-18 fi ; breadth 14-18 jx ; breadth of
isthmus 0—7*5 /x; thickness 9-12 /a.
Scotland. — Poole we, Ross; Brin, Inverness (R<v/ Sf
Bissett).
Ireland. — Grlen Caragh, Kerry !
Geogr. Distribution. — Austria and Galicia.
This species should be compared with Cosmarmm monochon-
dncui Nordst., from which, however, it is easily distinguished.
Var. subundulatum W. & G. S. West, (PI. CIII,
fig. 3.)
C. prominulum var. subundulatum W. & G. S. West, New Brit. Freshw.
Alg. 1894, p. 6, t. 1, f. 16.
Semicells with the apex slightly 3-4-undulate, and
with the superior lateral margins biundulate (one crest
and two hollows) ; vertical view with a more conical
median protuberance on each side, with the tumours
near the poles larger, and with the poles more markedly
mamillate.
Length 16-18 /x ; breadth 17-19 /x ; breadth of
isthmus 8-9*5 tt; thickness 13*5 fi.
England. — Elter Water, Cumberland !
Liitkemuller has described from Austria (' Desm. Millstat-
"tersees/ 1900, p. 10, t. 1, f. 28-30) a forma ornata of this
variety, to which is also referable the Desmid described by
Messrs. Eichler & Gutwinski as Cosmarium sculptum (vide
Eichler & Gutw. 'Noun, spec. alg. nov.' 1891, p. 169, t, 4,
f. 22).
Species to be Enquired into.
Cosmarium cruciatum Breb. Liste Desm. 1856, p. 129, t. 1,
f. 14; Rabenh. Flor. Europ. Alg. HI, 1868, p. 168; Kirclm.
Alg. Schles. 1878, p. 153 ; Wolle, Desm. U. S. 1884, p. 81.
t. 18, f. 23, 24; Hansg. Prodr. Algenfl. Bohm. 1888, p. 201,
251 ; De Toni, Svll. Alg. 1889, p. 1014 ; Roy & Biss. Scott,
Desm. 1894, p." 44; Nordst, Index Desmid. 1896, p. 90.
48 BRITISH DESMIDIACEJE.
Ursinella cruciata Kuntze, Revis. gen. plant. 1891, p. 924.
Cells small, about as long as broad, deeply constricted, sinus
narrow, widening outwards ; semicells truncate-pyramid ate,
inferior angles broadly rounded, apices broadly truncate,
margin slightly crenate. Vertical view elliptic, with a small
submamillate protuberance at the middle on each side. Side
view subcircular, with a small protuberance on each side.
Cell-wall finely granulate. Chloroplasts axile, with two
pyrenoids in each cell.
The above description is based upon the indifferent figures
of Brebisson and of "Wolle. Messrs. Roy and Bissett have
recorded G. cruciatum from Scotland as "Not common. Alford,
Aberdeen ; Cammie, Cowie, etc., Kincardine/' We are in-
clined to regard Brebisson's figure as belonging to some form
of G.punctulatum, a variety of which (var. brasiliense Nordst.)
possesses two pyrenoids in each semicell. Nordstedt (in litf.,
July, 1907) writes "I have never seen any Desmid which I
could identify with the figure of C. cruciatum Breb."
Cosmahium Tcepinii Breb. var. cambricum Joshua, New and
Bare Desm. 1885, p. 35, t. 254, f. 8. Joshua's figure is a very
poor one, but we believe this Desmid to be most probably
identical with C. didymoprotupsum W. & Gr. S. AVest (Consult
Vol. Ill, p. 192. t, 88, f. 8).
Genus 16. XANTHIDIUM Ebrenb. 1837.
Ehrenb. in Abh. Berlin. Akad. 1837 [1836], p. 114; Infns. 1838, p. 146.
Menegh. Svnops. Desm. 1840. p. 223.
Kiitz.' Phyc. gener. 1843, p. 162.
Eass. Brit. Freshw. Alg. 1845, p. 35S.
Raits, Brit, Desna. 1848, p. 111.
Kiitz. Spec. Algar. 1849, p. 177.
Arch, in Pritch. Infns. 1861, pp. 720, 735.
Rabenh. Flor. Europ. Alg. Ill, 1868, p. 221.
Lund. Desm. Suee. 1871, p. 74.
Kirchn. Al^. Schles. 1878, p. 154.
Wolle. Desm. U. S. 1884, p. 92.
Cooke, Brit. Desm. 1887, p. 129.
Boldt, Desmid. Gronland, 1888, p. 31.
I ><• Toni, Syll. Altj. 1889, pp. 905. 916.
Turner, Freshw. Al«j. E. India, 1893, p. 103.
G. S. West, Treatise Brit. Freshw. Alg. 1904, p. 168.
Wille in Engler & PrantL Naturlieh Pflanzenfam. 1909, p. 9.
][i>1«canthum (Lund.) "Wille in Engler & Prantl, Naturlieh Pflanzenfam.
1890, 1, 2, pp. 7, 11. [ = Subgen. Holacanthum Lund. Desm. Suec. 1871,
p. 75].
Scliizacanthv/m (Lund) Wille, 1. e. p. 11 [ = Subgen. Schizacanthum Lund,
1871].
XANTHIDIUM. 49
Cells of very variable size, usually somewhat longer
than broad, invariably compressed (except in the rare
triangular forms), symmetrical in three planes at
right angles to each other; median constriction invari-
ably deep ; semicells of variable outline, elliptical,
elliptic-hexagonal, trapeziform, or polygonal, generally
with a flattened apex, centre of the semicell (with rare
exceptions) differentiated as a thickened, often scrobicu-
lated, and generally protuberant area; vertical view
more or less elliptic, generally with a protuberance at the
middle on each side. C 'ell-wall furnished with simple,
or more rarely with furcate spines, sometimes disposed
in a median plane, but usually arranged more or less
symmetrically on each side of a media it plane. Chloro-
plasts generally parietal, arranged in four cushions in
each semicell, each with one or more pyrenoids, but
often irregular, partly parietal and partly axile ;
chloroplasts axile in many of small species, with a
single central pyrenoid in each semicell.
Zygospores globose, usually furnished with simple
or furcate spines of variable length, more rarely spine-
less and conspicuously scrobiculate.
The genus Xanthidiiun is distinguished by the compressed
cells, the symmetrical, and generally paired, arrangement of
spines, and by the differentiated central area of the semicells.
The last character is one of the most important features of
the genus, although it is often very slight, and is entirely
absent in a few forms (such as X. antilopseum var. Iseve, X.
eontroversum, and X. cristatum var. leiodermum) . The differen-
tiated region may take the form of a thickened area, with or
without scrobiculations, or of a protuberance of variable size,
which may be entire, granulate, dentate, or spinate.
The genus is neaidy related to Cosmarium, Arthrodesmus,
and Staurastrum, from the first of which the majority of the
species may have been evolved. It is mostly in the tropics
that transitional species occur which connect the genera
Cosmarium and Xanthidiitm. Turner remarks about the
Indian species Xanthidium cosmariforme that "this might
just as correctly be called Cosmarium xanthidiforme"
Lundell, in 1871, instituted the two subgenera >Schizacau-
tlutm and Holacanthum, the former to include the species
VOL. IV. 4
50 BRITISH DESMIDIACE^I.
with furcate spines and the latter those with simple spines.
Wide, in 1890, elevated these to generic rank, but on most
inadequate grounds, as may be seen by mere reference to the
forms of the common species X. armatum. Moreover, in
some of the tropical and subtropical species partially divided
spines occur of such a nature that it is impossible to refer
these species with certainty to either of Wille's proposed
genera. It is also significant that in his revised account of
the Chlorophyceas in Engler & Prantl, ' Natiirl. Piianzenfam.'
1909, Wille has himself submerged his proposed genera in
the genus Xanthidium.
Boldt, in 1888, suggested that the genus should be sub-
divided into Euxanthidium, with parietal chloroplasts, and
Centrenterium, with axile chloroplasts. For the reasons that
the disposition of the chloroplasts of most species of Xantln-
divm is entirely unknown, and that the parietal disposition of
chloroplasts may be acquired at any time by any Desmid, and
is therefore no criterion of its affinities [vide Vol. II, p. 126],
these suggestions cannot be accepted. Moreover, the chloro-
plasts do not appear to be constant and may sometimes be
parietal and sometimes axile in the same species.
Turner, in 1893, adopted LundelFs two subdivisions, to
which he added a third, Micracanthum ; and this subdivision
of the genus into three sections we have adopted.
The decisive combination of characters which we adopt for
this genus is the possession of spines and the presence of a
differentiated area in the centre of each side of a compressed
semicell. Even in the very rare triangular forms the differen-
tiated area is present in the middle of each of the three sides.
This central area (whether protuberance or thickening) is
the only distinction which really separates Xanthidium from
Artlirodesmiib1.
We arrange the British species as follows : —
Section A. Schizacanthum Luud. Cells large or very large,
with ti'i- or quadrifurcate processes.
1. X. armatum.
Section B. Holacanthum Lund. Cells of medium size or
small, with long simple spines.
a. Semieells Avith one pair of spines on each side.
* Semieells elliptic, lateral spines in a vertical plane, cen-
tral area small and slio-htiv thickened.
2. X. subhastxferum.
** Semieells elliptic-hexagonal (not regularly elliptic),
lateral spines not in a vertical plane, central area
large, thickened, and scrobiculated.
3. X. tetracentrotwm.
xanthidium. .-)!
? Semicells elliptic-hexagonal, lateral spines iii a vertical
plane, central area absent or small, sometimes
scrobiculated.
4. X. controversion.
b. Semicells with two pairs of spines on each side.
* Cells small: semicells trapeziform with retuse (or
straight) sides and apex.
5. X. Smith it.
** Cells of medium size ; semicells more or less elliptic-
hexagonal.
6. X. antilopa um.
c. Semicells with two pairs of spines and one single spine on
each side
7. X. cristatum.
d. Semicells with three pairs of spines on each side.
8. X. fasciculatum.
e. Semicells with about 8-10 spines on each side, in pairs or
more or less irregularly scattered.
* Spines mostly in pairs.
** Spines irregularly scattered.
9. X. Brebissonii.
10. X. aculeatum.
Section C. Micracanthum Turner. Cells small or very small,
with very minute simple spines.
11. X. variabile.
1'2. X. Robinsonianum.
13. X. Orcadense.
14. X. apiculiferum.
15. X. concinnum.
1. Xanthidium armatum (Breb.) Rabenh.
(PI. CIV, figs. 1-5.)
Cosmarium armatum Breb. in Menegh. Synops. Desm. 1840, p. 218.
Euastrum armatrum Kiitz. Phyc. germ. 1845, p. 187.
Xanthidium furcatum Raits in Ann. Mag. Nat. Hist, xiv, 1845, p. 466,
t. 12, f. 1.
Xanthidium armatum (Breb.) Rabenh. Deutschl. Kryptoo-amenfl. Bd. II,
Algen, Leipsie, 1847, p. 55 ; Balfs, Brit. Desm. 1848, p. 112, 1. 18 ; Arch,
in Priteh. Infus. 1861, p. 735, t. 1, f. 27-28; Rabenh. Flor. Enrop.
Algar. Ill, 1868, p. 222 ; Lund. Desm. Suec. 1871, p. 75. t. 5, f. 4 ; Arch.
in Q. J. Micr. Sci. xiii, 1873, p. 37 ; Kirchn. Alg. Schles. 1878, p. 151 ;
Wolle, Desm. U. S. 18S4, p. 92, t. 21, f. 2-4 "figures poor] ; Cooke, Brit.
Desm. 1887, p. 129, t. 45, I'. 1 [figures very poor]; Hansg. Prodr.
Algenfl. Hohm. 1888, p. 191, f. 114; De Toni, Svll. Alg. 1889, p. 916;
West, Alg. N. Wales, 1890, p. 291 ; Alg. W. Ireland, 1892. p. 164; Alg.
Engl. Lake District, 1892, p. 730 ; Roy & Biss. Scott. Desm. 1893, p. 211 ;
Nordst. Index Desm. 1896, p. 51 ; W. & G. S. West, Alg. S. England,
1897, p. 4*4; Schmidle, Lappmark Susswasseralgen, 1898, p. 21; W. &
G. S. West, Alga-fl. Yorks. 1900, p. 67 ; Borg. Freshw. Alg. Faeroes,
.">2 BRITISH DESMIDIAOEjE.
1901, p. 229 ; W. & G. S. West, Alg. N. Ireland, 1902, p. 30 ; Hirn,
Desm. Finland, 1903, p. 23 ; W. & G. S. West, Scott, Freshw. Plank-
ton, I. 1903, p. 527 ; Cushm. in Bull. Tor. Bot. Club. 1904, xxxi, p. 583,
t, 26, f. 7 ; W. & G. S. West, Further Contrib. Freshw. Plankton Scott.
Lochs, 1905, p. 485 ; Corap. Study Plankton Irish Lakes, 1906, p. 85 ;
Borge, Beitrage Alg. Schweden, 1906, p. 28 ; W. & G. S. West, Brit.
Freshw. Phytoplankton, etc., 1909, p. 180 ; Phytoplankton Engl. Lake
Distr. 1909, p. 138.
Euastrum Bigorrianum Perty in Mittheil. d. naturforsch. Ges. Bern,
1849, p. 174.
Zygoxanthium Bigorrianum Perty, Kleinst. Lebensf. 1852, p. 209, t. 16,
f. 23.
Didymidium (Xanthidmm) armatum Eeinsch, Algenfl. Frank. 1867, p. 129.
Xanthidiwm Bigorrianum (Perty), Rabenh. Flor. Europ. Alg. Ill, 1868,
p. 222.
X. armatum var. Wolleanum Turn. New and Pare Desm. 1885, p. 938,
t. 15, f. 18.
X. armatum var. Americanum Turn. 1. c. t. 15, f. 19.
Schizacanthum armatum (Breb.) Wille in Engler & Prantl, Natiirl. Pflan-
zenfamil. 1890, p. 11, 12, f. 7E.
Xanthidium armatum var. supernumerariv/m Schmidle, Beitr. alp. Alg.
1895, p. 348, t. 15, f. 8.
Cells large, from 1^ to 1^ times as long as broad,
deeply constricted, sinus open and acute-angled, some-
what acuminate at the extremity ; semicells somewhat
octangular (reckoning the isthmus as one of the eight
sides), lower margins slightly convex, inferior and
superior lateral margins usually very slightly concave
but not infrequently straight, apex straight or
slightly convex, with the two lateral angles and the
apical angle on each side furnished with short, stout,
solid, wart-like spines, which are 2-4 (commonly 3)-
furcate at the apex, with a similar stout furcate spine
within each lateral angle and with a pair just within
the apex (all of which are subject to variation), in the
centre of the semicell with a ring of simple or emar-
ginate teeth representing the serrated edge of a large
central wart. Side view of semicell ovate-rectangular,
near the base on each side with a laro-e truncate toothed
w art, apical angles furnished with 2-o-furcate spines,
and with 2 similar furcate spines at the truncate apical
margin. Vertical view elliptic-oblong with subtnmcate
poles, with a large truncate toothed wart at the middle
on each side, and with four stout 2-o-furcate spines at
equal intervals along each polar margin. Cell-wall
punctate. Chloroplasts sometimes distinctly parietal,
XANTHID1UM. 53
4 in each semicell, eacli with several pyrenoids; but
frequently variable (?).
Zygospore globose or subglobose, thick-walled, and
rather densely covered with large scrobiculations.
Length (with spines) 116-185 /x ; breadth (with
spines) 78-127 /x; breadth of isthmus 30-43 p; thick-
ness (33-88 fi ; diam. zygosp. 100-131 \x.
England. — Cumberland ! Westmoreland ! Lanca-
shire ! W. and N. Yorks ! Norfolk (Cooke). Herts
(Hassall). Bucks! Warwickshire (Wills). Surrey!
Sussex! Kent! Hants! Devon! (Bennett) . Corn-
wall! (Rolfs). In the plankton of Coclale and Easdale
Tarns, Westmoreland !
Wales. — General! Zygospores from Capel Curig,
Carnarvonshire (Boy). Not uncommon in the plank-
ton.
Scotland.— General ! Zygospores from Loch Inver,
Sutherland; Cammie, Kincardine; and Glencoe, Argyll
(Bo ij Sf Bissett). Lewis, Harris, N. and S. Uist, and
Benbecula, Outer Hebrides ! General in the plankton
of the western lochs ! Zygospores in abundance from
bog near Loch Coruisk, Skye !
Ireland. — Donegal ! Mayo ! Galway ! Kerry !
Dublin and Wicklow (Archer). Down ! Very rare in
the plankton of the lakes in Galway !
Geogr. Distribution. — France. Germany. Austria
and Galicia. Hungary. Italy. Norway. Sweden
(with zygospores). Denmark. Finland. Poland.
N. and S. Russia. Faeroes. N. India. New Zealand
(var.). Cuba. United States.
X. armatum is generally distributed over the Avhole of the
British Islands except the eastern counties of England. It
often occurs in abundance in Sphagnum-bogs and at the
boggy margins of lakes. It also occurs in Loth the plankton
and benthos of the lakes of the western British areas, being
associated with various species of Gonmarium, Staurastrum,
Micrasterias, and Euastrum, and with the filamentous genera
Gymnozi/ga and Hijalotheca.
One of the handsomest of Desmids, X. armatum is the only
British species which possesses furcate spines. Six series of
54 BRITISH DESMIDIACEjE.
these spines traverse the semicell at right-angles to the plane
of compression, each series forming a short arc over one of
the six angles of the semicell. The variation in X. armatum,
which at first sight appears very considerable, is practically
confined to the variation in the number, in the degree of sub-
division, and in the relative regularity in disposition of these
furcate spines. Normally, there are four such stout spines in
each series, but this is frequently reduced to three in some of
the series. The trifurcate spine also seems to be the typical
one, although bifurcate spines are common, and others divided
to a greater or lesser extent into four teeth are scarcely less
frequent. The large truncated wart in the centre of each
semicell is furnished, in the typical form, with a marginal ring
of simple or emarginate teeth. The disposition of the furcate
spines is not always in regular series, and where such a
departure from the regular arrangement exists, even in only
a few of the series, the front view of the Desmid presents an
aspect of irregularity which has been largely responsible for
such named varieties as " var. supermimeraria Schmidle."
" var. incongruum Turn./' and "var. intermedium Schroder."
The stout spines of this species are very slightly hollowed
at the base, but are otherwise solid; and the punctulation of
the cell-wall is much more conspicuous in some individuals
than in others.
Vie figure on Plate CY, fig. 5, a curious form of X. armatum,
which must be either a reduction- form resulting from rapid
division or one of the early stages in the development from
the zygospore. Only two specimens have been seen, both
from the west of Ireland in 1892. Hustedt has recently
mentioned (fDesm. et Bacill. aus Tirol/ 1911, p. 337, fig. 27)
a similar reduction-form from the Tyrol.
Var. fissum Nordst. (PI. CV, figs. 1, 2.)
X. a rmatum var. fissum Nordst. Alg-. aq. dale, et Char. Sandvic. 1878, p. 17.
t. 2, f. (j ; Schmidle, Lappmark Siisswassoralgen, 1898, p. 21.
Spines much more elongate, 2-3-furcate at the
apex; central wart of the semicells elongate and
similar to the marginal spines, o-4-furcate at the
apex.
Length (with spines) 135-160/*; breadth (with
spines) 104-122 /x; breadth of isthmus o0-34 fx ;
thickness 80-80 /x.
XANTHIDITJM. 55
Wales. — Capel Curig lakes, Llyn-y-cwm-ffynon, and
Grlaslyn, Carnarvonshire !
Geogr. Distribution. — Norway. Sandwich Islands.
This is a very distinct variety, at once recognizable by the
elongation of the basal portions of the spines, and by the nature
of the central protuberance, which is very similar to the
marginal spines. It is apparently a very rare variety, but it
occurred in great abundance in Llyn-y-cwm-ffynon, both in
the benthos and the plankton.
Var. irregularius West. (PL CV, figs. :3, 4.)
X. armatum var. irregularius West, Alg\ W.Ireland, 1892, p. 164, t. 21, f. 1.
Spines of variable character, often of the nature of
emarginate or tridentate warts, often simple with
obtuse extremities, generally very irregular in disposi-
tion.
Length (with spines) 172-181 /x ; breadth (with
spines) 110-12(3 /x ; breadth of isthmus 41-50 /x.
Ireland. — Ballynahinch and Kylemore, Galway !
Var. cervicorne W. & G. S. West. (PI. CVI, figs.
1-4.)
X. armatum " finely developed form " Wolle, Desm. U. S. 1884, p. 92, t. 21,
f. 1.
A', armatum var. cervicorne W. & Gr. S. West, Some Desm. U. S. 1898, p.
3<)<>, fig. xylogr. 3 a-c; Notes Alg. Ill, 1903, p. 74; Cushman in
Khodora, vii, 1905, p. 259; W. & (i. S. West, Brit. Freshw. Phyto-
plankton, etc. 1909, p. 180.
Larger than the type, with the spines much longer,
basal part of spines elongated as in var. fissum, apical
part more deeply 3-5-furcate and frequently branched
in a subdichotomous manner ; teeth of the central wart
much larger and more elongated.
Length (with spines) '242-255 tt ; breadth (with
spines) 170-181 tt; breadth of isthmus 47—51 /a.
Wales. — In the plankton of the Capel Curig lakes
and Llynau Dy waunedd, Carnarvonshire !
Scotland. — Rhiconich, and in the plankton of Loch
Shin, Sutherland !
Geogr. Distribution. — United States.
56 BRITISH DESMIDIACILE.
This variety is one of the very handsomest of British
Desmids. The spines are greatly elongated and much
furcate, the branches reminding one of the tynes of an
antler.
2. Xanthidium subhastiferum West.
(PL CVI, figs. 5-9.)
Xanthidium subhastiferum West, Alg. W. Ireland, 1892, p. 16(3, t. 22, f. 4;
W. & Gr. S. West, Scott. Freshw. Plankton, I. 1903, p. 540, t. 16, f. 4-5;
Further Contrih. Freshw. Plankton Scott. Lochs, 1905, p. 485 ; Comp.
Study Plankton Irish Lakes, 1906, pp. 85, 102; Brit. Freshw. Phvto-
plankton, etc. 1909, p. 180.
X. quadricornutum Roy & Biss. forma lonaispina Borg. Freshw Alo-
Faeroes, 1901, p. 229, t. 7, f. 13.
Cells rather under medium size, about as long as
broad, deeply constricted, sinus acute-angled, open,
sometimes acuminate at the apex; semicells elliptic
or oblong-elliptic, often slightly flattened at both base
and apex, each lateral margin furnished with two
simple divergent spines situated in the same vertical
plane; in the centre of the semicell with a small,
rounded, thickened area. Side view of semicell
circular. Vertical view elliptic, with an elongated
spine at each pole, and with a slight thickening,
generally faintly protuberant, at the middle on each
side.
Zygospore unknown.
Length 43-54 //, ; breadth without spines 44-53*5 /x ;
breadth with spines 64-86 /a ; length of spines 12'5-
18 /x; breadth of isthmus 13-19/t; thickness 25-29 fi.
Scotland. — Plankton of Lochs nan Cuinne and
Ghriama, Sutherland (.7. Murray) ! Plankton of Loch
Luichart, Eoss ! Plankton of Loch Morar and Loch
Shiel, Inverness ! Plankton of Loch Fadaghoda. Lewis,
Outer Hebrides!
Ireland. — In the plankton of the small lakes between
Clifden and Roundstone, Gal way ! Lough Guitane and
Glen Caragh, Kerry ! Common in the plankton of the
lakes of Kerry !
Geogr. Distribution. — Faeroes.
XANTllIDiUM. .57
X subhastiferum is for the most part a plankton-Desmid,
occurring now and then in considerable quantity in the
western lakes. It sometimes exhibits a certain amount of
irregularity in the disposition of the spines, but such irre-
gularities are merely slight monstrosities due to rapidity of
division and other causes. The normal specimen possesses
two equal divergent spines placed one above the other, but
occasionally one spine is reduced or absent (PI. CVI. fig. 8),
or a third incipient spine is developed between the lateral
pair.
It is a very distinct species, but should be carefully
compared with X tetracentrotum Wolle.
Var. Murrayi W. & G-. S. West. (PL CVI, figs. 10,
11.)
X. subhastiferum var. Murrayi W. & G. S. West, Scott. Freshw. Plankton,
I. 1903, p. 540, t. 16, f. 6 ; Further Contrib. Freshw. Plankton Scott.
Lochs, 1905, p. 485; Brit. Freshw. Phytoplankton, etc., 1909, p. 180;
Phytoplankton Engl. Lake District, 1909, pp. 138, 288.
Semicells somewhat obsemicircular, with the apex
slightly convex but flattened in the middle, and with
the two lateral spines of each side disposed in a
horizontal (or sometimes more or less oblique) plane.
Length 52-61 /x,; breadth without spines 505-62 /(,
with spines 87-97 /x; breadth of isthmus 17-ll>/ot.
England. — Plankton of AVindermere, Hawes Water,
and Grasmere, Westmoreland !
Scotland. — Plankton of Loch Morar, Inverness ! ;
and Loch nan Cuinne, Sutherland (.7. Murray) !
This variety seems to be confined to the plankton, and since
its first discovery in Loch nan Cuinne, Sutherland, it has been
found in considerable abundance in other Scottish and English
lakes. It is one of the leading constituents of the autumn
plankton of Windermere, occurring in quantity from
September to November.
A slight abnormality was observed in a single specimen
from Grasmere in the English Lake District, one semicell
possessing an obliquely disposed pair of short, curved, apical
spines {vide PL CIII, fig. 14).
A triangular form, which we have named "forma tkiquetka "
occurs in the plankton of Loch Lomond (vide PI. CYI1, figs.
9, 10). This differs only in the triangular character of the
58 BRITISH DESMIDIACE2E.
semicells, 1 > t - i 1 1 u* strictly analogous to A', antilopseum var.
triquetrum Lundelb, and as in that variety the thickened central
area is present in the middle of each of the three sides. It
is at its greatest abundance from July to September.
3. Xanthidium tetracentrotum Wolle.
(PL CVII, figs. 1 , 2.) !
Xanthidium tetracentrotum Wolle in Bull. Torr. Bot. Club, 1882, p. 29, t.
L3, f. II: Wolle, Desm, U. S. 18S4. p. 95, t. 22, f. 8-9; De Toni, Syll.
Alg. 1889, p. 92:5; W. & G. S. West, Some N. Amer. Desm. 1896,
p. 253, t. 15, f. 24 ; Cushman in Rhodora, vii, 1905, p. 260, t. 64, f. 8, 9.
Arthrodesmus incrassatus Lagerh. Bidrag. Amerik. Desm.-fl. 1885, p. 242.
t. 27, f. 18; Wolle, Freshw. Alg-. U. S. 1887, p. 35, t. 61, f. (i ; De Toni,
Syll. Alg-. 1889, p. 1061.
Cells somewhat small, a little longer than broad,
deeply constricted, sinus widely open outwards with
a submamillate extremity; semicells subelliptic or
reniforin-elliptic, with the dorsal margin more convex
than the ventral margin, slightly flattened at the
middle of the ventral side and with the cell-wall
faintly thickened in the middle of the apex, each
lateral angle furnished with either one or two simple,
elongated, outwardly-curved spines ; in the centre of
the semicell with a thickened (and usually yellow-
brown) area of considerable size, possessing prominent
scrobiculations which are variable in size, number, and
disposition. Side view of semicell subcircular or
obovate-subcircular, with a conspicuous thickening of
the wall on each side. Vertical view rhomboid-elliptic,
with either one or two simple spines at each pole, and
a prominent thickening of the wall in the median part
of each side.
Zygospore unknown.
Length 41-50^; breadth without spines 33-40 /a,
with spines, 54-66 fx ; breadth of isthmus 12 /a; thick-
ness 23-25 /x.
Geogr. Distribution. — United States.
The typical form of this species is not known to occur in the
British 'islands. Its most characteristic feature is the large
thickened and scrobiculated area in the centre of the semi-
cell. The single or paired lateral spines are also distinctive.
XANTHIDIUM. 59
Forma protuberans nob. (PI. CVII, fig. 3.)
A large form with the semicells elliptic-hexagonal,
and with a small protuberance in the middle of the
scrobiculated central area.
Length 58 /t; breadth without spines 52 fi, with
spines 7«»/x; breadth of isthmus 15 /x; thickness 36 /x.
Scotland. — In the plankton of Loch Laxadale,
Harris, Outer Hebrides !
Var. quadricornutum (Roy & Biss.) W. & G. S. West.
(PL CVII, fig. 4.)
Xanfhidium quadricornutum Roy & Biss. Scott. Desm. 1893, p. 245, t. 4,
f. 5.
X. tetracentrotum Wolle var. quadricornutum (Roy & Biss.) W. & G. S.
West, Notes Alg. II, 1900, p. 291.
Spines shorter, with the pairs rather irregularly
disposed; central area large, not much thickened and
not protuberant, densely scrobiculate.
Length 47*5-50 p; breadth (without spines) 45-
47*5 p; breadth of isthmus 14-15 fx.
Scotland. — In a pool near Durris Bridge, Kincardine
{Boy § Busett).
As we pointed out in the ' Journal of Botany,' in 1900,
this variety differs very little from the American plant first
described by Wolle.
4. Xanthidium controversum W. & G. S. West.
(PI. CVII, figs. 5, 6.)
Xanthidium antilopteum (Breb.) Kiitz. 'forma' W. & G. S. West, Some
N. Amer. Desm. 1896, p. 252, t. 16, f. i.
X. controversum W. & G. S. West, Some Desm. U. S. 1S9S, p. 298, t. 17,
f . 2 ; Cushman in Rhodora, vii, 1903, p. 260; Nordst. Index Desmid.
Suppl. 1908, p. 41.
Cells rather under medium size, 14 times longer than
broad (without spines), deeply constricted, sinus
open and acute-angled, with an acuminate apex ;
semicells elliptic-hexagonal, upper lateral margins some-
times slightly retuse, apex widely truncate, lateral and
apical angles furnished with a single spine (or some-
00 BRITISH DESMIDIACEjE.
times with a pair of spines), all the spines upwardly
curved ; central area of semicell not differentiated or
very slightly thickened. Side view of semicell
circular. Vertical view elliptic. Cell-wall minutely
punctate.
Zygospore unknown.
Length without spines 36*5-38 /a, with spines 55-
•59 [jl ; breadth without spines ol jx, with spines 52-56 fi ;
breadth of isthmus 7'6-Sfx; thickness 20-21 /x.
Geogr. Distribution. — United States.
This is the only species of the genus in which the type
form is practically destitute of a differentiated central area.
As yet the typical form has not been observed in the British
Islands.
In outline the semicells are very similar to those of
X. antiloj)seum , but it is a smaller species with the spines of
each semicell more upwardly directed, and often with only
solitary spines at the angles. It appears to stand in an
intermediate position between X. antilopaeum and X. inchoatum
Nordst.
Var. planctonicum W. & G. S. West. (PI. CVII,
figs. 7, 8.)
X. controversum var. planctonicum W. & G. S. West, Scott. Freslr\v.
Plankton, I. 1903, p. 539, t. 16. f . 2, 3 ; Further Contrib. Preshw.
Plankton Scott. Lochs, 1905, p. 72 ; Brit. Freshw. Phytoplankton, etc.,
1909, p. 180.
A larger variety, with the sinus less open and
linear with a dilated extremity; central area of semi-
cells finely scrobiculated and with a small central
protuberance. Vertical view with a small tumour at
the middle on each side.
Length without spines 49-52 /x ; breadth without
spines 46-49 /x; length of spines 16-2o/x; breadth of
isthmus 12*5— 13*5 /tx; thickness 31 /x.
Scotland. — -Plankton of Loch Shin and Loch a
G-harbh Bhaid Mh'oir, Sutherland ! Plankton of Loch
(Ihriama, Sutherland (J. Murray) ! Plankton of Lochs
an Sgath, Langabliat, Shrubhail, Stranabhat, and
an Tomain, Lewis, Outer Hebrides !
XANTHIDIUM. Gl
This distinctive variety occurred abundantly in Loch Shin,
and we suggested at the time of its description that owing to
its striking characters it might perhaps be regarded as a
distinct species — X. planctonicum.
The cells are larger than those of the type, the sinus is
closed, the spines are longer, and those of the inferior angles
are less divergent; in the centre of the semicells is a scro-
biculated area which is thickened and possesses a small pro-
tuberance clearly visible in the vertical and lateral views.
As in typical X. controversion, single spines are frequently
replaced by a pair.
It should be compared with X. tetraeavthum Turner
('Freshw. Alg. E. India/ 1893, p. 101, t. 13, f. 29), from
which it differs in its hexagonal semicells, closed sinus, and
longer spines.
5. Xanthidium Smithii Arch.
(PI. CVIII, figs. 1-4; PI. CXI, fig. 10.)
Xanthidium Smithii Arch, in Proc. Dubl. Nat. Hist. Soc. iii, 1860, p. 51,
t. i, f. 10-12 ; in Q. J. Micr. Sci. 1860, p. 238, t. 11 ; in Pritch. Infus.
1861, p. 736; Eabenh. Flor. Europ. Alg. Ill, 1868, p. 224; Cooke,
Brit, Desm. 1887, p. 133, t. 45, f . 4 ; West, Alg. W. Ireland, 1S92, p.
166; Eoy & Biss. Scott. Desm. 1893, p. 245; W. & G. S. West, Notes
Alg-. Ill, 1903, p. 74.
Arthrodesmus octocornis Ehr. var. major Eoy & Biss. Scott. Desm. 1894,
t. 2, f. 20 [not Ealfs].
Cells small, deeply constricted, sinus open and
acute-angled with a rounded apex ; semicells rect-
angular-trapeziform, basal and apical angles rounded,
sides and apex very slightly concave (or almost
straight), each angle furnished with a pair of simple,
straight, and fairly long spines, with a small thickened
area in the centre of the semicell. Side view of semi-
cell circular, with a small protuberance at the middle
on each side, and with a pair of diverging spines at
the apex. Vertical view elliptic-rhomboid, with a
small rounded protuberance at the middle on each
side, and with a pair of diverging spines at each pole.
Chloroplasts ?
Zygospore globose, furnished with long, simple,
acute spines (about 7 visible at the actual margin),
each arising from a widely conical base.
f>2 BRITISH DESMII>IA<'l<:/i:.
Length without spines 21-30 p; breadth without
spines l(.»-28/x; length of* spines 6'5-8/u,; breadth of
isthmus 8-11 /x; thickness 12-16 /a; diam. zjgosp.
without spines 25-26 /a, with spines 66-68 /x.
England. — Near Bowness, Westmoreland (Bissett).
Walks. — Moel Siabod, Carnarvonshire ! Rlios Goch
Bog, Radnorshire !
Scotland. — Cammie in Strachan, Kincardine; zygos-
pore from near Aboyne, Aberdeen (Boy fy Bissett).
(xarynahine, Lewis, and Harris, Outer Hebrides !
Ireland. — Lakes between Clifden and Roundstone,
Galway! Cromagloun, and Tore Mountain, Kerry!
.Castletown, Cork!
Geogr. Distribution. — Patagonia.
X. Smith ii is a veryrare species which apparently only occurs
in abundance in a few districts in North Wales, the west of
Ireland, and the Outer Hebrides. It is one of the most
distinctive species of the genus and cannot well be confounded
with any other.
Yar. majus (Ralfs) nob. (PI. CYIII, fig. 5.)
Xanthidium ? octocomc (Ehrenb.) Ralfs var. major Ralfs, Brit. Desm.
1848, p. 116, t. 20, f. 2 f-A.
Arthrodesmus octocornis Ehrenb. var. major Cooke, Brit. Desm. 1887, p.
135, t. 47, f. 2 a. b, c, f, g ; Lund. Desm. Snec. 1871, p. 56; Nordst.
Norges. Desm. 1873, p". 25; De Toni, Syll. Alg. 1889, p. 1063; Roy &
Biss. Scott. Desm. 1894, p. 41 [but not t. 2, f. 20] ; Eichler in Pamiet,
Fizyograf. Akad. Umiej. Krakow, xiii, 1895, p. 60.
Slightly larger than the type, sides and apex of
snuicells rather more concave, spines often shorter
and stouter, from one to three inserted at each angle,
and often of different lengths ; central area of semicell
slightly thickened, but not protuberant.
Length without spines 26-3(5 fx ; breadth without
spines 27-32 /a ; breadth of isthmus 9-12 [i; thickness
12-16 jjl; length of spines 4-95 /x.
Walks. — Dolgelly, Merioneth (Ralfs).
Scotland. — Orkneys, Sutherland!, Ross, Inverness,
Aberdeen, Kincardine, Forfar, Perth, and Argyll
(Boy Sf Bissett).
XANTHIDIUM. 63
Ireland. — Cromagloun, Kerry !
Geoqr. Distribution. — Norway. Sweden. Poland.
This variety is not quite so rare as the type, but is very local
and confined to the rich bogs of the old formations. It is
easily distinguished by its stouter habit and thicker spines,
which are somewhat variable. Two is the usual number
at each angle of the semicell, but the basal angles are fre-
quently furnished with three, and more rarely with only one.
It seems to us an error of judgment to place this variety
under Arthrodesmus octocornis notwithstanding the fact that
the semicells are identical in outward form. The spines are
usually in pairs, and the vertical view shows that the central
area of the semicell is very slightly thickened. The association
of these characters is clear evidence that this plant should be
placed in the genus Xanthidium.
There seems little doubt that the Desmid described by
Reinsch as Xanthidium bicomutum should be relegated to
this variety. It might be regarded as :
Forma minor [= Xanthidium bicomutum Reinsch, Spec.
Gen. Alg. 1867, p. 119, t. 20 A III, f. 1-6; Didymidium
[Xanthidium) bicomutum Reinsch, Algenfi. Frank. 1867, p.
128, t. 9, f. 7; Arthrodesmus ? bicornutus De Tom, Svll. Alg.
1889, p. 1064] .
Var. collum West. (PL CVIII, fig. 6.)
X. Smlthii var. collum West. Alg. W. Ireland, 1892, p. 166, t. 22, f. 5.
Eacli superior angle of the semicell with three
spines ; isthmus elongated so that the sinus is wide
and ronnded-quadrate ; central protuberance of semi-
cell rather prominent and a little irregular.
Length without spines 30 /x ; breadth without spines
25 (jl; breadth of isthmus 9 fx; thickness 15/x; length
of spines 5-7 '5 jx.
Ireland. — Cromagloun, Kerry !
6. Xanthidium antilopseum (Breb.) Kiitz.
(PI. CVIII, figs. 7-18.)
? Xanthidium fasciculatum Ehrenb. var. polygonum Ehrenb. Infus. 1838,
p. 148, t. 10, f. 24a [description and figure imperfect].
Heterocarpella antilopaea Breb. in Cheval. Des. nricroscop. et de leur usage,
Paris, 1839, p. 272.
? Cosmarium antilopseum Breb. in Menegh. Synops. Desm. 1S40, p. 218.
64 BRITISH DESMIDIAC'E.E.
Xaniltidium fascimihttum Ehrenb. a Ralis in Ann. Mag. Nat. Hist. xiv.
1845, p. 466, t. 12, f. 3 a-d; Brit. Desm. 1848, p. 114, t. 20, f. 1; De
Not. Desm. Ital. 1867, t, 4, f. 36; Nordst. Desm. Brasil. 1870, p. 230;
Delp. Desm. subalp. 1877, p. 168, t. 13, f. 20-22; Tnrn. Alg. Strensall
Common, 1883, f. 12 ; Wolle, Desm. U. S. 1884, p. 93, t. 22, f. 4, 5.
X. polygonum Hass. Brit. Freshw. Alg. 1845, p. 360, t. 89, f. 4 [figure
pooir .
X. antilopseum (Breb.) Kiitz. Spec. Alg. 1849, p. 177; Breb. Liste Desm.
1856, p. 134 ; Lund. Desm. Suec. 1871, p. 75 .- Kirchn. Alg. Schles. 1878,
p. 155 ; Wolle, Desm. U. S. 1884, p. 94, t. 23. f . 1, 2 ; Cooke, Brit. Desm.
1887, p. 132, t. 46, f. 2 ; Hanssr. Prodr. Algenfl. Bohm. 1888, p. 192 ; De
Toni, Svll. Alg. 1889, p. 920; "West, Alg. N. Torks. 1889, p. 293 ; Alg.
N. Wales, 1890, p 291 ; Alg. W. Ireland, 1892, p. 165 ; Alg. Engl. Lake
District, 1892, p. 730 ; Liitkem. Desm. Attersees, 1893, p. 547 : Roy &
Biss. Scott. Desm. 1893, p. 244; 1894, t. 3, f. 13; W. and G. S. West,
New and Int. Freshw. Alg. 1896, p. 156; Alg. S. England, 1897, p. 484;
Alga-fl. Torks. 1900, p. 67 ; Borg. Freshw. Alg. Faeroes, 1901, p. 229;
W. & G. S. West, Alg. N. Ireland, 1902, p. 31 ; Scott. Freshw. Plankton,
I. 1903, p. 527 ; Hirn, Desm. Finland, 1903, p. 23, t. 2, f. 33 ; W. & G. S.
West, Freshw. Alg. Orkneys and Shetlands, 1905, p. 23; Further Contrib.
Freshw. Plankton Scott. Lochs, 1905, p. 72 ; Comp. Study Plankton
Irish Lakes, 1906, p. 85 ; Borge, Beitrage Alg. Sclrweden, 1906, p. 28 ;
Teodoresco, Mater, flor. alg. Eouman. 1907, p. 182 ; W. & G. S. West,
Brit. Freshw. Phytoplankton, etc., 1909, p. 180; Phytoplankton Engl.
Lake District, 1909, p. 138.
X antilopseum var. hirsutum Gay, Monogr. loc. Conj. Montpellier, 18S4, p.
77 ; Note Conj. du midi de France, 1884, p. 340.
X. spinulosum Benn. Freshw. Alg. Engl. Lake Distr. 1886, p. 10, t. 2, f. 17
[figure erroneous] ; Cooke, Brit. Desm. 1886, p. 132, t. 46, f. 4; De Toni,
Syll. Alg. 1889, p. 928.
X. initibqiwum var. ornatum Anderss. Sverig. Chlor. 1890, p. 13, t. 1, f. 6.
A", fasciculatum var. ornatum Schmidle, Beitr. Algenfl. Schwarzwald. u.
Rheineb. 1893, p. 94, t. 4, f. 6.
X. antilopseum var. fasciculoides Liitkem. Desm. Attersees, 1893, p. 547
[=X. fasciculatum, Ralfs, 1848, t. 20, f. \b ; X. antilopseum (Breb.) Kiitz.
in Wittr. & Nordst. Alg. Exsicc. No. 574.]
X. antilopseum var. Schmidlei Borge in Nuova Notarisia, 1895, vi, p. 25.
Cells of medium size, about as long as broad (without
spines), deeply constricted, sinus somewhat variable
in depth (according to form of basal half of semicell),
shortly linear with a slightly dilated extremity ; semi-
cells subelliptic-hexagonal, all the angles very slightly
rounded, sides and apex usually straight, each of the
four exposed angles furnished with a pair of simple,
straight or slightly curved, fairly long spines, central
area of moderate size, o-enerallv round (more rarely
elliptic), thickened and variously scrobiculated. Side
view of semicell circular or subcircular, with a slight
thickening at each side, and a pair of diverging spines
on the apical margin. Vertical view elliptic, with a
slight thickening (often somewhat protuberant) at the
XANTHIDIUM. 65
middle on each side, and with a pair of slightly
divergent spines on each polar margin. Cell-wall
finely punctate. Chloroplasts generally parietal, four
in each seraicell, each with one, or more rarely with
two, pyrenoicls ; sometimes irregular, and not infre-
quently wholly axile.
Zygospore globose, furnished with long, slender
spines, slightly widened at the base, and shortly
bifurcate at the apex.
Length without spines 42-76 /x, with spines 54-
114 /x; breadth without spines 42-72 /x, with spines
57-108 n; breadth of isthmus 14'5-26 fx ; thickness
21-37 /x; diam. zygosp. without spines 45-58 /x, with
spines 80-98 /x.
England. — Cumberland ! Westmoreland ! (Ralfs).
Lancashire! (Ralfs). W. and N. Yorks ! Cheshire
(Ralfs). Essex ! Buckinghamshire ! Surrey (with
zygospores from Thursley Common)! Sussex (Ralfs).
Hants! {Rolfs). Wilts! Devon! Cornwall! (Ralfs).
Plankton of Buttermere, Ennerdale Water, Brothers'
Water, Hayes Water, Hawes Water, Grasmere, Easdale
Tarn, and Stickle Tarn, in the English Lake District !
Wales. — Fairly general ! Plankton of many Welsh
lakes !
Scotland. — Common! Zygospores from Loch Inver,
Sutherland, and Logie Coldstone, Aberdeen (Roy and
Bissett). Common in the plankton.
Ireland. — Donegal ! Galway (zygospores from Bally -
nahinch)! Kerry! Dublin and Wicklow (Archer).
Armagh ! Down ! Plankton of the lakes of Galway
and Kerry. Lough Neagh !
Geogr. Distribution. — France. Germany. Austria
and Galicia. Roumania. Norway (and Finmark).
Sweden. Bornholm. Finland. N. Russia. Faeroes.
Siberia. Mongolia, Japan. N. India. Central
Africa (var.). United States. W. Indies (var.). Brazil.
Paraguay.
XanthicUum antilo'p&um is the most frequent British species
-of the genus. It rarely occurs in bogs, having a decided pre-
VOL. IV. 5
C)6 BRITISH DESMIDIACK.T,.
ference for the boggy margins of large pools and lakes, and
both the typical form and several varieties are regular con-
stituents of the lake-plankton.
The hexagonal semicells with four pairs of spines are so
characteristic that this species in its t}rpical form is not
easily confounded with any other. The scrobiculations of the
central area are exceedingly variable as can be seen bv a
scrutiny of figs. 7, 8, 10-18, on PI. OVIII.
Within certain limits the shape of the semicells is variable,
causing a corresponding variation in the length of the sinus
(compare figs. 7 and 8 on PI. CVIII). The spines are
somewhat variable both in length and acuteness, and they
may be straight or slightly curved, or even somewhat
recurved.
The form with the straight and less acute spines has been
named " var. fasciculoides " by Lutkemuller, but we hesitate
to separate this form as a distinct variety as the spines are
so variable in length and relative curvature, and the zygospores
of the straight-spined and curved-spined forms are exactly
alike.
Borgesen, and also Larsen, have questioned the distinction
between X. antilopseum and X.fasciculatum, but judging- from
the remarks made by Larsen in his 'Freshw. Alg. E.
Greenland/ 1904, p. 101, that author does not realize the
characters of X. fasciculatum. The form he figures is one of
the deformed specimens of X. antilopseum which are not un-
common in cold northern latitudes and in the plankton of
cold lakes.
We have recognized six distinct varieties of X. antilopseum
in the British Islands, but the two characteristic American
varieties, var. minneapoliense YVolle and var. canadense Joshua,
in which a large spine occurs on, or in relation to, the central
protuberance, are not known to occur in Britain.
X. antilopseum, var. incertum Schmidle ('Alg. aus Xyassa-
See/ 1903, p. 71, t. 2, f. 5) is not correctly placed under
X. antilopseum, and should be relegated elsewhere.
Var. triquetrum Lund. (PI. CIX, fig. 1.)
X. antilopfp.um var. triquetrum Lmnd. Desm. Suec. 1871, p. 76, t. 5, f. 1;
Wolle, Desm. U. S. 18S4, p. 94, t. 22, f. 1-3 [figures poor] ; De Toni,
Syll. Alg. 1889, p. 921 ; Borge, Chlor. Norska Finmark. 1892, p. 8 ; W.
& G-. 8. West, Phytoplankton Engl. Lake District, 1909, p. 138.
X. antilopseum var. fasciculoides Liitkem. forma triquetra Liitkem. Desm.
Attersees, 1893, p. .j47.
A large variety ; vertical view triangular, with
XANTHIDIUM. 67
straight or very faintly convex sides, each of which
is slightly thickened in the middle, angles wide and
emarginate, furnished witli a pair of stout spines,
and within each angle with a similar pair of stout
spines. Each semicell with 6 parietal chloroplasts.
Length without spines 81-90 jx, with spines 116-
126 fx; breadth without spines 65-82 [x, with spines
97-125 /x ; breadth of isthmus 26-28'5ja.
Exglaxd. — Plankton of Brothers' Water, Grasmere,
and Easdale Tarn in the English Lake District!
Geogr. Distribution. — Sweden. Finmark in Nor-
way. Austria and Galicia. Brazil (forma).
In the British Islands we have only observed this variety
in the plankton. Liitkemuller has recorded smaller forms
from Austria; length without spines 71//, with spines 90 ju ;
breadth without spines 55 fi, with spines 84//.
Var. polymazum Nordst. (PL CVIII, fig. 19.)
X. antilopxum var. polymazum Nordst. Norges Desm. 1873, p. 38, t. I,
f. 19 ; Wolle, Desm. U. S. 1884, p. 94, t. 23, f. 3, 4 [figures poor] ;
Borg. Bornholm Desm.-fl. 1889, p. 149 ; W, & G. S. West, Further
Contrib. Freshw. Plankton Scott. Lochs, 1905, p. 485 ; Cushman in
Rhodora, vii, 1905, p. 259 ; W. & G. S. West, Brit. Freshw. Phyto-
plankton, etc., 1909, p. 180.
Each semicell with a semicircular series of large
rounded granules above the central protuberance.
Length without spines 46-68 /x, with spines 62-85 fx ;
breadth without spines 45-62 [x, with spines 58-76*5 fx ;
breadth of isthmus 12-16 [x; thickness 28-33 /x.
Scotland. — Plankton of Loch Ghriar, Sutherland;
Loch Fadaghoda, Lewis ; and Loch nan Eun, N. Uist,
Outer Hebrides !
Geogr. Distribution. — Norway. Bornholm. United
States.
This is a rare variety in the British Islands and one that
we have found only in the plankton. In the original figure
given by Nordstedt there is an incipient third spine between
the pair at each lateral angle of the semicells, and we often
find this spine fully developed so that there are three equal
spines at each lateral angle (consult PI. CIX, fig. 2).
08 BKITISH DESMIDIACE.E.
Turner lias described a ' forma major ' of this variety from
northern India.
Var. lseve Schmidle. (PI. CIX, fig. 3.)
X. antilopseum var. lseve Schmidle, Beitr. Algenfl. Schwarzwald. u. Rheineb.
1893, p. 94, t. 4, f. 7 ; W. & G. S. West, Further Contrib. Freshw.
Plankton Scott. Lochs, 1905, p. 485 ; Brit. Freshw. Phytoplankton, etc,
1909, p. 180.
A rather large variety in which the semicells are
entirely destitute of a thickened or scrobiculated
central area. Cell- wall sometimes perfectly smooth,
at other times finely punctate.
Length without spines 79-90 fx, with spines 96-
121 jx; breadth without spines 62-79//,, with spines
88-116 fx; breadth of isthmus 20-35 /z.
Scotland. — Plankton of Loch Fadaghoda, Lewis,
Outer Hebrides !
Ireland. — Bog W. of Lough Neagh, Londonderry !
Geogr. Distribution. — Germany.
A form of this variety with a more or less irregular
disposition of the spines was abundant in Derrycrow Bog,
near Lurgan, in the north-east of Ireland. This we have
named ' forma irregularis ' (W. & Gr. S. West, * New Brit.
Freshw. Alg. ; 1894, p. 8, t. 2, f. 44) ; length without spines
80-82 fi, with spines 105-115 n ; breadth without spines 62-63 fi,
with spines 85-100 w ; breadth of isthmus 21-25 /x. (PI. CIX,
fig. 4.)
The form described hy Lutkemuller (' Desm. Attersees/
1893, p. 548) as "var. fasciculoides forma inevolutum" is
probably one of the forms of this variety.
Var. oligacanthum Schmidle. (PI. CIX, fig. 5.)
X. antilopseum var. oligacanthum Schmidle, Chlorophy.-Fl. Torfstiche
Vimheim, 1894, p. T.0, t. 7, f. 10.
Semicells more elliptical than in the type, with
only one spine at each of the upper angles, and with
no differentiated central area.
Length without spines 46-50 ll ; breadth without
spines 46-58 fx.
Geogr. Distribution. — Germany.
XANTHIDIUM. 69
From Lough Anna and near Lough Magrath in Donegal,
Ireland, a form of X. antilopasum was observed which we
have referred to this variety as "forma spinis longioribus ;
tumore centrali prominenti et supra tumorem cum scrobiculis
numerosis" (vide W. & G. S. West, ' Alg. N. Ireland,' 1902,
p. 31). Length without spines 39//, with spines 54 li; breadth
without spines 41 ii, with spines 65 fx ; breadth of isthmus
12-5 fx ; thickness 25 fi. (PL CIX,. fig. 6.)
Var. hebridarum W. & G. S. West. (PI. CIX, fig. 7 ;
PL CX, figs. 1, 2.)
X. antilopseum var. hebridarum W. & Gr. S.West, Further Contrib. Fresh n\
Plankton Scott. Lochs, 1905, p. 5C0, t. 7, f. 21 ; Comp. Study Plankton
Irish Lakes, 1906, p. 85 ; British Freshw. Phytoplankton, etc., 1909,
p. 180.
Semicells with three spines on each lateral margin,
all of which are disposed in a median vertical plane,
one spine only inserted at the upper angles, the other
two approximated near the lateral angles ; central
area consisting of a small obtusely mamillate pro-
tuberance around which is grouped in various ways a
number of minute scrobiculations.
Length without spines 46-50 /a, with spines 61—71 //, ;
breadth without spines 42-49 fx, with spines 69-82 jx ;
breadth of isthmus 12-14 ix; thickness 31 //..
Scotland. — Plankton of two lochs in Inverness, two
in Ross, three in Sutherland, six in Lewis, Outer
Hebrides, and three in Harris, Outer Hebrides !
Ireland. — Plankton of several small lakes between
Clifden and Rouudstone, Galway !
Instead of the normal pair of spines at each upper angle
of the semicells, there is in this variety only a single spine,
and the pair of spines which should be attached side by side
at the lateral angles ai'e here separated some distance apart,
and placed more or less vertically over each other. The
semicells are therefore not so angular as in typical X. anti-
lopveum. The length of the spines is variable, and examples
are sometimes met with in which the spines are to some
extent reduced and not strictly disposed in one vertical plane.
(vide PL CIX, fig. 7.)
70 BRITISH DESMIDIACE.E.
Var. depauperatum W. & G. S. West. (PI. CX,
figs. 3-7.)
X. antilopmum forma W. & G. S. West, Scott. Freshw. Plankton, I. 1903,
p. 539, t. 16, f. 1.
X. antilopseum var. depauperatum W. & G. S. West, Freshw. Alg. Orkneys
and Shetlands, 1905, p. 23, t. 1, f. 15, 16; Further Contrib. Freshw.
Plankton Scott. Lochs, 1905, p. 485 ; Comp. Study Plankton Irish
Lakes, 1906, p. 85 ; Brit. Freshw. Phytoplankton, etc., 1909, p. 180 ;
Phytoplankton Engl. Lake District, 1909, p. 138.
Semicells slightly inflated, with the lateral angles
very obtuse and generally very slightly truncate ;
spines 1-3 (more rarely 4) on each lateral margin,
very short, of unequal length, and irregularly disposed ;
central area of normal size and closely scrobiculated,
or with only one ring of scrobiculations.
Length without spines 46-55*5 /x ; breadth without
spines 43-50 jx; length of spines 2-10*5 [x; breadth
of isthmus 9*5-14 /x.
England. — Plankton of Buttermere, Crummock
Water, and Ennerdale Water, Cumberland ! ; and of
Red Tarn, Grasmere, and Easdale Tarn, Westmore-
land!
Wales. — Plankton of several Welsh lakes !
Scotland. — Plankton of Lochs Griama and nan
Cuinne, Sutherland ; of Loch na Cloiche Sgoilt, Inver-
ness ; and of Loch Tay, Perth ! Plankton of lakes in
Orkneys and Shetlands !
Ireland. — Plankton of lakes of Galway and Kerry !
In this variety the semicells are less hexagonal and more
inflated than in the typical form. The spines are fewer, thinner,
of unequal length, and show much irregularity in their dis-
position. In fact, the number and disposition of the spines is
generally quite different on the two semicells of the same
individual. It is sometimes a distinctive feature of the lake-
plankton.
7. Xanthidium cristatum Breb.
(PI. CX, figs. 8, 9; PI. CXI, fig. 1.)
Xanthidium cristatum Breb. in Ralfs' Brit. Desm. 1848, p. 115, t. 19, f. 3
a-c ; Arch, in Pritch. Infus. 1861, p. 736, t. 2, f. 18, 23 ; Eabenh.
Flor. Europ. Algar. Ill, 1868, p. 224; Lund. Desm. Suec. 1871, p. 76;
Reinsch, Contrib. Alg. et Fung. 1875, p. 92, t. 16, f. 13 ; Kirchn. Alg.
XANTHIDIUM. 71
Schles. 1878, p. 155 ; Wolle, Desm. U. S. 1884, p. 93, t. 21, f. 6, and 7 ? ;
€ooke, Brit. Desm. 1887, p. 133, t. 46, f. 3 ; Boldt, Desmid. Gronland^
1888, p. 31 ; De Toni, Syll. Alg. 18S9, p. 923 ; Heimerl, Desm. alp.
189L, p. 595 ; Hansg. Prodr. Algenfl. Bohm. 1892, p. 252 ; West, Alg. W.
Ireland, 1892, p. 165 ; Alg. Engl. Lake Distr. 1892, p. 730 ; Eoy &°Biss.
Scott. Desm 1893, p. 244; Nordst. Index Desmid. 1896, p. 89; W. & G.
S. West, Alg. S. England, 1897, p. 484 ; Alga-fl. Yorks. 190U, p. 67 ; Scott.
Freshw. Plankton, I. 1903, p. 527 ; Larsen, Freshw. Alg. E. Greenland,
1904, p. 101; W. & G. S. West, Further Contrib. Freshw. Plankton
Scott. Lochs, 1905, p. 485 ; Comp. Study Plankton Irish Lakes, 1906,
p. 85 ; Borge, Beitrag e Alg. Schweden, 1903, p. 28 ; Larsen, Ferskvand-
salg. Vest-Gr6nl. 1907, p. 354 ; W. & G. S. West, Brit, Freshw. Phyto-
plankton, etc. 1909, p. 180.
Didymidium (Xanthidium) cristatum (Breb.) Beinsch, Algenfl. Frank. 1867,
p. 127.
Xanthidium cristatum var. reniforme Cooke, Brit. Desm. 1887, 133.
Holocanihum cristatum (Breb.) Wille in Engler A: Prantl, Naturl. Pflan-
zenfam. 1890, pp. 11, 12 (c. fig. 7 D).
Cells of medium size, a little longer than broad
(without spines), deeply constricted, sinus rather
variable, sometimes narrowly linear with a dilated ex-
tremity and sometimes slightly open; semicells
trapeziform-subsemicircular, with a broad, subreni-
form, flat, or somewhat convex base, and with a basal,
lateral and apical angle on each side, apex truncate
and generally straight, basal angles furnished with a
single slightly convergent spine, lateral and apical
angles each furnished with a pair of divergent spines,
spines all simple and straight, central area differen-
tiated into a small thickened protuberance, generally
with a slight vertical elongation. Side view of semi-
cell circular, with a more or less flattened protuberance
at the middle on each side, and with a pair of divergent
spines at the apical margin. Vertical view elliptic,
with a small protuberance at the middle on each side,
and three slightly divergent spines at each pole. Cell-
wall delicately punctate.
Zygospore globose, furnished with numerous, elon-
gated, stout spines which are very slightly emarginate
at the apex.
Length without spines 44-55 /x, with spines 60-77 /x ;
breadth without spines 34*5-48 fx, with spines 48-68 jx ;
breadth of isthmus 13-15*5 fi; thickness 25-32*5 {x ;
cliam. zygosp. without spines 48*5-51 /x, length of
spines 15-16 fx.
72 BRITISH HKSMIDIACEJE.
England. — Westmoreland ! (Balfs). Hawkshead,
I jancashire ! N. and E. Yorks ! Warwickshire ( Wills).
Sussex (Balfs). Hants! Cornwall! (Ralfs).
Wales.— Capel Curig ! (Coolce Sf Wills) and Moel
Siabod, Carnarvonshire !
Scotland. — Sutherland ! , Ross, Inverness !, Aberdeen,
Kincardine, Forfar, Perth ! (Boy Sf Bissett). Plankton
of Lochs Fadaghoda, an Sgath, Langabhat, and an
Tomain, Lewis, Outer Hebrides ; and of Loch nan Eun,
N. Uist, Outer Hebrides !
Ieeland. — Mayo ! Gal way ! Kerry ! Dublin and
Wicklow (Archer). Plankton of small lakes in Galway !
Geogr. Distribution. — France. Germany. Austria
(var.) and Galicia. Hungary. Norway. Sweden.
Denmark. Finland. Poland. S. Russia. Green-
land. N. India, E. Africa (var.). United States.
Brazil.
The distinguishing feature of X. cristatum is the solitary
spine, in a median plane, at each basal angle of the semicell.
The central area is also small, protuberant, and in most type
specimens is devoid of either scrobiculations or granules. It
is a much less frequent species than X. antilopseum, and never
occurs in such abundance.
Forma angulata West. (PI. CX, fig. 10.)
X. cristatum forma angulatum West, Alg. W. Ireland, 1S92, p. 105, t. 22,
f. 3.
Semicells more angular; cell-wall distinctly punctate.
Length without spines 51^, with spines 67 n~,
breadth without spines 40-48 /«, with spines 62 p ;
breadth of isthmus 12*5 /» ; thickness 22'5/n.
Ireland. — Lough Aunierin, Galway.
Var. leiodermum (Roy & Biss.) Turner. (PI. CX,
eg. ii.)
Xanthidium leiodermum Roy & Biss. Japan. Desm. 1886, p. 2-AO, t. 268,
f. 11.
X. cristatum vav. glabrum Lagerh. Bidr. Amerik. Desm.-fl. p. 245.
X. glabrum Lagerh. Krit. Bemerk. Desm. 1887, p. 539; De Toni, Syll. Alg.
1889, p. 930.
X. cristatum var. leiodermum (Rov & Biss.) Turn. Freshw. Alg. E. India,
1893, p. 99, t. 12, f. 33.
XANTHIDIUM. 73
Central area not protuberant, slightly thickened
and sometimes of a yellow colour: cell-wall smooth.
Length without spines 48-54 /x, with spines 65-74 [x ;
breadth without spines 86-39 p, with spines 53-55 /x ;
breadth of isthmus 11-13 /x ; thickness 25-80 /a.
England. — Bowness, Westmoreland !
Geogr. Distribution. — India. Japan. United States.
Var. spinuliferum West. (PI. CX, fig. 12.)
X. cristatum var. spinuliferum West, Alg. N. Wales, 1890, p. 291, t. 5, f. 21.
Semicells furnished with 4 or 5 additional spines
irregularly placed just within the margin.
Length without spines 45 tt, with spines 58 /x;
breadth without spines 36 /x, with spines 48 /x.
Wales. — Cap el Curig, Carnarvonshire !
Ireland. — Lough Aunierin, Galway !
Var. uncinatum Breb. (PL CXI, figs. 2-4.)
'/ Xanthidium bisenarium Ehrenb. in Phvsik. Abb. Preuss. Ak. d. wiss. zu
Berlin, 1841 [1843], pp. 334, 339, 390, 426 [= Euastrum No. 11 Bailey
in Amer. Journ. of Science and Arts, iv, 1841, p. 296, t. 3, f. 13] ; Eabenh.
Flor. Europ. Alg. Ill, 1868, p. 224.
X. cristatum var. uncinatum Breb. in Ralfs' Brit. Desm. 1848, p. 115, 1. 19,
f . 3 d-f ; Wille, Sydamerik. Algfl. 1884, p. 18 ; Cooke, Brit. Desm.
1887, p. 133 ; De Toni, Syll. Alg. 1889, p. 923 ; Borg. Desm. Hrasil. 189i '.
p. 44 ; West, Alg. W. Ireland, 1892, p. 165 ; Alg. Engl. Lake Distr.
1892, p. 730 ; Roy & Biss. Scott. Desm. 1893, p. 244; W. & G. S. West,
Some N. Amer. Desm. 1896, p. 253. fig. xylogr. 3; Him, Desm. Finland.
1903, p. 23, t. 2, f. 34; W. & G. S. West, Brit. Freshw. Phytoplankton,
etc., 1909, p. 180 ; Phytoplankton Engl. Lake Distr. 1909, p. 138.
X. bisenarium [forma typica'] Turner, Freshw. Alg. E. India, 1893, p. 99.
t. 12. f . 30 ; W. & G. S. West, Alg. N. Ireland, 1902, p. 30.
Cells larger and proportionately a little longer; semi-
cells widely subpyramidate with truncate apices, with
the 4 pairs of spines directed more vertically upwards ;
all the spines (single and paired) curved or slightly
recurved, often dilated at the base ; central area
slightly protuberant and furnished with a ring of 8-12
granules surrounding 3-5 central ones, more rarely
with a much more irregular granulation.
Length without spines 55-74 /x, with spines 73-91 /x ;
74 BRITISH DESMIDJACEiE.
breadth without spines 40-64 fx, Avith spines 55-83
breadth of isthmus 12-20 /x; thickness 31-36 jx.
England. — Near Bowness, Westmoreland ! (Bissett).
Hawkshead and Hampsfell, Lancashire ! In the
plankton of Derwent Water, Cumberland !
Scotland. — Common (Boy Sf Bissett). Sutherland!
Ireland. — Ballynahinch, Gralway ! Lough Gartan,
Donegal !
Geor/r. Distribution. — France. Germany. Norway.
Sweden. Central China. N. India. United States.
This distinctive variety is larger than typical X. cristatum,
Avith more pyramidate semicells and a granulate central
protuberance. The spines are invariably curved, and often
recurved, and all the paired spines are turned in a direction
more nearly parallel with the longitudinal axis.
The granulation of the central area is variable, and some-
times of a very irregular character. We have previously
figured some of these variations as observed in American
specimens (vide W. & Gr. S. West, ' Some N. Amer. Desm.'
1896, fig. 3 on p. 253). Messrs. Roy and Bissett mention a
curious form from Loch Ruthven, Inverness, " in which the
central circlet of granules is replaced by a short, stout, blunt
spine."
In many specimens the basal part of the spines is distinctly
dilated, and in some this character is so far extended that
each of the paired spines is inserted upon a mamillate pro-
tuberance of the cell. This form, which we have observed
from the United States, we have named "var. uncinatum forma
mucronata" (West, ' Freshw. Alg. Maine 11/ 1891, p. 355, t.
315, f. 11).
Var. Delpontii Roy & Biss. (PL CXI, fig. 5.)
X. cristatum as described and figured by Delponte, Desm. subalp. 1877,
p. 75, t, 14, f. 1-11.
X. cristatum var. Delpontei Roy & Biss. Scott. Desm. 1893, p. 244.
Cells proportionately wider than in var. unci not inn ;
semicells subsemicircular with stout spines ; central
area large and furnished with large granules, one
in the centre surrounded by an inner circle of 6 or 7
and an outer circle of 10-12.
Length without spines 54-01 /<, with spines 86-95 /x ;
XANTHIDIUM. 75
breadth without spines 53-56 /*, with spines 76-88 /x ;
breadth of isthmus 13-16/z; thickness 35-39 ft.
Scotland. — Scolty, Kincardine (Boy Sf Bissett).
Geogr. Distribution. — Italy.
8. Xanthidium fasciculatum Ehrenb.
(PL CXI, figs. 6-8.)
Xanthidium fasciculatum Ehrenb. Infus. 1838, p. 147, t. 10, f. 24 b
[figure bad] ; Arch, in Pritch. Infus. 1861, p. 736 [in part] ; Arch, in
Q. J. Micr. Sci. vi, 1866, p. 273 ; Raberh. Flor. Europ. Alg. Ill, 1868 p.
223; Lund. Desin. Suec. 1871, p. 75; Lagerh. Bidr. till Aiuerik. Desm.-fl.
1886, p. 245 ; Cooke, Brit. Desm. 1887, p. 131, t. 46, f. 1 ; Hansg. Prodr.
Algenfl. Hohni. 1888, p. 192 ; De Toni, Syll. Alg. 1889, p. 918 ; Heimerl,
Desm. alp. 1891, p. 595; West, Alg. W. Ireland, 1892, p. 165; Turn.
Freshw. Alg. E. India, 1893, p. 100, t. 12, f. 34 [figure defective] ; Eoy
& Biss. Scott. Desm. 1893, p. 245 ; Nordst. Index Desmid. 1896, p. 122 ;
W. & G. S. West, Alg. S. England, 1897, p. 484; Alga-fl. Yorks. 1900,
p. 68 ; ? Biirg. Freshw. Alg. Faroe's, 1901, p. 229 ; W. & G. S. West, Alg.
N. Ireland, 1902, p. 30;. Freshw. Alg. Orkneys and Shetlands, 1905,
p. 23 ; Further Contrib. Freshw. Plankton Scott. Lochs, 1905, p. 485 ;
Korge, Beitrage Alg. Schweden, 1906, p. 28 ; W. & G. S. West, Brit.
Freshw. Phytoplankton, etc., 1909, p. 180.
X. fasciculatum var. polygonum Ralfs in Ann. Mag. Nat. Hist. 1845, p. 466,
t. 12, f. 3e ; Brit. Desm. 1848, p. 114, t. 19, f. 4.
Euastrum fasciculatum Kiitz. Phyc. german. 1845, p. 137.
Bidymidium (Xanthidium) fasciculatum Eeinsch, Algenfl. Frank. 1867, p.
126.
X. fasciculatum var. ornatum Nordst. Desmid. Gronland, 1885, p. 12, t. 7,
f. 10 ; Hirn, Desm. Finland, 1903, p. 23 ; Borge, Beitrage Alg. Schweden,
1906, p. 28.
Holacanthum fasciculatum Franze in Oesterr. botan. Zeitschr. 1893, p. 384.
Cells of medium size, about as long as broad (without
the spines), deeply constricted, sinus linear, sometimes
with a dilated extremity; semicells angular-reniform,
margin with six equidistant pairs of simple and often
rather short spines, apex subtruncate, central area
rather small and slightly protuberant, with a ring of
7-10 granules around a central group of 2 or 3 (rarely
smooth ?). Side view of semicell subcircular, with a
slight protuberance at the middle on each side, and a
pair of divergent spines at the apical margin. Vertical
view elliptic, with a slight protuberance at the middle
on each side, and a pair of divergent spines at each
pole.
Zygospore globose, furnished with long, attenuated
spines which are bifid at the apex.
76 BRITISH DESMIDIACEJE.
Length without spines 44-00 fx, with spines 65-74 jx;
breadth without spines 44-59 /x, with spines (32-72 /* ;
breadth of isthmus 12-21/1 ; thickness 31-40 /i.
England. —Westmoreland (Bissett). Strensall and
Pilmoor, N. Yorks ! Austwick Moss, W. Yorks I
Surrey! Cornwall! (Balfs).
Wales. — Capel Gurig, Carnarvonshire ! (Cooke Sf
1 1 tils) . Dolgell v, Merionethshire (Rolfs) .
Scotland. — Sutherland!, Ross, Aberdeen, Kincar-
dine, Forfar, Perth, Argyll, Fife (Roy Sf Bissett).
Plankton of Loch Cuthaig, Lewis, Outer Hebrides I
Hoy, Orkneys !
Ireland. — Lough Anna, Donegal ! Deiryclare
Lough, Ballynahinch, and lakes near Recess, Galway !
Dublin and Wicklow (Archer).
Geogr. Distribution. — France. Germany. Austria
(var.) and Galicia. Hungary. Italy. Norway.
Sweden. Denmark. Finland. Poland. N. and S.
Russia. Greenland. X. India. W. and E. Africa
(var.). United States. Brazil.
Xautliidium fasciculatum and X. antilopseiim have in the
past been greatly confused, although the reasons for such
confusion are not altogether obvious. The spines of
X. antilopasum are somewhat variable, it is true, but no matter
what their number or disposition may be, no form of this
species has the angularly reniform semicells of X. fascicu~
latum, neither does it possess six equidistant pairs of equal
spines.
The central area is always slightly protuberant, and we
have invariably found it to possess granules, generally in the
form of a small ring surrounding two or three central ones.
It was upon this character that Nordstedt in 1885 based his
' vnv.ornatum,' Kalfs having stated that his X.fasciculatumva,r,
fi polygonum [which is X. fasciculatum Ehrenb. type] was
very near in the shape of its central projections to X.fascicu-
latum Half's var. a [which is X.antilopseam(Breh.) Kiitz.type] .
We consider both Ehrenberg's and llalfs' account of X. fas-
ciculatum to be confused and imperfect, and therefore to a
large extent unreliable. All the British, American, and
African specimens of X. fasciculatum we have examined have
possessed a granulated central area, and we conclude therefore
XANTH1DIUM. 77
tliat Nordstedt's var. ornatum (from Finland, Sweden, and
Greenland) is nothing- more than a normally developed form.
The confusion between this species and" X antilopseum is
not confined to the writings of older authors, but is equally
manifest in the publications of many modern investio-ators.
[vide remarks by Borgesen, Larsen, etc.^j
An American variety — var. Oronense W. & G. S. West
from Orono, Maine, which we figure (PI. CXI, fig. 9) for com-
parison with the typical form, also possesses a granulated
central area and the six equidistant pairs of spines on each
semicell.
In the British Islands X. fasciculatum is a verv much rarer
Desmid than X. antilojpseum.
9. Xanthidium Brebissonii Ralfs.
(PI. CXII, figs. 1 and 3.)
Binatella aculeata Breb. Alg. Falaise, 1835, p. 58, t. 8.
Xanthidium Brebissonii Bali's, Brit. Desm. 18-48, p. 113, t. 19, f. 2 a, d;
Arch, in Pi-itch. Infus. 1861, p. 736 ; Eabenh. Flor. Europ. Alg. HE
1868, p. 223 ; Cooke, Brit. Desm. 1887, p. 130 ; De Toni, Syll. Alg. 1889,
p. 926 ; West, Alg. N. Wales, 1890, p. 291 ; Alg. Engl. Lake District,
1892, p. 730; Boy. & Hiss. Scott. Desm. 1893, p. 244; Nordst. Index
Desm. 1896, p. 69 ; W. & G. S. West, Alga-fl. Yorks. 1900, p. 68; liorge
Beitrage Alg. Schweden, 1906, p. 28.
Holacanthum Brebissonii Mignla, Kryptogamenfl. in Flora Dentschl.,
Osterreich u. Schweiz, Bd. 5, 1906, p. 516, t. 28, f. 6.
Cells of medium size, about as long as broad (without
spines), deeply constricted, sinus almost closed at the
apex but opening outwards ; semicells subsemicircular,
base slightly convex and apex a little flattened in the
middle, furnished with 8 or 10 pairs of stout marginal
spines, central area strongly protuberant and truncate,
furnished with a circle of 12-13 prominent granules.
Side view of semicell subcircular, with a truncate
granulated protuberance at the middle on each side,
and 2 or 3 spines at the apical margin. Vertical view
elliptic, with 2 or 3 spines at each pole, and a truncate
granulated protuberance at the middle on each side.
Zygospores unknown.
Length without spines 61-80 jjl, with spines 79-
101 fx ; breadth without spines 62-76 /a, with spines
80-104 fx; breadth of isthmus 18-27 /x; thickness
36-50 fx.
78 BRITISH DESMIDIACEJE.
England. — Brothers' Water and Deepdale, West-
moreland ! Bog two miles S. of Clapham, W. Yorks !
Strensall, N. Yorks (Turner). Gloucester (Ralfs),
Piltdown Common, Sussex (Jenner). Penzance (Ralfs)
and near St. Jnst !, Cornwall.
Wales. — Llyn Paclarn !, and Capel Cnrig ! {Coolce Sf
Wills), Carnarvonshire.
Scotland. — Aberdeen, Kincardine, Forfar, Perth !.
Dumbarton. (Roy Sf Bissett) . Renfrew !
Ireland. — Dublin and Wicklow (Archer).
Geogr. Distribution. — France. Germany. Italy.
Norway. Sweden. Bornholm.
X. Brebissonii is an uncommon species which is very local
in its distribution. The form of its semicells and the number
of its paired spines are its distinguishing features. The spines
exhibit considerable variability in disposition, and the spines
of any pair may be inserted close together or far apart.
Var. varians Ralfs. (PI. CXII, figs. 2 and 4.)
X. Brebissonii var. varians Ralfs, Brit. Desm. 1848, p. 113, t. 19, f . 2 b, c, d
West, Alg. Engl. Lake Distr. 1892, p. 730.
Semicells proportionately wider, on each side with a
small basal protuberance projecting into the sinus ;
spines generally more curved (often uncinate).
Length without spines 61 jx, with spines 82 fx ;
breadth without spines 76 [x, with spines 108 /x ;
breadth of isthmus 14-20 /x ; thickness 46 jx.
England. — Deepdale, Westmoreland! Piltdown
Common, Sussex (Jenner). Trewellard near Penzance,
Cornwall (Ralfs).
10. Xanthidium aculeatum Ehrenb.
(PI. CXII, figs. 5-9.)
Xanthidium aculeatum Ehrenb. in Abh. Acad. Wiss. Berlin, 1833, p. 318 [in
part] ; 1. c. 1836, t. 1, f. 11 ; Infus. 1838, p. 147, t. 10, f. xxiii b [figure
bad] ; Ealfs in Ann. Mag. Nat. Hist. 1845, p. 467, t. 12, f. 2 ; Hass.
Brit. Freshw. Alg. 1845, p. 360, t. 89, f. 3 [figure bad] ; Ealfs, Brit.
Desm. 1848, p. 113, t. 19, f. 1; Arch, in Pi-itch. Infus. 1861, p. 736;
Eabenh. Flor. Europ. Alg. Ill, 1868, p. 222 ; Lund. Desm. Suec. 1871,
p. 75, t. 5, f . 5; Kirchn. Alg. Schles. 1878, p. 155; Wolle, Desm. TT. S.
1884, p. 92, t. 23, f. 10-12 [figures bad] ; Cooke, Brit. Desm. 1887, p. 130,
XANTHIDIUM. 79
t. 45, f. 2; t, 43, f. 10; Hansg. Prodr. Algenfl. Bohm. 1888 p 191-
De Toni, Syll. Alg. 1889, p. 918 ; West, Alg. N. Torks. 1889, p. 293 -A].-'
N. Wales, 1890, p. 291 ; Alg. W. Ireland, 1892, p. 164 ; Alg. Engl. Lake
Distr. 1892, p. 730 ; Eoy & Biss. Scott. Desm. 1893, p. 244 • °Nordst
Index Desm. 1896, p. 39 ; W. & G. S. West, Alga-fl. Yorks. 1900, p 68 •
Borg. Freshw. Alg. Faeroes, 1901, p. 229; W. & G. S. West, Alg. n!
Ireland, 1902, p. 31 ; Borge, Beitrage Alg. Schweden, 1906, p. 28. °
Heterocarpella aculeata Breb. in Cheval, microscop. et usage, 1839, p. 272.
Zygoxanthium aculeatum Kiitz. Spec. Alg. 1849, p. 178.
Didymidium (Xanthidium) aculeatum Reinsch, Alo-enfl Frank 1867
p. 129.
Holacanthum aculeatum Wille in Engler & Prantl, Naturl. Pflanzenfam
1890, p. 11.
Cells of medium size, about as long as broad
(without spines), deeply constricted, sinus almost
closed at the apex but gradually opening outwards ;
semicells elliptic-reniform or elliptic-subsemicircular,
apex subtruncate and often slightly elevated, basal
angles sometimes broadly rounded, sometimes rounded-
subrectangular ; spines stout, irregular in disposition,
not arranged in definite pairs, disposed at or near the
margin (in a broad irregular band along the greatest
circumference) ; central area a prominent truncate
protuberance, sometimes granulated round the margin
but often emarginate and rather irregularly lobed,
frequently with an emarginate wart or a spine, or
both, immediately above the central protuberance.
Side view of semicell subcircular, with a prominent
truncate protuberance at each side, often with a
smaller emarginate wart immediately above it, and
with 4-5 spines visible at the apical margin. Vertical
view elliptic, with a truncate, granulate or emarginate
protuberance at the middle on each side, and with 7
or 8 spines showing round each polar margin. Cell-
wall punctate or finely scrobiculate.
Zygospore globose, furnished with numerous long,
sharply-pointed spines, each arising from a dilated
base.
Length without spines 64-76 fi, with spines 75-90 fx ;
breadth without spines 62-77 /*, with spines 79-96 \x ;
breadth of isthmus 19-22*5 /x; thickness 35-45 /x;
diam. zygosp. without spines 66-70 /x, with spines
126-136 ii.
80 BRITISH ItESMIDIACK.i:.
England. — Cumberland ! Westmoreland ! (Bissett).
Lancashire ! W., N., and E. Yorks ! Gloucester, Sussex,
Kent, Hants, and Cornwall! (Rolfs).
Wales. — Dolbadarn Castle, Llyn Padarn, Snowdon,
and Glyder Fawr, Carnarvonshire !
Scotland. — Sutherland, Aberdeen, Kincardine, For-
far, Perth, Dumbarton (Roy fy Bissett). Renfrew !
Ireland. — -Lough Guitane, Kerry ! Dublin and
Wicklow (Archer). Slieve Donard, Down !
Geogr. Distribution. — France. Germany. Bohemia
and Galicia in Austria. Italy. Norway. Sweden.
S. Russia. Faeroes. United States.
X.. aculeatum is more widely distributed than X. Brebissonii,
and is not an uncommon Desmid in the more mountainous
parts of the British Islands. The spines are arranged in a
continuous irregular band around the greatest circumference
of the cell. The semicells vary somewhat in outline, and the
apex may be slightly elevated (as in Cosmarium omatum).
The central protuberance is generally much less prominent
than in X. Brebissonii, and also less granulated than in that
species, while immediately above it there is often situated a
spine or an emarginate wart.
The forms with very short spines — described as 'forma
brevispina' — have not yet been observed iti the British
Islands.
Var. basidentatum (Borg.) nob. (PI. CXVII, figs. 23,
24.)
X. Brebissonii var. basidentatum 'Borg. Bidrag Bornh. Desm.-fl. 1889,
p. 148, t. 6, f. 11 ; Eoy & Biss. Scott. Desm. 1893, p. 244; Schmidle, Alg.
deb. Oberrheins, 1893, p. 552 ; Liitkem. Desm. Millstiittersees, 1900,
p. 14, t, 1, f. 15 ; Desm. Bohm. 1910, p. 496.
Semicells a little more angular, with a more promi-
nently raised apex; spines irregular and much curved,
showing a tendency to grouping at the angles ; with
a group of 2 or 3 flattened verruca? just above but
close to the sinus on each side.
Length without spines 60-78 fx, with spines 76-
93 /x,; breadth without spines 52— 67 fi, with spines
68-80 jx ; breadth of isthmus 20-2o fx ; thickness
42-48 fx.
XANTHIDIUM. 81
Scotland. — Near Dinnet, Aberdeen ; Tent's Moor,
Fife (Boy $ Bissett).
Geor/r. Distribution. — Germany. Austria. Bornholm.
This variety has been erroneously referred to X. Brebissonii,
whereas the form of the semicells, the irregularity of the
spines, and the nature of the central protuberance are all
much more in agreement with X. aculeatutn. Moreover,
the semicells possess that raised apex which is not infrequently
met with in X. aculeatuw,, but never in X. Brebissonii. The
semicells of the latter species are proportionately wider and
the spines are much more regularly disposed.
11. Xanthidium variabile (Xordst.) W. & G. S. West.
(PI. CXIII, figs. 1-7.)
X. Smithii Arch. var. variabile Nordst. in Botan. Notis. 1887, p. 159 ;
Freshw. Alg. N. Zeal. 1888, p. 44, t. 4, f . 27-29 ; West, Alg\ W. Ireland,
1892, p. 166 ; W. & G. S. West, New and Int. Freshw. Alg. 1896, p.
156, t. 4, f. 40; Alg. S. England, 1897, p. 484; G. S. West, Variation
Desm. 1899, p. 386, t, 8, f. 20 -22.
V. variable (Nordst.) W. & G. S. West, Notes Alg. II, 1900, p. 291;
Alga-fl. Yorks. 1900, p. 68 ; Alg. N. Ireland, 1902, p. 31 ; Freshw. Alg.
Ceylon, 1902, p. 160.
X. Westianum Ghitw. Alg. Ins. Java, 1902, p. 590.
Cells small, about as long as broad, or a little
longer, deeply constricted, sinns open and acute-
angled; semicells rectangular-trapezoid, sides and
apex almost straight, angles slightly rounded and
furnished with 1--1 (commonly 3) very short, sharp
spines (one of which is usually seen within the
margin), central area small and strongly protuberant,
usually almost papilliform, but sometimes broader
and triangulate or even bispinate. Side view of
semicell angular-subcircular, with a protuberance
(sometimes emarginate or bispinate) at the middle
on each side, and a small spine at each side of the
apical margin. Vertical view elliptic, with a papilli-
form (or emarginate) protuberance at the middle on
each side, poles rounded or subtruncate, trispinate
(or rarely only bispinate). Cell-wall smooth. Chloro-
plasts axile, one in each semicell, with a central
pyrenoid.
VOL. IV. 6
82 BltlTISH DESMIDLACE^,.
Zygospore globose, furnished with numerous short
stout spines (or processes), trifid (rarely bifid) at the
apex.
Length without spines 20-26 /x [-32 fi (Nordstedt)] ;
breadth without spines 18-23 fi [-28 /x (Nordstedt)];
length of spines 2-3 /x [-4/x (Nordstedt)]; breadth of
isthmus 6-8-6 /x ; thickness 13*5-17 /x ; diam. zygosp.
without spines 29-31 [x, with spines 42-45 /x.
England.— Mickle Fell, N. Yorks ! Devils' Jumps,
Frensham (with zygospores), Esher Common, and
Thursley Common, Surrey !
Ireland. — Dungloe, near Glenties, near Gweedore,
Lough Machugh, and near Lough Glentornan, Donegal!
Foxford and Clare Island, Mayo! Near Oughterard
and Clifden, Galway ! Tore Mountain, Cromagloun,
and Carrantuohill, Kerry !
Geogr. Distribution. — Ceylon. Australia, New Zea-
land. British Guiana. Patagonia.
We regard X variabile as one of the most distinctive
species of the genus. It occurs in many parts of the British
Islands, more especially in certain peaty Sjiliagnum-bogz, in
which it is sometimes found in large numbers. It differs
from X Smithii in its somewhat smaller size, its much more
protuberant central area, and in its much shorter and more
invgular spines. These points of difference are retained very
constantly, and not only does X variabile never occur
associated with X. Smithii, but no intermediate forms are
known which in any way tend to connect these species. In
fact we consider them to belong to different sections of the
g'enus Xanthidium.
X. variabile exhibits a considerable amount of variation
without losing any of its distinctive features. Each basal
angle possesses three short spines which show most distinctly
at the poles of the vertical view. The apical angles possess
either two or three spines. The central protuberance in the
great majority of specimens is in the form of a rather pro-
nounced papilla, but it may be truncate-emarginate or even
bispinate.
The poles of the vertical view were described by Nordstedt
as truncate in the New Zealand specimens. In British
examples, howevei', they are generally rounded, or rarely
sid (truncate. This is a point of little importance, although
XANTHIDIUM. 83
Gat win ski,, with his customary lack of perception, has seized
upon it as a reason for naming the British specimens X.
Westianum !
12. Xanthidium Robinsonianum Arch.
(PL CXIII, figs. 10-12; PL CXVIII, figs. 1-3.)
Xanthidium Robinsonianum Arch, in Q. J. Micr. Sci. n.s. xxii, 1880,
pp. 114, 116; Joshua in Journ. Bot. xxi, 1883, p. 291; Wittr. &
Nordst. Alg. Exsic. 1883, no. 550 ; Cooke, Brit. Desm. 1887, p 131 •
De Toni, Syll. Alg. 1889, p. 924.
X. variabile (Nordst.) W. & Gr. S. West var. comvlexum W. & G S West
Alg. X. Ireland, 1902, p. 31, t. 2, f. 8.
Cells small, as long as broad, deeply constricted,
sinns narrowly linear with a slightly dilated extremity;
semicells widely pyramidate-trapeziform, apex straight
or very faintly retuse, upper parts of sides slightly
retuse, apical angles slightly rounded, basal angles
broadly rounded; spines minute, variable in number
and exact disposition, but mostly grouped at the
angles and within the margin of the semicells, 2-4- at
each angle and with groups of 2—3 within the margins,
one of these groups almost invariably situated just
below the middle of the apex ; central area small and
protuberant, furnished with 3—5 granules more or less
irregularly disposed and sometimes connected by other
acute granules with the small group of spines below
the apex. Side view of semicell depressed-circular,
with an emarginate protuberance on each side. Ver-
tical view elliptic, with an emarginate protuberance at
the middle on each side, poles rounded and furnished
with 5-8 minute spines.
Zygospore globose, furnished with " delicately
furcate, tuberculose" spines (Joshua).
Length without spines 22-25 //,, with spines 24-
26*5 [x ; breadth without spines 22-25 /x, with spines
24-28 /u, ; breadth of isthmus 6'5-8'5 fx ; thickness
14-5-1(3 [x.
Wales. — Bog between G-lvder Fach and the river
Llugwy, Carnarvonshire !
Scotland. — N. of Barvas, Lewis, Outer Hebrides !
84 BRITISH MiSMIDIACK.K.
Ireland. — Near Grlenties, and Grlendoan, Donegal !
Armagh (Archer). Kildare (Crowe). Glengariff, Cork
(Crowe).
As in the case of so many other small Desmids discovered
by Archer, the promised full description of X. Rohinsonianum
did not appear, so that the only information concerning it are
the brief statements in the reports of the Dublin Microscopical
Club. It is a very rare Desmid, which up to the present has
been found nowhere in the world except in the western areas
of the British Islands. Its exact identity was long- uncertain,
which accounts for the fact that we described it in 190*2 as
' X. variahile var. complesbum.' Careful consideration, how-
ever, of the meagre information supplied by Archer, convinces
us that the Desmid we have so described is X. Rohinsonianum,
and that another minute Xanthidium which we had described
under the name of X. Rohinsonianum is an un described
species. This view was amply confirmed by an examination
of the specimens issued in Wittrock and Nordstedt's f Algae
Exsiccata?,' No. 550, under the name of X. Rohinsonianum,.
These are undoubtedly the Desmid which we described as
X. variahile var. complexum and which we have since come
to regard as X. Rohinsonianum. V\e give some figures of
these specimens (PI. CXVIII, tigs. 1-3) for comparison with
those of specimens collected by ourselves.
In some individuals the central protuberance is furnished
with three elongated and regularly disposed granules, but in
others there are four or five smaller granules, and these are
not infrequently connected with the small group of subapical
spines by several acutely -pointed granules.
X. Rohinsonianum differs from X. variahile in the shape of
its semicells, in the closed sinus, and in the more numerous
and differently grouped spines. The zygospore is also
probably of a different character, but Joshua's remarks on
the characters of the zygospore are very indefinite and he
gives no figures. The zygospores were obtained from Derry-
strasna Bog, Armagh.
13. Xanthidium Orcadense sp. nor.
(PL CXIII, figs. 10-12.)
Xanthidium Rohinsonianum W. & G. S. West, New and Int. Freshw. Alg.
1896, p. 156, t. 3, f. 21, 22. [This is not X. Rohinsonianum Arch.]
Cells small, as long as broad, deeply constricted,
sinus open and acute-angled ; semicells transyersely
XANTHIDIUM. 85
subrectangular, with convex lower margin, subparallel
sides, and a slightly convex apex, or subpyramidate-
trapeziform, with broadly rounded basal angles, and
almost straight sides and apex; spines very minute,
1-2 at each superior angle and 1-4 at the margin of
each basal angle, within the margins and towards the
centre with a few irregularly disposed spines (or acute
granules) ; central area protuberant but not thickened
or granulate. Vertical view elliptic, . with a small
rounded protuberance at the middle on each side,
poles rounded, each polar margin furnished with 3-6
minute spines.
Zygospore unknown.
Length without spines 18-27 [x ; breadth without
spines 10-24/x; length of spines 08-1 -2 /x ; breadth of
isthmus -y o-Dv //, ; thickness 11'5-13/a.
Sc( tJLAX l >. — Orkneys !
We have only observed this small species from a Sphagnum-
bog in the Orkney Islands, and in 1896 gave a description
of it under the name of X. Robinsonianum. We now know
that our identification was incorrect, and we therefore
describe ir as a new species. X. Orcadense differs from
X. Robinsonianum in it^ open sinus, in its more scattered and
more reduced spines, and in the rounded and less evident
central protuberance.
14. Xanthidium apiculiferum West.
(PI. CXIII, tig. 9.)
Xanthidium apiculiferum West, Alg. W. Ireland, 1892, p. 107, t. 24, i. 17;
Nordst. Index Desm. 1896, p. -IS.'
Cells minute, as long as broad, deeply constricted,
sinus narrow and slightly open ; semicells very
broadly pyramidate-trapezif orm, angles slightly rounded
and apex broadly truncate, inferior angles each fur-
nished with a single minute spine, superior angles each
furnished with a pair of minute spines, and with a
similar pair in the middle of the apex, central area
small and protuberant. Side view of semicell sub-
circular, with a small protuberance at the middle on
86 BRITISH DESMIDLAOE.K.
each side, and a pair of slightly divergent, minute
spines at the apical margin. Vertical view elliptic,
with one minute spine at each pole, and a small pro-
tuberance at the middle on each side.
Zygospore unknown.
Length without spines ll"5ja3 with spines 12*5 fi;
breadth without spines 12/x, with spines 12"5/>t;
breadth of isthmus 5 /x ; thickness 6'5 /x.
Ireland. — In small lake near Recess, Galway !
This little species should be compared with X. concinnum
Arch., from which it differs in the form of its semicells and in
the pair of minute spines in the middle of the truncate apex.
15. Xanthidium concinnum Arch.
(PL CXII, fig. 10.)
Xanthidium concinnum Arch, in Ann. Mag. Nat. Hist. ser. 5, xi, 1883, p. 285 ;
Cooke, Brit, Desm. 1887, p. 189 ; Nordst. Index Deam. 1896, p. 78 ;
W. & G. S. West, Alg. S. England, 1897, p. 48-4, t. 6, i. 15 ; Alga-fl.
Yorks. 1900, p. 68 ; Freshw. Alg. Orkneys and Shetlands, 1905, p. 23 ;
Liitkem. Desm. Bohm. 1910, p. 497.
Arthrodesmus hexagonus Boldt, Siber. Chlorophy. 1885, p. 109, t. 5, f. 16 ;
De Toni, Syll. Alg. 1889, p. 1059; Gntw. Flor. Glon. Okolie Lwowa,
1891, p. 64, t. 3, f. 9; Eichler in Painietnik fizvj. Akad. Umiej. Krakow,
1894, p. 130.
Xanthidium hexagonum (Boldt) Turner, Freshw. Alg. E. India, 1893,
p. 137.
Cells minute, about as long as broad, deeply con-
stricted, sinus narrow and linear; semicells trans-
versely subhexao'onal with a broad, truncate (or very
slightly convex) apex, lateral angles each furnished
with a single minute spine, apical angles each fur-
nished with a pair of minute spines, central area small.
Side view of seinicell subcircular, with a small papilla
at the middle on each side and a pair of minute spines
at the apical margin. Vertical view elliptic, with a
prominent papilla at the middle on each side, with
one minute spine at each pole and a pair of minute
spines on each side near the poles. Chloroplasts axile,
with a single central pyrenoid in each semicell.
Zygospore unknown.
Length without spines (.)-9*-j /x ; breadth without
XANTHIMCM. 87
spines 9*5-10*5/a; breadth of isthmus 2'5-Sfi; thick-
ness 7 jJL.
England. — Bog two miles S. of Clapham, W. Yorks !
Puttenham and Thursley Commons, Surrey!
Wales. — Grlyder Fach, Carnarvonshire !
Scotland. — Rhiconich, Sutherland! Orkneys! Shet-
land s !
Ireland. — \Yicklow (Archer).
Geogr. Distribution. — (lalicia and Bohemia in
Austria, Siberia.
This minute Desmid, first describtMl by Avclier as Xanthi-
dium coneinnum, was afterwards described and fio-ured by
Boldt under the name of Arthrodesmus hexagonus. It is
characterized by the hexagonal form of its semieells, by
the single minute spine at each lateral angle, and the pair
of similar minute spines at each apical angle. It should
be compared most carefully with Cosmariurn pygmaeum
Arch, (vide Vol. Ill, pp. 73-75, t. 71, figs. 22-81).
Var. Boldtiana West. (PI. CXII, figs. U, 12.)
Arthrodesmus hexagonus 'forma' Boldt Siber. Clilorophv. 1885, p. 109. t. •">,
f. 17.
Xanthidium coneinnum Arch. var. Boldtiana West, Alg. W. Ireland, 1892,
p. 167, t. 22, f. 6 ; Boy & Biss. Seott. Desm. 1893, p. 2-44 ; W. & G. S.
West, Alg. S. England, 1897, p. 484
Arthrodesmus hexagonus Boldt var. polonica Eiehl. & Racib. in Rospraw
Wvdz. matem.-przy. Akad. Umiej. Krakow, xxvi, 1893, p. 122, t. 3,
f. 6, 7.
Cells often less deeply constricted ; semicells ellip-
tic-hexagonal, without the apical pairs of minute
spines.
Length 10-13 /x ; breadth without spines 10-13'5 /a;
breadth of isthmus 2*5-4 fx ; thickness 8-10 /a.
England. — Thursley Common, Surrey!
Scotland. — Loch Ullachie near Ballater, Aberdeen
(Boy Sf Bissett).
Ireland. — Xear Oughterard, Galway ! Moher Lough,
Aiavo ! Lower Lake of Killarney, Kerry !
Geogr. Distribution. — Poland. Siberia. United
States.
This variety differs from typicnl X coneinnum in the
absence of the pairs of minute apical spines.
S> BRITISH DESMIDIACEJS.
Genus 17. ARTHRODESMUS Ehrenb. 18:38.
Ehrenb. in Arch. Naturg. Bd. II, 1836, p. 1S5 [name only"! ; Infus. 1838,
p. 149.
Ealfs in Ann. Mag. Nat. Hist, xv, 1845, p. 150.
Hass. Brit. Freshw. Alg. 1845, p. 356.
Ealfs, Brit. Desm. 1848, p. 117.
Kiitz. Spec. Algar. 1849, p. 176.
Arch, in Pritch. Infus. 1861, pp. 721, 736.
Eabenh. Flora Europ. Alg. Ill, 1868, p. 225.
Kirchn. Alg. Schles. 1878, p. 156.
Wolle, Desm. U. S. 1884, p. 95.
Cooke, Brit. Desm. 1887, p. 134.
Hansg. Prodr. Algenfl. Bohin. 1888, p. 202.
De Toni, Syll. Alg. 1889. p. 1056.
Turn. Freshw. Alg. E. India, 1893, p. 137.
G. S. West, Treatise Brit. Freshw. Alg. 1904, p. 170.
Cells mostly small, sometimes minute, usually about
as broad as long, invariably compressed (except in the
very rare triangular forms), symmetrical in three planes
at right angles to each other; median constriction
generally fairly deep, sinus nearly always open; semi-
cells very generally obversely triangular, sometimes
subquadrate and sometimes elliptic or subelliptic,
centre of semicell quite plane and undifferentiated;
vertical view elliptic, with no median 'protuberances.
Cell-ivall furnished with simple spines disposed in a
median plane, one inserted at each lateral angle.
Chloroplasts axile, generally one in each semicell,
but subject to considerable variation, usually with
one central pyrenoid.
Zygospores globose, smooth or furnished with simple,
subulate spines.
The genus Art.hr odesmus is closely related to Xaiithidium
and to certain of the spiny species of Staurastrum. It is
primarily distinguished from Xanthidium by the absence
from the semicells of any differentiated central area, and
secondarily by the insertion of the spines in a median plane.
Paired spines do not occur in the genus Arthrodesmus except
in the one instance of A. tenuissimus Arch., in which
the minute apical spines are paired. On the other hand,
there are several species of Xanthidium in which all the
spines are median and unpaged.
Some forms of certain species of Staurastiiim, such as *S7.
s
s
A.RTHRODESMUS. 89
jantiiferihi, var. suhe,:ccaratiim, forms of St. O'Mearii, etc., and
also souk' of the larger forms of Arthrodesmus Incus, are very
confusing in their relationships, and are only placed with
considerable difficulty. In some cases it is necessary to
examine a large series of forms from various districts in
oi-i.V r t<> arrive at a decision concerning the genus.
Jo st as there are fusiform or biradiate forms of Staurastrum,
so t'lerc are triangular forms of Arthrodesmus, such as A.
tr'ntn/it/iiris var. sub triangularis forma triquetra (cf. PI. (_'XY.
^ otwitlistanding the difficulties concerned with the placing
OJ J»tiesr transitional forms, and the fact that its definition
cw '" lot be made very exact, the genus Arthrodesmus is a
great convenience for the reception of those Desmids which
do not rightly belong either to Staurastrum or Xanthidium.
The genus has been subdivided into the sections ' Tetra-
canthiuni ' and ' Uctacanthium' by Hansgirg, into Euarthro-
desmus' and e Ce)drenterium} by Raciborski (who included
Bohlt's subgenus of Xanthidium) , and into ' Aplodesmus' and
• Schi,i,n> sin its' by Turner. It is not possible, after a careful
consideration of the species of this genus, to accept the
suggestions either of Raciborski or of Turner, but Hansgirg's
two sections are quite satisfactory for most species of the
genus. To these we have added a third section for the
reception of the species which do not appear to have been
sufficiently well studied by the above-mentioned authors.
Both Borge and Lutkeinuller have suggested that Ichthyo-
cercAis should probably be placed as a section of Arthrodesmus,
but that genus is nearest to Tetmemorus and has no close
affinity with Arthrodesmus. *
Section A. Seniicells with a single spine on each side, attached
to the lateral angle. [Tetracanthium (Nag.) Hansg.]
* Seniicells olisemicircular or in the form of an inverted
triangle, sinus open.
Angles of seniicells furnished with long or very long
spines.
% Apex of semicell straight or convex (or very faintly
concave), spines very rarely horizontal, usually
divergent, rarely convergent.
1. A. Inc us.
XX Apex of semicell elevated, and refuse in the middle
(except in one variety), spines horizontal.
2. A. triangularis.
XXX Apex of semicell refuse in the middle, spines of
great length and widely divergent.
3. A. quiriferus.
(.H> BRITISH DESMIDIACEJS.
++ Angles of semicells furnished with verv short spinet,
often merely mucronate.
+ Apex of semicell convex.
§ Cells small, vertical view rhomboid.
4. A. cras8U8.
§§ Cells minute, vertical view elliptic.
5. A. con-trovers iu.
IX Apex of semicells retuse, making the semicells
triangular-lunate.
6. A. phimiis.
■ Semicells subreetangular, sinus closed and linear.
7. A. P}tLllli'l niii .
*** Semicells elliptic or narrowly elliptic.
t Spines rather short and incurved, sinus closed at bbe
apex and opening outwards.
8. A. convergent.
t+ Spines longer and disposed horizontally, sinus open
from the extreme apex.
9. A. subidatusM
Section B. Semicells with two spines on each side, one
attached to each of the two lateral angles. [Octncanthinm Hans>>-.
* Semicells rectangular with retuse sides, spines fairly lon^.
10. A. octocomis. ...
** Semicells hexagonal depressed, spines short.
11. A. bifidus.
Section C. Semicells with three spines on each side.
* Three spines in the same vertical plane.
12. A. trisjiinat/is.
** Three spines not in the same plane; one lateral and two
apical, the latter forming a pair in a horizontal pla-ie.
13. A. ten u!*sl in im.
1. Arthrodesmus Incus (Breb.) Hass.
(PI. CXIII, figs. 13-15.)
Binatella Incus Breb. Alg. Falaise, 1835. p. 2(39.
Heterocarpella Incus Breb. in Cheval. microscop. et usage, 1S39, p.
Siaurastrum Incus (Breb.) Menegh. Synops. Desin. 1840, ]>. 228; Ralls
in Ann. Mao-. Nat. Hist. 1845, xv, p. ] .is, t . 12, f. 2 ; Jacobs. Deem. Dariem.
1876, p. 204- [in part].
Arthrodesmus Incus (Breb.) Hass. Brit. Freshw. Alg-. 1845, p. 357, t. 85,
f. 10; Ball's, Brit. Desm. 1848, p. 118, t. 20, f. 4 a-d; Arch, in Pritc-h.
Infns. 1801, p. 737 [in part] ; Rabenh. Flor. Enrop. Alg. Ill, 18(58,
p. 226 [in part] ; Nordst. Desm. Brasil. 1870, p. 231 : Kirohn. Alg.
iSchles. 1878, p. 156; Wolle Desm. U.S. 1884, p. 97, t. 24, f. 5 ( :- ) ;
Boldt, Siber. Chlor. 1885, p. 109 ; Cooke, Brit. Desm. 18S7, p. 135, t, 47,
f. 4 [in part] ; Hansg. Prodr. Algenfl. Bohm. 1888, p. 202 ; Boldt,
Desmid. (Iionland, 1888, p. 30; Nordst. Freshw. Alg. N. Zeal. 18»8,
p. 45 ; De Toni, Syll. Alg. 1 JS9, p. 1057 ; West, Alg-. W. Ireland, 1892,
p. L68 : Alo-. Engl. Lake Distr. 1892, p. 730; Liitkem. Desm. Attersees,
artheodl:smus. 91
1893, p. 559 ; Roy & Biss. Scott. Desm. 1894, p. 40 ; Nordst. Index Desm.
189(5, p. 145 ; W. & G. S. West, Alg. S. England, 1897, p. 496; Alga-fl.
Yorks. 1901, p. 109 ; Borg. Freshw. Alg. Faeroes, 1901, p. 228 ; W. &
G. S. West, Alg. N. Ireland, 1902, p. 58 ; Hirn, Desm. Finland, 1903,
p. 5 ; W. & G. S. West, Scott. Freshw. Plankton, 1, 1903, p. 527 ; Borge,
Alg. erst. Regnell. Exped. II. Desmid. 1903 p. 103 ; W. & G. S. West,
Freshw. Alg. Orkneys and Shetlands, 1905, p. 23; Further Contrib.
Plankton Scott. Lochs, 1905, p. 485 ; Comp. Study Plankton Irish Lakes,
1906, p. 85 ; Borge, Beitriige Alg. Sehweden," 1906, p. 49 ; Larsen,
Ferskvandsalg. Vest-Gronl. 1907, p. 324; W. & G. S. West, Brit.
Freshw. Phytoplankton, etc., 1909, p. 181 ; Phytoplankton Engl. Lake
District, 1909, p. 138.
/•.' lastrum retusum Kiitz. Phyc. germ. 1845, p. 136.
Cosmarium Incus De Bary, Conj. 1858, p. 72.
C. retusum (Kvitz.) Rossmann in Jahresber. d. Wetterau. Ges. f. die
gesammte Naturkunde zu Hanau, 186 L, p. 7.
Arihrodesmus Incus b. Lund. Desm. Suec. 1871, p. 55.
Didymidium erectum Reinsch, Algenfl. Frank. 1867, p. 157 [in part].
Arthrodesmus Incus var. divergens Cooke, Brit. Desm. 1887, p. 136: West,
Alg. N. Wales, 1890, p. 291.
A. Incus forma typica Heimerl, Desm. alp. 1891 , p. 603, t. 5, f . 17 ; Lutkem.
Desm. Millstattersees, 1900, p. 13.
Cells rather small, a little longer than broad
(without the spines), deeply constricted, sinus widely
open and sometimes submamillate at the extremity ;
semicells obversely triangular or obversely subtrapezi-
form-triangular, apex straight, rarely slightly concave,
sides very faintly convex, each angle only slightly
rounded and furnished with an elongated, stout,
diverging spine. Vertical view elliptic, each pole
furnished with a long, stout spine. Cell- wall smooth.
Chloroplasts axile, one in each semicell, sometimes
containing a conspicuous pyrenoid.
Zygospore not definitely known, but probably
furnished with simple spines.
Length without spines 21-27 /x, with spines II-
50//,; breadth without spines 18-28 [x, with spines
56-71 /x ; length of spines 20-28 fx ; breadth of isthmus
7-9 ja ; thickness 10— 11*5 /x.
England. — Cumberland ! Westmoreland ! Surrey !
Cornwall ! In the plankton of Buttermere, Enner-
dale Water, and Bassenthwaite Water, Cumberland!
In the plankton of Easdale and Codale Tarns, West-
moreland !
Wales.— In the plankton of several of the lakes of
Carnarvonshire !
\^2 BRITISH DESMIDIACEiE.
Scotland. — Sutherland! Inverness! Perth! Ayr!
Lewis and Harris, Outer Hebrides!
Irkland. — Donegal! Galwav! Mayo! Kerry! Cork!
Georji'. Distribution. — (The following distribution
most certainly includes the records of forma minor,
var indebitatus, and var. Ralfsii). France. Belgium.
Germany. Austria. Italy. Norway. Sweden. Den-
mark. Bornliolm. Finland. Poland. S- Russia.
Fasroes. Iceland. Greenland. India. Java. New
Zealand. Australia. United States. Cuba (var.). W.
Indies (var.). Guiana. Brazil. Paraguay. Patagonia.
Arthrodesmus Incus has numei*ous varieties, some of which
are distributed all over the world. It is very probable that I
many of the records e'iven above refer to one or more of the
following' varieties and not to what we consider the type
form. We have regarded the form described above as the
type form for two reasons. In the first place, most of
the forms of this Desmid are fair]}' stout with long divergent
spines ; and secondly, this form is nearest to certain forms
of Staurastrum from which it is probable that Arthrodesvius
Incus originated. It is, so far as we can judge, the least
specialized of all the forms of A. Incus.
Some of the long-spined forms with distinctly triangular
semicells appear to form a graduated series with the biradiate
forms of Staurastrumjacidiferum, and other species of Arthro-
desmus are closely related to certain of the triangular spiny
species of Staurastrum. In fact, there seems little doubt
that the majority of the species of Arthrodesmus have arisen
from certain species of Staurastrum by the adoption of a
permanent biradiate character.
Jn certain individuals we have noticed that through the
larger pores in the cell-wall a tough mucilage is excreted,
which assumes the form of blunt or emarginate processes
standing out at right angles to the surface of the wall and
disposed one over each pore. These mucilaginous processes
occasionally turn yellow or even brown in colour and become
quite hard. (Consult PI. CXIII, fig. 15; also PI. CX1V,
fig. 5c.)
Forma minor nob. (PI. CXIII, figs. 16-19.)
Arthi'tidexmti* Incut of very many authors.
Cells not much more than half the size of the type,
ARTHRODESMUS. 93
very slightly inflated so that both sides and apex of
semicells are a little convex ; cell-wall thinner ; spines
considerably shorter and not so robust.
Zygospore snbglobose, furnished with simple, acute
spines.
Length without spines 12'5-16'5/a, with spines
19-25 fx; breadth without spines 12-5-13*5ft, with
spines 19-26 p; length of spines 4-9 //. ; breadth of
isthmus -Vo-7/x; thickness 7-8*5 p; diam. zygosp.
without spines 19 /x, with spines 33-37 /a.
England. — Cumberland ! Westmoreland (zygospores
from several localities) ! W. and X. Yorks. (zygo-
spores from near Halifax and in bog 2 miles S.W.
of Clapham) ! Cheshire (Boy). Leicestershire (Hoy).
Warwick ! (Wills). Gloucester ! Surrey (zygospores
from Chobham and Esher Commons) ! Sussex !
Hants ! Devon ! Cornwall !
Wales. — General (zygospores frequent in Carnar-
vonshire and Merioneth) !
Scotland. — General! (Boy $• Bissett). Frequently
conjugated ! Lewis, Harris, X. and S. Uist, and
Benbecula, Outer Hebrides ! Orkneys ! Shetlands !
Frequent in the plankton !
Iceland. — Very frequent (zygospores not un-
common) !
Geogr. Distribution. — Consult that under the type
form, which it has been impossible to unravel.
This small form is perhaps one of the most abundant forms
of Arthrodesmus Incus met with in the British Islands, and is
certainly the most frequent one observed with zygospores.
It is sufficiently distinct by reason of its small size and
more delicate spines. It is found principally amongst
Sphagnum, both in bogs and pools.
Forma perforata Schmidle. (PI. CXIV, fig. 1 .)
Arthrodesmus Incus forma perforata Schmidle, Lappmark Siisswasser-
algen, 1898, p. 42, t. 2, f. 11.
Spines shorter ; cell-wall with a few scattered,
irregularly disposed scrobiculations.
94 BRITISH DKSMIDIACE/E.
Length without spines 81 fx, with spines 4o ^ ;
breadth without spines 2G fx, with spines 56 /* ; breadth
of isthmus 12*5/1.
Wales. — Llyn Idwal, Glaslyn, and Llyn-y-Ddinas,
Carnarvonshire !
Geogr. Distribution. — Lappmark in Norway.
The scrobic illations on the cell-wall of this form are doubt-
less situated each under the base of one of the mucilaginous
processes which have already been mentioned.
Var. indentatus var. nov. (PI. CXIII, figs. 20-24.)
Sides of semicells indented just above the isthmus,
making the semicell tranversely subrectangular in its
upper greater portion and somewhat cup-shaped in its
lower lesser portion ; spines long and stout, generally
divergent but more rarely horizontal. Cell-wall some-
times irregularly and sparsely scrobiculate.
Length without spines 2(3-31 ll ; breadth without
spines 18-22 /a; length of spines 17*5-26 /i; breadth
of isthmus 7-9 /x.
England. — Cumberland ! Westmoreland ! IS". Yorks !
Cornwall !
Wales. — Capel Curig, Llyn Ogwen, Llyn Idwal,
Llyn-y-cwm-ffynon, and Grlyder Fach, Carnarvonshire !
Dolo-ellv, Merioneth.
Scotland. — Sutherland! Perth! Forfar! Aberdeen!
Lewis and Harris, Outer Hebrides !
Ireland. — Donegal! Down! Mayo! Galwav! Kerry!
Cork !
This is one of the most frequent British varieties, occurring
principally at the boggy and weedy margins of lakes. It is
somewhat variable in the length and divergence of its spines,
but the slight constriction of the basal part of the semicell is
a very constant feature. Some of the cells are irregularly
scrobiculated, somewhat as in A. Incus forma perforata, and
these might be known as 'foi'ma scrobiculata' (PI. CXIII,
li^-24)*
It is possible that this variety is identical with A. Incus
forma isthmosa Heimerl ('Desna, alp.' 1891, p. 603, t. 5, f. 18)
ARTHEODESMUS. 95
but Heimerl's figures do not show the character upon which
we have founded this variety.
Var. Ralfsii W. & G. S. West. (PL CXIV, fio*s.
2-4.)
Arthrodesmus Incus var. fi Ralfs, Brit. Desm. 1848, p. 118, t. 20, f. 4 e-h^
? A. Incus forma Brebissonii Eacib. Desm. Ncnve, 1889, p. 96, t. 6, f. 15.
A. Ralfsii Wes, Alg\ W. Ireland, 1892, p. 168 ; Alg. Engl. Lake Distr
1892, p. 730-. W. & G. S. West, Alg. S. England, 1897, p. 497.
A. Incus var. vulgaris Eichl. & Eacib. inEospraw. Spraw. Wydz. matem.-
przyr. Akad. Umiej. Krakow, xxvi, 1893, p. 119.
.4. Incus var. Ralfsii W. & G. S. West, Alga-fl. Yorks. 1901, p. 109; Alg.
N. Ireland, 1902, p. 58 ; Scott Freshw. Plankton, I. 1903, p. 528 ; Freshw.
Alg. Orkneys and Shetlands, 1905, p. 23 ; Cushman in Ehodora, vii,
1905, p. 261 ; W. & G. S. West, Further Contrib. Freshw. Plankton
Scott. Lochs, 1905, p. 485; Cushman in Bull. Ton*. Bot. Club, xxxiii,
1907, p. 613 ; W. & G. S. West, Brit. Freshw. Phvtoplankton, etc., 1909,
p. 181 ; Phvtoplankton Engl. Lake Distr. 1909, p. 138.
? Btaurastrv/m Sarsii var. longispinum Huitfeldt-Kaas, Plankton. Norske-
Vande, 1906, p. 56, t. 1, f. 18, 19.
Semicells trapeziform, with the sides somewhat
upwardly diverging and a straight or slightly concave'
apex. Sinus a small rounded excavation. Spines
of moderate size and slightlv convergent.
Zygospore globose, furnished with long, simple
spines.
Length 27-33/x ; breadth without spines 18-20^,, with
spines 44-47 /a ; breadth of isthmus 7'»:>-(.>--5 jx ; diam.
zygosp. without spines 19 fi, with spines 35 jx.
England. — Westmoreland ! W., X., and E. Yorks !
Warwicks ! Essex ! Surrey ! Devonshire ! Cornwall !
In the plankton of Codale and Easdale Tarns, West-
moreland !
Wales. — Capel Curig, and in the plankton of Llyn
Ogwen, Carnarvonshire !
Scotland. — Perth! Aberdeen! Inverness! Forfar!
Sutherland ! In the plankton of Loch Fadaghoda,.
Loch Roinebhall, and Loch Shubhaill, Lewis; and
Loch a Bhursta, Benbecula, Outer Hebrides ! Orkneys !.
Ireland. — Donegal ! Roundstone and Lough Derry-
O CD t/
clare, Gahvay ! Near Lough Brin, Kerry ! Castletown
and Adrigole, Cork !
Geogr. Distribution. — Sweden. Greenland. (Consult
also the distribution given under the type.)
96 BRITISH DESMIDIA-CEiE.
This variety is widely distributed in the British Islands,
and several distinct forms of it can be recognized apart from
the one originally figured by Halt's. Two of these we have
named as follows : —
Forma latitjscula (PI. CXI V, fig. 5). Cells proportionately
wider and isthmus broader; spines shorter. Length 18-
20 in; breadth without spines 19-23 fx, with spines 31-34 fi;
breadth of isthmus 9—10 ^t.
Forma subhexagona (PI. CXIV, fig. 6). Smaller; semicells
subhexagonal-elliptic, spines very short. Length 15-4^i;
breadth without spines 15 n ; length of spines 3-3'8 /< ; 1 treadth
of isthmus 7 • 5 / 1 . This form has been' described and figured
as A. Incus var. Ralfsii forma spinis brevissimis W. & Gr. S.
West, 'Further Cont'rib. Freshw. Plankton Scott. Lochs/ 1905,
p. 501, t. 7, f. 10. It would appear also to be identical with
Staurastrum defectum Breb. var. Debaryanum (Jacobs.) Nordst.
forma Borge, 'Beitrage Alg. Schweden/ 1906, p. 44, t. 3,
I'. 36.
Var. validus W. & G. S. West. (PI. CXIV, figs. 9, 10.)
A. Incus var. validus W. & G. S. West, Some Desm. U. S. 1898, p. 320, 1. 17,
f. 16; Freshw. Alg. Ceylon, 1902, p. 192; Cushman in Rhodora, vii,
1905,' p. 260.
Cells large; semicells obversely subsemicircular
with an almost straight apex; spines very stout and
long, strongly divergent.
Length without spines 33-35 /a, with spines 84-
111ft; breadth without spines 29-36 ^, with spines
50-76 ft; length of spines 27-42 ft ; breadth of isthmus
8-5-9 ft.
Scotland. — Rhiconich, Sutherland !
Ireland. — Near Foxford, Mayo !
Geogr. Distribution. — Ceylon. United States.
This is the stoutest of the varieties of A. Incus, and in the
largest forms the bases of the spines are hollow (consult
PI. CXIV, f. 9).
Var. longispinus Eichl. & Racib. (PL CXIV, fig. 8.)
A. Incus Wolle, Desm. U. S. 1884, t. 24, f. 3.
.4. Incvs forma lungispina Eichl. & Racib. in Rospvaw. Spraw. Wydz.
matem.-przyr. Akad. Umiej. Krakow, xxvi, 1893, p. 120, t, 3, f. 21.
A. Incus var. longispinus W. & G. S. West, Further Contrib. Freshw.
Plankton Scott. Lochs, 1905, p. 501, t. 7, f. 22 ; Cushman m Rhodora,
vii, 1905, p. 260.
AETHRODESMUS. 97
A small variety with the spines very long and
upwardly divergent to the same extent as in var.
validus.
Length without spines 14 p; breadth without spines
11'5 jx; length of spines 21-25 /x; breadth of isthmus
57 ix.
Scotland. — Small loch near Cearnabhall, Lewis,
Outer Hebrides (in the plankton) !
Geogr. Distribution. — Poland. United States.
This variety is well characterized by the great length of
the spines as compared with the size of the cell-body.
Var. subquadratus W. & G. S. West. (PL CXIV,
fig. 7.)
? A. Incus forma quadrata Schmidle, Beitr. alp. Alg. 1896, p. 26 (sep.),
t, 16, f. 10.
A. Incus var. subquadratus W. & G. S. West, Alg. S. England, 1897, p.
496, t. 7, f. 20.
A small variety with the cells much less constricted
than usual; semicells subquadrate or rectangular-
quadrate, sides and apex very slightly convex.
Length without spines 15-1 7 /a; breadth without
spines 11/x: length of spines 5-5-7/x; breadth of
isthmus 7'bjx; thickness 8 jjl.
England. — Chobham Common, Surrey!
It is possible that " forma quadrata " described by Schmidle
from the Tyrol is identical witli this variety, but Schmidle's
figure is poor. His description reads " aculeis divergentibus,
apicibus truncato-rotundatis, lateribus fere parallelis vix vel
non concavis."
2. Arthrodesmus triangularis Lagerh.
(PI. CXIV, figs. 11-13, 17.)
Arthrodesmus triangularis Lagerh. Bidr. Amerik. Desm.-fl. 1885, p. 241,
t, 27, f. 22 ; De Toni, Syll. Alg. 1889, p. 1061 ; Eacib. Desni. Tapakooinas.
1895, p. 33 ; W. & a. S. West, Alg. N. Ireland, 1902, p. 58 ; Scott.
Fresh w. Plankton, 1. 1903, p. 528 ; Freshw. Alg. Orkneys and Shetlands,
1905, p. 24; Further Contrib. Freshw. Plankton Scott. Lochs, 1905,
p. 485; Freshw. Alg. Burma, 1907, p. 211, t. 15, f. 7; Brit. Freshw.
Phytoplankton, etc., 1909, p. 181 ; Phytoplankton Engl. Lake Distr.
1909, p. 138.
? A. Incus iovm&rotundata Eacib. Desm. Nowe, 1889, p. 96, t. 6, f. 16.
A. Incus var. triangularis Lagerh. in Nuova Notarisia, IV, 1893 p. 182.
VOL. IV. 7
98 BRITISH DESMIDIACE.E.
Cells rather small, a little longer than broad (without
the spines), deeply constricted, sinus a wide (often almost
semicircular) excavation, isthmus generally elongated
and shortly cylindrical ; semicells obversely triangular,
apex elevated and convex, retuse in the median part,
sides slightly convex, each lateral angle slightly
rounded and furnished with a long horizontally-
placed spine. Vertical view elliptic, each pole with
a long spine. One axile chloroplast in each semicell
containing a single pyrenoid.
Zygospore unknown.
Length (without spines) 23-30 fx; breadth without
spines 19-25 />t; length of spines 12*5-25 /x; breadth
of isthmus 5-7 /z ; thickness 7*8-9 /x.
England. — Plankton of Ennerdale Water and Crum-
mock Water, Cumberland ! Plankton of Grasmere,
Westmoreland !
Wales. — Near Conway and Llvn Elsie, Carnarvon-
shire !
Scotland. — Plankton of Lochs Katrine and Achrav,
Perth ! In the plankton of Loch na Cloiche Sgoilt,
Inverness ! Loch Beosetter, Bressay, Shetlands !
Ireland. — -Xear Glenties and near Lough Glentornan,
Donegal ! Ballynahinch, Galway !
Geogr. Distribution. — Galicia in Austria. Bengal.
Burma. United States. Brazil. Guiana.
In arranging the British species of Arthrodesmus we have
considered it most advisable to retain A. triangularis and its
allied forms as a separate species-group. All these forms
constitute a very natural series, easily recognizable and
well demarcated from the numerous forms of A. Incus by the
form of the semicells and the horizontal disposition of the
long spines. Perhaps the most distinctive feature of A.
triangularis is the elevated apex of the semicells, a character
which is only possessed by one form of A. Incus, namely, A.
Incus var. RaVfsii forma, subhexagona.
We find this species much more abundant in the plankton
than in any other situations, and in many of these plankton-
forms the cells are often conspicuously twisted at the isthmus
{vide PL CXIV, fig. 17).
ARTHRODESMUS. 99
Forma triquelra nob. (PI. CXXVIII, fig. 16.)
4
Staurastrum dejectum Breb. subsp. Tellamii W. & G. S. West, New Brit.
Freshw. Alg. 1894, p. 11, t. 2, f. 45 ; Alg. S. England, 1897, p. 492.
Vertical view triangular with retuse sides.
Length (without spines) 21 jjl; breadth without spines
21 li, with spines 48 lx; breadth of isthmus Cr-5/x.
England. — Gun wen Moor, Cornwall !
This Desmid lias little in common with Staurastrum dejectum,
whereas in front view it agrees very closely with some forms
of A. triangularis. It is in transitional forms of this kind
that the distinction between the genera Arthrodesmus and
Staurastrum breaks down. The occurrence of such forms,
however, does not seriously interfere with the view that it is
expedient to retain the genus Arthrodesmus.
Var. inflatus W. & G. S. West, (PI. CXIV, figs. 14-
15.)
A. triangularis forma West, Alg. W. Ireland, 1892, p. 168, t. 24, f. 19.
A. triangularis var. inflatus W. & G. S. West, Some Desru. IT. S. 1898,
p. 320; Cushman in Rhodora, vii, 1905, p. 261.
Semicells much inflated, angular-elliptic, apices
elevated and generally slightly truncate or faintly
retuse in the middle, more rarely entirely convex ;
spines stronger and very slightly divergent. Isthmus
very shortly cylindrical.
Length 24-38 fx ; breadth without spines 19-25 ix,
with spines 57-72 lx; breadth of isthmus 5'8-7'5/x;
thickness 10'5-12'5/x.
Wales. — Llvn Idwal, Carnarvonshire !
Scotland. — ^Bressay, Shetlands !
Geogr. Distribution. — United States.
This form occurs chiefly in the plankton and is readily
distinguished by its inHated semicells.
In the plankton of Cwellyn, Carnarvonshire, some large
forms with longer and stouter spines have been observed.
These wre have named " forma kobusta." Length 32-37 fx ;
breadth without spines 26"5-'27,5 /n, with spines 100-105 jx;
breadth of isthmus 8-8-7^. (PI. CXIV, fig. 1G).
100 BRITISH DESMIDIACEiE.
Var. subtriangularis (Borge) W. & Gr. S. West. (PL
CXV, figs. 1-3.)
A. Incus var. subtriangularis Borge, Algologiska Notiser, 1897, p. 212,
t. 3, f. 4.
A. triangularis var. hebridarum W. & G. S. West, Scott. Freshw. Plankton,
I. 1903, p. 542.
A. triangularis var. subtriangularis (Borge) W. & G. S. West, Freslnv.
Alg. Orkneys and Shetlands, 1905, p. 24, t. 2, f. 36 ; Further Contrib.
Plankton Scott. Lochs, 1905, p. 485 ; Comp. Study Plankton Irish
Lakes, 1906, p. 85 ; British Freshw. Phytoplankton, etc., 1909, p. 181 ;
Phytoplankton Engl. Lake Distr. 1909, p. 138.
A. granulatus Larsen, Ferskvandsalg. Vest-Gronl. 1907, p. 324, t. 7, f. 7.
Slightly larger, with more robust semicells as in
var. inflatus ; lower margins of semicells indented just
above the isthmus ; apex much elevated, convex, but
retuse in the middle; cell- wall commonly possessing
a number of irregularly scattered scrobiculations.
Length 30-42; breadth without spines 23-32 /x;
with spines 75-84*5 /x; breadth of isthmus 8-8'5/x.
England. — In the plankton of Ennerdale Water
and Thirlmere, Cumberland ! Plankton of Codale and
Easdale Tarns, Westmoreland!
Wales. — Plankton of Llynau Dywaunedd, Carnar-
vonshire !
Scotland. — Frequent in the Scottish plankton,
especially in the lakes of Sutherland, Ross, Inverness,
Argyll (Borge), and the Outer Hebrides ! Shetlands \
Ireland. — Lakes near Recess, and between Clifden
and Roundstone, Galway !
Geogr. Distribution. — West Greenland.
This northern variety of A. triangularis appears to be
mostly confined to the plankton. In the '' pinchecl-in ;
character of the semicells just above the isthmus it is strictly
analogous to the var. indentatus of A. Incus. The scrobicii-
lations on the cell-wall are variable both in number ami
disposition, and are sometimes very indistinct.
A most interesting- form with triangular semicells (in
vertical view) occurred in the plankton of Easedale Tarn.
Westmoreland. This we have named fonna teiqdetra \\ .
& G. S. West, < Phvtoplankton Engl. Lake Distr/ 1909,
p. 288, and text-fig. bd. (PI. CXV, fig. 4). It is another of
those connecting forms between the genera Arthrodesmus and
ARTHRODESMUS. 101
Staurastrum, and some individuals were observed in which one
semicell was of the normal elliptic form whereas the other
was triangular (vide PI. CXV, fig. 5).
The recently described A. granulatus Larsen, which, by
the way, is scrobicidate and not granulate, is merely an
arctic form of this variety in which the spines are a little
reduced.
3. Arthrodesmus quiriferus W. & Gr. S. West,
(PI. CXV, figs. 6, 7.)
Arthrodesmus quiriferus W. & G. S. West, Scott. Freshw. Plankton, I.
1903, p. 542, t. 17, f. 9, 10; Brit. Freshw. Phytoplankton, etc., 1909,
p. 181.
Cells of medium size, a little longer than broad
(without spines), fairly deeply constricted, sinus very
widely open and rounded ; semicells obversely sub-
triangular with convex sides and a widely concave
apex, each angle furnished with a strong, straight,
divergent spine of great length. Vertical view elliptic
with a strong, long spine at each pole. Cells usually
twisted at the isthmus.
Zygospore unknown.
Length without spines 28-31 /x, ; breadth without
spines 21-23 /x,; length of spines 31-44 /i,; breadth of
isthmus 6-9*5 fx; thickness 10-11 /x.
Scotland. — In the plankton of Loch Shin, Suther-
land ! In the plankton of Loch Laxadale, Harris,
Outer Hebrides !
In the plankton of Loch Shin this species was very
abundant. It is distinguished from the biradiate form of
Staurastrum jaculiferum by the outward form of the cells,
with refuse apices, and by the longer spines. The cells are
almost invariably twisted at the isthmus.
Forma compacta. (PI. CXV, fig. 18.)
Semicells stouter, sinus not quite so widely open and
rather narrowed towards the extremity; spines not
quite so long.
Length without spines 30 /x ; breadth without spines
102 BRITISH DESMIDIACK.D.
28 ix ; length of spines 3 1-36 /x; breadth of isthmus
9-5 p.
Hab. — In the plankton of Loch Shin, Sutherland!
4. Arthrodesmus crassus W. & G. S. West.
(PL CXV, figs. 8-11.)
Arthrodesmus crassus W. & Gr. S. "West, Scott. Freshw. Plankton, I. 1903,
p. 541, t. 14, f . 8, 9 ; Further Contrib. Plankton Scott. Lochs, 1905, p.
485 ; Comp. Study Plankton Irish Lakes, 1906, p. 85 ; Nordst. Index
Desmid. Supplem. 1908, p. 43 ; W. & G. S. West, Brit. Freshw. Phyto-
plankton, etc., 1909, p. 181 ; Phytoplankton Engl. Lake Distr. 1909,
p. 288, fig. 5 B.
Staurastrum Sarsii Huitfeldt-Kaas, Plankton. Norske Vande, 1906, pp. 55,
156, t. 1, f. 11-17 [figures incorrect].
Cells small, about as long as broad (without the
spines), moderately constricted, sinus very widely open
and slightly acuminate ; semicells obversely subtrian-
gular, sides veiy slightly convex, apex widely convex,
each angle furnished with a very short acute spine.
Vertical view broadly elliptic-fusiform, poles acute
and furnished with a very short spine. Chloroplasts
axile, one in each semicell with a single central
pyrenoid.
Zygospore unknown.
Length 19-5-24 [x ; breadth without spines 19-23 jx ;
length of spines 1*5 [x ; breadth of isthmus 9*5-12'5 jx ;
thickness 11*5-13 jx.
England. — Plankton of Ennerdale Water, Cumber-
land ; and Hawes Water, Westmoreland !
Scotland. — Plankton of Lochs Cuthaig, Fadaghoda,
Mor Bharabhais, and Roinebhall, Lewis, Outer
Hebrides !
Ireland. — Plankton of Louo-h Currane, Kerrv !
Grog r. Distribution. — Norway.
This characteristic plankton-species is found in all the
British lake-areas except the Welsh, in which it has not yet
been observed.
It is of the same size as the Brazilian A. psilos'poriis Nordst.
& Lofgr. (in Wittr. & Nordst. fAlg. Exsic/ 1883, no. 558),
but is relatively shorter, and the semicells are never retuse
ARTHRODESMUS. 103
either at the sides or the apex; the vertical view has also
more acute poles.
In its general form A. crassus agrees fairly well with A.
controversies W. & G. S. West, but the latter is very much
smaller and more delicate, with a broadly elliptic vertical
view.
This species sometimes occurs in great abundance in the
plankton, the cells secreting a large quantity of mucus.
The fibrillar structure of this mucus was described by
Huitfeldt-Kass in 1906 as an armature of spines.
5. Arthrodesmus controversus W. & G-. S. West.
(PL CXV, figs. 12-14.)
Arthrodesmus ? glaucescens Wittr. forma convesea West, Alg. W Ireland,
1892, p. 170, t. 22, f . 10 ; Alg. Engl. Lake Distr. 1892, p. 730, t. 9, f . 27 ;
Larsen, Ferskvandsalg. Vest-Gronl. 1907, p. 324.
A. controversus W. & G. S. West, New Brit. Freshw. Alg. 1894, p. 9 ; Nordst.
Index Desm. 1896, p. 81 ; W. & G. S. West, Alg. N. Ireland, 1902, p. 59.
Cells minute, a little longer than broad (without the
spines), moderately constricted, sinus obtuse-angled
and very widely open, with an acuminate apex; semi-
cells obversely subtriangular or cuneate, sides and
apex convex, angles furnished with a very minute
short spine. Side view of semicell subcircular.
Vertical view broadly elliptic, with a very minute
spine at each pole. Cell- wall smooth.
Zygospore globose, furnished with long, simple
spines.
Length 10*5-12 fx ; breadth without spines 10-11*5 jx,
with spines 11-13*6^; breadth of isthmus 5-5*9 /a ;
thickness 5 5-6*5 /a; diam. zygosp. without spines
16*5 /x, with spines 29 fx.
England. — Hawkshead, Lancashire ! Wastdale,
Cumberland (with zygospores) !
Ireland. — Near Lough Magrath, Donegal ! Slieve
Donard, Down ! Creggan Lough, Mayo ! Adrigole,
Cork !
The minute plant originally described by Wittrock as
" ArtJirodesmas ? glaucescens" has since been found to
belong to the genus Tetrapedia. As this minute alga is a
typical Desmid in every respect, and conjugates to form
104 BRITISH DESMIDIACEJI.
spiny zygospores, it was necessary that it should be re-
named.
A. controversies is probably the smallest species of the
genus. It resembles A. crassus in outward form, but is much
smaller and more delicate, and the vertical view is elliptic
Avith broadly rounded poles.
6. Arthrodesmus phimus Turn.
(PI. CXV, figs. 15, 1G.)
Arthrodesmus phimus Turn. Freshw. Alg. E. India, 1893, p. 136, t. 12, f. 9;
Nordst. Index Desmid. 1896, p. 200 ; W. & G. S. West, Freshw. Alg.
Ceylon, 1902, p. 192, t. 22, f. 21.
Cells small, about as long as broad (without the
spines), sometimes longer, sometimes broader, deeply
constricted, sinus subrectangular with a rounded
or an acuminate extremity; semicells obversely
subtriangular or widely cuneate, sides convex, apex
widely retuse, each angle slightly rounded and fur-
nished with a very short divergent spine. Vertical
view narrowly elliptic, poles rounded, each with a very
short spine. Cell-wall smooth.
Zygospore unknown.
Length 1 9-5-26 ll ; breadth without spines 20-25-5 yu, ;
length of spines 3-4//,; breadth of isthmus 6-5-7*5 ll.
Geogr. Distribution. — India. Ceylon.
The typical form of this species is not known to occur in
the British Islands.
Var. occidentalis W. & G. S. West, (PL CXV,
fig. 17.)
A. phimus var. occidentalis W. & G. S. West, Ate. N. Ireland, 1902, p. 59,
t.2,f.l7. * P
A small variety, with the cells broader than long,
the angles less produced, and the sinus somewhat less
open.
Length 14-14-6//,; breadth without spines 16'3-
17*3 ll, with spines 19-19-4 ll ; breadth of isthmus 5*7-
6-2 ll ; thickness 7'2 ll.
Ikeland. — Lough Anna, Donegal !
ARTHRODESMUS. 105
Var. hebridarum var. nov. (PL CXV1I, fig. 22.)
A small variety, with the angles of the semicells
somewhat produced and narrower ; sides of semicells
faintly retuse, and apex very slightly convex in the
middle portion only.
Length 15 jx; breadth without spines 18'Oju,, with
spines 21*5^; breadth of isthmus 6/n.
Scotland. — Benbecula, Outer Hebrides !
7. Arthrodesmus Bulnheimii Racib.
(PI. CXVI, figs. ] , 2.)
Arthrodesmus Incus Bulnh. in Hedwigia, 1861, p. 51, t. 9, f. 3.
A. Bulnheimii Racib. Desm. Nowe, 1889, p. 95, t. 16, f. 17 ; Eichler, Mat.
flor. Miedz. 1894, p. 129, t. 3, f . 34 ; Nordst. Index Desmid. 1896, p. 70.
Cells of medium size, or sometimes less, a little longer
than broad (without the spines), deeply constricted,
sinus narrowly linear with a slightly dilated apex;
semicells transversely subrectangular, sometimes very
slightly widened from base to apex, sides and apex
slightly convex, angles slightly rounded, each apical
angle furnished with a long, stout, divergent spine.
Cell-wall smooth, punctate, or more rarely with a few
irregularly scattered scrobiculations. Vertical view
elliptic with a stout spine at each pole.
Zygospore unknown.
Length without spines 32-42 /jl; breadth without
spines 30-40 /x; length of spines 18-27 /x; breadth of
isthmus 7-5-9-6 /x; thickness 16-20//,.
Scotland. — Rhiconich, Sutherland! Harris, Outer
Hebrides !
Geogr. Distribution. — Germany. Poland. Lapp-
mark in Norway (form).
A. Bitlnlteimii is a very rare Desmid characterized by the
rectangular semicells and the closed linear sinus.
Var. subincus var. nor. (PI. CXVI, fig. 3.)
A. Incus "forma apicibus constanter convexis" West, Alg. W. Ireland,
1892, p. 168.
A. Incus var. valiclus forma minor W. & G. S. West, Alg. N. Ireland, 1902,
p. 58, t. 2, f. 15.
106 BRITISH DESMIDIACEZE.
A somewhat smaller variet}^ with the basal angles
of the semicells rounded to such a degree that the
semicells are almost obversely semicircular.
Length without spines 23-26 ll, with spines 51-54 /x;
breadth without spines 25—28 ll, with spines 45-54 ll ;
breadth of isthmus 6*5—8 ll.
Wales. — Capel Curig and Llyn-y-cwm-ffynon, Car-
narvonshire !
Scotland. — Khiconich, Sutherland; Lewis and
Harris, Outer Hebrides !
Ireland. — Near Grlenties and Louo-h Anna, Donegal !
Ballynahinch and near Roundstone, Galway ! Grlen-
garriff, Cork !
We had for some time erroneously regarded this Desmid
as a form of Arthrodesmus Incus, as its proper place in a
systematic scheme appears to he with A. Bulnkeimii. No
form of A. Incus ever possesses a closed sinus with a dilated
extremity, and we consider that this one character is alone
sufficient to releo-ate it to A. Bulnkeimii.
A. Bulnkeimii var. suhincus is a western type of Desmid,
and iu parts of Lewis, Harris, and the west of Ireland it is
sometimes very abundant.
8. Arthrodesmus convergens Ehrenb.
(PI. CXVI, figs. 4-13.)
Arthrodesmus convergens Ehrenb. Infus. 1838, p. 152, t. 10, f. 18; Hass.
Brit, Freshw. Alg. 1845, p. 357, t. 85, f. 9 ; Ralfs, Brit. Desm. 1848,
p. 118, t. 20, f. 3; Kiitz. Spec. Alg. 1849, p. 176; Arch, in Pritch.
Infus. 1861, p. 737; Lund. Desm. Suec. 1871, p. 54; Kirchn. Alg.
Schles. 1878, p. 156; Wolle, Desm. U. S. 1884, p. 95, t, 23, f. 19-21;
Cooke, Brit, Desm. 1887, p. 136, t. 47, f. 1 ; Hansg. Prodr. Algenfl.
Bohm. 1888, p. 203, f. 117, and p. 251; Nordst. Freshw. Alg. N. Zeal.
1888, p. 45; De Toni, Syll. Alg. 1889, p. 1058; West, Alg. N. Wales,
L890, p. 292; Heimerl, Desm. alp. 1891, p. 603; West, Alg. W. Ireland,
1892, p. 169 ; Alg. Engl. Lake Distr. 1892, p. 730 ; Liitkem. Desm.
Attersees, 1893, p. 559 ; Boy & Biss. Scott. Desm. 1894, p. 40 ; W. & G.
S. West, Some N. Amer. Desm. 1896, p. 254, t, 16, fig. 3 ; Nordst. Index
Desmid. 1896, p. 81 ; W. & G. S. West, Alg. S. England, 1897, p. 497 ; G. S.
West, Variation Desm. 1899, p. 397, 398 and fig. xylogr. 4 ; Liitkem.
Desm. Millstattersees, 1900, p. 70 ; W. & G. S. West, Alga-fl. Yorks.
1901, p. 108 ; Alg. N. Ireland, 1902, p. 58 ; Hirn, Desm. Finland, 1903.
p. 5 ; W. & G. S. West, Scott, Freshw. Plankton, I. 1903, p. 528 ;
Borge, Alg. erst. Eegnell. Exped., II. Desmid. 1903, p. 103 ; Larsen,
Freshw. Alg. E. Greenland, 1904, p. 81 ; W. & G. S. West, Freshw. Alg.
Orkneys and Shetlands, 1905, p. 23 ; Cnshman in Ehodora, vii, 1905,
ABTHKODESMUS. 107
p. 260 ; W. & G. S. "West, Further Contrib. Preshw. Plankton Scott.
Lochs, 1905, p. 4S5 ; Borge, Beitrage, Alg. Schweden, 1906, p. 49 ; W. &
G. S. West, Brit. Freshw. Phytoplankton, etc., 19(J9, p. 181; Phyto-
plankton Engl. Lake Distr. 1909, p. 138 ; Hustedt, Desm. et Bacill.
aus Tirol, 1911, p. 336.
Staurastrum convergens Menegh. Synops. Desm. 1840, p. 228; Ealfs in
Ann. Mag. Nat. Hist, xv, 1845, p. 158, t. 12, f. 1 ; Eacib. Desm. Krakow,
1884, p. 16 (sep.), t. 1, f. 8.
Scenodesmus convergens Kiitz. in Linnrea, xvii, 1843, p. 74.
Euastrum convergens Kiitz. Phycol. germ. 1845, p. 136.
Euastrum (Tetracanthium) convergens Nag. Gatt. einz. Alg. 1849, p. 114,
t. 7, f. C 1.
Cosmarium convergens De Bary, Conj. 1S58, p. 72.
Didymidium (Staurastrum) convergens A. ellipticum Beinsch, Algenn.
Frank. 1867, p. 154.
Staurastrum convergens a armigera Jacobs. Desm. Danem. 1876, p. 203
[forma injiata et forma attenuata].
Xanthidium convergens Delp. Desm. subalp. 1S77, p. 76, t. 14, f. 13-23.
Artlirodesmus convergens a typica, (3 curta,et y minor Turn. Freshw. Alg.
E. India, 1893, p. 134, t. 11, f. 32, 41, 42; t, 12, f. 3.
Cells of medium size, about ly or 1^ times broader
than long* (without the spines), very deeply constricted,
sinus opening widely outwards from a narrow and
sublinear extremity; semicells more or less elliptic,
usually with one margin (and generally the dorsal
margin) slightly more convex than the other, lateral
angles sometimes rounded-conical, each normally
furnished with a rather short and slightly incurved
spine. Vertical view rather narrowly elliptic, with
a short spine at each pole. Cell-wall smooth or
delicately punctate. Chloroplasts as a rule axile with
a single central pyrenoid in each semicell, but inclined
to be variable.
Zygospore globose and smooth.
Length 33-54 p; breadth without spines 40-04 /x,
with spines 50-90*/, ; length of spines 5*5-] 5 fi ; breadth
of isthmus 10-17 /x; thickness 18-26/x ; diam. zygosp.
39-48 fx.
England. — Cumberland! Westmoreland ! (Haifa).
Lancashire! (Ealfs). W., N., and E. Yorks! Cheshire
(Balfs). Leicestershire (Boy). Bucks! Warwicks !
Gloucester (Ra Jfs). Herts (Hassall). Surrey! Sussex
(Ealfs). Kent (Balfs). Hants! (Roy). Devon!
Cornwall! (Rolfs).
Wales. — Capel Curig (common in the plankton of
108 BRITISH desmidiaueje.
the lakes) and Llyn Idwal, Carnarvonshire ! Llyn
Coron, Anglesey !
Scotland. — General! (Boy Sf Bissett). Lewis and
Harris, Outer Hebrides ! Orkneys ! Shetlands ! Scarce
in the plankton !
Ireland. — Donegal! Armagh! Dublin and Wick-
low (Archer), Galway ! Kerry! Cork!
Geogr. Distribution. — France. Germany. Austria.
Hungary. Italy. Norway. Sweden. Denmark.
Bornholm. Finland. N. and S. Russia. Greenland.
Nova Zembla. Central China. Japan. India.
New Zealand. Abyssinia. Central and E. Africa.
United States. Brazil. Paraguay.
This most characteristic species exhibits considerable varia-
tion in the degree of development of the spines, and the
semicells are also slightly variable in form. These points
can be noticed by an inspection of figs. 4-12 on PI. C'XVI.
Examples are often found in which the spines of one semi-
cell are normal and those of the other reduced or absent, and
by further division of such a plant a specimen may be
produced in which the spines are entirely absent {vide
PI. CXVT, fig. 10). On the division of this spineless cell,
however, the newly-formed semicells may, and usually do,
develop typical spines. Thus, a character which may be
entirely lost in a few individuals, as a result of repeated
vegetative division, is frequently reproduced at its maximum
in a succeeding division (Consult PI. CXVT, fig. 11, and the
remarks under Cosmarium Regnesi in Vol. Ill, p. 38).
The production of occasional spineless individuals of this
Desmid leads one to the conclusion that Arthrodesmus con-
vergent* originated in the fh\st instance from a Cosmarium of
the nature of G. depression (Nag.) Lund. In fact, the
resemblance between A. convergens and Cosm. depressum is
so very close that many suggestions have been made as to
their specific identity. These suggestions are, however,
based upon insufficient knowledge of these Desmids. It
must be remembered that the vegetative divisions of Cos-
marium depressum always produce unarmed cells similar to
the parent generation, but that the spineless cells of A.
convergens are nevertheless truly A. convergens with all those
inherited characters which will probably result in the pro-
duction of full-grown typical spines in the new semicells of
the next division;
AETHE.ODESMUS. 109
When in the plankton the spines of A. convergens are
frequently much reduced.
The form recorded as " forma membrana irregulariter
punctata" (cf. W. & G. S. West, 'New Brit. Freshw. Alg.'
1894, p. 9) cannot be regarded as a distinct form, as many
specimens of this species clearly show a finely punctate
cell- wall.
In a variety of this species (var. incrassatus Gutw.) which
occurs in Austria and in the United States the cell-wall is
thickened by two transverse bars of cellulose stretching-
across the semicell on each side of the apex.
9. Arthrodesmus subulatus Kiitz.
(PL OXVI, fig. 14; PI. CXVIT, fig. 1.)
Arthrodesmus subulatus Kiitz. Spec. Alg. 1849, p. 176 ; Nordst. Desm.
Brasil. 1870, p. 232, t, 4. f. 59 [forma major] ; Wolle, Desm. U. S. 1884,
p. 96, t, 24, f. 11, 12 ; De Toni," Syll. Alg'. 1889, p. 1059 ; Borges. Desm.
Brasil. 1890, p. 43, t. 5, f. 57 [forma major] ; Turn. Freshw. Alg. E.
India, 1893, p. 133 [forma media and forma minor] ; Roy & Biss. Scott.
Desm. 1894, p. 41 ; West, Alg. Madag. 1895, p. 72, t. 9, f. 32, 33 ; Some
N. Amer. Desm. 1896, p. 254 ; Borge, Alg. erst. Begnell. Exped. II.
Desmid. 1903, p. 103 ; W. & G. S. West, Scott. Freshw. Plankton, I,
1903, p. 528.
A. convergens Ehrenb. var. subulatus (Kiitz.) Rabenh. Flor. Eiu-op. Alg.
Ill, 1868, p. 227.
Cells of medium size, about as long as broad (without
the spines), deeply constricted, sinus widely open from
a more or less subacuminate apex ; semicells elliptic-
obsemicircular, ventral margin much more convex
than the dorsal margin (almost semicircular), lateral
angles somewhat rounded, each furnished with a long,
stout, straight, and horizontally disposed spine.
Vertical view elliptic, each pole furnished with a long
straight spine. Cell-wall finely punctate.
Z}'gospore globose and smooth.
Length 28'4— 50 [x; breadth without spines 27-54 /a,
with spines 52-100 /u, ; breadth of isthmus 7-13'5/x;
thickness 15-22 /a; diam. zygosp. 30-36 [x.
Scotland. — Slewdrum, Cambus O'May, and Glen
Clunie, Aberdeen (Roy Sf Bissett).
Ireland. — Dublin ancl Wicklow (Archer).
Geogr. Distribution. — India. Madagascar. Abys-
sinia. United States. Brazil. Paraguay.
110 BRITISH DESMIDIACE.^.
Arthrodesmus suhulatus is much more frequent in tropical
latitudes than in temperate countries. In its typical form it
is easily distinguished from A. convergens by the shape of its
semicells and the long, horizontally-placed spines.
Forma americana (Turn.) TV & Gr. S. West. (PI.
CXVII, figs. 4, 5.)
A. Incus var. americanus Turn. New and Rare Desm. 1885, p. 937, t. 16,
f. 17 ; De Toni, Syll. Alg. 1889, p. 1057.
A. triangularis var. americanus (Turn.) West, Alg. W. Ireland, 1892,
p. 169.
A. elegans West, Alg. W. Ireland, 1892, p. 169, t, 22, f. 7 [gelatinous pro-
cesses described as " spinis brevibus delicatis truncato-bif'urcatis/'J
A. suhulatus forma media Turn. Freshw. Alg. E. India, 1893, p. 133, 1. 11,
f . 36, 37 ; t. 12, f. 4.
Differs from the type only in the long spines being
slightly convergent, and in the semicells being a little
less turgid (in outline rather more triangular).
Length 26-32 /x ; breadth without spines 22*5-30 fx,
with spines 62-65 jx ; length of spines 16-22 fx ; breadth
of isthmus 7-10//,; thickness 11-14 jx.
Ireland. — Lakes between Clifden and Eoundstone,
near Recess, and Ballvnahinch, Galwav !
Geogr. Distribution. — India. United States.
When A. elegans was described from Ballvnahinch it was
not realized that the short emarginate " spines " were only
tough mucilaginous processes which had been secreted through
pores in the cell-wall. Similar "spines" or "processes" are
frequently met with in this genus (consult PI. CXIII, fig. 15,
and PI. CXIV, fig. 5 c) and they often become quite hard ami
resistant, although they consist only of the more gelatinous
pectose constituents of the cell-wall. Mucous projections
(from the pores in the cell-wall) of a precisely similar nature
have been described and figured by Lutkemuller in A.
octocomis (consult Liitkem. (Zellmembr. Desmid.' 1902, p. 412,
t. 18, f. 17).
Var. subaequalis var. nov. (PI. CXVII, figs. 2,3.)
A suhulatus as recorded by W. A G. S. West, Alg. X. Ireland. 1902, p. 58;
Scott. Freshw. Plankton, I, 1903, p. 528.
Cells proportionately wider (without the spines) ;
semicells more narrowly elliptical with a less con-
ARTHRODESMUS. Ill
spicuous difference in convexity between the ventral
and dorsal margins ; spines shorter and more slender.
Length 31-38 /x; breadth without spines 31-42 fi,
with spines 52-65 p; long. spin. 10'5-11'5/x; breadth
of isthmus 8-12 fx; crass. 16-19*5 ft.
Scotland. — Plankton of Loch Nan Eun, N. TJist,
Outer Hebrides !
Ireland. — Lough Gartan, Donegal !
10. Arthrodesmus octocornis Ehrenb.
(PI. CXVII, figs. 6-10.)
Arthrodesmus octocornis Ehrenb. Infus. 1838, p. 152; Hass. Brit. Freshw.
AJg. 1815, p. 357, t. 85, f. 11 ; Arch, in Pritch. Infus. 1861, p. 736; Rabenh.
Flor. Europ. Alg. Ill, 1868, p. 225 ; Lund. Desm. Suec. 1S71, p. 55 ;
Kirchn. Alg. Schles. 1878, p. 156 ; Wolle, Desm. U. S. 1884, p. 97, t. 24, f.
22 : Cooke, Brit. Desm. 1887, p. 134, t. 47, f . 2 ; De Toni, Syll. Alg. 1889,
p. 1063; West, Alg. N. Wales, 1890, p. 291 ; G-utw. Flor. Glon. Okolic
Lwowa, 1891, p. 64 ; West, Alg. W Ireland, 1892, p. 167 ; Alg. Engl.
Lake Distr. 1892, p. 730 ; Roy & Biss. Scott. Desm. 1894. p. 41 ; Nordst.
Index Desmid. 1896, p. 187 ; W. & G. S. West, Alg. S. England, 1897,
p. 496, t. 6, f. 16 ; Schmidle Lappmark Susswasseralgen, 1898, p. 42 ;
Liitkem. Desm. Millstattersees, 1900, p. 71 ; W. & G. S. West, Alga-fl.
Torks. 1901, p. 109; Borg. Freshw. Alg. Faeroes, 1901, p. 229; W.
& G. S. West, Alg. N. Ireland, 1902, p. 57 ; Liitkem. Zellmembr. Desmid.
1902, t. 18, f. 17 ; W. & G. S. West, Scott. Freshw. Plankton, I. 1903,
p. 528; Larsen, Freshw. Alg. E. Greenland, 1904, p. 81; W. & G. S.
West, Further Conti'ib. Freshw. Plankton Scott. Lochs, 1905, p. 485 ;
Borge, Beitrage Alg. Schweden, 1906, p. 49 ; Larsen, Ferskvandsalg.
Vest-Gronl. 1907, p. 325; W.& G. S. West, Brit. Freshw. Phytoplankton,
etc., 1909, p. 181; Hustedt, Desm. tt Bacill. aus Tirol, 1911, p. 336,
f. 25.
Micrasterias octocornis Menegh. Synops. Desm. 1S40. p. 216.
Staurastrum ? octocome Ralfs in Ann. Mag. Xat. Hist. 1845, xv, p. 159,
t. 12, f . 3.
Euastrum octocorne Kiitz. Phycol. germ. 1845, p. 134.
Xanthidium ? octocome (Ehrenb.) Ralfs, Brit. Desm. 1848, p. 116, t. 20,
f. 2 a-e ; Archer in Q. J. Micr. Sci. 1869, p. 423 ; Gay, Monogr. loc. Conj.
1884, p. 77 ; Hirn. Desm. Finland, 1903, p. 24.
Euastrum octacanthum Pertv in Mittheil. d. naturforseh. Gesellsch. in
Bern, 1S49, p. 174.
Didymidiuni (Xanthidium) octocorne Reinsch, Algenfl. Frank. 1867, p. 127.
Xanthidium octocome forma minor Jacobs. Desm. Danem. 1876, p. 211.
Arthrodesmus Lapczynskii Gutw. Nonn. alg. nov. 1896, p.' 57, t. 7, f. 68.
Cells small, about 1\ times longer than broad
(without the spines), deeply constricted, sinus a wide,
almost semicircular excavation: semicells tranversely
trapeziform-rectangular, sides and apex concave, angles
slightly rounded and each furnished with one fairly
112 BRITISH DESMIDrAOEiE.
long straight spine. Vertical view elliptic, with one
straight spine showing at each rounded pole.
Zygospore globose or subglobose, furnished with a
few simple straight spines, about 8 of which show at
the periphery ; wall of spore with a broad and slightly
projecting thickening at the base of each spine.
Length without spines 17-27 /a, with spines 30-
42 /a ; breadth without spines ] 4-3-19 ll, with spines
28-35"5/a; breadth of isthmus 4,2-7*6/x; thickness
G'5-9 [m ; diam. zygosp. without spines 15//,, with
spines 28 fx.
England. — Cumberland ! Westmoreland ! (Rolfs ;
Bissett). W. and N. Yorks ! Burnham Beeches,
Bucks! Gloucester (Rolfs). Surrey! (Ralfs) ; zygo-
spores from Puttenham Common! Sussex (Ralfs).
Hants! (Ralfs). Devon! Cornwall! (Ralfs).
Wales. — Llyn Bodgynwydd, Capel Curig (Goolce
Sf Wills), Llyn Ogwen, Llyn Idwal, Llyn Bochlwyd,
Glyder Fach (at 2200 ft.), Llyn-y-cwm-ifynon,
Snowdon, and Moel Siabod, Carnarvonshire !
Scotland. — General ! ; zygospores from Aberdeen,
Kincardine, and Perth (Roy Sf Bissett). Outer
Hebrides ! Scarce in the plankton !
Ireland. — Donegal ! Londonderry ! Dublin and
Wicklow (Archer). Galway ! Mayo! Kerry! Cork!
Geogr. Distribution. — France. Germany. Poland.
Austria and Galicia. Italy. Norway. Sweden.
Denmark. Bornholm. Finland. N. Eussia. Faeroes.
Iceland. Greenland. Mongolia. Japan. Burma.
Ceylon. Australia. United States.
A. octocomis is a very characteristic species with a wide
distribution. It scarcely needs comparison with any other
species, and in the British Islands it exhibits little variation.
The "/3 major Ralfs" has been transferred to XanthicUum
Smithii, a Desmid to which we think it more rightly belongs
(consult page 62).
A trigonal variety (var. trlgonum) was described by Boldt
from Greenland in 1888, and has since been found in West
Greenland by Larson.
Lutkemuller (' Desin. Millstattersees/ 1900, p. 13) has given
ARTHRODESMUS. 113
clear proof that A. LapczynsJcii Gutw. is merely typical A.
octocornis, Gutwinski having fallen into the error so repeatedly
made in dealing with Desmids of regarding certain of the
mucous rods connected with the pores in the cell-wall as an
armature of small spines.
Messrs. Eoy and Bissett have recorded from Scotland
(from a pool on Culblean, beside the old road from Tarland
to Ballater, Aberdeen) the Desmid described by Jacobsen
('Desm. Danem.' 1876, p. 211, t. 8, f. 28) as Xnnthidium
octocorne forma impar. We have not seen this Desmid and
are very doubtful concerning its inclusion under Arthro-
desmus octocornis, as it seems to agree more closely with forms
of Xanthidium Smithii. Jacobsen's description and figure
are insufficient to determine this point. The lower angles of
the semicells possess one long spine and the upper angles two
long spines. We give a copy of Jacobsen's figure (PI. CXVI1,
fig. 21).
11. Arthrodesmus bifidus Breb.
(PI. CXVII, figs. 11-13.)
Arthrodesmus bifidus Breb. Liste Desm. 1856, p. 135, t. 1, f. 19 ; Arch, in
Pritch. Infus. 1861, p. 736 ; Rabenh. Flor. Europ. Alg. Ill, 1868, p. 226 ;
Lund. Desm. Snee. 1871, p. 55 ; Boldt, Sibir. Chlorophy. 1885, p. 109 ;
Cooke, Brit. Desm. 1887, p. 137, t. 48, f. 2 [figures erroneous! ; De
Toni, Syll. Alg. 1889, p. 1064; Gutw. Fior. Glon. Okolic Lwowa, 1891,
p. 64, t. 3, f. 8; Roy & Biss. Scott. Desm. 1894, p. 40; Nordst. Index
Desmid. 1896, p. 59; W. & G. S. West, Alg. S. England, 1897, p. 496;
Some Desm. U. S. 1898, p. 319 ; Liitkem. Desm. Millstattersees, 1900,
p. 12 ; W. & G. S. West, Alg. N. Ireland, 1902, p. 57 ; Larsen, Ferskvand-
salger Vest-Gronl. 1907, p. 324.
Cells minute, about as long as broad, deeply con-
stricted, sinus open, subrectangular, with a minute
acuminate extremity ; semicells elliptic-lunate with
the angles upwardly divergent, apex slightly concave,
each lateral angle widely emarginate-bifid. Vertical
view narrowly elliptic, with a minute spine at each
rounded pole. Cell-wall smooth. Chloroplasts axile,
one in each semicell, with a central pyrenoid.
Zygospore unknown.
Length (including the minutely spinate angles) 10-
14 n ; Dreaclth 11-15*5 /x ; breadth of isthmus 3-5 • 6 /x ;
thickness 5-6 -5 ^.
England. — Burnham Beeches, Bucks ! Puttenham
VOL. IV. 8
114 BRITISH DESMIDIACE^.
and Thursley Commons, Surrey ! Roughter Moor,
Cornwall !
Scotland. — Ross, Inverness, Aberdeen !, Kincardine,
Perth !, Argyle (Boy 8f Bissett). Sutherland ! Lewis,
Outer Hebrides !
Ireland. — Near Glenties and Lough Anna, Donegal I
Dublin and Wicklow (Archer). Ballynahinch, Galway !
Geogr. Distribution. — France. Germany. Switzer-
land. Austria and Galicia. Sweden. Bornholm.
Poland. Greenland. Japan. Azores. United States.
This minute species is rather rare and liable to be over-
looked. Its characters are most distinctive, and it cannot
easily be confused with any other species of the genus.
Lundell gives measurements of Swedish specimens up to 18/*
in length and breadth.
Var. truncatus West. (PI. CXVII, fig. 14.)
A. bifidus Breb. var. truncatus West, Alg. N. Yorks. 1889, p. 293, t. 291r
f. 9 ; Alg. W. Ireland, 1892, p. 169 ; Alg-. Engl. Lake Distr. 1892, p.
730; Alg. S. England, 1897, p. 496; Alga-fl. Yorks. 1901, p. 109;
Alg. N. Ireland, 1902, p. hi.
Semicells subhexagonal, sides and apex straight ;
" angles " not emarginate but truncate, thus making
two angles (lateral and apical) on each side of the
semicell, each angle being furnished with a minute
spine.
Length (including minute spines) 10-15"5ju; breadth
10-14*4 /x ; breadth of isthmus 4*5-5 "7 fi.
England. — Bowness and Helvellyn, Westmoreland !
Strensall and Pilmoor, N. Yorks ! Thursley Common,
Surrey ! Keston Common, Kent !
Wales. — Moel Siabod, Carnarvonshire !
Ik eland. — Near Glenties, Donegal ! Ballynahinch,
Louo-li Derrvclare, and in small lakes between Clifden
and Roundstone, Galway !
Although distinctly rare, we have seen this variety oftener
than the type, from which it differs most markedly in the
angularity of its semicells.
One form of it was observed from Bowness, Westmoreland,
in which the semicells were entirely destitute of spines.
ARTHRODESMUS. 115
This curious form, unmistakable in its outline, we hare
named forma succisa W. & Gr. S. West (' New Brit. Freshw
Alg.' 1894, p. 9, t, 2, f. 52) ; length 12-5/u; breadth ll-o>'
breadth of isthmus 3 M ; thickness 6/1. (PI. CXVII, fig. 15).'
Var. latidivergens West. (PI. CXVII, fig. 16.)
A. bip.h's var. latodivergens West, Alg. W. Ireland, 1892, p. 169, t. 22,
f. 8.
Semicells with rather larger spines at the emarginate
angles, the two spines at each lateral angle being
placed exactly at right angles.
Length with spines 18 /x; breadth with spines 18 xi;
thickness 6*5 p.
Ireland. — Ballynahinch, Gaiway !
12. Arthrodesmus trispinatus W. & Gr. S. Wrest.
(PI. CXVII, fig. 17.)
Arthrodesmus trispinatus W. & G. S. West, Alg. X. Ireland, 1902, p. 57,
t. 2, f. 16 ; Gutw. Flor. Alg. Mont. Tatr. 1909, p. 466, t. 8, f. 40 [figures
very poor].
Cells minute, about as long as broad (without
spines), moderately constricted, sinus widely open and
rounded ; semicells transversely elliptic-oblong, with a
broadly concave apex, sides with three equal undula-
tions (three crests and two hollows) each furnished
with a short, stout spine, spines divergent. Vertical
view elliptic, showing the superposed spines at the
poles. Cell-wall smooth.
Zygospore unknown.
Length without spines 11*5 fi, with spines 17 ft;
breadth without spines 1 1 p, with spines 1 7 /x ; breadth
of isthmus 6*2 /x; thickness 7'o{jl; length of spines
3-3'5 /x.
Ireland. — Louoli Grartan, Donegal !
Geoijr. Distribution. — Galicia in Austria.
This plant is at once distinguished from all other species
of the genus by its small size and by the three spines on the
lateral margins of each semicell. It is perhaps nearest to
Arthrodesmus ineptus (Turn.) W. & Gr. S. West ( = XantJii-
dium ineptum Turn. ' Freshw. Alg. E. India/ 1893, p. 101,
116 BRITISH DESMIDIACE.E.
t. 12, f. 21), an Indian species with irregularly disposed
spines and cells of a different shape.
No living cells of this plant have yet been seen, and the
exact nature of the chloroplasts has not been determined.
We have suggested, therefore ('Alg. N. Ireland,' 1902,
p. 58), that it may be one of the Protococcales belonging to
the genus Tetra'edron. If such were the case then "A.
trispinatus" would to some extent resemble a Tetra'edron
which has been described on two separate occasions as one of
the Desmidiaceas ; first by Wille (' Ferskv. Alg. Nov. Semi].'
1879, p. 62, t. 13, f. 70) as " Sphserozosma excavatum Ealfs
var. Novai Semlise Wille," and secondly by Schmidle (' Beitr.
alp. Alg/ 1895, p. 350, t. 15, f. 9) as " Xanthidium alpinam."
13. Arthrodesmus tenuissimus Arch.
(PI. CXVII, figs. 18, 19.)
Arthrodesmus tenuissimus Arch. Palmoglcea and descrip. Mesot. 1864, p. 68
(sep. 28), t. 1, f. 50-55 ; Eabenh. Flor. Europ. Alg. Ill, 1868, p. 226 ;
Cooke, Brit. Desm. 1887, p. 137, t. 47, f. 3 [figures inaccurate] ; Anderss.
Sverig. Chlor. 1890, p. 13 ; Schmidle, Beitr. alp. Alg. 1896, p. 20 ; Nordst.
Index Desmid. 1896, p. 251 ; W. & G. S. West, Alg. N. Ireland, 1902,
p. 59 ; Lutkeni. Desm. Bohm. 1910, p. 497.
Xanthidium tenuissimum (Arch.) Turn. Freshw. Alg. E. India, 1893, p.
137.
Cells minute, a little broader than long (without
the minute spines), fairly deeply constricted, sinus
widely open, almost rectangular ; with a subacute
apex ; semicells subhexagonal, sides slightly concave
(almost straight), apex truncate, straight or slightly
concave, lateral angles each with a small, short,
horizontally-placed spine, apical angles each furnished
with a minute spine or mucro which is not easily seen
owing to its direction. Side view of semicell sub-
circular-depressed, with a minute divergent mucro on
each side of the apex. Vertical view broadly fusiform-
elliptic, poles acutely cuspidate, with a minute spine
on each side near the poles. Cell-wall smooth.
Chloroplasts axile, with a central pyrenoid in each
semicell.
Zygospore unknown.
Length 8-10 /x; breadth without spines 11— 11*5 /x,
ARTHRODESMUS. 117
with spines 12-5-1 3 "6 /a; breadth of isthmus 5'9-6/ot;
thickness 5-5*5 ti.
England. — Helvellyn, Westmoreland !
Wales. — Llyn Teyrn on Snowdon, Carnarvonshire !
Scotland. — Sutherland !, Ross, Aberdeen, Forfar !,
Perth (Boy Sf BisseM). Lewis and Harris, Outer
Hebrides !
Ireland. — Lough Fea, Londonderry ! Featherbed
Bog, Dublin Mountains (Archer). Ballynahinch,
Galway !
Geogr. Distribution. — France. Germany. Galicia
and Bohemia in Austria. Arctic Norway. Sweden.
This minute species is unlike any other in the genus. It
is very rare, but when it does occur it is often in quantity
and generally amongst submerged Sphagnum.
It is, perhaps, nearest to Xanthidium concinnum Arch., but
the semicells are of a somewhat different shape, the spines
on the lateral angles are much longer, and there is no central
papilla. The minute, paired apical spines do not occur in any
other species of Arthrodesmus .
Forma longispina /. nov. (PI. CXVII, fig. 20.)
A. tenuissimus Arch, as figured by West, Alg. N. Wales, 1890, t. 5, f. 10
[figure very poor and inaccurate as to detail] ; West, Alg. W. Ireland,
1902, p. 170, t. 22, f. 9.
Lateral angles of semicells with much longer,
horizontally disposed spines.
Length 8-12'5/x; breadth without spines 9-125 jx ;
with spines 27—31 /x ; lat. isthm. 4-5 /a; thickness
5*5-6 (x.
Walks. — Capel Curig, Carnarvonshire !
Ireland. — Ballynahinch and Lough Aunierin,
Galway !
Under this form we call attention to the Desmid described
by Raciborski as Arthrodesmus hexagonus var. tumida (' Desm.
Tapakoomas./ 1895, p. 33, t. 4, f. 13) from Bintish Guiana.
It appears to differ only in the central protuberance, and is
therefore one of those forms which connect the genera Arthro-
desmus and Staurastrum.
118 BRITISH DESMIDIACE^.
Genus 18. STAURASTRUM Meyen, 1829; em. Ralfs.
Meyen in Nova acta Acad. Caesar. Leop. Carol. Nat. cur. t. 14, LS2h (1829).
[Description very imperfect.]
Ehrenb. Infus. 1838, p. 142.
Kiitz. Phyc. gener. 1843, p. 163.
Ealfs in Ann. Mag. Nat. Hist, xv, 1845, p. 149.
Ealfs, Brit. Desm. 1848, p. 119.
Arch, in Pritch. Infus. 1861, pp. 720, 737.
Eabenh. Flor. Europ. Alg. Ill, 1868, p. 196.
Lund. Desm. Suec. 1871, p. 7.
Delp. Desm. subalp. 1873, p. 38.
Kirchn. Alg. Schles. 1878, p. 163.
Wolle, Desm. U. S. 1884, p. 119.
Cooke, Brit. Desm. 1887, p. 138.
Hansg. Prodr. Algenfl. Bohm. 1888, p. 210.
De Toni, Syll. Alg. 1889, p. 1136.
Turner, Freshw. Alg. E. India, 1893, p. 132.
G. S. West, Treatise Brit. Freshw. Algae, 1904, p. 171.
Wille in Engler & Prantl, Natiirlich. Pflanzenfam. 1909, p. 9.
Didymocladon Ealfs, Brit. Desm. 1848, p. 144; Delp. Desm. subalp. 1877,
p. 78 (sep. p. 174).
Pleurenterium (Lund.) Wille in Engler & Prantl, Natiirlich. Pflanzenfam.
1890, p. 11 [= Subgen. Pleurenterium Lund. Desm. Suec. 1871, p. 72].
Tempered Bougon in Le Micrographe preparateur, iv, 1896, p. 210.
Cells of very variable size, generally longer than
broad (excluding spines or processes), usually with a
radial symmetry; median constriction variable in
depth ; semicells most variable in outline, subcircular,
elliptic, subtriangular, campanulate, trapeziform, etc.,
with the angles frequently produced into holloa- processes
of variable length ; vertical view 3-5 (or even up to 11)
-angular or -radiate (rarely compressed). Cell-wall
smooth, punctate, scrobiculate, or granulate, or clothed
with spines of various kinds ; sometimes furnished
with flattened, emarginate, or spiny verruca?. Chloro-
plasts generally axile, one in each semicell, consisting
of a central mass containing one pyrenoid from which
lobes radiate into the angles or processes ; in a few
species sometimes parietal or partially so (often most
irregular) and sometimes axile, and containing several
pyrenoids.
Zygospores globose or angular, rarely winged or
furnished with blunt warts, commonly clothed with
long spines, which are simple or furcate at their
STAURASTEUM. 119
•extremities, and each often situated at the apex of a
mamillate or obtusely conical protuberance.
The genus Staurastrum is primarily distinguished by the
radial symmetry of the cells as seen in vertical view. It
embi'aces species of more varied character than any other
genus of Desmids.
Through some of the smooth species, and especially through
St. tortum, St. co$marioides,ii\i(\. St. Clepsydra Ya,r. sibiricum,th.e
geuus Staurastrum is closely related to certain species of Cos-
marium, and it is highly probable that most of the species of
Staurastrum wei'e evolved along various lines from the genus
Cosmarium. Specialization has been carried to a much greater
extent than in the latter genus, and the development of long,
hollow processes at the angles of the semicells is a character
which is practically confined to the genus Staurastrum.
All kinds of spiny forms occur in the genus, from those in
which a single spine is present at each angle to those in
which the whole surface of the cell is covered with spines.
All gradations occur from smooth to granulate species, from
granulate to asperulate and minutely-spined forms, and from
these to coarsely-spined forms.
All attempts to split up this genus on natural principles
have entirely failed. The relationships of the numerous species
are too complex and close, so that only arbitrary lines of
demarcation can be drawn. Even the genus proposed by
Ralfs as Dklymocladon completely breaks down on considering
all the known species with accessory processes, both smooth
and rough forms. St. furciyerum var. reductum is almost
sufficient in itself to show how unnatural such a genus would
be, and the various forms of St. leptacanthum, St. Tohopehali-
gense, and others, clearly show how impossible it would be
to define the limits of such a genus.
On the whole, it would seem most unwise to split up the
large genus Staurastrum, but, as in the case of the still
larger genus Cosmarium, it is more in accordance with our
knowledge of the genus to group the species into such
sections as will most clearly indicate their probable affinities.
The subgenus Pleurenterium founded by Lundell in 1871,
and raised to generic rank by Wille in 1890, is just as
untenable as Pleurot&niopsis amongst the Cosmaria. It was
founded to include those species of Staurastrum in which the
chloroplasts were parietal, and is in consequence one of the
most unnatural groups which could possibly be suggested.
It would include'" a few scattered species, having no relation-
120 BRITISH DESMIDIACE^.
ship with each other, in which the parietal disposition of
chloroplasts had been independently acquired. Moreover,.
this so-called parietal disposition of chloroplasts is a matter
for further investigation. In most cases careful examination
shows them nor- to be truly parietal, but of an irregular
character, and they may be axile in one semicell and parietal,
or partially so, in the other. One of the principal species
included by Lundell in his subgenus Pleurenterium was St.
grande Bulnh., but the careful investigations of Lutkemiiller
show that in most individuals of this species the chloroplasts
are axile. Also in St. Brasiliense var. Lundellii, another
Desmid placed by Lundell in Pleuretderium, the chloroplasts
are invariably axile.
As mentioned above, there is one feature possessed by a
considerable percentage of the species of Staura strum which
does not occur in any other genus of Desmids,* namely, the
production of the angles of the semicells into hollow pro-
cesses. We have, therefore, regarded this character as of
fundamental importance, and used it as a basis for the
primary division of the genus into two large groups of
species. In each division Ave have arranged the species under
several fairly well-defined sections.
The outline of the scheme is as follows : —
Division I. Angles of semicells not produced into processes.
a. Cells with only a slight constriction and a very small sinus,
semicells subcylindrical in the basal part and angular at the apex.
Section A. Cells subcylindrical, granulate or verrucose.
4 species.
Section B. Cells subcylindrical, smooth.
1 species.
b. Cells with a well-marked constriction and a deep sinus, semi-
cells 3-6-angled, or rarely compressed.
Section C. Cells smooth or punctate, without spines, verrucae,
or granules.
21 species.
Section D. Cells furnished with small granules, regularly or
irregularly disposed, often covering the whole cell- wall or sometimes
more or less restricted to the angles.
15 species.
* The only other known processes of this nature are those on the lobes of
a few species of Micrasterias, such as M. americana, M. Mahabuleshirarensis,
M. anomala, M. muricata, M. Nordstedtiana, etc., and those at the apices of
the elongated semicells of Triploceras.
STAURASTRUM. 121
Section E. Cells furnished with spines at the angles only, each
angle provided with single or binate spines, rarelv with three or
four.
About 29 species.
Section F. Cells with numerous spines, either clothing the
whole surface of the cell-wall or more or less restricted to the
vicinity of the angles.
About 21 species.
Section G-. Cells with verrucse, which are emarginate or very
much reduced and 2-3-spinate.
About 8 species.
Division II. Angles of semicells produced into processes.
a. Processes arising exclusively from the angles of the semicells,
and therefore all arising in the same horizontal plane.
Section H. Processes smooth (although usually emarginate,
furcate, or spinate at the extremity) .
About 9 species.
Section I. Processes rough, denticulate or spinate along their
whole length.
About 46 species.
b. Processes not arising exclusively from the angles of the semi-
cells, and therefore with their points of origin in more than one
horizontal plane.
Section J. Semicells with accessory processes, most commonly
of dorsal oi'iarin.
About 15 species.
The ten sections just enumerated not only meet all the require-
ments of the British species, but of all the known species of
Staurastrum. We have indicated, in most cases provisionally, the
number of British species of each section.
In most of these sections there are species of an intermediate
character of which the exact systematic position is somewhat doubt-
ful. To the best of our judgment we have placed these species
alongside their nearest relatives.
For greater convenience, a synopsis of the British species con-
tained in any section is given immediately in front of that section.
122 BRITISH DESMIDIACE.2E.
Section A.
Cells subcylindrical, granulate or verrucose.
* Semicells uniformly granulate. 1. St. Meriani.
* Semicells granulate in the upper part (or more rarely with
very short minute spines), with a basal ring of
verruca?.
t Three apical lobes of semicells spreading horizontally.
2. St. capital a in .
ft Three apical lobes of semicells upwardly divergent.
3. St. pileolatum.
*** Semicells verrucose both in the upper part and at the
base.
4. ,S7. rhubdophorum.
1. Staurastrum Meriani Reinsch.
(PI. CXVIII, figs. 4-6.)
Staurastrum Meriani Reinsch, Spec. Gen. Alg. 1867, p. 125, t. 23 D I,
fig. 1-11; Nordst. Norges Desm. 1873, p. 29; Wolle, Desm. U. S.,
1884, p. 132, t. 46, f. 17-19; Nordst. Desmid. Gronl. 1885, p. 10; Cooke,
Brit. Desm. 1887, p. 161, t. 55, f. 2 ; West, Desm. .Mass. 1S89, t. 3, f. 22 ;
Alg. N. Yorks. 1889, p. 293; De Toni, Syll. Alg. 1889. p. 1192; West,
Alg. N. Wales, 1890, p. 294; Hansg. Prodr. Algenfl. Bohm. ed. germ.
II, 1892, p. 259; West, Alg. W. Ireland, 1892, p. 179; Alg. Engl. Lake
Distr. 1892, p. 732; Roy & Biss. Scott. Desm. 1893, p. 22 (sep.) ; Nordst.
Index Desm. 1896, p. 169 ; W. & G. S. West, Alg. S. England, 1897,
p. 494; Liitkem. Desm. Millstattersees, 1900, p. 80; W. & Gt. S. West,
Alga-fl. Yorks. 1901, p. 103 ; Borg. Freshw. Alg. Faroes, 1901. p. 231 ;
W. & G. S. West, Alg. N. Ireland, 1902, p. 51 ; Larsen, Freshw. Alg.
E. Greenland, 1904, p. 98; W. & G. S. West, Freshw.. Alg. Orkneys and
Shetlands, 1905, p. 25'; Teodoresco, \ Mater, flor. alg.Rouman. Ib07, p.
185 ; Larsen, Ferskvandsalg. Vest-Gronl. 1907, p. 350.
Didymidium (Staurastrum) Meriani Reinsch. Algenfl. Frank. 1867, p. 160,
t, 12, f. 1.
Calocylindrus cylindricus (Ralfs) Racib. var. hexagona Racib. in Spraw.
Kom. fizyjogr. Akad. Urn. Krakow, xix, 1884, p. 9.
Staurastrum hexagonum Racib. Nonn. Desm. Polon. 1885, p. So, t. 12, f. 3.
Dysphinctium Ralfsii (Kiitz.) Hansg. var. hexagonum Schmidle, Alg.
Bern. Alp. 1894, p. 92.
Cosmarium pseudoralfsii Migula in Flora von Deutschland, Osterreich
und der Schweiz. Bd. 5 (Desmidiacea? in parts 29-36), 1906, p. 423.
Staurastrumi Meriani forma constricta Teodoresco, Mater, flor. alg.
Roinnan. 1907, p. 185.
Cells rather small, about twice as long as broad,
slightly constricted, sinus a small indentation ; semi-
cells trapeziform-rectaiigular or trapeziform-quadrate,
STATJEASTEUM. 123
wider at the apex than at the base, basal angles
slightly rounded, sides faintly retuse, apical angles a
little dilated and rounded, apex strongly convex and
often flattened in the middle. Vertical view 3-
6-gonal (commonly tetragonal or pentagonal), angles
rounded, sides almost straight. Cell-wall evenly
granulate all over ; granules for the most part without
any definite arrangement, but with distinct indications
of ring-like series around the angles.
Zygospore unknown.
Length 36-40 fx ; breadth of base of semicells
17-20 fx, of apex 20-20 /x ; breadth of isthmus
13-18 p.
England. — Buttermere, and Blea Tarn in Borrow-
dale, Cumberland ! Ambleside and Blea Tarn
(Bissett), and Helvellyn !, Westmoreland. Xear
Cockley Beck, Lancashire! Blubberhouses {Turner),
Baildon !, Ingleton !, Penyghent !, and Cowgiil "Wold
Moss on Widdale Fell !, W. Yorks. Mickle Fell,
N. Yorks ! Hartlebury Common, Worcestershire !
Tintagel, Cornwall !
Wales. — Grlyder Fawr, Snowdon, and near Llyn
Padarn, Carnarvonshire !
Scotland.- — General, but scarce ! (Boy Sf Bissett).
Skye ! Lewis, Outer Hebrides ! Orkneys ! Shet-
lands !
Ieeland. — Near Glenties and near Lough Magrath,
Donegal ! Lough Derryclare, Galway ! Carrantuo-
hill, and 8 miles S. of Kenmare, Kerry! Dublin and
Wicklow (Archer). Westmeath (Archer). Slieve
Donard, Down (at 2000 feet) !
Geogr. Distribution. — France. Germany. Switzer-
land. Austria and Galicia. Roumania. Italy.
Norway. Faeroes. Greenland. United States.
St. Meriani is a very distinctive upland species. It occurs
in alpine and subalpine lakes, tarns, and boggy rills; and
is also not uncommonly found amongst mosses and hepatics
on the dripping rocks of subalpine ghylls and glens. The
form of its semicells, combined with its uniform granulation,
] 24 BRITISH DESMIDIACE.E.
at once distinguishes it from all other species of the genus.
The commonest forms are pentagonal in vertical view,
although tetragonal forms are by no means infrequent.
A form in which the apex of the semicells is more elevated
has been described by Borge from Norway (Finmark) as
"forma rotundata" (Borge, ' Chlorophy. Norska Finmark/
1892, p. 7, t. 1, f. 4).
2. Staurastrum Capitulum Breb.
(PL CXVIII, figs. 7 and 10.)
Staurastrum Capitulum Breb. in Ralis' Brit. Desm. 1848, p. 21-4, t. 35,
f. 25 [figure inaccurate] ; Arch, in Pritch. Infus. 1861, p. 740; Rabenh.
Flor. Europ. Alg. Ill, 1868, p. 209 ; Kirchn. Alg. Schles. 1878, p. 165 -r
De Toni, Syll. Alg. 1889, p. 1191 ; West, Alg. N. Wales, 1890, p. 294 ;
Borge, Siissw. Chlor. Archang. 1894, p. 37 ; Nordst. Index Desm. 1896,
p. 72.
St. amcenum Hilse in Ber. d. Schles. Gesellsch. 1865 [1866], p. 123 ;
Kirchn. Alg. Schles. 1878, p. 165; Wille Ferskvandsalg, Nov. Semlj.
1879, p. 54; De Toni, Syll. Alg. 1889, p. 1191; Heimerl, Desm. alp.
1891, p. 606 ; West, Alg. W. Ireland, 1892, p. 179 ; Alg. Engl. Lake
Distr. 1892, p. 732.
St. Capitulum b. amoenum Rabenh. Flor. Europ. Alg. Ill, 1868, p. 209;
Cooke, Brit. Desm. 1887, p. 161 ; W. & G. S. West, Alga-fl. Yorks. 1901,
p. 107.
Cells rather small, about lj-lf times as long as
broad, slightly constricted, sinus a small acute-angled
notch; semicells campanulate from a broad base,
which is slightly tumid on each side and 2-4-denticu-
late (this marginal appearance being caused by a ring
of denticulate verrucas completely encircling the base
of the semicell), sides slightly retuse above the base
and then upwardly divergent, apex broad and faintly
retuse, apical angles generally denticulate with sharp
granules arranged in concentric rings ; granules
diminishing in size and sharpness as they extend
towards the basal ring of verrucas. Vertical view of
basal part of semicell circular with a crenate margin ;
crenae 10-12, denticulate or emarginate; vertical
view of apical part triangular with subacute angles
and almost straight sides.
Zygospore unknown.
Length 37-40 ^ ; breadth of base of semicell 21-
22 n, of apex 26-28 /x ; breadth of isthmus 13-14-5 fx.
STAURASTRUM. 125
England.— Scawfell, Cumberland ! Easdale and
Stickle Tarns, Westmoreland ! Old Cote Moor and
Cam Fell, W. Yorks ! Bog near Widdale Beck, N.
Yorks! Dartmoor, Devonshire (Joshua).
Wales. — Moel Siabod and Llyn Bochlwyd, Carnar-
vonshire ! Dolgelly, Merioneth !
Irkland. — Kylemore, Gal way ! Carrantuohill and
Lower Lake of Killarney, Kerry !
Geof/r. Distribution. — France. Germany. Austria
and Galicia. Servia. Italy. Norway. Poland.
Greenland. Azores.
With regard to the Desmids described under the names of
St. Capitulnm, St. amoenum, and St. 'pileolatum, a few plain
statements are necessary. The original descriptions of St.
Capitulnm and St. pileolatum are very brief and imperfect, but
the outlines of the figures are moderately good. St. amoenum
appears to have been founded upon a misconception of the
true nature of St. Capitulum — a misconception which we
venture to think was due entirely to the failure of the
author to realise that the figm-e given by Ralfs was inaccurate
in its detail. This figure was only a copy of one of
Brebisson's drawings, and nearly all that author's figures
are very inaccurate, the detail being invariably wrong-.
We have a wide acquaintance with these forms of
Staurastrum in the British Islands and in western Europe
generally, and have come to the conclusion that it is only
possible to recognize two species. These must of necessity be
referred to St. Capitulum and St. pileolatum, the two
originally described and so poorly figured by Brebisson in
the Appendix to Halts' ' British Desmids.' A comparison of
a large series of specimens with all the published information
on these Desmids convinces us that no other interpretation
would be consistent with the known facts.
These two species are distinct only by reason of the
direction of the apical angles of the semicell, which in St.
Capitulum are horizontally spreading whereas in St. pileolatum
they are upwardly directed.
In addition to what we regard as the type form the
following varieties of this species can be distinguished, of
which only the first is at present known to occur in the
British Islands : —
Var. spetsbergense (Nordst.) Cooke, Brit. Desm. 1887,
p. 161, t. 55, f. 3. For description see below.
126 BRITISH DESMIDIACEjE.
Var. italicum (Nordst.) — St. amoenum var. italicum Nordst.
Desm. Ital. 1876, p. 43, t. 13, f. 18. Seraicells with a convex
apex, granules of upper part of semicell all arranged on small
flattened warts which are well seen in the vertical view ;
basal part of semicell triangular, angles granulate and with
a small granulate tumour in the middle of each side. Length
31 ju; breadth of base of semicell 20//, of apex 28-30 /u;
breadth of isthmus 18 fx. Italy.
Var. ACANTHOPHORUM (Nordst.) — St. amoenum subsp. acan-
thophorum Nordst. 1. c. t. 13, f. 19. Each basal verruca
furnished with a pair of sharp spines ; granules of upper part
of semicells very acute and with a tendency to be arranged
on flattened warts. Length 38 fx ; breadth of base of semi-
cell 19 fi, of apex 24; breadth of isthmus 14 ft. Italy.
Austria (Tyrol and Bohemia) .
Var. tumimT'SCULUM (Nordst.) — St. amoenum var. tumidius-
culum Nordst. in Bot. Notiser, 1887, p. 158 ; Freshw. Alg. of
N. Zeal. 1888, p. 38, t. 4, f. 13. Apical angles inclined to be
verruculose rather than granulate or denticulate ; vertical
view quadrangular with straight sides and slightly dilated
angles. Length 45 u; breadth of apex (max.) 40 /x; breadth
of isthmus 24//. New Zealand. We have given a figure of
this variety for comparison with var. spetsbergense (PL CXVIII,
%. 9).
Var. spetsbergense (Nordst.) Cooke. (PL CXVIII,
fig. 8.)
St. Capitulum var. amoenum forma spetsbergensis Nordst. Desm. Spetsb.
1872, p. 39, t. 7, f . 25 [figures not quite correct according to Nordstedt] ;
Larsen, Ferskvandsalg. Vest-Gronl. 1907, p. 348.
St. amoenum forma spetsbergensis Nordst. Desm. arct. 1875, p. 36 ; Boldt.
Desm. Gronl. 1888, p. 39 ; Roy & Biss. Scott. Desm. 1893, p. 178 ; Borge,
Siissw. Chlor. Archang. 1894, p. 37.
St. Capitulum var. spetsbergense (Nordst.) Cooke, Brit. Desm. 1887, p. 161,
t. 55, f. 3.
With the sharp granules (or denticulations) of the
upper angles fewer in number and more irregularly
disposed.
Length 34-45 /x ; breadth of base of semicell
26-28 /x, of apex 31-33 /x; breadth of isthmus
12-20 ft,
England. — Blea Tarn, Westmoreland {Bissett).
Wales. — Capel Curig and Pen-y-gwryd, Carnarvon-
shire (Boy).
STAURA STRUM. 127
Scotland. — Sutherland, Ross, Inverness, Aberdeen,
Kincardine, Forfar, Perth, Dumbarton, and Bute (Rot/
fy Bissett).
Geogr. Distribution. — Spitzbergen. Xova Zembla.
N. Russia. Brazil.
We have not seen this variety, and we are inclined to think
that Messrs. Roy & Bissett have referred to it all the forms of
St. Gapitulum which came under their notice. It differs so
little from typical St. Capitulum that it is hardly worth the
separation.
3. Staurastrum pileolatum Breb.
(PI. CXVIII, figs. 11-13.)
Staurastrum pileolatum Breb. in Ralfs' Brit. Desm. 1848, p. 215, t. 35,
f. 2:3 [figure inaccurate] ; Arch, in Pritch. Infus. 1861, p. 740 ; Rabenh.
Flor. Europ. Alg. Ill, 1868, p. 220 ; Cooke, Brit. Desm. 1887, p. 160,
t. 55, f. 1 ; Hansg. Prodr. Algenfl. Bohm. 1888, p. 216 ; De Toni, Syll.
Alg. 1889, p. 1191 ; West, Alg. N. Wales, 1890, p. 294 ; Roy & Biss.
Scott. Desm. 1893, p. 241 ; Nordst. Index Desm. 1896, p. 200. *
St. amcenum Hilse var. brasiliense Borg. as recorded by West, Alg. W.
Ireland, 1892, p. 179, t. 23, f. 9.
St. pileolatum Breb. var. brasiliense (Borg.) Liitkem. as recorded by W.
& G. S. West, Alga-fl. Yorks. 1901, p. 107 ; Notes Alg. Ill, 1903, p. 11
(sep.) ; Freshw. Alg. Orkneys and Shetlands, 1905, p. 28.
Cells rather small, about twice as long as broad,
slightly constricted, sinus a small acute-angled notch ;
semicells rectangular-subcampanulate, base broad and
very slightly tumid-emarginate just above the sinus
(caused by a ring of emarginate verrucas or short
ridges which completely encircle the base of the semi-
cell), sides slightly retuse near the base, after which
they diverge very slightly upwards, apex concave,
apical angles rounded-conical and minutely granulate,
each with about 5 concentric rings of small granules,
those near the basal verrucas becoming very minute.
Vertical view of basal part of semicell circular with a
Crenate margin ; crense 18-21, bluntly rounded; vertical
view of apical part of semicell triangular (rarely quad-
rangular) with acutely-rounded angles and very slightly
concave sides.
Zygospore globose, furnished with a few short, stout
spines, 2-3-fid at the apex.
128 BRITISH DESMIDIACEJL
Length 40-44 jx ; breadth of base of semicells 18-5-
22 /a, of apex 20-25 /a; breadth of isthmus 14-16*5 /t.
England. — Bog near Widdale Beck, N. Yorks ! Scaw-
fell, Cumberland ! Bovey Tracey, Devonshire {Joshua).
Wales. — Capel Curig, and at 2200 feet on Glyder
Fach, Carnarvonshire ! Dolgelly, Merioneth !
Scotland. — Ross, Aberdeen, Kincardine, Perth,
Argyll; zygospores from Den of Garrol, Kincardine
{Boy Sf Bissett). Glen Nevis and Invermoidart, Inver-
ness ! Near Lerwick, Shetlands !
Ireland. — Dublin and Wicklow {Archer). Bally -
nahinch !, and Leenane {Archer), Galway.
Geogr. Distribution. — France. Germany. Austria
(Bohemia). Bulgaria. Brazil.
St. pileolatum is distinguished from St. Capitulum by two
main features ; first, the upwardly drrected apical angles of
the semicells, resulting in a markedly concave apex, and
secondly, the greater number of verrucas encircling the base
of the semicells. The granulation is also a little different, as
the granules are never sharp and spine-like in St. pileolatum.
The verrucas at the base of the semicell are variable
in character, but the most frequent form possesses longi-
tudinally compressed and slightly emarginate verrucas, which
might almost be described as short emarginate ridges
(consult PI. CXVIII, figs. 11 and 12). Sometimes the verrucas
are not so compressed and are furnished with blunt teeth at
their angles, in which case they much resemble those of
St. Capitulum (consult fig. 13).
Brebisson's figure of this species (in Ralfs' ' Brit. Desm.'
1848, t. 35, f. 22) is very inaccurate as to detail, but the out-
line and general proportions are not bad. The granulation
as depicted at the base of the semicell is an obvious error.
In addition to the type form of St. pileolatum there are
two others which are sufficiently distinct to merit definite
varietal names. These are : —
Var. cristatum LiAtkem. For description see below.
Var. bbasiliense (Borg.) Liitkem. Desm. Attersees, 1893,
p. 567. St. amoenum Hilse var. brasiliense Borg. Desm.
Brasil. 1890, p. 45, t. 4. f. 44. Basal verrucas of semicells
larger and fewer in number (about 13), each surmounted by
5 or 6 minute, irregularly disposed denticulations. Long.
15 fx-} lat. 19 /u; lat, isthm. 12 /i. Hab. Brazil. We had
STATJRASTRUM. 129
recorded this variety from Yorkshire, X. Wales, the Shet-
lands, and from the west of Ireland, but we have since found
that the specimens in all instances were of the typical
form .
Var. cristatum Liitkem. (PL CXVIII, fig-. 14.)
St. pileolatum Breb. var. cristatum Liitkem. Desm. Attersees, 1893, p. 566,
t. 9, f. 16 ; G-utw. Plor. Alg. Mont. Tatr. 1909, p. 474.
St. Lewisianum Turn. Desm. Notes, Nov. 1893, p. 345, fig. 8 on p. 344
[figure incorrect].
With the basal arc of granules on the underside of
each apical angle transformed into small, longitudinally
compressed, emarginate verruca?.
Length 35'5-41/a; breadth of base of semicell
20-22 fx, of apex 20-23 [x; breadth of isthmus 15-1 G jx.
Wales. — On the Llanberis slopes of Snowdon,
Carnarvonshire ! (J. H. Lewis).
Geogr. Distribution. — Austria and Galicia.
The only important distinction between this variety and
the type is the duplication of the granules forming the lower-
most series on the underside of the apical angles. These
binate granules are situated on very small compressed warts,
which form ai'cs round the bases of the apical angles.
Lutkemuller found in his Austrian specimens a large granule
immediately under the point of junction of two adjacent arcs,
but we have not observed these granules in the Welsh speci-
mens.
We have examined a number of the specimens collected by
Mr. J. H. Lewis on the slopes of Snowdon towards Llanberis
and have given an illustration of one of them (PL CXVIII,
fig. 14). These specimens were made the foundation of a
distinct species by Turner, under the name of St. Lewisianum,
but Turner's description and figure are both veiw inaccurate.
4. Staurastrum rhabdophorum Norclst.
(PI. CXVIII, fig. 15.)
Staurastrum rhabdophorum Nordst. Desm. Arctoae, 1875, p. 36, t. 8, f. 40;
Wille, Ferskv. Alg. Nov. Semlj. 1879, p. 54 ; De Toni, Syll. Alg. 1889,
p. 1179 ; Eoy & Biss. Scott. Desm. 1893, p. 242 (sep. p. 24).
Cells rather under medium size, cylindrical, H-
times as long as broad, very slightly constricted, sinus
a small notch, dilated inwardly ; semicells subquadrate,
vol. iv. 9
130 BRITISH DESMIDIACE-F.
basal angles rectangular, margin at the base crenate-
clenticulate (which appearance is due to a basal ring
of longitudinally compressed denticulate verrucas),
apex truncate-convex, furnished with about 7 emargi-
nate verrucas at the margin and about 6 denticulate
verrucas within the dorsal margin. Vertical view
triangular- subcircular or quadrangular-subcircular,
entire margin furnished with emarginate verrucas,
and with a series of verrucas within the margin.
Zygospore unknown.
Length 47*5 /a; breadth of base of semicells 31*5 ft,
of apex 31 '5-3 3*3 /a ; breadth of isthmus 25 jx.
Nordstedt mentions the two following forms :
Forma trigona. — Vertical view triangular-circular,
with 15 (= 3 x 5) marginal verrucas, with (.»
(= 3 X 3) within the margin, and usually with 18
(= 3 x 6), more rarely with 16 or 17, basal verrucas.
Formo, tetragona.- — Vertical view quadrangular-cir-
cular, with 20 (= 4 X 5) marginal verrucas, with 12
(=4 x 3) within the margin, and usually with 20
(=4 x 5), more rarely with 19, basal verrucas.
Scotland. — On the table-land north-west of Can-
lochan, Aberdeen (or Forfar ?) (Boy Sf Bissett).
Geogr. Distribution. — Spitzbergen. Nova Zembla.
We have not yet seen this characteristic arctic Desmid. It
is so distinctive that it scarcely needs comparison with any
other species of the genus.
Section B.
Cells subcylindrical, smooth.
5. Staurastrum minutissirnum Reinsch.
(PL CXIX, fig. 2.)
Staurastrum minutissirnum Reinsch, Spec. Gen. Alg. 1867, p. 140, t. 23
A II, f. 3-8 ; ? Rabenh. Flor. Europ. Alg\ III, 1868, p. 201 ; Reinsch,
Contrib. Alg. et Fungi, 1875, p. 91, t. 16, f. 3 [forma] ; De Toni, Syll.
Alg. 1889, p. 1184; Borge, Susswasseralgen Franz Josefs-Land, 1899,
p. 763.
Didymidium (Staurastrum) minutissirnum Reinsch, Algenfl. Frank. 1867,
p. 153, t. 13, f. 1.
STAUEASTEUM. 131
Cells minute, a little longer than broad, very slightly
constricted, sinus very obtuse-angled (about 140°) ;
semicells quadrate-cuneiform, sides almost straight,
apex concave, apical angles a little produced and
rounded. Vertical view tetragonal or pentagonal
(more rarely trigonal), with concave sides and rounded
angles. Cell-wall smooth.
Zygospore unknown.
Length 8-12 /x; breadth 7-9 [x; breadth of isthmus
6-7-5 fi.
Geogr. Distribution. — Germany.
The above description and the measurements refer to
St. minutissimum as described by Reinsch, and fig. 2 on
PI. CXIX is a copy of one of Reinsch's original figures.
So many different forms have been referred to " Staurastrum
minutissimum Auersw." that it wasfelt to be an absolute neces-
sity to carefully examine Auerswald's original specimens.
Fortunately, these were issued in Rabenh. Alg. Europ. 1863, no.
1428 (c. fig.). All the specimens thus distributed consist of a
stout form of St. inconspicuum Nordst., and both the descrip-
tion and figure given by Auerswald are erroneous. Therefore,
the only ' St. minutissimum '. which can be regarded as a
valid species is that described and figured by Reinsch in
1867, and hence Reinsch must remain the authority for this
species. Even then the species remains doubtful, as nearly
all the published figures since 1867 differ widely from those
of Reinsch.
Most of Reiusch's figures represent a minute Staurastrum
with concave apices, and this we have regarded as the type-
form. We suggest the following arrangement of the other
known forms of St. minutissimum : —
Var. coxvexcm nob. [= St. minutissimum Reinsch, Spec.
Gen. Alg. 1867, t. 23 A II, f. 1, 2.] Constriction of cells
somewhat deeper ; apex of semicells convex. (PI. CXIX,
fig. 3.)
Forma trigona. St. minutissimum forma tngona major
et minor Wille, Ferskv. Alg. Nov. Semlj. 1879, p. 52,
t. 13, f. 59, 60 ; Larsen, Freshw. Alg. E. Greenland, 1904,
p. 98. Vertical view triangular, with very slightly con-
cave sides. Length 18-29,u; breadth 17-29/z; breadth
of isthmus 9-11 fi. (PI. CXIX, fig. 5.) Hab. Green-
land. Nova Zembla.
Forma tetragona. St. minutissimum forma tetragona
132 BRITISH DESMIDIACE/E.
Nordst. Desm. Arctoaj, 1875, p. 33, t. 8, f. 36. Cells
proportionately wider; vertical view tetragonal with
slightly concave sides. Length 15 /u ; breadth 15-17 ju ;
breadth of isthmus 13 fx. (PI. CXIX, fig. 4.) Hab.
Spitzbergen.
Var. constrictum West. Constriction deeper, sinus form-
ing a right angle ; apex of semicells straight or slightly
concave. See below.
Messrs. Roy and Bissett have recorded " St. minutissimum
Auersw." from Cairngorm, Inverness; Milton Moor, and
Tomachar in Cromar, Aberdeen; and Kerloch, Kincardine.
We do not know, however, to which form these records
refer.
The only form we have personally observed in the British
Islands is the following : —
Var. constrictum West. (PL CXIX, fig. 6.)
St. minutissvm/wm var. constrictum West, Alg. W. Ireland, 1892, p. 172,
t. 24, f. 14 ; Cushman in Khodora, 1905, x>. 263.
Rather larger than the type and more deeply con-
stricted, apex of semicells straight or slightly concave ;
vertical view triangular, with subconcave sides.
Length 16-24/x; breadth 17"5-24/m; breadth of
isthmus 9 ft.
Ireland. — :Near Clifden, Grahvay !
Geogr. Distribution. — United States.
Section C.
Cells smooth or punctate, without spines, verruca?,
or granules.
* Angles more or less rounded or furnished with a small solid
mucro or mam ilia.
t Sinus open and acute-angled (or more rarely obtuse-
angled) .
+ Semicells more or less elliptic, angles rounded or
acutely rounded.
§ Angles not thickened and without a mucro.
6. St. m a tie inn.
7. St. Bieneanum .
8. St. ellipticum.
9. St. coarctatinn.
10. St. grande.
STAUEASTEUM. ]33
§§ Angles with a small mucro or a mamilla.
11. St. tumidum.
§§§ Angles thickened.
12. St. conspicuunt.
13. St. aver sum.
14. St. brevispinum.
15. St. Janceolatu in.
*
16. St. pa eh y rh y n ch urn.
XX Semicells obversely triangular.
17. /S7. Clepsydra.
XXX Semicells rhomboidal.
18. St. inelegans.
19. St. angulatum.
ft Sinus closed and linear.
X Semicells widely subpyramidate-trapeziform or sub-
semi-circular.
20. St. orbiculare.
21. St. suborbiculare.
22. St. retusum.
XX Semicells elongately subpyramidate-inflated.
23. St. Cosmarioides.
f Angles distinctly produced into a hollow mamillate lobe.
24. St. tortum.
25. St. subpygmseum.
26. St. cornlculatii hi .
6. Staurastrum muticum Breb.
(PL CXVIII, figs. 16-20.)
Binatella mutica Breb. Alg Falaise, 1835, p. 57, t. 8.
? Staurastrum trilobum Menegh. Conspect. Alg. Eugan. 1837, p. 18 (sep.).
St. muticum Breb. in Menegh. Synops. Desm. 1840, p. 228; Kalfs, Brit.
Desm. 1848, p. 125, t. 21, f. 4. t. 34, f. 13 ; Arch, in Priteh. Infus. 1861,
p. 740; Eabenh. Flor. Europ. Alg. Ill, 1868, p. 200; Kirchn. Alg. Schles.
p. 163 ; Gay, Monogr. loc. Conj. MontpeUier, 1884, p. 64 ; Wolle, Desm.
U. S. 1884, p. 119, t. 39, f. 11, 12 [figures poor] ; Cooke, Brit. Desm. 1887,
p. 156, t. 51, f. 6 ; Hansg. Prodr. Algenfl. Bohm. 1888, p. 210 ; De Toni,
Syll. Alg. 1889, p. 1177 ; West, Alg. N. Wales, 1890, p. 293 ; Heimerl,
Desm. alp. 1891, p. 605; West, Alg. W. Ireland, 1892, p. 176; Alg.
Engl. Lake Distr. 1892, p. 731 ; Liitkem. Desm. Attersees, 1893, p. 563 ;
Eoy & Biss. Scott. Desm. 1893, p. 241 (p. 23 sep.) ; Nordst. Index
Desm. 1896, p. 179; W. & G. S. West, Alg. S. England, 1897, p. 494 :
G. S. West, Variation Desm. 1899, p. 391 ; W. & G. S. West, Alga-fl.
Yorks. 1900, p. 100; Alg. N. Ireland, 1902, p. 49; Freshw. Alg. Ceylon,
1902, p. 178 ; Borge, Alg. erst Eegnell. Exped., II. Desmid. 1903, p. 106 ;
Larsen, Freshw. Alg. E. Greenland, 1904, p. 98 ; W. & G. S. West,
Freshw. Alg. Orkneys and Shetlands, 1905, p. 25 ; Comp. Study Plank-
ton Irish Lakes, 1906, p. 86 ; Borge, Beitriige Alg. Schweden, 1906,
p. 43 ; Larsen, Ferskvandsalg. Vest-Gronl. 1907, p. 351 ; G. S. West,
Alg. Yan Yean, 1909, pp. 15, 28; W. & G. S. West, Brit. Freshw.
134 BRITISH DESMIDIACE.E.
Phytoplankton, etc., 1909, p. 182 ; Hustedt, Desm. et Bacill. aus Tirol,
1911, p. 337.
St. muticum var. ellipticum Wolle, Desm. U. S. 1884, t. 39, f. 13.
St. muticum a. typicum Riabin. in Bull. Soe. Imp. Natur. Moscou, 1888,
no. 2, p. 329.
St. depressum (Nag.) Turn, forma aperta Turn. Freshw. Alg. E. India,
1893, p. 104, t. 13, f . 19.
Cells small, as long as broad or a little longer, deeply
constricted, sinus open and acute - angled ; semicells
usually elliptic, but often elliptic-semicircular or even
subrenif orm. Vertical view triangular or quadrangular,
with broadly rounded angles and concave sides. Cell-
wall smooth.
Zygospore globose, furnished with stout spines which
are bifurcate at the apex \_Ralfs\.
Length 22-43-5^; breadth 21-37-5/*; breadth of
isthmus I'b-VZfx; diam. zygosp. without spines 38 fi;
length of spines 9*5—12 fx.
England. — Westmoreland! (Halfs). W., N., and
E. Yorks! Essex! Warwick (Wills). Surrey!
Hants! Devon ! (Bennett). Cornwall!
Wales. — Bethesda !, Snowdon !, and Capel Curig !
(Cooke Sf Wills), Carnarvonshire. Dolgelly, Merioneth
(Ralfs). Plankton of various Welsh lakes!
Scotland. — Sutherland !, Inverness, Aberdeen, Kin-
cardine, Perth, Stirling, Argyll (Boy tif Bissett).
Orkneys ! Shetlands !
Ireland. — Castlebar and Achill Island, Mayo !
Lough Guitane, Kerry ! Adrigole, Cork ! Dublin
and Wicklow (Archer). Plankton of Lough Xeagh !
Geogr. Distribution. — France. Germany. Austria
and Galicia. Hungary. Italy. Norway (and Fin-
mark). Sweden. Denmark. Bornholm. Finland.
N. and S. Russia. Faeroes. Spitzbergen. Green-
land (var.). Siberia. Mongolia. Java. Australia.
Central Africa. Azores (var.). Sandwich Islands.
United States. Brazil.
St. muticum is a widely distributed species which sometimes
occurs in more or less abundance at the margins of pools and
lakes. The outward form of the semicells is somewhat vari-
able, and both triangular and quadrangular vertical views are
common.
STAURASTRUM. 1 3 5
The range of size in this species is considerable, and although
it has been customary to specially mention the smaller forms,
any line of demarcation is purely arbitrary. The following
small form is recorded by many authors, but in some cases it
is questionable whether the author who recorded it was aware
of the fact that the only basis of separation was " size."
Forma minor Rabenh. Flor. Europ. Algar. Til, 1868, p. 200;
Lund. Desm. Suec. 1871, p. 56 ; Boldt, Siber. Chlorophy.
1885, p. 110. Phycastrum depressum Nag. Gatt. einzell. Alg.
1849, p. 126, t. 8, f. A 1. St. muticum var. minor Wolle,
Desm. U. S. 1884, p. 119, t. 39, f. 14, 15; Hansg. Prodr.
Algenfl. Bohm. 1888, p. 255 ["var. minus"]; W. & G. S.
West, Alg. S. England, 1897, p. 494; Alg. N. Ireland, 1902,
p. 49 ; ? Cushman in Rhodora, v, 1903, p. 224. St. muticum
var. depressum (Nag.) Nordst. in Pointsf. Skandin. Vaxt. iv,
1880, p. 27 ; Schmidle, Beitr. Algenfl. Schwarzwald. u.
Rheineb. 1893, p. 109. St. depressum (Nag.) Turn. Freshw.
Alg. E. India, 1893, p. 104.
Cells smaller ; length 16-21 /x ; breadth 15*5-17 \x ; breadth
of isthmus 4"5-5 ft.
England. — New Forest, Hants !
Scotland. — Hoy, Orkneys !
Ireland. — Near Glenties, Loughs Machugh and Magrath,
Donegal !
Geogr. Distribution. — Germany. Austria. Sweden. Siberia-
India. United States.
Cushman records " St. muticum var. minor Wolle" from
New England with zygospores. He describes these spores as
clothed with numerous acute spines, which is a striking con-
trast to the zygospore of St. muticum desci'ibed and figured by
Ralfs (consult PI. CXVIII, fig. 20). It leads one to suspect
that the zygospores observed by Cushman did not belong to
the same species as that described by Ralfs.
7. Staurastrum Bieneanum Rabenh.
(PL CXX, figs. 4-6.)
Staurastrum Bieneanum, Rabenh. Alg;. Eur. 1862, no. 1410; Wittr. &
Nordst. Alg. Exsic. 1877, no. 73 ; De Toni, Syll. Alg. 1889, p. 1197 ;
West, Alg. W. Ireland, 1892, p. 177; Alg. Engl. Lake Distr. 1892,
p. 731 ; Roy & Biss. Scott. Desm. 1893, p. 178 (sep. p. 17) ; W. & Gt. S.
West, Alg. Madag. 1895, p. 74 ; New and Int. Freshw. Alg. 1896, p. 158,
t. 3, f. 27 ; Nordst. Index Desm. 1896, p. 58 ; W. & G. S. West, Alg. S.
England 1897, p. 494; Alga-fl. Yorks, 1901, p. 101 ; Alg. N. Ireland, 1902,
p. 49 ; Freshw. Alg. Orkneys and Shetlands, 1905, p. 25 ; Further
Contrib. Freshw. Plankton Scott. Lochs, 1905, p. 486; Comp. Study
186 BRITISH DESMIDIACE^.
Plankton Irish Lakes, 1906, p. 86 ; G-. S. West, Alg. Yan Yean, 1909,
p. 28; W. & G. S. West, Brit. Freshw. Phytoplankton, etc., 1909, p. 181.
Didymidium (Staurastrum) muticum c. Bieneanum Reinseh, Algenfl.
Frank. 1867, p. 151.
Staurastrum orbiculare (Ehrenb.) Menegh. var. Bieneanum Rabenh. Flor.
Europ. Alg. Ill, 1868, p. 200.
St. muticum c. Bieneanum Riabin. in Bull. Soc. Imp. Natur. Moscou, 1888,
no. 2, p. 329.
Cells small, generally a little broader than long, very
deeply constricted, sinus widely open with an acuminate
apex ; semicells subelliptic, dorsal margin less convex
than the ventral margin and slightly flattened in the
middle, lateral angles subacute. Vertical view tri-
angular, angles subacute (or acutely rounded), sides
retuse in the median part. Cell-wall densely and finely
punctate.
Zygospore globose, clothed with numerous, simple,
stout, slightly curved spines, which are a little dilated
at the base and sharp at the apex.
Length 26-37'5/x; breadth 29-42 /x ; breadth of
isthmus 7-9 /x ; diam. zygosp. without spines 33-35 /x,
with spines 50-52 /x; length of spines 8-10 fx.
England. — Borrowdale, Cumberland ! Brothers'
Water, \Yestmorelancl ! Pilmoor, X. Yorks ! Epping
Forest, Essex ! Goring, Oxfordshire (with zygospores) !
New Forest, Hants !
Scotland. — Loch Hempriggs and St. John's Loch,
Caithness ! Kerloch and Blackball, Kincardine ; Bal-
quhadly in Fern, Forfar (Roy fy Bissett). Benbecula,
Outer Hebrides ! Orkneys ! Plankton of Loch Bair-
ness, Inverness ! Plankton of Lochs Cuthaig, Fada-
ghoda, Jtoinebhal, and an Tomain, Lewis, Outer
Hebrides !
Ireland. — Lough Cloncarney and Sproule's Lough,
Donegal ! Creggan Lough, Galway ! Upper Lake of
Killarney, Kerry ! Adrigole, Cork ! Plankton of
Loughs Caragh and Currane, Kerry !
Geogr. Distribution. — Germany. Austria. Norway.
Sweden. Bornholm. Faeroes. Nova Zembla. Russia.
Siberia. Japan. Siam (var.) New Zealand. Mada-
gascar. E. Africa (var.). United States.
STAUEASTK UM . 137
St. Bieneanum, originally described by Rabenhorst as a
distinct species, was subsequently placed by that author as
a variety of St. orbiculare (Ehrenb.) Ralfs. It cannot be
considered as a near relative of the latter species, however,
and throughout the British Islands it maintains its characters
very constantly. The lower margins of the semicells are
always more convex than the upper ones, an inequality of
curvature which causes a slight outward divergence of the
semicells. The dorsal margin is always truncate or faintly
retuse in the middle, the angles of both front and vertical
views are subacute, and the cell-wall is delicately but dis-
tinctly punctate. The zygospores possess fewer, shorter, and
stouter spines than those of St. orbiculare var. Balfsii.
Forma spetsbergensis Xordst. (PI. CXX, fig. 7.)
St. Bieneanum forma spetsbergensis Nordst. Desm. Arctoffi, 1875, p. 32,
t. 8, f. 35 ; Bolclt, Siber. Chlorophy. 1885, p. 110 ; Boy & Biss. Scott.
Desm. 1893, p. 178 (sep. p. 17) ; Borg. Perskv. alg. Ostgronl. 1894,
p. 25 ; Freshw. Alg. Faeroes, 1901, p. 232 ; Larsen, FresW. Alg. E.
Greenland, 1904, p. 96 ; Ferskvandsalg. Yest-Gronl. 1907, p. 348.
Cells proportionately a little longer, not quite so
deeply constricted ; vertical view of triangular form
with straight or sometimes slightly convex sides, or of
tetragonal form with slightlv concave sides. Cell-wall
punctate as in the typical form.
Length 35-42 fx ; breadth 24-38 /x ; breadth of
isthmus 10-14 /x.
Scotland. — Xear the summit of Lochnagar, Aber-
deen (Boi/ Sf Bisxett).
Geogr. List filiation. — Faeroes. Spitsbergen. Green-
land. Siberia.
Var. ellipticum Wille. (PI. CXX, fig. 8.)
St. Bieneanum var. ellipticum Wille, Ferskv. Alg. Nov. Semlj. 1879, p. 50,
t. 13, f. 49; Boldt, Siber. Chlorophy. 1885, p. Ill; West, Alg. W.
Ireland, 1892, p. 177 ; Schmidle, Beitr. Algenfl. Schwarzwald. u.
Eheineb. 1893, p. 10.), t. 5, f. 29 ; W. & G. S. West, Alg. S. England,
1897, p. 494 ; Schmidle, Lappmark Siisswasseralgen, 1898, p. 58 ;
Lutkem. Desm. Millstattersees, 1900, p. 19; Larsen, Ferskvandsalg.
Vest-Gronl. 1907, p. 348.
Semicells rather narrowly elliptic, angles rounded ;
cell-wall punctate, with the punctulations arranged in
concentric series around the angles.
loH BRITISH DESMIDIACE^E.
Length. 38-45 fi ; breadth. 38-45 /x ; breadth of
isthmus 11-12 /x.
Ext; [-and. — Puttenham Common, Surrey! Keston
Common, Kent ! New Forest, Hants !
Ireland. — Near Westport, Mayo ! Ballynahinch,
Loughs Nacoogarrow, Shannacloontippen. and Derry-
clare, Galway ! Lough Guitane, Kerry ! Adrigole and
Glengariff, Cork !
Geogr. Distribution. — Germany. Austria. Norway
(Lappmark). Greenland. Samoa. Australia.
8. Staurastrum ellipticum West.
(PI. CXIX, fig. 7.)
Staurastrum ellipticum West, Alg. Engi. Lake Distr. 1892, p. 731, t. 9,
f. 28; Nordst. Index Desm. 1896, p. 117 Lemm. Beitr. Kenntnis
Planktonalg. XXYI, 1910, p. 295.
St. muticum Breb. var. subsphsericum Borg. Ferskv. alg. Ostgronl. 1S94,
p. 24, t. 2, f. 18.
Cells small, about H times longer than broad, fairly
deeply constricted, sinus open and acute-angled ;
semicells somewhat broadly elliptic. Vertical view
trigonal, with broadly rounded angles and straight or
slightly convex sides, or tetragonal with broadly
rounded angles and slightly concave sides. Cell-wall
smooth.
Zygospore unknown.
Length 42-5-40 /x ; breadth 29-30 fi ; breadth of
isthmus 13-15 /x.
England. — Borrowdale, Cumberland !
( ieogr. Distribution. — Greenland. Paraguay.
This species is nearest to St. vesiculatum Wolle ('Freshw.
Alg-. U.S./ 1887, p. 42, t, 54, f. 6, 7), from which it differs in
its broader sinus and elliptical semicells. It should also be com-
pared with St. muticum Breb. from which it is distinguished
hy the proportionately greater length, the different shape of
the semicells, and the form of the vertical view. The axile
chloroplast in each semicell possesses a particularly large
central pyrenoid.
STAURASTRUJ1. 139
9. Staurastrum coarctatum Breb.
(PI. CXIX, fig. 8.)
Staurastrum coarctatum Breb. Liste Desm. lSo^S, p. 144, t. 1, f. 29 ; Arch.
in Pritch. Infus. 1861, p. 740; Eabenh. Flor. Europ. Alg. Ill, 1S6S,
p. 220; De Toni, Syll. Alg. 1889, p. 1187; Eoy & Biss. Scott. Desm.
1893, p. 179 ; Nordst. Index Desm. 1896, p. 76.
Cells small, a little broader than long, very deeply
constricted, sinus open and acute-angled; semicells
transversely oblong, with the angles very broadly
rounded and slightly divergent, apex faintly retuse.
Vertical view triangular, with broadly rounded angles
and concave sides. Cell- wall smooth.
Zygospore unknown.
Length oo'o/x; breadth 38-40 ju,; breadth of
isthmus 9—5 /x.
Scotland. — ■Cammie in Strachan, Kincardine {Roy
Sf Bissett).
Geocjr. Distribution. — France. Sweden (var.). Brazil
(var.).
The typical form of this species has only once been observed
since its original discovery by Brebisson in 1856. It is
recorded by Messrs. Roy and Bissett as "very rare" in one
locality in Kincardine.
Var. subcurtum Nordst. (PI. CXIX, figs. 9, 10.)
St. coarctatum var. subcurtum Nordst. in Botan. Notiser, 1887, p. 158;
Freshw. Alg. N. Zeal. 1888, p. 41, t. 4, i. 20; Wrest, Alg. N. Wales,
1890, p. 293, t. 5, f. 8 ; Sehmidle, Lappmark Siisswasseralgen, 189S,
p. 57.
Cells with a wider and more obtuse sinus, isthmus
relatively broader and a little elongated ; semicells less
wide than in the type, lateral angles shorter and not
divergent, apex straight or very faintly convex.
Length 20-28 fi ; breadth 16-23 fi; breadth of
isthmus (3-12 /x.
Wales. — Capel Curig, Carnarvonshire !
Geogr. Distribution. — Norway (Lappmark). New
Zealand.
This variety should be compared with St. muticum, from
H-0 BRITISH desmidiacej:.
which it differs in its oblong semicells and in the elongation
of the isthmus.
The Desmid figured by Bohlin from the Azores under the
name of " St. co arc latum var. subcartwrn " (Cf. Bohlin, ' Flor.
Algol, d'eau douce d. Acores/ 1901, t. I, f. 27) is probably a
small form of St. ellipticiun.
10. Staurastrum grande Bulnli.
(PL CXIX, figs. 11-13; PI. CXX, fig. 1.)
Staurastrum grande Bulnli. in Hedwigia, 1861, p. 51, t. 9, f . 14; Lund.
Desm. Suec. p. 72 ; Cooke in Grevillea, ix, 1881, p. 91, t. 139, f. 4 ;
Wolle, Desm. U. S. 1884, p. 120, t. 39, f . 3, 4 ; Cooke, Brit. Desm. 1887,
p. 166, t. 57, f. 2 ; De Toni, Syll. Alg. 1889, p. 1201 ; Borg. Desm.
Brasil. 1890, p. 51 ; West, Alg. Engl. Lake Distr. 1892, p. 732 ; Eoy &
Biss. Scott. Desm. 1893, p. 238; Johnson, Rare Desm. U. S. II, 1895,
p. 294; Nordst. Index Desm. 1896, p. 134; W. & Gh S. West, Scott.
Freshw. Plankton, I. 1903, p. 547 ; Further Contrib. Freshw. Plankton
Scott. Lochs, 1905, p. 486 ; Cushman in Bull. Torr. Bot. Club, xxxii,
1905, p. 227, t. 8, f . 17 ; in Rhodora, vii, 1905, p. 262 ; W. & G. S. West,
Comp. Study Plankton Irish Lakes, 1906, p. 86 ; G. S. West, Alg. Yan
Yean, 1909, pp. 15, 27 ; W. & G. S. West, Brit. Freshw. Phytoplankton,
etc., 1909, p. 182 ; Phytoplankton Engl. Lake Distr. 1909, p. 139.
St. grande forma Lund. Desm. Suec. 1871, p. 72, t. 4, f. 11 ; Liitkem.
Desm. Bohm. 1910, p. 498.
Pleurenterium grande (Bulnh.) Wille in Engler & Prantl, Naturl.
Pflanzenfam. 1890, pp. 11, 12 (f. 7 G).
Cells large, about as long as broad, deeply constricted,
shins acnte-angled ; semicells elliptic or subeliiptic,
sometimes with the ventral margin more convex than
the dorsal margin, lateral angles rather acutely rounded.
Vertical view triangular, or very rarely quadrangular,
sides slightly retuse, angles acutely rounded. Cell-
wall finely punctate. Chloroplasts axile, or sometimes
parietal, 0-6 in each semicell, each with 1-3 pyre-
noicls.
Zygospore angular-globose, furnished with scattered
stout spines, arising from a dilated base and often
curved.
Length 84-100 ^ ; breadth 80-111 /x ; breadth of
isthmus 21—25 /u. ; diam. zygosp. (of rather small form)
without spines 60 p, with spines 100 fx.
England. — Borrowdale, Cumberland ! Loughrigg,
and near Bowness ; also plankton of Brothers' Water,
AVestmoreland !
STAUBASTKUM. 141
Wales. — Capel Curig, Carnarvonshire (Goolce Sr
Wills).
Scotland. — Loch Shin, and plankton of L. nan
Cuinne, Sutherland ! Near Loch Mharc in the forest
of Athole, Perth {Boy Sf Bissett). Plankton of Loch
Doon, Ayr ! ; Lochs Cuthaig and Fadaghoda, Lewis ! ;
Loch nan Eun, N. LTist ! ; and Loch Laxadale,
Harris !
Ireland. — Rare in the plankton of the small lakes
between Clifden and Roundstone, Galwa y !
Geogr. Distribution. — Germany. Austria. Sweden.
United States. Brazil. Australia.
St. grande is a rare Desmid, which we have chiefly met
with in the plankton of the western lake-areas. The form of
the semicells is somewhat variable, some having a much less
convex dorsal margin than others. The relative length and
breadth of the cells is also slightly variable, and some
individuals have more rounded angles than others.
The zygospores have been observed by Cashman from
Reading, Mass., U.S.A. This author also describes a var.
glabrum in which the cell-wall is perfectly smooth. Moreover,
the zygospores of this smooth variety are not so angular as
those of the type, and are " more densely set with shorter and
more slender spines."
The disposition of the chloroplasts in Si. granite is subject
to much variation. Lundell, who was the first to examine
them with care, described and figured them as parietal
masses. Dr. Liitkemuller, who has recently made a careful
study of them in large numbers of individuals, finds all con-
ditions from truly axile to truly parietal chloroplasts, and
states that the former condition is the more prevalent.
Var. parvum West. (PI. CXX, figs. 2, 3.)
St. grande var. parvum West, New Brit. Fresh w. Alg. 1894, p. 11, t. 2,
f. 51 [= St. brevispinmn Breb. var. inerme Wolle, Freshw. Alg. U. S.
1887, t. 62, f. 9, 10 (non Wille, 1879). J
Cells smaller, with a narrower isthmus ; angles of
semicells more rounded. Cell-wall finely punctate.
Length 61-63 [x; breadth 60-61 fx ; breadth of
isthmus 13*5-14 /x.
Scotland. — den Shee, Perthshire !
142 BRITISH DESMIDIACEJ5.
Geogr. Distribution. — Lappmark in Norway (forma).
Schmidle (' Lappmark Suss wasseral gen,' 1898, p. 59, t. 3,
f. 9) has described a "forma lapponica" of this variety in
which the cells are smaller and narrower, with subtruncate
apices and slightly thickened angles; length 52/^, breadth
45 ju.
11. Staurastrum tumidum Breb.
(PI. CXXII, figs. 1-5.)
Binatella tumida Breb. Alg. Falaise, 1835, p. 269.
Staurastrum tumidum Breb. in Ralfs' Brit. Desm. 1848, p. 12(5, t. 21, f. 6 ;
Arch, in Pritch. Infus. 1861, p. 741 ; Eabenh. Flor. Europ. Alg. Ill,
1S6S, p. 201 ; Lnnd. Desm. Suec. 1871, p. 72, t. 4. f. 10; Wolle, Desin.
TJ. S. 1884, p. 120, t. 39, f. 1, 2 [figures poor] ; Cooke, Brit. Desm. 1887,
p. 165, t. 55, f. 8, t. 57, f. 1 ; De Toni, Syll. Alg. 1889, p. 1201 : West,
Alg. W. Ireland, 1892, p. 180 ; Alg. Engl. Lake Distr. 1892, p. 732 ;
Boy & Biss. Scott. Desm. 1893, p. 244 (sep. p. 26) ; Nordst. Index Desm.
1896, p. 263 ; W. & G. S. West, Alg. S. England, 1897, p. 494; Schmidle,
Lappmark Siisswasseralgen, 1898, p. 58 ; W. & Gr. S. West, Alga n.
Yorks. 1901, p. 103 ; Further Contrib. Freshw. Plankton Scott. Lochs,
1905, p. 486 ; Brit. Freshw. Phytoplankton, etc., 1909, p. 183.
Phycastrum tumidum Kiitz. Spec. Alg. 1849, p. 179.
Plenrenteriimi tumidum (Breb.) Wille in Engler & Prantl, Natiirl. Pfian-
zenfam. 1890, p. 11.
Temperea tumida (Breb.) Bougon in Le Micrograph e preparateur, v, 1897,
p. 68.
Cells very large, a little longer than broad, deeply
constricted, sinus open and acute-angled with a slightly
rounded apex; semicells very broadly subelliptic, apex
generally a little flattened and sometimes faintly con-
cave in the middle, lateral angles with a small button-
like thickening, which is sometimes replaced by a
small, solid mamilla. Vertical view triangular (rarely
quadrangular), with strongly convex sides, and a small
projecting mamilla at each angle. Cell- Avail punctate.
Chloroplasts forming 4-6 (?) parietal cushions in each
semicell.
Zygospore ovoid-oblong, with a thick lamellose
wall, furnished with a few, irregularly scattered,
conical papillae.
Length 112-134 /x; breadth 90-127 ju; breadth of
isthmus 44-50 /x ; length of zygosp. without papillae
176 jx, breadth 92 /x; length of papilla? 14 jx.
England. — Cumberland! Westmoreland ! (Bissett).
STAURASTRUM. 143
Lancashire ! Ilkley, W. Yorks ( W. H. Bikes) . Surrey !
Sussex (Rolfs). Hants! Devon! Cornwall!
Wales. — Capel Curig ! (Cooke and Wills), Llyn
Padarn, and near Dolbadarn Castle, Carnarvonshire !
Dolgellv, Merioneth ! (Balfs). Plankton of several
of the Welsh lakes !
Scotland. — Sutherland ! Ross ! Aberdeen, Kincar-
dine, Forfar, Perth ! (Boy Sf Bissett). Plankton of
Loch Luichart, Ross ! Lewis, Outer Hebrides !
Ireland. — Near Westporb, Mayo ! Gallery Bog,
Gal way (Archer). Carantuohill, Kerry ! Dublin and
WicMow (A rcher) .
Geogr. Distribution. — France. Germany. Galicia in
Austria. Norway. Denmark. Sweden. Bornholm.
United States.
St. tumidum is one of the largest and most distinctive
British species of the genus. The cells are usually enveloped
in a large mucilaginous envelope, which may attain a
diameter of 196^.
The semicells vary a little in outward form in front view
(Consult PI. CXXII, figs. 1 and 3 a). The form with the
triangular vertical view is much the commonest, but tetra-
gonal forms are sometimes met with, and we have on one
occasion observed an irregularly pentagonal form. The
mamillate thickening at each angle is sometimes prominent,
but in other individuals it may be rather obscure.
12. Staurastrum conspicuum W. & G. S. West.
(PL CXXI, figs. 1, 2.)
Staurastrum conspicuum W. & G. S. West, Scott. Freshw. Plankton, I.
1903, p. 547, t. 14, f . 4 ; Further Contrib. Freshw. Plankton Scott. Lochs,
1905, p. 486 ; British Freshw. Phytoplankton, etc. 1909, p. 181.
Cells very large, about 1| times broader than long,
very deeply constricted, sinus linear in the median
part, widely open outwards, and dilated at its
extremity ; semicells elliptic-fusiform, dorsal margin
convex but widely truncate in the middle, lateral
angles strongly thickened and mamillate. Vertical
view triangular, sides widely concave, angles acutely
144 BRITISH DESMIDIACE.E.
rounded and mamillate. Cell-wall delicately punctate-
scrobiculate.
Zygospore unknown.
Length 83-103 p; breadth 111-134/*; breadth of
isthmus 21-27 fi.
Scotland. — In the plankton of Loch Shin and Loch
Grhriama ; also in a small pool at Rhiconich, Suther-
land !
One of the largest and most striking species of the genns,
St. conspicuum can be compared with St. rnajusculum Wolle,
from which it differs in the form of its semicells, its sinus,
and the form of the vertical view. From St. grande it is at
once distinguished by the entirely different sinus, the
shape of its semicells, and the mamillate angles.
13. Staurastrum aver sum Lund.
(PI. CXX, figs. 9-13.)
Staurastrum aversum Lund. Desm. Suec. 1871, p. 59, t. 3, f. 27 ; Cooke in
Journ. Quekett Micr. Club, 1881, p. 206, t. 16, f. 36; Brit, Desm. 1887,
p. 166, t. 55, f . 6 ; De Toni, Syll. Alg. 1889, p. 1202 ; West, Alg. N.
Wales, 1890, p. 294 ; Eoy & Biss. Scott. Desm. 1893, p. 178 ; Nordst.
Index Desm. 1896, p. 54; W. & G. S. West, Notes Alg. Ill, 1903, p. 75;
Scott. Freshw. Plankton, I. 1903, p. 529; Further Contrib. Freshw.
Plankton Scott. Lochs, 1905, p. 486; Comp. Study Plankton Irish
Lakes, 1906, p. 86 ; Brit. Freshw. Phytoplankton, etc., 1909, p. 181.
Cells of medium size, about 1| times as long as
broad, deeply constricted, sinus acute-angled and
widely open ; semicells obversely elliptic-semicircular,
apex truncate or slightly retuse (rarely convex),
ventral margin very strongly convex, angles broadly
rounded, each furnished with a minute papilla.
Vertical view triangular, with broadly rounded angles
and slightly concave sides, each angle furnished with
a minute papilla. Cell- wall very delicately punctate.
Zygospore unknown.
Length 35-58 /x; breadth 29-45 /a ; breadth of
isthmus 10-17 [jl.
Wales.— Capel Curig! {Coolce Sf Wills), near Llan-
fairfechan, and Llyn-y-cwm-fTynon, Carnarvonshire !
Plankton of several of the Welsh lakes !
STAURASTRTJM. 145
Scotland. — Rliiconich, plankton of Lochs Shin and
Nan Cuinne, Sutherland ! Plankton of Loch Shiel,
Inverness ! Near Aboyne, Aberdeen ; Cammie, Kin-
cardine (Boy Sf Bissett). Plankton of Loch Fadaghoda
and four other lochs in Lewis ; plankton of Loch nan
Eun, N. Uist ; and plankton of Loch Mhorgain, Harris,
Outer Hebrides !
Ireland.— Plankton of small lakes between Clifden
and Roundstone, and of Lough Corrib, Gralway !
Geofjr. Distribution, — Norway. Sweden. United
States.
This characteristic species is practically confined to the
western lake-areas of the British Islands. It is most nearly
allied to St. brevispinum, but need never be confused with
that species, differing in the form of its semicells, in the
nature of its sinus, and in the less retuse sides of the vertical
view. We regard it as a very distinct species with a veiy
definite geographical distribution. It exhibits little variation
except in size.
14. Staurastrum brevispinum Breb.
(PI. CXXIII, figs. 1-3.)
Binatella brevispina Breb. in Cheval. microscop. et visage, 1839, p. 272.
Staurastrum brevispinum Breb. in Ralfs' Brit. Desm. 1848, p. 124, t. 34,
f . 7 a et b ; Arch, in Pritch. Infns. 1861, p. 737 ; Rabenh. Flor. Europ.
Alg. Ill, 1868, p. 202 ; Kirchn. Alg. Schlesien, 1878, p. 168 ; Wolle,
Desm. U. S. 1884, p. 121, t, 53, f. 2, 3 ; Cooke, Brit. Desm. 1887, p. 140,
t, 49, f. 4 ; Hansg. Prodr. Algenfl. Bohm. 1888, p. 211 ; De Toni, Syll.
Alg. 1889, p 1140 ; West, Add. Alg. W. Yorks. 1891, p. 247 ; Alg. Engl.
Lake Distr. 1892, p. 730 ; Liitkem. Desm. Attersees, 1893, p. 563 ; Roy
& Biss. Scott. Desm. 1893, p. 179 (sep. p. 18) ; Nordst. Index Desm.
1896, p. 69 ; W. & G. S. West, Alg. S. England, 1897, p. 492 ; Schmidle,
Lappmark Siisswasseralgen, 1898, p. 50 ; W. & G. S. West. Alga-fl.
Yorks. 1900, p. 97 ; Borge, Siisswasseralgen Siid-Patagon. 1901, p. 27 ;
W. & G. S. West, Alg. N. Ireland, 1902, p. 44 ; Freshw. Alg. Orkneys
and Shetlands, 1905, p. 24, t. 1. f. 32 ; Further Contrib. Freshw.
Plankton Scott. Lochs. 1905, p. 486 ; Comp. Stndy Plankton Irish
Lakes, 1906, p. 86; Borge, Beitrage Alg. Schweden, 1906, p. 44;
Larsen, Ferskvandsalg. Vest-Gronl. 1907, p. 348; W. & G. S. West,
British Freshw. Phytoplankton, etc., 1909, p. 181.
St. brevispinum forma minor Rabenh. Flor. Europ. Alg. Ill, 1868, p. 202 ;
Boldt, Siber. Chlorophy. 1885, p. 113 ; Larsen, Freshw. Alg. E. Green-
land, 1904, p. 96.
St. muticum Breb. var. brevispinum (Breb.) Jacobs. Desm. Danem. 1876,
p 202.
St. brevispinum var. minor Roy & Biss. Jap. Desm. 1886, p. 237.
St. brevispinum forma hexagona Eichl. & Gutw. Nonn. spec. alg. nov.
1894, p. 175, t. 5, f. 48.
VOL. IV. 10
14G BRITISH DESMIDlACEiE.
Cells rather under medium size, about as long as
broad, deeply constricted, sinus open and acute-angled,
very narrow at the extremity ; semicells oblong-elliptic,
ventral margin frequently more convex than dorsal
margin, apex convex, subtruncate, or sometimes slightly
retuse in the middle, lateral angles rounded and fur-
nished with a small mucro or papilla. Vertical view
triangular, with concave sides and rounded angles,
each allele furnished with a small mucro. Cell-wall
smooth.
Zygospore unknown.
Length 27-50;u; breadth 27-49 [x; breadth of
isthmus 8-17 /i.
England. — Westmoreland! (Bissett). Hawkshead
and Hampsfell, Lancashire ! Malham Tarn, W. Yorks !
Gormire and Pilmoor, N. Yorks ! Riccall Common,
E. Yorks ! Thursley Common, Surrey ! Sussex
(Balfs). New Forest, Hants ! (Boy). Cornwall
(Balfs).
Wales. — Capel Curig, Carnarvonshire ! Plankton
of Llyn Ogwen !
Scotland. — Sutherland, Inverness !, Aberdeen, Kin-
cardine, Forfar, Perth (Boy Sf Bissett). Plankton of
Loch Shiel, Inverness ! Loch Stranabhat, Lewis,
Outer Hebrides ! Plankton of Shetlands !
Ireland. — E. of Glenties, Donegal ! Plankton of
lakes in Mayo, Galway, and Kerry ! Dublin and
Wicklow (Archer). Plankton of Loughs Neagh and
Beg ! Lough Fea, Londonderry !
Geogr. Distribution. — France. Germany. Switzer-
land. Austria and Galicia. Hungary. Macedonia.
Servia. Italy. Norway. Sweden. Denmark. Born-
holm. Poland. N. Russia (var.). Iceland. Green-
land. NovaZembla. Siberia. India. Abyssinia (var.).
Central Africa. United States. Paraguay. Patagonia.
St. brevispiuum is a well-marked and widely distributed
species. It is distinguished from St. aversum by the shape
of the semicells and the sinus, the latter being- almost
mucronate at the extremity. The short papillas at the angles
ST AURA STRUM. 147
are similar to those in St. aversum, but in most cases are
rather stronger and firmer. Owing- to the varying- degrees
of convexity of the lower margin of the semicells the position
of the angular papillae is not quite constant, and they some-
times have a distinct upward direction (Consult PL CXXIII,
figs. 3 a and a').
The zygospores recorded by Cushman (' Bull. Torr. Bot.
Club,' xxxii, 1905, p. 226, t. 8, f. 12, 13) under the name of
St. brevispinum do not appear to us to belong to this species,
but rather to some form of St. Dickiei. The angles of the
semicells as figured by Cushman are much too acutely rounded
(exclusive of the short spines) for any form of St. brevi-
spinum.
Liitkemuller (f Desm. Millstattersees/ 1900, p. 78) has
described a " forma minima" of this species (length 20 ju ;
breadth 22" 5 p ; breadth of isthmus 7'5/x).
Forma major W. & G. S. West. (PL CXXIII, fig. 4.)
St. brevispinum forma major W. & G-. S. West, Phytoplankton Engl. Lake
Distr. 1909, p. 290, f . 6 E (p. 291).
Cells larger and somewhat inflated.
Length 59-63 fx ; breadth 52-57 p. ; breadth of
isthmus 16-17 p.
England. — Plankton of Thirlmere, Cumberland !
Plankton of Brothers' Water and Ullswater, West-
moreland !
Var. Boldtii Lagerh.
St. brevispinum forma Boldt, Siber. Chlorophy. 1885, p. 113, t. 5, f. 30.
St. brevispinum var. Boldtii Lagerh. Chlor. Abessin. u. Kordofan, 1893,
p. 163.
St. brevispinum forma Boldtii Turn. Freshw. Alg. E. India, 1893, p. 130,
t. 16, f. 45 (?).
Cells proportionately longer, semicells more broadly
elliptic.
Length 47 p; breadth. 35 p; breadth of isthmus
13*5 p..
Geogr. Distribution.— -Siberia. Abyssinia. India (?).
This variety as figured by Boldt does not occur in the
British Islands, but a form of it is known from Scotland : —
148 BRITISH desmidiacej-:.
Forma retusa (Borge) nob. St. brevispinum var. retusum
Borge, Sussw. Chlor. Archang. 1894, p. 36, t. 3, f . 42 ; W. & G.
S. West, Scott. Freshw. Plankton, I. 1903, p. 546, t. 14, f. 6.
Apex of semicell slightly retuse in the middle, angles of
semicells very broadly rounded. (PI. CXXIII, fig. 6.)
Length 43-52 /< ; breadth 36-41 fi ; breadth of isthmus
13-14 n-
Scotland. — Loch Nan Cuinne and Loch Euar, Sutherland !
(.7. Murray). Loch Fadaghoda, Lewis, Outer Hebrides I
Geogr. Distribution. — X. Russia.
Var. altum W. & G. S. West. (PL CXXIII, fig. 5.)
St. brevispinum var. altum W. & G. S. West, Further Contrib. Freshw.
Plankton Scott. Lochs, 1905, p. 502, t. 7, f. 16; Comp. Study Plankton Irish
Lakes, 1906, p. 86 ; Brit. Freshw. Phytoplankton, etc., 1909, p. 181.
Cells longer than broad, dorsal margin of semicells
very strongly convex (almost subsemicircular) ; in the
vertical view with the sides less concave and the
angles thicker.
Length 57-66 fx ; breadth 43-50 /x ; breadth of
isthmus 12"5-15*3 \x.
Scotland. — Plankton of Lochs Nan Cuinne and
Ruar, Sutherland ! (J. Murray) ; Lochs Fadaghoda,
an Sgath, and an Tomain, Lewis; and Loch Diracleet,
Harris, Outer Hebrides !
Ireland. — Plankton of Lough Corrib, Gal way !
Var. obversum \X . & G. S. West. (PI. CXXIII,
fig. 7.)
St. brevispinum var. obversum W. & Gr. S. West, Further Contrib. Freshw-
Plankton Scott. Lochs, 1905, p. 502, t. 7, f. 15 ; British Freshw. Phyto-
plankton, etc., 1909, p. 181.
Cells broader than long, sinus narrow and sub-
linear towards the extremity ; semicells obverselv
semi-elliptic, with a prominent papilla at each superior
angle, dorsal margin slightly convex, ventral margin
very strongly convex.
Length 38-42 fx ; breadth 45-49 '5 fx ; breadth of
isthmus 10*5-11 jx.
Scotland. — Plankton of Loch Fadaghoda, Lewis,
Outer Hebrides !
STAURASTEUM. 140
Var. inerme Wille.
St. brevispinum var. inerme Wijle, Ferskv. Alg. Nov. Semli. 1879, p. 52,
t. 13, f. 62.
Cells larger, sinus more open with a rounded
extremity, isthmus wider; sides of vertical view less
retuse; angles of semicells destitute of a papilla or
nmcro.
Length 7o ja ; breadth 60 /x ; breadth of isthmus
24 p.
England. — Woodbury Common, Devonshire ! (R.
Morgan).
Geogr. Distribution. — NovaZembla. United States (?).
It is possible that this variety should be relegated else-
where. The rounded sinus and the entire absence of the
small macros are characters which separate it somewhat
widely from all other known forms of St. brevispinum.
15. Staurastrum lanceolatum Arch.
(PI. CXXI, figs. 3-6.)
Staurastrum lanceolatum Arch. Descript. New Cosm. etc. 1862, p. 79, t. 2,
f. 16-22; Eabenh. Flor. Europ. Alg. Ill, 1868, p. 202; Nordst. Desm.
Spetsb. 1872, p. 38 ; Desm. Arctose, 1875, p. 33 [forms] ; Wille, Ferskv.
Alg. Nov. Semlj. 1879, p. 51 ; Cooke, Brit. Desm. 1887, p. 158, t. 54, f. 2 ;
De Toni, Svll. Alg. 1889, p. 1182 : West, Alg. N. Wales, 1890, p. 293;
Alg. W. Ireland, 1892, p. 178 ; Koy & Biss. Scott, Desm. 1893, p. 22
(sep.) ; Nordst. Index Desm. 1896, p. 155 ; W. & G. S. West, Alg. S.
England, 1897, p. 493 ; Larsen, Ferskvandsalg. Vest-Gronl. 1907, p. 350.
Cells very small, about as long as broad, very
deeply constricted, sinus open and acute-angled, sides
of sinus almost straight; semicells elliptic-lanceolate,
dorsal margin more convex than the ventral margin,
lateral angles acute and minutely apiculate (although
the apiculus is sometimes difficult to detect). Vertical
view triangular (or more rarely quadrangular), angles
very slightly inflated and minutely apiculate, sides
concave in the middle. Cell-wall smooth.
Zygospore globose, furnished with numerous,
slender, acute spines.
Length 15-29 [jl; breadth lo-28[x; breadth of
150 BRITISH DESMIDIACE^.
isthmus 9-14 /x; diam. zygosp. without spines 22-
25 ix, with spines 37-40 /a.
England. — Borrowdale, Cumberland ! Thursley
Common, Surrey! New Forest, Hants (with zygo-
spores) ! Near St. Just and Halgavor Moor, Corn-
wall !
Wales. — Capel Curig !, and Glyder Fawr (Boy),
Carnarvonshire.
Scotland. — Ross, Aberdeen, Kincardine, Forfar,
Perth ; zygospores from Aberdeen and Kincardine
(Boy fy Bissett). Glen Nevis, Inverness!
Ireland. — Lough Clogher, and Errigal, Donegal !
Adrigole, Cork! Dublin and Wicklow (Archer).
Geogr. Distribution. — Germany. Bavaria. Sweden.
Nova Zembla. Spitzbergen. Greenland. United
States.
St. laiiceolatum is a rare species with very distinct
characters. The quadrangular forms appear to be mostly
confined to arctic areas.
In the above description we have combined the three
forms (f. minor, f. media, and f. major) mentioned by Nord-
stedt in his ' Desm. Arctoa?,' p. 33, as it is unwise to draw
arbitrary lines of demarcation such as would be required to
separate these forms.
Var. compressum W. & G. S. West. (PI. CXXI,
fig. 7.)
St. lanceolatum var. compressum W. & G. S. West, New Brit. Freshw.
Alg. 1894, p. 11, t. 1, f. 22 ; Some N. Amer. Desiu. 1896. p. 261 ; Alg. S.
England, 1897, p. 493.
Cells somewhat compressed, sinus narrower espe-
cially at the extremity ; apex of semicells flattened ;
sides of vertical view more distinctly concave.
Length 17-3-17-5 /x; breadth 21-21-2 /*; breadth of
isthmus 7 '5 /a.
England.— New Forest, Hants !
Scotland. — Lewis, Outer Hebrides !
Geogr. Distribution. — United States.
STATJRASTRUM. 151
16. Staurastrum pachyrhynchum Nordst.
(PI. CXXI, figs. 8, 9.)
Staurastrum pachyrhynchum Nordst. Desm. Arctose, 1875, p. 32, t. 8, f . 34 ;
Boldt, Siber. Chlorophy. 1885, p. Ill ; De Toni, Syll. Alg. 1889, p. 1185 ;
Borge, Bidr. Siber. Chlor. 1891, p. 9, t. 1, f . 5 ; Eoy & Biss. Scott. Desm.
1893, p. 241 (sep. p. 23) ; Borg. Ferskv. Alg. Ostgronl. 1894, p. 24, t. 2,
f . 19, 20 [forms] ; Nordst. Index Desm. 1896, p. 193 ; W. & G. S. West,
Alg. S. England, 1897, p. 494 ; Some Desm. U. S. 1898, p. 314 ; Larsen,
Freshw. Alg. E. Greenland, 1901, p. 99 ; Ferskvandsalg. Vest-Gronl.
1907, p. 351.
Cells somewhat small, about as long as broad, deeply
constricted, sinus open, subrectangular or acute-angled ;
semicells subelliptic or elliptic-subtriangular, dorsal
margin subtrnncate, convex or strongly convex, angles
very slightly (almost imperceptibly) produced, rounded-
obtuse, usually with a very faint upward tilt. Vertical
view 3-5-angular, sides concave, angles rounded-obtuse.
Cell-wall smooth or very delicately punctate, very
strongly thickened at the angles.
Zygospore unknown.
Length 28-45 ju ; breadth 22-45 fx; breadth of
isthmus 8-15 /x.
England. — Thursley Common, Surrey ! New Forest,
Hants !
Wales. — Capel Curig, Carnarvonshire !
Scotland. — Slewdrum and Heughhead near Aboyne,
Aberdeen (Roy 8f Bissett).
Ireland. — Dublin and Wicklow (Archer).
Geogr. Distribution. — Germany. Austria (var.).
Sweden. Poland (var.). Nova Zembla. Spitz-
bero-en. Greenland. Siberia. United States. Para-
guay (form).
In British and American specimens Ave have found tin-
thickened angles of the semicells directed horizontally in the
front view. In arctic specimens they appear usually to have
a faint upward or divergent tilt, h\ a form described by
Raciborski as "var. convergens" (Racib. 'Desm. Nowe/ 1889,
p. 98, t. 7, f. 14), and known to occur in Poland, (lermany,
and Austria, the angles of the semicells are decidedly con-
vergent.
We do not agree with Stockmayer (in * Osterr. botan
152 BRITISH DESMIDIACE.E.
Zeitschr.' 1906, no. 2, p. 6) in regarding this species as a
form of St. Clejisydra Nordst.
1 7. Staurastrum Clepsydra Nordst.
(PI. CXXII, fig. 6.)
Staurastrum Clepsydra Nox-dst. Desm. Brasil. 1870, p. 224, t. 4, f. 47 [a
obtusum and (3 acuminatum'] ; Lagerh. Bidr. Amerik. Desm.-fl. 1885,
p. i46; De Toni, Syll. Alg. 1889, p. 1139; Boy & Biss. Scott. Desm.
1893, p. 179.
Cells small, as broad as long or a little broader ;
very deeply constricted, sinus widely open, sub-
rectangular or aciite-angled ; semicells obversely
subtriangular, sides convex, apex straight or convex,
angles very slightly produced and sometimes sub-
mucronate. Vertical view triangular, sides very
slightly concave, angles very little rounded and some-
times submucronate. Cell-wall smooth.
Zygospore unknown.
Length 27-31 /x; breadth 27-oG//,; breadth of
isthmus 6-8 fi.
Scotland. — Aclmerran in Logie-Coldstone, Aber-
deen (Roy Sf Bissett).
Geogr. Distribution. — Norway. Sweden. Poland.
Spitzbergen. Greenland. United States. Brazil.
The characters of this species are a little obscure, and we
have not personally seen any Desmid exactly agreeing with
Nordstedt/s original figure. We are, however, acquainted
with a small Desmid, described by Borge in 1891 as " St.
tdbericum," which we think cannot with justice be separated
from St. Clepsydra.
Var. sibericum (Borge) nob. (PI. CXXII, figs. 7, 8.)
Staurastrnm sibiricum Borge, Bidr. Siber. Chlor. 1891, p. 9, t. 1, f. 4
[forma ovalis] ; W. & G. S. West, Further Contrib. Freshw. Plankton
Scott. Lochs, 1905, p. 502, t. 7, f. 20; Brit, Freshw. Phytoplankton,
etc., 1909, p. ]83.
Cells smaller and less deeply constricted. Vertical
view fusiform or triangular.
Forma ovaus Borge, 1. c. Vertical view fusiform,
poles slightly rounded and almost imperceptibly pro-
duced. Length 17-20 ,u ; breadth 17-21 yu ; breadth of
isthmus 7'5-8'bju; thickness 8-9//.
STAURASTRUM. 153
Scotland. — Plankton of Loch Fadaghoda, Lewis,
Outer Hebrides !
Geogr. Distribution. — Siberia.
F< irma tkigona nob. St. sibericu m Borge forma trigona
W. & G. S. West, New and Int. Freshw. Alg. 1896, p.
157, t. 4, f. 39; Alg. S. England, 1897, p. 493- Some
Desm. U. S. 1898, p. 312. Vertical view triangular with
slightly concave sides and subacute angles. Leno-th
13- o-l& o fx ; breadth 15—16 ^u ; breadth of isthmus 3'8-
8-5 ,x.
England. — Devil's Jumps, Frensham Common,
Surrey !
Geoijr. Distribution. — United States.
One specimen of this form was noticed with a wide
gelatinous investment 39 fx in diameter.
18. Staurastrum inelegans W. & G. S. West.
(PI. CXXIV, figs. 2-4.)
Staurastrum inelegans W. & G. S. West, Further Contrib. Freshw. Plank-
ton Scott. Lochs, 1905, p. 501, t. 7, f. 11, 12 ; Brit. Freshw. Phytoplank-
ton, etc., 1909, p. 182.
Cells of medium size, as long as broad or a little
broader, deeply constricted, sinus very wide and
obtusely rounded at the extremity, isthmus shortly
cylindrical ; semicells widely subtriangular, inferior
margins almost straight or slightly biundulate, dorsal
margin (apex) convex in the middle, angles produced,
acute or apiculate (rarely subobtuse). Vertical view
triangular, sides convex in the middle, angles sub-
mamillate and slightly apiculate. Cell-wall smooth.
Zygospore unknown.
Length 53-5-60 /x ; breadth 51-02 fx ; breadth of
isthmus 9-10 fx.
Scotland. — Plankton of Loch Fadaghoda, Lewis,
Outer Hebrides !
This remarkable Staurastrum, so far only observed from
the one locality, is somewhat variable in its characters. The
angles of the semicells are generally produced, and either
acute or apiculate, but in some specimens they are relatively
154 beitish desmidiacej:.
obtuse. They may be horizontally disposed, but are more
often slightly turned upwards. The shortly cylindrical
isthmus is also characteristic.
St. inelegans undoubtedly stands near to St. Clepsydra, but
differs in its more produced angles, its more elevated apices,
its elongated isthmus, and in the form of the vertical view.
It is also a larger species.
19. Staurastrum angulatum West.
(PL CXXIII, figs. 8, 9.)
Staurastrum angulatum West, Desm. Mass. 1889, p. 20, t.3,f. 20 ; Nordst.
Index Desm. 1896, p. 44.
Cells of medium size, about l\ times as long as
broad, deeply constricted, sinus widely open and acute-
angled ; semicells rhomboid with straight sides and
very slightly rounded angles. Vertical view triangular,
sides faintly retuse in the middle, angles a little inflated
and subacute. Cell-wall smooth.
Zygospore unknown.
Length 76-79 /x ; breadth 60-62 /x ; breadth of
i sthmu s 1 7— 1 8 ' 5 /x.
Geogr. Distribution. — United States.
The typical form of this species is not known to occur in
the British Islands. It was originally found in collections
from Amherst, Massachusetts. There is a faint indication of
an obscure mucro at the angles of the semicells.
Var. planctonicum W. & G. S. West. (PI. CXXIII,
fig. 10.)
St. angulatum var. planctonicum W. & G. S. West, Scott. Freshw. Plank-
ton,'I. 1903, p. 551; t. 16, f. 10; Brit. Freshw. Phytoplankton, etc.,
1909, p. 181.
Colls smaller, almost as broad as long, semicells
rhomboid-depressed, each angle furnished with a small
apiculus.
Length 47 /x ; breadth 44-46 /x; breadth of isthmus
9-5-10-5 /x.
Scotland— Plankton of Loch Shin, Sutherland !
ST AURA STRUM. 155
20. Staurastrum orbiculare Raits.
(PI. CXXIV, figs. 10, 11.)
? Desmidium orbiculare Ehrenb., 1834; Infus. 1838, p. 14-1, t. 10, f. ix.
Staurastrum orbiculare [? Menegh. Synops. Desm. 1840, p. 22-T ; Ealfs in
Ann. Mag. Nat. Hist xv, 1845, p. 152, t. 10, f. 4; Ralfs, Brit. Desm.
1848, p. 125, t. 21, f. 5 ^i and i ? [not figs. 5 a-g] ; Arch, in Pritch.
Infus. 1861, p. 740 ; Rabenh. Flor. Europ. Alg. Ill, 1868, p. 200 ; Lund.
Desm. Suec. 1871, p. 56 ; Delp. Desm. subalp. 1877, p. 37. t. 10, f. 11
and 12 [not f. 5-10] ; ? Wolle, Desm. U. S. 1884, p. 120, t. 39, f. 9, 10;
? De Toni, Syll. Alg. 1889, p. 1180 ; Nordst. in Wittr., Nordst. & Lagerb.
Alg. Exsic. 1903, no. 1472 ; fasc. 35, 1903, p. 9 [in part].
Goniocystis (Trigonocystis) orbicularis Hass. Brit. Freshw. Alg. 1845,
p. 349, t. 84, f. 7.
Phycastimm orbiculare Kiitz. Phyc. germ. 1845, p. 137.
Didymidium (Staurastrum) orbiculare Eeinsch, Algenfl. Frank. 1867,
p. 152 [in part],
r Staurastrum orbiculare forma punctata Grutw. Wahr. d. Prioritiit, 1890,
p. 71 ; Flor. Glon. Okolic Lwowa, 1891, p. 65, t. 3, f. 10.
St. Farquharsonii, Roy & Biss. Scott. Desm. 1893, p. 237, t. 4, f. 3.
St. hibernicum West var. Farquharsonii (Roy & Biss.) W. & Gr. S. West,
Notes Alg. II, 1900, p. 296, t. 412, f. 21.
Cells of medium size, a little longer than broad,
almost circular in general outline, very deeply con-
stricted, sinus narrowly linear with a slightly dilated
extremity ; semicells subsemicircular, apex a little
depressed but scarcely truncate, basal angles some-
what rounded. Vertical view triangular, sides slightly
concave, angles broadly rounded. Cell-wall punctate.
Zygospore unknown.
Length 54*4-56 p; breadth 46*5-49 /a; breadth of
isthmus ll-12-o fx.
England.— Hampsfell, Lancashire ! Cornwall (Ralfs) .
Scotland — Alford, Aberdeen (Boy fy Bissett).
Geogr. Distribution. — Germany. Austria (?). Sweden.
Finland. Italy.
The Desmid described above must be taken as the typo
form of St. orbiculare, as it is identical with the Staurastrum
described and figured by Ralfs in 1845 under that name.
Ralfs identified his plant with "Desmidium orbiculare
Ehrenb.," but as that is open to some doubt, Ave regard Ralfs
as the author of the species.
In 1848, although Ralfs did not alter his description, he
included other forms among his figures. Thus, of the figures
in his ' British Desmids,' t. 21, only figs. 5 h and i represent
typical St. orbiculare, and even these figures are not good.
15(> BRITISH DES.MIIUACEJE.
Ralfs5 figs. 5 a-g represent another form of the species
which we have here named "var. Ralfsii." This is the
form which most authors, ourselves included, have until
recently regarded as the type form of the species, an error
due to the fact first pointed out by Nordstedt in 1903, that
no one had taken the trouble to go back to Ralfs' original
account in the 'Annals and Magazine of Natural History '
for 1845.
St. Farquharsonii Roy & Biss. is this species in its most
typical form.
Var. hibernicum nob. (PL CXXIV, figs. 5-9.)
St. orbiculare forma in Wittr. & Nordst. Alg. Exsic. 1878, no. 107.
? St. cordatum Gay, Monogr. loc. Conj. Montpellier, 1884, p. 65, t. 2, f. 7 ;
De Toni, Syll. Alg. 1889, p. 1194.
St. hibernicum West, Alg. W. Ireland, 1892, p. 177, t, 23, f. 6 ; Alg. Engl.
Lake District, 1892, p. 731 ; Notes Alg. II, 1900, p. 296, t. 412, f. 20.
St. orbiculare var. extensu.m Nordst. forma major Schmidle, Beitr. alp. Alg.
1896, p. 61.
St. orbiculare in Nordst., Wittr., & Lagerh. Alg. Exsic. 1903, no. 1472 ;
t'asc. 35, 1903, p. 9 [in part], f. 1-6 (p. 10).
Cells often a little larger than the type ; semicells
with the basal angles less rounded and the apex broadly
truncate ; vertical view somewhat variable in the
width of the angles ; cell- wall punctate as in the
type.
Length 42-65 /a ; breadth 36-50 /a; breadth of
isthmus 9*5-20 /a.
England. — Near Bowness and Loughrigg, West-
moreland !
Ireland. — Near Westport, Mayo !
Geogr. Distribution. — France (?). Austria. Sweden.
This is the largest form of St. orbiculare and is principally
characterized by the more pronounced basal angles of the
semicells and the flattened apices.
Var. Ralfsii var. hoc, (PL CXXIV, figs. 12, 13, 15, 16.)
St. orbiculare Ralfs, Brit. Desm. 1848, t. 21. f. 5 a-a ^not 5 h and i] ; Delp.
Desm. snbalp. 1877, p. 37 (sep. p. 133), t. 10, f. 8-10; Wille, Ferskv. Alg.
Nov. Semlj. 1879, p. 49 ; Gay, Monogr. loc. Conj. Montpellier, 1884,
p. 65 ; Cooke, Brit. Desm. 1887, t. 51, f. 7 [figures poor] ; Hans<j. Prodr.
Algenfi. Bohm. 1888, p. 254 ; West, Alg. N. Wales, 1890, p. 293 ; Alg.
W. Ireland, 1892, p. 176; Alg. Engl. Lake Distr. 1892, p. 731 ; Roy &
Hiss. Scott. Desm. 1893, p. 23 (sep.) ; W. & G. S. West, Alg. S. Engl.
1897, p. 494 ; Alga-fl. Yorks. 1900, p. 100 ; Alg. N. Ireland, 1902, p. 49 ;
STAURASTRTJM. 157
Scott. Freshw. Plankton, I. 1903, p. 529; Freshw. Alg. Orkneys &
Shetlands, 1905, p. 25; Further Contrib. Freshw. Plankton Scott.
Lochs, 1905, p. 486; Brit. Freshw. Phytoplankton, etc., 1909, p. 182.
Semicells subtriaiigular, basal angles and apex
rounded, sides slightly convex ; cell-wall smooth.
Zygospore globose, furnished with numerous, simple,
acute spines.
Length 31-41 /a; breadth 22-36 /a ; breadth of
isthmus 7-11 ^ ; diam. zygosp. without spines 36-40 /x,
with spines 60-66 jx.
England. — Cumberland! Westmoreland! Lan-
cashire! W., N., and E. Yorks ! Cheshire (Roy).
Leicestershire (Boy). Bucks ! Warwick (Wills).
Sussex ! Kent ! Hants ! Devon ! Cornwall !
Walks. — General (but scarce) !
Scotland. — General, and often conjugated (Boy fy
Bissett). Inverness ! Ayr ! Wigtown ! Lewis, Outer
Hebrides ! Orkneys ! Shetlands ! Rare in the plankton !
Ireland. — Donegal ! Mayo (and Clare Island) !
Galway ! Kerry! Dublin and Wicklow (Archer).
Down ! Londonderry !
Geogr. Distribution. — France. Germany. Switzer-
land. Austria and Galicia. Hungary. Servia. Italv.
Portugal. Norway. Sweden. Denmark. Bornholm.
Finland. Poland. N., Central, and S. Russia.
Faeroes. Iceland. Nova Zembla. Spitzbergen.
Greenland. E. and N. India. Australia. United
States. Brazil. Bolivia. Paraguay. Argentina.
Patagonia.
This is much the most abundant and widely distributed of
all the forms of St. orbiculare, and one which has generally
been accepted as the type form. We have ourselves
invariably, although erroneously, recorded it as such. Its
most important character is the elevated apex of the semicell,
giving the latter a subtriaiigular outline. This variety and
var. eztensum Nordst. are the only forms of St. orbiculare of
which the zygospores are known.
A large form — forma major [= St. orbiculare f. major West,
'Alg. Engl. Lake Distr.' 1892, p. 731] — is known from near
Bowness, Westmoreland ; length 61 /.i ; breadth 50 n ; breadth
of isthmus 17*5 /i.
158 BRITISH DKS.MIDIACE.E.
Var. depressum Roy & Biss. (PL CXXIV,
figs. 17-19.)
St. orbiculare var. depressum Roy & Biss. Jap. Desrn. 1886, p. 237, t. 268,
f 14 ; Nordst. Freshw. Alg. N. Zeal. 1888, p. 42 ; West, Alg. W. Ireland,
1892, p. 177 ; Alg. Engl. Lake Distr. 1892, p. 731 ; W. & G. S. West,
Alg. S. England, 1897, p. 494 ; Alga-fl. Yorks. 1900, p. 100 ; Freshw.
Chlorophy. Koh Chang, 1901, p. 178; Alg. N. Ireland, 1902, p. 49;
Freshw. Alg. Orkneys and Shetlands, 1905, p. 25 ; Brit. Freshw. Rhyto-
plankton, etc., p. 182.
Cells small, as long as broad, semicells much
depressed ; cell- wall smooth.
Length 22-27 /x; breadth 20-27 /x ; breadth of
isthmus 6-7*5 /x.
England. — Near Bowness, Westmoreland ! Hawks-
head, Lancashire ! Malham Tarn and near Clapham,
W. Yorks ! Pilmoor and Strensall, N. Yorks ! Riccall
and Skip with Commons, E. Yrorks ! Dernford Fen
and Wicken Fen, Cambridge ! Chobham and Witley
Commons, Surrey ! New Forest, Hants ! Near
the Lizard, Cornwall !
Wales. — Llvn Idwal and Y Foel Fras, Carnarvon-
shire ! Brecon !
Scotland. — Rhiconich, Sutherland ! At 3500 ft. on
Lochnagar, Aberdeen ! Ben Laoigh, Perth ! Tents
Moor, Fife {Boy Sf Bissett). Renfrew ! Near Loch
Doon, Ayr ! Orkneys and Shetlands, in both the bogs
and the plankton !
Ireland. — Donegal ! Mayo ! Gralway ! Kerry !
Londonderry !
Geogr. Distribution. — Galicia in Austria. Sweden.
N. Russia, Central China. Japan. Siam. Australia.
New Zealand. Madagascar.
Var. extensum Nordst. (PI. CXXV, figs. 1, 2.)
St. orbiculare var. extensum Nordst. Norges Desm. 1873, p. 26, t. 1, f. 10 ;
Desm. Ital. 1876, p. 42 ; West, Alg-. Eng. Lake Distr. 1892, p. 731 ;
Notes Alg. II, 1900, p. 296, t. 412, f. 19 ; Alga-fl. Yorks, 1900, p. 100.
Cells 1^ times as long as broad ; semicells relatively
higher and more inflated.
Zygospores exactly similar to those of var. Balfsii.
STAURASTRUM. ] 59
Length 38-48 /x; breadth 25*5-36 fi; breadth of
isthmus 8-14 /x.
England.— Stye Head Tarn, Cumberland ! Rydal
Fell, Westmoreland ! Near the side of Windermere,
Lancashire! Cautley Spout, Cocket Moss near
Giggleswick, Ogden Clough, and Arncliffe (with
zygospores), W. Yorks ! Mickle and Cronkley Fells,
and bog near Widdale Beck, IN". Yorks !
Wales. — At over 3000 ft. on Snowdon, Carnarvon-
shire !
Scotland. — General, but scarce; zygospores from
near Dinnet, Aberdeen (Roy Sf Bissetl).
Geogr. Distribution. — Germany. Austria. Norway.
21. Staurastrum suborbiculare W. & G. S. West.
(PI. CXXV, figs. 3-5.)
Staurastrum orhiculare Ralfs forma? Roy & Biss. Scott. Desm. 1893, t. 4,
f.7.
St. suborbiculare W. & G. S. West, New and Int. Freshw. Alg. 1896, p. 158,
t. 4, f. 48 ; Alga-fl. Yorks. 1901, p. 101.
Cells small, about as long as broad, very deeply
constricted, sinus narrowly linear ; semicells pyrami-
date-subsemicircular, basal angles slightly rounded,
sides convex, apex narrow and faintly retuse. Vertical
view triangular, angles rounded, sides almost straight
(very slightly concave). Cell-wall minutely and densely
punctate.
Zygospore globose, densely covered with small
conical verrucas, each of which bears a very short
spine at its apex.
Length 35-44ja; breadth 35-38 /x ; breadth of
isthmus 7'5— 9'5 /x ; diam. zygosp. with short spines
37*5-45 /x.
England.— Cam Fell, W. Yorks !
Scotland. — Glas Mhoel, Perth (with zygospores) !
Tins species is distinguished from St. orhiculare var. Ralfsii
by the more depressed semicells, with retuse apices; and hy
the very different nature of the zygospore.
160 BRITISH DESMIDIACEJE.
22. Staurastrum retusum Turn.
(PL CXXV, figs, 6, 7.)
Staurastrum retusum Turn. Freshw. Alg. E. India, 1S93, p. 104, t. 13, f. 13;
Nordst. Index Desm. 1896, p. 224.
St. retusum var. pimctulatum Eichl. & Grutw. Nonn. spec. alg. nov. 1894,
p. 174, t. 5, f. 45 ; W. & G. S. West, Freshw. Alg. Ceylon, 1902, p. 178 ;
Freshw. Alg. Burma, 1907, p. 216, t. 15, f. 30-32.
Cells small, as long as broad, very deeply constricted,
sinus narrowly linear with a slightly dilated extremity ;
semicells shortly pyramidate-trapeziform, angles a
little rounded, lateral margins straight, convex, or
concave, apex very slightly concave. Vertical view
triangular, angles rounded, sides concave. Cell- wall
finely punctate, punctulations much more pronounced
at the angles.
Zygospore unknown.
Length 15*5-30 /a; breadth 15*5-30 /a ; breadth of
isthmus 3*6—10 /x.
Geogr. Distribution. — Poland. India. Ceylon. Burma.
We have mentioned on two previous occasions that the var.
punctulatum should most probably be regarded as identical
with the original form. All the tropical forms of this species
which have been found since the publication of Turner's
description are punctulate, and Turner himself, judging by his
expression " glabras ? ", was doubtful concerning this point.
It should also be remembered that the figure given by Turner
is from an old drawing of Wallich's, and is probably far from
good.
The typical form of this species is not known to occur in
the British Islands.
Var. boreale W. & G. S. West. (PI. CXXV, fig. 8.) S
St. retusum var. boreale W. & G. S. West, Freshw. Alg. Orkneys and
Shetlands, 1905, p. 25, t. 2, f. 30.
Cells smaller ; semicells more rounded, lateral
margins convex, apices very slightly retuse ; cell- wall
smooth.
Length 17*5-19 fx; breadth 16*2-17*5 ll; breadth of
isthmus 5*5 /x.
Scotland. — Hoy, Orkneys ! In bog near Lerwick,
Shetlands !
STAURASTRUM. 161
23. Staurastrum Cosmarioides Nordst.
(PL CXXV, figs. 11, 12.)
Staurastrum Cosmarioides Nordst. Desm. Brasil. 1870, p. 223, t. 4, f. 43 ;
Alg. Brasil. 1877, p. 23 : De Toni, Svll. Alg. 1889, p. 1194 ; Borg. Desm.
Brasil. 1890, pp. 49, 50, f. 1-6 [formse1 ; W. & G. S. West, Some Desm.
U. S. 1898, p. 313 ; Alga-fl. Yorks. 1901, p. 103.
Cells of various magnitudes, generally of medium
size or rather large, about twice as long as broad,
deeply constricted, sinus linear ; semicells semi-elliptic,
or subpyramidate, sides convex (rarely faintly concave
in the middle), apex a little flattened and slightly
thickened. Vertical view trigonal (or rarely tetra-
gonal), with broadly rounded angles and very faintly
refuse sides. Cell-wall punctate.
Zygospore unknown.
Length 64-142 p\ breadth 39-62 /i; breadth of
isthmus 14-34 /x.
England. — Blubberhouses,W. Yorks (W. B. Turner).
New Forest, Hants !
Scotland. — Ben Chiurn, Perth !
Geogr. Distribution.—Umted States. Guiana (var.).
Brazil.
A number of somewhat varied forms have been figured by
Borgesen as examples of this species. It is possible that all
the records of St. Cosmarioides refer to trigonal and tetragonal
forms of species of Cosmarium akin to C. pyramidatum and
G. pseudopyrarhidatum, but further investigations are neces-
sary to decide this point. St. Cosmarioides is one of those
connecting-links between the genera Cosmarium and Stau-
rastrum, and without doubt originated in the former genus.
In parts of the American continent it appears to have become
well established.
24. Staurastrum tortum (Lagerh. & Nordst.) nob.
(PI. CXXV, fig. 9.)
Cosmarium tortum Lagerh. & Nordst. in "VVittr., Nordst., & Lagerh. Alg.
Exsic. 1903, no. I486 ; fasc. 35, p. 16, f. 1-8.
Cells very small, a little longer than broad, con-
spicuously twisted at the isthmus, slightly constricted,
VOL. iv. 11
162 BRITISH DESMIDIACEjE.
sinus scarcely evident; semicells obtrapeziform, with
the sides slightly convex, apex truncate or sometimes
widely concave, apical angles obtuse and almost
imperceptibly produced. Side view of semicell semi-
elliptic. Vertical view elliptic, with the semicells not
in the same vertical plane. Cell-wall smooth.
Zygospore unknown.
Length 16-20 /a; breadth 14-17 /x ; breadth of
isthmus 10-11 /x; thickness 10*5 /a.
Wales. — In boggy pools, Glyder Fach, Carnar-
vonshire !
Geogr. Distribution. — Sweden.
Wh think this minute Desmid is better regarded as a
Staurastrum than as a Cosmarium although it is obviously one
of those peculiar species which connect the two genera. A
marked twisting- of the cell at the isthmus is a feature much
more often met with in Staurastrum than in Cosmarium.
An Australian form of this species observed abundantly in
the plankton of the Yan Yean Reservoir, Victoria, was trigonal
in vertical view. The occurrence of this ti'igonal form (forma
trigona G. S. West in ' Journ. Bot,' xliii, 1905, p. 253; fAlg.
Yan Yean/ 1909, p. 60, t. 5, f . 3, 4) adds weight to the sug-
gestion that the species is best placed under the genus
Staurastrum. It has not been seen in the British Islands,
but we give a fio-ure of it for comparison with the typical
elliptic form (PI. CXXV, fig. 10).
25. Staurastrum subpygmseum West.
(PI. CXXV, figs. 13-16.)
Staurastrum subpygmseum West, Alg. W. Ireland, 1892, p. ITS, t. 23, f. 8 ;
W. & G. S. West, New Brit. Freshw. Alg. 1894, p. 11, t, 2, f. 43 forma
glabra] ; Alg. S. England, 1897, p 494 ; Further Contrib. Freshw.
Plankton Scott. Lochs, 1905, p. 486 ; Comp. Study Plankton Irish
Lakes, 1906, p. SO ; Brit Freshw. Phytoplankton, etc., 19U9, p. 183.
Cells of medium size, about as long as broad, deeply
constricted, sinus subrectangular with an acuminate
extremity ; semicells very widely cuneate, lateral
margins and apex convex, each lateral angle produced
into a hollow mantilla. Vertical view triangular, with
convex sides and mamillate angles. Cell-wall punctate
(or rarely smooth).
STAURASTRUM. 163
Zygospore unknown.
Length 42-53 fi; breadth 39*5-52/1,; breadth of
isthmus 16-22'5 [x.
England.— Borrowdale, Cumberland ! Thursley Com-
mon, Surrey !
Scotland. — Plankton of Loch Luichart, Ross !
Plankton of Loch Fadaghoda, Lewis, Outer Hebrides !
Ireland. — Lough Aunierin, and plankton of small
lakes between Clifden and Roundstone, Gralway !
St. subpygmaeum is a well-marked specieswith an unfortunate
name, as it bears no relationship to "St. 'pygmsewm." We
have never seen it in great abundance, although it has been
frequent in some of the plankton-collections. It is a stout
Staurastrum, its general convexity and mamillate angles
giving it at once a distinctive character. The cell-wall is
usually distinctly punctate, but in some individuals the
punctulations are so faint as almost to escape detection, and
in a few cases the cell-wall has appeared to be quite smooth.
To the latter forms we gave the name of " forma glabra,"
Some specimens of this species develop a wide gelatinous
integument which may reach a diameter of 75 /x.
Var. subangulatum var. nor. (PI, CXXIV, fig. 1.)
Cells somewhat smaller than in the type, and more
deeply constricted ; semicells subrhomboid-elliptic,
angles less produced and thicker.
Length 41 fx; breadth -II /x; breadth of isthmus 9'5 /x.
Scotland. — Loch Luichart, Ross !
26. Staurastrum corniculatum Lund.
(PI. CXXV, figs. 17, 18.)
Staurastrum corniculatum Lund. Desm. Suec. 1871, p. 57, t. 3, f. 23;
De Toni, Syll. Alg. 1889, p. 1150 ; Roy & Biss. Scott. Desm. 1893, p. 1 80 ;
W. & G. S. West, Alg. S. England, 1897, p. 493 ; G. S. West, Alg. Yan
Yean, 1909, pp. 15, 27.
Cells rather under medium size, lj-li times longer
than broad, slightly constricted, sinus a small obtuse
notch ; semicells widely subcimeate, gradually widened
from a broad base, sides very slightly convex (almost
straight), apex straight, superior angles obliquely and
164 BRITISH DESMIDJACEjE.
upwardly produced, obtuse. Vertical view triangular,
with straight sides, angles obtusely rounded, sometimes
a little produced. Cell-wall smooth.
Zygospore unknown.
Length 29-42 /x; breadth 28-33 ^ ; breadth of
isthmus 12-17 /x.
England. — New Forest, Hants !
Scotland. — Bottomend and Heuo-hhead near Abovne,
Aberdeen (Roy 8f Bis-set t).
Geogr. Distribution. — Sweden. Servia. Australia.
New Zealand (var.). United States.
In 1896 we described and fissured what we tlien regarded
as the zygospore of St. comiculatum (vide W. & (t. S. West,
'New and Int. Freshw. Alg.' 1896, p. 157, t. 4, f. 37; ' Alg.
S. England/ 1897, p. 493). Subsequent investigation showed
the zygospore to belong to St. trachytithophorum, a species of
whose existence at that time we were unaware.
St. comiculatum is a very rare Desmid, but the following
variety, although rare, appears to be widely distributed.
Var. spinigerum West, (PL CXXV, figs. 19-22.)
St. comiculatum var. spinigerum West, Alo\ W. Ireland, 1892, p. 171, t. 22,
f. 12 ; W. & G. S. West, Alg. N. Ireland, 1902, p. 45, t. 2, f . 22 [forma
minor] ; CI. S. West, Alg. Yan Yean, 1909, pp. 15, 27.
Cells smaller, sometimes proportionately a little
longer, angles of semicells produced to a variable
degree and each furnished with a minute spine.
Length (without spines) 21-28 fx ; breadth 15-25 /x ;
breadth of isthmus 9'5-11/5/x; length of spines 1*5-
l-7/i.
Scotland. — Ehiconich, Sutherland ! Harris, Outer
Hebrides !
Iceland. — Lough Anna, Donegal (forma minor) !
Lakes between Clifden and Roundstone, Galwav !
Geogr. Distribution . — Australia.
Another variety of St. comiculatum described by Nordstedt
from New Zealand as "var. variabile " (cf. Xordst. ' Freshw.
Alg-. N. Zeal/ 1888, p. 39, t. 4, f. 17), sometimes possesses a
minute spine at one or more of the angles, which are also
more acute.
STAJJIiASTEOM. 105
Section D.
Cells furnished with small granules, generally
covering the whole cell-wall, and regularly or irregu-
larly disposed.
* Granules few and restricted to the angles which are produced
(submamillate).
27. St. trachytithophorum.
* * Granules more or less evenly distributed all over the cells.
t Semicells pyramidate-truncate.
28. St. botrophilum.
ft Semicells elliptic with broadly rounded angles.
% Sinus open. 29. St. turgescens.
X+ Sinus closed and linear ; semicells elliptic-pyra-
midate.
30. St. Donardense.
ttt Semicells oblong-elliptic, angles more or less produced
and often subtruncate, apex flattened.
31. St. alternants.
32. St. dilatatu hi.
33. St. disputatv in .
34. St. striolatum.
35. St. rugulosum.
tttt Semicells angularly elliptic (often rhomboid-elliptic),
with a strongly convex apex.
X Angles rounded or broadly rounded, destitute of a
mucro.
36. St. punctulatum.
37. St. dispar.
38. St. pilosellum.
XX Angles slightly rounded, furnished with a mucro.
39. St. granulosa m.
40. St. paxilliferum.
ttttt Semicells angularly rotund (subcircular).
41. St. inflatum.
27. Staurastrum trachytithophorum W. & Of. S. West.
(PL CXXVI, figs. 1, 2.)
Staurastrum trachytithophorum W. & G. S. West, Alg. S. England, 1897,
p. 493, t. 6, f. 22.
Cells small, about as long as broad, deeply con-
stricted, sinus open and subrectangnlar, with an
acuminate extremity ; semicells very widely cuneate,
166 BRITISH DESMIDIACEiE.
lateral margins slightly convex, apex strongly convex,
lateral angles upwardly turned and markedly mamil-
late, each mamilla with two ill-defined rings of minute
granules, few granules in each ring. Vertical view
triangular, sides very faintly convex, angles slightly
produced and submamillate, with two rings of minute
granules.
Zygospore globose, furnished with long, slender
spines, the apices of which are deeply 2-1-furcate,
with the divisions widely spreading.
Length 30-34 //,; breadth 29-32'5/x; breadth of
isthmus 10-5-11-5/x; diam. zygosp. without spines
31 /x, with spines 6S /x ; length of spines 15-19 fx.
England. — -Thursley Common, Surrey (with zygo-
spore) !
Only one zygospore of this species lias been observed and
it was at first referred to St. corniculatum Lund. (cf. W. &
G. S. West, ' New and Int. Freshw. Alg.' 1896, p. 157, t, 4,
f. 37). At that time the existence of St. trachytithophorum
was not known, and we failed to notice the granules on the
mamillate angles of the semicells still attached to the zygo-
spore. The discovery of vegetative cells of St. trachytitho-
phorum led to the re-examination of the supposed zygospore
of St. corniculatum, when it was at once seen that old
semicells did not belong to that species but were those of
St. trachytithophorum.
28. Staurastrum botrophilum Wolle.
(PI. CXXVI, fig. 4.)
Staurastrum botrophilum Wolle in Bull. Torr. Bot. Club, 1881, p. 2, t. 6,
f. 13 ; Wolle, Desm. U. S. 1884, p. 131, t. 42, f. 11, 12 figures poor ;
fig. 13 ?] ; De Toni, Syll. Alg. 1889, p. 1170 ; Roy & Biss. Scott. Desm.
1893, p. 18 (sep.) ; W. & G. S. West, Some N. Amer. Desm. 1896, p. 261 ;
Cushman in Rhodora, vii, 1905, p. 262.
Cells of medium size, 1-J— 1£ times as long as broad,
very deeply constricted, sinus narrowly linear with a
slightly dilated extremity ; semicells pyramidate-trun-
cate, angles a little rounded, sides subconvex^ apex
truncate and straight. Vertical view triangular, sides
faintly refuse in the middle, angles acutely rounded
STAU HAST BUM. 167
Cell-wall granulate, granules arranged in concentric
series around the angles, in the middle of the apex,
slightly reduced in size.
Zygospore unknown.
Length 46-50 /x; breadth 34-40'5/a; breadth of
isthmus 9—11 /x.
Scotland.— At 3500 ft. on Cairngorm, Inverness
(Boy Sf Bissett).
Grogr. Distribution. — United States. Macedonia (?).
St. botrophilum is a very characteristic species, very rare
in the British Islands, but more frequently observed in the
United States. The figure we give (PI. CXXVI, fig. 4) is a
drawing made from one of Wolle's original specimens which
that author sent to us some years ago.
20. Staurastrum turgescens De Not.
(PL CXXVI, figs. 5, 6.)
Staurastrum turgescens De Not. Desm. Ital 1867, p. 51, t. 4, f. 43 j Arch.
in Quart. Journ. Mier. Sci. 1878, p. 105 ; Cooke, Brit. Desm. 1887,
p. 189, t. 66, f. 4; De Toni, Syll. Alg. 1889, p. 1189; West, Alg. N.
Wales, 1890, p. 294 ; Alg. W. Ireland, 1892, p. 178 ; Alg. Engl Lake
Distr. 1892, p. 731 ; P Schinidle, Beitr. Algenfl. Schwarzwald. u.
Rheineb. 1893, p. 109, t. 5, f. 28 ; Boy & Biss. Scott. Desm. 1893, p. 26
fsep.) ; Nordst. Index Desm. 1896, p. 263 ; W. & G. S. West, Alg. S.
England, 1897, p. 494; Alga-fl. Yorks. 1901, p. 102; Alg. N. Ireland,
1902, p. 50 ; G. S. West, West Indian Freshw. Alg. 1904, p. 286 ; Alg.
Third Tanganyika Expedit. 1907, p. 125 ; Hustedt, Desm. et Bacill. aus
Tirol, 1911, p. 337.
St. pwrictulatum Breb. var. turgescens (De Not.) Rabenh. Flor. Europ. Alg.
Ill, 1868, p. 208.
St. punctulatum Breb. var. subrugulosum Racib. Nonn. Desm. Polon. 1885,
p. 86, t. 12, f. 13.
Cells rather small, a little longer than broad, deeply
constricted, sinus a little open and acute-angled ; semi-
cells elliptic or elliptic-oblong. Vertical view triangular
(very rarely quadrangular), sides concave, angles
broadly rounded. Cell-wall finely granulate, granules
fairly dense but without definite disposition.
Zygospore compressed and smooth, circular in the
broad view with 9-12 marginal undulations, in the
narrow view oblong-elliptic.
Length 28-38-5 fx; breadth 25-32'5^; breadth of
isthmus 10-12 /x.
H)8 BRITISH DESMIDIACE^I
England. — Buttermere, and Blea Tarn in Borrow-
dale, Cumberland ! Near Ambleside, Westmoreland !
Crimsworth Dean, W. Yorks ! Wimbledon Common,
Surrey !
Wales. — Bog above Capel Ourig Lakes, Llyn
(xwynant, Yr Orsedd, and Y Foel Fras, Carnarvon-
shire ! Ffestiniog, Merioneth !
Scotland. — Ross, Inverness, Aberdeen, Kincardine,
Forfar, Perth, and Wigtown {Roy $f Bissett). Caith-
ness !
Ireland. — Gortahork, Donegal ! Cloonee Longh,
Kerry ! Dublin and Wicklow {Archer). Slieve Donard,
Down (up to 2000 ft.) !
Geogr. Distribution. — Germany. Austria (Tyrol).
Italy. Bornholm. Poland. Central Africa. West
Indies.
St. turgescens is a somewhat uncommon species easily dis-
tinguished by the elliptic or elliptic-oblong semicells and the
broadly-rounded angles. The granulation is dense, but the
granules have no definite arrangement. It is probably most
nearly related to St. alternans.
The chloroplasts, according to Archer, are axile, with a
number of irregular, divergent lobes somewhat like those
which are found in the genus Cylindrocystis.
Archer found the zygospore of this species in Ireland
(Consult ' Q. J. Micr. Sci.' xviii, new series, 1878, pp. 105,
106). It is very like those of St. dilatatum and St. striolatnm.
He describes it as follows: — "circular, compressed (thus
shaped like a round cushion); in the broad view the margin
is undulate, undulations nine to twelve, smooth ; in the
narrow (edp-e) view the zygospore is oblong-elliptic, sides
parallel and straight for a notable distance at the middle,
then gradually merging into the broadly-rounded extremities,
margin smooth; contents at maturity passing into a bright
brownish-yellow colour. An inspection of a zygospore in an
oblique position, or, better still, of an empty membrane,
showed that the undulations at the circumference of the
broad aspect were carried onwards over the front surface,
and that the elevations converged towards the centre, and at
the same time diminished inwards, so as to disappear ere they
reached the centre, where the surface appeared flat."
The smallest recorded form of St. turgescens is from pools
STAURASTRUM. 169
near the shore of Lake Nyasa in Central Africa (Consult
G. S. West, ' Alg. Third Tanganyika Expedit.' 1907, p. 125) ;
this was named " forma minor" ,: length 28 fi ; breadth 25 fl ■
breadth of isthmus 10 /*.
Var. arcticum \Ville. (PI. CXXVII, fig. 24.)
St. turgescens var. arcticum Wille. Ferskv Alg. Nov. Semlj. 1879, p. 51,
t. 13, f. 57 ; W. & G. S. West, Alga-fl. Yorks. 1901, p. J 02.
Cells proportionately narrower, sinus a little more
open ; semicells very broadly elliptic (almost rotund-
elliptic) ; sides of vertical view convex.
Length 45 ju, ; breadth 30 jx ; breadth of isthmus
14 [x.
England. — Ogden Clough, W. Yorks!
Geogr. Distribution. — Nova Zembla.
30. Staurastrum Donardense W. & G. S. West.
(PI. CXXVI, fig. 7.)
Staurastrum Donardense W. & Gr. S. West, Alg. N. Ireland, 1902, p. 50,
t. 2, f. 33.
Cells small, a little longer than broad, deeply con-
stricted, sinus narrowly linear with a faintly dilated
extremity ; semicells elliptic-semicircular, basal angles
broadly rounded, apex subtruncate in the middle.
Vertical view triangular, angles broadly rounded, sides
straight or very slightly concave. Cell-wall very
minutely granulate, granules arranged in indistinct
rings around the basal angles.
Zygospore unknown.
Length 25*5-27 /x ; breadth 21-23 /x; breadth of
isthmus 6* 5-7" 5 jx.
Ireland. — Slieve Donard (abundant at 1800 ft.) and
Slievecommedagh (at 2000 ft.), Down !
This species occurred abundantly amongst numerous ex-
amples of St. turgescens in boggy pools on granitic rocks.
It should be compared with St. smaragdinum Turn.
(•Freshw. Alg. of E. India/ 1893, p. 103, t, 13, f. 14) from
which it differs in its more rounded semicells with flatter
apices, its coarser granulation, its wider isthmus, and in the
170 BRITISH DESMIDIACEA.
more rounded anyles and straighter sides of the vertical
view. It can also be compared with St. puncbulatum var.
muricatiforme Schraidle ( = St. miiricatiforme Schmidle, 'Beitr.
alp. Alg./ 1896, p. 162, t, 16, f. 14, 15), from which it is
distinguished by its smaller size, its deeper constriction and
much narrower sinus, its more compressed and flattened
semicells, and by the rounder angles and straighter sides of
the vertical view.
31. Staurastrum alternans Breb.
(PL CXXVI, figs. 8, 9.)
Staurastrum tricorne Balls, in Ann. Mag-. Nat. Hist. 1845, p. 155, t. 11,
f. 2 [not St. tricorne (Breb.) Menegh.].
St. alternans Breb. in Kalfs' Brit. Desni. 1848, p. 132, t. 21, f. 7; Arch,
in Pritch. Infus. 1861, p. 741, t. 2, f. 16, 17 ; Delp. Desm. subalp. 1877,
p. 47, t. 1 1, f . 39-42 ; Wille, Ferskv. Alg. Nov. Semlj. 1879, p. 53 ;
? Wolle, Desm. U. S. 188 4-, p. 128, t. 41, I'. 26-28 ; Cooke, Brit. Desm.
1887, p. 162, t. 54, f. 7 rfigures very poorj ; Hansg. Prodr. Algenfl.
Bohm. 1888, p. 254; Boldt, Desm. Gronland, 1888, p. 37; DeToni.Syll.
Alo-. 1889, p. 1193 ; West, Alg. N. Wales, 1890, p. 294; Alg. W. Ireland,
1892, p. 180; Alg. Engl. Lake Distr. 1892, p. 732; Liitkem. Desm.
Attersees, 1893, p. 567 ; Roy & Biss. Scott. Desm. 1893, p. 16 (sep.) ;
? Turn. Freshw. Alg. E. India, 1893, p. 105, t. 16, f. 6 ; Nordst. Index
Desm. 1896, p. 41 ; W. & G. S. West, Alg. S. England, 1897, p. 494 ;
Schmidle, Lappmark Siisswasseralgen, 1898, p. 58: W. & G. S. West,
Alga-fl. Vorks. 1901, p. 101; Borg. Alg. Faroes, 1901, p. 230; W. A
G. S. West, Alg. N. Ireland, 1902, p. 51 ; Hirn, Desm. Finland, 1903,
p. 19; Larsen, Freshw. Alg. E. Gieenland, 1904, p. 95; W. & G. S.
West, Freshw. Alg. Orkneys and Shetlands, 1905, p. 25; Borge,
Beitraire Alg. Sehweden, 19*06, p. 46 ; G. S. West, Alg. Third Tan-
ganyika Expedit. 1907, p. 125 ; Alg. Yan Yean, 1909, p. 28 ; W. &
G. S. West, Brit. Freshw. Phytoplankton, etc., 1909, p. 181.
Phycastrum t rilobatum Kiitz. Spec. Alg. 1849, p. 179.
P. Balfsii Nag. Gatt. einzell. Alg. 1849, p. 125.
Didymidium (Staurastrum) punctulat ion A minus y alternans Reinsch,
Algenfl. Frank. 1867, p. 160.
St. dilatatum b. alternans Rabenh. Flor. Europ. Aly. Ill, 1868, p. 207.
Cells small, as long as broad, twisted at the isthmus
through 60°, deeply constricted, sinus open and
acute-angled ; semicells rather narrowly oblong-
elliptic, lateral angles rounded, apex flattened in the
middle (but convex if the cell is very slightly oblique).
Vertical view triangular, angles of one semicell alter-
nating with those of the other, sides concave, angles
rounded. Cell- wall finely granulate, granules arranged
in concentric rings around the angles, but scattered
and somewhat reduced in the middle of the apex.
STAURASTKUM. 171
Zygospore globose, and "furnished with spines
forked at the apex" (Ralfs).
Length 22-33 li ; breadth 21-31 ll ; breadth of
isthmus 7'5-9-5 li.
Exglaxd. — Cumberland ! Westmoreland ! (Rolfs).
W., X.,andE. Yorks ! Leicestershire (Roy). Essex!
Oxfordshire ! Gloucestershire ! Surrey (zygospores
from Thursley Common) ! Sussex ! Kent ! Hants !
Devon ! Cornwall !
Walks. — Llyn Padarn !, Moelfre !, Capel Curig !
{Coolie Sf Wills), and Bettwys-y-Coed (Roy), Carnar-
vonshire. Llyn Coron, Anglesey ! Dolgelly, Merio-
neth (Rolfs). "
Scotland. — Sutherland !, Ross, Inverness, Aberdeen,
Kincardine, Forfar, Perth !, Fife (Roy Sf Bissett).
Cumbrae, Ayr ! Lewis, Outer Hebrides ! Plankton of
Loch Asta, Shetlands !
Irelaxd. — Donegal ! Mayo ! Galway ! Kerry !
Dublin and Wicklow (Archer). Londonderry!
Geogr. Distribution. — France. Germany. Austria
and Galicia. Servia. Italy. Norway (and Finmark).
Sweden. Denmark. Bornholm. Finland. N. Russia.
Faeroes. Iceland. Nova Zembla. Greenland. India.
Siam. Australia. New Zealand. Central Africa.
United States.
Staurastrum alternans is a characteristic species with a
world-wide distribution. It is found in all parts of the
British Islands, but is never common. When seen in exact
front view the semicells are narrowly elliptic-oblong, although
the slightest tilting to an oblicpie position at once causes a
change in their form. This fact alone is sufficient to separate
St. alternans from St. punctulatum, although there are other
important differences, such as the proportionately shorter
cells, less open sinus, more rounded angles, and more retuse
sides in the vertical view.
Ralfs' figure of St. alternans is very poor, scarcely
differing in any respect from his figure of St. dilatatum except
that it is triangular in vertical view. We have given a copy
of this figure (PI. CXXVI, fig. 9), although it conveys little
idea of the characters of the species.
The granules in this species are only definitely arranged
172 BRITISH DESMIDIACEiE. .
around the angles, those at the apices having no regular dis-
position. The alternation of the angles of one semicell with
those of the other is of no specific importance, notwithstand-
ing the fact that the specific name was based upon this
character. Such alternation is common in Staurastra of this
kind, and is frequently observed in St. punctulatum and St.
(Yd (datum.
The zygospore has been described by Ralfs, but not
figured. We are not sure, however, that the zygospore
described by Ralfs belonged to St. altemans, as for many
years Ralfs was greatly confused between this species and St.
hexacerum (= St. tricome Ralfs). We have ourselves once
observed a zygospore (from Thursley Common, Surrey), but
the specimen was lost in attempting to permanently mount it.
Unfortunately this happened before a drawing had been made.
We regard St. altemans var. coronatum Schmidle (1895)
as a variety of St. 'punctulatum Breb.
Var. pulchrum Wille. (PL CXXVII, fig. 16.)
St. altemans var. pulchrum Wille, Perskv. Alg. Nov. Semlj. 1879, p. 53
t. 13, f. 66; Boldt, Siber. Chlorophy. 1885, p. 115; Desm. Oronland,
1888, p. 37 ; Eoy & Biss. Scott. Desm. 1894, p. 16 (sep.)
Cells proportionately a little longer, with an obtuse
sinus ; lower lateral margins of semicells slightly eon-
cave, apex less convex.
Leno-th 28-8-36 u; breadth 22'8-33*6/a; breadth of
isthmus 7'2-12 /x.
Scotland. — Glen Garry near Dalnaeardoch, Perth !
Geogr. Distribution. — N ova Zembla. Greenland.
Siberia.
This variety approaches St. punctulatum, but differs in the
sinus, the form of the semicells, and the blunter angles
(especially in the vertical view).
32. Staurastrum dilatatum Ehrenb.
(PL CXXVI, figs. lO-lo.)
Staurastrum dilatatum Ehrenb. Infus. 1838, p. 143, t. 10, f xiii [descrip-
tion and figures very poor] ; Ralfs in Ann. Mag. Nat, Hist, xv, 1845,
p 156, t, 11, f. 5 ; Brit. Desm. 1848, p. 133, t, 21, fV8 [figures not good] ;
Lrch in Pritch. Infus. 1801. p. 741; Rabenh. Flor. Europ. Alg. Ill,
1868 p. 207 ; Kirchn. Alg. Schles. 1878, p. 165; ? ? Wolle, Desm. U. S.
1884, p. 128, t. 52, f. 32, 33 ; Nordst. Desm. Grimland, 1885, p. 10 ; Cooke,
Brit.' Desm. 1887, p. 162, t. 54, f. 8 [figures bad ; Hansg. Prodr. Algenfl.
STAUUASTJJTJM. 173
Bohm. 1888, p. 212; De Toni, Syll. Alg. 1889, p. 1193; West, Alg. N.
Wales, 1890, p. 294; Gutw. Flor. Glon. Okolic Lwowa, 1891, p. 66;
West. Alg. W. Ireland, 1892, p. 180; Alg. Engl. Lake Distr. 1892,
p. 732 ; Liitkem. Desm. Attersees, 1893, p. 567 ; Eoy & Biss. Scott,
Desm. 1893, p. 237 ; 1894, t. 4, f . 4 ; Nordst. Index Desm. 1896, p. 109 ;
W. & G. S. West, Welw. Afric. Freshw. Alg. 1897, p. 181 ; Alg. S.
England, 1897, p. 494 ; Sehmidle, Lappmark Siisswasseralgen, 1898,
p. 58; Liitkem. Desm. Millstattersees, 1900, p. 2L (sep.) ; W. & G. S.
West, Alga-fl. Yorks. 1901, p. 101 ; Alg. N. Ireland, 1902, p. 51 ; Freshw.
Alg. Orkneys and Shetlands, 1905, p. 25 ; Borge, Beitrage Alg.
Schweden, 1906, p. 46 ; Larsen, Ferskvandsalg. Vest-Gronl. 1907
p. 349 ; W. & G. S. West, Freshw. Alg. Burma, 1907, p. 214.
Goniocystis (Staurastrum) dilatata Hass. Brit. Freshw. Alo-. 1845, p 353
t. 85, i. 5.
Phycastrum dilatatum Kutz. Phycol. germ. 1845, p. 138.
Staurastrum dilatatum var. obtusilobum De Not. Desm. Ital. 1867, p. 53, t. 4,
f. 47 ; Nordst. Freshw. Alg. N. Zeal. 1888, p. 41, t. 4, f . 19; West, Alg!
W. Ireland, 1892, p. 180; Alg. S. England, 1897, p. 494 ; Lutkem. Desm.
Millstattersees, lbOO, p. 21 (sep.) ; W. & G. S. West, Alga-fl. Yorks.
1901, p. 101 ; Alg. N. Ireland, 1902, p. 51 ; Freshw. Alg. Ceylon, 1902,
p. 177 ; Freshw. Alg. Orkneys and Shetlands, 1905, p. 25 ; Further
Contrib. Plankton Scott. Lochs, 1905, p. 487 ; Comp. Study Plankton
Irish Lakes, 1906, p. 86; Teodoresco, Mater, flor alg. Eouman. 1907,
p. 185 ; G. S. West, Alg. Yan Yean, 1909, pp. 28, 38 ; W. & G. S. West,
Brit. Freshw. Phytoplankton, etc., 1909, p. 182.
Cells small, about as long as broad or sometimes a
little longer, deeply constricted, sinus widely open and
minutely acuminate at the extremity ; semicells elliptic-
subfusiform, dorsal margin convex, ventral margin
greatly inflated in the median part, so that the greater
portion of the semicell is raised up on a smaller ventral
piece, lateral angles rounded or rounded-truncate.
Vertical view 3-5 (usually 4)-angular, angles of one
semicell often alternating with those of the other, sides
deeply concave, angles rounded or rounded-truncate.
Cell-wall finelv granulate, granules arranged in con-
centric rino-s around the angles, and in regular series
between the angles, extreme apex smooth or with a
few minute punctulations.
Zygospore (?) " somewhat barrel-shaped, with round
ends, and has numerous raised bands, passing longi-
tudinally round it, giving the end view an undulated
appearance " (Boy Sf Buse.it).
Length 21-46 fx ; breadth 22-40/z; breadth of
isthmus 7"5-1o/a; diam. zygosp. 48 fi.
England. — Cumberland! Westmoreland, up to
400 ft. on Helvellyn ! (Ralfs). Lancashire! W., N.s
o
174 BRITISH DESMIDIACE^.
and E. Yorks ! Bucks ! Oxfordshire ! Warwickshire
(Wills). Gloucestershire (Rolfs). Surrey ! Sussex
(Ealfs). Kent (Rolfs). Hants I (Roy). Devon! Corn-
wall ! '
Walks. — Capel Curig !, Llyn Padarn !, Llyn Idwal !,
Llyn Gwynant !, Llyn-y-cwm-ffynon !, near Dolbadarn
Castle !, Bettwys-y-coed (Roy), Pen-y-gwryd (Roy),
and Glyder Fawr (Roy), Carnarvonshire.
Scotland. — General : zygospore near Dinnet, Aber-
deen (Roy Sf Bissett). Sutherland! Inverness! Lewis
and Benbecula, Outer Hebrides ! Scottish plankton
generally ! Plankton of Loch Beosetter in Bressay,
Shetlands !
Ireland. — Donegal ! Mayo (including Achill and
Clare Islands) ! Several lakes in Galway ! Several
lakes in Kerry (also in plankton) ! Dublin and
Wicklow (Archer). Louth ! Down ! Londonderry !
Geogr. Distribution. — France. Germany. Austria
and Galicia. Hungary. Eoumania. Servia. Mace-
donia. Italv. Portugal. Norwav. Sweden. Denmark.
Central and S. Russia. Greenland. Japan. India.
Ceylon. Australia. New Zealand. Madagascar.
Central Africa. Azores. United States. Brazil.
Bolivia. Paraguay. Argentina.
Staurastrum dilatatum is most frequent in bogs and at the
boggy margins of lakes, and in some of the western areas of
the British Islands it is commonly found in association with
Cosmarwim conspersum var. latum, C. tetraophthalmum, C.
reniforme, C. subundulatum, Staurastrum teliferum, and other
Desmids.
Ealfs' figures are poor and do not give an adequate idea of
the characters of the species. We find the semicells somewhat
variable in outward form. They may be regularly elliptic-
fusiform, but more often there is a more or less distinct
ventral inflation. The regularity of the granulation, especi-
ally as seen in the vertical view, is one of the principal
characters of the species. The angles were described and
figured by Halt's as truncate, in consequence of which De
Notaris (1867) founded for the form with rounded ang-les
the var. obhisilobum. This form was admirably figured by
Nordstedt in 1888, and since that date has been repeatedly
STAURA STRUM. 1
i O
recorded by many authors, ourselves included, as a distinct
variety. Careful examination of large numbers of specimens
has convinced us, however, that the angles of this species are
never more than subtruncate, and that every state exists
between those which are subtruncate and those which are
entirely rounded. We are therefore compelled to discard the
var. obtusilobum, as it is founded upon a character which can
only be regarded as slight, indefinite, and arbitrary.
The description given by Roy and Bissett of the zygo-
spore requires confirmation. From their figure (in ' Ann.
Scott Nat. Hist.' 1894, t. 4, f. 4) we should say that it is very
similar to the zygospore of the closely allied species St.
striolatum, in which case it would be compressed and not
"barrel-shaped." The outlines of the semicells as depicted
by Messrs. Roy and Bissett do not agree with those of St.
dilatation.
Cushman (in 'Bull. Torr. Bot. Club/ xxxii, 1905, p. 227,
t. 8, f. 14) has also described and figured what he considers
to be the zygospore of St. dilatatum. His description states
that it is "elliptical, covered with rounded protuberances," and
his figure, although somewhat poor, might possibly be recon-
ciled with an oblique view of a zygospore similar to that of
St. striolatum (cf. PI. CXXVII, fig. 5).
The Desmid described by Boldt (' Desm. Gronland,' 1888,
p. 37, t. 2, f. 48) under the name of " St. margaritaceum var.
truncatuin " is a variety of St. dilatatum with truncate apices,
and should be placed as St. dilatatum var. teuncatum.
Var. hibernicum nob. (PI. CXXVI, fig. 18.)
St. sinense Lutkem. var. hibernicum W. & G. S. West, Alg. X. Ireland,
1902, p. 52, t. 2, f. 34.
Cells rather small, basal portion of semicells more
pronounced ; granules very minute, disposed in series
around the angles but irregularly scattered on the rest
of the cell.
Length 24 li; breadth 21-24/x; breadth of isthmus
7 fx.
Ireland. — Lough Anna, Donegal !
This Desmid was originally described as a variety of St.
sinense, but the convex apex of the semicells, combined with
the fact that the cell is finely granulate all over, points
unmistakably to a close relationship with St. dilatatum.
176 DltlTISH DESMIDIACK .-!•:.
33. Staurastrum disputatum nov. nom.
(PL CXXVI, fig. 1(3; PL CXXIX, fig. 1.)
St. dilatatum var. insigne Racib. Desmidvja Ciastonia, 189.;, p. 388, t. 1,
f. 13 ; W. & G. S. West, Welw. Afric. Preshw. Alg. 1897. p. 181 forma
minor] ; Borge, Alg. erst. Regnell. Exped., II. Desmid. 1903, p. 1< »7,
t. 4, f. 12 [forma minor].
Cells small, a little longer than broad, moderately
constricted, sinus widely open and obtuse-angled, with
the apex minutely acuminate ; semicells widely cunei-
form from a broad base, lateral margins slightly retuse,
apex widely truncate and flat, angles slightly produced
and rounded. Vertical view quadrangular, angles
somewhat produced and rounded, sides concave. Cell-
wall granulate at the angles, but the body of the cell
(including the apices) quite smooth, granules disposed
in 4 or 5 ring's around the angles.
Zygospore unknown.
Length 35 fi; breadth 33 /a; breadth of isthmus
19^.
Ir bland. — Near Westport, Mayo ! Lough Bonn,
Gal way !
Geogr. Distribution. — W. Africa. Brazil. Argentina.
It does not seem to us quite correct to place this Desmid as
a variety of St. dilatatum. It differs from that species very
much in the form of its semicells and in its granulation. The
sinus is more widely open, the apex of the semicell is very
widely truncate and straight, and the granules are confined
to the angles, around which they are disposed in four or five
series. Under these circumstances we have established it as
a species. Neither "insigne" nor " RaciborsJcii" could be
utilized for the specific name, as both are already in use.
Borge has mentioned a " forma minor " from Brazil :
length 20-21 fi; breadth 20-21 p; breadth of isthmus 9ju.
We recorded this same small form from West Africa in 1897.
The following might also be best regarded as varieties of
this species : —
Y;ir. sinense (Liitkem.) nob. St. sinense Lutkem. Desm.
Central China, 1900, p. 124, t. 6, f. 39, 40 ; G. S. West, Alg.
Third Tanganyika Expedit. 1907, p. 125. Cells smaller, body
STAURASTEUM. 177
of semicells somewhat smaller, angles more produced and
cylindrical (almost forming- cylindrical processes), with about
four rings of minute granules. Length 1 8-20 u ; breadth
18-23/i; breadth of isthmus 7/z. (PI. CXXVI, fig. 19).
Distrib. — Central China. Central Africa.
Var. extensum (Borge) nob. St. dilatatum Ehrenb. var.
externum Borge, Beitrage Alg. Schweden, 1906, p. 46, t. 3,
f. 37. Basal portion of semicells narrower and almost
shortly cylindrical, causing the angles to appear more pro-
duced ; granules arranged in 5 or 6 rings around each angle.
Length 23-24 /t; breadth 195/z; breadth of isthmus 6-5//.
(PL CXXVI, fig. 17). Distrib.— Sweden.
We have given figures of both the above varieties in order
to render clearer the characters of St. disputatum. The
broad, fiat apex, and the restriction of the granules to the
circles around the angles, are its distinctive features.
St. moniliferum Playfair (' New or Less-known Desm. N. S.
Wales/ 1907, p. 188, t. 5, f. 7) and St. campanulatum Playfair
(I.e. p. 189, t. 5, f. 8) may both be forms of this Desmid but
at present they are insufficiently known.
34. Staurastrum striolatum (Nag.) Arch.
(PL CXXVII, figs. 1-5.)
Phycastritm (Amblij actinium) striolatum Nag. Gatt. einzell. Alg-. 1849,
p. 126, t. 8 A, fig. 3.
Staurastrum striolatum (Nag.) Arch, in Pritch. Infus. 1861, p. 740 ;
Rabenh. Flor. Europ. Alg. Ill, 1868, p. 201 ; Nordst. Desm. Brasil.
1870, p. 225, t. 4, f. 45 ; Wittr. Gotl. 01. sotv. Alg. 1872, p. 52 ; Kirchn.
Alg. Settles. 1878, p. 164; ? Wolle, Desm. U. S. 1884, p. 126, t. 51, f. 27,
28; Lagerh. Bidr. Amerik. Desm.-fl. 1885, p. 246; Cooke, Brit. Desm.
1887, p. 158, t. 54, f. 4 [figures poor] ; De Toni, Syll. Alg. 1889, p. 1188 ;
West, Alg. W. Ireland, 1892, p. 178 ; Nordst. Index Desm. 1896, p. 243 ;
Cushman, in Bull. Torr. Bot. Club, 1905, p. 552 ; in Rhodora, 1905,
p. 264 ; Borge, Beitnige Alg. Schweden, 1906, p. 43 ; G. S. West, Alg.
Yan Yean, 1909, pp. 38, 69, t. 6, f . 10-12...
St. striolatum var. celandicum Wittr. Gotl. 01. sotv. Alg. 1872, p. 52.
St. striolatum forma brrrsiliensis Turn Freshw. Alg. E. India, 1893, p. 109, t.
13, f . 15 [figures poor] ; W. & G. S. West, Some Desm. U. S. 1898, p. 313.
St. dilatatum var. indicum Turn. 1. c. t. 13, f. 17 [figure poor].
Cells small, about as long as broad; deeply con-
stricted, sinus widely open, rather obtuse at the
extremity ; semicells somewhat oblong-elliptic, dorsal
margin (apex) straight or slightly retuse, ventral
margin convex and inflated in the middle, lateral
angles rounded or subtruncate. Vertical view trian-
gular, sides concave, angles rounded or subtruncate.
vol. iv. 12
178 BRITISH DESMIDIACEjE.
Cell-wall finely granulate, granules arranged in rings
around the angles, although sometimes a little scattered
on the body of the semicell, granules at the end of
each angle often a little larger than the rest.
Zygospore compressed, having a circular outline in
the front view, with 10-12 marginal undulations ; side
view oblong.
Length 19-28 ll; breadth 18-28 [x; breadth of isthmus
6-10 fx; diam. zygosp. 35-39 jx, thickness 21-24 fx.
Wales. — Capel Curig and near Bethesda, Carnar-
vonshire !
Ireland. — Near Westport, Louisburgh, and Dugort,
Mayo ! Near Leenane, Rounclstone, and Ballynahinch,
Gal way !
Geogr. Distribution. — Germany. Galicia in Austria.
Hungary. Norway. Sweden. India. Australia.
New Zealand. Azores. United States. Brazil.
Patagonia.
St. striolatum differs from St. dilatatum in the outward
form of its semicells and its somewhat different granulation.
As in St. disputatum the semicells have a flat apex, but the
granulation extends over the whole body of the Staurastrum.
We can see no valid reason for the separation of Wittrock's
var. oelandicum, the characters of which were based upon the
zygospore. This is, however, similar in every respect to other
zygospores which must be attributed to St. striolatum.
We figure the following variety for comparison with the
more typical forms of St. striolatum : — ■
Var. divergens nob. [St. altemans var. divergens W. &
G-. S. West, Freshw. Alg. Ceylon, 1902, p. 177, t. 21, f. 18.]
Cells a little smaller, apices of semicells concave, angles very
faintly dilated (indistinctly subcapitate) and slightly divergent)
angles of one semicell alternating with those of the other.
Length 17 /n ; breadth 17-18 /.t; breadth of isthmus 5'5//.
(PL CXXV1I, fig. 6.) Distrib.— Ceylon.
35. Staurastrum rugulosum Breb.
(PI. CXNVI, fig. 3.) J
Staurastrum rugulosum Breb. in Ralis' Brit. Desm. 1848, p. 214, t. 35,
f. 19; Arch, in Pritch. Infus. 1861, p. 740 ; Rabenh. Flor. Europ. Alg.
Ill, 1868, p. 208; Kirchn. Alg. Schles. 1878, p. 164; De Toni, Syll.
STAURASTRUM. 179
Alg. 1889, p. 1170; ? Heimerl, Desm. alpin. 1891, p. 605 ; Roy & Biss.
Scott. Desm. 1893, p. 241 ; Lagerh. Chlor. Abessin. u. Kordofan, 1893,
p. ] 63 ; Schmidle, Lappmark Siisswasseralgen, 1898, p. 54 ; Gvitw. Flor.
Alg. Mont. Tatr. 1909, p. 471.
Cells small, a little broader than long, deeply con-
stricted, sinus slightly open, narrowly acute-angled ;
semicells oblong-elliptic, with a rather flattened apex.
Vertical view triangular, sides very slightly concave,
angles rounded. Cell-wall granulate, granules some-
what irregularly scattered and a little more prominent
at the anodes.
Zygospore unknown.
Length 33 fx ; breadth 36 jjl ; breadth of isthmus 13 ju.
Scotland. — Near Strathpeffer, Ross; Cairnmonearn,
Kincardine (Roy S,' Bissett).
Geogr. Distribution. — France. Germany. Sweden.
Galicia in Austria. Madagascar (forma?). Abyssinia.
We regard this species as exceedingly doubtful. The
figure in Ralfs' ' British Desmids/ of which we give a copy,
is very poor, and the original description is much too brief.
Gntwinski, Heimerl, Roy, Lagerheim, and Schmidle are the
only authors who have recorded it since its description in
1848, and Heimerl's measurements (length 38-49 ji; breadth
37-44^) are considerably larger than those obtained by
measuring RalfV original figure. Wolle's supposed figures
of this Desmid (f Desm. TJ. S.; 1884, t. 41, f. 41, 42) are too
uncertain to be of any value.
It is possible that St. rugnlosum is merely a form of St.
alternans, but the available evidence is insufficient to make
a definite statement regarding its exact position.
We have ourselves recorded what we believed to be a form
of St. rugnlosum from Madagascar (cf. W. & G. S. West, 'Alg.
Madag.' 1895, p. 74), but we are not at all certain of the
correct position of this form.
36. Staurastrum punctulatum Breb.
(PL CXXVII, figs. 8-11, 13, 14.)
Staurastrum punctulatum Breb. in Ealfs' Brit. Desm. 1848, p. 133, t. 22,
f. 1 ; Arch, in Pritch. Infus. 1861, p. 740; Rabenh. Flor. Europ. Alg.
Ill, 1868, p. 208 ; Lnnd. Desm. Suec. 1871, p. 63 ; ? Nordst. Desm.
Spetsb. 1872, p. 39 ; Norges Desm. 1873, p. 29 ; Desm. Arctose, 1875,
p. 34; Kirchn. Alg. Schles. 1878, p. 164; Gay, Monogr. loc. Conj.
Montpellier, 1884, p. 66 ; ? Wolle, Desm. U. S. 1884, p. 127, t. 41, f. 43-
45; Nordst, Desmid. Gronland, 1885, p. 10; Cooke, Brit. Desm. 1887,
180 BRITISH DESMIDIACEyE.
p. 160, t, 54, f. 6 ; Hansg. Prodr. Algenfl. Bohm. 1888, pp. 212, 25 ' ;
Boldt, Desm. Gronland, 1888, p. 34 ; De Toni, Syll. Alg. 1889, p. 1190 ;
West, Alg. N. Yorks, 1889, p. 293 ; Alg. N. Wales, 1890, p. 294 ;
Heimerl. Desm. alpin. 1891, p. 605; West, Alg. W. Ireland, 1892,
p. 179 ; Alg. Engl. Lake Distr. 1892, p. 732 ; Borge, Chlorophy. Norska
Finmark. 1892, p. 7 ; Gutw. Flor. glonow Galic. 1892, p. 134 ; Lutkem
Desm. Attersees. 1893, p. 566 ; Roy & Biss. Scott. Desm. 1894, p. 24
(sep.) ; Nordst. Index Desmid. 189fi, p. 213 ; Schmidle, Beitr. alp. Alg.
1896, p. 62 ; W. & G. S. West, Welw. Afric. Freshw. Alg. 1897, p. 181 ;
Alg. S. England, 1897, p. 494 ; Alga-fl. Yorks. 1901, p. 101 ; Borg.
Freshw. Alg. Faeroes, 1901, p. 230 ; Bohlin, Flor. Algol, d'eau donee d.
Acores, 1901, p. 61, t. 1, f . 20, 21 ; W. & G. S. West, Alg. N. Ireland,
1902, p. 50; Him, Desm. Finland, 1903, p. 22; W. & G S. West, Scott,
Freshw. Plankton, I. 1903, p. 529; Larsen, Freshw. Alg. E. Greenland,
1904, p. 99 ; W. & G. S. West, Freshw. Alg. Orkneys and Shetlands,
1905, p. 25 ; Borge, Beitrage Alg. Schweden, 1906, p. 45 ; Teodoresco,
Mater, flor. alg. Ronman. 1907, p. 184 ; Larsen, Ferskvandsalg. Vest-
Gronl. 1907, p. 352 ; W. & G. S. West, Freshw. Alg. Burma, i907, p.
214; G. S. West, Alg. Yan Yean, 1909, p 28; W. & G. S. West, Brit.
Freshw. Phytoplankton, etc., 1909, p. 183 ; Phytoplankton Engl. Lake
Distr. 1909, p. 139; Hustedt, Desm. et Bacill. aus Tirol, 1911, p. 337.
Didymidium (Staurastrtim) punctulatum Reinsch, Algenfl. Frank. 1867,
p. 159.
Staurastrum punctulatum forma contorta Schmidle, Beitr. alp. Alg. 1896,
p. 62.
Cells small, a little longer than broad, deeply con-
stricted, often twisted at the isthmus, sinus open and
acute-angled (about 70°) ; semicells subrhomboid-
elliptic, dorsal and ventral margins about equally
convex, angles somewhat acutely rounded. Vertical
view triangular (rarely 4-, and very rarely 5-angular),
angles acutely rounded, sides slightly retuse in the
middle ; angles of one semicell often partly or entirely
alternating with those of the other. Cell-wall uni-
formly granulate with flattened granules, which are in
regular series around the angles.
Zygospore globose, furnished with rather short
spines which are doubly furcate at the apex, each one
arising from a broadly mamillate base.
Length 26-405 /x ; breadth 23-36*5 fx ; breadth of
isthmus 8-16 fx ; diam. zygosp. without spines 29-38 /x,
with spines 42-58 /x.
England. — Cumberland ! Westmoreland ! Lanca-
shire ! W., N., and E. Yorks. (zygospores from
Keighley, W. Yorks) ! Leicester {Roy). Essex !
Cambridge! Warwicks ! (Wills). Worcestershire!
Staffordshire ! Middlesex ! Surrey (zygospores from
STAUEASTRUM. 181
Devil's Jumps near Frensham) ! Sussex (Rolfs).
Kent! Hants! (Boy). Devon! Cornwall (zygo-
spores from Tremethick Moor) ! (Marquand).
Wales. — Fairly general !
Scotland. — General, but rather scarce ! (Boy fy
Bissett.) Loch More, Sutherland ! Loch Doon, Ayr !
Dumfries ! Wigtown ! Plankton of Orkneys and
Shetlancls ! Rather rare in general plankton !
Ireland. — Donegal! Mayo (and Clare Island)!
Galway! Kerry! Dublin and Wicklow (Archer).
Down (up to 2000 ft.) ! Lough Neagh, Antrim !
Londonderry !
Geogr. Distribution. — France. Germany. Switzer-
land. Austria and Galicia. Hungary. Servia. Ron-
mania. Italy. Spain. Norway (and Finmark).
Sweden. Denmark. Bornholm. Finland. Poland.
Russian Lapland. N., Central, and S. Russia.
Faeroes. Iceland. Nova Zembla. Spitzbergen.
Greenland. Japan. E. India. Ceylon. Java.
Australia. New Zealand. Azores. United States.
Brazil. Argentina, Patagonia (a form).
St. punctu latum is one of the most ubiquitous species of the
genus, being almost universally distributed in bogs, marshes,
and marshy pools. Its characters are distinctive, although it
is subject to considerable variation. The cells are frequently
twisted at tlie isthmus, so that the angles of one semicell are
not vertically over those of the other, and in many individuals
the twist is fully 60°. The semicells are usually triangular in
vertical view, but tetragonal forms are 'by no means rare.
The granules are uniform in character and somewhat depressed,
having- a disposition in concentric series around the angles,
but at the apex of the semicell, and in other parts, they are
irregularly scattered. In its most typical form the semicells
of St. punctulatum are on the whole rhomboid-elliptic, with
acutely-rounded lateral angles, and the sides of the vertical
view are slightly retuse in the middle.
Some of the specimens recorded by Nordstedt from within
the arc-tic circle are larger than any British specimen we have
yet seen : length up to 52 /u ; breadth up to 48 fi.
The smallest forms we have seen were from Lewis, Outer
Hebrides; length 22 « ; breadth 18'5 fi (PL CXXVII, fig. 12).
182 BRITISH DESMIDIACEiE.
A careful consideration of the various forms of St. pintc-
tulatum and its allies has convinced us that St. Kjellmani
AVille, St. pygmseum Breb. and St. punctulatum all belong to
the same species-group. We have found it clearly impossible
to separate these Desmids as distinct species, as the inter-
mediate forms constitute a gradation through which any line
of demarcation is purely arbitrary. We have therefore placed
all the various forms under the one species St. punctulatum.
We wish it to be understood that this closer grouping of
the above " species," so often regarded as distinct, is an
expression of opinion that after twenty years' experience of
them from all parts of the world we are still unable to draw
up valid specific characters.
St. subpunctulatum Gay (' Monogr. loc. Conj. Montpellier,'
1884, p. 66, t. 2, f. 8) is most probably only a form of St.
punctulatum.
It is possible to discriminate between seven more or less
distinct British varieties of St. punctulatum.
Var. subproductum var. nov. (PL CXXVII, fig. 15.)
Staurastrum punctulatum forma G. S. West, Alga-fl. Cambr. 1899, p. 219.
Cells proportionately wider, lateral angles of semi-
cells very slightly produced ; vertical view with faintly
convex sides and almost imperceptibly produced
angles.
Length 31/x; breadth 31 p. ; breadth of isthmus
8*5 p.
England.- — Dernford Fen, Cambridgeshire !
To this variety belongs the form described by Boldt from
Greenland (cf. Boldt, 'Desmid. Gronland/ 1888, p. 35, t. 2,
f . 43) as "forma semicellulis a vertice visis area triangnlari
nuda, lateribus in medio tumidis." This form has the faintly
produced angles characteristic of var. subproductum, but in the
middle of the apex of each semicell is a triangular smooth area.
Var. Kjellmani Wille. (PL CXXVII, figs. 13, 17-19,
21, 22.)
Staurastrum Kjellmani Wille, Ferskv. Alg. Nov. Semlj. 1S79, p. 50, t. 13,
f. 50-53 [forma trigona major, forma trigona minor, and forma tetra-
gona] ; Cooke, Brit. Desni. 1887, p. 163, t. 54, f. 9 ; West, Alg. N.
Yorks. 1889, p. 293; Alg. W. Ireland, 1892, p. 177; Alg. Engl. Lake
Distr. 1892, p. 731 ; Eoy & Biss. Scott. Desm. 1894, p. 21 (sep.) ; Nordst.
Index Desm. 1896, p. 152 ; W. & G. S. West, Alga-fl. Yorks. 1901, p.
102 ; Bohlin, Flor. Algol, d'eau douce d. Acores, 1901, p. 62 j Larsen,
STAGRA STRUM. 183
Freshw. Alg. E. Greenland, 1904, p. 97; G. S. West, Treat. Brit.
Freshw. Alg. 1904, p. 139, f. 51 F ; W. & G. S. West, Freshw. Alg.
Orkneys and Shetlands, 1905, p. 25.
St. punctidatum var. Kjelhnani Wille in Dijinphna-Togtets zool.-bot.
Udbytte, 1886, p. 86 ; Boldt, Desm. Gronland, 1888, p. 35 ; De Toni,
Syll. Alg. 1889, p. 1190; Borg. Ferskv. Alg. Ostgronl. 1894, p. 26;
Schmidle, Lappmark Siisswasseralgen, 1899, p. 57 ; Borg. Freshw.
Alg. Faeroes, 1901, p. 230 ; Borge, Beitrage Alg. Schweden, 1906, p. 45 ;
Teodoresco, Mater, flor. alg. Rouman. 1907, p. 185 ; Larsen, Ferskvand-
salg. Vest.-Gronl. 1907, p. 353 ; Hustedt, Desm. et Bacill. aus Tirol,
1911, p. 337.
St. punctidatum as figured by W. & G. S. West, Notes Alg. II, 1900, p. 297,
( t. 412, f. 13 [zygosp.]
St. Bieneanum Rabenh. forma groenlandica Larsen, Freshw. Alg. E.
Greenland, 1904, p. 96.
Cells with a more open sinus (almost rectangular),
angles of semicells more rounded ; sides of vertical
view straight or slightly convex ; granulation on the
whole a little finer and denser.
Zygospore similar to that of type, but with the
spines a little stouter.
Length 30-43 p : breadth 24-3 7'5 /a; breadth of
isthmus 9-20 jx; diam. zygosp. without spines 29 fx,
with spines 42 /x.
England. — Blea Tarn in Borrowdale, Cumberland !
Near Bowness (Bissett), Helvellyn, Stickle Tarn, and
Blea Tarn, Westmoreland ! Wrynose, Lancashire !
Mickle Fell, N. Yorks ! Darenth Wood, Kent (with
zygospore) !
Wales.— Glyder Fawr (at 2700 ft.), Snowdon (at
over 3000 ft.), Carnarvonshire !
Scotland. — General on the higher mountains!
(Iio)j fy Bissett.) Up to 3500 ft. on Lochnagar,
Aberdeen ! Shetlands !
Ireland. — Lough Gruitane and Carrantuohill, Kerry !
Glengariff, Cork !
Geogr. Distribution. — Germany. Austria and Galicia.
Roumania. Norway. Sweden. Faeroes. Nova
Zembla. Spitzbergen. Greenland. Azores (var.)
In making- a comparative examination of numerous forms
from various localities we find it impossible to separate
*S7. Kjelhnani from St. 'punctidatum, and we have therefore
adopted Wille's decision of 1886 and placed it as a variety of
184 BRITISH DESMlDIACE.i:.
that species. It is essentially an alpine and arctic variety,
and often attains a larger size than the average specimens of
the type.
The semicells are somewhat variable in shape, triangular
and quadrangular forms being almost equally common. The
bluntness of the angles and the rather finer granulation are
the principal features of the variety.
We have observed one zygospore (PI. CXXVII, fig. 13)
which we figured in 1900 as that of St. punctulatum (Cf. W.
& G. S. West, 'Notes Alg II,' t, 412, f. 13).
Var. coronatum (Schmidle) nob.
St. alternans var. coronatum Schmidle, Weitr. Beitr. Algenfl. Rheineb. u.
Schwarzwald, 1895, p. 82, t. 1, f. 21; Schroder, Alg. Yersuchsteiche
Schles. Fischereiv. Trachenberg, 1897, p. 42.
Semicells with six rounded warts of small size in the
central part of the apex, one opposite each side and
each angle.
Length 28 /x ; breadth 22 jx.
Ireland. — Achill Island, Mayo ! Near Konndstone,
Galway !
Geogr. Distribution. — Germany.
This variety has the proportions and also the acutely
rounded and slightly inflated angles of St. 'punctulatum. The
apical warts are very distinctive.
Var. pygmamm (Breb.) nob. (PI. CXXVIII,
figs. 1,2.
Staurastrum pygmseum Breb. in Ralfs' Brit. Desm. 1848, p. 213, t. 35, f.
26 [description and figure very poor] ; Arch, in Pritcb. Int'us. 1861, p.
740; Rabenh. Flor. Europ. Alg. II J, 1868, p. 220; Wittr. Gotl. Ol.
s6tv. Alg. 1872, p. 53, t, 4, f . 10 ; Cooke, Brit, Desm. 1 887, p. 1 57, t. 54,
f. 1 [figures poor] ; Hanssc. Prodr. Algenfl. Bohm. 1888, p. 213 ; De
Toni, Syll. Alg. 1889, p. 1181 ; West, Alg. N. Wales, 1890, p. 293 ; Alg.
W. Ireland, 1892, p. 177 ; Alg. Engl. Lake Distr. 1892, p. 731 ; Liitkem.
Desm. Attersees, 1893, p. 565 ; Roy & Biss. Scott. Desm. 1894, p. 24
(sep.) ; Borg. Ferskv. Alg. Ostgronl. 1894, p. 26 ; Nordst. Index Desm.
1896, p. 214; W. & G. S. West, Alg. S. England, 1897, p. 494;
Schmidle, Lappmark Susswasseralgen, 1898, p. 56 ; W. & G. S. West,
Alga-fi. Yorks. 1901, p. 102 [in part] ; Borg. Freshw. Alg. Faroes,
1901, p. 230; W. & G. S. West, Alg. N. Ireland, 1902, p. 50; Hirn,
Desm. Finland, 1903, p. 23 ; Cushman in Rhodora, v, 1903, p. 222 ; in
Bull. Torr. Bot, Club, xxxii, 1905, p. 552 ; W. & G. S. West, Freshw.
Alg. Orkneys and Shetlands, 1905, p. 25 ; Borge, Beitriige Alg.
Schweden, i906, p. 45 ; Larsen, Ferskvandsalg. yest-Gronl. 1907, p.
353.
STAURA STRUM. 185
Cells with a slightly broader isthmus ; sides of
vertical view convex, straight, or slightly concave;
granules minute but acute.
Zygospore similar to that of type, but with slightly
longer spines.
Length 27-42 /x ; breadth 24-40 fx; breadth of
isthmus 9-18 /x.
England. — Cumberland ! Westmoreland ! Lan-
cashire ! W., N., and E. Yorks ! Surrey! Devon!
Cornwall !
Wales. — Fairly general in Carnarvonshire !
Scotland. — Sutherland ! Ross, Aberdeen, Kincar-
dine, Forfar, Perth ! (Boy Sf Bisnett.) Renfrew ! Wig-
town ! Orkneys and Shetlands !
Ireland. — Donegal ! Mayo (and Clare Island) !
Galway ! Kerry ! Down (up to 2000 ft.) !
Geogr. Distribution. — France. Germany. Austria
and Calicia. Portugal. Norway. Sweden. Bornholm.
Finland. Poland. N. Russia. Faeroes. Nova Zembla.
Spitsbergen. Greenland. Siberia. Sumatra. Mada-
gascar (var.). E. Africa. United States. Brazil.
Ecuador.
There is only one reliable distinction between this variety
and typical St. punctulatum, and that is in the nature of the
granulation. The granules of var. pygmseum are sharp,
whereas those of the type are flattened or rounded. The
isthmus of the cells is also, as a rule, a trifle broader. There
is no difference in the shape of the semicells, except in vertical
view, in which the sides are generally straight or slightly
convex. This difference is, however, of little importance, as
in many specimens the sides of the vertical view are concave
(consult PI. CXXVIII, fig. 2 6). Sometimes the cells are of
exactly the same outward form as those of typical St. punctu-
latum, but the granules are sharp (PI. CXXVIII, figs. 3 and 9).
Such forms belong to the var. pygmseum only by reason of
their sharp granules.
One form, which so far has only been observed from
Nacoogarrow Lough in Galway, has three series of slightly
larger granules forming a triangle on the apex of each
semicell ; length 48 /u; breadth 40 /a; breadth of isthmus 15 yu
(PI. CXXVIII, fig. 4) . It should be known as forma trilineata
18(3 BRITISH DESMIDIACEJl.
[= St. pygmaeum var. trilineatum West, 'Alg. W. Ireland/
1892, p. Ill, t. 23, f. 7].
"St. pygmpewm var. obtusum" Wille ('Ferskv. Alg. Xov.
Scnilj/ 1879, t. 13, f. 56) appears to be more closely related to
St. hexacerum (Ehrenb.) Wittr.
Var. striatum var. nov. (PI. CXXVIII, figs. 5, G.)
St. pygmseum as figured by W. & G. S. West, Notes Alg. II, 1900, p. 297,
t. 4J2, f. 12.
Semicells more distinctly rhomboid than in the type;
grannies most minute, fewer in number, and arranged
in somewhat distant series around the angles. Zygo-
spore exactly like that of var. pygmseum.
Length 29-3 ljx; breadth 29-3 i -5 /x; breadth of isth-
mus 9'5-11'5/x; diam. zygosp. without spines 36-37ja,
with spines about 67 ft.
England. — Cautley Spout, W. Yorks (with zygo-
spores) !
This is the most angular of any of the varieties of St.
punctulatum. It is well characterized by its somewhat distant
lines of granulations.
Two other forms of St. punctulatum, although not yet found
in the British Islands, require brief mention.
Forma klliptica Lewin, Span. Siisswasseralg. 1888, p. 9,
t. 1, f. 16. Semicells rather narrowly elliptic; length 24'6-
26;6ju; breadth 25-2-29-3 /*; breadth of isthmus &1-9S p.
Distrib. Spain. \Ve have seen nothing precisely like this
form, and think that it may possibly belong to St. alternans.
Arar. mukicatiformk Schmidle, Lappmark Siisswasseralgen,
1898, p. 57 [= St. muricatiforme Schmidle, Beitr. alp. Alg.
1895, t. 16, f. 14, 15 ; 1896, p. 162]. Cells with a less open
sinus; semicells elliptic-subsemicircular, granulation less dense
than in the type; angles in the vertical view more rounded.
Length 28-32 fi; breadth 23-30 /i. Schmidle has described a
" forma lapponica" of this variety which very nearly approaches
St. punctulatum f. elliptica Lewin. We have not observed
var. muricatiforme from any part of the British Islands, and
as originally described by Schmidle it appears to be known
only from the Tyrol.
STAURASTRUM. 187
37. Staura strum dispar Breb.
Staurastrum dispar Breb. Liste Desm. 1856, p. 144, t. 1, f. 27; Nordst.
Freshw. Alg. N. Zeal. 1888, p. 41 ; Eoy &Biss. Scott. Desm. 1893, p. 237.
Phycastrnm dispar (Breb.) Grogn. Plant, cryptogam.-cellul. du departm.
de Saone-et-Loire, Antun, 1863, p. 262.
Cells small, about as long as broad, very deeply
constricted, sinus open and acute-angled ; semicells
narrowly elliptic-rhomboid or elliptic fusiform, dorsal
margin somewhat more convex than the ventral margin,
lateral angles acutely rounded. Vertical view triangular,
angles subacute, those of one semicell alternating with
those of the other, sides convex. Cell-wall finely
granulate, granules arranged in concentric rings around
the angles.
Zygospore ?
Length 27'5 fx ; breadth 27-28 fi.
England. — Delamere, Cheshire (Roy). Leicester
(Roy). Enbridge Lake, Hants (Roy).
Wales. — Capel Curig, Carnarvonshire (Roy).
Scotland. — Sutherland, Ross, Aberdeen (zygospores
from Slewdrum), Kincardine, Forfar, Perth, Dumbarton
(Roy §• Bissett).
Geogr. Distribution. — France. Norway. Sweden.
New Zealand.
This species is recorded by Roy from several English
counties and one Welsh one, also by Roy and Bissett from
several Scottish counties; they also report the zygospores
from Slewdrum in Aberdeen, but give neither description nor
figure of them. We have not seen anything exactly corre-
sponding to Brebisson's original figure, but the following Irish
form should most probably be referred to St. dispar: —
Forma. (PI. CXXVII, fig-. 7.) Angles of semicells truncate-
emarginate; vertical view with slightly concave sides. Length
24M ; breadth 23-24/*; breadth of isthmus 6fi. Cf. W. & G. S.
West, 'Alg. N. Ireland/ 1902, p. 52, t, 2, f. 30.
Ireland. — Lough Gartan, Donegal.
O Q
>8. Staurastrum pilosellum sj). nor.
(PL CXXVIII, figs. 7, 8.)
Cells small, about 1| times as long as broad, deeply
constricted, sinus open and rectangular; semicells
188 BRITISH DESMIDlAOEdS.
broadly subrliomboid-elliptic, ventral margin somewhat
more convex than dorsal margin, lateral angles rounded.
Vertical view triangular, sides straight, angles broadly
rounded. Cell- wall granulate, granules with no definite
disposition, and those at the angles modified to form
minute spines, with a smooth area at the apex of each
semicell.
Zygospore globose, furnished with long spines, each
arising from a broadly conical base, and doubly furcate
at the apex.
Length 34-35^; breadth 27-29^; breadth of isth-
mus 10-12"5 fx; diam. zygosp. without spines 38 //,,
with spines 63-67 /x.
England. — Near St. Just, Cornwall (with zygo-
spores) !
This species appears to connect the St. punctulatum species-
group with those forms possessing minute spines such as occur
in Staurastrum hirsutum. The zygospore is exactly like those
of St. punctulatum var. pygmseum and St. punctulatum var.
striatum. The outward shape of the semicells and the form
of the vertical view are more or less in agreement with St.
punctulatum var. Kjellmani, but the character of the granu-
lation is quite different, especially in the development of the
minute spines at the angles.
39. Staurastrum granulosum (Ehrenb.) Ralfs.
(PI. CXXVTII, figs. 10-12.)
Desmidium granulosum Ehrenb. in Abh. Akad. Wiss. Berlin, 1S39, pp. 51,
56, t. 1, i.' 12.
Staurastrum granulosum (Ehrenb.) Ralfs, Brit. Desni. 1848, p. 217 ; Arch,
in Pritch. Infus. 1861, p. 738 ; Eabenh. Flor. Enrop. Alg. Ill, 1868, p.
206 ; De Toni, Syll. Alg. 1889, p. 1147 ; Gutw. Flor. glonow Galic. 1892,
p. 134 ; ? Eoy & Biss. Scott. Desm. 1893, p. 238 ; 1894, t. 3, f . 6 ; W. \
G. S. West, Alg. N. Ireland, 1902, p. 45, t. 2, f . 24 ; Notes Alg. Ill,
1903, p. 76; Scott. Freshw. Plankton, I. 1903. p. 529; Freshw. Alg.
Orkneys and Shetlands, 1905, p. 24 ; Comp. Study Plankton Irish Lakes,
1906, p. 86 ; Brit, Freshw. Phytoplankton, etc., 1909, p. 182.
St. lunatum Ralfs var. subarmatum W7. & G. S. West, New Brit. Freshw.
Alg. 1894, p. 10, t. 2, f. 47.
Cells small, about as long as broad, or sometimes a
little longer, deeply constricted, sinus open and sub-
rectangular, with an indistinctly acuminate apex ;
semicells more or less obsemicircular, apex convex,
STAURASTRUM. 189
lateral angles scarcely rounded, furnished with a
mucro (or very minute spine). Vertical view tri-
angular, median portion of sides refuse, angles acutely
rounded and mucronate. Cell-wall granulate ; granules
minute and arranged in concentric rings around the
angles, much reduced and scattered at each apex.
Zygospore globose, furnished with long slender
spines, which are slightly furcate at the apex.
Length 29-33 /a; breadth (with mucro) 27-33 /a;
breadth of isthmus 9-12*5 jx ; diam. zygosp. without
spines 32'5-34"5 p, with spines 62-65 /a; length of
spines 13"4-15'5 /x.
England. — Epping Forest, Essex ! Near Crowan,
Cornwall (with zygospores) !
Wales. — Capel Curig !, and Glyder Fawr (Roy),
Carnarvonshire.
Scotland. — Rhiconich, Sutherland ! Near Tain,
Ross ; Birsemore, Aberdeen ; Cammie, Heughhead
and Dalbrake (with zygospores) in Strachan, Kin-
cardine (Boy §' Bissett). Plankton of lakes in Lewis,
N. LTist, and Benbecula, Outer Hebrides ! Shetlands !
I Iceland. — Loughs Cloncarney and Grartan, Donegal !
Derryclare Lough, Gralway ! Plankton of Lough
Neagh ! Lough Fea and Plankton of L. Beg, Lon-
donderry !
Geogr. Distribution. — France. Germany. Galicia
in Austria.
St. granulosum is at once distinguished from all forms of
St. punctulatum by the more flattened apices of the semicells
and the mucronate angles. The cells are slightly variable in
external form, due largely to differences in proportionate
length and breadth.
We have previously mentioned (' Journ. Bot.' 1903, p. 76)
that the figure of the zygospore given by Roy and Bissett is
very indistinct and specifically unrecognizable.
Forma connexa. (PI. CXXVIII, fig. 13.)
Angles of semicells furnished with a pair of minute
spines in place of a single mucro.
190 BRITISH DESMIDIACE.E.
Length 28*5 ll ; breadth 25-27 ll ; breadth of isth-
mus 9*5 ll.
Scotland. — Plankton of Loch Asta, Shetlands !
Ireland. — Plankton of Lough Neagh ! Lough
Gartan, Donegal !
In this form some or all of the angles are furnished with
two minute spines. The form thus approaches the granulate
forms of St. Avicula, and to a smaller extent it resembles St.
denticulatum.
Var. acutum (Breb.) W. & G. S. West. (PL CXXVIII,
fig. 14.)
Staurastrum acutum Breb. Liste Desm. 1856, p. 143, t. 1, f. 26; Rabenh.
Flor. Europ. Alg. Ill, 1868, p. 202; Kirchn. Alg. Schles. 1878, p. 168;
Roy & Biss. Scott. Desm. 1893, p. 178.
St. granulosum var. acutum (Breb.) W. & G. S. West, Alg. N. Ireland,
1902, p. 45, t. 2, f. 25 ; Scott. Freshw. Plankton, I. 1903, p. 529 ; Brit.
Freshw. Phytoplankton, etc., 1909, p. 182.
Semicells elliptic-fusiform, dorsal and ventral margins
more equally convex ; sides of vertical view straight.
Length 29-30 ll ; breadth without mucro 28-31 ll,
with mucro 30-33 ll ; breadth of isthmus 11"5-12'5 ll.
Wales. — Capel Curig, Carnarvonshire (Eoy).
Scotland. — Ross, Inverness, Aberdeen, Kincardine,
Forfar, Perth (Boy Sf Bissett). Plankton of Loch
Mhor Bharabhais in Lewis, Outer Hebrides !
Ireland. — Near Grlenties, Donegal ! Plankton of
Louffli Neao-h ! Plankton of Lower River Bann, Lon-
donderry !
Geogr. Distribution. — France. Germany.
40. Staurastrum paxilliferum Gr. S. West.
(PL CXXVIII, fig. 15.)
Staurastrum paxilliferum G. S. West, Alga-fl. Cambr. 1899, p. 219, t. 396,
f . 8 ; W. & G. S. West, Alga-fl. Yorks. 1900, p. 100.
Cells somewhat small, a little longer than broad,
deeply constricted, sinus open and subrectangular,
with a submamillate apex ; semicells subelliptic, ven-
tral margin a little more convex than the dorsal
margin, angles subacute and furnished with a prominent
STAURASTRUM. 191
but rounded mucro. Vertical view triangular, with
straight sides and slightly rounded angles, each angle
furnished with a rather blunt mucro. Cell-wall
granulate, granules rather distant, those near the angles
more or less papilliform and arranged in three con-
centric series, granules away from the angles much
smaller, irregularly punctate between the granules,
apices of semicells smooth.
Zygospore unknown.
Length 36'5-40 {jl; breadth with mucros 32-38'5 /x;
breadth of isthmus 12*5-1 3* 5 /x.
England. — Pilmoor, N. Yorks ! TVicken Fen, Cam-
bridge !
This species should he compared with St. gramdosum
(Ehrenb.) Ralfs, with which it appears to have a very close
affinity. It should also he compared with St. brachyacanthum
Nordst.
41. Staurastrum inflatum sp. nov.
(PI. CXXVII, fig. 23.)
Staurastrum Kjellmani Wille var. rotundatum W. & G. S. West, New and
Int. Freslnv. Alg. 1896, p. 158, t. 4, f . 46 ; Alga-fl. Yorks. 1901, p. 102
" rotunduni"].
Cells rather small, about If longer than broad,
moderately constricted, sinus very widely open and
obtuse-angled: semicells obovate-subcircular, the widest
part being about two-thirds the height of the semi-
cell. Vertical view quadrate-circular. Cell-wall
densely granulate ; granules fairly large with no defi-
nite disposition, a little smaller towards the isthmus.
Zygospore unknown.
Length 43 /x ; breadth 25-26'5 fx ; breadth of isthmus
i o. k
loo /x.
Hab.— Ogden Clough, W. Yorks !
This species is at once distinguished from St. punctulatum
var. Kjellmani by its proportionately greater length, its more
open sinus, its much more rounded semicells, and its coarser
granulation.
The name " rotundatum " is already in use for an Indian
species of this genus.
EXPLANATION OF THE PLATES.
(194)
NOTE ON THE TEXT.
For reasons mentioned in the preceding volume (on p. 274)
several species of Cosmarium which were there figured are
described in the present volume.
EXPLANATION OF THE LETTERING.
a, a, a". Front view of cell or semicell.
b, b'. Vertical view.
c. Side view.
d. Basal view of semicell.
Plate 96
PLATE XCVI.
FIGS. PAGE
1-2. — Cosmarium Botrytis Menegh. x 500 . 1
3-4. — C. Botrytis var. jxixillosporum W. & Gr. S.
West. 3, x 400 ; 4, zygospore, x 520 . 4
5-6. — C. Botrytis. Two zygospores, x 520 . 2
7-15. — Germination of zygospore of C. Botrytis, x 190
(after De Bary) . . .3
;
PLVSTE XCVI.
Plate 97
PLATE XCVII.
FIGS.
1.
2-3.
4.
5.
6.
7-8.
9-11.
-Cosmarium Botrytis Menegh. var. subtumidum
Wittr. x 400 (after Wittrock)
-G. Botrytis var. twnidum Wolle. x 500
■C. Botrytis var. gemmiferum (Breb.) Nordst
x 500
-C. Botrytis var. mediolseve West, a and b, x 400
a', x 500
■C. Botrytis var. depressum W. & G. S. West
x 430
■C. controversion West. 7, x 520; 8, x 430
-C. tuberculatum Arch. 9 and 10, x 400 (after
Archer); 11, x 400
PAGE
4
5
6
6
7
9
42
PLATE XCV1J
Plate 98
PLATE XCVIII.
FIGS. PAGE
1—3. — CosmariuM ochthodes Nordst. 1, x 400 (after
Nordstedt) ; 2, x 520 ; 3, zygospore, x 520 . 10
4-6. — C. ochthodes var. amoebum West. 4 and 6, x
520 ; 5, a few of the depressed, lobed granules,
x 830 . . . 11
7. — C. ochthodes var. subcirculare Wille. x 480
(after Wille) . . . .12
8. — G. coronatum Cooke & Wills. x 400 (after
Cooke & Wills) . . .13
9-12. — G.crenatumll&Ws. 9 and 10, x 520; 11, zygo-
spore, x 400 (after Ralfs) ; 12, x 570 (after
Nordstedt) . . . .35
13-14. — C. crenatum forma Boldtiana (Gutw.) W. & G-. S.
West. 13, x 400 (after Ralfs) ; 14, x 500.
Fig-. 13 is only an outline, the surface marks
not being represented . . .37
15. — C. crenatum var. bicrenatum Nordst. x 570
(after Nordstedt) . . .38
PLATE AC" vii I.
f°00'-'-, 00 0 0.1
il
Plate 99
PLATE XCIX.
FIGS. PAGE
1-2. — Cosmarium conspersum Ralfs. 1, x 400 (after
Ealfs) ; 2, x 520 . . .13
3. — C. conspersum var. rotundatum Wittr. x 400
(after Wittroek) . . .16
4. — C. conspersum var. subrotundatum West, a, x
600; b, x 400 . . . .17
5-6. — C. conspersum var. latum (Breb.) W. & G. S. West.
5, x 400 (after Roy & Bissett) ; 6, x 500 . 15
7. — C. Logiense Biss. forma expansa W. & Gr. S. West.
x 400 (after Roy & Bissett) . .16
8. — C. margaritatum (Lund.) Roy & Biss. x 600 . 18
9. — C. margaritatum forma minor Bolclt. x 520 . 19
10. — G. margaritatum. x 520 . . .18
O O 2
c- _> ■'. a o a o o
° ° o o a "
O O t> O o
c o o o o o o o „ 0 o D "°oJ
oooonoo . 0 o '
>°° ° ° " ° ° = ° o c ; 9 OOOo^ o0(.
PLATE XCIA
O O » O C c ., .
. o o o o 0 „ -
,3 o = ° ° =000,
VCCOOOOCOOO-C^V
, c o c o o o c "
G.S^estdel.
Plate 100
PLATE C.
FIGS. PAGE
1. — Cosmarium margaritatum (Lund.) Roy & Biss.
forma subrotundata W. & Gr. S West. x 500 19
2. — C. Quadrnm var. sublatum (Nordst.) W. & Gr. S.
West, x 500. An Australian specimeu figured
here for comparison with C. Quadrum, of which
it is probably but a variety . .21
3-6. — C. Quadrum Lund. 3, x 400 (after Lundell) ; 4,
x 500 ; 5 and 6, x 520 . . .20
7_8._ (7. Pseudobroomei Wolle. x 520 . . 22
9. — C. Pseudohroomei var. convexum W. & Gr. S. West.
x 400 . 23
10. — G. Subbroomei Schmidle. a, x 420; b, x 500 (after
Schmidle) . . . .23
11 _C. Subbroomei forma. x 520 . . 24
12.— C. Broom ei Ralfs. x 400 (after Ralfs) . 24
PLATE C.
G.S.-VVest da.
Plate 101
PLATE 01.
FIGS. PAGE
1-8. — Cosmarium biretum Breb. 1 and 2, x 400 (after
Ealfs) ; 3-8, x 520, various forms from Welsh
Harp, Middlesex . . .25
9. — C. biretum forma triquetra Breb. x 330 (after
Brebisson). Outline of basal view of semicell 28
10-15. — C. biretum var. trigibberum Nordst. 10, x 400
(after Nordstedt) ; 1 1, x 400 (after Nordstedt) ;
12-15, various forms, x 520; fig. 11 represents
the form described by Nordstedt as "forma
supernumeraria" . . .28
PLATE CI.
G SWesi del
Plate 102
FIGS
1-
-4
5-
-6
7-
-9
[0-12
PLATE CII.
PAGE
-Cosmarium amoenum Ralfs. 1 and 3, x 500 ;
2, x 520 ; 4, x 400 . . .29
-G. amoenum var. mediolxve Nordst. 5, x 625 ;
6, x 570 (after Nordstedt) . .31
-C. pseudamcenum Wille. 7, x 480 (after Wille) ;
8, x 600 (after Joshua) ; 9, 500 . .31
-C '. pseudamcenum var. basilars JSTordst. 10, x
570 (after Nordstedt) ; 11, x 520; 12, x 500 32
13—15. — G. annulatum (Nag.) De Bary. 13, x 600
(after Nageli) ; 14, three individuals forming
a short chain, x 400; 15, x 500 . . 39
16-18. — C. annulatum var. elegants Nordst. 16, x 570
(after Nordstedt) ; 17, x 400; 18 x 500 . 40
19. — C. elegantissimum Lund. x 400 (after Lundell) 40
20-21. — G. elegantissimum forma minor West. 20, x
400 '; 21, x 500 . . .41
22. — C. punctulatum Breb. Zygospore, x 500.
[Consult Vol. Ill, page 207.]
PLATE CII.
Plate 103
PLATE CIII.
FIGS. I'.WE
1. — Cosmarium basilicitm G. S. West, x 520 . 4-1
2. — C. prominulum Eacib. x about 1200 (after
Raciborskij . . . 4t>
8. — G. prominulum var. subundulatum W. A: G. S.
West, x 520 . . .47
4. — G. Portiamim Arch. Zygospore, x 390 (after
De Bary). [Consult Vol. Ill, page 166].
5-6. — G. Gayanum De Toni. 5, x 400; 6, zygo-
spore, x 200 (after Gay) . . 7
7. — C. Pseudobroomei Wolle. Zygospore, x 400
(after Half's) . . . .22
8. — C. Botrytis Menegh. var. e marginatum Hansg.
x 400 (after Hansgirg) . . .6
9.— G. ammnum Breb. x 500. [Consult PI. CII,
figs. 1-4] . . . .29
10.— C. Wittrockii Lund. x 520. [Consult PI,
LXXVIII, fig. 19, and page 179 in Vol. III].
11-13. — G. taxichondrum Lund. 11, x 400 (after
Lundell) ; 12 and 13, x 520 . . 4.~>
14. — Xanthidium subhastiferum West var. Murrayi
W. & G. S West. A form in which one
semicell is furnished with a pair of accessory
spines, x 430 .... 57
PLATE Cm.
■S.West cUl
Plate 104
PLATE CIV.
FIGS. PAGE
1—5. — Xanthidium armatum (Breb.) Kabenh. 1 and '2,
front views, x 500 ; S, vertical view, x 500 ;
4, side view of semicell, x 430; 5, zygospore,
x 430 . . . . .51
PLATE CIV
GSWest Id
Plate 105
/
PLATE CV.
FIGS. lAGE
1-2. — Xanthidium armatum var. fissum Nordstedt. x
500 . . . . .54
3-4. — X. armatum var. irregularius W est. 3, x 500;
4, x 400 .... 55
5. — A carious form of X. armatum, which may be a
reduction form, or one of the earliest stages in
the development from the zygospore, x 4(H) . 54
PLATE CV
>>
jfc
/
K^ ?«
<£
3
1 ^ V"
G.S.Krcst oLJ
.
Plate 106
PLATE CVI.
FIGS.
1-4. — Xantltidium armatum var. cervicorne W. & G-. S
West. 1 , x 430 ; 2-4, single spines, x 520
5-9.— X subhastiferum West. 5, x 400 ; 6, x 430
7-9, three specimens showing irregularities
which sometimes occur. 7 and 9, x 500
8, x 430
10— 1 J . — X. subhastiferum var. Murrayi W. & G. S
West. x 430
V WE
55
PLATE CVI
G-S.We.sf dbd
Plate 107
PLATE CVII.
FIGS.
1 , after
1-2. — Xanthidium tetracentrotum Wolle.
Wolle ( x 500) ; 2, x 520
'3. — X. tetracentrotum forma protuberans W. it G. S.
West, x 520 .
4. — X. tetracentrotum, var. auadricornutum (Roy h
Biss.) W. & G. S. West. x 400 (after Roy
Ik, Bissett)
5-0. — X. controversum W. & (i. S. West, 5, x 525
6, x 520
7-8. — X. controversum var. planctonicum W. & G. S
West. x 520 .
9-10. — X. subhastiferum var. Murrai/i forma triquetra
W. & (i.'s. West, x 430'
TAGE
58
59
59
59
60
57
PLATE CVn
3 We si del
Plate 108
PLATE CVIII.
FIGS. PAGE
1-4. — Xanthidium Smithii Arch. 1-8, x 500; 4, x
460 . . . . .61
5.— X. Smithii var. majus (Half's) W. & G. S. West,
x 500 .' . . .62
6.— X Smithii var. collum West. x 400 . 68
7-18. — X antilopseum (Breb.) Kiitz. 7, x 520; 8, x
400 ; 9, specimen showing chloroplasts, x
500 ; 10-17, different dispositions of the scro-
bic illations situated in the central thickened
area of the semicells, x 520 ; 18, zygospore,
x 400 ... 63
19. — X. antilopseum var. polymazwm Nordst. x 400
(after Nordstedt) . . .67
PLATE CVDT
G S.West del.
Plate 109
PLATE CTX.
FIGS. PAGH
1. — Xanthidium antilopssum (Breb.) Kiitz. var. trique-
trum Lund. x 430 . . .66
2. — X. antilopssum var. polymazum Nordst. forma.
x 520 . . . . .67
3. — X. antilopssum var. Iseve Schmidle. x 520 . 68
4. — X. antilopssum var. Iseve forma irregularis W. iv
G. S. West, x 520 . . .68
5. — X. antilopssum var. oligacanthum Schmidle. x
about 500 (after Schmidle) . . . 68
6. — X. antilopssum var. oligacanthum Schmidle forma.
x 520 . . . . .69
7. — X. antilopsenm var. hehridarum W. & G. S. "\\ est.
x 520 ..... 69
PLATE CIX
G.SWfsh rW
Plate 110
PLATE CX.
FIGS. _ PAGB
1-2. — Xanthidium antilopa urn (Breb.) Kiitz. var. hebri-
darum W. & G. S. West. 1, x 500 ; 2, x 520 69
3-7. — X. antilopseum var. de-pawperatum W. & Gr. S.
West, 3-5, x 520 ; 0 and 7, x 480
8-9.— X cristatum Breb. x 520 .
10. — X. cristatum forma angulata West. x
11. — X. cristatum var. leiodermum (Roy
Turner. x 520 .
12. — X. cristatum var. spinuliferum West.
.
70
70
400
7:2
& Biss.)
.
72
x 400 .
73
PLATE CX
G.S.Wesb del.
Plate 11]
PLATE CXI.
FIGS. PAGE
1. — Xanthidium cristatum Breb. Zygospore, from a
poor figure by Reinsch, x 360 . .71
2-4. — X. cristatum var. uncinatum Breb. 2, x about
360 (after Ralfs) ; 3, x 500 (after Turner) ;
4, x 360 (after Hirn) . . .73
5. — X. cristatum var. Delpontei Roy & Biss. x 416
(after Delponte) . . .74
6-8. — X. fasciculatum Ehrenb. 6, x 400 (after Ralfs) ;
7, x 400 ; 8, x 400 (after Nordstedt) . 75
9. — X. fasciculatum var. Oronense W. & G. S. West.
x 520 . . . . 77
10. — X. Smithii Arch. Zygospore, x 400 (after Roy
& Bissett) . ' . . .61
PL/YTE CXI
G SWest del
Plate 112
PLATE CXII.
FIGS. PAGE
1 and 3. — Xanthidium Breblssonii Ralfs. 1, x about
360 (after Ralfs) ; 3, x 460 . 77
2 and 4. — X. Bn'bissonii var. varians Ralfs. x 400
(after Ralfs) . . . .78
5—9. — X. aculeatum ELrenb. 5—7, x 400 (after
Ralfs) ; 8, x 500 ; 9, zygospore, x 400
(after Lnndell) . . .78
10. — X. concinnum Archer, x 740 . . 86
11-12. — X. concinnum var. Boldtianum West. x 400 87
PLATE CXlf
G.SVesl del
Plate 113
PLATE CXII1.
FIGS. PAGE
1-7. — Xanthidium variabile (Nordst.) W. & G. S.
West. 1 and 2, x 570 (after Nordstedt) ;
3-6, x 520; 7, zygospore, x 520. . 81
8. — X. Robinsonianum Arch, x 520 . . 83
9. — X. apiculiferum West, x 625 . . 85
10-12.— X Orcadense W. & G. S. West, x 520 . 84
13-15. — ArtJirodesmus Incus (Breb.) Hass. x 520 . 90
16-19. — A. Incus forma minor. 16, x 400; 17, x 520;
18, x 400; 19, zygospore, x 520 . ' .92
20-23.— .4. Incus var. indentatus W. & G. S. West. 20,
x 520; 21 and 22, x 500; 23, x 520 . 94
24. — A. Incus var. indentatus forma scrobicidata. x
520 . . . . .94
ft. ate cxnr
G SWe3i del
Plate 114
PLATE CXIV.
FIGS. PAGE
1. — Arthrodesmus Incus forma perforata Sclimidle.
x 500 . . . .93
2_4._ A Incus var. Balfsii W. & G. S. West, 2 and
3, x 400 (after Ralfs; 3, zygospore); 4, x
400 . . . . • 95
5. — A. Incus var. Ralfsii forma latiuscula W. &
G. S. West, x 500 . . .96
In fig. 5 c the delicate furcate processes are
gelatinous rods secreted by the protoplast,
each one being situated over one of the prin-
cipal pores in the cell-wall.
6. — A. Incus var. Ralfsii forma subheacagonaW. &
G. S. West, x 520 . . .96
7. — A. Incus var. subquadratus W. & G. S. West.
x 520 . .97
8. — A. Incus var. longtspinus Eichler & Racib. x
520 . . . . . 96
9-10.— 4. Incus var. validux W. & G. S. West, x
520 . . . . . 96
11-13. — A. triangularis Lagerh. 11, x about 400
(after Lagerheim) ; 12 and 13, x 520 . 97
14-15. — A. triangularis var. inflatus W. & G. S. West.
x 520 . . . .99
16. — A. triangularis var. inflatus forma robusta W. &
G. S. West, x 400 . .99
17. — A. triangularis. A form from the plankton
with the cell twisted at the isthmus, x 500 . 98
PLATE CXLY
S West A^l
Plate 115
PLATE CXV.
FIGS. PAGB
1-3. — Arthrodesmus triangularis var. subtriangularis
(Borge) W. & G. S. West, x 520 _. 100
4. — A. triangularis var. subtriangidaris forma tri-
quetra W. & G. S. West, x 500 ._ _. 100
5. — A form of A. triangularis var. subtriangidaris
in which one semicell is biradiate and the
other triradiate . . .101
6-7.— .4. quiriferus W. & G. S. West. x 520 . 101
8-11.— J. crassus W. & G. S. West. 8, x 520; 9, 10,
and Ha, x 500; 11a', x 520 . . 102
12-14.— X controversy W. & G. S. West. 12 and 14,
x 520; 13, x 400 . . . 103
15-16:— A. phimus Turn. 15, x 500; 16, x 520 . 104
17.-^4. phimus var. occidentalis W. & G. S. West.
x 520 . 105
18. — A. quiriferus forma compaeta W. & G. S. West.
x 520 . . . 101
PLATE CXY
3
U
0
u
12..
w.
o
17
15.
16.
G 5. West del
Plate 116
PLATE CXVI.
FIGS. PAGE
1-2. — Arthrodesmus Bulnheimii Racib. 1, X 430;
2, x 460 . . . 105
3. — A. Bulnheimii var. subincus W. & Gr. S. West.
x 520 . . . . 105
4-13. — A. convergens Ehrenb. 4, x 360 (after Ralfs) ;
5, x 520; "6, large form, x 500; 7 and 8,
forms in which one semicell is destitute of
the spines, x 520 ; 9, division of preceding
form, showing the acquirement of fully deve-
loped spines by the new half-cells, x 520 ;
10, form produced by rapid division and
entirely destitute of spines, x 520; 11, divi-
sion of such a form showing fully developed
spines re-acquired by the new semicells, x
520; 12, x 520; 13, zygospore, x 520 ' .106
14.— A. subulatus Kiitz. x 520 . .109
PLATE CXVI
G.S.Wesl del.
Plate 117
Plate 118
PLATE CXVIII.
FIGS. TAGE
1—3. — Xanthidium Robinsonianum Arch. x 500.
These drawings are from specimens distri-
buted in Wittr. & Nordst. Alg. Exsic. no. 550,
and were collected in Derrytrasna Bog,
Armagh, Ireland . . .83
4-6. — Staurastrum Meriani Reinsch. 4, x 400; 5
and 6, x 500 . . . . 122
7 _ St. Capitulum Breb. x 520 . . 124
8. — St. Capitulum var. xpitsbergense (Nordst.)
Cooke. x 400 (after Nordstedt) . .126
9. — St. Capitulum var. himidiusculum (Nordst.)
W. & G-. S. West, x 400 (after Nordstedt) 126
10.— St. Capitulum Breb. x 460 . . 124
11-13.— iSfi. pileolatum Breb. 11, x 500; 12 and 13,
x 520 . . . 127
14. — St. pileolatum var. cristatum Liitkem. x 500 129
15. — St. rhabdophorum Nordst. x 570 (after Nord-
stedt) . . • -129
16-20.— St. muticum Breb. 16-19, x 520; 20, zygo-
spore, x 400 (after Ralfs) . . 133
PLATE CXVTH
10.
13.
GS.Vest del
Plate 119
PLATE CXIX.
PIGS. PAGE
1. — Stau I'd. strum muticum Breb. forma minor
Rabenh. x 520 . . . 13a
2. — St. minutissimum Reinsch. x 1250 (after
Reinsch) .... 130
3. — St. minutissimum var. convexum W. & (jr. S.
West. x 1250 (after Reinsch) . . 131
4. — St. minutissimum var. convexum forma [= forma
tetragonaNordst.']. x 570 (after Nordstedt) 131
5. — St. minutissimum var. convexum forma [="forma
trigona minor " Wille]. x 400 (after Wille) .
Fig. 5 a represents two cells resulting- from
division; tliey are in a slightly oblique position.
Fig. 5«' is also in an oblique position . 131
6. — St. minutissimum var. constrictum West, x 625 132
7.— St. ellipticum West, x 520 . . 138
8. — St. coarctatum Breb. x 420 (after Brebisson).
Front view only . . .139
9-10. — St. coarctatum var. subcurtum Nbrdst. 9, x 400
(after Nordstedt) ; 10, smaller form, x 400 . 139
11-13. — St. grandeBuhih. x 520 . . . 140
plate exrx
Plate 120
PLATE CXX.
FIGS. PAGE
1. — Zygospore of ' Statirastrumgrande. x about 360
(after Cushman) . Cushman gives the magnifi-
cation of this figure as 450 diameters, but this
is incorrect according to his own measurements 140
2-3. — St. grande var. parvum W. cS^ Gr. 8. West. 2, x
400; 3, x 500 . . . . 141
4-6. — St. Bieneanum Rabenli. 4, x 500; 5 and 6, zygo-
spores, x 520. The minute punctulations are
not indicated on the empty semicells of fisrs. 5
and 6 . . '. . . 135
7. — St. Bieneanum, forma spetsbergensis JSTordst. x
400 (after Nordsteclt) . ' . .137
8. — St. Bieneanum var. ellipticum Wille. x 330
(after Wille) .... 137
9-13. — St. aversum Lund. 9, x 400 (after Lundell) ;
10, small form, x 500; 11-13, larger forms,
x 500 . . . . .144
PLATE CXI
G.S.Wesl del.
Plate 121
PLATE CXXr.
FIGS. PAOI
1-2. — Staurastrum conspicuum W. & G. S. West, x 520 143
3-6. — St. lanceolatum Arch. 3 and 4, x 400 (after
Archer) ; 5 and 6, x 500. 4 and 6, zygospores 149
7. — St. lauceoldtum var. compressum W. & (r. S. West.
x 520 . . . . .150
8-9. — St. parhyrhynchum Nordst. b, x 400 (after
Nordstedt); 9.. x 520 . . . 151
G.3.Vest del
Plate 122
PLATE CXXII.
FIGS. 1'AiiE
1-5. — Staurastrum tumidum Breb. All x 400. 1—3,
triangular forms ; 4, vertical view of quadran-
gular form ; 5, zygospore (after Lundell) . 142
6. — St. Clepsydra Nordst. x 400 (after Nordstedt) 152
7-10. — St. Clepsydra var. sibericum (Borge) W. & G. S.
West, ' 7, x about 330 (after Borge) ; 8-10, x
520. 7 and 8, forma ovalis ; 9 and 10, forma
trigona . . . .152
PLATE CXXI1
G.SVest del
Plate 123
PLATE CXXIII.
FIGS. PAGE
1-3. — Staurastrum brevispinum Breb. 1, x 400 (after
Ralfs); 2, x 400; 3, x 520 . ^ . 145
4. — St. brevispinum forma ■major W. & Gr. S. West.
x 500 . . . . .147
5. — St. brevispinum var. altum W. & Gr. S. West. x
520 . . . . .148
6. — St. brevispinum var. Boldtii Lagerh. forma retusa
(Borge) W. & G. S. West, x 430 . .148
7. — St. brevispinum var. obversum W. & Gr. S. West.
x 520 . . . . • 148
8-9.— St. angulatum West. x 400 . ^ . 154
10. — St. angulatum var. planctonicum W. & G-. S. West.
x 520 . . . . -154
PLATE CXXIii
SVesl del
Plate 124
PLATE CXXIY.
FIGS. PAGE
1. — Staurastrum subpt/gmaeum West var. subaiigu-
latumW.&G.S.West. x 520 . . 163
2-4.— St. inelegans W. & G. S. West, x 520 . 153
5-9. — St. orbicular e var. hiliemicumW '. & G. S. West.
5, x 400 ; 6, x 520 ; 7-9, x 640 (after Nord-
stedt) . . . .156
10—11.' — St. orbiculare Ralfs. 10, x 400 (after Roy and
Bissett) ; 11, x 520 . . . 155
12-16.— St. orbiculare var. Lialfsii W. & G. S. West. 12,
x 400 (after Ralfs) ; 13 and 14, x 520 ; 15,
x 400; 16, zygospore, x 400 . .156
Pig. 14 is "forma major" . . . 157
17-19. — St. orbiculare var. depressum Roy & Biss. 17,
x 460 ; 18, x 600 (after Roy and Bissett) j
19, x 520 .... 158
PLATE CXXIN
Plate 125
PLATE CXXV.
FIGS.
1-2. — Staurastrum orbiculare Ralfs var. externum
Nordst. x 520
3-5. — St. suborbiculare W. & G-. S. West. 3 and 4,
x 400 ; 5, zygospore, x 400 (after Roy &
Bissett)
6-7. — St. retusum Turner. x 520
8. — St. retusum var. boreale W. & (1. S. West. >
400 .
9._ St. tortum (Lagerh. & Nordst.) W. & G. 8
West, x 800 (after Nordstedt) .
10. — St. tortum forma trigone, G. S. West. x 430
11-12. — St. cosmarioides Nordst. 11, x 400 (after
Nordstedt) ; 12, x 400 .
13-16. — St. subpygmseumMVest. 13, 14, and 16, x 520
15, x 400
17-18. — St. corniculatum Lund. 17, small forms, x 430
18, x 400 (after Lundell)
19-22. — St. corniculatum var. spinigerum West. 19, x
400; 20-22, x 500
PAGE
158
159
160
160
161
162
161
162
163
164
PLATE CXKV
5 West del
Plate 126
PLATE CXXVI.
FIGS.
1-2. — Stawrastrum trachytiihophorwm W. >.S.West
x 520. 2, zygospore
3. — St. rugulosum Breb. x 400 (after Kali's)
4. — St. botrophilum Wolle. x 520
5-6. — St. turgescens Be Not. x 520
7.— St. Donardense W. & Q. S. West. x 520
8-9. — St. altemans Breb. 8, a typical specimen, x
520; 9, x 400 (after the poor figure given
by Halt's)
Fig. 9 a is only the outline of the front
view ; both 9 a and 9 d are poor figures and
scarcely represent the species.
10-15.— St. dilatatum Ehrenb. 10, x 400 (after the
very poor figure given by Ralfs) ; 11 and 13,
x 520; 12 x 550; 14, x 840; 15, supposed
zygospore, x 400 (after Roy and Bissett)
Fio-. 10 a is only the outline of the front
view, but neither 10 a nor 10 d are very good,
are typical examples of St.
16
Figs. 11-1.4
dilatntwni.
-St. disputatui
,n W.& G.S. West, x about 540
(after Baciborski). This figure is imperfect
as the granulation is insufficiently depicted .
17. — St. disputatwm var. extensivm (Borge) W. & Gr. S.
West. x 740 (after Borge)
18. — St. dilatatum var. hibernicum W. & (x. S.
West. x 520
19. — St. disputatnm var. sinense (Liitkem.) W. A:
G. S. West. x 600 (after Lutkemiiller)
PAGE
165
178
160
167
169
170
172
176
177
17:.
176
PLATE CXKVl
18.
G S.Wesl del
Plate 127
PLATE CXXVII.
FIGS. PAGE
1-5. — Staurastrum striolatum (Nag.) Arch.
I, x 570 (after Nordstedt) ; 2, x
500 ; 3-5, zygospores, x 500. Fig.
4 is the side view of the zygospore,
and fig. 5 shows a zygospore in an
oblique position . . . 177
6. — St. striolatum var. divergens W. & Gr. S.
West, x 520 . . . 178
7.— St. dispar Breb. forma, x 520 . 187
8-11. — St. pwictulatum Breb. 8-10, x 520;
II, x 500 . . 179
12. — St. punctidatum forma minor, x 460 . 181
13. — Zygospore of St. punctulatum var. Kjell-
mani Wille. x 520 . . 182
14. — Zygospore of St. punctidatum. x 500 181
15. — St. punctidatum var. subproductum W.
& G. S. West, x 520 . .182
16. — St. altemans var. pulchrum Wille. x
400 (after Wille). In fig. 16a the
lower semicell is outlined in dots to
give a general idea of the form of the
sinus ....
17-19, 21, 22. — St. punctidatum var. Kjellmani Wille.
17, x 400 (after Wille) ; 18, x 330
(after Wille); 19, x 520; 21, x
520; 22, x 400 . . . 182
23.— St. inflatum W. & G. S. West. x 520 191
24. — St. turgescens De Not. var. arcticum
Wille. x 400 (after Wille) . 169
172
PLATE CXXVTT
G S West del
Plate 128
PLATE CXXVIIL
FIGS.
1-3. — Staurastrum punctulatum var. pygmamm (Breb.)
W. & G. S. West. 1, x 400 (after Wille)
2, x 400; 3, x 500
4. — St. punctulatum var. pygmseum forma trilineata
West. x 400 .
5-6. — St. punctulatum var. striatum W. & G. S. West
x 520. 6, zygospore
7-8.— St. pilosellum W. & G. S. West, x 520. 8
zygospore
9. — Zygospore of St. punctulatum var. pygmseum
x 400
10-12.— fl*. granulosum (Ehrenb.) Ralfs. x 520. 12
zygospore
13. — St. granulosum forma connexa. x 520
14. — St. granulosum var. acutum (Breb.) W. & G. S
West, x 520
15. — St. paxilliferum G. S. West. x 520
16. — Arthrodesmus triangularis Lagerli. forma tri-
guetra W. & G. S. West, x 520 .
PAGE
184
185
186
187
184
188
189
190
190
99
PLATE CXKVUL
GSWesUe
RAY SOCIETY
INSTITUTED 1844
FOR THE PUBLICATION OF WORKS OX
NATURAL HISTORY
ANNUAL SUBSCRIPTION ONE GUINEA
OFFICERS AND COUNCIL.
1911-12.
The Et. Hon. LOED AVEBUEY, D.C.L., LL.D., Pres.Soc.Ant.,
For.Sec.E.A., F.E.S., F.L.S., etc.
llkc-^prc-aiucnts.
S. F. HAEMEE, M.A., Sc.D., F.E.S., V.P.Z.S.
P.. DAYDON JACKSON, Ph.D., F.L.S.
E. F. SCHAEFF, Ph.D., B.Sc, F.L.S., F.Z.S.
Council.
Eobert Adkin, F.E.S.
G. T. Bethune-Baker, F.L.S., F.E.S.
Eev. C. E. N. Burrows, F.E.S.
T. A. Chapman, M.D., F.Z.S., F.E.S.
Sir Charles Eliot, K.C.M.G., C.B.
Eev. Alfred Fuller, M.A., F.E.S.
A. E. Gibbs, F.L.S., F.E.S., F.E.H.S.
Albert H. Jones, Treas.E.S.
G. B. Longstaff, M.D., F.E.S.
J. W. S. Meiklejohn, M.D., F.L.S.
A. D. Michael, F.L.S., F.Z.S.
James Murray, F.Z.S., F.E.M.S.
Charles Oldham, F.Z.S., M.B.O.U.
C. D. Soar, F.L.S., F.E.M.S.
treasurer.
F. DuCANE GODMAN, D.C.L., F.E.S., F.L.S., F.G.S., F.Z.S., F.E.S.
^cmtary.
JOHN HOPKINSON, F.L.S., F.G.S., F.Z.S., Assoc.Inst.C.E. :
^Veetwood, Watford.
RECENTLY ISSUED AND FORTHCOMING
MONOGRAPHS.
For the Sixty-first Year, 1904.
82. A Monograph of the British Desmidiacea?. By W. and
G. S. West. Vol. I. xxxvi + 224 + 64 pp., 32 plates.
8vo. 1904.
83. British Tunicata. By tlie late Joshua Alder and the
late Albany Hancock. Edited by John Hopkinson. Vol. I.
With a History of the Work by Canon A. M. Norman.
xvi + 146 + 42 pp., 20 plates, and frontispiece. 8vo.
1905.
For the Sixty-second Year, 1905.
84. A Monograph of the British Desmidiaceae. By W. and
G. S. West. Vol. II. x + 206 + 64 pp., 32 plates. 8yo.
1905.
85. The British Freshwater Rhizopoda and Heliozoa. By
James Cash, assisted by John Hopkinson. Vol. I. The
Rhizopoda, Part I. x + 150 + 32 pp., 16 plates. 8yo. 1905.
For the Sixty-third Year, 1906.
86. The British Tunicata. By the late Joshua Alder and the
late Albany Hancock. Edited by John Hopkinson. Vol.
II. xxviii + 164 + 62 pp., 30 plates (xxi-1), and frontis-
piece. 8yo. 1907.
For the Sixty-fourth Year, 1907.
87. The British Annelids. By Prof. W. C. McIntosh. Vol.
II, Part 1. Polychasta (continued), viii + 232 + 46 pp.,
22 plates (xliii-1, lvii-lxx). Folio. 1908.
For the Sixty-fifth Year, 1908.
88. A Monograph of the British Desmidiaceae. By W. and
G. S. West. Vol. III. xvi + 274 + 62 pp., 31 plates (lxv-
xcv). 8vo. 1908.
89. The British Freshwater Rhizopoda and Heliozoa. By
the late James Cash, assisted by John Hopkinson. Vol. II.
The Rhizopoda, Part II. xviii + 168 + 32 pp., 16 plates
(xvii-xxxii), and frontispiece. 8vo. 190!>.
4 PUBLICATIONS OF THE RAY SOCIETY.
For the Sixty-sixth Year, 1909.
90. The British Nudibranchiate Moll u sea. By the late
Joshua Alder and the late Albany Hancock. Part 8 (supple-
mentary). Text by Sir Chables Eliot, viii +198+18 pp.,
8 plates. Folio. 1910.
For the Sixty-seventh Year, 1910.
91. The British Annelids. By Prof. W. C. McIntostt. Vol.
II, Part 2. Polycha3ta. Syllidae to Ariciidae. vii + 292
(233-524) + 46 pp., 23 plates (li-lvi, lxxi-lxxxvii). Folio.
1910.
For the Sixty-eighth Year, 1911.
92. A Monograph of the British Desmidiaceae. By W. West
and Prof. G. S. West. Vol. IV. xiv + 194 + 66 pp., 33
plates (xcvi-cxxviii). 8vo. 1912.
93. The British Tunicata. By the late Joshua Alder and
the late Albany Hancock. Edited by John Hopkinson. Vol.
III. xii + 114 + 34 pp., 16 plates (li-lxvi). 8vo. 1912.
In Course of Publication.
The British Desmidiacea?. By W. West and Prof. G. S.
West.
The British Freshwater Rhizopoda and Heliozoa. By
the late James Cash and (after Vol. II) G. H. Wailes.
The British Marine Annelids. By Prof. W. C. McIntosh.
Preparing for Publication.
A Bibliography of the Tunicata. By John Hopkinson.
For 1912.
The British Parasitic Copepoda. By Dr. Thomas Scott and
Andrew Scott. Arol. I (Copepoda parasitic on Fishes, Part I)
for 1912.
The British Centipedes and Millepedes. By W. M. Webb.
The British CharaceaB. By Henry and James Groves.
The British Earthworms. By the Rev. Hilderic Friend.
The British Hydrachnida?. By C. D. Soar and W.
Williamson.
The British Ixodoidea. By W. F. Cooper and L. E. Robinson.
The Earwigs of the World. By Dr. Malcolm Burr.
December, 1911.
>
H
\
«
\
i — i
nA
o
W
H
<
^
1
«
Q
d)
N
a}
^
CO
■
^
\ 1
O
jS
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11